DC Dysrhythmia Cardiac Rhythm Interpretation 3

Question 1

Which characteristic finding differentiates torsades de pointes from monomorphic ventricular tachycardia?

Accepted Answer

Twisting of the QRS axis around the baseline with varying amplitude

Answer

Torsades de pointes is identified by the characteristic twisting of QRS polarity around the isoelectric baseline, distinguishing it from monomorphic VT.

Question 2

A patient presents with sudden palpitations. The ECG shows an abrupt onset narrow-complex tachycardia at 180 bpm that terminates suddenly with vagal maneuvers. Which dysrhythmia best fits this presentation?

Accepted Answer

AV nodal reentrant tachycardia (AVNRT)

Answer

AVNRT is a reentrant tachycardia within or near the AV node, producing a sudden-onset narrow-complex tachycardia that responds to vagal maneuvers or adenosine.

Question 3

On a 12-lead ECG you see right bundle branch block (RBBB) morphology with an RSR' pattern in V1 and deep S waves in leads I and V6. Which QRS duration is consistent with a complete RBBB?

Accepted Answer

Greater than or equal to 0.12 seconds

Answer

A complete RBBB requires a QRS duration of ≥0.12 seconds (3 small boxes on standard ECG paper), whereas an incomplete RBBB is 0.10–0.12 seconds.

Question 4

A critically ill patient's monitor shows wide, bizarre QRS complexes at a rate of 30 bpm with no discernible P waves. The patient is pulseless. What rhythm should you identify?

Accepted Answer

Idioventricular escape rhythm with cardiac arrest

Answer

A slow idioventricular rhythm (20–40 bpm) without a pulse indicates cardiac arrest; immediate CPR and resuscitation are required.

Question 5

You observe an ECG with a QTc interval of 520 milliseconds. Which clinical condition is most directly associated with this finding?

Accepted Answer

Long QT syndrome predisposing to torsades de pointes

Answer

A corrected QT interval (QTc) ≥500 ms significantly increases risk of torsades de pointes, a life-threatening ventricular dysrhythmia.

(DC) Dysrhythmia Certification Practice Test

(DC) Dysrhythmia Certification Practice Test

DC Dysrhythmia Cardiac Rhythm Interpretation 3