Cardiac patients are living longer and longer–up to 20 years after receiving stents, a heart bypass, or heart-valve replacements. But extended lifespan is often accompanied by other complications, as a repaired heart can still have difficulty getting enough oxygen. The accompanying pain, a squeezing pressure in the chest called angina, can plague patients for years, and there are some for whom no surgery can provide relief. But a noninvasive shockwave machine could help prompt the growth of new blood vessels, restoring the heart’s oxygen supply and alleviating the pain.
In a clinical trial at three centers across the United States, cardiologists are testing the safety of the shockwave device, developed by Maryland-based Medispec. The “Cardiospec” machine is based on the same sound-wave technology used to break up kidney stones, but it requires only about one-tenth the energy. “Shock waves are acoustic waves that create pressure that can be focused,” says Medispec’s Gil Hakim, the company’s director of new product development. Direct that pressure toward the heart muscle with just the right intensity, and it causes the body to produce new blood vessels.
Researchers aren’t sure precisely why shockwaves have this effect–they believe that the pressure may induce a cascade of events that mimic wound-healing, recruiting undifferentiated cells to the area to build blood vessels. Preliminary studies show that about 70 percent of the patients who undergo the shockwave procedure experience somewhere between a 60 to 70 percent improvement in blood flow to their hearts.
“Patients with [recurring] angina consume a lot of medical care because they have multiple emergency visits, they have multiple angiograms, and their quality of life is extremely low,” says Amir Lerman, a cardiovascular specialist at the Mayo Clinic in Rochester, MN, who’s heading up the Cardiospec trial. And, he notes, the treatments available to these patients to date are short-term therapies that address the symptoms rather than the cause. “These patients currently don’t have any alternative solution. And we need to find one because they live a long time.”
The trial will recruit 15 patients–five each at the Mayo Clinic, the University of California at San Diego, and Albert Einstein Medical Center in Philadelphia–and it will consist of nine treatments applied over a nine-week period (three treatments per week during weeks one, five, and nine).
The Cardiospec technology has already been used to treat about 1,000 patients worldwide, in Europe, Canada, and other regions around the globe. And so far, it seems that about two to three years after the original treatment, patients can experience a relapse. Many patients who undergo treatment don’t change their exercise habits or diets, their blood vessels begin to narrow, and once again their hearts can’t get enough oxygen. “It’s like when patients have undergone a stenting procedure,” Hakim says. “That won’t necessarily be the only stent, because they develop another problem in another area in the heart.”
It’s not that the shockwave treatment has failed. Rather, a patient ends up with the same problem in a different region of his heart. “It’s like maintenance–after a few years, patients can be evaluated, checked again, and then retreated,” Hakim says.
The options available for so-called “refractory angina” patients, who have pain after surgery or aren’t candidates for surgery in the first place, are quite limited, says Timothy Henry, an interventional cardiologist at the Minneapolis Heart Institute who’s not involved in the trial. “We definitely need new options, and this is an interesting one. The preliminary data looks very good, it’s low risk. I think this is a really good option, but it needs to be tested,” Henry says.
Lerman and his collaborators hope to complete the safety trial in a few months, and Medispec is aiming for U.S. Food and Drug Administration approval by 2012. Hakim is hopeful that the technology can provide relief for patients who are now completely dependent on oral medications to stem the tide of their angina attacks. “On average, before starting the treatment, the patients took their medication around three times a day. After the therapy, they’re taking it around three times a week. It’s a marked improvement in their quality of life,” he says. “It’s not a cure, but it’s an improvement.”