Tuesday Morning, April 28, 1964

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

Grand Ballroom

15. The Experimental Production of Hypertrophic Subaortic Stenosis

J. S. McLaughlin*, A. G. Morrow, and M. J. Buckley*,

Bethesda, Md.

In patients with hypertrophic subaortic stenosis it has been shown that obstruction to left ventricular ejection results from the contraction of an abnormal muscle mass within the outflow tract of the left ventricle. This dynamic obstruction contrasts with the fixed stenotic orifice associated with other forms of aortic stenosis and has not, heretofore, been produced in the experimental animal. Coarctation of the ascending aorta was produced in dogs and, over a period of 4-6 months, resulted in the progressive development of concentric left ventricular hypertrophy. Cardiac catheterizations at this time revealed intraventricular pressure gradients up to 75 mm. Hg which persisted after the aortic obstruction was relieved. In every animal the administration of small doses of isuprel increased the hypertrophic obstruction significantly but it was not altered by the changes in left ventricular flow and volume associated with aortic regurgitation or a subclavian-left atrial shunt. The operative methods utilized in producing experimental hypertrophic subaortic stenosis and physiologic comparisons between this lesion and that encountered in man will be presented.

16. The Fate of the Starr-Edwards Valve in the Aortic Area of Calves

Peter E. Blundell*, and Dwight C. McGoon, Rochester, Minn.

The fate of the Starr-Edwards ball valve in the subcoronary position of calves has been followed for periods up to 8 months. Animals were sacrificed at regular intervals after insertion of the prosthesis, for gross and microscopic study of the operative area. Special note was made of any alterations of blood coagulability or of the presence of infection on the prosthesis. There were no operative deaths during this study. In the absence of infection, fibrin deposition was minimal. During the first few days, a thin layer of fibrin formed over the Teflon on the prosthesis. By the end of 1 week, fibroblasts could be seen invading this material; and 1 week later they were organizing the interstices of the Teflon mesh. During the first month, extensions of fibrin could be seen creeping up the struts of the cage but thus far have not been seen thereafter in this study. In contrast, the presence of infection resulted in severe fibrin deposition beginning after 2 weeks and becoming severe enough to cause marked aortic stenosis and bacterial endocarditis at the end of 8 weeks. There was no significant change in the plasma clotting time or in the prothrombin time during the first 2 postoperative months.

17. A Hinged-Leaflet Valve for Total Replacement of the Human Aortic Valve

Vincent L. Gott*, Ronald L. Daggett*, james D. Whiffen*,

Donald E. Koepke*, and William P. Young*, Madison, Wisc.

Sponsored by Anthony R. Curreri

A new type prosthetic valve has been developed for complete replacement o£ the human aortic valve. The valve consists of a rigid housing of graphite coated Lexan plastic with a central cross strut for the anchoring of a flexible "butterfly-wing" leaflet. This prosthetic valve evolved through many modifications made during the course of 115 canine valve replacements. To date the hinged-leaflet valve has been utilized as a total aortic valve replacement in eight patients at the University of Wisconsin Hospitals. The first placement was 7 months ago, and in those patients catheterized to date none has shown a systolic pressure gradient. Three of the eight patients have died but from causes other than valve malfunction. The hinged-leaflet valve appears to offer several significant advantages over existing prosthetic aortic valves. These advantages include a large I.D./O.D. ratio which eliminates any significant systolic gradient, an extremely low profile (5/16" tall) which permits easier suture and valve placement, and a graphite-heparin coating which significantly reduces the incidence of thrombosis. Also, with the use of a hinged-leaflet as opposed to a caged ball the stress placed on the anchoring sutures is considerably reduced.

18. Homotransplantation and Autotransplantation of a Pulmonary Lobe

Otto Gago*, Emilio Delgado*, Fred Schoenfeld*,

Klaus Ranniger*, Francis L. Archer*, and William E. Adams,

Chicago, Ill.

The feasibility of the transplantation of a lower pulmonary lobe in the human with respiratory insufficiency seems to us greater than the transplantation of the total lung. The surgical technique is easier and less traumatic, avoiding the risk of a pneumonectomy in a patient with severe functional deficit. In order to study this problem, transplantation was done in a group of 20 pairs of nonrelated mongrel dogs, with two teams working simultaneously. Methotrexate in large dose was used postoperatively as an immuno-suppressive drug. Angiographic studies of the pulmonary tree were made at different times following the graft. Oxygen saturation of the pulmonary vein draining the transplanted lobe was also made at different postoperative periods. Open chest biopsies and pathologic findings will be discussed.

19. Replacement of Tracheobronchial Defects with Autogenous Pericardium

Lester R. Bryant*, Lexington, Ky.

Sponsored by Ben Eiseman

The size of the defect following excision of deformities or tumors of the trachea may require the use of a tracheal graft. In this study, free grafts of unsupported autogenous pericardium were used to bridge defects in the tracheobronchial tree of mongrel dogs. In twenty animals, portions of the carina, main stem bronchi, or trachea were excised to produce defects two to five centimeters in length and involving up to two-thirds the circumference of the airway. Circumferential defects of the intra-thoracic trachea were created in another ten animals by excising three to eight cartilaginous rings. Repair was effected by interposition of a tubular pericardia! graft without rigid support of the pericardium. The grafts functioned well in the immediate postoperative period and became airtight in 24 hours. Collapse of the graft with respiratory obstruction did not occur. Four animals died of mediastinal suppuration and severe stenosis developed at the graft site in three dogs with circumferential grafts before a program of bronchoscopic dilatations was begun. The grafts in the remaining animals have functioned satisfactorily for periods up to eight months. The results indicate that pericardium may be used satisfactorily to patch defects and as a tubular substitute when circumferential tracheal resection is required.

20. A New Method for Extensive Resection and Reconstruction of Mediastinal Trachea and its Bifurcation in Man, without Prosthesis or Graft

Hermes C. Grillo*, and Ellen B. Dignan*, Boston, Mass.

Sponsored by J. Gordon Scannell

A new method is presented for extensive resection and reconstruction of the trachea within the thorax, where complex techniques other than direct anastomosis of tracheobronchial tissue so frequently fail. The anatomic basis of the method lies in (a) extension of the limits of mobilization of the trachea and (b) transfer of the cervical trachea into the thorax. In a series of dissections in fresh cadavers, in the age group 55-90, an average of 6.5 cm. of lower trachea was resected and continuity restored directly, without excessive tension. This was accomplished by (1) mobilization of the right hilum, (2) division of the pulmonary ligament, (3) reimplantation of the left main bronchus and (4) pericardial vascular mobilization. Additional length was resected and tracheal continuity restored within the mediastinum by division of the trachea below the cricoid cartilage and downward mobilization of the cervical segment, establishing a cervical tracheostomy. Vascular supply of the transferred segment was maintained. These methods supply a unified approach to wide tracheal resection at any level, transferring any necessary reconstruction into the neck, where complex methods may be applied safely.

21. Pulmonary Surgery in Cystic Fibrosis

Samuel R. Schuster, Harry Shwachman*,

G. B. C. Carris*, and Kon-Taik Khaw*,

Boston, Mass.

The usual cause of death and most serious manifestation of cystic fibrosis is chronic pulmonary infection with resultant bronchiectasis that often progresses toward total lung destruction. In addition to the usual medical therapy, we have utilized limited pulmonary resection in carefully selected patients with evidence of bronchiectasis and or localized lobar collapse as a palliative measure to slow down the unrelenting pulmonary involvement. A review of this series of children with cystic fibrosis undergoing palliative pulmonary resection is presented and demonstrates the effectiveness o£ such surgery in slowing the progress of pulmonary involvement once overt structural changes have occurred. Also demonstrated is the fact that these surgically treated patients, if operated upon early enough, are usually more comfortable and less symptomatic for significantly longer periods of time than those who have not had surgical intervention at this stage in the disease.

22. Direct Sputum Smear for Diagnosis of Pulmonary Histoplasmosis

Leon P. Woods*, Ellis A. Tinsley*, and

Walter L. Diveley, Nashville, Tenn.

In pulmonary histoplasmosis, diagnosis by culture and serologic means has been slow and too often only presumptive. At the R. S. Gass Hospital we have come to accept as routine the success with which pulmonary histoplasmosis is diagnosed from simple sputum smears, and we were quite surprised to find that there has been no emphasis upon this method in the literature. Feeling that this very old and useful diagnostic technique is virtually unknown and unused for this disease, we have analyzed our experience to confirm the accuracy of the method. Of 84 patients seen with pulmonary histoplasmosis since 1960, 54 submitted sputum specimens for direct examination. H. Capsulatum was identified within macrophages, using histologic stains, in 35 of these cases; 88% of these diagnoses were later proven and 12% were presumed correct because both complement fixation and skin test were positive. Smears were not diagnostic in 19 of the54 submitted cases. Cavitary lesions were most often associated with positive sputum smears (70%), while only 50% of the cases with infiltrative lesions were smear positive. Thus % of active pulmonary histoplasmosis cases were diagnosed by direct sputum smear, and false positives did not occur.

23. Surgical Correction of Ruptured Chordae Tendineae

Joe D. Morris, Ralph L. Brandt*, and

David A. Penner*, Ann Arbor, Mich.

Ruptured chordae tendineae has been the mechanism of mitral valve insufficiency in eleven patients put of fifty-two who underwent open operation for correction of pure mitral insufficiency. The diagnosis was made preoperatively in six of these patients on the basis of history and distinguishing physical findings. Only four patients in this series had a history of rheumatic fever while five patients presented a history of coronary artery disease. Trauma and hypertension were thought to be the etiology of the chordae rupture in two cases. A satisfactory surgical correction employing a prosthetic chorda of Teflon cloth has been evolved. The technique permits adjustment of tension on the flail leaflet and preserves an otherwise satisfactory mitral valve. The results of operative correction will be presented. Fabrication of the Teflon prosthesis and appearance of the valve will be shown by a short film strip.

24. Increase in Blood Flow in Experimental Replacement of the Superior Vena Cava

Theodor M. Scheinin*†, and James R. Jude*, baltimore, md.

Sponsored by Alfred Blalock

Early thrombosis has made experimental superior vena caval (SVC) replacement unsatisfactory. Blood flow through the graft is recognized as an important early factor in maintaining patency. This study encompassess such effect by increasing superior caval blood flow by a temporary distal arterio-venous fistula. Studies were performed on 36, 11-16 Kgm mongrel dogs. In the test series, the entire SVC was replaced by a crimped teflon or dacron tube or an autogenous external jugular vein graft. A temporary carotid to external jugular arteriovenous (A-V) fistula was then immediately constructed. This A-V fistula was closed four weeks later. The control series had no A-V fistula. In both groups the azygos vein was not ligated and no anticoagulants employed. The fate of the grafts was determined by repeated cavograms and gross and microscopic studies up to eight months. The patency rate in the test series was 83%. The average follow-up was 5.7 months. There was no instance of late thrombosis or narrowing of any of the grafts. In the control series only 26% remained patent. Stenosis occurred only in this group. Teflon tubes and autogenous vein grafts appeared to be superior to dacron. The temporary distal A-V fistula markedly enhanced persistent patency of all types of grafts.

25. Operations Upon Coronary Arteries Using Absorbable In-traluminal Gelatin Tubes

Walter F. Ballinger II*, Noel Fishman*, and

Rudolph C. Camishion, Philadelphia, Pa.

Operations upon coronary arteries require hypothermia or temporary shunts to protect the myocardium from ischemia. Early thrombosis frequently occurs, with death due to arrhythmias or myocardial infarction. In-traluminal gelatin tubes dilate spastic arteries, provide rigidity to facilitate suturing, allow blood flow to the distal myocardium and dissolve quickly and completely after arterial repair. Fifteen linear arteriotomies and nine transections were performed on the left circumflex coronary artery of 24 normothermic dogs. Repair over a gelatin tube was accomplished without arrhythmias or ischemia. There were 15 long-term survivors, nine with repair of arteriotomies and six with end-to-end anastomoses. Three deaths occurred from thrombosis due to poor intimal apposition, three from atelec-tasis and three from gelatin emboli. This latter complication did not recur once the proper technique of cutting the tube to size was learned. Long-term survivors were sacrificed after three to nine months. A varying degree of late narrowing without myocardial infarction was observed and was due to progressive fibrosis around the suture. Gelatin tubes provide a high rate of immediate successs in experimental operations upon coronary arteries. Long-term patency is related to choice of suture material which will be discussed. A short film strip illustrating this technique will be shown.

26. Metabolism of Vasomotor Agents by the Isolated Perfused Lung

BenEiseman, Lester Bryant*, and Theodore Waltuch*,

Lexington, Ky.

Although primarily considered as an organ devoted to gaseous exchange, the lung also is active in the metabolism of non-gaseous substances. This is a study of metabolic degradation of various vasoactive substances by isolated freshly excised canine lungs aseptically perfused with heparinized blood and oxygenated by mechanical insufflation through the cannulated trachea. Temperature, pH, pO₂, pCO₂, pulmonary artery pressure, pulmonary venous return and airway pressure were monitored during each perfusion. Forty-five technically successful experiments have been performed with a total of 60 loading experiments divided as follows: serotonin, 5 and 10 milligram loads, 19 experiments; histamine, one to ten milligram loads, 35 experiments; nore-pinephrine, 150 micrograms to one milligram loads, six experiments. Serotonin is promptly cleared by the lung with the production of 5-HIAA. The pulmonary blood flow is markedly reduced by this agent and the airway resistance is increased. Histamine produces increased airway resistance and a moderate increase in pulmonary vascular resistance, but it is not metabolized by the lung. Norepinephrine is quickly degraded but it produces little change in pulmonary vascular resistance or airway resistance. The implications of the non-gaseous metabolic properties of the lung during pulmonary by-pass and with the infusion of vasoactive agents are discussed.

27. Pulmonary Artery Bypass: A Simplified Method For Prolonged Support

John Just*, Thomas O'Connor*, Robert Brault*,

and Derward Leplev, Jr., Milwaukee, Wisc.

This study reports the use of a disposable oxygenator without extra-corporeal pumps for use in emergency pulmonary embolectomy or for prolonged pulmonary support. Fifteen dogs were subjected to a small left anterior thoracotomy. A large cannula, attached to the oxygenator, was inserted into the right ventricular outflow tract. The oxygenator was placed at slightly above the level of the heart. The arterial limb was then inserted into the left auricular appendage. The pulmonary artery was clamped and the lungs bypassed for a period of one hour with the heart used as a pump. Normothermia and flows ranging from 45 to 60 milliliters/kilogram of body weight were realized throughout the period of bypass. Blood samples were drawn periodically for gas analysis and plasma hemoglobin. Survivors were observed for neurologic deficit. Our results show that the animals can be so perfused, maintaining normal blood pressure and without development of metabolic acidosis. To date, all animals have survived without sequlae. Plasma hemoglobin levels indicated minimal blood trauma. In a second series of 15 dogs, prolonged support for many hours was carried out with an identical procedure and the results of these studies will be discussed.

†Evarts A. Graham Memorial Traveling Fellow, 1962-63. Present address: Oulun Lääninsairaala, Oulu, Finland

*By Invitation