Patent Ductus Arteriosus
INCISION
The ductus arteriosus can be adequately exposed through a small left anterior thoracotomy. A limited left posterolateral thoracotomy through the third or fourth intercostal space partially dividing the latissimus dorsi muscle and preserving the serratus anterior muscle provides good exposure and is more commonly used. The skin incision can be quite short, especially in premature infants. If a right aortic arch and right ductus are present, a right thoracotomy approach must be used.
SURGICAL ANATOMY
The ductus arteriosus runs parallel to the aortic arch from the superior aspect of the origin of the left pulmonary artery and passes through the pericardium to join the medial margin of the aorta at an acute angle just opposite the origin of the left subclavian artery (Fig. 14.1). The left vagus trunk enters the thorax from the root of the neck in a groove between the left subclavian artery and the left common carotid artery, crosses the aortic arch and the ductus arteriosus, and continues downward. The recurrent laryngeal branch curves around the ductus arteriosus and extends back upward into the neck. The vagus nerve gives rise to many other small branches that are important tributaries to the pulmonary and cardiac plexuses. There are usually some lymph nodes buried in the hilum of the left lung that sometimes extend upward near the inferior margin of the ductus arteriosus. The left phrenic nerve enters the thorax medial to the vagus nerve and continues downward on the pericardium.
Technique for Exposing and Dissecting the Ductus Arteriosus
The left lung is retracted inferiorly and medially to expose the ductus arteriosus. The parietal pleura is divided longitudinally behind the vagus nerve if the intention is to retract the vagus nerve medially. Alternatively, a pleural incision may be made between the vagus and phrenic nerves when the vagus nerve is to be retracted laterally (Fig. 14.1). The incision of choice is extended superiorly along the left subclavian artery and inferiorly to the left hilum. The pleural edges are then suspended.
In an infant, the ductus is exposed by sharp dissection with scissors both from above and below. A blunt right-angled clamp or preferably a Waterson dissector/Dennis-Browne is then carefully passed above and below the ductus to create a plane for its ligation or division. The ductus can most often be occluded by the application of a metal clip.
Recurrent Laryngeal Nerve Location with Medial RetractionTo facilitate dissection and exposure of the posterior aspect of the ductus arteriosus, many surgeons prefer that the vagus nerve and its recurrent laryngeal branch be reflected medially on the pleural flap (Fig. 14.2). The surgeon should be aware that traction of the nerve toward the pulmonary artery causes the recurrent nerve to lie along a diagonal course behind the ductus arteriosus. Therefore, care must be taken to ensure that the recurrent nerve is not injured during dissection. Alternatively, the vagus nerve and its branches can be isolated and retracted laterally to ensure their protection during the process of dissection of the posterior wall of the ductus. 
Complete Exposure of the DuctusSpecial care should be taken when dissecting near the angle between the pulmonary artery and the ductus arteriosus because the ductus is particularly susceptible to injury. A lappet of pericardium usually covers the ductus anteriorly. It should be dissected free to ensure complete exposure of the ductus (Fig. 14.3). Similarly, it is essential to separate the cranial aspect of the ductus from the transverse aortic arch—this maneuver more clearly demonstrates the angle that the clip will need to follow so as not to either impinge upon the arch or only partially occlude the ductus (Fig. 14.4). 
Technique for Dividing and Ligating the Ductus Arteriosus
The vagus and recurrent laryngeal nerves are identified so that they are not divided inadvertently. Two heavy
Ethibond sutures are individually passed behind the ductus, which is then securely ligated (Fig. 14.5). Some favor using a 5-0 or 6-0 Prolene taking occasional adventitial bites circumferentially around the ductus to secure the tie. A purse-string suture of 4-0 Prolene may be placed between the ligatures to secure complete occlusion of the ductus (Fig. 14.5, inset).
Ethibond sutures are individually passed behind the ductus, which is then securely ligated (Fig. 14.5). Some favor using a 5-0 or 6-0 Prolene taking occasional adventitial bites circumferentially around the ductus to secure the tie. A purse-string suture of 4-0 Prolene may be placed between the ligatures to secure complete occlusion of the ductus (Fig. 14.5, inset).
 FIG. 14.1 Surgical anatomy of the ductus arteriosus. A: This incision line is used if the vagus nerve is to be retracted medially. B: This incision line is used if the vagus nerve is to be retracted laterally. |
 FIG. 14.2 Medial reflection of the vagus nerve on the pleural flap. |
 FIG. 14.3 Dissecting the lappet of pericardium to ensure complete exposure of the ductus. |
Alternatively, the ductus is divided between clamps and oversewn with fine, nonabsorbable sutures (Fig. 14.6). This technique is particularly useful when the ductus is exceptionally short and large. Another option is to occlude the ductus with one or two metal clips. This latter technique is especially applicable to premature infants and is the most commonly practiced.
 FIG. 14.4 Using a Waterston dissector to expose and separate the transverse arch from the cranial aspect of the ductus, and freeing the recurrent nerve from the inferior aspect. |
Injury to the Recurrent Laryngeal Nerve during Ligation of the Ductus ArteriosusThe surgeon must always pay special attention to the recurrent laryngeal nerve. It can easily be divided during ductus mobilization. It can also be caught in the ligature, metal clip, or ductal clamp. 
 FIG 14.5 Ligation of the ductus. Inset: Securing the occlusion with purse-string sutures. |
 FIG. 14.6 Dividing the ductus arteriosus between clamps and oversewing it with fine, nonabsorbable sutures. |
A Ductus Arteriosus TearThe ductus arteriosus is liable to be injured and torn any time during dissection, ligation, or division, resulting in massive hemorrhage. Digital pressure over the ductus usually controls the bleeding and provides adequate exposure in a dry field. The aorta can then be temporarily clamped above and below the ductus while the torn ductus is oversewn with nonabsorbable sutures. The pulmonary artery end of the ductus can be similarly oversewn. Occasionally, this end of the ductus, if completely severed, may retract medially and its
exposure may become impossible. Under these circumstances, while continuing digital control of the bleeding, the surgeon must gain access to the pericardium by incising it longitudinally, anterior to the left phrenic nerve. Control of bleeding from the ductal end is then achieved by temporarily occluding the left pulmonary artery from within the pericardium. The ductal opening is then oversewn under direct vision in a relatively dry field (Fig. 14.7).
exposure may become impossible. Under these circumstances, while continuing digital control of the bleeding, the surgeon must gain access to the pericardium by incising it longitudinally, anterior to the left phrenic nerve. Control of bleeding from the ductal end is then achieved by temporarily occluding the left pulmonary artery from within the pericardium. The ductal opening is then oversewn under direct vision in a relatively dry field (Fig. 14.7).
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