Wednesday Morning, March 31, 1965

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

International Room

31. The Immediate and Long-term Physiologic Function of Bilateral Re-implanted Lungs

L. Penfield Faber*, Alceu L. Scaffa Pedreira*,

Paul H. Pevsner*, and Edward J. Beattie, Jr.,

Chicago, Ill.

Conclusive evidence that the acutely re-implanted dennervated lung will sustain life is lacking. Bilateral lung re-implantations seemingly without time for nerve regeneration are hereby reported. A series of 10 dogs underwent right lung re-implantation. Seven days later left lung re-implantation was performed. Four dogs surviving bilateral lung re-implantation are alive at 9, 6, 2, and 2 months respectively. A control group of 7 dogs underwent right hilar stripping followed in one week by left hilar stripping. Four dogs survived this procedure and were sacrificed after 3 months. All dogs were studied by cardiac catheterization, bronchospirometry, and measurement of lung compliance at varying post-operative intervals. Cardiac output, pulmonary artery pressure and pulmonary resistance and their response to O%was determined. Ventilatory response to hypercapnia and anoxia was measured. Lung biopsies were obtained from all dogs. The dogs surviving bilateral re-implantation show an early post-operative rise in pulmonary artery pressure and pulmonary vascular resistance. These values tend to return to normal as the post-operative period lengthens. Pulmonary artery pressure remains normal in the hilar stripping group. All dogs in both groups increased tidal volume and minute ventilation in response to hypercapnia and anoxia.

32. Preservation of the Canine Lung in Vitro for 24 Hours Using Hypothermia and Hyperbaric Oxygenation

David A. Blumenstock, Neil Lempert*, and Fernando Morgado*,

Cooperstown, N. Y.

In this study the left lung was removed from 20 dogs, perfused with serum or dextran and placed at 4°C. for 24 hours in an atmosphere of oxygen at a pressure of 30 pounds per square inch. The lung was then placed in a homologous host treated with methotrexate to delay the rejection reaction. The transplant was evaluated by biopsy 3-10 days later. Nine of the 20 lungs had a normal histologic appearance at biopsy. Of the 11 failures, 10 were due to technical problems with the pressure tank or the vascular anastomosis. One failure was unexplained and may have been due to the method. The preservation failed in two additional lungs cooled to 4°C. but not subjected to hyperbaric oxygen. This method is simple and may be satisfactory to preserve lungs used for clinical transplantation.

33. Canine Pulmonary Allografts With Uncontrolled Cross Circulation

O. Gago*, R. Zajtchuk*, S. L. Nigro, and W. E. Adams,

Chicago, Ill.

Repeated uncontrolled cross circulation as a means of preventing rejection without the aid of drugs or X-ray treatment was used following pulmonary homografts in 60 dogs. Lung biopsy and blood Po₂ studies during repeated thoracotomy following transplantation were used for evidence of pulmonary function. A complete alveolocapillary block occurred by the third day in the control group of left lower lobe and right lung allografts as demonstrated by the oxygen diffusion studies and the histologic pattern of edema and peribronchial lymphocytic infiltration. Uncontrolled cross circulation between the host and the donor, and between the host and different subjects during each cross circulation, have been shown to preserve the function of left lower lobe allografts studied for as long as 24 days after grafting, at which time they were sacrificed for other studies. During this time they exhibited normal Po₂ and histological appearance. The same procedure was used in right lung allografts, obtaining inconstant results. These findings indicate that the amount of antigen plays a significant role in the control of the rejection phenomenon. Physiological and histological data will be presented and the significance of this methodology as a means of preventing graft rejection discussed.

34. Immediate and Delayed Orthotopic Homotransplantation of the Heart

Yoshio Kondo*, Franz Gradel*, Willy Meier*,

and Adrian Kantrowitz*, Brooklyn, N. Y.

Sponsored by Karl E. Karlson

Among 43 puppies whose hearts were transplanted orthotopically under profound hypothermia without a pump-oxygenator, one is alive 203 days postoperatively. Its well-functioning homograft has grown proportionally and become innervated. No immunosuppressive therapy has been used. Fifteen puppies lived 7-57 days; about half died of acute rejection at 2-3 weeks. The ultimate result sensitively reflected the graft's handling, e.g., 76% of transplants from donors under moderate hypothermia maintained circulation over 24 hours. These findings suggest the technical feasibility of heart transplantation for otherwise uncorrectable congenital heart failure, but procurement of ideal grafts will be a major problem. In 20 experiments to preserve grafts 24 hours, several factors were variously combined and survival data on recipients compared. Best results were obtained with the donor under moderate hypothermia, coronary artery perfusion with Tyrode solution for one minute, cooling in 4°C Tyrode, refrigeration under 3 atm. O₂ pressure, without solution to avoid edema. Eleven of 13 similarly treated grafts functioned adequately for at least four hours. One recipient survived five days. We hope to evolve a reliable storage method by making minor changes in this technique.

35. An Artificial Heart Inside the Chest

Yukihiko Nose*, Lawrence L. Tretbar*, A. Sengupta*,

S. R. Topaz*, and W. J. Kolff*, Cleveland, Ohio

Sponsored by donald B. effler

Present artificial hearts approximate the human heart in size and shape and fit within the pericardium of the calf. This one-piece Silastic unit can pump 8 liters of blood per minute. Attachment of the artificial heart is by direct end-to-end anastomosis to the great vessels and atria. Reservoir action of the atria is not compromised. The four valves are a newly designed tear-drop shape which gives greater flow with less excursion than a ball valve. Retaining feet are used instead of a cage. The heart is driven by compressed air with a relatively simple solenoid system. Regulation of cardiac output is governed by right and left atrial pressures. Calves have replaced dogs as the experimental animal in order to simulate human conditions. The longest survival is 30 hours. Most failures have been mechanical and should therefore be avoidable. Since stroke volume is monitored from beat to beat the effect of drugs can be studied. Vasopressors (nora-drenalin) caused increased blood pressure with decreased cardiac output. Some vasodilators (dibenzyline) caused a fall in blood pressure with a rise in cardiac output without a change in the driving mechanism.

36. The Permanently Implanted Bypass Heart

Nazih Zuhdi*, John Carey*, and Allen Greer,

Oklahoma City, Okla.

Implanted bilateral bypass of heart is accomplished by withdrawing blood at a pre-determined rate from right atrium and returning it to pulmonary artery, and withdrawing it from left atrium and returning it to aorta. Such a bypass heart decreases work of the heart as measured in kilogram meters per hour. This may not be conspicuously reflected by oxygen consumption measurements. Function of the bypass implanted heart is to decrease work of the heart and increase cardiac output as a reduction-additive device to the beating heart. Flow rates smaller than the cardiac output in the bypass heart mean less basic energy and simpler energy conversions. Prototype and controlling mechanisms will be briefly outlined. A bypass implanted heart is placed in either pleural cavity and requires four anastomotic lines without a body perfusion system. Pulmonary artery pressure, aortic pressure and heart rate were recorded during similar and unequal flow rates in each side of the bypass heart for different lengths of time. Equalization of flow of both sides of the implanted heart is achieved through cardiac and extra-cardiac mechanisms. The impossible problem of having pumps delivering identical amounts of blood may thus be obviated.

37. Assisted Circulation: The Pressure Pulse Generator

Phillip B. Callaghan*, and David H. Watkins,

Denver, Colo.

In recent years attempts to assist the circulation in cases of coronary occlusion or following cardiac surgery have been sought. One of the methods which has been tried to assist the circulation has been counterpulsation. Early attempts to use pneumatically operated systems have failed, and it appears that on a system analysis basis the failures may well have been due to engineering design rather than poor physiological concepts. Consequently, a hydraulically or electrically actuated system has been designed which has the following features: (1) ability to maintain good volume transfer in and out of the arterial system even at high heart rates, (2) ability to maintain synchronization even with cases of auricular fibrillation or auricular flutter with a varying block, (3) ability to discriminate physiologically between true heart beats and physiological noise, (4) very fast response time, leading to the discovery of a Null timing point at which the effect on cardiac work of the pressure pulse generator appears to be a maximum for a given volume displacement, and (5) construction of the blood handling apparatus to minimize priming volume. Resultant new physiological concepts and clinical applications of the pressure pulse generator will be illustrated.

38. The Normal Mode of Action of the Mitral Valve and its Alteration Following Replacement by a Prosthetic Ball Valve

Stanley K. Brockman*, Harold A. Collins, and

Harold E. Snyder*, Nashville, Tenn.

Left atrial pressure, left ventricular pressure, the gradient across the mitral valve and phonograms were recorded in dogs before and after insertion of a Starr-Edwards mitral ball valve. Individual atrial contractions in dogs with heart block caused a delayed rise in ventricular pressure which remained elevated while atrial pressure fell. The negative difference in A-V pressure resulted in closure of the mitral valve. In dogs with sinus rhythm the mitral valve is closed prior to the rise in ventricular pressure by the same mechanism. Closure of the prosthetic mitral valve is accomplished by a similar mechanism but the negative difference in A-V pressure is less. An increased resistance across the prosthetic valve best explains the altered pressure relationship. Closure of the mitral ball valve can be distinctly felt with each atrial contraction during induced ventricular fibrillation. "Double draw" dye studies revealed no mitral regurgitation. These data suggest that the normal mitral valve and the ball valve are closed by atrial contraction prior to the onset of ventricular contraction. This is contrary to the accepted view that the mitral valve is closed by the rising intraventricular pressure.

39. Open Heart Surgery for Mitral Valve Disease

William P. Young, Vincent L. Gott*, and George G. Rowe*,

Madison, Wis.

Closed heart surgery for mitral disease was abandoned at the University of Wisconsin Hospitals in 1961. Since then 120 patients have had open surgery on the mitral valve alone or in conjunction with other valves. The frequency of unexpected clots, subvalvular stenosis, and ability to open posteromedial commissures widely justified the open procedures. In 81 patients mitral stenosis was more significant than mitral insufficiency. There were only 3 deaths in this group. All 3 had multiple valve disease. In 39 patients, mitral insufficiency was the more significant, 14 of these died. Dissatisfaction with the results of annuloplasty led to a more routine use of a caged-ball prosthesis. This was, however, accompanied by an increase in deaths, believed to be due to pressure of the cage into the interventricular septum and/or partial obstruction of the left ventricular outflow tract by the ball. The hinged-leaflet prosthetic valve has recently been adopted for use when annuloplasty does not seem satisfactory. With this valve there has been but one death in 10 cases and it was due to cirrhosis. Cardiac catheterization studies of the hinged-leaflet valve are very favorable and will be presented.

40. Factors Limiting Survival After Circulatory Occlusion Under Hypothermia and Hyperbaric Oxygenation

W. Sterling Edwards, Wilfred F. Holdefer, Jr.*,

and Alan R. Dimick*, Birmingham, Ala.

Canine experiments were conducted under hyperbaric conditions at 2 atmospheres, absolute, combined with mild general body hypothermia (30°C) to determine whether the brain or the heart was the major factor limiting the safe time of inflow and aortic occlusion. Experiments were done in a hyperbaric chamber large enough for 2 humans and the experimental animal. After reaching 2 atmospheres pressure the animals were ventilated with 98% O₂ and 2% CO₂ for 15 minutes before caval and aortic occlusion were established for 30 minutes. One half the animals served as controls and the other half had coronary perfusion with hyper-oxygenated blood from a small reservoir, delivered through a needle in the ascending aorta proximal to the aortic clamp. There was a mortality of 83% in the control animals, as compared with a 22% mortality in those with coronary perfusion, and refractory ventricular fibrillation was a much more difficult problem in the control animals. Dogs that survived in both groups had no gross neurological damage. We believe this indicates that myocardial ischemia is a more serious limiting factor than cerebral ischemia under these conditions.

41. The Influence of Hyperbaric Oxygen and of Hypoxia on the Ventricular Fibrillation Threshold

Alan D. Turnbull*, Anthony R. C. Dobell,

and Lloyd D. Maclean, Montreal, Quebec

The ventricular fibrillation threshold (V.F.T.) was determined before and after coronary occlusion in 14 normothermic dogs ventilated with room air, 100% oxygen at 1 atmosphere and 100% oxygen at 3 atmospheres. Arterial blood pressure, arterial blood pH, Po₂ Pco₂ and body temperature were monitored throughout all experiments. Using each animal as its own control, no significant variation in susceptibility to ventricular fibrillation was produced when arterial Po₂ varied between a minimum of 16 mm Hg and a maximum of 1660 mm. of Hg. The V.F.T. declined from 22.5 ± 0.9 ma. without occlusion to 8 ± 0.52 ma. with coronary occlusion when animals were ventilated with room air at 1 atmosphere. Protection was not afforded by ventilation with 100% oxygen at 3 atmospheres (V.F.T. pre-occlusion 21.2 ± 1.1 ma. post occlusion 8.3 ± 0.8 ma.). Arterial blood pH, Pco₂ and body temperature were maintained within normal range in both groups. The ease of defibrillation was strikingly facilitated during the period of hyperbaric treatment. Defibrillation was impossible in animals breathing room air or oxygen at 1 atmosphere with coronary occlusion present. On oxygen at 3 atmospheres, defibrillation was regularly accomplished with single shocks of low voltage even in the presence of coronary occlusion.

42. Clinical Experience and Problems Encountered with an Implantable Pacemaker

Joe D. Morris, Richard D. Judge*, Bernard J. Leininoer*,

and Friedrich K. Vontz*, Ann Arbor, Mich.

A series of 65 patients with complete heart block treated by means of an implanted pacemaker has been reviewed. A high incidence of pacemaker failure early in the series has been reduced by progressive improvement in lead design and improvement in surgical techniques of implantation which minimize lead stress. A new lead possessing greatly increased stress tolerance will be shown. Exit block phenomenon characterized by lack of ventricular response to adequate artificial pacemaker stimulus has been encountered in 14 patients. Management of this complication will be discussed. Other mechanisms of pacemaker malfunction will be reviewed and means of identifying and correcting these problems will be demonstrated. Clinical experience with a variable two-rate unit will be presented.

43. A New Epicardial Pacemaker for the Control of Complete Heart Block

Raymond C. Bonnabeau, Jr.*,

Randolph M. Ferlic*, and C. Walton Lillehei,

Minneapolis, Minn.

The conventional treatment of patients with complete heart block utilizes a cardiac pacemaker implanted in the abdominal wall or elsewhere with myocardial stimulation by means of wire electrodes. Good results have been obtained with this type unit, but many failures have occurred related to wire electrode breakage. As a result, we have developed a small transistorized pacemaker unit measuring 4 x 3 x 1 cm. which is sutured directly on the epicardial surface and heals thereon. Small electrodes projecting from the unit insert into the myocardium from the under surface of the pacemaker, thus entirely eliminating electrode wires. This unit is powered by a mercury cell which can be recharged at approximate yearly intervals from an induction coil source through the intact chest wall. The recent development of much more reliable rechargeable energy cells makes this new approach feasible. Acute and chronic experiments on canines have shown the feasibility and practicability of this approach.

*By Invitation