All issues > Volume 46(10); 2003

Original Article

J Korean Pediatr Soc. 2003;46(10):983-988. Published online October 15, 2003.

Change of Cerebral Blood Flow during Tilt Tests in Children with Vasovagal Syncope

Su Jung SJ Kim¹, Hye Won HW Yom¹, Young Mi YM Hong¹, Jung Hyen JH Yoo², Sook Hee SH Lee³, Chong Hee CH Kim³

¹Department of Pediatrics, College of Medicine, Ewha Womans University, Seoul, Korea
¹Department of Pediatrics, College of Medicine, Ewha Womans University, Seoul, Korea
²Department of Radiology, College of Medicine, Ewha Womans University, Seoul, Korea
³Seoul School Health Center, Seoul, Korea

Correspondence Young Mi YM Hong ,Email: hongym@chollian.net

Abstract

Purpose
: Syncope appears to be common. However, the mechanism of syncope is not clear. Increased vagal activity and withdrawal of sympathetic stimulation cause hypotension, bradycardia and finally loss of consciousness. The purpose of this study was to evaluate changes of cerebral blood flow velocity, blood pressure, and heart rate during tilt test in children with vasovagal syncope.
Methods
: Sixty four children with a past history of syncope were evaluated. The stand up test was performed for 15 minutes after a rest at supine position for 10 minutes, followed by an 80컏ilt test lasting 45 minutes. If presyncope(lightheadedness, nausea, blurred vision, or sweating) or syncope occurred, the study was discontinued. 12-lead electrocardiography, echocardiography, and electroencephalography were performed. Transcranial Doppler study was performed at the middle cerebral artery with 2 MHz continuous Doppler probe in 10 children with positive tilt test. Systolic, diastolic, mean cerebral blood flow velocity, integral, and pulsatility index were measured with blood pressure, heart rate, and O2 saturation.
Results
: The positive rate of tilt test was 31.3%(20/64). Systolic, diastolic, and mean cerebral blood flow velocity decreased significantly in absence of hypotension or bradycardia during presyncope. Time velocity integral of cerebral artery also decreased significantly.
Conclusion
: Decreased cerebral blood flow velocity can predict the presyncope manifestation. Impairment of autoregulation of cerebral blood flow might play an important role in the pathophysiology of vasovagal syncope.

Keywords :Vasovagal syncope, Tilt test, Transcranial Doppler study