Characteristic changes of the pre-ejection period of the human fetal heart during umbilical cord complications

Abstract

l IntroductionA differential analysis of the cardiotocogram allows conclusions äs to the functional state of the fetus. However, the interpretations of changes in the heart rate depend to a large extent on the experience of the examiner because of the poorly defined deliminations of specific pattems of heart rate changes. New techniques enable the recording of the pre-ejection period (PEP) of the human fetal heart; i.e., the time between ventricular excitation and aortic pressure rise, continuously parallel with the CTG [3,12,16,24,27]. The PEP is a measure of the myocardial contractility. Thus, with adrenergic Stimulation the cardiac contractility increases and the PEP is shortened. On the other hand, an increase in peripheral resistance leads to a lengthening of the PEP äs does a decrease of ventricular filling. Recent experiments in fetal lambs [20,21,37,52,53] showed in acute and chronic experiments [20,29] that in acute hypoxia the PEP falls below the normal ränge, and that with compression the PEP is increased while the relation of the PEP to duration of systole (relative PEP = PEPr) is constant. Furthermore, with umbilical cord complications characteristic PEP changes are seen and chronic and acute hypoxia lead to changes in the baseline level of the PEP. This study de als with the question whether the results of animal experiments from PEP recording together with the CTG apply to the human fetus during birth and whether the characteristics of the PEP and heart rate allow conclusions äs to the pathophysiology of umbilical cord complications. Curriculum vitae THOMAS BÄRTLING was born in 1947 in Material and methodDuring the delivery of 115 fetuses the course of the absolute and relative PEP was recorded for at least 50-90 minutes simultaneously with the CTG. Of the 115 fetuses, 38 had anuchal umbilical cord noted at birth. The CTG and PEP recordings of these 38 fetuses are the subject of the study. During or shortly after PEP recording a blood sample was obtained from the fetal scalp for the analysis of pH, base excess and pC0 2 . Blood gas analysis from umbilical artery blood was performed immediately postpartum. In five fetuses with documented cord complication the transcutaneous oxygen tension was recorded from the presenting part according to the method of HUCH [28,29,30] and recorded together with the PEP and

Fetal cardiac electromechanical intervals during labour and effects of hypoxia and cord compression

“…and one effect of this seems to be lengthening of PEP. Thus, Organ et al (1974) found prolonged PEP in seven fetuses, in three of which the FHR pattern of variable decelerations suggested umbilical cord compression, while Bartling et al (1980) recorded prolonged PEP in 15 of 3s fetuses with nuchal cord entanglement. We now add eight further examples of lengthened PEP in association with variable FHR decelerations, in four of which tight cord entanglement was confirmed at birth.…”

“…In addition to animal studies measurement of fetal cardiac electromechanical intervals (FCEMI) in the human has been reported from several centres (Organ el al. 1973a;Murata & Martin 1974;Bartling et al 1980) as well as by our team (Robinson et al 1978;Adam et al 1980).…”

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

“…The fetal systolic time intervals have been analysed by several research groups in the past 3–6 . The fetal pre‐ejection period has been studied the most extensively 7–11 . The fetal pre‐ejection period was defined as the interval between the onset of QRS complex of the fetal electrocardiogram and the beginning of ventricular ejection, timed as the opening of the aortic valve.…”

A new and simple Doppler method for measurement of fetal cardiac isovolumetric contraction time

“…The systolic time intervals of the fetal cardiac cycle have been analyzed by several authors in the past [4][5][6][7] . The fetal PEP was defined as the interval between the onset of the QRS complex (electrical activity on the fetal electrocardiogram (ECG) relating to ventricular contraction) and the beginning of ventricular ejection, timed as the opening of the aortic valve.…”