Carotid sinus hypersensitivity is a condition brought on by rapid changes in blood pressure, potentially causing dizziness or fainting during everyday activities. The condition can sometimes go undiagnosed because other common conditions also cause dizziness and fainting.

What You Need to Know

• Carotid sinus hypersensitivity is rarely diagnosed before age 50 and is more common in men than women. Men with heart conditions such as hypertension, hypercholesterolemia, coronary artery disease and diabetes are especially at risk.
• Carotid sinus hypersensitivity cannot be reversed. Treatments include implantation of a pacemaker, and medications to balance sodium and fluid levels in the body and to treat low blood pressure.
• Lifestyle changes can also reduce occurrences of rapid change in blood flow that trigger symptoms.

What is carotid sinus hypersensitivity?

The carotid arteries are the main blood vessels that carry blood and oxygen to the brain. When pressure is applied to the carotid sinus (located in the neck just below the jaw, where the carotid arteries enter the head), people with carotid hypersensitivity experience reduced heart rate, enlarged blood vessels and a drop in blood pressure, causing dizziness or syncope (fainting). Carotid hypersensitivity can be triggered by many common activities such as standing, turning the head, shaving or driving.

What causes carotid hypersensitivity?

The carotid sinus has key receptors that connect the nervous system to the vascular system. Carotid sinus hypersensitivity makes these receptors overreact to changes in pressure caused by common movements and actions. The receptors then send signals to the medulla, a section of the brain stem that regulates parasympathetic functions in the body including heart rate, blood pressure, breathing and circulation, triggering hypotension (a drop in blood pressure), bradycardia (reduced heart rate) and vasodilation (enlarged blood vessels). Together, these rapid changes in blood flow can cause dizziness and fainting. What is usually a normal compensatory mechanism is instead an exaggerated response, sometimes making the patients dizzy or even causing them to faint.

What are the types of carotid hypersensitivity?

• Cardioinhibitory: carotid hypersensitivity triggers the heart to stop for three seconds or more
• Vasopressor: carotid hypersensitivity triggers a decrease in blood pressure of 50 millimeters of mercury or more
• Mixed: both cardioinhibitory and vasopressor carotid hypersensitivity are present

Symptoms of Carotid Sinus Hypersensitivity

Carotid hypersensitivity shares symptoms with many heart conditions and can be difficult to diagnose. Key symptoms of carotid hypersensitivity include:

• Presyncope or syncope (fainting caused by carotid hypersensitivity is called carotid sinus syncope)
• Falling without an obvious cause
• Darkening vision before fainting
• Pale skin
• Hypotension
• Bradycardia (slowed heart rate)
• Bruises from falls

Who is at risk of carotid sinus hypersensitivity?

The risk of carotid sinus hypersensitivity increases with age, and the condition is rare before age 50. Carotid hypersensitivity is more common in men than in women, and it often affects men who have chronic heart conditions such as:

• Hypertension
• Coronary artery disease
• Diabetes
• Valvular pathologies

Carotid hypersensitivity also sometimes occurs in people with neurological conditions such as Alzheimer’s disease and Lewy body dementia.

How is carotid sinus hypersensitivity diagnosed?

Carotid hypersensitivity can sometimes go undiagnosed because other common conditions also cause dizziness and fainting. To rule out other possibilities, the patient’s conditions and family medical history are reviewed. Depending on the patient, the following tests may also be performed:

• Electrocardiogram (ECG or EKG)
• Echocardiogram
• Electroencephalogram (EEG)
• Computed tomography (CT) scan

A heart monitor (an event monitor or an implanted loop monitor) may also be used to review heart activity over a longer period of time for any irregularities.

Once other causes have been ruled out, carotid hypersensitivity may be diagnosed with monitored carotid massage. Because this test may trigger fainting or a cardiac event, it is only performed in a controlled environment, where the patient can be quickly treated if either occur. Usually, the patient will lie down and a doctor will apply pressure with their fingers to the exterior of the carotid sinus on the right side of the neck, moving in a circular motion for five to 10 seconds, before switching sides if there is no response. If the patient’s heart stops for more than three seconds or if there is significant drop in measured blood pressure, or if both occur, the test is considered positive, even if dizziness or fainting do not happen. If a heart attack occurs, emergency equipment and staff will immediately provide help.

How is carotid sinus hypersensitivity treated?

Carotid hypersensitivity cannot be reversed, but once diagnosed, patients are advised to avoid actions such as the following that can trigger an event:

• Wearing clothes with tight collars
• Getting massages or chiropractic techniques around the neck
• Any action that might result in pressure on the carotid sinus (upper neck)

The subtype of carotid hypersensitivity diagnosed determines the treatment:

• Cardioinhibitory carotid hypersensitivity requires a pacemaker to regulate the speed and rhythm of heartbeats.
• Vasopressor carotid hypersensitivity can usually be treated by maintaining proper hydration and salt intake. If symptoms continue, medication may be prescribed to help balance sodium and fluid levels in the body and to treat low blood pressure.
• Mixed carotid hypersensitivity generally requires an implanted pacemaker, but the risk of dizziness or fainting is still possible if sodium, fluid levels and blood pressure are not managed.

Living With Carotid Sinus Hypersensitivity

Carotid hypersensitivity can be a serious condition, but it can be managed with treatment and lifestyle changes. Avoiding constricting the neck with tight clothing and activities that require sudden neck movements or pressure on the neck, and staying properly hydrated, can help prevent episodes in many cases. Patients with cardioinhibitory or mixed carotid hypersensitivity who receive a pacemaker should take the standard precautions. Having documentation of the condition with you may be helpful for emergency situations.