Tuesday Morning, May 8, 1956

8:30 A.M. Scientific Session: THORACIC SURGICAL FORUM.

15. Introducing a Simple Surgical Method for the Correction of Mitral Regurgitation Using the Finger Ring Valve Elevator.

Aran S. Johnson (by invitation). Sponsored by William M. Tuttle,

Detroit, Mich.

A careful examination of over 100 necropsy specimens of hearts with residual rheumatic mitral valvular lesions reveals the following pathology. In 70 per cent of the hearts with mixed mitral stenosis and regurgitation, or pure mitral regurgitation, the regurgitant defect was found constantly in the posterior leaflet of the mitral valve. With this nearly constant pathological finding in mind, a simple surgical technique was developed to correct the existing defects in the posterior mitral leaflets. With the aid of the Finger Ring Valve Elevator, the posterior wall of the left atrium is inyaginated and sutured over the anterior surface of the posterior leaflet of the mitral valve. This maneuver corrects the existing valvular defect satisfactorily.

Clinical cases of mitral regurgitation treated surgically will be presented and discussed.

16. Further Experiences with the Method of Controlled Unilateral Pulmonary Artery Occlusion in the Study of Lung Function.

Paul Nemir, Jr., H. H. Stone (by invitation), H. R. Hawthorne (by invitation)

and T. N. Mackrell (by invitation), Philadelphia, Pa.

In 1953 we presented a preliminary report on the method of unilateral pulmonary artery occlusion for the study of lung function in patients who were candidates for pulmonary resection. Since that time, the method has been employed in several other clinics and the number of patients now studied has become sufficiently large to allow significant conclusions. Study has now been carried out by us on approximately 35 patients. With our continuing experience, refinements in technique have occurred. Moreover, analysis of the data has yielded information which has allowed us to concentrate on the observations which are the most significant. Special triple lumen balloon-tipped cardiac catheters have allowed simultaneous pressures and gas analyses at various levels of the pulmonary system and have allowed a study of bronchial artery blood flow in normal and diseased lungs. Analysis of the results in this larger group of patients has confirmed the earlier observations with respect to the relationship between sustained elevation of pulmonary artery pressure following occlusion and occurrence of dyspnea following resection. There is evidence that study of the pressures and blood gases distal to the occluding balloon may give similar important information on resection tolerance and on bronchial artery blood flow in certain disease states. Responsiveness of the pulmonary circulation to various drugs has been demonstrated.

17. Oxygen Availability to the Brain During Inflow Occlusion of the Heart in Normothermia and Hypothermia.

Samuel Kaplan (by invitation), Edward C. Matthews (by invitation),

Loius Schwab (by invitation) and Leland C. Clark (by invitation).

Sponsored by James A. Helmsworth, Cincinnati, Ohio

Many of the surgical techniques used in the therapy of intracardiac anomalies under direct vision depend on the application of either one or the other of two principles: the reduced metabolism associated with hypothermia, or a low flow rate (azygos principle). These two principles were tested by measuring oxygen available to the brain (tension) by the polarographic technique.

Dogs were prepared by placing a polarograph cathode in the brain. After the cathode had "healed", continuous records of brain oxygen availability were obtained at normal temperatures before, during, and after the occlusion of the inferior vena cava and the superior vena cava above the azygos vein. In vivo calibration of the cathode was obtained by allowing the animals to breathe 100%, 20%, 9.8% and 4.8% oxygen while the circulation was intact. Galvonometer readings obtained during the venous occlusion were the same as those obtained during the breathing of about 10% oxygen.

Further records were obtained after the animals' temperature had been reduced to 26° - 28° C. by extracorporeal cooling. After complete inflow venous occlusion, there was a precipitous fall of the oxygen available to the brain, followed by a return to pre-occlusion levels after the circulation had been re-established. In vivo calibration showed that in hypothermia, the measurable oxygen available to the brain during venous occlusion was the same as while breathing less than 4.8% oxygen.

These studies indicate that there is a rapid and significant reduction of oxygen available to the brain during reduced flow rates as in the "azygos principle" and is exaggerated in hypothermia with complete inflow occlusion.

18. The Effect of Somatotrophin on Ventricular Fibrillation of Arterioclusive and Hypothermic Origin.

David H. Watkins (by invitation), S. Rothman (by invitation), Arthur

E. Prevedel (by invitation) and Gordon A. Munro (by invitation).

Sponsored by William B. Condon, Denver, Colorado

Bovine Somatotrophin was administered to a series of dogs prior to the attempted induction of ventricular fibrillation by right ventriculotomy under hypothermic conditions or by one-stage coronary artery ligation in normothermic animals. Under control conditions such hearts fibrillate readily. However, those animals which had been premedicated were remarkably resistant to fibrillogenic stimuli.

The hypothermic heart has been defibrillated in other ways: prolonged massage, electric current, acetylcholine, potassium chloride and infiltration of the sinoauricular node. Thus, the trigger mechanisms inducing ventricular fibrillation apparently may be modified by several modalities.

The protection by pre-treatment with Somatotrophin of dogs which are subsequently exposed to stimuli usually provocative of ventricular fibrillation leads us to believe that the mechanisms producing fibrillation may be modified on the metabolic level. The early local metabolic derangements produced by myocardial infarction are of special interest because of the production of ventricular fibrillation, a frequent cause of early mortality. Similar relationships exist with reference to cardiac arrest. Conditions known to provoke cardiac arrest conceivably alter membrane permeability and the intrinsic cellular metabolism of the myocardium.

19. Physiologic Responses in Man to Total Body Perfusion for Open Intracardiac Surgery.

Richard A. DeWall (by invitation) and Raymond C. Read (by invitation),

Minneapolis, Minn.

In this clinic a simple disposable artificial oxygenator is being employed together with a standard pump for direct vision intracardiac reparative surgery. To date, fifty patients ranging in age from 16 weeks to 37 years have had intervals of total cardiac and pulmonary by-pass at normal body temperatures for intervals up to 50 minutes at various rates of perfusion utilizing this oxygenator.

Detailed biochemical data has been obtained in these patients before, during and after the by-pass interval in regard to their physiologic response to this total body perfusion. These data will be presented.

20. A Method for Controlled Cardiac Arrest as an Adjunct to Open Heart Surgery.

W. Glenn Young (by invitation), Will C. Sealy,

Ivan W. Brown, Jr. (by invitation), Wilmer C. Hewitt, Jr. (by invitation),

Henry A. Callaway, Jr. (by invitation), Doris H. Merritt (by invitation) and

Jerome S. Harris (by invitation), Durham, N. C.

Induced cardiac arrest would seem to be desirable as an adjunct to intracardiac surgery. Since no work is performed during standstill, cardiac metabolism theoretically would be so decreased that long periods of aortic and coronary artery occlusion would be possible. It also has the advantage of preventing air embolism, diminishing blood loss, and providing a motionless operative field.

In this study a series of experiments with the Langendorf perfusion apparatus were performed to determine the best agents for causing rapidly reversible cardio-plegia. Among the substances tested alone or in various combinations were potassium, magnesium, antihistaminic drugs, cholinergic drugs and barbiturates. A solution containing magnesium sulphate, potassium citrate, and prostigmine was found to be satisfactory. This cardioplegic agent has been used in a series of acute and survival experiments on both hypothermic and normothermic dogs. The solution was injected into the coronary arteries through the occluded aorta until cardiac contractions stopped. Then a right ventriculotomy was made and repaired. This was followed by perfusion of the coronary vascular tree until normal cardiac activity was resumed. In acute experiments, the cardioplegic drug was washed out with an oxygenated balanced electrolyte solution. Normal cardiac activity in survival experiments was restored by perfusing the coronaries with oxygenated blood. In the latter group, the systemic circulation was maintained by a simple oxygenating system and a Sigmamotor pump.

21. The Neutralization of Heparin by Protamine in Extracorporeal Circulation.

Mr. Raymond Hurt, Traveling Fellow of the Association (by invitation),

London, England. Sponsored by Frank L. Gerbode.

At the conclusion of heart-lung bypass with an extracorporeal circulation, it is necessary to neutralize the anticoagulant action of the heparin with protamine. This protamine, in addition to neutralizing the heparin, has three other effects if given in excess. It will cause a shock-like syndrome (characterized by a fall in blood pressure and a bradycardia), a haemorrhagic tendency, and thrombocytopenia. A method of protamine titration has been developed in order to estimate the correct dose and reduce the severity of these undesired side-effects.

Data will be presented which demonstrate that the severity of the shock-like syndrome that occurs following the administration of protamine is much greater if the blood has previously been passed through an extra-corporeal pump.

22. Experience with a Disposable, Artificial Lung.

D. B. Effler, W. J. Kolff (by invitation), L. K. Groves (by inviattion),

F. M. Sones, Jr. (by invitation) and G. Peereboom (by invitation,)

Cleveland, Ohio

Acceptance of the azygous flow principle and cross-circulation procedures in open heart surgery have emphasized the need for a safe and practical blood oxy-genator. Research and clinical experience with an artificial kidney (Kolff) led to the development of an artificial lung. The Kolff lung employs the membrane principle of oxygenation. This artificial lung, using polyethylene tubing (.001 inch thick) permits ready exchange of carbon dioxide and oxygen without bubbles, foam or alteration in the clotting mechanism. The present apparatus will oxygenate 300 cc. of venous blood per minute up to 95% saturation. In addition to these features, the artificial lung is disposable and should be relatively cheap to manufacture.

Experience in over one hundred dog operations has been encouraging. Open heart surgery in dogs (10 kilo.) is permitted by utilization of these disposable prostheses; with the venae cavae occluded, auricular and ventricular septal defects may be created and sutured under direct vision. Neither hypothermia nor supplemental drugs (e.g., chlorpromazine) are used in adjunct. Description of techniques and recovery rates will be presented.

The schedule of initial experimental work with the Kolff lung will be completed in the very near future. The authors anticipate clinical application of this simple blood oxygenator. A report of all clinical experience will be included.

23. An Artificial Lung Dependent upon Diffusion of Oxygen and Carbon Dioxide Through Plastic Membranes.

George H. A. Clowes, Jr., Amos L. Hopkins (by invitation) and

William E. Neville (by invitation), Cleveland, Ohio

A new type of blood oxygenator has been developed to prevent direct exposure of blood to gaseous oxygen and the formation of foam. We wish to present this apparatus, the preliminary work on evaluating the characteristics of thin plastic membranes, and the results of perfusions employing this oxygenator.

Sixteen varieties of plastic films ranging in thickness from .0004 to .003 inches were tested to determine their capacities of oxygen transmission directly to venous blood. Of these ethyl cellulose and polyethylene have proven to be the best.

Using these films, an apparatus has been constructed to permit blood to flow in a very thin layer between them with oxygen circulating outside the plastic. At the same time an effort has been made to make the apparatus as efficient as possible and to minimize the amount of blood held within it. In operation this device transmits oxygen to flowing blood in quantities of up to 80% of the maximum calculated value for a given membrane and surface area. A unit capable of oxygenating 1,000 cc. of blood per minute holds approximately 650 cc.

Recovery of dogs perfused up to one hour and the absence of electroencephalographic depression suggest that embolization and other untoward changes in blood elements are not taking place.

24. Extracorporeal Circulation for Open Heart Surgery.

Russell M. Nelson (by invitation), Hans H. Hecht (by invitation),

Richard W. Hardy (by invitation) and Joe Burge (by invitation),

Salt Lake City, Utah

An apparatus has been developed for extracorporeal circulation permitting open heart surgery in a dry field. It has been employed successfully in laboratory and clinical work. It consists of a Sigmamotor pump and a bubble-oxygenating device consisting of two concentric lucite plastic cylinders. Oxygenation and elimination of carbon dioxide are accomplished in the center bubbling chamber. The bubbles are eliminated by contact with stainless steel mesh coated with antifoam. The oxygenated blood is then collected in the outer reservoir chamber and returned. Blood aspirated from the cardiotomy incision is returned. The entire apparatus is sterilized by autoclaving.

With total by-pass of the heart and lungs for 30 minutes or more, long incisions have been made into the right ventricle and/or the right atrium in twelve dogs with ten surviving the procedure. One died of an error in anesthesia technique, and one of the first dogs died of hemorrhage. Since the substitution of plastic for glass in the oxygenating chamber, no further wound oozing has been observed.

Measurements of oxygen, carbon dioxide and plasma hemoglobin concentrations have all been within satisfactory limits. pH determinations at first showed a rise during perfusion; this now being controlled by the addition of 5% CO₂ to the gas mixture. Pulse pressure curves and electrocardiographix tracings have been monitored throughout each experiment. Flow rates have averaged 20 to 30 cc/kg/min.

Brief reference to clinical application will be presented.

25. A Mechanical Pump-Oxygenator for Direct Vision Repair of Atrial Septal Defects.

Bernard S. Levowitz (by invitation), Melvin M. Newman, Jackson H.

Stuckey (by invitation), Marie C. Kernan (by invitation), Harry

N. Iticovici (by invitation) and Clarence Dennis, Brooklyn, N. Y.

A simplified mechanical pump-oxygenator has been developed in this laboratory which permits a direct-vision approach to infcracardiac defects with relative safety. The present communication describes this apparatus and its application in the experimental creation and repair of atrial septal defects. The heart and lungs were totally bypassed in 31 dogs ranging in weight from 10 to 35 kilograms for intervals of 10 to 63 minutes. During this period atrial septal defects from 1.5 centimeters to 3 centimeters were made and repaired in a single stage. Twenty-two dogs were long term survivors.

The causes of death were: air embolism, 3 dogs; uncontrollable bleeding, two dogs; dissecting aneurysm of thoracic aorta, one dog; technical error, one dog; undetermined causes, two. Techniques for avoiding the major hazards have been studied. The physiologic alterations in acid-base balance, oxygen transport, and protein fractions of the blood have been determined in detail during each perfusion. Similarly, changes in the clotting mechanism have been followed and will be presented.

The results of a successful clinical application of this apparatus to a case of a large foramen ovale-septum secundum defect in an 18 year old female are included in this report.

26. Elimination and Transport of Mucus in the Lung: An Experimental Study in the Dog.

Edward G. Huppler (by invitation), O. Theron Clagett and

John H. Grindlay (by invitation), Rochester, Minn.

A study was undertaken on dogs in an attempt to answer the following questions: 1. Can mucus be absorbed in the lobule of the lung when the proximal bronchus is transected and the ends closed? 2. Can a bronchial cyst be produced by isolating a segment of bronchus but leaving the blood and nerve supply intact?

In one group of dogs the right upper lobe bronchus was transected and both ends of the divided bronchus were closed by suture. In these animals mucus secreted into the right upper lobe bronchus could not be removed through the trachea by coughing or movement by the cilia but it could flow into the alveoli.

In a second group of animals, following right upper lobe bronchus transection, the first four secondary bronchi were doubly ligated, thus producing an isolated segment of bronchus. Mucus secreted into this segment could not be removed through the trachea nor could it flow into the alveoli. The secondary bronchi distal to this isolated segment were not ligated; hence, mucus secreted into the primary bronchus distal to the isolated segment could flow into the alveoli but not into the trachea.

An animal from each series was sacrificed at intervals varying from 2 to 48 weeks after operation. In both groups of animals endobronchial mucus dilated all portions of the bronchial tree but a bronchial cyst was not produced. In animals sacrificed 16 to 48 weeks after operation the degree of dilatation of the bronchial tree and the quantity of mucus in the lung lobule were decreased.

The findings are discussed in relation to cases of traumatic rupture of a bronchus and in relation to the various theories of etiology of bronchogenic cysts.

27. Surgical Treatment of Ventricular Septal Defects: A Method Utilizing Selective Coronary Perfusion and Hypothermia.

John B. Grow, Charles V. Demong (by invitation) and Charles R.

Hawes (by invitation), Denver, Colo.

The closure of interatrial septal defects utilizing hypothermia and cardiac occlusion has proved to be a successful procedure. Study of ventricular septal defects in museum specimens and at the Children's Hospital autopsy table indicates that such defects can be closed by suture technique but not in the relatively short periods of occlusion thought safe and proved applicable to the atrial septal defects.

Failure of laboratory animals to survive closure of septal defects under hypothermia and cardiac occlusion results from: (1) Ventricular fibrillation; (2) coronary air embolism; (3) uncontrollable capillary bleeding following surgery. A combination of perfusion of the coronary arteries with oxygenated blood as suggested by Shumway et al and sino-atrial node blockade as described by Shumacher offers an uncomplicated method of increasing the safe limits of cardiac occlusion to at least 20 minutes. This is considered sufficient for closure of ventricular septal defects.

A simplification of this technique has been devised in which the coronary arteries are perfused by syringe with oxygenater donor blood from a reservoir, thereby obviating both mechanical pump and oxygenator.

Successful closure of ventricular septal defects with survival of four of the five patients to date (December 1, 1955) suggests that this method may be useful in the surgical repair of intracardiac defects which necessitate more than five minutes of occlusion time. Details of technique, summaries of clinical cases, and postoperative management with particular regard to hematologic changes will be discussed.

28. A Report on Heterologous Vascular Shunts (Bovine Brachiocephalic) in Experimental Aortic Arch Resection.

Ralph D. Alley, William H. Sewell (by invitation), Allan Stranahan,

Harvey W. Kausel (by invitation), Thomas S. Reeve (by invitation) and

Alan S. Peck (by invitation), Albany, N. Y.

Surgical resection of the aortic arch poses two major unsolved problems: (a) a practical method for by-passing the aortic arch during the period of occlusion, and (b) a suitable graft for its reconstruction. This report concerns progress in the solution of the first of these problems.

Since our preliminary report of a heterograft external shunt for by-passing the aortic arch (1954), further technical refinements have reduced the operative mortality in experimental aortic arch resection to negligible levels. In brief, the shunt is fashioned from the bovine brachiocephalic trunk which is oversewn as a manifold, preserving its carotid and subclavian branches as limbs of the shunt.

The features which recommend it are: (a) availability of the material; (b) its physiologic elastic properties; (c) adequate caliber; (d) absence of thrombosis; (e) mobility in the operative field; (f) basic simplicity of application with no premium on speed or critical dexterous maneuver. Although more rapid methods for experimental resection of the dog's normal aortic arch have been described, the advantages of the bovine brachiocephalic shunt would appear to offer greater promise of adaptability to the unpredictable operative problems presented by clinical vascular pathology.

Because others have reported difficulty in obtaining intact specimens, an expeditious method for procuring bovine brachiocephalic arteries will be described and illustrated by a short motion picture. The technique ensures intact subclavian and carotid branches of adequate length without mutilating the carcass or otherwise hampering the work of the abattoire.

29. Arterial Homograft Substitution and Bypass in Superior Vena Caval Obstruction.

John F. Higginson, Portland, Ore.

Superior vena caval obstruction syndrome is usually the result of malignant tumors invading the superior vena cava and/or the innominate veins. Ordinarily extirpative treatment is not possible. Occasionally, however, the tumor is benign or, if malignant, is resectable. Even if not resectable, relief of the superior vena caval obstruction would be most desirable since the symptoms are extremely distressing and often the immediate cause of death.

The use of arterial homograft substitution or bypass in these situations is one means of effectively solving the problem as is the reverse of the earlier treatment of arterial defects by the use of segments of veins.

Three cases will be presented. In one an aortic-iliac bifurcation homograft was substituted for the resected innominate veins and superior vena cava. In two a bypass arterial homograft shunt was established between the left innominate vein and the right auricular appendage.

30. Experiments with Substitute Esophagus.

Laurence Rubenstein (by invitation), Chicago, Ill.

Much work has been done in the patient in an attempt to alleviate obstructive lesions of the esophagus. The problem in most cases has been that either forbiddingly hazardous operations or inadequate replacements of portions of the esophagus have yielded relatively unsatisfactory results. In the past few years, we have attempted to remove portions of the esophagus in dogs and to replace them with various substitutes, including living tissue as well as prostheses. Although we have been successful in replacing segments of esophagus, a serious complication has been stricture formation with interference of the propulsion of food through the esophagus. In recent experiments, using new type prostheses which can be easily sutured, we have been successful in reconstructing esophageal defects with a minimum of disturbance to the physiological mechanism of swallowing. This work has been encouraging enough so that we feel justified in translating our results to humans.

Various portions of the esophagus have been removed and replaced with this prosthesis. The main advantages are: (1) The ease and rapidity with which it may be inserted; (2) the firm yet yielding nature of the material; (3) the absence of postoperative strictures in the area of surgical intervention when the prosthesis is left in place.