The ventriculophasic response: relationship to sinus arrhythmia and the duration of interposed QRS complexes.

Background: The ventriculophasic response (VR) refers to shortening of sinus cycle length during heart block when a QRS complex is interposed between 2 P waves. Our purpose was to analyze its relationship to respiratory sinus arrhythmia (SA) and to compare VR in relation to paced versus intrinsic QRS complexes.

Methods: Patients with advanced heart block had their pacer devices temporarily programmed to ventricular inhibited mode at 30 ppm.