Pre-implant left ventricular apex position predicts risk of HeartMate II pump thrombosis

Abstract

Background Thrombosis within a Left Ventricular Assist Device (LVAD) is a devastating complication that often necessitates device exchange. Few studies have evaluated the relationship between patient anatomy and pump thrombosis. We hypothesize that lateral displacement of the left ventricular (LV) apex increases risk for pump thrombosis. Methods All patients who underwent primary implantation of a Thoratec HeartMate II (HM2) device at a single center (2009-2015) were evaluated. Operative mortalities and patients without imaging were excluded. The angle of the LV apex relative to the midline was measured on preoperative CT scans by two independent surgeons. Pump thrombosis was defined as LDH>700 with clinical symptoms of hemolysis or LVAD malfunction. Univariate and Cox Proportional Hazards analysis was performed to evaluate the impact of LV apex angle on long-term freedom from pump exchange for thrombosis. Results Of 122 patients who met inclusion criteria for this study, 16 (13.1%) underwent exchange for presumed pump thrombosis. Of these patients, 6 (37.5%) required more than one exchange. Patients undergoing exchange for thrombosis had greater LV angle (43.8±9.7 vs 49.5±11.2, p=0.037) with LV apex angle being a significant predictor of LVAD exchange for thrombosis (HR= 1.047, p=0.046). Additionally, when surgeon measurements were compared there was good inter-observer reliability (Pearson Correlation= 0.89). Conclusion A laterally displaced left ventricular apex correlates with a higher risk of pump thrombosis in patients undergoing HM2 implantation. LV apex angle is an easily obtained, reproducible measurement that should be considered when selecting a ventricular assist device.

Left ventricular assist device and pump thrombosis: the importance of the inflow cannula position

“…It should be noted that this was a computational study, not including real patient data. Also, the left ventricular apex position is associated with the occurrence of PT [ 15 ]. There is some data on relation between LVAD angle and PT derived from pathology studies suggesting that minor thrombosis of the inflow cannula is frequently observed and unrelated to clinically relevant PT.…”