Portal hypertension: diagnosis

Visualization of the portal vein system

Non-Invasive Methods

Non-invasive methods of investigation make it possible to determine the diameter of the portal vein, the presence and severity of collateral circulation. You should pay attention to the presence of any voluminous formations. Research begins with the most simple methods - ultrasound and / or CT. Then, if necessary, resort to more complex methods of visualization of vessels.

1. Ultrasonography

It is necessary to examine the liver in the longitudinal direction, along the course of the rib arc, and in the transverse, in the epigastric region. Normally, you can always see the portal and upper mesenteric veins. It is more difficult to see a spleen vein.

With an increase in the size of the portal vein, portal hypertension can be assumed, but this symptom is not diagnostic. Detection of collaterals confirms the diagnosis of portal hypertension. Ultrasound can reliably diagnose thrombosis of the portal vein, in its lumen it is sometimes possible to identify areas of increased echogenicity due to the presence of thrombi.

The advantage of ultrasound before CT is the ability to get any cross section of the organ.

Doppler ultrasound

Doppler ultrasound can reveal the structure of the portal vein and the hepatic artery. The results of the study depend on a thorough analysis of the details of the image, technical skills and experience. Difficulties arise in the study of cirrhotically altered liver of small size, as well as in obese persons. The quality of visualization increases with color Doppler mapping. Correctly performed Doppler ultrasound can diagnose obstruction of the portal vein as reliably as angiography.

Clinical significance of Doppler ultrasound

Portal vein

• Penetration
• Hepatofugal blood flow
• Anatomical abnormalities
• The permeability of portosystemic shunts
• Acute disorders of blood flow

Hepatic artery

• Prohodimost (after transplantation)
• Anatomical abnormalities

Hepatic Veins

• Identification of the Budda-Chiari syndrome

In 8.3% of cases of cirrhosis of the liver with Doppler ultrasound revealed hepatofugal blood flow through the portal, spleen and upper mesenteric veins. It corresponds to the severity of the course of cirrhosis of the liver and the presence of signs of encephalopathy. Bleeding from varicose veins is more common in hepatopetal blood flow.

Doppler ultrasound can detect abnormalities of the intrahepatic branches of the portal vein, which is important in planning surgical intervention.

With the help of color Doppler mapping it is convenient to detect portosystemic shunts, including after transjugular intrahepatic portosystemic shunting with the help of stents (TSSH), and the direction of blood flow along them. In addition, it is possible to identify natural intra-hepatic portosystemic shunts.

Color Doppler mapping is effective in diagnosing Buddha-Chiari syndrome.

The hepatic artery is more difficult to detect than the hepatic vein, due to its smaller diameter and length. Nevertheless, duplex ultrasound is the main method for assessing the patency of the hepatic artery after liver transplantation.

Duplex ultrasound is used to determine portal blood flow. The average linear velocity of blood flow through the portal vein is multiplied by the area of its cross section. Values of blood flow, obtained by different operators, may vary. This method is more likely to be used to detect acute, significant changes in blood flow than to monitor chronic changes in portal hemodynamics.

The velocity of blood flow through the portal vein correlates with the presence of varicose-dilated esophagus veins and their size. With cirrhosis, the rate of blood flow through the portal vein usually decreases; at a value below 16 cm / s, the likelihood of developing portal hypertension is significantly increased. The diameter of the portal vein usually increases; In this case, the stagnation index, i. The ratio of the cross-sectional area of the portal vein to the average velocity of blood flow along it. This index is increased for varicose veins and correlates with liver function.

Ultrasound signs of portal hypertension:

• an increase in the diameter of the portal, splenic veins and insufficient expansion of the portal vein during inspiration. The diameter of the portal vein on expiration is normally less than 10 mm, on inspiration - 12 mm. If the diameter of the portal vein is more than 12 mm during exhalation and almost does not react with an increase in diameter on inspiration, this is an indisputable sign of portal hypertension. The diameter of the splenic vein on exhalation is normal to 5-8 mm, on inhalation - up to 10 mm. Expansion of the diameter of the splenic vein more than 10 mm is a reliable sign of portal hypertension;
• an increase in the diameter of the superior mesenteric vein; in norm its diameter on inhalation is up to 10 mm, on exhalation - up to 2-6 mm. An increase in the diameter of the superior mesenteric vein and the absence of an increase in its diameter on inspiration are a more reliable sign of portal hypertension than an increase in the diameter of the portal and splenic veins;
• recanalization of the umbilical vein;
• port-caval, gastro-renal anastomoses are determined.

2. Splenomanometry is performed after puncture of the spleen with a needle 0.8 mm in diameter, which is then connected to a water manometer.

Normally, the pressure does not exceed 120-150 mm. Aq. Art. (8.5-10.7 mm Hg).

Pressure 200-300 mm.vod.st. Indicates moderate portal hypertension, 300-500 mm. Aq. Art. And above indicates a significant hypertension.

3. Hepatomanometry is performed after a puncture of the liver, regardless of the position of the needle in the liver, the pressure near the sinusoids reflects the pressure in the portal system. Intrahepatic pressure is normally 80-130 mm of water. In the case of CP, it increases by a factor of 3-4.
4. Portomanometry - direct measurement of pressure in the portal system (portal vein) can be performed during laparotomy, as well as during transumbilical portography. In this case, through the bougie umbilical vein, a catheter is inserted into the portal vein. Conditionally, portal hypertension is moderately expressed (portal pressure is 150-300 mm of water) and sharply expressed (portal pressure is above 300 mmHg).
5. Portomanometry ends with portogepometografiya - through the catheter in the portal vein is introduced contrast agent, while you can make a judgment about the status of the vascular bed in the liver and the presence of intrahepatic block.
6. Splenoportography is performed after splanometonomy, a contrast agent is injected through the catheter into the spleen. Splenoportografiya gives an idea of the state of the spleno-portal channel: its patency, the branching of the vessels of the portal vein and liver system, the presence of anastomoses between the veins of the spleen and diaphragm. With the intrahepatic block on the splenoportogram only the main trunks of branching of the portal vein are visible. With an extrahepatic block, splenoportography makes it possible to determine its location.
7. Hepatovenography and kavografiya are crucial in the recognition of the Badka-Chiari syndrome.
8. Esophagoscopy and gastroscopy - allow to identify varicose veins of the esophagus and stomach (in 69% of patients), which is a reliable sign of portal hypertension.
9. Esophagography - the detection of varicose veins of the esophagus with the help of fluoroscopy and radiography. In this case, the varicose-dilated esophageal veins are defined as circular enlightenments in the form of a chain or branching strips. Simultaneously, one can see the expansion of veins in the cardiac part of the stomach. The study should be carried out with a thick barium suspension in the position of the patient on the back.
10. Recto-manoscopy reveals varicose veins in the development of collaterals along the mesenteric-hemorrhoidal pathway. Under the mucosa of the rectus and sigmoid colon, varicose veins with a diameter of up to 6 mm are visible.
11. Selective arteriography (celiacography, etc.) is rarely used, usually before surgery. The method allows to draw a conclusion about the state of blood flow in the hepatic artery.
12. CT scan

After the introduction of a contrast agent, it becomes possible to determine the lumen of the portal vein and to identify varicose-dilated veins located in the retroperitoneal space, as well as perivisceral and para-esophageal veins. The varicose-dilated esophagus veins bulge into its lumen, and this swelling after the introduction of the contrast agent becomes more noticeable. You can identify the umbilical vein. Varicose-dilated veins of the stomach are visualized as annular structures that are indistinguishable from the stomach wall.

CT with arterial portography allows to identify the ways of collateral blood flow and arteriovenous shunts.

13. Magnetic resonance imaging

Magnetic resonance imaging (MRI) allows you to clearly visualize the vessels, since they are not involved in the formation of the signal, and to study them. It is used to determine the lumen of the shunts, as well as to assess portal blood flow. The data of magnetic resonance angiography are more reliable than the data of Doppler ultrasound.

14. Radiography of the abdominal cavity helps to identify ascites, hepato- and splenomegaly, calcification of the hepatic and splenic arteries, calcifications in the main trunk or branches of the portal vein.

X-ray examination allows you to determine the size of the liver and spleen. Occasionally it is possible to reveal a calcified portal vein; Computed tomography (CT) is more sensitive.

With infarctions of the intestine in adults or enterocolitis in infants, it is sometimes possible to detect linear shadows caused by gas accumulations in the portal vein branches, especially in the peripheral regions of the liver; gas is formed as a result of vital activity of pathogenic microorganisms. The appearance of gas in the portal vein can be associated with disseminated intravascular coagulation. CT and ultrasound (ultrasound) detect gas in the portal vein more often, for example, with purulent cholangitis, in which the prognosis is more favorable.

Tomography of an unpaired vein can reveal its increase, since a significant portion of collaterals enter it.

It is possible to expand the shadow of the left paravertebral region due to the lateral displacement of the enlarged semi-unpaired vein of the pleura between the aorta and the vertebral column.

With a significant expansion of the esophagus collateral veins, they are revealed on the chest X-ray as a volumetric formation in the mediastinum located behind the heart.

Study with barium

The study with barium is largely obsolete after the introduction of endoscopic methods.

To study the esophagus, a small amount of barium is needed.

Normally, the mucosa of the esophagus has the form of long, thin, evenly spaced lines. Varicose-dilated veins on the background of an even contour of the esophagus look like defects in filling. Most often they are located in the lower third, but they can spread upward and appear along the entire length of the esophagus. Their detection is facilitated by the fact that they are enlarged and as the disease progresses, this enlargement can become significant.

Varicose veins of the esophagus are almost always accompanied by an expansion of the veins of the stomach, which pass through the cardia and lining its bottom; they have a worm-like appearance, so it can be difficult to distinguish them from the folds of the mucous membrane. Sometimes varicose-dilated veins of the stomach look like a lobed formation on the bottom of the stomach, resembling a cancerous tumor. Differential diagnosis can help contrast portography.

15. Venography

If, with cirrhosis of the liver by some method, the permeability of the portal vein is established, confirmation by venography is not necessary; it is indicated in the planning of liver transplantation or surgery on the portal vein. If, according to scintigraphy, a portal vein thrombosis is assumed, then verification of the diagnosis requires venography.

The permeability of the portal vein is of great importance in the diagnosis of splenomegaly in children and for the exclusion of invasion of the portal vein of hepatocellular carcinoma, which developed against cirrhosis.

The anatomical structure of the portal vein system should be studied before such operations as portosystemic shunting, resection or liver transplantation. The use of venography may be required to confirm the patency of the superimposed portosystemic shunt.

In the diagnosis of chronic hepatic encephalopathy, the severity of collateral circulation in the portal vein system is important. The absence of collateral circulation excludes this diagnosis.

Phlebography can also detect a defect in the filling of the portal vein or its branches, indicating a compression by voluminous formation.

The portal vein on the veins

If the blood flow through the portal vein is not disturbed, then only the spleen and portal veins are contrasted. At the junction of the spleen and upper mesenteric veins, a filling defect due to the mixing of contrasted and normal blood can be detected. The size and course of the spleen and portal veins are subject to considerable fluctuations. Inside the liver, the portal vein gradually branches and the diameter of its branches decreases. After a while, the transparency of the liver tissue decreases due to the filling of sinusoids. On later radiographs, hepatic veins are usually not visible.

With cirrhosis of the liver, the venographic picture is quite variable. It can remain normal or on it can be seen numerous collateral vessels and a significant distortion of the pattern of intrahepatic vessels (the picture of "tree in winter".

With extrahepatic obstruction of the portal or obstruction of the spleen vein, the blood begins to flow through the numerous vessels connecting the spleen and the spleen vein with the diaphragm, thorax and abdominal wall.

Intrahepatic branches usually do not come to light, although with an unbroken portal portal blocking, blood can flow around the blocked area along the bypass vessels flowing into the distal sections of the portal vein; In this case, intrahepatic veins are visualized clearly, albeit with some delay.

16. Assessment of hepatic blood flow

Method of continuous dye introduction

Hepatic blood flow can be measured by injecting a constant rate of indocyanine green and installing a catheter in the hepatic vein. The blood flow is calculated by the Fick method.

To determine blood flow, a dye is required that is removed only by the liver and at a constant rate (which is evidenced by stable blood pressure) and not participating in enterohepatic circulation. With the help of this method, a decrease in hepatic blood flow was observed in the position of the examined lying, with fainting, heart failure, with cirrhosis and with physical exertion. Hepatic blood flow increases with fever, but does not change with an increase in cardiac output, observed, for example, in thyrotoxicosis and pregnancy.

A method based on the determination of extraction from plasma

Hepatic blood flow can be measured after intravenous administration of indocyanine green, analyzing the concentration curve of the dye in the peripheral artery and hepatic vein.

If the substance is extracted by the liver by almost 100%, which is observed, for example, by using a colloidal complex of heat-denatured albumin with ¹³¹ I, hepatic blood flow can be estimated from the clearance of matter from peripheral vessels; in this case there is no need to catheterize the hepatic vein.

With cirrhosis up to 20% of the blood passing through the liver can be directed to bypass the normal path of blood flow and the excretion of substances by the liver decreases. In these cases, a hepatic vein catheterization is necessary to measure hepatic extraction and thus assess hepatic blood flow.

Electromagnetic Flowmeters

Electromagnetic flowmeters with a rectangular pulse shape allow for separate measurement of blood flow through the portal vein and the hepatic artery.

Blood flow through an unpaired vein

The main part of the blood flowing through the varicose-dilated veins of the esophagus and stomach, enters the unpaired vein. Blood flow through an unpaired vein can be measured by thermodilution using a double catheter placed in an unpaired vein under fluoroscopic control. In alcoholic cirrhosis, complicated by bleeding from varicose-dilated veins, the blood flow is about 596 ml / min. Blood flow through the unpaired vein is significantly reduced after the appointment of propranolol.

[1], [2], [3], [4], [5], [6], [7], [8]