Một xơ gan tim thật sự là rất hiếm. Cơ chế (Hình 11,20) tình trạng thiếu oxy gây ra sự thoái hóa của các tế bào gan khu 3, giãn nở của xoang và làm chậm bài tiết mật. Endotoxins khuếch tán qua thành ruột vào máu cổng thông tin có thể làm tăng thêm hiệu ứng này | 202 Chapter 11 Bilirubin release from infarcts Zone 3 congestion and necrosis and tissue congestion Bilirubin overload JAUNDICE Fig. . Mechanisms of hepatic jaundice developing in patients with cardiac failure. complex cirrhosis results. A true cardiac cirrhosis is extremely rare. Mechanism fig. Hypoxia causes degeneration of the zone 3 liver cells dilatation of sinusoids and slowing of bile secretion. Endotoxins diffusing through the intestinal wall into the portal blood may augment this effect 27 . The liver attempts to compensate by increasing the oxygen extracted as the blood flows across the sinusoidal bed. Collagenosis of Disse s space may play a minor role in impairing oxygen diffusion. Necrosis correlates with a low cardiac output 1 . The hepatic venous pressure increases and this correlates with zone 3 congestion 1 . Thrombosis begins in the sinusoids and may propagate to the hepatic veins with secondary local portal vein thrombosis ischaemia parenchymal loss and fibrosis 30 . Clinical features Mild jaundice is common but deeper icterus is rare and associated with chronic congestive failure. In hospital inpatients cardio-respiratory disease is the commonest cause of a raised serum bilirubin level. Oedematous areas escape for bilirubin is protein-bound and does not enter oedema fluid with a low protein content. Jaundice is partly hepatic for the greater the extent of zone 3 necrosis the deeper the icterus fig. 26 . Bilirubin released from infarcts or simply from pulmonary congestion provides an overload on the anoxic liver. Patients in cardiac failure who become jaundiced with minimal hepato-cellular damage usually have pulmonary infarction 26 . The serum shows unconjugated bilirubinaemia. The patient may complain of right abdominal pain probably due to stretching of the capsule of the enlarged Fig. . Possible mechanisms of the hepatic histological changes in heart failure. liver. The firm smooth tender lower edge may reach the .
