The Blood Supply of the Pancreas

Arteries

The pancreas, in particular its head, has an abundant blood supply basically derived from the celiac axis and the superior mesenteric artery (SMA). In fact, the collateral pathways between these two arteries are so efficient that the cut surface of the pancreas removed en bloc using the Whipple procedure will often continue to bleed until the very last jejunal branch (and the proximal jejunal artery itself) has been divided. The general pattern of the arterial blood supply and anatomy of the pancreas is shown in figure 1.

The pancreatic head and uncinate process receive arterial blood from two pairs of pancreatoduodenal (PD) arcades. The superior PD arteries, the anterior and posterior, arise from the gastroduodenal artery (GDA) (either separately or

Smv Sma Anatomy

Fig. 1. Vascular anatomy (autopsied pancreas). a Gross appearance. b Horizontal section of the entire infantile pancreas on pancreatic polypeptide staining. The lines indicate the boundaries between the head, body, and tail. c Anterior PD arcade, SMA, and SMV are shown on the front of the pancreas. d Posterior PD arcade, SMA, SMV, SA, and SV are shown on the back of the pancreas. e The appearance of the vascular anatomy after removal of the pancreatic head. AIPDA = Anterior inferior pancreatoduodenal artery; ASPDA = anterior superior pancreatoduodenal artery; CA = celiac artery; CBD = common bile duct; CHA = common hepatic artery; DPA = dorsal pancreatic artery; GCT = gastrocolic trunk; GDA = gastroduodenal artery; IMV = inferior mesenteric vein; J-1 = first branch of jejunal artery; LGA = left gastric artery; LNs = lymph nodes; PIPDA = posterior inferior pancreatoduodenal artery; PSPDA = posterior superior pancreatoduodenal artery; PV = portal vein; RGEA = right gastro-epiploic artery; SA = splenic artery; SMA = superior mesenteric artery; SMV = superior mesenteric vein; SV = splenic vein.

Fig. 1. Vascular anatomy (autopsied pancreas). a Gross appearance. b Horizontal section of the entire infantile pancreas on pancreatic polypeptide staining. The lines indicate the boundaries between the head, body, and tail. c Anterior PD arcade, SMA, and SMV are shown on the front of the pancreas. d Posterior PD arcade, SMA, SMV, SA, and SV are shown on the back of the pancreas. e The appearance of the vascular anatomy after removal of the pancreatic head. AIPDA = Anterior inferior pancreatoduodenal artery; ASPDA = anterior superior pancreatoduodenal artery; CA = celiac artery; CBD = common bile duct; CHA = common hepatic artery; DPA = dorsal pancreatic artery; GCT = gastrocolic trunk; GDA = gastroduodenal artery; IMV = inferior mesenteric vein; J-1 = first branch of jejunal artery; LGA = left gastric artery; LNs = lymph nodes; PIPDA = posterior inferior pancreatoduodenal artery; PSPDA = posterior superior pancreatoduodenal artery; PV = portal vein; RGEA = right gastro-epiploic artery; SA = splenic artery; SMA = superior mesenteric artery; SMV = superior mesenteric vein; SV = splenic vein.

from a common trunk). The inferior pair of PD arteries arises from the SMA, either separately or together with one of the proximal jejunal arteries. If the latter is accidentally ligated with an inferior PD artery, proximal segment jejunum ischemia may result and necessitate removal of more jejunum (e.g. in the course of Whipple's procedure) than is normally the case.

Both pairs of arcades supply the pancreatic head as well as the duodenal wall, and communicate freely with one another. Whereas the anterior PD arcade runs close to the inner curve of the duodenum, the posterior arcade passes posterior to the intrapancreatic portion of the common bile duct, maintaining a greater distance from the duodenum.

The rule, stated in most textbooks, that the close inter-relationship of the duodenum and pancreas regarding blood supply prevents removal of one without the other has been largely refuted in actual practice. Thus, duodenum-preserving total pancreatectomy has been performed successfully, providing that the duodenal branch of the GDA supplying the first portion of the duodenum and the first 3 cm of the anterior inferior pancreatoduodenal artery (AIPDA) supplying the fourth part of the duodenum are preserved [1]. However, the tenuous blood supply to the remaining duodenum in some cases, and oncological requirements in most other situations, make this procedure the exception that proves the rule.

Branches of the splenic artery (SA) supply the body and tail of the pancreas. These include multiple small branches to the upper border of the pancreas and the dorsal pancreatic artery. The latter arises from the proximal 2 cm of the SA, but it may also originate from the GDA or from an aberrant right hepatic artery. Apart from providing branches to the head and uncinate process, this artery sends off a large, but variable, inferior or transverse pancreatic artery to supply the body and tail of the pancreas from below. Its branches usually communicate with those pancreatic arteries giving off some epiploic branches to the greater omentum, including the left colic artery.

Veins

The veins draining the pancreas largely run parallel to the arteries. They drain into the portal vein (PV) or its two main tributaries, the superior mesenteric vein (SMV) and splenic vein (SV). The anterior superior pancreatoduodenal vein (ASPDV) drains into the right gastro-epiploic veins. The posterior superior pancreatoduodenal vein (PSPDV) is a constant tributary entering the PV from the right, just behind the upper border of the pancreas. As mentioned before, tributaries entering the anterior surface of the SMV or PV are very rare, but even so dissection between the pancreatic neck and the great veins must be done carefully. The inferior PD veins usually terminate as a common trunk draining into the SMV This trunk is short and, in passing under what appears to be just one anterior vein, the posterior branch is easily stopped by pressure from behind. The inferior mesenteric vein (IMV) enters the SV in 38% of subjects [2], in another one-third it drains into the splenomesenteric confluence, and in the remainder it terminates in the SMV The left gastric or coronary vein enters the PV in one-quarter of subjects [3]. In total pancreatectomy this vein must be preserved, since here it is the only vessel remaining to drain the proximal gastric segment. There are a number of rare abnormalities of the PV It may run in front of the duodenum and it may drain into the superior vena cava. Total anomalous pulmonary venous drainage may occur into the PV and present as a congenital cardiac defect [4]. Finally, congenital strictures of the PV can suggest tumor infiltration in patients whose tumors are not really inoperable.

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