Techniques for percutaneous mitral valve replacement and sealing

A method, for use at a mitral valve of a heart of a subject, the method comprising:

• advancing a transluminal sheath into a femoral vein of the subject, through an inferior vena cava of the subject, into a right atrium of the subject, and transseptally into a left atrium of the subject;
• advancing a surrounding-sheath out of a distal end of the transluminal sheath, into the left atrium, and toward a commissure of the mitral valve;
• implanting a helix at the mitral valve by advancing the helix out of the surrounding-sheath and through the commissure into a left ventricle of the subject, such that the helix wraps around at least some chordae tendineae of the mitral valve;
• collapsing a prosthetic valve into a collapsed state;
• subsequently to implanting the helix and collapsing the prosthetic valve, advancing the prosthetic valve, in its collapsed state, through the transluminal sheath to the mitral valve;
• and
• implanting the prosthetic valve in the mitral valve by expanding the prosthetic valve such that the helix facilitates anchoring of the prosthetic valve and sealing of the commissure.