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, 30 o and 60 o . 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.

Echo-guided left ventricular assist device speed optimisation for exercise maximisation

“…Routinely, pump speed optimisation is based mainly on serial TTEs assessing the degree of LV decompression, RV function and AVO rate in proportion to electrocardiographic QRS complexes 6–8 15 17. Constant AV observation may allow evaluation of the residual LV systolic reserve and match the LVAD speed to metabolic requirements 25.…”

“…The limitation of exercise tolerance in patients with LVAD is multifactorial and results from biventricular HF, inadequate chronotropism, multiorgan dysfunction, pulmonary hypertension, ventilatory inefficiency, anaemia and myopathy 2–6. However, an insufficient rise in cardiac output in response to increased flow demand seems to be one of the most important factors that can potentially be modified 7.…”

Management of Hypertension in Patients With Ventricular Assist Devices: A Scientific Statement From the American Heart Association

“…Diastolic BP increases after CF-LVAD implantation, likely because flow through the device is continuous and not gated to the cardiac cycle. 10 This rise in diastolic BP increases MAP. Despite normalization of resting cardiac output, objective measures of functional capacity remain reduced after CF-LVAD implantation.…”

“…Despite normalization of resting cardiac output, objective measures of functional capacity remain reduced after CF-LVAD implantation. 10,11 CF-LVADs improve but do not normalize the hyperadrenergic state present in patients with advanced HF and reduced ejection fraction, and cardiac baroreceptor sensitivity remains impaired. 10 Exercise produces large increases in pulsatility from increased ventricular contractility, but BP response is blunted.…”

Biomarkers in Patients with Left Ventricular Assist Device: An Insight on Current Evidence

“…A study of cardiopulmonary exercise tests demonstrated an inverse relationship between norepinephrine circulating levels and anaerobic threshold and oxygen pulse, but their levels did not correlate with peak oxygen consumption [ 11 ]. Besides, the exercise-induced increase in blood pressure is blunted in patients with LVAD, despite the increase in the pulsatile component related to the intrinsic ventricular activity [ 12 ]. LVAD-dependent blood flow is only mildly increased during exercise, as current devices cannot adjust flow depending on peripheral requests [ 13 ].…”