AP window defects present during the neonatal period or in early infancy. The typical signs and symptoms of an AP window are that of pulmonary over-circulation occurring as the pulmonary vascular resistance falls over the first few weeks of life. The symptoms would include diaphoresis (especially with feeds), tachypnea, tachycardia, poor weight gain, and increased respiratory symptoms with viral infections. The precordium is often hyperdynamic, and a mitral valve rumble can be appreciated. The pulses are often bounding as the systemic diastolic blood pressure is decreased secondary to aortic flow reversal in diastole. Rarely, there is a continuous murmur noted as the connection between the aorta and the pulmonary artery is usually large. AP window can be associated with other types of congenital heart defects.  In tetralogy of Fallot, a pulmonary ejection murmur and pulmonary valve click can be noted. When the AP window occurs with an interrupted aortic arch, the neonate can present with shock as the ductus arteriosus constricts. Occasionally the AP window can be restrictive and present with less significant symptoms of over circulation. In this scenario, a continuous heart murmur could be noted.  Rarely, an AP window diagnosis is not made until late in infancy or during childhood. This could present with features of Eisenmenger syndrome, including cyanosis and clubbing.[4] 

In children with an AP window, a chest x-ray will show cardiomegaly and increased pulmonary vascular markings. Electrocardiogram will demonstrate tachycardia and increased right and left-sided voltages. The diagnosis of an AP window is made by echocardiography after suspicion of a large left to right shunt. Because the connection is usually without significant restriction, color Doppler echocardiography will not detect a high-velocity jet (communication). When the suspicion is high, the 2D images are usually sufficient to measure the AP window communication. If echocardiogram imaging is insufficient, a CT scan can potentially delineate the AP connection. Echocardiography should completely evaluate the remaining cardiac structures, including an evaluation of other cardiac diseases such as tetralogy of Fallot and interruption of the aortic arch. Unless the diagnosis is made late or not able to be made with less invasive means, cardiac catheterization adds little to the diagnostic management. When the diagnosis is made after a few months of life, catheterization could be utilized to evaluate the pulmonary vascular resistance as Eisenmenger syndrome can develop. If there is pulmonary vascular disease, reactivity testing should be performed during catheterization.[2][5]

In general, the treatment for an AP window is surgery, although catheterization device closure has been described in case reports. Anticongestive medications such as diuretics (e.g., furosemide and chlorothiazide) and digoxin can provide temporary symptomatic improvement but should not significantly alter the course of the disease. Afterload reduction can be considered with ACE inhibition. Medical therapy should be approached with caution, as there can be abnormal renal perfusion. Surgery should be considered at the time of diagnosis as there will likely be little growth with this physiology, and there is a risk of developing irreversible pulmonary hypertension over time. Furthermore, the AP window does not restrict or get hemodynamically less significant over time. In general, surgery involves separation of the great arteries with either suture division or patch closure of the aorta and pulmonary artery, and this occurs with low surgical mortality. Catheterization can be considered when a defect is small enough to allow for device closure without causing stenosis of the great arteries or interference with the semilunar valves. If other cardiac defects are present, repair of the other defects should occur at the same operation. Postoperative aorta, rarely, and pulmonary artery stenosis in the main and branch pulmonary arteries, more commonly, can occur. If this stenosis is hemodynamically important, future cardiac catheterization with balloon angioplasty or stent implantation can be employed.[6][7]

• Coronary artery anomalies

• Patent ductus arteriosus

• Truncus arteriosus

• Ventricular septal defect

The diagnosis of an AP window is usually made by echocardiography. It cannot be emphasized enough that a high clinical suspicion of a large left to right shunt and bounding pulses should prompt an echocardiogram with a focus to include an evaluation for an AP window. Genetic testing for DiGeorge syndrome should be performed. Late repair of AP window is a risk for persistence of substantial pulmonary hypertension, and there should be a low threshold for postoperative cardiac catheterization for evaluating the pulmonary vascular resistance. In general, early repair of an AP window results in an excellent long-term prognosis. 

The diagnosis and management of AP window require an interprofessional team that includes a pediatrician, cardiologist, cardiac surgeon, geneticist, intensivist, and radiologist. The disorder is managed with surgery, but the key that the child does not have any other associated congenital heart defects. Once the surgery is performed, the infant is usually monitored by cardiac or critical care nurses. If this is an isolated defect, the outcomes are good. Pharmacists should review the dosing of medications and provide teaching to families of patients. Specialty care nurses help coordinate care and update the team on changes in patient status. [8]For children with multiple other defects, the outlook is guarded. A geneticist should be consulted if the patient has DiGeorge syndrome.