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Using devices with a variable postventricular atrial refractory period for cardiac resynchronization.

S S Barold¹, R X Stroobandt

¹Florida Heart Rhythm Institute, Tampa General Circle, 33606, Tampa, FL, USA. ssbarold@aol.com

Herzschrittmachertherapie & Elektrophysiologie

|February 22, 2012

Summary

Automatic postventricular atrial refractory period (Auto-PVARP) programming in cardiac resynchronization therapy (CRT) devices can delay atrial synchrony restoration. A short, fixed PVARP is recommended for CRT patients to optimize AV synchrony.

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Area of Science:

Cardiology
Biomedical Engineering
Electrophysiology

Background:

Automatic postventricular atrial refractory period (Auto-PVARP) is a dynamic pacing feature in Medtronic devices.
It aims to lengthen the PVARP at slow heart rates for pacemaker tachycardia (PMT) protection and shorten it at high rates for improved atrial sensing.
Auto-PVARP is frequently used in cardiac resynchronization therapy (CRT) despite limited understanding of its effects.

Observation:

This study presents sequential ECGs of a CRT patient whose atrial rate was increased with isoproterenol to simulate exercise.
The patient's device was programmed with Auto-PVARP.
ECGs revealed a significant delay in restoring atrioventricular (AV) synchrony once the spontaneous atrial rate fell below the upper tracking rate.

Findings:

Auto-PVARP programming resulted in a substantial delay in AV synchrony restoration after the atrial rate decreased.
This effect is particularly concerning in CRT patients, especially those with first-degree AV block.
Pacemaker tachycardia (PMT) is rare in CRT patients, questioning the necessity of Auto-PVARP in this population.

Implications:

The findings suggest Auto-PVARP may be detrimental in CRT patients by hindering AV synchrony.
A short, fixed PVARP (≤250 ms) is recommended for programming in CRT patients to ensure optimal AV synchrony.
Further research is needed to fully elucidate the role and impact of dynamic refractory periods in CRT.