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Figure 4 The coil position is adjusted by placing gentle traction on the snare. Note this maneuver results in wedging of the coil into the conical shaped ampulla for better occlusion. Comparing the coil position to the tracheal air column in Figure 3, note also the coil has been pulled more anteriorly by the snare. The first proximal loop (solid white arrowhead) is oriented parallel to the segment of the ductus that contains the minimum diameter as it enters the pulmonary artery. The horizontal alignment of the proximal coil loop to the ductus increases its occlusive abilities. The most distal coil loop (open arrowhead) maintains a perpendicular alignment to the ductus inside the aortic ampulla and will prevent the coil from embolizing through the ductus into the main pulmonary artery. White arrows = tracheal air column.