Fetal Systolic Time Intervals in Late Pregnancy Effect of Atropine

Abstract

Abstract. Fetal systolic time intervals (FSTI) were derived from the externally recorded electrocardiogram and phonocardiogram in 74 women during late pregnancy. The FSTI of the first 43 patients were recorded as a control. In the others FSTI were registered before and after intravenous injection of atropine to the mother to increase the range of fetal heart rate. Two patients in the atropine group were excluded. Correlation was found between the duration of the heart cycle (R‐R interval) and the mechanical systole (S1‐S2 interval) before and after atropine. The amplitude of the initial part of the first heart sound (S1a) increased after atropine, when postatropine tachycardia evidenced significant placental transfer of the drug. After atropine some fetuses showed initial bradycardia or bradycardia without following tachycardia. In such periods of bradycardia S1a amplitude was reduced. During the initial period of postatropine tachycardia short periods of constant R‐R interval combined with varying S1a amplitude and S1‐S2 interval occurred. A close correlation was then present between S1a amplitude and S1‐S2 interval. The time from electrical to mechanical start of ventricular systole was measured as the R‐S1 interval; it did not vary with heart rate in the control group or in the atropine group before atropine was given. Atropine shortened the R‐S1 interval; no correlation was found between shortening and tachycardia. It is concluded that in the fetus, changes of FSTI can be observed from the externally recorded electrocardiogram and phonocardiogram. Signs of peripheral circulatory change after atropine were not found. The changes observed after atropinization can be explained as a reduction of vagal tonic inhibition of cardiac chronotropism and inotropism. Atropine also may cause a decrease of mitral valve flow.

Neurobehavioral effects of choninergic drugs in prenatal period

“…Внутривенное введение АХ при сроке беременности 2 месяца сопровождается снижением частоты сер-дечных сокращений у плодов [163]. При внутривен-ном введении атропина сульфата женщинам со сро-ком беременности 33-42 недели у плодов возникала тахикардия, а на ЭКГ регистрировали увеличение амплитуды зубца S и укорочение интервала R-S [92]. Клинические наблюдения также подтверждают су-щественное влияние атропина сульфата на сер-дечную деятельность плода.…”