Abstract
Background: Left ventricular outflow tract diameter (LVOTD) is an important component in the calculation of aortic valve area (AVA). The timing when and the site where it is measured are different among each laboratory. We investigated the influence of the methods of measuring LVOTD on the assessment of AVA.
Methods: We included 200 aortic stenosis (AS) patients with AVA below 2.0 cm2 with use of the B method describing below. We retrospectively measured LVOTD in three different ways (A, B and C) and calculated AVA from each LVOTD measurement using the continuity equation. (A: at end-diastole, 5 mm below the aortic valve annulus, B: at early systole, 5 mm below the aortic valve annulus, C: at early systole at aortic valve annulus) We also measured the valve area using planimetry method (D) in 144 patients. We compared AVA from the four methods. We also checked grading of AS between B and C.
Results: The mean AVA was 1.25±0.42 cm2 with A method, 1.26±0.41 cm2 with B method, 1.40±0.48 cm2 in C method and 1.54±0.50 cm2 in D method. AVA was similar between A and B methods as well as between C and D methods. AVA was 18% smaller with B method and 10% smaller with C methods than with D method. AS was graded severe with B method than D method.
Conclusion: There is difference in the AVA assessment by different measurement methods of LVOTD, leading to the misleading of AS grading, probably because of the oval shape of the left ventricular outflow tract. LVOTD measurement at the aortic annulus should be considered to have better assessment.
