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