Background: The proximal isovelocity surface area (PISA) method is validated to quantify mitral regurgitation (MR) and ventricular shunt (VS). However, the two-dimensional echocardiography (2DE) PISA method assumes a hemispherical distribution of velocity factors proximal to the MR or VS orifice.
Aim: To assess the PISA shape by three-dimensional echocardiography (3DE) in a paediatric population with MR or VS. According to the true PISA shape, we suggest different models to calculate the MR or VS volume by the 3DE PISA method.
Methods: Thirty-one paediatric patients (aged 1month to 20years, median 69months) were included: 17 had MR and 14 had VS. The orifice area and volume of MR and VS were evaluated by 2DE. 3DE acquired the entire PISA volume at orifice level. The PISA shape was estimated according to three diameters as being hemispherical, prolate hemispheroid, oblate hemispheroid and hemiellipsoid.
Results: Data from 28patients were analysed. The PISA shape was variable: hemispherical, 11%; prolate hemispheroid, 43%; oblate hemispheroid, 32%; hemiellipsoid, 14%. Oblate hemispheroids occurred more frequently in the MR group (47%), whereas prolate hemispheroids occurred more frequently in the VS group (62%); hemispheres were scarce in both groups (10%). The mean MR or VS orifices and volumes measured by 2DE and 3DE were significantly different (0.123cm(2) versus 0.094cm(2) and 13.2mL versus 10.1mL, respectively; p=0.019).
Conclusions: 3DE describes the true surface of the PISA shape. In a paediatric population with MR or VS, the PISA is rarely hemispherical but is more often prolate or oblate hemispheroid.