Carotid Sinus Syndrome

Carotid sinus syndrome is carotid sinus hypersensitivity that causes recurrent syncope or falls, with symptoms reproduced by carotid sinus massage. It is a recognised cause of unexplained syncope in older men.

It accounts for a notable proportion of syncope in older people and increases with age. It is more frequent in men and in those with coronary or cerebrovascular disease.

Pathophysiology. Mechanical stimulation of the carotid baroreceptors in the carotid sinus produces exaggerated vagal bradycardia, vasodilatation or both. Sleeping, neck turning, shaving or tight clothing can trigger it, though most episodes occur without an obvious trigger.

Sudden syncope or drop attacks with little warning, often a short loss of consciousness, quick recovery and amnesia for the event. Injuries and fractures are common. Presyncope, dizziness and falls without remembered loss of consciousness are frequent.

Red flags.

• Syncope on exertion or with chest pain.
• Syncope with a family history of sudden death.
• Murmur, heart failure or an abnormal ECG.

Diagnosis needs unexplained syncope or falls, reproduction of symptoms with carotid sinus massage (5 to 10 seconds, supine and head up, with asystole of 3 seconds or more or a fall in systolic pressure of 50 mmHg or more), and no other cause after assessment. Prolonged ECG monitoring or an implantable loop recorder may be used when the diagnosis is unclear.

Differential diagnosis.

• Sick sinus syndrome, atrioventricular block and ventricular arrhythmia.
• Aortic stenosis and hypertrophic cardiomyopathy.
• Orthostatic hypotension and drug effects.
• Epilepsy and vertebrobasilar insufficiency.

Offer a dual chamber pacemaker for cardioinhibitory or mixed syndrome, which cuts syncope recurrence substantially. Review and withdraw bradycardic and hypotensive drugs. Advise avoiding tight collars and sudden neck movements. For purely vasodepressor syndrome, treatment is limited to fluids, support stockings and, in some patients, midodrine.

Special groups. Apply local driving restrictions for patients with syncope until treated.

Monitoring. Symptom recurrence and device review.