# Hemodynamic analysis of the aortic root based on differences in outflow graft angle in patients with implantable left ventricular assist devices

## TL;DR

This study uses computational models to show how the angle of LVAD outflow grafts affects blood flow and stress on the aortic valve, which could help reduce aortic insufficiency in patients.

## Contribution

The study introduces patient-specific CFD simulations to analyze how outflow graft angles influence aortic valve wall shear stress and coronary perfusion in LVAD patients.

## Key findings

- Steeper outflow graft angles increase wall shear stress on aortic valve leaflets.
- Shallower graft angles significantly reduce coronary artery blood flow.
- Patient-specific simulations could help optimize graft positioning to prevent aortic insufficiency.

## Abstract

Aortic insufficiency (AI) that develops during long-term support with continuous-flow left ventricular assist devices (LVADs) remains a significant clinical problem. Abnormal flow patterns and altered wall shear stress (WSS) on the aortic valve are believed to contribute to leaflet remodeling, yet the hemodynamic influence of outflow graft orientation in patient-specific anatomies is not fully understood. This study investigated how different outflow graft angles affect aortic valve WSS and coronary perfusion using computational fluid dynamics (CFD). Three LVAD recipients who underwent preoperative ECG-gated coronary CT were retrospectively analyzed. Patient-specific geometries of the ascending aorta, aortic root, and coronary arteries were reconstructed. A cylindrical outflow graft was virtually anastomosed 25 mm above the sino-tubular junction, and three inclination angles (30°, 60°, 90°) were modeled with a fixed azimuthal angle of 90°. CFD simulations were performed under constant LVAD inflow (5.0 L/min) and uniform outlet pressure conditions. WSS on the aortic valve cusps and coronary flow rates were evaluated after achieving quasi-steady flow. Increasing outflow graft angle resulted in higher WSS on the ascending aortic wall opposite the anastomosis and consistently elevated WSS on the left coronary cusp. In some cases, the non-coronary cusp also showed localized WSS increases. Coronary flow decreased with shallower graft angles, with left coronary artery flow approximately halved at 30° compared with 90°, while right coronary flow exhibited a smaller reduction. Outflow graft angle substantially affects aortic valve WSS distribution and coronary perfusion. Steeper angles increase leaflet WSS, whereas shallower angles reduce coronary flow. Patient-specific CFD simulations may aid in optimizing graft positioning and reducing the risk of AI progression in LVAD patients.