Fetal Breathing Movements Are Associated with Changes in Compliance of the Left Ventricle

Abstract

We have tested the hypothesis that the limited fetal ventricular distensibility is not only an intrinsic cardiac characteristic but is also contributed to by the pressure exerted by the intrathoracic organs. To this purpose we have studied the diastolic cardiac function by Doppler velocimetry in 11 fetuses during fetal breathing and in 22 fetuses during apnea, controlling for gestational age at examination and heart rate. Inspiration was associated with a significant increase in left ventricular compliance, as measured by deceleration time (inspiration 182.6 ± 15.5 s vs. expiration 137.1 ± 13.1 s vs. apnea 151.7 ± 51.8 s), and in ventricular filling, as measured by velocity time integral (inspiration 0.086 ± 0.020 m vs. expiration 0.064 ± 0.014 m vs. apnea 0.065 ± 0.011m), compared with both the expiration and apnea groups. These increases most likely reflect changes in venous return and ventricular end-diastolic volume secondary to a decrease in intrathoracic pressue during fetal breathing.

Bases morfológicas para o estudo do septo interatrial no feto humano

“…In an earlier study, it was also found that septum primum maximal excursion is increased during fetal breathing, a finding that was related to an increase in left ventricular distensibility due to respiratory movements 24 .…”

Behavior of Pulmonary Venous Flow during Fetal Respiratory Movements

“…We showed a significant reduction of pulmonary venous flow impedance, represented by the pulsatility index of the pulmonary vein, during fetal breathing movements. It is believed that, in apnea, the pressure of intrathoracic organs on the fetal heart, particularly as a result of nonexpanded lungs, limits ventricular distensibility 1 . Improvement of compliance and filling pressure reflects changes in venous return and end‐diastolic volume of the left ventricle, secondary to the fall of intrathoracic pressure during respiratory movements 21 .…”

“…Analysis of fetal breathing has been used as a physiological model of increased ventricular compliance and relaxation, according to observations by Miyague et al 1 . Van Der Mooren et al.…”

“…Respiratory movements influence fetal circulation 1 . Their presence indicates an intact, nondepressed nervous system, reflecting a good fetal clinical status 2–6 …”

A mobilidade do Septum primum não depende do diâmetro do forame oval em fetos normais

“…Another previous study has already demonstrated that, during fetal breathing, the excursion index of the septum primum is significantly increased; this finding was explained by an increase in left ventricular distensibility due to respiratory movements 7 . Therefore, excursion of the septum primum depends on multiple factors, and its correlation with the foramen ovale size has not been studied.…”