Novel Stent Relieves Acute Heart Pain
It diverts blood to oxygen-starved heart muscle, researchers say
MONDAY, April 23, 2007 (HealthDay News) -- A different kind of stent brought relief to some people suffering from refractory angina, a kind of heart-related chest pain for which there currently is no effective treatment, Israeli researchers report.
A conventional stent is a flexible tube implanted in an artery to keep it open. The new stent, being developed by Neovasc Medical Inc., a startup company in Tel Aviv, is designed to partially block a coronary blood vessel so that blood is diverted to areas of the heart muscle that are in pain because of inadequate blood supply.
"Neovasc's Reducer is an hourglass-shaped, stainless steel, balloon-expandable stent delivered on a proprietary catheter," said Dr. Shmuel Banai, an interventional cardiologist at Tel Aviv Medical Center and chief medical officer at Neovasc. The stent partially restricts the flow of blood draining from the heart by narrowing the coronary sinus, a vein that collects blood from the heart, to a diameter of 3 millimeters, he said.
"That's enough of a differential to drive arterial blood into ischemic (oxygen-lacking) zones of the heart muscle and to perfuse and nourish those ischemic areas," Banai said. "The coronary sinus narrowing induced by the Reducer is not severe enough to affect drainage and cause the complications of decades-old surgical attempts at various attempts at venous revascularization (blood flow restoration)."
A report in the May issue of the Journal of the American College of Cardiology described results of implantation of the stent in 15 patients with refractory angina in Germany and India. The angina score measuring pain improved in 12 patients, the report said, with echocardiograph and computed tomography showing a reduction in the ischemic area of the heart.
"There were no total occlusions, clotting or other complications noted at the end of the trial, and that is still the case two years out," Banai said.
An effective treatment for refractory angina is definitely needed, said Dr. Deepak Bhatt, associate director of the Cleveland Clinic cardiovascular coordinating center, because it now affects at least 500,000 Americans, and the number is growing.
"A very substantial portion of these folks I see have no option," Bhatt said. "We've tried everything there is to be tried, and they continue to have chest pain. There is an unmet need for better therapies for this unstable angina."
The new report is "intriguing" and "provocative," Bhatt said, but the number of patients in the study was small, and there was no control group that did not get the treatment for comparison.
"A placebo effect can occur," he said, so that just the thought of having an effective treatment can bring improvement. "These folks have no hope, so if you offer some hope, they can respond positively," Bhatt said.
Still, the concept "definitely is worthy of further study," Bhatt said.
Dr. Gregory Barsness, assistant professor of cardiology at the Mayo Clinic in Rochester, Minn., said, "This is a unique method in that it tries to improve blood flow by raising blood pressure. It is a small trial with incomplete follow-up, but it is a novel strategy that at least has been shown to be safe in a small group of patients and could be pursued."
Having refractory angina does not necessarily increase the risk of death, Barsness said, "but these people certainly are suffering greatly. This population of patients with refractory angina is growing and will continue to grow as the population ages. Any strategy that improves the quality of life without morbidity and mortality would certainly be welcome."
For more on angina, visit the U.S. National Library of Medicine.