Patent ID: 6997925

Claim:
A tissue ablation system for treating atrial arrhythmia by ablating a circumferential region of tissue at a location where a pulmonary vein extends from an atrium, comprising: a delivery member with a proximal end portion and a distal end portion having a longitudinal axis and a radial axis; and a circumferential ablation member coupled to the distal end portion and having a plurality of splines, each with a proximal end portion and a distal end portion, and also having one or more ablation elements each supported along a support region of one of the splines, wherein the plurality of splines are circumferentially spaced around the longitudinal axis, each of the splines being adjustable between a first condition and a second condition wherein the respectively supported ablation element is adjustable between a first radial position and a second radial position, wherein each spline in the first condition is substantially radially collapsed and extends substantially along the longitudinal axis such that the circumferential ablation member is adapted to be delivered through a delivery sheath into the atrium, and in the second condition the support region of each spline extends at least in part radially away from the longitudinal axis such that each of the individual ablation elements is held by the supporting spline in the second radial position with the one or more ablation elements being spaced along a circumferential pattern that surrounds the longitudinal axis, said circumferential pattern being configured such that the one or more ablation elements is adapted to engage and ablate the circumferential region of tissue when the splines are adjusted to the second condition at the location, wherein the distal end portion of each of the splines in the second position has a radius of curvature toward the longitudinal axis, and wherein each of the splines has a memory to the second condition.