April 1, 2006 — A new "wingspan" stent helps restore blood flow for patients with intracranial atherosclerotic disease, or ICAD. Surgeons insert the stent up the leg arteries, guide it to the brain, then let its wire mesh expand, propping open a clogged blood vessel. The new stent, designed for the fragile, curvy arteries in the brain, replaces stiffer stents used in heart and neck vessels.
When a stroke hits, it hits the brain hard -- many times causing paralysis, speech problems, or even death. Now, doctors have a new weapon against this deadly brain attacker.
John Dietz is happy to be back on his feet after a surprise stroke left him almost speechless. "I have trouble getting the words out. I know the words in my brain, but I can't get them out."
The artery in John's brain that caused the stroke was almost completely blocked. Now, to save his life a new tiny, flexible stent to open clogged arteries and prevent another stroke from happening is in his brain.
Traditional stiff stents are used to treat blockages in the heart and neck. The new wingspan stent, however, is designed for the fragile, curvy arteries in the brain.
Abraham Obuchowski, an interventional neuroradiologist at the University of Maryland Medical Center in Baltimore, says, "The stent is more flexible so it can make the turns to get up into the brain."
Neuroradiologists guide the wire-mesh stent with a catheter up the artery in the leg leading to the brain. Then a protective covering is removed and the self-expanding stent props open the clogged artery. "You can actually take it and squeeze it and crush it, and it will pop back into position. So that's what's unique about this stent," Dr. Obuchowski says.
John is hopeful this unique device will help him have a stroke-free future.
The new wingspan stent system is designed for patients with intracranial atherosclerotic disease, or ICAD. Until now, the only treatment option for these patients was medication therapy like aspirin or using a heart stent in the brain.
BACKGROUND: A new medical device can open clogged arteries in the brain, helping prevent strokes. Called the Wingspan Stent System, it is specifically designed to treat blockages caused by intracranial athlerosclerotic disease, a condition that causes strokes. While it won't address risk factors such as high blood pressure or high cholesterol, the device will significantly decrease a patient's risk of stroke.
WHAT ARE STENTS? A stent is essentially a small piece of metal "scaffolding" that pushes arterial plaque to the side and provides a framework to keep the blood vessel open so that the blood can flow freely through it. Stents have been used for many years to clear blockages in the arteries of the heart and neck. But arteries in the brain are fragile, with many more curves, so it is much harder to get the stent to the blockage site. Steel stents can injure those vessels. The Wingspan stent is made of an alloy of nickel and titanium, which puts less pressure on the blood vessel when it expands.
HOW IT WORKS: Neuroradiologists insert a catheter into an artery in the upper leg. Using digital X-rays for image guidance, they then navigate the catheter through the blood vessels to the site of the blockage in the brain. They then slowly inflate an angioplasty balloon to push away the plaque and put the stent in place to hold the vessel open.
ABOUT STROKES: The brain is made up of living cells that require a constant supply of nutrient- and oxygen-rich blood. Blockage or rupture of the blood vessels supply parts of the brain cause most strokes. A stroke occurs when brain tissue is deprived of blood and brain cells die from the lack of oxygen. Depending on which area of the brain is affected, a stroke can cause vision problems, speech problems, disability, even death. Traditionally, treatment for stroke-causing diseases involves blood-thinning drugs to prevent clots, but for patients with severe blockage, this may not be sufficient. Some temporary blockages only last minutes or hours, leading to mini-strokes. Mini-strokes are a sign of a serious problem and can lead to a permanent stroke if left untreated.
ABOUT BLOOD FLOW: The heart pumps blood through the arteries, capillaries and veins to provide oxygen and nutrients to every cell of the body, and also carries away waste products from those cells. The liquid portion of the blood is called plasma. It distributes various nutrients and chemicals throughout the body, diffusing into the tissues and cells. In general, they diffuse from areas of high concentration to areas of low concentration. Waste flows in the opposite direction and are removed in the kidneys or the lungs. Blood pressure pushes fluid out of blood vessels. This is balanced by something called oncotic pressure, which keeps fluid inside the blood vessels so that the body maintains a constant volume of blood.
Note: This story and accompanying video were originally produced for the American Institute of Physics series Discoveries and Breakthroughs in Science by Ivanhoe Broadcast News and are protected by copyright law. All rights reserved.
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