The success of a pancreas transplant, a life-altering procedure for individuals with type 1 diabetes, begins long before the organ reaches the recipient. The critical first phase is the organ recovery, or procurement, from a deceased donor. This intricate surgical process demands meticulous technique, profound anatomical knowledge, and careful decision-making to ensure the pancreas is retrieved in optimal condition. A high-quality graft is paramount for successful engraftment, long-term function, and minimizing post-operative complications.
The Foundations of Pancreas Recovery: The Organ Procurement Process
Organ procurement is a highly coordinated, multi-team effort. Once a donor has been declared brain dead and consent for donation has been obtained, the surgical recovery team is mobilized. The primary goal during this phase is to maintain the donor’s physiological stability while preparing for the systematic and rapid cooling and removal of the organs to minimize ischemic damage.
A. Donor Evaluation and Surgical Preparation: Before the initial incision, the surgical team reviews the donor’s medical history, laboratory values (including lipase and glucose levels), and imaging studies. In the operating room, the donor is positioned supinely, and a wide sterile field is prepared, extending from the chin to the pubis. A long midline incision (sternotomy to pubis) is made to provide maximum exposure to the thoracic and abdominal organs.
B. Initial Exploration and Mobilization: Upon entering the abdominal cavity, the surgeon performs an initial inspection of the pancreas. It is assessed for any signs of trauma, edema, significant fat infiltration, or masses that might preclude its use. The first major surgical maneuver is the mobilization of the ascending and descending colon (a wide Kocher maneuver and Cattell-Braasch maneuver). This exposes the great vessels—the aorta and inferior vena cava (IVC)—as well as the duodenum and the head of the pancreas.
C. Systemic Heparinization and Cannulation: To prevent blood from clotting within the organ’s small vessels during the cooling process, the donor is given a large dose of systemic heparin (typically 30,000-40,000 units). Following this, cannulas are strategically placed. An arterial cannula is inserted into the distal aorta, which will be used to infuse cold preservation solution throughout the abdominal organs. A venous cannula is often placed in the portal vein or inferior mesenteric vein to decompress the portal system and allow for efficient flushing of blood from the liver and pancreas.
D. In Situ Cold Perfusion: Once all surgical teams (heart, lung, liver, pancreas, kidney) are ready, the aorta is cross-clamped at the supraceliac level. Immediately, cold preservation solution is infused rapidly through the aortic cannula. This flushes the warm blood out of the organs and quickly drops their core temperature, drastically reducing their metabolic rate and oxygen demand. This moment marks the beginning of “cold ischemic time” and is the most critical step in preventing cellular injury.
A-traumatic Handling: Using the Spleen as a Handle
The pancreas is a notoriously delicate and friable organ. Its soft, glandular tissue is encased in a thin capsule that is easily torn. Direct grasping or excessive manipulation with surgical instruments can cause:
- Capsular fractures: Leading to leakage of digestive enzymes.
- Intraparenchymal hematomas: Blood clots within the gland.
- Post-recovery pancreatitis: Inflammation triggered by physical trauma.
Any of these injuries can render the organ unsuitable for transplantation. To avoid this, surgeons employ an elegant technique that uses an adjacent, more robust organ as a tool.
The tail of the pancreas is intimately attached to the hilum of the spleen. The splenic artery and vein, which represent the primary blood supply and drainage for the body and tail of the pancreas, run directly along its posterior aspect. By treating the spleen and pancreas as a single unit, surgeons can safely mobilize the gland.
The Technique: The surgeon begins by carefully dividing the ligaments that hold the spleen in place (the splenorenal and gastrosplenic ligaments). Once the spleen is freed from its attachments, it can be gently grasped. By retracting the spleen medially (towards the center of the body), the surgeon can lift the entire tail and body of the pancreas away from its retroperitoneal bed without ever directly touching the pancreatic tissue. The spleen effectively acts as a “handle,” allowing for safe dissection and mobilization of the entire distal portion of the pancreas.
Managing Anatomical Variations: The Replaced Right Hepatic Artery (RHA)
One of the most significant challenges in a multi-organ recovery is navigating anatomical variations. The most common and critical variation affecting pancreas procurement is a “replaced” or “aberrant” right hepatic artery (RHA). In approximately 15-20% of individuals, the RHA, which supplies the right lobe of the liver, does not arise from its usual origin (the common hepatic artery) but instead branches directly off the superior mesenteric artery (SMA).
The Problem: The SMA is the primary blood supply to the head of the pancreas. A replaced RHA often travels directly posterior to, or sometimes through, the pancreatic head on its way to the liver. If a liver and pancreas are being procured simultaneously, failure to identify and meticulously preserve this vessel could be catastrophic for the liver recipient, as ligating it would cut off blood flow to the right lobe of the liver.
The Surgical Approach:
- Identification: The surgeon must carefully dissect the root of the small bowel mesentery to identify the SMA. By palpating for its strong pulse and tracing its course, any large branches heading towards the liver can be identified as a potential replaced RHA.
- Decision and Dissection: When a replaced RHA is confirmed, the procurement teams must coordinate. The vessel must be preserved with the liver graft. This requires dissecting the origin of the SMA and carefully separating the RHA from the pancreatic head.
- Pancreas Reconstruction: Taking the RHA with the liver leaves the pancreas graft without its primary inflow from the SMA. To solve this, the pancreas is procured with both the celiac axis and the stump of the SMA. On the “back table” (a sterile table where the organ is prepared for transplant), the surgeon will perform a vascular reconstruction. This typically involves using a Y-graft, often fashioned from the donor’s iliac artery, to connect the donor splenic artery and the donor SMA stump to a single arterial inflow, which will then be anastomosed in the recipient.
Choosing the Preservation Solution: University of Wisconsin (UW) vs. HTK
The choice of cold preservation solution is vital for minimizing ischemic injury during transport. The two most widely used solutions are the University of Wisconsin (UW) solution and the Histidine-Tryptophan-Ketoglutarate (HTK) solution.
University of Wisconsin (UW) Solution:
- Composition: An “intracellular-like” solution, high in potassium and sodium. Its key components are lactobionate and raffinose, which are large, impermeable molecules that prevent cells from swelling (cytotoxic edema). It also contains hydroxyethyl starch (HES) to provide oncotic pressure and prevent tissue edema, and antioxidants like allopurinol and glutathione to combat free radical damage.
- Characteristics: UW is highly viscous due to the HES. It has historically been considered the gold standard for abdominal organ preservation, especially for the pancreas.
- Pros: Proven efficacy, particularly for extended cold ischemic times (>15 hours) and for organs from “extended criteria donors.”
- Cons: High viscosity can sometimes lead to incomplete or slow flushing of the microvasculature. It is also significantly more expensive than HTK.
Histidine-Tryptophan-Ketoglutarate (HTK) Solution (Custodiol®):
- Composition: An “extracellular-like” solution, low in potassium. Its primary buffer is histidine, which is effective at low temperatures. Tryptophan helps stabilize cell membranes, and ketoglutarate provides a substrate for aerobic metabolism upon reperfusion.
- Characteristics: HTK has a very low viscosity, similar to water.
- Pros: The low viscosity allows for rapid and uniform cooling and flushing of the organ, which is a distinct advantage. It is also much less expensive.
- Cons: Some studies suggest that for very long cold ischemic times, UW may offer superior protection for the pancreas. However, for standard recovery times (under 12-15 hours), outcomes are widely considered to be equivalent to UW.
The Choice: The decision between UW and HTK often comes down to institutional protocol, surgeon preference, anticipated ischemic time, and cost. Many centers use HTK for its rapid flush properties and reserve the more expensive UW solution for cases where a long transport time is expected or the donor quality is suboptimal.
Conclusion
The recovery of a pancreas for transplantation is a technically demanding procedure where every step has profound implications for the graft’s future success. From the organized chaos of the initial procurement to the delicate, a-traumatic handling of the gland using the spleen, the careful navigation of vascular anatomy, and the science-driven choice of preservation fluid, each action is deliberate. Mastery of these techniques ensures that a life-saving organ is given the best possible start, maximizing the potential for a transformative outcome for the recipient.
