In Vitro and In Silico Characterization of the Aggregation of Thrombi on Ventricular Assist Device Cannula

TL;DR

This study combines in vitro experiments and computational modeling to analyze thrombus formation on ventricular assist device cannulas, aiming to improve design and reduce stroke risk.

Contribution

It introduces a combined experimental and computational approach to understand thrombogenesis on VAD cannulas, focusing on surface roughness and shear effects.

Findings

Rougher cannula regions promote more thrombus deposition.

Shear stress influences thrombus detachment patterns.

Insights may guide design improvements to reduce stroke risk.

Abstract

The unacceptably high stroke rate of HeartMate III VAD without signs of adherent pump thrombosis is hypothesized to be the result of the thrombi originating on the inflow cannula, ingesting and ejecting emboli from the VAD. Therefore, inflow cannula thrombosis has been an emerging focus. The inflow cannula of contemporary VADs, which incorporate both polished and rough regions serve as useful benchmarks to study the effects of roughness and shear on thrombogenesis. An in vitro study was conducted to emulate the micro-hemodynamic condition on a sintered inflow cannula, and to observe the deposition and detachment patterns. Together with a computational fluid dynamic tool, this study aimed to provide insight into the optimization of inflow cannula and potentially reducing adverse neurological events due to upstream thrombus.