An apparatus for endovascularly replacing a patient's heart valve comprises an anchor having an outer surface and an inner surface. The anchor is expandable from a collapsed delivery configuration to a fully deployed configuration. A first locking element and a second locking element are attached to the inner surface of the anchor. The first locking element is engageable with the second locking element. At least one of the first locking element and the second locking element has a curved outer surface. Methods for attaching the second locking element to the anchor are also provided.