Effect of aortic outflow on the quantification of mitral regurgitation using the flow convergence method

The proximal isovelocity surface area (PISA) method has shown promise in the non-invasive assessment of mitral regurgitation. In this study, in-vitro steady flow studies were conducted to determine if the PISA method could be used to accurately estimate the regurgitant flow rate in the presence of complicating factors such as aortic outflow. By digitizing the color flow map, velocity information was obtained along the orifice centerline. These studies showed that the presence of aortic outflow caused isovelocity contours to merge with the aortic outflow for lower aliasing velocities, causing further overestimation in the regurgitant flow rate at large distances from the orifice, than for converging flows in the absence of aortic outflow. In addition, this study suggests that the digital flow map may be useful to quantify mitral regurgitation in the near future.