Origin and Prevalence of the Retroportal Course of Hepatic Artery- A Retrospective Study

Abstract

Introduction: Anatomical variations of celiac and hepatic arteries are relatively common and impact operative time and technique. Intraoperative identification of the entire course of these vessels can be a challenge due to limited surgical field and increases the chance of iatrogenic injury. Aim: To evaluate and describe the origin and prevalence of retroportal course of hepatic arteries seen in Computed Tomography (CT) angiography in a large series of patients. Materials and Methods: The present retrospective study was conducted in the Department of Radiology, affiliated to a tertiary cancer centre in Southern India. CT angiogram done between January 2020 to June 2021 were included. Total of 326 abdominal CT angiograms were studied for celiac axis variations, variations in the origin and branching pattern of hepatic arteries, trajectory of the hepatic artery and its relation to portal vein. The branching pattern of celiac axis was analysed with adherence to the modified definition of Common Hepatic Artery (CHA) and it was classified as normal/variant/ambiguous. Based on the origin and branching pattern, hepatic arteries were divided into standard/replaced/accessory and classic/variant divisions, respectively. Variant divisions include trifurcation, duplicate or double hepatic artery and late origin of Gastro Duodenal Artery (GDA). Retroportal hepatic arteries under each variation was identified separately and their prevalence calculated. Confidence interval was calculated using simple proportionfrequency analysis open Epi version 3 software. Results: The age of the patients varies from 3 to 83 years (mean age 53.7 years). 207 (63.49%) cases were male and 119 (36.5%) cases were female. 262 (80.37%) cases had a normal celiac axis anatomy. Eight specific types of celiac axis variations were observed in 48 (14.72%) cases. In the remaining 16 (4.91%) cases, the celiac axis anatomy was ambiguous. CHA originated from the celiac axis, Superior Mesentric Artery (SMA) and aorta in 294 (90.18%), 10 (3.07%) and 6 (1.84%) cases respectively. Out of the 52 replaced Right Hepatic Artery (rRHA), 48 (14.72%), 3 (0.92%) and 1 (0.30%) cases had Right Hepatic Artery (RHA) replaced to the SMA, aorta and GDA, respectively. Except for the one rRHA from GDA, all of them had a retroportal course. Classic branching pattern of hepatic artery was seen in 154 (47.24%). Trifurcation, early branching of RHA and early branching of LHA were found in 49 (15.03%), 4 (1.22%) and 8 (2.45%) respectively. 63 (70%) cases of variations in hepatic artery origin, 15 (16.67%) cases of variations in hepatic artery branching and 12 (13.33%) cases of variations in celiac axis contributed to a total of 90 cases with retroportal hepatic artery. Prevalence of retroportal hepatic artery in the present study is 27.61% (confidence interval 22.82- 32.8) and the most common cause was aberrant RHA origin. Conclusion: Knowledge about the origin and prevalence of retroportal course of hepatic artery will help the surgeon to approach it systematically. Preoperative knowledge of the variations in origin and branching patterns and its influence on the trajectory will help in a better intraoperative identification of these variant vessels.