Evaluation of tilt test and heart rate variability results of our patients in whom vaso-vagal syncope is considered

Vasovagal syncope (VVS), which develops due to over sensitivity of the autonomic cardiovascular system, is the most commonly observed syncope reason in children. Although head-up tilt (=tilt table) test (HUTT) is a method frequently preferred in distinguishing vasovagal syncope, its diagnostic value in children is questionable due to the lack of a standard protocol. Vasovagal syncope is known to develop with the presence of triggering factors in people who have autonomic dysfunction. Recently, determination of heart rate variability is used as the most important test in demonstrating autonomic dysfunction. There is only a limited number of studies which determine the value of tilt test for the diagnosis of vasovagal syncope in children and adolescents, and evaluate these patients for autonomic dysfunction by observing heart rate variability. The aim of this study was to evaluate the place of tilt test in the diagnosis of syncope, and to investigate autonomic dysfunction through basal heart rate variability in the group of patients who previously had holter monitorization. In the study, file records of nearly 300 patients who had tilt test for the diagnosis of vaso-vagal syncope between 2011 and 2014 in Akdeniz University Medical Faculty Pediatric Cardiology department were reviewed retrospectively. Demographic characteristics (age, gender), history (how many times she/he had syncope, if she/he had any additional diseases or not, drug use), physical examination findings and laboratory investigations such as ECG, ECHO, Holter, EEG and Brain MR were recorded. Patients (n:139) who had two or more syncope attacks and had a HUTT with the consideration of vasovagal syncope were included in the study. Of these patients, heart rate variability was calculated in those who had 24 hour holter records (n:46). Among the time-domain parameters in heart rate variability measurements SDNN, SDANN, SDNNindex, rMSDD, pNN50, Triangular index and among frequency-domain parameters LF/HF rate were calculated and analyzed. A total of 139 patients were included in the study. Of these patients 104 were female (74,8%) and 35 were male (25,2%). Average ages of the patients were 14,27±0,33 years in females and 13,23±0,68 years in males. When HUTT results of 139 patients were evaluated, it was (-) in 110 (79,1%), and (+) in 29 (20,9%). Holter records of 46 out of 139 patients were reached. Tilt result was (+) in 9 patients and (-) in 38 patients out of 46. When the average values of time-domain and frequency-domain parameters of HRV were compared in HUTT (+) and HUTT (-) patients, a significant difference was determined in favor of parasympathetic system activity in HUTT(+) patients in RMSSD, SDNNindex and pNN50 measurements among time-domain parameters (p <0,05) while no significant difference was determined among the LF/HF ratio among frequency-domain parameters and Triangular index (p>0,05). As a result, basal cardiac autonomic activity was found to be in favor of parasympathetic system in children with vasovagal syncope in this study. Although HRV was not evaluated during the tilt test in our study, similar results were found in other studies carried out with a similar protocol in the literature. For this reason, it was concluded that the autonomic activity increase in patients might have triggered syncope occurrence when the patients were exposed to orthostatic stress. For children who present with vasovagal syncope and have a (+) HUTT, the presence of parasympathetic activity increase in basal heart rate variability needs to be considered, and beta-blocker treatment should be started in a more cautious and controlled way.