摘要：Background Syncope is an important and common clinical condition, and the neurally mediated syncope is the most frequent type of syncope. Head up tilt testing is considered as a first line diagnostic test. The aim of this study was to assess the left ventricular outflow tract velocity time integral in echocardiography of pediatric patients with vasovagal syncope. Materials and Methods: In this case-control study, between January 2019 and December 2020 92 patients who referred in in Mofid Children Hospital in Tehran, Iran, for vasovagal syncope in the case group and 92 healthy children with maximum matching of sex and age in the control group were included in the study. Demographic, clinical and para-clinical data were recorded for each patient in the respective checklists, and HUTT and echocardiography were reviewed, then the results of two groups were compared. Results: The mean age of the patients with vasovagal syncope was 12.12 ±5.18 years. 66.3% of patients in the case group were female. There was a statistically significant relationship between LVOT-VTI and positive result of HUTT (p <0.001). There was no relationship between LVOT VTI in case and control groups (p=0.14). Conclusion The mean LVOT VTI index in patients with negative tilt test is higher than patients with positive tilt test. Although echocardiographic indices in children with vasovagal syncope are in normal range, accurate measurement of LVOT-VTI can be helpful in predicting a positive HUTT result.
