A wall (39) of a catheter (38) (a) includes a braided portion (41) having an outer surface (45), an inner surface (47), and a braided interior (53) between the outer and inner surfaces (45, 47), and (b) is shaped to define first and second longitudinally-running channels (27a, 27b) therethrough. A distal portion of the catheter (38) is shaped to define first and second lateral openings (26a, 26b). An angle between (a) a first line (76) running between the first and second lateral openings (26a, 26b), and (b) a second line (78) that is parallel to a central longitudinal axis of the catheter (38) when the catheter (38) is straight, is between 30 and 150 degrees. A flexible longitudinal member (14) passes from a proximal portion of the catheter (38) to the distal portion via the first channel (27a), out of the first channel (27a) via the first lateral opening (26a), into the second channel (27b) via the second lateral opening (26b), and from the distal portion to the proximal portion via the second channel (27b).
