An exemplary medical apparatus insertable into the vasculature of a patient at an insertion point for treating a defect in the heart, may include an elongated, flexible driver sufficient in length to extend from the insertion point to the defect in the heart; and a staple frangibly attached to the distal end of the driver. Another exemplary medical apparatus may include a catheter sufficient in length to extend from the insertion point to the patent foramen ovale; a housing attached to the distal end of the catheter; a driver extending into the housing; and a staple frangibly attached to the driver. Another exemplary medical apparatus may include a steering catheter sufficient in length to extend from the insertion point to the patent foramen ovale; an end effector attached to the distal end of the steering catheter, the end effector having a cross-section sufficiently small to allow it to be moved through the vasculature to the patent foramen ovale; and a staple held by the end effector, wherein the staple is frangibly separable from and deployable out of the end effector to close the patent foramen ovale.