Thursday Morning, May 8, 1952

9:00 A.M. Business Meeting.

9:30 A.M. Scientific Session.

1. Experimental Methods for Detection of Changes of Blood Supply to the Heart.

Alfred Goldman, Clinton Shaw (by invitation), Eliot Corday (by invitation),

Joshua Fields (by invitation), S. Rexford Kennamer (by invitation),

Allen Smith (by invitation), Inga Lindgren (by invitation)

and Myron Prinzmetal (by invitation),

Los Angeles, Calif.

In an effort to determine the effects of increased blood supply which might be induced by therapeutic surgical procedures for ischemic heart muscle, an extensive investigation of the hearts of forty dogs subjected to ligation of the anterior descending coronary artery was carried out. This investigation showed that certain methods might be utilized to detect the effects of altered blood supply to cardiac muscle.

(1) High speed motion pictures were used (heart beats were slowed 120 times) so that subtle differences in motion of normal and ischemic muscle could be clearly seen.

(2) An exhaustive electrocardiograph study was made including limb and chest, direct pericardial, epicardial, intramural, and ventricular cavity leads. By means of a new technique it was possible to photograph simultaneously the beating ischemic heart together with the direct writing electrocardiogram.

(3) Careful comprehensive histological studies of all hearts were made to determine the extent of distribution of ischemic tissue.

Thus a unique and original correlation of physiological disturbances as seen in the motion pictures with electrocardiographic and pathological findings was made. The effect of slight changes in blood supply could be detected by all three methods.

Fundamental work of this type appears necessary for evaluating experimental surgical procedures intended to increase the blood supply to diseased heart muscle. For example-direct leads of the human heart could be made m the operating room, the ischemic area outlined and the immediate effects of surgical therapeutic measures evaluated.

These methods will be demonstrated by suitable colored pictures.

2. Artificial Oxygenation and Circulation During Complete Bypass of the Heart.

James A. Helmsworth, Roger T. Sherman (by invitation),

Samuel Kaplan (by invitation) and Leland C. Clark (by invitation),

Cincinnati, Ohio

Approximately 50 dogs were subjected to total bypass of the heart for periods of 30 minutes. Observations during the experiments included determination of serum proteins, blood electrolytes, pH, and carbon dioxide and oxygen content. The nine survivors made a prompt and complete recovery.

A new method for the drainage of all venous blood from the right heart was employed. The operations on dogs with blood rendered incoagulable by heparin and the several steps in cannulation required specific modifications of surgical technic.

The Fels Oxygenator employed consisted of a unit for dispersion oxygenation, a chamber for bubble coalescence, and a pumping force achieved by cyclic alteration of the oxygen pressure in the closed system.

3. Some Physiological Aspects of the Artificial Heart Problem.

F. D. Dodril, Edward Hill (by invitation) and

Robert Gerisch (by invitation), Detroit, Mich.

Considerable experience has been gained in the use of a multiple function artificial heart. Right-sided, left-sided and complete extra-corporeal substitutions have been carried out and some physiological data will be presented.

4. Technique of Producing Mitral Stenosis of Controlled Degree.

Robert G. Ellison, Robert C. Major, Raymond W. Pickering

(by invitation) and Wm. F. Hamilton (by invitation),

Augusta, Ga.

The desirability of a practical technique of creating mitral stenosis for experimental studies has long been recognized. The advances in clinical methods of investigating cardiovascular disturbances and in cardiac surgery during the past ten years make it even more urgent that one study the disturbed dynamics in experimental animals. For years investigators have attempted to develop such a technique, but none has been entirely satisfactory.

Our earlier attempts ended unsuccessfully and the discarded techniques will be briefly described.

In an effort to produce the experimental disease in severe chronic form the ends of the sutures (silver wire encased in nylon tubing to lessen fraying) were drawn out through a cannula whose large, flat head was affixed to the chest wall and whose cardiac end prevented displacement of the heart as the ligatures were tightened. After the animals had recovered from the operation, pressures within the pulmonary artery and vein were recorded with optical manometers through angiostomy cannulas placed upon the vessels at the time of surgery. In some preparations the pulmonary arterial and pulmonary capillary (venous) pressures were studied by the method of cardiac catheterization.

Ligatures were tightened at weekly intervals without opening the thorax; thus varying degrees of stenosis were produced. These animals were studied to elucidate the mechanism of the increased pulmonary vascular resistance associated clinically with mitral stenosis and the mechanism by which blood is shunted away from anoxic lungs.

5. Surgical Approach for Stenotic Lesions of the Semilunar Valves by Excision and Cusp Replacement Under Direct Vision.

Robert S. Litwak (by invitation) and Howard L. Gadboys

(by invitation), Boston, Mass.

The purpose of this study was the development of more satisfactory technics for the relief of stenotic lesions of the semilunar valves. To date, attempts to relieve pulmonary and aortic valvular stenosis have been confined to blind incision and/or dilatation of the valve. Restoration of function, therefore, has been dependent upon the inherent flexibility of the valve. Since the disease process often renders the valve rigid, such procedures may be expected to result in only limited improvement.

It is known that stenotic lesions of the semilunar valves do not evidence themselves clinically until the cross-sectional areas of their ostia are diminished approximately 75%.

Our aim was to resect approximately one-third (one cusp) of the stenosed valve in order to reduce the degree of obstruction, thereby increasing ventricular output. It was deemed essential to obtain this increased output without the production of a regurgitant lesion.

A clamp has been developed which permits resection of one-third of the valve (one cusp) and adjacent vascular wall under direct vision without interruption of the circulation. The basic design of the clamp as modified for pulmonary and aortic cusp resections renders intra-cardiac orientation quite simple. The dog heart has tolerated the clamp well.

Utilizing this instrument, cusp resections of both aortic and pulmonary valves have been carried out in a series of thirty-four animals at this writing. The valves have been reconstituted successfully using both homografts and autografts.

The animals have been scarificed from one day to seven months following operation. The results will be presented.

The possible advantages which may develop from the use of this procedure in clinical surgery will be discussed.

6. Experimental Pulmonary Venous Occlusion.

C. Rollins Hanlon, David Sabiston (by invitation) and

Donald R. Burke (by invitation), St. Louis, Mo.

Ligation of pulmonary veins has been given limited therapeutic trial in patients and in experimental investigations on animals. Total ligation of pulmonary lobar veins is well tolerated, but ligation of the entire venous return from one lung has been reported to cause wet gangrene in patients and a uniformly fatal outcome in experimental animals. The animals were believed to die of shock due to blood loss in the affected lung.

The present experiments involve one stage ligation of all the veins of the left or right lung in dogs. The outcome of these experiments is somewhat at variance with published results. The effect of antibiotic medication in altering the prognosis of such lesions has been investigated. The practical implication of these studies is briefly discussed.