Association of Supine and Upright Blood Pressure Differences with Head-Up Tilt Test Outcomes in Children with Vasovagal Syncope

Mohammad Reza Khalilian ¹ Mohammad Mehdi Nasehi ^2,3 Fargol Farahmandi ^4* Farzaneh Farahmandi ¹ Tahmineh Tahouri ¹ Parynaz Parhizgar ⁴

• ¹ Department of Pediatrics, Shahid Beheshti University of Medical Sciences, Tehran, Alborz, Iran
• ² Pediatric Neurology Research Center, Research Institute for Children's Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran., Tehran, Iran
• ³ Pediatric Nephrology Research Center, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Alborz, Iran
• ⁴ Student Research Committee, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran, Tehran, Iran

Vasovagal syncope (VVS) is the most common childhood neurally mediated syncope. This study aims to define the different hemodynamic patterns in pediatric cases of vasovagal syncope and the difference between supine and upright blood pressure (orthostatic blood pressure), and other factors affecting them. Medical records of 88 children with normal laboratory and subclinical tests referred to Mofid Hospital for head-up tilt testing were retrospectively evaluated. Eightyfive children, 31 (36.5%) boys and 54 (63.5%) girls, aged 10.72 ± 3.52 years (median 10; range 4-17), with vasovagal syncope, were enrolled in the study. Age, sex, baseline heart rate, baseline blood pressure, orthostatic blood pressure, provoking factors, symptoms, and frequency were recorded. The test protocol included 10 minutes of supine rest followed by 30 minutes of upright positioning at a 70-degree angle. Subjects were divided into groups according to their differing hemodynamic patterns based on modified VASIS criteria. Our data showed a strong association between the difference in supine and upright blood pressure and positive HUTT results (p = 0.001). In the positive HUTT group, age had a higher probability of vasodepressor pattern in younger patients (p-value=0.014). Also, a significant relationship is seen with the boys (p- § The authors Mohammad Reza Khalilian and Fargol Farahmandi have contributed equally to this work and share first authorship. value=0.014, 0.038), which means that the male gender increases the probability of a positive tilt test.In conclusion, our study indicates that orthostatic blood pressure can predict HUTT in VVS children. Also, our results showed there is a higher chance of having a positive response to HUTT for the younger boys. Further studies in this field are warranted.