The present invention relates to a system for performing minimally invasive procedures in a working space within a body lumen of a patient, the system comprising a flexible catheter having an inner wall, an outer wall, a first flexible tube, and a second flexible tube, the flexible catheter insertable over an endoscope such that the endoscope is received within the flexible catheter, the first and second flexible tubes attached to the flexible catheter at a proximal portion thereof to provide first and second floating lumens to reduce the stiffness of the flexible catheter, the first flexible tube configured and dimensioned to receive a first endoscopic tool for axial movement therein, and the second flexible tube configured to receive a second endoscopic tool for axial movement therein, and a working space expanding system positioned at a distal portion of the flexible catheter, the working space expanding system movable from a non-expanded insertion position to an expanded position forming an expanded cage to expand the working space within the body lumen.
