Heart-rate control in 8 to 10-year-old healthy and diabetic children

Abstract

Department of Paediatrics and Cardiorespiratory Research Unit, University of Turku, 20520 Turku 52, Finland Autonomic cardioneuropathy is a late complication in adult diabetic patients (Wheeler,T. & Watkins,P.J.,Br Med J 4:584, 1973). The problem of this project was whether disturbed cardiac chronotropic control could be detected by computerized heart-rate (HR) analysis early in juvenile diabetes mellitus. 11 children with diabetes (duration 3-5 yrs) and a similar number of sex- and agematched healthy control subjects, age 8-10 yrs, were investigated. The HR was recorded by a hybride computer system in supine position during spontaneous breathing, deep regular breathing and tilting at a rate of 0.1 Hz. For each record of 2 min two indices of heart-rate variability (HRV) and power spectrum of HRV were computed. Results: The diabetic patients had a higher mean HR both in spontaneous and stimulated conditions. The indices of HRV increased (p<0.01) indeep breathing test similarily in both test groups. The HRV did not change during tilt test. The negative slope of linear regression between the HR and HRV was significantly (p=0.008) steeper in healthy than in diabetic subjects in spontaneous conditions only. In the power spectrum the entrainment of HRV caused by deep breathing was identical in both groups. The results indicate evidence of limited HRV response in relation to HR already after 3 yrs' duration of diabetes, although respiratory HRV is produced in a normal way by deep breathing.