Role of prenatal echocardiography in the study of hypertrophic cardiomyopathy in the fetus.

The increased incidence of hypertrophic cardiomyopathy in children of diabetic mothers has already been demonstrated, but its prenatal diagnosis has not yet been extensively studied. The purpose of this prospective study was to evaluate the frequency, severity, and echocardiographic features of fetal hypertrophic cardiomyopathy in a population with several indications for prenatal echocardiography. From March 1987 to April 1991, 283 fetuses were submitted to comprehensive prenatal echocardiography, including M-mode measurements, cross-sectional imaging, Doppler studies, and color flow mapping. One hundred seventy-six were pregnancies complicated by previous or gestational diabetes. The diagnosis of disproportionate septal hypertrophy was made in 39 fetuses (mean septal thickness 7.12 +/- 1.6 mm), at a mean gestational age of 32 weeks. Diabetes mellitus was present in 36 of these pregnancies (92.3%). In four cases, nonimmune hydrops was detected. A systolic anterior motion of the mitral valve was present in three fetuses, but only one showed a gradient across the left ventricular outflow tract. Postnatal echocardiographic examination in 27 babies did not show false positivity. In ten cases, spontaneous regression of the septal hypertrophy was shown. There were three neonatal deaths, unrelated to the myocardial disease. We concluded that transient hypertrophic cardiomyopathy is a frequent entity, especially when associated with diabetes during gestation, being a potential cause for nonimmune hydrops. Fetal echocardiography is the method of choice for its prenatal diagnosis and should always be indicated in diabetic mothers.