The implanted HeartMate attaches to the aorta and leaves natural circulation in place. It is implanted just below the diaphragm in the abdomen. An external wearable vest holds a controller and batteries. A small driveline pierces the skin to power the pump.

Patients with weak or damaged hearts that need replacing often rely on bridge-to-transplant devices like the HeartMate II, a left ventricular assist device (LVAD) from Thoratec Corp., Pleasanton, CA (thoratec.com). These devices keep patients healthy until a suitable organ is found. The HeartMate won FDA approval as a bridge-to-transplant device this past April based on its technology and success in clinical trials.

Engineers at Thoratec made sure the device would minimize clotting and damage to blood cells by choosing biocompatible materials for surfaces that contact blood. Designers also textured those surfaces so they will not cause clots. The axial flow device can pump 10 liters/min., which is the full output of a healthy heart. The device is smaller than most LVADs, which makes it easier to implant in a range of patients, and it operates more quietly.