Portal hypertension is an increase in the blood pressure within a system of veins called the portal venous system.
Normal portal pressure is generally considered to be between 5 and 10 mm Hg. Once the portal pressure rises to 12 mm, complications arise.
Relevant Anatomy and Physiology
The portal venous system refers to the vessels involved in the drainage of the capillary beds of the gastrointestinal tract and spleen. Veins from the stomach, intestine, spleen, and pancreas merge into the portal vein. Portal vein branches into smaller vessels and travel through the liver.
The portal vein is formed by the union of superior mesenteric vein and the splenic vein, behind the neck of the pancreas.
Any obstruction to the vessels in the liver leads to improper inflow of the blood through the liver. This leads to high pressure in the portal system.
Increased pressure in the portal system causes the development of large swollen veins, termed as varices, in the esophagus, stomach, rectum or umbilical area.
The portal vein carries approximately 1500 mL/min of blood from the small and large bowel, the spleen, and the stomach to the liver.
In response to this rise in pressure, collateral circulation develops in an attempt to divert the obstructed blood flow to the systemic veins.
These are called portosystemic collaterals and form by the opening and dilatation of preexisting vascular channels connecting the portal venous system and the superior and inferior vena cava.
The most important portosystemic anastomoses are the gastroesophageal collaterals which drain into the azygos vein.
Causes of Portal Hypertension
Depending on the site of obstruction to the flow, the portal hypertension cause could be prehepatic, hepatic and post hepatic.
The cause of obstruction is before the venous blood enters the liver
- Portal vein thrombosis
The obstruction is in the liver itself
- Cirrhosis of liver
- Non-cirrhosis portal fibrosis
- Arteriovenous fistulae
- Primary biliary cirrhosis
- Toxicity- Vinyl chloride, copper, arsenic, etc.
The obstruction is in the system after the blood leaves the liver towards the heart
- Budd Chiari syndrome
- Veno-occlusive disease
- Constrictive pericarditis
- Right-sided heart failure
Symptoms and Signs of Portal Hypertension
A person might have portal hypertension without any manifestation in the initial stages. Portal hypertension should be suspected in patients with liver diseases that could progress to cirrhosis.
When manifested, the symptoms of portal hypertension could be in the following forms
- Development of varices at esophagus, stomach, anorectal region, and caput medusa. Varices especially esophageal varices may rupture causing blood in vomiting [hematemesis] or melena [black tarry stools due to bleeding]
In a patient with portal hypertension, the effort should be also to search for a cause of the condition.
The patient should be enquired about the history of
- Previous jaundice
- History of transfusions of blood or blood products
- Family history of hereditary liver disease
- Alcohol abuse
- High-risk sexual behavior
On examination, the patient may have dilated veins in the anterior abdominal wall or flanks, caput medusa, rectal hemorrhoids, ascites, and paraumbilical hernia
Presence of liver disease is suggested by
Symptoms of liver disease include the following:
- Weakness, tiredness, and malaise
- Sudden and massive bleeding
- Spontaneous bleeding or easy bruising
- Nausea and vomiting
- Weight loss
- Edema and abdominal swelling
- Symptoms of encephalopathy
- Spider angiomas
- Palmar erythema and leukonychia
- Testicular atrophy
Sometimes, the patient may present with complications of portal hypertension, which are
- Hematemesis or melena – May indicate gastroesophageal variceal bleeding or bleeding from portal gastropathy [Melena means vomiting the blood,
- Mental status changes like lethargy, increased irritability, and altered sleep patterns [suggestive of encephalopathy]
- Increasing abdominal girth may point towards the presence of ascites
- Hematochezia – bleeding in the lower intestinal region, results in passage of fresh blood in stools
The patient of portal hypertension may have signs of hyperdynamic circulation which are
- Bounding pulses
- Warm, well-perfused extremities
- Arterial hypotension
- Flow murmur in the heart
Diagnosis of Portal Hypertension
Laboratory studies are directed towards investigating the etiologies of cirrhosis, which is the most common cause of portal hypertension. The rate and volume of bleeding in the patient should be assessed.
Routine lab studies of the patient including complete blood count, liver function tests and renal function tests should be done. Prothrombin time and measure serum electrolyte levels.
CBC may show
- Decrease in leucocyte count
- Decreease in platelet count
- In the presence of hypersplenism, pancytopenia may occur.
Liver function tests may be abnormal but a normal liver function test may not suggest the absence of abnormal liver.
Coagulation studies include Prothrombin Time, partial thromboplastin time, and international normalized ratio may be altered because the synthetic function of the liver is impaired in cirrhotic patients.
Renal Function Tests
Blood urea nitrogen and creatinine levels may be elevated in patients with esophageal bleeding.
In the case of viral hepatitis, the patient may be found positive for a particular virus.
Duplex Doppler Ultrasonography
Ultrasound in portal hypertension may reveal –
- Nodular liver surface
- Collateral circulation
Findings suggestive of portal hypertension include collaterals arising from the portal system and dilatation of the inferior vena cava. MRI provides information similar to that from CT scanning.
Hepatic Venous Pressure Gradient
It is an indirect measurement of portal venous pressure. It is used to monitor the disease progression, response to treatment and progression of the disease.
It is measured by inserting a fluid-filled balloon introduced into the femoral or internal jugular vein and advanced into a branch of the hepatic vein fluoroscopy.
It is now considered to be the gold standard for assessment of the severity of portal hypertension.
A value greater than 5mm Hg is considered significant and the disease becomes clinically apparent when the value exceeds 10-12 mm Hg.
Upper Gastrointestinal Endoscopy
Endoscopy for evaluation of varices is considered the gold standard test.
Endoscopic examination of the esophagus, stomach and duodenum is used to assess varices and severity of bleed if any.
Endoscopy is also used for periodic surveillance endoscopy in patients with cirrhosis.
Ultrasonography-based transient elastography is a new noninvasive technology to detect clinically significant portal hypertension but requires further studies.
Emergency Treatment in Cases of Portal Hypertension
Severe variceal bleed can be life-threatening and needs immediate resuscitation and restoration of fluid volume.
While waiting for blood reports, fluid should be started through a wide bore cannula. If the bleeding is severe enough, early measures to control bleeding episodes should be done and blood transfusion should be carried out. If indicated correct clotting factor deficiencies with fresh frozen plasma, fresh blood, and vitamin K.
A nasogastric tube should be inserted to decompress the stomach and assess the severity of the bleeding.
The airway should be protected, especially in unconscious patients to prevent aspiration of the blood into the lungs.
Control of Bleeding
Variceal bleeding may cease spontaneously in as many as 50% of patients. Rebleeding is known to occur in 40% of patients within 6 weeks.
Following resuscitation, treatment of acute variceal bleeding includes control of bleeding and prevention of early recurrence.
All patients with cirrhosis and upper gastrointestinal bleeding are at high risk for developing severe bacterial infections which can be associated with early rebleeding. A short course of prophylactic antibiotics can decrease infection and recurrence of bleeding.
Drugs for Control of Bleeding
Somatostatin is a hormone that decreases portal blood flow by splanchnic vasoconstriction, without causing significant systemic adverse effects.
Octreotide is a synthetic analogue of somatostatin and is the drug of choice in acute variceal bleeding and is used in conjunction with endoscopic therapy.
Vasopressin is the most potent splanchnic vasoconstrictor; it reduces blood flow to all splanchnic organs, decreasing portal venous inflow and portal pressure. But due to its potent nature, it can cause bowel ischemia and systemic vasoconstriction leading to causing a risk of hypertension, myocardial ischemia
Terlipressin is a synthetic analogue of vasopressin that has longer biologic activity and significantly fewer adverse effects than vasopressin.
Endoscopic Control of Bleeding
Endoscopy should be performed as soon as the patient is stabilized.
The aim is to establish the cause of and to control the bleeding.
Failures in endoscopic treatment may be managed with a second session of such therapy, but if bleeding occurs the third time, need for TIPS should be considered
Endoscopic variceal ligation
Endoscopic variceal ligation is the preferred endoscopic therapy in acute esophageal variceal bleeding. It is superior to sclerotherapy. The procedure is similar to rubber-band ligation of hemorrhoids.
Endoscopic injection sclerotherapy
Endoscopic injection sclerotherapy is an alternative procedure when endoscopic variceal is not technically feasible. This procedure has higher complication rates.
Sclerotherapy involves injecting a sclerosant solution like including 5% sodium morrhuate, 1-3% sodium tetradecyl sulfate, and 5% ethanolamine oleate into bleeding varix which causes thrombosis and obliteration of lumen.
This is used in 5-10% of patients in whom bleeding cannot be controlled by endoscopic and/or drug treatment.
This technique should be employed only in patients with massive bleeding and should be a temporary measure until definitive treatment like Transjugular intrahepatic portosystemic shunt [TIPS] or some other surgery can be done.
Percutaneous transhepatic embolization
Percutaneous transhepatic embolization involves catheterization of the gastric collaterals that supply blood to varices via the transhepatic route. It is less effective than endoscopic sclerotherapy.
Endoscopic Administration of Cyanoacrylate monomer
Endoscopic administration of cyanoacrylate monomer also called superglue in gastric varices is another intervention.
Transjugular intrahepatic portosystemic shunt
Transjugular intrahepatic portosystemic shunt is a useful procedure in patients in whom bleeding persists in spite of drugs and endoscopic treatment. This procedure is effective only in portal hypertension of hepatic cause.
This procedure is not a surgical procedure, rather it is a procedure done by an interventional radiologist.
The procedure is done under local anesthesia and sedation
Access is made through the internal jugular vein and the hepatic vein is cannulated. A tract is created through the liver parenchyma, from the hepatic to the portal vein under ultrasonographic and fluoroscopic guidance. The tract is dilated, and an expandable metal stent is introduced, connecting the hepatic and portal systems. This leads to the shunting of blood from the hypertensive portal vein and sinusoidal bed the hepatic vein.
Apart from acuter variceal bleed, recurrent variceal bleeding is another indication for TIPS
Complications of TIPS
- Neck hematoma, perihepatic hematoma, liver capsule rupture and extrahepatic puncture of portal vein can occur during the procedure
- Arterioportal fistula
- Portobiliary fistula
- Shunt narrowing or blockage can occur within the first year after the TIPS procedure.
- Worsening of encephalopathy due to reduction of hepatic blood flow
- Increased susceptibility to bacteremia
- Liver failure.
- Stent infection
Long Term Treatment
Long term treatment includes dietary restriction and primary prophylaxis to prevent further bleeding and complications
Alcohol intake is strongly discouraged and rehabilitation should be undertaken when required. Salt restriction is also advocated to reduce the volume of circulating fluid and as part of treatment for ascites, if present.
Following approach is used
- Patients with small varices – Only surveillance
- Medium to large varices
- Nonselective beta-blocker [preferred]
- Esophageal varices ligation may be considered if beta-blockers are contraindicated or are not tolerated
- Patients without varices – Endoscopy every 2 years, or sooner if they have signs of decompensation in which case nonselective beta-blockers.
- Patients with small varices – Annual endoscopy annually
Endoscopy is not mandatory in patients who are already on nonselective beta-blockers
The most common drug used for prophylaxis of variceal bleeding.
Propranolol and nadolol are the most commonly used drugs
These nonselective beta-blockers reduce portal and collateral blood flow and decrease portal pressure.
These also cause a reduction in cardiac output.
Nonselective beta-blockers have been shown to prevent or decrease the risk of bleeding by 50%. The risk of bleeding returns on withdrawl of drugs. So the drug needs to be given lifetime
The vasodilator isosorbide mononitrate may be considered as a second-line agent for secondary prophylaxis for variceal bleeding.
It is not effective alone and should be considered when a single drug fails.
Endoscopic Procedures for Prophylaxis
Sclerotherapy has no role in primary prophylaxis
Endoscopic variceal ligation procedure may be an option in secondary prophylaxis for patients with large varices who cannot tolerate beta-blockers.
Treatment of Hepatic encephalopathy
If encephalopathy occurs, the standard treatment includes lactulose, bowel enemas, and oral antibiotics along with maintenance of adequate nutrition.
These include shunts, with the distal splenorenal shunt being most common.
This procedure connects the vein from the spleen to the vein from the left kidney in order to reduce pressure in the varices and control bleeding.
This is done in cases of end-stage liver disease.
Patients with severe and persistent upper gastrointestinal hemorrhage have higher morbidity and mortality rate.
Almost 90% of patients with cirrhosis develop varices.
The first episode of variceal hemorrhage carries a mortality of 30-50%.
Patients with a known diagnosis of esophageal varices have a 30% chance of variceal bleeding within the first year after the diagnosis.
Patients who bleed once carry a 60-80% chance of rebleeding within 1 year of the first episode.
The risk of dying is maximal during the first few days after the bleeding episode and decreases slowly over the first 6 weeks.