Abstract
It has been well documented in laboratory animals that β-sympathicomimetics, such as isoprenalin, can cause myocardial lesions. Other so called “β2-selective” symphaticomimetic drugs, which nevertheless induced β1-cardiostimulatory side effects, are now widely used for suppression of premature labor. We examined the hearts of 25 newborns whose mothers had been treated with β-sympathicomimetics for various lengths of time (24 h to 8 weeks). Three types of lesions were detected: (1) focal subendocardial necroses (3 cases), similar to isoprenalin-induced myocardial necroses in animal experiments, (2) diffuse fatty degeneration of myocardial cells (3 cases), and (3) nuclear polyploidization in the subendocardial layer of the right ventricular wall (14 cases). However, the immediate causes of death could not be directly related to the tocolytic treatment in any of the cases.