Accuracy of sizers for aortic valve prostheses.

Accurate sizing of the aortic anulus is a prerequisite of prosthetic valve implantation, because it is usually desirable to insert the largest possible prosthesis. Although it is generally assumed that commercial valve sizers are accurately labeled, our measurements reveal that the sizers for the St. Jude Medical, Björk-Shiley, and Ionescu-Shiley prostheses are larger than their nominal sizes. These findings are relevant to the selection of prosthetic valves.