Proximal isovelocity surface area method for assessment of mitral regurgitation severity: Principles, pitfalls, and future directions

Quantification of mitral regurgitation (MR) is important in clinical practice. As fluid approaches a finite circular orifice, concentric hemispherical shells are formed with gradually decreasing surface area and increasing velocity. Severity of MR by the proximal isovelocity surface area (PISA) can be quantified using this principle. Careful attention to detail needs to be paid in the acquisition and measurement to ensure accuracy and reproducibility of the PISA method. The pitfalls of this method are related to geometric assumptions, the limitations of ultrasound, and the shape of the orifice. Some of these can be overcome with a good understanding of the principles and limitations of PISA and also newer three-dimensional techniques for quantification