Figure 2.10 shows the PAB in place; the inset reveals the gradual suture tightening of the band to achieve the optimal result.
2.2 Pulmonary Artery Band Takedown and Repair
In those rare instances in adults when the surgeon must take down a PAB and repair the pulmonary artery, two techniques are used and require cardiopulmonary bypass, removal of the PAB, and repair by either direct anastomosis or a patch technique. Each technique has advantages and disadvantages.
2.2.1 Excision and Direct Anastomosis Technique
Figure 2.11 shows the completed dissection of a patient with PAB in preparation for excision and direct anastomosis. After cardiopulmonary bypass, the PAB is resected and removed with the cuff of pulmonary artery wall (Fig. 2.12, dotted lines). Figure 2.13 demonstrates the completion of the banded segmental resection, leaving native proximal and distal pulmonary artery segments. The reanastomosis is concluded using the interrupted suture technique, as shown in Fig. 2.14. Figure 2.15 shows the completed anastomosis.
2.2.2 Patch Pulmonary Artery Arterioplasty
Repair can also be performed by wide incisions and placement of a biologic or synthetic patch. Figure 2.16 demonstrates removal of the PAB during cardiopulmonary bypass. The initial incision in the distal pulmonary artery is shown, and the proposed incisions are noted by dotted lines that extend into the anterior pulmonary artery sinuses of Valsalva. Patch augmentation is performed with a pantaloon-shaped patch of autologous pericardium or prosthetic material (polytetrafluoroethylene [PTFE]), as in Fig. 2.17. The suture line can be started proximally or distally, depending on the situation. Figures 2.18 and 2.19 show the placement of the patch using the running suture technique.
No single recommended procedure applies to all systemic-to-pulmonary artery shunts in the adult with congenital heart disease. In most cases, a systemic-to-pulmonary artery shunt may be indicated for patients who have had prior failed shunts resulting in distorted pulmonary artery anatomy that extends into the deep hilum of the lungs. Other patients may present late in life, diagnosed with tetralogy of Fallot, pulmonary atresia, and major arterial pulmonary collateral arteries. These patients may be treated with staged unifocalization and ipsilateral shunt creation to the reconstructed amalgamation of pulmonary arteries. Other patients with single-ventricle palliation resulting in differential pulmonary artery flow (too much to one side; not enough to the other side) may have developed pulmonary hypertension that would contraindicate a Fontan operation and cardiac transplantation. Systemic-to-pulmonary artery shunt to the under-perfused lung may help relieve the cyanosis.
In circumstances that may require increased flow to the right pulmonary artery (e.g., discontinuous pulmonary arteries, preparation for unifocalization, or terminal palliation), a median sternotomy is preferable for exposure, accesses to the brachiocephalic arteries, and ease of cardiopulmonary bypass if the need arises. Figure 2.20 shows transmediastinal exposure of the epicardial surface of the heart, demonstrating the relationships between the ascending aorta, the brachiocephalic arteries, the right pulmonary artery (dashed lines), and the pericardial reflections. In preparation for the systemic-to-pulmonary artery shunt (which in this case will be a shunt from the innominate artery to the right pulmonary artery), the azygous vein is dissected, ligated, and divided (Fig. 2.21) to accommodate an unconstricted pathway for the proposed shunt. Pledgeted sutures are placed in the adventitia of the superior caval vein to facilitate exposure. In addition, the PTFE shuntis measured for size, length, and contour (Fig. 2.22). Heparin (1 mg/kg) is administrated, after which time the innominate artery is clamped in such a manner that the inferior portion of the course of the artery rotates into the operative field. This maneuver optimizes the relationship and flow characteristics between the artery, the graft, and the pulmonary artery. The artery is incised, and thebeveled graft is sutured end-to-side into the innominate artery (Fig. 2.23). Any coordinated suture technique can be used. We prefer to start the anastomosis at the proximal end of the innominate artery and perform the posterior suture line first (Fig. 2.24), followed by the anterior suture line (Fig. 2.25). Once the anastomosis is complete, the occluding clamp is left in place to prevent clot formation at the proximal anastomotic site during the distal anastomosis (Fig. 2.26). The right pulmonary artery is controlled using a proximal clamp to control the right upper pulmonary branch arteries, and distal snuggers to control the lower pulmonary branch arteries. An incision is made in the pulmonary artery that is intentionally shorter than what would seem to be an obvious length because the pulmonary artery stretches and may, in the end, be too long. Careful consideration ensures a properly sized anastomosis that mitigates against the possibility of anastomotic stenosis. Theposterior suture line (Fig. 2.27) is followed by the anterior suture line (Fig. 2.28). De-airing maneuvers are performed, and all occluding clamps and snuggers are removed in succession. Figure 2.29 shows the completed systemic-to-pulmonary artery shunt. This classic systemic-to-pulmonary artery shunt is shown to demonstrate the principles that attend creation of such a shunt. In most adult patients with cyanotic congenital heart disease, however, the circumstances are much more complicated and require careful consideration of the major arterial pulmonary collateral arteries, simultaneous pulmonary artery repair, and various forms of ventricular-to-pulmonary artery connection.