Rotary blood pumps are gaining popularity among cardiothoracic surgeons. This article presents an in vitro investigation for choosing a suitable mechanical bearing system in a medium-long term microaxial pump. Different metallic, polymeric, and ceramic components are introduced. Polymers displayed mechanical insufficiency for the application, whereas certain ceramics displayed an inconsistent pattern of failure. We are in search of a compromise in properties that would favor a durable material combination.

The aim of this study was to assess the in vivo performance of a new microaxial rotary blood pump developed for long-term intraportal implantation. The pump, measuring 7 mm in diameter, has a single stage impeller and is powered by a microelectric motor. The pump was implanted into the portal vein in 13 large white pigs under general anesthesia. All animals recovered after the portal pump implantation, and they were observed until the pump failed. The 2 longest running pumps performed for 40 and 36 h, respectively. Either thrombus formation or technical problems, especially in the bearings, were the main causes of pump failure during the experiment. No local or systemic adverse effects were observed during the portal pumping period. Full recovery of the animals following intraportal pump implantation was achieved. However, further technical improvements to the pump are required to maintain a longer performance in vivo.