Current continuous-flow left ventricular assist devices (LVADs) decrease peripheral vascular pulsatility, which may contribute to side effects such as bleeding and thrombotic events. However, the actual impact of manipulating LVAD pump speed, revolutions per minute (rpm), on peripheral (brachial) pulsatility index (brachial PI), in patients with heart failure implanted with a HeartWare (HVAD) or HeartMateII (HMII) LVAD is unknown. Therefore, blood velocities (Doppler ultrasound) in the brachial artery were recorded and brachial PI calculated across rpm manipulations which spanned the acceptable clinical outpatient range: 360 rpm (HVAD, n = 10) and 1200 rpm (HMII, n = 10). Left ventricular assist device-derived PIs were also recorded: HVAD maximal blood velocity (HVADVmax), HVAD minimum blood velocity (HVADVmin), and HMII PI (HMIIPI). Brachial PI changed significantly with rpm manipulations, from 2.3 ± 0.6 to 4.1 ± 0.8 (HVAD) and from 1.8 ± 0.5 to 3.6 ± 1.0 (HMII). Multilevel linear modeling with random intercepts revealed a 180 rpm decrease of the HVAD resulted in a 0.9 ± 0.1 (37 ± 4%, d = 2.65) increase in brachial PI and a 600 rpm decrease in the HMII resulted in a 0.8 ± 0.1 (38 ± 3%, d = 4.66) increase. Furthermore, a reduction in rpm resulted in a 20.0 ± 0.3% power savings, and a reduction in device reported blood flow of 9 ± 1%. Brachial PI was linearly related to HVADVmax, HVADVmin, their difference (R2 = 0.42, R2 = 0.65, and R2 = 0.54, respectively), and HMIIPI (R2 = 0.86). Manipulating LVAD pump speed, within a clinically acceptable outpatient range, resulted in a significant change in brachial PI, which was reflected by pump indices, documenting the potential for LVAD pump speed manipulations to improve LVAD outcomes.
From the *Department of Nutrition and Integrative Physiology
†Department of Internal Medicine
‡Department of Surgery, University of Utah
§Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, Utah.
Submitted for consideration September 2018; accepted for publication in revised form March 2019.
Disclosure: The authors have no conflicts of interest to report.
This work was supported by, in part, by the National Heart, Lung, and Blood Institute at the National Institute of Health (PO1 HL1091830) and the Veteran’s Administration Rehabilitation Research and Development Service (E6910-R, E1697-R, E1433-P, E9275-L, and E1572-P).
Correspondence: Russell S. Richardson, VA Medical Center, 500 Foothill Dr., Salt Lake City, UT, 84148. Email: firstname.lastname@example.org