Left ventricular decompression during speed optimization ramps in patients supported by CF-LVADS: Device specific performance characteristics and impact for diagnostic algorithms

PURPOSE: Echocardiographic ramp tests have been widely used to help guide speed adjustments and for identification of potential device malfunctions in patients with axial continuous flow LVADs (Hea.rtmate II LVAD). Recently, the use of centrifugal flow LVADs (Heartware LVAD) has been on the rise. The purpose of this study was to evaluate the utility of ramp tests for assessing ventricular decompression in HVAD patients. METHODS: In this prospective study, ramp tests were performed prior to index hospitalization discharge or at the time of device malfunction. Vital signs, device parameters (including flow) and echocardiographic parameters (including left ventricular end-diastolic dimension, frequency of AV opening and valvular insufficiency) were recorded in increments of 100 rpm, from 2,300 rpm to 3,200 rpm. RESULTS: Twenty-six ramp tests were performed, 19 for speed optimization and 7 for device malfunction assessment. The average speed after the speed optimization ramp tests was 2534.74 +/- 156.32 RPM, and the aortic valve (AV) closed at a mean speed of 2751.77 +/- 227.16 RPM, with one patient’s valve remaining open at the maximum speed. The reduction in LVEDD for each speed increase was significantly different when the AV was open or closed, at -0.09 cm/increment and -0.15 cm/increment, respectively (p=0.013), which is significantly different than previously established HM II LVEDD slopes. There were also significant changes in overall device flow (p=0.001), upper flow (p-0.031) and lower flow (p=0.003) after aortic valve closure. The power slope did not change significantly after the AV closed (p=0.656). Five of the nineteen tests were stopped prior to completion due to suction events, but all tests reached at least 3000 RPM. CONCLUSIONS: The parameter slopes for the Heartmate II cannot be directly applied to ramp studies in HVAD patients. Overall, the LVEDD slope is drastically smaller in magnitude than the previously reported HM II findings, and speed adjustments were not based on the degree of LV unloading. Therefore, the slope of the LVEDD-rpm relationship is not likely to be helpful in evaluating HVAD function.