Vascular Disorders & Thrombosis 5

Question 1

Active increased blood flow into microvasculature is also called…

Answer 1

Hyperemia

Question 2

Passive accumulation of blood due to decreased outflow is also called…

Answer 2

Congestion

Question 3

Decreased tissue perfusion is also called…

Answer 3

Ischemia

(This results in coagulative necrosis/infarction!)

Question 4

What is the macroscopic appearance of hyperemia?

Answer 4

Tissue appears bright red and warm

Question 5

Acute heart failure, GDV, and euthanasia are all causes of which type of congestion?

Answer 5

Acute passive congestion

Question 6

Chronic left-sided heart failure and chronic right-sided heart failure are both causes of which type of congestion?

Answer 6

Chronic passive congestion

Question 7

What is the macroscopic appearance of congestion?

Answer 7

Tissue appears dark red and swollen

Question 8

Inadequate tissue perfusion which occurs when metabolic needs of the tissues are not met; typically caused by vascular obstruction, congestion, or decreased cardiac output

Answer 8

Ischemia

Question 9

What are three factors that determine tissue susceptibility to ischemia and infarct?

Answer 9

• Anatomy of vascular supply
• Rate of occlusion
• Tissue vulnerability to hypoxia

Question 10

Which organs are most susceptible to ischemia and infarct, due to having high metabolic needs and poor collateral circulation?

Answer 10

Brain and heart

Question 11

Which organs are only at a moderate risk for ischemia and infarct, due to generally receiving more blood than they need under normal conditions?

Answer 11

Lungs, GI tract, kidneys, skin

Question 12

Which organs are least susceptible to ischemia and infarct, due to only receiving blood based on immediate needs under normal conditions?

Answer 12

Skeletal muscle

Question 13

Rank these 3 tissues based on their susceptibility to hypoxia (from most to least susceptible):

Myocardial cells, neurons, fibroblasts

Answer 13

1. Neurons (death after 3 to 4 minutes)
2. Myocardial cells (death after 20 to 30 minutes)
3. Fibroblasts (remain viable after several hours of hypoxia)

Question 14

True or False: Reperfusion after a brief period of ischemia can result in a full recovery

Answer 14

True

Question 15

Reperfusion after a prolonged period of ischemia causes inflammation and oxidative damage, which is also called ___________ ________.

Answer 15

Reperfusion injury

Question 16

What occurs if ischemia is not corrected?

Answer 16

Tissue necrosis (infarct)

Question 17

A depressed, tan, firm, fibrotic infarct

Answer 17

Chronic pale infarct

Question 18

An angular/wedge-shaped area of infarct with an occluded vessel at the base; swollen/dark red (hemorrhagic) or tan

Answer 18

Acute hemorrhagic infarct

Question 19

Systemic hypotension due to reduced cardiac output or reduced blood volume

Answer 19

Shock (cardiovascular collapse)

Question 20

What is the pathogenesis of shock (cardiovascular collapse)?

Answer 20

• Hypotension causes impaired tissue perfusion and cellular hypoxia
• Result: anaerobic metabolism, cell injury, and cell death

Question 21

What are the three general categories of shock (cardiovascular collapse)?

Answer 21

• Cardiogenic shock (circulatory shock)
• Hypovolemic shock
• Blood maldistribution (vasogenic shock)

Question 22

Shock that occurs due to failure of the heart to adequately pump blood; causes include myocardial infarct, arrhythmia, cardiomyopathy, and obstruction of blood flow

Answer 22

Cardiogenic shock

Question 23

GDV is a catalyst for ___________ shock, because it causes obstruction of blood flow

Answer 23

Cardiogenic

Question 24

What is the pathogenesis of GDV?

Answer 24

• Gastric dilation causes gastric volvulus & splenic/esophageal displacement, leading to venous infarct in gastric mucosa
• Ischemia & necrosis set in, which decreases venous return via portal vein/caudal vena cava
• Reduced perfusion of intra-abdominal organs & reduced cardiac output causes cardiogenic shock, then death

Question 25

Shock that occurs due to blood loss from hemorrhage or fluid loss from V+, D+, and severe burns

Answer 25

Hypovolemic shock

Question 26

The most common malignant tumor of the canine spleen involving neoplasm of the endothelium; single to multiple discrete to coalescing splenic masses; can cause hemoabdomen; poor prognosis, metastasis common

Answer 26

Splenic hemangiosarcoma

Question 27

What is the pathogenesis of splenic hemangiosarcoma?

Answer 27

• Ruptured splenic hemangiosarcoma leads to hemoabdomen, resulting in severe blood loss
• Severe blood loss causes hypovolemic shock

Question 28

Shock due to decrease in peripheral vascular resistance with pooling of blood in peripheral tissues due to anaphylaxis, sepsis, etc.

Answer 28

Blood maldistribution

Question 29

What type of hypersensitivity is anaphylactic shock?

Answer 29

Generalized type I hypersensitivity

Question 30

What is the pathogenesis of anaphylactic shock?

Answer 30

• IgE binds to mast cells, causing widespread mast cell degranulation & release of vasoactive mediators
• Systemic vasodilation occurs, which increases vascular permeability
• Result: hypotension & tissue hypoperfusion

Question 31

What causes septic shock?

(Think at the microbial level)

Answer 31

Gram-positive / gram-negative bacteria, and fungi

Question 32

What is the pathogenesis of septic shock?

Answer 32

• Gram-neg bacteria release microbial substances (especially LPS), and this causes endothelial activation and injury (vascular leakage)
• Leukocytes are stimulated to release inflammatory cytokines, activate complement, and promote coagulation
• Result: vasodilation, hypotension, tissue hypoperfusion

Question 33

What are the 3 stages of shock?

Answer 33

• Non-progressive stage (compensatory) (inc cardiac output)
• Progressive stage
• Irreversible stage

Question 34

What occurs during the non-progressive stage of shock?

Answer 34

Compensatory mechanisms activate and vital organ perfusion is maintained (tachycardia, peripheral vasoconstriction, renal fluid conservation)

Question 35

What occurs during the progressive stage of shock?

Answer 35

Peripheral vasodilation and blood pooling, tissue hypoperfusion & hypoxia, metabolic derangement (like acidosis), and cell necrosis

(Compensatory mechanisms no longer adequate)

Question 36

What occurs during the irreversible stage of shock?

Answer 36

Widespread peripheral vasodilation, anaerobic metabolism, severe cellular and tissue injury leads to multiple organ dysfunction, then DIC and eventually death

(This stage is the point of no return - repair not possible)