Effect of prolonged nonpulsatile left heart bypass on vascular control status

Abstract

We investigated the vascular control status, including vasoactive hormones, systemic vascular resistance (SVR), and baroreceptor sensitivity, in prolonged nonpulsatile left heart bypass (NLHB). Nine goats underwent pulsatile left heart bypass (PLHB) with a ventricular assist device (VAD). Two weeks postoperatively, the VAD was replaced with a centrifugal pump and NLHB was subsequently conducted for 4 weeks. Thirteen healthy goats were also evaluated to obtain normal control data. The aortic pulse pressure on average was 37 mmHg for controls; 36mmHg at the end of PLHB; and 11, 9, 12, and 12mmHg at the end of the first, second, third, and fourth NLHB weeks, respectively. Plasma norepinephrine (NE), vasopressin (VP), renin activity (RA), and endothelin-i (ET) levels were measured for controls and at each point during PLHB and NLHB. The baseline SVR and the minimum SVR values after nitroglycerin injection were determined at each point during PLHB and NLHB. Baroreceptor sensitivity was calculated as the regression slope between R-R intervals and mean aortic pressure for controls and at each point during PLHB and NLHB. The plasma levels of NE, VP, RA, and EN did not change significantly during the entire course of the experiments. The baseline and minimum SVR values after nitroglycerin injection remained unchanged during PLHB and NLHB. Furthermore, the baroreceptor sensitivity did not change significantly during the entire course of the experiments. These results indicate that prolonged NLHB does not affect vascular control

Change in Vasoconstrictive Function During Prolonged Nonpulsatile Left Heart Bypass

“…In this study, during NLHB, mAoP did not show any extreme oscillations, and SVR, systemic blood flow, and major vasoactive hormone levels maintained a level of consistency; hence, it was inferred that the baroreceptor function was maintained during NLHB. Previously, we evaluated the baroreceptor function and reported the maintenance of the baroreceptor function during NLHB as well as the levels of normal control animals and the level of animals during PLHB (25). Therefore, the cause of the reduction in SVR reaction was not likely to have been the downgrading of the baroreceptor function.…”

The Roles of Vascular Smooth Muscle Cells in the Aortic Wall Thinness under Prolonged Continuous Flow Left Heart Bypass

“…The most characteristic change in the hemodynamic parameters was a decrease in pulse pressure, observed while continuous flow left heart bypass was performed for 4 weeks. The pulse pressure of the Continuous Flow Group (11 ± 4 mm Hg) was clearly lower than that of the normal healthy goats (37 ± 4 mm Hg) (8). Both the bypass flow (105 ± 8 ml/min/kg) and the mean aortic pressure (104 ± 4 mm Hg) in the Continuous Flow Group were maintained within approximately the normal range (8).…”

Morphological Changes of the Arterial Systems in the Kidney under Prolonged Continuous Flow Left Heart Bypass

“…There are 3 possible mechanisms for the diminution of vasoconstrictive function: a change in vascular SMCs, a change in the desensitization of vascular α‐receptors, and a change in baroreceptor function. Previous studies have demonstrated that baroreceptor function is maintained during continuous flow left heart bypass (10,18). This narrows the list of possible mechanisms to 2.…”