Advances in the hemodynamic assessment of stenotic cardiac valves.

In 1951 Gorlin and Gorlin (Am Heart J 1951;41:1-29) published their formula for calculating the area of a stenotic cardiac valve from hemodynamic data. The important concept implicit in this formula is that the hemodynamic evaluation of a stenotic valve requires that the pressure gradient across that valve be examined in light of the cardiac output passing through the orifice. The concept asserts that if an accurately obtained pressure gradient can be related to an accurate cardiac output by an accurate formula, valve area can be determined. However, recent studies have demonstrated flaws in current practices for obtaining transvalvular gradients and cardiac outputs. Further, new data are available regarding the validation and possible changes in the Gorlin formula, validation and changes that the Gorlins noted might be necessary to make. These new data concerning the three basic requirements of an accurate valve area determination are the subject of this review.