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Journal of the Anatomical Society of India

Large Accessory Hepatic Veins - A Case Report

Author(s): Taranikanti, V; Dhar, P.

Vol. 52, No. 2 (2003-07 - 2003-12)

Department of Anatomy, All India Institute of Medical Sciences, Delhi INDIA

Abstract

A routine dissection in the abdominal region of an adult male cadaver revealed large 'accessory' veins belonging to the lower group of the hepatic veins. These veins emerged from the posteroinferior aspect of the right lobe and the caudate process of the liver and their caval openings were seen in the subhepatic segment of the inferior vena cava (IVC). The extent of these venous tributaries from their emergence with context to the liver parenchyma up to their openings into the IVC was measured. Also, the location and the calibre of the corresponding venocaval opening was determined. Retrohepatic and subhepatic segments of the IVC were examined for other larger as well as smaller venous openings. The possible developmental basis for variations like the present one, could be attributed to arrests, errors or persistence of innumerable patterns encountered during the initial period of embryonic development.

The variation described is significant in many ways. Inadvertent trauma and unforeseen bleeding during the surgical manipulations in the vicinity of liver can be avoided to a great extent with prior knowledge of the possible anatomic variations of the hepatic veins.

Key words: Right accessory hepatic vein, middle accessory hepatic vein, inferior vena cava, venocaval openings, liver transplantation.

Introduction:

The hepatic veins usually present as the superior, middle and the inferior groups of veins. Enlarged veins of the middle and the inferior groups bear surgical importance-(Launois et al, 1993). Accordingly, their ligation during right hapatectomy before commencing the actual parenchymatous dissection has been advocated. Also, in resections for malignant liver disease, the scope of ligating the main hepatic vein and yet maintaining the drainage for segment VI is based on the fact that the inferior veins, when large, drain segment-VI.

Variations in the drainage pattern of hapatic veins have been reported from time to time. These include accessory right hapatic veins (Van Leeuwen et al., 1994, De Cecchis et al, 2000), significant accessory hepatic veins (Marcos et al., 2000) and accessory suprahepatic veins (Bach et al., 1994-95). The varied presentation of hepatic veins does necessitate an awareness of associated anatomical variations as an important prerequisite for avoidance of potential surgical catastrophies while dealing with abdominal interventions.

Recent advances in the field of organ transplantation have emerged as the most valuable means in combating the disorders that lead to irreversible organ failures. This holds especially true for organs like heart and liver where there is no adjuvant support like dialysis. Any anatomical deviation from the usual pattern might influence the technical feasibility and the outcome of such surgical procedures. However, in spite of the great practical importance of hepatic venous pattern in clinical set up, only few authors have detailed its morphology in comparison to numerous reports on arterial, ductal and portal venous system.

Case Report:

During routine dissection, a varied hepatic venous drainage pattern was noted in an adult cadaver. Large 'accessory' hapatic veins of the lower group were seen draining into the subhepatic segment of the IVC (Fig. 1A). Of these, one emerged as a single trunk from the postero-inferior surface of the right lobe - right accessory hapatic vein (RAHV) and the other - middle accessory hapatic vein (MAHV) was formed by union of two individual tributaries emerging from the caudate process (Fig. IB). The RAHV measured 1.5cm (from its emergence through the liver parenchyma upto its joining with the IVC). The individual tributaries of MAHV were 1.0 and 0.75cm long with the common trunk measuring 1.0cm in length. Examination of the luminal aspect of IVC (Fig. 2A) revealed the openings of the superior group of hepatic veins, one for the right upper hepatic vein (RHV) with a luminal diameter of 2.0cm and a common opening for middle and left upper hepatic veins (LHV) with a luminal diameter of 1.75cm. in the retrohepatic segment of IVC. For the inferior group, the luminal diameter of RAHV and MAHV was 0.8 and 0.7cm respectively and their openings were localized in the subhepatic segment of the IVC (Fig. 2B). The luminal opening of RAHV was observed to be in line with the luminal opening of the right renal vein, being 3.0 cm proximal to it. In addition to this classical group of lower hepatic veins, a large vein (** in Fig. 3) was seen emerging in the vicinity of the bare area (base) and draining into the IVC. The opening of this vein was posteroinferior to the opening of the right (superior) hepatic vein (Fig. 2B) and presented a luminal diameter of 1.0cm.

Discussion:

In earlier days, procedures involving segmental resections of the liver did not consider hepatic venous drainage pattern important in spite of their known intersegmental territorial distribution. However, it was realized subsequently that intraoperative bleeding (venous) problems during liver surgery could pose a great threat even if knowledge of arterial and biliary pattern was respected. Nevertheless, it became clear that a comprehensive knowledge of various anatomic variations with regard to arterial supply and ductal pattern along with the segmental divisions of portal and hepatic veins does play a pivotal role in developing comprehensive surgical skills for successful completion and outcome of difficult and complex procedures such as liver transplantation (Williams et al, 1998). Thus, a complete and thorough knowledge of surgical vascular anatomy related to liver has become an important and integral component of donor harvesting as well as recipient operations.

In conventional Anatomy texts, hepatic veins have often been described as sessile veins opening immediately beneath the diaphragm into the IVC – (McGregor & du plessis, 1969). Nevertheless, unanticipated abnormal systemic venous channels have been reported as the causative factors for post surgical problems such as cyanosis following Fontan type operation – Yoshimura et al, 1999). The study carried out on corrosion casts of 93 adult livers by Sledzinski and Tyszkiewicz (1975) has revealed the incidence of large 'accessory' hepatic veins of the lower group to be 15%. De Cecchis et al (2000) have documented the presence of such accessory veins in 28% of the cases, being mostly restricted to the right lobe. Marcos et al. (2000) observed the presence of at least one significant accessory hepatic vein in sixteen out of forty living liver donors. In the present study, the large accessory hepatic veins of the inferior group were seen in one out of twenty cadavers examined (5%). A thorough knowledge pertaining to the openings of the hepatic veins holds relevance in the management of cases of hepatic trauma with hepatic vein avulsion and also in resection of parts of diseased liver (Kennedy and Madding, 1977; Nakamura and Tsuzuki, 1981).

According to the classification criterion for openings of the hepatic veins adopted by Camargo et al., (1996), the caval openings of the superior group of hepatic veins (1.5-2.0cm) corresponded to the set of large openings (LO) and those of the accessory hepatic veins (0.5-1.0 cm) of the lower group to the set of medium openings (MO). In the present case report, the location of superior large openings (SLO) in the first row of retrohepatic segment and the inferior openings (ILO) in the subhepatic segment of the IVC correlated with the earlier report of Chang et al. (1989) that focuses on the location of the hepatic vein openings in the IVC.

From the developmental point of view, the vitelline veins (between suprahepatic and subhepatic intervitelline anastomosis) are resolved into a network of sinusoids by the developing cords of the endodermal cells (future hepatocyes) in the septal mesenchyme as early as four weeks (Arey, 1966). The corresponding lengths of the umbilical veins follow the suit. Thus, at this early stage, mixed blood derived from umbilical and vitelline veins perfuses the hepatic sinusoids by a series of branching vessels called venae advehentes (VA) and is returned back from liver by a set of four venae revehentes (VR)- two venae revehentes lying on each side and opening in the corresponding horn of the sinus venosus (Williams et al, 1998) (Fig. 4A). However, this developmental stage represented by four hepatocardiac veins is a transient one and is replaced by one dominant rapidly enlarging channel referred to as the right vitelline hepatocardiac vein ultimately forming the terminal segment (TS) of the inferior vena cava (IVC). It is into this segment of the IVC, that the right venae revehentes and the new channels draining territories of the left venae revehentes (representing superior and inferior groups of right and left hepatic veins respectively) establish communication (Williams et al, 1998) (Fig. 4B) Modifications in the morphogenesis occuring at this embryonic period of development could explain the genesis of varied venous patterns encountered from time to time.

The more significant implication of the variability with context to the venous drainage pattern of the liver is of immense practical importance to the surgeon who deals with interventional procedures. The recognition of the fact regarding the presence or absence of large accessory veins is important at the time of surgery because factors other than haemorrhage like air embolism at laparotomy could be the important cause of death in hepatic vein injuries (Decker & du Plessis, 1986). Keeping in view the intraoperative complications, Ledesma- Medina et al. (1985) have suggested in toto preoperative radiological evaluation in patients who are to undergo liver transplantation. A prior knowledge of the possible anatomic variations resulting from persistent developmental arrangement can avert inadvertent traumas and unforeseen bleeding to a great extent. To conclude, the presence or absence of such variations my help in modifying the criteria adopted for management by a transplant surgeon. Hence, this report re-emphasizes the importance of adequate knowledge regarding the varied pattern of large 'accessory' hepatic veins as an accurate and better designed road map for the surgeon.

References:

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Fig 1A:

Visceral surface of liver with exposed subhepatic segment of IVC. Large accessory hepatic veins of the lower group seen draining into the IVC.

 

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Fig. 1B:

Subhepatic segment of IVC with large accessory hepatic veins as its communications. RAHV- right accessory hepatic vein. MAHV- middle accessory hepatic vein.

 

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Fig 2A:

Luminal aspect of retrohepatic segment of IVC showing superior large openings (SLO). RHV- opening of right upper hepatic vein. LHV- common opening formed by middle and left upper hepatic vein.

 

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Fig. 2B :

Luminal aspect of subhepatic segment of IVC showing openings of large accessory hepatic veins. RAHV-right accessory hepatic vein. MAHV- middle accessory hepatic vein; opening of the vein emerging in the vicinity of bare area.

 

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Fig. 3

Posterior surface of liver showing a large vein (**) emerging in the vicinity of bare area and draining into the IVC.

 

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Fig.4A:

Venous arrangement in embryo at 4 weeks of gestational age.
RVA-right venae advehentes; RVR-right venae revehentes;
LVA-left venae advehentes; LVR-left venae revehentes;
RVHC-right vitelline hepato cardiac.

 

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Fig. 4B:

Venous arrangement in later prenatal months showing the grouped hepatic veins.
URHV- upper right hepatic vein; LRHV-lower right hepatic vein;
ULHV-upper left hepatic vein; LLHV-lower left hepatic vein;
TS-terminal segment.

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