CCRN Cardiac Rhythm Interpretation and Management

Question 1

An ICU patient's monitor shows a regular rhythm at 150 bpm with narrow QRS complexes and a classic sawtooth baseline pattern. What is the most likely rhythm?

Accepted Answer

Atrial flutter with 2:1 block

Answer

Sinus tachycardia

Answer

Junctional tachycardia

Answer

Atrial fibrillation

Question 2

Which ECG change is the earliest indicator of hyperkalemia in a critically ill patient?

Accepted Answer

Peaked (tall, narrow) T waves

Answer

Widened QRS complex

Answer

Sine wave pattern

Answer

Flat or absent P waves

Question 3

Which ECG characteristic definitively identifies a third-degree (complete) AV block?

Accepted Answer

Completely independent atrial and ventricular rates with no relationship

Answer

PR interval consistently greater than 0.20 seconds

Answer

Progressive PR prolongation followed by a dropped QRS complex

Answer

Alternating conducted and non-conducted P waves

Question 4

A normal PR interval on a standard ECG measures:

Accepted Answer

0.12–0.20 seconds

Answer

0.06–0.10 seconds

Answer

0.20–0.24 seconds

Answer

0.24–0.30 seconds

Question 5

A patient's rhythm strip shows an irregularly irregular ventricular response, absent distinct P waves, and an estimated atrial activity rate of 400–600 bpm. What is this rhythm?

Accepted Answer

Atrial fibrillation

Answer

Atrial flutter

Answer

Multifocal atrial tachycardia

Answer

Junctional tachycardia

Question 6

What is the normal range for QRS complex duration in an adult?

Accepted Answer

0.06–0.12 seconds

Answer

Less than 0.06 seconds

Answer

0.12–0.16 seconds

Answer

0.16–0.20 seconds

Question 7

Which ECG finding most strongly differentiates ventricular tachycardia from supraventricular tachycardia with aberrant conduction?

Accepted Answer

AV dissociation visible on the rhythm strip

Answer

Heart rate greater than 150 bpm

Answer

Hemodynamic instability in the patient

Answer

Left bundle branch block morphology of the QRS