Carotid sinus syndrome: a case report of an unusual presentation of cardiac arrest while diving

Background Carotid sinus syndrome (CSS) is an exaggerated response to carotid sinus baroreceptor stimulation, which may result in hypotension, prolonged asystole, and subsequently transient loss of consciousness due to cerebral hypoperfusion. However, this commonly benign syndrome may have lethal consequences under certain circumstances such as scuba diving. Case summary We report the case of a trained 73-year-old male diver, who survived an almost fatal diving accident without any neurological deficits due to cardiac arrest under water. After recovery and intensive diagnostics in the local hospital, the origin of cardiac arrest remained unclear. However, after referral to our tertiary care centre CSS could be diagnosed by provoking syncope and asystole with carotid sinus massage (CSM). Consequently, a leadless pacing system was implanted and his medical diving fitness could then be recertified. Discussion In conclusion, CSS may be an underdiagnosed cause of loss of consciousness. Thus, screening for CSS by CSM should be included in medical exams in senior athletes and specifically in senior divers.