When the device goes to market in Europe--and in its second round of United States clinical trials--it will be implanted using an even less invasive procedure. Instead of opening the chest and inserting the inflow tube directly into the left atrium, the surgeon will use a catheter to snake it through a large vein into the right atrium, and then through the heart's inner wall to the left atrium.

Ultimately, the Synergy will target a patient population not usually given VADs. These patients--in late stage-three and early stage-four heart failure, often called the "lost stages"--do not respond to drugs but are not yet sick enough to warrant an invasive, risky surgery. "They really have no other option," says Paul Southworth, CEO of CircuLite. "The few patients who get VADs or transplants get them by getting sicker." Earlier intervention will drastically improve quality of life for these patients, says Columbia's Naka.

The CircuLite pump is powered by a roughly four-pound battery pack worn at the waist. Southworth says that future versions will have an even smaller battery, about the size of a Razr cell phone. Patients with the implant can live at home with relatively few lifestyle restrictions. "They want to play with their kids or their grandchildren, or garden, or do the things that they did before," says Southworth, "so it's important that they have something unobtrusive."

Although trials of the device have so far aimed to keep end-stage heart-failure patients alive while they await transplants, Synergy was not designed as a so-called bridge-to-transplant device. Providing a modest boost in blood output from the heart, it is ultimately meant to support patients with chronic heart failure in the long term--over many years--perhaps obviating the eventual need for a transplant. Preliminary results from the European trials suggest that the pump may even allow the failing heart to heal itself by giving it a rest.

"It allows the heart to rest and potentially recover," says Southworth, "and it supplements the heart where it's unable to pump the required blood."