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HYPERAEMIA AND CONGESTION
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Definition
- Hyperaemia is increased volume of blood in affected tissue or part.
Hyperaemia (Active hyperaemia)
- Occurs in arterioles or arteries
- Increased blood flow in capillaries
Congestion (Passive hyperaemia)
- Occurs due to impaired venous drainage
- Stasis of blood in veins
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ACUTE GENERAL ACTIVE HYPERAEMIA
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Increased blood throughout the body
Causes
- Various systemic diseases. E.g. Pasteurellosis, erysipelas
- Rapidly beating heart → increased blood supply
- Renal diseases - due to retention of fluids
Macroscopically
- Bright red color or organs
Microscopically
- Arteries and capillaries dilated with blood
Result
- Disappears if cause is removed
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ACUTE LOCAL ACTIVE HYPERAEMIA
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- Increased amount of blood in arterial system within a local area (leg, Stomach, lung)
- Most common type of hyperaemia
Causes
- Physiological
- Occurs in stomach and intestine following a meal
- Lactating mammary gland
- Muscles during exercise
- Genital tract during oestrus
Blushing
Macroscopically
- Enlarged, swollen, heary
- ↑ warmth in Skin
Microscopically
- In live animals, arteries, arterioles and capillaries are distended with blood
- Difficult to detect in dead animals
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PASSIVE HYPERAEMIA OR CONGESTION
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- Increased blood in the venous end due to improper drainage.
- GRNERAL - if interference is central (i.e.) lungs, heart
- LOCAL - if vein of an organ or body
- It can be acute or chronic
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Brain congestion
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ACUTE GENERAL PASSIVE HYPERAEMIA
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- Increase in the amount of blood on the venous side of circulatory system
- Due to sudden obstruction to the flow of blood in heart and lungs.
Causes
- Heart failure
- Pneumonia
- Pulmonary thrombosis or embolism
- Hydropericardium, Haemopericadium, etc.
- Hydrothorax, Haemothorax, etc.
Macroscopically
- Organs are blue in color (Unoxygenated blood)
- Veins distended with blood
- Organs enlarged, heavy
- Upon incision, blood oozes out
Result
- Causes are mild → Recovery
- Causes are severe → Death
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CHRONIC GENERAL PASSIVE HYPERAEMIA
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Increased blood on venous end persisting for long period of time causes Permanent changes (fibrosis, atrophy).
Causes due to central lesions in heart and lungs
- Heart lesions
- Stenosis of valvular openings
- Valvular insufficiency
- Failure of cusps of valves to close property
- Inflammatory tissue
- Thrombus
- Myocardial failure
Contraction of muscles
↓
Blood pushed in arteries
↓
But accumulates in venous side
- Anomalies of heart
- Persistent foramen orale
- Interventricular septal defects
Blood moves from one chamber to another
↓
Arterial blood pressure maintained
↓
Blood accumulates in venous end.
- Constrictive lesons in pericardium
- Traumatic pericarditis in cattle
- Lesions of lungs
- Obliteration of capillary bed in lungs
- Prevents free flow of blood through the lungs
- Retards flow through right side of heart
- Blood back flows into Liver
- Causes
- Chronic alveolar pulmonary emphysema in horses (BROKEN WIND)
- Pneumonia
- Hydrothorax, haemothorax
- Compression of major pulmonary vessels
Lesions in CVC
Liver
- Lesions in Rt A-V valve or lungs
- Increase in size and weight on section,
- “Nutmeg pattern”
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Liver - CVC
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- Central veins are prominent
- Area surrounding central vein is congested
- Congested area is surrounded by hypoxic areas
Morphologic features of CVC
- Veins all over the body engorged with blood
- Blood is bluish red in color
- Oedema of tissues
- Atrophy of organs
- Degeneration and Necrosis or organs
Microscopically
Mitral valve diseases
↓
Affected in Left – sided heart failure
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Alveolar capillaries distended with blood
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Rupture of capillaries
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Minute intra – alveolar haemorrhages
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Haemosiderin release from RBCs
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Phagocytosed by macrophages
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Heart failure cells (Macrophages)
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Fibrosis (induration) of alveolar septa
↓
Brown induration of lungs
↓
(due to haemosiderin)
Spleen
- Enlarged and cyanotic
- Due to congestion of Liver
- Occurs in vegetative endocarditis (swine) and
- Traumatic pericarditis (cattle)
- Hard and indurated - Cyanotic induration
Kidneys
- Pressure on renal veins by
- Tumours of adrenals
- Abscesses
- Grossly, enlarged and dark purple
- Cortico-medullary junction – dark red in color
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ACUTE LOCAL PASSIVE HYPERAEMIA
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Increase in blood in the veins of a portion (foot, tail, kidney etc) Due to sudden obstruction to blood flow
Causes
- Malposition of viscera
- Volvulus, intussusception, torsion
- External pressure
- Ligatures, tourniquets, bandages
Pathogenesis
Accumulation of blood in ventral portions of the body due to gravity.
Causes
- Occurs in heart diseases
- Recumbency
- Inactive animals
- Large animals
- Heart failure - Agonal congestion
Appearances
- Veins in ventral portion or organs distended with blood
- Lungs - increase capillary bed
- Intestine & kidneys – necrosis and gangrene
- Causes pneumonia and gangrene of intestine
Significance
- Indicates
- the side of animals which was ventral at the time of death
- Heart was not able to pump properly
- Location of body in medico–legal cases
Grossly and microscopically
Veins are engorged with blood
↓
Necrosis of endothelial cells
↓
Haemorrhage
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CHRONIC LOCAL PASSIVE HYPERAEMIA
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- Increase in amount of blood for a long time in veins
- Permanent tissue changes (atrophy, fibrosis)
Causes
- External pressure
- Obstruction from within
Gross and microscopic appearance
- Enlarged initially later undergoes atrophy
- Veins - bluish blood
- Oedema due to increase permeability of capillaries
- Fibrosis
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Participants