Diploma In Board Review Internal Medicine

Mitral Stenosis (MS)

Introduction: What Is Mitral Stenosis?

Mitral stenosis refers to a narrowing of the mitral valve orifice, which obstructs the flow of blood from the left atrium to the left ventricle during diastole. The most common cause worldwide is rheumatic heart disease, often following untreated group A streptococcal pharyngitis.

This condition remains a high-yield topic for USMLE Step 2 CK, especially in patients with a history of childhood rheumatic fever or those from regions with limited access to medical care.

Pathophysiology: Understanding the Hemodynamics

• Narrow mitral valve limits diastolic filling of the left ventricle

• This causes a pressure buildup in the left atrium, leading to:

  • Left atrial enlargement

  • Pulmonary venous hypertension → congestion and edema

  • Reactive pulmonary arterial hypertension → right ventricular overload

• In the long term, this can lead to:

  • Atrial fibrillation (AF) due to atrial stretch

  • Right-sided heart failure: ascites, hepatomegaly, peripheral edema

Clinical Presentation

Patients often present with:

• Exertional dyspnea (most common initial symptom)

• Orthopnea and paroxysmal nocturnal dyspnea (PND)

• Hemoptysis (from ruptured pulmonary veins or bronchial vein engorgement)

• Fatigue due to reduced cardiac output

• Palpitations due to AF

• Advanced cases:

  • Peripheral edema, ascites, hepatomegaly (right heart failure signs)

Physical Examination Findings

Hallmark murmur:

• Low-pitched, mid-diastolic rumbling murmur heard best at the apex

• Use bell of stethoscope in left lateral decubitus position

Opening snap:

• Occurs just after S2, caused by stiff mitral valve leaflets

• Shorter S2–OS interval = more severe stenosis

Other findings:

• Loud P2: from pulmonary hypertension

• Right ventricular heave: from RV hypertrophy

Investigations

1. Echocardiography (Diagnostic test of choice):

• Thickened mitral valve leaflets

• Reduced valve area:

  • Mild: >1.5 cm²

  • Moderate: 1.0–1.5 cm²

  • Severe: <1.0 cm²

• Elevated transmitral gradients

• Assess for left atrial thrombus, mitral regurgitation, or valve calcification

2. ECG:

• Atrial fibrillation

• Left atrial enlargement (e.g., broad notched P waves in lead II)

3. Chest X-ray:

• Straightening of the left heart border

• Pulmonary vascular congestion

• Double density sign (left atrial enlargement)

• Possible mitral valve calcification

Management of Mitral Stenosis

Asymptomatic patients:

• Observation and monitoring with periodic echocardiography

Symptomatic patients:

• Diuretics: to reduce pulmonary congestion

• Beta-blockers or non-dihydropyridine CCBs: to slow ventricular rate in AF

• Anticoagulation (e.g., warfarin):

  • If AF, left atrial thrombus, or prior embolic event

Definitive treatment:

• Percutaneous Balloon Mitral Valvotomy (PBMV):

  • First-line if valves are pliable, non-calcified, and no significant MR or LA thrombus

• Surgical valve repair or replacement:

  • For patients not eligible for PBMV or with complex valve pathology

High-Yield Takeaways

• Mitral stenosis = rheumatic heart disease until proven otherwise

• Classic vignette = young immigrant or middle-aged woman with dyspnea and murmur

• Always think AF + embolic risk = need for anticoagulation

• Shorter S2–opening snap interval = worsening severity

• Echocardiography is diagnostic; PBMV is preferred definitive treatment in selected patients

Aortic Stenosis (AS)

Introduction: What Is Aortic Stenosis?

Aortic stenosis is a narrowing of the aortic valve orifice, which obstructs the flow of blood from the left ventricle to the aorta during systole. Over time, this causes chronic pressure overload, leading to concentric left ventricular hypertrophy (LVH).

AS is one of the most frequently tested valvular diseases on USMLE Step 2 CK, especially in:

• Elderly patients: due to degenerative calcific stenosis

• Younger patients: due to congenital bicuspid aortic valve

Pathophysiology: Pressure Overload and Its Consequences

• Narrow valve → resistance to systolic outflow → increased LV pressure

• LVH develops to overcome this pressure

• Initially maintains cardiac output, but eventually causes:

  • Diastolic dysfunction (stiff LV)

  • Impaired filling

  • Increased left atrial pressure

  • Pulmonary congestion and eventually heart failure

Clinical Presentation

The classic symptom triad of severe AS:

1. Exertional dyspnea (from elevated LV filling pressures)

2. Angina (increased O2 demand with fixed supply)

3. Syncope (especially with exertion due to fixed cardiac output)

Other signs:

• Fatigue

• Signs of congestive heart failure in late stages

This triad = severe disease with poor prognosis if untreated

Physical Examination Findings

• Crescendo–decrescendo systolic murmur:

  • Best heard at right upper sternal border (RUSB)

  • Radiates to carotid arteries

• Pulsus parvus et tardus:

  • Weak, delayed carotid upstroke

• Soft or absent S2:

  • In severe AS, valve is calcified and immobile

• Paradoxical splitting of S2:

  • A2 is delayed due to prolonged LV ejection

• Murmur intensity:

  • Increases with squatting or leg raise (↑ preload)

  • Decreases with Valsalva or standing (↓ preload)

Helps differentiate from HCM (which behaves the opposite)

Investigations

1. Echocardiography (Diagnostic gold standard):

• Valve area <1.0 cm² = severe AS

• Peak and mean transvalvular gradient

• LV wall thickness and function

2. ECG:

• Signs of LVH (e.g., high-voltage QRS, strain pattern)

3. Chest X-ray:

• May show post-stenotic aortic dilation

• Signs of pulmonary venous congestion or cardiomegaly in late disease

Management of Aortic Stenosis

Asymptomatic with mild/moderate AS:

• Monitor with serial echocardiography

• No intervention if LV function is preserved

Symptomatic or severe AS:

• Aortic valve replacement (AVR) is definitive treatment

Options:

• Surgical AVR (SAVR): for patients with acceptable surgical risk

• Transcatheter AVR (TAVR): for elderly or high surgical risk patients

Medical therapy:

• Limited role

• Avoid excessive diuresis or vasodilators: can reduce preload and worsen symptoms in fixed output states

Summary Pearls

• Think aortic stenosis in an elderly patient with exertional syncope or angina + systolic murmur

• RUSB murmur radiating to carotids = classic AS finding

• Pulsus parvus et tardus, soft S2, and paradoxical S2 splitting are signs of severity

• Murmur intensifies with squatting and softens with Valsalva → distinguishes AS from HCM

• Echocardiography is diagnostic → look for valve area <1.0 cm²

• AVR is indicated in symptomatic or severe AS (SAVR or TAVR)

Introduction: What Is MVP?

Mitral Valve Prolapse (MVP) is a valvular heart disorder in which one or both leaflets of the mitral valve bulge (prolapse) back into the left atrium during systole. This abnormal movement is most commonly due to myxomatous degeneration, where the connective tissue of the valve becomes redundant and floppy.

It is the most common cause of mitral regurgitation in developed countries, and a classic USMLE Step 2 CK topic, especially in:

• Young, thin females

• Patients with connective tissue disorders like Marfan syndrome or Ehlers-Danlos syndrome

Pathophysiology: What Goes Wrong?

• Structural weakening of the valve leaflets (myxomatous degeneration)

• During systole, increased LV pressure pushes the redundant leaflets back into the LA

• This may or may not cause mitral regurgitation (MR)

• Over time, MVP can lead to progressive MR, left atrial dilation, and in rare cases, arrhythmias or infective endocarditis

Clinical Features

Many patients are asymptomatic, but some may present with:

• Atypical chest pain (non-exertional, sharp or stabbing)

• Palpitations (due to associated arrhythmias or heightened awareness)

• Fatigue, dizziness, or anxiety

• Rare: syncope, arrhythmias, or embolic complications

MVP should be suspected in young patients with these symptoms and no evidence of ischemic disease.

Physical Exam Findings

Classic auscultation finding:

• Mid-systolic click, followed by a late systolic murmur (if MR is present)

• Best heard at the cardiac apex, with the diaphragm of the stethoscope

Dynamic auscultation clues:

• Valsalva or standing ↓ preload → earlier click + longer murmur

• Squatting or leg raise ↑ preload → delayed click + shorter murmur

This dynamic response helps distinguish MVP from other murmurs like hypertrophic cardiomyopathy (HCM).

Investigations

1. Echocardiography (Definitive Test):

• Prolapse of one or both mitral valve leaflets >2 mm above annular plane during systole

• Assess for degree of mitral regurgitation

2. ECG:

• Usually normal, but may show nonspecific ST/T changes or supraventricular arrhythmias

3. Chest X-ray:

• Normal in most cases

• Left atrial or ventricular enlargement if significant MR is present

Management

Asymptomatic patients:

• Reassurance and routine follow-up

• No restrictions on activity unless symptomatic

Symptomatic patients (e.g., palpitations, chest pain):

• Beta-blockers: to control symptoms and reduce adrenergic surges

Mitral regurgitation present?

• Follow MR management guidelines

• Monitor with serial echocardiography if regurgitation is mild to moderate

Endocarditis prophylaxis:

• NOT routinely recommended for isolated MVP, even with MR

• Only indicated if there’s a history of infective endocarditis or prosthetic heart valves

Summary Pearls

• MVP = most common valvular abnormality in developed countries

• Think of MVP in young female with mid-systolic click and atypical chest pain

• Dynamic murmur timing is key: earlier with ↓ preload (Valsalva), later with ↑ preload (squatting)

• Echo is diagnostic — confirms leaflet prolapse

• Beta-blockers help with symptomatic relief

• No routine endocarditis prophylaxis unless prior history or prosthetic valve

Mitral Regurgitation (MR)

Introduction: What Is Mitral Regurgitation?

Mitral regurgitation (MR) is a valvular heart disease where the mitral valve fails to close completely during systole, allowing blood to leak backward from the left ventricle (LV) into the left atrium (LA). This causes volume overload, leading to progressive LA dilation, elevated pulmonary pressures, and ultimately LV dysfunction.

MR is a key topic on USMLE Step 2 CK, often tested in cases of post-MI papillary muscle rupture, mitral valve prolapse, or rheumatic heart disease.

Classification and Etiology

Acute MR:

• Sudden onset of regurgitation → no time for LA adaptation

• Causes:

  • Papillary muscle rupture (e.g., after MI)

  • Infective endocarditis

  • Blunt chest trauma

• Leads to:

  • Abrupt rise in LA pressure

  • Pulmonary edema and flash heart failure

Chronic MR:

• Gradual progression → LA and LV have time to dilate and adapt

• Causes:

  • Mitral valve prolapse (MVP) – most common in developed countries

  • Rheumatic heart disease

  • Ischemic cardiomyopathy

• May remain asymptomatic for years, but eventually causes:

  • Fatigue, dyspnea, orthopnea, palpitations, atrial fibrillation

Clinical Features

• Symptoms:

  • Dyspnea on exertion, orthopnea

  • Fatigue (due to low forward output)

  • Palpitations (especially if AFib develops)

  • Acute MR → sudden pulmonary edema, dyspnea, hypotension

• Complications:

  • Atrial fibrillation from LA dilation

  • Pulmonary hypertension

  • Left-sided heart failure

Physical Examination

• Murmur:

  • Holosystolic (pansystolic) murmur

  • Best heard at the apex, radiates to the axilla

• S3 gallop:

  • Suggests increased volume returning to LV during diastole (seen in severe MR)

• Laterally displaced apex beat: due to LV dilation

Diagnostic Workup

1. Echocardiography (Gold standard):

• Visualizes leaflet anatomy, regurgitant jet, and chamber size

• Quantifies severity based on regurgitant volume and effective orifice area

• Assess LV function (EF) and LA size

2. ECG:

• LA enlargement, LV hypertrophy, or atrial fibrillation

3. Chest X-ray:

• Cardiomegaly

• Pulmonary venous congestion or edema (especially in acute MR)

Management Strategy

Medical Management (Supportive only – does not reverse valve disease):

• Diuretics for volume overload

• Vasodilators (e.g., ACE inhibitors) – reduce afterload if BP tolerates

• Rate control and anticoagulation if atrial fibrillation present

Surgical Management (Definitive):

• Indications:

  • Symptomatic MR

  • Asymptomatic MR with:

    • LVEF < 60% or

    • LVESD > 40 mm (left ventricular end-systolic dimension)

• Options:

  • Mitral valve repair (preferred for primary MR)

  • Mitral valve replacement (for secondary MR or non-repairable valves)

High-Yield

• MR = backward flow → volume overload → LA dilation → LV dysfunction

• Acute MR: think post-MI (papillary muscle rupture) → flash pulmonary edema

• Chronic MR: long-standing MVP, RHD, or ischemic disease

• Holosystolic murmur at apex → radiates to axilla

• S3 = severe MR and LV volume overload

• Echo = gold standard, evaluate severity + EF + chamber size

• Surgery = only definitive therapy; repair preferred over replacement when possible

Cardiac Tumors

Introduction: Why Cardiac Tumors Matter

Cardiac tumors are rare, but they are an important differential diagnosis in patients with unexplained cardiac symptoms such as dyspnea, syncope, embolic events, or constitutional symptoms. Recognizing these presentations is high-yield for USMLE Step 2 CK.

Cardiac tumors are categorized into:

• Primary tumors (originate in the heart)

• Secondary tumors (metastatic involvement) – more common than primary

Primary Cardiac Tumors: Most Common by Age

1. Myxoma (Most common in adults)

• Benign, mesenchymal origin

• Usually found in the left atrium, attached to the interatrial septum

• Pedunculated, gelatinous mass that may prolapse into mitral valve orifice

• Mimics mitral stenosis clinically → may obstruct blood flow during diastole

Clinical features:

• Positional dyspnea, orthopnea, syncope

• Sudden death if complete obstruction occurs

• Embolization: stroke, limb ischemia from tumor fragments

• Constitutional symptoms: fever, malaise, weight loss due to IL-6 secretion

2. Rhabdomyoma (Most common in children)

• Associated with tuberous sclerosis

• Typically affects infants and young children

• May cause arrhythmias or obstruction

• Often regresses spontaneously

Other primary tumors:

• Fibromas: firm, fibrous tumors seen in children

• Lipomas: benign fatty tumors

• Papillary fibroelastomas:

  • Usually located on valves

  • May embolize → stroke or MI

Secondary (Metastatic) Cardiac Tumors

Metastatic tumors are far more common than primary:

• Originate from:

  • Lung, breast, renal cell carcinoma

  • Melanoma (highly metastatic)

  • Lymphoma, leukemia

• Frequently involve the pericardium → may cause:

  • Pericardial effusion

  • Cardiac tamponade

Diagnostic Approach

1. Echocardiography:

• First-line test (especially transesophageal echo)

• Evaluates tumor location, mobility, size, and hemodynamic impact

2. Cardiac MRI / CT:

• For tissue characterization, exact size, and surgical planning

3. Histopathology:

• Needed post-resection for definitive diagnosis

Management Strategy

• Myxomas:

  • Surgical excision is curative in most cases

• Rhabdomyomas:

  • Often monitored; surgery if obstructive or symptomatic

• Metastatic tumors:

  • Treat primary cancer

  • Pericardiocentesis if tamponade occurs

  • Palliative care if extensive cardiac involvement

High-Yield

• Left atrial myxoma = think of mitral stenosis-like symptoms + systemic emboli + constitutional signs

• Positional syncope or dyspnea → suspect obstruction by pedunculated tumor

• Stroke in a young person with a normal carotid/heart exam → evaluate for myxoma

• Rhabdomyoma = child with tuberous sclerosis

• Metastatic cardiac tumors often present as pericardial effusion or tamponade

• Echo is diagnostic, especially transesophageal

Abdominal Aortic Aneurysm (AAA)

Introduction: What Is an Abdominal Aortic Aneurysm?

An abdominal aortic aneurysm (AAA) is a localized dilation of the abdominal aorta, defined as an aortic diameter ≥3.0 cm. It most frequently occurs in the infrarenal segment, below the origin of the renal arteries.

AAA is a classic Step 2 CK topic, especially in elderly men with atherosclerotic risk factors, and its timely recognition can be life-saving.

Pathophysiology: Why Do AAAs Form?

• The underlying cause is usually degenerative atherosclerosis → progressive loss of elastin and collagen in the aortic wall → wall weakening and dilation.

• Risk factors include:

  • Male sex

  • Age >65 years

  • Smoking (strongest modifiable risk factor)

  • Hypertension, hyperlipidemia

  • Family history of AAA

  • Connective tissue disorders: Marfan syndrome, Ehlers-Danlos syndrome

Clinical Presentation

• Asymptomatic: Most AAAs are incidentally discovered on abdominal imaging

• Symptomatic (but unruptured):

  • Deep, constant abdominal or back pain

  • Pulsatile abdominal mass

  • Compression effects: early satiety, urinary obstruction, venous thrombosis

• Ruptured AAA (surgical emergency):

  • Classic triad (but only in minority of cases):

    1. Severe abdominal or back pain

    2. Hypotension or syncope

    3. Pulsatile abdominal mass

  • May present in hemorrhagic shock with very high mortality

Physical Examination

• Palpable pulsatile mass in the abdomen (may be hard to appreciate in obese patients)

• Hypotension and cool extremities may indicate rupture

• Retroperitoneal bleeding may cause flank ecchymosis (Grey Turner sign)

Diagnostic Approach

1. Screening:

• One-time abdominal ultrasound for men aged 65–75 who have ever smoked

• Non-invasive, low-cost, and no radiation

2. Symptomatic or surgical planning:

• CT angiography (CTA) is the gold standard:

  • Accurately measures aortic diameter, extent, branch involvement

  • Helps with EVAR planning

3. Other studies:

• MRI/MRA: alternative for patients with contrast allergy or renal dysfunction

Management Strategy

Elective repair indications:

• Aneurysm size:

  • ≥5.5 cm in men

  • ≥5.0 cm in women

• Rapid growth:

  • >0.5 cm over 6 months

• Symptomatic aneurysms (even if <5.5 cm)

Surveillance strategy (if below threshold):

• 3.0–3.9 cm → ultrasound every 2–3 years

• 4.0–4.9 cm → every 12 months

• 5.0–5.4 cm → every 6 months

Surgical options:

• Open surgical repair: preferred in younger, low-risk patients

• Endovascular aneurysm repair (EVAR): minimally invasive; preferred in older/high-risk patients

Medical Risk Reduction

• Smoking cessation (most effective modifiable risk factor)

• Statins: recommended for atherosclerotic disease prevention

• Antihypertensive therapy: especially beta-blockers for BP control

Summary Pearls

• AAA = aortic diameter ≥3.0 cm, usually infrarenal

• Think AAA in elderly male smoker with abdominal/back pain and hypotension

• Pulsatile mass + pain + hypotension = rupture until proven otherwise

• Ultrasound for screening, CT angiography for surgical planning

• Repair if ≥5.5 cm in men, ≥5.0 cm in women, symptomatic, or rapidly expanding

• Prevent with smoking cessation, statins, and BP control

Dilated Cardiomyopathy (DCM)

Introduction: What Is DCM?

Dilated cardiomyopathy (DCM) is the most common type of cardiomyopathy, characterized by dilation and impaired systolic function of the left ventricle or both ventricles. The heart muscle becomes thin-walled and stretched, leading to reduced contractility, low ejection fraction, and symptoms of progressive systolic heart failure.

Etiology: Know the Primary and Secondary Causes

• Idiopathic (most common): many cases are familial/genetic (e.g., titin mutations)

Secondary causes include:

• Alcohol abuse (chronic toxicity)

• Viral myocarditis (especially Coxsackie B virus)

• Chemotherapy: doxorubicin, trastuzumab

• Peripartum cardiomyopathy

• Hemochromatosis

• Thyroid disease (hyperthyroidism or hypothyroidism)

• Chronic tachyarrhythmias (e.g., AFib with RVR)

• Chagas disease (important in Latin America)

Clinical Presentation

DCM typically presents with symptoms and signs of systolic heart failure (HFrEF):

Symptoms:

• Dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea (PND)

• Fatigue, exercise intolerance

• Peripheral edema, weight gain

Signs:

• Elevated jugular venous pressure (JVP)

• S3 gallop (due to volume overload)

• Displaced apical impulse

• Mitral or tricuspid regurgitation murmurs (secondary to dilation)

• Arrhythmias (AFib, ventricular tachycardia)

• Thromboembolic events (stroke, PE) from blood stasis in dilated chambers

Diagnostic Workup

1. Echocardiography (test of choice):

• Shows dilated ventricles with global hypokinesis

• Reduced ejection fraction (<40%)

2. Chest X-ray:

• Cardiomegaly, pulmonary vascular congestion or edema

3. ECG:

• Nonspecific ST-T changes, conduction abnormalities

• Atrial fibrillation or ventricular arrhythmias

4. BNP / NT-proBNP:

• Elevated in decompensated heart failure

5. Cardiac MRI / endomyocardial biopsy:

• May help in specific cases (e.g., myocarditis, sarcoidosis, amyloidosis)

Management of Dilated Cardiomyopathy

Standard HFrEF therapy:

• ACE inhibitors or ARBs

• Beta-blockers (e.g., carvedilol, bisoprolol, metoprolol succinate)

• Mineralocorticoid receptor antagonists (e.g., spironolactone, eplerenone)

• SGLT2 inhibitors (e.g., dapagliflozin)

• Loop diuretics (e.g., furosemide) for symptom relief of volume overload

Advanced interventions:

• Implantable cardioverter-defibrillator (ICD):

  • For EF ≤35% despite 3 months of optimal therapy

• Cardiac resynchronization therapy (CRT):

  • In patients with EF ≤35% + wide QRS

• Heart transplant: for refractory end-stage heart failure

Supportive care:

• Sodium restriction, fluid restriction in select patients

• Lifestyle changes: alcohol cessation, control of hypertension, diabetes

• Exercise rehab under supervision

High-Yield

• Think DCM in a patient with systolic heart failure, enlarged heart, and history of viral illness, alcohol use, or chemo

• S3 gallop + displaced PMI + low EF = classic signs

• Echo is diagnostic; look for global hypokinesis and chamber dilation

• Treat as HFrEF with ACEi/ARB, beta-blockers, MRA, SGLT2i

• ICD if EF ≤35%; consider CRT if wide QRS

• Always consider reversible causes (alcohol, thyroid, tachyarrhythmia)

Restrictive Cardiomyopathy (RCM)

Introduction: What Is RCM?

Restrictive cardiomyopathy (RCM) is a less common but clinically significant form of cardiomyopathy, characterized by impaired ventricular filling due to stiff, non-compliant ventricular walls, despite preserved systolic function. As a result, patients develop diastolic dysfunction, elevated filling pressures, biatrial enlargement, and often right-sided heart failure features.

It’s a high-yield topic for Step 2 CK, especially in cases involving infiltrative or fibrotic diseases.

Etiology: Infiltrative, Fibrotic, or Systemic Causes

Most common causes include:

• Amyloidosis (most common in the U.S.)

• Endomyocardial fibrosis (most common worldwide; endemic to tropics)

• Sarcoidosis

• Hemochromatosis (iron overload)

• Löffler eosinophilic myocarditis

• Scleroderma

• Radiation-induced fibrosis

• Post-surgical or post-radiation scarring

Clinical Presentation

Patients often present with right-sided heart failure symptoms:

• Peripheral edema

• Hepatomegaly

• Ascites

• Jugular venous distention (JVD)

Other symptoms include:

• Dyspnea, fatigue, exercise intolerance

• Atrial fibrillation due to biatrial enlargement

EF is usually preserved until late stages, making RCM a diastolic heart failure picture.

Diagnostic Workup

1. Echocardiography:

• Biatrial enlargement, normal or small ventricles

• Diastolic dysfunction (abnormal relaxation patterns)

• Normal or near-normal EF

• Increased wall thickness (especially in amyloidosis)

2. Cardiac MRI:

• Helps detect infiltrative patterns

• Late gadolinium enhancement in amyloidosis or sarcoidosis

3. Endomyocardial biopsy:

• Definitive diagnosis for amyloid, iron, eosinophils

4. ECG:

• Low-voltage QRS (in amyloidosis)

• Conduction abnormalities or arrhythmias

Management of Restrictive Cardiomyopathy

Supportive therapy:

• Diuretics: relieve volume overload (use cautiously to avoid underfilling)

• Rate control in atrial fibrillation

Etiology-specific treatment:

• Amyloidosis: Tafamidis (transthyretin), chemotherapy (AL type)

• Hemochromatosis: Iron chelation (deferoxamine) or phlebotomy

• Sarcoidosis: Immunosuppressants (e.g., corticosteroids)

• Löffler syndrome: Steroids ± cytotoxic agents

Advanced care:

• Heart transplantation for refractory end-stage disease

High-Yield

• Think RCM in patients with right-sided heart failure + normal EF + biatrial enlargement

• Amyloidosis = thickened ventricular walls + low-voltage ECG

• Endomyocardial fibrosis = most common RCM worldwide

• Echo shows: diastolic dysfunction, biatrial enlargement, preserved EF

• Use MRI and biopsy to confirm etiology

• Treat underlying cause; diuretics for symptom relief

Hypertrophic Cardiomyopathy (HCM)

Introduction: What Is HCM?

Hypertrophic cardiomyopathy (HCM) is a genetic myocardial disorder characterized by left ventricular hypertrophy (LVH) without an identifiable cause such as hypertension or aortic stenosis. It is one of the leading causes of sudden cardiac death (SCD) in young athletes, making it a high-yield topic for USMLE Step 2 CK.

HCM is usually caused by autosomal dominant mutations in sarcomeric proteins, especially:

• β-myosin heavy chain

• Myosin-binding protein C

Histologically, it is associated with myofibrillar disarray and diastolic dysfunction due to stiffened ventricles.

Pathophysiology: LVH, Diastolic Dysfunction, and LVOT Obstruction

• Asymmetric septal hypertrophy is the hallmark

• Can cause dynamic left ventricular outflow tract (LVOT) obstruction:

  • Obstruction worsens with ↓ preload/afterload (e.g., Valsalva, standing)

  • Improves with ↑ preload/afterload (e.g., squatting, handgrip)

• Diastolic dysfunction due to non-compliant hypertrophied ventricle

• Mitral valve systolic anterior motion (SAM) contributes to LVOT obstruction and mitral regurgitation

Clinical Presentation

Symptoms:

• Exertional dyspnea (most common)

• Chest pain (angina-like)

• Palpitations, syncope (especially post-exertional)

• Sudden cardiac death, especially in young athletes

Physical Exam:

• Crescendo–decrescendo systolic murmur:

  • Best heard at left lower sternal border

  • Increases with Valsalva or standing (↓ preload)

  • Decreases with squatting or leg raise (↑ preload)

• May also have S4 (stiff ventricle)

Diagnostic Workup

1. Echocardiography (test of choice):

• Asymmetric septal hypertrophy (septum >1.3x thickness of LV wall)

• Systolic anterior motion (SAM) of mitral valve

• Possible mitral regurgitation

2. ECG:

• LVH

• Deep Q waves in inferolateral leads

• Repolarization changes

3. Cardiac MRI:

• Detailed structural imaging

• Helpful when echo is inconclusive

4. Genetic testing & family screening:

• First-degree relatives should be screened

Management of Hypertrophic Cardiomyopathy

1. Medical therapy (first-line):

• Beta-blockers (reduce heart rate and LVOT gradient)

• Non-dihydropyridine CCBs (e.g., verapamil) if beta-blockers not tolerated

Avoid the following:

• Diuretics, nitrates, and vasodilators (↓ preload/afterload → worsens obstruction)

2. Prevention of Sudden Cardiac Death (SCD):

• ICD placement for high-risk patients:

  • Family history of SCD

  • Prior syncope

  • Massive LVH (wall >30 mm)

  • NSVT on Holter monitor

  • Abnormal BP response to exercise

3. Septal reduction therapy (for refractory obstruction):

• Surgical septal myectomy

• Alcohol septal ablation (catheter-based approach)

4. Lifestyle modification:

• Avoid competitive or strenuous sports

• Counsel patients on hydration and activity precautions

High-Yield

• Think HCM in young athlete with syncope, murmur, or SCD in family

• Murmur increases with Valsalva, decreases with squatting

• Echo confirms diagnosis: asymmetric septal hypertrophy + SAM

• First-line: beta-blockers or verapamil

• Avoid preload-reducing agents (diuretics, nitrates)

• High-risk = ICD placement

• Surgical options for refractory obstruction

Jugular Venous Pressure (JVP)

Introduction: What Is JVP and Why Is It Important?

Jugular venous pressure (JVP) is a non-invasive bedside tool used to estimate right atrial pressure, making it a key component of the physical exam in assessing volume status and central venous hemodynamics. It is especially useful in evaluating patients with heart failure, pericardial disease, and volume overload.

Technique: How to Measure JVP

• Patient should be reclined at a 30–45° angle

• Focus on the right internal jugular vein (IJV):

  • Direct anatomical connection to the right atrium

  • No valves and responsive to intrathoracic pressure

Measurement:

• Identify the highest point of venous pulsation

• Measure vertically from the sternal angle

• Normal JVP: ≤3 cm above the sternal angle → corresponds to ≤8 cm H₂O total right atrial pressure

Clinical Interpretation of Elevated JVP

Elevated JVP (>3 cm) may indicate:

• Right-sided heart failure

• Volume overload

• Pulmonary hypertension

• Tricuspid regurgitation

• Constrictive pericarditis
  
  JVP Waveform Components

  • a wave
    ▪ Represents atrial contraction
    ▪ Absent in atrial fibrillation due to loss of organized atrial contraction

  • c wave
    ▪ Caused by bulging of the tricuspid valve into the right atrium during early ventricular systole
    ▪ Often not visible on clinical exam

  • x descent
    ▪ Reflects atrial relaxation and downward displacement of the tricuspid valve during systole
    ▪ Prominent in cardiac tamponade

  • v wave
    ▪ Reflects venous filling of the right atrium against a closed tricuspid valve in late systole
    ▪ Becomes prominent in tricuspid regurgitation

  • y descent
    ▪ Represents passive emptying of the right atrium into the right ventricle during early diastole
    ▪ Prominent in constrictive pericarditis
    ▪ Blunted or absent in cardiac tamponade
    

  
  

  Clinical Signs & Associations

  • Kussmaul’s sign:

    • • Paradoxical rise in JVP during inspiration

      • Seen in constrictive pericarditis, restrictive cardiomyopathy, RV infarction

    • Prominent v wave:

      • Seen in tricuspid regurgitation

    • Absent a wave:

      • Classic for atrial fibrillation

    • Cannon a waves:

      • Due to AV dissociation (e.g., complete heart block)

      • Atrial contraction against a closed tricuspid valve

    • Hepatojugular reflux (HJR):

      • Sustained rise in JVP with firm abdominal pressure

      • Seen in right heart failure

    High-Yield Applications

    • Identify elevated JVP in patients with heart failure, tamponade, or pericardial disease

    • Differentiate:

      • Constrictive pericarditis: prominent y descent, Kussmaul's sign

      • Cardiac tamponade: blunted y descent, pulsus paradoxus

    • Recognize waveform clues:

      • Cannon a waves → complete heart block

      • Absent a wave → atrial fibrillation

      • Prominent v wave → tricuspid regurgitation
        

Heart Murmurs: Clinical Identification & Maneuver Response

Introduction: What Are Heart Murmurs?

Heart murmurs are audible vibrations caused by turbulent blood flow across cardiac structures. They are essential for bedside diagnosis and frequently tested on USMLE Step 2 CK, especially in cases involving valvular heart disease, congenital anomalies, and hemodynamic changes.

Murmurs are categorized by their timing in the cardiac cycle:

• Systolic: between S1 and S2

• Diastolic: after S2

• Continuous: persist throughout systole and diastole

Systolic Murmurs (S1 → S2)

1. Holosystolic (Pansystolic) Murmurs:

• Mitral regurgitation (MR):

  • Location: Apex

  • Radiation: to axilla

  • Quality: blowing

• Tricuspid regurgitation (TR):

  • Location: Left lower sternal border

  • Increased with inspiration (Carvallo’s sign)

• Ventricular septal defect (VSD):

  • Location: Left lower sternal border

  • Quality: harsh

2. Ejection Systolic (Crescendo–Decrescendo) Murmurs:

• Aortic stenosis (AS):

  • Location: Right upper sternal border

  • Radiation: to carotids

  • Associated with pulsus parvus et tardus

• Pulmonic stenosis (PS):

  • Location: Left upper sternal border

  • May have a systolic ejection click

Diastolic Murmurs (Always Pathologic)

1. Early Diastolic Murmurs:

• Aortic regurgitation (AR):

  • Location: Left sternal border

  • Best heard with patient leaning forward, during expiration

  • Quality: high-pitched, decrescendo

2. Mid-Diastolic Murmurs:

• Mitral stenosis (MS):

  • Location: Apex

  • Best heard in left lateral decubitus

  • Opening snap followed by low-pitched rumble

• Tricuspid stenosis (TS):

  • Location: Left lower sternal border

  • Increased with inspiration

Continuous Murmurs

• Patent ductus arteriosus (PDA):

  • Location: Left infraclavicular area

  • Quality: machinery-like murmur

?️Murmur Response to Maneuvers

↓ Preload: Valsalva & Standing Up

• ↑ HCM murmur

• ↑ MVP (earlier click and longer murmur)

• ↓ AS, ↓ MR

↑ Preload: Squatting & Leg Raise

• ↓ HCM murmur

• ↓ MVP (later click and shorter murmur)

• ↑ AS and MR intensity

↑ Afterload: Handgrip

• ↑ MR, AR, VSD murmurs

• ↓ AS and HCM murmurs

Respiratory Maneuvers:

• Inspiration:

  • ↑ Right-sided murmurs (TR, PS)

• Expiration:

  • ↑ Left-sided murmurs (MR, AR, MS)

Clinical Application

• Know murmur location, timing, radiation, and maneuvers

• Diagnose valvular disease based on clinical signs + echo

• Determine next step in management: observation, medical therapy, valve repair, or surgical replacement

Pulse Examination: Interpretation & Clinical Correlation

Introduction: Why the Pulse Matters

The pulse is a fundamental part of the cardiovascular exam and offers insight into cardiac output, rhythm, vascular tone, and valvular function. Proper assessment involves evaluating rate, rhythm, volume (amplitude), character (contour), and symmetry. Mastering pulse interpretation is essential for both physical diagnosis and Step 2 CK clinical reasoning.

Normal Pulse Characteristics

• Rate: 60–100 bpm

• Rhythm: regular

• Volume: normal amplitude

• Contour: smooth, brisk upstroke with gradual downstroke

• Symmetry: equal on both sides

Abnormal Pulse Findings & Their Clinical Associations

• Bounding pulse (high volume):

  • Seen in: Aortic regurgitation, anemia, thyrotoxicosis, AV fistula, fever

• Weak/thready pulse (pulsus parvus):

  • Seen in: Aortic stenosis, heart failure, hypovolemia

• Pulsus paradoxus:

  • Exaggerated drop in systolic BP >10 mmHg during inspiration

  • Seen in: Cardiac tamponade, severe asthma, constrictive pericarditis

• Pulsus alternans:

  • Alternating strong and weak pulse with regular rhythm

  • Seen in: Severe left ventricular dysfunction

• Bisferiens pulse:

  • Double-peaked pulse per systole

  • Seen in: Aortic regurgitation + stenosis, hypertrophic cardiomyopathy

• Anacrotic pulse:

  • Slow-rising, low-amplitude

  • Seen in: Aortic stenosis

• Dicrotic pulse:

  • Two distinct beats per cardiac cycle (second in diastole)

  • Seen in: Sepsis, low cardiac output states

Pulse Timing & Delays

• Radio-femoral delay:

  • Suggests: Coarctation of the aorta

• Radio-radial delay:

  • Suggests: Subclavian artery stenosis, aortic dissection

• Asymmetric pulses:

  • Red flags for: Aortic dissection, peripheral artery disease, embolism

Rhythm Abnormalities

• Irregularly irregular pulse:

  • Suggests: Atrial fibrillation

• Regularly irregular rhythm:

  • Suggests: Second-degree AV block, ventricular bigeminy

Pearls

• Know which pulse patterns match specific cardiac or systemic diseases

• Pulsus paradoxus = cardiac tamponade or severe asthma

• Pulsus alternans = advanced LV dysfunction

• Delayed or asymmetric pulses → think aortic pathology

• Irregularly irregular rhythm = AFib until proven otherwise

Pericarditis

Introduction: What Is Pericarditis?

Pericarditis means inflammation of the pericardial sac, the thin fibrous membrane surrounding the heart. It’s a frequently tested topic on Step 2 CK, especially when evaluating patients after a viral illness, myocardial infarction, or systemic autoimmune condition.

The most common cause is viral, particularly Coxsackievirus B. But always think beyond viruses — several other etiologies should be on your radar:

• Autoimmune diseases: e.g., systemic lupus erythematosus (SLE), rheumatoid arthritis

• Uremia: in advanced kidney disease

• Post-MI pericarditis:

  • Early (within 1–3 days after MI)

  • Late: called Dressler syndrome (autoimmune, weeks after MI)

• Trauma, radiation, malignancy

• Tuberculosis: in endemic regions

Clinical Presentation: Know the Classic Clues

Pericarditis usually presents with sharp, pleuritic chest pain. This pain is:

• Worse when lying flat

• Relieved when sitting up and leaning forward ← classic board clue

• May radiate to shoulders, neck, or trapezius

Associated symptoms may include low-grade fever, dyspnea, and palpitations.

Auscultation Finding: The Pericardial Friction Rub

The pericardial friction rub is a high-yield physical finding:

• Described as high-pitched, scratchy, or grating

• Best heard at the left lower sternal border using the diaphragm

• Often triphasic — heard in systole and both phases of diastole

If you hear it, write down “pericarditis” as your top differential.

ECG Findings: Saddle-Shaped ST Elevation and More

Pericarditis is ECG goldmine territory. Learn these classic changes — they are tested often.

• Diffuse ST-segment elevation across most leads (except aVR and V1)

  • Concave upward or “saddle-shaped”

• PR-segment depression

  • Most specific finding

• No reciprocal ST depression (unlike in MI)

Key comparison:

• Pericarditis = diffuse, concave ST elevation

• MI = localized ST elevation with reciprocal depression

Diagnostic Imaging: Role of Echocardiography

• Echo is essential to check for pericardial effusion

• In isolated pericarditis, the effusion may be small or absent

• If tamponade develops, watch for:

  • Hypotension

  • JVD (jugular venous distension)

  • Muffled heart sounds → this triad = Beck’s triad

Management: Tailored by Cause and Severity

Uncomplicated Acute Pericarditis:

• NSAIDs (e.g., ibuprofen or aspirin) for inflammation

• Colchicine to reduce recurrence (continue for 3 months)

• PPI for gastric protection when using NSAIDs

When NSAIDs Are Avoided:

• Early post-MI pericarditis (within 3 days):

  • NSAIDs may impair infarct healing

• Dressler’s Syndrome (post-MI autoimmune pericarditis, weeks later):

  • Treat with NSAIDs + colchicine

  • Avoid anticoagulants — risk of hemorrhagic pericardial effusion

Steroids:

• Reserved for NSAID-refractory cases or when NSAIDs are contraindicated

• May increase recurrence risk if used first-line

Summary Pearls

• Sharp, positional chest pain that improves when sitting up = think pericarditis

• Pericardial rub, diffuse concave ST elevation, and PR depression = classic triad

• Use echo to assess for effusion or tamponade

• Treat uncomplicated cases with NSAIDs + colchicine

• Avoid anticoagulants in Dressler syndrome

• Know which post-MI cases get NSAIDs and which do not

Pericardial Effusion

? Introduction: What Is Pericardial Effusion?

Pericardial effusion refers to the abnormal accumulation of fluid in the pericardial sac surrounding the heart. While small physiologic effusions may be asymptomatic, larger or rapidly accumulating effusions can impair cardiac filling and lead to cardiac tamponade, a life-threatening condition.

Step 2 CK often tests this topic alongside pericarditis, malignancy, uremia, or trauma-related cases.

Types of Pericardial Fluid (Based on Etiology)

• Serous → viral, autoimmune, idiopathic

• Hemorrhagic → trauma, malignancy, post-MI rupture, TB

• Purulent → bacterial infections

• Chylous → lymphatic obstruction (rare)

Common Causes of Pericardial Effusion

• Viral infections (e.g., Coxsackie B)

• Autoimmune diseases (e.g., SLE, RA)

• Malignancy (lung, breast, lymphoma)

• Uremia (CKD, ESRD)

• Post-MI (Dressler syndrome)

• Radiation therapy

• Trauma (can cause rapid, hemorrhagic effusion)

Clinical Presentation: Depends on Speed & Size

Small or slow effusions:

• May be asymptomatic

• Mild chest discomfort or dyspnea

Rapid or large effusions:

• Chest pressure, fatigue, dyspnea

• Hoarseness (compression of recurrent laryngeal nerve)

• Dysphagia (esophageal compression)

If tamponade develops: anticipate shock signs, including altered mental status and low output.

Physical Exam Findings

• Muffled or distant heart sounds

• Decreased apical impulse

• Pericardial friction rub may or may not be present

• If tamponade is present: Beck’s triad

  • Hypotension

  • Elevated JVP

  • Muffled heart sounds

Imaging and ECG

Chest X-ray:

• "Water bottle"–shaped heart silhouette if effusion is large

• May appear normal in small or acute effusions

ECG:

• Low-voltage QRS complexes

• Electrical alternans (swinging heart) — specific but not always present

Definitive Diagnosis: Echocardiography

Echocardiogram is the gold standard:

• Detects even small pericardial effusions

• Assesses for signs of tamponade:

  • Right atrial or RV diastolic collapse

  • Dilated IVC with no inspiratory collapse

CT/MRI:

• Helpful for characterization and surgical planning, but not first-line acutely

Management Approach

Stable patients with small/moderate effusion:

• Treat the underlying cause:

  • NSAIDs + colchicine for pericarditis

  • Dialysis for uremic effusion

  • Chemotherapy or radiation for malignant effusions

Unstable patients or those with tamponade physiology:

• Immediate pericardiocentesis (don’t delay for imaging)

• Monitor vitals and repeat echo post-drainage

Recurrent or loculated effusions:

• May require surgical pericardial window

High-Yield Pearls

• Think of pericardial effusion in any patient with distant heart sounds + chest discomfort

• Tamponade = Beck’s triad: hypotension, JVD, muffled heart sounds

• Echo is always the test of choice

• ECG clues: low-voltage QRS and electrical alternans

• CXR: water bottle silhouette in large effusion

• Management depends on stability — treat underlying cause or perform urgent pericardiocentesis if unstable

Infective Endocarditis (IE)

Introduction: What Is Infective Endocarditis?

Infective endocarditis is a serious infection of the endocardial surface of the heart, most often involving cardiac valves. The disease arises when bacteremia seeds damaged, prosthetic, or abnormal valves, triggering vegetation formation.

It is a high-yield condition on Step 2 CK — frequently tested through microbial etiology, clinical signs, and Duke criteria–based diagnosis.

Pathogenesis: How Does It Develop?

1. Endothelial damage (e.g., due to turbulent flow from pre-existing valvular disease or prosthetic material)

2. Deposition of platelets + fibrin

3. Microorganisms adhere to this damaged site during bacteremia

4. Formation of infected vegetations → local destruction and potential embolization

Common Causative Organisms by Scenario

• Staphylococcus aureus

  • Most common overall

  • Most common in IV drug users

  • Often involves tricuspid valve

  • Highly virulent → rapid valve destruction

• Viridans streptococci

  • Common post-dental procedures

  • Subacute presentation

  • Involves native valves (especially mitral)

• Enterococci

  • Associated with GU or GI procedures (e.g., colonoscopy, TURP)

• Staphylococcus epidermidis

  • Common in prosthetic valve endocarditis

• HACEK organisms (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)

  • Fastidious Gram-negative bacilli

  • Cause culture-negative endocarditis

Clinical Features: Classic and Systemic Signs

Constitutional symptoms:

• Fever, chills, malaise, anorexia

Cardiac signs:

• New or changing murmur (especially mitral or aortic)

Peripheral stigmata (vascular + immunologic phenomena):

• Janeway lesions: painless macules on palms/soles

• Osler nodes: tender nodules on fingers/toes

• Roth spots: retinal hemorrhages with pale centers

• Splinter hemorrhages: under nails

• Septic emboli → stroke, hematuria, renal infarct, lung abscess (tricuspid IE)

Diagnosis: Modified Duke Criteria

Major Criteria:

• Positive blood cultures for typical organisms

• Evidence of endocardial involvement on echocardiogram (vegetation, abscess, new valve regurgitation)

Minor Criteria:

• Fever ≥38°C

• Vascular phenomena (e.g., emboli, Janeway lesions)

• Immunologic signs (e.g., Osler nodes, Roth spots, glomerulonephritis)

• Predisposing heart condition or IV drug use

• Positive cultures not meeting major criteria

Diagnosis =

• 2 major, or

• 1 major + 3 minor, or

• 5 minor criteria

Investigations

• Blood cultures: ≥3 sets from separate sites before starting antibiotics

• Echocardiography:

  • Transesophageal (TEE) preferred for sensitivity

  • Transthoracic (TTE) for initial screening

• ESR/CRP: elevated

• Urinalysis: hematuria, RBC casts (immune complex glomerulonephritis)

• ECG: may show conduction abnormalities (if abscess near AV node)

Management Strategy

Empiric treatment (before culture results):

• Vancomycin + ceftriaxone (covers MRSA, strep, enterococci)

Definitive therapy (4–6 weeks IV antibiotics) tailored by:

• Organism

• Valve type (native vs prosthetic)

• Susceptibility profile

Indications for surgery:

• Heart failure from valve dysfunction

• Perivalvular abscess

• Persistent bacteremia >7 days despite antibiotics

• Large vegetations (>10 mm)

• Prosthetic valve involvement

• Recurrent emboli

Prophylaxis Guidelines (Dental Procedures)

Who gets it?

• Prosthetic heart valves

• Prior history of IE

• Certain congenital heart defects

• Cardiac transplant recipients with valvulopathy

What to give?

• Amoxicillin 2g PO 30–60 minutes before procedure

• If allergic: clindamycin 600 mg PO

Summary Pearls

• Think IE in any patient with fever + murmur

• IV drug user + tricuspid murmur + septic emboli = S. aureus

• Viridans strep = post-dental

• TEE = best imaging; 3 blood cultures before antibiotics

• Use Duke Criteria to diagnose

• Empiric antibiotics: vancomycin + ceftriaxone

• Prophylaxis for high-risk patients before dental procedures

Heart Sounds

Introduction

Heart sounds are a fundamental part of the cardiovascular examination. They offer essential diagnostic insight into conditions like valvular heart disease, cardiomyopathy, and pericardial inflammation. For Step 2 CK, being able to identify and interpret heart sounds — including timing, quality, and associated pathology — is critical in answering murmur-based and auscultation-driven clinical vignettes.

Normal Heart Sounds (S1 and S2)

S1 marks the beginning of systole and results from the closure of the mitral and tricuspid valves. It is best heard at the cardiac apex. A loud S1 may suggest mitral stenosis, while a soft S1 can be heard in cases of mitral regurgitation or a prolonged PR interval such as in first-degree AV block.

S2 marks the end of systole and is caused by the closure of the aortic and pulmonic valves. Physiologic splitting of S2 occurs during inspiration, where the pulmonic valve closes slightly later than the aortic valve.

S2 Splitting Variants and Their Clinical Associations

• Wide splitting of S2 (greater separation between A2 and P2) is heard in right bundle branch block or pulmonic stenosis.

• Fixed splitting of S2, which does not vary with respiration, is classic for atrial septal defect.

• Paradoxical splitting is when the aortic valve closes after the pulmonic valve, usually due to left bundle branch block or severe aortic stenosis. It becomes more apparent during expiration.

Extra Heart Sounds (S3 and S4)

S3 is a low-pitched sound heard early in diastole, just after S2. It is best heard with the bell of the stethoscope at the apex in the left lateral decubitus position. S3 indicates increased filling pressure and is considered normal in children and young adults. However, in adults over 40, it often reflects volume overload as seen in heart failure, mitral regurgitation, or dilated cardiomyopathy. It is referred to as a “ventricular gallop.”

S4 occurs in late diastole, just before S1, and represents atrial contraction against a stiff or noncompliant ventricle. This sound is associated with left ventricular hypertrophy, hypertrophic cardiomyopathy, or aortic stenosis. It is absent in atrial fibrillation and is called an “atrial gallop.”

Clicks, Snaps, and Friction Rubs

Ejection clicks are high-pitched sounds occurring shortly after S1 and are linked to structural abnormalities such as a bicuspid aortic valve or pulmonic stenosis.

Opening snaps are heard after S2 and are specific to mitral stenosis. The shorter the interval between S2 and the opening snap, the more severe the stenosis.

Pericardial friction rubs are not true heart sounds, but they are critical to identify. These scratchy, high-pitched sounds are best heard at the left lower sternal border with the patient leaning forward. They are characteristic of acute pericarditis and may be triphasic, occurring during systole and both phases of diastole.

Clinical Pearls

• A loud S1 suggests mitral stenosis; a soft S1 indicates mitral regurgitation or first-degree AV block.

• Physiologic S2 splitting is normal with inspiration.

• Fixed splitting is seen in atrial septal defect, while paradoxical splitting indicates left-sided delay, such as in left bundle branch block or aortic stenosis.

• An S3 gallop points toward fluid overload and heart failure, particularly in adults over 40.

• An S4 gallop reflects a stiff ventricle and is linked to conditions like LV hypertrophy or HCM.

• Opening snaps are specific for mitral stenosis, and their timing correlates with severity.

• Ejection clicks hint at bicuspid valves or outflow obstruction.

• A friction rub is a hallmark of pericarditis and should prompt evaluation for other signs like chest pain relieved by sitting up.

Congestive Heart Failure (CHF)

Introduction: What Is CHF?

Congestive heart failure is a clinical syndrome characterized by the heart’s inability to pump sufficient blood to meet the body's metabolic demands. This results in symptoms of congestion, such as dyspnea and edema, and signs of low cardiac output, such as fatigue and exercise intolerance. CHF is a common and highly testable topic on Step 2 CK due to its diagnostic complexity, diverse causes, and nuanced treatment strategies.

Classification of Heart Failure

CHF is typically divided into two major categories:

• Heart Failure with Reduced Ejection Fraction (HFrEF):

  • Defined as LVEF <40%

  • Involves systolic dysfunction — the heart cannot contract effectively

• Heart Failure with Preserved Ejection Fraction (HFpEF):

  • Defined as LVEF ≥50%

  • Involves diastolic dysfunction — the ventricle becomes stiff and does not fill adequately

There is also a mid-range category (LVEF 41–49%), but Step 2 CK primarily focuses on HFrEF and HFpEF.

Etiology

HFrEF (Systolic Failure):

• Ischemic heart disease (most common cause)

• Dilated cardiomyopathy

• Valvular disease (e.g., aortic or mitral regurgitation)

• Myocarditis

HFpEF (Diastolic Failure):

• Chronic hypertension

• Diabetes mellitus

• Obesity

• Aging-related myocardial stiffness

• Atrial fibrillation

Clinical Presentation

Common symptoms include:

• Dyspnea on exertion

• Orthopnea (dyspnea when lying flat)

• Paroxysmal nocturnal dyspnea (PND)

• Fatigue and weakness

• Peripheral edema or abdominal bloating

Physical exam findings may include:

• Elevated jugular venous pressure (JVP)

• S3 gallop (typical of HFrEF)

• Bibasilar crackles (due to pulmonary congestion)

• Hepatomegaly

• Pitting leg edema

Diagnostic Evaluation

• BNP or NT-proBNP:

  • Released due to ventricular stretch

  • Helps differentiate CHF from other causes of dyspnea

• Chest X-ray:

  • May show cardiomegaly, pulmonary vascular congestion, or pleural effusions

• Echocardiography (test of choice):

  • Assesses LVEF, wall motion abnormalities, valvular function, and diastolic filling patterns

• Electrocardiogram (ECG):

  • Evaluates for ischemia, arrhythmias, or prior MI

• Additional labs:

  • Creatinine and electrolytes (especially when using diuretics)

  • Troponins (if ischemia suspected)

  • Liver function tests, TSH, CBC

Management Based on Heart Failure Type

HFrEF: Guideline-Directed Medical Therapy

These drugs reduce mortality and improve symptoms:

• ACE inhibitors or ARBs

• Beta-blockers: carvedilol, metoprolol succinate, or bisoprolol

• Mineralocorticoid receptor antagonists: spironolactone or eplerenone

• SGLT2 inhibitors: dapagliflozin or empagliflozin

• Loop diuretics (e.g., furosemide): for volume overload relief

• Hydralazine + nitrates: especially beneficial in African American patients

Device therapies for HFrEF (when indicated):

• ICD for primary prevention if EF ≤35%

• CRT if EF ≤35% and QRS ≥150 ms with LBBB pattern

HFpEF: Symptom-Based Management

• Focus on treating comorbidities:

  • Hypertension, atrial fibrillation, coronary disease, diabetes

• Diuretics for fluid control

• No current therapies show a consistent mortality benefit

Acute Decompensated Heart Failure

Patients may present with:

• Severe dyspnea, tachypnea, hypoxia

• Pulmonary edema, elevated JVP, hypotension

Management includes:

• IV loop diuretics (e.g., furosemide)

• Supplemental oxygen or non-invasive ventilation

• Vasodilators (e.g., nitroglycerin) if BP allows

• Identify and correct triggers:

  • Infection, arrhythmia, dietary or medication nonadherence, ischemia

Pearls

• Think HFrEF in a patient with low EF and S3 gallop

• BNP helps rule in CHF, especially when the diagnosis is uncertain

• Always use echo to differentiate HFrEF vs HFpEF

• Initiate GDMT with ACE inhibitors, beta-blockers, MRA, and SGLT2 inhibitors for HFrEF

• Loop diuretics relieve congestion but do not improve survival

• In HFpEF, focus on managing BP, AFib, and volume

• Know when to admit for acute decompensation, especially with respiratory distress or hypoxia

Hypertension (HTN): Clinical Foundations & Management Strategy

Introduction: What Is Hypertension?

Hypertension is one of the most common chronic medical conditions seen in clinical practice and a key concept for Step 2 CK. According to the current ACC/AHA guidelines, hypertension is defined as a systolic blood pressure (SBP) ≥130 mmHg or diastolic blood pressure (DBP) ≥80 mmHg, measured on at least two separate occasions.

Classification of Hypertension

• Primary (Essential) Hypertension:

  • Accounts for about 90–95% of cases

  • Has no identifiable cause

  • Related to genetic factors, increased sympathetic activity, salt sensitivity, obesity, and lifestyle (sedentary behavior, poor diet)

• Secondary Hypertension:

  • Should be suspected in:

    • Young patients (<30 years) with no family history

    • Patients with sudden onset or refractory hypertension

    • Cases of malignant hypertension or resistant HTN

Common secondary causes include:

• Renal artery stenosis

• Primary hyperaldosteronism (Conn syndrome)

• Pheochromocytoma

• Cushing's syndrome

• Coarctation of the aorta

• Obstructive sleep apnea (OSA)

Target Organ Damage in Hypertension

Although hypertension is often asymptomatic, its long-term effects are significant and include damage to multiple organ systems:

• Cardiovascular system:

  • Left ventricular hypertrophy (LVH)

  • Coronary artery disease (CAD)

  • Congestive heart failure (CHF)

• Neurological system:

  • Ischemic and hemorrhagic stroke

  • Hypertensive encephalopathy

• Renal system:

  • Chronic kidney disease (CKD)

  • Proteinuria

• Ophthalmologic system:

  • Hypertensive retinopathy:

    • Arteriolar narrowing

    • Arteriovenous (AV) nicking

    • Flame hemorrhages

    • Cotton wool spots

    • Papilledema in severe cases

Initial Evaluation of Hypertension

The workup begins with accurate BP measurements and an evaluation for end-organ damage. The basic lab tests include:

• Serum creatinine and electrolytes

• Fasting glucose or HbA1c

• Lipid profile

• Urinalysis

• Electrocardiogram (ECG) — to assess for LVH or arrhythmias

Further investigations (e.g., plasma aldosterone/renin ratio, renal Doppler, 24-hour urine catecholamines) are guided by the clinical suspicion of secondary causes.

Non-Pharmacologic Management (Lifestyle Modifications)

Lifestyle changes are first-line in all patients, and may be sufficient in early or borderline cases:

• Weight loss

• DASH diet (rich in fruits, vegetables, whole grains, and low-fat dairy)

• Sodium restriction: <2.3 g/day

• Regular aerobic exercise: 30 minutes most days

• Limit alcohol: <2 drinks/day (men), <1 drink/day (women)

• Smoking cessation and stress reduction

Pharmacologic Therapy: When and What to Start

Treatment is indicated in the following situations:

• Stage 1 HTN (130–139/80–89 mmHg) with known ASCVD or a 10-year cardiovascular risk ≥10%

• Stage 2 HTN (≥140/90 mmHg)

First-line antihypertensive classes include:

• Thiazide diuretics

• ACE inhibitors (ACEi) or Angiotensin receptor blockers (ARBs)

• Calcium channel blockers (CCBs)

Agent Selection Based on Comorbidities

• Diabetes or CKD: Use ACE inhibitors or ARBs (renal protection)

• African American patients (without CKD): Prefer CCBs and thiazide diuretics

• Post-MI or heart failure: Use beta-blockers and ACE inhibitors

• Pregnancy: Use labetalol, methyldopa, or nifedipine (avoid ACEi/ARBs)

Treatment Targets

• The goal BP in most patients is <130/80 mmHg, particularly in those with cardiovascular disease, diabetes, or CKD.

Clinical Pearls

• Always assess for secondary causes in young, non-obese, or resistant cases

• A renal bruit should prompt investigation for renal artery stenosis

• Hypokalemia + HTN = suspect primary aldosteronism

• Refractory HTN + episodic headaches + palpitations = think pheochromocytoma

• Don't forget DASH + exercise as foundational therapy

• Monitor electrolytes and renal function regularly on ACEi/ARBs or diuretics

Rheumatic Fever (RF)

Introduction: What Is Rheumatic Fever?

Rheumatic fever is a post-infectious autoimmune complication that develops 2–4 weeks after an episode of untreated or inadequately treated group A Streptococcus (GAS) pharyngitis, most often caused by Streptococcus pyogenes. It is a key cause of acquired valvular heart disease globally, with a strong predilection for the mitral valve (leading to mitral stenosis in chronic cases).

This is a high-yield Step 2 CK topic, especially in global health or cardiology-based clinical scenarios.

Pathophysiology: The Role of Molecular Mimicry

The pathogenesis involves molecular mimicry, where the body’s immune response against the streptococcal M protein results in cross-reactive antibodies that mistakenly target host tissues:

• Heart → pancarditis (pericardium, myocardium, endocardium)

• Joints → inflammation

• Skin, brain, subcutaneous tissues → systemic involvement

Clinical Diagnosis: Jones Criteria

To diagnose RF, you need evidence of a recent GAS infection (such as a positive throat culture or elevated anti-streptolysin O [ASO] or anti-DNase B titers) along with major and minor criteria.

Major criteria (mnemonic: J♥NES):

• Joints: Migratory polyarthritis, especially of large joints (knees, ankles)

• ♥ Carditis: May involve all three heart layers — pancarditis

  • Common murmurs: mitral regurgitation > aortic regurgitation

• Nodules: Firm, painless, subcutaneous nodules over extensor surfaces

• Erythema marginatum: Pink, serpiginous rash with central clearing

• Sydenham chorea: Involuntary, jerky movements; often seen in adolescent girls

Minor criteria:

• Fever

• Arthralgia

• Elevated ESR or CRP

• Prolonged PR interval on ECG

Diagnostic requirement:

• 2 major criteria
  OR

• 1 major + 2 minor criteria
  PLUS

• Evidence of preceding streptococcal infection

Carditis: Clinical and Subclinical Forms

Carditis may be clinically evident or subclinical, especially in early stages. Even if auscultation is unremarkable, echocardiography should be performed to assess for valvular involvement — particularly mitral valve regurgitation. Pancarditis remains the hallmark cardiac manifestation.

Management Overview

Acute Treatment

• Eradicate Streptococcus:

  • Benzathine penicillin G (IM injection)

• Anti-inflammatory therapy:

  • Aspirin for arthritis and mild carditis

  • Corticosteroids for severe carditis or heart failure symptoms

• Sydenham chorea:

  • May require valproate or neuroleptics

Secondary Prophylaxis: Preventing Recurrence

This is the most critical long-term step in management. Monthly intramuscular benzathine penicillin G is used to prevent recurrence and progressive rheumatic heart disease.

• Duration of prophylaxis depends on cardiac involvement:

  • No carditis → prophylaxis for 5 years or until age 21, whichever is longer

  • Carditis without residual heart disease → 10 years or until age 21

  • Carditis with residual valvular disease → at least 10 years or until age 40 (possibly lifelong)

Pearls

• Always think of rheumatic fever in a child with fever, arthritis, murmur, and history of untreated sore throat

• Sydenham chorea may appear late and in isolation — still qualifies for diagnosis

• Carditis can be silent — always order an echocardiogram

• Mitral valve is most commonly affected; aortic valve may be involved as well

• Treat acutely with penicillin + aspirin, and follow with long-term prophylaxis

• Know the Jones criteria and how to apply them in vignettes

Pulmonary Valve Regurgitation (PR)

Introduction: What Is PR?

Pulmonary valve regurgitation is a condition where blood flows backward from the pulmonary artery into the right ventricle during diastole, due to an incompetent pulmonary valve. While mild or physiologic PR can be found in healthy individuals and is often benign, pathologic PR has clinical implications and is frequently integrated into USMLE vignettes involving right heart failure, congenital heart disease, or pulmonary hypertension.

Etiology: What Causes Pulmonary Regurgitation?

PR can be:

• Physiologic: trivial and asymptomatic in healthy individuals

• Pathologic, commonly due to:

  • Pulmonary hypertension (leading to annular dilation)

  • Surgical repair of congenital heart disease (e.g., tetralogy of Fallot)

  • Infective endocarditis affecting the pulmonary valve

  • Carcinoid syndrome causing serotonin-mediated fibrotic valve damage

  • Iatrogenic injury post cardiac procedures

Clinical Features: When Does PR Become Symptomatic?

• Mild PR: usually asymptomatic and detected incidentally

• Moderate to severe PR: leads to right ventricular volume overload, eventually progressing to right-sided heart failure

Symptoms in advanced cases include:

• Fatigue and exertional dyspnea

• Peripheral edema and ascites

• Hepatic congestion (abdominal fullness or discomfort)

• Jugular venous distension

Physical exam findings:

• High-pitched early diastolic decrescendo murmur, best heard at the left upper sternal border

  • Especially notable in pulmonary hypertension: known as the Graham Steell murmur

• Murmur increases with inspiration (Carvallo’s sign)

• Possible prominent RV impulse, hepatomegaly, and JVD

? Diagnostic Workup

1. Echocardiography (first-line):

• Visualizes pulmonary valve structure and motion

• Detects regurgitant jet and right ventricular size/function

2. Additional tests if pulmonary hypertension is suspected:

• Chest X-ray: may show RV enlargement or pulmonary artery dilation

• ECG: signs of right axis deviation or RV hypertrophy

• BNP or NT-proBNP: elevated in volume overload

• Right heart catheterization: confirms pulmonary pressures and hemodynamics

Management Approach

Mild PR:

• No treatment required

• Monitor clinically and with periodic echocardiograms if indicated

Moderate to severe PR:

• Treat the underlying cause:

  • Control pulmonary hypertension

  • Address carcinoid syndrome, infection, or postoperative complications

• Medical therapy:

  • Diuretics for symptomatic relief in volume overload

  • Note: diuretics improve symptoms but do not correct the valvular lesion

• Surgical intervention:

  • Consider valve repair or replacement in:

    • Symptomatic patients with right ventricular dysfunction

    • Patients post-repair of congenital heart defects (e.g., repaired tetralogy of Fallot)

Clinical Pearls

• Graham Steell murmur = high-pitched early diastolic murmur at the LUSB, often from pulmonary hypertension

• Murmur gets louder with inspiration — a right-sided murmur (Carvallo’s sign)

• Always think of PR in patients with tetralogy of Fallot repair or carcinoid syndrome

• Echo is the diagnostic cornerstone, but right heart cath may be required in advanced cases

• Diuretics relieve symptoms, but surgery is definitive when RV dysfunction develops

Tricuspid Stenosis (TS)

Introduction: What Is Tricuspid Stenosis?

Tricuspid stenosis is a rare diastolic valvular lesion that obstructs blood flow from the right atrium to the right ventricle, resulting in elevated right atrial pressures, systemic venous congestion, and reduced cardiac output. While less common than left-sided valvular disease, it often coexists with mitral stenosis, especially in cases of rheumatic heart disease, which remains the leading cause worldwide.

Etiologies

• Rheumatic heart disease (most common cause)

  • Often seen alongside mitral valve involvement

• Carcinoid syndrome

  • Serotonin-induced fibrotic plaque formation affecting right-sided valves

• Congenital tricuspid stenosis (rare)

• Infective endocarditis

  • Especially in prosthetic tricuspid valves

• Iatrogenic or postoperative complications

Clinical Presentation

Patients with significant TS typically exhibit features of isolated right-sided heart failure, often in the setting of multivalvular involvement.

Symptoms:

• Fatigue and exercise intolerance (due to low forward output)

• Peripheral edema

• Abdominal discomfort, ascites, and hepatomegaly

• Jugular venous distension (JVD) with prominent a waves

  • Reflecting right atrial contraction against a narrowed valve

Auscultatory Findings:

• Low-pitched diastolic rumbling murmur

  • Best heard at the left lower sternal border

  • Louder with inspiration (Carvallo’s sign) — a key finding that distinguishes it from mitral murmurs

• Mid-diastolic opening snap may be audible in some cases

Diagnostic Workup

Echocardiography (mainstay of diagnosis):

• Thickened tricuspid valve leaflets

• Reduced valve area

• Elevated diastolic pressure gradient across the valve

• Doppler studies used to assess severity

ECG findings:

• Right atrial enlargement (e.g., peaked P waves in lead II)

Chest X-ray:

• May show prominent right heart border

• Possible dilated superior vena cava (SVC) or inferior vena cava (IVC)

Management Strategy

Medical therapy (initial):

• Diuretics: relieve venous congestion and symptoms like edema and ascites

  • Especially useful in patients who are not immediate surgical candidates

Definitive treatment:

• Surgical valve repair or replacement

  • Often performed during surgery for left-sided valvular disease

  • Indicated in symptomatic patients with severe TS

• Percutaneous balloon valvotomy

  • Considered in patients without significant tricuspid regurgitation or calcification

Clinical Pearls

• Think tricuspid stenosis in a patient with systemic venous congestion and a diastolic murmur that increases with inspiration

• Always assess for coexisting mitral stenosis, especially in rheumatic heart disease

• The Carvallo’s sign is essential to identify right-sided murmurs

• Echocardiography is diagnostic, but ECG and CXR provide supporting data

• Diuretics manage symptoms, but surgery or valvotomy is required for long-term correction

Tricuspid Regurgitation (TR)

Introduction: What Is Tricuspid Regurgitation?

Tricuspid regurgitation refers to the incompetence of the tricuspid valve, where blood flows backward from the right ventricle into the right atrium during systole. This leads to right atrial volume overload, elevated systemic venous pressures, and ultimately manifests as right-sided heart failure. On Step 2 CK, this valvular lesion is frequently tested in association with pulmonary hypertension, right ventricular dilation, or IV drug use–related endocarditis.

Etiologies: Primary vs. Secondary TR

• Secondary (functional) TR is far more common and is due to:

  • Right ventricular dilation or pressure overload

  • Pulmonary hypertension

  • Left-sided heart failure (indirect RV strain)

  • Pacemaker or ICD leads disrupting leaflet coaptation

• Primary TR (structural valve abnormality):

  • Rheumatic heart disease

  • Infective endocarditis, especially in IV drug users

  • Carcinoid syndrome (serotonin-induced fibrosis of right heart valves)

  • Ebstein’s anomaly (congenital malformation of the tricuspid valve)

Clinical Features

TR commonly presents with systemic venous congestion and signs of right-sided heart failure.

Symptoms:

• Fatigue

• Peripheral edema

• Ascites

• Hepatomegaly or abdominal fullness

Physical Exam Findings:

• Holosystolic murmur at the left lower sternal border

  • Increases with inspiration (Carvallo’s sign) — a hallmark right-sided feature

• Jugular venous distension with prominent V waves

• Pulsatile liver on abdominal palpation

• Right ventricular heave may be palpable in longstanding cases

Diagnosis

Echocardiography (gold standard):

• Reveals regurgitant flow across the tricuspid valve

• Evaluates valve anatomy and leaflet coaptation

• Measures RA and RV chamber size

• In functional TR, valve leaflets appear normal but the annulus is dilated

ECG findings:

• May show right atrial enlargement

• Atrial fibrillation may be present in chronic TR

Chest X-ray:

• Can show right-sided heart enlargement

• Pulmonary vasculature is usually normal unless associated with pulmonary hypertension

Management

Medical therapy:

• Aimed at treating underlying causes:

  • Control pulmonary hypertension

  • Manage left-sided heart failure

  • Eradicate infection in cases of endocarditis

• Diuretics for volume overload and symptomatic relief

  • Common agents: furosemide, torsemide

Surgical intervention:

• Indicated for:

  • Severe symptomatic TR

  • Patients undergoing surgery for coexisting valvular lesions (e.g., mitral or aortic)

• Valve repair is preferred over replacement when feasible

  • Repair reduces risk of prosthetic complications and preserves RV function

• Replacement is considered when:

  • Repair is not technically possible

  • There is severe leaflet destruction (e.g., due to infection or fibrosis)

Clinical Pearls

• A holosystolic murmur that increases with inspiration = think TR

• TR + IV drug use + fever = suspect infective endocarditis

• TR + serotonin-producing tumor = consider carcinoid syndrome

• Always investigate pulmonary hypertension in secondary TR

• Treat volume overload with diuretics, but definitive management depends on severity and symptoms

• Echo is diagnostic — never rely solely on auscultation

Aortic Regurgitation (AR)

Introduction: What Is Aortic Regurgitation?

Aortic regurgitation is a diastolic valvular lesion in which the aortic valve fails to close completely, causing retrograde blood flow from the aorta back into the left ventricle. This leads to volume overload, progressive ventricular dilation, and eventually systolic heart failure. AR is tested frequently on Step 2 CK — especially through recognition of its classic murmur, exam findings, and management distinctions between acute and chronic forms.

Etiologies of AR: Chronic vs Acute

Chronic AR causes:

• Bicuspid aortic valve (most common congenital cause)

• Rheumatic heart disease

• Aortic root dilation from:

  • Marfan syndrome

  • Ehlers-Danlos syndrome

  • Syphilitic aortitis

  • Chronic hypertension

• Connective tissue diseases (e.g., ankylosing spondylitis, reactive arthritis)

Acute AR causes (medical emergency):

• Aortic dissection

• Infective endocarditis

• Chest trauma

• Sudden valve leaflet rupture

Clinical Presentation

Chronic AR:

• Often asymptomatic for years

• Eventually presents with:

  • Fatigue, dyspnea on exertion

  • Orthopnea, paroxysmal nocturnal dyspnea

  • Palpitations, especially when lying flat (due to widened pulse pressure)

• Physical signs of high stroke volume and wide pulse pressure become prominent in severe disease

Acute AR:

• Presents with sudden cardiogenic shock

• Pulmonary edema, hypotension, dyspnea, and signs of poor perfusion

• No time for left ventricular adaptation → rapid decompensation

Physical Examination Findings

Murmur:

• High-pitched, early diastolic decrescendo murmur

• Best heard at left sternal border, with patient sitting up, leaning forward, and during expiration

Peripheral signs of chronic severe AR:

• Bounding pulses (Corrigan’s pulse)

• Head bobbing with each heartbeat (de Musset’s sign)

• Capillary pulsations in nail beds (Quincke’s sign)

• “Pistol-shot” femoral sounds (Traube’s sign)

• Wide pulse pressure is a hallmark feature

These signs are classic vignette clues on Step 2 CK and indicate chronic, severe AR.

Diagnostic Evaluation

• Echocardiography (gold standard):

  • Confirms valve dysfunction

  • Visualizes regurgitant jet

  • Assesses left ventricular size and function

  • Doppler used to grade regurgitation severity

• ECG:

  • May reveal left ventricular hypertrophy (LVH) due to volume overload

• Chest X-ray:

  • Can show cardiomegaly, aortic root dilation, or pulmonary congestion

• CT or MRI:

  • Useful in evaluating the aortic root, especially when dissection or connective tissue disorder is suspected

Management Approach

Chronic AR:

• Asymptomatic with normal LV function:

  • Monitor periodically with serial echocardiograms

  • Start vasodilators (e.g., ACE inhibitors, nifedipine) if hypertensive or not surgical candidates

• Surgical aortic valve replacement (AVR) is indicated for:

  • Symptomatic patients

  • Asymptomatic patients with:

    • Ejection fraction <55%

    • Severe LV dilation (LV end-diastolic dimension >65 mm)

Acute AR:

• Requires urgent surgical intervention

• While awaiting surgery, initiate IV vasodilators (e.g., nitroprusside) and inotropes (e.g., dobutamine)

• Avoid beta-blockers — they worsen forward flow and prolong diastole

Key Pearls

• A diastolic murmur + bounding pulse = think AR

• Head bobbing + wide pulse pressure = classic for chronic AR

• IV drug use + murmur + shock = suspect acute endocarditis with AR

• Always evaluate for aortic root disease in younger patients with Marfan features

• Echo is diagnostic; surgery is curative in symptomatic or deteriorating patients

Constrictive Pericarditis (CP)

Introduction: What Is Constrictive Pericarditis?

Constrictive pericarditis is a chronic inflammatory condition where the pericardium becomes fibrotic, thickened, and non-compliant, ultimately restricting the heart’s ability to expand during diastole. This mechanical constraint leads to impaired ventricular filling, predominantly affecting the right heart, and results in elevated venous pressures, systemic congestion, and low cardiac output. For Step 2 CK, it's a classic diagnosis often tested in patients with a history of tuberculosis, prior cardiac surgery, radiation therapy, or recurrent viral pericarditis.

? Pathophysiology and Etiology

• Chronic inflammation causes pericardial fibrosis, and in some cases, calcification

• The heart becomes "encased" in a non-distensible pericardial shell

• This leads to a loss of diastolic compliance and rapid, early ventricular filling followed by abrupt cessation

• Common etiologies include:

  • Tuberculosis (especially in developing countries)

  • Post-cardiac surgery

  • Radiation-induced fibrosis

  • Recurrent viral or idiopathic pericarditis

  • Uremia, malignancy, or autoimmune disease (less common)

Clinical Presentation

Patients typically present with symptoms resembling right-sided heart failure, including:

• Progressive fatigue

• Dyspnea on exertion

• Peripheral edema

• Ascites and abdominal discomfort from hepatic congestion

• Weight loss and cachexia in advanced cases

? Physical Examination Findings

Highly tested exam features that raise suspicion for constrictive pericarditis include:

• Elevated jugular venous pressure (JVP) with prominent y descent

• Kussmaul’s sign: paradoxical rise in JVP during inspiration

  • Distinguishes constrictive pericarditis from tamponade (where y descent is blunted)

• Pericardial knock: a sharp, high-pitched early diastolic sound caused by sudden halting of ventricular filling

• Hepatojugular reflux: sustained JVP elevation with abdominal pressure

• Ascites, hepatomegaly, and peripheral pitting edema

Diagnostic Workup

Diagnosis is based on a combination of clinical suspicion, imaging, and hemodynamic studies.

• Echocardiography:

  • May show thickened pericardium, septal bounce, or interventricular dependence

  • Useful but not always definitive

• CT scan or Cardiac MRI:

  • Superior for visualizing pericardial thickening (>4 mm) and calcifications

  • Helps distinguish constrictive pericarditis from restrictive cardiomyopathy

• Cardiac catheterization (definitive diagnostic tool):

  • Shows equalization of diastolic pressures in all chambers

  • Classic “square root sign” or dip-and-plateau waveform in ventricular pressure tracings

Management Strategy

Initial Symptom Relief:

• Diuretics may be used to relieve systemic congestion

  • Effective in early or mild cases

  • Caution: Excessive preload reduction may worsen cardiac output

Definitive Treatment:

• Surgical pericardiectomy is the only curative approach

  • Indicated in moderate to severe cases, especially if refractory to medical therapy

  • Outcomes are best when done before irreversible organ dysfunction occurs

Medical therapy alone is not sufficient for long-term control, particularly in cases of progressive disease.

Clinical Pearls

• Think constrictive pericarditis when a patient presents with signs of right-sided heart failure, clear lungs, and history of TB, radiation, or heart surgery

• Kussmaul’s sign and a pericardial knock are highly testable exam findings

• Always differentiate from restrictive cardiomyopathy (which affects myocardium, not pericardium)

• Cardiac catheterization confirms the diagnosis and distinguishes CP from other mimics

• Pericardiectomy is curative; early referral to surgery improves long-term outcomes

Acute Coronary Syndrome (ACS)

What Is ACS?

Acute coronary syndrome refers to a spectrum of clinical conditions caused by acute myocardial ischemia, most commonly due to rupture of an atherosclerotic plaque followed by thrombus formation in the coronary arteries. ACS includes three major clinical entities:

• Unstable angina (UA)

• Non–ST elevation myocardial infarction (NSTEMI)

• ST elevation myocardial infarction (STEMI)

These differ by the extent of myocardial damage and diagnostic findings, but they share a common pathophysiologic basis—partial or complete occlusion of coronary vessels.

Clinical Presentation

Patients classically present with:

• Retrosternal chest pain: described as pressure-like, squeezing, or crushing

• Pain may radiate to the left arm, neck, jaw, or back

• Often not relieved by rest or nitroglycerin

• Associated symptoms:

  • Shortness of breath (dyspnea)

  • Diaphoresis

  • Nausea or vomiting

  • Sense of impending doom

On USMLE Step 2 CK, suspect ACS in any patient over 40 with atypical chest pain, especially with cardiac risk factors (HTN, DM, smoking, hyperlipidemia, family history).

ECG and Troponin: How to Differentiate

Understanding ECG + cardiac enzymes is crucial for diagnosis and urgency of intervention.

STEMI

• ST-segment elevation in ≥2 contiguous leads

• May show new LBBB

• Indicates transmural infarction

• Immediate PCI required (within 90 minutes)

NSTEMI

• ST depression or T-wave inversion

• Positive troponins

• Indicates subendocardial infarction

Unstable Angina (UA)

• Same symptoms as NSTEMI

• Normal cardiac enzymes

• No myocardial necrosis — but still high risk

Note: Elevated troponins = infarction (NSTEMI or STEMI)
Normal troponins = unstable angina (if ischemic symptoms persist)

Initial Emergency Management: MONA-BASH

This easy-to-remember acronym guides your first steps:

• Morphine: for pain unrelieved by nitrates (used cautiously)

• Oxygen: only if patient is hypoxic (SpO₂ <90%)

• Nitroglycerin: for chest pain (avoid in RV infarct or hypotension)

• Aspirin: chew 325 mg immediately

Then initiate:

• Beta-blockers: unless contraindicated (e.g., bradycardia, shock)

• ACE inhibitors: especially if EF <40% or diabetes

• Statins: high-intensity (e.g., atorvastatin 80 mg)

• Heparin: LMWH or unfractionated for anticoagulation

Also add:

• P2Y12 inhibitors: clopidogrel, ticagrelor, or prasugrel
  (dual antiplatelet therapy = aspirin + P2Y12 blocker)

Reperfusion Therapy

For STEMI:

• PCI is preferred within 90 minutes (door-to-balloon time)

• If PCI unavailable: Fibrinolysis (e.g., alteplase) if <12 hrs from symptom onset and no contraindications

For NSTEMI/UA:

• No thrombolytics

• Perform risk stratification using:

  • TIMI Score

  • GRACE Score

• High-risk patients benefit from early invasive strategy (PCI within 24–48 hrs)

Key Pearls

• Chest pain + ST elevation = STEMI → urgent PCI

• Chest pain + ST depression/T-wave inversion + elevated troponins = NSTEMI

• Chest pain + normal troponins = unstable angina

• Never give nitrates in inferior wall MI with RV involvement → risk of hypotension

• Thrombolytics are only for STEMI, not NSTEMI or UA

Summary

• ACS = Unstable angina + NSTEMI + STEMI

• Key steps: ECG → cardiac enzymes → MONA-BASH → decide on PCI

• Dual antiplatelet therapy and statins are critical in all subtypes

• Step 2 CK will test your ability to recognize the type, initiate proper therapy, and determine timing of interventions

? Introduction to Tachyarrhythmias

Tachyarrhythmias are fast heart rhythms where the heart rate exceeds 100 beats per minute. The key to understanding these rhythms lies in identifying where the impulse originates in the heart.

Based on origin, tachyarrhythmias are divided into two broad categories:

• Supraventricular tachyarrhythmias: These originate above the bundle of His, typically in the atria or AV node.

• Ventricular tachyarrhythmias: These originate below the bundle of His, from the ventricular tissue.

But before jumping into types and ECG patterns, the very first step in approaching any tachyarrhythmia — whether in an exam or clinical practice — is to assess if the patient is stable or unstable.

? First Step: Hemodynamic Stability

Ask yourself this: Is the patient hemodynamically stable?

A patient is considered unstable if they exhibit any of the following:

• Low blood pressure (hypotension)

• Confused or altered mental status

• Chest pain or pressure

• Signs of shock like cold extremities or weak pulses

If even one of these is present, immediate synchronized cardioversion is the treatment of choice — regardless of the underlying rhythm.

If the patient is stable, meaning they are alert, perfusing well, and have no signs of end-organ compromise, then we proceed with detailed rhythm analysis on ECG.

? ECG-Based Approach in Stable Patients

Once you confirm stability, analyze the ECG by focusing on three parameters:

• QRS complex width: Narrow means <120 ms, wide means ≥120 ms.

• Rhythm regularity: Is it a regular or irregular rhythm?

• P waves: Are they present, absent, or abnormal in appearance or position?

This analysis will help you narrow down the specific arrhythmia.

? Supraventricular Tachyarrhythmias (SVTs)

Supraventricular tachycardias originate above the ventricles, so their QRS complexes are usually narrow. However, they can sometimes appear wide if there's a preexisting bundle branch block or aberrant conduction.

Major supraventricular tachyarrhythmias include:

Sinus Tachycardia
This is usually a response to an underlying stressor or physiological state such as fever, dehydration, pain, anxiety, anemia, or hyperthyroidism. The key management principle is that you should not treat the heart rate directly — instead, identify and correct the underlying cause. Once that’s resolved, the tachycardia typically settles on its own.

Atrial Fibrillation (AF)
AF presents as an irregularly irregular rhythm with no distinct P waves. Patients may report palpitations, fatigue, or dizziness, and some may have stroke as their first manifestation.
Management includes three steps:
First, rate control using beta-blockers or calcium channel blockers.
Second, rhythm control with antiarrhythmic drugs or electrical cardioversion if symptoms persist.
Third, assess the need for anticoagulation using the CHA₂DS₂-VASc score, as AF increases the risk of embolic strokes.

Atrial Flutter
This rhythm typically has a regular rate with classic sawtooth flutter waves, best seen in the inferior leads (II, III, aVF). The atrial rate is often around 300 beats per minute, with 2:1 AV block leading to a ventricular rate near 150. Like AF, atrial flutter is managed with rate control, rhythm control, and anticoagulation. In contrast to AF, radiofrequency ablation offers a highly effective curative option.

AV Nodal Reentrant Tachycardia (AVNRT)
This is the most common type of paroxysmal SVT. It occurs due to a reentrant circuit within the AV node involving dual pathways — a slow and a fast pathway.
Patients typically describe sudden-onset palpitations. The ECG shows a regular, narrow-complex tachycardia. P waves may be hidden or occur just after the QRS complex.
Management starts with vagal maneuvers, which attempt to interrupt AV nodal conduction. If ineffective, adenosine is the next step. It temporarily blocks AV node conduction and often terminates the arrhythmia. Beta-blockers or calcium channel blockers can also be used if needed.

AV Reentrant Tachycardia (AVRT)
This includes Wolff-Parkinson-White (WPW) syndrome, where an accessory pathway (Bundle of Kent) allows impulses to bypass the AV node. In sinus rhythm, WPW shows a short PR interval and a delta wave on ECG.
In WPW with atrial fibrillation, the accessory pathway can conduct impulses rapidly to the ventricles, leading to dangerously high ventricular rates or even ventricular fibrillation.
Never use AV nodal blockers like beta-blockers, calcium channel blockers, or digoxin in this scenario, as they may worsen the conduction through the accessory pathway.
Instead, the drug of choice is procainamide. In emergencies, cardioversion is used.

Multifocal Atrial Tachycardia (MAT)
Most commonly seen in elderly patients with chronic lung disease, especially COPD.
ECG shows an irregularly irregular rhythm with at least three distinct P wave morphologies.
Management focuses on treating the underlying pulmonary condition. Rate control may be achieved using non-dihydropyridine calcium channel blockers such as verapamil. Beta-blockers are usually avoided due to the risk of bronchospasm.

? Treatment Summary Based on Stability and ECG

Let’s consolidate the management strategies based on clinical scenarios — explained as lecture-style notes:

If the patient is unstable, such as having low BP, chest pain, or altered consciousness — your answer is immediate synchronized cardioversion.

If the patient is stable and the rhythm is regular with a narrow QRS, it’s likely AVNRT or a regular SVT. First try vagal maneuvers. If that fails, give adenosine to block AV nodal conduction.

If the rhythm is irregular, think about atrial fibrillation or MAT. Manage with rate control agents, and in case of AF, assess the need for anticoagulation.

If the QRS complex is wide in a stable patient, but the rhythm is from above (i.e., a supraventricular rhythm with aberrancy), manage according to the underlying SVT. But if it’s wide due to WPW with AF, avoid nodal blockers — use procainamide.

? Key Concepts to Remember

• Always assess clinical stability first. The management decision tree starts there.

• If WPW is present with AF, avoid AV nodal blocking drugs at all costs — this is a commonly tested trap.

• Learn to recognize ECG features: no P waves and irregular rhythm = AF; three different P wave shapes = MAT; delta wave = WPW.

• Adenosine is both diagnostic and therapeutic for regular narrow-complex tachycardias like AVNRT.

• Anticoagulation in AF is not optional — use the CHA₂DS₂-VASc score to decide.

• In MAT, treat the lungs, not the heart. The tachycardia is a reflection of pulmonary pathology.

Ventricular tachyarrhythmias are potentially life-threatening rhythm disturbances originating below the bundle of His and are a critical focus in USMLE Step 2 CK, especially in emergency and cardiology settings. These arrhythmias include ventricular tachycardia (VT), ventricular fibrillation (VF), and torsades de pointes, each associated with different clinical implications and management strategies. Monomorphic VT typically arises from a single irritable ventricular focus and presents as a regular, wide-complex tachycardia on ECG. It often occurs in the setting of prior myocardial infarction, structural heart disease, or cardiomyopathy, and may cause palpitations, syncope, hypotension, or even cardiac arrest. Polymorphic VT, including torsades de pointes, features a varying QRS morphology and is commonly linked to prolonged QT interval, which may be congenital or acquired (due to medications, electrolyte abnormalities like hypokalemia or hypomagnesemia). Ventricular fibrillation, on the other hand, is characterized by chaotic, disorganized electrical activity with no effective cardiac output, leading to sudden cardiac death if not treated immediately.

The initial step in management depends on hemodynamic stability. Unstable patients with hypotension, altered mental status, or chest pain should undergo immediate synchronized cardioversion for VT or defibrillation for VF or pulseless VT. Stable VT may be treated with antiarrhythmic medications such as amiodarone, procainamide, or lidocaine, depending on the clinical context. In torsades de pointes, the treatment of choice is IV magnesium sulfate, and in cases with bradycardia-induced QT prolongation, temporary pacing may be necessary.

Long-term management includes identifying and treating the underlying cause, such as ischemic heart disease, electrolyte disturbances, or medication toxicity, and determining the need for implantable cardioverter-defibrillator (ICD) placement, particularly in patients with sustained VT, prior VF, or ejection fraction ≤35%. Beta-blockers and catheter ablation may be used in select cases.

? Introduction to Myocardial Infarction

A myocardial infarction, or MI, refers to the death of cardiac muscle cells due to a sudden and sustained interruption of blood flow to a part of the heart. This interruption is most commonly caused by rupture of an atherosclerotic plaque, leading to thrombus (clot) formation inside a coronary artery.

When this artery gets blocked, oxygen cannot reach the myocardial tissue supplied by that vessel. As a result, the myocardium undergoes ischemic necrosis, which becomes irreversible if blood flow is not restored rapidly.

This is a true medical emergency that demands prompt recognition and immediate action. On exams like USMLE Step 2 CK, you are expected to identify MI clinically, interpret ECG findings, evaluate biomarkers like troponin, and know the step-by-step emergency management.

? Classification of Myocardial Infarction

Clinically, myocardial infarctions are divided into two major types:

ST-Elevation Myocardial Infarction (STEMI)
This form represents transmural ischemia, meaning the full thickness of the heart muscle is affected. It is seen on ECG as persistent ST-segment elevations in two or more contiguous leads. These patients require urgent reperfusion therapy — either by opening the artery mechanically using primary PCI (percutaneous coronary intervention) or, if PCI is unavailable within 90 minutes, by using fibrinolytics.

Non–ST-Elevation Myocardial Infarction (NSTEMI)
This is a subendocardial infarction, meaning the inner portion of the myocardium is affected. ECG may show ST-segment depressions or T-wave inversions, but no ST elevation. Diagnosis is confirmed by elevated cardiac biomarkers, especially troponins. Reperfusion is not emergent like in STEMI, but these patients still need prompt medical therapy and often undergo early invasive strategies depending on risk scores.

? Clinical Presentation of MI

Most patients describe the classic chest pain of MI as:

• Crushing or pressure-like in nature

• Localized to the center of the chest or left side

• Lasting more than 20 minutes

• May radiate to the left arm, jaw, neck, shoulder, or even back

• Often associated with diaphoresis (sweating), shortness of breath, nausea, and vomiting

However, not every patient fits this classic mold.

Atypical presentations are common in:

• Elderly patients

• Diabetics

• Females

In such cases, the symptoms may include:

• Unexplained fatigue

• Epigastric discomfort

• Lightheadedness

• Dyspnea without chest pain

On physical examination, we may find:

• An S4 gallop due to stiff left ventricle

• A new systolic murmur, possibly indicating mitral regurgitation from papillary muscle dysfunction

• Signs of heart failure, such as crackles in lungs, elevated jugular venous pressure, or peripheral edema

? Initial Diagnostic Workup

The initial evaluation of any suspected MI begins with the following:

Electrocardiogram (ECG)
Should be done within the first 10 minutes of arrival. Look for:

• ST elevations in STEMI

• ST depressions or T-wave inversions in NSTEMI

Cardiac Biomarkers
The most specific and sensitive is cardiac troponin I or T. It rises within 3–4 hours, peaks at 24 hours, and remains elevated for up to 10–14 days.

Risk Stratification Tools
In NSTEMI or unstable angina, calculate risk using scores like:

• TIMI score

• GRACE score

These help decide who needs early invasive treatment.

? Emergency Management: MONA-BASH Protocol

Once the diagnosis is suspected or confirmed, initiate immediate medical therapy, commonly remembered as MONA-BASH:

M – Morphine
Used only in patients with severe pain unresponsive to nitrates. Use cautiously, as it may lower blood pressure and mask symptoms.

O – Oxygen
Give only if the patient is hypoxic (SpO₂ < 90%), or has signs of respiratory distress. Routine oxygen is not beneficial and may be harmful.

N – Nitroglycerin
Sublingual nitroglycerin relieves ischemic pain. Avoid in right ventricular infarcts, hypotension, or recent use of phosphodiesterase-5 inhibitors (e.g., sildenafil).

A – Aspirin
Chewable aspirin should be given immediately, as it provides rapid antiplatelet action and reduces mortality.

B – Beta-blockers
Administer if the patient is hemodynamically stable and there are no contraindications such as bradycardia, hypotension, heart block, or acute decompensated heart failure.

A – ACE inhibitors
Especially beneficial in anterior MI, heart failure, or reduced ejection fraction. They prevent remodeling and improve long-term survival.

S – Statins
Initiate high-intensity statins as early as possible to stabilize plaques and reduce inflammation.

H – Heparin
Give anticoagulation using low-molecular-weight heparin (LMWH) or unfractionated heparin (UFH), especially in NSTEMI or when planning PCI.

?️ Long-Term Secondary Prevention

After the acute phase, your role is not over. The goal now is to prevent future cardiac events and optimize cardiac recovery. This includes:

• Dual antiplatelet therapy: aspirin + a P2Y12 inhibitor like clopidogrel, prasugrel, or ticagrelor

• Beta-blockers continued long-term

• ACE inhibitors or ARBs, especially in high-risk patients

• Statins, continued indefinitely

• Smoking cessation

• Glycemic control in diabetic patients

• Blood pressure optimization

• Cardiac rehabilitation, including supervised exercise and education programs

⚠️ Major Complications of MI

You must always be vigilant for life-threatening complications post-MI:

• Arrhythmias: such as ventricular tachycardia, ventricular fibrillation, or bradyarrhythmias

• Acute heart failure or pulmonary edema

• Cardiogenic shock due to extensive myocardial dysfunction

• Free wall rupture, leading to pericardial tamponade

• Ventricular septal rupture, presenting as a new harsh systolic murmur and heart failure

• Papillary muscle rupture, leading to acute mitral regurgitation and pulmonary edema

Each of these requires immediate recognition and intervention, often with surgical backup.

? Final Takeaway

• Think rapid diagnosis, structured protocol-based management, and recognition of complications.

• Learn the ECG patterns: ST elevation in STEMI; ST depression or T-wave inversion in NSTEMI.

• Know when to use PCI vs. thrombolysis, and how to manage based on availability and timing.

• Understand the indications and contraindications of each drug in the MONA-BASH sequence.

• Never forget secondary prevention — this is where long-term survival is determined.

? What Are Bradyarrhythmias?

Bradyarrhythmias refer to heart rhythm disturbances where the heart rate drops below 60 beats per minute. Now, this doesn’t always mean disease. Some people — like trained athletes — can have a resting heart rate below 60 and be completely healthy. That’s called physiologic bradycardia.

But when this slow rhythm becomes pathologic, it’s often due to either:

• A problem in the SA node — the heart’s natural pacemaker — where the impulse fails to start properly.

• A problem in the AV node or the His-Purkinje system — where the impulse gets delayed or blocked during transmission.

The clinical relevance? These rhythms can cause syncope, fatigue, dizziness, and even sudden cardiac arrest if not recognized and treated properly.

? Sinus Bradycardia

This is the most common type of bradyarrhythmia, and it originates in the sinoatrial (SA) node. The ECG shows normal P waves and PR intervals, just spaced further apart due to the slow rate.

Physiologic causes include:

• Well-conditioned athletes

• During sleep

• High vagal tone

Pathologic causes include:

• Hypothyroidism

• Hypothermia

• Increased intracranial pressure

• Inferior wall myocardial infarction (which may affect the SA node blood supply)

• Medications like beta-blockers, calcium channel blockers (like verapamil), and digoxin

Management depends on symptoms. If the patient is asymptomatic, no intervention is needed. But if symptoms like lightheadedness, syncope, or hypotension are present, treatment becomes urgent.

? Sick Sinus Syndrome (SSS)

Sick sinus syndrome is a more serious SA node dysfunction, usually seen in the elderly due to fibrosis of the SA node or after cardiac surgery.

This condition includes:

• Persistent sinus bradycardia

• Sinus pauses or sinus arrest

• Tachy-brady syndrome – where bradycardia alternates with episodes of supraventricular tachycardia, like atrial fibrillation

Symptoms include:

• Intermittent syncope

• Fatigue

• Palpitations due to the tachy episodes

• Confusion or memory complaints in the elderly

Diagnosis is based on ECG or Holter monitoring, especially if the rhythm disturbances are intermittent.

Treatment usually involves implantation of a permanent pacemaker, especially if symptoms are disabling.

? Atrioventricular (AV) Blocks

Now let’s explore AV blocks — where the electrical impulse is delayed or blocked as it travels from the atria to the ventricles.

There are three degrees of AV block:

? First-Degree AV Block

This is the mildest form and is often benign. Here, all the atrial impulses are conducted, but the conduction is slower than normal.

This shows up on ECG as a prolonged PR interval, more than 200 milliseconds, but every P wave is followed by a QRS complex.

This type is often seen in:

• Healthy individuals

• Athletes

• As a drug effect (e.g., beta-blockers, calcium channel blockers)

• Myocardial infarction

Since there is no dropped beat and no significant hemodynamic effect, no treatment is needed.

? Second-Degree AV Block

Now things get more interesting — and more dangerous.

Second-degree block means some atrial impulses are blocked, so not every P wave results in a QRS complex.

There are two types:

Mobitz Type I (Wenckebach)
This usually occurs at the level of the AV node. On ECG, we see:

• Progressively lengthening PR intervals

• Followed by a dropped QRS (i.e., a P wave with no following QRS)

It’s usually benign, especially if asymptomatic. Often seen in athletes, during sleep, or with increased vagal tone.

If the patient is asymptomatic, no intervention is needed. If symptomatic, pacing may be considered.

Mobitz Type II
This is a more serious form. The PR interval is constant, but some QRS complexes are suddenly dropped without warning.

It typically reflects a block in the His-Purkinje system, and is more likely to progress to complete heart block.

This type always warrants attention, even if the patient is asymptomatic.

The recommended treatment is permanent pacemaker implantation.

? Third-Degree (Complete) AV Block

This is the most severe form of AV block.

In this case, no impulses from the atria reach the ventricles. The atria and ventricles beat completely independently, a situation called AV dissociation.

The atrial rate is usually normal, but the ventricles are driven by a slow escape rhythm, often at a rate of 30–40 beats per minute. This may be junctional or ventricular in origin.

The ECG shows:

• Regular P waves

• Regular QRS complexes

• But no relationship between them

Clinically, these patients often present with:

• Syncope (often sudden and without warning)

• Severe fatigue

• Hypotension

• Heart failure symptoms

This is an emergency.

Management includes immediate temporary pacing, followed by permanent pacemaker implantation as definitive therapy.

? Diagnostic Evaluation

After ECG confirmation, further investigations should be considered to look for underlying or reversible causes. These include:

• Electrolyte disturbances, especially potassium, calcium, and magnesium

• Thyroid function tests to rule out hypothyroidism

• Ischemic workup, such as cardiac enzymes and coronary imaging if infarction is suspected

• Medication review to identify bradycardia-inducing drugs

• Holter monitoring for intermittent or episodic bradyarrhythmias

⚡ Acute Emergency Management

If a patient presents with symptomatic bradycardia, such as syncope, hypotension, or altered mental status, you need to act fast.

Initial steps include:

• Administering IV atropine as the first-line treatment

• If atropine is ineffective, consider temporary transcutaneous pacing

• Alternatives include IV dopamine or epinephrine infusions to support heart rate

In patients with persistent or recurrent symptomatic bradyarrhythmias, permanent pacemaker implantation is indicated.

? High-Yield Summary

• Bradyarrhythmia = heart rate < 60 bpm. Always assess for symptoms.

• Sinus bradycardia can be normal in athletes but may indicate pathology if symptomatic.

• Sick sinus syndrome causes alternating bradycardia and tachycardia; managed with pacing.

• First-degree AV block has prolonged PR but no dropped beats — benign.

• Mobitz type I shows progressive PR lengthening — usually benign.

• Mobitz type II shows sudden dropped beats without PR change — requires pacing.

• Third-degree AV block shows AV dissociation — needs immediate pacing.

• Atropine is the first step in managing symptomatic bradycardia; pacing is next if needed.

? Final Words

Bradyarrhythmias are not just “slow heart rates” — they’re windows into the integrity of the heart’s electrical system. A small PR delay may be harmless, but a missed beat or dissociated rhythm may be life-threatening.

Always correlate the ECG with the patient’s symptoms. Understand which blocks are benign, which are red flags, and when to call for emergency pacing.

The heart doesn’t always shout — sometimes it slows down silently. And if you listen carefully, your ECG skills can save a life.

❤️ Introduction: What Is an ECG?

The electrocardiogram, or ECG (also called EKG), is one of the most fundamental, non-invasive, and powerful diagnostic tools in clinical medicine. It records the heart’s electrical activity from multiple angles, providing real-time insight into cardiac rhythm, rate, conduction, ischemia, structural changes, electrolyte shifts, and drug effects.

? How Does an ECG Work?

A standard 12-lead ECG captures the heart’s electrical activity from six limb leads and six precordial (chest) leads. Together, they allow us to view the heart from multiple planes:

• Limb leads (I, II, III, aVR, aVL, aVF) provide a frontal plane view

• Precordial leads (V1–V6) give us the horizontal plane view

Each lead acts like a different “camera angle,” helping us visualize the electrical flow through the heart — from atrial depolarization to ventricular repolarization.

? Key Components of the ECG Tracing

Let’s break down what we actually see on the ECG:

P wave
This represents atrial depolarization — the electrical activation of the atria.

PR interval
This measures the time from atrial depolarization through AV nodal conduction to the ventricles. A normal PR interval is between 120–200 milliseconds.
A prolonged PR interval indicates first-degree AV block.

QRS complex
This reflects ventricular depolarization — a normal QRS duration is under 120 milliseconds.
A widened QRS suggests bundle branch blocks or ventricular rhythms.

T wave
This shows ventricular repolarization. Tall, peaked T waves may suggest hyperkalemia, while flattened or inverted T waves suggest ischemia or hypokalemia.

QT interval
This encompasses both depolarization and repolarization of the ventricles. A prolonged QT interval can lead to life-threatening arrhythmias like torsades de pointes, especially in the setting of certain medications or congenital syndromes.

? Estimating Heart Rate on ECG

To quickly calculate the heart rate on an ECG with a regular rhythm:

• Use the 300-150-100-75-60-50 method.

• Start at the first R wave on a bold grid line.

• Count large boxes between two R waves:

  • 1 box = 300 bpm

  • 2 boxes = 150 bpm

  • 3 boxes = 100 bpm

  • And so on...

For irregular rhythms, count the number of R-R intervals in a 6-second strip (30 large boxes) and multiply by 10.

? Rhythm Analysis: Is It Sinus?

Begin rhythm analysis with these questions:

• Is the rhythm regular or irregular?

• Is there a P wave before every QRS?

• Is every P wave followed by a QRS?

If yes, the rhythm is most likely sinus.

If there are no P waves and the rhythm is irregularly irregular, think atrial fibrillation.

If the P–QRS relationship is abnormal, consider AV blocks.

? Axis Determination

Cardiac axis refers to the net direction of electrical flow in the heart.

• Use leads I and aVF to estimate:

  • Both positive = normal axis

  • Lead I positive, aVF negative = left axis deviation

  • Lead I negative, aVF positive = right axis deviation

Left axis deviation can result from left anterior fascicular block, LVH, or inferior MI.
Right axis deviation may point to right heart strain, pulmonary embolism, or RVH.

? ST Segment Abnormalities

ST-segment elevations in at least two contiguous leads suggest acute myocardial infarction (STEMI). The location tells you the area of infarction:

• Leads II, III, aVF = inferior wall

• V1–V4 = anterior wall

• I, aVL, V5–V6 = lateral wall

ST depressions and T wave inversions may represent:

• Myocardial ischemia

• Reciprocal changes in STEMI

• Electrolyte imbalances

• Digoxin effect (downsloping ST depression)

⚡ Electrolyte Abnormalities on ECG

Hyperkalemia
Look for peaked T waves, widened QRS, and eventual sine wave pattern in severe cases.

Hypokalemia
Shows flattened T waves, prominent U waves, and increased risk for ventricular arrhythmias.

Hypocalcemia
Causes prolonged QT interval

Hypercalcemia
Leads to shortened QT interval

? Bundle Branch Blocks

Right Bundle Branch Block (RBBB)

• Shows an RSR' pattern ("rabbit ears") in V1

• Wide S wave in leads I and V6

• Often benign but may be seen in pulmonary embolism or right heart strain

Left Bundle Branch Block (LBBB)

• Broad, notched R wave in leads I, V5, and V6

• Absence of Q waves in left-sided leads

• Associated with underlying structural heart disease

• New LBBB in chest pain should raise suspicion for acute MI

? AV Conduction Blocks – ECG Clues

First-degree AV block
Every P wave is followed by a QRS, but the PR interval is consistently prolonged (>200 ms)

Second-degree AV block Type I (Wenckebach)
Progressive PR prolongation followed by a dropped QRS complex. Usually benign.

Second-degree AV block Type II (Mobitz II)
PR interval remains constant, but intermittent dropped beats occur without warning — more dangerous, can progress to complete block.

Third-degree AV block (complete heart block)
P waves and QRS complexes occur independently with no relationship. Requires urgent pacing.

? Other Morphologic Clues

P wave abnormalities

• Tall P wave in lead II = right atrial enlargement

• Bifid P wave in lead II = left atrial enlargement (P mitrale)

Q waves

• Pathologic Q waves (deep and wide) may indicate prior MI

QRS widening

• A QRS duration over 120 ms suggests intraventricular conduction delay, bundle branch blocks, or ventricular origin rhythms

? Final Takeaways

• ECG interpretation is not just pattern recognition, but clinical correlation.

• Always start with rate, rhythm, axis, and intervals.

• Know the classic patterns for ischemia, infarction, electrolytes, and drug effects.

• Be alert for life-threatening clues like ST elevation, wide QRS in hyperkalemia, or AV dissociation in complete heart block.

• ECG interpretation is often the first and fastest clue in emergency settings — your ability to read it saves both exam questions and real lives.

? Interpreting Chamber Enlargement & Hypertrophy on ECG – Complete Clinical Lecture

? Why Is This Important?

Understanding chamber enlargement and hypertrophy on ECG is more than just identifying tall waves or deep complexes — it’s about recognizing pressure or volume overload affecting specific cardiac chambers.

When the atria or ventricles enlarge, they alter the timing, direction, and magnitude of electrical depolarization. These changes are often visible on a standard 12-lead ECG, long before structural changes are seen on echocardiography.

Mastering these patterns allows you to detect early cardiac remodeling in diseases like hypertension, valvular heart disease, pulmonary hypertension, or congenital heart defects. For USMLE Step 2 CK, this is a core topic — often tested in clinical vignettes featuring dyspnea, murmurs, or ECG-based questions.

? Left Atrial Enlargement (LAE)

Left atrial enlargement usually reflects pressure overload in the left atrium. Common causes include:

• Mitral stenosis or regurgitation

• Chronic systemic hypertension

• Aortic valve disease

• Left ventricular dysfunction

How does it appear on ECG?

• In lead II, the P wave is broad and bifid — that is, notched like an "M". This is known as P mitrale.

• The P wave duration is greater than 120 milliseconds.

• In lead V1, you’ll often see a biphasic P wave — the initial positive component from right atrial activation, and the terminal negative component is deep and wide, reflecting delayed activation of an enlarged left atrium.

These findings result from prolonged conduction through a stretched left atrium.

? Right Atrial Enlargement (RAE)

Right atrial enlargement reflects volume or pressure overload of the right atrium. Causes include:

• Pulmonary hypertension

• Chronic obstructive lung disease (COPD)

• Tricuspid stenosis or regurgitation

• Pulmonary embolism

• Congenital defects like ASD

ECG Features:

• In lead II, the P wave becomes tall and peaked, often greater than 2.5 mm in amplitude — this is called P pulmonale.

• In lead V1, the initial positive deflection of the P wave is tall, as the right atrium depolarizes first and dominates the waveform.

Unlike LAE, the P wave is narrow in width but tall in height.

? Left Ventricular Hypertrophy (LVH)

LVH is caused by conditions that chronically increase afterload or workload on the left ventricle. These include:

• Systemic hypertension (most common)

• Aortic stenosis

• Hypertrophic cardiomyopathy

• Coarctation of the aorta

The hypertrophied left ventricle generates greater electrical force, especially directed posteriorly and laterally, which gets reflected in lateral and precordial leads.

Diagnostic Criteria – Most Commonly Used:

• Sokolow-Lyon Index:
  Add the S wave in V1 and the R wave in V5 or V6.
  If the total is ≥ 35 mm, it suggests LVH.

• R wave in lead aVL:
  If it is ≥ 11 mm, this is another supportive sign of LVH.

Additional clues:

• Left axis deviation — the electrical axis shifts leftward.

• Strain pattern — look for ST segment depression and T wave inversion in the lateral leads (I, aVL, V5–V6). This reflects subendocardial ischemia due to increased wall stress.

• Widened QRS may be present in advanced hypertrophy due to conduction delay.

? Right Ventricular Hypertrophy (RVH)

RVH occurs when the right ventricle is under chronic strain. Common etiologies include:

• Pulmonary hypertension

• Pulmonary embolism

• Chronic lung disease (cor pulmonale)

• Congenital heart diseases like Tetralogy of Fallot or VSD

ECG Findings in RVH:

• Right axis deviation — the QRS axis shifts to the right (> +90 degrees).

• In lead V1, you’ll see a dominant R wave (R > S) — this is unusual and should raise suspicion for RVH.

• In leads V5 and V6, there will be a deep S wave, as depolarization shifts away from the left chest leads.

• May be accompanied by RAE features and even incomplete or complete RBBB, due to conduction delay in the hypertrophied right bundle.

? Biventricular Hypertrophy

When both ventricles are enlarged, the ECG may show overlapping features of both LVH and RVH. However, one chamber’s electrical dominance may mask the features of the other.

Clues suggesting biventricular involvement:

• ECG shows criteria for both LVH and RVH

• Axis may be normal or indeterminate

• Precordial leads show both prominent R waves (V1) and deep S waves (V6)

• Can occur in congenital heart disease, combined valve lesions, or advanced cardiomyopathies

? Clinical Pearls for USMLE Step 2 CK

• Think P pulmonale = RAE = tall P in II

• Think P mitrale = LAE = bifid P in II, terminal negative P in V1

• Sokolow-Lyon Index is a high-yield LVH criterion — memorize it:
  S in V1 + R in V5 or V6 ≥ 35 mm

• RVH = right axis + R > S in V1 + deep S in V6

• Don’t forget to correlate ECG with the clinical picture — dyspnea, murmurs, hypertension, or cyanotic spells.

? Final Summary

Chamber enlargement and ventricular hypertrophy leave distinct footprints on the ECG. These aren’t just patterns to memorize — they reflect long-standing pressure or volume overload that has caused the heart to structurally remodel itself.

Your job as a clinician is to decode these patterns and match them with the underlying condition — whether it’s mitral stenosis, pulmonary hypertension, or left-sided hypertrophy from chronic hypertension.

Learning these ECG signs isn’t just for exams — they allow you to detect disease early, guide further imaging like echocardiography, and initiate timely management.