Figure 9  Typical bronchoscopic view of a) mild indentation of right lateral wall of trachea with posterior vascular compression of left main bronchus origin. b) Significant vascular compression of the right lateral tracheal wall by the right pulmonary artery as it wraps behind the trachea with cartilage distortion. Trachelais muscle is present. c) Complete rings with limited visibility of carinal bifurcation. The cartilage rings cross the midline on the floor of the trachea and there is no visible trachealis muscle.