C  2007, the Authors Journal compilation C  2007, Blackwell Publishing, Inc. DOI: 10.1111/j.1540-8175.2007.00488.x ORIGINAL INVESTIGATIONS A Nomogram for Measurement of Mitral Valve Area by Proximal Isovelocity Surface Area Method Mehmet Uzun, M.D., Oben Baysan, M.D., Celal Genc, M.D., Mehmet Yokusoglu, M.D., Hayrettin Karaeren, M.D., and Ersoy Isik, M.D. Gulhane Military Medical Academy, Department of Cardiology, Ankara, Turkey 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. (ECHOCARDIOGRAPHY, Volume 24, September 2007) mitral valve area, PISA method Mitral stenosis (MS) is the most prevalent rheumatic heart disease in developing coun- tries that necessitates intervention. According to the ACC/AHA guidelines, symptomatic sta- tus and mitral valve area (MVA) are the major determinants of the treatment strategy. 1 Mea- surement of MVA has developed significantly after the introduction of echocardiography into clinical practice. Most frequently used methods are pressure half-time (PHT) method and plani- metric method (PL). In most instances, these two are sufficient for a reliable estimation of MVA. However, in certain circumstances, such as accompanying aortic insufficiency, 2 mitral regurgitation, 3 massive calcification of the mi- Address for correspondence and reprint requests: Mehmet Uzun, Barisyolu Cd. No:4/3 Esertepe, Ankara, Turkey. Fax: 90-392-8156367; E-mail: muzun1@yahoo.com tral valve, 4 advanced age, 5 valvuloplasty, 6 and atrial fibrillation, 7 these methods may provide limited help in measuring the MVA. To over- come these limitations, the proximal isoveloc- ity surface area (PISA) method has been sug- gested. The PISA method is a different way of apply- ing the continuity principle to the MVA mea- surement. According to the PISA method, the flow through a narrow orifice is assumed to form concentric layers of same velocity proximal to the orifice. The flow through these surfaces is equal to the flow through the stenotic orifice. Because these layers are also assumed to be hemispheric, it is possible to measure the sur- face area of these shelves. In cases of MS, the MVA is calculated by the formula: MVA = 2 × π × r 2 × (V al /V max ) × θ/180 (1) Vol. 24, No. 8, 2007 ECHOCARDIOGRAPHY: A Jrnl. of CV Ultrasound & Allied Tech. 783