Reflex syncope

Reflex syncope, also called neurally mediated syncope, accounts for 56–73% of the aetiologies of syncope, with a balanced incidence over the various age categories. The most common form is ‘vasovagal syncope’ where the trigger is pain, fever, instrumentation, emotion, or orthostatic stress; ‘situational syncope’ refers to syncope triggered by a specific situation, that is, micturition, defecation, swallowing, cough; and ‘carotid sinus syncope’, which may be triggered by carotid sinus manipulation or diagnosed in patients with syncope and positive carotid sinus massage. The term ‘atypical reflex syncope’ is used to describe reflex syncope occurring without an apparent trigger: the diagnosis is mainly based on history, exclusion of other causes of syncope, and a positive head-up tilt test. Although recent developments have prompted new pathophysiological hypotheses, including the adenosine pathway, the diagnostic strategy for reflex syncope remains mainly based on clinical evaluation and very few ancillary diagnostic tests. The pharmacological armament is still very limited while new perspectives have been opened for specific subgroup of patients. Regarding the very rare patients who are candidates for permanent cardiac pacing, a new pragmatic approach may help their selection and the prediction of the effect of pacing.