Management of cardioinhibitory hypersensitive carotid sinus syncope with permanent cardiac pacing--a seventeen year prospective study.

Sudden and unannounced syncope due to increased vagal tone as manifested by hypersensitivity of the carotid sinus mechanism is not uncommon. A 17 year prospective study of 89 patients with cardio-inhibitory (Type 1) hypersensitivity showed that males outnumbered females 4.5:1. The age range at the onset of symptoms was 37 to 88 years with an average of 63 years. Hypersensitivity of the right carotid sinus was 7:1 compared to the left. These patients had unilateral hypersensitivity in 71% and bilateral in 29%. A new classification of Hypersensitive Carotid Sinus Syncope incorporating sinoatrial node (Type 1A) and atriaoventricular node (Type 1B) suppression in the Type 1 syndrome is presented. Many forms of treatment for cardioinhibitory Hypersensitive Carotid Sinus Syncope have been forthcoming but in our hands in these 89 patients over 17 years, there has been no single case of recurrence of syncope after implantation of a permanent VVI electronic cardiac pacemaker. Type 2 (vasodepressor) Hypersensitive Carotid Sinus Syncope is rare, occasionally seen combined with the cardioinhibitory (Type 1) response and it is not helped with cardiac pacing.