AF Electrophysiology & ECG Interpretation 2

Question 1

What primary electrophysiological mechanism underlies atrial fibrillation?

Accepted Answer

Multiple reentrant electrical wavelets within the atria

Answer

Single-focus rapid automaticity in the SA node

Answer

Enhanced automaticity from the AV node

Answer

Complete block of conduction at the Bundle of His

Question 2

A patient with Wolff-Parkinson-White (WPW) syndrome who develops atrial fibrillation is at risk for which dangerous ECG pattern?

Accepted Answer

Wide, bizarre QRS complexes due to rapid accessory pathway conduction

Answer

Regular narrow complex tachycardia at 150 bpm

Answer

Complete AV block with ventricular escape rhythm

Answer

Sinus bradycardia with prolonged QT interval

Question 3

Which finding best distinguishes multifocal atrial tachycardia (MAT) from atrial fibrillation on ECG?

Accepted Answer

MAT displays at least 3 distinct P wave morphologies with varying PR intervals

Answer

MAT has wider QRS complexes than AF

Answer

MAT has an irregularly irregular rhythm while AF is regular

Answer

MAT has a consistently faster ventricular rate than AF

Question 4

How would you describe the f-waves (fibrillatory waves) characteristic of atrial fibrillation?

Accepted Answer

Chaotic, irregular undulations varying in amplitude and morphology

Answer

Regular, organized waves at exactly 300 bpm

Answer

Tall, symmetrical peaked waves following each QRS

Answer

Flat, isoelectric baseline between QRS complexes

Question 5

'Coarse' atrial fibrillation is differentiated from 'fine' atrial fibrillation on ECG by:

Accepted Answer

Coarse AF has f-waves greater than 1mm in amplitude

Answer

Coarse AF has a regular ventricular rhythm

Answer

Fine AF has more visible and organized P waves

Answer

Coarse AF always shows wide QRS complexes

Question 6

A patient presents with an irregularly irregular rhythm, no visible P waves, and a ventricular rate of 82 bpm. Which diagnosis is most consistent?

Accepted Answer

Atrial fibrillation with controlled ventricular rate

Answer

Sinus arrhythmia

Answer

Second-degree AV block Mobitz type I

Answer

Junctional tachycardia

Question 7

In atrial fibrillation with a coexisting right bundle branch block (RBBB), the ECG will show:

Accepted Answer

Irregularly irregular rhythm with wide QRS showing RBBB morphology

Answer

Normal narrow QRS with irregularly irregular rhythm

Answer

Regular rhythm with wide QRS and RSR' pattern in V1

Answer

Absent QRS complexes with only f-waves visible