|Year : 2015 | Volume
| Issue : 1 | Page : 38-40
Atypical origin of cystic artery from superior mesenteric artery and untimely termination of common hepatic artery: Concurrent arterial variation in the supra-colic compartment
Jyothsna Patil, Naveen Kumar, Ravindra S Swamy, Anitha Guru, Satheesha B Nayak, Mohandas K. G. Rao
Department of Anatomy, Melaka Manipal Medical College, (Manipal Campus), Manipal University, Manipal, Karnataka, India
|Date of Web Publication||26-Feb-2015|
Department of Anatomy, Melaka Manipal Medical College (Manipal Campus), Manipal University, Manipal - 576 104, Karnataka
Secure laparoscopic cholecystectomy operation requires a sound anatomical knowledge of cystic artery (CA) and all possible variations involving it. Very rarely the CA arises from an extra territorial source of celiac axis. Since CA is to be ligated always during cholecystectomy, its variant origin, course and position in the Calot's triangle should be carefully noted. We report here a concurrent arterial variation showing rare origin of CA from superior mesenteric artery and trifurcation of common hepatic artery into right and left hepatic artery together with gastro duodenal artery just above the proximal part of the duodenum. Among the branches of celiac trunk, variant morphology of its common hepatic branch is reported to be rare. Ample knowledge of multiple arterial variations in the supracolic compartment of the abdominal cavity warrants the clinical attention. Overlooking such variations might result in iatrogenic injury to the vessels leading to fatal haemorrhage during surgical approaches.
Keywords: Common hepatic artery, cystic artery, superior mesenteric artery, trifurcation
|How to cite this article:|
Patil J, Kumar N, Swamy RS, Guru A, Nayak SB, Rao MK. Atypical origin of cystic artery from superior mesenteric artery and untimely termination of common hepatic artery: Concurrent arterial variation in the supra-colic compartment. Sahel Med J 2015;18:38-40
|How to cite this URL:|
Patil J, Kumar N, Swamy RS, Guru A, Nayak SB, Rao MK. Atypical origin of cystic artery from superior mesenteric artery and untimely termination of common hepatic artery: Concurrent arterial variation in the supra-colic compartment. Sahel Med J [serial online] 2015 [cited 2019 Dec 15];18:38-40. Available from: http://www.smjonline.org/text.asp?2015/18/1/38/152157
| Introduction|| |
Celiac trunk (CT) is the shortest ventral branch of the abdominal aorta. It is the artery of the foregut given off at the level of T12 and L1 vertebrae. It is about 1.5 cm long with the normal trifurcating branching pattern giving rise to common hepatic, splenic and left gastric arteries. The common hepatic artery (CHA) continues as hepatic artery proper distal to the origin of gastro-duodenal branch and terminate as right hepatic artery (RHA) and left hepatic artery (LHA) at porta hepatis. The right hepatic branch (HB) gives off cystic branch to supply the gall bladder (GB) and cystic duct (CD). Among the branches of CT, variations of CHA are reported to be uncommon.
The main arterial supply to the GB is derived from the cystic artery (CA) which normally arises as the cystic branch of RHA given off in the Calot's triangle. This typical pattern of blood supply to the GB occurs in 72% of normal individuals.  Other origins of CA might be from LHA, hepatic artery proper, and common hepatic arteries. These variant origins of CA however, are either from CT itself or through its branches. Very rarely, the CA stems from other arterial basis rather than the CT. Reporting such a rare variant origin of the artery with its clinical implications makes it clinically relevant. The course of the CA is highly unpredictable. In about 5.5% of cases it may not be found in Calot's triangle, inspite of being the main content of the triangle. 
The high risk of bleeding of injured CA during laparoscopic cholecystectomy often leads to open surgery. This in turn jeopardizes the normal function of extra-hepatic biliary apparatus and or its neighboring viscera. 
The variant pattern of vascular morphology of hepatic and CA can be explained by the background of its development. During an early embryonic period, the growth of liver and pancreas, differential growth of stomach and duodenum, the branching pattern of gastroduodenal and hepatibiliary vasculature are altered. This alteration results in the complexity of celiac axis and proximal part of the superior mesenteric arterial (SMA) pattern. Since the liver and GB develop from the hepatic diverticulum of the endodermal foregut, they normally receive arterial supply from the branches of CT. However, due to the complicated developmental scheme of hepatobiliary vasculature, contribution from SMA may, in addition, be established. 
| Case report|| |
During routine cadaveric dissection of supracolic compartment of the abdominal cavity of an elderly male aged about 60 years, we observed an unusually elongated CT, measuring about 3.5 cm in length but with normal trifurcated branching pattern. Its common HB was shorter than normal and trifurcated into the gastro duodenal artery (GDA), RHA and LHA [Figure 1]. The trifurcation occurred just above the commencement of first part of the duodenum. GDA assumed its normal course and it gave rise to right gastric branch to supply the stomach before its termination. The right and left HBs were much longer and ended at porta hepatis of the liver for the corresponding lobes of the liver. The right HB did not give the CA. Instead, the CA arose from SMA, coursed upwards obliquely towards right, deep to portal vein and common bile duct. Near the neck of the GB, it terminated by dividing into two branches to supply the GB and CD [Figure 2].
|Figure 1: Pattern of termination of common hepatic artery (CHA) into gastro duodenal (GDA), right hepatic (RHA) and left hepatic (LHA) arteries and origin of cystic artery (CA) from superior mesenteric artery. PV: Portal vein, CBD: Common bile duct. GB: Gall bladder, CD: Cystic duct, LGA: Left gastric artery, SA: Splenic artery. CT: Celiac trunk|
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|Figure 2: Closer view of variant branching pattern of common hepatic artery (CHA) into right and left hepatic branches (HB) and gastro duodenal artery (GDA), and distribution of cystic artery (CA) to gall bladder (GB) and cystic duct (CD). LGA: Left gastric artery, CT: Celiac trunk, CBD: Common bile duct, PV: Portal vein|
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| Discussion|| |
The variance in origin of the branches of CT is well documented. Normal trifurcation pattern of CT is observed in only 89.8% of cases.  Among the branches of CT, the variations of CHA are comparatively rare.  Its incidence is reported to be 3.7%.  Detailed variations of hepatic artery and its unusual branching patterns have been reported by Satheesha et al.  Thorough knowledge of its variations is important in therapeutic embolization of the hepatic artery.
CA is known to show high degree of variability both in its origin confined to celiac axis and course to the GB. However, reports on its origin from arterial source deviating from CT are very rare. Katada et al., in their study reported 2 cases of variant origin of CA from SMA as observed by angiography and CT. 
The overall incidence of CA arising from SMA is reported to be 0.2%.  In a study on anatomical variations of CA done by Mlakar et al., observed that the prevalence of double cystic arteries was 14%. Furthermore they observed that irrespective of the presence of the number of cystic arteries, they mostly originate from RHA.  A common trunk of accessory hepatic artery and CA originating from SMA has been reported by Shetty et al. 
Based on laparoscopic observations, Ding et al., classified the variant origin of cystic arteries into 3 groups. Group I consists of all possible variations within the Calot's triangle, whereas variations outside the Calot's triangle were categorized in Group II including its origin from variant hepatic artery. Group III also named as the compound group included the combined features of groups I and II. However, there was no mention about the variant origin of CA directly from SMA.  Therefore, we suggest an additional group for this type of abnormal origin deviating from its normal territorial source of CT.
Precise recognition of the origin and course of CA is important during laparoscopic cholecystectomy operations to prevent uncontrolled arterial bleeding which may result in increased risk of bile duct damage.  Very often, locating the posterior branch of the CA may not be easily appreciated which could result in bleeding during surgical procedures in the Calot's triangle. The CA also gives branches to CD which are usually smaller and their identification makes it clinically important in laparoscopic cholecystectomy. 
| Clinical importance|| |
Detailed knowledge of arterial supply to extra hepatic biliary system helps in minimizing iatrogenic bleeding which may produce increased risk of intra-operative lesions to the biliary structures.  This knowledge is also important for interventional radiologists in routine clinical practice.
Concurrent arterial variation reported herewith (untimely termination of CHA and the rare variation of CA arising from SMA) may perhaps help the surgeons to minimize the incidence of vascular accidents during surgical approaches in the supracolic compartment of the abdominal cavity.
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[Figure 1], [Figure 2]