Catheter member for interacting with a circumferential tissue structure comprising: an elongate primary catheter which has at least one inner lumen and which extends along a longitudinal axis and has a distal end portion, first and second elongate secondary catheters each extending along a longitudinal axis (125, 135), each comprising a distal end portion (140, 150) and a proximal end portion (180, 190) and an inner lumen (160, 170), and each comprising a secondary alignment portion (127, 137), which is located between the distal (140, 150) and proximal end portions (180, 190) and adjacent to the distal end portion (140, 150), and each positionable in an inner lumen of the primary catheter to be moveable relatively thereto and exposable therefrom, a first flexing mechanism to provide the distal end portion (140, 150) of one or both of the first and second secondary catheters with a tendency to assume a first secondary bent shape, and a second flexing mechanism to provide the secondary alignment portion (127, 137) of the first and second secondary catheters with a tendency to assume a second secondary bent shape, wherein the distal end portion (140, 150) of the one or both of the first and second secondary catheters (120, 130) is configured to be able to be flexed by the first flexing mechanism to form an arm portion (126, 136) substantially transverse to the direction of the longitudinal axis of the primary catheter so as to assume the first secondary bent shape, when being exposed from the distal end portion of the primary catheter, wherein the secondary alignment portion (127, 137) of the first and second secondary catheters is configured to be able to be flexed by the second flexing mechanism to assume the second secondary bent shape having a predetermined curvature, and wherein the arm portion (126, 136) of the one of the first and second secondary catheters extends transverse to the longitudinal axis of the primary catheter, while at the same time the distal end portion (140, 150) of the other one of the first and second secondary catheters remains straight when the secondary alignment portions (127, 137) of the first and second secondary catheters assume the second secondary bent shape extending in parallel to each other, or the arm portions of both of the first and second secondary catheters extend in generally opposite directions to each other when the secondary alignment portions (127, 137) of the first and second secondary catheters assume the second secondary bent shape extending in parallel to each other. an elongate primary catheter which has at least one inner lumen and which extends along a longitudinal axis and has a distal end portion, first and second elongate secondary catheters each extending along a longitudinal axis (125, 135), each comprising a distal end portion (140, 150) and a proximal end portion (180, 190) and an inner lumen (160, 170), and each comprising a secondary alignment portion (127, 137), which is located between the distal (140, 150) and proximal end portions (180, 190) and adjacent to the distal end portion (140, 150), and each positionable in an inner lumen of the primary catheter to be moveable relatively thereto and exposable therefrom, a first flexing mechanism to provide the distal end portion (140, 150) of one or both of the first and second secondary catheters with a tendency to assume a first secondary bent shape, and a second flexing mechanism to provide the secondary alignment portion (127, 137) of the first and second secondary catheters with a tendency to assume a second secondary bent shape, wherein the distal end portion (140, 150) of the one or both of the first and second secondary catheters (120, 130) is configured to be able to be flexed by the first flexing mechanism to form an arm portion (126, 136) substantially transverse to the direction of the longitudinal axis of the primary catheter so as to assume the first secondary bent shape, when being exposed from the distal end portion of the primary catheter, wherein the secondary alignment portion (127, 137) of the first and second secondary catheters is configured to be able to be flexed by the second flexing mechanism to assume the second secondary bent shape having a predetermined curvature, and wherein the arm portion (126, 136) of the one of the first and second secondary catheters extends transverse to the longitudinal axis of the primary catheter, while at the same time the distal end portion (140, 150) of the other one of the first and second secondary catheters remains straight when the secondary alignment portions (127, 137) of the first and second secondary catheters assume the second secondary bent shape extending in parallel to each other, or the arm portions of both of the first and second secondary catheters extend in generally opposite directions to each other when the secondary alignment portions (127, 137) of the first and second secondary catheters assume the second secondary bent shape extending in parallel to each other.