ECHOCARDIOGRAPHIC LOAD-INDEPENDENT INDEXES OF CONTRACTILITY IN CHILDREN AND ADOLESCENTS WITH TYPE-I DIABETES - EFFECT OF METABOLIC CONTROL AND INSULIN ON LEFT-VENTRICULAR PERFORMANCE

A case-control study was carried out in a tertiary referral teaching hospital to evaluate left ventricular contractlity in children and adolescents with type 1 diabetes and to study factors influencing left ventricular contractility. Thirty-four children and young adults with type 1 diabetes (age 10.8-21.8 years) were randomly selected from approximately 400 patients of the same age range in the outpatient department and compared with 16 non-diabetic controls (age 7.3-21.2 years). The relation of end-systolic wall stress to velocity of circumferential fiber shortening as a standard deviation score (SDS) from the normal range described by Colan et al. was used to assess left ventricular contractility. In the diabetic group the effect of age, duration of diabetes, metabolic control, insulin dose, and autonomic function on left ventricular contractility were studied. It was found that the end-systolic wall stress-velocity of circumferential fiber shortening relation was not different between diabetic subjects and controls [+ 0.52 (SEM 0.21) vs + 0.90 (SEM 0.26) SDS, p = 0.3]. In the diabetic subjects, the end-systolic wall stress-velocity of circumferential fiber shortening relation was positively correlated with glycated hemoglobin (r = 0.37, p = 0.03) and insulin dose per kilogram of body weight (r = 0.36, p = 0.04). Those two variables together explained 24% of the variability in the end-systolic wall stress-velocity of circumferential fiber shortening relation. Twenty-eight of the diabetic subjects were also assessed for cardiac autonomic function. Disturbances of cardiac autonomic function were not associated with increased contractility. It is concluded that left ventricular contractility assessed by load-independent echocardiographic indices was not different between children and adolescents with type 1 diabetes and controls. However, increased contractility was positively related to unfavorable metabolic control and higher insulin dose.