Wednesday Afternoon, April 18, 1962

2:00 P.M. Scientific Session: THORACIC SURGERY FORUM

Khorassan Room

38. The Surgical Significance of the Fibrous Skeleton of the Heart

Jacob Zimmerman (by invitation), and

Charles P. Bailey, New York, N. Y.

The majority of surgical heart lesions, congenital as well as acquired, are related anatomically to the fibrous structures at the base of the heart which have, in a vaguely denned sense, been referred to as its "fibrous skeleton." Standard descriptions of these structures make no attempt at defining them either in relation to function or with respect to their substantiality as anchorage for surgical sutures. The fibrous skeleton of the heart, which is here defined as those structures at its base which are densely collagenous and comparatively stationary relative to the myocardium and valve leaflets, was carefully identified anatomically in this study by: (a) Gross dissection of fresh human hearts, (b) Continuous serial histological sections through the base of the heart with histological identification of the structures and three-dimensional model reconstruction. (A specially adapted technique for mounting the sections in plastic will be published separately.) A detailed description of these collagenous structures will be presented with special stress on their anatomical relationship to valve leaflets and the conduction system. The profound influence of this more accurate appreciation of cardiac anatomy on the concepts underlying the surgical treatment of mitral and aortic valve diseases will also be discussed

39. Replacement of the Canine Pulmonary Valve and Pulmonary Artery with a Graphite Coated Valve Prosthesis

Vincent L. Gott, Ronald L. Daggett,

William P. Young, Donald E. Koepke (all by invitation), and

Anthony R. Currerl, Madison, Wis.

At the present time there appears to be a significant need for a pulmonary artery-pulmonary valve prosthesis for clinical application. Such a prosthetic unit would permit a more satisfactory surgical repair in patients with tetralogy of Fallot, transposition of the great vessels, isolated pulmonary valve insufficiency and truncus arteriosus We therefore have been experimenting with a complete pulmonary artery-pulmonary valve prosthetic unit in the canine heart. The artificial valve is a flap valve constructed of a rigid plastic housing and a flexible butterfly wing leaflet. This valve unit is placed inside a teflon fabric graft which serves as the pulmonary artery replacement. The complete artery-valve unit except for the flexible leaflet is coated with colloidal graphite, for previous work from this laboratory has shown that this type of coating significantly reduces clotting on a plastic prosthesis. It was felt that the experimental placement of this artificial valve in the low-velocity pulmonary arterial circuit would also serve as a severe clotting test for this type of valve unit. To date the pulmonary artery and pulmonary valve have been replaced in 20 dogs. Eleven dogs died between the 5th and 12th day after surgery, usually as a result of postoperative hemorrhage or pneumonia. Clotting was not a significant problem in these early deaths. Six of the dogs now survive one to five months after surgery and in most of these animals the valve is known to be functioning as determined by auscultation, cardiac catheterization and exploratory thoracotomy. It is hoped that with continued modification and improvement of this prosthetic unit, clinical application may be possible.

40. Dynamics of Pulmonary Outflow Patches

John R. Derrick, Thomas Miller, and Taylor Smith

(all by invitation), Galveston, Tex.

Sponsored by Albert W. Harrison, Galveston, Tex.

Purpose: Several series of experiments were performed to investigate the limitations and cardiodynamics of patches placed in the pulmonary outflow tract and over the pulmonary valve in dogs. Methods: Series 1. Teflon patches of varying size were placed over different sized defects in the pulmonary outflow tract. The patch and defect surface area were correlated with the dog weight and cardiac size and with the cardiac function pre and post-operatively by employing pressure and flow determinations. Series 2. Similar investigation was carried out with patches over the pulmonary valve. Series 3. Gineradiography of radiopaque patches in place in the right ventricle and over the pulmonary valve was carried out, and the findings correlated with the cardiac function studies. Series 4. Radiopaque sutures were placed in the pulmonary outflow tract and across the pulmonary valve and cineradiography was performed to demonstrate lines of stress and direction of myocardial contraction Results-From Series 1 and 2, we were able to establish the correlation between the onset of failure and the size patch and amount of myocardium that can be removed from the pulmonary outflow tract. From Series 3 and 4, we were able to demonstrate by cineradiography the mechanical stresses placed on a patch in the pulmonary outflow tract. Discussion: The authors will discuss the application of their findings to the use of patches in the correction of pulmonary stenosis. A movie will be shown to demonstrate the cineradiographic findings.

41. Experimental Production and Study of Left Ventricular Aneurysm

K. Tyson (by invitation), I. Mandelbaum (by invitation),

and H. B. Shumacker, Jr., Indianapolis, Ind.

Left ventricular aneurysms have been produced acutely and chronically in dogs by suturing to the ventricular wall pouches of teflon or homologous aorta and removing the intervening ventricular wall Paradoxical filling of aortic homograft aneurysms is evident from gross observation and cineangiographic study. The adverse effect of chronic aneurysms has been demonstrated by cardiac enlargement, elevation of left atrial pressure and by decreased left ventricular function curves. Left ventricular function studies carried out after producing acutely homograft aneurysms show depression as compared with measurements made with the aneurysm clamped off. The same is true of the less expansile teflon aneurysms when ventricular cavity-aneurysm exchange is assisted by gentle manual compression during diastole. Left ventricular function does not seem to be depressed when the ventricular size is acutely enlarged by inserting a patch graft in a vertical incision, the measurements being the same with the patch in place as with the incision closed. The studies carried out show that aneurysms have an adverse effect upon left ventricular function .and that this is due in part at least to paradoxical filling. As yet they offer no demonstrable support for decreased function as the result of increased ventricular diameter (LaPlace's law).

42. Post-Stenotic Dilatation: Confirmation of an Old Hypothesis by a New Method

John L. Kline, Jose L. Gimenez, and Roger Maloney

(all by invitation), Philadelphia, Pa.

Sponsored by George P. Rosemond, Philadelphia, Pa.

The exact hemodynamics which produce the phenomenon of post-stenotic dilatation remain obscure despite considerable work by a few investigators over the past half-century. We propose to show by a totally new method and employing growing pigs rather than static glassware or tubing, that the theory of post-stenotic blood stream turbulence is in all likelihood correct. The weanling pig is an extraordinarily hardy animal which can survive multiple pre- and post-operative studies, and also which can increase tenfold in weight within 5 months. In addition we have thus produced considerable post-stenotic delatation of the aorta and of the right and left outflow tracts of the heart in a brief time. Utilizing high-speed cineangiography and by a new technique of droplet injection of radiopaque dye, we have demonstrated that there is indeed a whirlpool of turbulence within the post-stenotic segment. By means of a Vanguard Motion Analyzer the kinetic energy expended in a lateral direction of such droplets can be computed in terms of the velocity index If a constant bombardment of the vascular wall persists - in the growing animal, the kinetic energy expended will alone produce post-stenotic dilatation.

43. Experimental Cardiac Surgery Under High Atmospheric Pressure

N. G. Meyne (Evarts A. Graham Memorial Traveling Fellow

1958-59), M. E. Sluijter, and I. Boerema (all by invitation),

Amsterdam, Netherlands.

In 1956 Boerema introduced the idea of the use of oxygen under high atmospheric pressure as an aid to cardiac surgery. By cooling the metabolism of the tissues is diminished and at the same time the amount of physically dissolved oxygen can be increased by ventilation with oxygen at 3 atm in a high pressure chamber. 35 Dogs were cooled by surface cooling to 19-23°C; inflow occlusion and atriotomy were performed for 30-20 minutes; during a part of the procedure the animals were ventilated with oxygen at 3 atm in a high pressure chamber. In 20 control animals similar experiments were carried out at normal pressure. In the last part of the series all high pressure animals survived the experiment and 86% were long term survivors, without abnormalities on subsequent histological examination. Advantages of the high atmospheric pressure were found in less potassium shift, less rise in hemoglobin concentration and hematocrit, compared to the normal pressure group, immediately after release of the flow. During the rewarming phase the drop in CO2-combining power was very slight and less than in the control series. When ventricular fibrillation occurs under high atmospheric pressure, defibrillation is extremely easy and frequently spontaneous defibrillation occurs during manual massage; ventricular fibrillation did not occur in the cooling period.

44. Hyperbaric Oxygenation in Vascular Collapse

Safuk Attar (by invitation), William G. Esmond

(by invitation), and R. Adams Cowley, Baltimore, Md.

A standard preparation of vascular collapse was developed by bleeding dogs to a mean arterial pressure of 30 mm.Hg and maintaining this pressure for 2 ½hours. At the end of this period the shed blood was reinfused intravenously. Mortality in a series of 30 dogs treated in this manner was 83%. In a second series, 11 dogs were bled in an identical manner and their pressure stabilized at 30 mm Hg for 30 minutes, after which they were introduced individually into a pressure chamber where pure oxygen was introduced until a pressure of three atmospheres absolute was realized. The dogs were maintained at this level for two hours after which the pressure was reduced slowly to one atmosphere and their shed blood was reinfused. Mortality in this group was reduced to 36%. The significant reduction in mortality observed in the second series is believed due to improved tissue oxygenation due to greatly increased oxygen transport in simple physical solution in the blood in addition to oxygen transport by hemoglobin.

45. Preservation of the Canine Lung

David A. Blumenstock, john A. Collins, and

Herbert B. Hechtman (all by invitation), Cooperstown, N.Y.

Sponsored by Robert H. Wylie, New York, N.Y.

Preyious studies in the laboratory have shown that homografts of the lung in dogs can survive extended periods of time if Methotrexate is given to the recipient animal. Most homografts survive more than a month and several have survived over six months. This provides a homo-graft system, which has been used to test various methods of preserving the lung outside of the body. A series of ten unrelated animal pairs have been subjected to orthotopic homotransplantation of the left lung. In each case the donor lung was stored in vitro 18 to 24 hours before placement in the recipient animal. The lung was stored at 4°C and was ventilated with room air after the blood in the pulmonary vessels had been replaced by saline, dextran, or serum. When saline or dextran was used death of the transplant occurred during the first two weeks or the transplant survived but showed nearly complete fibrosis. In one lung treated with serum some granulomas were seen at biopsy 56 days after transplantation, but the alveoli and vessels were normal. The present series indicates that the lung can be successfully stored outside of the body for 18 hours. Further elaboration of technique and pulmonary function studies will be reported.

46. An Approach to Extracorporeal Surgery of the Heart

Edward J. Hurley, Eugene Dong, Jr., Richard R. Lower

(all by invitation), and Norman E. Shumway, Palo Alto, Calif.

There are many cardiac diseases which theoretically could be best treated by homotransplantation or by total removal of the heart and replacement after corrective surgery. While homograft rejection has no immediate solution, it is feasible to consider that such complex problems as transposition of the great vessels might be treated by removing the heart, performing corrective surgery leisurely in a bloodless field, and then replacing the heart. Experiments were performed in dogs to develop a method for successful isotopic replacement of the totally excised heart and to study the physiological effects of complete cardiac denervation. Method: With peripheral venous cannulation and cardiopulmonary bypass, the heart is excised and immediately placed in normal saline at 0° to 5°C. Replantation of the heart is accomplished by simple suture. A movie will be shown depicting the surgical method. Results: Six dogs are alive and well one to six months postoperatively. The longest period of extracorporeal displacement of the heart was two hours, although seven hours was attained in homograft experiments. The safe period of cardiopulmonary bypass appears more restrictive of what may be done in the way of extracorporeal cardiac surgery than the duration of cardiac anoxia. Physiological studies reveal no important untoward effects either from total cardiac denervation or from the prolonged period of myocardial anoxia.

47. Absorption of Hemopericardium

John L. Wilson, Beirut, Lebanon

The mechanism and rate of absorption of whole blood from the pericardium in dogs is investigated by use of red cells tagged with Cr⁵¹ Observations are made on (1) absorption of a small (physiologically insignificant) volume of blood and (2) absorption of a large hemopericardium. About 20 ml. of tagged blood is injected intrapericardially in splenectomized dogs. Approximately 30% of the tagged cells appear in the circulation within 4 days. Pericardiotomy on the 5th day invariably shows complete absorption of the blood Features of absorption of hemo-pericardium sufficiently large to produce mild tamponade will be described for comparison. Absorption of hemothorax has been shown to be rapid and complete in dogs with 60-70% of red cells migrating from pleural space into general circulation (Wilson, J L., et al. The absorption of blood from pleural space. Surgery 48:766,1960). Reasons for differences in absorption of red cells from pleura and pericardium will be discussed briefly. Although hemopericardium is a frequent sequel to trauma or surgery, the capacity of the pericardial sac to absorb blood has not been studied previously. Hemopericardium will be better understood and management may possibly be improved when the dynamics of blood absorption from pericardium are elucidated.

48. Carbon Dioxide Pneumomediastinography as an Aid in Evaluation of the Resectability of Bronchogenic Carcinoma

Phillip M. Ikins, Alfred S. Berne,

Clifford J. Straehley, Jr. (all by invitation), and

Walter F. Bugden, Syracuse, N.Y.

Our primary interest has been in the development of a technique for the delineation of structures of the mediastinum by introducing carbon dioxide via a cannula placed in a paratracheal or subcarinal position at the time of scalene node exploration. It adds no more than an additional twenty minutes to scalene lymph node exploration. (5). Probably its greatest value lies in the fact that it does not involve another procedure. It is merely an extension of a well known and accepted technique. The failure of other methods of pneumomediastinography is due to the fact that they always involved the addition of another procedure and/or the gas was not introduced directly into the site of primary concern. Thus far, we have had experience with 30 pneumomediastinograms, performed at the time of scalene lymph node exploration and their subsequent anatomic evaluation at the time of thoracotomy. In addition to indicating criteria of absolute contraindication to resection, the dissection of carbon dioxide has, on three occasions, indicated resectability in cases that would have otherwise appeared radiologically inoperable. We have interesting photographic reproductions of Xrays which clearly define the dissection pattern of carbon dioxide in the mediastinum. The reason for the scant illustrative material in the literature of pneumomediastinography, in the past, is the poor definition of structures afforded by these other techniques.

49. Upper Hemi-Body Infusion with Alkylating Agents for Advanced Lung Cancer

H. F. Rheinlander, H. H. Miller, Ross B. Moquin

(all by invitation), and R. A. Deterlino, Jr.,

Boston, Mass.

In evaluating a technique for safely increasing the dosage of alkylating agent delivered to tumors in the upper half of the body, dogs were subjected to thoractomy, the lower thoracic aorta, and internal mammary vessels were temporarily occluded and otherwise lethal doses of nitrogen mustard (1.2 mgm./Kg.) were rapidly injected into a neck vein. Bone marrow and peripheral blood studies were carried out. Encouraged by the successful animal studies, a group of patients with lung cancer found unresectable at thoracotomy were subjected to upper body perfusion using this technique. Another group of patients with obviously inoperable lung cancer have been similarly treated with 1.2 mgm/Kg. of chlorimine mustard but had their aortas occluded by an intraluminal balloon and superficial vessels occluded by an abdominal tourniquet. Results of therapy include shrinkage of tumor, prompt alleviation of bone pain, disappearance of effusion, loss of cough, cessation of hemoptysis and improvement of central nervous system symptoms. Upper body bone marrow is severely damaged by this dosage of alkylating agent but lower body bone marrow is protected and provides adequate production of peripheral blood elements. The neurotoxicity encountered with nitrogen mustard appears to have been overcome by the substitution of chlorimine mustard.