Reported April 2006

BACKGROUND: A new medical device can open clogged arteries in the brain, helping prevent strokes. The Wingspan Stent System 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 a small piece of metal scaffolding that pushes arterial plaque to the side and provides a framework to keep the blood vessel open so 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, making it 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. Finally, they 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 that 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 and 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 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 the body can maintain a constant volume of blood.

If you would like more information, please contact:

Dr. Abraham Obuchowski
University of Maryland Medical Center
Baltimore, MD
410-328-UMMS (8667)

FACTOID...

The human body contains about 5 liters (5.3 quarts) of blood and makes up about 7 percent to 8 percent of a person's body weight.