BIO7: Hemodynamic Patient Responses to Activities of Daily Living in Left Ventricular Assist Device Patients in Constant Speed and with a Novel Physiological Control Algorithm

Background: Left Ventricular Assist Devices (LVAD) are implanted in late-stage heart failure patients. Currently, LVAD therapy is adapted to the patient by setting a constant speed. However, the development of physiologic control strategies allows finer adjustment to the patient and their individual hemodynamic responses to activities of daily living. Methods: Six patients implanted with a centrifugal LVAD (Medtronic HVAD) underwent a standardized protocol consisting of postural transition from supine to standing position, Valsalva maneuver and submaximal bicycle ergometry in a clinical pilot trial investigating a novel control algorithm (NCT04786236). The patients completed this protocol in constant speed and with activated control algorithm. Patient pump data was collected, physiological variables such as flowrate, flowrate pulsatility and suction prevalence were extracted. Results: The patients safely underwent a total of 13 testing days. Suction typically occurred at the transition phase during postural transitions (4 tests) or during straining or release of Valsalva maneuver (7 tests). The control algorithm reduced speed at postural transition- (Median [Interquartile Range]: -136 [-169, 30] rpm) and Valsalva maneuver onset (-90 [-153, 61]) rpm leading to lower suction prevalence than in constant speed in three tests and 5 tests respectively. In six tests with constant speed patients did not experience increase of their pump flowrate upon exercising. In control mode speed was increased by at least 100 rpm for all but three tests for a median increase of 86 [31, 193] rpm and concomitant flowrate increases of 0.2 [0.1, 0.8] L/min. In two tests flowrate could be increased by up to 1 L/min compared to constant speed, whereas in two patients persistent suction did not allow speed increases above usual set speed. Conclusion: The proposed control system allows additional adaptability to patient hemodynamics. Heterogeneous hemodynamic responses to everyday activities in LVAD patients need to be considered when designing a physiologic control system.