CEREBRAL-CIRCULATION DYSFUNCTION AND HEMODYNAMIC ABNORMALITIES IN SYNCOPE DURING UPRIGHT TILT TEST

OBJECTIVE: To assess the hemodynamic features, including monitoring of cerebral circulation, blood pressure and heart rate, in syncope patients during upright tilt test. DESIGN: Nonrandomized sequential patients with history of syncope of uncertain etiology compared with healthy subjects. SETTING. Noninvasive hemodynamic laboratory of a tertiary referral centre. PATIENTS: Twenty patients with history of syncope and 10 controls without syncope. PROCEDURES: Transcranial Doppler measurement or middle cerebral artery flow velocity, noninvasive and invasive blood pressure monitoring, electrocardiography and pulse oximetry monitoring during upright tilt testing. Measurements were taken in patients at the height of symptoms in supine and upright posture. MAIN RESULTS: Ten patients, while still normotensive, had a drop of 53+/-10% (mean+/-SD) in cerebral bloodflow velocity (P=0.0001) and an increase in heart rate by 58+/-35%. The remaining 10 patients had a 58+/-15% reduction in cerebral bloodflow velocity (P=0.0001), a drop in blood pressure of 33+/-8% (P=0.0001) and no change in heart rate. The controls showed no significant changes in cerebral bloodflow velocity and a 25+/-12% increase in heart rate (P=0.0002). CONCLUSIONS: Transcranial Doppler monitoring of cerebral bloodflow velocity during upright tilt testing may improve insight into the complex physiology of syncope.