Changes in the systolic time intervals of the fetal heart after surgical manipulation of the fetus

The fetal cardiac systolic time intervals are potentially an important indicator of fetal well-being. Because experimental studies with the use of animal models are being carried out to evaluate the effects of abnormal antenatal factors on fetal myocardial function, it is important to establish the changes in the systolic time intervals that can occur as a result of the surgical preparation of the animal model and also to determine the time required for the recovery of myocardial function. After the appropriate catheters have been placed in fetal sheep, the ratio of preejection time to ejection time was followed in six maternal-fetal sheep models for 3 days postoperatively. The mean values obtained from the animals were then compared to the data obtained and were considered to be normal on the eighth postoperative day. In spite of acid-base data within the physiologic limits, the ratio of preejection period/ejection time was elevated postoperatively and reached normal values between 2 to 3 days postoperatively. The study demonstrates that 3 days are required for the recovery of fetal myocardial function before baseline preexperimental conditions are reached.