Aortopulmonary Window Surgery Treatment & Management
- Author: Mary C Mancini, MD, PhD, MMM; Chief Editor: Jonah Odim, MD, PhD, MBA more...
Medical therapy is focused on preoperative stabilization. Surgical correction is the only effective treatment for aortopulmonary window (APW).
Intravenous prostaglandins (eg, alprostadil) may be required to maintain patency of the ductus arteriosus in patients with interrupted aortic arch in order to provide blood flow to the lower half of the body. The associated pulmonary arterial vasodilatation may further exacerbate the increased pulmonary blood flow.
Digoxin and furosemide are frequently administered to treat the heart failure and volume overload associated with this lesion.
Inotropic agents (eg, dopamine, dobutamine) may also be required for infants with significant heart failure and low cardiac output associated with myocardial dysfunction.
Surgery is the treatment for aortopulmonary window. After initial stabilization and correction of acidosis, surgery should be undertaken as soon as possible.
Surgery is performed with the use of cardiopulmonary bypass. An incision can be made into the anterior aspect of the aorta, the main pulmonary artery, or the aortopulmonary window itself.
Associated lesions are usually repaired during the same surgery. More complex repairs and myocardial protection strategies are required in patients with associated lesions, increasing the morbidity and mortality associated with the operation.
Preoperative care is centered on correction of acidosis and stabilization of the child. Congestive heart failure symptoms are treated with digoxin, Lasix, and inotropes as necessary.
Elective intubation can also be performed and pulmonary blood flow regulated by altering the inspired fractions of oxygen and carbon dioxide.
Echocardiography is performed to define the anatomy and assess ventricular function. In complex lesions or in instances in which the coronary arteries cannot be clearly seen, cardiac catheterization may be required.
Patients presenting when older than 6 months need cardiac catheterization to rule out irreversible pulmonary hypertension.
Exposure is obtained through a median sternotomy. The aortopulmonary window should be directly visible. The aorta is cannulated as distally as possible. A single right atrial cannula or, if an atrial septal defect (ASD) or ventricular septal defect (VSD) is present, separate caval cannulae must be used.
Cardiopulmonary bypass is instituted, and the procedure is performed at moderate hypothermia. One of the pulmonary arteries can be snared early in the operation if pulmonary overcirculation remains a problem or has been exacerbated by the induction of general anesthesia. Deep hypothermic circulatory arrest (DHCA) may be necessary if the lesion is complex or extends distally into the arch of the aorta. This also applies to patients who require repair of an interrupted aortic arch.
The right and left pulmonary arteries should be snared before the administration of cardioplegia. The snares should be tightened to ensure good coronary flow and prevent runoff of cardioplegia into the pulmonary circulation. Consideration can be given to retrograde cardioplegia but is not mandatory. If DHCA is used for complex repairs, retrograde cardioplegia should not be necessary.
The defect is entered from the anterior aspect of the aorta, the main pulmonary artery, or the aortopulmonary window itself. The origins of the coronary arteries and branch pulmonary arteries are identified. A running nonabsorbable suture is then used to affix a patch of glutaraldehyde-treated pericardium or synthetic material to the posterior aspect of the defect. The remainder of the patch is then sewn to the superior and inferior aspects of the defects, with attention to the coronary arteries and branch pulmonary artery orifices. The anterior aspect of the patch is incorporated into the closure of the incision.
Associated anomalies require repair using the protocols for those lesions. Specifically, the interrupted aortic arch is reconstructed before closure of the aortopulmonary window. Because of the presence of the aortopulmonary window, a single aortic cannula can be used. The patient is then cooled to 18°C (64.4°F). The head vessels and branch pulmonary arteries are snared, and cardioplegia is delivered into the coronary arteries. The descending aorta can then be anastomosed to a separate aortotomy above the aortopulmonary window or incorporated into an extension of the incision used to open the aortopulmonary window. The aortopulmonary window is then closed using patch material. The frequent abnormal right pulmonary artery must be baffled to be continuous with the main pulmonary artery.
The patient is then warmed and weaned from cardiopulmonary bypass. The integrity of the repair is examined by means of transesophageal echocardiography. Protamine is administered to reverse the heparin, and the patient is decannulated and the incision closed.
Inotropic support with milrinone, epinephrine, dopamine, or other agents can be anticipated in the initial postoperative period. A patient can usually be weaned off these over the next several hours and days, depending on his or her preoperative condition, length of time on cardiopulmonary bypass, and duration of hypothermic circulatory arrest.
Older patients may require treatment of postoperative pulmonary hypertension and pulmonary hypertensive crises. High levels of inspired oxygen remain one of the most effective pulmonary vasodilators. Deep sedation and paralysis are also effective in preventing hypertensive crises. If paralysis is not used, additional sedation should be used for endotracheal suctioning and other procedures. Inhaled nitric oxide may be effective for the treatment of pulmonary hypertension in intubated patients.
Patients may also require continued digitalis and Lasix, which may be discontinued in outpatient therapy.
Patients require follow-up with their cardiac surgeon initially and a pediatric cardiologist indefinitely. The surgical repair can be monitored by means of serial echocardiography. Further operative intervention may be required for the development of pulmonary artery stenosis. Some element of heart failure may persist after surgery and require continued medical therapy.
Pulmonary hypertensive crises may occur in the postoperative period. Patients at high risk should be sedated overnight, and paralysis should be considered. Acidosis should be avoided, and the pCO2 should be maintained at 30-35 mm Hg. Hypoxia should be avoided. Deep sedation should be confirmed before endotracheal suctioning. Finally, inhaled nitric oxide should be instituted for pulmonary artery pressures not managed by the above measures. Milrinone may also be used to lower pulmonary artery pressures and provide inotropic support. These measures can often be discontinued the next day.
Long-term follow-up is done with echocardiography. Recurrent coarctation and development of branch pulmonary artery stenosis are long-term risks.
Outcome and Prognosis
Outcomes continue to improve with better management during the perioperative period. An example of this can be seen in Backer and Mavroudis' description of their 40-year experience at Northwestern University. Early in their experience, repair primarily consisted of aortopulmonary window (APW) division and resulted in a 37% mortality rate (6 of 16 patients). However, no deaths occurred in their most recent series of 6 patients in which cardiopulmonary bypass and transaortic patch closure were used. Most series consistently report a mortality rate less than 10%. The mortality rate for simple aortopulmonary window without other associated anomalies should be near 0%.
The prognosis of aortopulmonary window is excellent if repaired in infancy and preferably before the onset of significant pulmonary hypertension. In Backer and Mavroudis' series noted above, the average pulmonary vascular resistance was elevated at 5.4 U/m2, but only one patient died from complications of pulmonary hypertension.
Future and Controversies
Little change has occurred in the diagnosis and management of aortopulmonary window (APW). Its frequent complexity and proximity to the aortic and pulmonary valves make catheter-based interventions unlikely in the future, although a catheter-based device has been used to close a residual defect following surgical repair. In addition, angioplasty with or without stenting may be effective in postoperative pulmonary artery stenoses.
Imaging modalities may advance and come to include MRI to better define the more complex lesions and avoid cardiac catheterization when the anatomy is unclear.
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