Abstract
Summary
Pregnant rats were subjected to high altitude hypoxic stress and the offspring studied for heart malformations. Of the 99 fetuses born from the stressed rats, 28 were shown to have defective hearts. The most common defects (69%) were septal, ranging from very small apertures to a large opening covering one-fourth of the interventricular septum. Of the septal defects the most common was a communication between the left ventricle and right atrium which entered the left ventricle just below the cusps of the aortic valve and the right atrium just above the tricuspid valve. There were also intraventricular septal defects and 1 intra-atrial. Other defects were 4 with 90° rotation of the ventricles, 1 aortic stenosis, 1 pulmonary atrial stenosis, 1 narrowed infundibulum, and 1 over-riding aorta. Of the control animals only 7.5% had heart deformities, all of which were small interventricular defects, except in 1 fetus where the septum secundum failed to form.
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