Preliminary Study to the Development of a Right Ventricular Assist Device for the Patients with Univentricular Heart: An Animal Model

Background: Children with univentricular pathologies in whom a biventricular repair is impossible can survive with a palliative repair. Thereafter, only a Fontan correction or a heart-lung transplantation can be proposed. But, we believe that an implantable VAD could palliate the lack of organ for transplantation. We decided to explore the possibility of a definitive RVAD in the pulmonary circulation in the situation of univentricular heart. The aim of the present study was to test in this situation if a pulsatile or non-pulsatile device had different effects on pulmonary vascular reactivity. Methods: A univentricular circulation was created into five pigs and their circulation was maintained with either or continuous flow by means of a roller pump or a pulsatile flow with a pneumatically driven assist device (Medos ). Insufflation pressure in the device was set at 150 mmHg or 300 mmHg. Adaptation of the pulmonary vasculature was evaluated by continuous pulmonary artery pressure (PAP) monitoring and its response to non-pharmacologic stimuli after 120 minutes support. Results: The PAP is more than 35 mm Hg when the insufflation pressure is 300 mm Hg but with 150 mm Hg, the PAP is 20 mm Hg. The continuous flow assistance shows the same results. Non-pulsatile or pulsatile VAD with a low driving pressure in the right circulation don’t change the pulmonary reactivity to hypoxia and hypercapnia. Conclusion: A pulsatile right assistance with an insufflation pressure of 300 mm Hg must be avoided because of the risk of creating pulmonary hypertension. Assistance with 150 mm Hg or with a continuous flow doesn't create short-term threatening effect. The pulmonary arterial reactions during hypoxia and hypercapnia before and during mechanical support are not altered.