It is difficult to perform a retrograde left ventricular catheterization in patients having an aortic valve replacement. An improvement of the conventional transseptal catheterization (Brockenbrough method) led to a better success rate of catheterization. The fulcrum of the improved catheter was located 7 cm from the tip. Its curvature was approximately 270 degrees. Its tip was bent inward to form a pig-tail shape to prevent myocardial injury. This catheterization was performed 33 times in 32 patients. A 97% success rate was achieved. An exercise loading test was performed with a bicycle ergometer while this catheter was maintained in the left ventricle of a patient placed in a supine position. The catheter was well retained in the left ventricle and produced a minimal number of arrhythmias during exercise. The modification of this catheter has proved to be a better method of left ventricular catheterization in patients with an aortic valve replacement.