[Hepatic arterial vascular anatomy and its variants]

We investigated the frequency of anatomical variants of the hepatic artery, which can influence interventional angiographic procedures.

We reviewed 150 consecutive angiograms performed for the treatment of primary (112) or metastatic (38) liver tumors and evaluated the frequency of anatomical variants of the hepatic artery based on the classification proposed by Michels in 1955, which describes 10 variants. The so-called typical anatomy, which is in fact only found in 55% of cases, is indicated as type I.

The typical anatomy (type I variant) was seen in 78 patients (52%) and variants were seen in the other 72 (48%). We found 15 type II variants (10%), 23 type III (15.5%), 1 type IV and 1 type V (0.6%), 3 type VI (2%), 1 type VII (0.6%) and finally 6 type IX (4%). There were no type VIII or X variants, but in 22 patients (14.7%) vascular anatomy did not fit Michaels' classification.

In our series the typical hepatic artery anatomy was found in 52%, which is in agreement with Michels' findings, while the frequency of the individual anatomical variants differed. Not all of the variants reported by Michels were seen in our series and we found 22 patients with different variants. Disagreement might be due to the fact that Michels' was an autoptic series while our patients were cancer patients only and thus variability could be at least partly accounted for by neoplastic neovascularization. We believe that thourough knowledge of the anatomical variants of the hepatic artery is fundamental to angiographic practice, in particular for interventional procedures, because such variants can influence the choice of vascular technique and of materials.