Evidence of remodeling in dura mater cardiac valves.

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.

Homologous dura mater cardiac valves. Structural aspects of eight implanted valves.

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.

Microscopic study of normal parietal pericardium and unimplanted Puig-Zerbini pericardial valvular heterografts.

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.

Inferior epigastric artery as a free graft for myocardial revascularization.

The inferior epigastric artery was used as a free graft for direct myocardial revascularization in 22 patients from October 1987 to July 1988. The artery was used either alone or along with internal mammary artery or saphenous vein grafts. The inferior epigastric artery was dissected through an infraumbilical incision without entrance into the peritoneal cavity. The results depend on the technique used for the aortoepigastric anastomosis. When a segment of saphenous vein or a patch of bovine pericardium was sutured to a large aortic orifice with the inferior epigastric artery previously anastomosed to these patches, the patency rate of the free grafts in the early postoperative period was 100%. Histologic examination showed identical structure of the inferior epigastric artery and the internal mammary artery. Application of the inferior epigastric artery is an attempt to increase the use of arterial grafts for myocardial revascularization.

Homologous dura mater cardiac valves. Study of 533 surgical cases.

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.

Tricuspid dura mater bioprostheses: more than 20-year follow-up of 3 patients.

Replacement of the tricuspid valve is sometimes necessary. We report 3 consecutive patients with tricuspid insufficiency who underwent valve replacement with glycerol-preserved, homologous dura mater cardiac bioprostheses between 1971 and 1973. The first 2 patients are well 28 and 27 years later; the last patient was lost to follow-up after 20 years. We conclude that preservation of homologous dura mater bioprostheses in glycerol may reduce rates of thromboembolism, thrombosis, and structural dysfunction during the late postoperative period.

A technique of anastomosis of the right internal mammary artery to the circumflex artery and its branches.

A new technique for direct revascularization of the left circumflex artery and its ventricular branches through anastomosis with the right internal mammary artery (RIMA) was applied in 56 patients. Postoperative angiographic studies in 17 patients showed that positioned behind the aorta, the RIMA can reach the circumflex artery with no tension, allowing adequate distal filling.

Right internal thoracic artery through the transverse sinus in myocardial revascularization.

BACKGROUND: This study presents the late patency rate of the right internal thoracic artery (ITA) used in situ through the pericardium transverse sinus to the circumflex artery and its branches. METHODS: From April 1983 to December 1994, 2,642 patients were submitted to myocardial revascularization; 201 of them had bilateral ITAs. The right ITA through the transverse sinus was grafted to obtuse marginal artery in 170 patients (84.5%) and the left ITA was grafted to the anterior descending artery in 188 patients (93.5%). Angiographic studies were performed in 80 patients, 44 patients in the immediate postoperative period and 36 patients in the late follow-up (mean, 51.6 months). RESULTS: The right ITA was patent in 75 patients (93.7%) and the left ITA was patent in 77 (96.2%). At the late postoperative period, the right ITA was patent in 33 patients (91.6%) and the left ITA was patent in 34 (94.4%). CONCLUSIONS: The right ITA placed through the pericardium transverse sinus has a good long-term patency rate, similar to that observed with the left ITA and superior to that of saphenous vein grafts for myocardial revascularization.

Eight years experience using the inferior epigastric artery for myocardial revascularization.

We present the initial experience with the use of inferior epigastric artery as a free graft for myocardial revascularization in a series of 41 patients operated on between 1987 and 1989 to show the clinical and angiographic results. Of the 41 patients, 29 were male, 12 female, with ages ranging from 33 to 72 years, and weights from 50 to 86 kg. The inferior epigastric artery grafts were predominantly employed to the anterior interventricular branch and diagonal branch. The proximal anastomosis into the aorta was done directly or with a patch of vein or pericardium. The 32 patients who survived had mean follow-up of 82 months and 22 are in functional class I, 8 in class II and 2 in class III of angina. The early patency rate was: inferior epigastric artery-anterior interventricular branch, 85.7% and inferior epigastric artery-diagonal branch. 85.7%. Sixteen patients underwent angiographic study at a mean follow-up of 81.2 months and the patency rate to the anterior interventricular branch was 77.7% and to the diagonal branch was 100%. Three patients with early occluded inferior epigastric artery were reoperated on 3, 3 and 11 months after the operation. A filiform lumen of the graft and a small ostium in the aorta was found and explained the imperfection of the direct anastomosis due to unbalance thickness of the graft and the aortic wall. Therefore it is occluded that the inferior epigastric artery is an alternative arterial graft for myocardial revascularization and that the use of a vein or pericardium patch can help the proximal anastomosis and improve potency of the graft.

Early experience with crimped bovine pericardial conduit for arterial reconstruction.

A bovine pericardial conduit was developed in the laboratory incorporating the principle of crimping used for synthetic vascular prostheses. The pericardium was processed in glutaraldehyde and the tube was crimped by a technique which preserves the integrity of collagen fibres. This vascular substitute presents a non-thrombogenic and non-porous inner surface which does not require preclotting and does not leak. The material is very soft, easy to handle and suture, coapts nicely to suture lines resulting in a hemostatic anastomosis. The crimping design provides longitudinal elasticity and resistance to collapsing, retains its shape with bending and avoids kinking. Crimping provides a circular tube which makes the construction of the anastomosis easier. Experimental studies in dogs demonstrated absence of thromboembolism with the conduit implanted in the abdominal aorta. Fibrin accumulation was not noted in the convexities of the crimps. This conduit was designed for aortic and pulmonary reconstruction and available in different sizes with or without a biological valve. Initial clinical experience included its use in 10 patients with aortic dissections or aortic aneurysms from August 1989 to March 1990. A reconstruction of the abdominal aorta was performed in 2 patients, the descending thoracic aorta in 2, the ascending aorta in 2 and the ascending aorta including the aortic valve and reimplantation of coronary arteries in 4. For the latter 4, composite crimped pericardial tubes containing a porcine bioprosthesis were used. An additional patient with a single ventricle underwent a Fontan type operation also employing a valved crimped pericardial conduit.(ABSTRACT TRUNCATED AT 250 WORDS)

Four years experience with dura mater cardiac valves.

The clinical use of homologous dura mater cardiac valves was begun in January 1971. Between January 1971 and May 1975, 751 patients received 849 dura mater valves: 428 mitral, 365 aortic, 52 tricuspid and 4 pulmonary. The hospital mortality observed in this series was 13.6% and late mortality was 2.5%. The main causes of death were low-output syndrome in the immediate post-operative period or cardiac failure in the late post-operative period, due to myocardial impairment. Paravalvular leaks and errors in the manufacture of the valve were the main causes of regurgitation both in the immediate and late post-operative period. The incidence of thromboembolism, bacterial and fungal endocarditis was: 0.79%, 0.39%, 0.53% respectively. The results obtained with dura mater valve in a period of four years are satisfactory from the clinical and hemodynamic points of view.

Late results of replacement of cardiac valves by dura-mater allografts.

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.

Mitral valve repair. Quadrangular resection of the posterior leaflet in patients with myxomatous degeneration.

OBJECTIVE: To analyze the immediate and late results of mitral valve repair with quadrangular resection of the posterior leaflet without the use of a prosthetic ring annuloplasty. METHODS: Using this technique, 118 patients with mitral valve prolapse who underwent mitral repair from January '84 through December '96 were studied. Age ranged from 30 to 86 (mean = 59.1 +/- 11.8) years and 62.7% were males. An associated surgery was performed in 22% of the patients, and coronary artery bypass graft was the most frequently performed surgery (15 patients--12.7%). In 20 (16.9%) patients other associated techniques of mitral valve repair were used and shortening of elongated chordae tendineae was the most frequent one (6 patients). RESULTS: Immediate mortality was 0.9% (one patient). Long-term rates for thromboembolism, endocarditis, reoperation and death in the late postoperative period were 0.4%, 0.4%, 1.7% and 2.2% patients/year, respectively. The actuarial curve of survival was 83.8 +/- 8.6% over 12 years; survival free from re-operation was 91.8 +/- 4.3%, free from endocarditis was 99.2 +/- 0.8% and free from thromboembolism was 99.2 +/- 0.8%. In the late postoperative period, 93.8% of the patients were in functional class 1 (NYHA), with a complete follow-up in 89.7% of the patients. CONCLUSION: Patients with mitral valve prolapse who undergo mitral valve repair using this technique have a satisfactory prognosis over 12 years.

[The use of left and right internal thoracic artery grafts for revascularization of the left coronary artery]. / Uso das artérias torácicas internas esquerda e direita na revascularização da artéria coronária esquerda.

PURPOSE: To analyze the late results of patients who underwent left coronary myocardial revascularization with both internal thoracic arteries, with the right internal thoracic through the transverse sinus. METHODS: From July/83 to September/96, 233 patients underwent myocardial revascularization, with ages ranging from 35 to 76 (average of 52.8) years. One hundred and eighty five were male and 48 female. Internal thoracic arteries (466), saphenous veins (192) and epigastric arteries (11) were employed. RESULTS: The hospital mortality was 3% and the late mortality was 6.1%. The immediate postoperative bleeding was 0.8%, mediastinitis 1.7% and myocardial infarction 2.1%. The immediate and late coronariography showed the rates of patency, respectively: left internal thoracic artery 98% and 96%, right internal thoracic artery 96% and 92, and saphenous vein grafts 80% and 67.5%. CONCLUSION: The main advantage in using both internal thoracic arteries in the revascularization of the left coronary branches was the better quality of life, the low rates of cardiac events and the absence of reoperation due to occlusion of the grafts.