| Acquired valvular heart disease is one of the most common cardiac disease, valve replacement is the most effective method. There are two types of heart valve prosthesis used in clinic now, mechanical valve and bioprosthetic valve. Mechanical prosthetic valve has the advantages of predominant durability, easy to handle, but it needs lifelong anticoagulation for furthermore. Haemodynamics performance after implanted is not atisfactory. Bioprosthetic valve is made with reshaped biological tissue. It has good biocompatibility, with no need for anticoagulation after implanted. Blood current through the valve orifice is central flow. Haven't central occluder, haemodynamics performance is atisfactory. But bioprosthetic valve easily turn to calcify, tear and degenerate. These reasons make its life decurtate and limit its applicatin in clinic. There are two types of bioprosthetic heart valve:stent and stentless. Stent one is simple handling and complicate valve insufficiency less, but stent valve doesn't analogue the native valve, the maximal stress effect centralize in the valval root. These may cause the mechan- defatigation and collagen breakage to lead to laceration and perforation. Stentless valve removes hard frame and abates deterioration leaded by blood flow. The bigger valve orifice can be used when implanting because there isn't frame and the better hemodynamic properity come on. The clinical effect and durability of both stent and stnetless valves after operation still need to further observe.In valve replacement operation is suture method a important factor which effects the duration of operation. There are usual intermittent or continuous suture, or mixd sutures with intermittent and continuous methods. Double layer suture at inflow tract and outflow tract have been used widespreadly in stentless valve replantment need more time, but single layer suture method for stentless valve replantment reguires study to date.Objective:to shorten duration of valve replacement and to improve valval properity. To develop a new type of single suture stentless porcine aortic valve on base of refining valve design with porcine aortic root configuration.Method:1 Preparation for new type single layer suture stentless porcine aortic valve: Porcine valves are treated with dutaraldehyd and epichorohydrin and the method is similar to that of the previous stentless porcine aortic valve in our laboratory. The new valve tailor is performed nearby valve ring at the inflow and outflow tract .Bovine pericardium strip is sutured on the outside of valve ring to make it firm and convenient replacement.The natural configuration be careful to retain.2 Suture methods of implanting newtype single layer suture stentless valve Used single layer suture, every suture needle should pentrate valve ring from the outflow tract to inflow tract, then the stentless valve is putted dowing and tied to acceptor's valve ring.3 Analogous aortic valve replacement compare single layer with double layer with double layer sutures in vitro: The new type stentless porcine aortic valve are implanted on porcine aortic root with single layer suture for 6 times, and with double layer suture implanting XJ stentless porcine aortic valve on the porcine aortic root for 4 times, then the operative duration, feasibility and suture quality are compared between the two analogous suture methods.4 Hydromechanics test of single layer suture stentless porcine aortic valve in vitro.6 stentless porcine aortic valve divided into 2 groups according to the different suture method. Either single layer suture valve in new stentless porcine aortic valve group or double layer suture valve in previous stentless porcine aortic valve group all inplant in the bovine pericardial conduit,and each group contains 3 valves 23mm,25mm and 27mm size.Experiment's condition: carry out ISO5840 and GB-12279-2000 valve detect standard.Statistical analyses use SPSS 11.5 software. Result for demonstrate with mean±standard deviation, use independent sampler t analysis.5 Durability of Single layer suture stentless porcine aortic valve in vitro. After detecting hydromechanics of valve in vivo accelerating defatigation test is performed. Experiment's condition complied ISO5840 and GB-12279-2000 valval detect standard. to observe valve's appearance and detect hydromechanics again after the test.Result: 1 Result of analogue aortic valve replacement in vitro.About use the duration of analogous single layer suture for new stentless porcine aortic valve implantation take average 50min and that of analous double layer suture for XJ stentless porcine aortic valve take average 70min in vitro.2 Result of hydromechanics test for new single layer suture stentless porcine aortic valve in vitro.①Result of the test for△P,△P increased with the CO augment.23mm and 27mm size valve's△P in single layer group are smaller than the same size in double layer group in the condition which the CO is 5.0L/min (23mm_ P=0.001,27mm_ P=0.008,P<0.01);the contrast of△P between two groups in other conditions hasn't statistical meaning(P>0.01).②Result of the test for EOA, EOA increased with the CO augment.23mm and 27mm size valve's△P in single layer group are smaller than the same size in double layer group in the condition which the CO is 5.0L/min (23mm_ P=0.001,27mm_ P=0.001,P<0.01);the contrast of EOA between two groups in other conditions hasn't statistical meaning.about utility valve orifice's area,the contrast between two groups hasn't statistical meaning(P>0.01).③percentage of reverse flow about the valves in two groups are smaller than 5.12±0.22%, complied ISO5840 valval detect standard(<10%).3 The durability of single layer suture layer suture stentless porcine aortic valve isn't perforation; laceration; abrasion and deformation etc after 50×106 cycle times.The results show that△P after the test is larger than data before the test in the condition which CO is 5.0L/min (P=0.006), the contrast in△P, EOAbetween forward and after test hasn't statistical meaning. complied ISO5840 valval detect standard. Conclusion:The newtype stentless porcine aortic valve after mimical implantation retain satisfactory hydromechanics performance for the aortic root of the acceptor.Time for implantation has been decurtated. The contrast in△P, EOA and F% between single layer group and double layer group hasn't statistical meaning. inartificial architecture and favourable. Neotype Single layer suture decurtate This experiment make the foundation for animal experiment.
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