Sinus Venosus Atrial Septal Defect: Repair with an Intra-Superior Vena Cava Baffle

A limited skin incision may be employed but should be planned to allow easy access to structures in the upper mediastinum including the SVC, innominate vein, and upper pulmonary veins. An incision limited over its inferior extent with normal or slightly limited superior extent may be used. SVC = superior vena cava.

Arterial supply to the SA node usually arises from the right coronary artery but occasionally arises from the circumflex coronary artery. Regardless of its origin, the most important consideration is the relationship of the artery to the cavoatrial junction, which generally follows one of three courses (inset). In the majority of cases, the SA node artery follows a precaval course anterior to the junction.¹ Less commonly the artery follows a retrocaval course or bifurcates and encircles the cavoatrial junction. It is important to carefully inspect the region of the cavoatrial junction to determine the course of the SA node artery; the incision required for creation of an intra-SVC baffle may damage an artery that possesses either a retrocaval or an encircling pattern. In these cases, an alternative approach to ASD closure should be considered. Ao = aorta; ASD = atrial septal defect; CX = circumflex coronary artery; LA = left atrium; LAD = left anterior descending coronary artery; MPA = main pulmonary artery; RCA = right coronary artery; SA = sinoatrial; SVC = superior vena cava.

Relationship of the azygous vein and SA node to the anomalous pulmonary veins visualized through the pericardial incision. Ao = aorta; SA = sinoatrial; SVC = superior vena cava.

Cannulation for upper body venous return may be accomplished with placement high in the SVC if this structure is long (inset). Cannulation of the innominate vein as shown provides a convenient alternative for cannula placement without distortion near the site of incision in the SVC. An incision is made in the SVC just anterior to the pulmonary veins with extension into the right atrium as depicted. The atrial incision is substantially superior and posterior to that employed for a typical secundum ASD. Ao = aorta; ASD = atrial septal defect; IVC = inferior vena cava; RA = right atrium; SA = sinoatrial; SVC = superior vena cava.

Intraatrial anatomy visualized through the incision demonstrating the relationship of the right-sided pulmonary veins, SVC orifice, SA node, and ASD. ASD = atrial septal defect; SA = sinoatrial; SVC = superior vena cava.

ASD closure is performed using a patch of untreated autologous pericardium with fine monofilament suture (6-0 or 7-0) to baffle pulmonary venous flow to the left atrium. Fine silk stay sutures are placed at the corners of the patch to facilitate handling; the patch is trimmed to size as it is sewn into the defect.

Increased travel between suture bites on the patch relative to the SVC avoids narrowing of the baffle pathway at the point of entry of the uppermost pulmonary vein branches. SVC = superior vena cava.

It is important to create some degree of redundancy in the patch to produce unobstructed blood flow from the pulmonary veins to the left atrium through the ASD. It is also important to create a baffle that is not overly large to avoid obstruction of SVC return to the right atrium; therefore, the design and execution of patch placement must be precise. ASD = atrial septal defect; SVC = superior vena cava.

Closure of the cavoatrial junction may be performed primarily, with a flap from the right atrial appendage⁴ or with a patch. Reconstruction of the SVC-RA junction with an autologous pericardial patch as shown enlarges the cavoatrial junction and helps to ensure unobstructed SVC blood flow. (Note: completed baffle and external atrial patch in this figure viewed from anterior and to the left of the patient.) ASD = atrial septal defect; IVC = inferior vena cava; RA = right atrium; RV = right ventricle; SVC = superior vena cava; TV = tricuspid valve.

Proper baffle placement and external patch reconstruction of the SVC-RA junction results in unobstructed blood flow from the pulmonary veins into the left atrium through the ASD and preserves unobstructed SVC return. Untreated autologous pericardium is ideal patch material for both the baffle and the atriotomy patch in that it tends to “autoregulate” by shifting in response to fine pressure differences in each pathway, insuring unobstructed SVC and pulmonary venous return. SVC = superior vena cava; ASD = atrial septal defect.