Cirurgia de Ross em crianças

Pinto, Valdester Cavalcante; Carvalho, Waldomiro; Barroso, Haroldo B; Mesquita, Fernando; Mejía, Juan Armando; Moreira, Jane Eyre Melo; Cirino, Célia M. F.; Rocha, Marilena G.; Branco, Klebia Castello; Maior, Maria M. S.; Sardenberg, Ricardo F.; Torres, João M. S.

doi:10.1590/s0102-76381999000200008

Cited by 3 publications

(2 citation statements)

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“…The gradient increase in sheep with lyophilized valves suggests that there are changes resulting in lyophilized valve replacement, as seen in the results of in vitro tests. There are references that RV-PA from 10 to 15 mm Hg are acceptable, resulting in satisfactory performance of the pulmonary valve (15,16). Comparing the gradients immediately after implantation of the lyophilized prosthesis presents similar gradient to the nonlyophilized prosthesis after 3 months of implantation when they exhibited stiff and deformed leaflets due to calcification ( Fig.…”

Section: Discussion Of In Vivo Resultsmentioning

confidence: 90%

In Vitro and In Vivo Evaluation of Lyophilized Bioprosthetic Valve

et al. 2011

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Freeze-drying of biological tissues allows for dry storage and gamma ray sterilization, which may improve their use as a medical prosthesis. The objective of this study was to evaluate the rehydration characteristics and hydrodynamic performance of prosthetic valves before and after lyophilization. Two size 23 bovine pericardium aortic valve prostheses from different manufacturers were evaluated in a Shelhigh (Union, NJ, USA) pulse duplicator (80 ppm, 5 L/min) before and after lyophilization. Flow and transvalvular pressure gradient were registered in vitro and in vivo, and images of opening and closing of the prosthesis were obtained in the pulse duplicator in a digital camera. Rehydration was evaluated by comparison of dry valve weight with valve weight after 15 min, and 1, 24, 48, and 72 h in saline solution, inside the pulse duplicator. In vivo performance was assessed by surgical implantation in Santa Inês young male sheep in the pulmonary position after 30 min rehydration with 0.9% saline. Transvalvular pressure gradient and flow measurements were obtained immediately after implantation and 3 months after surgery when valves were explanted. Captured images showed a change in the profile opening and closing of valve prosthesis after lyophilization. The gradient measured (in vitro) in two valves was 17.08 ± 0.57 and 18.76 ± 0.70 mm Hg before lyophilization, and 34.24 ± 0.59 and 30.40 ± 0.97 mm Hg after lyophilization. Rehydration of both lyophilized valves was approximately 82%. Drying changed the profile of the opening and closing of valve prostheses, and increased on average by 83% the gradient in vitro tests. The result of the in vivo tests suggests maintaining pressure levels of the animal with the lyophilized prostheses within acceptable levels.

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Section: Discussion Of In Vivo Resultsmentioning

confidence: 90%

In Vitro and In Vivo Evaluation of Lyophilized Bioprosthetic Valve

et al. 2011

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“…This suggests that 30 min of rehydration were not sufficient for complete hydration of the BP valves, causing increased rigidity in their leaflets during the initial phase, resulting in a significant difference between the two groups (P < 0.05) and possibly causing other changes in the lyophilized valvular prostheses as seen in the results of in vitro assays (20). There are, however, references that report RV/AP gradients of 10-15 mm Hg with acceptable and satisfactory performance of the pulmonary valve (21,22). After 3 months, when the valve prostheses had suffered structural damage and were stiff due to calcification, the gradients of the two groups were equivalent (P > 0.05), suggesting that the hydration process in lyophilized valves continues hours after implantation.…”

Section: Lyophilized Groupmentioning

confidence: 99%

Behavior of Lyophilized Biological Valves in a Chronic Animal Model

et al. 2013

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Glutaraldehyde is used in order to improve the mechanical and immunogenic properties of biological tissues, such as bovine pericardium membranes, used to manufacture heart valve bioprostheses. Lyophilization, also known as freeze-drying, preserves biological material without damage by freezing the water content and removing ice by sublimation. Through this process, dehydrated products of high quality may be obtained; also, the material may be easily handled. The lyophilization process reduces aldehyde residues in biological tissue previously treated with glutaraldehyde, thus promoting reduction of cytotoxicity, increasing resistance to inflammation, and possibly decreasing the potential for tissue calcification. The objective of this study was to chronically evaluate the calcification of bovine pericardium heart valve prostheses, previously lyophilized or not, in an animal model. Six-month-old sheep received implants of lyophilized and unlyophilized heart valve prostheses in the pulmonary position with right bypass. The study followed 16 animals for a period of 90 days. Right ventricle-pulmonary artery (RV/PA) transvalvular pressure gradient was evaluated before and immediately after implantation and before explantation, as were tissue calcium, inflammation intensity, and thrombosis and pannus formation. The t-test was used for statistical analysis. Twelve animals survived to the end of the experiment, but one of the animals in the control group had endocarditis and was excluded from the data. Four animals died early. The mean RV/PA gradient on implantation was 2.0 ± 1.6 mm Hg in the control group and 6.2 ± 4.1 mm Hg in the lyophilized group (P = 0.064). This mean gradient increased at explantation to 7.7 ± 3.9 mm Hg and 8.6 ± 5.8 mm Hg, respectively (P = 0.777). The average calcium content in the tissue leaflets after 3 months was 21.6 ± 39.1 mg Ca(2+)/g dry weight in the control group, compared with an average content of 41.2 ± 46.9 mg Ca(2+)/g dry weight in the lyophilized group (P = 0.478). In this experimental study there was no reduction of calcification after lyophilization. However, histological analysis showed less inflammation over the lyophilized tissue when compared with the control.

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