An expandable member for coupling to a catheter shaft, comprising • a spline configured to expand from an undeployed state to a deployed state and extending continuously between a pair of proximal locations (204, 206) on the catheter shaft and intersecting a central axis of the expandable member at a distal intersection, the spline having a first subsegment intersecting the central axis at the distal intersection and a second subsegment, o wherein the first subsegment is continuous with the second subsegment, o wherein, in the deployed state, a first profile of the first subsegment viewed in an isometric plan view in a direction along the central axis of the expandable member is straight between the distal intersection at the central axis and a distal subsegment end of the second subsegment, o wherein in the deployed state the distal intersection is axially proximal to the distal subsegment end and nearer to the proximal location at the central axis than the distal subsegment end is, and o wherein a second profile of the second subsegment viewed in the isometric plan view in the direction along the central axis is curved between the distal subsegment end and a proximal subsegment end of the second subsegment, and • an electrode mounted on the second subsegment. • a spline configured to expand from an undeployed state to a deployed state and extending continuously between a pair of proximal locations (204, 206) on the catheter shaft and intersecting a central axis of the expandable member at a distal intersection, the spline having a first subsegment intersecting the central axis at the distal intersection and a second subsegment, o wherein the first subsegment is continuous with the second subsegment, o wherein, in the deployed state, a first profile of the first subsegment viewed in an isometric plan view in a direction along the central axis of the expandable member is straight between the distal intersection at the central axis and a distal subsegment end of the second subsegment, o wherein in the deployed state the distal intersection is axially proximal to the distal subsegment end and nearer to the proximal location at the central axis than the distal subsegment end is, and o wherein a second profile of the second subsegment viewed in the isometric plan view in the direction along the central axis is curved between the distal subsegment end and a proximal subsegment end of the second subsegment, and o wherein the first subsegment is continuous with the second subsegment, o wherein, in the deployed state, a first profile of the first subsegment viewed in an isometric plan view in a direction along the central axis of the expandable member is straight between the distal intersection at the central axis and a distal subsegment end of the second subsegment, o wherein in the deployed state the distal intersection is axially proximal to the distal subsegment end and nearer to the proximal location at the central axis than the distal subsegment end is, and o wherein a second profile of the second subsegment viewed in the isometric plan view in the direction along the central axis is curved between the distal subsegment end and a proximal subsegment end of the second subsegment, and • an electrode mounted on the second subsegment.