Apparatus and methods for using the apparatus are disclosed for cardiac restraint. More specifically, the apparatus and methods are directed to accessing the pericardium, accessing the heart within the pericardium, and restraining the heart by at least partially enclosing the heart with the apparatus. An embodiment of a cardiac restraint apparatus according to the present invention comprises a jacket, the jacket having a rim which defines an opening for receiving a heart. The apparatus also comprises a knot pusher that has a hollow elongate body, as well as a strand that extends around the rim of the jacket and is tied into a slipknot. The strand is positioned such that at least one end portion of the strand extends through the knot pusher such that a distal end of the knot pusher can be moved into engagement with the slipknot, whereby pulling the end portion of the strand away from the heart while pushing the knot pusher against the slipknot and reducing the diameter of the opening defined by the rim. In addition, the apparatus comprises one or more guide elements that are attached to the jacket.