CET Rhythm Interpretation & Patient Care 3 — Questions and Answers
Question 1: A rhythm strip shows no identifiable P waves, an irregularly irregular ventricular response, and a rate of 110 bpm. What rhythm is this?
- Atrial flutter
- Atrial fibrillation with rapid ventricular response (Correct answer)
- Multifocal atrial tachycardia
- Ventricular fibrillation
Correct answer: Atrial fibrillation with rapid ventricular response
Atrial fibrillation with rapid ventricular response presents with an irregularly irregular rhythm, absent distinct P waves, and a ventricular rate above 100 bpm.
Question 2: Which ECG finding indicates ventricular fibrillation?
- Wide, bizarre QRS complexes at a rate of 180 bpm with no P waves
- Chaotic, undulating baseline with no identifiable QRS complexes (Correct answer)
- Regular sawtooth baseline at 300 bpm with 2:1 QRS response
- P waves firing at 400 bpm with narrow QRS complexes
Correct answer: Chaotic, undulating baseline with no identifiable QRS complexes
Ventricular fibrillation produces a chaotic, disorganized baseline with no discernible P waves, QRS complexes, or T waves.
Question 3: On a 12-lead ECG, ST-segment elevation in leads II, III, and aVF most suggests injury to which territory?
- Anterior wall
- Lateral wall
- Inferior wall (Correct answer)
- Posterior wall
Correct answer: Inferior wall
Leads II, III, and aVF are the inferior leads; ST elevation in these leads indicates inferior wall myocardial injury.
Question 4: A patient's rhythm strip shows regular P waves at 80 bpm, but only every other P wave is followed by a QRS. What is this rhythm?
- Second-degree AV block, Mobitz Type I
- Second-degree AV block, Mobitz Type II with 2:1 conduction (Correct answer)
- Third-degree AV block
- Sinus arrest
Correct answer: Second-degree AV block, Mobitz Type II with 2:1 conduction
A 2:1 AV block means every other P wave conducts to the ventricles, which is consistent with Mobitz Type II presenting with 2:1 conduction.
Question 5: Which characteristic best distinguishes ventricular tachycardia (VT) from supraventricular tachycardia (SVT) with aberrant conduction on an ECG?
- Heart rate above 150 bpm
- AV dissociation (independent P waves and QRS complexes) (Correct answer)
- Absence of P waves
- ST-segment depression
Correct answer: AV dissociation (independent P waves and QRS complexes)
AV dissociation, where P waves and QRS complexes are independent, is a hallmark of ventricular tachycardia and helps differentiate it from SVT with aberrancy.
Question 6: A patient with a pacemaker shows occasional QRS complexes not preceded by a pacemaker spike, yet the pacemaker appears to function normally otherwise. This is most consistent with:
- Failure to capture
- Failure to sense (undersensing)
- Normal demand pacemaker function with intrinsic beats (Correct answer)
- Pacemaker-mediated tachycardia
Correct answer: Normal demand pacemaker function with intrinsic beats
A demand pacemaker senses intrinsic beats and inhibits its own output; native QRS complexes without pacemaker spikes reflect normal sensing and inhibition.
Question 7: Before applying ECG electrodes, the skin should be prepared by:
- Applying conductive gel only
- Clipping hair, lightly abrading, and cleaning with alcohol (Correct answer)
- Warming the skin with a heating pad for 5 minutes
- Applying lotion to improve electrode adhesion
Correct answer: Clipping hair, lightly abrading, and cleaning with alcohol
Proper skin preparation—removing hair, light abrasion, and alcohol cleaning—reduces impedance and improves signal quality.
CET Rhythm Interpretation & Patient Care 3
A rhythm strip shows no identifiable P waves, an irregularly irregular ventricular response, and a rate of 110 bpm.
What rhythm is this?