Finding Strokes and Aneurysms Before They Occur

For years, surgeon Dr. K. Craig Kent has asserted that vascular screening, a 30-minute, $110 series of ultrasonic exams to identify potential aneurysms and strokes before they occur, should be part of an annual physical. "Strokes and aneurysms generally don't happen without warning," says Dr. Kent. "The weakening of an artery that can lead to an aneurysm develops over time, so does the plaque that can eventually block arteries in the neck and trigger a stroke."

	Dr. K. Craig Kent examines a patient's aorta.

Dr. Kent has insisted that screening patients at risk is actually cost effective, and this past January the federal government agreed. When the Medicare Act takes effect in January 2007, one of its provisions will make vascular screening for aneurysm disease covered by insurance. The provision covers males over the age of 65 that are current or former smokers as well as individuals with a family history of aneurysm disease. There are others including some groups of women that should still have the exam as an "out of pocket" expense. "In time, we hope coverage can be expanded to other groups and risks, and that improvements in technology can make the cost even less for 'out of pocket' patients," says Dr. Kent.

Being screened is actually a fascinating experience. During part of the exam, your beating heart appears on a bedside monitor, and it is hard not to feel both mortal and lucky to be alive simultaneously. Here is how the screening works.

	An ultrasonic image of blood flowing through an artery.

Part One: Aortic Aneurysm Detection
An ultrasonic wand, like the wand that is used to monitor a developing fetus, is slid along the patient's torso, above where the aorta lies. The aorta is a major artery that runs from the heart to the abdomen. It is where an aneurysm is most likely to occur and can be deadly if it does.

As a technician moves the wand, an ultrasonic image of the aorta appears on a nearby monitor. Depending on the position of the wand, the aorta can be viewed from several different angles: lengthwise, and also straight on, as if looking through a tube. From this "straight on" view, the aorta's diameter is measured. Any spot found to be greater than 3 cm in diameter is considered an aneurysm and would require additional investigation.

Part Two: Carotid Artery Disease Detection
In the second part of the screening, the wand is run along the carotid arteries. The carotid arteries run along both sides of the neck and are where dangerous plaque buildup is likely to occur. A blockage or a situation where plaque breaks loose and lodges "upstream" can trigger a stroke.

Along with a visual inspection of the carotid's ultrasonic images, the technician will measure the speed at which blood flows through them. If blood flows through the carotid arteries at greater than 125 cm/second, the artery has grown too narrow and is in need of monitoring or repair.

Part Three: Lower Extremity Artery Disease Detection
The final part of the screening uses Doppler technology to compare blood pressure from a reading in the arm to blood pressure from a reading in the ankle. Blood pressure in the ankle is expected to be slightly higher (gravity being the cause), but a difference beyond .95 signals a blockage of blood flow to the lower extremities and would warrant further investigation.

Dr. K. Craig Kent is chief of vascular surgery at NewYork-Presbyterian Hospital and professor of surgery at Weill Cornell Medical College and Columbia College of Physicians and Surgeons.