title: Left ventricular access point determination for a coaxial approach to the mitral annular landing zone in transcatheter mitral valve replacement.
abstract: BACKGROUND
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada. Electronic address: phil.blanke@gmail.com.
authors.forename: Philipp
authors.initials: P
authors.lastname: Blanke
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Jong K
authors.initials: JK
authors.lastname: Park
authors.affiliation: Baylor Heart and Vascular Institute, Baylor University Medical Center, Dallas, TX, United States.
authors.forename: Paul
authors.initials: P
authors.lastname: Grayburn
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Christopher
authors.initials: C
authors.lastname: Naoum
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Ong
authors.affiliation: Tendyne Holdings, Roseville, MN, United States.
authors.forename: Keshav
authors.initials: K
authors.lastname: Kohli
authors.affiliation: Skejby University Hospital, Aarhus, Denmark.
authors.forename: Bjarne L
authors.initials: BL
authors.lastname: Norgaard
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: John G
authors.initials: JG
authors.lastname: Webb
authors.affiliation: Beth Israel Deaconess, Boston, MA, United States.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Popma
authors.affiliation: St Vincent's Hospital, Sydney, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Boshell
authors.affiliation: Minneapolis Heart Institute Abbott Northwestern Hospital, Minneapolis, MN, United States.
authors.forename: Paul
authors.initials: P
authors.lastname: Sorajja
authors.affiliation: St Vincent's Hospital, Sydney, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Muller
authors.affiliation: St. Paul's Hospital, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Jonathon
authors.initials: J
authors.lastname: Leipsic
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks; D006328:Cardiac Catheterization / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006350:Heart Valve Prosthesis; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery; D018579:Patient Selection; D011237:Predictive Value of Tests; D011474:Prosthesis Design; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed
keywords: TMVR; Transapical access; Transcatheter mitral valve implantation; Transcatheter mitral valve replacement