A New Pumping Device Brings Hope for Cheney
By Lawrence K. Altman, M.D.
Former Vice President Dick Cheney is recuperating from surgery to implant the kind of mechanical pump now being given to a small but growing number of people with heart failure so severe that they would most likely die within a few months without it.
The pumps are partial artificial hearts known as ventricular assist devices, and they come in various models. Mr. Cheney's kind is about the size of a D battery and leaves most recipients without a pulse because it pushes blood continuously instead of mimicking the heart's own pulsatile beat. Most such pulse-less patients feel nothing unusual. But they are urged to wear bracelets or other identifications to alert emergency room doctors as to why they have no pulse.
The pumps are not cures and do not replace the heart. They pose significant risks and are implanted as a last resort either for permanent use or as a bridge to transplant until a donor heart can be found. An estimated five million people in the United States are in various stages of heart failure. Patients in end-stage heart failure are severely short of breath, able to walk only a few yards at a time, or confined to a chair or bed.
As a small number of published studies have shown increasing success with the devices — which are powered by batteries that are about 4-by-6 inches and are connected by a wire that goes through the skin — leaders in the field are trying to increase public and physician awareness that such therapy is available and relatively safe if the patients are carefully chosen. Current belief is that the best time to refer patients for such therapy is before kidney, liver and lung damage develops.
By supplementing the amount of blood pumped through the body, the devices allow many recipients to lead active lives from home. They can bicycle, golf, play tennis, drive cars, shop and generally do what they could before they developed severe heart failure. Patients need to take an anticoagulant, like Coumadin (warfarin) and have blood tests to monitor the amount.
The latest model devices, "though imperfect, are a stupendous advance compared to 36 years ago," said Dr. O.H. Frazier of the Texas Heart Institute at St. Luke's Episcopal Hospital in Houston. Dr. Frazier has been developing and implanting mechanical hearts over that time.
"Still, it is a big operation with risks because we are operating on mortally ill patients," Dr. Frazier added.
In interviews, he and others not connected with Mr. Cheney's case said the implants required opening the chest and could be as arduous for a surgeon as risky for a patient, particularly one like Mr. Cheney, 69, who has had earlier open-heart surgery. Mr. Cheney had a quadruple bypass operation in 1988.
Among the risks are bleeding that requires transfusions, infections, strokes and device malfunctions.
The most recently licensed pumps are smaller, quieter, easier to implant, allow quicker recovery time and last longer than earlier models. Recent reports show improvement over the earlier model mechanical hearts that carried a high rate of complications and death.
Nevertheless, said Dr. Allen S. Stewart, who directs the aortic surgery program at New York-Presbyterian Hospital/Columbia University Medical Center in Manhattan, "everyone wants a better device."
One reason, said Dr. Stuart Katz, who directs heart-failure programs at New York University, is that many pump recipients still have symptoms from their heart failure.
Mr. Cheney has not said whether he intends to live with the device until his death or to sign up as a candidate for a human heart transplant. Inova Fairfax Hospital in Virginia, where a very ill Mr. Cheney with worsening heart failure received his pump earlier this month, performs heart transplants.
Mr. Cheney's heart has been severely damaged from five heart attacks, starting at age 37, with the most recent in February. Doctors cite him as a model for the benefits of modern cardiac care.
Over the years, Mr. Cheney has had angioplasty to unblock coronary arteries and stents to keep them open; an implanted pacemaker and defibrillator; surgery to repairaneurysms, or ballooning of arteries, behind both knees; and a number of visits to George Washington University Hospital for monitoring and observation, the last in June.
In a statement issued on July 14, Mr. Cheney said that he "was entering a new phase of the disease" with "increasing congestive heart failure" and chose a pump to "enable me to resume an active life."
Mr. Cheney went to Ivona Fairfax Hospital apparently because George Washington University Hospital does not perform heart transplants or implant VADs. George Washington did not respond to inquiries.
Mr. Cheney received a HeartMate II device, according to a health care worker who did not want to be identified because he was not authorized to speak for Mr. Cheney.Thoratec of Pleasanton, Calif., sells the device and did not respond to inquiries.
After heart transplants were first performed in 1967, they became the only treatment for end-stage heart disease. But with donor hearts in very short supply, and with improved drugs and other therapies allowing more people to live longer with chronic heart failure, the disparity between demand and supply has accelerated the need for researchers to come up with safe and effective mechanical heart replacements.
Over the years, doctors have implanted various kinds of mechanical hearts with definite, though erratic, progress.
The Food and Drug Administration has licensed two ventricular assist devices for both permanent and bridge-to-transplant use — Thoratec Heartmate XVE and Heartmate II. The agency has licensed four additional devices as bridges to transplant: WorldHeart Novacor, Thoratec PVAD, Thoratec IVAD and MicroMed Heartassist V (for pediatric use).
Also, the agency has licensed two total artificial hearts: SynCardia Cardiowest for bridge to transplant and Abiomed Abiocor on a "probable benefit" basis.
The current continuous-flow pumps are modified derivatives of one that Dr. Richard K. Wampler developed in the 1980s. The latest devices contain an impeller, or a rotor, that spins 8,000 to 10,000 times a minute to pump up to 10 liters of blood a minute without causing major damage to red blood cells.
The limited success has proved wrong the many experts who said people could not live without a pulse. The thought was that since the heart had a beat, that beat was needed for blood pressure and circulation. But now doctors believe that continuous-flow devices, which can be smaller and last longer, may function well. Doctors must use a Doppler machine to measure and monitor the blood pressure of such patients because it cannot be measured through standard cuffs. Some have developed high blood pressure that requires drug treatment, said Dr. Frazier, who implanted the first HeartMate II in November 2003.
Dr. Frazier said he had implanted a total of 170 such pumps as of June 1, more than any other surgeon. Of those, 24 were in patients 65 and older and 11 of the 24 were in patients older than 70. The oldest was 76. Nine of the 24 have died, and seven of the nine did not leave the hospital. Six of the 15 survivors received heart transplants. The remaining nine are living with the pump. The longest survivor at his hospital had an implant in his 30s and has lived five and a half years.
In The European Journal of Heart Failure in May, Dr. Roland Hetzer's team at the Berlin Heart Institute in Germany reported a study of 60- to 80-year-old recipients showing that the continuous-flow devices have a significantly higher survival rate than the pulsatile devices in such patients.
Over recent years, doctors have significantly advanced the upper age limit for a heart transplant to about 72.
Doctors generally wait at least three months to allow the body to adjust to the new pump and recover from the major surgery before a possible transplant.
Patients and doctors give varying accounts of the quality of life with either a pump or transplant. Some patients prefer transplants. Others have chosen to stay with a pump because they do not like the prospect of taking the immunosuppressive and other drugs that are standard for transplant recipients.
Experts like Dr. Stewart and Dr. Frazier said they were awaiting development of newer and smaller pumps that could fit in the arm and not require chest surgery. They said that while the devices would pump about two liters of blood a minute, about one-fifth the amount current devices do, that would be sufficient to aid a failing heart.