Predicting aortic valve prosthesis size. A step toward better matching of patient and prosthesis

We have developed a simple method of predicting aortic valve prosthesis size from supravalvular aortic cineangiograms, taken in the 30 degree right anterior oblique projection, during routine diagnostic cardiac catheterization. Measurements made on the aortogram were corrected to true size by means of a 1 cm2 grid reference plate filmed at the conclusion of the catheterization. This method was utilized prospectively to predict the anulus size in 26 patients undergoing aortic valve replacement alone or as part of a more extensive procedure. The catheterization prediction of anulus size was perfectly predictive of the prosthesis size used in eight of 26 (31%) cases, within 1 mm of the prosthesis size used in 20 of 26 (77%), and within one prosthesis size in all 26 (100%) cases. Comparing the measured anulus diameter to the actual prosthesis diameter yielded r = 0.93. When both systolic and diastolic frames were available for analysis, the diastolic frame was more accurately predictive than the systolic frame (diastolic r = 0.93; systolic r = 0.88), although both yielded acceptable results. Utilization of this method has significantly altered operative plans in four patients with a small anulus. Such preoperative assessment should allow improved matching of patient and valve prosthesis and thereby yield improved long-term results in aortic valve replacement.