Michels Type II Vessel Branching Pattern Variant of the Hepatic Pedicle

Michels type II vessel branching pattern variant of the hepatic pedicle Gabriel Gonzales, Anju Kannappan, An Doan, Steven Vo, Tyler Petree, Katherine Pumphrey, Claire Kirchhoff UNT Health Science Center Introduction: In the branching of the celiac trunk, the left hepatic artery arises from the common hepatic in 89% of cases. However, in 11% of cases the vessel may instead arise from the left gastric artery, an alternate branching pattern known as Michels Type II variation of hepatic arteries. This study looks into the prevalence of this particular variation in a UNT Health Science Center cadaver subset and its correlation with the statistics stated in the most recent literature. Methods: The cadavers in this study (n = 39)were provided through the University of North Texas Health Science Center Willed Body program. For dissection protocol, dissections of the abdominal area included removal of overlying tissues to expose the celiac trunk. Literature review was performed utilizing PubMed. Results: Of the 39 cadavers observed, only 31 were examined due to 8 having undergone complete liver removal. The prevalence of the left hepatic artery branching off of the left gastric artery was 12.9%. The sample frequency of the Michels Type II variation correlated well with the previous findings, where 11% of people exhibited this variation. In addition, one of the cadavers with the variant branching pattern exhibited an additional variation where the cystic artery pierced the common bile duct. This was not observed in the other cadavers. Conclusion: Previous research has revealed a wide range of variations in the branching patterns of the liver vasculature. The Michels classification system was established to serve as a standard nomenclature. The variation of interest, with the left hepatic artery branching from the left gastric artery, is an example of a Michels Class II variant. Similar to prior results, a prevalence of approximately 12.9% was found within the sample of hepatic pedicles evaluated. In addition to this finding, a unique arterial branching pattern where the cystic artery pierces the common bile duct was noted. This finding was present in a single cadaver. Clinically, variants with persistently reported high prevalence such as these should be screened to help prevent serious complications during surgical procedures involving these vessels, such as left gastric artery ligation and liver removal. The persistently reported high prevalence for the Michels type II variant exemplifies the need for such pre-operative screening.