Role of Collateral Venous Circulation in Prevention of Sinistral Portal Hypertension After Superior Mesenteric-Portal Vein Confluence Resection during Pancreaticoduodenectomy: a Single-Center Experience

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Executive Summary

Ligation of the splenic vein (SV) during pancreaticoduodenectomy (PD) for cancers involving the superior mesenteric-portal vein confluence traditionally carries a high risk of sinistral portal hypertension (SPH). SPH can lead to severe clinical complications, including splenomegaly, thrombocytopenia, and life-threatening gastrointestinal (GI) bleeding from varices.

This retrospective single-center study of 43 patients who underwent PD with SV ligation demonstrates that while subclinical SPH (indicated by splenomegaly and thrombocytopenia) is common, clinically significant GI bleeding is rare. The study identifies three primary collateral venous routes—the left gastric, colic marginal, and first jejunal routes—that provide sufficient decompression of the splenic bed. Crucially, the preservation of the arc of Barkow, the greater omentum, and the first jejunal vein appears to be a vital surgical strategy for preventing clinical SPH and maintaining venous drainage after SV ligation.

Overview of the Clinical Challenge

In patients with cancers of the pancreatic head, uncinate process, or neck, tumor invasion often involves the confluence of the portal vein (PV), superior mesenteric vein (SMV), and splenic vein (SV). While advances in surgical techniques allow for extensive venous resection and reconstruction, the management of the SV remains a subject of debate.

  • The Risk of SPH: Ligation of the SV without reconstruction is historically associated with SPH.

  • Contradictory Evidence: Some clinical series report high rates of variceal bleeding, while others report no clinical manifestations following SV ligation.

  • The Study's Hypothesis: The specific surgical technique—specifically the preservation of preformed or potential collateral pathways—determines the ultimate risk of SPH and subsequent GI bleeding.

Study Parameters and Surgical Outcomes

The study analyzed 43 patients (28 men, 15 women; mean age 64) who underwent PD with PV/SMV reconstruction and SV ligation between 2013 and 2018.

Venous Preservation and Reconstruction

All 43 patients underwent successful end-to-end anastomosis (most commonly SMV to PV). During these procedures:

  • The left gastric vein (LGV) was preserved in 32.5% of cases.

  • The inferior mesenteric vein (IMV) was preserved in 41.8% of cases.

  • The middle colic vein was preserved in 14.0% of cases.

  • The Henle trunk was sacrificed in all patients.

Identification of Collateral Venous Drainage Routes

The study utilized three-dimensional CT reconstruction to identify three distinct routes that established blood flow from the spleen back to the portal system.

1. The Left Gastric Route

This route establishes flow from the spleen via the short gastric vein, left gastric vein (or aberrant left gastric vein) to the esophageal vein or portal vein.

  • Prevalence: Identified in 46.5% of patients.

  • Observation: 92.8% of patients with LGV preservation developed left gastric varices, indicating its role in decompression.

2. The Colic Marginal Route

This route utilizes the arc of Barkow along the edge of the omentum to direct flow into the transverse colic marginal vein and eventually the SMV.

  • Prevalence: Identified in 81.4% of patients.

  • Surgical Note: The arc of Barkow was routinely preserved and was seen to dilate postoperatively in 74.4% of patients.

3. The First Jejunal Route

This route develops through pancreatojejunal and gastrojejunal anastomoses, draining into the first jejunal vein (FJV).

  • Prevalence: Identified in 86.0% of patients.

  • Significance: This route effectively releases venous congestion around the gastrojejunostomy, particularly in patients where the IMV was ligated.

Manifestations of Subclinical SPH

While clinical GI bleeding was avoided, the study found significant evidence of subclinical SPH and splenic hypofunction.

Thrombocytopenia, while not resulting in massive hemorrhage in this series, is noted as a potential obstacle for patients requiring adjuvant chemotherapy to extend survival.

Analysis and Conclusion

Comparison with Existing Literature

The study contextualizes its findings against prior research, noting a lack of consensus on SV reconstruction. While some authors argue for reconstruction to avoid varices, this study aligns with those suggesting that SV ligation is safe provided critical collateral pathways are maintained.

Critical Success Factors in SV Ligation

  • Omental Preservation: Maintaining the attachment of the splenocolic omentum to the transverse colon allows the arc of Barkow to function as a major decompressive channel.

  • First Jejunal Vein (FJV) Preservation: Preserving the FJV is essential for decompressing esophageal and gastrojejunostomy varices.

  • Individualized Therapy: Surgical decisions regarding SV reconstruction should be based on how many critical veins (LGV, IMV, MCV) can be preserved during resection.

Final Conclusion

The study concludes that intraoperative preservation of the arc of Barkow, the omental veins, and the first jejunal vein is a reasonable and effective strategy to prevent the clinical complications of SPH after PD. By facilitating the development of the three identified collateral routes, surgeons can achieve R0 resection without the added complexity or risk of SV reconstruction or graft placement, which carries its own risk of thrombosis and stenosis.