IJCRR - Vol 06 Issue 17, September
Date of Publication: 11-Sep-2014
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STUDY OF ABERRANT LEFT HEPATIC ARTERY FROM LEFT GASTRIC ARTERY AND ITS CLINICAL IMPORTANCE
Author: Suman Tiwari, Roopashree R., Padmavathi G., Varalakshmi K. L., Sangeeta M
Abstract:Objectives: Variations of the hepatobiliary region are frequent and are of concern to the radiologists and gastroenterological surgeons. The variations reported in the literature are of several kinds such as accessory hepatic arteries, replaced hepatic arteries and additional branches. The present study describes the incidence of origin of aberrant left hepatic artery from left gastric artery and its clinical importance. Methods: 50 adult embalmed human cadavers of both the sexes were studied by dissection method at the Department of Anatomy, MVJ Medical College and other medical colleges in and around Bangalore. Results: In 4(8%) specimens, the aberrant left hepatic artery had its origin from left gastric artery. Out of the 4 specimens, the aberrant left hepatic branch was accessory in 3(6%) specimens and replaced in 1(2%) specimens. Conclusion: The knowledge about variations in the anatomy of subhepatic region is of immense significance to hepatobiliary surgeons since bleeding from aberrant vessels may increase the risk of intra-operative complications.
Keywords: Accessory left hepatic artery, Hepatobiliary surgery, Left gastric artery, Replaced left hepatic artery
The common hepatic artery, a branch from coeliac trunk divides into right and left branches to the hepatic lobes. Variations of hepatic arteries are common and surgically important. 1 Aberrant hepatic artery is of two types, replacing and accessory. An aberrant replacing hepatic artery is a substitute for the normal (usual) hepatic artery which is absent. An aberrant (a variable) accessory hepatic appears in addition to one that is normally (usually) present. 2 The most common aberrant hepatic arterial variations are right hepatic artery originating from the superior mesenteric artery (10–12% of individuals) and left hepatic artery or accessory left hepatic artery originating from the left gastric artery (25% of individuals). 3 Michaels 4 in his dissection of 200 cadavers has reported the incidence of accessory left hepatic artery from left gastric artery in 8% and replaced left hepatic artery from left gastric artery in 10% specimens. An aberrant left hepatic artery arising from left gastric artery either as an accessory or replacing the left hepatic artery is occasionally seen in patients with gastric cancer. Resection of this aberrant vessel which feeds a wide area of the liver, as a part of gastrectomy procedure may cause postoperative liver dysfunction.5 Present study is undertaken to know the incidence of origin of aberrant left hepatic artery from left gastric artery and its clinical importance.
MATERIALS AND METHODS
Fifty adult embalmed human cadavers from south Indian population were studied irrespective of their sex. The specimens were obtained from the Department of Anatomy, MVJ Medical College and other medical colleges in and around Bangalore. The gross dissection was done following the guidelines of Cunningham’s manual. The peritoneal cavity was opened and the anterior layer of peritoneum from the lesser omentum close to the lesser curvature of stomach was removed. The Coeliac trunk and its branches namely, left gastric, common hepatic and splenic arteries were identified and cleaned. The dense autonomic plexus from its branches was removed. The left gastric artery was traced till it curves posteriorly around the superior surface of omental bursa. The common and proper hepatic artery and its branches to the porta hepatis were exposed and cleaned. The aberrant left hepatic artery from left gastric artery if present was identified and cleaned. The data obtained was analyzed and compared with that of previous studies.
Out of the 50 specimens studied, the aberrant left hepatic artery arising from left gastric artery was seen in 4 (8%) specimens. The remaining 46 (92%) specimens did not show the presence of aberrant left hepatic artery. It was observed that out of the 4 specimens, the aberrant left hepatic artery was accessory in 3(6%) and replacing in 1(2%) specimen. The aberrant left hepatic artery was originating from the proximal one third of left gastric artery in 3(6%) specimens and from the middle one third in 1(2%) specimen. In all the specimens, an aberrant branch arose from the left gastric artery and entered the visceral surface of the left lobe of the liver at a site independent from the porta hepatis. In specimen no.9 (Fig 1), the Coeliac trunk branched into four arteries; Gastroduodenal, Left gastric, Right hepatic and Splenic arteries. The replaced left hepatic artery was arising from left gastric artery and entered the left lobe of the liver. In specimen no. 26 (Fig 2), the coeliac trunk divided into Common Hepatic, Splenic, Left gastric, Dorsal pancreatic and Left inferior phrenic arteries. An accessory left hepatic artery was seen arising from the left gastric artery. This artery passed from below upwards in the cranial part of the lesser omentum and entered the left lobe of liver through the fissure for ligamentum venosum. The rest of the course of left gastric artery was normal in all the specimens.
The incidence of aberrant left hepatic artery from left gastric artery varies from 6.1-21% in various studies 6-13 and is summarized in Table 1. The highest incidence of aberrant left hepatic artery from left gastric artery was reported by Urugel11 (21%) and the lowest by Iezzi 10(6.1%). In the present study, its incidence is 8% which is within the range. The embryological basis for the origin of aberrant left hepatic artery from left gastric artery is as follows: The primitive liver is supplied by 3 embryonic hepatic arteries namely, Left hepatic, Right hepatic and Common hepatic arteries. The Left and Right hepatic arteries undergo regression. If they persist, they lead to the development of aberrant hepatic arteries. Kulesza 14 has explained that there should be presence of sufficient quantities of signalling molecules and growth factors produced by the developing and migrating mammalian cells for the normal development of any viscera. In the event of an improper signalling and incorrect gradient, there may occur visceral anomalies. When an artery does not originate from an orthodox position, being the only supply to a particular lobe, it is called a replaced artery. The left hepatic artery arising from left gastric artery may be injured as it lies in the upper portion of the lesser omentum during mobilization of stomach in gastrectomy and hiatal hernia repair. So these aberrant vessels must be recognized, since even in gastrectomy because of gastric cancer it was shown that leaving the aberrant hepatic artery and the proximal left gastric artery has the same oncologic effect as complete ligation of the left gastric artery. Accessory left hepatic artery provides a source of collateral arterial circulation in cases of occlusion of the vessels in the porta hepatis. 1, 5 It is important that interventional radiologists who perform hepatic arterial embolisation be familiar with both common and rare hepatic arterial variants, because failure to recognize the presence of an aberrant vessel can result in incomplete embolisation of liver tumours. Familiarity with these variants can also help one avoid various surgical complications. The replaced left hepatic artery originating from left gastric artery must be identified and ligated before left hepatectomy is performed, because the major arterial branch to the left liver does not need to be found in the porta hepatis. The accessory hepatic artery provides an additional source of arterial blood to the left hepatic lobe and may be sacrificed without compromising the arterial supply to the left hepatic lobe. An accessory left hepatic artery needs to be occluded separately when controlling the inflow to the left hepatic lobe because this artery will not be occluded when the blood supply in the porta hepatis is occluded. Distinction between an accessory and a replaced artery is therefore important. Recognition of a replaced or an accessory artery is important so that the vessel can be ligated at the time of catheter placement to allow uniform perfusion of the hepatic parenchyma. 6, 8, 10 Accidental ligation of aberrant hepatic arteries may lead to liver necrosis and death. The role of the accessory arteries and the segments of the liver supplied should be considered during planning for liver surgery since these vessels are end arteries in most cases and injury would compromise liver supply, resulting in necrosis of the entire left hemiliver or some segments, commonly two and three. An aberrant hepatic artery may cause a potential error in the angiographic diagnosis of traumatic liver haematoma. So the aberrant hepatic vascularisation should be assessed preoperatively by invasive and non-invasive techniques to avoid fatal complications. 13, 15, 16
Aberrant left hepatic artery arising from left gastric artery is a common anomaly found in 8% of specimens. The knowledge of existence of aberrant hepatic arteries, either accessory or replacing, is important during hepatobiliary surgeries as they present potential bleeding risks and complicates the procedure. They also have importance in partial hepatectomy, gastric resection, operations performed near the gastro hepatic ligament, including esophagogastrectomy, gastric bypass, and antireflux procedures. Knowledge of variant hepatic arteries is of greatest importance in liver transplantation.
The authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors/editors/publishers of all those articles, journals and books from where the literature of this article has been reviewed and discussed. Authors are grateful to IJCRR editorial board members and IJCRR team of reviewers who have helped to bring quality to this manuscript.
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