sentences:  By the late 1960s, Melvin Judkins had begun work on creating catheters that were specially shaped to reach the coronary arteries to perform selective coronary angiography.His initial work involved shaping stiff wires and comparing those shapes to radiographs of the ascending aorta to determine if the shape appeared promising.Then he would place the stiff wire inside a flexible catheter and use a heat-fixation method to permanently shape the catheter.