Medical Care
Medical palliation of aortopulmonary septal defect (APSD) may be performed for several days to weeks to allow elective surgical scheduling. Because an aortopulmonary window does not spontaneously close, surgical repair is necessary to prevent the development of pulmonary vascular obstructive disease (PVOD). Meanwhile, digoxin and diuretics may provide some symptomatic benefit before surgical repair.
Preoperative inpatient care of patients with APSD is directed at managing congestive heart failure (CHF) and completing the diagnostic evaluation in anticipation of surgery. In rare instances (eg, active sepsis), postponing surgery may be desired. In this situation, provide medical therapy (ie, digoxin, inotropic drugs, diuretics) for a brief time in anticipation of surgery.
The effect of vasodilator agents (eg, angiotensin-converting enzyme [ACE] inhibitors, phosphodiesterase inhibitors, nitrates) is uncertain because these drugs all affect pulmonary resistance in addition to systemic resistance.
Intubation and positive pressure ventilation with permissive hypercarbia and limiting inspired oxygen concentration to 21% may help limit pulmonary blood flow in infants with torrential pulmonary flow requiring medical palliation. Consider using lower inspired oxygen concentrations (15-19%) to elevate pulmonary vascular resistance (PVR) in more extreme cases. Sedation and muscle relaxants may prove necessary to limit spontaneous ventilation.
Previous common practice consisted of medically treating a small infant with congestive heart failure (CHF) with the expectation that he or she would grow and become a "better" surgical candidate. This approach is seldom successful because caloric demands of an infant with CHF typically exceed the amount of nutrition delivered by even the most aggressive means.
Case reports and small case series report closure of small aortopulmonary septal defects in the cardiac catheterization (CC) lab. The Rashkind double umbrella device, [24] the Amplatzer duct occluder, [25] the Amplatzer septal occluder, muscular ventricular septal defect (VSD) occluder, and perimembranous VSD occluder have all been used to close small (type I) defects. [26] The limiting factor to catheter closure of these defects is the anatomy. Only relatively small defects with circumferential tissue rims are amenable to transcatheter device closure, limiting this therapeutic option to a relatively small number of patients. See the image below.
Angiogram of a small-to-moderate aortopulmonary septal defect in a 4 year-old child. Complete occlusion of the aortopulmonary septal defect with an Amplatzer Duct Occluder. Ao = Ascending aorta; PA = Pulmonary artery.
Important considerations
The following are essential issues to keep in mind:
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Early recognition of serious heart disease with associated pulmonary hypertension and high pulmonary vascular resistance (PVR) is important, as irreversible pulmonary vascular obstructive disease (PVOD) may develop (one of the most feared scenarios in pediatrics and pediatric cardiology)
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Realization that heart diseases, including large ventricular septal defects (VSDs), patent ductus arteriosus (PDA), and aortopulmonary septal defect (APSD), may present in this fashion (When PVR does not fall after birth, children may not have symptoms of congestive heart failure [CHF] and may feed and grow normally with a paucity of cardiac findings.)
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Recognition of loud and single second heart sounds that indicate the existence of pulmonary hypertension, thereby warranting further workup
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Ensuring clearly discernment of a splitting of the second heart sound with respiration on each cardiac examination on every child, and referral of the patient to a pediatric cardiologist for evaluation if the heart sounds are suspicious
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Identification of aortopulmonary septal defect as the cause of a large left-to-right shunt causing CHF
Consultations
Consult a pediatric cardiologist for diagnosis. Then, refer the patient to a competent cardiovascular surgical team experienced in the repair of congenital heart disease.
Transfer
Transport patients, if needed, to a facility with the appropriate pediatric and/or pediatric cardiac surgical services.
Diet and activity
A high-calorie formula may be needed for infants with CHF perioperatively. Generally, activity is not restricted in patients with this defect, except in those with Eisenmenger syndrome.
Surgical Care
Various surgical techniques allow correction of this lesion. [7, 27, 28, 29, 30, 31]
Most centers use techniques that involve cardiopulmonary bypass.
The aorta and pulmonary artery may be divided, and the defects in the walls may be closed primarily or with patch material. Alternatively, the aorta or pulmonary artery may be opened and the defect patched using autologous, homologous, xenograft, or synthetic material. Two larger case series have reported that transaortic repair is associated with a more favorable outcome and has less risk of causing late pulmonary artery stenosis.
Other defects may be addressed at the same operation; however, in rare instances, a staged approach may be undertaken.
Specific techniques for unique anatomy must be individualized.
A retrospective review (2002-2011) reported good outcomes associated with the use of a single pericardial patch technique for primary repair of an aortopulmonary window with an interrupted aortic arch. [32] In 6 of 11 patients, the interrupted aortic arch was type A; the remaining 5 patients had type B. Median age at the time of surgery was 11 days, with a mean weight of 2.6 kg; mean follow-up was 6 ± 3 years. There were no early and late deaths nor reoperations. There was one case of postoperative stroke without late sequelae. All patients at last follow-up visit had no recurrent aortic arch obstruction or pulmonary artery branch stenosis. [32]
Postoperatively, evidence of a good surgical repair should be confirmed.
Postoperative care should focus on managing pulmonary hypertension, evaluating for residual defects, and aiding convalescence in anticipation of discharge. Residual anatomic problems may be anticipated from preoperative anatomy and include, but not be limited to, pulmonary artery stenosis or distortion, residual left-to-right shunt at the aortopulmonary septal defect site, and ascending aortic obstruction or distortion. Postoperative data should be consistent with a complete repair.
If a pulmonary artery catheter was left in place, it should indicate low pulmonary artery pressure and pulmonary artery oxygen saturation less than 80%.
An elevated pulmonary artery pressure may indicate pulmonary artery vasoreactivity or a persistent left-to-right shunt. Pulmonary artery saturation and left atrial pressure should differentiate the two conditions. If concerns persist, transthoracic or transesophageal echocardiography may be informative. Rarely, cardiac catheterization may be needed to detect residual abnormalities. A case report indicated successful transcatheter closure of a late-onset residual shunt following repair of an aortopulmonary septal defect with the use of a muscular ventricular septal occlude. [33]
Postoperative pulmonary hypertension
Apart from anatomic concerns, an older infant or child with elevated preoperative PVR is at risk for postoperative pulmonary hypertension that may require aggressive management.
Inhaled nitric oxide may be useful in the management of postoperative pulmonary hypertension by acting as a selective pulmonary arteriolar vasodilator.
Other drugs such as sildenafil or calcium channel blockers may provide ongoing pulmonary vasodilatation.
Follow-up care
Provide follow-up care within 1-2 weeks following discharge.
Patients are commonly discharged on diuretics, but if a good repair is achieved, most patients can be weaned from cardiac medications soon after discharge.
Even in the absence of clinically evident problems, at least one postoperative echocardiogram should be performed during follow-up to evaluate for potentially silent problems.
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Echocardiographic image of a 1-month-old infant with a large isolated aortopulmonary septal defect (APSD). The image is a parasternal short-axis view just below the pulmonary artery bifurcation. Aorta at this level is to the right and in the same anterior-posterior plane as the main pulmonary artery (MPA). Right pulmonary artery is seen posterior to the aorta at this level, but the origin of the pulmonary arteries is not visible; it is more superior than this axial image. Normally, a complete wall should be visible for both aorta and pulmonary artery. This image shows the absence of that wall, resulting in the large defect between aorta and pulmonary artery.
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Angiogram of a small-to-moderate aortopulmonary septal defect in a 4 year-old child. Complete occlusion of the aortopulmonary septal defect with an Amplatzer Duct Occluder. Ao = Ascending aorta; PA = Pulmonary artery.
