affixed to the scope body 82 and to the surrounding inner surface of the cylindrical member 120 an annular spring member 130 is positioned within an annular notch formed about the outer surface of engagement member 124 and a series of corresponding engagement notches or detents 131 are formed in the inner surface of the cylindrical member 120 thus cylindrical member 120 engagement member 124 scope body 82 and proximal scope connector assembly 90 may be concurrently moved back and forth longitudinally relative to the catheter body 12 proximal y connector assembly 50 fine adjustment mechanism 100 and handpiece 88 as such longitudinal movement is accomplished the spring member 130 will engage the individual detents 131 to bias and hold the scope body 82 in selected longitudinal positions in this regard the operator may manually grasp and move the cylindrical member 120 to accomplish movement of the scope 80 between it 39 s distally advanced position fig2 a 3a wherein the illumination outlet ports 86 and imaging receiving port 84 of the scope 80 are positioned immediately adjacent or within the image receiving port 126 formed in the distal face 24 of the distal tip member 18 and the proximally retracted position fig2 b 3b wherein the illumination ports 86 and image receiving port 36 of the scope 80 are positioned immediately proximal to the side opening 32 formed in the distal tip member 18 in this regard when the scope 80 is in its distally advanced position fig2 a 3a the scope 80 may be utilized to visualize an area which is ahead of and surrounding the distal end de of the catheter body 12 thereby facilitating advancement of the catheter.