Spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein: techniques and its significance
Executive Summary
Spleen-preserving distal pancreatectomy (SpDP) with conservation of the splenic artery and vein—frequently referred to as Kimura’s procedure—is a specialized surgical technique indicated for benign lesions, low-grade malignancies, and chronic pancreatitis of the pancreatic body and tail. This approach prioritizes the preservation of the spleen to maintain immunologic capabilities and prevent post-splenectomy complications such as sepsis, changes in peripheral blood counts, and intestinal obstruction (ileus).
A critical finding in the comparative analysis of SpDP and distal pancreatectomy with splenectomy (DPS) is the significant difference in postoperative platelet levels. SpDP patients experience a much lower increase in platelet counts, which may reduce the risk of pulmonary and cerebral infarctions. Furthermore, the conservation of the splenic artery and vein is vital for maintaining blood supply to the proximal stomach, particularly in patients who have undergone or require distal gastrectomy. Clinical data indicates that while SpDP may require longer operative times, it offers superior physiological outcomes without increasing the incidence of pancreatic fistulas or diabetes mellitus.
Anatomical Foundation: The Fusion Fascia
Successful execution of SpDP requires a precise understanding of the pancreatic anatomy and its relationship to the retroperitoneum, specifically the "fusion fascia."
Treitz and Toldt Fascia
During embryonic development, the pancreas consists of ventral and dorsal buds. As the ventral bud moves around the duodenum and contacts the dorsal bud, the membranes fuse with the inferior vena cava and abdominal aorta.
Fusion Fascia of Treitz: Located at the head of the pancreas.
Fusion Fascia of Toldt: Located at the body and tail of the pancreas.
Composition and Significance
Structure: The fusion fascia is composed of loose connective tissue. Though it appears fragile, it is structurally strong and contains a high density of arteries, arterioles, veins, and nerves situated between the fascia and the pancreatic parenchyma.
Surgical Access: In maneuvers such as Kocher’s mobilization, the fascia adheres to the pancreatic side rather than the vena cava. The splenic artery, splenic vein, and pancreatic parenchyma are all contained within the area surrounded by the fusion fascia of Toldt.
Surgical Methodology and Techniques
The procedure relies on specific directional approaches to safely isolate the pancreas from the splenic vasculature.
Venous and Arterial Isolation
The technique prioritizes a median-to-lateral approach for the venous system:
Splenic Vein Identification: The vein is located behind the pancreas within the fusion fascia of Toldt.
Median Approach: The fascia is cut longitudinally above the splenic vein. The vein must be removed by working from the pancreatic body toward the spleen. A lateral approach is discouraged because the distal end of the pancreas is difficult to distinguish from fatty tissue in the splenic hilum, where vessels are smaller and easily injured.
Arterial Removal: Unlike the vein, the pancreatic parenchyma is removed from the splenic artery by proceeding from the spleen toward the head of the pancreas.
Hand-Assisted Laparoscopic Surgery (HALS)
SpDP can be performed using HALS, where the spleen and distal pancreas are mobilized retroperitoneally and exteriorized through a 7-cm upper-middle incision. The pancreas is then meticulously separated from the splenic vessels outside the abdominal cavity.
Comparative Clinical Analysis: SpDP vs. DPS
A study comparing 16 SpDP patients with 16 DPS patients (2001–2007) highlights the physiological advantages of splenic preservation.
Platelet Count and Infarction Prevention
The most significant clinical difference lies in postoperative hematological profiles:
Maximal Platelet Count: SpDP patients reached a maximum platelet count of 39.5 ± 13.3 x 10^4, whereas DPS patients reached 58.9 ± 19.5 x 10^4 (P < 0.01).
Timing: The peak occurred earlier in SpDP patients (approximately Day 10) compared to DPS patients (approximately Day 13).
Clinical Impact: The lower platelet elevation in SpDP helps prevent serious postoperative complications such as lung and brain infarctions.
Operative and Postoperative Data
Clinical Indications and Vascular Significance
Indications for Kimura's Procedure
The procedure is recommended for:
Benign Lesions: Serous cystic neoplasms (SCN), epidermoid cysts, and retention cysts.
Low-grade Malignancies: Intraductal papillary-mucinous neoplasms (IPMN), particularly intraductal papillary-mucinous adenoma (IPMA), and endocrine tumors (e.g., insulinoma, glucagonoma).
Chronic Pancreatitis: Especially in younger patients where lifelong splenic function is critical.
Preservation of Gastric Blood Supply
A primary significance of conserving both the splenic artery and vein is the maintenance of blood flow to the residual proximal stomach.
Distal Gastrectomy Context: In patients who have undergone distal gastrectomy with resection of the left gastric artery, the short gastric arteries (originating from the splenic artery) become the primary blood supply for the remaining stomach.
Risk of DPS: If a splenectomy (DPS) is performed in these patients, the lack of blood supply can necessitate the total resection of the residual stomach. SpDP ensures gastric viability by maintaining this vascular bypass.
Complication Profile
Theoretical risks of SpDP include postoperative bleeding from the ablated vein (due to digestion by pancreatic juice) and torsion of the splenic vessels. However, clinical experience shows that when performed correctly using the fusion fascia as a guide, these complications are not encountered, making the procedure a safe and reliable method for organ-preserving pancreatic surgery.
