Heart rate variability in healthy children and in those with congenital heart disease both before and after operation

There are no reports of standard measures of heart rate variability (HRV) i n pediatric patients with heart disease. Time domain (standard deviation of all normal RR intervals [SDNN], standard deviation of all 5-minute mean RR intervals, average standard deviation of ail 5-minute RR intervals, and fr equency domain (total, low- [LF], and high-frequency [HF] power) measures o f HRV were (1) obtained in 45 healthy children, (2) compared between 36 chi ldren with congenital heart disease and age-matched controls, (3) compared before and after surgery, and (4) compared between age-marched postoperativ e patients staying <7 days (group I, n = 16) and those staying longer (grou p II, n = 16). In healthy children, SDNN increased rapidly during infancy a nd more gradually thereafter, while the LH/HF ratio decreased until prescho ol age, with a later increase into adolescence. Compared with controls, pre operative patients had decreased total (53 +/- 55 vs 84 +/- 75 beats/min(2) /Hz, p = 0.01) and HF (12 +/- 14 vs 29 +/- 46 beats/min(2)/Hz, p = 0.03) po wer despite having similar heart rates. In the immediate postoperative peri od, all measures of HRV were decreased from preoperative valves. Groups I a nd II did not differ in mean RR interval or HRV preoperatively; however, po stoperatively, HRV was decreased in group II when compared with group I (SD NN 53 +/- 17 vs 40 +/- 14 ms, p = 0.01), although the mean RR interval rema ined comparable (499 +/- 81 vs 481 +/- 62 ms, p = 0.3). It is concluded tha t (1) there are significant age-related changes in HRV in healthy children, (2) preoperatively, children with congenital heart disease have reduced to tal and HF power when compared with healthy controls, (3) HRV is further re duced postoperatively in all patients, and (4) prolonged postoperative hosp italization is associated with a greater reduction in HRV. (C) 1999 by Exce rpta Medico, Inc.