Which of the following is the correct apical view used for PISA measurement in MR, given the preference?

• A. Apical 4-chamber
• B. Apical 2-chamber
• C. Parasternal long axis
• D. AP4/3 (4 preferred)

Answer: (D)

PISA measurement for mitral regurgitation relies on visualizing the flow convergence around the regurgitant orifice and accurately assessing the radius at the chosen aliasing velocity. To get a true read of the jet geometry, you image from the apical windows that best align with the jet. The apical four-chamber view typically provides the clearest view of the regurgitant jet as it passes through the mitral valve plane, making the PISA radius measurement in this plane the most reliable. Using an additional apical view, usually the apical three-chamber, helps detect any jet tilt or eccentricity that might be missed in a single view, preventing underestimation of the flow convergence. Therefore, it’s standard to perform PISA in both apical four- and three-chamber views, with the four-chamber view preferred when available. The parasternal long-axis view is less ideal for PISA in MR because the Doppler alignment with the flow convergence is not as favorable, and relying on a single apical view (like the two-chamber) may miss jet eccentricity.