Cardiac Pre-Ejection Period during Prenatal Life

Abstract

Perinatal clinicians are confronted with the problem that they are supposed to gather information about the condition of the unborn child almost exclusively by monitoring the rate of the fetal heart. Human heart rate recording, however, is no more or less informative in utero than in the newborn nursery. Determination of the pre-ejection period (PEP) of the fetal heart might provide information regarding the performance of the heart of the human fetus in utero and about its cardiovascular adjustments during fetal distress. On the verge of introduction of clinical human fetal PEP monitoring, this article presents a review of the results obtained from chronically instrumented fetal animals as well as some preliminary data from human perinatal research. Finally, possible future developments in human fetal PEP recording are anticipated and it is concluded that the most promising feature of the PEP for clinical use appears to be its predictive value as an early antepartum indicator of possible fetal distress during subsequent labor.

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

“…A double monophasic PEP increase appears to be characteristic for cord complications; 89% of all fetuses in our material with heart rate changes during the contraction (N = 103) who had a twostep type PEP increase had a documented cord complication. This second rise in PEP following an initial rise has been observed by EVERS and DE HA AN [20,21] in chronic sheep experiments with poorly oxygenated fetal lambs (e.g., Figures 4 and 5). EVERS and DEHAAN [20,21] demonstrated that the second PEP rise is caused by a second increase in arterial blood pressure.…”

“…This second rise in PEP following an initial rise has been observed by EVERS and DE HA AN [20,21] in chronic sheep experiments with poorly oxygenated fetal lambs (e.g., Figures 4 and 5). EVERS and DEHAAN [20,21] demonstrated that the second PEP rise is caused by a second increase in arterial blood pressure. If the ,alpha-adrenergic receptors in the fetal lamb were blocked with phentolamine the second rise in blood pressure and PEP was not observed.…”

“…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.…”

Transcutaneous and Arterial Carbon Dioxide Tension at Various Conditions of Fetal Stress in Lambs

“…However, obstruction of the umbilical cord had a more pronounced effect on fetal acid-base state. The effect of maternal common iliac artery occlusion on the fetal acidbase state was less striking, possibly due to the extended collateral circulation in the pelvis of the ewe, which often results in an incomplete and variable uteroplacental blood flow after occlusion [16]. In both experiments PaCCK increased significantly during obstruction and decreased within a few minutes after release of the clamp.…”

Assessment of Left Ventricular Pre-Ejection Period in the Fetus Using Simultaneous Magnetocardiography and Echocardiography

“…The fetal PEP was studied in the 1970s and 1980s as a possible parameter of fetal condition [5][6][7][8][9][10] . It was suggested that PEP reflects both myocardial contractility and the loading conditions of the heart, and may be a useful indicator of fetal cardiac performance and hence of the condition of the fetus as a whole [5] .…”