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

Respiratory-cardiovascular interactions

Much of biology is rhythmical and comprises oscillators that can couple. These have optimized energy efficiency and have been preserved during evolution. The respiratory and cardiovascular systems contain numerous oscillators, and importantly, they couple. This coupling is dynamic but essential for an efficient transmission of neural information critical for the precise linking of breathing and oxygen delivery while permitting adaptive responses to changes in state. The respiratory pattern generator and the neural network responsible for sympathetic and cardiovagal (parasympathetic) tone generation interact at many levels ensuring that cardiac output and regional blood flow match oxygen delivery to the lungs and tissues efficiently. The most classic manifestations of these interactions are respiratory sinus arrhythmia and the respiratory modulation of sympathetic nerve activity. These interactions derive from shared somatic and cardiopulmonary afferent inputs, reciprocal interactions between brainstem networks and inputs from supra-pontine regions. Disrupted respiratory-cardiovascular coupling can result in disease, where it may further the pathophysiological sequelae and be a harbinger of poor outcomes. This has been well documented by diminished respiratory sinus arrhythmia and altered respiratory sympathetic coupling in animal models and/or patients with myocardial infarction, heart failure, diabetes mellitus, and neurological disorders as stroke, brain trauma, Parkinson disease, or epilepsy. Future research needs to assess the therapeutic potential for ameliorating respiratory-cardiovascular coupling in disease.

A 2:1 atrioventricular block presenting paradoxical ventriculophasic response

Ventriculophasic response (VR) is defined as the shortening of the sinus cycle length in the setting of greater than second-degree atrioventricular (AV) block. Typically, the PP intervals interposing a QRS complex are shorter than those without a QRS complex. Paradoxical VR is a rare clinical entity. We report about an 80-year-old man presenting with a 2:1 AV block, in whom typical and paradoxical VRs were observed.

Factors affecting ventriculophasic response: An investigation in patients with permanent pacemaker

BACKGROUND

Ventriculophasic response (VR) refers to the shortening of the atrial cycle length (P-P-interval) that occurs during the heart block when a QRS complex is interposed between two P-waves. The aim of this study was to determine the factors affecting this phenomenon.

METHODS

Thirty patients with high grade heart block treated with dual chamber pacemaker were studied. The pacer function of the patients' device was temporarily programmed to the ventricular-inhibited mode at 30 pulses per minute. A total of 330 recordings containing two P-waves with an interposed QRS and its previous P-P interval without any QRS were collected. The VR was defined as being present when the P-P interval with an interposed QRS shortened more than 3% compared to the preceding P-P interval.

RESULTS

The VR was present in 45% of the recordings. In the multivariate logistic regression analysis, only a mid position of the interposed QRS was a positive predictor for presence of VR. However, there were no differences between recordings with or without VR groups according to QRS duration, paced or intrinsic interposed QRS. Hypertension and age had a negative correlation with the presence of VR when the QRS was interposed in the mid part.

CONCLUSION

We found that the VR was present in approximately half of our cases. This phenomenon was mostly affected by position of the interposed QRS according to the previous P-P interval.