INFARCTION OF THE CARDIAC AURICLES (ATRIA): CLINICAL, PATHOLOGICAL, AND EXPERIMENTAL STUDIES

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Abstract
In 182 cases of myocardial infarction, 31 (17%) showed auricular involvement. Some Electrocardiograms were taken in 23 of 31 cases, and abnormal auricular mechanism was present in 17 (74%). But in 91 verified cases of ventricular infarction without auricular infarction (in which ECGs had been taken) there was disturbed auricular mechanism in only 8 (8%). In patients with auricular infarction, auricular fibrillation was observed in 9 cases, auricular premature beats in 4, auricular flutter in 2, and sinus arrest and wandering pacemaker in 1 each. The great majority of infarcts were in the right auricle, usually in the appendages. The descending and circumflex branches of the left coronary artery, and the right coronary artery, were always diseased; serious stenosis or occlusion was encountered m 23 of 31 cases. Gross appearance of atrial infarcts was similar to those in the ventricle. In the dog, the right and left coronary arteries were dissected out, each auricular branch being isolated, ligated. and cut. ECGs were taken during the operation and daily thereafter. One or more atrial arteries were ligated in 18 dogs; all the right atrial branches were ligated in 11; all the left atrial branches in 7, and the arteries of both atria in 4. In 4 dogs the effect of chemically produced atrial necrosis was studied. The dogs were later sacrificed, and the hearts injected, using the Gross technique. Disturbances of auricular mechanism occurred in only 6 of 20 of the expts. In 4 expts. there were transient changes in the P waves. Depression of the P-Q segment of the electrocardiogram -was seen in 4 instances. Abnormalities of the auricular mechanism are the most reliable clues to the clinical diagnosis of auricular infarction.