Investigation of portal hypertension.

I WILL present a personal approach to the problem of portal hypertension, without attempting to cover the subject exhaustively, but emphasizing what I feel to be the important points for consideration in relation to the management of patients. Causes of portal hypertension The most important cause of portal hyperten-sion is chronic liver disease which usually implies cirrhosis of the liver. The second cause of portal hypertension to be considered is obstruction to the portal vein before its entry to the liver, or in some cases obstruction to the splenic vein producing hyper-tension in only the splenic portion of the portal venous system. A third and less important cause of portal hypertension is obstruction to the hepatic vein, either to the major hepatic veins as in Chiari's syndrome, or obstruction to the intrahepatic tributaries of the hepatic veins as in the veno-occlusive disease found in some tropical areas. A similar variety of portal hypertension is caused by obstruction to the flow of blood from a patent hepatic vein as is produced by occlusion of the inferior vena cava, or by constrictive pericarditis or by disease of the tricuspid valve. These three causes of portal hypertension can be looked at in another way. Cirrhosis may be regarded as portal hypertension due to a lesion within the liver, portal vein obstruction may be regarded as portal hypertension due to a pre-hepatic cause, and obstruction to the hepatic vein may be regarded as post-hepatic portal hyper-tension. TABLE 1 Causes of portal hypertension Cirrhosis Portal vein obstruction Hepatic vein obstruction Idiopathic Secondary Table 1 lists the mechanical causes of portal hypertension just described, and for the sake of completeness two other causes are added. The fourth cause of portal hypertension listed is idiopathic. This implies that chronic liver disease is not present, that there is no block in the extra-hepatic portal venous system and no block to outflow from the hepatic veins. A number of possible mechanisms for the portal hypertension have been postulated, including portal-vein spasm, an increase in portal venous blood-flow due for example to abnormal vessels in the stomach, or abnormal communications between branches of the hepatic artery and the portal vein within the liver. All these are difficult to substantiate and would be even more difficult to treat. However, one rare cause of portal hypertension which is more easy to substantiate and to treat is an arterio-venous aneurysm between major arteries …