The HeartWare Transvalvular Miniature Ventricular Assist Device Used for Right Ventricular Support

Abstract

Purpose The HeartWare Longhorn is a new Miniature Ventricular Assist Device (MVAD) undergoing pre-clinical testing. The device, provided by HeartWare, requires minimal surgical access for transmyocardial implantation and no outflow graft anastomosis is needed. With the miniature axial flow pump positioned intraventricularly and the outflow cannula directed to lie in the ascending aorta, the Longhorn is able to provide up to 6l/min of flow to completely support ventricular function. We report the first use of the Longhorn device for right ventricular support in a biventricular assist device model. Methods and Materials Using a porcine model on cardiopulmonary bypass, the Longhorn MVAD was implanted into the right ventricle through its diaphragmatic surface. The outflow cannula was directed into the main pulmonary artery and its position optimised by angulation of the gimbal on the sewing ring. A HeartWare MVAD device was implanted onto the left ventricle and severe biventricular dysfunction induced by ligation of the left main and right coronary arteries. Flows through the pulmonary artery and MVAD outflow graft as well as systemic and pulmonary haemodynamic parameters were recorded. Results The biventricular support from the MVAD devices allowed for successful weaning from cardiopulmonary bypass. Flows of 3.4l/min and 3.5l/min were generated by the left and right-sided assist devices at pump speeds of 21 000rpm and 18 000rpm respectively. This resulted in right and left intraventricular diastolic pressures of 0mmHg, while a mean arterial pressure of 60mmHg and pulmonary artery pressure of 33mmHg was maintained. Conclusions The Longhorn MVAD can fully support the right ventricle in a porcine biventricular assist model. Its use for right ventricular support may be particularly advantageous given the absence of an outflow graft anastomosis and that there appears to be no need for outflow graft modification to prevent excessively high pulmonary flows. Further investigation into its usage in the clinical setting is warranted.