Abstract: Objective To examine the cell viability and hemodynamic functions of the stented homograft valves preserved in liquid nitrogen. Methods Cell viability of the stented homograft valve preserved in liquid nitrogen after 3 months of preservation (experimental group，n=6) was examined using flow cytometer. Fresh homografts served as control group (n=6). We prepared three sorts of stented homograft valve(21#, 23#, 25#) preserved by liquid nitrogen. In vitro pulsatile flow tests were performed on valves of two groups. Effective opening area EOA),transvalve pressure gradient and regurgitation ratio were recorded at various flow volume, and compare with Perfect bioprosthetic valve. Results The results revealed that the death ratio of endothelial cell was 10.24%±1.71% in the experimental group, and 9.09%±2.72% in the control group (P=0.441). The death ratio of smooth muscle cell was 8.76%±1.82% in the experimental group, and 7.84%±0.59% (P=0.178) in the control group. The death ratio of total cell was 8.79%±1.44% in the experimental group, and 7.40%±0.49% in the control group (P=0.072). There were no significantly differences between two groups. The transvalve pressure gradient of two groups of valve depended on the flow volume, and increased with the flow volume increasing. The transvalve pressure gradient of the stented homograft valve was higher than that of Perfect valve. Regurgitation ratio of the stented homograft valve was bigger than Perfect valve’s. EOA had an increasing character when flow volume increased. EOA of the stented homograft valve was smaller than that of Perfect valve’s. Conclusion Liquid nitrogen can offer the benefit of cell viability of the stented homograft bioprosthetic valves. The stented homograft valve has salisfactory hemodynamic functions.
Abstract:The use of pulmonary autograft was first reported in 1967 by Ross for the treatment of aortic valve disease in adults. Since that time, Ross procedure has been applied to a variety of forms of aortic stenosis and left ventricular outflow tract obstruction and mitral valve disease, Ross procedure has undergone several modifications, such as the root replacement method, inclusion cylinder technique, annular reduction, Konno root enlargement procedures and replacement of the mitral valve with a pulmonary autograft （Ross-Kabbani procedure or Ross Ⅱ procedure）. Advantages of Ross procedure in women of childbearing age, children and young adults include freedom from anticoagulation, appropriate sizing, cellular viability with growth potential proportional to somatic growth, acceptable long-term durability, excellent hemodynamic performance and decreased susceptibility to endocarditis. Surgical technical aspects, indications, selection criteria for the Ross procedure and its modifications, their applicability in the surgical management of aortic stenosis, left ventricular outflow tract obstruction and mitral valve disease and clinical outcome of Ross procedure are reviewed in this article.
Objective To compare the difference of effect while using homograft pericardium patch and Gore- tex patch in staged repair of tetralogy of Fallot（TOF） to enlarge the right ventricular outflow tract （RVOT）. Methods Twenty-eight patients with TOF who underwent the staged complete repair were divided into 2 groups according to the date of surgery. Gore-rex group, 13 cases, their RVOT were enlarged with Gore-tex patches. Cryopreserved homograft pericardium patch group, 15 cases, their RVOT were enlarged with cryopreserved homograft pericardium patches. Clinical results and follow-up results were compared. Results There were 1 operative death in Gore-tex patch group （7. 7%）, and 1 early postoperative death in cryopreserved homograft pericardium patch group （6. 7%）. Hemostasia time, the pericardial cavity drainage volume in cryopreserved homograft pericardium patch group were less than those in Gore-tex patch group （P〈0. 01）. All patients were followed-up for 0.8-4.5years. The residual obstruction rate at RVOT level in Gore-tex patch group was higher than that in cryopreserved homograft pericardium patch group by echocardiography （P〈0.01）. No calcification shadow was found on the chest X-ray. Conclusion Homograft pericardium is the tissue with high density and intensity, its elasticity and compliance are good. Using homograft pericardium patch may be helpful to decrease the residual obstruction of RVOT after operation. It can be adapted as a repairing material in heart surgery.
Objective To compare the effect of fabricating decellularized scaffold of homograft bioprosthetic tube valved (HBTV) with two kinds of cell detergents and to provide a homograft bioprosthetic scaffold for fabrication of tissueengineering heart valve (TEHV). Methods The active cells in the HBTV, which conserved by liquid nitrogen, were decellularized by low osmotic pressure of Tris buffer, in which containing sodium dodecylsulphate (SDS) and deoxycholic acid (DOA) respectively. The leaflets or aortic wall was fixed with fixative and stained with hematoxylin and eosin, collagen fibers or elastic fibers for observation and photographs by light microscope or by scanning electron microscope (SEM) after decellularized. Results When the leaflets of HBTV were incubated togetherwith 0.03% SDS or 0.5% DOA of Tris buffer respectively for 48 hours, the activeendothelial cells (ECs) in the leaflets were not only decellularized completely, but also reserved the collagen fibers or elastic fibers integrally, which is two of the main components of extracellular matrix (ECM). A part of fibroblast inthe center leaflets was reserved. The morphologic structure of leaflets after decellularized was not significantly different from that before decellularized. The concentration of SDS was increased to 0.1% when decellularized the cells of aortic wall, but DOA was still kept 0.5%. Conclusion The better decellularizedscaffold of HBTV obtained was disposed by 0.03%-0.1% SDS or 0.5% DOA, which wasadvantageous to adhesiveness and amplification of implantation cells on the decellularized scaffold of HBTV in order that HBV reendothelialized or for the TEHVfabricated in vitro.
This experiment consisted of removing a segment of femoral artery measuring 3cm from Japanese white rabbits. The arterial segments were divided into 3 groups and grafted as homograft at different periods of time. The segments in group 1 were grafted immediatly after their removals, those in the group 2 and group 3 were stored at -30 and -196 degrees centigrade before grafting, respectively. The results from gross and histological examinations, it was noted that following deep freezing the long term patency rate after grafting of the arterial homografts was superior to those not undergoing deep freezing. Those stored at 30 degrees centigrade for 12 weeks had the lowest patency rate.
ObjectiveExtracting the endothelial cells or all endothelial cells and interstitial cells from the cryopreserved homograft valves (HV), to evaluate the immunogenicity of this two kinds of decellular HV. MethodsFor extracting the endothelial cells, the leaflet and wall of the HV were decellularized by a 4-step detergent-enzymatic extraction method involving the 1% triton in combination with RNase (1μg/ml) and DNase (10μg/ml). For extracting the endothelial cells and interstitial cells, the leaflet and wall of the HV were decellularized by a 3-step detergent-enzymatic extraction method involving the 1% deoxycholic acid (DOA) in combination with RNase (20μg/ml) and DNase (200μg/ml). HLA-DR antigen expression was detected by using immunohistochemical techniques. The valve and wall of the HV were transplanted subcutaneously in the mice for 8 weeks, and the histology, calcium assay and calcium content were examined. ResultsFor the staining of the HLA-DR antigens, the immunogenic potential of the HV with extracting all endothelial cells and interstitial cells or only the endothelial cells was lower than cryopreserved HV, but it more obviously decreased for the HV with extracting all endothelial cells and interstitial cells. After 8 weeks embedded in the mice, the histological signs of the inflammatory reactions and the calcification extent to the cryopreserved HV and the HV with only extracting endothelial cells were stronger than the HV with extracting all endothelial cells and interstitial cells predominantly. And calcification extent or the inflammatory reactions to the wall of the HV were more severe than those of the leaflet. ConclusionsThe immunogenicity of the HV with extracting all endothelial cells and interstitial cells is much less than HV with only extracting endothelial cells. The histological signs of the inflammatory reactions and the calcification extent in vivo experiments is obviously decreased. For the HV with only extracting endothelial cells, though the histological signs of the inflammatory reactions slightly decrease, the calcification extent in vivo experiments is more severe, especially for the wall. The interstitial cells may be the important factor for the donor-reactive immune responses that is related to the graft calcification or destruction after implantation.