A NOVEL METHOD TO DETECT CHANGING LEFT VENTRICULAR ASSIST DEVICE PUMP FLOW USING A WIRELESS, WEARABLE DOPPLER ULTRASOUND: PROOF-OF-CONCEPT

Abstract

TYPE: Late Breaking Abstract TOPIC: Critical Care PURPOSE: A proof-of-concept study to assess the accuracy of common carotid artery Doppler ultrasonography for detecting clinically-significant changes in continuous-flow left ventricular assist device (LVADCF) pump speed. METHODS: LVADCF outpatients were enrolled; written and informed consent was obtained and the study was approved by the Research Ethics Board of the Mayo Clinic. Each patient underwent a 6-minute protocol while sitting – 2 minutes at their baseline LVAD pump speed (T1), 2-minutes with pump speed decreased by 5% (T2) and 2-minutes with pump speed increased to 5% above baseline (T3). The patients wore an FDA-cleared, wireless, wearable Doppler ultrasound (Flosonics Medical, Sudbury, Ontario, Canada) over the common carotid artery. Both total velocity time integral per 5-seconds (VTI5-SEC) and a corrected VTI for the non-pulsatile fraction of the VTI (VTICORR) were investigated (Figure 1). Sensitivity and specificity for both VTI measures were compared for their ability to distinguish clinically-insignificant pump speed change (i.e., T1-to-T2, 5% decrease) from a significant one (i.e., T2-to-T3, 10% increase). RESULTS: Exploratory analysis was performed on two patients; results are shown in Figure 1. CONCLUSIONS: Changing LVADCF flow, induced by pump speed change, was accurately detected by a wireless, wearable Doppler ultrasound. Novel measures that correct for the non-pulsatile fraction of the cardiac cycle may improve diagnostic accuracy. CLINICAL IMPLICATIONS: Caring for the critically-ill patient with a LVADCF is challenging given that pump flow is afterload sensitive and that mean arterial pressure can be labile. Therefore, an automated method to detect changing LVAD flow from a wearable Doppler ultrasound is promising. DISCLOSURE: JSK, ME, ZY, AME, JKE work for Flosonics Medical, a start-up building the wearable Doppler ultrasound. PS, BDJ, MLC report no conflicts KEYWORD: left ventricular assist device