Change in Vasoconstrictive Function During Prolonged Nonpulsatile Left Heart Bypass

Abstract

We investigated changes in vasoconstrictive function accompanying prolonged nonpulsatile left heart bypass (NLHB). After 2-week pulsatile left heart bypass (PLHB) in 11 goats, NLHB was conducted for another 4 weeks (Group N) in 6 goats. In the other 5 goats, PLHB was continued for another 4 weeks (Group P). Systemic vascular resistance at rest (rSVR) was measured on the last days of the second and sixth postoperative week (W2 and W6, respectively). Subsequently, phenylephrine was injected, and the maximum values (SVRmax) and the maximum increasing change in SVR (DeltaSVR) were measured. No significant difference was observed in rSVR between groups at W2 or W6. The SVRmax and the DeltaSVR at W2 were consistent in both groups. However, at W6, the SVRmax and the DeltaSVR of Group N were significantly lower than those of Group P. In conclusion, prolonged NLHB caused a significant decrease in the SVR response to phenylephrine, indicating a dimunition of vasoconstrictive function.

Nonphysiologic blood flow triggers endothelial and arterial remodeling in vivo: Implications for novel left ventricular assist devices with a peripheral anastomosis

“…In contrast, during support with a continuous-flow LVAD, native pulsatility is nearly abolished 27 . Interestingly, there is significant evidence that prolonged non-pulsatile blood flow with a continuous-flow LVAD also produces arterial remodeling 28-31 similar the changes described in this report with a pulsatile pump. These studies and our data demonstrate that altered pulsatility (increased or reduced) produces architectural and functional arterial changes.…”

Recurrent orthostatic syncope due to left atrial and left ventricular collapse after a continuous-flow left ventricular assist device implantation

“…7 In addition, compensation for decreased venous return is inadequate due to poor contractile reserve, 8 and lower extremity reflexes are blunted due to chronic volume overload and neurohormonal activation. 9 Continuous-flow left heart bypass is shown to be associated with a marked decrease in vasoconstrictive function in animal models 10 ; however, similar human data are lacking. Patients are also seen to have impaired chronotropic reserve and an abnormal heart rate recovery early after continuous-flow LVAD placement, indicating significant cardiac autonomic abnormalities.…”

Left ventricular assist devices: a kidney’s perspective

“…Animal [87] and human [88, 89] studies have shown that prolonged continuous flow caused significant changes in the aortic wall, including medial degeneration, smooth muscle cell (SMC) disorientation and depletion, elastic fiber fragmentation and depletion, medial fibrosis and atherosclerotic changes [89]. Such changes may translate to decreased peripheral vascular reactivity [90, 91]. It has been suggested that continuous flow leads to stiff and unresponsive arteries [92].…”