Mechanism of development and general consequences
The pathology is based on slowed blood outflow. The venous bed becomes engorged, and vessels (veins, venules, and capillaries) dilate. The pressure within them steadily rises. If it becomes critical and exceeds arterial pressure, a pendulum-like (to-and-fro) blood flow occurs.
What systemic congestion leads to:
- Hypoxia and stasis: blood flow in the microvasculature stops, the volume of flowing blood drops, and tissues do not receive enough oxygen.
- Congestive edema: due to high hydrostatic pressure, fluid is forced out into the tissues. Meanwhile, its reabsorption and lymphatic drainage sharply decrease.
- Cyanosis and cooling: the skin turns blue due to the accumulation of reduced hemoglobin. Tissue temperature drops because the inflow of warm arterial blood is reduced, oxidative processes are inhibited, and dilated superficial veins actively radiate heat outward.
- Varicose veins: with a prolonged course, veins not only dilate but also become tortuous.
Acute course: impact on microcirculation
In acute general venous congestion, blood flow velocity drops sharply. The main problem here is rapidly escalating hypoxia and acidosis, which destroy the barrier function of the vessels.
As a result, wall permeability increases critically. Plasma impregnates the vessel walls (plasmarrhagia), red blood cells escape beyond the vascular bed, forming multiple diapedetic hemorrhages. Red blood cells clump together inside the capillaries — a sludge phenomenon occurs. Organ cells, deprived of oxygen, undergo acute dystrophy and necrosis.
Chronic course and vicious cycle
Chronic general venous congestion is characterized by the addition of profound tissue remodeling to the vascular disorders. Prolonged oxygen deprivation, hypercapnia, and acidosis trigger three parallel pathways:
- Vascular-exudative: persistent edema leads to chronic lymphatic system insufficiency (lymphedema).
- Parenchymatous: specific cells of the organ undergo dystrophy, atrophy, and necrosis.
- Stromal-sclerotic: fibroblasts are activated, and the synthesis of collagen and glycosaminoglycans increases.
The result is induration (hardening) of the organs. Proliferating connective tissue creates an insurmountable barrier between capillaries and cells. A capillary-parenchymal block is formed, which exacerbates hypoxia via a feedback loop.
To relieve pressure on the periphery, the body triggers magnalization of blood flow — blood is shunted through large stem vessels bypassing the capillaries. At early stages, this is protective, but over the long term, it leads to irreversible atrophic changes.
Morphological changes in organs
Blood-depot organs bear the brunt of the impact:
- Lungs: cardiogenic edema and punctate subpleural hemorrhages develop (in areas most remote from major vessels).
- Kidneys: due to ischemia, blood is shunted through the juxtamedullary shunt. The cortical layer pales, while the medullary layer becomes engorged with blood. Tubule epithelium dies, leading to acute renal failure (necrotizing nephrosis).
- Liver: veins in the center of hepatic lobules dilate sharply, centrilobular hepatocytes undergo necrosis and hemorrhage.
- Spleen: enlarges, its sinuses are packed with blood (abundantly flowing from the cut surface).
- Skin and subcutaneous tissue: changes are most pronounced in the legs. Edema, epidermal atrophy, and dermal sclerosis are observed. Acrocyanosis — blueness of the distal extremities and nail beds — is characteristic.
Briefly: answers to topical questions
What do the gross and microscopic appearance of the liver look like in chronic right ventricular congestion?
In chronic right ventricular congestion, a "nutmeg liver" develops. Grossly, the organ is enlarged, has a firm consistency and rounded edges. On cross-section, the tissue has a speckled appearance resembling a cross-section of a nutmeg due to the alternation of dark red and yellowish-brown areas. Microscopic changes depend on the zone of the hepatic lobule:
- Central zones — hemorrhages, atrophy, and necrosis of centrilobular hepatocytes are observed; venous blood accumulates in the central part of the sinusoids.
- Lobular periphery — fatty degeneration of liver cells develops.
The final stage of the process involves connective tissue proliferation (capillarization of sinusoids), leading to nutmeg fibrosis and micronodular cirrhosis.
How do the lungs change grossly and microscopically in chronic left ventricular congestion?
In chronic left ventricular congestion, brown induration of the lungs (induratio fusca pulmonum) develops. Grossly, the lungs acquire a dense consistency and a characteristic brownish color. The microscopic picture includes the following changes:
- Hemosiderosis — accumulations of brown hemosiderin pigment in the cytoplasm of macrophages (siderophages, or "heart failure cells").
- Sclerosis — diffuse proliferation of connective tissue around bronchi and vessels, as well as thickening of interalveolar septa due to congestion and fibrosis.
These processes are a consequence of erythrocyte diapedesis from hyperemic veins and lead to a decrease in organ function.
How does the spleen change in chronic general venous congestion?
In chronic general venous congestion, cyanotic induration and congestive splenomegaly develop in the spleen. Grossly, the organ is significantly enlarged and has a firm consistency. On cross-section, the tissue is dense, and pulp scraping is minimal/absent. Microscopic examination reveals the following structural changes:
- Follicles — undergo progressive atrophy.
- Red pulp — becomes markedly congested, with diffuse fibrosis (sclerosis) developing within it.
These changes are caused by prolonged venous stagnation, which leads to parenchymal atrophy and connective tissue proliferation (induration) of the organ.
What is brown induration of the lungs and in what condition does it develop?
Brown induration of the lungs (induratio fusca pulmonum) is a morphological manifestation of chronic venous congestion in the pulmonary circulation, in which local hemosiderosis is combined with pulmonary tissue sclerosis. The pathology characteristically develops in the following conditions:
- Rheumatic mitral valve disease — a classic cause leading to left atrial failure.
- Chronic left ventricular heart failure — of any other etiology.
- Pulmonary vasculitis and recurrent pulmonary thromboembolism — as causes of venous blood stagnation.
As a result of erythrocyte diapedesis, hemosiderin is formed, giving the lungs a brown color, while connective tissue proliferation leads to their hardening (induration) and decreased function.
To remember how congestion is distributed in isolated heart failure, use the first-letter rule: Right ventricle — Rest of the body (systemic circulation). Left ventricle — Lungs (pulmonary circulation).
Class and exam questions
Why do tissues become cold during venous congestion?
Due to oxygen deficiency, oxidative processes decrease, the inflow of warm arterial blood diminishes, and dilated superficial veins act as a radiator, increasing heat dissipation.
What is a capillary-parenchymal block?
This is a pathological barrier in chronic congestion. Proliferating connective tissue and altered vessels physically separate capillaries from organ cells, making normal metabolism impossible and increasing atrophy.
How does renal blood flow change in acute congestion?
Blood is shunted through the juxtamedullary shunt. As a result, the cortex suffers from ischemia while the medulla becomes engorged with blood, culminating in tubular necrosis.
What else to study on this topic
- Mechanisms of development of the sludge phenomenon and stasis in the microvasculature
- Pathogenesis of cardiogenic pulmonary edema
- Morphology of centrilobular hepatic necrosis
- Stages of microcirculatory blood flow magentization
- Differences between plasmarrhagia and other types of vascular permeability disorders
Master the entire topic in the "Pathological Anatomy" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on «General venous congestion» and 4,414 more pages on the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 153 video lessons on the subject
Other topics in the section "Disorders of Blood and Lymph Circulation"
Free video lessons: pathological anatomyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.