Monday Morning, May 6, 1957

8:30 A.M. Scientific Session: THORACIC SURGERY FORUM-Grand Ballroom

14. The Effects Produced by Various Types of Pump Oxygenators During Two Hour Partial Perfusions in Dogs.

Marian E. Molthan (by invitation), Stanley Gianelli (by invitation)

Richard J. Best (by invitation), James A. Dull (by invitation)

and Charles K. Kirby, Philadelphia, Pa.

The careful use of a large bubble oxygenator for whole body perfusion produces no apparent ill effects for periods up to about thirty minutes. We have found evidence, however, that prolonged bubbling of oxygen through blood may cause irreversible changes, particularly as manifested by permanent brain damage.

Blood was withdrawn from the superior and inferior cavae through jugular and femoral vein cannulae and returned to the thoracic aorta through a carotid cannula inserted in the neck at a rate of 40 cc/Kg. of body weight per minute (a rate commonly used for whole body perfusion). No incisions were made except for those in the neck and groin. When a bubble oxygenator was used, neurologic evidence of brain damage was almost invariably present. Some animals showed only minimal transitory changes, whereas others had severe impairment with ensuing death or prolonged disability, usually without complete recovery. The degree of brain damage appeared to be greater when the oxygen flow rate was increased. When blood from a femoral artery was passed through the same extra-corporeal circuit without bubbling oxygen through the blood, there was no neurologic evidence of brain damage.

Multiple small infarcts were found in the brain of the animals showing permanent damage. We hope to be able to learn the cause of these infarcts.

The cause of the brain damage resulting from these two hour perfusions is under investigation. The experiments are being repeated with the use of a film oxygenator and a biologic oxygenator.

15. Acid-Base Balance During Prolonged Cardio-Respiratory By-Pass.

Matthias Paneth, Traveling Fellow of the Association, 1956-57

(by invitation), London, England, M. Nazih Zuhdi (by invitation)

and William Weirich (by invitation), Minneapolis, Minn.

The perfusion rate in most pump-oxygenator systems for complete cardio-respiratory by-pass is usually a portion of the normal resting cardiac output. This means that an elevation of fixed acids and fall in alkaline reserve may develop during the period of by-pass presumably because of reduced blood flow and/or diminished renal function. Since it might be supposed that the degree of metabolic acidosis is related to the perfusion rate as well as duration of perfusion, a series of dogs have been perfused for one hour at varying rates using the Sigmamotor pump and the bubble oxygenator. The acid-base alterations after an hour's perfusion have been measured in these animals and the results are presented. The acid-base alterations in human perfusions lasting one hour or more will also be presented.

16. Coronary Perfusion as an Aid to Open Heart Surgery under Hypothermia in Man.

J. V. Maloney, Jr. (by invitation), S. A. Marable (by invitation)

and W. P. Longmire, Jr., Los Angeles, Calif.

Open heart surgery during circulatory occlusion under hypothermia has been demonstrated to be a feasible method for operations of brief duration. The major deterrent to the use of this method has been the frequent occurrence of arrhythmias, myocardial cyanosis and flaccidity, and ventricular fibrillation. The present report deals with 12 patients in whom this technique was employed. Of the first six patients, four showed poor myocardial tone and developed arrhythmias, including two instances of ventricular fibrillation. All six patients developed myocardial cyanosis and required cardiac massage to restore effective heart action.

In the second group of six patients, the heart was perfused with freshly-drawn, heparinized artenahzed blood during the period of circulatory interruption. Perfusion was carried out by cross-clamping the ascending aorta and delivering blood from a pressurized bottle through a needle inserted into the aorta just above the coronary ostia. The perfusion rate was 3 ml. per Kg., body weight per minute. Of these six patients, one showed poor myocardial tone and one other developed a transient arrhythmia. None showed myocardial cyanosis, and only one patient required cardiac massage. Ventricular fibrillation did not occur. Continuous tracings of the electrocardiogram and arterial pressure show that the circulation recovers spontaneously within several heart beats after inflow occlusion is released.

Although all 12 patients did well following surgery, the reduction in complications in the perfused group suggests that coronary perfusion greatly enhances the safety of open heart surgery under hypothermia.

17. Alterations in Renal Hemodynamics During and Following Resection of the Thoracic Aorta for Aneurysm.

George C. Morris, Jr. (by invitation), Raymond R. Witt (by invitation),

Denton A. Cooley, John M. Moyer (by invitation)

and Michael E. DeBakey, Houston, Texas.

Temporary occlusion of the thoracic aorta during resection and grafting for aortic aneurysm may produce ischemic changes in organs located distally. Damage to the central nervous system may occur after relatively brief periods of aortic occlusion unless means of protecting the brain or spinal cord are employed. We have employed cardio-pulmonary by-pass and total body perfusion for resection of the ascending aorta thus providing protection for the brain, spinal cord, and other vital organs. For aneurysms of the descending thoracic aorta we have used aortic by-pass shunts, general body hypothermia, and recently controlled extracorporeal circulation shunting blood from left auricle to abdominal aorta. The purpose of this presentation is to compare the effects of these various procedures upon renal function using inulm to determine glomerular filtration rate and para-amino hippurate to determine renal blood flow.

These studies indicate that none of the methods employed cause permanent deleterious effects on the kidney. Of particular physiological interest, however, was the measurement of renal blood flow and glomerular filtration rate during the period of aortic occlusion with and without artificial maintenance of circulation. In the absence of by-pass there was no measurable renal function, but with the by-pass mean blood pressure in abdominal aortic segment varied from 35 to 50 millimeters of mercury and renal blood flow ranged from 15 to 130 cubic centimeters per minute. These observations indicate that controlled temporary extra-corporeal circulation exerts an important protective effect upon the kidneys during periods of occlusion of the thoracic aorta.

18. Physiological and Pharmacological Studies of Collateral Pulmonary Flow.

David State (by invitation), Peter F. Salisbury (by invitation)

and Peter Weil (by invitation), Los Angeles, Calif.

Increased collateral blood flow to the lungs via dilatation of the bronchial vessels may play an important role in certain types of cardiac and pulmonary disease Direct measurements of the collateral blood flow to both lungs in animals with intact reflexes have not been reported before. The use of a pump-oxygenator has afforded us the opportunity for total by-pass of the heart and lungs for separate perfusion of the pulmonary circulation with known volumes of blood.

In the method used, all venous blood was diverted from the right ventricle to a pump-oxygenator and returned to the arterial tree through a femoral artery. Blood was prevented from reaching the lungs by a tie placed at the origin of the pulmonary artery. A plastic tube placed in the left atrium or ventricle, collected blood returning from the lung into a reservoir. By means of a separate pump, the blood collected from the reservoir was returned to the pulmonary artery by a catheter inserted distal to the tie about the pulmonary artery. The quantity of blood circulated through the isolated pulmonary circuit was kept at known volume. Any increments above this could be directly read from changes of blood level in the reservoir and represented collateral pulmonary flow originating in the systemic circulation.

The effect of the following factors on collateral pulmonary flow will be reported: (1) systemic blood flow, (2) systemic arterial pressure, (3) systemic venous pressure, (4) pulmonary artery flow, (5) ventilation volumes of the lungs, (6) systemic anoxia, (7) systemic respiratory acidosis and (8) administration of various drugs (i.e., adrenalin, serotonin).

19. An Experimental Appraisal of the Finney Pyloroplasty in the Prevention of Esophagitis Following the Heller Myotomy.

Paul W. Herron (by invitation), George I. Thomas (by invitation)

and K. Alvin Merendino, Seattle, Wash.

It has been observed, both clinically and experimentally, that operative procedures which compromise the sphincter action of the esophagogastric junction, are attended by a significant incidence of post-operative esophagitis.

In the laboratory, esophagogastrostomy, Grondahl cardioplasty, and to a lesser extent, Heller myotomy, have all been shown to contribute to a high incidence of esophagitis in dogs stimulated with histamine. Vagotomy has been shown to complement the seventy of the esophagitis, but vagotomy and Finney pyloroplasty reduce it.

This study was undertaken to evaluate the effect of Finney pyloroplasty alone in histamine stimulated dogs following Heller myotomy. Two groups of dogs were developed. Group I consisted of dogs subjected to Heller myotomy. Group II consisted of dogs subjected to Heller myotomy and Finney pyloroplasty. After a 30-day recovery period, all dogs were given histamine for 45 days, or until death. They were autopsied and appropriate histologic studies done. The incidence of esophagitis in Group I was about 70%; in Group II it was 9%, in spite of abundant evidence of ulcerative disease in the stomach and duodenum in these dogs.

It is felt that under the conditions of these experiments, Finney pyloroplasty markedly reduces the incidence of esophagitis in dogs following Heller myotomy.

20. Esophageal Motility in Achalasia (Cardiospasm) After Treatment.

Brian Creamer (by invitation), Arthur M. Olsen, Colin B. Holman

(by invitation) and Charles F. Code (by invitation), Rochester, Minn.

Measurements of esophageal pressures have been made in our laboratory by use of minute electromagnetic transducers and a photokymographic system. Butin and his associates demonstrated patterns of motility in healthy individuals and showed that peristaltic contractions were either absent or ineffective in achalasia. Hightower and co-workers confirmed the observation of Kramer and Ingelnnger that methacholine chloride (mecholyl) produces sustained elevation of pressure in achalasia. Creamer and associates showed that the resting pressures at the cardia in cardiospasm are similar to those of healthy persons. Although there is increased tone at the gastroesophageal sphincter, there is no more spasm in the patient with cardiospasm than in the normal person. However, clinically successful treatment of cardiospasm either by dilatation or cardiornyotomy significantly alters the pressures at the gastroesophageal sphincter.

The intraluminal pressures of the esophagus and the gastroesophageal sphincter have been measured following hydrostatic dilatation of the sphincter in 17 patients with achalasia and following operative procedures in 13 patients with achalasia. The motility in the body of the esophagus after dilatation was found to be identical to that seen in untreated patients with achalasia. In a few patients in whom the studies were made both before and after treatment the abnormal pattern of motility in the esophagus was usually unchanged, and the normal peristaltic wave of deglutition was never observed to return following treatment. The resting tone of the gastroesophageal sphincter was, however, almost always reduced following a successful clinical result of either dilatation or operation. The abnormally high pressures, developed in the esophagus in response to methacholine chloride (mecholyl) in achalasia, were still present following treatment.

21. Postoperative Sodium Excretion Following Administration of Hypertonic Sodium Chloride Solution.

Joseph L. Kovarik (by invitation) and John F. Laws (by invitation).

Sponsored by Hiram T. Langston, Chicago, Ill.

Postoperative hyponatremia and decreased urinary sodium excretion have been accepted as a normal sequel to surgical trauma. Numerous studies have been reported which attempt to elucidate the physiologic processes which contribute to the observed sodium retaining properties of the kidney after operation. Hormonal influence, particularly aldosterone, translocation of the sodium ion from the serum to the intra-cellular and/or extracellular space, and altered renal tubular function have all been implicated with regard to this phenomenon. It has been generally agreed that the ability of the normal kidney to excrete sodium is impaired early postoperatively and because of this, it is advisable to restrict sodium intake during this period.

Because this postoperative sodium retention occurs concomitantly with a decrease in the serum sodium level, it was felt that the renal sodium retention might be a reflection of a need to conserve sodium early postoperatively in an effort to return the serum sodium level toward a normal concentration.

Studies of serum electrolytes (notably sodium) and urinary electrolyte excretion have been carried out in thoracic surgical patients divided into two groups-

1. Those receiving "routine" management i.e. sodium restriction during the early postoperative period.

2. Those receiving hypertonic sodium chloride solution postoperatively. Thoracic surgical patients were chosen for this study because of minimal alteration of gastrointestinal tract function with only short-term dependence on parenteral feeding postoperatively.

The results indicate that the postoperative kidney can and does excrete sodium when serum sodium levels are maintained by the administration of hypertonic sodium chloride solution.

22. Anatomic and Pathologic Studies of the Thoracic Duct.

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

Arthur A. Stein (by invitation), Ralph D. Alley and

Allan Stranahan, Albany, N. Y.

Surgical intervention for the treatment of chylous effusion has been a development of the past decade and has of necessity stimulated further investigation of the thoracic duct system. Since previous anatomic descriptions appeared to be at variance, and because little information concerning the pathology of the thoracic duct was to be found, the present project was undertaken.

Sixty fresh cadavers were utilized. In fifty, the thoracic duct was cannulated above the diaphragm. After injecting radiopaque dye proximally and distally appropriate radiographic exposures were made. Methylene blue (1% solution) was similarly injected. Following evisceration the duct system and cysterna chyli were dissected. Sections from various levels of the duct and cysterna were removed for histologic examination. Thus, radiographic, gross and histologic observations on each case were available for study, as well as the overall morbid processes found at autopsy.

In ten additional instances, cervical cannulation of the duct with caudad injection was performed.

From these preparations we observed: (1) Five separate duct systems are suggested. (2) Two or more channels were found in approximately one-third of the cases at the level of the tenth dorsal vertebra. (3) Retrograde injection from the neck is usually unsuccessful because of unidirectional valves. (4) The details of histologic structure vary with the level in the duct system. (5) No primary pathology of the duct itself was found although related morbid changes will be discussed.

23. The Study of Ventricular Fibrillation by Threshold Determinations.

Norman E. Shumway (by invitation), John A. Johnson (by invitation)

and Richard J. Stish (by invitation), Minneapolis, Minn.

Sponsored by F. John Lewis, Chicago, Ill.

Electronic implementation of the Wiggers technique for determining ventricular fibrillation thresholds provides a much needed quantitative method for the examination of fibrillatory and anti-fibrillatory agents, physical or chemical.

Accurately measured shocks of 10 milliseconds duration were applied to the hearts of dogs during the vulnerable period late in systole. The current in milliamperes just adequate to provoke ventricular fibrillation was considered to have threshold strength. Oscilloscopes used to monitor stimulus position in the cardiac cycle and to measure the current during stimulation were connected to a Sanborn Twin-Viso recorder so that stimulus amplitude and the electrocardiogram were simultaneously inscribed. The stimulus was delivered at any desired delay after the R wave of the electrocardiogram by means of a signal-synchronization circuit. As many as 50 determinations were obtained in some preparations: defibrillation by countershock was invariably effective.

Two sets of experiments were performed to evaluate the precision of this method. After acute coronary artery occlusion, thresholds to ventricular fibrillation with test stimuli delivered directly on the infarct were one-half the control. Thresholds in adjacent non-infarcted myocardium were not diminished. The second study revealed a consistent geographic pattern for ventricular fibrillation with the right ventricle significantly more susceptible to fibrillation than the left ventricle.

Wherever possible, techniques of measurement should be used to examine biological phenomena: ventricular fibrillation can be studied by this precise, quantitative method.

24. Direct Surgical Procedures on the Coronary Arteries- Experimental Studies.

Ormond C. Julian, M. Lopez-Belio (by invitation)

and Donald Moorehead (by invitation), Chicago, Ill.

It is predictable that future surgical approaches to coronary heart disease will include direct anastomoses between systemic arteries and the coronary arteries distal to the site of obstructive lesions.

In order to test techniques for these vascular procedures end-to-end anastomoses between the internal mammary artery and the circumflex coronary artery have been accomplished in mongrel dogs. Seven such procedures have been done under sterile conditions to date. Four have survived in an up to six month period of observation.

Two techniques, one utilizing temporary polyethylene shunts and, the second, potassium cardiac arrest during extracorporeal circulation will be described and compared.

25. Ligation of the Internal Mammary Arteries as a Means of Increasing Blood Supply to the Myocardium.

Robert P. Glover and Julio C. Davila (by invitation), Philadelphia, Pa.

Recent reports by European workers indicating that ligation of the internal mammary arteries has resulted in dramatic relief of angina have aroused the authors' interest.

Studies to ascertain the anatomic basis for these claims have been carried out. Tracer substances injected into the proximal segment of the internal mammary arteries after ligation at the second intercostal space have been recovered in the coronary sinus indicating a substantial contribution to myocardial circulation from this extracardiac source.

The detailed results of these experiments as well as of determinations of retrograde coronary flow will be presented. The initial clinical application of this approach will be discussed.

26. The Gradual Closure of Interatrial Defects.

Robert B. Benjamin (by invitation), Robert S. Flom (by invitation),

St. Paul, Minn., and F. John Lewis, Chicago, Ill.

Most interatrial defects can be closed surgically with few complications and with excellent long term results. However, there remains one group of patients-those having long-standing interatrial defects with an associated pulmonary hypertension- in which conventional methods of closure have resulted in a high mortality due to right heart failure. The authors have felt that if a method for gradual closure of interatrial defects could be developed, it would be suitable for treatment of this group of cardiac patients inasmuch as the dynamics of blood flow would then be changed rather slowly.

Large interatrial defects were created in 80 mongrel dogs, and the defects were then partially closed by suturing the edges of the defect to an ivalon patch having one or more holes of varying size. Most of the animals had an elevated right atnal pressure-produced by excising one-fourth to one-third of the tricuspid valve.

It was found that partially closing the interatrial defect with an ivalon patch containing a single hole 8 mm. in diameter produced gradual closure over a period of one to two weeks following surgery. All dogs sacrificed within one week after surgery

had a large defect still present. In all dogs sacrificed between 7 and 13 days post surgery the defect was at least half closed, and in all dogs sacrificed after 13 days the defect was completely closed. The ivalon sponge is first covered and invaded by fibrin. This is replaced by fibrous tissue and the defect is then bridged by strands of fibrin and connective tissue. After 3 weeks the defect is filled in with fibrous tissue and covered with endothelium. Defects in control dogs have all remained open.

At the present time this method of closing interatrial defects is being evaluated in dogs having pulmonary hypertension and a right to left shunt in addition to their interatrial defects.

27. Physiological Considerations of Intracardiac Pressures Following Closure of Atrial Septal Defects.

Henry T. Bahnson and G. Rainey Williams (by invitation), Baltimore, Md.

Of the several physiological data obtained on patients undergoing closure of atrial septal defect, measurements of intra-atrial pressure taken directly during operation before and after closure of the defect have been given special study. To date, information sufficiently complete for analysis has been obtained on 14 patients. There has often been a striking, and sometimes alarming, increase in left atrial pressure following closure. The increase in left atrial pressure is correlated with the size of the left to right shunt through the defect as measured preoperatively. These data agree with the concept of Dow and Maloney and indicate that the size of the shunt through an atrial septal defect is determined by the relative resistance to filling of the two ventricles. With a large preoperative shunt one may expect to find an increase of left atrial pressure after closure; this increment will be greater with an increased blood volume. The therapeutic significance of these data will be discussed in relation to selection of patients for operation and their surgical handling.

28. Transplantation of the Homologous Canine Heart.

Salem F. Sayegh (by invitation), Max Halley (by invitation)

and Oscar Creech, Jr., New Orleans, La.

This is a report of a study to determine: (1) factors influencing survival of the transplanted homologous heart, and (2) the electrocardiographic and vectocardiographic patterns of the denervated cardiac transplant.

The method of transplantation is essentially that described by Markowitz and his associates and consists in removal of the transplant, ligation of the superior and inferior vena cavae, and reimplantation in either the neck or the groin. The aorta is anastomosed to the common carotid or femoral artery, and the pulmonary artery to the external jugular or femoral vein.

Preliminary experiments consisted of transplantation of puppy hearts to the neck or groin of adult animals and resulted in a survival time of six hours to eight days. With these experiments as a background additional studies were undertaken in an attempt to prolong the survival of the transplanted hearts. In one group of animals the heart was encased in an envelop of "millipore" (which is a membranous filter made of cellulose esters and designed for surface screening of particles in the sub-micronrange). In another group of animals transplantation was done using fetal hearts removed during the last two weeks of gestation and transplanted into the neck of the mother. Finally, in a group of adult animals, cardiac transplantation has been preceded by about six weeks by transplantation of the spleen of the donor with vascular implantation of the splenic pedicle in an effort to produce immune paralysis.

The second phase of this study is concerned with the electrocardiographic and vectocardiographic patterns observed in the transplanted homologous heart. These studies are performed immediately after transplantation and daily thereafter for the life of the transplant in an attempt to determine the mechanism of failure of the grafted heart.