Science / Medicine : Non-Surgical Treatment of Clogged Arteries Makes Headway : Health: Lasers, clot-dissolving drugs and angioplasty are all being tested. The drug approach appears to be the most striking advance.
In the 1950s and 1960s, surgeons devised operations that revolutionized the treatment of peripheral vascular disease, a condition in which the arteries in the pelvis and legs are narrowed by a buildup of cholesterol and calcium clots in the vessel.
The new advance was to install artificial blood vessels made of Dacron or to use one of the patient’s veins to bypass the clots. These procedures prevented amputations and improved the lives of thousands of patients. Since that time surgery has been the treatment of choice for such cases.
Several hundred thousand surgeries for peripheral vascular disease are done annually.
Today, a new revolution is under way to find the best way to overcome these sometimes life-threatening blockages without surgery. Three different methods are now being tested: lasers, clot-dissolving drugs and angioplasty, a technique consisting of threading a balloon into the vessel to stretch it open.
While the winner has not yet been determined to everyone’s satisfaction, it appears that the drug approach--sometimes together with angioplasty--is making the most striking headway. Thrombolytic therapy, as clot-dissolving with drugs is called, makes surgery unnecessary in a significant percentage of cases. It also sharply reduces the need for amputation.
“With clot lysis (dissolving), all we are doing is accelerating the body’s normal physiological process of clearing clots,” said Dr. Thomas O. McNamara, chief of cardiovascular radiology at UCLA Medical School and a pioneer in using this method. “This natural mechanism is overwhelmed in these patients by whatever it is that causes them to have clots in the first place. The drugs we use accelerate the normal mechanism sufficiently to overcome the forces promoting clot formation so that we can dissolve the existing clot.”
Drugs that dissolve blood clots have been available for many years, but were not used successfully against clots in the body’s extremities until recently. Now researchers have developed procedures that are being applied in selected cases at centers from coast to coast.
Some of the centers involved are Loyola University Medical School in Chicago, the University of Utah, the University of Texas at San Antonio and St. Vincent’s Hospital in Indianapolis. Faculty members from these and other institutions met recently at UCLA to teach their techniques.
The typical patient is over the age of 50, a smoker, has a high cholesterol level and may have high blood pressure, diabetes or high blood sugar. Typically, deposits of cholesterol and calcium have accumulated slowly in one or more vessels, gradually narrowing them.
The early symptoms include pain in the hips, thighs, calves or feet, depending on which vessel or vessels are involved. At a certain stage, the flow of blood can slow to the point that a clot forms and the circulation to the tissues downstream is blocked completely.
Until recently such an event could call for immediate emergency surgery. Failure to act quickly could result in death or an amputation. But emergency surgical treatment, according to McNamara, results in a 10% to 30% mortality rate. Additionally, 10% to 30% of those who survive lose a leg to amputation.
“In contrast,” he said, “drug therapy restores blood flow with only a 1.3% mortality rate and the amputation rate is virtually cut in half.” The results cited by McNamara are based on about 1,000 cases nationally.
The physician first threads a guide wire into the vessel while observing its passage by means of a fluoroscope. When the wire reaches the blockage, it is pushed gently into the clot.
The resistance by the clot is one criterion the doctor uses to determine whether it is suitable for dissolution with drugs. If the clot is soft, the wire is used to make a passage through the clot and the drug, urokinase, is continuously deposited along this channel for several hours to dissolve the clot and clear the blockage.
To be a candidate for thrombolytic therapy a patient first undergoes a series of tests to determine the clot’s precise location as well as other factors that may rule him or her out as a candidate. No treatment can cure peripheral vascular disease, McNamara said.
But his studies and others show that thrombolysis will make surgery unnecessary in about half of the acute cases in which operations are now performed. In some patients, the drug treatment must be repeated periodically. Some patients eventually may even require surgery. But, the physician said, the new treatment provides an option previously not available.
In the past it was believed that the clot-dissolving drugs worked only on clots formed within the previous few days. But Dr. Amir Motarjeme, director of the Illinois Vascular Institute at Good Samaritan Hospital in Downers Grove, Ill., has found that thrombolytic therapy is able to get rid of longstanding clots completely or partially in 80% of properly selected patients. Motarjeme said that clots known to be up to 5 years old have been treated successfully.
