Aortic Arch Homograft Reconstruction of Nonconfluent Pulmonary Arteries During Extracardiac Fontan

Introduction

Reconstruction of nonconfluent pulmonary arteries during Fontan completion is a challenging technical issue. In this report, we describe the use of an aortic homograft, including the aortic arch, to complete a Fontan and reconstruct the pulmonary artery confluence in a child with discontinuous pulmonary arteries and bilateral superior vena cavae after bilateral unidirectional cavopulmonary shunt palliation.

Case

A three-year-old boy was referred for Fontan completion. His cardiac diagnosis was left atrial isomerism with an unbalanced atrioventricular septal defect, pulmonary atresia, bilateral superior vena cavae, and nonconfluent pulmonary arteries. He had previously undergone bilateral Blalock-Taussig shunts in the newborn period followed by bilateral unidirectional superior cavopulmonary shunts at seven months of age.

Preoperative cardiac catheterization demonstrated well-developed bilateral pulmonary artery branches with a 13-mm gap between the hilar branches (Figure 1). Both superior cavopulmonary anastomoses were widely patent with a pressure of 9 mm Hg in the right and 7 mm Hg in the left. The estimated ratio of pulmonary to systemic flow was 0.52. The ventricular function was well preserved with minimal atrioventricular valve regurgitation.

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Figure 1.

Preoperative angiography. A, Right superior vena cava to the right pulmonary artery. B, Left superior vena cava to the left pulmonary artery.

The technical challenge of the Fontan operation was reconstruction of the central pulmonary arteries. After reopening the sternum and completion of the dissection, we found the right upper and middle pulmonary veins were returning to the right atrium anteriorly; careful conduit placement was necessary to prevent compression. Cardiopulmonary bypass was established with ascending aortic, right superior vena cava, and inferior vena cava cannulation. The left superior vena cava was transiently clamped during the Fontan anastomosis. The right atrium was detached from the inferior vena cava and oversewn. A 19-mm aortic homograft was trimmed at the level of the sinutubular junction and anastomosed to the inferior vena cava. The curvature of the aortic homograft was optimal for bridging the gap between the right and left pulmonary arteries. The first orifice of the aortic homograft (donor innominate artery) was transected and anastomosed to the left aspect of the blind end of the right pulmonary artery (Figure 2). The second and third head vessels were stapled and the distal arch was trimmed and anastomosed to the right aspect of the blind end of the left pulmonary artery. The procedure was completed with the heart beating. Hemodynamics were excellent after termination of bypass with a pulmonary artery pressure of 12 mm Hg; no fenestration was placed. The patient was extubated in the operating theater and discharged uneventfully on postoperative day 6.

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Figure 2.

Fontan reconstruction of discontinuous pulmonary arteries with an aortic arch homograft. The second and third head vessels were stapled.

Comment

Various techniques have been proposed to reconstruct discontinuous pulmonary arteries during single ventricle palliative procedures. ^{1 -3} Autologous pericardial patches or rolls are susceptible to aortic compression, necessitating repeat intervention. Although Gore-Tex (W. L. Gore & Associates, Flagstaff, Arizona) ² grafts can be utilized for this application, their geometry is relatively fixed. ⁴ In our case, an aortic arch homograft was optimal for reconstruction. The greater curvature of the aortic homograft appropriately sat next to the right atrium, preventing obstruction of the right pulmonary veins, and the homograft aortic arch was well configured to reconstruct the central pulmonary artery confluence. The elasticity of the aortic homograft avoided anterior compression by the native ascending aorta. Minimizing energy loss with a geometrically satisfactory conduit is crucial to an optimal long-term Fontan outcome. ⁵ Mavroudis et al reported the use of an aortic homograft for a total cavopulmonary connection conversion. ⁶ The aortic homograft was used to establish pulmonary artery continuity in a patient with an established classic right Glenn/right atrium-to-left pulmonary artery Fontan. Kiraly et al and Monro et al previously summarized the fate of aortic homografts in the Fontan circulation. ^7,8 In their report, of 27 consecutive cases, freedom from reoperation was 100%, 88%, and 54% at 5, 10, and 15 years, respectively. Despite heavy calcification of the conduits, except for one patient, no hemodynamically significant gradients were found. Preformed antibodies induced by homograft implantation may impact future transplant candidacy. Close follow-up is necessary for patients who have homograft tissue implanted during Fontan completion. Although caution should be exercised, the three-dimensional configuration of the aortic homograft was well suited to the anatomical challenges of this case. In addition, the user-friendly tissue properties of homograft facilitate hemostasis, contributing to the ease of intraoperative extubation, which optimizes Fontan hemodynamics.