Cardiac Performance after Open Intracardiac Surgery.

THE hemodynamic state, blood gas levels, blood volumes, and residual shunts soon after repair of atrial septal defect, ventrieular septal defect, and tetralogy of Fallot have been described in previous publications.1-4 Similar data have now been obtained after open operation for acquired disease of the aortic valve, and additional measurements of atrial pressures after repair of ventricular septal defect and tetralogy of Fallot have been nmade. The present paper represents an attempt to sumnmarize all these data in such a way as to permnit generalizations concernilng the relation of various factors to cardiac output, heart rate, stroke volume, and atrial pressure (in a word, to cardiac performance) after open intracardiae surgery. The variability in the relations of cardiac output to the arteriovenous difference in oxygeni content of blood and in the percentage of oxygen saturation of mixed venous blood becomes apparent from examiinationi of these data and, as would be expected, is related to the variability in the metabolic rate and the anmounit of hemoglobin in the blood after operation. These studies and observations nmade by other investigators have led to the gradual evolution of methods of accomplishing the operation and postoperative care so as to maintain optimal cardiac perfornmanee and blood gas levels in such patients. The incidence of deaths from low cardiac output, a problem originally stressed by Boyd and associates, has thereby been decreased.