925-39 Prenatal Hypertrophic Cardiomyopathy and its Association with Amniotic Fluid Insulin in Fetuses of Diabetic Mothers

Abstract

The frequent presence of a disproportionate hypertrophic ventricular septum in infants of diabetic mothers, as well as its benign course, has been widely reported. This phenomenon has also been demonstrated in the fetus. The most accepted hypothesis to explain this disorder, yet to be proved in the prenatal period, is fetal hyperinsulinism due to inadequate control of maternal diabetes. This prospective controlled tra nsversal study was carried out to test the hypothesis that hypertrophic cardiomyopathy during prenatal life in diabetic pregnancies is related to fetal hyperinsulinism as assessed by amniotic fluid insulin levels. Sixty-five fetuses (37 of diabetic mothers and 28 of hypertensive mothers) were studied sequentially and non-intentionally. A comprehensive M-mode and cross-sectional Doppler echocardiogram, with color flow mapping, was performed within one week of the amniocentesis in every case. Fetal insulin levels and interventricular septum thickness were considered abnormal when their values were above 2 standard deviations, according to local nomograms. Statistical analysis utilized Student's “t” test, Fisher's exact test, ANOVA and Kruskal-Wallis test. The mean gestational age at the time of examination was 32.3 ± 3.5 weeks (24 – 39 weeks) in the gestational diabetes group, 28.5 ± 2.7 weeks (23 – 33 weeks) in the previous diabetes group and 30.6 ± 3.1 weeks (25 – 36 weeks) in the control group. Mean septal thickness was 3.7 (2.2 to 6.3 mm) in the group of diabetic mothers and 3.0 (2.0 to 4.3 mm) in the control group (p < 0.01). Mean fetal insulin levels was 14.7 ± 16.8 microlU/ml (3.2 to 75.3 microlU/ml) in the group with diabetes and 6.4 ± 3.3 microlU/ml (3.1 to 17 microlU/ml) in the control group (p < 0.01) Median insulin levels were 8.7 and 5.5 microlU/ml in the diabetes and in the control group, respectively. Ten out of 37 fetuses of the diabetic group were considered to have hypertrophic cardiomyopathy (27%). while none of the fetuses of the control group showed increase in the septal thickness (p < 0.01). A significant association between prenatal hypertrophic cardiomyopathy and fetal hyperinsulinism was demonstrated (p < 0007). We conclude that there is association between the presence of hypertrophic cardiomyopathy during prenatal life and high levels of fetal insulin in diabetic mothers, thus justifying efforts to improve the glucemic control in pregnancies with this frequent complication.