All You Need To Know About ECG exam review

Identify how ecg records the heart's electrical activity with skin electrodes, how leads are derived, and v1–v6 chest placements with limb electrode mnemonics cloud over grass and smoke over fire.

Explore the 12-lead ECG as a camera viewing the heart from multiple angles, detailing bipolar limb leads, unipolar augmented limb leads, and V1-V6 chest leads across septal to inferior surfaces.

Understand how depolarization and repolarization produce upward or downward ECG deflections based on lead orientation and the camera position, and read the ECG paper by time and amplitude scales.

The P wave represents both atria depolarization; right atrial enlargement yields tall peaks, left atrial enlargement yields broad notched waves. Absent P waves indicate atrial fibrillation, atrial flutter, supraventricular tachycardia.

Learn how the PR interval reflects conduction from the SA node through the AV node to the ventricle, and identify delta wave pre-excitation, Wolff-Parkinson-White, and first degree AV block.

Identify the QRS complex as ventricular depolarization with a normal width of 1–2.5 small boxes, and differentiate origin by width: narrow (<3 boxes) indicates supra-ventricular, wide (>3 boxes) indicates ventricular.

Identify the ST segment as the end of ventricular depolarization and the start of repolarization, usually isoelectric, with depression indicating ischemia or hypokalemia and elevation indicating infarction or pericarditis.

The t wave represents ventricular repolarization; normally upright and under one big box, but tall peaked in hyperkalemia, inverted in ischemia or conduction block, and flat in hypokalemia.

Explore the QT interval, from the start of the QRS to the end of the T wave, reflecting ventricular depolarization and repolarization, 0.36–0.44 seconds, prolongation raises torsades de pointes risk.

Measure the R-R interval between QRS complexes to distinguish regular from irregular rhythm, noting equal distances for regular rhythm and varying distances, such as three vs six boxes.

Measure ECG heart rate by rhythm: regular rhythms use 300 divided by large boxes between R waves; irregular rhythms use QRS count on a six-second strip, times ten.

The heart axis is direction of electrical activity, normally -30 to +90 degrees. Left axis deviation signals left ventricular hypertrophy; right axis deviation signals COPD or right ventricular hypertrophy.

Normal sinus rhythm arises from the SA node in the right atrium, with a regular 60–100 bpm rate and upright P waves, and a narrow QRS with isoelectric ST segment.

Explore how sinus tachycardia and sinus bradycardia differ by rate and SA node impulse on the ECG. Treat underlying causes; use atropine or pacemaker for symptomatic bradycardia.

Atrial flutter arises from an irritated atrial focus driving a circular impulse at 250–300 bpm, creating sawtooth P waves with narrow QRS and 3:1 conduction.

Atrial fibrillation arises from multiple atrial foci firing over 400 bpm, creating irregular rhythm with absent P waves and narrow QRS, treated by synchronized cardioversion or rate control with warfarin.

Explore svt, arising above the ventricles from the av node, with 150–250 bpm, narrow qrs, and hidden p waves; treat with vagal maneuvers, adenosine, or ablation.

Review atrial arrhythmias by analyzing rhythm regularity, heart rate, P waves, and QRS complexes to diagnose supraventricular tachycardia.

ventricular tachycardia originates from the ventricle, producing wide QRS and a fast rate. Causes include ischemia, electrolyte imbalances; treat unstable ventricular tachycardia with synchronized cardioversion, amiodarone, lidocaine, or procainamide.

Learn how prolonged qt interval causes torsades de pointes via r on t phenomenon, polymorphic ventricular tachycardia, and treatments like electrolyte correction, stopping offending agents, pacing, and defibrillation.

Ventricular fibrillation arises from multiple ventricular foci firing chaotically, creating waves that may progress to asystole. Treat with CPR, defibrillation, and antiarrhythmics, with epinephrine or vasopressin and Hs and Ts.

Review ventricular arrhythmias through an ekg exam, focusing on a wide, bizarre QRS twisting around the baseline, and diagnosing torsades de pointes.

Understand AV block, its causes including myocardial infarction and drugs (digoxin, beta blockers, calcium channel blockers), and its classification into first, second (Mobitz type I and II), and third degree.

Identify first degree AV block as a delay at the AV node that prolongs the PR interval on the ECG. If asymptomatic, treat none and monitor, correcting the underlying cause.

Mobitz type 1, a second-degree AV block, shows progressive PR prolongation due to fatigued AV node, eventually dropping a QRS. Treat underlying cause if asymptomatic; atropine or pacemaker as needed.

Explore how Mobitz type II second degree AV block arises from His-Purkinje failure to conduct, causing occasional missing QRS with a normal PR interval and treatment with atropine and pacemaker.

Identify third degree av block as a complete heart block where av conduction fails, the ventricle paces itself slowly, and the ekg shows no p–qrs relation, treated by pacemaker.

Review AV block patterns on ECG: first-degree with PR prolongation, Mobitz type I with progressively lengthening PR, Mobitz type II with sudden QRS drop, and third-degree with no P-QRS relation.

Diagnose asystole as a flatline with no electrical activity, recognize pulseless electrical activity means the heart fails to contract despite signals, and treat with cardiopulmonary resuscitation and epinephrine or atropine.

Distinguish non shockable rhythms like asystole and pulseless electrical activity from shockable rhythms, where synchronized shocks target QRS peak and unsynchronized shocks are used for chaotic rhythms with QRS absent.

Celebrate completing this ecg exam review course; the instructor simplified ekg concepts with many exercises for both passive and active learning, and invites feedback.

Explore Mobitz type 1 and Mobitz type 2 AV blocks, atrial flutter, and the deflection patterns on the ECG, along with common recording mistakes in ECG exams.