APPLICATION OF COLOR DOPPLER FLOW MAPPING TO CALCULATE EFFECTIVE REGURGITANT ORIFICE AREA - AN IN-VITRO STUDY AND INITIAL CLINICAL OBSERVATIONS

Background. Analogous to stenotic valve area in the assessment of valv ular stenosis, regurgitant orifice area (ROA) represents a fundamental parameter to assess valvular insufficiency. However, this parameter h as not been routinely available up to now. In this study, we introduce the concept and provide the methodology to calculate regurgitant orif ice area noninvasively, based on the analysis of the proximal flow con vergence zone. Methods and Results. In an in vitro study, we showed th e feasibility and the accuracy of calculating effective ROA by the pro ximal flow convergence method throughout a range of driving pressures. The calculated and true ROA showed an excellent correlation with r=.9 92, DELTAROA= -1.4+/-2.9 mm2. We then applied this concept clinically in 77 patients with mitral regurgitation and showed a very good correl ation between effective ROA calculated by the proximal How convergence method and calculated by the Doppler echocardiographic method: r=.95, DELTAROA=-0.2+/-3.9 mm2. The ROA also correlated very well with Doppl er echocardiographic-derived regurgitant stroke volume (r=.93) and reg urgitant fraction (r=.82). In a subgroup of 20 patients who underwent invasive evaluation, the calculated effective ROA also correlated well with the angiographic grade of mitral regurgitation (rho=.81). Conclu sion. We conclude that effective ROA represents unique information on the severity of a regurgitant lesion and can easily be calculated by t he proximal flow convergence method. This new parameter should enhance our understanding and improve the serial assessment of valvular regur gitation.