Science Probes Mystery of Swellings in Arteries

Cathy, an energetic young mother of two, spent the day laughing and picnicking in the mountains with her husband and friends. Nobody knew that inside her head, a blood vessel had swollen into a dangerously weak balloon.

Not until after she collapsed that evening, in the middle of a telephone conversation, did doctors detect the exploded time bomb in her head. Cathy was declared dead the next day.

“None of this made sense to me, for a 34-year-old woman, my wife, to suddenly die in the space of 24 hours before my eyes,” said her husband, George, who asked that their real names not be used.

Without Warning

Cathy had joined the tens of thousands of Americans who die without warning each year from the bursting of an aneurysm, the balloon-like swelling of an artery.

Fatal aneurysms can occur in the head and on the abdominal or chest portions of the aorta, which pumps blood from the heart to the rest of the body. Aneurysms cause most hemorrhages between the skull and brain, resulting in strokes that strike 28,000 North Americans each year, killing about 3,000 suddenly.

Aneurysms in the aorta hospitalize 130,000 people in the United States each year, killing 14,000 directly and contributing to the deaths of an additional 20,000, Dr. Thomas Robertson, cardiac disease chief at the National Heart, Blood and Lung Institute, says.

Experts say the biggest potential for saving lives is in improving detection of aneurysms in the aorta. Aneurysms in the head are difficult to detect before they burst. There are some warning signs before a rupture, but the best hope to save lives lies in diagnosing aneurysms after they burst, when a quarter are still overlooked.

For now, experts know that the risk of aneurysm is increased by smoking cigarettes or taking birth control pills.

Effects of Pressure

Arteries form the fragile aneurysm balloons when weakened portions of their walls are forced outward by pressure, especially high blood pressure. Nobody knows exactly what weakens the artery wall. Many doctors suspect hardening of the arteries. In some cases, arteries can be weakened by injury, inherited defects, infections and pressures caused by pregnancy.

Recent evidence suggests an alternative to hardening of the arteries as a cause: abnormally high levels of enzymes, which break down the connective tissue in arteries, says Dr. Ronald J. Stoney, a vascular surgeon at the University of California, San Francisco.

If true, researchers may be able to identify people at high risk by detecting those enzymes; drugs could be developed to interfere with the enzymes and prevent weakening of the artery, Stoney says.

A 1983 study at the University of Rochester, N.Y., calculates that about 3,900 lives could be saved each year in the United States if all abdominal aneurysms were detected and treated before they burst.

Diagnostic Methods

A common sign is a throbbing bulge felt below the breastbone and above the navel. The diagnosis usually can be confirmed by pictures made by ultrasound, arteriography (an X-ray taken after the aorta is injected with dye) or devices called CT scanners.

Aneurysms of the chest portion of the aorta, especially those that force layers of the artery walls to separate, often are initially confused with heart attacks because they cause severe chest pain.

Robertson says that researchers are trying to improve the ability to diagnose aortic aneurysms by developing tiny viewing scopes that could be inserted via catheter directly into the aorta.

Within the head, fewer than 10% of aneurysms are diagnosed before they burst, says Dr. John Marler, medical officer for the National Institute of Neurological and Communicative Disorders and Stroke.

Cathy’s case illustrates the problem. For two years before her death, she suffered severe headaches. Her neurologist, believing they were migraine headaches, prescribed drugs but never ordered sophisticated diagnostic tests that might have shown the truth.

“Chronic headache is not a hallmark, in general, of aneurysm,” says Dr. Steven Giannotta, a USC neurosurgeon. “There are so many people in the world who have headaches and so few who have aneurysms that a few people are going to have headaches and aneurysms, but the two aren’t necessarily related.”

“There are a few warning symptoms--very few,” says Dr. John Frazee, chief neurosurgeon at the Wadsworth Veterans Hospital in Los Angeles. Symptoms of an aneurysm about to burst may include a sudden, severe and uncharacteristic headache, abnormal eye movement, double vision or a neck so stiff the patient is unable to touch the chin to the chest.

Even after a rupture, many doctors fail to diagnose aneurysms in the head, Frazee says. Marler adds that of the 28,000 annual victims, doctors fail to diagnose the rupture in about 7,000 who survive the initial hemorrhage. The lack of proper treatment leads to severe paralysis or death days or weeks after the initial rupture, he says.

Experts say no drug can reverse the relentless expansion of an aneurysm, so surgery is almost always the treatment of choice, especially for abdominal aneurysms.

Use of Medication

The only existing drug therapy for aneurysms is medication to control high blood pressure and slow the gradual bulging of the weakened artery wall, Robertson says. But Marler says that many aneurysms burst in people with normal blood pressure, so there is debate over the effectiveness of such drugs.

The accepted surgical approach to aortic aneurysms involves grafting a tube of knitted Dacron inside the defective segment of artery. “We put a new pipe inside the old pipe and use the old pipe as a cover,” Stoney says.

Surgery is performed less often on aneurysms in the chest portion of the aorta because of the danger of straining the heart or cutting the blood supply to the spine. In any event, such aneurysms are far less likely to burst than abdominal aneurysms.

However, Dr. Richard Spears, a Harvard Medical School cardiologist, has performed experimental surgery in dogs with chest aneurysms that force the layers of the arterial wall apart. A balloon-tipped catheter is inserted into the aorta along with an optical fiber. The balloon is inflated to push the separated layers of the artery wall together, and the fiber delivers a laser beam to fuse them permanently.

Treatment in the Head

In the head, grafts of synthetic arteries are considered too risky because of the danger of cutting the blood supply to the brain. Such aneurysms, once they have burst, usually are treated by placing a clip over the swollen portion to prevent another hemorrhage.

Tiny balloons, inserted into aneurysms of the head with a catheter and then inflated, are being used experimentally in a few patients, Giannotta reports. Blood clots around the balloon, sealing off the swelling portion of the artery while leaving the main portion open. Once sealed, the aneurysm and the man-made balloon slowly dissolve while blood continues to flow normally through the artery.