Portal hypertension

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Portal hypertension

The portal pressure, ie the pressure that is measured inside the portal vein of the liver, which represents the supply path of nutrients from the intestine and the main source of circulation for the liver (with flow of 1-1.5 l / min), in importance before the hepatic artery, it is 5-10 mmHg. Hypertension is determined, therefore, by an increase in hepatic resistance and collateral port. This resistance is modulated by an increase in intrahepatic endothelin levels, a potent vasoconstrictor and a reduction in levels of hepatic nitric oxide, a vasodilator. The hepatic resistance can be modulated, again, by cells like my perivenular fibroblasts and presinusoidal and of the smooth muscle component of the collateral vessels. The fact is that 50% of patients with cirrhosis will develop portal hypertension and therefore esophageal varices, while this risk appears to be reduced to 30% in patients with chronic HCV hepatitis.
Portal hypertension is defined as any increase in pressure> 12mmHg. When the portal pressure increases, a pressure gradient is created between the portal system and that of the hepatic veins above the normal range of 2-6 mmHg. The main problem that creates portal hypertension is the formation of discharges to the flow that are defined as "collateral circles" and are made up of varices, from venous vessels, that is, that is loaded with excessive pressure and, so to speak, are exhausted and they become "varices". The main varices are the esophageal varices, responsible for dangerous bleeding when, due to excess of pressure and the effect of the acid from the stomach, they break with a conspicuous emission of blood from the mouth that is defined hematemesis, ie vomiting of blood. Furthermore, congestive gastropathy, called "watery-melon" type congestion, is created.

Causes of hypertension

Prearatic causes, that is, resulting from conditions that occur before the liver:
thrombosis of the portal vein
cavernous transformation of the portal vein
splecnica arteriovenous fistula with noticeable flow
tropical splenomegaly

Intrahepatic causes. (alongside the "mosaic" appearance of an endoscopic gastric mucosa in a patient suffering from cirrhosis with portal hypertension)

Endoscopy: mosaic aspect of the gastric mucosa
in case of congestion of the splanchial circle for
portal hypertension

a) Presinusoidal, ie it affects portal venules:
schistosomiasis
congenital hepatic fibrosis
sarcoidosis
primary biliary cirrhosis
myeloproliferative diseases
cancer diseases
Wilson's disease
hemochromatosis
amyloidosis
toxic agents, copper, arsenic, vinyl chloride, 6-mercaptopurine

b) Sinusoidal

All causes of cirrhosis
Acute alcoholic hepatitis
Fatty alcohol liver
Vitamin A intoxication
Systemic mastocytosis
Peliosis rheumatic
drugs

c) Post-sinusoidal

Thrombosis from the hepatic vein
Budd-Chiari Syndrome
Neoplastic invasion of the vessels
Obstruction of the vena cava
Heart disease with decompensation and stasis
Constrictive pericarditis
Mitral regurgitation

Therapy

Drugs used in the control of portal hypertension are mainly:
- Vasoconstrictors (vasopressin, somatostatin and beta-blockers) that reduce venous flow and portal pressure (see also esophageal variceal hemorrhage)
- Vasodilators (nitroglycerin, long acting nitrates, prazosin) that modify the action of my perivenular fibroblasts, but their use is limited by the considerable side effects.