The portal vein (PV, portal vein) is one of the largest vascular trunks in the human body. Without it, normal functioning is impossible digestive system and adequate blood detoxification. The pathology of this vessel does not go unnoticed, causing serious consequences.
The hepatic portal vein system collects blood coming from the abdominal organs. The vessel is formed by connecting the superior and inferior mesenteric and splenic veins. In some people, the inferior mesenteric vein drains into the splenic vein, and then the junction of the superior mesenteric and splenic veins forms the trunk of the PV.
Anatomical features of blood circulation in the portal vein system
The anatomy of the portal vein system (portal system) is complex. This is a kind of additional circle of venous circulation, necessary to cleanse the plasma of toxins and unnecessary metabolites, without which they would immediately fall into the inferior hollow, then into the heart and further into the pulmonary circle and the arterial part of the large one.
The latter phenomenon is observed when the liver parenchyma is damaged, for example, in patients with cirrhosis. It is the absence of an additional “filter” on the way of venous blood from the digestive system that creates the preconditions for severe intoxication with metabolic products.
Having studied the basics of anatomy at school, many remember that most organs of our body include an artery that carries blood rich in oxygen and nutritional components, and a vein emerges that carries “waste” blood to the right half of the heart and lungs.
The portal vein system is structured somewhat differently; its peculiarity can be considered the fact that the liver, in addition to the artery, includes venous vessel, the blood from which again enters the hepatic veins, passing through the parenchyma of the organ. It is as if additional blood flow is created, the work of which determines the condition of the entire organism.
The formation of the portal system occurs due to large venous trunks merging with each other near the liver. The mesenteric veins transport blood from the intestinal loops, the splenic vein leaves the spleen and receives blood from the veins of the stomach and pancreas. Behind the head of the pancreas, the venous “highways” connect, giving rise to the portal system.
Between the layers of the pancreaticoduodenal ligament, the gastric, periumbilical and prepyloric veins flow into the PV. In this area, the PV is located behind the hepatic artery and the common bile duct, together with which it follows to the porta hepatis.
At the gates of the liver, or not reaching them one to one and a half centimeters, division occurs into right and left branch portal vein, which enter both hepatic lobes and there break up into smaller venous vessels. Reaching the hepatic lobule, venules entwine it from the outside, enter inside, and after the blood is neutralized upon contact with hepatocytes, it enters the central veins emerging from the center of each lobule. The central veins gather into larger ones and form hepatic veins, which carry blood from the liver and flow into.
Changing the size of an explosive carries a large diagnostic value and can talk about various pathologies - cirrhosis, venous thrombosis, pathology of the spleen and pancreas, etc. The length of the portal vein of the liver is normally approximately 6-8 cm, and the diameter of the lumen is up to one and a half centimeters.
The portal vein system does not exist in isolation from other vascular systems. Nature provides the possibility of dumping “excess” blood into other veins if a hemodynamic disturbance occurs in this section. It is clear that the possibilities of such a discharge are limited and cannot last indefinitely, but they make it possible to at least partially compensate for the patient’s condition in case of severe diseases of the liver parenchyma or thrombosis of the vein itself, although sometimes they themselves become the cause of dangerous conditions (bleeding).
The connection between the portal vein and other venous collectors of the body is carried out thanks to anastomoses, the localization of which is well known to surgeons, who quite often encounter acute bleeding from anastomotic areas.
Anastomoses of the portal and vena cava in healthy body are not expressed because they do not carry any load. In pathology, when the flow of blood into the liver becomes difficult, the portal vein expands, the pressure in it increases, and the blood is forced to look for other outflow routes, which become anastomoses.
These anastomoses are called portocaval, that is, the blood that should have gone to the IV goes into the vena cava through other vessels that unite both blood flow basins.
The most significant anastomoses of the portal vein include:
- Connection of gastric and esophageal veins;
- Anastomoses between the veins of the rectum;
- The junction of the veins of the anterior wall of the abdomen;
- Anastomoses between the veins of the digestive organs with the veins of the retroperitoneal space.
In the clinic highest value has an anastomosis between the gastric and esophageal vessels. If the movement of blood through the veins is disrupted, it is dilated, portal hypertension increases, then the blood rushes into the flowing vessels - the gastric veins. The latter have a system of collaterals with the esophageal, where venous blood that does not go to the liver is redirected.
Since the ability to discharge blood into the vena cava through the esophageal veins is limited, overloading them with excess volume leads to varicose veins with the likelihood of bleeding, often fatal. The longitudinally located veins of the lower and middle thirds of the esophagus do not have the ability to collapse, but are at risk of injury when eating, gag reflex, and reflux from the stomach. Bleeding from varicose veins of the esophagus and the initial part of the stomach is not uncommon in liver cirrhosis.
From the rectum, venous outflow occurs both into the venous system (upper third) and directly into the lower cavity, bypassing the liver. With an increase in pressure in the portal system, stagnation inevitably develops in the veins of the upper part of the organ, from where it is discharged through collaterals into the middle vein of the rectum. Clinically this is expressed as varicose veins hemorrhoids– hemorrhoids develop.
The third junction of the two venous pools is the abdominal wall, where the veins of the peri-umbilical region take on “excess” blood and expand towards the periphery. Figuratively, this phenomenon is called the “head of Medusa” because of some external resemblance to the head of the mythical Gorgon Medusa, who had writhing snakes on her head instead of hair.
The anastomoses between the veins of the retroperitoneal space and the PV are not as pronounced as those described above, it is impossible to trace them by external signs, and they are not prone to bleeding.
Video: lecture on veins of the systemic circulation
Pathology of the portal system
Among pathological conditions, in which the explosive system is involved, there are:
- Thrombosis (extra- and intrahepatic);
- Portal hypertension syndrome (PHS) associated with liver pathology;
- Cavernous transformation;
- Purulent inflammatory process.
Portal vein thrombosis
Portal vein thrombosis (PVT) is dangerous condition, in which blood clots appear in the EV, preventing its movement towards the liver. This pathology is accompanied by an increase in pressure in the vessels - portal hypertension.
4 stages of portal vein thrombosis
According to statistics, among residents of developing regions, LPG is accompanied by thrombus formation in the veins in a third of cases. In more than half of patients who die from cirrhosis, thrombotic clots can be detected postmortem.
The causes of thrombosis are considered:
- Cirrhosis of the liver;
- Malignant intestinal tumors;
- Inflammation of the umbilical vein during catheterization in infants;
- Inflammatory processes in the digestive organs - cholecystitis, pancreatitis, intestinal ulcers, colitis, etc.;
- Injuries; surgical interventions (bypass surgery, removal of the spleen, gallbladder, liver transplant);
- Blood clotting disorders, including certain neoplasias (polycythemia, pancreatic cancer);
- Some infections (tuberculosis of portal lymph nodes, cytomegalovirus inflammation).
Very rare causes of PVT include pregnancy and long-term use of oral contraceptives. contraceptives, especially if the woman has crossed the 35-40 year mark.
Symptoms of PVT consists of severe pain in the abdomen, nausea, dyspeptic disorders, vomiting. Possible increase in body temperature, bleeding from hemorrhoids.
Chronic progressive thrombosis, when blood circulation through the vessel is partially preserved, will be accompanied by an increase in the typical picture of LPG - fluid will accumulate in the abdomen, the spleen will enlarge, giving characteristic heaviness or pain in the left hypochondrium, and the veins of the esophagus will dilate with a high risk of dangerous bleeding.
The main way to diagnose PVT is ultrasound, and a thrombus in the portal vein looks like a dense (hyperechoic) formation that fills both the lumen of the vein itself and its branches. If ultrasound is supplemented with Doppler ultrasound, then there will be no blood flow in the affected area. Cavernous degeneration of blood vessels due to dilation of small-caliber veins is also considered characteristic.
Small portal thrombi can be detected by endoscopic ultrasound examination, and CT and MRI make it possible to determine the exact causes and find probable complications thrombosis.
Video: incomplete portal vein thrombosis on ultrasound
Portal hypertension syndrome
Currently answering questions: A. Olesya Valerievna, candidate of medical sciences, teacher at a medical university
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The portal vein (portal vein or PV) is a large vascular trunk that collects blood from the stomach, spleen, and intestines, and then transports it to the liver. There the blood is cleansed and again returns to the hematocirculatory channel.
The anatomy of the vessel is quite complex: the main trunk branches into venules and other blood vessels with different diameters. Thanks to the portal vein (PV), the liver is saturated with oxygen, vitamins, and minerals. This vessel is very important for normal digestion and blood detoxification. When explosives malfunction, severe pathologies appear.
As mentioned earlier, the hepatic portal vein has a complex structure. The portal system is a kind of additional circle of blood flow, the main task of which is to cleanse the plasma of toxins and decay products.
The portal system has a complex structure
In the absence of the portal vein system (PVS) harmful substances would immediately enter the inferior vena cava (IVC), the heart, the pulmonary circulation and the arterial part of the large circulation. A similar disorder occurs with diffuse changes and compaction of the liver parenchyma, which manifests itself, for example, in cirrhosis. Due to the fact that there is no “filter” on the path of venous blood, the likelihood of severe poisoning of the body with metabolites increases.
From the anatomy course we know that many organs contain arteries that saturate them useful substances. And veins come out of them, which transport blood after processing to the right side of the heart, the lungs.
The PS is structured a little differently - the so-called gates of the liver include an artery and a vein, the blood from which passes through the parenchyma and again enters the veins of the organ. That is, an auxiliary blood circulation is formed, which affects the functionality of the body.
The formation of SVV occurs due to large vein trunks that unite next to the liver. The mesenteric veins carry blood from the intestines, the splenic vessel leaves the organ of the same name and receives nutrient fluid (blood) from the stomach and pancreas. Behind the last organ they merge large veins, which give rise to SVV.
Gastric, periumbilical, and prepyloric veins pass between the panecretoduodenal ligament and the PV. In this area, the PV is located behind the hepatic artery and the common bile duct, with which it follows to the porta hepatis.
Near the portal of the organ, the venous trunk is divided into the right and left branches of the venous veins, which pass between the hepatic lobes and branch into venules. Small veins cover the hepatic lobule externally and internally, and after blood contacts the liver cells (hepatocytes), they move to the central veins emerging from the middle of each lobule. The central venous vessels unite into larger ones, after which they form the hepatic veins, which drain into the IVC.
If the size of the PV changes, this may indicate cirrhosis, PV thrombosis, spleen diseases, and other pathologies. Normally, the length of the PV is from 6 to 8 cm, and the diameter is about 1.5 cm.
Portal vein basin
The portal system of the liver is not isolated from other systems. They pass side by side so that if blood circulation is impaired in this area, “excess” blood can be discharged into other venous vessels. Thus, the patient’s condition in case of severe pathologies of the liver parenchyma or venous thrombosis is temporarily compensated, but at the same time the likelihood of hemorrhages increases.
The PV is connected to the veins of the stomach, esophagus, intestines, etc.
The PV and other venous collectors are connected through anastomoses (connections). Their placement is well known to surgeons who often stop bleeding from anastomosing sites.
The connections of the portal and hollow venous vessels are not pronounced, since they do not bear any special load. When the functionality of the IV is disrupted, when the flow of blood to the liver is hampered, the portal vessel expands, the pressure in it increases, and as a result, blood is discharged into the anastomoses. That is, the blood that should have entered the PV fills the vena cava through the portacaval anastomoses (system of anastomoses).
The most significant PV anastomoses:
- Connections between the veins of the stomach and esophagus.
- Anastomosis between venous vessels rectum.
- Anastomoses of the veins of the anterior abdominal wall.
- Vein connections digestive organs with vessels of the retroperitoneal space.
The most important is the venous junction between the stomach and esophagus. When blood flow in the PV is disrupted, it expands, pressure increases, and blood fills the veins of the stomach. The gastric veins have collaterals (bypass paths of blood flow) with the esophageal veins, where blood that does not reach the liver rushes.
As mentioned earlier, the ability to release blood into a hollow vessel through the esophageal vessels is limited, so they expand due to overload, increasing the likelihood of dangerous hemorrhage. The vessels of the lower and middle third of the esophagus do not collapse, as they are located longitudinally, but there is a risk of their damage during eating, vomiting, and reflux. Often, hemorrhage from the veins of the esophagus and stomach affected by varicose veins is observed in cirrhosis.
From the veins of the rectum, blood rushes into the PS and IVC. When the pressure in the IV pool increases, a stagnation process occurs in the vessels of the upper part of the liver, from where the fluid enters the middle vein of the lower part of the colon through collaterals. As a result, hemorrhoids appear.
The third place where the 2 venous pools merge is the anterior wall of the abdomen, where the vessels of the peri-umbilical zone receive “excess” blood, expanding closer to the periphery. This phenomenon is called "jellyfish head".
The connections between the veins of the retroperitoneum and the PV are not as pronounced as those described above. Identify them by external symptoms it won’t work, and they are not predisposed to hemorrhage.
IV thrombosis
Portal vein thrombosis (PVT) is a pathology characterized by slowing or blocking of blood flow in the PV by blood clots. Clots obstruct the movement of blood to the liver, resulting in hypertension in the vessels.
PVT provokes various diseases and medical procedures
Causes of hepatic portal vein thrombosis:
- Cirrhosis.
- Bowel cancer.
- Inflammatory lesion of the umbilical vein during catheterization in an infant.
- Inflammatory diseases of the digestive tract (inflammation of the gallbladder, intestines, ulcers, etc.).
- Trauma, surgery (bypass surgery, splenectomy, cholecystectomy, liver transplantation).
- Coagulation disorders (Vaquez disease, pancreatic tumor).
- Some infectious diseases(tuberculosis of portal lymph nodes, cytomegalovirus infection).
Thrombosis is most rarely provoked by pregnancy, as well as oral contraceptives, which a woman takes for a long time. This is especially true for patients over 40 years of age.
With PVT, a person experiences discomfort, abdominal pain, nausea, vomiting, and stool disorders. In addition, there is a possibility of fever and rectal bleeding.
With progressive thrombosis (chronic), blood flow in the PV is partially preserved. Then the symptoms of portal hypertension (PH) become more pronounced:
- fluid in the abdominal cavity;
- enlarged spleen;
- feeling of heaviness and pain on the left under the ribs;
- dilatation of the veins of the esophagus, which increases the likelihood of dangerous hemorrhage.
If the patient rapidly loses weight, suffers from excessive sweating(at night), then it is necessary to conduct a high-quality diagnosis. If he has an enlarged lymph node near the gate of the liver and the organ itself, then competent therapy cannot be avoided. This results in lymphadenopathy, which is a sign of cancer.
Ultrasound will help identify vein thrombosis; in the image, a thrombus in the portal vein looks like a formation with a high density for ultrasound waves. The blood clot fills the IV, as well as its branches. A Doppler ultrasound will show that there is no blood flow in the damaged area. Small veins dilate, as a result, cavernous degeneration of blood vessels is observed.
Endo-ultrasound, computed tomography or MRI can help identify small blood clots. In addition, with the help of these studies it is possible to identify the causes of thrombosis and its complications.
Portal hypertension (PH) is a condition that is manifested by increased pressure in the PS. The pathology often accompanies IV thrombus, severe systemic diseases(most often the liver).
With portal hypertension, the pressure in the PV increases
PG is detected when the circulation is blocked, causing the pressure in the SVV to increase. Blockage can occur at the level of the IV (prehepatic PG), in front of the sinusoidal capillaries (hepatic PG), in the inferior vena cava (suprahepatic PG).
U healthy person PV pressure is about 10 mm Hg. Art., if this value increases by 2 units, then this is a clear sign of PG. In this case, the anastomosis between the tributaries of the venous veins, as well as the tributaries of the superior and inferior vena cava, gradually turns on. Then varicose veins affect collaterals (bypass paths of blood flow).
Factors for the development of PG:
- Cirrhosis.
- Hepatic vein thrombosis.
- Different types of hepatitis.
- Congenital or acquired changes in the structures of the heart.
- Metabolic disorders (for example, pigmentary cirrhosis).
- Thrombosis of the splenic vein.
- PV thrombosis.
PG is manifested by dyspepsia (flatulence, defecation disorders, nausea, etc.), heaviness on the right side under the ribs, yellow discoloration of the skin and mucous membranes, weight loss, and weakness. With increased pressure in the SVV, splenomegaly appears (enlarged spleen). This is due to the fact that the spleen suffers most from venous stagnation, since blood cannot leave the vein of the same name. In addition, ascites (fluid in the abdomen) appears, as well as varicose veins of the lower esophagus (after bypass surgery). Sometimes the patient has enlarged lymph nodes at the porta hepatis.
Using an ultrasound examination of the abdominal organs, changes in the size of the liver, spleen, and fluid in the abdomen can be detected. Doppler measurements will help assess the diameter of the vessel and the speed of blood movement. As a rule, with PG, the portal, superior mesenteric and splenic veins are enlarged.
Portal vein cavernoma
When a patient is diagnosed with “cavernous transformation of the portal vein,” not everyone understands what this means. Cavernoma may be a congenital malformation of the hepatic veins or a consequence of liver disease. With portal hypertension or thrombosis of the PV near its trunk, many small vessels are sometimes found that intertwine and compensate for blood circulation in this area. Cavernoma looks like a neoplasm in appearance, which is why it is called that. When the formations are differentiated, it is important to begin treatment (surgery).
Cavernoma is vascular formation in the liver
In younger patients, cavernous transformation indicates congenital pathologies, and in adults – about portal hypertension, cirrhosis, hepatitis.
Pylephlebitis
A purulent inflammatory lesion of the portal vein and its branches is called pylephlebitis, which often develops into PVT. Often the disease provokes acute appendicitis, which ends in purulent-necrotic inflammation of the liver tissue and death.
Pylephlebitis is a purulent lesion of the IV
Pyephlebitis does not have characteristic symptoms, so it is quite difficult to identify it. Not so long ago, this diagnosis was given to patients after their death. Now, thanks to new technologies (MRI), the disease can be detected during life.
Purulent inflammation manifests itself as fever, chills, severe poisoning, and abdominal pain. Sometimes hemorrhage occurs from the veins of the esophagus or stomach. When the liver parenchyma becomes infected, purulent processes develop, which is manifested by jaundice.
After laboratory tests, it will become known that the erythrocyte sedimentation rate has increased, the concentration of leukocytes has increased, which indicates acute purulent inflammation. But a diagnosis of “pyophlebitis” can only be made after an ultrasound, CT, or MRI.
Diagnostic measures
Ultrasound is most often used to detect changes in the portal vein. This is a cheap, accessible, safe diagnostic method. The procedure is painless and suitable for patients of all ages.
VV pathologies are detected using ultrasound and MRI
Doppler ultrasound allows you to evaluate the nature of blood movement; the portal vein is visible at the gate of the liver, where it divides into 2 branches. Blood moves towards the liver. Using 3-D/4-D ultrasound, you can obtain a three-dimensional image of the vessel. The normal width of the ventricular lumen during ultrasound examination is about 13 mm. The patency of the vessel has great value in diagnostics.
This method also allows you to detect hypoechoic (reduced acoustic density) or hyperechoic (increased density) contents in the portal vein. Such foci indicate dangerous diseases(PVT, cirrhosis, abscess, carcinoma, liver cancer).
With portal hypertension, an ultrasound will show that the diameter of the vessels is increased (this also applies to the size of the liver), and fluid has accumulated in the abdominal cavity. With the help of color Doppler, it is possible to detect that blood circulation has slowed down and cavernous changes have appeared ( indirect symptom portal hypertension).
Magnetic resonance imaging is useful in that it helps determine the causes of changes in the portal vein system. The liver parenchyma, lymph nodes and surrounding formations are examined. MRI will show that normally the maximum vertical size of the right lobe of the liver is 15 cm, the left one is 5 cm, and the bilobar size at the porta hepatis is 21 cm. With deviations, these values change.
One of the most effective methods for diagnosing PVT is angiography. In case of PG, fibrogastroduodenoscopy, esophagoscopy, and X-rays using a contrast agent are required to examine the esophagus or stomach.
Except instrumental studies, laboratory tests are also carried out. With their help, deviations from the norm are detected (excess of leukocytes, increased liver enzymes, blood serum contains a large amount of bilirubin, etc.).
Treatment and prognosis
Treatment of portal vein pathologies requires complex drug therapy and surgical intervention. The patient is usually prescribed anticoagulants (Heparin, Pelentan), thrombolytic drugs (Streptokinase, Urokinase). The first type of medication is necessary to prevent thrombosis and restore vein patency, and the second destroys the blood clot itself, which blocks the lumen of the vein. To prevent portal vein thrombosis, non-selective β-blockers (Obzidan, Timolol) are used. These are the most effective medications for the treatment and prevention of PVT.
VV pathologies are treated with medications and surgical intervention
If medications are ineffective, the doctor prescribes transhepatic angioplasty or thrombolytic therapy with portosystemic shunting in the liver. The main complication of IV thrombosis is hemorrhage from the esophageal veins, as well as intestinal ischemia. Treat these dangerous pathologies Only surgery is needed.
The prognosis for portal vein pathologies depends on the degree of damage that they provoked. If thrombolytic therapy during treatment acute thrombosis turned out to be not entirely effective, then surgery cannot be avoided. Thrombosis with chronic course threatens dangerous complications, so the patient must first be given first aid. Otherwise, the risk of death increases.
Thus, the portal vein is an important vessel that collects blood from the stomach, spleen, pancreas, and intestines and transports it to the liver. After filtration, it returns to the venous bed. VV pathologies do not go away without leaving a trace and threaten dangerous complications, even death, so it is important to identify the disease in time and carry out competent therapy.
The portal vein (liver) (v. portae hepatis) occupies a special place among the veins that collect blood from internal organs. This is not only the largest visceral vein (its length is 5-6 cm, diameter 11-18 mm), but also the afferent venous link of the so-called gate system liver. The portal vein of the liver is located in the thickness of the hepatoduodenal ligament behind the hepatic artery and the common bile duct along with the nerves, lymph nodes and vessels. It is formed from the veins of unpaired abdominal organs: stomach, small and large intestines, spleen, pancreas. From these organs, venous blood flows through the portal vein to the liver, and from it through the hepatic veins into the inferior vena cava. The main tributaries of the portal vein are the superior mesenteric and splenic veins, as well as the inferior mesenteric vein, which merge with each other behind the head of the pancreas. Having entered the portal of the liver, the portal vein divides into a larger one right branch(r. dexter) and left branch(r. sinister). Each of the branches of the portal vein, in turn, breaks up first into segmental branches, and then into branches of ever smaller diameter, which pass into the interlobular veins. Inside the lobules, these veins give off wide capillaries - the so-called sinusoidal vessels, flowing into the central vein. The sublobular veins emerging from each lobule merge to form three to four hepatic veins. Thus, the blood flowing into the inferior vena cava through the hepatic veins passes through two capillary networks on its way. One capillary network is located in the walls of the digestive tract, where the tributaries of the portal vein originate. Another capillary network is formed in the liver parenchyma from the capillaries of its lobules.
Before entering the portal of the liver (in the thickness of the hepatoduodenal ligament), the gall bladder vein (v. cystica) from the gallbladder, the right and left gastric veins (vv. gastricae dextra et sinistra) and the prepyloric vein (v. prepylorica) flow into the portal vein, delivering blood from the corresponding parts of the stomach. The left gastric vein anastomoses with the esophageal veins - tributaries of the azygos vein from the superior vena cava system. In the thickness of the round ligament of the liver, the paraumbilical veins (vv. paraumbilicales) follow to the liver. They begin in the anterior abdominal wall, in the umbilical region, where they anastomose with the superior epigastric veins - tributaries of the internal thoracic veins (from the superior vena cava system) and with the superficial and inferior epigastric veins - tributaries of the femoral and external iliac veins from the inferior vena cava system.
Portal vein tributaries
- The superior mesenteric vein (v. mesentenca superior) runs at the root of the mesentery small intestine to the right of the artery of the same name. Its tributaries are veins of the jejunum and ileum(vv. jejunales et ileales), pancreatic veins (w. pancreaticael, pancreaticoduodenal veins(vv. panсreaticoduodenales), ileocolic vein(v. ileocolica), right gastroepiploic vein(v. gastroomenialis dextra), right and middle colic veins(vv. colicae media et dextra), vein vermiform appendix (v. appendicuiaris). In the superior mesenteric vein, the listed veins bring blood from the walls of the jejunum and ileum and the appendix, ascending colon and transverse colon, from the stomach, duodenum and pancreas, greater omentum.
- The splenic vein (v. splenica) is located along top edge pancreas below the splenic artery. This vein runs from left to right, crossing the aorta in front. Posterior to the head of the pancreas, it merges with the superior mesenteric vein. The tributaries of the splenic vein are pancreatic veins(vv. pancieaticae), short gastric veins(vv. gastricae breves) and left gastroepiploic vein(v. gastroomentalis sinistra). The latter anastomoses along the greater curvature of the stomach with the right vein of the same name. The splenic vein collects blood from the spleen, part of the stomach, pancreas and greater omentum.
- The inferior mesenteric vein (v. mesenterica inferior) is formed as a result of the fusion superior rectal vein(v. rectalis superior), left colic vein(v. colica sinistra) and sigmoid veins(vv. sigmoideae). Located next to the left colic artery, the inferior mesenteric vein heads upward, passes behind the pancreas and flows into the splenic vein (sometimes into the superior mesenteric vein). The inferior mesenteric vein collects blood from the walls of the upper rectum, sigmoid colon, and descending colon.
In men blood flow through the portal vein is about 1000-1200 ml/min.
Oxygen content in portal blood
After eating, the absorption of oxygen by the intestines increases and the difference between arterial and portal blood in oxygen content increases.
Blood flow in the portal vein
The distribution of portal blood flow in the liver is not constant: blood flow to the left or to the left may predominate. right lobe liver. In humans, it is possible for blood to flow from the system of one lobar branch to the system of another. Portal blood flow appears to be laminar rather than turbulent.
Portal vein pressure in humans the normal level is about 7 mm Hg.
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Collateral circulation
When outflow through the portal vein is impaired, regardless of whether it is caused by intra- or extrahepatic obstruction, portal blood flows into the central veins through venous collaterals, which significantly expand.
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Intrahepatic obstruction (cirrhosis)
Normally, all portal blood can flow through the hepatic veins; with cirrhosis of the liver, only 13% leaks. The rest of the blood passes through collaterals, which can be combined into 4 main groups.
- Igroup: collaterals passing in the area of transition of the protective epithelium into the absorbent one
- A. In the cardiac part of the stomach there are anastomoses between the left, posterior and short veins of the stomach, which belong to the portal vein system, and the intercostal, diaphragmatic-esophageal and hemizygos veins, which belong to the inferior vena cava system. Redistribution of flowing blood into these veins leads to varicose veins of the submucosal layer of the lower esophagus and the fundus of the stomach.
- B. In the anal area, there are anastomoses between the superior hemorrhoidal vein, which belongs to the portal vein system, and the middle and inferior hemorrhoidal veins, which belong to the inferior vena cava system. Redistribution of venous blood into these veins leads to varicose veins of the rectum.
- Group II: veins running in the falciform ligament and associated with the peri-umbilical veins, which are a rudiment of the umbilical circulatory system of the fetus.
- III group: collaterals passing in the ligaments or folds of the peritoneum formed during its transition from the abdominal organs to abdominal wall or retroperitoneal tissues. These collaterals run from the liver to the diaphragm, in the splenorenal ligament and in the omentum. These also include lumbar veins, veins that developed in scars that formed after previous operations, as well as collaterals that form around entero- or colostomy.
- IV group: veins that redistribute portal venous blood to the left renal vein. Blood flow through these collaterals is carried out both directly from the splenic vein to the renal vein, and through the phrenic, pancreatic, gastric veins or the vein of the left adrenal gland.
As a result, blood from the gastroesophageal and other collaterals through the azygos or semi-gypsy vein enters the superior vena cava. A small amount of blood enters the inferior vena cava; blood may flow into it from the right lobar branch of the portal vein after the formation of an intrahepatic shunt. The development of collaterals to the pulmonary veins has been described.
Extrahepatic obstruction
With extrahepatic portal vein obstruction, additional collaterals are formed, along which blood bypasses the obstruction site in order to enter the liver. They drain into the portal vein at the porta hepatis distal to the site of obstruction. These collaterals include the portal veins of the liver; veins accompanying the portal vein and hepatic arteries; veins running in the ligaments supporting the liver; phrenic and omental veins. Collaterals associated with the lumbar veins can reach very large sizes.
The portal vein of the liver is a 1.5 cm wide vessel through which blood passes from the organs of the digestive system that do not have a pair and is sent to the liver. The vessel is located behind the hepatic artery and main bile duct, surrounded by lymph nodes, bundles of nerve fibers and small vessels.
The portal vein is formed by the confluence of three others: the superior and inferior mesenteric and splenic veins. It performs essential functions for the digestive system, and also plays a major role in blood supply to the liver and detoxification. Left unattended vascular pathologies lead to serious consequences for the body.
The portal vein system is a separate circulatory system in which toxins and harmful metabolites are removed from the plasma. That is, it is part of that very main filter in the human body. Without this system, toxic components would enter the heart through the inferior vena cava and be distributed throughout the entire circulatory system.
The portal vein is incorrectly called “collar”. The name comes from the word “gate”, not “collar”.
When the liver tissue is damaged due to disease, there is no additional filter for the blood coming from the digestive system. This creates conditions for intoxication of the body.
Most human organs are designed in such a way that arteries supplying nutritious blood approach them, and veins with waste blood come out of them. The liver is structured differently. It includes both an artery and a vein. From main vein the blood is distributed through the small hepatic vessels, thereby creating venous blood flow.
Massive venous trunks participate in the creation of the portal system. The vessels connect near the liver. Mesenteric veins carry blood from the intestines. The splenic vein arises from the spleen. It connects the veins of the stomach and pancreas. The lines connect behind the pancreas. This is the starting point of the portal circulatory system.
Not reaching 1 cm to the gate of the liver, the portal vein is divided into 2 parts: left and right branches. These branches envelop the hepatic lobes with a fine network of vessels. Inside the lobes, the blood comes into contact with hepatocytes and is cleared of toxins. The blood then flows into the central outgoing veins, and along them to the main line, the inferior vena cava.
If normal size the portal vein is changed, this gives reason to talk about the course of the pathology. It can be expanded in case of thrombosis, cirrhosis, or disturbances in the functioning of the digestive organs. The normal length is 6-8 cm, lumen diameter is 1.5 cm.
Portal vein thrombosis The portal vein system closely interacts with other vascular systems. If hemodynamic pathology occurs, human anatomy provides for the possibility of distributing “excess” blood to other veins.
The body uses this ability when serious illnesses liver, inability of the organ to fully perform its functions. However, thrombosis can cause dangerous internal bleeding.
Pathologies of the portal system
The portal vein is involved in a number of pathological conditions, including:
- Extrahepatic and intrahepatic thrombosis;
- Portal hypertension;
- Inflammation;
- Cavernous transformation.
Each of the pathologies in a certain way affects the condition of the main vessel and the functioning of the body as a whole.
Thrombosis
Thrombosis is a dangerous condition in which blood clots appear inside a vein, preventing the normal flow of blood towards the liver. Thrombosis is the cause of high pressure in blood vessels.
Portal vein thrombosis develops in the following pathologies:
Rarely, thrombosis develops after taking oral contraceptives, especially after the age of 40.
Symptoms of thrombosis include:
With chronic thrombosis, fluid accumulates in the abdomen, an increase in the size of the spleen is observed, the veins of the spleen dilate, and there is a threat of bleeding.
Diagnosis of portal vein thrombosis is carried out using ultrasound. The thrombus is visualized as a dense body closing the lumen. In this case, there is no blood flow in the affected area. Endoscopic ultrasound can detect small blood clots, and MRI can detect complications and determine the causes of blood clots.
Cavernous transformation
Pathological vascular formation of many small intertwining vessels that can minimally compensate poor circulation, is called cavernous transformation. In terms of external signs, the pathology is similar to a tumor, which is why it is called a cavernoma.
In a child, a cavernoma develops due to congenital anomalies, and in an adult, due to high pressure in the portal vessels.
Portal hypertension
Hypertension - what is it? This is a steady increase in pressure, and in the case of portal hypertension- in the portal vein. In this case, the blood flow in the portal vessels, liver, and inferior vena cava is disrupted. The condition accompanies thrombus formation and causes severe liver pathologies.
Causes of the syndrome:
- Hepatitis;
- Cirrhosis;
- Thrombosis of the portal system;
- Heart disease;
- Metabolic disorders leading to damage to liver tissue.
Symptoms include difficulty digestion, lack of appetite, weight loss, pain in the right hypochondrium, jaundice skin. Due to venous stagnation, the spleen enlarges and fluid accumulates in the abdomen. The veins of the lower part of the esophagus are characterized by the development of varicose veins.
Portal hypertension can be diagnosed using ultrasound. The study shows an increase in the size of the liver and spleen. The Doppler ultrasound method allows you to evaluate the lumen of blood vessels. An increase in the diameter of the portal vein and expansion of the lumens of the splenic and superior mesenteric veins are considered common.
Inflammation of the portal vein
In acute appendicitis, in rare cases, purulent inflammation develops - pylephlebitis.
Signs of damage:
- Chills;
- Feverish state;
- Signs of intoxication;
- Sweating;
- Pain.
With purulent inflammation, pressure in the vessels increases, and there is a risk of venous bleeding from the digestive organs. If the infection enters the liver tissue, jaundice develops.
If the portal vein is inflamed, jaundice may develop The main way to detect the inflammatory process is laboratory research . A blood test shows a significant increase in leukocytes, and the ESR increases. Ultrasound and MRI help to reliably diagnose pylephlebitis.
One of the largest and the most important vessels V human body is the portal vein of the liver.
Without it, the normal functioning of the digestive tract and the necessary purification of the blood are impossible.
The portal vein can be called a vessel that collects blood from all unpaired organs and delivers fluid to the liver for filtration.
Pathologies of the portal vein do not go unnoticed, but leave a mark on the functioning of the entire body.
The role of the portal vein in the structure of blood circulation
Certain organs of the human body are created in pairs: kidneys, lungs, eyes. But there are also single components: liver, heart, stomach.
This is the normal structure and functioning of the body. All unpaired organs of the abdominal region have ducts for connection with common system venous circulation.
The collected blood from each organ goes to the liver. There, the portal vein diverges into right and left branches, which are divided into small venous vessels.
In terms of size, this is the largest vessel great circle blood flow The length of the human visceral trunk can be more than four to six cm, and the diameter from ten to twenty mm.
The portal vein system is quite complex: it is an additional circle of blood flow created to cleanse the blood of poisons and allergens.
Pathologies in the functioning of the organ on the path of blood from the digestive organs contribute to the creation of conditions for poisoning the body with decay and metabolic products.
The main feature of the structure of the portal vein is that a venous vessel enters the liver, and blood through it exits into the hepatic veins.
Changes in the size or functioning of the portal vein can signal diseases of various kinds - thrombosis of the portal vein of the liver, diseases of the pancreas, spleen and others.
The hepatic vessel does not function separately from the others vascular systems. Nature has thought of a way to release excess blood into other vessels in the event of hemodynamic disturbances.
This helps to alleviate the patient’s condition with diseases of the liver or hepatic vessel.
The normal functioning of blood flow through the veins is based on the uninterrupted flow of blood through the vascular system.
If an obstacle appears in the path of blood, the entire blood flow system of the body is upset.
This condition can provoke portal hypertension syndrome, in which the main hepatic vessel is filled with blood, which leads to the need for blood to flow through other great vessels.
This replacement can cause internal bleeding and serious illnesses, such as varicose veins and hemorrhoids.
The portal vein has vital importance in the hemodynamic system, as well as in the process of filtering blood from toxins and poisons that enter a person.
With minor disturbances in the functioning of the vessel, damage can be caused to the body in the form of toxicity or blockage of blood vessels, as well as other problems.
Pathologies of the portal vein
The portal vein is susceptible to various diseases, such as:
- intrahepatic and extrahepatic thrombus formation;
- congenital abnormalities;
- aneurysms;
- portal hypertension syndrome;
- cavernous transformation;
- various inflammatory processes.
Portal vein thrombosis is a serious pathology, which is characterized by the appearance of blood clots in the vessels that interfere with the movement of fluid to the liver. For this reason, the pressure in the vessels increases.
Causes of thrombosis:
- cirrhosis of the liver;
- oncological diseases gastrointestinal tract;
- inflammatory diseases of internal organs;
- surgery and injuries;
- blood clotting problems;
- infectious diseases.
The disease manifests itself as sharp, persistent pain in the liver, nausea, vomiting, weakness, bleeding, and fever.
Portal hypertension is an increase blood pressure in design blood vessels, which can contribute to the formation of blood clots in the portal vein.
The causes of the disease can be cirrhosis, thrombosis, various hepatitis, diseases of the cardiovascular system.
Symptoms that manifest hypertension include a feeling of heaviness in the right side, weight loss, lack of appetite, nausea, and lethargy.
Cavernoma is a large number of small vessels that intertwine with each other and partially compensate for the lack of hemodynamics in the portal system.
This phenomenon is appearance looks like a malignant tumor process. Diagnosis of the disease in children may be a sign of inherited pathologies of the hepatic vessels.
Symptoms inflammatory diseases in the portal vein are not clearly expressed, so it is difficult to suspect a painful process.
More recently, the disease was diagnosed at autopsy, but with the advent of magnetic resonance imaging, diagnosis has moved to a new level.
Some symptoms that will help identify inflammation:
- fever;
- sharp pain in the abdominal area;
- severe toxicity.
Scientists have discovered two reasons for the development of portal vein diseases - local and systemic factors.
In addition, the normal operation of the vessel may be disrupted due to oncological diseases and unsuccessful surgery.
Diseases of the hepatic vessel can be acute and chronic.
The acute manifestation corresponds to the name, since the disease is accompanied by unexpected, sharp pain in the abdomen, fever and chills, enlarged spleen, nausea, vomiting and diarrhea.
All symptoms occur simultaneously, which significantly complicates the patient’s condition. If timely therapy is not prescribed, adverse consequences may occur.
No less dangerous chronic form diseases, in particular those that may be characterized by the absence of symptoms.
Are detected chronic diseases portal vein by chance, for example on an abdominal ultrasound or when diagnosing another disease.
The absence of symptoms is explained by the body's defense mechanisms, which include the ability of the hepatic artery to dilate and the growth of cavernoma.
However, sooner or later the defense mechanism weakens, which is why the patient feels the onset of symptoms of pathology.
Treatment and prevention of diseases
In order to most accurately expose the presence of a characteristic pathogenic process, inpatient diagnostics are needed.
To begin with, the doctor determines all the patient’s symptoms and then sends him for a thorough clinical examination.
To diagnose disease of the main hepatic vessel, modern examination methods are used:
- ultrasound examination of the abdominal organs;
- CT scan;
- Dopplerography;
- Magnetic resonance imaging;
- x-ray using contrast agents.
Laboratory tests have their own characteristics. The secondary ones are general tests urine and blood, but leading role they have no role in establishing a diagnosis.
Scintigraphy or hepatoscintigraphy can be used to make the correct diagnosis.
If the disease worsens, you need to contact a medical facility to prescribe adequate treatment.
The treatment strategy consists of combined therapy with the use of medications, surgery, and elimination of consequences and complications.
Diseases require immediate treatment, otherwise complications can be fatal.
In mild cases, attacks of the disease may go away on their own, in which case the patient is confident of a cure.
However, the results self-treatment are seen extremely rarely, so visiting medical institution Necessarily.
Classical therapy is aimed at urgently thinning the blood and preventing its excessive clotting.
To achieve a positive result, it is recommended to use anticoagulants and antiplatelet agents to suppress the attack.
If internal bleeding is present, hemostatic procedures must be performed in a hospital.
If traditional treatment turns out to be ineffective, then the doctor can perform surgical intervention to immediately restore the impaired blood flow.
For this purpose, special vascular prostheses were created. The operation is extremely complicated, and recovery period can last up to six months.
To prevent the occurrence or recurrence of hepatic vascular diseases, it is necessary to monitor liver function.
The main preventive action should be aimed at lowering blood pressure in the hepatic circulatory system.
To do this, it is necessary to ensure the normal functioning of the esophagus and gastrointestinal tract. To achieve this effect, it is recommended to monitor your lifestyle.
It is necessary to eat a balanced and rational diet, avoid bad habits and visit a medical facility regularly.
