Pancreas Removal for Islet Transplantation
For islet procurement, the pancreas is removed together with the liver and the duodenum is simply removed from the pancreatic head.
After initial preparation of the superior mesenteric artery and the celiac trunk, the intestine is repositioned adequately in the abdominal cavity. The first jejunal loop is transected about 10 cm distal to the ligament of Treitz using a GIA stapler . The transected jejunal loop is pulled up by the assistant in order to better individualize the mesenteric root. A second assistant maintains the intestine in place to avoid traction on the superior and inferior mesenteric veins, as malpositioning causes reduced splanchnic perfusion.
Several small branches of the jejunal mesentery are transected close to the serosa (as is usually done in a duodenopancreatectomy). The proximal part of the mesenteric vessels are freed for about 2 cm, so the small pancreatic veins joining the right part of the SMV are ligated, as well as those branches of the SMV draining the pancreatic isthmus. Once the SMV is freed, the abdominal organ perfusion can be started.
As soon as the perfusion is completed, the liver-pancreas-small bowel bloc can be retrieved. In case of an isolated intestinal transplant it can be necessary to extend the superior mesenteric vein and artery using free iliac venous and arterial grafts.
First, the gallbladder and the bile ducts need to be flushed again to avoid mucosal damage by precipitating bile salts. Next, ex-vivo portal flushing is done through a canula introduced in the SMV. The tip of the portal vein catheter is positioned with slight finger compression.
The liver-pancreas bloc is positioned as in the abdominal cavity; the aorta patch, containing the celiac trunk and the superior mesenteric artery, is dissected free. Splenic, celiac, hepatic and left gastric artery should all be individualized; one should look as well for the RHA and the LHA. Bile duct and the portal vein and splenomesenteric venous confluence also need to be dissected. The final repartition of all vascular axes is dictated by their anatomical variability.
A. In the presence of standard arterial anatomy, the celiac trunk should be kept with the whole pancreas transplant. By doing so, a reconstruction with a Y-graft can be avoided as the superior mesenteric artery can be directly connected to the ostium of the common hepatic artery (for illustration see chapter "Orthotopic Liver Transplantation"). The repartition of the venous vessels is usually unproblematic if the recipient portal vein is transected close to the liver parenchyma.
B. If the liver-pancreas bloc contains an LHA originating from the left gastric artery, the celiac trunk should go to the liver graft. In this case, a vascular reconstruction between splenic artery and superior mesenteric artery is necessary using a free iliac arterial graft (see Sect. 6, chapter "Pancreas Transplantation").
C. In the presence of an aberrant RHA with a complete extrapancreatic course, one can decide to divide the superior mesenteric artery between the head of the pancreas and the origin of the aberrant right hepatic artery (see Figure). This allows for three different types of reconstruction (for illustrations see chapter "Orthotopic Liver Transplantation"):
- Anastomosing the stump of the superior mesenteric artery on the ostium of the splenic artery
- Anastomosing the celiac trunk or the common hepatic artery on the proximal ostium of the superior mesenteric artery
- Anastomosing the aberrant right hepatic artery to the gastroduodenal artery
In the case of an intrapancreatic RHA, division of this artery should only be performed after discussion with the pancreas and liver teams. If this artery is transected proximal to the pancreatic head, it must be possible for the liver surgeon to implant the RHA into the ostium of the gastroduodenal or the splenic artery.
Both recipient teams must finally decide if both organs should be implanted because of technical difficulties.
The only anatomical absolute contraindication to simultaneous whole pancreas and liver transplantation is the presence of an important pancreatico-duodenal artery originating from an aberrant RHA. In this case, vascularization of the pancreatic head can be compromised, as the gastroduodenal artery and thus the superior pancreatico-duodenal artery are kept to retain the common hepatic artery for the liver allograft.
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