Figure 5 : The pledgeted anchoringsutures on the innominate artery and proximal aortic arch shown. Using these anchoring sutures, the Ethibond suspensionsutures are then placed through them. The inset below shows the compression of the trachea by the innominate artery and presence of the thymus (yellow structure) acting as a space occupying structure in a cross-sectional view.
In order to get a good purchase on the artery, horizontal mattress felt pledgeted sutures with 5-0 Prolene™ sutures (Ethicon, Somerville, NJ) with either a BV-1 or a RB-2 needle are used on the artery in a partial thickness manner as the anchoring sutures. Using these felt pledget as anchors, 4-0 or 3-0 Ethibond® excel (Ethicon, Somerville, NJ) suspension sutures with a RB-1 needle are passed through the sternal table to pull the innominate artery anteriorly towards the posterior aspect of the sternal table. At, times when the sternal table is particularly thick as in an older child, a French eye needle with a larger gauge and size is used to facilitate the passage of the suture. The advantage of the this composite suture technique is use of a fine sutures such as a 5-0/ 6-0 Prolene suture with a fine needle supported with pledgets on the arterial structures as an anchoring sutures and the use of a more robust suture such as a 3-0/4-0 Ethibond suture with a stronger needle to pass through the full thickness of the sternal table as a suspension suture (Figure 5, 6 ). Also, if the suspension sutures were to break during the securing process, a new suture can be easily replaced. For a left aortic arch, the left half of the sternal table is chosen and vice versa. Before tying down the Ethibond sutures on the anterior aspect of the sternal table, a mediastinal Blake® drain (Ethicon, Somerville, NJ) is placed to drain the mediastinum. The tip of it is tucked into the pericardial space to drain it. The drain is exited retrosternally just below the xiphoid process (Figure 7 ). A set of about 2 to 3 sternal wires are placed. The sternal tables are partially bought together except for a 1 cm gap.
With real time flexible bronchoscopic guidance, the Ethibond® excel sutures are cinched up and tied on the anterior aspect of the sternal table. Simultaneously, the innominate artery and the aortic arch can be observed gradually moving up towards the posterior aspect of the sternal table. The partial gap in the sternum helps with the visualization of any of the anchoring sutures cutting through the innominate artery or snapping of the suspension sutures as the sutures are tightened. The suture on the aortic arch is tightened first followed by the sutures distal to it as it is the most robust of the sutures. The innominate artery should rise up and should be well opposed to the posterior sternal table to optimize the AA. In one case, there was a cut through of the anchoring suture on the innominate artery requiring a revision. With all the sutures tightened and tied, the anterior compression on the trachea should be relieved and generally there is ≤ 20% residual tracheal stenosis (Figure 6 ). If this result is not achieved, then alternate factors causing the compression need to be looked for. This can range from an innominate artery arising further leftward on a left aortic arch which cannot be sufficiently addressed just by an aortopexy or an intrinsic tracheal abnormality. In such cases, the partial sternotomy is converted to a full sternotomy to evaluate the anatomy further.