Left ventricular access point determination for a coaxial approach to the mitral annular landing zone in transcatheter mitral valve replacement.
J Cardiovasc Comput Tomogr. 2017 Jul - Aug;11(4):281-287. doi: 10.1016/j.jcct.2017.04.002. Epub 2017 Apr 7. Blanke P1, Park JK2, Grayburn P3, Naoum C2, Ong K2, Kohli K4, Norgaard BL5, Webb JG2, Popma J6, Boshell D7, Sorajja P8, Muller D7, Leipsic J2.
INTRODUCTION: To facilitate coaxial device deployment in transcatheter mitral valve replacement (TMVR), a coaxial approach to the mitral annular plane is needed. We sought to establish a method to determine an 'orthogonal' left ventricular (LV) access point for transapical TMVR and to quantitatively characterize its location in patients with severe mitral regurgitation using cardiac computed tomography.
METHODS: Cardiac CT data sets of 54 patients with moderate-severe mitral regurgitation evaluated for potential TMVR were analyzed. The D-shaped mitral annular contour was segmented and a 2-dimensional annular plane was derived, allowing for subsequent definition of the perpendicularly oriented mitral annular trajectory. The 'orthogonal' LV access point was defined as the transection point of mitral trajectory with the LV epicardial surface. The location of the access point was quantified by its epicardial distance from the true apex and by the rotational offset from a 3-chamber view.
RESULTS: LV access points orthogonal to the mitral annular plane were most frequently located in the anterolateral (n = 22, 40.7%) and anterior (n = 16, 29.6%), less frequently anteroseptal (n = 6, 11.1%) and inferolateral (n = 5, 9.3%) ventricular segment; none inferior or inferoseptal. The mean distance to the LV apex was 17.6 ± 7.7 mm. The mean forward rotational offset from the 3-chamber view was 96.4 ± 43.4°, relating to a mean forward rotational offset of 6.4 ± 43.4° in regard to a hypothetical, secondary 90° x-plane view. No significant difference between patients with degenerative mitral valve disease or functional mitral regurgitation was observed.
CONCLUSION: The location of the LV access point that provides an orthogonal trajectory to the mitral annular plane exhibits relevant inter-individual variability. It is commonly not identical with the true apex, and frequently localized in the anterolateral or anterior ventricular segments.