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Cardiac function in fetal sheep during two weeks of hypoxemia
M Kamitomo1, L D Longo, R D Gilbert
1Department of Physiology, Loma Linda University, California 92350.
The American Journal of Physiology
|June 1, 1994
Summary
Prolonged hypoxemia significantly impairs ovine fetal cardiac function, reducing both right and left ventricular outputs over 14 days. Left ventricular function curves showed depressed plateaus, indicating reduced cardiac output capacity under chronic low oxygen.
Area of Science:
- Cardiovascular Physiology
- Fetal Medicine
- Hypoxia Research
Background:
- Fetal cardiac responses to acute hypoxemia are documented, but effects of prolonged hypoxemia remain less understood.
- Understanding chronic hypoxemia's impact is crucial for managing conditions affecting fetal oxygen supply.
Purpose of the Study:
- To investigate the long-term effects of sustained hypoxemia on ovine fetal cardiac function.
- To assess changes in right and left ventricular outputs and ventricular performance under chronic hypoxic stress.
Main Methods:
- Surgically instrumented ovine fetuses were exposed to 14 days of maternal hypoxemia (induced by N2 inhalation).
- Right ventricular output (QRV) and left ventricular output (QLV) were measured using electromagnetic flow probes.
- Ventricular function curves (preload and afterload sensitivity) were assessed in hypoxemic and control fetuses.
Main Results:
- Prolonged hypoxemia significantly reduced fetal arterial PO2.
- QRV decreased progressively from day 3 to day 14 of hypoxemia.
- QLV showed significant depression by day 7 and further decline by day 14, with a depressed plateau on ventricular function curves.
Conclusions:
- Sustained hypoxemia leads to progressive impairment of ovine fetal cardiac output, particularly affecting left ventricular function.
- The depressed ventricular function plateau suggests reduced cardiac contractility or efficiency under chronic low oxygen conditions.