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Portal hypertension - increased pressure in the portal portal vein, caused by blood flow disorders of various origins and localization - in portal vessels, hepatic veins and inferior vena cava.
When the amount of portal blood flowing to the liver decreases in connection with the development of collateral circulation, the role of the hepatic artery increases. The liver decreases in volume, its ability to regenerate decreases. This is probably due to inadequate intake of hepatotropic factors, including insulin and glucagon, produced by the pancreas.
Portal hypertension is most often caused by cirrhosis of the liver (in developed countries), schistosomiasis (in endemic areas) or vascular disorders in the liver. Effects include varicose veins of the esophagus and portosystemic encephalopathy. The diagnosis is based on clinical data, the results of instrumental examination and endoscopy. Treatment includes endoscopic prophylaxis of gastrointestinal bleeding, drug therapy, a combination of these methods and, sometimes, portocaval shunting.
The portal vein, formed by the upper bramble and splenic veins, delivers blood from the organs of the abdominal cavity, gastrointestinal tract, spleen and pancreas to the liver. Within the reticuloendothelial blood vessels (sinusoids), blood from the terminal portal venules of the liver is mixed with arterial blood. Blood from sinusoids through the hepatic veins enters the inferior vena cava.
Normally, portal pressure is 5-10 mm Hg. Art. (7-14 cm Hg), it exceeds the pressure in the inferior vena cava by 4-5 mm Hg. Art. (portal venous gradient). Higher rates are characterized as portal hypertension.
Causes and pathophysiology of portal hypertension
Portal hypertension arises mainly due to increased resistance to blood flow as a result of directly pathological processes in the liver, impaired patency of the splenic or portal veins or impaired venous outflow from the hepatic veins. Increased volume of incoming blood is a rare cause, although it often contributes to portal hypertension in liver cirrhosis and hematological diseases accompanied by severe splenomegaly.
Classification and common causes of portal hypertension
Thrombosis of the portal or splenic vein
Increase in portal blood flow: arteriovenous fistula, expressed splenomegaly with hematological diseases
Presinusoidal: schistosomiasis, other periportal lesions (eg, primary biliary cirrhosis, sarcoidosis, congenital liver fibrosis), idiopathic portal hypertension
Sinusoidal: cirrhosis (of any etiology).
Post-sinusoidal: occlusal lesions of venules
Thrombosis of hepatic veins (Badd-Chiari syndrome) Obstruction of the inferior vena cava
Difficult inflow to the right heart (for example, squeezing pericarditis, restrictive cardiomyopathy)
Cirrhosis of the liver is accompanied by tissue fibrosis and regeneration, which increase resistance in sinusoids and terminal portal venules. At the same time, other potentially reversible factors, such as the contractility of sinusoidal cells, the production of vasoactive substances (eg, endothelium, nitric oxide), various system mediators of arteriolar resistance, and possibly the swelling of hepatocytes, are important.
Over time, portal hypertension leads to the development of portosystemic venous collaterals. They contribute to some reduction in pressure in the portal vein, but also the development of complications. Extended convoluted submucosal vessels (varicose veins) of the distal esophagus and sometimes the bottom of the stomach can tear, causing sudden catastrophic gastrointestinal bleeding. Bleeding develops rarely if the portal pressure gradient is less than 12 mm Hg. Art. Stasis of blood in the vessels of the gastric mucosa (gastropathy with portal hypertension) can cause acute or chronic bleeding regardless of varicose veins. The common is the visible widening of the abdominal wall collaterals; the veins that radiate away from the navel (the head of the jellyfish) are more rare and indicate a significant flow of the umbilical and paraumbilical veins. Collaterals around the rectum can lead to varicose veins of the rectum and bleeding.
Portosystemic collaterals shunt the blood past the liver. Thus, with an increase in portal blood flow, less blood reaches the liver. In addition, toxic substances from the intestine enter the systemic circulation directly, participating in the development of portosystemic encephalopathy. Venous congestion in the internal organs with portal hypertension contributes to the development of ascites as a result of the phenomenon of Starling. Splenomegaly and hypersplenism are usually the result of increased pressure in the splenic vein. The result can be thrombocytopenia, leukopenia and, more rarely, hemolytic anemia.
Portal hypertension is often associated with hyperdynamic circulation. The mechanisms are complex and probably involve a rise in the sympathetic tone, the formation of nitric oxide and other endogenous vasodilators, as well as an increase in the activity of humoral factors (for example, glucagon) in the pathological process.
Symptoms of portal hypertension
Portal hypertension develops asymptomatically; Symptoms and signs are the result of complications. The most dangerous is acute bleeding from varicose veins. Patients usually complain of sudden, often massive, painless bleeding from the upper gastrointestinal tract. Bleeding in gastropathy with portal hypertension is often subacute or chronic. There may be ascites, splenomegaly or portosystemic encephalopathy.
Diagnosis of portal hypertension
In patients with chronic liver disease, portal hypertension provides for the presence of expanded collaterals, splenomegaly, ascites or portosystemic encephalopathy. For confirmation, a direct portal pressure measurement is necessary for jugular vein catheterization, which is an invasive procedure and is usually not performed. In case of suspected cirrhosis of the liver, instrumental examination helps. Ultrasonography or CG often indicates enlarged vagina-associated collaterals, and Doppler ultrasound can assess the condition of the portal vein and the rate of blood flow.
Varicose veins of the esophagus and stomach, as well as gastropathy with portal hypertension, are best diagnosed endoscopically, which allows you to predict bleeding from varicose veins of the esophagus and stomach (for example, red spots on varicose veins).
Prognosis and treatment of portal hypertension
Mortality in acute bleeding from varicose veins may exceed 50%. The prognosis depends on the reserve capacity of the liver and the severity of the bleeding. For survivors, the risk of bleeding in the next 1-2 years is 50 to 75%. Endoscopic and medication therapy reduces the risk of bleeding, but only slightly increases life expectancy.
Long-term therapy of gastroesophageal varicose veins, which are the source of bleeding, consists in phased endoscopic ligation or sclerotherapy with the purpose of obliteration of the nodes followed by mandatory monthly endoscopic control. Ligation of varicose veins is more preferable than sclerotherapy, because of the lower risk.
Long-term drug therapy for varicose veins of the esophagus and stomach, complicated by bleeding, includes b-blockers; these drugs reduce portal pressure primarily due to a decrease in portal blood flow, although the effect of their use is not always constant. Preferred is the use of propranolol (40 mg-80 mg orally 2 times a day) or nadolol (40-160 mg once daily) in titrating doses, which reduce the heart rate by approximately 25%. Addition of isosorbide mononitrate 10 mg-20 mg orally 2 times a day can further reduce portal pressure. The combined use of long-term endoscopic and drug therapy is a more effective approach. Patients in whom this treatment is ineffective or not shown need trans- gular intrahepatic portal-systemic shunting ( TIPS) or portocaval shunting. With the help of TIPS, a stent is established between the portal and hepatic venous blood flow within the liver. At the same time, TIPS is safer than portocaval bypass, in terms of mortality, especially in conditions of acute bleeding. However, over time, bleeding is often repeated due to stenosis of the stent or its obstruction. The long-term effect is unknown. A certain group of patients showed liver transplantation.
In patients with varicose veins, which was not complicated by bleeding, the use of b-blockers reduces its risk.
With gastropathy, complicated by bleeding, drug therapy can be used to reduce portal pressure. Indications for shunting should be considered with ineffective drug therapy, but its results may be less positive than shunting with bleeding from varicose veins of the esophagus.
Because this rarely causes clinical problems, hypersplenism does not require any specific treatment and splenectomy should be avoided.
Endoscopic sclerotherapy is a method that is considered the "gold standard" of emergency treatment of bleeding from esophageal varices. In skilled hands, it allows you to stop bleeding, but usually to improve the review of a tamponade and prescribe somatostatin. Thrombosis of varicose-dilated veins is achieved by introducing into them an sclerosing solution through an endoscope. Data on the effectiveness of routine sclerotherapy with varicose veins of the esophagus are inconsistent.