A Bridge to Tomorrow
The unhealthiest hearts usually give out before transplants become available. Now, a new assist device could make the wait worthwhile.
"Some patients have such poor blood flow to their brains that while we are talking to them about putting the device in, they can't even carry on a conversation. We have to talk to their families, because they are so sick."
MICHAEL K. PASQUE, MD
"[The device] does make a big difference. They can eat what they want, move around more easily, get out more. They no longer have to be on intravenous medicines, and it is much less stressful for them and their families."
A GENTLE, PERSISTENT BEATca-THUMP, ca-THUMP follows Keith Norris everywhere now. At his north St. Louis County home, he wakes up to it each morning and falls asleep to it each night. The steady rhythm is reassuring; in fact, it is music to his ears, because it comes from a fist-sized electro-mechanical pump, implanted in his abdomen, which is keeping him alive.
The Novacor® Left-Ventricular Assist System (LVAS), produced by World Heart Corporation, is designed to support the circulation of end-stage heart failure patients, a group with severely limited options. While most of the 5 million Americans who suffer from heart failure respond to medication, these patientssome 200,000 of the totaldo not. At this final stage of the disease, they are critically ill and desperate.
"These patients are short of breath at rest, and that gets worse as they do very modest things, like taking a shower or making their bed. They have swelling in their legs, fluid in their bellies. Its a very uncomfortable way to live," says Joseph G. Rogers, MD, associate professor of medicine and medical director of the cardiac transplant program.
Rogers and his colleagues in the Barnes-Jewish Hospital (BJH) Heart Failure ProgramEdward Geltman, MD, and Gregory Ewald, MDare currently following some 2,000 patients with advanced heart failure. Many would be saved by a heart transplant, but donor hearts are scarce. According to the United Network for Organ Sharing (UNOS), 9,102 patients died while waiting for a heart transplant from 1988 to 2000.
But the LVAS, one of several ventricular assist devices (VADs) being evaluated nationwide, offers patients new hope. In 1997, Washington University joined a clinical trial testing the use of the LVAS to support end-stage patients until a donor heart came available. Of the nine people implanted here, sevenall of whom would otherwise have diedmade it to transplantation. Results elsewhere were also impressive, and in September 1998 the FDA approved the LVAS as a bridge to transplantation.
Michael K. Pasque, MD, professor of surgery and of radiology and surgical director of the heart failure and ventricular assist programs, is excited by the LVAS potential. His "bridge" trial experience had convinced him that it is a well-engineered deviceit has the lowest mechanical failure rate of any VADand might work as a longer-term alternative for advanced heart failure patients who were not transplant candidates.
In March 2000, with Pasque as principal investigator, Washington University became the first of five medical centers to sign on to a new LVAS trial: "Investigation of Non-Transplant-Eligible Patients who are Inotrope Dependent" (INTrEPID). He came to the trial with an outstanding team of cardiologists, anesthesiologists, perfusionists, LVAS coordinators and nurses, along with strong backing from the Department of Medicine and the cardiovascular division, school and hospital administrations and the BJH Foundation.
In December 1999, Keith Norris, 33, had his usual beginning-of-the-winter cold, but it didnt go away. At a local hospital, doctors found he was seriously ill with double viral pneumonia. They also discovered an underlying problem: viral cardiomyopathy. As weeks went by, his heart weakened and medications did not help, and in February, he was transferred to Barnes-Jewish Hospital.
In 70 percent of patients, coronary artery disease is the cause of their heart failure. In others, a virus has damaged their heart. Overall, heart failure patients reflect a range of risk factors, such as hypertension, family history and smoking. But by the end-stage of the disease, the result is the same: The patients heart is not pumping enough blood, and the organs, especially the kidneys, are in a dangerously weakened state.
"Some patients have such poor blood flow to their brains that while we are talking to them about putting the device in, they cant even carry on a conversation. We have to talk to their families, because they are so sick," says Pasque.
Keith Norris was one of them. Though a heavy equipment mechanic by trade, he resisted the idea of a mechanical device keeping him alive. On March 8, 2000, as he lay near death, drifting in and out of consciousness, his father begged him to take this chance for survival. Finally, he agreed, and the following morning he was in the operating room. The next thing he knew, he was in a recovery roomalive.
At the core of the LVAS is a two-pound pump which is implanted in a patients abdomen between layers of muscle. Running off it is an inflow conduit which the surgeon connects to the apex of the left ventricle, the hearts main pumping chamber. Blood flows through this conduit, into the pump, and then through an outflow conduit connected to the aorta. From there, it is circulated throughout the body.
There is also an external part of this system. A drive line attached to the pump runs out through the patients skin to connect with other components: a portable electronic controller, which operates and monitors the device; and primary and reserve battery packs, worn on the patients belt or carried in a shoulder bag. To keep the system running, the patient changes batteries every three to four hours. The pump itself is designed to last a little over four years, but can be replaced.
The surgery to implant the LVAS is complexat least six hours long, requiring sophisticated suturing technique. Early on, Pasque successfully refined the procedure to reduce the risk of bleeding. Now it is a "lean, mean operation," he says. "We can place the device in higher risk patients than we ever thought possible."
Afterwards, younger patients usually bounce back quickly; older, sicker patients may need intensive rehabilitation. All patients receive training on the device from LVAS coordinators Tina Hanselman and Kim Shelton, who maintain close contact once the patients go home. Some potential complications, primarily infections in the drive line, require careful watching. But patients are extraordinarily grateful for their second chance at life.
"It does make a big difference," says Hanselman. "They can eat what they want, move around more easily, get out more. They no longer have to be on intravenous medicines, and it is much less stressful for them and their families."
After 19 days, Norris went home, where he now leads an active life. A girlfrienda nurse he met at the hospitalis part of it; so is a newfound religious faith. One low point came when he snagged his drive line and needed corrective surgery. Now he is hoping for a heart transplant sometime in the future. Meanwhile, he says, "each day is given me by God, and I try to get the most out of it. There are blessings all around meI just have to keep going."
Since the FDA approval, Pasque has implanted the LVAS in
other "bridge" patients21 all told, with an 81 percent
By contrast, INTrEPID has included a control group of patients who were not candidates for the LVAS or chose not be implanted. Survival statistics highlight the benefit of the device: 70 percent of those control patients died within two months.
Ultimately, newer technologies will come along, possibly a fully internal pump. Pasque and Rogers are not strong proponents of the much-publicized artificial heart, which is only useful, they say, for the tiny fraction of patients who need both ventricles replaced. They look forward to advancessuch as the re-growth of heart muscle cellsmade possible by stem cell research and the Human Genome Project.
"In a way, we are bridging people to things that havent been discovered yet," says Rogers. "We are trying to buy them time, and we hope that in the next five to 10 years we will have something even better than we have now."