Development of DexAide right ventricular assist device: update II

Abstract

The DexAide right ventricular assist device (RVAD) is a magnetically and hydrodynamically levitated implantable centrifugal pump. Recent progress includes 1) redesign of the inflow/outflow conduits, which yielded two successful 3-month experiments, 2) development of alternative journal bearing materials, and 3) completion of an 18-month duration of in vitro endurance testing. Verification testing of the RVAD electronics has been completed, and a prototype biventricular assist device (BVAD) system has been tested. Acute DexAide/CorAide BVAD implantations via median sternotomy in two calves documented BVAD control algorithms and anatomical fit. A drug-induced chronic calf heart failure model, currently under development in our laboratory, resulted in a successful BVAD implantation in a calf with heart failure. Our future plans are to complete in vitro and in vivo validation of alternative bearing materials, perform preclinical DexAide in vivo and in vitro reliability studies, and obtain Food and Drug Administration (FDA) approval for an Investigational Device Exemption to conduct a clinical pilot study. In conclusion, two successful 3 month in vivo experiments and an 18-month in vitro endurance test were completed. After final bearing material selection, the DexAide design will be "frozen" so that preclinical systems can be manufactured. BVAD experiments using a chronic heart failure model are in progress.

Figure 1

The DexAide calf inflow cannula after 3-month implantation through a right thoracotomy. The cannula’s end and both side holes were widely patent with no obstruction or deposition.

Figure 2

(A) A Hemashield® outflow graft after a 43-day implantation. Severe neointimal tissue growth (range 4–9 mm in thickness) was observed on the entire surface of the outflow graft, obstructing the lumen by 25–75%. (B) A Gore-Tex® outflow graft after a 41-day implantation. Thin neointimal tissue (1–1.5 mm in thickness) was observed on the entire surface of the outflow graft, showing no obstruction.

Figure 3

A zirconia stator after 3-month implantation. There was no deposition nor any signs of bearing wear or deformation on the bearing surfaces.

Figure 4

The CorAide LVAD and the DexAide RVAD implantation through a median sternotomy. LVAD, left ventricular assist device; RVAD, right ventricular assist device; LV, left ventricle; RV, right ventricle; Lt., left; Rt., right.