THE most common cause of stroke is the total blockage of a carotid artery.

We have two carotid arteries, one on each side of the neck, that transport oxygenated blood from the heart to the brain.

When you put your fingers on one side of your neck by the jaw and feel a beating, thumping sensation, that is the carotid artery pulsating.

How large are the carotid arteries?

The carotid artery, on average, is about 8 to 10 millimeters in diameter (about the size of the little finger of an average adult).

It is about 4 to 5 inches in length outside of the skull, under the skin and neck muscles, from the collar bone to the base of the jaw below the ear.

What veins are “paired” with the carotid arteries?

Arteries have “partner” veins.

In the case of the carotid arteries, the counterpart veins are the jugular veins, one on each side of the neck.

The carotid arteries bring blood from the heart to the brain, the jugular veins transport “used” blood from the brain back to the lungs for oxygenation and to the heart for recirculation.

Do the carotid arteries get blocked also?

Yes, the carotid arteries, like any artery in the body, are not immune to hardening (arteriosclerosis) of the arteries.

Hardening of the carotid arteries could lead to severe narrowing of the caliber of artery, and a blood clot in the circulation of individuals with thickened blood could completely plug the already tight channel and instantly cause a stroke.

This condition (occlusion of the carotid artery) is the most common cause of stroke in the world.

The stroke could be transient and mild, from which the person recovers after a few minutes or a day or so, or it could be severe, where the face, arm and leg paralysis are permanent.

How do hardening of the arteries develop?

There are various risk factors, like smoking, high blood pressure, lack of physical exercise, overweight condition, eating high cholesterol diet (red meats, like pork and beef), stress and anxiety, heredity, and diabetes.

These risk factors lead to a hypercoagulable state (thickening of the blood), making the person very prone to blood clot formation.

As the thickened blood passes through the arteries, it “paints” or “coats” the inner tubing wall of the arteries.

If the blood is thickened, one could imagine how this “coats” the inner wall.

As years go by, this constant “painting or coating” of the wall builds up, like junk in the sink plumbing, making the caliber or diameter of the artery smaller and tighter, leading to blockage in the circulation to the part of the body involved.

In the case of the carotid artery, the brain suffers, leading to a stroke.

What happens next?

The hardening of the arteries starts with the abnormally thick blood coating the inner wall of the arteries as blood circulates through them.

The thickened blood “painted” against the wall builds up, and gradually transforms to jelly-like consistency, becomes harder, then becomes like a scar, and eventually becomes as hard as our teeth or bones (calcification).

This is evolution of arteriosclerosis, which is actually a more complex process.

How does blockage of the carotid arteries cause stroke?

Like blockages in any other arteries, obstruction in the carotid arteries cuts off or severely reduces the blood that goes to that part of the brain.

The brain is very sensitive to lack of oxygen (which is being carried by blood) and when the amount of blood to the brain is significantly reduced (usually when the artery is blocked more than 50 percent), oxygen deficit occurs (called cerebral ischemia) and stroke develops.

How can one detect blockage of the carotid arteries?

A physical examination by a physician who listens to the carotid artery (in the neck) with a stethoscope will reveal an abnormal hissing sound (carotid bruit), which denotes reduction in the caliber of the artery and blood is going through a tight portion of the artery.

It is like pinching a hose while air or water is going through it, a similar high-pitched hissing sound is heard.

When carotid bruit is heard, what is the next test needed?

A Doppler Ultrasound of the carotid arteries, a non-invasive and painless test, can detect, with about 80 percent to 90 percent accuracy, if a significant blockage is present in the carotid artery.

If there is any doubt, a carotid angiogram is performed.

What test confirms blockage in the artery?

The final test, the “Supreme Court” if you will, among all these tests, is the angiogram or arteriogram.

It is a dye test that will give the final verdict as to the presence or absence of a blockage, its location, the degree of obstruction, the extent of the blockage, and if other arteries are involved.

Dye is injected into the carotid artery through a tiny “spaghetti” catheter that is passed into the groin artery and advanced into the upper chest segment of the main artery (Aorta), where the carotid arteries attached to, and dye is injected.

This is followed by a rapid multiple, serial, X-ray filming, recording the flow of the dye inside the artery.

This test is safe and most helpful in making the diagnosis and the choice of treatment.


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