micro channel as is shown in fig8 fig9 and 10 illustrate yet another embodiment of the present invention which substantially reduce the problems described in connection with fig1 and 2 above as can be seen flexible tubular guidewire catheter 46 acts as an inner shaft which is slidably mounted within an outer flexible tubular balloon catheter 68 equipped with an expandable membrane e g a compliant balloon 70 inner shaft 46 may further include blades or ribs 80 mounted on a distal section as shown in fig1 blades 80 are housed within outer shaft 68 to protect the vessel from damage until inner shaft 46 is advanced sliding inner shaft 46 is advanced over wire 36 and into chronic total occlusion 14 in order to score the lesion and potentially facilitate controlled expansion or opening of the lesion as can be seen balloon 70 may be inflated by means of inflation channel 72 inner shaft 46 may have an outer diameter of 0 023 inches and an inner diameter of 0 016 inches outer shaft 68 may have an inner diameter of 0 041 inches and an outer diameter of 0 047 inches compliant balloon 70 when inflated or expanded serves to center wire lumen 46 and therefore guidewire 36 within the vessel to be treated for example referring to fig1 balloon 70 centers exit port 34 thereby centering guidewire 36 within vessel 12 distal portion 77 of balloon 70 substantially abuts at least a portion of chronic total occlusion 14 if desired catheter 68 may be provided with a marker band 34 on its distal portion therefore marker band 34 also substantially abuts chronic total occlusion 14 and enables a clinician to predict the location of the central region of chronic total occlusion 14.