Diagnosing Carotid Artery Disease
In carotid artery disease, there is a narrowing, or stenosis, of one or both of the carotid arteries, which are the two main arteries in the neck that supply blood and oxygen to the brain. This narrowing is caused by a buildup of plaque, a waxy substance made up of fat, cholesterol, and calcium in the blood. When plaque builds up in the body’s arteries, it’s called atherosclerosis, or hardening of the arteries; when it occurs in the carotid arteries, it can lead to stroke.
Some people with carotid artery disease experience no obvious symptoms, even when they have severe blockages. Such blockages may be discovered accidentally, particularly during routine imaging or screening tests for other conditions, such as diabetes and hypertension, which increase risk for heart attack or stroke.
However, some people with carotid artery disease experience a stroke or ministroke as the first sign of this condition.
A ministroke, or transient ischemic attack, is a temporary blockage or interruption of blood flow to part of the brain. It usually occurs when a small piece of plaque in the carotid artery breaks off and travels to the brain. It is considered a major warning sign of a future stroke.
The symptoms of a transient ischemic attack are similar to those of stroke, but they don’t last long or cause long-term damage to brain cells, which a stroke can. If carotid artery disease leads to a ministroke, quick treatment is warranted to prevent a stroke.
Symptoms of both stroke and ministroke include a sudden numbness, tingling, or weakness in the arm, face, or leg, particularly on one side of the body. A person may also have difficulty speaking or understanding speech. Sudden vision troubles in one or both eyes may occur, as may difficulty with walking. People having a stroke or ministroke may also experience a sudden, severe headache.
The symptoms of a ministroke typically last for one to two hours. The symptoms of a stroke last at least 24 hours, and, unfortunately, can cause permanent damage.
Both are medical emergencies. If you are experiencing symptoms of stroke or ministroke, call 911 or seek treatment at a nearby hospital immediately. Receiving treatment quickly can limit or stop potentially permanent complications, particularly after a stroke.
In diagnosing carotid artery disease, your NYU Langone doctor performs a physical examination. This includes listening to the carotid arteries with a stethoscope for signs of bruit, a “whooshing” sound caused by irregular blood flow, which can be heard when the carotid arteries are significantly blocked.
The doctor also takes a medical history to determine risk factors, including a family history of carotid artery disease and atherosclerosis.
Imaging tests may be used to further assess the carotid arteries. Among other details, these tests provide your doctor with information about the extent of a blockage.
Our doctors use noninvasive duplex ultrasound as the first and most important test to diagnose carotid artery disease. This exam provides information about the structure of the blood vessels as well as the blood flow within them.
Duplex ultrasound combines conventional and Doppler ultrasound to create a two-dimensional, black-and-white, moving image of the blood vessels that reveals any blockages caused by plaque deposits in the arteries. Doppler ultrasound involves the use of sound waves to provide information about the speed and other characteristics of blood flow within the carotid arteries.
During the ultrasound, the doctor places a handheld instrument called a transducer against the skin. It transmits sound waves that produce images of blood vessels on a monitor.
The exam can take 30 to 60 minutes and is painless. After the test, you can typically return to your regular activities immediately.
Your doctor may order this test to help identify diseased, narrowed, enlarged, and blocked carotid and vertebral arteries. These vessels carry blood to the brain from the subclavian arteries, which branch off the aorta in the chest. A CT angiogram (CTA) uses a specialized CT scan, in which X-rays are taken to gain multiple three-dimensional views of arteries in the body.
Before the scan, you are given an intravenous (IV) dose of a contrast dye through a catheter inserted in the arm. This liquid travels through the blood vessels and highlights on a computer screen any blockages in arteries leading to the brain. It doesn’t hurt, but you may feel a spreading sensation of warmth throughout your body after the contrast material is injected.
You are asked to lie on a table that slides into the CT machine. A test image of your head and upper torso is taken first. The technologist may ask that you hold your breath for 10 to 25 seconds to ensure that each subsequent image isn’t blurred due to movement. The test takes 20 to 60 minutes.
Magnetic Resonance Angiogram
Doctors may also recommend a magnetic resonance angiogram (MRA), which is a study of the blood vessels using an MRI scan. During an MRI, large magnets, radio waves, and computers create two- and three-dimensional pictures of the inside of the body.
Before the test begins, a contrast dye is injected into a vein in your arm or hand to allow the blood vessels and arteries to be clearly seen on the computer screen. You are asked to lie very still on a table that slides into the machine. The test takes 40 to 90 minutes to complete. Typically, either an MRA or CTA may be ordered, but not both.
Carotid and Cerebral Angiogram
Once more commonly used, a carotid and cerebral angiogram, which involves inserting a hollow tube called a catheter into the carotid arteries and the brain, is rarely required to diagnose carotid artery disease or to determine treatment.
In this procedure, which is performed with a local anesthetic, a catheter is inserted into the femoral artery through a small incision in the groin and advanced to the arteries of the neck and head. A dye is injected to make the arteries and any blockages visible on a computer screen. It takes 60 minutes to complete.