What is the Carotid Sinus?

Katriena Knights

The carotid sinus is a slightly enlarged area in the carotid artery where it divides into the internal and external carotids. Within it are sensitive areas called baroreceptors. These baroreceptors respond to pressure and when stimulated can cause reduced blood pressure, vasodilation, and can slow the heartbeat.

If blood pressure increases, the pressure in the sinus also increases and the baroreceptors respond by dilating blood vessels.
If blood pressure increases, the pressure in the sinus also increases and the baroreceptors respond by dilating blood vessels.

Often called the common carotid, the carotid artery is the major artery that provides blood and oxygen to the head and neck. There are two carotid arteries, one on each side of the body. Both split into internal and external carotid arteries, creating a carotid artery sinus where the division occurs.

The carotid artery, which is located in the neck, supplies the brain with oxygenated blood.
The carotid artery, which is located in the neck, supplies the brain with oxygenated blood.

Within the carotid sinus, the baroreceptors work to help the body respond to changes in pressure within the arteries. If blood pressure increases, the pressure in the sinus also increases and the baroreceptors respond by dilating blood vessels through a process called vasodilation. Widening the blood vessels leads to a decrease in blood pressure. Under normal conditions, this process helps maintain blood pressure at a proper level.

When stimulated, the baroreceptors of the carotid sinus can lower blood pressure.
When stimulated, the baroreceptors of the carotid sinus can lower blood pressure.

In some people, a malfunction occurs in this area called carotid sinus syndrome or carotid sinus hypersensitivity. In this condition, the baroreceptors become oversensitive to pressure, creating an overreaction in the carotid sinus reflex. In some cases, even mild pressure on the neck such as turning the head or wearing a shirt with a tight collar can trigger symptoms. The pressure on the neck leads to rapid decline in blood pressure, dizziness, and even fainting as the baroreceptors cause blood pressure to decrease, leading to reduced blood flow to the brain. This condition rarely occurs in individuals younger than 50, and is more common in males than in females.

The carotid arteries split into internal and external carotid arteries, creating a carotid artery sinus where the division occurs.
The carotid arteries split into internal and external carotid arteries, creating a carotid artery sinus where the division occurs.

Carotid sinus syndrome can be diagnosed with carotid sinus massage. This process is where this part of the artery is manually stimulated under controlled, highly monitored conditions. By observing and recording how the blood pressure of a patient and other symptoms change during stimulation, doctors can determine the seriousness of the condition. Carotid sinus hypersensitivity is caused by a physical irregularity in the structure of the sinus, but doctors have not yet determined exactly how and where this malformation occurs.

Some people have a high sensitivity to neck pressure.
Some people have a high sensitivity to neck pressure.

Treatment for this condition varies. Some cases are treated by simply avoiding pressure on the front of the neck, while others require dietary modification such as avoiding caffeine and other stimulants. Medications might help mitigate the condition. Particularly severe cases could require a pacemaker.

Treatment for carotid sinus syndrome may involve avoiding caffeinated drinks.
Treatment for carotid sinus syndrome may involve avoiding caffeinated drinks.
An artery transports oxygen-rich blood to various parts of the body.
An artery transports oxygen-rich blood to various parts of the body.
An overreaction in the carotid sinus reflex may cause dizziness or fainting.
An overreaction in the carotid sinus reflex may cause dizziness or fainting.

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Discussion Comments

anon343204

Can playing around with your carotids (like for the fun of the feeling) lead to carotid sinus sensitivity?

seag47

@OeKc05 - I underwent testing also, and I must say, that carotid sinus massage is quite relaxing! The doctor told me to lie down and extend my neck fully. He then asked me to turn my head away from the side that he was about to massage. At first, he gently touched the area, but since that did not elicit a response, he began massaging it in a circular motion. I nearly fell asleep! He repeated the massage on the other side and nothing happened, so he set me up with a blood test. It turns out I’m actually anemic, and that’s the reason for my dizziness.

OeKc05

I got tested for carotid sinus sensitivity a year ago. The doctor put me in a relaxing, silent, warm room and attached blood pressure monitors to me. After a short time of rest, she gently applied pressure to my right carotid sinus. She found no response, but then she tested my left carotid sinus and my blood pressure dropped significantly.

At the time, I was taking Diltiazem to lower my blood pressure. I did not know this, but Diltiazem and other Beta-blockers can heighten carotid sinus sensitivity. The doctor informed me of this, but she did not think it wise for me to stop taking my blood pressure medication, so she just lowered the dosage.

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