The present invention pertains generally to the field of cryo balloon therapy and the use of cryo balloon therapy catheters to generate cold-induced lesions. The present invention includes a cryo balloon therapy apparatus, comprising a catheter having a proximal and a distal end, a cooling member disposed at the distal end of the catheter, a pull cord coupled to the cooling member, and a sheath that couples the pull cord and the catheter. A method for causing cold-induced necrosis is also disclosed.