Background and purpose: Continuity equation to measure aortic valve area is limited by poor acoustic window or difficulty in obtaining acceptable Doppler signal. Our aim has been to analyze the accuracy of planimetry by transesophageal echocardiography to calculate aortic valve area and the impact of calcification on results.
Methods: Planimetry of aortic valve area by transesophageal echocardiography has been compared to continuity equation by transthoracic approach and the Gorlin formula in 26 consecutive patients with aortic stenosis. Degree of calcification was qualitatively estimated by the 3 methods and 2 groups were distinguished: group A (mild or moderate calcification) and group B (severe calcification).
Results: An excellent agreement between continuity equation and the Gorlin formula was found (mean difference: 0.03 +/- 0.15 cm2). Agreement between transesophageal planimetry and the Gorlin formula was poor (mean difference: 0.14 +/- 0.25 cm2). Planimetry and the Gorlin formula demonstrated an excellent agreement in group A (mean difference: -0.03 +/- 0.17 cm2). By contrast, agreement in group B was not acceptable (mean difference: 0.27 +/- 0.22 cm2).
Conclusions: 1) continuity equation by transthoracic echocardiography is useful in calculating aortic valve area. 2) aortic planimetry by transesophageal echocardiography is an excellent method in noncalcified aortic valves, and must not be used on severely calcified valves.