CMT Cardiac Dysrhythmias and Arrhythmias 3 — Questions and Answers
Question 1: Which finding on an ECG strip indicates third-degree (complete) AV block?
- PR interval >0.20 sec with all P waves conducted
- Progressive PR lengthening followed by a dropped beat
- P waves and QRS complexes firing independently with no association (Correct answer)
- Wide QRS complexes with retrograde P waves
Correct answer: P waves and QRS complexes firing independently with no association
In third-degree AV block, atria and ventricles beat independently — P waves and QRS complexes have no consistent relationship.
Question 2: Ventricular fibrillation on a monitor appears as:
- Regular wide QRS complexes at 150-250 bpm
- Chaotic, irregular waveforms with no identifiable QRS complexes (Correct answer)
- Sawtooth waves at 300 bpm
- Absent electrical activity (flat line)
Correct answer: Chaotic, irregular waveforms with no identifiable QRS complexes
Ventricular fibrillation produces chaotic, irregular undulations with no discernible QRS complexes, representing disorganized ventricular electrical activity.
Question 3: A patient develops a regular wide-complex tachycardia at 180 bpm. The most dangerous assumption to make is that this is:
- Ventricular tachycardia
- SVT with aberrant conduction (Correct answer)
- Atrial flutter with BBB
- Accelerated idioventricular rhythm
Correct answer: SVT with aberrant conduction
Assuming a wide-complex tachycardia is SVT with aberrancy is dangerous because the majority are ventricular tachycardia, requiring prompt intervention.
Question 4: What is the escape rate of a junctional (AV nodal) escape rhythm?
- 20-40 bpm
- 40-60 bpm (Correct answer)
- 60-100 bpm
- 100-150 bpm
Correct answer: 40-60 bpm
The AV node has an inherent pacemaker rate of 40-60 bpm and will generate escape beats when higher pacemakers fail.
Question 5: Which arrhythmia is defined as three or more consecutive PVCs at a rate greater than 100 bpm?
- Accelerated idioventricular rhythm
- Ventricular tachycardia (Correct answer)
- Ventricular bigeminy
- Torsades de pointes
Correct answer: Ventricular tachycardia
Ventricular tachycardia is defined as three or more consecutive ventricular beats at a rate exceeding 100 bpm.
Question 6: On a monitor strip, which feature most reliably distinguishes sinus bradycardia from a junctional rhythm?
- QRS complex width
- Presence and polarity of P waves in lead II (Correct answer)
- PR interval duration
- Regularity of the rhythm
Correct answer: Presence and polarity of P waves in lead II
Sinus bradycardia has upright P waves before each QRS in lead II, while junctional rhythms show inverted, absent, or retrograde P waves.
Question 7: PVCs occurring on every other beat are called:
- PVC trigeminy
- PVC bigeminy (Correct answer)
- Couplet PVCs
- R-on-T phenomenon
Correct answer: PVC bigeminy
Bigeminy refers to a repeating pattern of one normal sinus beat alternating with one PVC.
CMT Cardiac Dysrhythmias and Arrhythmias 3
Which finding on an ECG strip indicates third-degree (complete) AV block?