ECG Anatomy Series

ECG heart rate calculation methods — 300 rule, 1500 rule, 6-second method, tachycardia, bradycardia, irregular rhythms, and clinical significance.

Mean frontal plane QRS vector interpretation — normal and pathological axis deviations, systematic determination methods, and clinical correlations.

Atrial depolarization and P wave morphology — normal variants, abnormalities, atrial enlargement patterns, and ectopic atrial rhythms.

Initial ventricular depolarization and MI marker — physiologic vs pathologic Q waves, criteria, MI localization, and Q wave mimics.

Ventricular depolarization and R wave progression — normal amplitude, dominant R in V1/aVR, poor progression, posterior MI, and RVH.

Terminal ventricular depolarization — deep S waves in LVH/RVH, Sokolow-Lyon criteria, bundle branch patterns, and S1S2S3 pattern.

Ventricular repolarization morphology — tall/peaked T waves, inversions, Wellens syndrome, hyperacute changes, and electrolyte effects.

Isoelectric baseline between atrial and ventricular depolarization — PR depression in pericarditis, atrial infarction, and STEMI differentiation.

AV conduction time measurement — normal PR duration, first-degree AV block, short PR syndromes, and preexcitation patterns.

Ventricular depolarization patterns — QRS duration/morphology, bundle branch blocks, hypertrophy criteria, and conduction delays.

Ventricular repolarization abnormalities — ST elevation/depression, T wave inversions, ACS patterns, and repolarization variants.

Ventricular systole duration — QT measurement, QTc correction, prolonged/shortened QT causes, Torsades risk, and drug effects.

Supraventricular arrhythmias — atrial fibrillation, atrial flutter, MAT, atrial tachycardia, and PACs with diagnostic criteria.

Life-threatening ventricular arrhythmias — VT, VF, PVCs, AIVR, and Brugada criteria for VT diagnosis.

AV blocks and intraventricular conduction delays — 1st/2nd/3rd-degree AV blocks, RBBB, LBBB, fascicular blocks, and pacing implications.