Polymorphic VT shows multiple ventricular foci with varying QRS complexes. Torsades de pointes is a specific form of PVT with QT prolongation. Bidirectional VT is associated with digoxin toxicity. First described by François Dessertenne in 1966
Wellens Syndrome shows biphasic or inverted T waves in V2-3 with recent chest pain resolution. Highly specific for critical LAD stenosis. Pattern usually present in pain-free state. Two types exist: Type A (25%) with biphasic T waves and Type B (75%) with deep inversion
Sinus rhythm begins at sinus node, necessary but not sufficient for normal heart activity. ECG shows normal P waves with typical P vector between +50° and +80°. Normal sinus rhythm includes tachycardia, bradycardia, and arrhythmia
QT prolongation measures delayed ventricular repolarization on ECG. Drugs inhibit rapid delayed rectifier potassium current protein. Normal QTc values increase from 400ms in infancy to 480ms after puberty
WPWS is a heart disorder affecting 0.1-0.3% of population. Named after Louis Wolff, John Parkinson, and Paul Dudley White. Caused by accessory pathway bypassing atrioventricular node
ECG records heart's electrical activity through repeated cardiac cycles. Electrodes placed on skin detect small electrical changes during heartbeat. Normal ECG shows P wave, QRS complex, T wave, and U wave