A Left Ventricular Assist Device (LVAD) is often used to assist a really sick heart and to bridge a patient until they can get a heart transplant. They can sometimes be used as a bridge to recovery in a very sick heart that cannot wean off the heart-lung machine during open heart surgery.
The left ventricle is the large, muscular chamber of the heart that pumps blood out to the body. A left ventricular assist device is a battery-operated, mechanical pump-type device that's surgically implanted. It helps maintain the pumping ability of a heart that can't effectively work on its own.
An LVAD has a tube that pulls blood from the left ventricle into a pump. The pump then sends blood into the aorta (the large blood vessel leaving the left ventricle). This effectively helps the weakened ventricle.