Carotid sinus hypersensitivity

Carotid Sinus Hypersensitivity (CSH), also known as carotid sinus syndrome or carotid sinus syncope, is a condition characterized by an exaggerated response to pressure on the carotid sinus, resulting in decreased heart rate (bradycardia), low blood pressure (hypotension), and sometimes syncope (fainting). The carotid sinus is a region of the carotid artery that helps regulate blood pressure. CSH is more common in older adults and can lead to significant morbidity due to falls and associated injuries.

Causes and Pathophysiology

CSH is caused by an abnormal reflex in the carotid sinus. The carotid sinus contains baroreceptors that sense blood pressure and help regulate it by sending signals to the brain. In CSH, these receptors are overly sensitive, and slight pressure or manipulation can trigger a significant drop in blood pressure and heart rate. This condition can be idiopathic or associated with underlying conditions such as atherosclerosis or neck tumors.

Classification

CSH is classified into two types based on the response to carotid sinus massage (CSM):

• Cardioinhibitory type: Characterized by a significant decrease in heart rate.
• Vasodepressor type: Characterized by a significant drop in blood pressure without a significant change in heart rate.
• Mixed type: Exhibits features of both cardioinhibitory and vasodepressor types.

Symptoms

Symptoms of CSH may include:

• Dizziness or lightheadedness
• Fainting or near-fainting episodes
• Blurred vision
• Weakness
• Palpitations
• Confusion or memory problems, especially in older adults

Diagnosis

Diagnosis of CSH involves a detailed medical history, physical examination, and specific tests:

• Carotid sinus massage (CSM): Performed under controlled conditions, CSM can provoke symptoms and diagnose CSH. Heart rate and blood pressure are closely monitored during the procedure.
• Electrocardiogram (ECG): To assess heart rhythm.
• Tilt table test: May be used if CSM is inconclusive.

Treatment

Treatment of CSH focuses on preventing symptoms and may include:

• Avoiding triggers, such as tight collars.
• Medication adjustments, especially if medications contribute to hypotension.
• Pacemaker implantation for those with the cardioinhibitory type.
• Education on counter-pressure maneuvers to prevent or mitigate fainting spells.

Prognosis

With appropriate management, individuals with CSH can have a good prognosis, though the risk of falls and associated complications remains a concern, particularly in the elderly.

Prevention

Preventive measures for CSH primarily involve lifestyle modifications and managing underlying conditions that may contribute to the syndrome.