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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 Institut do Coracão, Faculdade de Medicina, Universidade de São 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, PcO2, PO2, and base excess before and after cardiopulmonary bypass ranged within normal levels, and oxygenation (PO2) was always satisfactory.

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.

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.

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 used. 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.

This investigation used light microscopy and transmission and scanning electron microscopy to study native human and bovine parietal pericardium, glutaraldehyde-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.

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.

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.

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.