Heart valve

Abstract

A heart valve is at least partially constructed from a block-copolymer, the block-copolymer having a phase structure formed by its constituent blocks, and wherein the phase structure is arranged so as to produce anisotropic physical properties in the heart valve.

What is claimed is: 
     
         1 . A heart valve, at least partially constructed from a block-copolymer, the block-copolymer having a phase structure formed by its constituent blocks, and wherein the phase structure is arranged so as to produce anisotropic physical properties in the heart valve. 
     
     
         2 . The heart valve according to  claim 1 , wherein the heart valve comprises leaflets for actuating the valve, and the leaflets are made from the block-copolymer with the arranged phase structure. 
     
     
         3 . The heart valve according to  claim 1 , wherein the block copolymer forms a phase structure comprising cylinders of a first polymer material in a matrix of another polymer material. 
     
     
         4 . The heart valve according to  claim 3 , wherein the first polymer material is a glassy polymer at body temperature and the second polymer material is a rubbery polymer at body temperature. 
     
     
         5 . The heart valve according to clam  4 , wherein the block-copolymer is one of SIBS30 (poly(styrene-block-isobutylene-block-styrene), 30% styrene); SIS30 (poly(styrene-block-isoprene-block-styrene), 30% styrene); SI/BS19 (poly(styrene-block-isoprene/butadiene-block-styrene), 19% styrene); SIS18 (poly(styrene-block-isoprene-block-styrene), 18% styrene); SE/BS30 (poly(styrene-block-ethylene/butylene-block-styrene), 30% styrene); SE/BS20 (poly(styrene-block-ethylene/butylene-block-styrene), 20% styrene); SE/PS20 (poly(styrene-block-ethylene/propylene-block-styrene), 20% styrene); and SE/PS22 (poly(styrene-block-ethylene/propylene-block-styrene), 22% styrene). 
     
     
         6 . The heart valve according to  claim 1 , wherein the phase structure is arranged to produce layers in which the phase structure is differently aligned in neighbouring layers. 
     
     
         7 . The heart valve according to  claim 6 , wherein the layers include two outer layers in which the phase structure is aligned substantially perpendicularly to the phase structure within the inner layer. 
     
     
         8 . The heart valve according to  claim 7 , wherein the total thickness of the two outer layers is from 25% to 75% of the thickness of the heart valve. 
     
     
         9 . A method of manufacturing a heart valve, the method comprising:
 a step of injection moulding at least one part of the heart valve from a block-copolymer, wherein the injection moulding is performed at a temperature below the order-disorder transition temperature for the block copolymer, such that a phase structure is present in the molten block-copolymer;   a step of cooling the at least one part of the heart valve after it is moulded, without heating the at least one part above the order-disorder transition temperature between the step of injection moulding and the step of cooling, so as to preserve an arrangement of the phase structure created during the step of injection moulding and produce anisotropic physical properties in the heart valve.   
     
     
         10 . The method of manufacturing a heart valve according to  claim 9 , wherein the step of injection moulding includes the use of a mould with injection moulding points positioned at the top and/or base of one or more leaflets of the heart valve. 
     
     
         11 . A method of designing a mould for injection moulding a heart valve from block copolymer below the block copolymer's order-disorder transition temperature, the method comprising
 modelling at least a section of a heart valve produced by the mould, including modelling the stresses in the valve and accounting for the orientation of the phase structures within the block copolymer;   changing the injection position of the block copolymer in the model of the mould, and remodelling the at least a section of the heart valve;   selecting an injection position, based on the modelling and remodelling, that provides the least stress concentration in the valve; and   producing a mould with the injection position in the position that provides the least stress concentration in the valve.   
     
     
         12 . A method of producing anisotropic physical properties in a solid block copolymer, the method comprising:
 a step of injection moulding the block-copolymer at a temperature below the order-disorder transition temperature for the block copolymer, without lubricant, such that a phase structure is present in the molten block-copolymer;   a step of cooling the molten block-copolymer after it is moulded, without heating the block-coploymer above the order-disorder transition temperature between the step of injection moulding and the step of cooling, so as to preserve an arrangement of the phase structure created during the step of injection moulding and to produce anisotropic physical properties in the heart valve.   
     
     
         13 . A solid block copolymer material, the block-copolymer having a phase structure formed by its constituent blocks, wherein the phase structure is arranged to produce layers in which the phase structure is differently aligned in neighbouring layers. 
     
     
         14 . A medical prosthetic, at least partially comprising a solid block copolymer material according to  claim 12 .