John H. Musser

Experimental Chronic Pericarditis. Further Contribution to the Study of Cardiac Hypertrophy.

Within the past year and a half we have performed periocardotomies on 60 dogs through the more or less avascular midsternal route and have introduced into the pericardium various substances, as bacterial antigen, organic and inorganic compounds. Morphine and ether anesthesia by the intratracheal method with artificial respiration were employed. Electrocardiograms and roentgenograms were made before and at intervals after operation and just before death when it was possible to do so. At autopsy the sternum, with the anterior mediastinum, the pericardium, heart and lungs intact, was carefully removed together and subsequently dissected and weighed. Six dogs died at the end of the first week with serous, fibrinous, and purulent pericardial effusion and with conspicuous anterior mediastinitis from the sternal wound to the heart. The heart weight-body weight ratios of these dogs ranged from 0.00988 to 0.00812, and were, thus, below the maximum normal of 0.01000, but above the average of 0.00798 established in a series of 200 normal dogs of all mongrel breeds, of various ages, sexes, and sizes. 1 One dog survived for 200 days with thick, anterior mediastinal bands of adhesions, but without any visceral adhesions. In this instance the heart weight-body weight ratio was found to be 0.00916. Another dog with a pure anterior mediastinitis for 10 days had a H. W./B. W. ratio of 0.00914. Five dogs had partial visceral synechia as well as heavy anterior mediastinal bands of adhesions for 212, 108, 83, 81 and 43 days, and these presented, respectively, H. W./B. W. ratios of 0.0133, 0.0100, 0.0131, 0.0079, 0.0082; thus presenting evidences of some cardiac hypertrophy, especially in dogs with the more extensive lesions for longer periods of time.

Sudden death of experimental animals following intrapericardial injections of tincture of iodine.

During the course of some experiments on rabbits, it was noted that injection of tincture of iodine (U. S. P.) into the pericardial sac was followed by some unidentified disturbance of cardiac mechanism which resulted in the death of the animals within a few minutes. The same series of events followed in each of the five animals employed. Six dogs were then studied. Under ether intratracheal anesthesia, the chest was opened and from 1.5 to 2 cc. of tincture of iodine injected, with much the same results as with the rabbits. As soon as the first few drops of the solution touched the epicardium there was an obvious visible effect on the heart muscle which continued until the death of the animal within five to ten minutes. Examining the heart grossly after death, it was found that the iodine had diffused over the entire epicardium but there was no visible evidence of staining of the heart muscle beneath the serous covering. In order to determine, if possible, the sequence of events following the injection of the irritant, the next two experiments were carried out in the Department of Physiology with the animals attached to the electrocardiograph. The first animal alone succumbed to the first dose of iodine. The second animal failed to show the usual prompt response and death did not occur until three injections of iodine had been given. We have no positive explanation to give of the phenomena observed. The rapidity of the effect of the injection would make it improbable that there was any systemic disturbance; rather it would point to a purely local action of the alcohol on the heart muscle or the electrical mechanism of the organ.