Introduction The term idiopathic ventricular tachycardia (IVT) refers to a clinical entity observed in children and adults in whom conventional diagnostic evaluation fails to detect structural heart disease. Precise data about the incidence and prevalence of IVT in children is insufficient, and published pediatric studies in- cluded small numbers of children (from 4–26) with IVT [11, 26]. It was found that children with IVT have a good prognosis, although reports of sudden deaths have appeared [7, 28]. Bojko Bjelakovic Goran Vukomanovic Vladislav Vukomanovic Ljiljana Pejcic Ljiljana Saranac Ljiljana Bjelakovic Lidija Dimitrijevic Heart rate variability in children with idiopathic ventricular tachycardia Accepted: 13 April 2007 Published online: 25 May 2007 j Abstract Idiopathic ventricular tachycardia (IVT) is a rare arrhythmia in children. A great deal of uncertainty and numerous questions still remain regarding the extent of investigation, ther- apy, and long-term prognosis for children with IVT. The existence of subclinical cardiac disease, as well as of autonomic dysfunction in patients with ventricular arrhythmias, has been well documented. A number of exper- imental and clinical studies have suggested that imbalances within the cardiac autonomic system’s activity may be crucial in the generation of ventricular tachy- cardia, irrespective of the presence of cardiovascular pathological substrate. Heart rate variability (HRV) analysis provides a useful method for measuring the auto- nomic activity. This study evaluates HRV in children with IVT. The study included 31 children with ventric- ular arrhythmia who were divided into two groups: (1) patients with frequent ventricular extrasystoles (VES) and (2) patients with IVT. The control group comprised 23 healthy children without patho- logical findings on 24-h ECG Hol- ter. Twenty-four-hour ambulatory electrocardiography recordings were obtained, and the time- domain variables were calculated. HRV was compared to age-related normal values. It was observed that the overall heart rate vari- ability is diminished in children with IVT. We recommend HRV analysis of any child with IVT. Quantifica- tion of the autonomic nervous system activity using time domain analyses may be a helpful diag- nostic tool in the clinical assess- ment and initial evaluation of these children. j Key words ventricular Æ tachycardia Æ heart rate Æ variability Æ autonomic nervous system RESEARCH ARTICLE Clin Auton Res (2007) 17:153–159 DOI 10.1007/s10286-007-0416-1 CAR 416 B. Bjelakovic, MD, PhD (&) L. Pejcic, MD, PhD L. Saranac, MD, PhD L. Bjelakovic, MD, PhD Clinic of Pediatrics, Clinical Center Nis Zorana Djindjica 48 Boulevard 18000 Nis, Serbia Tel.: +381-18/534-579 Fax: +381-18/238-770 E-Mail: bojko@medianis.net G. Vukomanovic, MD, PhD University Children’s Hospital Belgrade, Serbia V. Vukomanovic, MD, PhD Mother and Child Health Institute, ‘‘Dr Vukan Cupic’’ Belgrade, Serbia L. Dimitrijevic, MD, PhD Clinic of Physical Medicine and Rehabilitation, Clinical Center Nis Nis, Serbia Departments at which the work was done: Clinic of Pediatrics, Clinical Center, Nis and University Children’s Hospital, Bel- grade, Serbia