Hepatic segments

Uchida H, Ohishi H, Matsuo N (1990) Transcatheter hepatic segmental arterial embolization using Lipiodol mixed with an anticancer drug and Gelfoam particles for hepatocellular carcinoma. Cardiovasc Intervent Radiol 13 140... 

Fig. 6.17 Liver metastasis (subcostal section) hypoechoic fringe (arrow) wide, more hyperechoic margin and hypoechoic central colliquation ( bull s-eye ). Structural inhomogeneity of the remaining hepatic segments...

Fig. 20.1. Hepatic segmental anatomy. RHP right hepatic vein MHP middle hepatic vein LHV left hepatic vein RPV right portal vein LPV left portal vein...

Intrahepatic collateral pathways can develop in cirrhotic patients with portal hypertension. Park et al. (1990) classified them in 4 types type 1 when there is a vessel of large diameter that connects the right portal branch with the inferior vena cava type 2 when there are one or more communications between the portal vein and hepatic veins in one hepatic segment type 3 when there is an aneurysmatic shunt between peripheral branches of the portal vein and hepatic veins type 4 when there are multiple communications between portal peripheral branches and hepatic vein branches in both hepatic lobes. 

When the infrarenal IVC is occluded, the hepatic segment of the IVC is invariably patent. This area is most conveniently accessed via one of the hepatic veins with subsequent catheterization of the IVC and right atrium. The middle hepatic vein is ideal and can be targeted with ultrasound. After access, the tunnel or pocket are typically fashioned on the chest wall for easy use (Azizkhan 1992). 

Chemoembolization and Portal Vein Occlusion In the presence of portal vein invasion, the risks of hepatic complications following chemoembolization are increased and the survival rates are decreased. In a series of 110 patients with HCC invading major portal branches, Chung et al. (1995) reported 1-, 2-, and 3-year survival rates of 30%, 18%, and 9%, respectively. Complete or partial response (22/33) and survival times (22 months) were significantly longer in those patients with disease limited to one or two hepatic segments. In 77 patients with more extensive hepatic involvement, the mean survival time was 5 months. Ten patients in this latter group developed hepatic insufficiency and three deaths occurred within 1 month after treatment. 

Jung G, Krahe T, Krug B, et al (1996) Delineation of segmental liver anatomy. Comparison of ultrasonography, spiral CT and MR imaging for preoperative localization of focal liver lesions to specifc hepatic segments. Acta Radiol 37 691-695... 

Bile is produced continuously by the liver bile salts are secreted by the hepatocytes and the water, sodium bicarbonate, and other inorganic salts are added by the cells of the bile ducts within the liver. The bile is then transported by way of the common bile duct to the duodenum. Bile facilitates fat digestion and absorption throughout the length of the small intestine. In the terminal region of the ileum, the final segment of the small intestine, the bile salts are actively reabsorbed into the blood, returned to the liver by way of the hepatic portal system, and resecreted into the bile. This recycling of the bile salts from the small intestine back to the liver is referred to as enterohepatic circulation. 

This theory was further explored in an anaesthetised pig model, which facilitated portal vein and bile sampling [86], However, the hepatic extraction ratio and the biliary clearance of fexofenadine were unaffected by verapamil in the pig model. The question as to why verapamil/ketoconazole increase the fraction absorbed (i.e. based on appearance kinetics) and yet the fraction absorbed estimated on the basis of disappearance kinetics (i.e. /err) for the intestinal segment appears unchanged remains to be explored and most likely reflect multiple interplay between absorptive and efflux drug transporters in the intestinal tissue. 

HBV is transmitted among humans and is manifested as a chronic infection that debilitates infected individuals and may cause severe liver damage, primary carcinoma, and ultimately death. Although in most cases the patients recover, there are large segments of the population that have chronic hepatitis B (especially in African and Asian countries) and can transmit the disease as a pandemic. 

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