Thomas M. Durant

Pulmonary (venous) air embolism

Abstract Pulmonary (venous) air embolism is a catastrophe which may occur under a variety of circumstances in medical practice. It must be distinguished from arterial air embolism. Our studies in the experimental animal have shown that important factors in determining whether death or survival will occur are: (1) the amount of air which gains admission to the circulation, (2) the speed with which it enters, (3) the position of the body at the time of the embolic accident, and (4) the efficacy of the respiratory excretory mechanism. Death, when it occurs, is due to circulatory obstruction resulting from an air trap in the right ventricular outflow tract. Displacement of the air trap by turning the body into the left lateral position may be life saving even after the right ventricular contractions have become feeble and death seems imminent. Pulmonary air embolism provides a valuable means of studying experimentally the effects of acute right ventricular dilatation produced by obstruction. The rapid and profound electrocardiographic changes which occur under these circumstances include an excellent demonstration of the effects of myocardial ischemia, and also, in some instances, the demonstration of right ventricular conduction defects. The observations of Bayley and LaDue concerning the ischemia-injury pattern are confirmed.

Arterial air embolism.

Abstract Arterial air embolism is an infrequent but often disastrous complication of various thoracic therapeutic procedures. Occasionally it may result paradoxically from air entering the systemic veins and reaching the systemic arteries through a septal defect, or possibly by other mechanisms. The serious manifestations are the result of obstruction by air bubbles of cerebral and coronary vessels, together with spasm of these vessels induced by the irritation of the gas. Animal experiments indicate that air introduced into the coronary circulation, either directly or by injection into the pulmonary vein or left auricle, produces ischemia of the myocardium in areas supplied by involved vessels. The ischemia is demonstrable grossly and by electrocardiographic examination. It may be very temporary, with speedy recovery, or it may persist even after the apparent complete disappearance of the gas bubbles. Death from ventricular fibrillation may result within a very short time after the injection of the air. The distribution of air within the arterial circulation is determined by the principle of air buoyancy. This principle may be made use of in the therapy of arterial air embolism.

Transient bundle branch block and other electrocardiographic changes in pulmonary embolism

Abstract Transitory electrocardiographic changes which have their onset in right bundle branch block and occur in association with pulmonary embolism are described and their diagnostic significance discussed. The importance of the very early conduction disturbance, occurring within a few hours of the onset of the condition, and the rapidity with which this disturbance regresses are emphasized.

Splenomegaly associated with rheumatic heart disease: Its diagnostic significance

Abstract In a careful study of eighty patients with rheumatic heart disease, the spleen was found to be palpable in eighteen instances. In two the splenomegaly was due to subacute bacterial endocarditis, in two to coexisting portal cirrhosis, and in one it was probably the result of tuberculous dissemination. In the remaining thirteen cases (16 per cent), no cause, other than congestive failure, was found to explain the splenic enlargement, and clinical evidence of congestive failure was minimal or absent in a few of these cases. While it is admittedly very important to consider subacute bacterial endocarditis in all cases of rheumatic heart disease with fever and splenomegaly, the clinician must not place too much reliance upon splenomegaly as a finding favoring such a diagnosis.

Effect of Carbon Dioxide and Other Gases on Electrocardiogram of the Right Ventricle.

Conclusion The rapid intravenous injection of gases or mineral oil in sufficient quantities to replace blood in the right ventricle of dogs will cause the reduction or loss of the initial ventricular deflection of the electrocardiogram in direct leads from the epicardial surface of the right ventricle.