Scientific Session: REGULAR PROGRAM

1. Studies of Pulmonary Diffusion after Open Heart Surgery.

Robert J. Schramel (by invitation), Robert Cameron (by invitation),

Morton Ziskind (by invitation), Maurice Adam (by invitation),

and Oscar Creech, Jr., New Orleans, La.

This study was undertaken to determine the factors responsible for the high incidence of serious pulmonary complications in patients undergoing open heart surgery with the aid of extracorporeal circulation. Diffusion of carbon monoxide was measured by the technique of Filley in eight patients pre-operatively and post-operatively on the second, seventh, fourteenth, and twenty-first days. These studies demonstrated marked depression of the carbon monoxide diffusing capacity in every instance. This depression existed occasionally without significant roentgenographic changes and without clinically apparent pulmonary complications. To further evaluate the factors responsible for this depression, the carbon monoxide diffusing capacity was measured in dogs undergoing unilateral thoracotomy alone; extracorporeal circulation without inflow occlusion and without thoracotomy; extracorporeal circulation with inflow occlusion and without thoracotomy; extracorporeal circulation, inflow occlusion, and thoracotomy. The results of these experiments will be reported together with an evaluation of the relative contribution of the incision, extra-corporeal circulation, and existing heart disease to the observed depression of carbon monoxide diffusing capacity.

2. Clinical Results of Correction under Hypothermia of Atrial Septal Defects and Pulmonary Valvular Stenosis.

Earle B. Mahoney, James A. Manning (by invitation), James A.

Deweese (by invitation) and Seymour I. Schwartz

(by invitation), Rochester, N.Y.

This report is concerned with thirty-six patients who have had "open-heart" surgery performed under hypothermia for the closure of atrial septal defects and/or correction of pulmonary valvular stenosis. These patients have been subjected to long-term clinical observation following operation and have undergone post-operative cardiac catheterization. There has been uniform evidence of adequate correction of the defects, and the physiological data will be presented in detail. Twenty-four patients had coronary autoperfusion during inflow tract occlusion; eighteen had repair of ostium secundum defects of the atrial septum; and eighteen had pulmonary valvulotomy for so-called pure pulmonary valvular stenosis; three patients had both defects and had both corrected.

The surgery was performed under direct vision at temperatures between 28° C. and 31° C. for periods of caval occlusion averaging 5 minutes, 20 seconds. In those who received coronary perfusion, the myocardium was perfused with warm, oxygenated, heparinized blood previously withdrawn from the patient's aorta during simultaneous intravenous replacement of fresh heparinized donor blood. This autoperfusion has resulted uniformly in a fully saturated perfusate, and it has had the same evidence of beneficial effect on the myocardial tone, metabolism, and electrical activity as we have recorded in experimental observations. There has been one operative death in this group.

The long-term results indicate that the hypothermic technique offers an open-heart method for the correction of the defects, which is simple, and complete correction can be accomplished. The efficacy of the method demands accurate preoperative diagnosis which is possible with careful evaluation. The use of the pump oxygenator is reserved for lesions requiring ventriculotomy or prolonged periods of exposure for repair.

3. Simplified Technic for Direct Vision Pulmonary Valvotomy.

Conrad R. Lam and Rodman E. Taber, Detroit, Mich.

It is now well recognized that a completely satisfactory operation for congenital pulmonic stenosis must be done under direct vision, rather than by the transventricular methods. Following the example of Swan, many surgeons have employed hypothermia to provide adequate operating time for the valvotomy, and more recently, even pump-oxygenators have been employed during the operation.

It has seemed to us that with the valve clearly visualized, not more than one minute of time would be required to make the cuts necessary to open it completely. If this is the case, neither hypothermia nor the pump oxygenator are needed. In line with this theory, we have operated on 45 cases of congenital pulmonic stenosis with the patients at normal temperature. The period of caval occlusion has never exceeded a minute and a half, and there has been no instance of brain damage. One infant died of pulmonary complications in the postoperative period. Instances of isolated infundibular stenosis must and can be differentiated by catheter pressure tracings, and these cases must be operated on with the aid of the pump-oxygenator.

The procedure will be illustrated by a short motion picture film.

4. Surgical Treatment of Isolated Pulmonary Infundibular Stenosis.

William P. Hederman (by invitation), S.Gilbert Blount

(by invitation), and Henry Swan, Denver, Colo.

Infundibular stenosis occurring with an intact interventricular septum and a normal pulmonary valve is a relatively unusual condition. This paper discusses the relative incidence, clinical features, pathology, and differential diagnosis of the lesion. It is possible to identify the existence of this entity pre-operatively with some certainty. Four cases of our own who had surgical correction of isolated infundibular stenosis are reported, including objective post-operative studies of the hemodynamic changes effected by surgery. The need for accurate recognition of the lesion is stressed and the surgical approach and techniques involved, using hypothermia, are discussed in detail.

5. Surgical Experiences in the Treatment of Congenital Mitral Stenosis and Mitral Insufficiency.

George W. B. Starket, Boston, Mass.

Although congenital mitral valvular lesions are among the rarer anomalies they certainly can cause severe incapacitation and death in children. There have been seven patients operated upon to the date of submission of abstract. (Several more will undoubtedly be done before April 1959.) There has been one death from unexplained cause on the fifth postoperative day. The ages of these patients range from fifteen months (nineteen pounds) to fourteen years. All patients had been or were in heart failure. Both closed and open surgical methods have been used.

This group does not include the mitral insufficiency so often found in ostium primum defects - i.e. the bifid mitral septal leaflet. The pathological variations, catheterization data and clinical course of this very interesting group of patients will be presented and discussed.

6. The Etiology and Prevention of Atrial Fibrillation after Mitral Valvotomy.

C. Frederick Kittle, and James Crockett (by invitation),

Kansas City, Kan.

One of the most common postoperative complications after mitral valvotomy is the occurrence of atrial fibrillation in a patient with a previously normal sinus rhythm. Although recognized for several years, the prevention, etiology, and occurrence of this iatrogenic arrhythmia are poorly understood. Analysis has been made of 250 consecutive patients undergoing mitral valvotomy with particular attention to postoperative fibrillation.

Of the 250 patients 153 had a normal sinus rhythm preoperatively and 42 developed atrial fibrillation (an incidence of 27%). Of the 97 patients with atrial fibrillation preoperatively an attempt to establish a normal sinus rhythm was made in 45 with success in 12.

The predisposing factors of age, associated mitral insufficiency, prior attacks of atrial fibrillation, and electrolyte disturbances are discussed in relation to this postoperative arrhythmia. The suppressive actions of digitalis and/or quinidine in preventing this complication are analyzed.