Previously Undescribed Anomalies of Hepatic Artery and Portal Venous Anatomy in a Case of Extrahepatic Biliary Atresia and its Implications.

A search on PubMed and Web of Science revealed scarcity of the literature on anomalies of hepatic artery or portal vein and the presence of arterioportal fistula in biliary atresia; although, it has long-lasting implications for both the patient and the surgeon, including hepato-pancreato-biliary surgeons, pediatric surgeons (who perform Kasai's portoenterostomy), liver transplant surgeons, and interventional radiologists. We report a case of extrahepatic biliary atresia with multiple anomalies involving the hepatic arteries, portal vein, cystic artery, arterioportal fistula and shunting, intrahepatic portal vein radicals, kidney, and external genitalia. The merits of the case from various standpoints including its implications for etiopathogenesis, caution during surgical anesthesia or postoperative management, and enrichment of the literature have been discussed. Copyright:

INTRODUCTION

The authors herein report a case of extrahepatic biliary atresia with previously undescribed arteriovenous anomaly complex involving the hepatic and cystic arteries, portal vein, arterioportal fistula with arteriovenous shunting, and disorganized intrahepatic portal vein radicals along with concurrent unilateral renal agenesis and hypospadias.

The merits of the case from various standpoints, including etiopathogenesis, caution during surgery, anesthesia or postoperative management, and enrichment of the literature have been discussed.

CASE REPORT

A 4-month-25 day's boy was admitted with a history of progressive jaundice, high-colored urine, and clay-colored stools. He had progressive distention of abdomen for 3 weeks. On examination, baby had icterus, hepatomegaly (firm, smooth surface, size up to 7 cm below the right costal margin) without splenomegaly, and distal hypospadias.

Blood picture was peculiar with leukocytosis and conjugated hyperbilirubinemia (6.3 mg %) with elevated alanine and aspartate transaminases. Sonography documented hepatomegaly with nonvisualization of gallbladder and absent of intrahepatic biliary radical dilatation. Left kidney could not be visualized. There was no gut tracer excretion up to 24 h on postpriming hepatobiliary iminodiacetic acid scan.

During Kasai's portoenterostomy, dissection of the fibrous gallbladder and portal remnants revealed a long cystic artery; the origin could not be traced. The left branch of the portal vein was attenuated. The hepatic arteries could not be traced. The cone of fibrous tissue at the portal plate was barely present.

Postoperatively, the serum bilirubin ameliorated, but did not come down to the basal levels.

Doppler ultrasonography revealed nonvisualization of hepatic artery proper at the porta; instead a branch from the left gastric artery was entering directly in the left lobe of the liver. Main portal vein was observed at porta with normal hepatopetal color flow.

A multiphasic-computed tomography-angiogram in arterial and venous phase was done to delineate the vascular anatomy using 1.5 mL/kg intravenous nonionic contrast with power injector (flow rate: 2.5 mL/s). The celiac artery divided into splenic, left gastric, and gastroduodenal arteries. The common hepatic and hepatic artery proper were absent; a branch of left gastric artery entering the liver directly from the left lobe [Figure 1a] was identified. Right hepatic artery was not visualized.

Figure 1

Arterial phase computed tomography angiography of maximum-intensity-projection images in coronal plane showing (a) replaced hepatic artery arising from the left gastric artery (horizontal arrow pointing left) and entering the liver through the left lobe. Splenic artery (vertical arrow pointing upward) was normal, (b) absent of the left kidney and the left renal artery (vertical arrow pointing downwards); the empty renal fossa is occupied by bowel loops

The main portal vein formed by the confluence of splenic and superior mesenteric veins [Figure 2a] continued as the right portal vein and attenuated left portal branch [Figure 2b]. The intrahepatic portal vein radicals were disorganized [Figure 2c].

Figure 2

(a) Coronal venous phase of maximum-intensity-projection images showing the formation of the main portal vein (horizontal arrow facing left) at porta by the confluence of splenic vein (vertical arrow pointing down) and superior mesenteric vein (vertical arrow pointing upwards). (b) Normal caliber right branch of the portal vein (horizontal arrow pointing right) and the attenuated left portal vein (horizontal arrow pointing left). (c) Venous phase axial computed tomography image showing disorganized intrahepatic portal vein branches (arrows). (d) Arterial phase axial computed tomography image showing the transient hepatic attenuation difference phenomenon, observed as an area of enhancement in the left lobe of the liver (encircled) with early opacification of the left portal vein suggesting arterioportal shunt

The presence of an arterioportal fistula was suggested by the identification of (1) Transient hepatic attenuation difference phenomenon, that is, area of parenchymal enhancement in left lobe of the liver visible during hepatic arterial phase [Figure 2d] and (2) Early filling of the left portal vein in arterial phase images.

The hepatic veins and inferior vena cava were unremarkable. The left kidney and left renal artery were not visualized [Figure 1b].

DISCUSSION

Biliary atresia is associated with other malformations in up to 20% of cases; the commonly encountered anomalies include malrotation, preduodenal portal vein, polysplenia, inferior vena cava or azygos anomalies, and cardiac malformations.[1] A search on PubMed and Web of Science revealed scarcity of literature on anomalies of the hepatic artery or portal vein and the presence of arterioportal fistula in biliary atresia.[23]

Anatomy of hepatic artery and biliary atresia

The celiac trunk continues as the common hepatic artery (CHA) after branching off the left gastric and splenic arteries. The CHA after issuing the gastroduodenal artery continues as hepatic artery proper which subdivides into the left and right hepatic arteries. Many variations of hepatic arterial anatomy have been described and may be observed in 25%–42% population;[4] however, hepatic arterial anatomical variations in the context of biliary atresia have not been documented much.

Implications for Kasai's portoenterostomy and the liver transplantation

The knowledge of variations in hepatic arterial and venous anatomy has long-lasting implications for the patient and medical practitioners including hepato-pancreato-biliary and pediatric surgeons (who perform Kasai's portoenterostomy), liver transplant surgeons, and interventional radiologists.

A description of the surgical technique of Kasai's portoenterostomy in Coran warrants careful dissection of “right and left hepatic arteries away from the field to preserve them.” Furthermore, the cone of fibrotic tissue “is located at the bifurcation of the main portal vein and its left and right branches. This constitutes the most important landmark during the dissection of the portal plate….”[1]

It is well-known that biliary atresia is the most common diagnosis leading to liver transplantation in children.[1] The importance of hepatic artery and portal vein anatomy in the context of a liver transplant cannot be overemphasized.

In the index case, we report several anomalies. (1) Absence of CHA and hepatic artery proper, (2) Left hepatic artery arising from the left gastric artery and entering the substance of the liver directly. Due to this anatomy, we could not identify the hepatic artery at surgery. Besides, such an abnormal anatomy makes it prone to inadvertent avulsion if the area is manipulated for any reason whatsoever, (3) Absence of the right hepatic artery, (4) Attenuation of the left branch of portal vein, (5) Anomalous, unidentified origin of cystic artery, (6) Disorganized intrahepatic portal vein radicals suggesting congenital rather than acquired (infective) origin of biliary atresia, (7) Presence of an arterioportal fistula which was probably compensating for the intrahepatic vascular insufficiency created by the absent of right hepatic artery and attenuated left portal vein, (8) Fibrous cone at the portal plate was barely present; in such cases dissection is guided by the portal bifurcation which in the index case was not prominent due to attenuated left portal vein, (9) Solitary functioning kidney which calls for caution in anesthesia, drug and fluid administration, and (10) Presence of distal hypospadias, necessitating additional anesthesia and surgery.

CONCLUSIONS

With this case report, the authors wish to emphasize several points: first, the need for meticulous and careful dissection in the region of the porta in view of possibility of aberrant arteriovenous anatomy, second, the need to document such abnormalities properly to caution against the possibility of any inadvertent vascular injury during future laparotomies for the liver transplant or other reasons, third, the support in favor of congenital origin of biliary atresia as a “global developmental anomaly,” and finally, the case merits reporting for adding value to the published literature.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient's parents have given their consent for the patient's images and other clinical information to be reported in the journal. The patient's parents understand that the name and initials of the patient will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.