CAROTID-SINUS HYPERSENSITIVITY AND SYNDROME IN PATIENTS WITH CHRONIC ATRIAL-FIBRILLATION

Carotid sinus hypersensitivity (CSH) has been studied in subjects in s inus rhythm, but it has never been studied in patients with chronic at rial fibrillation (AF). After a finding of CSH in a patient with chron ic AF and syncope, we studied the effects of carotid sinus stimulation in a group of patients with AF. Ten patients with chronic AF and norm al ventricular rates who complained of dizziness or loss of consciousn ess underwent right and left carotid sin us massage (CSM) during ECG m onitoring. A control group of ten patients with AF but without neurolo gical symptoms was likewise investigated. CSH was present in eight sym ptomatic patients (5 patients presented right CSH, 1 left and 2 bilate ral CSH), but only in three of the control patients. The mean duration of asystole induced by right CSM was 5.94 +/- 2.10 seconds; the mean asystolic interval induced by left CSM lasted 8.58 +/- 1.42 seconds. S ix patients in the symptomatic group had a recurrence of spontaneous s ymptomatology during CSM, so that a diagnosis of carotid sinus syndrom e was established All symptomatic patients (8 patients with CSH, 2 pat ients with ventricular standstills but without CSH) received a permane nt ventricular pacemaker. Following pacing, all patients, except for o ne with a significant drop of systolic blood pressure during CSM, beca me completely asymptomatic. In elder patients with chronic AF, CSH can induce prolonged ventricular asystole, which may be responsible for n eurological symptoms such as dizziness, presyncope, or syncope, as obs erved in patients in sinus rhythm with carotid sinus syndrome. Abnorma l sensitivity of the carotid sinus could, therefore, be one of the cau ses of increased morbidity and mortality in patients with chronic AF. Permanent ventricular pacing may help reduce these complications.