[Carotid sinus syndrome. Apropos of 6 cases with the cardio-inhibitory type].

The hyperirritable carotid sinus syndrome may have three different expressions: 1. a prolonged ventricular pause, the cardioinhibitory type and the most common; 2. hypotension without slowing of the heart rate, the vasodepressor type; 3. the association of a prolonged ventricular pause and hypotension, the mixed type. The aim of this communication is to present 6 cases of the cardioinhibitory type of hyperirritable carotid sinus syndrome. Three cases were selected from a series of 242 patients investigated for syncopal episodes. The results of carotid sinus massage and electrophysiological investigation could be classified into 4 goups: --Carotid sinus massage reproducing the clinical symptoms negative electrophysiological investigation: pure carotid sinus syndrome. --Carotid sinus massage negative, electrophysiological investigations negative: pure hyperirritable carotid sinus syndrome. --Carotid sinus massage reproducing the clinical symptoms, electrophysiological investigation positive: associated carotid sinus syndromes. --Carotid sinus massage negative: electrophysiological investigations positive: associated hyperirritable carotid sinus syndrome. The diagnosis of the cardioinhibitory type of hyperirritable carotid sinus syndrome was made on four criteria: 1. the association of hyperirritable carotid sinus and spontaneous syncopal or minor syncopal episodes; 2. the reproduction of symptoms together with a ventricular pause of over three seconds by carotid sinus massage under cover of pacing (to exclude the rare mixed forms); 4. the absence of associated sinus node dysfunction or atrioventricular conduction defects on endocavitary electrophysiological recordings. This syndrome should be tested for as a routine in patients with syncope as usually no suggestive trigger factors are found. Carotid sinus massage in this series of patients caused quite long ventricular pauses (average: 7,5 sec.) with serious symptoms (2 syncopes). Therefore, in the investigation of patients with syncope it would seem to be useful to perform this manoeuvre during electrophysiological investigation with pacing cover. The treatment of choice of the cardioinhibitory carotid sinus syndrome is permanent pacing. This was undertaken in 5 out of four 6 patients leading to total regression of all symptoms. It seems justifiable to propose permanent pacing for patients who have syncope with hyperirritable carotid sinus syndrome, easily demonstrated by carotid sinus massage, but in whom massage does not provoke symptoms, reasoning by analogy with patients with atrioventricular conduction defects or sinus node dysfunction.