Hepatic Artery Anatomy and Hepatic Vein Drainage
Most Common Variant of Normal Hepatic Artery Anatomy
The most common variant of normal hepatic artery anatomy is the replaced right hepatic artery from the superior mesenteric artery (SMA).
Hepatic arterial anatomy demonstrates significant variability, with approximately 40% of cases showing anomalies from the standard configuration 1. Understanding these variations is crucial for hepatobiliary surgeons and interventional radiologists to avoid complications during procedures.
The most common variants include:
- Replaced right hepatic artery (RRHA) from the superior mesenteric artery, occurring in approximately 8-15% of cases 2, 3
- Replaced left hepatic artery from the left gastric artery, occurring less frequently 1
- Combinations of both variants 3
The RRHA arising from the SMA typically courses dorsal to the portal system to reach the Calot's triangle before entering the right lobe of the liver 2. This variant is particularly important to recognize during pancreaticoduodenectomy (Whipple procedure) and other hepatobiliary surgeries to prevent inadvertent injury 1.
Right Hepatic Vein Drainage
The right hepatic vein drains segments V-VIII of the liver.
The liver is divided into eight functional segments according to the Couinaud classification system, which is based on vascular inflow, outflow, and biliary drainage 4. The venous drainage of the liver follows a specific pattern:
- Right hepatic vein: Drains segments V-VIII 4
- Middle hepatic vein: Drains segments IV, V, and VIII
- Left hepatic vein: Drains segments II-IV
Understanding this segmental anatomy is essential for:
- Surgical planning in liver resections 4
- Transplantation procedures, especially split liver transplantation 4
- Interventional radiological procedures such as transarterial chemoembolization (TACE) 5
Clinical Significance
The anatomical variations of the hepatic artery have significant clinical implications:
- During pancreaticoduodenectomy, failure to recognize a replaced right hepatic artery can lead to inadvertent injury, resulting in hepatic ischemia or infarction 1
- In liver transplantation, precise knowledge of donor and recipient vascular anatomy is crucial for successful anastomosis 4
- For TACE procedures in hepatocellular carcinoma, identifying variant arteries is essential as they may be the primary blood supply to tumors 6
Preoperative imaging with CT, MRI, or angiography plays a vital role in detecting these variations before surgical intervention 6. The American Association for the Study of Liver Diseases emphasizes the importance of understanding these anatomical relationships for optimal surgical planning 4.
Common Pitfalls
- Failure to identify a replaced right hepatic artery during pancreatic surgery may result in accidental ligation and subsequent right lobe ischemia 1
- Not recognizing the relationship between the falciform ligament and liver segments can lead to errors in surgical planning, especially in split liver transplantation 4
- Assuming standard anatomy without appropriate preoperative imaging can lead to significant complications during hepatobiliary procedures 6, 2