Grand Ballroom

38. Parenchymatous Splenopulmonary Anastomosis as Possible Treatment for Portal Hypertension in Children

Francis Remillard (by invitation), Patrick E. Conen (by

invitation), Toronto, Ont., and George R. Walker, Sudbury, Ont.

The operation consists of embedding a portion of the spleen on its pedicle within the substance of the lung. This was carried out on dogs in the absence of, immediately preceding, and following the onset of portal hypertension. (This condition is created by a previously developed method known as the "sponge" procedure). This anastomosis is uniformly successful in the presence of portal hypertension and the latter is reduced as a result. Operations were also carried out in monkeys. In two cases, after a splenopulmonary anastomosis was done it was possible to do a one-stage portal vein ligation with survival. The monkeys used were Cynomolgus, which normally do not survive one-stage portal ligation.

39. Alterations in Intrabronchial Temperature, Humidity, and Oxygen Concentration Produced by Various Clinical Methods of Oxygen Administration

JD Mortensen (by invitation), Salt Lake City, Utah

Techniques have been developed for determining the oxygen content, humidity, and temperature of both inspiratory and expiratory gas samples at various points from mid trachea to bronchioles. Normal values for these variables at four points in the tracheobronchial tree have been established. The same determinations have been made when oxygen is being administered by various methods in current clinical use, and indicate often severe alterations from the physiologic state. More effective "conditioning" procedures are suggested.

40. The Regression of Pulmonary Vascular Disease after the Creation of Pulmonary Stenosis

J. Francis Dammann, Jr., Charlottesville, Va , James A. McEachen

(by invitation), Santa Monica, Calif., W. M. Thompson, jr.,

(by invitation), Charlottesville, Va., Rodney Smith (by invitation),

Santa Monica, Calif., and William H. Muller, Jr., Charlottesville, Va.

Corrective surgery for large ventricular septal defects in face of relatively advanced pulmonary vascular changes has been attended by a high mortality rate. A palliative surgical procedure consisting of the creation of pulmonary stenosis has been reported. Twelve patients in whom this operation was performed have since returned for a corrective procedure. In each there was good evidence of regression of the pulmonary vascular disease and a close correlation was noted between the degree of stenosis created and the degree of improvement. The principle factors that appear important in this correlation will be developed.

41. The Effects of Low Molecular Weight Dextran Upon the Blood Flow Rate During Extracorporeal Circulation

Christopher Drake (by invitation), Fidel Macalalad (by invitation), and

F. John Lewis, Chicago, Ill.

During extracorporeal circulation with blood cooling, the blood flow rate tends to decrease as the body temperature drops. Thirty-one animals were cooled to 10° C. on by-pass without added blood. Fifteen of these were used as controls and 16 were given 10-12.5 cc./kg. of 10% LMWD intravenously just prior to by-pass. In the latter, flow rates were better maintained and less time was required to cool and rewarm the animals than in the controls. Arterial pressure tended to be somewhat higher but venous pressure did not appear to be affected, in the animals receiving LMWD. No pulmonary edema was noted. We conclude that LMWD may be used in small doses to maintain adequate flow rates during extra-corporeal circulation with hypothermia without adding blood.

42. Mechanisms of Pulmonary Hypertension in Acute Hypoxia

Ibrahim K. Dagher (by invitation), Henry G. Mishalany

(by invitation), Beirut, Lebanon, and F. A. Simeone (by

invitation), Cleveland, Ohio

Sponsored by John L. Wilson, Beirut, Lebanon

The occurrence of pulmonary arterial hypertension in hypoxia has been demonstrated. The mechanism of this has not been thoroughly investigated. Twenty-four dogs were made hypoxic with N₂O and were subjected further to vagotomy; bilateral thoracic sympathectomy; left atrioarterial shunt ; vagotomy and left atrioarterial shunt; bilateral thoracic sympathectomy and left atrioarterial shunt, sympathectomy, vagotomy and left atrioarterial shunt; bilateral adrenalectomy; bilateral adrenalectomy and phentolamine-Regitine(^R); RegitineW alone. Two underwent controlled constant right ventricular output and two others electrical stimulation of the thoracic sympathetics alone and coupled with controlled constant right ventricular output. Two animals were used as controls. We conclude: (1) The hypertension is initiated by the thoracic sympathetic system. Subsequent development of pulmonary congestion secondary to left heart failure adds to its intensity; (2) sympathetic activity accounts for about 55% of the total rise in pulmonary arterial pressure and left heart failure for 45%; (3) stimulation of the thoracic sympathetics produces a rise in the pulmonary arterial pressure. Blocking this sytem with RegitineW prevents this rise; (4) bilateral adrenalectomy, bilateral vagotomy and controlled constant right ventricular output do not influence the course of the pulmonary hypertension induced by severe hypoxia.

43. Experiences with NaI¹³¹ Injected into the Myocardium as an Estimate of Coronary Blood Flow

Irving M Madoff, and William Hollander (by invitation),

Boston, Mass.

Previous studies have shown that the rate of disappearance of an ion injected into a tissue is a function of blood flow The disappearance of NaI¹³¹ was measured by externally monitoring the site of injection. Radioactivity increased in the blood as NaI¹³¹ disappeared from the injection site. In dogs the disappearance of NaI¹³¹ (10 micro-curies) was extremely rapid. The rate of removal decreased as a coronary artery was progressively narrowed and stopped completely following total occlusion of the artery. In human subjects without coronary artery disease, the disappearance of NaI¹³¹ was also rapid. In patients with coronary disease, the removal of NaI¹³¹ was markedly impaired being only ¹/₅ to ¹/₂₀ as rapid.

44. Replacement of Right Ventricular Myocardium with a Teflon Prosthesis

Harold A. Collins (by invitation), J. Kenneth Jacobs

(by invitation), Robert T. Sessions (by invitation),

and Rollin A. Daniel, Jr., Nashville, Tenn.

In one series of dogs, 25% to 40% of the right ventricular myocardium was excised and replaced by woven teflon fabric. In another series of animals infarction was produced by ligation of branches of the right coronary artery. The infarcted portion was excised and replaced with teflon fabric. Cardiac output was determined by the dye dilution technic pre-operatively and in six weeks. Animals were permitted to survive a minimum period of six weeks before sacrifice. Of 10 animals in the first group 7 survived. On sacrifice the teflon fabric was well incorporated and the intraventricular portion was smooth and no thrombi were apparent. Cardiac output had been maintained. The mortality in the second group was high; 7 of 13 dogs died as a result of sloughing of the fabric, apparently due to inadequate resection of non-viable myocardium. It would appear that prosthetic material can be utilized to replace right ventricular myocardium.

45. Blood-Brain Barrier Studies in Extracorporeal Cooling and Warming

Harry S. Pollard, Jr. (by invitation), R. J. Fleischaker (by

invitation), J. J. Timmes, and K. E. K.arlson, St. Albans, N. Y.

Seventeen dogs were perfused under varied circumstances, for study of the fluorescein blood-brain barrier. These included normothermic total perfusions, total perfusions with rapid cooling, partial perfusions via the femoral artery with rapid cooling, cooling with perfusion via the aortic arch, cooling by partial perfusion via femoral artery and warmed by heat exchanger in the arterial line and finally cooling by femoral perfusion and warming by heat exchanger in the venous line The areas of brain fluorescence were recorded for each category. The results of these studies suggest that, from the standpoint of minimizing the risk of gaseous embolism to the brain, rapid cooling of a patient is most safely accomplished by partial perfusion via the femoral artery and that rapid warming is safest with the heat exchanger proximal to an adequate bubble trap.

46. Hemodynamic and Metabolic Responses of the Whole Body and Individual Organs to Cardiopulmonary Bypass with Profound Hypothermia

Thomas J. Yeh (by invitation), Lois T. Ellison (by

invitation), and Robert G. Ellison, Augusta, Ga.

Profound hypothermia was induced in dogs undergoing total cardio-pulmonary bypass. Venous return, venous and arterial oxygen saturation, pH, pCO₂ and bicarbonate were determined at different temperatures and perfusion rates. Venous return diminished progressively with cooling in all dogs. With higher flows blood sequestrated in large quantities and was only partly recovered during rewarming. Portal venous pressure rose markedly. With lower flow rates, these effects were minimized. Arterio-venous oxygen saturation difference narrowed with cooling, and was abolished at about 10° C. By reducing flow rate, venous oxygen saturation could be kept at 70% to 80%. With high flow perfusion, pH was not affected appreciably, but with low flow perfusion metabolic acidosis developed in spite of seemingly adequate flow. In cardiopulmonary bypass, the use of mixed venous oxygen saturation as monitor of adequacy of flow may be fallacious. Thus, flow rates must exceed those anticipated from reduction in metabolism associated with hypothermia. It seems desirable to adjust flow at maximum possible, without seriously exceeding available venous return at a given temperature.

47. Metabolic Alterations Associated with Profound Hypothermia and Extracorporeal Circulation in the Dog and Man

William F. Bernhard (by invitation), Hans F. Schwarz

(by invitation), and Robert E. Gross, Boston, Mass.

Certain inherent metabolic alterations accompany continuous hypo-thermic perfusion, and are accentuated by periods of circulatory arrest. The least well documented of these involves the development of a metabolic acidosis during the rewarming period. The reductions in arterial pH and plasma CO₂ content which occur have been found to be directly proportional to an elevated plasma lactate concentration. This lactacidemia is dependent upon several factors: (1) A relative failure of the muscle mass to cool sufficiently; (2) the duration of total circulatory arrest; (3) a depression of hepatocellular activity noted below 30° C. The material for this investigation includes: (1) An evaluation of the changes in arterial pH, whole blood CO₂, pCO₂, plasma CO₂ content, plasma lactate, and oxygen consumption, in 30 dogs subjected to profound hypothermia, (10°G); (2) a similar study involving 13 patients with congenital heart disease, who had open repair of their intracardiac defects at body temperatures of 9°-14° C.

48. Treatment of Respiratory Insufficiency by Prolonged Extra-corporeal Circulation: Experimental Observations

Robert Schramel, William Chapman (by invitation),

Berwin Volnie (by invitation), and Oscar Creech, Jr.,

New Orleans, La.

Thirty-five dogs were subjected to partial cardiopulmonary bypass for six to eight hours, whereby blood was removed by gravity from the inferior vena cava, pumped into an oxygenator and returned by gravity to the superior vena cava. Observations were made to delineate the control of blood gases that can be achieved by this method as well as the effects on the animal of prolonged partial cardiopulmonary bypass. The various data derived from these studies will be given in detail It is concluded, that this procedure can safely be applied for six to eight hours and should be effective in controlling arterial levels of oxygen and carbon dioxide in the presence of respiratory insufficiency in humans.

49. Correction of Complete Heart Block by a Self-Contained and Subcutaneously Implanted Pacemaker

William M. Chardack (by invitation), Andrew A. Gage

(by invitation), and Wilson Greatbatch (by invitation),

Buffalo, N. Y.

The development of a transistorized and completely implantable pacemaker has been previously reported. The dimensions of the device, including its battery supply, are approximately 6 x 9 x 2 cm. The current drain is so low that the useful life of the batteries is conservatively estimated to be between five and six years. A bipolar electrode is placed on the myocardium and its lead wires travel to the upper abdominal area where the pacemaker itself is placed subcutaneously. The device has been implanted in eight patients. All are alive. Results have been gratifying. Complications have occurred in two but have not necessitated interruption of electrical pacing of the heart. Follow-up observations and operative technique will be reported upon.