title: Optimal projection for transcatheter aortic valve implantation determined from the reference projection angles.
abstract: BACKGROUND
  An optimal fluoroscopic working view projection (OP) with all three aortic sinuses aligned is crucial during trans-catheter aortic valve implantation (TAVI). The aim of this study was to identify simple reference projection angles, which would act as a starting point for the operator to help determine OP for patients undergoing TAVI.
  
  
  METHODS
  During the period under consideration, 50 patients underwent TAVI. Procedural data and outcomes were collected prospectively on a dedicated database. Optimal angiographic deployment angles were achieved for all patients by starting in an anteroposterior caudal 15 degrees projection and then adjusting according to the initial image, with multiple small volume contrast injections undertaken to determine when all three aortic cusps were aligned (OP).
  
  
  RESULTS
  OP angles for the 50 cases were plotted on a graph. After normality testing confirmed that all angles were normally distributed, regression analysis enabled a regression line to be calculated. The equation for the regression line was defined as cranial/caudal intercept -16.4 ± 1.5 (SE of the coefficient), P < 0.0001, slope of regression line LAO/RAO + 0.53 ± 0.1 (SE of the coefficient SE), P < 0.0001).
  
  
  CONCLUSIONS
  As the regression line and its equation represents an acceptable estimate of the true relationship between Cranial/Caudal and LAO/RAO, to determine OP while remaining close to the regression line we suggest starting in LAO = 8.9, Caudal = -11.4 (which represent the mean values of these two variables), and then increasing the caudal angle by approximately 0.5 degrees for every increase of 1 degree of the LAO angle or decreasing the caudal angle by 0.53 degrees for every decrease of 1 degree in LAO until all three aortic sinuses are in line which represents OP.
authors.affiliation: Sussex Cardiac Centre, Brighton and Sussex University Hospitals NHS Trust, Brighton, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Cockburn
authors.forename: Uday
authors.initials: U
authors.lastname: Trivedi
authors.forename: Adam
authors.initials: A
authors.lastname: de Belder
authors.forename: David
authors.initials: D
authors.lastname: Hildick-Smith
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000000981:diagnostic imaging*; D001027:Aortography; D006328:Cardiac Catheterization; D005260:Female; D005471:Fluoroscopy; D019918:Heart Valve Prosthesis Implantation / Q000379:methods*; D006801:Humans; D016014:Linear Models; D008297:Male; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D015641:Radiography, Interventional / Q000379:methods; D012189:Retrospective Studies; D013813:Therapy, Computer-Assisted; D016896:Treatment Outcome