BMC surgeon pioneers heart surgery for atrial fibrillation
This story was published in the BU Bridge on February 25, 2005.
David Richard’s heart has been ticking a steady rhythm since Richard Shemin, chief of cardiothoracic surgery at Boston Medical Center, performed an innovative procedure to steady his erratic heartbeat on January 12. Like 2.2 million other Americans, Richard, a 75-year-old man from Reading, Mass., suffers from atrial fibrillation, a condition where his normal heartbeat slips into a kind of spasm and the two upper chambers, or atria, quiver instead of effectively squeezing blood into the lower chambers. Shemin is one of three surgeons nationwide trained to use a device that delivers high intensity focused ultrasound (HIFU) energy, which, he says, promises to revolutionize the treatment of atrial fibrillation.
“This new procedure takes less time to complete than the open-heart surgery or catheter-based treatments,” says Shemin. “It optimizes patient recovery time, and it has an over 85 percent success rate.”
In a landmark operation, Shemin opened Richard’s chest and wrapped around his heart a device that focuses high-intensity ultrasound waves into the atria. The waves heat the tissue, burning a precise pattern into the walls of each chamber. The burns become scars, Shemin says, which help to fix the underlying problem in atrial fibrillation: wayward electrical signals in the heart.
In a healthy heart, Shemin explains, electrical signals travel along fixed pathways, triggering muscle fibers to squeeze or relax in a carefully choreographed sequence. But in patients with atrial fibrillation, the electrical signals deviate from their pathways, throwing off the synchronous beating. “I was constantly in and out of it,” Richard says. “It felt like my heart was going to come out of my chest — it would be fluttering like crazy. I was afraid to go anywhere in case this came on when I was away from my doctors.”
Scar tissue does not conduct electrical impulses, Shemin says, so cardiac surgeons create a series of scars that function like levees and dikes in a river, channeling the flow of impulses along a single route. For the past 20 years, surgeons have accomplished something similar using the so-called Cox-Maze procedure, which involves opening the heart itself and cutting a maze pattern in the atria with a scalpel. “That complex operation was successful in over 90 percent of patients,” Sheman says, “and the vast majority of patients remained cured for 10 years following the surgery. But it was not widely performed by many surgeons because it required extensive training and it was time-consuming.”
Shemin was one of the early adopters of the Cox-Maze, but he soon began searching for a simpler technique that could be more widely replicated. “As we’ve learned more about what triggers these arrhythmias,” he says, “we’ve found that all of those incisions in the Cox-Maze were not always necessary. So then the question was, do you really have to cut and sew the incisions, or could you use different energy sources to create a burn that would produce a mini-maze pattern of scar tissue in the atrium?”
Shemin envisioned a minimally invasive technique, where he wouldn’t have to stop the heart, because that requires using a heart-lung machine, which can introduce new complications. “I wanted to do this from outside a beating heart, I wanted a quick recovery time, and I needed it to be highly reliable and reproducible,” he says. In other words, he wanted a procedure that didn’t require “a virtuoso super heart surgeon” at the helm.
Over the past 15 years, Shemin has occasionally put down his scalpel to experiment with alternative tools in the Cox-Maze procedure. He’s tried lasers, microwaves, and “cryo” (a freezing technique), all of which had pluses and minuses. But then he was contacted by a startup company called Epicor Medical, Inc., in Sunnyvale, Calif., which was building an instrument that delivers high-intensity ultrasound waves. As an energy source, ultrasound seemed perfectly suited for the job, Shemin says, because it penetrates the layer of fat outside the heart and doesn’t damage major coronary arteries along the surface. It can also be tightly focused, reducing the possibility of inflicting collateral damage to structures around the heart, such as the esophagus.
Epicor was last year acquired by St. Jude Medical, Inc., which is now manufacturing a device that looks something like a flexible U-shaped umbrella handle. The surgeon opens the breastbone and snugs the collar around the heart’s upper chambers. “Then you turn on the computer that controls each of the little segments that focus the ultrasound,” Shemin says, “and you’re done about 10 minutes later.” He currently uses a sternal incision, opening the chest through the breastbone to approach the heart. “But we’re working on techniques to insert the device through small incisions between the ribs to further make it less invasive,” he says.
Shemin flew to Lyons, France, last year during a European trial to learn how to use the device. He’s performed six procedures at BMC, which is the only hospital in New England, and one of three sites in the United States, to currently offer the new, less invasive surgical treatment.
While most doctors currently treat atrial fibrillation with medications to slow the heart and prevent blood clots, Shemin says, the new surgery is preferable for a number of reasons. “Medical management is not very good,” he says. “Many of the patients are still in atrial fibrillation while they’re taking powerful medication, some for the rest of their lives.” The medications have a number of side effects, such as extreme fatigue. When medicines don’t work, patients can receive cardioversion, where electrical paddles are applied to the chest to shock the heart into normal rhythm. Richard received this treatment six times. “That would work for a month or two,” he says, “and then I’d be back in atrial fibrillation again.”
Another treatment involves inserting a catheter through the leg and threading it up inside the heart. The tip of the catheter has an instrument that shoots short blasts of high-energy radio waves into the heart, creating scars. The problem, Shemin says, is that it’s difficult to align the catheter in the right spot, and the success rates for the procedure are not as high as the Cox-Maze. Catheterization also can take four to six hours, while surgery is rarely longer than 90 minutes.
Richard had had a catheterization done at another hospital. “It was a complete disaster,” he says. “I thought it was going to cure it, but made me feel worse than before.”
Richard’s cardiologist referred him to Shemin, who told him he was a good candidate for the new ultrasound surgery, which had previously been done only in conjunction with other major heart procedures, such as coronary bypass or valve replacement. Richard’s operation would be the first “stand-alone” procedure, where Shemin would treat only the atrial fibrillation on a beating heart.
“I was a little hesitant at first,” Richard says, “because it was the first one in the world and I was the guinea pig. But it’s turned out just absolutely great. I have a little more energy, but I’m still recuperating, of course. It feels good to not feel like your heart is coming out of your chest. As hospital experiences go, that one wasn’t bad at all. They won’t say whether it was a success for a few months, but the way I feel now is absolutely fantastic.”