Stanford Medicine Newsletter Updates For the Local Community

 

Natural solutions

Leading the way in using heart patients' own tissue to repair damaged valves

Joseph Woo repairs aortic valves, a difficult and painstaking job most other heart surgeons decline.

   

Nathan Healey was in the prime of his life, a successful tennis pro who had been a contender at the Australian Open, when his heart erupted. A seemingly healthy 32-year-old, he was puttering around his house in Reading, Pennsylvania, when he felt a tightness in his chest.

"All of a sudden, I felt dizzy and my heart rate was rising. I guess that is when something blew inside," Healey, now 37, recalled recently from his home near Sydney, Australia.

An ambulance ferried him to the local emergency room, where doctors found that a hole had ruptured in the center of his heart, releasing a stream of blood into his system. Healey was transferred to the University of Pennsylvania medical center, where the cardiac surgeon on call, Joseph Woo, MD, greeted him before midnight with some grim news.

"I remember hearing Dr. Woo say, 'Chances aren't good, but I will see what I can do,'" Healey recalled.
Woo, now chair of cardiothoracic surgery at Stanford, discovered that Healey had been born with some previously undetected heart defects, including a weak spot that had progressively enlarged and finally burst open. He had other abnormalities in his aorta, including an aortic valve whose three flaps were of different sizes, making it hard for the valve to close properly.

In the operating room, Woo faced an urgent decision: Should he try to repair the defective valve, using Healey's own tissue, or should he just replace it with a mechanical or animal valve, as was the more standard procedure?

Woo knew that Healey's athletic career would be over if he replaced the faulty valve, as the replacement options either would not be durable enough or would require him to take lifelong medications that would limit his physical activities.

He decided to take the extraordinary step of repairing the valve, doing some creative trimming and sculpting. He cut out one of the three oddly shaped flaps and used that tissue to fashion two flaps of equal size. He also rebuilt some of the surrounding tissues as part of the seven-hour procedure that saved Healey's life and livelihood.

"It was an epiphany," Woo said. "We're always thinking, 'How do you use what's there and take advantage of it?' That's the fundamental concept to natural valve repair — to use what's there in whatever creative manner you can to design something that works."

That philosophy has put Woo in the forefront of the movement toward natural valve repair, which evolves as surgeons devise new techniques and gain experience.

Valve history

Modern-day valve treatment goes back to the 1950s, when the introduction of mechanical valves enabled doctors to replace the diseased tissues with a substitute made of mechanical parts, similar to the valves found in car engines, Woo says. Mechanical valves are effective and last a lifetime, but they have a major drawback in that blood tends to stick to them and form clots. As a result, patients have to take blood-thinning medications, which require regular monitoring for side effects, such as excessive bleeding and stroke.

An aortic valve as seen during a surgery to repair the valve and replace a diseased section of the aorta.

   

In the 1970s, another alternative came to the fore: prosthetic valves taken from the cadavers of pigs or cows. These can work well but aren't as durable, particularly when used in younger patients, who have greater heart demands. Animal valves can wear out in 10 to 15 years, so patients have to undergo a second replacement and endure the risks of another surgery.

Because none of these replacement options are ideal, surgeons have turned to creatively restructuring damaged valves using the patient's own tissue. Multiple studies have shown that patients who undergo mitral valve repair do better overall: They are more likely to survive, spend less time in the hospital, and suffer fewer complications, such as infection and stroke, compared with those who receive substitute valves, whether animal or mechanical.

Fixing the aortic valve

While mitral repair has gained greater acceptance, aortic valve repair is far less common, as the valve is very different in both form and function. For instance, while the mitral valve has two flaps, the aortic valve has three, so a surgeon has to effectively line up three sides for the valve to open and close properly, Woo says. There is also less tissue to work with in an aortic valve repair, and different techniques and finer sutures are needed, he says.

In the 1990s, two surgeons, Tirone David, MD, and Sir Magdi Yacoub, MD, pioneered a technique to preserve the aortic valve in patients with aortic aneurysms, or a bulge in the vessel that can cause it to rupture.

In the procedure, known as valve-sparing root replacement, surgeons cut out the diseased part of the aorta and replace it with a tube of Dacron polyester, known as a graft, which is stitched to the heart. Instead of cutting out the aortic valve, as was done in the past, surgeons preserve the patient's tissue and reimplant it inside the new tube, sometimes refashioning the valve to fit the space.

In the operating room

One morning in the fall, Woo was called in to perform a variation on this procedure at Stanford Hospital for a man in his 50s who had endocarditis — a heart infection — which had damaged part of the aorta, including the valve. The patient was put on a heart-lung bypass machine, which took over the function of his heart and lungs while the surgical team did their work. Before Woo began, he viewed the heart on an echocardiogram, displayed on a nearby screen. It showed the valve leaflets flopping back and forth, indicating significant destruction.

He and his team began by cutting out the defective root, then meticulously removing 20 fragments of diseased tissue from around the faulty valve. They replaced the aortic root with an inch-wide Dacron tube, which they anchored in place with multiple blue Gore-Tex sutures. Then came the most challenging part: sewing what remained of the patient's valve back inside the tube.

"Imagine tailoring a suit but from inside the suit," said Woo, as he worked inside the narrow tube, meticulously stitching the valve in place and shaping it so that the leaflets were evenly aligned. It's a procedure many surgeons won't attempt, as there is very little valve tissue left to work with. But for the patient's sake, Woo was determined to make it happen. After more than five hours, he was satisfied with the results: "It's opening up nicely and working beautifully. This guy will keep his own valve over time."

All-repair philosophy

In general, Woo says, he likes to approach each patient as a potential candidate for repair, though he realizes it's not always possible. For instance, in patients with aortic stenosis, or a narrowing of the vessel, the leaflets may be so thickened and damaged by calcium deposits that they can't be manipulated and preserved. But he is nonetheless guided by an all-repair philosophy.

"We believe, in our hands, we can try to approach everyone as potentially reparable," he says. "No one should be viewed as automatically not a candidate. Everyone should have an opportunity."

He says he often gives talks to cardiologists and cardiac surgeons throughout the world, trying to promote the concept and techniques of repair. "It's an ongoing challenge to educate the community that aortic valves can be repaired," Woo says. "Either they have never heard of it or they've never seen it done effectively by a surgeon. Or they don't want to try it out until there is long-term durability data," which is not yet available.

As for Nathan Healey, he fully recovered from his marathon repair procedure after spending 10 days in the hospital. Woo implanted a pacemaker in his heart, as the rupture had disrupted its natural rhythm. Healey was able to return to professional tennis and three years later went on to try his hand in the 2015 U.S. Open — likely one of the few players with a pacemaker to compete at that level.

In the fall of 2016, he moved with his family back to his native Australia, where he now coaches tennis and competes in the occasional tennis tournament.

"I'm just incredibly grateful to be enjoying the life I'm living," he says. "A lot of fortunate pieces fell into place that night. I was lucky to get the surgeon and I was lucky to get the repair."

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