Doppler echocardiography versus cardiac catheterization in the evaluation of valvular heart disease: do we have a gold standard?

Definitive evaluation of valvular heart disease is traditionally accomplished by cardiac catheterization. Recent advances in Doppler echocardiography allow noninvasive assessment of valvular heart disease with a high degree of accuracy compared to the cardiac catheterization gold standard. Doppler echocardiography may occasionally yield erroneous results due to technical difficulties in the performance of the study. A number of patient related and echo-machine related factors may also affect the Doppler measurements independent of the severity of the lesion. Thus, a discrepancy between Doppler and catheterization data is generally considered to be a failure of Doppler methods. However, catheterization data may also be flawed due to errors in the measurement of pressure and cardiac output, as well as the known shortcomings of qualitative angiography. The Gorlin equation itself suffers from several limitations, including the substitution of pressure gradient for velocity in the basic hydrodynamic equation, and the use of a constant which may not be appropriate in all circumstances. Therefore, when Doppler echocardiography and cardiac catheterization yield discordant results, both studies should be carefully reviewed and correlated with other clinical data in order to elucidate the sources of the discrepancy and ascertain the actual severity of the valvular lesion.