Aortic valve prosthesis having natural tissue and an internal cover

1. A prosthetic valve assembly for replacing a stenotic native aortic valve in a patient, comprising:

a metallic frame having an inlet end, an outlet end and an internal surface, the metallic frame having a concave profile and constructed with sufficient radial strength for resisting the recoil forces of the stenotic native aortic valve;

a flexible valvular structure having open and closed positions, the valvular structure sewn directly to the frame along a coupling region between the inlet and outlet ends of the frame, the valvular structure adapted for permitting blood to flow in one direction, the valvular structure formed of pericardial tissue and positioned entirely between the inlet and outlet ends of the frame when in the closed position; and

an internal cover having an inlet end and an outlet end, the internal cover sewn to the frame along the internal surface and contacting the internal surface only between the inlet end of the frame and the valvular structure for preventing blood from flowing laterally through gaps in the frame between the inlet end of the frame and the valvular structure while permitting blood to flow laterally through gaps in the frame between the valvular structure and the outlet end of the frame, the internal cover comprising pericardial tissue and disposed only along the internal surface of the frame, the inlet end of the internal cover sewn to the inlet end of the frame, the outlet end of the internal cover sewn to the valvular structure adjacent the coupling region between the inlet and outlet ends of the frame;

wherein the frame is collapsible for advancing the prosthetic valve assembly through a patient's vasculature using a catheterization technique and wherein the frame is expandable for maintaining the native aortic valve in an open state and supporting the valvular structure.

2. The prosthetic valve assembly of claim 1 , wherein the inlet end of the internal cover has a zig-zag shape and the inlet end of the frame has a zig-zag shape and wherein the inlet end of the internal cover is sewn to the inlet end of the frame along a zig-zag line.

3. The prosthetic valve assembly of claim 1 , wherein the outlet end of the frame is flared.

4. The prosthetic valve assembly of claim 1 , wherein the inlet end of the frame is flared.

5. The prosthetic valve assembly of claim 4 , wherein the frame has a substantially cylindrical structure.

6. A prosthetic valve assembly for replacing a deficient native valve by a catheterization technique, comprising:

a collapsible and expandable stent formed with intersecting bars, the stent having an outer surface configured for pushing against the deficient native valve, the stent comprising a substantially cylindrical structure when implanted within the native valve, the stent having an inlet end and an outlet end and an internal surface, the stent being radially collapsible to a collapsed diameter of about 5 millimeters for advancing the prosthetic valve assembly through a patient's vasculature using a catheterization technique, the stent having sufficient height for extending above and below a native valve annulus after implantation within the native valve;

a flexible valvular structure sewn to the stent along the internal surface, the valvular structure formed of pericardial tissue and having an open position and a closed position, the valvular structure positioned entirely between the inlet and outlet ends of the stent when in the closed position, the valvular structure configured for permitting the flow of blood in one direction; and

an internal cover sewn to the stent, the internal cover positioned along the internal surface and contacting only the internal surface, the internal cover forming a sleeve extending only between the inlet end of the stent and the valvular structure for preventing blood from flowing through gaps between the intersecting bars of the stent upstream of the valvular structure and wherein blood is permitted to flow through gaps between the intersecting bars of the stent downstream of the valvular structure for ensuring that an adequate supply of blood enters the coronary arteries;

wherein the valvular structure and the internal cover are coupled together by suture along an intermediate portion of the stent.

7. The valve assembly of claim 6 , wherein the internal cover is formed of pericardial tissue.

8. The valve assembly of claim 7 , wherein the valvular structure and the internal cover are sewn to the stent by suture lines extending around the intersecting bars of the stent.

9. The valve assembly of claim 6 , wherein the stent is expandable to an expanded diameter of about 20 to 25 millimeters.

10. The valve assembly of claim 6 , wherein at least a portion of the stent has a generally concave profile.

11. The valve assembly of claim 6 , wherein the valvular structure forms a continuous surface and is provided with guiding means.

12. The valve assembly of claim 11 , wherein the guiding means create stiffened zones which induce the valvular structure to follow a patterned movement when moving from the closed position to the open position.

13. The valve assembly of claim 12 , wherein the guiding means are further configured to prevent eversion of the valvular structure.

14. A prosthetic valve assembly for replacing a deficient native aortic valve using a catheterization technique, comprising:

a collapsible and expandable metallic stent formed with intercrossing bars and configured for advancement through a patient's vasculature when in a collapsed state, the stent having an internal surface, an inlet end, an outlet end and a middle portion between the inlet and outlet ends, the stent having an outlet diameter at the outlet end and a middle diameter along the middle portion and wherein the outlet diameter is greater than the middle diameter for facilitating anchoring of the stent within the deficient native aortic valve when in an expanded state;

a flexible valvular structure formed of pericardial tissue and coupled to the middle portion of the stent via suture lines extending around bars in the stent, the flexible valvular structure having open and closed positions, the flexible valvular structure located entirely between the inlet and outlet ends of the stent when in the closed position; and

an internal cover formed of pericardial tissue, the internal cover sewn to the stent along the internal surface of the stent and contacting the internal surface, the internal cover extending only along the internal surface and only between the valvular structure and the inlet end of the stent, the internal cover forming a sleeve for preventing blood from flowing through gaps in a wall of the stent between the valvular structure and the inlet end of the stent;

wherein the internal cover is sewn directly to the valvular structure such that the internal cover is securely coupled to the valvular structure and wherein blood is permitted to flow through gaps in the wall of the stent downstream of the valvular structure for providing blood to the coronary arteries.

15. The prosthetic valve assembly of claim 14 , wherein an inlet end of the internal cover has a zig-zag shape and the inlet end of the stent has a zig-zag shape and wherein the inlet end of the internal cover is sewn to the inlet end of the stent along a zig-zag line.