A Nomogram for Measurement of Mitral Valve Area by Proximal Isovelocity Surface Area Method

INTRODUCTION: Although its accuracy has been documented in many studies, the proximal isovelocity surface area (PISA) method is not used widely for mitral valve area (MVA) measurement. In this study, we prepared a new nomogram and tested its use in MVA assessment. MATERIAL AND METHODS: The study included 23 patients (age: 27 +/- 5 years) with mitral stenosis, of whom 7 were in atrial fibrillation. The MVA was measured by four methods: planimetry (PL) (reference method), pressure-half time (PHT), conventional PISA (CP), and nomogram (Nomo) methods. The nomogram included two unknowns: (1) r; the radius of the first PISA section; (2) a; the length of the border opposite to the PISA angle in the triangle with both adjacent borders of 1 cm. The nomogram was also tested for its popularity potential by eight echocardiographers, none of whom were included in the author list. RESULTS: Mean MVA(PL) was 1.85 +/- 0.53 cm(2) (range: 0.72-2.99), mean MVA(PHT) was 1.72 +/- 0.56 cm(2) (range: 0.91-3.30), mean MVA(CP) was 1.69 +/- 0.45 cm(2) (range: 0.97-2.54), and MVA(Nomo) was 1.70 +/- 0.44 cm(2) (0.96-2.49). The nomogram correlated with planimetry (r = 0.87; P < 0.001), pressure half-time (r = 0.71; P < 0.001) and conventional PISA (r = 0.99; P = 0.000) methods. The nomogram method also correlated with planimetry in patients with atrial fibrillation (r = 0.81; P = 0.026). The echocardiographers found that the nomogram is superior to the planimetry and conventional PISA methods but inferior to the pressure half-time method in terms of simplicity. CONCLUSION: The new nomogram is potentially helpful in measurement of MVA. It may be used as an additional method in assessing severity of mitral stenosis.