ECG Rhythm Analysis 3

Question 1

What is the intrinsic escape rate of the ventricular (His-Purkinje) pacemaker cells?

Accepted Answer

20–40 bpm

Answer

Ventricular escape pacemakers fire at 20–40 bpm, which is the slowest intrinsic rate in the conduction hierarchy.

Question 2

On telemetry, a patient's rhythm suddenly shows fine, chaotic baseline deflections with no identifiable P waves, QRS complexes, or T waves. What is this rhythm?

Accepted Answer

Ventricular fibrillation

Answer

Ventricular fibrillation (VF) produces disorganized chaotic waveforms with no discernible cardiac complexes and requires immediate defibrillation.

Question 3

A junctional rhythm with a rate of 60–100 bpm is best described as:

Accepted Answer

Accelerated junctional rhythm

Answer

When the AV junction fires at 60–100 bpm (faster than its intrinsic 40–60 bpm but not tachycardia), it is called an accelerated junctional rhythm.

Question 4

Which characteristic best identifies atrial fibrillation on an ECG?

Accepted Answer

Irregularly irregular rhythm with absent distinct P waves

Answer

Atrial fibrillation is characterized by an irregularly irregular ventricular response and chaotic atrial activity replacing distinct P waves.

Question 5

A PVC that falls on the T wave of the preceding beat is clinically dangerous because it may:

Accepted Answer

Trigger ventricular fibrillation (R-on-T phenomenon)

Answer

The R-on-T phenomenon occurs when a PVC fires during the vulnerable period of ventricular repolarization, potentially precipitating VF.

ECG Certification Practice Test

ECG Certification Practice Test

ECG Rhythm Analysis 3