A scientific evaluation of the carotid sinus syndrome.

Assessment of the carotid sinus baroreceptor control of pulse interval has been made, by means of neck suction, in 10 patients with a clinical diagnosis of the carotid sinus syndrome (CSS). Results have been compared with 16 age-matched control patients. The mean gain in the CSS patients was 11.64 +/- 2.51 ms . mmHg-1, whereas the mean gain in the control patients was 3.61 +/- 0.68 ms . mmHg-1 (p less than 0.02). There was a significant correlation (p less than 0.01) between the degree of cardiac slowing, following carotid sinus massage, and the gain, following neck suction, in the CSS patients. Abnormality of the carotid sinus baroreceptor control of heart rate is confirmed in these patients and neck suction is an useful method of investigation of this syndrome.