Surgical anatomy of the pancreas for limited resection

Transcription

1 J Hepatobiliary Pancreat Surg (2000) 7: Surgical anatomy of the pancreas for limited resection Wataru Kimura First Department of Surgery, Yamagata University School of Medicine, Iida-Nishi, Yamagata City, Yamagata , Japan Abstract The fusion fascia of the head of the pancreas is called the fusion fascia of Treitz and that of the body and tail of the pancreas is termed the fusion fascia of Toldt. The fusion fascia is histologically composed of a loose connective tissue membrane. All of the important pancreaticoduodenal arcades of arteries and veins are situated on this membrane, i.e., between this membrane and the pancreatic parenchyma. The topography of the head of the pancreas shows that, after departing from the gastroducodenal artery, the anterior superior pancreaticoduodenal artery runs toward a point 1.5 cm below the papilla of Vater, then turns to the posterior aspect of the pancreas to join the anterior inferior pancreaticoduodenal artery. For preserving the duodenum, the artery toward the papilla is very important. The artery toward the papilla of Vater runs along the right side of the common bile duct after departing from the posterior superior pancreaticoduodenal artery. The gastrocolic trunk of Henle has been reported to be found in about 60% of individuals. It is possible that the gastroepiploic vein and anterior superior pancreaticoduodenal vein (ASPDV) can be divided at pancreaticoduodenectomy, with preservation of the superior right colic vein, if this area is free of carcinoma. The ASPDV and anterior inferior pancreaticoduodenal vein form an arcade on the anterior surface of the pancreas. However, arcade formation was not found between the posterior superior pancreaticoduodenal vein and posterior inferior pancreaticoduodenal vein in many of the individuals examined. The vein joined by the inferior mesenteric vein was also investigated. Key words Fusion fascia Topography of the head of the pancreas Artery toward the papilla of Vater Gastrocolic trunk of Henle Offprint requests to: W. Kimura Received: July 3, 2000 / Accepted: August 8, 2000 Introduction The anatomy of the pancreas has been a longstanding topic of study in anatomy departments worldwide, and many reports on the anatomy of the pancreas have been published. Here, the surgical anatomy, as well as the results of our anatomical investigation of the pancreas, are reviewed. Anatomical descriptions, which are useful not only for ordinary pancreaticoduodenectomy and distal pancreatectomy but also for limited resection of the pancreas for low-grade malignancies such as mucinproducing tumor or cystic lesions of the pancreas, are also provided. Fusion fascia The fusion fascia of the head of the pancreas in an autopsy subject is shown in Fig. 1. This fascia is composed of a loose connective tissue membrane. With Kocher s maneuver, this fascia adheres to the pancreatic parenchymal side, but not to the vena caval side. All of the important pancreaticoduodenal arcades of arteries and veins are situated on this membrane, i.e., between this membrane and the pancreatic parenchyma. 1 The composition of this membrane has already been investigated in detail. 2 Briefly, the pancreas develops during the fourth to seventh weeks of fetal life. At first, the pancreas is divided into the two buds of the ventral and dorsal anlage (Fig. 2a). The ventral anlage of the pancreas moves around the duodenum until it comes in contact with the dorsal bud (Fig. 2b). The membrane of the ventral bud and that of the inferior vena cava and abdominal aorta are fused (Fig. 2c). The name fusion fascia reflects this fusion. The fusion fascia of the head of the pancreas is called the fusion fascia of Treitz and that of the body and tail of the pancreas is the fusion fascia of Toldt. Accordingly, the fusion fascia behind

2 474 W. Kimura: Surgical anatomy of pancreas for limited resection the ascending colon is called the right Toldt fusion fascia and that behind the descending colon is the left Toldt fusion fascia. Figure 3 shows the schema of a sagittal section through the neck of the pancreas 2 with the fusion fascia indicated by the dotted line. The superior mesenteric artery (SMA) penetrates the fusion fascia, just after it originates from the abdominal aorta, running to the pancreatic side. A posterior view of the head of the pancreas in an autopsy subject is shown in Fig. 4. This is the surface that is ablated by Kocher mobilization. The probe is inserted into the portal vein. The cut end of the SMA is also shown, which was cut almost at the radix to the aorta. Figure 4, like the schema in Fig. 3, shows that the SMA penetrates the fusion fascia, just after it originates from the abdominal aorta. Figure 4 also shows that the pancreatic parenchyma, arcades of the arteries and veins, pancreatic neural plexus, and SMA are all situated on the abdominal side of this fusion fascia. The fusion fascia of Treitz is con- Fig. 1. Fusion fascia of the head of the pancreas in an autopsy subject. PIPD, Posterior inferior pancreaticoduodenal artery; AIPD, anterior inferior pancreaticoduodenal artery; SMV superior mesenteric vein; SMA, superior mesenteric artery Fig. 3. Sagittal section through the neck of the pancreas. The fusion fascia is indicated by the dotted line. MCA, Middle colic artery; Lt., left. (From reference 2, with permission) a,b c Fig. 2a c. Rotation of the pancreas. a Primitive relation of the dorsal and ventral anlage of the pancreas. b Rotation of the ventral anlage of the pancreas. c Final retroperitoneal position. The fusion fascia of the head of the pancreas is called the fusion fascia of Treitz and that of the body and tail of the pancreas is the fusion fascia of Toldt. Inf. Inferior. (From reference 2, with permission)

3 W. Kimura: Surgical anatomy of pancreas for limited resection 475 a b PSPDV PSPDV c Fig. 4a d. Posterior view of the head of the pancreas. a,b The posterior surface of the pancreas is covered with fusion fascia. c,d When this connective tissue membrane is removed, the posterior superior pancreaticoduodenal vein (PSPDV) is revealed. PV, Portal vein; CBD, common bile duct d nected to the fusion fascia of Toldt in the back of the pancreas. When the fusion fascia of Treitz is ablated from the parenchyma of the pancreas, an important pancreaticoduodenal vessel, the posterior superior pancreaticoduodenal vein (PSPDV), is revealed. This vein departs from the portal vein and runs behind the common bile duct toward the papilla of Vater (Fig. 4). Figure 5 shows pancreaticoduodenal vessels, such as the anterior inferior pancreaticoduodenal artery (AIPD) and posterior inferior pancreaticoduodenal artery (PIPD), and the fusion fascia of Treitz after removal of the head of the pancreas. Figures 4 and 5 show that removal of the head of the pancreas is possible while preserving the vascular arcades and their branches to the duodenum, the bile duct and the papilla of Vater. Pancreaticoduodenectomy is shown in Fig. 6. A cannula is inserted into the main pancreatic duct of the cut end of the pancreas. Near the SMA, a thread is inserted Fig. 5. The pancreaticoduodenal vessels and the fusion fascia of Treitz after removal of the head of the pancreas in an autopsy subject. ASPD, Anterior superior pancreaticoduodenal artery; GDA, gastroduodenal artery; PSPD, posterior superior pancreaticoduodenal artery; PD, pancreatic duct

4 476 W. Kimura: Surgical anatomy of pancreas for limited resection a b Fig. 6a,b. Pancreaticoduodenectomy. A thread is inserted into the second part of the pancreatic neural plexus to ligate it. b The thread penetrates the fusion fascia (arrowhead) a Fig. 7a,b. At distal pancreatectomy with preservation of both the spleen and splenic artery and vein, the pancreatic vein should be revealed by longitudinal division of the fusion fascia of Toldt b into the second part of the pancreatic neural plexus to ligate it. When we look at the posterior aspect of the pancreas, the pancreatic parenchyma is covered with the fusion fascia and the thread penetrates the fascia. Thus, when the neural plexus is divided at pancreaticoduodenectomy, the fusion fascia is also divided. In distal pancreatectomy with preservation of both the spleen and splenic artery and vein, 3 the pancreatic vein should be revealed by longitudinal division of the fusion fascia of Toldt, which is situated above both the posterior aspect of the pancreatic parenchyma and the splenic vein (Fig. 7a,b). Tiny venous branches toward the pancreatic parenchyma should be carefully ligated and cut after this procedure. Histological findings of the fusion fascia and vessels are shown in Fig. 8. The fusion fascia is composed of a loose connective tissue membrane. The vessels are histologically situated between the fusion fascia and parenchyma of the pancreas. Fig. 8. Histological findings of the fusion fascia and vessels. H&E, 40

5 W. Kimura: Surgical anatomy of pancreas for limited resection 477 Arteries of the pancreas The topography of the head of the pancreas is shown in Fig. 9. We previously found arcade formation between the anterior superior pancreaticoduodenal artery (ASPD) and the AIPD in all of 40 autopsied subjects. 1 After departing from the gastroduodenal artery, the ASPD runs toward a point 1.5 cm below the papilla of Vater, then turns to the posterior aspect of the pancreas to join the AIPD. Thus, in contrast to the prevailing belief, the AIPD was found on the posterior surface of the pancreas (Fig. 10) in all of the subjects we investigated. Although some authors show the AIPD on the anterior surface of the pancreas in video sessions, we believe that the above findings may apply to almost all individuals. In 88% of the subjects, an arcade was found Fig. 9. Schema of the topography of the head of the pancreas, showing the arteries and common bile duct, GEA, Gastroepiploic artery; GDA, gastroduodenal artery; acc., accesory; SV, splenic vein; IMV, inferior mesenteric; IPD, inferior pancreaticoduodenal artery; J1, first jejunal artery (From reference 1, with permission) between the posterior superior pancreaticoduodenal artery (PSPD) and the PIPD. Generally, it was easy to dissect the pancreas from the duodenum because of the loose connection. Near the accessory papilla, however, dissection of the vessels was difficult, and pancreatic parenchyma was sometimes found in the wall of the duodenum. Dissection of the pancreas from the common bile duct and identification of the main pancreatic duct at the junction with the terminal portion of the bile duct were straightforward in all subjects. For preserving the duodenum, the artery toward the papilla of Vater is very important. 4 The artery toward the papilla of Vater runs along the right side of the common bile duct after departing from the PSPD. Angiography which demonstrates the artery toward the papilla of Vater is shown in Fig. 11. No other such large artery was found toward the papilla, so it seems that this artery is very important for the blood supply of the papilla of Vater, the lower common bile duct, and second part of the duodenum. If this artery is injured, necrosis of these organs may occur, which would necessitate abandoning a limited operation. Chronic papillitis could occur in the future, which could impair the function of the papilla. Surgeons should be careful not to injure this artery when removing this part of the pancreas. Variations in the inferior pancreaticoduodenal artery (IPDA) have been described in detail by Murakami and co-workers. 5 The IPDA was found in 80% of 214 autopsy subjects; a common artery composed of the IPDA and the first jejunal artery (J1) arose from the SMA in 56% and the IPDA arose independently from the SMA in 22% of subjects. Fig. 10. Schema of the anterior superior (ASPD) and anterior inferior pancreaticoduodenal arteries (AIPD). (From reference 1, with permission) Fig. 11. Angiography which demonstrates the artery toward the papilla of Vater (arrows)

6 478 W. Kimura: Surgical anatomy of pancreas for limited resection SRC Fig. 12. Variations and their incidence in the gastrocolic trunk of Henle. SRC, Superior right colic vein; GEV, gastroepiploic vein; ASPDV, anterior superior pancreaticoduodenal vein. (From reference 7, with permission) Fig. 14. Schema of the topography of the head of the pancreas, showing the arteries and common bile duct. PIPDV, Posterior inferior pancreaticoduodenal vein; GCT, gastrocolic trunk; (From reference 1, with permission) Fig. 13. Arcade formation of the ASPDV and anterior inferior pancreaticoduodenal vein (AIPDV; arrowheads) Veins of the pancreas With regard to the gastrocolic trunk of Henle, this area is complicated by fusion of the omentum and mesotransverse colon. Therefore, surgeons and their first assistants should know the precise anatomy of this area, lest they tear the tissue and fragile veins with excessive tension, followed by bleeding, which might make operation more difficult. The gastrocolic trunk is called the gastrocolic trunk of Henle or Henle s trunk, because Henle reported a common trunk of the superior right colic vein and the right gastroepiploic vein in In 1964, Gillot et al. 7 reported that a gastrocolic trunk was found in about 60% of 78 subjects (Fig. 12). In 1912, Descomps and De Lalaubie 8 reported that the anterior superior pancreaticoduodenal vein (ASPDV) may join the gastrocolic trunk in some subjects. At pancreaticoduodenectomy, division of the right gastroepiploic vein (GEV) and the ASPDV with preservation of the superior right colic Fig. 15. Variations in the IMV, SV, and SMV. A, IMV joining SV; B, IMV joining confluence of SV and SMV; C, IMV Joining SMV Fig. 16. Relation of the tail of the pancreas to the splenic porta. (From reference 2, with permission)

7 W. Kimura: Surgical anatomy of pancreas for limited resection 479 vein, to prevent congestion, is possible if this area is free of carcinoma. According to Gillot et al. 7 the area of the portal vein around the radix of the gastrocolic trunk of Henle is called Henle s trunk area. The part of the portal vein from the radix of the ileocolic vein and Henle s trunk area is called the surgical trunk, and this should be revealed at lymph node dissection in right hemicolectomy for carcinoma of either the ascending colon or the cecum. The ASPDV and the anterior inferior pancreaticoduodenal vein (AIPDV) form an arcade on the anterior surface of the pancreas (Fig. 13). However, arcade formation was not found between the PSPDV and the posterior inferior pancreaticoduodenal vein (PIPDV) (Fig. 14), in contrast to many illustrations of pancreatic anatomy in textbooks. Sakamoto et al. 9 reported findings similar to ours with regard to these veins. Takamuro et al. 10 reported that the PSPDV and PIPDV sometimes formed arcades and at other times did not. When the PSPDV is large and the connective vein with the PIPDV is small, the PSPDV may have previously been called the dorsal pancreatic vein. We believe that the PSPDV is larger than the connecting vein in most subjects, according to our investigation of autopsy subjects. After departing from the portal vein, the PSPDV runs across the posterior surface of the common bile duct, and fans out and irrigates the second part of the duodenum near the papilla of Vater. The PIPDV departs from the first jejunal vein (J1V), and runs horizontally behind the SMV toward the right on the fusion fascia of Treitz. An investigation of which vein is joined by the inferior mesenteric vein (IMV), in 38 autopsy subjects, revealed that the IMV joined the splenic vein (SV) in 34% of the subjects, the superior mesenteric vein (SMV) in 42%, and the confluence of the SV and SMV in 24% (Fig. 15). These incidences are almost the same as those reported in Europe 11 and the United States. 12 In distal pancreatectomy with preservation of the spleen and splenic artery and vein, 3 the relationship between the tail of the pancreas and the splenic porta is important. According to Skandalakis et al., 2 the tail of the pancreas reaches the center of the hilus of the spleen in 50% of individuals, the upper part of the hilus in 8%, and the lower part of the hilus in 42% (Fig. 16). Acknowledgments. This work was supported in part by Grants-in-Aid for Scientific Research from the Ministry of Health and Welfare of Japan and the Pancreas Research Foundation of Japan. References 1. Kimura W, Nagai H (1995) Study of surgical anatomy for duodenum-preserving resection of the head of the pancreas. Ann Surg 221: Skandalakis JE, Skandalakis LJ, Colborn GL (1998) Congenital anomalies and variations of the pancreas and pancreatic and extrahepatic bile ducts. In: Beger HG, Warshaw AL, Buchler MW, Carr-Locke DL, Neoptolemos JP, Russell C, Sarr MG (eds) The pancreas, volume 1. Blackwell Science, London Edinburgh Malden Victoria Paris Berlin Tokyo, pp Kimura W, Inoue T, Futakawa N, Shinkai H, Han I, Muto T (1996) Spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein. Surgery 120: Kimura W, Morikane K, Futakawa N, Shinkai H, Han I, Inoue T, Muto T, Nagai H (1996) A new method of duodenumpreserving subtotal resection of the head of the pancreas based on the surgical anatomy. Hepatogastroenterology 43: Murakami G, Hirata K, Takamuro T, Mukaiya M, Hata F, Kitagawa S (1999) Vascular anatomy of the pancreaticoduodenal region: a review. J Hepatobiliary Pancreat Surg 6: Henle J (1868) Handbuch der systematischen Anatomie des Menschen. Druck und Verlag von Friedrich Vieweg und Sohn, Braunschweig, pp 391 (cited by 7 Gillot et al. 7 ) 7. Gillot C, Hureau J, Aaron C, Martini R, Thaler G (1964) The superior mesenteric vein. J Int Coll Surg 41: Descomps P, De Lalaubie G (1912) Les veines mésentériques. J. de l Anat. et physiol. norm. et path. de l homme et des animaux. 48: (cited by Gillot et al. 7 ) 9. Sakamoto Y, Makuuchi M, Nagai M, Tanaka N, Nobori M (2000) Embryology and anatomy of the head of the pancreas. (in Japanese). Geka (Surgery) 62: Takamuro T, Oikawa I, Murakami G, Hirata K (1998) Venous drainage from the posterior aspect of the pancreatic head and duodenum. Okajimas Folia Anat Jpn 75: Douglas BE, Baggenstoss AH, Hollinshead WH (1950) The anatomy of the portal vein and its tributaries. Surg Gynecol Obstet 91: Barry P, Repolt A, Autssier AH (1968) Le confluent portal. Notes statistiques sur son mode de constitution. Bull Assoc Anat 141: