Heart Block Quiz
Questions: 16 · 10 minutes
1. An ECG shows PR intervals that lengthen from beat to beat, followed by a P wave with no QRS complex. Which rhythm does this pattern indicate?
Second-degree AV block, Mobitz type I
First-degree AV block
Second-degree AV block, Mobitz type II
Third-degree AV block
2. In atrioventricular (AV) heart block, what part of cardiac electrical conduction is delayed or interrupted?
Generation of every impulse within the ventricular muscle
Transmission of impulses from the atria toward the ventricles
Recovery of the heart muscle after ventricular contraction
Blood flow from the ventricles into the major arteries
3. Several conducted beats have identical PR intervals, but occasional P waves are suddenly not followed by QRS complexes. Which diagnosis best fits this pattern?
Sinus bradycardia
First-degree AV block
Second-degree AV block, Mobitz type II
Second-degree AV block, Mobitz type I
4. Why is Mobitz type II generally treated as more concerning than Mobitz type I?
It always causes a faster ventricular rate than normal
It is defined by atrial fibrillation occurring between conducted beats
It often reflects disease below the AV node and can progress to complete block
It affects only the sinus node and prevents P-wave formation
5. Which pattern best describes second-degree AV block, Mobitz type I (Wenckebach)?
Every P wave is followed by a QRS complex after a fixed prolonged PR interval
The PR interval progressively lengthens until a P wave is not followed by a QRS complex
P waves and QRS complexes occur independently at separate regular rates
Conducted beats have fixed PR intervals, with sudden unpredictable dropped QRS complexes
6. A person has persistent symptomatic complete AV block after reversible causes have been addressed. Which treatment is commonly considered for ongoing rhythm support?
Coronary stent placement solely to shorten the PR interval
Long-term anticoagulation solely to reconnect atrial conduction
Permanent pacemaker implantation
Catheter ablation of the AV node to restore normal conduction
7. Which finding is most characteristic of second-degree AV block, Mobitz type II?
A prolonged but unchanged PR interval without any dropped beats
Gradual PR prolongation followed by a dropped QRS complex
An irregular atrial rhythm with no identifiable P waves
Intermittent nonconducted P waves without progressive PR prolongation
8. During ECG review, how is a blocked atrial impulse typically recognized in second-degree AV block?
A QRS complex appears without any atrial activity nearby
A T wave is followed immediately by another T wave
The PR interval becomes shorter than the QRS duration
A P wave appears without a subsequent QRS complex
9. When measuring the PR interval on an ECG, which points are used?
The end of the P wave to the end of the QRS complex
The peak of one R wave to the peak of the next R wave
The beginning of the QRS complex to the end of the T wave
The beginning of the P wave to the beginning of the QRS complex
10. A person has fainted and now has a pulse of 32 beats per minute with ongoing dizziness. What is the most appropriate response?
Arrange immediate emergency medical evaluation
Wait several hours to see whether the pulse returns to normal
Take an extra dose of any prescribed heart medication
Perform vigorous exercise to increase the heart rate
11. On an ECG, P waves occur regularly at one rate and QRS complexes occur regularly at a slower rate, with no consistent PR relationship. What is the best interpretation?
First-degree AV block
Mobitz type I AV block
Third-degree AV block
Mobitz type II AV block
12. A patient develops new AV conduction slowing after a medication change. Which drug class is especially relevant to review because it can slow AV nodal conduction?
Proton-pump inhibitors
Non-sedating antihistamines
Penicillin antibiotics
Beta blockers
13. What is the usual ECG hallmark of first-degree AV block in an adult?
A PR interval longer than 200 milliseconds, with every P wave conducted
A QRS complex wider than 120 milliseconds with no preceding P wave
Progressive shortening of the PR interval before a pause
Complete independence of P waves and QRS complexes
14. A monitored patient with high-grade AV block has low blood pressure, confusion, and poor circulation. Which general management approach is most appropriate?
Provide urgent expert care and prepare for pacing while reversible causes are assessed
Encourage walking while repeating the pulse occasionally
Schedule a routine clinic visit several weeks later
Treat the ECG finding only if chest pain develops
15. What defines complete, or third-degree, AV block?
All atrial impulses conduct, but each PR interval is longer than normal
Atrial impulses do not conduct to the ventricles, so atrial and ventricular rhythms are independent
Only premature atrial impulses fail to reach the ventricles
The sinus node stops producing P waves while AV conduction remains normal
16. A patient’s ECG shows a PR interval of 240 milliseconds, and every P wave is followed by a QRS complex. Which explanation is most accurate?
Every other atrial impulse is blocked from reaching the ventricles
AV conduction is delayed, but no atrial impulses are dropped
The atria and ventricles are beating independently
The ECG proves that the person requires emergency pacing