Surgical repair of an aortopulmonary window and subaortic stenosis in an adolescent: case report

Introduction

Aortopulmonary windows (APWs) are communications between the ascending aorta and the pulmonary arteries (PA). APWs form due to improper conotruncal septum development (1). Patients with APWs usually present within the first year of life (2). Congenital subaortic stenosis (SAS) is a left ventricular outflow tract (LVOT) obstruction often caused by an anomalous fibrous membrane. The fibrous membrane can form secondary to LVOT blood flow disturbances (e.g., from an APW or ventricular septal defects) (3). We describe the case of an adolescent patient with a SAS and APW with delayed presentation, which were surgically treated. We present this article in accordance with the CARE reporting checklist (available at https://shc.amegroups.com/article/view/10.21037/shc-24-14/rc).

Case presentation

A 16-year-old female (43 kg) with known SAS presented to establish care upon immigrating to New York with her family from the Dominican Republic. The patient was not on cardiac medications and had no history of invasive cardiac treatments. The patient was asymptomatic and reported participating in physical education classes. On physical exam, the patient appeared well and a grade-5 systolic murmur could be appreciated on auscultation. Transthoracic echocardiogram (TTE) showed SAS (subaortic membrane extending into the LVOT for 7 mm, mean gradient of 79 mmHg, peak gradient of 114 mmHg), a dilated aorta (systolic dimension of 4.5 cm), and moderate aortic regurgitation, secondary to a tethered leaflet (Figure 1). The TTE also found a dilated left ventricle with normal systolic function and severe pulmonary hypertension. Subsequent cardiac catheterization and computerized tomography (CT) revealed a large APW (3.4-by-3.6 cm), elevated pulmonary-vascular-resistance (PVR) of 15 wood units and a pulmonary to systemic blood flow of 1:1. With 100% FiO₂ and 80 parts per million of nitric oxide, the pulmonary to systemic blood flow increased to 3.2:1 and the PVR dropped to 3.2 wood units (Figure 2).

Figure 1 Preoperative transthoracic echocardiogram showing subaortic membrane extending into the left-ventricular-outflow-tract (red arrow) and dilated left ventricle.

Figure 2 Pre-operative imaging. (A) Cardiac catheterization. (B) Three-dimensional computed tomography reconstruction. (C) Computed tomography angiography showing a large aortopulmonary window (red arrow).

In the presence of pulmonary reactivity, the patient underwent surgical APW repair, subaortic membrane resection, and atrial septal defect (ASD) creation. After a median sternotomy, the ascending aorta was found to be dilated with an APW (Figure 3). A 6-mm ringed Gore-Tex graft (W.L. Gore & Associate Inc., Flagstaff, AZ, USA) was anastomosed to the innominate artery and cannulated with the arterial cannula, along with bicaval venous cannulation. Under moderate hypothermia (28 degrees centigrade) the left and right PA were dissected out and snared. A high aortic cross-clamp was placed and the aorta opened longitudinally along the APW. Cardioplegia was administered directly into the coronary ostia and cardiac arrest was obtained (Figure 4).

Figure 3 Intra-operative picture showing the dilated ascending aorta with aortopulmonary window.

Figure 4 Intra-operative picture showing the aortopulmonary window (blue arrow).

The APW was dissected and the pulmonary end of the APW closed with a PhotoFix bovine pericardial patch (Artivion, Kennesaw, GA, USA). The aortic valves were retracted and the subaortic membrane was resected (Figure 5). Scar tissue on the underside of the aortic valve leaflets was carefully removed. Portions of the dilated aortic wall were resected and repaired with a Dacron Hemashield patch (Boston Scientific, Marlborough, MA, USA) (Figure 6). Finally, the right atrium (RA) was opened, and a small 4 mm ASD was created to serve as a “pop-off” for the right side of the heart. The RA was then closed, left heart de-aired, cross-clamp removed, and the patient was warmed and weaned off bypass with inhaled nitric oxide. Modified ultrafiltration was performed, protamine was administered, and venous cannulas were removed.

Figure 5 Resected subaortic membrane.

Figure 6 Completed aortopulmonary window repair with a hemashield graft used to reconstruct the aorta (blue arrow).

The aortic cross clamp time was 83 minutes and bypass time was 183 minutes. Post-operative transesophageal echocardiogram showed mild aortic insufficiency, no left ventricle outflow tract obstruction and bidirectional shunting at the ASD level.

Her post-operative course was complicated by bleeding requiring a mediastinal washout on post-operative day (POD) 2. The patient was extubated on POD-3 and transitioned from inhaled nitric oxide to sildenafil on POD-4. She was discharged home on POD-6. POD-15 TTE showed significantly reduced aortic and pulmonary valve pressure gradients (Table 1). At 8-month follow-up, she was doing well and able to exercise. TTE and cardiac catheterization showed a closed APW, trivial aortic regurgitation, normal left ventricular function, and PVR of 6 wood units (down from 15), with a mean PA pressure of 22 mmHg. The patient is maintained on amlodipine 5 mg daily for arterial hypertension and sildenafil 20 mg three times a day for pulmonary hypertension. All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient and the patient’s parents for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

APWs are rare, accounting for 0.1–0.2% of congenital heart defects (1). Patients generally present at a young age with heart failure (2). Unrepaired APWs lead to pulmonary arterial disease and Eisenmenger’s syndrome. Three United States (US) studies of patients with APW found median ages of 19, 22, and 35 days. The oldest patient across the three studies was a 7-year-old (N=107) (1,2,4). The average age of presentation is older in lower-income countries. A study from India reported a median age of 7 months (5). Patients with APWs rarely have subaortic obstruction. Only 6% of the patients in the India study and none of the patients in the three US studies had SAS lesions (1,2,4,5). We present a case of a 16-year-old patient with an APW and SAS that recently immigrated to New York from a lower-income country with severe pulmonary hypertension but with pulmonary reactivity.

Early surgical repair of APWs is recommended to prevent the progression of pulmonary vascular disease (2,5). US outcomes for APW repair are excellent. A US study from 1994–2013 (N=40) reported a 0% mortality (1). It is unclear why some patients with large shunts have delayed development of pulmonary arterial disease. In the presence of congenital heart disease with left-to-right shunts and pulmonary hypertension, surgical correction has been deemed safe when PVR is below 6 wood units. An individualized approach is required when the PVR is between 6–8 wood units (6). In the absence of pulmonary vasoreactivity or in situations with a high fixed PVR, management becomes more challenging and includes repairing the APWs with concomitant bilateral lung transplantation or awaiting the development of Eisenmenger’s syndrome and then proceeding with a combined heart-lung transplantation. It is likely that if left untreated, our patient would have developed severe fixed pulmonary arterial disease and would require bilateral lung transplantation with concomitant APW repair.

Leaving a small atrial-level communication allows for a smoother post-operative course, as it acts as a “pop-off” for the right side of the heart. The right ventricle is prone to failure in the post-operative period with high PVR. Leaving a small ASD allows the preload to the left side to be maintained enabling a smoother post-operative ICU course. The fact that the child had bidirectional flow at the atrial level in the post-operative echo validates this decision. An aortic approach aligns with literature findings that pulmonary arteriotomies increase the risk of reintervention (2). Given the large size of the APW (3.4-by-3.6 cm), patches were used to close the PA and aorta, as primary closure would have resulted in stenosis and distortion of the great vessels. With a dilated aorta, narrow LVOT and aortic valve regurgitation, there is a possibility of this child requiring future intervention, hence, two separate patches were used to repair the APW instead of a single patch.

Conclusions

This case describes a rare, delayed presentation of a large left-to-right shunt with severe pulmonary hypertension and preserved pulmonary reactivity, making primary surgical repair possible. Although such presentations are rare in developed countries, congenital heart surgeons must be aware of such late presentations and the various management options.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://shc.amegroups.com/article/view/10.21037/shc-24-14/rc

Peer Review File: Available at https://shc.amegroups.com/article/view/10.21037/shc-24-14/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://shc.amegroups.com/article/view/10.21037/shc-24-14/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patient and the patient’s parents for the publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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