The effects of betamimetic drugs used for tocolysis on the fetal myocardium.

During the last five years tocolysis with betamimetic drugs, e.g. Fenoterol has become a standard method for the treatment of impending premature births. We studied the effect of Fenoterol in vitro on organ cultures of human fetal hearts. At a concentration in the nutrient medium corresponding to the dose used in clinical application, light and electron microscopy demonstrated myocardia damage. In contrast the combined use of Fenoterol and the calcium antagonist Verapamil in a ratio of 1:40 showed no pathological findings either clinically or in vitro. The results are documented with light and electron photomicrographs.