Assessment of Cardiac Baroreflex Function During Fixed Atrioventricular Pacing Using Baroreceptor‐Stroke Volume Reflex Sensitivity

Abstract

Fixed-rate AV sequential pacing did not blunt the decrease in baroreceptor-SV reflex sensitivity consistent with the arterial baroreflex gain response to upright posture. The decreased baroreceptor-SV reflex sensitivity occurring with the upright posture may reflect a baroreflex-induced inotropic effect secondary to vagal withdrawal and sympathetic activation.

Measurement of vascular tone and stroke volume baroreflex gain

“…To the best of our knowledge, only one study has measured VT-BRS gain (Yambe, Sugita, & Yoshizawa, 2009) and one study has measured SV-BRS gain (Yasumasu, Abe, Oginosawa, Takahara, & Nakashima, 2005). Yet, the VT-BRS and SV-BRS arches are of no less importance to physiological health than the HR-BRS.…”

Comparison of the Effects of VVI Versus DDD Pacing on Cardiac Baroreflex Function

“…The upright position causes blood pooling to the lower body, decreasing the venous return and activating hemodynamic, homeostatic autonomic reflexes. The effects of inotropic activity, vagal withdrawal, and sympathetic augmentation on SV to maintain BP in the upright position were preserved during fixed AV pacing, as they are in healthy subjects 14 . In contrast, BRS‐SV during VVI was already decreased in the supine position, and was not changed significantly by the upright position.…”

“…Cardiac baroreflex function stabilizes the arterial BP by varying the cardiac output (CO) via the baroreceptor‐induced autonomic control of the chronotropic and inotropic state of the heart. We have reported that BRS‐stroke volume (SV), examined by power spectral analysis of spontaneous variations in SV and BP in the low‐frequency band, can serve as an alternate probe of the baroreceptor‐cardiac reflex, similar to the BRS‐HR tested in healthy subjects, 13 and that fixed‐rate atrioventricular (AV) sequential pacing did not blunt the decrease in BRS‐SV consistent with the arterial baroreflex gain in response to upright posture 14 . This method of assessment of BRS‐SV is based on the control mechanisms of CO via a rapid and simultaneous effect of the cardiac baroreflex on SV and HR 15,16 .…”

Cardiac Reflexes During Pacing: Are We Getting to the Heart of the Matter?

“…The authors assessed cardio‐vagal tone by calculating the baroreceptor reflex sensitivity‐stroke volume reflex function. This index has been previously validated by the same group of investigators and reportedly reflects baroreceptor‐induced inotropic action and correlates with spectral‐derived baroreceptor reflex sensitivity 13 . The authors investigated 9 patients who had a dual chamber permanent pacemaker previously implanted for complete heart block.…”

“…This index has been previously validated by the same group of investigators and reportedly reflects baroreceptor-induced inotropic action and correlates with spectral-derived baroreceptor reflex sensitivity. 13 The authors investigated 9 patients who had a dual chamber permanent pacemaker previously implanted for complete heart block. Subjects were randomly assigned in a crossover fashion to either the VVI or DDD mode with a fixed atrio-ventricular (AV) interval of 150 msec and studied during 5 minutes in the supine and upright position.…”