Surgical Ligation of Isolated Type I Aortopulmonary Window Without Cardiopulmonary Bypass is a Safe and Cost-Effective Surgical Technique

Introduction

Aortopulmonary window (APW) is a rare congenital anomaly of the heart, comprising 0.1% to 0.2% of all congenital heart defects, ¹ and consists of a direct communication between the pulmonary artery (PA) and the aorta. APWs are often associated with other congenital heart defects (up to 90%) which include coronary anomalies (10%). ² Different classifications of the APW exist in the literature, the most commonly used being that of the Society of Thoracic Surgeons (STS) which is a modified version of the classification by Mori et al. ³

Type I APW is a proximal defect located just superior to the sinuses of Valsalva and the sinotubular junction, with an inferior rim that separates the defect from the semilunar valves. Type II APW is a distal defect located in the uppermost portion of the ascending aorta and overlying the right PA (RPA). Type III APW is defined as a total defect that involves the majority of the ascending aorta. Finally, Intermediate defects are defined by having adequate superior and inferior rims—this type is considered the most suitable for potential device closure.

Early closure of APW has shown excellent survival rates, and surgical repair with cardiopulmonary bypass (CPB) is currently considered the standard of surgical care. Research has shown that transcatheter closure of APW has also shown success, yet the data are limited.^4–6 There is very little available data regarding direct surgical ligation of APW without CPB—successful ligations have been reported by Gross, and Scott and Sabiston.^7,8 The hypothesis of this study was that direct surgical ligation of APW is safe and may be equivalent to the standard open-heart repair. Patients with isolated type I APW were selected to undergo direct surgical ligation.

Method

Institutional Review Board approval was obtained for the study which lasted from December 2020 to January 2024. Twelve patients with a simple or isolated type I APW were selected to undergo direct surgical ligation by a single surgeon at Children's Hospital, Lahore, Pakistan.

During the same time period, nine patients underwent an operation for AP window repair undergoing repair on CPB. Five of these patients had an associated ventricular septal defect (VSD), one had a coarctation of the aorta and one had an interrupted arch with a VSD in addition to the AP window. One patient required a PA patch plasty and one patient had an aortic origin of the RPA.

The median age at the time of repair was 8.5 months (range, 3 to 36 months) and mean weight was 5.5 kg (range, 3.5 to 10 kg). All patients came with delayed presentations of failure to thrive and recurrent respiratory infections. Diagnosis of APW was made on two-dimensional transthoracic echocardiogram, and classification of APW was determined using the STS nomenclature.

The mean size of the APW was 10.8 mm (range, 7-18 mm). One patient underwent preoperative cardiac catheterization to determine operability, and despite having severe pulmonary hypertension was still determined to be a potentially salvageable surgical candidate. Representative catheterization images of that patient are shown below (Figures 1 and 2). The arrow in Figure 2 points to the APW.

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Figure 1.

Cardiac catheterization with contrast injection in ascending aorta (pigtail catheter) demonstrating a large aortopulmonary window.

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Figure 2.

Cardiac catheterization with contrast injection in ascending aorta (pigtail catheter) demonstrating a large aortopulmonary window( arrow).

A sternotomy approach was used in all cases, and CPB was on stand-by.

The final decision to proceed with ligation was made after detailed intraoperative inspection. The first assessment was of the origin of the left main coronary artery and its distance from the lower end of the aortic end of the window. The aorta is retracted to the left, and the posterior aspect of the window and the aorta is examined. The origin of the left main coronary artery must be a few millimeters away from the lower end of the aortic origin of the window thereby ensuring that the shape of the coronary ostia is maintained with AP window ligation. The origin of the right PA was examined and confirmed not to be originating from the back wall of the window and would not be compromised on AP window ligation. A meticulous and careful dissection was done along the lower border of the AP window just above the semilunar valves, between the two great vessels from anterior to posterior and then a right angle clamp was passed through this space and two 4-0 prolene suture ligatures were passed around the window. The 4-0 prolene suture on the pulmonary end of the window was double looped.

Initially, the APW was snared at the aortic end with a Rummel tourniquet, and hemodynamic status was assessed. Blood pressure was lowered pharmacologically to a systolic blood pressure of less than 60 mm Hg, and ligation was done starting at the aortic end first. An intraoperative epicardial echocardiogram was done to determine that the window had been completely and successfully ligated with no compromise of the branch pulmonary arteries, the semilunar valves, or coronary arteries. Patients underwent repeat echocardiogram prior to discharge and were then followed with serial transthoracic echocardiograms.

Results

Intraoperative epicardial echocardiography was performed to assess for any residual defect, aortic or pulmonary insufficiency, or any branch PA stenosis. All patients underwent successful ligation of the APW. On follow-up ranging from 6 months to 3 years there was no mortality. No patients had evidence of residual aortopulmonary defect, aortic or pulmonary insufficiency, branch PA stenosis or distortion, or coronary compromise.

A significant cost–benefit of approximately $2,000 per patient was seen with this surgical management—a major concern in a low- to middle-income country such as Pakistan.

Discussion

An APW is a rare congenital anomaly that accounts for less than 0.5% of all congenital heart defects. ¹ It results from the incomplete separation of the aorta and PA during embryonic development and if left untreated, leads to excessive blood flow to the lungs, eventually causing pulmonary hypertension and congestive heart failure. ⁹ Aortopulmonary window has been classified into three types: type I being a proximal defect that is just above the sinotubular junction, type II being a distal defect before the aortic branches and type III being a large complete defect from proximal to distal. ¹⁰ In our case series, all patients had a type I defect as confirmed on preoperative echocardiogram and intraoperative examination.

Historically, the first record of successful management of an APW was reported by Gross in 1952. ⁷ Due to previously reported high rates of mortality and residual shunts, the procedure has now been largely replaced by patch closure using CPB. t. ¹¹ With increased refinement of catheter-based interventions selected patients with APW are now being offered this alternative.^4,5,6,12 Device closure is a relatively newer technique with the potential for future advances. However, current evidence does not demonstrate its superiority over surgical repair.

In our practice, the decision to proceed with ligation is made after a detailed assessment of the preoperative echocardiogram to demonstrate a Type I window and careful intraoperative assessment of the APW. This is done to ensure that there is adequate distance between the APW and the coronary arteries along with minimal risk of PA distortion. Despite this, the CPB circuit is on standby, while the surgeon dissects the APW and completes the ligation. We have so far performed this procedure successfully in 12 patients with no immediate or long-term complications. Our results align with the trend toward early surgical intervention for APW defects, as reported by Backer and Mavroudis. ¹¹ However, our approach differs in that we opted for ligation without CPB, deliberately avoiding its associated risks and added costs. Our outcomes, with no mortality and no residual defects, are comparable to those achieved with transaortic patch closure using CPB.¹³ This suggests that ligation without CPB can be a viable alternative for select patients, offering a cost-effective and risk-reducing strategy for APW repair. Ligation of APW in extremely low weight neonates or in babies with comorbidities, avoiding the use of CPB, has also been successfully reported.^14,15 Our findings contribute to the ongoing discussion on optimal management strategies for APW defects, highlighting the importance of individualized approaches based on patient needs and resource considerations.

Notably, our series had no instances of residual or recurrent APW defects observed during follow-up, which ranged from discharge to 3 years postoperatively. This finding is comparable to the results reported by Yakut et al, who also achieved a low recurrence rate with their approach. ¹⁶ The absence of recurrence in our series may be attributed to the careful patient selection and meticulous surgical technique of dissection and ligation of the APW. Our results suggest that ligation without CPB can be an effective and durable solution for selected type I APW repair, with a low risk of recurrence, death, or PA stenosis.

Conclusion

On short-term follow-up, direct surgical ligation of type I APW appears to be a safe and cost-effective alternative to standard open-heart surgical repair of APW on CPB. The technique has been reported successfully in selected circumstances; however, a larger sample with continued long-term follow-up will be needed to better determine the effectiveness of this alternative procedure. Specifically, in low-middle income countries, this technique offers the unique advantage of being significantly more cost effective than standard repair on CPB.