Time-dependent heart rate variability in the head-up tilt test in children with postural orthostatic tachycardia syndrome

Abstract:

Objective To study the time-dependent heart rate (HR) variability in the head-up tilt test (HUTT) in children with postural orthostatic tachycardia syndrome (POTS) and to explore the HR diagnostic criteria for POTS in children. Methods A retrospective analysis was performed on the clinical data of 105 children diagnosed with POTS with HR ≥120 beats per minute (bpm) within the first 10 minutes of HUTT between January 2007 and December 2014. Their HR variability within the first 10 minutes of HUTT was analyzed. Results The HR of children with POTS increased gradually from the supine position to a 60° head-up tilt position, and the increase in HR was 24±12 bpm at the beginning of HUTT, 30±14 bpm at 3 minutes of HUTT, 32±13 bpm at 5 minutes of HUTT, and 38±12 bpm at 10 minutes of HUTT. The average maximal HR increase within the first 10 minutes of HUTT was 43±10 bpm. Conclusions In children with POTS, the HR variability gradually increases with time, and therefore, it is suggested that HR increase ≥40 bpm is more suitable for diagnosis of POTS in children.