A VAD in the right circulation of patients with univentricular hearts : an animal model

Background: In the long term, patients with univentricular hearts and high pulmonary artery pressures are doomed to either death or heart-lung transplantation. The same fate is reserved to patients with failing total cavo-pulmonary connections. Implantable assist devices offer a new hope for these patients. We explored the possibility of definitive implantation of a ventricular assist device in the pulmonary circulation of patients with univentricular heart physiology. Methods: Five pigs weighing a mean of 33 ± 12 kg were placed under cardiopulmonary bypass. Univentricular hearts were obtained under cardioplegic arrest by ligating the pulmonary artery and resecting 2 leaflets of the tricuspid valve and the interatrial septum. A MEDOS HIA assist device was interposed between both venae cavae and the main pulmonary artery. Results: The animals were maintained under right ventricular assist device for a median of 4 hours (range: 3-6 hours). Their systemic and pulmonary artery pressures remained stable throughout the experiment. No changes were observed on their arterial blood gases after the implantation of the device. Conclusion: Definitive implantation of a ventricular assist device in the right circulation of patients with univentricular hearts might become an alternative to heart-lung transplantation in those with elevated pulmonary artery pressures or with failing cavo-pulmonary connections. An animal model has been developed to study this possibility.