A catheter assembly provided with a wire arranged therein to form a loop extending from near the effective end of the catheter for bypassing an occlusion in a vein/artery. This loop consists of two wire ends, one of which wire ends extends through the catheter to the control end thereof, while the other wire end is attached thereto, in close proximity to the effective end of the catheter. By varying the relative position of the loop wire end extending from the control end and the control end, the size of the loop and the pushability thereof at the effective end of the catheter can be determined. In this manner, the occlusion can be removed with precise control by the physician using two hands. In addition, the catheter is formed not only for the loop wire end extending through the catheter, but also for incorporating a guide wire and/or for contrast fluids.