Pathology of Vessels Flashcards
what are the mechanisms of edema formation (4)
- vascular permeability increased
- intravascular hydrostatic pressure increased
- intravascular oncotic pressure decreased
- lymphatic drainage decreased
how does increased vascular permeability increased
inflammation or immunologic stimuli
mediators (histamine, bradykinin, leukotrines)
endothelial cell contraction then retraction
fluid into interstitial space
how does intravascular oncotic pressure lead to edema formation
oncotic pressure = colloid osmotic pressure (interchangable)
if protein levels low the fluid will leak out into surrounding tissues
what causes hydrostatic pressure to increase
blood pressure increase
or
decreased venous return
how does renin potentiate edema
- water and/or blood leaves blood vessels
- decreased blood volume or drop in blood pressure
- kidneys secrete renin
- stimulates production of angiotensin by the liver
- ultimately results in the constriction of blood vessels and increased blood pressure
- increased hydrostatic pressure
- potentiates edema
what other disease can cause edema
congestive heart failure
what maintains oncotic pressure
protein loss
albumin mainly
if albumin level is decreased than fluid can leak out vessels because of decreased oncotic pressure
what are the causes of protein lack/loss (leading to decrease in oncotic pressure)
- lack of albumin (hypoalbuminemia)
- failure of albumin production (liver failure –> cirrhosis)
- loss of albumin (intestinal malabsorption –> Johnes, IBD; renal failure –> nephrotic syndrome (glomeruli cannot reabsorb protein and will be lost in urine); parasitic infection –> severe abdominal blood loss)
how does lack of albumin lead to edema
- liver damage (non-functional, decreased size)
- decreased albumin production
- hypoproteinemia
- decreased oncotic pressure
- edema
how does loss of albumin cause edema
1. albumin loss
- johne’s –> thickening of lamina propria in intestine –> macrophages, not absorbing protein back into circulation
- nephrotic syndrome –> dilated tubules filled with protein –> leaking –> not grabbing protein and lots in urine
- heamonchus worm –> edema in jaw
2. hypoproteinemia
3. decreased oncotic pressure
4. edema
what are disruption of normal circulation
- torsion
- rupture
- vascular thickening
- vasculitis
- thrombosis
what 3 things need to occur in order to form a blood clot
- endothelial cells need to be healthy
- blood needs to be right consistency
- normal blood flow
what is vascular torsion and what does it cause
- low pressure vessels collapose after torsion occurs
- blood can flow in but not out
- congestion
- necrosis
what is shown here
vascular torsion
what are causes of arterial rupture
- traumatic (common)
- spontaneous (uncommon) –> racehorses may be underlying degeneration
what is shown here
aortic rupture
tear in aorta
what are causes of equine sudden death
- horse kicked
- dark red blood in thoracic cavity –> huge blood clot around heart (ruptured heart or blood vessel)
- ruptured aorta
what is petechia
pinpoint hemorrhages
what is purpura
medium sized hemorrhages
what is ecchymoses
large hemorrhages (>1cm)
what are hematomas
localized, extravascular collection of blood
what is hemothorax
free blood in the thorax
what is hemoperitoneum
free blood in abdomen
what are the types of aneurysms
- saccular: one side
- fusiform: both sides
what are false and dissecting aneurysms
- false: blood dissecting between the outer layers of the wall
- dissecting aneurysm: blood dissecting between the inner layers of wall
what is guttural pouch mycosis
fungal plaque –> erroding through normal tissues –> important vessels near (carotid) and can start erroding through these walls
what is arterioscleorsis and what are the causes
hardening of arteries
old age and high BP
how does arterioscleorsis occur
proliferation of medial smooth muscle and fibrosis of the intima (+/- mineralization)
–> narrowing of lumen with loss of elasticity
ex. aorta in cow with Johne’s multiple mineralized plaques
what is mineralized arterioscleorsis
calcification around the arties
will not be able to contract and dilate
what is atherosclerosis and what are the causes
specific form of vascular thickening
- dogs with hypothyroidism
- diabetes mellitus
how does hypothyroidism and diabetes mellitus cause atherosclerosis
depression of lipid metabolism –> accumulation of plasma lipids
deposition of fibro-fatty plaques (deposits of lipid, fibrous tissue and calcium in vessel walls)
damage to endothelium leads to thrombosis (virchow’s triad)
settles into blood vessels –> cholesterol clefts –> granulomatous inflammation
what does atherosclerotic plaques lead to
infarction in coronary arteries, basilar artery
no blood flow
what is vasculitis
inflammatory cells within the blood vessel wall
what are the infectious causes of vasculitis
viral, bacterial, mycotic, parasitic
ex. FIP (coronavirus)
what are the non-infectious causes of vasculitis
immune-mediated, toxic
what are the possible lesions of vasculitis
- edema
- hemorrhage
- necrosis/infarction
how does feline infectious peritonitis and pyogranulomatous vasculitis lead to infarction
infarction because pyogranulomatous inflammation (pus, neutrophils and macrophages)
commonly seen in kidneys, gut and abdominal and chest cavity, sometimes brain
what is an example of bacterial vasculitis
omphalophlebitis (navel-ill)
umbilical vein: affected
inflammation of umbilical vein gets into heart and then to systemic circulation –> present with polyarthritis of joints
what is an example of parasitic vasculitis
angiostrongylus vasorum
green and yellow lesions in lung (eosinophils)
larvae and eggs in the lung
what is a thrombus
when normal hemostais is disrupted and a solid mass forms within vessels from blood constituents
draw a flow chart explaining how virchow’s triad leads to a thrombus
what is saddle thrombi in cats and what is it associated with and what do they present with
feline aortic thromboembolism
ventricle thickens –> atrium dilates because blood gathers here –> distention –> might throw a clot into systemic circulation –> causes problem when decrease in lumen size when aorta splits (iliac arteries)
associated with hypertrophic cardiomyopathy
cold back feet, blue, collapsed, act fast
what is pulmonary artery thrombosis in dogs and what causes it
heartworm disease (dirofilaria immitis)
what is an example of thrombosis and occlusion in arterial circulation
mesenteric arteritis in horses
strongylus vulgaris
inflammation and thrombosis due to migrating larvae (L4)
commonly seen in cranial mesenteric artery –> no blood flow –> undergoes ischemia, infarction, necrosis
presents as colic
what are the causes of thrombosis in venous circulation
- iatrogenic: catheterization (ex. jugular vein thrombosis)
- portal vein thrombosis: development of accessory circulation (little vessels that can form shunts)
- vena caval syndrome
what is shown here
portal vein thrombosis
accessory portal circulation due to venous occlusion
what is vena caval syndrome
occlusion of vena cava by infiltration, thrombosis or compression
what is vena caval syndrome in dogs
secondary to heartworm infection, neoplasia (heart base tumour –> blood can’t get past)
venous congestion, pleural effusion
what is vena caval syndrome in cattle
secondary to hepatic abscesses
hepatic venous congestion, pulmonary thromboembolism
what is the pathology when caudal vena cava thrombosis ruptures
can rupture
embolic arteritis and aneurysm
causes hemoptysis (cough blood)
what is lymphatic diseases (3)
- lymphangiectasis (ex. intestinal lymphangiectasia)
- rupture of lymphatic ducts
- lymphangitis
thinner walled than blood vessels but show similar range of lesions
what occurs in rupture of lymphatic ducts in thorax and abdomen
- thorax: thoracic duct rupture –> chylothorax
- abdomen: cisterna chyli rupture, chylous ascities
what are the causes of lymphangitis
- systemic infections
- granulomatous lymphangitis (Johne’s, Actinobacillosis) - idiopathic: sporadic lymphangitis in horses
what is another name for omphalophlebitis and what vessel does the infection travel up
navel ill
umbilical vein
what are 2 major underlying mechanisms of hypoalbuminemia
- failure of liver production (liver failure)
- loss of albumin (intestinal malabsorption –> Johne’s, IBD; renal failure –> nephrotic syndrome; parasitic infection –> severe abdominal blood loss)
what is saddle thrombosis and what species does it affect and what is the pathogenesis
cats
feline aortic thromboembolism associated with hypertrophic cardiomyopathy
ventricle thickens –> atrium dilates because blood gathers here –> distended left atrium –> might throw a clot –> into systemic circulation down aorta –> causes problem when decrease in lumen size at aortic trifurcation (iliac arteries)
