Effect of metoprolol in carotid sinus hypersensitive patients

The reflex effects induced by carotid sinus stimulation were studied in 23 subjects before and after oral administration of 200 mg metoprolol. Eight patients had sustained hypertension, eight had normal blood pressure. All patients had carotid sinus hypersensitivity (CSH). Seven normotensive subjects without carotid sinus hypersensitivity constituted the control group. Two hours after intake of metoprolol the baroreflex induced sinus node inhibition and blood pressure lowering effect proved to be greater, in all groups of subjects, than before taking the drug, however, in the group of carotid sinus hypersensitive patients with high blood pressure only the parameters relating to heart rate showed significant differences. In a comparison of the effects of the metoprolol on the parameters induced by carotid stimulation, significant increases could be seen in both CSH groups compared to the data found in the control group. The reflex induced fall in blood pressure and the time needed for the return to the prestimulating level showed a significantly greater augmentation in the normotensive, than in the hypertensive CSH patients.