Microneurographic evidence of sudden sympathetic withdrawal in carotid sinus syncope; treatment with ergotamine.

A proportion of patients with carotid sinus syncope (CSS) remain symptomatic even after pacemaker implantation because of persistence of a vasodepressor component. We report a patient with CSS whose syncopal episodes could be reproduced by carotid sinus massage and were due to profound hypotension associated with sudden sympathetic withdrawal, based on direct measurements of sympathetic nerve traffic. A double-blind trial with inhaled ergotamine provided significant symptomatic relief.