Keeping the Beat
by Jill Spotz
rom the time it starts beating at 21 days after conception, the human heart works tirelessly, pulsating over three billion times in an average lifetime, pumping blood through the body until its work is complete. For the lucky ones, the heart is silenced only after a long life is lived. When it threatens to stop earlier than expected, many medical options can keep the beat going in the most important muscle in our body.
Heart failure occurs when the heart is not able to pump enough blood through the body. It is estimated to affect 5 million people in the U.S., with about 500,000 new cases cropping up each year. The condition can be acute or chronic and involve the left, right or both sides of the heart. Ronald Freudenberger, MD, director of Advanced Heart Failure and Transplant Cardiology at Robert Wood Johnson University Hospital (RWJUH), and associate professor at the medical school, notes that heart failure is the only major cardiovascular disorder that is increasing in incidence and prevalence.
Freudenberger and his team are using a new implantable device called a hemodynamic monitor that is showing great promise in the management of this disease. The device continuously tracks intracardiac pressure, body temperature, physical activity and heart rate in patients suffering from cardiac failure. “Pressure changes in the heart often precede an event and can be one of the symptoms of a failing heart,” says Freudenberger. “A daily record of the heart’s activity can be transmitted via the internet to the heart specialist, while the patient is comfortable at home. The sensor allows us to monitor the patient’s medications and treat the condition before it becomes worse or before someone requires hospitalization,” he explains.
The hospital is one of 28 clinical sites in the U.S. enrolled in this COMPASS-HF (Compass Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure) randomized clinical trial. A total of 274 patients with Class III or IV (the most severe) heart failure are included. Freudenberger notes that they have implanted the device in nine patients at RWJUH with great success. The monitor is manufactured by Medtronic and is expected to receive FDA approval this year.
For an individual whose heart is irreversibly damaged and who is at risk of dying from long-term heart disease, heart failure or heart injury, a transplant may be the only hope. “Heart transplantation is still the star for end-stage heart failure,” explains Freudenberger. According to the most recent American Heart Association data, the one-year survival rate following heart transplantation is 86.1 percent for males and 83.9 percent for females; three-year survival is 78.3 percent for males and 74.9 percent for females; and the five-year survival is 71.2 percent for males and 66.9 percent for females. The problem is not in the survival statistics but in the number of individuals waiting for a transplant. There are currently 2,825 in the U.S. on a waiting list with an average wait time of 230 days.
Freudenberger explains that although the demand for heart transplants has remained the same and survival rates have only gradually increased, medical therapy is catching up. His research on the success of medical therapy was published in the journal Circulation in July 2006. “There were no studies to date comparing heart transplantation to optimal medical therapy,” he explains. “We created a decision analytic model that simulated a randomized clinical trial of heart transplantation versus medical therapy. The model predicted that optimal medical therapy is superior to heart transplantation for Class I, II, and III patients. But heart transplantation is still the best option for Class IV patients.” Freudenberger notes that in addition to medical therapy, there are new devices used as bridges to transplant. Also, implants that were once a temporary fix are now considered a permanent solution.
One of these temporary implants to buy time in situations where cardiac dysfunction is potentially reversible is the Impella 5.0. Manufactured by ABIOMED, the miniaturized ventricular assist device is delivered through a catheter and can support the heart with up to 5.5 liters of blood per minute. The Impella is implanted by inserting it into an artery in the groin and passing it up into the heart or directly to the ascending aorta. “This research device offers hope for patients previously considered too ill to be operated on by providing temporary support for the heart muscle during the critical period after a heart attack or surgery,” explains Mark Anderson, MD, associate professor of surgery, chief of cardiac surgery, director of cardiopulmonary transplantation and principal investigator of the trial. He has implanted the Impella in five patients so far. All of the patients survived and were slowly weaned from the device. RWJUH is one of seven hospitals participating in the FDA Phase 1 clinical trial and the only hospital to date to have implanted any devices. “The Impella is unique because it is less invasive than a conventional ventricular assist device (VAD), yet offers the same amount of support,” explains Anderson. “It is also better than a balloon pump because it offers more support. A balloon increases cardiac output by 15 percent, whereas the Impella can support the entire left heart circulation.” The Impella is intended to be used up to seven days and once it is removed, the hope is that the patient’s heart will take over. This process of resting the heart — called unloading — allows it to “take a vacation” and recover following a heart attack. If the heart does not regain its ability to pump, a more permanent assist device would be implanted.
For those patients in end-stage heart failure and in need of a long-term solution, Anderson and his team implant ABIOMED’s AB5000 or Thoratec’s HeartMate®, depending on the patient’s medical situation. Both ventricular assist devices provide long-term support for the heart in end-stage heart failure, giving the organ an opportunity to recover, and allowing patients to survive while waiting for a transplant.
The AB5000, which can assist one or both sides of the heart, requires that the patient remain under close medical observation, though a console offers mobility throughout the hospital and on hospital grounds. The HeartMate®, which only supports pumping in the left ventricle, is a more portable device, offering the patient the opportunity to recover at home. Both can be left in for as long as they will sustain the patient. The components of both devices include an implantable pump, an external controller and a power supply. Anderson led a nationwide clinical trial on the use of ABIOMED’s AB5000. Results showed that patients who suffered a heart attack followed by cardiogenic shock (a sudden drop in blood pressure and blood flow), could recover when placed on the AB5000 for an average of 31 days. “Sixty-seven percent of the patients who survived the event were able to recover native heart function,” said Anderson. “We were able to restore our patients’ hearts and send them home without a transplant, which is a disease unto itself with a limited lifespan. If a heart can be allowed to recover good function, this is better than a transplant.” VADs were once considered a temporary solution but now have become a long-term treatment for select patients with heart failure. The HeartMate® has been FDA approved for long-term use for people who are ineligible for heart transplants known as destination therapy.
Keeping up with the times
Why the surge in new devices? “Because cardiac care is evolving along with its patient population,” explains Peter Scholz, MD, RWJMS James W. Mackenzie Professor of Surgery and chief, division of cardiothoracic surgery. “Coronary artery disease is not going away but deaths from the disease are decreasing. If you have a heart attack in this day and age, you are less likely to die than 10 to 15 years ago. People are living longer and those who survive a heart attack often go on to develop heart failure, which explains the ballooning population with this problem.” Surgeons have responded by coming up with alternatives to treating heart failure short of a heart transplant.
Aortic valve replacement – one such option – is performed on approximately 80,000 patients each year in the U.S. The procedure carries considerable risks in the elderly since it requires cardiopulmonary bypass and opening of the sternum. Scholz explains that researchers are devising less invasive methods to repair and replace valves. “There is an aortic valve in clinical trials currently in Europe and Canada that can be compressed and positioned in a metal cage. The device can be placed into a balloon and threaded through the leg vein, up into the aorta, allowing for easier access to the heart,” he says. “Unfortunately this approach is very difficult to do because the valve has to be threaded in a maze-like fashion with a series of turns to get to the aorta.” Although it is a promising method, Scholz says it is still very difficult. “Surgeons have devised a minimally invasive method of making a small incision in the chest offering a straight shot to the aorta through the tip of the heart,” he says. Scholz explains that this procedure offers an opportunity for cardiologists and surgeons to work together and with this new relationship comes a more efficient way of treating heart failure patients. “Hospitals are adding hybrid operating rooms, where a cardiac catheterization lab is actually inside an operating room,” he says. “We can offer angioplasty for smaller blood vessels and perform a catheterization or an aortic valve replacement at the same time.”
In 2001, history was made when a 58-year-old patient in Kentucky received the first fully implantable artificial heart. Initially, the man had less than 30 days to live but following the transplant, survived for several months. Since that time, 14 patients have gotten a second chance at life with the device that took more than 25 years to make. “The AbioCor is designed for the most severely ill, Class IV heart failure patients,” explains Anderson. “These patients have only a limited life expectancy, often measured in weeks or months, and are not candidates for a heart transplant.” RWJUH is one of only a few hospitals in the U.S. authorized to implant the device.
The AbioCor was approved in 2006 by the FDA under its Humanitarian Use Device Exemption (HDE), for patients who are not eligible for a transplant and are facing death. To receive this approval, the device must be proven safe. Clinical trials showed that a patient’s life can be extended by four and a half months. “These patients have no other options,” explains Anderson.
The two pound AbioCor contains an electrically powered pump that replaces the main pumping chambers of the heart. When implanted, the device’s thoracic unit, which is equipped with its own ventricles, is connected to the patient’s own atria and outgoing vessels, supplying blood to the lungs and to the rest of the body. The patient’s ventricles are removed. The device replicates normal function of the heart by circulating blood through the body and lungs. An implanted controller monitors the thoracic unit and can send and receive information that is not connected to the body through any wires. An implanted battery operates without a physical connection to the outside. A coil implanted under the skin receives energy from the external power source to recharge the implanted battery. ABIOMED is now working on the AbioCor II which is 30 percent smaller than the original and designed to last five years.
There is no doubt, the future of cardiac care is evolving along with its patient population. Endovascular and percutaneous procedures to replace blood vessels and valves and artificial pumps and total heart replacements are the wave of the future. “As assist devices become more advanced, we’ll be able to implant them in patients months before their hearts begin to fail, instead of when they are already in life-threatening distress,” says Scholz. Now THAT is a goal that would make 5 million heart failure patients very happy.
The critical goal to improve outcomes and reduce surgical risk has transformed many once highly invasive surgeries requiring days and sometimes weeks in the hospital to “mini” procedures with short hospital stays followed by home-based recovery. From cataracts to fibroids, from prostate enlargement to knee damage, more refined techniques and sophisticated technology are allowing physicians to repair a host of medical problems quickly and more simply.
for Ailing Hearts
By Susan Glick
When these improvements are applied to one of the most common ailments, heart disease, it is win-win all around. Today cardiologists routinely reach a heart without opening a chest through cardiac catheterization. A small tube, called a catheter, enters a blood vessel through a needle in the skin and is threaded to the heart. This catheter can support devices to open vessels, deposit implants and deliver other targeted heart treatments. With the advent of angioplasty in 1977, the insertion of a balloon to open a closed vessel, thedefinition of open heart surgery was transformed. Indeed, in 2003 (the most recent statistics available), according to the federal Agency for Healthcare Research and Quality, 82percent of all cardiovascular surgeries were done outside the traditional operating room.
At UMDNJ-New Jersey Medical School, Marc Klapholz, MD, director of the division of cardiology and associate professor of medicine, is studying the efficacy of plugging a hole in the heart to prevent recurrent stroke and provide patients with severe congestive heart failure an external pump to assume some of the heart’s work. Both procedures can be performed in one to two hours.
Of the more than 700,000 adult patients annually who experience a stroke, nearly 40 percent will never know why. Cryptogenic is the term used when there is no apparent underlying reason. New techniques in echocardiography allow physicians to recognize that many victims of cryptogenic strokes have a small open space — patent foramen ovale (PFO) — between the two upper chambers of the heart. The foramen ovale is used during fetal circulation. In some individuals, this hole does not close during infancy, but remains permanently patent, or open. Actually, the hole is more like a space between two unconnected flaps. That small space may be just big enough for a small venous blood clot to pass directly into the arterial side of the heart, which then pumps this clot through the aorta to other parts of the body. Once that clot enters the arterial blood stream, there is a risk of stroke.
In adults, PFOs are typically asymptomatic and discovered incidental to other findings.
The hole can be closed with an implant delivered into the heart through a tube inserted in the thigh. These small implants look like a cross between a spring-loaded balloon with a waist and a stick with open umbrellas on each end. The device provides a sheath over the hole on both sides of the septal wall, which is the center column of the heart separating the upper chambers. Because foreign objects can actually spur the formation of thrombi, patients are instructed to stay on blood thinning medication for three to six months after surgery. This gives the body time to grow a layer of cells over the entire device, permanently securing it and eliminating further risk of clot formation. Did the undiscovered PFO cause the stroke? Will plugging the hole prevent further strokes? If so, can this device prevent an initial stroke? These questions are currently unknown, and some of what the RESPECT clinical trial will determine. New Jersey Medical School has only recently joined this study and is fully prepared for its first patient.
Stroke prevention was not the original goal of closing PFOs with implants. Individuals with this condition are typically prescribed a blood thinning medication, such as warfarin or aspirin, as a first line of treatment. When this traditional approach fails or is compromised, a physician and patient may elect to have the closure device implanted. The non-invasive implantation technique is also used for a less common condition, arterial septal defect (ASD), another type of hole in the septal wall. That hole, however, is caused by incomplete fetal development and leads to ineffective blood circulation. ASD patients may present with symptoms of shortness of breath, fatigue, high blood pressure, abnormal heart rhythms, or strokes. It is almost always recommended that an ASD be closed.
More common than stroke is congestive heart failure (CHF), affecting nearly 5 million Americans. CHF manifests when a weakened heart can no longer pump blood efficiently. Blood flow out of the heart slows and backs up, causing congestion and swelling in tissues throughout the body. Individuals with CHF often suffer from fatigue, shortness of breath and become debilitated in the advanced stages. If patients with severe CHF meet the criteria for the MOMENTUM clinical trial, an external pump can be attached through tubes placed in arteries along the thigh to improve blood flow throughout the body. Amazingly, the “heart” of the pump is a magnetically levitated propeller-like device that spins freely in mid-air within its casing.
Essentially, this tube and pump system create an additional closed-loop flow circuit at the top and bottom of the descending aorta, which like a tree trunk, is the main canal that delivers enriched blood to the rest of the body. The pump strengthens circulation by adding force and momentum to the blood leaving the heart, thereby enabling greater amounts of enriched blood to reach distant parts of the body. This strengthened flow allows the body a short respite from chronic deficiency. It reduces congestion, swelling, and potential clotting, and damaged organs sometimes begin to recover.
Current protocol limits use of the pump to four days. The patient must remain in the hospital during this time. For a physician, the pump can buy critical time to establish different or more aggressive treatment. To date, only 140 patients nationwide have used this device, and eight of them have been at New Jersey Medical School. The next investigational stage of this device is to place the pump permanently within the body.