Learning Objectives
• Define congestion and hyperemia
• Differentiate between the two with regard to:
• Mechanisms / underlying causes
• Appearance (gross and histologic)
• Effects
• Differentiate between the 2 types of hyperemia
• Know where congestion occurs with right and left heart failure
• Be able to differentiate acute and chronic pulmonary congestion (gross and histology)
• Know the consequences of chronic pulmonary congestion
• Be able to recognize and describe hepatic congestion (acute vs chronic) and know under what condition it occurs
• What does the term shock mean and what are the 3 main categories?
HYPEREMIA AND CONGESTION
Circulatory Disturbances 2: Hyperemia and Congestion
Shannon Martinson, January 2017
http://people.upei.ca/smartinson/ VPM 152 General Pathology
Edema
Hyperemia and congestion
Shock
Hemorrhage
Thrombosis and embolism
Infarction
CIRCULATORY DISTURBANCES
Altered Blood flow
Hyperemia and congestion indicate a local increase in blood within a tissue
• Active engorgement of vascular beds due to increased arteriolar flow Hyperemia
• Passive engorgement of vascular beds due to decreased outflow of blood Congestion
ALTERATIONS IN BLOOD FLOW & PERFUSION
Image - Robbins and Cotran PBD 8th Ed, 2010
• Active process
• Increased blood entering tissue via arterial flow
• Oxygenated (red) Hyperemia
ALTERATIONS IN BLOOD FLOW & PERFUSION - HYPEREMIA
• Response to stimulus → Can be physiologic or pathologic Image - Robbins and Cotran PBD 8th Ed, 2010
Physiologic Hyperemia
Digestion
Exercise
Dissipate heat
Neurovascular (blushing)
ALTERATIONS IN BLOOD FLOW & PERFUSION - HYPEREMIA
• Due to an underlying pathologic process → INFLAMMATION
• Arteriolar dilation in response to inflammatory stimuli / mediators
• Often accompanied by edema!
ALTERATIONS IN BLOOD FLOW & PERFUSION - HYPEREMIA
Pathologic Hyperemia Chantal Albert AVC ‘2007
Gross Findings • Red colouration of the tissue • Swelling, warmth (in the living…)
ALTERATIONS IN BLOOD FLOW & PERFUSION - HYPEREMIA
One of the cardinal signs of inflammation is reddening = “rubor”
Histology Findings • Capillaries +/-
arterioles are dilated and filled with blood
• Often accompanied by edema
• May see inflammation!
ALTERATIONS IN BLOOD FLOW & PERFUSION - HYPEREMIA
Effect of hyperemia – hastens movement of metabolites into an area and flushes catabolites from the area
• Passive process
• Decreased outflow of blood
• Deoxygenated blue (dark red - blue) Congestion
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
• Passive engorgement of vascular beds due to decreased/
obstructed venous return Image - Robbins and Cotran PBD 8th Ed, 2010
Gross Appearance
• Dark red to blue / black depending on degree of stagnation of blood
• Tissues might be cooler than normal (living animal)
• Cut surfaces ooze blood and are often wet due to accompanying edema
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Chronic Congestion • Hypoxia (O2)
• Cellular atrophy
• Cellular degeneration / necrosis
Histopathology
Acute Congestion • Engorged capillaries
• +/- Edema
Effect of congestion • Leads to hypoxia and accumulation of catabolites
• Cellular degeneration / necrosis • Interference with normal tissue function • May get thrombosis of congested veins • +/- proliferation of connective tissue if chronic
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Two factors used to define types of congestion
1. Duration
• Acute (sudden)
• Chronic (longer-term)
2. Extent
• Localized – Change is confined to a discrete area
• Generalized – Indicates systemic change (eg heart failure)
Acute localized
congestion
Acute generalized congestion
Chronic generalized congestion
Chronic localized
congestion
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Intestinal torsion
Localized congestion
• Local obstruction to venous drainage
• Such as when and organ twists
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Splenic torsion (with GDV)
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Generalized congestion
• Can be acute:
• Sudden death due to heart
failure or euthanasia with
barbiturates
• Blood accumulates in lung,
spleen and liver
• More often chronic!
Generalized congestion occurs with pathology of the heart or lung • Left heart failure → pulmonary congestion • Right heart failure → systemic congestion • 1◦ Pulmonary disease → can cause RHF → systemic congestion
• LEFT sided heart failure
• Congestion and edema of the lungs
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
RIGHT sided heart failure
•Systemic congestion – Liver especially
•Generalized edema (dependent SQ edema, ascites)
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Primary pulmonary disease • Lung disease → damage of pulmonary vascular bed → increased resistance /pulmonary hypertension →
RIGHT heart failure
• Generalized edema (SQ, ascites) and hepatic congestion; +/- pleural effusion
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
• Right heart failure resulting from pulmonary disease Cor pulmonale
Histology
•Pulmonary congestion
•Usually due to LEFT heart failure
•Lungs are red (congestion), wet (edema) and heavy
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Gross
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
•Chronic pulmonary congestion
•When chronic →lungs may have brown – tan areas reflecting hemosiderin accumulation
PBVD, Zachary, 2017
Gross
Histology
Consequences of Chronic Pulmonary Congestion
1. Intra-alveolar hemorrhages • “Heart failure cells”
2. Pulmonary Edema • Interferes with gas exchange
3. Interstitial Fibrosis
4. Pulmonary Hypertension • ↑ Pressure in pulmonary artery • +/- Cor pulmonale
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Histology
• Hepatic Congestion • Most often due to right heart failure • Less often secondary to pulmonary hypertension and cor pulmonale
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
• Hepatic Congestion • Gross appearance:
• Liver is enlarged and dark brown with rounded edges
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
• Hepatic Congestion • Gross appearance:
• Cut surface may have a reticular / zonal pattern (= nutmeg liver)
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Hepatic Congestion
Zone 1 - relatively normal Zone 2 - fatty change
(partial hypoxia)
Zone 3 - congested sinusoids, hepatocyte degeneration/necrosis
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Hepatic Congestion Histopathology: Acute hepatic congestion
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Zone 1 - relatively normal Zone 2 - fatty change
(partial hypoxia)
Zone 3 - congested sinusoids, hepatocyte degeneration/necrosis
Histopathology: Acute hepatic congestion
Hepatic Congestion
In zone 3
• Hemosiderin within macrophages (kupffer cells)
• Hepatocyte loss &/or atrophy and dilated sinusoids
• Increased connective tissue around central veins
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
Hepatic Congestion Histopathology: Chronic hepatic congestion
Congestion / Hyperemia – RBCs are within the blood vessels (*)
Hyperemia/Congestion vs Hemorrhage
*
*
Hemorrhage – RBCs are outside vessels ( )
ALTERATIONS IN BLOOD FLOW & PERFUSION - CONGESTION
• Systemic hypotension due to reduced cardiac output or reduced blood volume Shock
• Results in impaired tissue perfusion • Brain and heart especially • Tissue hypoxia
• Final common pathway for: • Microbial sepsis • Severe hemorrhage • Trauma or burns • Myocardial damage • Severe pulmonary embolism
ALTERATIONS IN BLOOD FLOW & PERFUSION - SHOCK
Cardiovascular collapse
3 Categories of Shock
1. Cardiogenic Shock
2. Hypovolemic Shock
3. Vasogenic Shock
1. Cardiogenic shock
• Failure of the heart to adequately pump the blood
• Can result from: • Myocardial infarction • Arrhythmias • Cardiomyopathy • Valvular disease • Obstruction of blood
flow from the heart
ALTERATIONS IN BLOOD FLOW & PERFUSION - SHOCK
2. Hypovolemic shock • Decreased circulating blood volume • May result from
• Blood loss from hemorrhage (internally or externally)
• Fluid loss • Vomiting • Diarrhea • Burns
ALTERATIONS IN BLOOD FLOW & PERFUSION - SHOCK
3. Vasogenic shock
• Maldistribution of blood • Due to decreased peripheral
vascular resistance → pooling of blood in peripheral tissues
• Results from vasodilation
• Release of vasoactive amines
Anaphylactic shock
• Occurs with severe CNS damage
• Loss of ANS signals to arteriolar smooth muscle
Neurogenic shock
• Release of chemical mediators associated with inflammation
Septic shock*
ALTERATIONS IN BLOOD FLOW & PERFUSION - SHOCK
Microbial substances are released from bacteria (LPS)
Activation / endothelial cells and stimulation of WBCs to release cytokines
Vasodilation, coagulation activation (DIC), complement activation…
Pathogenesis
ALTERATIONS IN BLOOD FLOW & PERFUSION - SHOCK
3. Vasogenic shock
• Release of chemical mediators associated with inflammation
Septic shock*
Three stages of shock: 1 2 3
Compensated
• Reflex compensation
• ↑HR, peripheral vasoconstriction
• Perfusion of vital organs
Progressive
• Tissue hypoperfusion
• Worsening circulatory and metabolic imbalances
Irreversible
• Severe cell/tissue injury
• Survival is not possible
ALTERATIONS IN BLOOD FLOW & PERFUSION - SHOCK
LESIONS OF SHOCK
Pulmonary congestion & edema
Hepatic congestion
Heart - hemorrhage and necrosis
Brain - neuronal cell death
Kidneys - acute tubular necrosis
Blood vessels - endothelial damage (thrombosis / DIC)
Adrenal glands - hemorrhage
GI Tract – congestion and hemorrhage
Skeletal muscle - pallor
ALTERATIONS IN BLOOD FLOW & PERFUSION - SHOCK
REVIEW QUESTIONS
How would you describe this change
What’s your morphologic diagnosis?
What do these two findings tell you about the lungs?
•Possible cause?
REVIEW QUESTIONS
REVIEW QUESTIONS
What is your morphologic diagnosis?
Possible cause?
REVIEW QUESTIONS
Give 3 morphologic diagnoses
Possible cause?