The Implication of HeartWare HVAD Inflow Cannula Angle on Stroke and Thrombus Rate

Abstract

Purpose Stroke and ventricular assist device (VAD) pump thrombus are serious complications that have previously been thought to be related to surgical placement - namely VAD inflow cannula angle. Our aim with this study was to better elucidate the impact of post-operative HeartWare HVAD (left VAD) cannula inflow angle on stroke and thrombus rate within a single centre in Sydney, Australia. Methods Data were extracted retrospectively for all patients who underwent Heartware HVAD implantation from 2007-2017 with accessible on-site CT imaging. BiVAD patients were excluded. Angulation data was available for 95 patients. Post-implant inflow angle was measured between the middle of the inflow cannula relative to the middle of the sternum . All measurements were carried out in the axial plane on CT imaging. Data on Free Haemoglobin level was extracted at 3 intervals (3, 6, and 12-months post VAD implantation). Statistical analysis was carried out using IBM SPSS v25. Results Mean post-operative inflow cannula angle was 89 +/- 27 degrees vs 91 +/- 22 degrees for the non-stroke and stroke groups respectively, p=NS. Similarly, there was no difference in mean post-operative inflow cannula angle between those that formed pump thrombus (89 +/- 28 degrees) and those that did not (91 +/- 19 degrees), p=NS. Average 12-month post-implant Free Haemoglobin was higher in the group with pump thrombus than the group that did not form thrombus (9.1 +/- 9 vs 5.3 +/- 9), p=0.012. Conclusion There was no association between HVAD cannula inflow position and incidence of stroke or thrombus rates in this population. The previous finding of an interaction between inflow cannula angulation and pump thrombosis may be device specific.