Although surgical closure of the patent ductus arteriosus in premature newborns is technically straightforward and generally safe, there are several well-recognized potential complications including: bleeding, recurrent laryngeal nerve injury, and erroneous ligation of a major vessel such as the left pulmonary artery. The operation is best performed with the patient in the NICU with proper anesthesiology support and monitoring, preferably including an arterial cannula, secure intravenous access, and at least one blood volume (80–100 mL/kg) of packed red blood cells warmed and ready to infuse at a moment’s notice.
Indications for surgery are well-established and there is usually consensus among the clinicians involved in the patient’s care regarding the need for intervention. It is preferable for the patient to have had an echocardiogram performed less than 48 h before the proposed operation to be certain that the ductus is still large enough to warrant ligation. Indomethacin might make the ductus more friable and could make bleeding more difficult to control due to its effect on platelet function, but its recent use is not a contraindication to an operation.
The thoracoscopic approach to ductus ligation in premature newborns appears to be safe and effective and will likely eventually become standard. Nevertheless, the open approach is still acceptable and does not require a large incision. A small left posterolateral muscle-sparing incision, rarely more than 3 cm in length, is made near the tip of the scapula and the chest is entered through the fourth intercostal space. In general, the more posterior the incision, the smaller it needs to be. An extrapleural dissection provides optimal exposure, allows easier containment of bleeding should it occur, and obviates the need for a chest tube. The lung is gently retracted anteriorly using a small malleable Deaver retractor bent at 90° and fixed to the Finochietto retractor by means of an Allis clamp. Although proximal and distal control of all major vascular structures is risky and unnecessary, all structures should be clearly identified with certainty, including the aortic arch, the descending aorta, the subclavian artery, the pulmonary artery, the ductus arteriosus, and, perhaps most importantly, the vagus and recurrent laryngeal nerves. Identification of the nerves helps to ensure that the structure to be divided is in fact the ductus and helps to avoid vocal cord paralysis, a morbid complication to be avoided if at all possible. The ductus can usually be safely dissected circumferentially to allow passage of two 2-0 silk ligatures; however many have proposed that the risk of bleeding is lessened by only partially dissecting the ductus and only to the degree necessary to allow placement of a hemoclip.
Erroneous ligation of a vascular structure other than the ductus is surprisingly easy to do, but should be quite rare for the experienced surgeon. The risk is minimized by identifying the vagus and recurrent laryngeal nerves and all pertinent vascular structures clearly. It is also important to test-clamp the structure to be ligated to confirm that post-ductal blood pressure improves (an arterial cannula with continuous pressure tracing is helpful), oxygen saturation remains high, and lower extremity perfusion is intact. If errant ligation does occur, it must be recognized early and the ligature or clip removed as soon as possible if there is any hope of survival.
Bleeding from an injured ductus can be astonishingly brisk. It is important to maintain poise and to use a careful approach to control the bleeding. It is important to have excellent suction, a second pair of hands, and good exposure. Blind placement of a hemoclip on the proximal ductus can be effective in slowing down the bleeding but must be done with care as injury of the ductus at the aortic take-off can make things much worse. Frantic attempts to control the bleeding almost invariably result in recurrent laryngeal nerve injury. Parents need to be aware of the potential for bleeding and that it can sometimes result in death of the infant.
Parents should be warned that the infant’s clinical condition will likely not improve immediately after ligation of the ductus. Instead, they usually become relatively fluid overloaded and require ongoing support until they can diurese. Most will begin to improve by the third or fourth postoperative day.