An electrode support structure assembly is provided comprising an electrode support structure including a plurality of splines. Each of the plurality of splines can have a proximal end portion and a distal end portion. The assembly further comprises a first element defining an axis and comprising an outer surface. The outer surface comprises a plurality of slots configured to receive the distal end portion of each of the plurality of splines. The first element is configured such that the distal end portion of each of the plurality of splines may move with respect to each slot. In accordance with some embodiments, the distal end portion of each of the plurality of splines comprises a section configured for engagement with the first element, wherein the section comprises a shoulder.