Cardiac catheterization is carried out by introducing a catheter into the coronary sinus, acquiring a first set of 2-dimensional images of the catheter, thereafter acquiring a second set of 2-dimensional images of the catheter, and creating respective 2-dimensional models of the catheter in synchronized frames of the first set and the second set. The 2-dimensional models include respective tracked 2-dimensional paths of the catheter. The first and second sets are synchronized by identifying frames that are in respective phases of the cardiorespiratory cycle. First and second 3-dimensional models of the catheter are constructed from the synchronized frames, and geometrically transformed to minimize a distance function between the two models.
