AF Electrophysiology & ECG Interpretation 3

Question 1

What is the standard method for estimating ventricular rate in atrial fibrillation on a rhythm strip?

Accepted Answer

Counting QRS complexes in a 6-second strip and multiplying by 10

Answer

Measuring the PP interval and calculating atrial frequency

Answer

Measuring the PR interval and dividing by 0.2

Answer

Dividing 300 by the number of large boxes between QRS complexes

Question 2

Which ECG monitoring modality is most appropriate for detecting intermittent paroxysmal AF in an outpatient setting?

Accepted Answer

24-hour Holter monitor

Answer

Standard 12-lead ECG in the clinic

Answer

Single 30-second rhythm strip

Answer

Exercise stress test alone

Question 3

An implantable loop recorder (ILR) is MOST indicated in a patient with:

Accepted Answer

Unexplained stroke (cryptogenic) suspected to be AF-related

Answer

Known permanent AF requiring rate control adjustment

Answer

Symptomatic persistent AF requiring ablation planning

Answer

AF with rapid ventricular response requiring urgent cardioversion

Question 4

After successful electrical cardioversion of atrial fibrillation, which ECG finding confirms restoration of sinus rhythm?

Accepted Answer

Return of distinct P waves preceding each QRS complex

Answer

Widening of the QRS complex beyond 0.12 seconds

Answer

Disappearance of all ECG waveforms temporarily

Answer

Development of right bundle branch block morphology

Question 5

In atrial fibrillation, which ECG lead is the standard choice for performing a rhythm strip assessment?

Accepted Answer

Lead II

Answer

Lead aVR

Answer

Lead V1

Answer

Lead V6

Question 6

A pre-excitation pattern (short PR interval and delta wave) visible during sinus rhythm should raise concern if the patient develops AF because:

Accepted Answer

Rapid conduction via the accessory pathway can precipitate ventricular fibrillation

Answer

Delta waves prevent the AV node from conducting any impulses

Answer

AF will automatically convert to ventricular fibrillation within minutes

Answer

The short PR indicates underlying complete heart block

Question 7

What ECG finding in AF indicates the ventricular rate is adequately controlled with rate-control therapy?

Accepted Answer

Heart rate between 60–100 bpm at rest with persistent irregular rhythm

Answer

Return of regular P waves on the ECG tracing

Answer

Complete resolution of fibrillatory waves from the baseline

Answer

QRS complex narrowing to less than 0.08 seconds