Thrombus formation at the inflow cannula of continuous-flow left ventricular assist devices-A systematic analysis

Background Despite numerous design iterations, thrombus formation at the inflow cannula of continuous-flow left ventricular assist devices remains an unsolved problem. We systematically investigated the impact of cannula surface on thrombus formation. Methods Thrombus appearance was photographically documented in 177 explanted hearts with the polished (N = 46) or sintered (N = 131) inflow cannula of the Medtronic HeartWare (TM) HVAD (TM) System. Thrombus load was compared for both inflow cannula types. Mean thrombus length was correlated with protruding cannula length. Support duration and the extent of thrombus growth were examined. The prevalence of thrombi at the left ventricular entry site and at the sintered-to-polished transition zone was correlated with left ventricular geometry and hemodynamic parameters. Results Polished inflow cannulas showed a greater percentage and also a greater mean length of thrombus formation at the entry site than sintered cannulas (91.3% [Pol] vs. 36.7% [sTi]; p p < 0.0001). A comparison of the early postoperative period (POD1-90) with long-term support (POD>90) showed an increase in thrombus length originating from the transition zone (1.96 +/- 3.41 mm vs. 3.03 +/- 2.91 mm; p = 0.013). Conclusions A sintered titanium surface at the entry site is crucial to enable anchoring of myocardial tissue to the cannula. As thrombus growth progresses on polished surfaces, a greater sintered length seems to be beneficial. After an initial three-month healing period, thrombus load appears to decline during prolonged support duration at the sintered entry site but not at the transition zone.

Automated summary

In this study, we systematically investigated the impact of cannula surface on thrombus formation in continuous-flow left ventricular assist devices. The results showed that polished cannulas had a higher percentage and length of thrombus formation at the entry site compared to sintered cannulas. A sintered surface is crucial for anchoring myocardial tissue to the cannula.