CRAT Atrioventricular (AV) Blocks 2

Question 1

In first-degree AV block, which ECG finding is diagnostic?

Accepted Answer

PR interval greater than 200 ms with every P wave conducted

Answer

Dropped QRS complexes with progressive PR lengthening

Answer

Complete dissociation between P waves and QRS complexes

Answer

PR interval less than 120 ms

Question 2

Mobitz type I (Wenckebach) second-degree AV block is best described by which pattern?

Accepted Answer

Progressive PR lengthening until a QRS is dropped, then the cycle resets

Answer

Fixed PR interval with intermittently dropped QRS complexes

Answer

Complete AV dissociation

Answer

Constant PR interval with every other P wave blocked

Question 3

Mobitz type II second-degree AV block differs from Mobitz type I primarily because it has which characteristic?

Accepted Answer

Constant PR interval with sudden unexpected dropped beats

Answer

Progressively lengthening PR intervals

Answer

Variable PR intervals

Answer

No visible P waves

Question 4

In third-degree (complete) heart block, how do atria and ventricles relate to each other?

Accepted Answer

They beat completely independently at their own intrinsic rates

Answer

P waves conduct to ventricles after a very long PR interval

Answer

P waves and QRS complexes maintain a fixed but abnormal ratio

Answer

Ventricular rate equals atrial rate

Question 5

A patient has second-degree AV block with a 3:2 conduction ratio in Wenckebach pattern. How many P waves appear for every 2 QRS complexes?

Accepted Answer

3 P waves

Answer

2 P waves

Answer

4 P waves

Answer

1 P wave

Question 6

Which of the following AV block types is most likely to require immediate pacemaker implantation?

Accepted Answer

Mobitz type II second-degree AV block

Answer

First-degree AV block

Answer

Mobitz type I second-degree AV block

Answer

Fascicular block without AV block