Sympathoinhibition and hypotension in carotid sinus hypersensitivity

Michael L. Smith, Kenneth A. Ellenbogen, Dwain L. Eckberg

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15 Scopus citations


Carotid sinus reflex hypersensitivity is a known cause of syncope in humans. The condition is characterized by cardioinhibition and vasodepression, each to varying degrees. The extent and importance of sympathoinhibition has not been determined in patients with carotid sinus hypersensitivity. This study reports on the extent of sympathoinhibition measured directly during carotid massage with and without atrioventricular sequential pacing, in a patient with symptomatic carotid sinus reflex hypersensitivity. Carotid massage elicited asystole, hypotension and complete inhibition of muscle sympathetic nerve activity. Carotid massage during atrioventricular pacing produced similar sympathoinhibition, but with minimal hypotension. Therefore, sympathoinhibition did not contribute importantly to the hypotension during carotid massage in the supine position in this patient. Further investigations are required to elucidate the relation of sympathoinhibition to hypotension in patients with carotid sinus hypersensitivity in the upright position.

Original languageEnglish
Pages (from-to)389-392
Number of pages4
JournalClinical Autonomic Research
Issue number6
StatePublished - Dec 1992


  • Asystole
  • Carotid baroreflex
  • Sympathetic nervous system
  • Syncope


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