title: Multislice computed tomography-based prediction of the implantation plane in transcatheter aortic valve implantation: determination of the line of perpendicularity and the implanter's views.
abstract: OBJECTIVE
  We demonstrate a multislice computed tomography (MSCT)-based method to calculate the prediction of the so-called 'line of perpendicularity' (LOP) and the 'implanter's views' (IVs) for transcatheter aortic valve implantation (TAVI) procedures. The LOP represents all possible angiographic angulations that result in an orthogonal view to the aortic annulus plane. The IVs allow visual confirmation of correct implantation planes, and are crucial for the commissural aligned implantation of second-generation TAVI prostheses.
  
  
  METHODS
  The LOP and IVs of 335 concomitant patients were prospectively analysed using multiple plane reconstruction (MPR) of the patient's MSCT scans. Exclusion criteria were bicuspid valves (n = 18) and valve-in-valve TAVI (n = 15). In the MPRs, the aortic cusps' lowest points were marked. With the marker's three-dimensional coordinates, the graph of the LOP with the IVs was calculated and plotted using vector mathematics. In the last 244 cases, the IV with the right coronary cusp in front was chosen for the first aortic root angiogram of the TAVI procedure. The finally used angulation was confirmed by aortic angiogram prior to the valve implantation. Solid angle differences that show the combined left anterior oblique/right anterior oblique and cranio/caudal movement of the C-arm allow quantification of corrections as well as demonstrate interindividual variations.
  
  
  RESULTS
  There is a broad interindividual variation of the aortic valve's topology with solid angle variations of up to 74°. The shape of the LOPs is extremely varying, especially regarding the slope of the curve that indicates differences in valve orientations. Among the 244 patients for whom we used the prediction for the procedure, the first angiogram was considered perfect for implantation without further corrections in 97% (n = 237) of them. In case of the 7 patients with subsequent corrections, the mean solid angle between the prediction and the final angiogram prior to implantation was 6.2° (±5°); the largest correction was 14°.
  
  
  CONCLUSIONS
  Prediction of the implantation plane by analysing the patient's MSCT is highly reliable in achieving an adequate view of the aortic annulus in TAVI. The analysis of LOPs showed the large interindividual differences that permit using a standard implantation plane. Therefore, we strongly recommend determining the LOP and IVs during the patient's screening process in each single TAVI case.
authors.affiliation: Klinik und Poliklinik für Herz-, Thorax- und herznahe Gefäßchirurgie, University of Regensburg Medical Center, Regensburg, Germany andreas.holzamer@ukr.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Holzamer
authors.affiliation: Klinik und Poliklinik für Herz-, Thorax- und herznahe Gefäßchirurgie, University of Regensburg Medical Center, Regensburg, Germany.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Sitka
authors.affiliation: Klinik für Herz- und Kreislauferkrankungen, Deutsches Herzzentrum München, Technische Universität München, Munich, Germany DZHG (German Center for Cardiovascular Research), Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Hengstenberg
authors.affiliation: Klinik und Poliklinik für Herz-, Thorax- und herznahe Gefäßchirurgie, University of Regensburg Medical Center, Regensburg, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Schmid
authors.affiliation: Klinik und Poliklinik für Innere Medizin II, University of Regensburg Medical Center, Regensburg, Germany.
authors.forename: Kurt
authors.initials: K
authors.lastname: Debl
authors.affiliation: Klinik und Poliklinik für Innere Medizin II, University of Regensburg Medical Center, Regensburg, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Maier
authors.affiliation: Klinik und Poliklinik für Herz-, Thorax- und herznahe Gefäßchirurgie, University of Regensburg Medical Center, Regensburg, Germany.
authors.forename: Daniele
authors.initials: D
authors.lastname: Camboni
authors.affiliation: Klinik für Herz- und Kreislauferkrankungen, Deutsches Herzzentrum München, Technische Universität München, Munich, Germany DZHG (German Center for Cardiovascular Research), Munich, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Husser
authors.affiliation: Klinik und Poliklinik für Herz-, Thorax- und herznahe Gefäßchirurgie, University of Regensburg Medical Center, Regensburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hilker
mesh_terms: D001021:Aortic Valve / Q000033:anatomy & histology / Q000601:surgery*; D005471:Fluoroscopy; D006801:Humans; D061330:Multidetector Computed Tomography / Q000379:methods; D065467:Transcatheter Aortic Valve Replacement / Q000379:methods*
keywords: Angulation; Implanter's view; Line of perpendicularity; Transcatheter aortic valve implantation