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Portal Hypertension Definition
Portal Hypertension – high pressure in the portal vein, the large blood vessel that carries blood from the abdominal organs to the liver. Cirrhosis, in which scar tissue replaces liver tissue as a consequence of repeated inflammation, is the primary cause of portal hypertension. Right heart failure also can cause portal hypertension.
About 40 percent of the blood that enters the liver does so through the portal vein. Blood drains into the portal vein from the digestive organs of the abdomen, carrying nutrients and metabolic wastes to the liver for processing. Though blood flows through the arteries under high pressure, the pressure within the veins is low and venous blood flow mostly relies on a combination of lower resistance, gravity, and valves within the veins to prevent backflow.
The spongy tissue of a healthy liver accepts blood flow from the portal vein in a smooth process, literally soaking in the blood and channeling it through the thousands of lobules that form the liver’s interior architecture. The solid structure of scar tissue does not absorb blood like the spongy tissue of the healthy liver, and blood must force its way around. The resistance that results causes the pressure within the portal vein to rise.
When scarring becomes severe, as in cirrhosis, the liver cannot contain the amount of blood attempting to enter and the blood backs up into the portal vein as well as the veins that feed into the portal vein. The walls of the portal vein stiffen against the resistance, which further raises pressure. Eventually the consequence of portal hypertension is twofold: blood cannot circulate through the liver and the supporting veins that feed into the portal vein distend and weaken. These varicose veins typically protrude into the esophagus (esophageal varices) and often bleed.
Symptoms of Portal Hypertension and Diagnostic Path
The key symptoms suggesting portal hypertension are those of liver disease and may include
- Jaundice, a yellowish discoloration of the skin
- Pruritus (widespread itching)
- Fatigue and weakness
- Ascites, an accumulation fluid in the abdomen
- Evidence of gastrointestinal bleeding, which may appear as vomiting blood (hematemesis) or passing dark stools (melena)
The doctor’s examination can usually detect numerous signs of portal hypertension, such as abnormal pulse, low systemic blood pressure (hypotension), and evidence of altered venous blood flow in the abdomen and lower extremities. The diagnostic path includes imaging procedures that can show the flow of blood through the liver, such as Doppler ultrasound, computed tomography (ct) scan, or magnetic resonance imaging (mri). Endoscopic examination of the esophagus reveals esophageal varices, a conclusive sign of portal hypertension.
Portal Hypertension Treatment Options and Outlook
Bleeding esophageal varices require immediate medical attention. The gastroenterologist often can cauterize these during endoscopy. Vasodilator medications that relax the blood vessels, such as nitrates and beta blockers, relieve mild to moderate portal hypertension. Moderate to severe portal hypertension requires surgical intervention. Shunts can help redirect the flow of blood into the liver and lower portal vein pressure. Sometimes removing the spleen (splenectomy) and blood vessels surrounding the esophagus is necessary to control esophageal varices. The only curative treatment is liver transplantation, which, because donor organs are so limited, is a treatment of final resort when other therapies fail and liver failure becomes life-threatening.
Medications and intermediary surgical procedures such as shunts can successfully manage portal hypertension in many people, allowing good quality of life.
Risk Factors and Preventive Measures
Chronic liver disease and heart disease are the primary risk factors for portal hypertension. Lifestyle measures to minimize these conditions, and appropriate treatments to manage them when they do occur, significantly reduce the likelihood that portal hypertension will develop.
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