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FEATURES OF THE VARIANT ANATOMY OF THE VASCULAR AND BILIARY LIVER
ARCHITECTONICS IN RELATED DONORS
A.Kh. Babadjanov, Doctor of Medical Sciences, Professor S.A. Sultanov, Candidate of Medical Sciences S.S. Ibrohimov, Surgeon
The Republican specialized scientific and practical medical center of surgery named after academician V. Vakhidov (Uzbekistan, Toshkent)
DOI:10.24412/2500-1000-2025-1-3-28-33
Abstract. The main variants of angioarthroatronics of the arterial system and venous outflow, as well as biliary structure of the liver are covered. The typical and atypical deviations of vessels and biliary ducts, which play a special role in donor liver resection, are frequently encountered in surgical practice. The most important modern studies on improving liver fragment resection results in donors are reviewed, and the most effective tactical and technical surgical aspects with lower frequency of complications are indicated.
Keywords: resection, liver donor, transplant, multispiral computed tomography, liver vessels, biliary ducts.
The Orthotopic liver transplantation (OLT), which is actively developing in the world medical practice, revolutionized approaches to treatment of patients with terminal stages of diffuse and focal lesions of the liver, providing a radical cure with long-term and favourable outlook. However, the advances in this area, coupled with the ever-increasing need for OLTs, have contributed to a new medical and social problem - a lack of post-mortem donor organs. Due to the growing shortage of donor organs, waiting times for surgery have increased to many months, correspondingly, the mortality of patients in this period is increasing. One of the additional sources for liver transplants was the involvement of live (mostly related) donors of liver fragments [4].
The advantages of organ transplantation from a living donor include independence from the system providing cadaveric donor organs, scheduled surgical intervention, high quality hepatic parenchyma transplant, short conservation time, good «congruence» HLA donor and recipient haplopopes (Gautier S.B Co-author, 2004). The main drawback of the method is the anaesthesia and surgical risks to health and life of the donor family. The risk of developing postoperative complications in a donor is considered to be up to 21% (Nakamura T. et al., 2002; Malago M. et al., 2003). To minimize these risks, the potential donor is tested for functional state of major organs and systems during selection, and anatomical
variants of vascular and biliary liver are identified, Influence the possibility and tactics of operational intervention. The variability of the anatomy of the arterial liver is found in 32-50% (Balahnin P.V. and Soav. 2004; Egorov V.I. and co-author., 2009). The ramification of the portal vein causes a failure of donation in almost 20% of cases (Kamel I.R., Kruskal J.V., 2004). The plane of parenchyma separation depends on the course of the hepatic veins, with the preservation of adequate venous outflow of the future transplant (Cheng Y., 1997; Pomfret E., 2002). Biliary complications in liver transplantation, associated with complex anatomy of the bile ducts, develop in almost 30% of cases and often determine risks to the life of the recipient (Cheng Y.F., 1997; Icoz G., 2003; Kim R.D., 2005).
Preliminary assessment of the vascular structures of the liver by the architect
According to Galyan T.N. with co-author. (2011) in the study of angioarchitectonics, which allows to evaluate anatomical reserves of liver for life-giving its fragment, the accuracy of mul-tispire computed tomography (MSCT) with intravenous contrast is up to 100%, and magnetic resonance imaging (MRI) up to 93%. MSCT has a high resolution in the visualization of liver parenchyma and vascular structures (Table) [6]. As the technology and software of the tomographs improve, many diagnostic problems are solved
faster, the quality of images is improved, it be- structural-anatomical features of the organ [1, comes possible to evaluate more clearly the 16].
Table. Diagnostic informativity of MSCT - angiography in the identification of the type of LABS IV
segment, the type of PV split, determination of hemodynamic importance of the veins of the liver
ABS segment IV type Split PV Stem Option Hemodynamically significant liver veins
Type R type RL type
Sensitivity 92% 100% 78,5% 87,5% 100% 100% 100%
Specificity 100% 95% 100% 100% 93% 96% 87,8%
Precision 95,5% 97,3% 97,3 90,5% 94% 96% 90%
The improvement of the tomography software allows to obtain three-dimensional images, including virtual ones, necessary for surgeons [2, 12]. In addition, three-dimensional images facilitate the calculation of the intended transplant volume and liver as a whole, because the correctness of the calculations of these parameters reduces the risk of an operation for both donor and recipient [5]. MSCT provides the most accurate information on the size of the intended transplant, surpassing anthropometric methods by allowing virtual resection of the liver. In the studies of Abramov N.N. with the co-authors, the volume of the liver fragment at MSCT was compared to the mass of the received transplant on operations [14, 16].
Features of angioarchitectonics of the liver venous system
The venous circulation in the liver is represented by the portal vein (PV) system, which carries blood to the organ, as well as the hepatic veins that draw blood into the inferior vena cava (IVC). The number of veins in the liver that are entering the IVC varies significantly, sometimes reaching 25 vessels and more [12, 15]. The classical anatomy of the hepatic veins was originally described in the classification by Soyer (1995). Three main anatomical variants of the terminal part of the liver veins were identified, which are responsible for the drainage of the right part of the liver. The first option - the lower hepatic vein is visible, but significantly thinner or not at all (the dominant right upper hepatic vein (88%)). The second option is the upper right and lower right hepatic veins are equivalent (6%). The third option is the dominant lower hepatic vein (6%), where the upper hepatic vein is always visible but has a smaller diameter than the lower [8].
In 2004 S. Orguc and M. Tercan modified the scheme Soyer (1995). According to this classification, the following anatomical variants of the left hepatic vein (LHV) are described:
1) single LHV barrel (16%);
2) Separate LHV front and back branch injection into the IVC;
3) Merging of the front and rear branches of the LHV with the formation of a common trunk;
4) the merging of the front and rear branches of the LHV with the formation of a common trunk and the attachment of a lateral branch from segment IV [3, 10].
In the literature, intermediate, diffuse and main types of liver veins are also distinguished. The main type is detected in 70% of observations. In the flattening type it is very difficult to separate the main stem, instead of it 2-3 veins of approximately one diameter are separated. Variability of formation and supply of blood outflow from liver described by V.A. Vasilev and coauthor [3] based on the primary classification of Soyer (1995) as follows:
1. The most frequently detected number of hepatic veins - 3-5;
2. The Middle Hepatic Vein (MHV) and LHV in 80% of observations form a common trunk that opens into the IVC next to the right hepatic vein (RHV);
3. The majority of authors consider RHV to be the dominant vein;
4. The predominant type of hepatic vein structure is the trunk [9].
It is worth paying attention to the features of venous drainage of the right liver due to additional lower right hepatic vein (LRHV). It can be detected in a number of observations and refers to the vessels draining segments V and VI of the liver. There are also anatomical variants in which the large branches V and VIII of the liver segments are the inflow of the median vein. The most structured classification of effusive vessels of the right liver was proposed by G. Varotti and co-author. The authors identify 4 types of venous drainage from the right liver. Type 1a is characterized by the outflow due to RHV and single stem formed by RHV and MHV, type 1b - RHV and LRHV; type 2a - RHV and median vein
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branch, draining V segment of liver; type 2b -RHV, LRHV and median vein branch, draining V segment of liver; type 3 a RHV and branch of median vein, draining VIII segment of liver; type 3b - RHV, LRHV and median vein branch, draining segment VIII of liver; type 4a - RHV and branches of the median vein, drainage V and VIII segments of the liver; type 4b - RHV, LRHV and median vein branch, drainage segments V and VIII of the liver [14].
The options of anatomy of terminal segments of MHV and LHVP were studied by M.G. Yefa-nov and co-author. (2009). The common liver stem was found in 42% of observations, the common mouth of the vessels was found in 44% of patients. Separate LHV and MHV intakes were found in 14% of observations. The fusion options of fissural vein with MHV and LHV were classified separately: the most frequent variant of anatomical fissural vein was its fusion with HPS (68%). Significantly less than the fissural vein was fused with the medium (12%). The insertion of a fissural vein between the left and middle hepatic veins was detected in 20% of observations. However, it is worth mentioning that in 16% of the observations, there was a self-insertion of the fissural vein into the common mouth of the left and middle hepatic veins or between them when they are separated in the IVC. In 4% of the observations, the fissural vein was between the left and middle veins in the stem formed by them. As for the other additional branches, besides fissural vein, in all analyzed observations the left dorsal vein fell into the left half-circle of LHV, vein VIII segment - into the right wall of MHV [8].
In the studies of Gautier S.V. with co-author. (2008) Patients with vein bifurcation were the most prevalent among MSCT findings on portal vein branching [5, 10].
The most successive classification is considered, according to the structure of the portal vein system, proposed by T. Nakamura (2002). In the study of portal blood supply of liver in relatives donors determined the structure of the stem of the portal vein and its branching options: bifurcation, triforcation and transposation of right paramedic veins. Bifurcation of PV was determined in 91.4% of the observations, of which early division of right PV (length of stem of right VE less than 15mm) was observed in 43.7% of the cases. Trifurcation of PV is observed in 5% of cases.
Transpossion of right paramedic veins was attributed to 3.5% of observations - extra-hepatic detachment of the anterior right PV from the left PV (1.4%), intra-hepatic detachment of the anterior right PV from the left PV (2.1%) [6].
Features of the arterial angioar-throiretronics and the hepatic duct system
Belouus P.V. s. co-author (2014) Studying the question of segmental structure of the liver, determined the number of hepatic ducts and arteries within each segment. In the first segment, one to five segmental arteries were identified starting from both branches of the liver's own artery or from an additional artery to the left portion of the liver. Bile outflow was carried out by bile ducts in the number of one to four, entering the left or right hepatic duct. The second segment has one or two segmental arteries. The bile drain was carried out on the ducts from one to three. The third segment had in the vast majority of cases one segmental artery, and in 5% two segmental arteries, and also (in predominant quantity) contained one segmental duct, and in 3% - two. The fourth segment was infused by branches from both branches of the own hepatic artery at the expense of one or three segmental arteries, or from additional branch of the artery to the right portion of the liver, in the absence of a right branch. The bile drain also occurred on segmental ducts in a number of one to three. The fifth segment in all cases received arterial blood from the right branch or additional artery to the right portion of the liver by one-three arterial vessels, and the gallbladder occurred on one or two ducts. The sixth segment also had blood flow from the right branch or additional artery to the right liver portion by one or two segmental arteries, and only in one case contained three arteries with both the right branch and additional artery. The bile leaked 7% from two ducts, and in other cases one per duct. The seventh segment of segmental arteries in number from one to three, from the right branch or additional artery to the right portion of the liver, and in the same number segmental ducts, which enter into the right hepatic tract. The eighth segment also contained one to three segmental arteries and bile ducts [2].
The authors noted that liver blood supply is characterized by a pronounced individual variability, which manifests in:
a) separation of the general hepatic artery directly from the aorta (1.8%) or from the upper pleural artery (1.4%);
b) the length of the total hepatic artery depends on the type of duodenal structure: short (7,1±0,3 mm), vertical, long (27±0,3 mm) horizontal, intermediate (5,2±0,3), horseshoe-shaped;
c) sources of the right and left branches of the own hepatic artery (in 5.7% the right branch, and in 1.8% the left branch were the only continuation of the own hepatic artery, in 1.8% the right branch was separated from the upper parietal; left branch separated from the left ventricle artery by 5.7%);
d) the difference in the course and the entrance into the liver of the right and left branches (bifurcation and trifurcation);
e) in the expressed number of additional arteries (to the right - 25.2%, to the left - 4.7%, un-described option of availability to both parts -0.7%);
f) in large amount of the bubble artery deviating from the additional artery to the right portion - 17.5% of cases [2, 13].
Among the many existing classifications of the hepatic branch of the artery, the most practical classification is proposed by N. Michels (1962). Based on this classification Galyan T.N. with co-author (2011) emphasized «typical» structure of the own hepatic artery, that is its division into independent right hepatic artery (RHA) and left hepatic artery LHA - type 1, was identified in 56.7% of observations. The most frequent vessel replacement options were left ventricular artery replacement LVA (10%) and superior ventricular artery replacement SVA (12.9%) [6].
The Optional anatomy of the protozoan system according to Belos P.V. with co-author you [2,11]. Was found in: a) variability of the bubble duct (right-side-flow was detected in 4 cases); b) change in the number of bubble ducts (two bubble ducts in 2 cases, entering the common liver duct); c) Variation of the length of the bubble duct (5.7% more than 4 cm, 8.6% less than 2 cm), g) Variability of the angle of incidence (25-70°).
Galyan T.N. with co-author (2011) described a typical structure of the bile ducts (type I) according to the results of MRI in studies of 60 potential donors in 53.5% of cases; 21.6% - II type of formation of the general hepatic duct (GHD) -
equivalent to the merger of the two right and left partial ducts (LPD) with the formation of «upper biliary Confucius»; independent insertion of the right rear segmental duct (RRSD) into the LPD (type III) - 11.6% of donors; RRSD absorption in the LPD (type IV) - 8.3% of observations. Rare forms of GHD formation (type V) were detected in 5% of cases. The anatomical variation of the left lobe was studied in 32 donors (53.3%). According to the classification P.R. Reichert et al. (2000) the following variants are distinguished: L1 - the flow of segment IV is poured into the PLC between the junction of the channels II and III segments and the confluence of the left channels (43.7%; при n-32); L2 - presence of two channels of the IV segment, which are in the LPD (n-5; 15,6%); L3 - drainage of the duct of segment IV into the duct of segment III (n-2; 6,2%); L4 - The inlet of the segment IV in the LPD at the junction of the segments II and III (n-5; 15,6%); L5 (unclassified variants) - 6 (17.7%) [6].
According to Belos P.V. (2014) hepatic-duodenal ligament has topographic anatomical features:
a) the difference in the studies of the left branch of the own liver artery was revealed, which is probably related to the «U-shaped» movement of the left branch;
b) a new, practically significant topographic-anatomical region of the location of the vesicular artery was identified, when it is separated from the additional artery to the right portion of the liver - «an alternative triangle»;
c) New topographic-anatomical relationships of structures of liver and duodenal ligament, which are structured in different types, have been identified;
d) the number of intra-cerebral arteries and ducts varies in most from one to three, with the largest (up to five) in the first segment d) there are different types of nervous structures of the hepatic-duodenal ligament, with a predominance of net type [2, 7].
Discussion. The algorithm for screening potential donors of liver fragments should include MSCT and MRI to investigate the vascular and biliary anatomy of the liver of the related donor. MSCT has advantages in the most detailed study of the structure of the liver's arterial line. Given the better visualization of the right and left limb and especially the additional arteries and segment
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IV arteries in MSCT, donors who plan to perform a right, left or lateral bisection of the liver should be treated with an arterial MSCT, portal and venous phase for accurate determination of the arterial blood supply IV segment in combination with MR-cholangygraphy for parallel evaluation of biliary structure. When planning the right lobe resection, attention should be paid to the accuracy of diagnosis of double arterial blood supply of the liver, presence of right-sided type IV segment blood supply, tricuspid stem of the portal vein and additional hemodynamically significant (more than 5 mm) vein of right ventricle. When planning the left lateral liver bisect donation, it is necessary to detail anatomical features of separate hepatic vein II and III segments, as well as the fusion of the medial and left hepatic veins to form a single trunk together with the inferior vena cava. The accuracy of diagnosing these structural features has a crucial influence on the choice of liver fragment resection strategy for the donor family, thus ensuring safety for the donor and recipient lives. The application of a complete evaluation of the biliary and vascular anatomy of
mal plane of the liver resection with the aim of obtaining two fragments of the liver, which meet the criteria of the whole organ, having autonomous systems of arterial and portal blood supply, venous and bile drainage. When planning the resection of the left lateral liver bisect in the related donor, it is necessary to determine the level of drainage of the IV segment relative to the bile ducts II and III segments. The inclusion of it in the duct III segment limits the possibility of donation of left lateral liver bisection. When planning the right liver resection, donors with separate right front and right back sectional ducts at a considerable distance should be excluded if possible [6].
Conclusion. Thus, the study of the vascular and biliary architectonics of the liver in the relatives is an integral part of their preoperative examination, and shows a great variability both of the individual structures and of all their systems. This knowledge is particularly important when performing a donor resection in liver transplantation and should lead to a reduction of the frequency of possible complications.
the liver in the relatives allows to select the opti-
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ОСОБЕННОСТИ ВАРИАНТНОЙ АНАТОМИИ СОСУДИСТОЙ И БИЛИАРНОЙ АРХИТЕКТОНИКИ ПЕЧЕНИ У РОДСТВЕННЫХ ДОНОРОВ
А.Х. Бабаджанов, д-р мед. наук, профессор С.А. Султанов, канд. мед. наук С.С. Иброхимов, врач хирург
Республиканский специализированный научно-практический медицинский центр хирургии имени академика В. Вахидова (Узбекистан, г. Ташкент)
Аннотация. Освещены основные варианты ангиоархитектоники артериальной системы и венозного оттока, а также билиарного строения печени. Подчеркнуты часто встречающиеся в хирургической практике типичные и атипичные отхождения сосудов и билиарных протоков, которые играют особую роль при донорских резекциях печени. Проведен обзор важнейших современных исследований по улучшению результатов резекции фрагмента печени у доноров, указаны наиболее эффективные тактико-технические хирургические аспекты с более низкой частотой осложнений.
Ключевые слова: резекция, донор печени, трансплантация, мультиспиральная компьютерная томография, сосуды печени, билиарные протоки.
