ECC Cardiac Rhythm Recognition & Interpretation 3

Question 1

In complete (third-degree) heart block, what is the relationship between P waves and QRS complexes?

Accepted Answer

P waves and QRS complexes occur completely independently with no fixed relationship

Answer

Complete heart block (third-degree AV block) features total AV dissociation — the atria and ventricles are controlled by separate independent pacemakers.

Question 2

Which combination of ECG findings is pathognomonic for Wolff-Parkinson-White (WPW) syndrome?

Accepted Answer

Short PR interval (< 0.12 s) with a delta wave

Answer

WPW syndrome is defined by a short PR interval and a delta wave (slurred QRS upstroke) caused by ventricular pre-excitation via an accessory bypass tract.

Question 3

An ECG shows a regular rhythm with sawtooth-shaped negative deflections at 300 bpm and a ventricular rate of 150 bpm. What is the most likely rhythm?

Accepted Answer

Atrial flutter with 2:1 AV conduction

Answer

Atrial flutter produces regular sawtooth flutter waves at approximately 300 bpm; with 2:1 AV conduction, the ventricular rate is 150 bpm.

Question 4

Which ECG change is most characteristic of hyperkalemia in an emergency setting?

Accepted Answer

Peaked (tall, narrow) T waves with progressive QRS widening

Answer

Hyperkalemia first produces peaked T waves (tall, narrow, symmetric), and as levels rise further the QRS widens, which can progress to a sine-wave pattern and cardiac arrest.

Question 5

Pulseless electrical activity (PEA) is best described as which of the following?

Accepted Answer

Organized electrical activity on ECG with no palpable pulse

Answer

PEA is defined as any organized cardiac rhythm on ECG without a palpable pulse, indicating mechanical failure despite preserved electrical activity.

(ECC) Emergency Cardiovascular Care Certification Practice Test

(ECC) Emergency Cardiovascular Care Certification Practice Test

ECC Cardiac Rhythm Recognition & Interpretation 3