Impairments in Blood Pressure Regulation and Cardiac Baroreceptor Sensitivity Among Patients With Heart Failure Supported With Continuous-Flow Left Ventricular Assist Devices

Abstract

Background: Continuous-flow (CF) left ventricular assist devices (LVADs) improve outcomes for patients with advanced heart failure (HF). However, the lack of a physiological pulse predisposes to side-effects including uncontrolled blood pressure (BP), and there are little data regarding the impact of CF-LVADs on BP regulation.

Methods: Twelve patients (10 males, 60±11 years) with advanced heart failure completed hemodynamic assessment 2.7±4.1 months before, and 4.3±1.3 months following CF-LVAD implantation. Heart rate and systolic BP via arterial catheterization were monitored during Valsalva maneuver, spontaneous breathing, and a 0.05 Hz repetitive squat-stand maneuver to characterize cardiac baroreceptor sensitivity. Plasma norepinephrine levels were assessed during head-up tilt at supine, 30o and 60o. Heart rate and BP were monitored during cardiopulmonary exercise testing.

Results: Cardiac baroreceptor sensitivity, determined by Valsalva as well as Fourier transformation and transfer function gain of Heart rate and systolic BP during spontaneous breathing and squat-stand maneuver, was impaired before and following LVAD implantation. Norepinephrine levels were markedly elevated pre-LVAD and improved-but remained elevated post-LVAD (supine norepinephrine pre-LVAD versus post-LVAD: 654±437 versus 323±164 pg/mL). BP increased during cardiopulmonary exercise testing post-LVAD, but the magnitude of change was modest and comparable to the changes observed during the pre-LVAD cardiopulmonary exercise testing.

Conclusions: Among patients with advanced heart failure with reduced ejection fraction, CF-LVAD implantation is associated with modest improvements in autonomic tone, but persistent reductions in cardiac baroreceptor sensitivity. Exercise-induced increases in BP are blunted. These findings shed new light on mechanisms for adverse events such as stroke, and persistent reductions in functional capacity, among patients supported by CF-LVADs. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03078972.

Keywords: arterial pressure; blood pressure; heart failure; heart rate; hypertension.

Figures

Figure 1:

Hemodynamic and Autonomic Response to Passive Tilt

Figure 2:

Hemodynamic Response to Valsalva Maneuver. Example tracings taken during a Valsalva maneuver from a single participant prior to (A), and following (B) LVAD implantation. Note the marked reduction in pulsatility throughout phase II of the Valsalva maneuver. For a referent comparison of a normal response, Valsalva maneuver obtained from a healthy control is included (C).

Figure 3.

Example tracing of the heart rate and blood pressure response to exercise in a 46yo man with history of advanced HFrEF. (A): exercise prior to LVAD implantation; (B): exercise test following LVAD implantation; (C): inset demonstrates enlarged BP waveforms from B, emphasizing the early increase in pulsatility following initiation of exercise. Note dicrotic notch in arterial waveform, demonstrating aortic valve opening.