Mar 22 2006
Neurosurgeons at Thomas Jefferson University Hospital in Philadelphia are the first in the region and among the first in the nation to successfully use a new stent specifically designed to open potentially life-threatening clogged arteries in the brain, preventing a stroke.
The device, called the Wingspan Stent System, is used for individuals with intracranial atherosclerotic disease, which results from too much plaque in brain arteries. The condition accounts for about eight to 10 percent of strokes due to ischemia, or some 60,000 strokes in Americans each year.
Traditional medical management for such blockages using blood thinners such as Coumadin and aspirin is frequently ineffective. Doctors have tried using heart stents - the mesh metal tubes placed in a coronary artery to keep it open after an interventional procedure - but they are stiff and not meant for the more fragile blood vessels in the brain.
The Wingspan Stent is self-expanding and is placed using minimally invasive techniques. It is threaded through an artery in the leg. "It's the first self-expanding stent for intracranial use designed specifically for atherosclerotic disease in the brain," says Robert Rosenwasser, M.D., chair of neurosurgery at Thomas Jefferson University Hospital.
Dr. Rosenwasser, who is a professor at Jefferson Medical College of Thomas Jefferson University continued, "With stent technology and the proper tools, we should be able to lower the risks of treating the disease because these devices are designed specifically for cerebral blood vessels."
Instead of steel, the most commonly used material for traditional coronary stents, the Wingspan stent is composed of nitinol, an alloy of nickel and titanium. This design puts less pressure on the blood vessel when it expands.
Previously, patients had few options. "Up until recently all we could do was offer anticoagulants such as Coumadin, Plavix and aspirin to avoid a stroke," explained Erol Veznedaroglu, M.D., assistant professor of neurosurgery at Jefferson Medical College of Thomas Jefferson University.
"These patients either responded to medical therapy or were given devices that were less than ideal," Dr. Rosenwasser says. But blood-thinning drugs fail to open blockages in brain arteries in 30 percent of cases, putting patients at high risk for stroke. And even many of those who initially respond to such medications often go on to have another stroke in the next year.
Stroke is the third leading cause of death and disability in the United States, according to Dr. Rosenwasser. He notes that some 80 percent of strokes are due to brain injuries caused by a lack of oxygen, such as those from the buildup of plaque in blood vessels. Only 20 percent are due to hemorrhage.
Dr. Rosenwasser, who is also director of the Division of Cerebrovascular Neurosurgery and Neuroradiology at Jefferson Medical College and Thomas Jefferson University Hospital, pointed out that using other means, such as balloon angioplasty, to push aside plaque, has high complication rates, about 18 to 20 percent.
"What's so exciting here is that we'll begin seeing a host of patients who were never able to be treated before," says Dr. Veznedaroglu. "This is really a revolution for the treatment of this disease and we expect the Wingspan stent to be used frequently."
"The device will allow us to treat more patients up front before they exhaust medical therapy," says Dr. Rosenwasser.
Doctors don't know yet if the stent can be used preventatively. Dr. Veznedaroglu thinks it can. "With a safe stent, I think you'll see eventually that it is better than the best medical management," he says. "But it's just too soon to know. We'll need long-term studies to find out."
The Wingspan stent is not a panacea. Atherosclerotic disease and plaque buildup (as coronary artery disease) can return, he notes, despite a stent. Stents do not stop what causes the clogging to occur, so they will not prevent the disease. Scar tissue is also a problem, just as it is with coronary disease. Early experience, however, indicates that cranial vessels may not develop as much plaque as do arteries around the heart.
The procedure is performed similarly to coronary artery stent placement or placing a coil for an aneurysm. The surgeon snakes a catheter through the femoral artery and into the blood vessel in question. With the aid of X-rays, the surgeon navigates the stent device into the cerebral circulation to the precise location of the narrowing and blockage.
The stent is self-expanding, meaning a balloon is not required to open it (as it is in coronary artery stents). It essentially opens automatically when it comes out of the catheter. The catheter is inserted through the blockage, and a balloon is inflated with low pressure to slowly open the clog. The balloon and catheter are removed, and the stent is released from a second catheter.
The procedure can last from 30 minutes to two hours, depending on the complexity of the case. Patients may leave the hospital as soon as 48 hours later. Recovery time will be dictated by the patient's neurological condition. Ideally, a patient could return to work in a week.
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