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A new bubble oxygenator has been developed. Its main advantage is that the dimensions of the oxygenating chamber can be varied. Thus, the capacity for oxygenation may be adapted to different patients. It was used in 2,700 open-heart operations performed at the Instituto do Coracao, Faculdade de Medicina, Universidade de Sao Paulo, between January, 1971, and December, 1973. A group of 50 patients were subjected to more detailed studies. We found that the average hemolysis was 38.67 mg. per cent with a mean perfusion duration of 69 minutes, 38 seconds. Fibrinogen and platelet concentrations decreased by 14 and 25 per cent, respectively. The pH, P co 2, P o 2, and base excess before and after cardiopulmonary bypass ranged within normal levels, and oxygenation (P o 2) was always-satisfactory.

In this paper, we shall describe a means of determining the amount of fibrinogen adsorbed to foreign surfaces in a given amount of time. Polished Stellite 21, Teflon-coated Stellite 21, and polished glass are the surfaces that were tested. We developed a contact system which allowed fibrinogen, labeled with radioiodine-125, to be dropped at a constant rate onto these surfaces. Next, the test surfaces were evaluated by spectrometry and autoradiography. The reproducibility of our findings indicates that our contact system is a valid means of determining the degree of adsorption of fibrinogen to foreign surfaces.

The case is presented of a patient with congenital tricuspid stenosis who was treated successfully by a palliative open operation. The preoperative diagnosis was tricuspid atresia. At operation, however, congenital tricuspid stenosis was detected and managed by commissurotomy. The postoperative course was very good. Later, the associated ventricular septal defect (VSD), pulmonary annular stenosis, and probably the atrial septal defect (ASD) will be corrected. We emphasize the importance of diagnosing congenital tricuspid stenosis correctly, because of the possibility of operating upon the valve itself.

A group of 533 patients had cardiac valves replaced with homologous dura mater valves. The dura mater was preserved in a solution of 98 per cent glycerol and antibiotics for a period of 12 days before use. The leaflets were mounted in a stainless steel ring covered by Dacron velour. Two hundred forty-five patients had mitral valve replacement; 205 patients, aortic valve replacement; 17 patients, tricuspid valve replacement; and 2 patients, pulmonary valve replacement. Sixty-four patients were subjected to multivalvular replacements. The patients were followed for a period of 1 to 40 months after surgery with satisfactory clinical and hemodynamic results. Because 2 patients developed endocarditis produced by fungii, fungicidal drugs were added to the preservative solution. No bacterial endocarditis has been observed. No pressure gradient through the valve has been noted at rest. Anticoagulant drugs have not been used in the postoperative period.

Normothermic anoxic cardiac arrest alters the activities of the mitochondrial enzymes in the myocardium. We have studied these alterations in 24 dogs. The animals were divided into three groups: Group I (control) consisted of 8 animals whose hearts were studied soon after anesthesia and thoracotomy. Group II included 8 dogs whose hearts were studied after being submitted to 60 minutes of anoxic arrest. The ascending aorta was clamped to produce anoxia. Group III was comprised of 8 dogs submitted to anoxic cardiac arrest for 60 minutes. The myocardium was then reperfused and cardiac activity was renewed before the hearts were studied. The following results were obtained: (1) The activity of succinic dehydrogenase, glutamic dehydrogenase, and beta hydroxybutyric dehydrogenase, in both simple and phosphorylating media, did not show statistically significant alterations after 60 minutes of anoxic arrest. (2) The activity of alpha ketoglutaric dehydrogenase in simple medium was markedly reduced by the anoxic arrest but returned to normal 60 minutes after coronary perfusion was resumed; in phosphorylating medium, however, its activity did not return to normal after cardiac recovery. (3) The activity of malic dehydrogenase in simple medium was markedly reduced by anoxic arrest and did not recover after renewed coronary perfusion.

Twenty patients with Ebstein's anomaly underwent corrective operations between 1965 and 1978. Sixteen were in Functional Class III or IV (N.Y.H.A.) and four were in Class II but were having episodes of anoxia, syncope, or a rapid increase in cardiac size. In the first 10 cases (1965 to 1972) the tricuspid valve was replaced with a Starr-Edwards prosthesis, and in the second group (1972 to 1978) a dura mater valve was used. Five patients also underwent plication of a very large atrialized right ventricular segment. The atrial septal defect was closed totally in four cases, partially in eleven cases, and left open in five cases; one patient also underwent closure of the ventricular septal defect. Four patients died in the immediate postoperative period, three of whom were in the first group. There were three late postoperative deaths in the remaining 16 patients, all of them in the first group. All 13 of the surviving patients are in Functional Class I, except for one patient who is in Class II.

We studied eight homologous dura mater valves removed 1 to 35 months after implantation. Five dura mater valves were placed in the mitral position and three in the aortic position. Two of the valves were obtained after deaths not related to the valve itself and six after reoperations due to immediate or late incompetence. In 2 cases the dura mater valves were entirely normal, both macroscopically and microscopically. In 2 other cases the leaflets were caught by stitches related to the struts, a technical error that caused laceration of the leaflets. Not withstanding this fact, the dura mater was normal on histologic examination. In 3 cases, and probably in 1 other, one or two leaflets were detached partially from the suture line, probably because of a technical error in the manufacture of the valve. These studies demonstrated satisfactory evolution of the homologous dura mater valves until 35 months after implantation. No signs of rejection or degeneration of the dura mater were observed in the present series.

The authors present the case of a fifteen-year old girl with double outlet right ventricle with ventricular d-loop and l-malposition of the great arteries, bilateral conus, pulmonary stenosis and subaortic ventricular septal defect, who was operated on successfully. This is the fourth case of double outlet right ventricle with l-position of the aorta that has been surgically corrected. The subaortic position of the interventricular defect favours the creation of the tunnel connecting the left ventricle with the aorta without obstructing the right ventricular outflow tract. The patient was doing well 11 months postoperatively.

Homologous dura-mater valve was employed in a series of 2.338 patients in the period between January 1971 and January 1979. A restricted group of the first 272 patients were followed-up from six to eight years. This study showed gratifying results following mitral and tricuspid valves replacement and not as satisfactory results after aortic replacement. The postoperative complications were, for mitral valve: fungal endocarditis (0.68%), bacterial endocarditis (2.56%) thromboembolism (1.36%) valve dysfunction (12.9%) and reoperation was performed in 5.12% of the cases. For aortic valve replacement there was fungal endocarditis in 1.36% of cases, bacterial endocarditis in 5.68%, valve dysfunction in 29.54% and the incidence of reoperation was 23.28%. No anticoagulants were employed in this series.

Subcellular changes in 12 dura mater cardiac valves (in the mitral or aortic position) surgically removed after 23 to 108 months of implantation owing to calcification, rupture, or endocarditis show signs of a remodeling process. Significant morphologic changes in the connective tissue fiber matrices and cell populations were noted in the recovered valvular leaflets. Macrophages were found within electronlucent (cleared-out) areas, and they seemed to play an essential role in the remodeling process by ingesting and digesting selected connective tissue components. Fibroblasts found within these "rebuilding" areas in the dura mater tissue possessed small cytoplasmic vesicles (65 nm in diameter) being extruded from the cell. Evidence of early collagen formation was also found in association with both peripheral filaments and peripheral condensations, as well as within the connective tissue matrices surrounding the cellular elements, where electron dense amorphous material was observed. In conclusion, the long-term durability of dura mater bioprosthetic cardiac valves may be directly related to (1) glycerin stabilization and preservation of the collagen fibers, (2) the viability of the fibroblasts and macrophages within the implanted valves, and (3) the unique morphology and fine structure of the double-layered dura mater encephali. We hypothesize that the fibroblasts or myofibroblast-like cells found within the implanted leaflets, no matter what their origin, are capable of giving form and organization to the early developing connective tissue.

This investigation used light microscopy and transmission and scanning electron microscopy to study native human and bovine parietal pericardium, ghrtaraldehyde-fixed bovine pericardial patch-grafts, and bovine pericardial cusps of unimplanted Incor or Puig-Zerbini heart valves. The primary objective was to obtain a data base for the future evaluation of postimplantation structural alteration in this valve and in other cardiac valvular bioprostheses constructed of pericardium. The mesothelial cell layer in normal pericardium was best preserved in the bovine tissue. In both bovine patch-grafts and Puig-Zerbini valvular cusps, the serosal surface usually was completely devoid of mesothelial cells and revealed an underlying, finely fibrillar basal lamina. The fibrosa varied in thickness and organization, both within and between the two species, but similar nervous, vascular, and connective tissue components were observed in each. The epipericardial surface was smoother, had fewer elastic fibers, and possessed more surface cells in the human tissue than in the bovine tissue. No evidence of significant tissue degeneration or remodeling was noted in either the stored patch-grafts or heart valves when compared with control bovine and human pericardial tissue layers.

Summary 1. Surgical correction of pure mitral stenosis under extracorporeal circulation was attended by gratifying results, with a mortality of 1.3 per cent. 2. Surgical treatment of aortic stenosis was satisfactory for the correction of congenital lesions, with a mortality of 5.3 per cent. Acquired aortic valve lesions corrected by valvulotomy and debridement had a higher mortality (19.9 per cent) and poor late results. 3. A series of 105 cases of aortic and mitral valve lesions were corrected by replacement with a Starr prosthesis, with an early and late mortality of 22.8 per cent. 4. In a group of 42 cases of aortic valve lesions, mortality was higher in patients with pure aortic stenosis. Aortic insufficiency was treated with low mortality (8.6 per cent). The mortality observed in aortic valve replacement was not increased by simultaneous open mitral commissurotomy. 5. Mitral valve replacement was performed in 43 cases with a mortality of 21.9 per cent. Myocardial failure was the outstanding cause of death. 6. In a group of 10 patients who underwent aortic and mtral valve replacement, extremely high mortality was observed. 7. Immediate and late postoperative courses of the patients in the present series are analyzed.

SUMMARY This paper summarizes the experience in the treatment of a series of 1,370 cases of open-heart surgery. Of these, 964 valvular lesions and the associated pathologic lesion are analyzed. Details of correction and immediate and late results in the treatment of the following groups of lesions were studied: 74 cases of congenital aortic stenosis; 57 cases of acquired aortic valve lesions; 514 cases of different types of mitral lesions; 123 cases of pulmonic stenosis, 95 isolated lesions and 28 with associated atrial septal defects; 221 cases of pulmonic stenosis associated with interventricular septal defect; 28 cases of persistent common atrioventricular canal, and 5 patients with interventricular septal defect complicated by aortic insufficiency.

SUMMARY In this study, 221 patients with interventricular septal defect associated with pulmonic stenosis underwent total correction. On the basis of the type of the associated pulmonic stenosis, the cases were classified into 3 groups: type I—infundibulo-valvular stenosis; type II—infundibular stenosis; and type III— valvular stenosis. The first group comprises 156 cases, or 70.5 per cent of the series. In this group, symptoms are more intense and correction is followed by a higher mortality than in the other groups. The second group of 54 patients (24.2 per cent) and the last one of 11 patients (4.9 per cent) present less severe surgical problems. The factors responsible for the decreasing mortality observed in this series are discussed. In the last group of 118 patients subjected to total correction, the mortality was 13.5 per cent.

Heart valve replacement has initiated special research efforts and has led to debate among surgeons from different surgical services. It is in this area of cardiac surgery that complications are frequent. This paper is a summarized review of the problems related to valve replacement by the Starr-Edwards prosthesis at the University of Sao Paulo Medical School Heart Institute. It describes the difficulties which led the authors to abandon its use in 1971. Clinical experience is from July 1958 to January 1974.

Six cases of coronary artery fistulae surgically treated are presented. All patient but one was male; the ages varied from 4 to 44 years. The fistulae originated from the left coronary artery in three cases from the right in two cases and from both arteries in one case. The draining heart chambers were the right atrium in three, the right ventricle in two and the pulmonary artery in one case. Associated lesions were present in three cases. One patient died on the early postoperative period and the evolution was satisfactory in five cases.

The cases of 3 patients with an aneurysm of the innominate artery treated surgically are reported. The clinical manifestations were different, and the surgical procedures employed also varied. In 1 patient, the neck of the aneurysm was isolated and clamped near the aortic arch. It was closed, and a graft was interposed between the ascending aorta and the right carotid and subclavian arteries. In the second, the aneurysm was resected under cardiopulmonary bypass, deep hypothermia, and total circulatory arrest. The neck was closed with a large Teflon patch, and a tube graft was interposed between the ascending aorta and the right carotid artery. In the third, a graft was interposed between both carotid arteries; conventional cardiopulmonary bypass was instituted, and the aorta was clamped between the innominate and the left carotid arteries. The neck of the aneurysm was closed, and a graft was interposed between the ascending aorta and the right carotid and subclavian arteries. All patients had an excellent postoperative course. Our comments regarding the clinical and surgical aspects of this condition are based on the present experience and reports in the literature.

The association of transposition of the great arteries with total anomalous pulmonary venous connection is very rare. In this report we describe 1 patient with this combination of anomalies who underwent successful repair. The patient has made an uneventful recovery.

In this report, we shall describe a case of interventricular septal defect with severe cardiac and respiratory insufficiency unresponsive to clinical treatment. The critical condition of the patient prompted us to introduce an obstructive balloon into the pulmonary artery with the objective of reducing pulmonary flow and improving respiratory insufficiency. The mean pressure was reduced from 45 to 19 mm. Hg, and the infant's cardiopulmonary status improved dramatically. After 36 hours, during which the clinical picture stabilized, a banding operation was performed with success.

The authors present the early results hi 50 cases of aortic valve homograft replacement. The homografts were sterilized and preserved in 4.0 percent formaldehyde solution buffered to a 5.6 pH, as proposed by Paneth. Aortic valve replacement only was performed in 34 cases, open mitral commisurotomy in 11 cases, and mitral valve replacement with a Starr-Edwards prosthesis in five cases. The immediate mortality was 4 percent and the late mortality was 6 percent The most important postoperative complications were myocardial infarction, transient atrioventricular block, acute bacterial endocarditis and the appearance of an aortic diastolic murmur of aortic insufficiency. The five deaths were caused by (1) cardiac arrest (2) myocardial infarction, (3) and (4) low cardiac output due to aortic incompetence, and (5) acute bacterial endocarditis.

Serum and urinary potassium variations during cardiac surgery with extracorporeal perfusion and in the immediate postoperative period were studied in 50 patients. The patients were divided into four groups: those with (1) congenital lesions; (2) cyanotic congenital lesions; (3) acquired lesions without diuretic therapy in the preoperative period; and (4) acquired lesions with diuretic therapy in the preoperative period. The uniform decrease in serum potassium during perfusion was confirmed in the four groups. In group II preoperative potassium levels were below normal range. In group IV low potassium levels were observed in the preoperative period, associated with respiratory alkalosis; subjects in this group had more instances of arrhythmias in the postoperative period than those in the other three groups. In the absence of dilutional or urinary potassium loss, the decrease in serum potassium is probably a consequence of its penetration into the body cells. Respiratory alkalosis due to anesthetic hyperventilation is an important factor contributing to this change.