OBJETIVO: Estudar bioprótese com descontinuidade do anel de sustentação, a bioprótese "Less Stented ®". O objetivo da fase 1 do trabalho foi o seu estudo "in vitro", onde foram avaliadas as características hemodinâmicas. O objetivo da fase 2 é relatar a experiência clínica inicial. MÉTODO: As biopróteses foram confeccionadas e avaliadas laboratorialmente na Braile Biomédica, em São José do Rio Preto, São Paulo. São próteses de pericárdio bovino, tratadas com glutaraldeído, segundo os mesmos padrões das próteses "stented". As próteses foram testadas no simulador de pulso e analisadas em simulador cardíaco. Foi realizada análise clínica e laboratorial (ecoDopplercardiografia e ressonância magnética) dos pacientes. RESULTADOS: A análise do gradiente pressórico transvalvar mostrou que ao longo do fluxo médio, equivalente ao débito cardíaco e que variou de 4,39 a 7,96 l/min, o gradiente transvalvar se manteve dentro de níveis clinicamente aceitáveis (6,37 a 11,62 mmHg). A curva de regressão mostrou boa correlação com o aumento de débito cardíaco com R² = 0,8291. A fração regurgitante variou de 10,95 a 17,94%, sendo que a fração de vazamento variou de 4,49 a 7,87%. Quanto ao coeficiente de descarga, ao índice de performance e ao de eficiência, verificou-se que esses parâmetros mostraram comportamento favorável com aumento progressivo do débito cardíaco, com excelente correlação tanto para o coeficiente de descarga, quanto para o índice de performance e o índice de eficiência (R² respectivamente, 0,9385; 0,9332; 0,9024). Os dois pacientes submetidos ao implante da bioprótese "Less- Stented®" apresentaram evolução clínica satisfatória. CONCLUSÃO: A bioprótese "Less-Stented®"poderá representar uma nova alternativa de substituto valvar.

OBJECTIVE: To study a bioprosthesis with discontinuation of the annular support, named the "Less Stented®" bioprosthesis. The Phase 1 objective was the "in vitro" study, during which the hemodynamic characteristics were analyzed. Phase 2 of this study consisted of an initial clinical implant protocol. METHOD: The "Less Stented" bioprosthesis consists in a glutaraldehyde treated bovine pericardium prosthesis manufactured by Braile Biomedica Ltda, São José do Rio Preto, São Paulo, Brazil, using the same manufacturing protocols as the stented bioprosthesis but with discontinuation of the annular suport. Bioprostheses were tested in a pulse simulator system and analyzed in cardiac simulator. with respect to the transvalvular gradient, regurgitant fraction and leakage volume, discharge coefficient, performance and efficiency index. The two patients of clinical protocol were analyzed according to the functional class (NYHA), an echocardiographic study and magnetic resonance, in both pre and postoperative periods. RESULTS: The transvalvular gradients ranged between 6.37 and 11.62 mmHg with a mean flow between 4.39 and 7.96 L/min, giving a good correlation (0.8291) on the regression curve with the increase in flow. The regurgitant fraction ranged between 10.95% and 17.94% and leakage volume between 4.49% and 7.87%. The discharge coefficient, performance and efficiency index showed favorable behavior with the flow increase, with good coefficient correlations for all three variables (0.9385, 0.9332 and 0.9024, respectively). The two patients submitted to "Less Stented®" bioprostheses implant presented good clinical evolutions. CONCLUSION: "Less Stented®" bioprostheses may represent a new alternative to aortic valve replacement.

OBJECTIVE: To assess the results observed during the early postoperative period in patients who had the posterior coronary arteries revascularized without cardiopulmonary bypass (CPB), in regard to the following parameters: age, sex,bypass grafts types, morbidity and mortality. METHODS: From January 1995 to June 1998, 673 patients underwent myocardial revascularization (MR). Of this total, 607 (90.20%) MR procedures were performed without CPB. The posterior coronary arteries (PCA) were revascularized in 298 (44.27%) patients, 280 (93.95%) without CPB. The age of the patients ranged from 37 to 88 years (mean, 61 years). The male gender predominated, with 198 men (70.7%). The revascularization of the posterior coronary arteries had the following distribution: diagonalis artery (31 patients, 10%); marginal branches of the circumflex artery (243 patients, 78.7%); posterior ventricular artery (4 patients, 1.3%); and posterior descending artery (31 patients, 10%). RESULTS: Procedure-related complications without death occurred in 7 cases, giving a morbidity of 2.5%. There were 11 deaths in the early postoperative period (mortality of 3.9%). CONCLUSION: Similarly to the anterior coronary arteries, the posterior coronary arteries may benefit from myocardial revascularization without CPB.