CRAT Junctional Rhythm Analysis 3

Question 1

Which feature best differentiates a junctional rhythm from a sinus rhythm with first-degree AV block?

Accepted Answer

P wave morphology and axis — junctional P waves are inverted in inferior leads while sinus P waves are upright

Answer

The key differentiator is P wave direction: sinus rhythm produces upright P waves in II, III, aVF regardless of PR length, while junctional rhythms produce inverted or absent P waves in inferior leads.

Question 2

In a junctional escape rhythm, the QRS complex is typically narrow because of which reason?

Accepted Answer

The impulse reaches the ventricles via the normal His-Purkinje conduction system

Answer

Since junctional impulses travel through the normal bundle of His, bundle branches, and Purkinje fibers to activate the ventricles, the QRS duration is narrow — less than 120 ms — identical to sinus conducted beats.

Question 3

A patient post-cardiac surgery develops a regular narrow-complex tachycardia at 110 bpm with inverted P waves in lead II occurring just after each QRS. Which rhythm is most likely?

Accepted Answer

Junctional tachycardia

Answer

Regular narrow-complex tachycardia at 110 bpm with retrograde P waves (inverted in II) immediately after QRS in a post-cardiac surgery patient is consistent with junctional tachycardia due to enhanced automaticity.

Question 4

What is the significance of a junctional escape rhythm appearing at a rate slower than 40 bpm?

Accepted Answer

It may indicate junctional suppression, possibly due to enhanced vagal tone, medication effect, or junctional disease

Answer

A junctional rhythm below 40 bpm suggests the junctional pacemaker itself is suppressed, raising concern for medications (beta-blockers, digoxin), hyperkalemia, or intrinsic junctional disease.

Question 5

Digitalis toxicity is classically associated with which junctional arrhythmia pattern?

Accepted Answer

Accelerated junctional rhythm with AV dissociation

Answer

Digitalis toxicity enhances junctional automaticity (causing accelerated junctional rhythm at 60-100 bpm) while simultaneously blocking AV conduction, producing AV dissociation.

CRAT - Certified Rhythm Analysis Technician Practice Test

CRAT - Certified Rhythm Analysis Technician Practice Test

CRAT Junctional Rhythm Analysis 3