Published: Jan. 21, 2011
Updated: Jan. 21, 2011
By Kathleen Yount
Sometimes it pays to be a zebrafish. You could stab a zebrafish in the heart, and that zebrafish would grow new heart muscle and keep on swimming.
This is not true of the human heart.
The human heart can take many an insult, that much is true. But after a heart lives long enough or suffers greatly enough, it will begin to give out. In fact, this is a guarantee for us all: if something else doesn’t get us first, eventually our hearts will fail.
Heart failure isn’t really a disease. It’s a syndrome -- a collection of symptoms that comprise the bottom of the great funnel of heart diseases, disorders, and distresses. Whether you get there as a side effect of cancer treatment, a devastating heart attack, an unlucky viral infection, or decades of high blood pressure or atherosclerosis, it is the state of being in which the heart simply doesn’t pump as strongly or effectively as the body needs it to.
Its symptoms stem from the body’s attempts to compensate for its failing pump -- the kidneys sense a reduced blood volume and compensate by retaining fluid, which begins to seep out into the body’s tissues and organs, causing swelling, lung congestion, and so on. Without the pump at its prime, the body starts to sputter, to stall out.
Between the body’s dogged insistence on survival and the advent of medical management breakthroughs such as ACE inhibitors and beta-blockers, many people who develop heart failure today can expect to live for years, perhaps with symptoms but also still very much able to work, travel, spend time with family and friends, even exercise. But heart doctors will tell you that once the condition reaches an advanced stage, heart failure patients are difficult to treat, and their quality of life is very poor.
“Surgical treatments for heart failure deal with the sickest of the sick,” says Carmelo Milano, MD, a cardiothoracic surgeon who specializes in care of heart failure patients at Duke.
“When you talk about medical management of heart failure, many of those patients still have some mobility, they can still walk across the room. The patients we evaluate for advanced surgical options have symptoms of heart failure even when they’re at rest.”
They can’t sleep, eat, bathe, or even enjoy the comfort of a loved one’s touch without the constant companion of half-drowned breathing, fatigue, and pain. They are moribund; they are out of options.
Unless, of course, they can be brought back from the brink. Advanced heart failure has one well-established treatment, and that is transplant. The success rate of heart transplant is booming today, boasting nearly 87 percent one-year survival nationwide (at Duke it’s 88.7) and 54 percent 10-year survival (59 percent at Duke).
For the transplant team, Milano says, the gig can really mess with your personal life -- “It’s emergency surgery, so we’re often operating in the middle of the night. But the difference it makes in our patients’ lives, within just a month or two of the surgery -- it’s incredible. That’s what keeps drawing me to it.”
Every transplant surgery is an opportunity to recycle tragedy into triumph -- death makes possible life. But the trouble with transplant is just that: it depends on the unplannable, unexpected, and terrible loss of life.
And it’s not even as simple as that -- to be brought back from the dead, both the donor heart and the recipient must meet very stringent criteria. There are at least 150,000 people in the United States currently on waiting lists for heart transplants, but this year there will be only about 2,200 heart transplants performed.
In 2000, Duke created an extended criteria transplant program, which has given 70 hearts to patients who would otherwise not have been candidates and made use of donor hearts that would otherwise have not been transplantable. But even with the success of that program, patients and physicians are still confronted with a supply dependent on loss and woefully undermeeting demand.
“Transplant is a wonderful therapy,” says Duke cardiologist Joseph Rogers, MD, who works with Milano to care for patients with advanced heart failure. “But in the world I live in, there’s this huge clinical need, and there’s just not enough organs to help all of our patients. So the question becomes, what do you do to help the rest of these people?”
Former vice president Dick Cheney has a troubled heart, to be sure. At age 69, he’s already survived five heart attacks and undergone quadruple bypass, two angioplasties, and placement of an implantable cardiac defibrillator (ICD).
This summer, to treat his advancing congestive heart failure, he was implanted with one of the newest generation of VADs, or ventricular assist devices.
VADs are the current answer to the question of a viable artificial heart -- basically, they replace the heart’s left ventricle, which is its main pumping chamber. The device attaches to the heart, and its battery-powered pump (controlled by a small, externally worn computer) pulls blood from the left ventricle and sends it through the aorta.
It’s not clear whether or not Cheney ultimately will receive a transplant, but the choice to use a VAD to treat such a public figure may mark the turning point in public opinion on this type of technology.
Such heart pumps were originally approved by the FDA only for use as a medical stopgap, to keep a patient alive while he or she awaited a heart transplant. But recent studies at Duke and other institutions are showing that more and more patients are living with a VAD indefinitely -- and they are living well.
In his sixteenth-century Codex on the Flight of Birds, da Vinci declared that “a bird is an instrument working according to a mathematical law, which instrument it is within the capacity of man to reproduce with all its movements.” Milano uses that quote to remind himself of the possibilities that are in our grasp, such as a man-made replacement for a broken heart.
But Milano will be the first to say it -- a plane is not a bird. And when it comes to building a device that can replicate the human heart’s 100,000 daily pulses that circulate six liters of blood through thousands of kilometers of blood vessels, man’s now-conquered quest to fly seems rather like child’s play.
It’s hard -- maybe harder for the doctors than the patients -- to shake the memories of earlier “mechanical heart” devices. The well-publicized deaths of some patients in the late 1980s who were implanted with the Jarvik Seven -- an artificial heart that was powered by refrigerator-sized air compressors -- led that device to be dubbed in an often-cited New York Times op-ed as the “Dracula of medical technology.” Those patients suffered postsurgical infections, sepsis, delirium, and organ failure.
But by 1994 a new model of heart device -- the VAD -- was progressing through clinical trials. Instead of completely replacing the heart, these ventricular assists bolster the heart’s function by taking on the lion’s share of the pumping process.
These first models were in fact pulsatile -- they mimicked the pulsing action of the heart. The devices were exciting, but “everybody thought we wouldn’t be able to get these people out of the hospital,” says Laura Blue, NP, nurse coordinator for the Duke VAD program. “We had to push really hard and be very cautious. It took years to develop safe ways to discharge patients.” Through the late 1990s, Duke took part in several national trials to test the devices.
In November 2001, results of REMATCH, a national trial to compare VADs to medical management in patients who weren’t transplant candidates, were published in the New England Journal of Medicine (NEJM).
Positive outcomes in VAD patients helped garner the approval of the FDA first for use in patients who needed to buy more time while they waited on a transplant list, and then as the destination therapy itself.
In July 2003, Duke performed North Carolina’s first destination therapy VAD implant.
“We were the first hospital in our region who ever sent a VAD patient out in the community,” says Blue. “It was entirely new type of life support; so at first, for every patient we implanted, I went to their local EMS station and met with the chief and the training officer, so that they’d know what to do if the patient needed emergency care.”
According to just about everyone who worked on them, the VADs were “like breathing life back into dying people,” says Blue. “I always loved transplant medicine, but the VADs really felt like, wow, we were stopping the train headed off the cliff. While it was not easy, they were alive, they were going to make it.”
Though Duke patients overall had outcomes that exceeded even the REMATCH standards, as a widespread practice VADs were still problematic. The pulsatile models were “bulky, noisy devices that had lots of moving parts that would break frequently,” says Rogers.
It was to be counted on that, within a year or 18 months, something in the pumps would break, requiring another operation to replace the pump. A Duke study published in November 2008 in JAMA showed that, among Medicare patients who received these pumps between 2001 and 2006, the one-year mortality was still high -- 45 percent -- as was cost.
“We learned several things from that study,” says its lead author, cardiologist Adrian Hernandez, MD, who like Rogers cares for VAD and transplant patients at Duke. He says the data showed that, like other highly complex technical treatments, one of the most important factors in determining outcome was the experience of the team who performed the procedure.
Hospitals with smaller procedure volume trended toward poorer outcomes than hospitals with more frequent procedures. And when you’re dealing with an $80,000-per-person technology, as Hernandez says, “we really want -- and really need -- to be responsible citizens with this.”
By 2008, though, design of the pumps had taken a new leap: a new generation of continuous-flow pumps, such as the HeartMate II, had abandoned the notion of pumping like a heart in favor of a tube-shaped axial flow pump, which boasted only one moving part and was one-seventh the size of its pulsatile predecessor.
Rogers and Milano helped lead the study to test this new model, and the results -- presented and published in the NEJM in November 2009 -- showed that after one year, 68 percent of patients on the continuous flow VAD survived, compared to 55 percent in the pulsatile flow group.
Following the second year, 58 percent survived (compared to 24 percent with the older device).
“And there was a 38 percent reduction in patients who needed to be re-hospitalized in the continuous-flow group,” says Hernandez, noting that heart failure is the number-one contributor to the country’s rates of hospital readmissions.
These reduced re-hospitalizations were attributed to significantly fewer major adverse events, including infection, difficulty breathing, kidney failure, and cardiac arrhythmias.
Outside the hospital, the HeartMate II patients were thriving. Heart researchers will often reference the “meters walked in six minutes” as a metric of the effectiveness of a new intervention in heart failure. Rogers explains that this measure is particularly important, because it represents the difference between a person who can go to the grocery store, go to church, go to his family reunion, and the person who cannot.
“Our patients don’t exercise on treadmills every day,” says Rogers. “But we want them to be comfortable doing what they like to do—going out to eat, shopping, golfing.”
According to the Duke research, compared to people living with heart failure, the improvement in these kinds of quality-of-life scores go up dramatically within three months of implanting a HeartMate II pump, and they stay high for at least two years (the longest period of time studied so far). “The improvement in this measurement went up more than any other therapy we’ve tested in non-transplant advanced heart failure patients,” says Rogers.
Duke cardiologist Michael Felker, MD, who is also on the transplant and VAD team, adds that there are few things in medicine that you can call a magic bullet, but this kind of change in patient quality of life qualifies.
“You can almost think of the VAD like you think of the iPhone,” he says. “Every generation gets a little better.”
On paper, the benefits of being on a pump seem myriad -- until you remember that the patient has a driveline coming out of her abdomen. The pump sits in the chest, and a small tube connects it to the computer, which is worn holster-style around the patient’s hips.
“It’s not forgettable therapy -- you have batteries, you have a computer, and you have to wrap your head around the notion that you will run on batteries from now on,” says Blue. “I’ve had patients say, ‘Thank you for telling me about this, but it’s not for me.’ And that is the right choice for some people -- I will be the first one to tell anybody that living with a VAD is not going to be easy.”
Blue says that, when the VAD team talks with a heart failure patient about the possibility of placing a VAD, they must take the whole patient into perspective.
“We put these pumps into people who have family to help care for them and a place to go when they leave the hospital. We don’t recommend to anyone that they plan to live alone, at least not at first. We use a caregiver contract, we train them,” she says. “And in some ways it’s harder in younger people, for dual-career households, because early after surgery we ask someone to be with the patient all the time.”
New batteries that weigh less and hold a longer charge have helped ease some of the logistical burdens, and patients leave the hospital with extra batteries and an extra controller. But still, says Blue, it’s an adjustment.
“I’ve run out to the front of Duke Hospital and stood in the middle of Erwin Road, because a patient who came in for her first clinic visit after surgery left her batteries hanging on the back of her wheelchair in the parking garage. Her alarm started going off halfway back to Rocky Mount . . . so there she was, barreling down Fulton Street, and they whipped around the hospital driveway and I was jumping into the car to change out the batteries.”
To some VAD patients, Blue says, the grass looks greener on the transplant side of the fence. “Other than when they take their handful of pills every day, transplant patients can almost pretend that they have a normal life -- they don’t necessarily have to be confronted with their illness every day. And transplant is still the gold standard -- so when we can transplant a patient, we do."
"But transplant patients who have problems, who are sick or have rejection episodes, they can struggle just as much. And they don’t get to give their transplants back. So it’s a decision that we make very carefully. When the VAD patients get past the recovery from their surgery, and they are up and walking, and having a normal life . . . They can’t believe it, how much better they feel.”
The successful outcomes of the new VADs are raising a lot of questions -- and a lot of expectations.
A Duke study found that outcomes in VAD patients and Duke’s extended-criteria transplant patients are the same after two years, and physicians like Rogers and Milano are exploring the idea of placing the devices in patients who are less advanced in the disease process.
This idea is encouraged by outcomes from the HeartWare device, an even smaller, newer VAD design. Investigators at the November 2010 American Heart Association meeting in Chicago reported one-year survival that was greater than 90 percent for patients who received a HeartWare VAD.
“We’re also collaborating with industry partners to evaluate new, experimental devices,” says Rogers. “We’re looking at partial-support devices -- some of those are the size of a AA battery, and they sit in a pacemaker-like pocket in the chest.”
Such devices may supply two or three liters of blood, which is less than the six or seven liters that current pumps flow. But they could be put in with less morbidity, less invasive procedures, and allow these patients to feel better and to function better.
Rogers says that the possibilities give a new optimism to the care of these patients who were once at death’s door.
“There aren’t many chances in medicine to do this,” says Rogers, “where you can take a technology that has such profound effects on patients and how they feel, and actually help it advance.”
“There’s clearly a point when heart failure progresses, when the physician has done the best that can be done with medications, when the VAD option should be considered,” says Blue. “It isn’t for everybody, but for those who say ‘Look, I’ve got grandchildren to raise,’ or ‘I just retired, I was looking forward to a great life -- I want more years’ -- the VAD can give it to them."
“I’ve got an 83-year-old patient who was 80 when we did his surgery, and he’s still going. And the only thing that limits his golf game is his wife.”