PAPVR (RUPV–SVC): Anatomy, Hemodynamics, and Surgical Repair

Anatomy, Hemodynamics, and Surgical Repair

Partial anomalous pulmonary venous return (PAPVR) involving the right upper pulmonary vein (RUPV) and superior vena cava (SVC) is a classic lesion associated with a superior sinus venosus atrial septal defect (SVASD). The central abnormality is not merely an atrial septal communication, but an anomalous pulmonary venous connection in which oxygenated blood from the right lung returns to the systemic venous circulation—most often the SVC, the SVC–right atrial junction, or the high right atrium—instead of the left atrium.

The surgical goal is conceptually simple but technically delicate: redirect the anomalous pulmonary venous pathway to the left atrium while preserving a wide, unobstructed SVC pathway to the right atrium. The long-term success of repair depends on maintaining both pathways without stenosis and avoiding injury to the sinus node region [1, 2].

1. Anatomy and Physiologic Burden

1.1 Anatomic pattern

In RUPV–SVC type PAPVR, one or more right-sided pulmonary veins drain anomalously into the SVC or the high RA. The lesion is commonly associated with a superior SVASD, located near the cavoatrial junction rather than within the central fossa ovalis.

Key anatomic features include:

1. Anomalous pulmonary venous connection
• The RUPV, and sometimes the right middle pulmonary vein, drains into the SVC or high RA.
• The left pulmonary veins usually drain normally into the LA.
2. Superior sinus venosus ASD
• Provides an interatrial communication near the SVC–RA junction.
• Allows oxygenated pulmonary venous blood to enter the right-sided circulation.
3. Right-sided volume overload
• Oxygenated pulmonary venous blood returns to the RA/SVC.
• This creates chronic RA and RV volume loading, similar to a significant left-to-right shunt.

1.2 Hemodynamic principle

The RA is a highly compliant receiving chamber. Therefore, anomalous pulmonary venous blood returning to the RA/SVC preferentially enters the right-sided circulation, producing a left-to-right shunt at the venous and atrial levels.

The magnitude of the shunt depends on:

• Number of anomalous pulmonary veins
• Size and location of the sinus venosus ASD
• Relative atrial compliance and pressure
• Pulmonary vascular resistance
• Contribution of the right lung to total pulmonary venous return

Because the right lung contributes a large portion of total pulmonary blood flow, anomalous drainage of right-sided pulmonary veins can generate a substantial shunt burden. Even involvement of two right pulmonary veins may represent a major fraction of pulmonary venous return.

2. Indication and Timing of Repair

Surgical repair is generally indicated when PAPVR with SVASD causes clinically meaningful right-sided volume overload, typically manifested by RA/RV dilation, increased pulmonary blood flow, or symptoms such as exercise intolerance, dyspnea, or recurrent respiratory issues. In children, many patients are repaired electively before long-standing right heart dilation, arrhythmia substrate, or pulmonary vascular disease develops.

Important preoperative assessment includes:

• Echocardiographic evaluation of RA/RV size and function
• CT or MRI definition of pulmonary venous anatomy
• Identification of the level of anomalous pulmonary venous entry into the SVC
• Assessment of SVC length and relationship to the right atrial appendage
• Estimation of Qp/Qs when needed
• Evaluation for associated lesions

The most important anatomic determinant of surgical strategy is the height of pulmonary venous drainage into the SVC. Low drainage near the cavoatrial junction may be suitable for patch repair, whereas high drainage into the SVC often favors the Warden procedure [1, 3].

3. Surgical Objectives

The operation must create two durable, non-obstructed venous pathways:

1. Pulmonary venous pathway
• RUPV/SVC-side pulmonary venous blood must be redirected to the LA.
2. Systemic venous pathway
• SVC blood must return freely to the RA/RV.

Therefore, the surgeon must avoid three major complications:

• Pulmonary venous pathway obstruction
• SVC obstruction
• Sinus node dysfunction

The technical challenge is not simply closing the ASD. The true surgical endpoint is reconstruction of two smooth venous channels with adequate growth potential and minimal rhythm disturbance.

4. Double-Patch Technique

The double-patch technique is typically considered when the anomalous pulmonary venous connection enters relatively low into the SVC or near the SVC–RA junction. In this setting, an intracardiac baffle can redirect pulmonary venous blood to the LA without creating an excessively long or narrow pathway.

4.1 Operative concept

The double-patch technique uses two separate patches:

1. First patch: intracardiac pulmonary venous baffle
• Redirects anomalous pulmonary venous blood through the SVASD into the LA.
2. Second patch: SVC/cavoatrial augmentation patch
• Enlarges the systemic venous pathway.
• Prevents SVC narrowing caused by the intracardiac baffle.

4.2 Stepwise repair

Step 1: Define the anatomy

The surgeon identifies:

• SVC
• RUPV orifice
• SVC–RA junction
• Sinus node region
• Superior SVASD
• Relationship between the anomalous PV and the LA

The incision is usually planned along the lateral RA and anterior SVC, while avoiding unnecessary injury to the sinus node region.

Step 2: Construct the pulmonary venous baffle

The first patch is placed to redirect the anomalous pulmonary venous flow across the SVASD into the LA.

The baffle should be:

• Wide
• Smooth
• Non-restrictive
• Free of sharp angulation
• Positioned without compromising SVC flow

Step 3: Augment the systemic venous pathway

The second patch enlarges the SVC–RA junction and offsets the narrowing that may be caused by the internal baffle.

The purpose of the second patch is to:

• Preserve SVC drainage
• Reduce cavoatrial narrowing
• Lower the risk of postoperative SVC stenosis
• Maintain a generous systemic venous channel

4.3 Strengths and limitations

The double-patch technique provides direct intracardiac rerouting and is anatomically logical for low anomalous venous drainage. However, because it requires manipulation near the cavoatrial junction, it may be associated with sinus node dysfunction, especially when the incision or suture line involves the sinus node region or its arterial supply.

Comparative studies suggest that double-patch repair can achieve excellent survival and low rates of major venous obstruction when properly selected, but early postoperative sinus node dysfunction appears more frequent than after the Warden procedure in some series [3].

5. Warden Procedure

The Warden procedure was developed for PAPVR draining into the high SVC. In this anatomy, a conventional intracaval baffle may become long, narrow, or prone to obstruction. The Warden strategy avoids this problem by dividing the SVC and separating the pulmonary venous and systemic venous pathways [1].

5.1 Operative concept

The Warden procedure creates two separate routes:

1. Pulmonary venous route
• The lower SVC stump containing the anomalous pulmonary venous orifice is baffled through the SVASD into the LA.
2. Systemic venous route
• The distal SVC is anastomosed to the right atrial appendage.

This approach avoids a long intracaval baffle and may reduce surgical trauma near the sinus node.

5.2 Stepwise repair

Step 1: Identify the anomalous pulmonary venous entry

The level of RUPV drainage into the SVC is carefully defined. This determines the level of SVC division and whether the distal SVC can reach the right atrial appendage without tension.

Step 2: Divide the SVC

The SVC is divided above or at the level required to keep the anomalous pulmonary venous orifice on the lower SVC/atrial side.

Key principle:

• The anomalous pulmonary venous orifice must remain with the pulmonary venous pathway.
• The distal SVC must have enough length for a tension-free anastomosis to the right atrial appendage.

Step 3: Redirect the pulmonary venous pathway to the LA

The proximal SVC stump is closed or incorporated into the intracardiac baffle. The SVASD is patched so that the anomalous pulmonary venous blood enters the LA.

The baffle must be:

• Wide
• Smooth
• Short when possible
• Free of compression or kinking

Step 4: Reconstruct the systemic venous pathway

The right atrial appendage is opened and prepared. Trabeculations may be removed to create a smooth receiving chamber. The distal SVC is then anastomosed to the right atrial appendage.

Technical priorities include:

• Tension-free SVC–RAA anastomosis
• Wide anastomotic diameter
• No twisting of the SVC
• No compression by surrounding structures
• Preservation of sinus rhythm

Step 5: Patch augmentation when necessary

If the SVC–RAA anastomosis appears narrow or under tension, anterior patch augmentation should be considered. This is particularly important in smaller children or when the distance between the distal SVC and right atrial appendage is relatively long.

6. Double Patch vs Warden Procedure

The choice between double patch and Warden repair should be anatomy-driven rather than dogmatic. The Warden procedure is not automatically superior for every patient, but it is particularly useful when the anomalous pulmonary venous connection is high in the SVC.

6.1 Practical selection criteria

6.2 Evidence-based comparison

Several comparative and institutional series show excellent survival after both approaches. However, the Warden procedure is often associated with a lower rate of early sinus node dysfunction, likely because it avoids a long incision across the cavoatrial junction [3, 4].

A comparative series of double-patch and Warden techniques reported excellent early and mid-term outcomes with no mortality and minimal venous obstruction, while early sinus node dysfunction was more common after double-patch repair [3]. Pediatric Warden series also report no operative mortality, low pacemaker requirement, and generally favorable mid-term outcomes, although SVC obstruction can occur and may require catheter-based intervention [2].

More recent Warden series emphasize that younger age and smaller patient size may increase the risk of reintervention, particularly for SVC pathway obstruction [6]. Therefore, when the Warden procedure is performed in infants or small children, the surgeon must pay meticulous attention to SVC length, anastomotic geometry, and growth potential.

7. Modified Techniques and Alternative Reconstructions

7.1 Modified two-patch repair

Modified two-patch techniques have been developed to reduce the risks of SVC obstruction and sinus node dysfunction. Some approaches use the right atrial appendage or atrial tissue to augment the systemic venous pathway and avoid narrowing at the SVC–RA junction [5].

The conceptual advantage is to preserve the simplicity of patch repair while improving the geometry of the systemic venous channel.

7.2 Double-decker repair

The double-decker technique is an alternative reconstruction for PAPVR draining into the SVC. It creates separate “stacked” venous pathways for pulmonary venous and systemic venous return, aiming to avoid both pulmonary venous and SVC obstruction [4].

This approach reflects the same core principle: the repair must create two independent, unobstructed channels rather than merely redirect flow through a narrow intracardiac tunnel.

7.3 Modified Warden strategies

Modified Warden procedures may include:

• Patch augmentation of the SVC–RAA anastomosis
• Use of right atrial appendage flap
• Interposition graft or conduit in selected cases
• Enlargement of the atrial septal communication
• Customized repair based on SVC length and PV insertion height

These modifications are particularly relevant when the distal SVC cannot reach the right atrial appendage without tension or when the patient is small.

8. Technical Pitfalls and Surgical Pearls

8.1 Avoid sinus node dysfunction

The sinus node lies near the SVC–RA junction. Sinus node dysfunction may result from:

• Incision across the cavoatrial junction
• Direct suture injury
• Disruption of sinus node arterial supply
• Excessive traction or distortion
• Patch placement near the sinus node region

The Warden procedure may reduce this risk by avoiding extensive cavoatrial incision, but rhythm preservation still depends on careful technique.

8.2 Prevent pulmonary venous obstruction

Pulmonary venous pathway obstruction is one of the most important late complications.

Risk factors include:

• Narrow intracardiac baffle
• Long baffle pathway
• Sharp angulation
• Inadequate enlargement of the SVASD
• Patch redundancy
• High anomalous PV insertion
• Compression between reconstructed pathways

The pulmonary venous pathway should be inspected as a three-dimensional channel, not simply as a closed septal defect.

8.3 Prevent SVC obstruction

SVC obstruction can occur after both patch repair and Warden repair.

Preventive strategies include:

• Generous SVC augmentation in double-patch repair
• Tension-free SVC–RAA anastomosis in Warden repair
• Patch augmentation when the anastomosis is narrow
• Avoidance of twisting or kinking of the distal SVC
• Attention to future somatic growth in small children

SVC obstruction after Warden repair is often treatable by catheter intervention, but prevention at the initial operation remains the best strategy [6, 7].

9. Postoperative Evaluation

Postoperative assessment must evaluate both reconstructed pathways.

9.1 Pulmonary venous pathway

Assess for:

• Laminar pulmonary venous flow into the LA
• No Doppler acceleration across the baffle
• No pulmonary venous obstruction
• No residual atrial-level shunt

9.2 Systemic venous pathway

Assess for:

• Unobstructed SVC flow into the RA
• No SVC gradient
• No upper-body venous congestion
• No narrowing at the SVC–RAA anastomosis after Warden repair

9.3 Rhythm surveillance

Because sinus node dysfunction is a recognized complication, follow-up should include:

• Early postoperative rhythm monitoring
• Assessment for junctional rhythm or sinus bradycardia
• Long-term surveillance for atrial arrhythmias
• Consideration of Holter monitoring when clinically indicated

Large contemporary Warden series demonstrate satisfactory early and late survival, but persistent sinus node dysfunction, venous pathway obstruction, and reintervention remain important outcome measures [8].

10. Summary

PAPVR with RUPV drainage to the SVC and superior SVASD is a lesion of abnormal venous routing and right-sided volume overload. The operation is not simply ASD closure; it is reconstruction of two venous pathways:

1. Pulmonary venous blood must be redirected to the LA.
2. Systemic venous blood from the SVC must return freely to the RA.

The double-patch technique is useful when the anomalous pulmonary venous drainage is low and a short, wide intracardiac baffle can be constructed. The Warden procedure is particularly valuable when the anomalous pulmonary venous connection is high in the SVC, where a long intracaval baffle would risk obstruction.

Both strategies can achieve excellent survival and durable repair when anatomy is appropriately selected. The key determinants of long-term success are prevention of pulmonary venous obstruction, prevention of SVC obstruction, preservation of sinus node function, and careful follow-up for late venous pathway stenosis or rhythm disturbance.

References

[1] Warden HE, Gustafson RA, Tarnay TJ, Neal WA. An alternative method for repair of partial anomalous pulmonary venous connection to the superior vena cava. Ann Thorac Surg. 1984;38(6):601-605.

[2] Yong MS, Griffiths S, Robertson T, Brink J, d’Udekem Y, Brizard CP, Konstantinov IE. Outcomes of the Warden procedure for partial anomalous pulmonary venous drainage in children. Interact Cardiovasc Thorac Surg. 2018;27(3):422-426.

[3] Zubritskiy A, Naberukhin Y, Arkhipov A, et al. Outcomes of double-patch and Warden techniques in patients with supracardiac partial anomalous pulmonary venous connection. Heart Lung Circ. 2020;29(1):156-161.

[4] Hongu H, Yamagishi M, Maeda Y, Itatani K, Asada S, Fujita A, Yaku H. Double-decker repair of partial anomalous pulmonary venous return into the superior vena cava. J Thorac Cardiovasc Surg. 2019;157(5):1970-1977.

[5] Elzein C, Abdulkarim M, Abbas U, Vricella L, Ilbawi M. Repair of superior sinus venosus atrial septal defect using a modified two-patch technique. Ann Thorac Surg. 2020;109(2):583-587.

[6] Binsalamah ZM, Ibarra C, Edmunds EE, Qureshi AM, Adachi I, Caldarone CA, et al. Younger age at operation is associated with reinterventions following the Warden procedure. Ann Thorac Surg. 2021;111(6):2059-2065.

[7] Lim SC, Kwak JG, Cho S, Min J, Lee S, Kwon H, Kim WH. Outcomes of the Warden procedure for anomalous pulmonary venous return to the superior vena cava: a 17-year experience. J Chest Surg. 2022;55(3):206-213.

[8] Griffeth EM, Dearani JA, Mathew J, Graham G, Connolly HM, King KS, Schaff HV, Stephens EH. Early and late outcomes of the Warden and modified Warden procedure. Ann Thorac Surg. 2022;114(5):1723-1729.