Circulatory responses in children with unexplained syncope evaluated by continuous non-invasive finger blood pressure monitoring.

Cardiovascular responses on active standing in children with unexplained syncope were investigated with continuous non-invasive finger artery pressure monitoring (Finapres). We examined 34 symptomatic patients (13 boys and 21 girls), aged 8-16 years, and 24 age-matched controls. Finger blood pressure and heart rate were monitored continuously for 5 min in the supine position and for 10 min while standing. Ten of 34 patients developed fainting symptoms with hypotension during upright posture (fainters). In the initial standing phase (0-30 s), two prominent abnormal blood pressure responses were found in patients: a marked decrease 45 +/- 18/23 +/- 8 mmHg and a prolonged recovery time (16.5 +/- 2.9 versus 27.7 +/- 13.6 s), which appeared to be based on impaired vasoconstriction. Either or both abnormalities were observed in 21 (62%) of the 34 patients and in 2 (8%) of the controls. In addition, fainters also had a more marked increase in heart rate during standing compared with non-fainters. Our findings suggested that more than half of children with syncope had abnormal cardiovascular reflexes in the initial phase which appeared to be associated with vasodepressor syncope. The active standing test with a continuous beat-to-beat blood pressure recording has a high sensitivity in detecting abnormalities of autonomic function in patients with unexplained syncope.