Ventricular Arrhythmia Identification Flashcards

A premature ventricular complex (PVC) is recognized on ECG by which characteristic?

Answer: Wide QRS greater than 120 ms appearing earlier than expected with a compensatory pause and no preceding P wave

PVCs arise from an ectopic ventricular focus, producing a wide (> 120 ms), abnormal QRS complex that occurs early in the cycle, not preceded by a P wave, and typically followed by a full compensatory pause.

PVCs occurring in pairs (two consecutive PVCs) are referred to as which term?

Answer: Couplets

Two consecutive PVCs are called a couplet. Three or more consecutive PVCs constitute a run of ventricular tachycardia.

Monomorphic ventricular tachycardia is distinguished from polymorphic VT by which feature?

Answer: Monomorphic VT has QRS complexes of uniform appearance; polymorphic VT has QRS complexes that change in morphology and axis

In monomorphic VT, all QRS complexes originate from the same ventricular focus and appear identical, while polymorphic VT (such as torsades de pointes) has varying QRS morphology because multiple foci are involved.

What is the minimum number of consecutive ventricular beats at 100 bpm or greater required to define ventricular tachycardia?

Answer: Three or more consecutive beats

Ventricular tachycardia is defined as three or more consecutive ventricular complexes (wide QRS) at a rate of 100 bpm or greater, originating from a ventricular focus.

PVCs occurring in a pattern of one PVC for every normal beat are called what?

Answer: Ventricular bigeminy

Ventricular bigeminy describes a pattern where every other beat is a PVC, creating an alternating normal-PVC-normal-PVC rhythm.

The R-on-T phenomenon in PVCs is dangerous because it does which of the following?

Answer: A PVC occurring during the vulnerable period of ventricular repolarization (T wave peak) can initiate ventricular fibrillation

The peak of the T wave represents the vulnerable period of ventricular repolarization — when cells are partially recovered, making them susceptible to fibrillation if an electrical stimulus (PVC) falls during this window.