DALLAS, May 29 – A 53-year-old German man became the first person to undergo a new, non-surgical technique that turned one of his coronary veins into a coronary artery to bypass a blockage, according to a special report in today’s Circulation: Journal of the American Heart Association.
“This milestone marks the first coronary artery bypass performed with a catheter,” says lead author Stephen N. Oesterle, M.D. “The technology offers a realistic hope for truly minimally invasive bypass procedures in the future.” The procedure, called percutaneous in-situ coronary venous arterialization (PICVA), involved connecting a vein to an artery that has been blocked.
The new procedure may offer a treatment alternative for heart patients with severely clogged arteries who are unable to undergo traditional bypass surgery or angioplasty. Traditional bypass surgery requires opening the chest and taking a blood vessel from either the calf (saphenous vein) or chest (internal mammary artery) to bypass the clogged coronary artery.
“One of the most invasive things you can do in medicine is coronary artery bypass surgery. Our ultimate goal is to replace traditional coronary artery bypass with a procedure that does not require surgery,” says Oesterle, director of invasive cardiology services at Massachusetts General Hospital and associate professor of medicine at Harvard Medical School in Boston.
According to American Heart Association statistics, 336,000 people underwent coronary artery bypass surgery in the United States in 1998. Oesterle says more than 100,000 patients each year may be ineligible for either bypass surgery or balloon angioplasty because their arteries are too severely clogged. These ineligible patients are the same ones being targeted for other experimental techniques including laser heart surgery and gene therapy, he says.
An international team of researchers performed the procedure at the Krankenhaus der Barmherzigen Brüder in Trier, Germany, on a man who had one heart artery blocked almost its entire length by atherosclerosis, the buildup of fatty deposits in vessel walls. As a result of his blocked artery, the man suffered severe chest pain, but he was not a candidate for bypass surgery or balloon angioplasty.
The team performed the new procedure in November 1999, and the man remains pain-free and living a far more normal life today, says Oesterle. Oesterle says he was able to use a vein for the bypass because veins are not affected by atherosclerosis. “No matter how badly diseased the arteries are, veins are seldom diseased.”
Arteries route blood from the heart’s pumping chambers to the rest of the body. Coronary arteries branch off the heart’s largest artery, the aorta, and deliver oxygenated blood to the heart muscle. Running near and parallel to some of the coronary arteries are coronary veins, which return deoxygenated blood back to the heart’s pumping chambers. Oesterle explains the body’s system of arteries and veins running beside one another and carrying blood in opposite directions as a sort of “vascular highway.”
In PICVA, an ultrasound-guided catheter system developed by the research team is inserted into an artery in one leg, threaded up through the aorta, and into the coronary arteries. The procedure is performed by cardiologists in a cardiac catheterization lab. In their first patient, the heart muscle served by his clogged left anterior descending coronary artery was alive but starved for oxygen, which was the cause of his severe chest pain. Only the very top of the artery was open and receiving blood. The catheter was inserted into the top of the diseased artery. Then, guided by ultrasound, a physician pushed a needle from inside the catheter through the artery wall and into the adjacent vein.
Next, a thin, flexible wire was threaded through the needle and the needle and catheter were withdrawn, leaving the wire behind. Following the wire like a monorail, a small angioplasty balloon was then used to widen the channel and a tubular device similar to a stent was inserted to keep it open for blood to pass though.
Finally, the vein itself was blocked just above the new channel. Blood from the artery had now been re-routed down the vein. After the procedure, blood flowed in a reverse direction to nourish the heart muscle that was previously starved for oxygen, rather than following the normal course of the vein up to the heart’s pumping chambers.
To use a traffic analogy: The procedure “detours” the patient’s blood flow around the artery blockage by using the neighboring vein. The arterial blood “crosses the median” and continues on its way headed towards oncoming traffic. Because there is a “roadblock” in the vein, the oncoming traffic has to turn around as well, and it all heads the same direction back to nourish the heart muscle.
“The technique described in this report is ingenious,” says Timothy Gardner, M.D., chief of cardiothoracic surgery at the Hospital of the University of Pennsylvania, and a national spokesperson for the American Heart Association. “However, it can be used only for an unusual type of coronary blockage – that is, in an artery that is open in its first portion, closed in the middle and still supplying good heart muscle.
It is very premature to suggest that this technique will significantly reduce the need for coronary bypass surgery in the near future.” David Faxon, M.D., president-elect of the American Heart Association, says the procedure offers hope for individuals with chronically occluded vessels, a group that is increasing in number. “But it won’t be a solution for everyone. The reality is that veins are not always located that close to an artery, so it wouldn’t work under certain circumstances.”
Oesterle says that more trials are needed to prove the long-term outcomes of this procedure. The researchers are currently conducting a 20-patient trial at three sites in Germany to follow up on this work. They expect to begin clinical trials in the United States later this year.
In addition, researchers plan to expand the catheter-bypass approach to patients who have short stretches of complete artery blockage. In this procedure, two channels will be made between an artery and a vein so that arterial blood can flow around the blocked area.
Co-authors are Nicolaus Reifart, M.D.; Eugen Hauptmann, M.D.; Motoya Hayase, M.D.; and Alan C. Yeung, M.D.
The above post is reprinted from materials provided by American Heart Association. Note: Content may be edited for style and length.
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