The hepatic artery plays a vital role in supplying oxygenated blood to the liver, an organ responsible for numerous metabolic and detoxification processes. Understanding the anatomy of the hepatic artery is essential for professionals in medicine, surgery, and imaging, as well as for students studying human anatomy. The hepatic artery has a complex and sometimes variable anatomy that is important to understand, especially during procedures involving the liver, gallbladder, pancreas, and surrounding organs. This artery, although small in diameter compared to others in the body, carries a disproportionately high significance in liver health and surgical planning.
Overview of the Hepatic Artery
Primary Function
The hepatic artery is one of two main sources of blood supply to the liver. While the portal vein delivers nutrient-rich blood from the gastrointestinal tract, the hepatic artery provides oxygen-rich blood, essential for hepatic cell metabolism and function.
General Pathway
Originating from the celiac trunk, the hepatic artery progresses toward the liver, branching and subdividing as it reaches and enters hepatic tissue. The typical anatomy may differ among individuals, but there is a standard model known as the ‘classic hepatic arterial anatomy.’
Classic Hepatic Arterial Anatomy
Origin and Course
In most people, the hepatic artery arises from the celiac trunk, which is one of the three main branches of the abdominal aorta. The celiac trunk gives rise to three arteries:
- Left gastric artery
- Splenic artery
- Common hepatic artery
From this point, the common hepatic artery gives off branches before continuing toward the liver as the proper hepatic artery.
Branches of the Hepatic Artery
- Gastroduodenal artery (GDA): Branches from the common hepatic artery; supplies the stomach and duodenum.
- Proper hepatic artery: Continuation of the common hepatic artery after the GDA branches off.
- Right and left hepatic arteries: Branch from the proper hepatic artery to supply the corresponding lobes of the liver.
In some individuals, additional branches such as the cystic artery may arise from the right hepatic artery, supplying the gallbladder.
Variants of Hepatic Artery Anatomy
Common Variations
Although the classic anatomy occurs in about 55-75% of the population, many people have variations. These variants are usually asymptomatic but are critical to identify before surgeries like liver transplants, cholecystectomy, or pancreaticoduodenectomy (Whipple procedure).
- Replaced right hepatic artery: Originates from the superior mesenteric artery (SMA) instead of the proper hepatic artery.
- Replaced left hepatic artery: Arises from the left gastric artery.
- Accessory hepatic arteries: Additional arteries that supplement the blood supply to the liver.
Clinical Relevance of Variants
Variations can influence the approach during interventional radiology, liver resection, and organ transplantation. Accurate mapping of hepatic arteries using imaging techniques like CT angiography or MR angiography is recommended before procedures.
Terminal Distribution Within the Liver
Segmental Distribution
The liver is divided into eight segments based on vascular supply. The right and left hepatic arteries further divide into segmental branches that feed these individual liver segments. This segmental pattern is crucial in hepatic surgery, allowing for segment-specific resections.
Coupling with Portal Triads
Each hepatic segment receives a triad of structures: a branch of the hepatic artery, portal vein, and bile duct. These structures travel together in the portal triads and supply the functional units of the liver known as hepatic lobules.
Hepatic Artery in Clinical Procedures
Liver Transplantation
The hepatic artery is surgically anastomosed in liver transplants. Proper arterial blood flow is essential, as the liver depends on dual blood supply, and the hepatic artery is the only source of blood for the biliary tree. Any interruption in arterial supply may lead to biliary complications or graft failure.
Chemoembolization and Radiologic Interventions
In hepatic tumors like hepatocellular carcinoma (HCC), the hepatic artery becomes a target for transarterial chemoembolization (TACE) or selective internal radiation therapy (SIRT). These procedures deliver treatment directly through the arterial branches feeding the tumor.
Surgical Ligation and Bleeding Control
Understanding hepatic artery anatomy is essential when managing bleeding in trauma or during surgical procedures. Accidental ligation or injury to the hepatic artery can lead to ischemia and severe hepatic dysfunction.
Diagnostic Tools for Hepatic Artery Mapping
CT Angiography (CTA)
CTA provides detailed 3D imaging of vascular anatomy, helping identify arterial variants and detect blockages or aneurysms. It is commonly used before liver surgery and transplantation planning.
MR Angiography (MRA)
MRA is a non-invasive method to visualize hepatic arteries without radiation exposure. It is useful in patients with kidney problems or when repeated imaging is needed.
Doppler Ultrasound
Ultrasound is often used to assess hepatic artery flow post-transplant or during abdominal evaluations. It helps detect vascular complications like thrombosis or stenosis.
Hepatic Artery Disorders
Hepatic Artery Thrombosis
This condition is a critical complication in liver transplant recipients. It involves blockage of the hepatic artery and can result in liver infarction, graft failure, and death if not promptly treated.
Hepatic Artery Aneurysm
A rare but potentially life-threatening condition. These aneurysms can rupture and cause internal bleeding. Diagnosis is usually made through imaging, and treatment may include surgery or embolization.
The hepatic artery, although small in size, plays a significant role in liver function, surgical success, and overall abdominal health. Its anatomy, including common variants and segmental distribution, must be well understood by healthcare professionals. Accurate knowledge of hepatic arterial anatomy aids in the safe performance of surgeries, interventional procedures, and transplants. With the aid of modern imaging technologies and anatomical studies, clinicians can better plan interventions and manage complications related to hepatic arterial circulation.