Nonpulsatile Flow Among Patients With Continuous-Flow Left Ventricular Assist Devices Leads to Greater Levels of Sympathetic Neural Activity Through Unloading of Arterial Baroreceptors

Background: Patients with continuous-flow (CF) left ventricular assist devices (LVADs) have elevated sympathetic neural activity (SNA). We hypothesized that this hyperadrenergic environment is related to unloading of arterial baroreceptors resulting from reduced pulsatility. The purpose of this study was to quantify differences in carotid arterial (CA) distortion and wall tension at the level of the arterial baroreceptors in patients with CF-LVADs and healthy controls and determine how these variables influence muscle (M)SNA burst frequency (bursts/min). Methods: Eleven CF-LVAD subjects and nine healthy controls underwent measurements of CA diameter using high-resolution ultrasonography and MSNA by microneurography during head-up tilt (HUT) at supine, 30o and 60o. Results: CF-LVAD patients had higher mean arterial pressure (MAP) at the level of the CA, higher MSNA and a lower pulse pressure than healthy controls during HUT (P<0.05 at all positions). Pulsatile diameter of the CA (defined as diametersystole...