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International Physician Update
Mechanical Ventricles: An Alternative to Transplant?
Heart failure patient Steven Riddle, 61, knew he was in deep trouble when the motor that powered the mechanical ventricle that kept him alive for a year suddenly burned out. As alarm bells from his belt battery pack went off, Riddle and his wife tried frantically to connect a hand pump to a tube leading through his abdomen to the device, implanted beneath his ribs. Then, the room started to spin—Riddle turned blue and passed out. Fortunately, Riddle’s wife began manually pumping air into the device, propelling oxygen-rich blood through the aorta and throughout her husband’s body—a job his diseased left ventricle couldn’t handle. The color returned to Riddle’s face as he regained consciousness.
Today, Riddle is in the hospital, tethered to a pneumatic pump that keeps his left ventricular assist device, or LVAD, working until a heart becomes available for transplantation. The device he had been relying on failed, in part, because it was designed to keep the patient alive until transplant, on average about 100 days. But newer, smaller models of these machines are being designed to work much longer—and with less risk of complications. Rather than thinking of LVADs solely as a bridge to transplant, surgeons now say these devices might soon be used as an alternative.
“The thinking is, we can sustain a patient as well as a heart transplant can with potentially fewer complications,” says cardiac surgeon John Conte.
Conte explains that 90 percent of heart transplant patients, like Riddle, need a new heart because of left-ventricle failure. But why replace the entire heart if the right ventricle is doing an adequate job of pumping blood into the lungs? Assist devices offer some additional advantages; they avoid transplant-related problems like organ-tissue rejection.
These are among the reasons why Hopkins is participating in a study of a new LVAD named after heart surgeon Michael DeBakey. Like most LVADs, the DeBakey is externally powered, but it’s only about one-tenth the size of a typical device. That means it can fit into more patients, and could be less prone to infections and clots, the two major problems with LVADs. Initially, the device will be offered to heart failure patients ineligible for transplant. If those patients do well, the device may one day be an option for transplant patients.
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