Head-up tilt test provokes dynamic alterations in total peripheral resistance and cardiac output in children with vasovagal syncope.

AIM: This study examined the total peripheral vascular resistance (TPVR) and cardiac output changes due to the head-up tilt test (HUTT) in children with vasovagal syncope (VVS).
METHODS: From December 2013 to January 2016, we recruited 77 children diagnosed with VVS group at Peking University First Hospital, China, and 28 children without VVS provided the control group. Heart rate, blood pressure, TPVR, cardiac output and baroreflex sensitivity were monitored during the HUTT.
RESULTS: In the supine position, TPVR and baroreflex sensitivity were higher in the patients with VVS than the controls, but cardiac output did not differ between the two groups. There were obvious increases in the VVS patients from TPVR in the supine position to the prepositive response period (p < 0.05), then the positive response period (p < 0.01). However, we noted the opposite trend in cardiac output, from the supine position to the prepositive response period (p < 0.01) then the positive response period (p < 0.01).
CONCLUSION: During HUTT, children with VVS demonstrated increases in TPVR but decreases in cardiac output, during the transition from the supine position to the positive response. This response might be involved in the pathogenesis of VVS. ©2018 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.