CHAPTER 13 Patent Ductus Arteriosus
Step 1: Surgical Anatomy
♦ Because the dissection performed is typically limited, it is essential to identify key aspects of the juxtaductal anatomy before proceeding with ductal closure.
♦ The ductus arteriosus may be larger than the distal aortic arch, particularly in premature infants, and may be mistaken for the arch itself. Because the aortic arch follows a course in the mediastinum from right to left, the distal arch and isthmus typically lie in a slightly deeper plane, just superior to the ductus arteriosus. As a result of these factors, the ductus may be mistaken for the aortic arch itself, leading to unnecessary additional dissection and injury to other structures, such as the left pulmonary artery, the recurrent laryngeal nerve, or the aorta itself.
♦ With the typical dissection, the left pulmonary artery is not completely exposed, although its location should be appreciated at the superior aspect of the hilum of the lung.
♦ The phrenic nerve should be well anterior of the area of dissection, lying on the thymus in the superior mediastinum and coursing anterior to the pulmonary hilum.
♦ The vagus nerve is typically easily identified just anterior to the descending aorta. The recurrent laryngeal nerve leaves the vagus to loop around the inferior margin of the ductus arteriosus. Its relationship to the ductus arteriosus is the most reliable method of confirming the identity of the ductus, although its location results in its injury being the most common complication of juxtaductal operations.
Step 2: Preoperative Considerations
♦ Indications for ductal closure generally fall into two main categories dictated by the size of the ductus and the age of the child.
Congestive heart failure in the premature infant population is the most common indication for surgical ductal closure. Whereas echocardiography may demonstrate the presence and approximate size of the patent ductus, the decision to intervene should be based on clinical symptoms of congestive heart failure (respiratory compromise caused by excessive pulmonary blood flow, failure to maintain consistent weight gain, compromise of systemic perfusion manifested as renal insufficiency, or necrotizing enterocolitis). Echocardiographic evidence of significant pulmonary volume overload, such as left atrial and left ventricular enlargement, and a chest radiograph showing cardiac enlargement and prominent pulmonary vasculature support the clinical findings.
In older children a medium-sized to large patent ductus may lead to chronic congestive heart failure symptoms, the risk of developing pulmonary hypertension, and ultimately Eisenmenger physiology. In the current era, the incidence of bacterial endarteritis is extremely low, although bacterial endarteritis was responsible for a large portion of the mortality from patent ductus arteriosus (PDA) in the pre-antibiotic era.
Congestive heart failure in the premature infant population is the most common indication for surgical ductal closure. Whereas echocardiography may demonstrate the presence and approximate size of the patent ductus, the decision to intervene should be based on clinical symptoms of congestive heart failure (respiratory compromise caused by excessive pulmonary blood flow, failure to maintain consistent weight gain, compromise of systemic perfusion manifested as renal insufficiency, or necrotizing enterocolitis). Echocardiographic evidence of significant pulmonary volume overload, such as left atrial and left ventricular enlargement, and a chest radiograph showing cardiac enlargement and prominent pulmonary vasculature support the clinical findings. In older children a medium-sized to large patent ductus may lead to chronic congestive heart failure symptoms, the risk of developing pulmonary hypertension, and ultimately Eisenmenger physiology. In the current era, the incidence of bacterial endarteritis is extremely low, although bacterial endarteritis was responsible for a large portion of the mortality from patent ductus arteriosus (PDA) in the pre-antibiotic era.♦ Choices for management
Because ductal patency is related to prostaglandin metabolism, medical closure is possible using the prostaglandin synthetase inhibitors indomethacin or other nonsteroidal anti-inflammatory drugs (NSAIDs). Only premature infants in the first week or two of life predictably respond to NSAID therapy, although the use of NSAIDs may be contraindicated because of renal insufficiency or concern about bleeding complications.
Catheter-based therapy using Gianturco coils or the Amplatzer ductal occluder device has become the standard therapy, with few exceptions, for PDA in children beyond the newborn period.
Video-assisted clip occlusion of the patent ductus has been described in premature infants and in older children and is the preferred strategy in some centers. With this technique, the learning curve is often greater and the incidence of complications or incomplete ductal closure is often higher.
Because ductal patency is related to prostaglandin metabolism, medical closure is possible using the prostaglandin synthetase inhibitors indomethacin or other nonsteroidal anti-inflammatory drugs (NSAIDs). Only premature infants in the first week or two of life predictably respond to NSAID therapy, although the use of NSAIDs may be contraindicated because of renal insufficiency or concern about bleeding complications. Catheter-based therapy using Gianturco coils or the Amplatzer ductal occluder device has become the standard therapy, with few exceptions, for PDA in children beyond the newborn period. Video-assisted clip occlusion of the patent ductus has been described in premature infants and in older children and is the preferred strategy in some centers. With this technique, the learning curve is often greater and the incidence of complications or incomplete ductal closure is often higher.
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