PAPVR (RUPV-SVC) #1 Anatomy and Physiology

Partial anomalous pulmonary venous return (PAPVR) is a congenital pulmonary venous anomaly in which one or more (but not all) pulmonary veins drain to the systemic venous circulation—most commonly the superior vena cava (SVC) and/or right atrium (RA)—rather than to the left atrium (LA). In the typical phenotype RUPV → SVC/RA, frequently associated with a superior sinus venosus atrial septal defect (SV-ASD), the physiology is dominated by a pre-atrial left-to-right shunt that functions as “pulmonary recirculation”: oxygenated pulmonary venous blood returns to the right heart and is retransmitted to the lungs instead of contributing to LV preload and systemic output [1].

1) Core anatomy: what is structurally abnormal

1. Anomalous drainage site
• The right upper pulmonary vein (RUPV) (often with additional right PVs) drains into the SVC and/or high RA, so oxygenated pulmonary venous blood re-enters the right-sided circulation [1].
2. Partner lesion: superior sinus venosus ASD
• SV-ASD is not merely an “associated ASD”; it reflects malalignment at the SVC–RA–atrial septal interface and typically coexists with anomalous right PV drainage, creating a geometry that facilitates shunting and determines repair strategy [2].
3. Why right-sided PAPVR tends to be hemodynamically important
• Right-sided PAPVR commonly produces prominent right-sided volume loading; imaging series highlight that PAPVR is frequently accompanied by right-heart enlargement and that detection often requires cross-sectional imaging when echocardiography is equivocal [1].

2) Hemodynamic engine: why shunt magnitude can exceed expectations

A. “Compliance-driven runoff” (atrial reservoir effect)

• The RA is typically more compliant than the LA, so for the same added volume, RA pressure rises less than LA pressure.
• When oxygenated pulmonary venous return is redirected to SVC/RA, it preferentially enters a lower-pressure, higher-compliance reservoir, promoting an effective left-to-right shunt (RA → RV → PA → lungs) rather than augmenting LV preload [2].

B. “Partial” does not mean “small”

• Shunt magnitude is determined by flow fraction, not simply the label “partial.” Even a limited number of anomalous veins can drive meaningful volume load when the anomalous territory supplies a large proportion of pulmonary blood flow and when SV-ASD provides an additional low-resistance pathway [1,2].

3) Preoperative physiology: what you should expect clinically and on imaging

A. Chamber-level consequences (signature phenotype)

• RA/RV volume overload is typical:
• RA enlargement
• RV dilation (± mild functional tricuspid regurgitation)
• Increased pulmonary blood flow [1,2]
• The LA/LV may be relatively underfilled compared with total pulmonary blood flow because part of oxygenated return is “misdelivered” to the right heart [2].

B. Shunt behavior

• Net physiology: left-to-right shunt with elevated Qp:Qs (when quantified), determined by:
• Number/territory of anomalous veins
• SV-ASD size and geometry
• Pulmonary vascular resistance and right-heart compliance
• Presence/size of interatrial communication (including surgically relevant septal anatomy) [2]

C. Diagnostic “hooks” (practical pattern recognition)

• Echocardiography: disproportionate RA/RV dilation, difficult-to-visualize right PV connections, and Doppler clues near the SVC–RA junction.
• CT angiography / CMR: define exact PV insertion, SVC–RA geometry, and associated lesions; multimodality pathways improve delineation in complex variants and support operative planning [1,9].

4) Why SV-ASD + PAPVR is a distinct surgical problem

SV-ASD with PAPVR is best treated as a dual-pathway reconstruction problem, not simply ASD closure:

• Pulmonary venous pathway goal: route anomalous pulmonary venous blood to the LA without obstruction.
• Systemic venous pathway goal: preserve unobstructed SVC drainage to the RA without compromising the sinus node region or creating caval narrowing [2,3].

This is why repair selection is anatomy-driven: the operative solution must be tailored to the height of PV insertion, SVC size, cavoatrial junction geometry, and relationship to the sinus node/sinus node artery [2,3].

5) Repair strategy: what the operation must accomplish (and why technique matters)

A. Two mandatory endpoints

1. Eliminate pulmonary recirculation by redirecting anomalous PV return to the LA.
2. Avoid iatrogenic obstruction, specifically:
• SVC obstruction (systemic venous hypertension, head/neck edema, collateralization)
• Pulmonary venous pathway obstruction (pulmonary venous hypertension, lung congestion) [2,3]

B. Technique selection (conceptual algorithm)

• Intracardiac baffle / single-patch approaches
• Best when anomalous PVs enter at or near the cavoatrial junction and when a baffle can be created without narrowing the SVC lumen [2,8].
• Caval division / Warden-type repair
• Particularly suited for high PV insertion into the SVC, where patch/baffle techniques risk SVC narrowing and sinus node region injury. Caval division strategies were developed to reduce sinus node dysfunction and maintain unobstructed venous pathways in high-entry anatomy [3].

C. Rhythm and reintervention implications (evidence-informed)

• Institutional and comparative experiences have shown that technique choice influences sinus node outcomes, with data supporting lower sinus node dysfunction when repairs avoid incisions/manipulation across the cavoatrial junction—a key rationale for Warden-type approaches in appropriate anatomy [2,4,5].
• Pediatric series demonstrate excellent operative survival with the Warden procedure, low permanent pacing requirement, and a low incidence of clinically significant SVC obstruction when performed with attention to geometry [6].
• Risk is not uniform: younger age at Warden repair has been associated with a higher likelihood of subsequent reintervention (often reflecting growth-related geometry and pathway caliber constraints), emphasizing the importance of margin and pathway design in small patients [7].

6) Treatment thresholds: physiology-first indications

Intervention is generally favored when PAPVR/SV-ASD produces hemodynamically significant right-sided volume load, reflected by:

• Clear RA/RV dilation and/or symptoms (exercise intolerance, recurrent respiratory infections, reduced functional capacity)
• Quantitative evidence of meaningful shunt when available
• SV-ASD that is clearly contributory rather than “incidental” in the setting of right heart enlargement [2,6,9]

Principle: operate for volume load + reparability (routable anatomy with acceptable pathway geometry), not merely for the diagnosis label [2,6].

7) Post-repair physiology: what “success” looks like (and what to surveil)

Expected physiologic remodeling

• Right-sided volume unloading with progressive reduction in RA/RV dilation.
• Improved LV preload because oxygenated pulmonary venous return is restored to the LA/LV pathway [2,6].

Surveillance targets (high-yield)

• SVC pathway gradient/stenosis (especially after Warden-type repair; may present late and can require catheter-based intervention) [10,11].
• Pulmonary venous pathway gradient/stenosis (rare but clinically important) [2,6].
• Sinus node dysfunction / atrial arrhythmias: often transient, but persistent dysfunction is a key quality metric and technique-sensitive outcome [2,4,5,11].
• Residual shunt: uncommon with correct geometry and complete rerouting [2,8].

Notably, adult reports highlight that delayed SVC obstruction/SVC syndrome can occur after Warden repair and may require endovascular management—reinforcing the need for durable caval geometry and long-term surveillance [10,11].

References

[1] Ho ML, Bhalla S, Bierhals A, Gutierrez F. MDCT of partial anomalous pulmonary venous return (PAPVR) in adults. J Thorac Imaging. 2009;24(2):89-95.

[2] Stewart RD, Bailliard F, Kelle AM, Backer CL, Young L, Mavroudis C. Evolving surgical strategy for sinus venosus atrial septal defect: effect on sinus node function and late venous obstruction. Ann Thorac Surg. 2007;84(5):1651-1655.

[3] Shahriari A, Rodefeld MD, Turrentine MW, Brown JW. Caval division technique for sinus venosus atrial septal defect with partial anomalous pulmonary venous connection. Ann Thorac Surg. 2006;81(1):224-229.

[4] Agarwal V, Okonta KE, Abubakar U, Gichuhi S. Impact of Warden's procedure on the sinus rhythm: our experience. Heart Lung Circ. 2011;20(11):718-721.

[5] Okonta KE, Agarwal V, Abubakar U, Gichuhi S. Does Warden's procedure reduce sinus node dysfunction after surgery for partial anomalous pulmonary venous connection? Interact Cardiovasc Thorac Surg. 2012;14(4):423-427.

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

[7] Binsalamah ZM, Ibarra C, Edmunds EE, Qureshi AM, Adachi I, Caldarone CA, Imamura M, McKenzie ED, Heinle JS, Spigel ZA. Younger Age at Operation Is Associated With Reinterventions After the Warden Procedure. Ann Thorac Surg. 2021;111(6):2059-2065.

[8] Stephens EH, Mongé MC, Eltayeb O, Patel A, Webster G, Cornicelli MD, Kennedy C, Popescu AR, Rigsby CK, Backer CL. Evolution and Current Results of a Unified Strategy for Sinus Venosus Surgery. Ann Thorac Surg. 2021;111(3):980-986.

[9] Ng LY, Nolke L, James A, Grant B, Franklin O, Redmond JM, McGuinness J, Walsh K, McMahon CJ. Multimodality imaging in delineation of complex sinus venosus defects and treatment outcomes over the last decade. Cardiol Young. 2022;32(7):1112-1120.

[10] Perchik JD, Wilson CM, Abozeed M, Manapragada PP, Ahmed AN, Singh SP. Adult Partial Anomalous Pulmonary Venous Return Repair and Superior Vena Cava Syndrome: A Delayed Complication of the Warden Procedure. Radiol Cardiothorac Imaging. 2022;4(5):e220077.

[11] Griffeth EM, Dearani JA, Mathew J, Graham GC, 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.