A distal portion of a catheter is transluminally advanced to a heart of a subject. Via an atrium of the heart, a ventricular anchor-helix is transluminally advanced out of the distal portion of the catheter to a ventricular site in a ventricle of the heart. An atrial anchor-helix is transluminally advanced out of the distal portion of the catheter to an atrial site. A prosthetic valve, in a compressed state thereof, is transluminally delivered to a mitral valve of the heart. The prosthetic valve is expanded at the mitral valve and held in place using the ventricular anchor-helix and the atrial anchor-helix, such that an upstream portion of the prosthetic valve is disposed in the atrium, and a downstream portion of the prosthetic valve is disposed in the ventricle. Other embodiments are also described.
