Lavare Cycle Does Not Induce Pulsatility in CF-LVAD Patients

Abstract

Purpose The Lavare cycle (LC) is a pre-programmed speed modulation algorithm (SMA) in the HeartWare continuous flow left ventricular assist device (HVAD) designed to increase ventricular and pump washout. We sought to determine whether the LC induced artificial pulsatility and alter sympathetic nervous system activity. Methods Ten HVAD patients were prospectively recruited. Patients were monitored for 24 hours using 3 devices and pulsatility metrics were calculated; 1) SphygmoCor 24-hour ambulatory oscillometric / tonometric blood pressure (BP) monitoring device was used to calculate pulse pressure (PP) and mean arterial pressure (MAP), 2) CDAS continuous pump data recorder was used to calculate a flow pulsatility index (PI), defined as (maximum - minimum flow)/(mean flow) and 3) Holter monitor (1000Hz) was used to calculate time domain measures of heart rate variability (HRV) to ascertain changes in sympathetic activity levels. Patients were monitored on two separate occasions, once with their LC on and once with it off. BP, flow and PI analyses were dichotomized for awake and asleep hours to account for diurnal variation in blood pressure and cardiac output. Results PP and MAP results were available for 9 patients, PI for 8 patients and HRV for 7 patients (table 1). There was no difference in PP, MAP or PI between the LC on and LC off groups. In terms of HRV, the LC on group had slightly higher heart rate (HR) compared to the LC off group (81.2 vs 78.7 bpm, p=0.028). There was no difference between groups in time domain measures of HRV (SDNN, standard deviation of normal-normal intervals; RMSSD root mean square of successive differences), markers of sympathetic and parasympathetic activity respectively. MAP was lower whilst asleep than awake (68.8 v 78.5, p=0.004), unaffected by LC. There were no differences between awake and asleep groups for PP, PI or mean flow (table 1). Conclusion LC is not associated with induced pulsatility or altered sympathetic activity in HVAD patients. MAP was lower in patients whilst asleep compared to when awake.