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

Every P wave is conducted with a markedly prolonged PR interval

Answer

There is a fixed 3:1 ratio of P waves to QRS complexes

Answer

P waves are buried immediately after each QRS complex

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

Prolonged PR interval with wide slurred QRS

Answer

ST elevation in lateral leads with tall R waves

Answer

Biphasic P waves in lead II with right axis deviation

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 fibrillation with rapid ventricular response

Answer

Ventricular tachycardia at 150 bpm

Answer

Sinus tachycardia with first-degree AV block

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

Shortened PR interval with prominent U waves

Answer

ST elevation in anterior leads with Q waves

Answer

Prolonged QT interval with T-wave inversions

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

No electrical activity on ECG with no palpable pulse (asystole)

Answer

Ventricular fibrillation causing ineffective contraction

Answer

Agonal escape rhythm associated with agonal respirations

Question 6

In a wide-complex regular tachycardia, which ECG feature most strongly suggests ventricular tachycardia over SVT with aberrancy?

Accepted Answer

AV dissociation (independent P waves and QRS complexes)

Answer

Heart rate greater than 200 bpm

Answer

Right bundle branch block morphology

Answer

Inverted T waves in the precordial leads

Question 7

A new left bundle branch block (LBBB) in a patient presenting with ischemic chest pain should be managed how?

Accepted Answer

Treated as a STEMI equivalent requiring emergent reperfusion evaluation

Answer

Monitored and observed as a normal variant in older patients

Answer

Treated with antiarrhythmic medications to restore normal conduction

Answer

Attributed to right ventricular pressure overload and treated with diuretics