Carotid Sinus Hypersensitivity and Syncope

Background

• Carotid sinus hypersensitivity (CSH) is an abnormal autonomic response to carotid sinus massage defined as ventricular pause > 3 seconds and/or fall in systolic blood pressure > 50 mm Hg in asymptomatic patients
• Carotid sinus syncope is a form of neurally mediated syncope (also called reflex syncope) caused by CSH or an abnormal autonomic response to carotid stimulation.
• Neurally mediated syncope (also called reflex syncope):
  • includes vasovagal syncope (most common), carotid sinus syncope, and situational syncope
  • refers to a group of heterogeneous conditions characterized by intermittent inappropriate cardiovascular reflexes (usually in response to a trigger) that cause a drop in arterial blood pressure, heart rate, and global cerebral perfusion

Evaluation

• Suspect carotid sinus syncope in patients with syncope triggered by:
  • turning of neck
  • wearing a tight necktie or tight collar
  • shaving the neck
  • neck tumors
  • pressure on neck
  • mechanical manipulation of carotid sinuses (rare)
• Use carotid sinus massage for patients > 40 years old suspected of having carotid sinus if underlying cardiovascular disease is ruled out with electrocardiogram (ECG) and the etiology of the syncope is unclear (Strong recommendation).
  • It is diagnostic of carotid sinus syncope if the syncope is reproduced and accompanied by asystole for > 3 seconds or a fall in systolic blood pressure that is > 50 mm Hg.
• Consider tilt table testing for unexplained recurrent falls or to differentiate between neurally mediated syncope and orthostatic hypotension syncope (Weak recommendation).

Management

• Educate the patient about avoiding possible triggers (Strong recommendation).
• Avoid agents that lower blood pressure, such as beta blockers, diuretics, and alcohol.
• Explain risk of recurrence and reassure patient that this condition is benign (Strong recommendation).
• Consider cardiac pacing in patients with (Weak recommendation):
  • carotid sinus syndrome that is cardioinhibitory or mixed
  • tilt-induced asystolic response if aged > 40 years old and recurrent frequent unpredictable syncope
• Permanent pacing is not indicated in patients without documented cardioinhibitory reflex (Strong recommendation)