[Carotid sinus massage in diagnosing syncope of unknown origin].

Carotid sinus massage (CSM) was performed in 44 patients (23 female, 21 male, mean age 52 years) with recurrent episodes of unexplained syncope and without any organic heart disease. The protocol of examination consisted of 5 s CSM performed unilaterally in supine, upright 60 degrees positions, after administration of propranolol (i.v. 0.1 mg/kg) and during autonomic inhibition (atropine i.v. 0.02 mg/kg after propranolol). The diagnosis of hypersensitive carotid sinus syndrome (HCSS) was established in case of pathologic response to CSM in supine and upright 60 degrees positions. Positive results of CSM was obtained in 15 (34%) examined patients. Cardioinhibitory form of HCSS was recognized in 9 and mixed form in 6 cases. Pathologically augmented carotid sinus reflex was provoked in 8 cases by massage of the right, in 4 cases of the left and in 3 both carotid sinuses. Maximal time of electrical asystole after CSM was 6300 ms while maximal decreased od systolic blood pressure was 70 mmHg. Intravenous administration of propranolol caused decrease of systolic blood pressure approximately 43 +/- 15 mmHg whereas the cardioinhibitory effect of CSM after this drug significantly was increased only in patients with a positive response to CSM in the supine or upright 60 degrees positions. Autonomic inhibition significantly decreased the cardioinhibitory effect of CSM without significant influence on its vasodepressive component.