Replaced Left Hepatic ArteryEdit

Replaced Left Hepatic Artery (RLHA) is an anatomical variant in the hepatic arterial supply where the left hepatic artery does not originate from the usual source, the proper hepatic artery, but instead arises from an alternative vessel, most commonly the left gastric artery. This pattern, alongside related variants such as an accessory left hepatic artery, is a well-documented feature of hepatic vascular anatomy and carries practical significance for hepatobiliary surgery, interventional radiology, and liver transplantation. The terminology distinguishes “replaced” from “accessory”: a replaced artery is the sole supplier to the left liver lobe from an unusual source, whereas an accessory artery supplements the standard supply.

In clinical practice, RLHA can be incidental and asymptomatic, but its presence becomes critical when planning liver-directed procedures. Preoperative recognition helps avoid inadvertent arterial injury or misinterpretation during surgery or embolization. The term often appears in the context of hepatic arterial anatomy classifications, such as Hiatt’s or Michels’ schemes, which organize the variants surgeons and radiologists must anticipate when mapping the arterial tree prior to operative or interventional maneuvers. Left hepatic artery Hepatic arterial anatomy Hiatt's classification Michels classification

Anatomy and nomenclature

  • Normal hepatic arterial supply typically flows from the celiac trunk to the common hepatic artery, then to the proper hepatic artery, which divides into right and left branches supplying the liver. In RLHA, the left hepatic artery arises from an alternate source, most frequently the Left gastric artery (a branch of the celiac trunk). The absence or relocation of the usual left hepatic artery origin defines the “replaced” pattern.
  • An important distinction exists between a replaced left hepatic artery and an accessory left hepatic artery. A replaced artery is the sole supply to the left lobe from the alternative source, whereas an accessory artery provides an additional carrier of blood to the left lobe on top of the usual left hepatic artery. The presence of both a replaced and an accessory artery can further complicate surgical planning and embolization strategies. Replaced Left Hepatic Artery Accessory left hepatic artery Left gastric artery Proper hepatic artery

Epidemiology and embryology

  • The prevalence of RLHA varies across populations and study cohorts, with estimates generally ranging from a few to a couple of dozen percent in surgical series. The exact frequency depends on the definition used and the imaging modality in question. Recognition of this variant is especially important in centers performing complex liver resections, donor hepatectomies, or transplants.
  • Embryologically, hepatic arteries form from the ventral segmental arteries of the developing foregut, undergoing selective persistence and regression that yield the adult arterial map. Variants like RLHA reflect alternate persistence of embryonic vessels, such as connections involving the Left gastric artery or other celiac trunk branches. Embryology of hepatic arteries Hepatic arterial anatomy

Clinical significance

  • RLHA has direct implications for hepatobiliary surgery, liver transplantation, and interventional radiology. Injury to a replaced left hepatic artery without recognition can lead to segmental ischemia of the left liver lobe or complications related to intraoperative blood loss control.
  • Procedures that may be influenced include left-sided liver resections, segmentectomies, donor lobe procurement, hepatic artery infusion therapies, and selective embolization for tumors. Preoperative arterial mapping helps ensure that surgeons and interventionalists preserve or reconstruct the arterial supply as needed. Liver resection Liver transplantation Transarterial chemoembolization Hepatic artery infusion Hepatobiliary surgery

Imaging, diagnosis, and preoperative planning

  • Preoperative imaging with CT angiography or MR angiography is commonly employed to delineate hepatic arterial anatomy, identify RLHA, and plan the surgical approach. Intraoperative assessment or adjuncts such as fluorescence guidance can supplement preoperative maps when complex arterial configurations are encountered. Angiography Preoperative imaging
  • Radiologists and surgeons use standardized classifications to communicate the arterial pattern succinctly and to guide reconstruction or preservation strategies. Hiatt's classification Michels classification

Surgical implications and management

  • When RLHA is present, meticulous dissection and careful preservation or reconstruction of the arterial supply to the left hepatic lobe are essential during resections, transplant donor procedures, or arterial-based therapies. Loss of arterial inflow to the left lobe can lead to complications such as ischemia, biloma, or abscess. In some cases, arterial reconstruction from the alternate source is performed to maintain adequate perfusion. Hepatic artery Liver transplantation Hepatobiliary surgery
  • In the setting of transarterial therapies for liver tumors, including transarterial chemoembolization (TACE) or radioembolization, knowledge of RLHA origin informs catheter placement and reduces the risk of non-target embolization. Transarterial chemoembolization Radioembolization

Variants and nomenclature

  • Replaced versus accessory left hepatic arteries reflect different clinical scenarios and surgical challenges. Thorough understanding of these variants supports safe surgical planning and reduces the likelihood of inadvertent injury during operations in the left hepatic lobe or surrounding structures. Left hepatic artery Hepatic arterial anatomy

Controversies and debates

  • Routine preoperative hepatic arterial mapping versus selective imaging: Some centers advocate routine arterial mapping for all major hepatic procedures to minimize intraoperative surprises, arguing that upfront knowledge of RLHA reduces complication rates and operative time. Others contend that universal mapping adds cost and may yield variants of uncertain clinical significance in lower-risk cases; they favor selective imaging guided by patient risk factors and planned procedures. The equity-versus-efficiency tension enters here when discussing resource allocation in health systems, though the practical priority remains patient safety and outcome. CT angiography MR angiography
  • Imaging modality choice: Debate continues over when to prefer CT angiography versus MR angiography, and whether intraoperative imaging or fluorescence guidance should supplement static preoperative maps. Advocates of newer imaging techniques emphasize accuracy and speed, while traditionalists stress reliability, availability, and cost. Angiography
  • Arterial preservation versus reconstruction: In complex resections or living-donor procedures, there is discussion about when to attempt arterial reconstruction of a RLHA versus accepting a potential segmental perfusion compromise. Critics may argue for conservative approaches to avoid prolonged operative times, while proponents emphasize preserving full vascular supply to reduce postoperative complications. Liver transplantation Surgical reconstruction
  • Ethical and policy considerations in resource use: Critics of broad resource-intensive imaging might argue that patient outcomes should guide use, not a political or social agenda. Proponents counter that precise vascular mapping can prevent costly revisions or complications. In practice, clinicians weigh evidence from outcomes data, cost-effectiveness analyses, and patient values to determine the threshold for mapping in a given setting. Health policy

See also