Prosthetic heart valve

1. A prosthetic heart valve for implantation at a mitral annulus of a heart, the prosthetic heart valve comprising:

a support framework reversibly transformable between a collapsed configuration and an expanded configuration; and

one or more leaflets connected to the support framework;

wherein, in the expanded configuration:

the support framework defines a fluid pathway through the prosthetic heart valve, the support framework having a portion for engaging the mitral annulus, said portion defining a D-shaped cross section of the fluid pathway;

the one or more leaflets allow fluid to pass through the fluid pathway in a first direction but prevent fluid from flowing in the opposite direction; and

a tension adjusting mechanism at the portion with the D-shaped cross section of the support framework to provide flexibility in the size of the support framework when in the expanded configuration;

the support framework further being a wire frame bent into a plurality of loops, wherein the plurality of loops of the support framework includes two petal-shaped loops which extend from the portion with the D-shaped cross section at a first side of the one or more leaflets;

wherein in the collapsed configuration, the petal-shaped loops collapse into elongate arms, a length of one elongate arm being longer than a length of the other arm.

2. The prosthetic heart valve of claim 1 , wherein the portion of the fluid pathway comprising the D-shaped cross section includes a saddle-shaped frame structure, the saddle-shaped frame structure having the D-shape when viewed along the axis of flow of the fluid pathway.

3. The prosthetic heart valve of claim 1 , having no more than two leaflets.

4. The prosthetic heart valve of claim 1 , wherein the plurality of loops of the support framework includes two crown-structures which extend from the portion with the D-shaped cross section at the opposite side of the leaflets to the petal-shaped loops.

5. The prosthetic heart valve of claim 4 , wherein in the B collapsed configuration, the crown structures may collapse into elongate crown arms, a length of one elongate crown arm being longer then a length of the other elongate crown arm.

6. The prosthetic heart valve of claim 1 , further comprising an additional loop at the apex of one or more of the plurality of loops for reducing tension at the apex during transformation between the expanded and collapsed configurations.

7. The prosthetic heart valve of claim 1 , wherein a first one of the petal-shaped loops is a petal-shaped loop of a first size and a second one of the petal-shaped loops is a petal-shaped loop of a second size, the second size having a larger area than the first size.

8. The prosthetic heart valve of claim 7 , wherein the tension adjusting mechanism is a gap in the support framework.

9. The prosthetic heart valve of claim 1 , wherein the tension adjusting mechanism is a portion of wire which acts as a spring.

10. The prosthetic heart valve of claim 1 , comprising a cuff attached to the support framework, the cuff providing a seal around at least a portion of the fluid pathway to prevent paravalvular leakage.

11. The prosthetic heart valve of claim 10 , wherein the cuff comprises a first cuff portion which extends around half of the circumference of the support framework and a second cuff portion which extends around the other half of the circumference of the support framework.

12. The prosthetic heart valve of claim 1 , comprising a skirt attached to the support framework.

13. The prosthetic heart valve of claim 12 , wherein the skirt is a mesh.

14. The prosthetic heart valve of claim 12 , wherein the skirt comprises a first skirt portion which extends around half of the circumference of the support framework and a second skirt portion which extends around the other half of the circumference of the support framework.