HeartWare miniature axial-flow ventricular assist device: design and initial feasibility test

Pulsatile ventricular assist devices have successfully provided circulatory support for many patients throughout the past quarter century; however, persistent complications have hindered expanded clinical application of this technology. Although the use of smaller, continuous-flow ventricular assist device pumps has reduced the frequency and severity of some adverse events, design enhancement may further improve outcomes for patients who require long-term left ventricular support. One new product, the HeartWare, Inc., miniature ventricular assist device, features a wide-bladed rotor design in an axial-flow pump with a strong, passively suspended magnetic rotor. The operating range of 16,000 to 28,000 rpm can provide up to 10 L/min of flow. The wide blades portend minimal cellular trauma.This new device has not yet been approved for use in human beings. As a test, we implanted it in a calf, and we continuously monitored the device's performance and the hemodynamic results over 30 days. No mechanical failure occurred, and no thrombi were noted upon explantation of the device. The animal's circulation was stable during the test period, and no end-organ abnormalities were found upon autopsy. The potential benefits of this miniature ventricular assist device are its increased availability to a broader patient population, a lower risk of infection, simplified implantation procedures, and improved durability. Further in vivo testing is planned. Herein, we discuss the unique design of the HeartWare miniature ventricular assist device, our feasibility study of its performance, and the possibilities for its use in human beings.