The fetal cardiac isovolumetric contraction time in normal pregnancy and in pregnancy with placental vascular disease: the first clinical report using a new ultrasound technique

Objective To study the fetal cardiac isovolumetric contraction time in norm al and complicated pregnancies with placental vascular disease using a newl y developed digital Doppler cardiography system. Design A preliminary case-control study. Setting Tertiary referral hospital. Sample One hundred and sixteen normal fetuses (20 to 49 weeks) and 55 compl icated pregnancies with placental vascular disease as documented by a high systolic: diastolic ratio in the umbilical artery Doppler flow study. Method A digital Doppler cardiography system with a high sampling rate (400 0Hz) was used to detect the fetal cardiac valvular movements. The isovolume tric contraction time was measured as the interval between the mitral valve closing and the aortic valve opening with a built-in scale device. Results In normal pregnancy the isovolumetric contraction time remained rem arkably constant with gestation and fetal heart rate. Comparison between cl inical outcome and the isovolumetric contraction time of the complicated fe tuses who were born within a week after the last determination of the isovo lumetric contraction time revealed a strong correlation between prolonged i sovolumetric contraction time duration and abnormalities in the perinatal c ourse (non-reactive fetal heart rate pattern, low pulsatility index in the fetal middle cerebral artery Doppler flow and low birthweight infant). Conclusions The isovolumetric contraction time is constant with gestation a nd fetal heart rate in normal pregnancy. In the presence of placental vascu lar disease a prolonged fetal isovolumetric contraction time predicts adver se outcome.