Standard Versus Simplified Proxizmal Isovelocity Surface Area: An Echocardiographic Approach

Abstract

A noninvasive approach to quantitatively assessing mitral valve regurgitation is called the proximal isovelocity surface area (PISA) method. The basis for the PISA technique is to use color and spectral Doppler to measure flow velocity and effective area and then calculate effective regurgitant orifice area and regurgitant flow volumes as defined by the conservation of mass theory. Moreover, the complexity of these calculations leads to the search for a simplified approach to this laborious quantification method. It is with this in mind that a close clinical correlation of the standard PISA and the newly derived simplified PISA is established through the use of noninvasive techniques. In a prospective study, 21 patients (10 men and 11 women; mean age, 68.9 years) with at least mild mitral regurgitation were evaluated by color and spectral Doppler echocardiography. Two-dimensional imaging measurements also were recorded. This study used the simplified proximal convergence flow rate (r2 X Va), the standard PISA calculation, and the left atrial volume measurement. The simplified proximal convergence method correlated well with the standard PISA method but lacked a solid linear relation with the left atrial volume assessment. Simplified PISA shows accuracy in stratifying mild mitral regurgitation and moderately severe to severe mitral regurgitation. However, there remains a range (10-20 mL/s) in which further assessment may be necessary, either invasively or noninvasively, to accurately quantify the degree of mitral regurgitation.