The Challenges of Implanting the Penn State Pediatric Ventricular Assist Device: Study of the Ascending Aorta Anastomotic Flow

Open Access
Author:
Perone, Michael Vincent
Area of Honors:
Bioengineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Keefe B Manning, Thesis Supervisor
  • William O Hancock, Honors Advisor
  • Steven Deutsch, Faculty Reader
Keywords:
  • Penn State PVAD
  • anastomosis
Abstract:
Congenital cardiovascular defects are the leading cause of infant mortality due to birth defects. Ventricular assist devices (VADs) are being developed for use in adult applications and have even proven to be successful in supporting patients ineligible for transplant. VADs function as a secondary pump in parallel with the native ventricle. While implantation of adult VADs has been successful, a comparable pediatric ventricular assist device (PVAD) has yet to be developed. Thrombus formation and embolization have a high rate of occurrence in cardiovascular prosthetic devices, including VADs, due to the requirements for implantation and long-term use, along with large surface area and complex flow patterns. In order to predict the success of an implanted PVAD, the fluid mechanics within the device and its attachment to the aorta need to be studied. By gaining insight into the fluid dynamics of the PVAD anastomosis to the aorta, better PVAD outlet placement may be made to promote successful implantation. The anastomosis of the PVAD to the ascending aorta is found to significantly affect the flow within the aortic arch and the great vessels. At 100% VAD support, the jet from the anastomosis cannula quickly fills the branches but primarily directs the flow past the brachiocephalic artery, causing recirculation at the base of the vessel and retrograde flow within the ascending aorta. For 50% support at the same total flow rate (1.4 L/min) and beat rate (75 bpm), similar flow distribution is observed. The synchronization of the VAD pump with the native ventricle remains a challenge that will continue to be studied. Although drive pumps for the VAD and ventricle were started simultaneously at identical beat rates, pressure differences from each pulse influence the outflow between the pumps. Variability in flow conditions due to pump synchronization is found to cause inconsistency in the flow patterns and affects the flow distribution by developing areas of recirculation and retrograde flow.