| Background: Heart valve disease is a common heart disease. With the increase of valvular diseases in elderly patients who require surgical treatment, biological valve without the lifelong anticoagulation treatment is irreplaceable in valve surgery field for its good hemodynamics performance, and especially become a focus in biological valve research profession in recent years. As for the stentless biological valve ,because it can be able to adapt to the expansion of compliance of aortic root to divert the concentration of mechanical stress at the junction of leaflets when they are closed, reduce the tension at the valve free edge, the stentless aortic valve has unique advantages. Compared with the stented valve, it can obviously increase the effective valve opening area and reduce the turbulence, inter-valve pressure and the left ventricular ejection resistance as it removed the rigid stents. Its structure of no suture ring not only improves the healing of aortic root after the aortic valve replacement and reduces valve leakage and the infection rate of biological valve, but also accelerates physiological reconstruction of the aortic root and the anatomical remolding of the left ventricular morphology, in favor of the improvement of the left ventricular function. However, the endurance of stentless valve is not that good, the surgical replacement is more difficult for stentless biological valve than the stented valve, and the aortic cross-clamping time is longer during the stentless biological valve replacement, therefore a lot of scholars committed to the design of stentless valves of better performance. According to the choice of biological membrane material, the treatments of valve and the research and design of valve configuration, they performed a constant search for the stentless valves of good durability and biocompatibility, characteristic of anti-calcification and excellent hemodynamic performance.Objective: In this study, the epichlorohydrin was selected to modify glutaraldehyde for its good effect of anti-calcification and low toxicity. The influence of epichlorohydrin and glutaraldehyde treatment on the size of fresh porcine aortic root was observed, the orifice areas of porcine aortic root at different levels and the size of leaflets were measured and calculated, and the inner configuration of porcine aortic root was researched, which could provide the reference for the stentless aortic valve design.Methods: The orifice areas(OA1～4) of porcine aortic root at 4 levels, i.e. 1cm above the sinotubular junction (STJ1) and at the sinotubular junction(STJ0), aortic sinus(SINUS) and base (BASE) level and the size of leaflet were measured and calculated respectively in the fresh group and the treated group of epichlorohydrin and glutaraldehyde. The size of leaflets includes the leaflet height(H), the length of free edge(Lf) and attached edge(La), leaflet perimeter(P) and area of leaflets(square, S) Each group contained 20 porcine aortic root. The influence of epichlorohydrin and glutaraldehyde treatment on the dimension variations of fresh valves was studied. In addition, the average area of leaflets (average square, Sa), the area analogue of leaflets (AA,AA=1/2PH),the average area analogue of leaflets(AAa). And the product of perimeter and height (PH) was calculated. The value PH of the left, right, non coronary leaflets (PHl, PHr, PHn) and the sums of PHs of the left and non-coronary leaflets (PHln) in both groups were measured and calculated. The linear correlation and regression analysis by SPSS12.0 was used to analyze the correlation between Sa and AAa, OA and Sa, OA and AAa, PHl, PHr and PHn, PHln and PHr in both groups. The linear correlation and regression between the value PH of the right coronary leaflet and the sums of PHs of the left and non-coronary leaflets was further analyzed, and the equation of linear correlation and regression between PHln and PHr was drawn in both groups. In the end, the 95% prediction interval of PHr was described, by which the value PH of the right coronary leaflet could be predicted by PHln.Results:1.At STJ1,STJ0,SINUS,BASE level, the orifice areas of the fresh valves were respectively 2.33±0.41 cm2,2.18±0.45 cm2,4.07±0.54 cm2,2.48±0.36 cm2,and that of the treated valves were respectively 2.30±0.31 cm2,1.98±0.40 cm2,3.92±0.71 cm2,2.47±0.32 cm2.The orifice areas of both groups conformed to the pattern as follows: SINUS> BASE > STJ1> STJ0(P < 0.05);all the dimensions at four levels in fresh group were larger than that of treated group, without the statistical difference (P<0.05).2.The cusp areas of the fresh group were respectively 3.10±0.44 cm2,3.41±0.46 cm2,2.54±0.32 cm2,following the laws: right coronary cusp(R)>left coronary cusp(L)>non-coronary cusp(N)(P <0.05),and that of the treated group were 2.26±0.32 cm2,2.49±0.47 cm2,2.04±0.35 cm2, following the similar patterns, but statistical significance only existed between the right and non coronary leaflets(P<0.05).3.The coefficient correlation between Sa and AAa in fresh and treated groups were 0.886 and 0.872 respectively, P<0.05;the coefficient correlation between OA1～4 and Sa were 0.832,0.804,0.875,0.862 respectively in fresh group, P<0.05, and were 0.836,0.825,0.832,0.835 respectively in treated group, P<0.05 ; the coefficient correlation between OA1～4 and AAa were 0.810,0.851,0.900,0.815 respectively in fresh group, P<0.05, and were 0.852,0.888,0.836,0.817 respectively in treated group, P<0.05.This showed that the degree of correlation between the average area analogue of leaflets and the average area of leaflets, the orifice areas of aortic root were relatively high.4. The coefficient correlation between PHl and PHr, PHl and PHn, PHr and PHn were 0.817, 0.828, 0.835 respectively in fresh group, P<0.05, and were 0.895, 0.837, 0.845 respectively in treated group, P<0.05. This showed that the degree of correlation among the value PHs of the left, right and non-coronary valves were relatively stable and high. Additionally, the linear correlation and regression existed between the sums of PHs of left and non-coronary leaflets (PHln) and the value PH of right coronary valve(PHr) in both groups. And the values of PHr and PHln were in line with the equation of linear regression as follows: PHr=0.079+0.574PHln ( r=0.861 , P<0.05 ) in fresh group, and PHr=-1.665+0.688PHln(r=0.907,P<0.05)in treated group. Thereby, the value PH of right coronary leaflet could be predicted by the sums of PHs of left and non-coronary leaflets in treated group by the 95% prediction interval of PHr.Conclusion: 1.The influence of epichlorohydrin and glutaraldehyde treatment on the dimension variations of aortic wall of valves was not obvious, but it made the size of leaflets change statistically. Therefore, the relative spatial configuration between porcine aortic wall and leaflets changed after the treatment.2. The value PH of porcine aortic leaflets could represent the 2D information of the aortic leaflets (the area of leaflets) and the aortic root structure(the orifice area)in both fresh and treated valves. Thus the value PH could represent the spatial configuration of the aortic root, which provided a referenced index for the stentless biological valve design.
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