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Cardio-vascular Health

Clogged Atherosclerotic Arteries, Coronary Atherectomy

Unclogging Coronary Arteries: The new way

By Dr. W. Gifford Jones

December 10, 1989

Plumbing and delicate heart surgery seem to be miles apart. But the basic principles of each are similar. If there's a clogged drain in your house you quickly reach for Drano. If that fails you may insert a snake into the drain. If that proves futile you may have to replace the plumbing entirely. Regrettably, doctors have never discovered a Drano which cleans out clogged atherosclerotic coronary arteries. The only recourse has been replacement of the human plumbing by coronary by-pass surgery. Now "coronary atherectomy", once in the realm of science fiction can ream out tiny coronary vessels.

Whether it's plumbing or surgery, the right equipment is needed to do the job. In recent years tremendous advances have been made in the development of miniature surgical instruments. This has enabled doctors to perform a procedure called, "cardiac catheterization". A small, flexible, tubular instrument is gradually guided through the larger arteries in the body and finally into the coronary arteries.

Cardiologists then have several options. They can inject fluids into the coronary arteries and follow with X-rays to pinpoint narrowed or clogged areas in the vessels. Or insert optical instruments through the tube to detect atherosclerotic plaques blocking the arteries.

Until recently the newest technique for opening obstructed arteries was balloon angioplasty (balloon dilatation). A tiny balloon-tipped catheter was inserted into the artery. After inflating the balloon, the obstructing plaque was fractured and pushed against the inner wall of the artery. This often restored adequate blood supply to the heart. But since the plaque was not removed, some patients suffered a recurrence of the problem.

Coronary atherectomy hopes to overcome this problem. A cardiologist may now introduce a catheter into the artery in the groin and by careful monitoring its progress on a T.V. screen, slowly thread it towards the blockage in the heart. The atherectomy instrument, a tiny cutting blade which spins at 2,500 revolutions a minute, is then passed through the catheter. The blade gradually shaves off the obstructing plaque and collects it in a storage chamber in the instrument. Once this chamber is full the instrument is withdrawn, the atheromatous material removed and inserted again. This can be repeated several times until the artery is open and clear.

Until now this procedure has been used at only at a few university centers. Consequently only a small number of patients with coronary disease have been treated by this technique. But doctors believe this procedure shows great promise for the future. The Mayo Clinic reports it has been successful in 90 per cent of cases.

One major problem is the size of the coronary arteries. These vessels are only 2 to 3 millimeters in diameter. That's smaller than a piece of spaghetti. Furthermore the atherectomy instrument is rigid and cannot maneuver around difficult corners to penetrate the entire length of the coronary arteries.

And in spite of this fantastic 20th century voyage into the coronary vessels, patients must remember there's always a risk to any surgery, particularly those involving the heart. Surgeons equipped with all this modern technology can still encounter the same dilemmas as plumbers.

If a plumber tries to ream out a rusty, corroded pipe with too much force a major flood results when the pipe suddenly bursts. Similarly atherosclerotic disease weakens the walls of coronary arteries making them more fragile. The insertion of the catheter or the rotating blade may puncture the wall of the diseased coronary vessel. Emergency surgery will then be needed to repair the injury.

There's another point to remember. Plumbers who ream out a rusty pipe may remove the blockage but they're still left with an old corroded pipe. The same situation applies to coronary vessels. The cutting blade may scrape away a major obstruction, but leave the inner wall of the artery rougher than the wall of a normal artery. This increases the risk of blood clots forming on the irregular inner wall of the artery following atherectomy.

Cardiologists recommend an aspirin a day for patients who have undergone this procedure. Aspirin is like adding oil to the circulation. It makes the blood platelets less likely to stick together to form a clot.

Currently, to my knowledge, no university center in Canada is performing this procedure. But it's just a matter of time until more flexible and even smaller instruments are developed. For the moment however the coronary by-pass operation remains the primary procedure to circumvent blocked coronary vessels. 


W. Gifford-Jones M.D Most recent columns

W. Gifford-Jones M.D is the pen name of Dr. Ken Walker graduate of Harvard. Dr. Walker's website is: docgiff.com.
Dr. Walker can be reached at info@docgiff.com















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