Dean Ravnik

Anatomical variations in the pattern of the right hepatic veins: possibilities for type classification

A morphological study of the right hepatic veins (RHVv) was conducted based on the shape and the confluence pattern of the superior right hepatic vein (SRHV) and the presence of accessory right hepatic veins. The study was performed in 110 undamaged, randomly selected, cadaveric human livers prepared using the corrosion cast methodology. The principles for classifying the RHVv into types were as follows: the length of the vein trunk, the confluence of 2 or 3 main tributaries that form a trunk, and the accessory right hepatic veins that modify the venous drainage of the right side of the liver. Four types of SRHV were identified. Type 1 (20%), type 2 (40%) and type 3 (25%) were the most common, while type 4 (15%) was linked to the accessory right hepatic veins in cases where they drain a surgically important part of the liver. Accessory right hepatic veins were found in a total of 31 casts (28%). The hepatocaval confluence was studied and the tributary‐free part of the SRHV trunk before it entered the inferior vena cava was measured. The tributary‐free part of the SRHV was longer than 1 cm in 77% of the casts. Anastomoses between the terminal tributaries of the veins involved in the drainage of the right side of the liver were also investigated.

Atlas of applied internal liver anatomy

Material and Methods.- Preparation of the Models of the Upper Part of the Abdominal Cavity.- Preparation of the Corrosive Casts of the Hollow Structures of the Liver.- Portal Vein System.- Portal Vein Branching in the Hepatic Porta.- Right Main Portal Branch - The Right Portal Vein.- Right Anterior Sectorial (Paramedian, Anteromedian) Branch.- Veins to Segment V.- Veins to Segment VIII.- Right Posterior Sectorial (Posterolateral, Lateral) Branch.- Veins to Segment VI.- Veins to Segment VII.- Left Main Portal Branch - The Left Portal Vein.- Horizontal Part of the Left Main Portal Branch - Extrahepatic Portion of the Left Portal Vein.- Veins to Segment II.- Umbilical Part of the Left Main Portal Branch - Intrahepatic Portion of the Left Portal Vein.- Veins to Segment III.- Veins to Segment IV.- Veins to Segment I.- Veins to Segment IX (Right Paracaval Region).- Figures Illustrating the Portal Vein System.- Hepatic Artery System.- Proper Hepatic Artery.- Right Hepatic Artery.- Left Hepatic Artery.- Middle Hepatic Artery.- Accessory Right Hepatic Artery.- Accessory Left Hepatic Artery.- Right Hepatic Artery Originating from the Superior Mesenteric Artery.- Left Hepatic Artery Originating from the Left Gastric Artery.- Arteries to Liver Sectors and Segments.- Figures Illustrating the Hepatic Artery System.- Biliary System.- Bile Duct - The Hepatic Duct Junction.- Right Hepatic Duct.- Right Anterior (Paramedian) Sectorial Duct.- Bile Ducts from Segment V.- Bile Ducts from Segment VIII.- Right Posterior (Posterolateral) Sectorial Duct.- Bile Ducts from Segment VI.- Bile Ducts from Segment VII.- Left Hepatic Duct.- Bile Ducts from Segment II.- Bile Ducts from Segment III.- Bile Ducts from Segment IV.- Bile Ducts from Segment I.- Bile Ducts from Segment IX (Right Paracaval Region).- Figures Illustrating the Biliary System.- Hepatic Vein System.- Right Hepatic Veins.- One Right Hepatic Vein.- Two Right Hepatic Veins.- Three Right Hepatic Veins.- Middle Hepatic Vein.- Umbilical Hepatic Vein.- Left Hepatic Vein.- Short Subhepatic Veins.- Figures Illustrating the Hepatic Vein System.- References.- Index of Figures.

DEEP INFERIOR EPIGASTRIC PERFORATOR FLAP: AN ANATOMICAL STUDY OF THE PERFORATORS AND LOCAL VASCULAR DIFFERENCES

The objective of this study was to determine precise localization and external diameter of the lower abdominal wall perforators as well as to investigate some vascularity differences between the same parts of perfusion zones II and III according to Hartrampf perfusion zones. The study was performed on 10 fresh cadavers (20 hemiabdomens) using the gelatin injection technique. All perforators were identified, and their localization and diameter were noted. Measurements were made at the level of the fascia. We noted localization and diameter of arteries on cross‐sectional planes of either part of the flap. The median sum of the external diameter of all arteries in zone I was 17.01 mm. The median sum of the external diameter of all arteries in the medial 1/3 part of zone III was 4.17 mm, and in the medial 1/3 part of zone II, it was 0.96 mm. The median sum of the external diameter of all arteries in the intermediary 1/3 part of zone III was 2.16 mm, whereas in the intermediary 1/3 part of zone II, it was 0.81 mm. Significant differences were recorded between proximal and middle horizontal regions of zones II and III and between medial vertical part of zone III and medial vertical part of zone II. Anastomoses between zones I and II are considerably smaller compared with anastomoses between zones I and III. The best vascularized parts of the lower abdominal wall were perfusion zone I, then the inner 2/3 of zone III and medial 1/3 of zone II.

Anatomy of the ligamentum venosum arantii and its contribution to the left hepatic vein and common trunk control. A study on cadaveric livers.

Background: The control of the left hepatic vein (LHV) and the common trunk of the middle hepatic vein (MHV) and LHV (CT) is considered difficult during liver resection and could be improved by detailed knowledge on the ligamentum venosum Arantii (LV). Aim: The aim of this study was to describe the LV and its connections to the LHV and the CT and to present surgical relevance of the obtained data. Material and Methods: During autopsy of 50 cadavers of both sexes, the LV was exposed, measured and then dissected, simulating a surgical maneuver to facilitate the approach to the LHV and CT. The extrahepatic parts of the LHV, MHV and CT were measured. Results: The LV was 52–70 mm long and 5–8 mm thick. It had a fibrotic structure and was not patent in 96% of the cases. The extrahepatic part of the LHV measured 3–19 mm, that of the MHV 3–18 mm and that of the CT 4–15 mm. Conclusion: LV dissection facilitated extraparenchymatous clamping of the hepatic veins: the extrahepatic parts of the LHV and CT measured >3 mm in 86 and 84% of the cases, respectively.

Portal Vein System

It can be claimed that the portal vein system is the most important system of the internal liver structure, not only because it determines the course of other systems and the internal architecture of the liver, but also because it represents — together with the hepatic vein system — the basis for functional (surgical) liver anatomy. The valveless portal vein, a vein unique in the human body, which gathers practically all the blood from the stomach, small and large intestines, spleen and pancreas through the afferent superior and inferior mesenteric veins and the splenic vein, becomes the main afferent vessel to the liver after division in the hepatic porta. It seems that the hepatic artery mainly helps the portal vein to perfuse the liver by providing additional necessary pressure through its arterioles, thereby providing sufficient push to the blood in the liver sinusoids. Blood flow and the oxygenation of the liver tissue depend mainly on the portal vein.

Anatomy and Surgical Relevance of the Hepatocaval Ligament

Background: There are nearly no data on the hepatocaval ligament (HCL) in the anatomical literature, though it is of high importance during surgery of the right hemiliver. Aim: The aim of this study was to determine the frequency of the HCL, its description and its relations to the inferior vena cava (IVC) and the right hepatic vein (RHV) as well as the evaluation of the surgical relevance of the data obtained. Materials and Methods: The dissection of the livers of 43 cadavers of both sexes was performed and the presence of the HCL was established. The ligament was measured and dissected to expose the IVC and the extrahepatic part of the RHV from its inflow to the liver parenchyma. Results: The ligament was present in 77% of the cases. It was 12–35 mm long and 3–18 mm wide. The extrahepatic part of the RHV was 2–12 mm long. Conclusion: Dissection of the HCL revealed the terminal extrahepatic part of the RHV in all cases. Anatomically, resection of the right hemiliver with elective vascular control would be possible in 85% of the cases in which the length of the extrahepatic part of the RHV was ≧3 mm.

Congruence between the courses of the biliary ductal and the hepatic arterial systems.

The development of diagnostic methods and new surgical techniques means it is increasingly important to have accurate knowledge of the anatomy of the hepatic arterial and biliary systems, including their variations, at extrahepatic and intrahepatic levels. The aim of this study was to determine how often the biliary and arterial systems run together and branch in the same pattern. Fifty corrosion casts of the liver were used to analyse the origin and branching patterns of arteries and the confluences of bile ducts. In addition, both systems were analysed to determine the frequency of normal arrangements and variations. The congruence of the course of both systems was analysed at the porta hepatis and in the left and right hemilivers down to the segmental level. A congruent course of the arterial and the biliary systems was identified in 38% of cases at the porta hepatis, in 32% of cases in the left hemiliver and in 30% of the right hemiliver. The congruence of both systems at the porta hepatis and in the left hemiliver was identified only if both systems were normal. In the right hemiliver, however, the congruence of both systems was identified even when both systems were variable, but only in 10% of cases. The results of the study show that, on the basis of knowledge of the course and branching of one system, the other system cannot be predicted.

Hepatic Vein System

In general, the hepatic veins drain the liver through suprahepatic segmentation. As described by Couinaud, suprahepatic segmentation is exactly reflected by the external anatomical morphology of the liver. Consequently, the left hepatic vein drains the anatomic left lobe and the middle and right hepatic veins drain the right lobe, while the caudate lobe is the drainage region of short subhepatic veins.

Impacts to the chest of PMHSs - Influence of impact location and load distribution on chest response

The chest response of the human body has been studied for several load conditions, but is not well known in the case of steering wheel rim-to-chest impact in heavy goods vehicle frontal collisions. The aim of this study was to determine the response of the human chest in a set of simulated steering wheel impacts. PMHS tests were carried out and analysed. The steering wheel load pattern was represented by a rigid pendulum with a straight bar-shaped front. A crash test dummy chest calibration pendulum was utilised for comparison. In this study, a set of rigid bar impacts were directed at various heights of the chest, spanning approximately 120mm around the fourth intercostal space. The impact energy was set below a level estimated to cause rib fracture. The analysed results consist of responses, evaluated with respect to differences in the impacting shape and impact heights on compression and viscous criteria chest injury responses. The results showed that the bar impacts consistently produced lesser scaled chest compressions than the hub; the Middle bar responses were around 90% of the hub responses. A superior bar impact provided lesser chest compression; the average response was 86% of the Middle bar response. For inferior bar impacts, the chest compression response was 116% of the chest compression in the middle. The damping properties of the chest caused the compression to decrease in the high speed bar impacts to 88% of that in low speed impacts. From the analysis it could be concluded that the bar impact shape provides lower chest criteria responses compared to the hub. Further, the bar responses are dependent on the impact location of the chest. Inertial and viscous effects of the upper body affect the responses. The results can be used to assess the responses of human substitutes such as anthropomorphic test devices and finite element human body models, which will benefit the development process of heavy goods vehicle safety systems.

Hepatic Artery System

The source of hepatic arteries is determined before they enter the hepatoduodenal ligament. The arteries to the liver originate from three main sources: the celiac trunk, the left gastric artery and the superior mesenteric artery. Their embryological origin thus explains the relatively frequent presence of a left hepatic artery (dominant or accessory) stemming from the left gastric artery, as well as the “replacing” right hepatic artery and the “accessory” right hepatic artery originating from the superior mesenteric artery. There have been cases described where the right hepatic artery originated from the superior mesenteric artery, the middle hepatic artery from the celiac trunk and the left hepatic artery from the left gastric artery. In such cases surgeons performing liver transplantation had to use the aortic patch folding technique (Carrel patch), excising a patch of aorta together with the origin of the celiac trunk and the mesenteric arteries to facilitate an efficient anastomosis in the graft recipient. The common hepatic artery classically stems from the celiac trunk. When it gives off a gastroduodenal artery and sometimes a right gastric artery it becomes the proper hepatic artery. Sometimes the common hepatic artery derives from the hepatomesenteric trunk as the only artery to the liver and it is then a replacing type artery.