RESUMEN
AIM: Transcranial Doppler sonography was used to asses time relation and characteristically changes in middle cerebral artery blood flow velocity before syncope during tilt table test in children. METHOD: We performed tilt table tests in 40 pediatric patients with a medical history for syncope after exclusion of neurologic and cardiologic diseases. Examination was done in a 70 degrees postural position under control of electrocardiogram, blood pressure measurement and measurements of blood flow velocity of middle cerebral artery by transcranial Doppler with 3-MHz probe. RESULTS: In 13 children syncope occurred after 5 to 45 min (average 23.3). 10 of them were neurocardiogenic syncopes. With it diastolic and medium blood flow velocity of middle cerebral artery initial ever increased while resistance and pulsatility index decreased. Just before syncope the diastolic blood flow velocity decreased dramatically thus no diastolic blood flow could be measured, respectively. Almost we could measure no diastolic blood flow just before syncope occurred. CONCLUSION: Patients with neurocardiogenic syncope do have characteristically blood flow velocity changes of middle cerebral artery just before loosing consciousness. Transcranial Doppler is a usefully examination during tilt table. Clear transcranial Doppler results can help to prevent children from the impending syncope.