The hepatic artery: a reminder of surgical anatomy

R.M. JONES and K.J. HARDY
Victorian Liver Transplant Unit, University of Melbourne Department of Surgery, Austin Campus, Melbourne 3084, Australia

Introduction

Materials

Results

Discussion

References

This study was carried out to document the anatomy of the hepatic artery with the purpose of reminding surgeons of the need for this essential knowledge in order to practice safe hepatobiliary surgery. Repeated surgical mistakes on patients referred to our unit prompted the study. One hundred and eighty consecutive livers procured for transplantation was studied, and the anatomy drawn immediately after dissection. The left hepatic artery arose from the left gastric artery in 15%, and either the splenic, gastroduodenal artery or the aorta in 4% of cases. The right hepatic artery arose from the superior mesenteric artery in 15%, the gastroduodenal, right gastric artery or aorta in 10% of cases. There was a major variation of the coeliac axis in 9% of cases studied. Overall, there was an abnormality in 43% of dissections: 48% were multiple and 27% had more than two vascular variations. A constant pattern of abnormalities occurred in the anatomy of the hepatic artery. Realisation of this vascular pattern should make identification of the anatomy easier. When there is one vascular variation, there is a high chance of there being multiple variations.

An intact hepatic artery is the gateway to successful hepatobiliary surgery. Introduction of laparoscopic cholecystectomy has stimulated a renewed interest in the anatomy of the hepatic artery.¹ Division or damage with subsequent thrombosis produces ischaemia of the liver or bile duct which can have devastating consequences for the patient. Surgeons undertaking hepatobiliary surgery must know their hepatic artery anatomy and be able to recognise the multiple variants for safe surgery and low morbidity. The anatomy of the hepatic artery, and its variants, has been described adequately in the literature starting with Haller in 1756 (coeliac axis variations), Tidemann in 1822 (multiple anomalies), Adachi in 1928 (28 subgroups) and classic analyses by Flint, (1923) and by Michels (1955).^2-6 A new emphasis was given to this anatomy by the introduction of liver transplantation.⁷ The arterial patterns are of importance in planning and performance of all surgical and radiological procedures in the upper abdomen.¹ However, surgical mistakes from failing to appreciate hepatic artery anatomy continue to be made with serious consequences to the patient, and with medico-legal implications. This article builds on a previous report, and re-emphasises the importance of identifying the anatomy and variations of the hepatic artery.⁴ This anatomy will become even more important as computerised surgery develops.

Between July 1989 and December 1997, 180 livers harvested from multi-organ donors by the Victorian Liver Transplant team for 180 recipients at the Austin Campus of the Austin and Repatriation Medical Centre, Melbourne, were evaluated. The age of the donors was from 5 to 72 years. Livers were harvested using the rapid technique, which involves an en bloc dissection after cold perfusion. The method was to visualise the splenic artery, left gastric artery and inferior vena cava and then cannulate the portal vein via the inferior mesenteric vein.

Preparation of the donor liver (‘backtable’ dissection) was performed by the same surgeon (KJH), and the anatomy drawn immediately after the dissection.

This had its origin from the common hepatic artery trunk in 144 instances (80%), from the left gastric artery in 27 instances (15%), the splenic artery in four (2%), the gastroduodenal in two (1%) and one each in the aorta, coeliac axis and superior mesenteric artery (Figure 1). The aberrant left hepatic artery ran in the lesser omentum, traversing forwards and medially. The origin from the gastroduodenal artery ran in the free edge of the lesser omentum, accompanying the right and middle when they also arise from this source.

Figure 1: Anatomical variations of the hepatic arteries, documented in donor livers

In the 27 instances when the left hepatic took origin from the left gastric artery there were 18 instances (70%) of other arterial anomalies. In three instances the anomalous origins were of small size, and not the only arterial supply to segments II and III.

Of 180 dissections, the right hepatic artery took origin from the main trunk of the common hepatic artery in 135 instances (75%), the superior mesenteric in 32 (18%), and gastroduodenal artery in 10 (6%); it arose from the right gastric artery or aorta in three instances (Figure 1).

These anomalous right hepatic vessels from the superior mesenteric and gastroduodenal arteries had a course to the right of the portal vein. None gave rise to a middle hepatic artery, which supplied segment IV. They were the sole supply of the right half of the liver, Couinaud segments V-VIII. In the 26 instances when the right hepatic artery arose from the superior mesenteric artery, there were other arterial anomalies present in 12 instances (46%).

In 103 consecutive dissections, the middle hepatic artery arose from the right or left hepatic arteries in 82 instances (80%), the gastroduodenal in nine, the superior mesenteric and splenic in two instances each, the left gastric and common hepatic arteries in one instance each and was not identified in six dissections.

There was a major variation of the coeliac axis in 15 instances (8%). The coeliac axis and the superior mesenteric artery had a common origin in three instances, and the coeliac axis was absent in two, with the common hepatic, splenic and left gastric arising from the aorta.

A number of other abnormalities were observed: the coeliac axis arising from the superior mesenteric artery, the common hepatic from the superior mesenteric with the splenic and left gastric vessels arising from the aorta. The left gastric artery arose from the splenic in two instances and the aorta in one, and the gastroduodenal artery arises from the coeliac axis and from the right hepatic artery in one instance, respectively.

Abnormalities were found in 43% of dissections: of these abnormalities 48% were multiple, and 27% had more than two anomalies.

This current study shows that there is a pattern to the variations of the hepatic artery, even though the possibilities of individual variations are myriad. When the right hepatic artery does not arise from the common hepatic artery or the common hepatic artery is absent, its origin is ‘picked-up’ from the aorta or any of the arteries on the right side of the aorta: superior mesenteric, gastroduodenal, right gastric or an artery normally to the left of the aorta if it deviates to the right of the aorta, such as the splenic artery. The right hepatic artery runs in the free edge of the lesser omentum, and does not supply the liver to the left of the falciform ligament.

The left hepatic artery has the same pattern, ‘picking-up’ an origin from the arteries to the left of the aorta: splenic artery, left gastric artery or left side of the aorta. The coeliac axis can arise with the superior mesenteric artery, and then the left hepatic artery traverses the tissues forwards and to the left half of the liver, and can be difficult to identify. This assessment was made because in our previous study of 70 consecutive dissections; the patterns of variations were the same as the next 110 consecutive dissections.⁸

This anatomic surgical report demonstrates an anomalous variation of the right or left hepatic arteries in nearly 50% of dissections. It demonstrates also that variations when present are often multiple; 46% of anomalous right hepatic arteries had more than one variation present, and 70% of anomalous left hepatic arteries had other variations. When there were variations, 27% had more than two variations. The observation of one variation, therefore, should make the surgeon vigilant for further variations in the dissection.

Initially, the most puzzling anomalies are those involving the coeliac axis. However, the diameter of the arteries that usually arise from the coeliac axis is large, and the hepatic artery, when located, is easy to dissect and define. However, an anomalous left hepatic artery and an anomalous right hepatic artery, in the absence of the coeliac axis, can be difficult to locate and follow. The right hepatic artery arising from the superior mesenteric artery is not a problem to dissect nor are those right hepatic arteries arising from the gastroduodenal artery. (This variant frequently is not recognised). The right hepatic artery arising from the aorta can be hard to identify, and may be divided during the donor operation. The left hepatic artery is smaller than the right hepatic artery and more difficult to identify in the ‘back-table’ dissection with anomalous origins other than from the left gastric artery. Sometimes these aberrant left hepatic arteries are very small, and their preservation value for the transplant can be questioned. In the heart-beating donor, the left hepatic artery is easy to identify in the lesser omentum.

Particular arterial anatomical problems arise in two circumstances in liver transplantation: when major arteries are divided in the donor procurement, and when anomalies are present with simultaneous liver and pancreas procurement. With pancreatic procurement, if there is an anomalous right hepatic artery it is absolutely essential for the liver surgeon that a cuff of splenic artery be preserved, for if there are multiple variations elsewhere the reconstruction of right hepatic artery to splenic artery may be the only one possible.

The patterns of abnormalities and variations were remarkably similar between the first 70 and second 110 donors, suggesting a relatively constant pattern of anatomical variation.

The advent of computerisation for an intelligent operating room for surgeons is closer. Using the ‘visible man’data set, a working prototype of informatic and micro-engineering tools have been developed.⁹ Anomalous hepatic arteries are included. Also in ‘virtual anatomy’, the simulated presence of anomalous hepatic arteries will allow the surgeon to practice laparoscopic cholecystectomy, liver resections or vascular recombination in transplantation and, thereby, avoid errors and patient morbidity.¹⁰

Correspondence: Professor R.M. Jones, Liver Transplant Unit, Austin Campus, Melbourne 3084 Victoria, Australia

SURGICAL TECHNIQUE

The hepatic artery: a reminder of surgical anatomy