A medical device (100, 200, 400) for the treatment of a sinus opening, the medical device comprising: a handle (102, 202, 402) with: a proximal end (120, 216); a distal end (122,218); and a longitudinal axis along the length of the handle; a guide catheter (104, 204, 404) attached to the distal end of the handle, the guide catheter having a catheter lumen; and a balloon catheter movement mechanism (114, 212, 412) operatively disposed on the handle; wherein the handle and the catheter lumen are configured for operatively accepting a guide wire (106, 206, 406) and a balloon catheter (108, 208, 408); and wherein the balloon catheter movement mechanism is configured for advancement and retraction of a balloon catheter disposed at least partially in the handle and in the catheter lumen through the handle and catheter lumen by user operation of the balloon catheter movement mechanism, wherein the device further includes a guide wire support (118, 260) disposed within the handle and a guide wire (106, 206, 406) disposed at least partially in the handle and the catheter lumen, wherein the guide wire is at least partially disposed within the guide wire support; and wherein the guide wire support is cylindrical in shape and defines a thin walled tube, characterised in that said guide wire support includes a slit-shaped opening (136, 270) on said tube, said slit-shaped opening being configured to prevent buckling of the guide wire within the handle during advancement of the guide wire through the handle, wherein the slit-shaped opening is configured such that it opens as the guide wire is advanced. a handle (102, 202, 402) with: a proximal end (120, 216); a distal end (122,218); and a longitudinal axis along the length of the handle; a proximal end (120, 216); a distal end (122,218); and a longitudinal axis along the length of the handle; a guide catheter (104, 204, 404) attached to the distal end of the handle, the guide catheter having a catheter lumen; and a balloon catheter movement mechanism (114, 212, 412) operatively disposed on the handle; wherein the handle and the catheter lumen are configured for operatively accepting a guide wire (106, 206, 406) and a balloon catheter (108, 208, 408); and wherein the balloon catheter movement mechanism is configured for advancement and retraction of a balloon catheter disposed at least partially in the handle and in the catheter lumen through the handle and catheter lumen by user operation of the balloon catheter movement mechanism, wherein the device further includes a guide wire support (118, 260) disposed within the handle and a guide wire (106, 206, 406) disposed at least partially in the handle and the catheter lumen, wherein the guide wire is at least partially disposed within the guide wire support; and wherein the guide wire support is cylindrical in shape and defines a thin walled tube, characterised in that said guide wire support includes a slit-shaped opening (136, 270) on said tube, said slit-shaped opening being configured to prevent buckling of the guide wire within the handle during advancement of the guide wire through the handle, wherein the slit-shaped opening is configured such that it opens as the guide wire is advanced.