VASOVAGAL SYNDROMES

Most cases of dizziness or syncope referred to the emergency departmen t or to services of internal medicine are caused by vasovagal syndrome s. They comprise relative bradycardia with vasoplegia, the cardiovascu lar response to a neurological stimulus. It is possible to distinguish vagal or vasovagal syncope which is very common, the very stereotype reflex syncopes, carotid sinus hypersensitivity sometimes associated w ith sinus node dysfunction and bordeline forms such as orthostatic sin us tachycardia and cerebrovascular syncope. The differential diagnosis is vast. from simple hysteria to severe cardiac disease. Tilt testing should be indicated for diagnosis of most cases of syncope with appar ently normal hearts. Therapeutic abstention is the rule, providing cer tain preventive measures are taken, but, should treatment be necessary , cardiac pacing remains an exceptional modality in vasovagal syncope. Strict clinical and physiopathological studies are still required to determine the long-term prognosis and the underlying mechanisms of the se syndromes.