THE SIGNIFICANCE OF THE PERICARDIUM IN ACUTE CARDIAC DILATATION PRODUCED BY ANOXEMIA

Abstract

In cats, dogs, and monkeys anesthetized with barbital the normal cardiac area was ascertained by taking x-ray pictures of the heart and measuring the cardiac silhouette with a planimeter. The animals were then subjected to anoxemia, corresponding to 2.5 to 5% oxygen, by placing them in a suitable steel chamber from which air could be withdrawn. About 8 min. were allowed to bring the animals to the desired level and the barometric pressure was held at this point for 2 min. They were then quickly removed and an x-ray picture was taken at once and the cardiac area measured. In order to check the results an apparatus was arranged so that anoxemia could be produced while the animal lay directly under the x-ray tube. The pericardium was now removed; the animal was allowed to resume its normal breathing. Two hrs. after the operation another control picture was taken and the area computed. The animals were again subjected tothe same degree of anoxemia. X-ray pictures were again taken and the area ascertained. Animals[long dash]monkeys in particular[long dash]with the pericardium removed tend to show a greater cardiac dilatation in severe degrees of anoxemia. The protective action of the pericardium to prevent acute cardiac dilatation can rarely come into play in the normal animal.