Retaining mechanisms for prosthetic valves

1. An assembly comprising:

a prosthetic heart valve comprising an annular frame that is radially collapsible and expandable between a radially collapsed configuration and a radially expanded configuration, and a valve structure positioned within the frame; and

a support structure separate from the prosthetic heart valve configured to be positioned such that the support structure extends annularly around the native mitral valve leaflets within the left ventricle of a patient's heart;

wherein the prosthetic heart valve is configured to be deployed within the native mitral valve leaflets after the support structure is deployed around the native mitral valve leaflets such that the native mitral valve leaflets are positioned between and engaged by the support structure and the prosthetic heart valve;

a delivery system configured to deliver and implant the prosthetic heart valve and the support structure within the heart of the patient;

wherein the delivery system comprises:

a first loop delivery catheter having a distal end portion configured to be advanced into the left ventricle;

a second loop delivery catheter having a distal end portion configured to be advanced into the left ventricle; and

a guidewire configured to be inserted through the first loop delivery catheter and the second loop delivery catheter so as to form a loop in the left ventricle for delivering and positioning the support structure around the native mitral valve leaflets.

2. The assembly of claim 1 , wherein the distal end portion of the first loop delivery catheter is configured to extend substantially around the exterior of one half of the chordae tendineae of the patient and the distal end portion of the second loop delivery catheter is configured to extend substantially around the exterior of the other half of the chordae tendineae of the patient.

3. The assembly of claim 2 , wherein the distal end portion of the first loop delivery catheter is configured to engage the distal end portion of the second loop delivery catheter to form a contiguous junction between the first and second loop delivery catheters.

4. The assembly of claim 1 , wherein the first and second loop catheters are configured to be advanced through the patient's arch, the native aortic valve, and into the left ventricle.

5. The assembly of claim 1 , wherein the delivery system further comprises:

a first catheter delivery sheath having a curved distal end region, wherein the first loop delivery catheter is configured to be advanced through the first catheter delivery sheath into the left ventricle; and

a second catheter delivery sheath having a curved distal end region, wherein the second loop delivery catheter is configured to be advanced through the second catheter delivery sheath into the left ventricle.

6. The assembly of claim 5 , wherein the delivery system further comprises:

an introducer having a distal end portion configured to be inserted into the heart;

wherein the first and second catheter delivery sheaths are configured to be advanced through the introducer and into the heart.

7. The assembly of claim 6 , wherein the first catheter delivery sheath and the second catheter delivery sheath are configured such that they arc outwardly away from each other as they are advanced distally from the introducer sheath.

8. An assembly comprising:

a first loop delivery catheter having a distal end portion configured to be advanced into a patient's left ventricle;

a second loop delivery catheter having a distal end portion configured to be advanced into the left ventricle; and

a guidewire configured to be inserted through the first loop delivery catheter and the second loop delivery catheter so as to form a loop in the left ventricle for delivering and positioning a support structure around the patient's native mitral valve leaflets.

9. The assembly of claim 8 , wherein the distal end portion of the first loop delivery catheter is configured to extend substantially around the exterior of one half of the patient's chordae tendineae, the second loop delivery catheter is configured to extend substantially around the exterior of the other half of the patient's chordae tendineae, and the distal end of the first and second loop delivery catheters are configured to engage each other to form a contiguous junction between them.

10. The assembly of claim 8 , further comprising:

a first catheter delivery sheath having a curved distal end region, wherein the first loop delivery catheter is configured to be advanced through the first catheter delivery sheath into the left ventricle; and

a second catheter delivery sheath having a curved distal end region, wherein the second loop delivery catheter is configured to be advanced through the second catheter delivery sheath into the left ventricle.

11. The assembly of claim 10 , further comprising:

an introducer having a distal end portion configured to be inserted into the heart;

wherein the first and second catheter delivery sheaths are configured to be advanced through the introducer and into the heart.

12. An assembly comprising:

a prosthetic heart valve comprising an annular frame that is radially collapsible and expandable between a radially collapsed configuration and a radially expanded configuration, and a valve structure positioned within the frame; and

a support member separate from the prosthetic heart valve configured to be positioned annularly around the native mitral valve leaflets within the left ventricle of a patient's heart;

wherein the support member comprises a hollow first end and a second end configured to extend into the hollow first end to form an annular band configured to extend around and engage the native mitral valve leaflets and support the prosthetic heart valve when the prosthetic heart valve is deployed within the native mitral valve leaflets.

13. The assembly of claim 12 , wherein the first end comprises a shoulder and the second end comprises an angled collar that forms a snap-fit connection with the shoulder.