a guiding catheter 40 of variable , operator - controlled flexibility to be used in the performance of a percutaneous translumenal coronary angioplasty procedure is described which includes an elongate housing 42 suitable for insertion into an artery , as well as an operator - controlled variable stiffener coupled to the distal aspect of the catheter to permit the operator performing the angioplasty procedure to increase the rigidity of the catheter . in a preferred embodiment the stiffening apparatus consists of a balloon 50 extending longitudinally along the distal end of the catheter to allow increases in rigidity of the distal end as desired by the operator . increasing the rigidity of the guiding catheter , once installed within the coronary ostium , precludes disengagement of the guiding catheter , thus expediting the performance and enhancing the safety of the procedure .