Stable wire positioning is critical to successful positioning and complete inflation of the balloon during pulmonary valvuloplasty. In the presence of a patent ductusarteriosus, wire can be advanced across the ductus and deep into the descending aorta (4a). Wire positioning is also possible with the distal wire placed in the left pulmonary artery (4b) or right pulmonary artery (4c). (black arrows = distal wire position; white arrows = residual narrowing, or “waist” in balloon, indicating that the balloon diameter is larger than the pulmonary valve annulus)