ECG Rhythm Interpretation Flashcards

What are the hallmark ECG findings of atrial fibrillation?

Answer: Irregularly irregular rhythm with absent P waves and fibrillatory baseline

Atrial fibrillation shows an irregularly irregular ventricular rhythm (varying R-R intervals), absence of organized P waves replaced by fibrillatory baseline activity, and usually narrow QRS complexes.

How do you differentiate between ventricular tachycardia and supraventricular tachycardia with aberrancy?

Answer: VT shows AV dissociation, fusion/capture beats, and concordance; SVT with aberrancy usually has preceding P waves

Key VT indicators include AV dissociation, fusion/capture beats, extreme axis deviation, and QRS concordance. SVT with aberrancy typically shows preceding atrial activity and a bundle branch block pattern.

What does ST elevation on an ECG indicate?

Answer: Acute myocardial injury, most commonly from coronary artery occlusion causing a STEMI

ST elevation typically indicates acute myocardial injury from coronary artery occlusion (STEMI), though it can also occur in pericarditis, early repolarization, left ventricular aneurysm, and other conditions.

What are the three degrees of AV heart block?

Answer: First degree (prolonged PR), second degree (dropped beats), and third degree (complete dissociation between P waves and QRS)

First degree shows prolonged PR interval (>0.20s), second degree has intermittently dropped QRS complexes (Mobitz I with progressive PR prolongation, Mobitz II with sudden drops), and third degree shows complete AV dissociation.

What ECG findings suggest hyperkalemia?

Answer: Tall peaked T waves, widened QRS, flattened P waves, and potentially sine wave pattern

Hyperkalemia produces progressive ECG changes: peaked T waves, PR prolongation, P wave flattening, QRS widening, and eventually a sine wave pattern that can degenerate into ventricular fibrillation.

What is the significance of a prolonged QT interval?

Answer: It increases the risk of life-threatening ventricular arrhythmias, particularly Torsades de Pointes

Prolonged QT interval (>0.46s in men, >0.47s in women) indicates delayed ventricular repolarization, increasing vulnerability to Torsades de Pointes, a potentially fatal polymorphic ventricular tachycardia.