Implantable devices have been used for decades to treat heart disease. The first pacemaker was implanted over 40 years ago, and implantable defibrillators were first used in the early 1980s. But the last few years have witnessed a surge in both the types of devices being tested for heart-failure treatment, and in the optimism of experts about their usefulness.
"A lot of the big advances that we've had in treating heart failure in the last few years has been with devices," says Marvin A. Konstam, MD, chief of cardiology and director of cardiovascular development at Tufts-New England Medical Center. "It's an exciting time."
Eric Rose, MD, agrees. "Things are dramatically different in the last five years," says Rose, department of surgery chairman at the Columbia University College of Physicians and Surgeons. "For instance, the dream of using machines for long-term supportive patients with end-stage heart failure is now a reality."
But Rose, who led a study of one such implant used in heart-failure treatment -- the left ventricular assist device -- is temperate in his enthusiasm. "It's a reality, but I should say that it's a reality with mediocre outcomes at this point," he tells WebMD. "That's still an improvement over God-awful, which is what the prognosis was before."
While advances in devices are impressive, all experts agree that we are only in the early stages of their development. It remains to be seen how widely and how quickly these life-saving implants will become available for routine heart-failure treatment.
Given that heart failure is not a specific disease in itself, but rather a condition that results from other illnesses, different approaches have been developed to treat the condition. Some stem from the familiar pacemaker, others from devices designed as a stopgap before heart transplant.
Implantable Cardioverter Defibrillators (ICDs)
An ICD is used for heart-failure treatment when the person is considered to be a high risk of dying from an abnormal heart rhythm -- called sudden cardiac death. It is a small device that is implanted in the chest and continually monitors the heart's rhythm. If the ICD senses a dangerous abnormal heart rhythm, it delivers an internal electric shock to the heart -- the equivalent of being shocked with paddles outside the body -- that hopefully restores a normal heart rhythm.
Given that sudden cardiac death from fatal, abnormal heart rhythms causes about 50% of all heart-related deaths, ICDs have enormous potential. One recent study found that ICDs reduced sudden cardiac death in people at risk for it -- such as those with a previous heart attack or heart failure -- by more than 50%.
Of course, there is a potential disadvantage to having an ICD for heart-failure treatment: If the experience of being shocked by a box in your chest doesn't sound pleasant, you're right. While some report minor discomfort, others find it extremely painful and anxiety-provoking. This is particularly troublesome in people who have frequent episodes of this potentially fatal abnormal heart rhythm.
"There have been some studies [that] showed that after getting two shocks, people's anxiety went sky high," says Susan J. Bennett, DNS, RN, a professor in the Indiana University nursing school and a specialist in treating the condition. "But the other thing that happens is that some patients who get shocked are grateful because they know the device is working and they know that it saved their lives."
ICDs can be implanted alone, but they are also combined with other devices, such as cardiac resynchronization therapy, for heart failure treatment.
Cardiac Resynchronization Therapy (CRT)
Cardiac resynchronization therapy is a new and promising treatment. "Resynchronization therapy is the biggest story in device therapy for heart failure," says Konstam, who is also president of the Heart Failure Society of America.
In some patients with heart failure, the electrical signals that coordinate pumping of the different heart chambers become erratic, making the heart unable to pump blood efficiently. In addition, an already weakened heart wastes energy by fighting against itself.
CRT devices deliver electrical impulses to both the right and left ventricles -- the two large, main pumping chambers of the heart -- restoring the coordination between the two sides of the heart and improving its function.
Michael R. Bristow, MD, PhD, of the University of Colorado Health Sciences Center in Denver, was involved in one of the biggest studies of CRT ever done. Results were published in the May 2004 issue of The New England Journal of Medicine. Participants, all who had advanced heart failure, were divided into three groups: The first group got the best drug treatment -- a beta-blocker, an ACE inhibitor, and a diuretic -- while the second and third groups got the drug treatment plus either a CRT device or a CRT device with a defibrillator (the two devices now come together in one device). Researchers found that compared with aggressive medication treatment alone, adding CRT to treatment reduced the risk of death by 24%. Combining CRT with a defibrillator (the two devices now come together in one device) reduced deaths by 36%.
"CRT makes you feel better, keeps you out of the hospital, and gives you a better quality of life," Bristow tells WebMD.
Left Ventricular Assist Devices (LVADs)
In the past, people with end-stage heart failure had to rely on the hope of a transplant. Left ventricular assist devices (LVADs) were originally designed as "bridge" therapy, to help people with a weak left ventricle -- the main pumping heart pumping chamber -- survive while they waited for a heart transplant.
LVADs are implanted, pump-like devices that assist the weakened heart in circulating blood. While LVADs were originally attached to large control panels in hospitals, newer devices are smaller and contained, allowing patients to leave the hospital and go home with a small external device and battery pack. LVADs are generally used in people who are not eligible for heart transplants, usually because of age.
While transplants are a highly effective heart-failure treatment, the chances of getting one are limited by the availability of donors. Only about 2,500 people in the U.S. receive a heart transplant each year while many more remain on waiting lists; heart failure causes 50,000 deaths annually and contributes to another 250,000 deaths. A mechanical device like an LVAD that doesn't rely on donors could make a huge difference in heart-failure treatment.
Eric A. Rose, MD, chairman of the department of surgery at Columbia University College of Physicians and Surgeons and surgeon-in-chief at Columbia Presbyterian Medical Center, tested the effectiveness of the LVAD in people with end-stage heart failure -- 68 had LVADs implanted and 61 were given standard medical care. After two years, the LVADs were shown to be strikingly effective, reducing deaths by 47%.
Potentially, one of the most promising aspects of LVADs is that they may actually rest the heart, allowing it to recover; in such cases, the device can be removed.
"In a lot of ways, it's not unexpected," says John Watson, MD, who was a project officer for the LVAD study. "One of the original ways of treating heart failure was with bed rest, and some people recovered. It's like putting a bone in a cast, giving the heart time to heal."
However, Rose is cautious. "I think that the effect has been overrated," he says. "I've seen people who can have their LVADs removed successfully, but I've seen others who have had their hearts fail again afterwards. I think that success is the exception rather than the rule, and it all depends on the mechanism of heart failure in the first place."
Rose does believe that LVADs technology for heart-failure treatment will improve and become more widely used with time.
"I think that LVAD usage will be analogous to kidney dialysis," says Rose. "When dialysis was first introduced in the 1960s, it was only viewed as a bridge to kidney transplantation. But as the technology developed, it's gotten to the point where people can live on dialysis for decades."
Implants for Everyone?
According to many, the biggest obstacle to the widespread use of devices in heart-failure treatment is its costs. Drug treatment is definitely cheaper, and for the short term, most people with heart failure are likely to be treated with drugs and not devices. However, costs for devices will probably drop, according to experts.
"If you have something this effective in this large a market with more than one company making the devices," says Bristow, "the costs are going to come down."
Many experts observe that medical breakthroughs are always followed by concerns about costs. "People said the same thing about coronary bypass surgery, pacemakers, and defibrillators," says Watson, director of the clinical and molecular medicine program in the National Heart, Lung and Blood Institute's Division of Heart and Vascular Diseases. "By cost-effectiveness analysis, pacemakers and implantable defibrillators show that they save money in the long run."
As a society, we may also have a blinkered view when it comes to evaluating medical costs. "We have an inappropriate way of looking at the price tags for these devices," says Jay N. Cohn, MD, from the cardiovascular division in the department of medicine at the University of Minnesota Medical School. "Yes, an LVAD might cost a lot, but saving a single life with an airbag costs $25 million. That's money from taxes that we all pay to put airbags in every new car and no one raises an eyebrow at that."
Rose agrees, and argues that the high costs depend on the comparisons we use. "If you compare implanting an LVAD with administering a measles vaccine, an LVAD is going to be a lot less cost effective," he says. "But there are other procedures that have become accepted, like radiosurgery for brain tumors, that are even costlier."
Still, the costs are a serious impediment right now, and a great deal depends on what kind of coverage insurance companies provide. As more and more devices are developed, experts are working to devise better ways of figuring out who will benefit from them the most.
The Future of Device Treatment
Bristow says CRT is just the first wave of new devices designed for different aspects of heart-failure treatment.
"They're working on anything you can imagine," he says. He mentions devices that will physically restrain the heart from enlarging -- a process that leads to worsening heart failure -- and others that will correct leaking heart valves.
Devices like LVADs may offer a glimpse into heart-failure treatment for end-stage disease in the future. While stories about fully artificial hearts tend to grab headlines, such devices have limited use at this point. "The problem with the total artificial heart is that, as elegant as they have become, they still have to be absolutely flawless," says Rose.
LVADs, which use technology to supplement the heart's natural function, may be a more realistic approach in the near future. ""It's the best way to improve the quality of life for these people," Watson tells WebMD. "Although we talk about it a lot, our chances of making a bionic person are still pretty remote."
Although devices are sometimes compared unfavorably with drugs because of their costs, many experts consider it a misleading comparison. Instead, devices and drugs will be developed to work together for heart-failure treatment. For instance, Bristow became involved in CRT not because of an inherent interest in mechanical devices, but because he thought that CRT had the potential to improve heart-failure treatment with medications called beta-blockers.
Watson agrees and believes that heart-failure treatment with both drugs and devices will be important. "So far though, I don't think that there's been enough of a concerted effort to study the combination of drugs with devices," he says. "Most trials tend to look at one or the other."
Devices may prove to be useful tools for implementing promising new heart-failure treatments, such as cell implantation or gene therapy. "What we do now is called passive bridge to recovery, where we put in the LVAD and hope that whatever is wrong with the heart naturally works itself out," says Rose. "I think what we'll see in the future is active bridge to recovery where, in addition to putting the device in, we'll administer cells, or genes, or new or even old drugs to help repair the heart. Once the therapy works, the device could be removed."
In the use of device therapy, two things are certain: The next decade will bring a slew of new devices for heart-failure treatment and they will be considerably smaller and more refined than the ones now available.
"I think we've really entered the era of devices in heart failure," says Bristow. "And I think there will be rapid progress on multiple fronts in the next five to ten years."
Originally published April 2003.
Medically updated Sept. 30, 2004.
SOURCES: Bristow, M. The New England Journal of Medicine, May 20, 2004; vol 350: pp 2140-2150. Susan J. Bennett, DNS, RN, Professor in the School of Nursing, Indiana University, Indianapolis; affiliated scientist, Indiana University Center for Aging Research. Michael R. Bristow, MD, PhD, University of Colorado Health Sciences Center, Denver, Colorado; co-chair of the COMPANION study. Jay N. Cohn, MD, Professor, Cardiovascular Division in the Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota; past president of the Heart Failure Society of America. Marvin A. Konstam, MD, Chief of Cardiology, New England Medical Center; Director of Cardiovascular Development, Tufts-New England Medical Center; President of the Heart Failure Society of America.Bertram Pitt, MD, Professor of Internal Medicine, University of Michigan; Principal Investigator for EPHESUS and RALES trials. Eric A. Rose, MD, Chairman of the Department of Surgery, Columbia University College of Physicians and Surgeons; Surgeon-in-Chief, Columbia Presbyterian Medical Center, New York-Presbyterian Hospital; principal investigator for REMATCH trial. John Watson, MD, Director of the Clinical and Molecular Medicine Program in the National Heart, Lung and Blood Institute's Division of Heart and Vascular Diseases; project officer for the REMATCH trial.