Like the artificial heart, the first ventricular assist devices (VADs) developed 25 years ago were meant to sideline the failing biological heart of a heart failure patient. These pumps were heavy, bulky things that drew blood from the left ventricle through an intake valve and moved it into the aorta at as much as 10 liters per minute — the full output of a healthy heart.
Some of the VADs made today take into account the fact that even severe heart failure patients retain partial functioning of the left ventricle: from as little as 10 percent to as much as 50 percent of its normal capacity. The tiny, valveless Jarvik 2000 FlowMakerŽ, developed by artificial heart pioneer Dr. Robert Jarvik, is one such design.
Held in the hand, the Jarvik 2000 pump is about the size of a C battery. Within its welded titanium shell sits a direct-current motor, a rotor supported by two ceramic bearings, and a single moving part: a small, spinning titanium impeller that pumps blood from the heart at up to 7 liters per minute. Rather than take over for the biological heart, the Jarvik 2000 augments the weakened heart's blood output to help restore a normal blood flow throughout the body.
By utilizing the heart's remaining strength, the Jarvik 2000 takes a simple, unobtrusive approach to circulatory support. Any muscle that gets too little exercise becomes "out of shape," and the heart is no exception. The Jarvik 2000 allows the patient's heart to continue to exercise as it recovers after surgery. The pump is designed to minimize patient reliance on mechanical support, avoid risk and redundancy in its function, and give the patient the best chances of recovery.