# In silico analysis of pressure distribution and flow profiles across an experimental left ventricular assist device accessory

## TL;DR

Researchers used computer simulations to study how a new heart pump accessory causes pressure loss, aiming to improve its design for less invasive implantation.

## Contribution

The study identifies curvature and bifurcation in the accessory’s outflow as key causes of pressure loss, offering design improvements for less invasive LVAD implantation.

## Key findings

- Pressure loss increases significantly between 5 and 8.4 L/min flow rates in the experimental accessory.
- Curvature and bifurcation in the outflow path are the main contributors to downstream pressure loss.
- The accessory’s design could be improved to reduce curvatures and bifurcations for better performance.

## Abstract

Implantation of left ventricular assist devices conventionally requires a sternotomy and cardiopulmonary bypass. An experimental accessory was designed to redirect the device’s outflow graft through the left ventricle into the ascending aorta. This design allows for implantation via left thoracotomy only but resulted in significant pressure loss both in vitro and in vivo. We evaluated the reasons for the pressure loss of the experimental accessory by quantifying pressure distribution and flow profiles using computational fluid dynamics simulation tools.

A computational fluid dynamics model based on the accessory’s geometry was used to simulate nominal blood flow through the model. Quantities of interest included pressure and flow velocity. Pressure differences between the pump inlet and outlet were calculated at different rotational speeds (4000, 5200, 6400 rpm) and pump flow rates (1, 5, 8.4 L/min). Results were compared with simulations of a generic left ventricular assist device to determine the accessory’s impact.

Natural pump characteristics were observed, as increased rotational speed caused an increase in pressure head with a constant flow rate. For all cases, a greater decrease in pressure head was seen between 5 and 8.4 L/min than between 1 and 5 L/min. Curvature intensity and channel bifurcation in the outflow were the main contributors to downstream pressure loss.

The next iteration of the left ventricular assist device accessory should focus on minimizing curvatures and avoiding bifurcations in the outflow. Further development may allow for less invasive left ventricular assist device implantation with negligible alterations in pump performance.

Conventional left ventricular assist device (LVAD) implantation requires either a full or partial sternotomy to suture the outflow graft to the aorta (Fig. 1a).