Definition: It is increased accumulation of blood in tissues. Hyperemia may be: a) Active (arterial) Or b) Passive (Venous)
– Active or arterial hyperemia: In which the arterioles and capillaries are dilated and filled with blood, it may be physiological e.g. in muscular exercise or pathological e.g. in acute inflammation (the vascular response).
– Passive hyperemia or venous congestion:
It is increased accumulation of blood in the venous side of the circulation.
It is of two types local or general (systemic)
I- Generalized venous congestion or chronic venous
congestion (C.V.C): In which blood accumulates in the venous side of the circulation all over the body.
A- Causes in the heart: leading to congestive heart failure such as martial incompetence and aortic valvular disease.
B- Causes in lungs: leading to pulmonary hypertension such as:
– Increased fibrosis in the lungs as in pulmonary TB, chronic lung abscess, bronchiectasis and silicosis.
Effect of Generalized venous congestion:
1- The lungs:
Congestion of the lungs occurs only in cases of mitral stenosis and left sided heart failure.
1 – Both lungs are enlarged and heavy.
2- They are firm in consistency and brown (brown
induration) due to:
a- Hemosiderin pigmentation.
b- Fibrosis in alveolar septa induced by hemosiderin.
3- On cut section a big amount of frothy blood comes
out if the lungs are squeezed.
1- Alveolar capillaries are dilated, tortuous and packed with red blood cells. Upon rupture, the extravasated red cells haemolyse and hemoglobin breaks into hematoidin (absorbed) and hemosiderin. Macrophages move into alveolar spaces and engulf red cells and yellowish granules of hemosiderin and are called cardiac or heart failure cells.
2- Alveoli are distended and filled with red blood cells and heart failure cells (which are diagnostic).
3- The interstitial tissues show increased fibrosis.
1 – The liver is enlarged and firm in consistency.
2- Both outer and cut surfaces show a nut-meg appearance; mottled red due to congested centers of lobules and yellow streaks due to fatty change of the periphery of lobules.
1- The central vein and sinusoids in the central zone of each hepatic lobule are distended with blood.
2- Liver cells in the center of lobules show at first fatty change and in long standing cases show atrophy of the central zonal cells. With advance of the case, fatty change appears in the mid-zonal area this is due to stagnation of blood in the sinusoids giving rise to tissue anoxia. In old cases, there is increased fibrosis around the central veins in the lobules, a condition known as "cardiac cirrhosis". Hemosiderin granules arc seen in kupffer cells.
1- Dark red and enlarged up to 250 gm.
2- Red pulp is congested and appears almost black.
1- The spleen shows congestion of the venous sinuses in the red pulp.
2- Thickening of reticulin framework.
3- Atrophy of medullary cords. 4- Kidney
1 – Kidney is enlarged and dark red.
2- Cut surface shows small dark red dots (congested
glomeruli) and dark red streaks (congested vessels) in
a rather pale cortex.
3- Medulla is dark red.
1- Glomerular capillaries are distended with red cells.
2- Convoluted tubules show cloudy swelling or fatty change.
C.V.C. is also apparent in other organs as brain, stomach, intestine, adrenals.
II- Localized venous congestion: Occurs when the main vein of a tissue or an organ is obstructed. It may be acute or chronic.
a- Acute local venous congestion as occurs in strangulated hernia and thrombosis in a vein. The venules and capillaries in this local area are markedly engorged with venous blood.
b- Chronic local venous congestion for example.
1- In portal hypertension due to liver cirrhosis, leading to the following manifestations:
Venous blood accumulates in the radicals of the portal vein.
The spleen is enlarged in size and red in colour.
The anastomotic veins between the portal and systemic circulations become dilated, tortuous and engorged with blood i.e. varicosities at the lower end of oesphagus (oesophageal varices) and at the lower end of the rectum (piles).
In chronic cases, fluid may pass to the peritoneal cavity leading to ascites.
2- Gradual pressure on a vein from outside e.g by a tumor.