Right hepatic artery traveling anteriorly to the common bile duct
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- Honma, S., Matsuda, W. & Kudo, M. Anat Sci Int (2013) 88: 93. doi:10.1007/s12565-012-0134-1
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The topographic relationship between arteries and hepatobiliary ducts can be crucial during cholecystectomy. We observed the right hepatic artery traveling a rare route in a 91-year-old male. The common hepatic artery gave off the left hepatic, the right gastric, the gastroduodenal, and the right hepatic arteries consecutively without forming the proper hepatic artery. The right hepatic artery crossed the common bile duct anteriorly, ascended on the right side of the duct, passed the cystic duct posteriorly, and entered the right lobe of the liver. The so-called 9 o’clock artery running on the right side of the common hepatic and common biliary is reasonably speculated to be the aberrant right hepatic artery as presently shown. Developmental and clinical issues are discussed.
KeywordsCommon bile ductCystic arteryCystic ductPosterior superior pancreaticoduodenal arteryRight hepatic artery
Accessory left gastric artery
Common bile duct
Common hepatic artery
Dorsal pancreatic artery
Inferior phrenic artery
Left gastric artery
Left hepatic artery
Posterior superior pancreaticoduodenal artery
Right gastric artery
Right hepatic artery
Right portal vein
Superior mesenteric artery
The right (RHA) and left (LHA) hepatic arteries usually divide from the proper hepatic artery, which ascends on the left side of the common bile duct (CBD). The RHA usually crosses posterior to the common hepatic duct (CHD) to enter the cystic triangle of Calot (Michels 1955; Skandalakis 2004). According to Michels (1955), who classified the hepatic arteries into ten types based on the origin, the course and the supplying lobes, such a pattern is found only 55 % of 200 cases. Although Michels’ classification has been used widely in describing the branching of the hepatic artery (Covey et al. 2002; Saba and Mallarini 2011), the topographic relationship with the arteries and the ducts, the CBD and the CHD, has not been a matter of concern.
According to Skandalakis (2004), the most obvious danger in biliary tract surgery is hemorrhage from the large arteries lying anterior to the biliary tract such as the posterior superior pancreaticoduodenal artery (PSPdA) and the gastroduodenal artery (GdA). The present paper reports a case in which the RHA arose directly from the common hepatic artery (CHA) and crossed the CBD anteriorly. While anatomical variation has been well reported in hepatic vasculature, the present study focuses on the position of the RHA with the CBD.
In the gross anatomy of arterial variations, some branches, which can be found even in the normal cases, are considered to participate partly in forming the variant artery. Such arterial branches are similar in origin and course to the variant artery (Aizawa et al. 1996; Honma et al. 2008; Kawai et al. 2008). In the present case, we paid attention to the PSPdA because it travels anteriorly to the CBD as well as the present RHA.
To examine the intrahepatic distribution of the RHA, the parenchyma of the right lobe was removed and the Glissonian sheaths were opened (Fig. 1d). After entering the porta hepatis, the RHA passed over the right PV, divided into the anterior and the posterior branches, and supplied the right and caudate lobes of the liver. The anterior branch supplied segments 5 and 8 of Couinaud (Skandalakis 2004); the posterior branch supplied segments 6 and 7. Three small branches deriving from the posterior branch were found to enter the caudate lobe, i.e., segment 1 of Couinaud (not depicted).
The incidence of the RHA and the LHA arising separately from the CHA without forming the proper hepatic artery has been stated as below 4 % in previous reports: none of 96 cases (Suzuki 1982), <2 % (Lippert and Pabst 1985), 4 of 148 cases (2.7 %) (Weiglein 1996), 9 of 250 cases (3.6 %) (Song et al. 2006), and 22 of 600 cases (3.7 %) (Covey et al. 2002). Weiglein (1996) depicted the topographic relationship between the separately originated RHA and the CBD, and all four RHA passed anteriorly to the CBD, as we presently observed.
Weiglein (1996) also reported the RHA from the proper hepatic artery traveling anteriorly to the CBD in 2 of 148 cases (1.4 %); Suzuki (1982) reported it in 9 of 96 cases (9.4 %). Hence, traveling of the RHA from the proper hepatic artery anteriorly to the CBD may not be so rare.
The present results demonstrate that the RHA arose from the GDA to give the PSPdA, ascended on the right side of the CBD, gave off the CA and terminated in the right lobe of the liver. The hepatic artery running the right side of the CBD in adult reminds us of the accessory right hepatic artery of Adachi (1928), although the accessory right hepatic artery travels posterior to the PV rather than anterior. Parke et al. (1963) described large anastomotic channels from the PSPdA to the RHA in 2 fetuses of 58 specimens. After crossing the CBD anteriorly, an anastomotic channel from the PSPdA passes under the cystic duct to connect the RHA. The channel supplies the branches to the ducts and gives the CA in Calot’s triangle. What allows this aberrant formation in adult is a matter of discussion.
Northover and Terblanche (1979) studied arteries supplying the CHD and the upper CBD in adults. The rates of origin are 26.9 % from the PSPdA, 9.9 % from the GdA, 25.5 % from RHA and 7.5 % from the CA. Besides these direct supplies, a pair of axially ascending arteries existed in all 21 bodies. They run bilaterally to the CBD and the CHD supplying the walls. The right axial artery coursed posterior to the cystic duct. The authors called the right and the left axial artery the 9 o’clock artery and the 3 o’clock artery, respectively.
According to Northover and Terblanche (1979), the 9 o’clock artery is said to be identical with the anastomotic channels of Parke et al. (1963). It is postulated that the 9 o’clock artery might have changed the normal arterial routes via the proper hepatic artery during development. Given the fact that the 9 o’clock artery gives off the PSPdA proximally and the CA distally, the topographic relationship is very similar to that observed in the present case.
Strasberg and Helton (2011) have stated that, if the extrahepatic biliary ducts are intact, the right lobe of the liver can escape from ischemia in surgeries with occlusion of the RHA. The authors explain this by two arterial shunts: the hilar shunt from the LHA and/or the 9 o’clock artery supply enough blood flow. In patients with a large RHA running on the right side of the CBD, there may be more chance of hepatic ischemia than in those with normal RHA.
In studying hepatic angiography, Song et al. (2006) stated that PSPdA divided from the proper hepatic or the RHA runs the risk of pancreatitis or duodenal mucosal injury caused by unintentional embolization during transcatheter therapy. Of 250 cases, PSPdAs were divided from the proper hepatic artery in 10 cases; PSPdAs were originated in the RHA separating from the GdA in 7. Such anatomical variation of the hepatic artery should be noted in order to avoid possible complications.
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