Disorders of blood circulation

Arterial plethora (hyperemia)

Arterial plethora = increased blood supply to the organ, tissue due to increased arterial blood flow.

General arterial plethora. It occurs with an increase in circulating blood volume.

Local arterial plethora. Occurs when the innervation is disturbed (angioedema) due to impaired blood flow through the arterial trunk (collateral hyperemia), after elimination of the factor (tumor, ligature, fluid) that squeezes the artery (hyperemia after ischemia), due to a decrease in barometric pressure (vacant blood pressure). ), with inflammation (inflammatory hyperemia), in the presence of arteriovenous shunt.

Venous plethora

Venous plethora = increased blood supply to an organ or tissue due to a decrease (difficulty) in the outflow of blood; blood flow is not changed or reduced.

• Stagnation of venous blood leads to the expansion of veins and capillaries, slowing blood flow in them, to the development of hypoxia, which is the main pathogenetic factor determining changes in the organs in venous plethora.

• Venous plethora can be general and local, acute and chronic.

General venous plethora. It is a morphological substrate of heart failure syndrome.

a. Common acute venous plethora.

• Occurs with acute heart failure, complicating large-focal myocardial infarction, acute myocarditis, etc.

• Due to hypoxia and an increase in hydrostatic pressure, the permeability of capillaries increases dramatically, plasma saturation (plasmorrhage) and edema, stasis in capillaries and multiple diapedes hemorrhages develop in the stroma of organs; in the parenchyma - dystrophic and necrotic changes.

Morphological changes.

Edema and hemorrhages develop in the lungs; Acute pulmonary edema is one of the main causes of death in patients with acute cardiovascular insufficiency.

Kidney dystrophy and necrosis of the epithelium of the tubules occur.

In the liver, centrolobular hemorrhages and necrosis develop.

b. General chronic venous plethora.

• Occurs with chronic cardiovascular insufficiency (heart defects, coronary heart disease, chronic myocarditis, cardiomyopathy, etc.).

• Long maintaining the state of tissue hypoxia, it leads not only to plasmorrhagia, edema, stasis and hemorrhages, dystrophy and necrosis, but also to atrophy and sclerosis: a congestive seal (induration) of organs and tissues develops.

Morphological changes.

• In hypodermic cellulose at venous stagnation common edema - anasarka - develops.

• Fluid accumulates in serous cavities, hydrothorax, hydropericardium, ascites develops (fluid usually appears in the abdominal cavity in the presence of congestive nutmeg fibrosis of the liver).

• Cyanotic induration develops in the skin, kidneys, spleen; the liver becomes nutmeg; brown induration occurs in the lungs.

а. The skin (especially of the lower limbs) becomes cold and becomes bluish (cyanosis). The veins of the skin and subcutaneous tissue are dilated, filled with blood; lymphatic vessels are also enlarged and filled with lymph. Swelling of the dermis and subcutaneous tissue, proliferation of connective tissue in the skin.

b. Kidneys are enlarged, dense, bluish.

с. The spleen is enlarged, dense, on a cut of dark cherry color, no scraping of the pulp.

Liver.

Macroscopic picture: the liver is enlarged, dense, its edges are rounded, the cut surface is variegated, gray-yellow with dark red specks and resembles nutmeg.

Microscopic picture: only the central sections of the lobules are full of blood, where hemorrhages are noted, hepatic beams are complexed and hepatocytes are killed; these sections on the liver section look dark red. At the periphery of the lobules, hepatocytes are in a state of fatty degeneration, which explains the gray-yellow color of the liver tissue. The spread of venous plethora from the centers to the periphery of the lobules is prevented by high pressure in the sinusoids of the lobules' periphery - the place where the branch of the hepatic artery falls. In the outcome of chronic venous stasis, nutmeg fibrosis develops in the liver; rarely, with prolonged venous stasis, sclerosis in the liver progresses, the liver tissue undergoes restructuring and the process ends with the formation of small-node cirrhosis of the liver (nutmeg, cardiac fibrosis).

In the lungs brown induration develops: they are enlarged, brown in color, of a dense consistency.

Microscopic picture: in the lumens of the alveoli, bronchi, in the interalveolar septa and peribronchial connective tissue, there is an accumulation of cells loaded with brown pigment hemosiderin. The growth of connective tissue in the interalveolar septa and around the bronchi is also noted. During the Perls reaction, the brown pigment-hemosiderin gives a positive reaction to iron, its grains are painted in bluish-green color.

Pulmonary hemosiderosis in venous plethora is associated with an increase in vascular permeability and the development of multiple diapedesic hemorrhages (local hemosiderosis, see “Disorders of endogenous pigment metabolism” in the topic “Mixed dystrophies”).

Local venous plethora.

• Occurs when there is difficulty in venous blood outflow from a specific organ or part of the body due to the closure of the vein lumen (thrombus or embolus) or compression from the outside (tumor, growing tissue).

• In organs, the same changes occur as with general congestion.

• Muscat liver and nutmeg cirrhosis can occur with thrombophlebitis of the hepatic veins, which is characteristic of the Budd-Chiari disease (syndrome).

Anemia.

Anemia, or ischemia, is a decrease in the blood supply to a tissue, organ, or part of the body as a result of insufficient blood flow.

• Anemia may occur during arterial spasm (angiospastic anemia), closure of the artery through a thrombus or embolus (obstructive), with artery compression by a tumor, effusion, tourniquet, ligature (compression), as a result of redistribution of blood (for example, anemia of the brain during extraction of fluid from the abdominal cavity, where most of the blood rushes).

• Changes in tissue in case of anemia are associated with the duration of hypoxia resulting from this and the degree of sensitivity of the tissue to it.

• With acute anemia, dystrophic and necrotic changes occur in the organs.

• At chronic anemia, atrophy of parenchymal elements and stroma sclerosis develops.

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