Análise Do Comportamento Hidrodinâmico In Vitro Dos Implantes De Próteses Valvares Transcateter Dentro De Biopróteses Aórticas Convencionais: Uma Nova Alternativa À Reoperações

Abstract

OBJECTIVE: Hydrodynamic evaluation of the transcatheter valve implantation in aortic bioprosthesis (valve-in-valve) and in sets of bioprosthesis with a transcatheter valve previously implanted (valve-in-valve-in-valve or sequential valve-in-valve), in order to guide therapeutic limits and the optimal transcatheter valve size. METHODS: With the Pulse Duplicator, and accordingly to FDA and ISO 5840 determinations for cardiac output (5L/min), mean arterial blood preesure (100mmHg) and cardiac frequency variation (70-120), the hydrodynamics tests were procedded to measure efective orificial area (EOA-cm²) and transvalvar gradient (ΔP-mmHg) for each set of valve-in-valve and valve-in-valve-in-valve. The valve-in-valve tests: for each bioprosthesis (Braile Biomédica), between 19mm and 25mm, a transcatheter valve (Braile Inovare, with nominal sizes between 20 and 26mm), either 1mm larger or 1mm smaller, was implanted. The valve-in-valve-in-valve tests: for each optimal set of valve-in-valve (determined in the valve-in-valve tests), a transcatheter valve 2mm smaller than the previous was implanted. Each set described of valve-in-valve or valve-in-valve-in-valve was replicated ten times, and the tests in the Pulse Duplicator were performed for each set three times. RESULTS: The set aortic bioprosthesis 19mm and transcatheter valve 20mm, the EOA was 0,5 and the ΔP was 43,7. Moreover, the sets 21-20 and 21-22 resulted in EOA 0,8 and 0,73, and ΔP 19,4 and 23,4. For the sets 23-22 and 23-24, the tests showed EOA 1,06 and 0,8, and ΔP 12,5 and 19,5. And finally, for the sets 25-24 and 25-26, the EOA was 1,085 and 1,0, and the ΔP was 11,76 and 13,56. The valve-in-valve-in-valve tests has shown that the implantation of a transcatheter valve 22mm in a valve-in-valve set of a 25mm bioprosthesis with the 24mm valve transcathter resulted in EOA 0,99 and ΔP 13,59; when for this set was proceeded the implantation of a third transcatheter valve (20mm), was observed an EOA 10 0,84 and a ΔP 15,31. In a valve-in-valve set with a 23mm bioprosthesis and a 22mm transcatheter valve, the EOA was 0,86 and the ΔP was 15,62 when a 20mm transcatheter valve was implanted. CONCLUSION: The aortic valve-in-valve is fasible, with better hydrodynamic results when the transcatheter valve has the nominal size 1mm smaller than the bioprosthesis; this fact can be explained considering the appropriate oversizing between the bioprosthesis true internal diameter and the transcatheter external diameter (between 10 and 20%). The valve-in-valve in 21mm bioprosthesis should be individualized, and in 19mm prohibited. The transcatheter valve-in-valve-in-valve is feasible as well, with great performance with a sequential implantation of a smaller transcatheter valve up to the 22mm, the 20mm should be cautiously implanted; the oversizing between the immediate smaller transcatheter valve was between 4 and 5%.

OBJETIVO: Avaliação hidrodinâmica do implante de valva transcateter no interior de biopróteses aórticas convencionais (“valve-in-valve”) e de conjuntos de bioprótese com valva transcateter previamente implantada (“valve-in-valve-in-valve ou “valve-in-valve sequencial”), delimitando limites terapêuticos e o melhor tamanho de valva transcateter a ser implantada. MATERIAL E MÉTODOS: Com o Duplicador de Pulsos, seguiu-se especificações do FDA e ISO 5840 para débito cardíaco (5L/min), pressão arterial média (100mmHg) e variação de freqüência cardíaca (FC:70-120bpm), calculando-se EOA (cm²) e ΔP (mmHg). Para os testes valve-in-valve, com cada bioprótese aórtica (Braile Biomédica), entre 19 e 25mm, implantou-se uma valva transcateter (Braile Inovare, de tamanhos 20 a 26mm), 1mm maior e 1mm menor, a fim de delimitar o melhor tamanho a se eleger. Para os testes de valve-in-valve-in-valve, para cada conjunto valve-in-valve mais adequado no teste prévio, alocou-se uma valva transcateter imediatamente menor. Para cada teste proposto, replicou-se 10 conjuntos valve-in-valve/valve-in-valve-in-valve, repetindo-se o ciclo no duplicador de pulsos para cada conjunto 3 vezes. RESULTADOS: Para os testes valve-in-valve, com o conjunto de bioprótese aórtica 19mm e válvula transcateter 20mm, observou-se EOA 0,5 e ΔP 43,75. Com conjuntos 21-20 e 21- 22, resultou-se em EOA 0,8 e 0,73 e ΔP 19,46 e 23,41. Nos conjuntos 23-22 e 23-24, houve EOA 1,06 e 0,8 e ΔP 12,5 e 19,5 Para conjuntos 25-24 e 25-26, notou-se EOA 1,085 e 1,0 e ΔP 11,76 e 13,56. No testes valve-in-valve-in-valve, em conjunto valve-in-valve com bioprótese 25 e valva transcateter 24, quando do implante de valva tanscateter 22 observou-se EOA 0,99 e ΔP 13,59 e após, com implante sequencial de valva transcateter 20, houve EOA 0,84 e ΔP 8 15,31; por fim, em conjunto valve-in-valve com bioprótese 23 e valva transcateter 22, quando implantou-se a valva transcateter 20, detectou-se EOA 0,86 e ΔP 15,62. CONCLUSÃO: O implante valve-in-valve aórtico é factível, havendo melhor desempenho hidrodinâmico com a valva transcateter de tamanho nominal 1mm menor em relação à bioprótese; tal fato se deve à adequação do sobredimensionamento (oversizing) entre o diâmetro interno real da bioprótese e o diâmetro externo da valva transcateter (mantendo-se entre 10 e 20%). Esta modalidade deve ser utilizada com restrições em bioprótese 21 e evitada em bioprótese 19. O implante transcateter sequencial (valve-in-valve-in-valve) aórtico é igualmente factível em testes hidrodinâmicos, com bons resultados até a valva transcateter 22, e havendo restrições com o uso da valva 20. O sobredimensionamento observado foi entre 4 e 5% comparativamente ao implante de valva transcateter em outra já implantada.