Therapy for Patent Arterial Duct and Vascular Rings
3.1.2 Surgical Techniques
22.214.171.124 Single Ligation Technique
As noted, Fig. 3.3shows exposure of a PAD through a left thoracotomy. The course of the recurrent laryngeal nerve is noted as the clamp is placed around the ductus arteriosus (inferiorly to superiorly) after appropriate dissection is performed. Figure 3.4 shows the successful placement of the suture, and Fig. 3.5 shows the ligation.
126.96.36.199 Double Ligation Technique (Ligation and Clip Application)
Figure 3.6 shows a completed single ligation of the PAD with the application of the hemoclip in progress. The laryngeal nerve is plainly seen. Figure 3.7 shows the completed operation with obliteration of the PAD using one suture and the hemoclip application. This technique can be used if the pulmonary artery side of the PAD is very thin and would be subject to injury with secondary placement of another suture.
188.8.131.52 Double Ligation Technique
Figure 3.8 shows a completed singleligation of the PAD close to the descending aorta. A second suture has been placed around the arterial duct and through the ductal adventitia, with the intent of performing the double ligation technique. Figure 3.9 shows suture being placed in the adventitia of the ductus arteriosus closer to the pulmonary artery to ensure ligation in a separate location. Figure 3.10 shows the completed procedure. Preservation of the recurrent laryngeal nerve is noted.
184.108.40.206 Ligation and Division Technique
When adolescents or adults present with a large PAD that is not amenable to catheter intervention, the ligation and division technique is recommended to avoid the pitfalls of recurrence. Figure 3.11 shows the complete dissection of the PAD, recurrent laryngeal nerve, and the ductal clamps being placed on the aortic and pulmonary portion of the PAD. The duct is subtotally transected to provide traction between the cut edges in the unwanted event of clamp displacement. This allows relatively easy reapplication of the vascular clamp. Suture lines are started on both the aortic and pulmonary portions of the duct, thereby having another retraction point in the event of clamp dislodgment. The scissors show the transection of the ductus arteriosus in progress. Once the ductus is completely divided, both the aortic and the pulmonary artery stumps are oversewn in a two-layer technique, shown in Fig. 3.12. Figure 3.13 shows the application of mattress sutures before the clamps are removed, to avoid the presence of gaps. Figure 3.14 shows the site after removal of the clamps, with hemostasis and preservation of the recurrent laryngeal nerve. The pleural edges are usually closed over the repair before chest closure.
220.127.116.11 PAD Closure Using Cardiopulmonary Bypass Technique
Although quite rare because of transcatheter device techniques, occasionally a large PAD that is calcified may require a transmediastinal approach and closure using cardiopulmonary bypass. Figure 3.15 shows a calcified large PAD that has been approached through a median sternotomy. Aortobicaval cardiopulmonary bypass has been instituted, with application of an aortic cross clamp and antegrade cardioplegia. Systemic cooling is performed to at least 28 °C to perform low-flow technique for transpulmonary exposure of the PAD. After the conditions are acceptable and a low-flow state is enacted, the patient is placed in the Trendelenburg position and a longitudinal pulmonary arteriotomy is performed, with placement of a polytetrafluoroethylene (PTFE) patch at the orifice of the PAD. Figure 3.16 shows the beginning of placement of this patch with the running suture technique. Figure 3.17 shows the completion of the patch placement; at this point, the cardiopulmonary bypass flow can be increased and the patient can be rewarmed. Figure 3.18 shows a completed arteriorrhaphy of the pulmonary artery and separation from cardiopulmonary bypass.
3.2 Vascular Rings in the Adult
Though they are generally found in infants and children, occasionally vascular rings can be diagnosed in an adult because chronic symptoms have been misdiagnosed, or symptoms have had more recent onset from insidious vascular compression. Surgical options for adults may differ from those for young children. For example, the subclavian artery cannot be readily divided without reimplantation, aortic diverticulum compression may require aortic resection, and chronic tracheal compression may require more extensive maneuvers. In any case, a thorough understanding of the embryologic development and resultant anatomy helps the surgeon resolve unanticipated anatomic findings during surgery.
3.2.1 Etiology and Anatomy
The phrase “vascular ring” refers to a group of vascular anomalies that result from abnormal development of the aortic arch system and cause compression of the trachea, esophagus, or both. The vascular rings that form a true, complete ring and encircle both the esophagus and trachea are the double aortic arch and the right aortic arch with left ligamentum arteriosum. Partial vascular rings include innominate artery compression syndrome, pulmonary artery sling, and left aortic arch with aberrant right subclavian artery. These patients also present with symptoms from esophageal and tracheal compression. Because nearly two thirds of patients with a pulmonary artery sling have associated complete tracheal rings (the so-called ring/sling complex), one must be prepared to repair the trachea at the time of pulmonary artery sling surgery. The double aortic arch is typically approached through a left thoracotomy, as is the right aortic arch with left ligamentum. Patients with innominate artery compression syndrome are approached through a right anterolateral thoracotomy. Finally, patients with a pulmonary artery sling and/or tracheal stenosis are approached through a median sternotomy, and the operation is facilitated by cardiopulmonary bypass.
Knowledge of the embryologic etiology of vascular rings is important to understand the subtle variations in anatomy that may confound treatment options. Figure 3.19 illustrates the embryonic development of vascular rings, showing the fetal aortic arch system. Six pairs of aortic arches develop between the dorsal and ventral aorta. The first, second, and fifth aortic arches regress. Preservation or deletion of different segments of the remaining embryonic arches results in either the double aortic arch as shown in Fig. 3.20, the right aortic arch with left ligamentum as shown in Fig. 3.21, or the normal left aortic arch as shown in Fig. 3.22.
Depending on which portions of the arch remain or are deleted, the variety of potential combinations is nearly infinite. For example, the double aortic arch can be either right arch dominant, left arch dominant, or have balanced arches. The most common is right arch dominant (80%) (Fig. 3.23). Patients with a right aortic arch and left ligamentum may have a retroesophageal left subclavian artery (Fig. 3.24) or mirror-image branching, in which a left brachiocephalic artery gives rise to the left common carotid and left subclavian arteries (Fig. 3.25). In patients with mirror-image branching, the location of the ligamentum determines whether a vascular ring is present. If the ligamentum originates from the innominate artery (brachiocephalic artery) then there is not a complete ring (Fig. 3.25), but if the ligamentum originates from the descending thoracic aorta and connects to the main pulmonary artery, then these patients would have a vascular ring. A patient with a left aortic arch and an aberrant right subclavian artery is illustrated in Fig. 3.26. Most of these patients do not have symptoms related to esophageal compression by the subclavian artery. Indications to repair this entity are rare and are usually related to enlargement over time of a Kommerell diverticulum serving as the base of the right subclavian artery.