Variable shaped catheter system and method for catheterization

A catheter assembly (1d) and method for catheterization provides a means by which the curved configuration at the distal portion (14) of a catheter can be varied while the catheter system remains in the patient. The catheter, having a predetermined curve at its distal end is received within a sheath (28) that can be advanced over the distal end to tend to straighten the curve in the distal end of the catheter. The extent to which the sheath is advanced over the curved distal portion of the catheter controls the degree to which the catheter is straightened. The position of the sheath relative to the catheter can be adjusted while the catheter is in the patient, thereby enabling change in catheter shape without requiring catheter exchanges. For example, the system enables right and left coronary angiographic procedures to be performed without changing catheters. Left ventricular studies also can be made without catheter exchanges.