Endoscopic identification of endoluminal esophageal landmarks for radial and longitudinal orientation and lesion location

Figure 3 Identification of the left main bronchus and left atrium landmarks. A: A concave, non-pulsatile, extrinsic esophageal compression (blue lines) is observed 25 cm from the incisors. The landmark is radially oriented at the anterior esophageal quadrant, between 9 and 12 o’clock. B: A convex, pulsatile, extrinsic esophageal compression (blue lines) is observed 31 cm from the incisors. The landmark is radially oriented at the anterior esophageal quadrant, between 9 and 12 o’clock.