Cadaveric Study of Accessory/Aberrant Left Hepatic Artery From Left Gastric Artery - Embryological Basis & Its Clinical Significance

Keywords

Left Gastric Artery; Aberrant Left Hepatic Artery; Accessory Left Hepatic Artery; Embryological Basis; Clinicalsignificance.

Introduction

The Coeliac trunk is the first unpaired vessel of abdominal aorta, normally trifurcates into left gastric, splenic and common hepatic arteries. The common hepatic artery after its origin from Coeliac trunk divides into right and left branches to the respective lobes of the liver [1-3]. Variations in the hepatic arterial anatomy are common and knowledge about them plays a crucial role during hepatobiliary surgeries [4, 5]. The hepatic artery considered as aberrant is of two types, namely, ‘accessory’ and ‘replaced’. The aberrant is accessory hepatic when it is seen as additional to the one which is normally (usually) present. The aberrant is replacing hepatic when it is seen as substitute to the normal (usual) hepatic artery which is absent [6]. In about 12% of individuals it has been shown that the aberrant hepatic arterial variation as the right hepatic artery arising from superior mesentery artery and in about 25% of cases it has been shown that the left hepatic artery or accessory left hepatic artery to be arising from left gastric artery [7]. It has also been reported earlier about the incidence of accessory left hepatic artery to be arising from left gastric artery in about 6-8% of the specimens and at the same time the incidence of replaced left hepatic artery was also arising from left gastric artery itselfin about 8-10% of the specimens [8-10]. The aim of the present study is to observe the incidence of origin of aberrant left hepatic artery from the left gastric artery and to note its embryological basis & clinical significance.

Materials and Methods

Fifty (50) embalmed adult human cadavers of both the sexes were studied. The specimens were obtained from the Department of Anatomy, Sri Siddhartha Medical College, Bangalore. Abdomen was opened and dissected according to the Cunningham’s manual. The Coeliac trunk and its branches were located and cleaned. The common and hepatic artery proper and its branches going towards porta hepatics were also located and cleaned. The left gastric artery was identified and traced anticipating aberrant left hepatic artery. The observations noted were analyzed and compared with the previous studies.

Results

Study was conducted on 50 specimens, out of which four specimens (8%) showed the presence of aberrant left hepatic artery arising from left gastric artery. It was also observed that the aberrant left hepatic artery was accessory to the left hepatic artery (Figure 1 & 2). After its origin from the left gastric artery, the aberrant accessory left hepatic artery ascended upwards staying close to the lower end of esophagus within the layers of lesser omentum, later it entered the liver by passing through the porta hepatic. During its course it gave 3-4 branches to the lower end of esophagus. Rest of the 46 specimens showed the normal hepatic arterial pattern.

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Discussion

The arterial supply of liver shows anatomical variations and has been reported in about 25-50% population [11, 12, 3, 5]. The present study shows aberrant hepatic artery in four (8%) case. Studies have shown that the incidence of aberrant left hepatic artery arising from left gastric artery varies from 6.1-21% of cases [13-19, 5, 8]. Table 1.

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The lowest incidence of aberrant left hepatic artery arising from left gastric artery was 6.1% reported by Iezzi [14] and the highest incidence was reported by Urugel 21% [17]. The incidence in the present study was 8%.

Embryological basis

During fetal life, hepatic tissue is supplied by three embryonic hepatic arteries, namely, left hepatic, right hepatic and common hepatic arteries. There after regression occurs in relation to right and left hepatic arteries. Persistence of right and left hepatic arteries leads to the development of aberrant hepatic arteries [20-22].

For the normal development of any viscera there will be continuous synthesis of adequate quantities of signaling molecules and growth factors, which are produced by the mammalian cells. In case of any interference in the synthesis of signaling molecule and growth factor leads to development of visceral anomalies. In such cases if an artery fails to originate from the usual (normal) position being the only source of supply to the particular lobe, it is then called as replaced artery [23]. During gastrectomy and hiatal hernial repair surgical procedures the left hepatic artery arising from the left gastric artery frequently gets injured, hence the aberrant vessels must be kept in mind during surgical interventions. Having an accessory left hepatic artery contributes to the collateral arterial circulation in case of vascular occlusion in porta hepatis [24, 25].

In case of liver transplantation patients with the presence of accessory hepatic arteries calls for multiple vascular anastamosis to be done between donor and recipient vessels. If accessory vessels are not anastomosed properly it may lead to severe postoperative complications such as necrosis of liver parenchyma, acute liver failure and other fatal complications [26]. Studies have also shown that in presence of aberrant vessels can result in difficulty during catheter placement in case of chemoembolization and hepatic arterial infusion chemotherapy procedures [27]. Presence of aberrant hepatic arteries can prove to be fatal as there will be more chances of accidental ligation during surgeries done of liver tissue. Simultaneously presence of aberrant hepatic arteries can also lead to potential error in diagnosing angiographic procedures [28, 29]. Hence it is advisable to subject the patient to thorough preoperative procedures to reduce the fatal complications during hepatobiliary surgeries.

Conclusion

Presence of aberrant hepatic arteries, either as accessory or replacing is a common anomaly and it proves to be crucial in case of hepatobiliary surgeries as it may pose a threat of potential bleeding during surgical procedures. Hence a surgeon should be well equipped with the knowledge of aberrant hepatic arteries as it is also important during hepatectomy, gastric resection and liver transplantation surgeries.

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