A circulatory assist device, also known as a ventricular assist device, is a mechanical circulatory machine. These pumps are used on a short-term basis to allow the patient’s heart to rest while it is healing. However, they have also been used on a long-term basis to support the heart of patients awaiting a heart transplant. There are three major types of devices: counterpulsation devices, cardiopulmonary assist devices, and left ventricular assist devices.