Replaced Common Hepatic Artery Arising from the Superior Mesenteric Artery (Michel Type IX): A Cadaveric Case with Surgical Implications

Moultrie, GA

Background: Hepatic arterial anatomy demonstrates significant variability with important implications for hepatobiliary and pancreatic surgery. Although the common hepatic artery (CHA) classically arises from the celiac trunk, hepatic arterial variants are reported in up to 25% of individuals. A replaced CHA originating from the superior mesenteric artery (SMA), classified as Michel type IX anatomy, is considerably less common, with reported incidences ranging from approximately 1% to 4% in cadaveric and angiographic series. Recognition of such variants is essential to minimize intraoperative vascular injury and ischemic complications.

Objective: To describe a cadaveric case of a replaced CHA arising from the SMA and to examine its incidence and surgical relevance through focused review of the literature.

Methods: Routine cadaveric dissection was performed in a medical school gross anatomy laboratory. The abdominal aorta and its major branches were identified and traced to determine arterial origin and branching patterns. Photographic documentation was obtained in accordance with institutional guidelines. A targeted review of foundational and contemporary literature regarding hepatic arterial variation and surgical implications was conducted.

Results: A replaced CHA originating directly from the proximal SMA was identified. The vessel ascended toward the hepatoduodenal ligament and divided into the gastroduodenal and proper hepatic arteries while maintaining typical distal branching. The celiac trunk gave rise exclusively to the left gastric and splenic arteries without contributing to hepatic arterial inflow. Large surgical series confirm hepatic arterial variation in up to 25% of cases, while Michel type IX anatomy has been reported in approximately 1–4% of individuals. Contemporary imaging studies emphasize the importance of preoperative vascular mapping to prevent hepatic ischemia and operative complications during pancreaticoduodenectomy and liver transplantation.

Conclusion: This cadaveric finding highlights the surgical significance of Michel type IX hepatic arterial anatomy. Although uncommon, a replaced CHA arising from the SMA carries important implications during hepatopancreatobiliary procedures. Thorough anatomical knowledge and preoperative imaging are critical to minimizing operative morbidity and optimizing surgical outcomes.