A catheter member for interacting with a circumferential tissue structure includes: an elongate primary catheter having at least one inner lumen and extending along a longitudinal axis； first and second elongate secondary catheters, each having an inner lumen, and each positionable in an inner lumen of the primary catheter to be moveable relatively thereto and exposable therefrom； and a first flexing mechanism to provide a distal end portion of the first and/or second secondary catheter with a tendency to assume a first secondary bent shape. The distal end portion of the first and/or second secondary catheters is provided so as to be able to be flexed by the first flexing mechanism to form an arm portion substantially transverse to the direction of the longitudinal axis of the primary catheter so as to assume the first secondary bent shape when exposed from a distal end portion of the primary catheter.
