ACLS ACLS Cardiac Rhythms & ECG Interpretation

Question 1

On an ECG, what characteristic finding confirms ventricular fibrillation (VF)?

Accepted Answer

Chaotic, disorganized electrical activity with no identifiable QRS complexes

Answer

VF appears as chaotic, irregular waveforms with no identifiable P waves, QRS complexes, or T waves.

Question 2

Which ECG rhythm is characterized by a regularly irregular pattern with no P waves and a sawtooth baseline at ~300 bpm?

Accepted Answer

Atrial flutter

Answer

Atrial flutter produces characteristic sawtooth flutter waves at ~300 bpm, most visible in leads II, III, aVF, and V1.

Question 3

In ACLS, pulseless electrical activity (PEA) is best described as:

Accepted Answer

An organized ECG rhythm without a palpable pulse

Answer

PEA is defined as organized electrical activity on the monitor with absent pulse, requiring CPR and investigation of reversible causes.

Question 4

What is the hallmark ECG finding of first-degree AV block?

Accepted Answer

PR interval > 200 ms with every P wave followed by a QRS

Answer

First-degree AV block shows a consistently prolonged PR interval (>200 ms) with every P wave followed by a QRS complex.

Question 5

Which type of second-degree AV block is considered more dangerous and often requires pacing?

Accepted Answer

Mobitz Type II

Answer

Mobitz Type II block features a fixed PR interval with sudden dropped beats and can progress to complete heart block without warning.

ACLS Practice Test