Volume 11, Issue 1 , Pages 33-44, Spring 2006
Sinus Venosus Atrial Septal Defect: Repair with an Intra-Superior Vena Cava Baffle
Article Outline
Although sinus venosus atrial septal defect (ASD) is a relatively simple congenital cardiac lesion, repair should be performed carefully to avoid obstruction of blood flow from the superior vena cava (SVC), associated anomalous right-sided pulmonary veins, or both of these structures. Sinus venosus ASDs are located outside of the oval fossa at the point of entry of the SVC into the right atrium usually in close proximity to the pulmonary veins draining the right upper lung.1 Often the right superior and occasionally middle pulmonary veins appear to enter the right atrium close to the SVC orifice; not uncommonly, these veins enter directly into the SVC. A true secundum ASD or patent foramen ovale may also be present. Sinus venosus ASDs without anomalous pulmonary venous drainage may be managed by simple patch closure of the ASD with preservation of SVC blood flow into the right atrium. In the presence of anomalous drainage of the pulmonary veins at or above the SVC–right atrial junction, a number of reconstructive options may be employed for management of these defects.
When the entrance of the pulmonary veins is high in the right atrium with an adequate rim of tissue at the orifice of the SVC, simple patch closure of the defect can be performed, taking care to orient the patch to allow unobstructed pulmonary venous return into the left atrium while maintaining unobstructed SVC return to the right atrium. The Warden procedure may be successfully employed in cases where the anomalous pulmonary venous drainage is high into the SVC.2, 3 In this procedure, the SVC is transected above the entry point of the pulmonary veins and the cardiac end of the SVC is oversewn. The SVC orifice is then baffled to the left atrium through the ASD; in this way the SVC orifice effectively serves as a large common orifice for the anomalous pulmonary veins. The reconstruction is completed by anastomosing the distal end of the SVC to the right atrial appendage to reestablish SVC drainage.
For sinus venosus ASDs accompanied by anomalous pulmonary venous drainage that enters the SVC just superior to the cavoatrial junction or slightly higher, a pulmonary venous baffle to the ASD can be constructed via an incision in the SVC–right atrial junction with patch enlargement of the junction. This technique requires precise technical execution to produce unobstructed SVC and pulmonary venous return. In addition, it is important to avoid damage to the coronary arterial blood supply of the sinoatrial (SA) node at the time of surgery, which may demonstrate substantial anatomic variability from patient to patient.
Operative Technique
Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10
Figure 1.
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.
Figure 2.
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.
Figure 3.
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.
Figure 4.
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.
Figure 5.
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.
Figure 6.
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.
Figure 7.
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.
Figure 8.
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.
Figure 9.
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.
Figure 10.
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.
Conclusions
As expected, results with most approaches to surgical repair of sinus venosus ASD have been uniformly good.2, 4, 5, 6, 7 Reconstitution of anomalous pulmonary venous drainage into the left atrium and ASD closure with an intracaval baffle and patch enlargement of the cavoatrial junction provides an additional option for the treatment of this condition. This procedure may be considered when the anomalous pulmonary veins enter the SVC at or just superior to the cavoatrial junction. For veins that enter higher in the SVC (at or above the azygous vein) it is probably safest to perform the Warden procedure to avoid the creation of a long baffle within the SVC that may be prone to obstruction of either pulmonary venous or SVC blood flow. Alternative procedures are best considered as well if the blood supply to the SA node is jeopardized by the caval incision required for placement of the baffle. This situation arises when the SA node artery takes a posterior (retrocaval) course or encircles the cavoatrial junction. Despite the potential for damage to the SA node with intracaval baffle of the anomalous pulmonary veins or any of the described surgical approaches to this condition, long-term dysfunction of the conduction system is relatively rare.6, 7 Walker reported a 9% incidence of SA node dysfunction in the immediate postoperative period; however, this recovered in all patients with no evidence of sinus node dysfunction in any patient after nearly 4 years average follow-up. During a median follow-up of more than 10 years following repair, Jost and coworkers found that SA node dysfunction was documented in only 6% of patients.6
References
- . Surgical Anatomy of the Heart . (ed 2).. London: Gower Medical Publishing; 1992;
- . Partial anomalous pulmonary venous connection to the superior vena cava . Ann Thorac Surg . 1995;60:S614–S617
- An alternative method for repair of partial anomalous pulmonary venous connection to the superior vena cava . Ann Thorac Surg . 1984;38:601–605
- Surgical techniques in partial anomalous pulmonary veins to the superior vena cava . Ann Thorac Surg . 1993;55:1222–1226
- . Sinus venosus atrial septal defects (surgical follow-up) . Eur J Cardiothorac Surg . 1997;11:455–457
- Sinus venosus atrial septal defect (long-term postoperative outcome for 115 patients) . Circulation . 2005;112:1953–1958
- Paucity of sinus node dysfunction following repair of sinus venosus defects in children . Am J Cardiol . 2001;87:1223–1226 A8
PII: S1522-2942(06)00028-6
doi:10.1053/j.optechstcvs.2006.02.003
© 2006 Elsevier Inc. All rights reserved.
Volume 11, Issue 1 , Pages 33-44, Spring 2006
