Abstract 3657: Non-pulsatile Left Ventricular Assist Device (LVAD) Patients Have Exaggerated Hemodynamic and Autonomic Responses to Head up Tilting Compared to Pulsatile LVAD Patients and Controls
Introduction: The physiologic and hemodynamic differences between patients with pulsatile and non-pulsatile (axial flow) left ventricular assist devices (LVADs) are largely unknown. We characterized these differences by testing hemodynamic and autonomic control responses during orthostatic changes. We hypothesized that “normal” pulsatile flow would be necessary for normal physiological control during orthostasis.
Methods: 9 LVAD patients were studied: 4 with pulsatile devices and 5 with non-pulsatile devices (age range 20 –74 yrs), compared to 10 normal controls. Hemodynamics (BP, HR), cardiac output (C2H2 rebreathing), calf blood flow (CBF), and muscle sympathetic nerve activity (MSNA) in the peroneal nerve were recorded in the supine position and with graded head-up tilting (HUT).
Results: With HUT, all patients demonstrated increased MSNA, decreased cardiac output (CO) and stroke volume (SV), and increased total peripheral resistance (TPR) (Table⇓). Non-pulsatile patients had higher MSNA compared to controls (p<0.05) and greater changes in CO, SV, and TPR. There was a trend toward higher MSNA in non-pulsatile vs. pulsatile patients. Supine CBF did not differ significantly between pulsatile patients (1.79 mL-min−1–100 mL−1 tissue, SD±0.75) or non-pulsatile patients (1.72 mL-min−1–100 mL−1 tissue, SD±1.3) compared to historical normal controls (2.39 mL-min−1–100 mL−1 tissue, SD±0.2) (p=0.92), although there was a trend toward lower CBF and higher calf vascular resistance (CVR) in the LVAD patients.
Conclusions: Non-pulsatile LVAD patients have greater sympathetic tone than pulsatile patients or controls, presumably due to greater baroreceptor unloading. They also appear to have more severe physiologic responses to orthostasis, though more data are needed to further define these differences during activity.