THE PRESENT study was undertaken in order to study the chronic physiological and pathological changes that occur after pulmonary valvulectomy.
Adult mongrel dogs varying in weight from 7 to 14 kg. were used in the majority of the experiments. The dogs were given premedication with morphine and atropine and after open-drop ether induction, an endotracheal tube with an inflatable cuff was introduced and positive-pressure ether anesthesia was employed. The chest was opened through the left fourth interspace, and the pericardium was opened anterior and parallel to the phrenic nerve. Temporary ties of No. 4 braided silk were placed around the superior vena cava, inferior vena cava, azygos vein, and the distal portion of the main pulmonary artery.Except for the flow of blood through the coronary sinus, the return of blood to the heart was temporarily interrupted by traction on the braided silk ties; the pulmonary artery was opened