2.3.1 3D manual TEE aortic annulus measurement
Multiple 3D zoom datasets were acquired and the dataset with the maximal aortic diameter was used for analysis. We routinely used biplane imaging from the aortic short axis view to ensure correct alignment of the orthogonal long axis plane through the maximal diameter. This has been previously shown to be a robust method of aortic annular measurement [37]. From our experience we find this easily reproducible. For 3D manual TEE aortic annulus measurement commercially available 3D software (Qlab 3DQ V10.1) was used. A multi-planar reconstructive mode was used to ensure accurate alignment of the aortic annulus. The data set was scrolled to maximal aortic valve opening in mid-systole and the 2 orthogonal long axis images (Figure 1 , frame B and C) aligned to open up the left ventricular outflow tract. The transverse plane(Figure 1 , frame A) was then aligned to transect through the aortic annulus at the insertion point of the aortic valve in both long axis views. The transverse plane was then used to measure both annulus area and minimum and maximum diameters.