Monday Afternoon, April 24, 1961

2:00 P.M. Scientific Session: REGULAR PROGRAM Grand Ballroom

7. Tumors of the Thymus Gland

Philip E. Bernatz, O. Theron Clagett, and

Edgar G. Harrison, Jr. (by invitation), Rochester, Minn.

Review of the histories of approximately 150 patients whose thymic tumors have been available for study reveals a relatively ominous prognosis, particularly when associated with myasthema gravis (48% of the series). An interesting comparison is drawn with patients undergoing thymectomy for myasthenia gravis but without a thymic tumor. Available classifications of thymic tumors have been of little clinical value. Re-evaluation of the pathologic characteristics of this group of thymomas permits a practical working classification of prognostic value. The perplexing associations of thymic tumors and disturbances in serum proteins, as well as with refractory anemia caused by agenesis of erythrocytes and alterations in adrenal cortical function, will be reviewed.

8. The Etiology of Acute Respiratory Acidosis

Richard M. Peters, Thomas B. Barnett (by invitation), and

Robert Zeppa (by invitation), Chapel Hill, N. C

Our experience in the correction of acute respiratory acidosis by hyper-ventilation in 12 patients, one-third traumatic, one-third with degenerative pulmonary disease, and one-third following open heart surgery will be presented. The mechanism of the progressive increase in acute respiratory acidosis will be analyzed and correlated with experimental studies on the work of breathing. These studies demonstrate: (1) Hypercapnia markedly increases the non-elastic work of breathing (Principally the work needed to overcome airway resistance); (2) a given rise in arterial pCO₂ elicits an increase in respiratory work which may not necessarily lead to a level of alveolar ventilation adequate to maintain a normal level of arterial pCO₂. The metabolic acidosis following open heart surgery will be discussed as a possible etiologic factor in the acute respiratory insufficiency these patients develop.

9. Perfusion Hypothermia and Ventricular Fibrillation

William J. Kerth (by invitation), John J. Osborn (by invitation),

Frank Gerbode, J. Bruce Johnston (by invitation),

and Takeshi Ogata (by invitation), San Francisco, Calif.

In 56 patients perfused with a heat-exchanging oxygenator, blood temperature was lowered to between 15° and 25° C The temperature at onset of ventricular fibrillation during cooling and the incidence of spontaneous reversion to sinus rhythm during rewarming were studied in relation to acid base balance and other blood chemical parameters. A direct relation was found between blood temperature at onset of fibrillation and blood pH, regardless of how the pH was lowered. The incidence of spontaneous reversion from ventricular fibrillation during rewarming was highest in those patients who had been rendered most acidotic during cooling. Deep hypothermia was usually associated with loss of potassium from the serum, rewarming with return of serum potassium to normal levels. The clinical condition of patients who had been rendered acidotic during cooling was better postoperatively and their gross mortality was lower than in patients cooled at normal pH. Possible explanations for these findings will be discussed.

10. Alterations in Blood Volume Following "Normovolemic" Total Body Perfusion

Robert S. Litwak (by invitation), Albert J. Gilson (by invitation),

Ralph J. Slonim (by invitation), Caspar G. McCune (by invitation),

and Howard L. Gadboys (by invitation), Coral Gables, Fla.

This study attempts to evaluate our ability to maintain a normovolemic state in 25 consecutive cases undergoing open heart surgery with a pump-oxygenator. Plasma (PV), red cell (RCV), and total blood volumes (TBV), were determined directly by isotopic means using iodinated human serum albumin (RISA) and Crsi labeled red cells, (a) with the patients lightly anesthetized prior to thoracotomy and (b) two hours following the perfusion During surgery, an assiduous attempt was made to measure and immediately replace all blood losses. The patients were weighed on a metabolic scale at the end of the operation. The results of this study indicate significant errors (mean net TBV loss of 14.35 ml./kg., net PV loss of 7.33 ml/kg, and a RCV loss of 6.18 ml./kg. as compared to preoperative measurements) in the quantitative replacement of blood loss in these patients. Factors affecting the magnitude of these errors and the relative merit and dangers inherent in the use of venous and arterial pressures as a determinent of blood volume before, during and after perfusion will be discussed.

11. A Study of the Causes of 60 Deaths Following Total Cardio-pulmonary Bypass

Jean P. Despres (by invitation), Riccardo Benvenuto (by invitation),

and John C. Callaghan, Edmonton, Canada

The responsibility of numerous factors in production of death is analyzed in this series of patients. These include: (a) Patient selection - highest mortality was in cases of acquired mitral regurgitation and tetralogy of Fallot (only one death out of 76 cases of atrial septal defect and pulmonic stenosis); (b) adequacy of perfusion - a bubble oxygenator was used for the first 80 cases yielding 27 deaths. The 155 succeeding cases utilized a disc oxygenator yielding 43 deaths. However, a higher percentage of these latter cases included acquired disease; (c) proper understanding of the anatomical lesions as well as valve function; (d) technical aspects in the conduct of surgery as well as improved attention to postoperative care. The former include the matter of heart block, the type of cardiac arrest, coronary perfusion, decompression of the auricle, etc.

12. Coordinated Postsystolic Myocardial Augmentation Combined with Systolic Neutralization: Development and Clinical Application to the Failing Heart

David H. Watkins, E. R. Duchesne (by invitation),

and Byron E. Pollock (by invitation), Denver, Colo.

The experimental and clinical effects of a vascular pump on coordinated postsystolic myocardial augmentation and systolic neutralization of the proximal aortic pulse and the effect of these phenomena on the cardiac output and the work load of the myocardium will be shown. The action of this electronically coordinated electrohydropneumatic pump, and the mode of its automatic regulation by the form of the electrocardiogram or pulse wave will be described.

13. Clinical Results in Open Mitral Valvuloplasty

Joe D. Morris and Herbert Sloan, Ann Arbor, Mich.

Thirty-two patients (all clinically in class III and IV) underwent mitral valvuloplasty by open cardiotomy through the right chest in the past two years. Indications for open mitral valvuloplasty were: (1) Recurrent mitral stenosis or unsatisfactory valvuloplasty by the closed technique; (2) mitral insufficiency, pure or in combination with stenosis; (3) multivalvular disease; and (4) atrial thrombosis, embolic history, or heavy valvular calcification. There were four deaths in this series, all in class IV patients suffering refractory congestive failure. All patients surviving operation and convalescence were clinically improved, many dramatically. The technique of leaflet reconstruction and annular plication will be discussed. Problems related to exposure and the complication of air embolism will be reviewed.