AF Electrophysiology & ECG Interpretation

Question 1

What is the characteristic ECG finding that distinguishes atrial fibrillation from normal sinus rhythm?

Accepted Answer

Absence of distinct P waves with an irregularly irregular ventricular rhythm

Answer

AF is characterized by absent organized P waves replaced by chaotic fibrillatory waves and an irregularly irregular ventricular rhythm.

Question 2

What is the typical atrial rate during atrial fibrillation?

Accepted Answer

350–600 impulses per minute

Answer

In AF, the atria fire chaotically at 350–600 impulses per minute, far exceeding any organized atrial rhythm.

Question 3

In atrial fibrillation, the RR intervals on the ECG are best described as:

Accepted Answer

Irregularly irregular with no repeating pattern

Answer

The hallmark of AF is irregularly irregular RR intervals, meaning there is no consistent repeating pattern to ventricular activation.

Question 4

Which ECG lead is most useful for identifying fibrillatory (f) waves in atrial fibrillation?

Accepted Answer

Lead V1

Answer

Lead V1, positioned closest to the right atrium, best displays fibrillatory waves because it directly captures atrial electrical activity.

Question 5

In uncomplicated atrial fibrillation, the QRS complex width is typically:

Accepted Answer

Between 0.08–0.12 seconds (narrow)

Answer

Without an aberrant conduction pathway or bundle branch block, ventricular depolarization follows normal pathways in AF, producing a narrow QRS.

(AF) Atrial Fibrillation Certification Practice Test