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In what 7 ways can the heart respond to injury?
hypertrophy, necrosis/degeneratoin, fibrosis, thrombosis, inflammation, inflammation, neoplasia, mineralization
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Hypertrophy occurs when ___________; it is considered a change in _________, but cardiomyocytes do not ____________, hence hypertrophy.
synthesis of cell components> breakdown; cardiac mass; multiply postnatally
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What are the 3 categories of cardiac hypertrophy?
concentric, eccentric, mixed
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Concentric hypertrophy is a response to __________; 2 causes can be...
increased afterload; aortic or pulmonic stenosis, systemic hypertension.
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Describe concentric hypertrophy grossly.
more mass (thicker wall) and lumen is compressed or smaller
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Eccentric cardiac hypertrophy occurs in response to __________; 2 possible causes of this include...
increased preload; valve regurgitation (extra blood flow), volume overload
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Describe eccentric hypertrophy grossly.
chamber is dilated, increased mass, circumference of wall increased
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Describe mixed cardiac hypertrophy grossly.
wall is thicker, chamber is dilated, more mass
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Mixed cardiac hypertrophy occurs in response to __(2)__; possible causes of this include... (2)
increased afterload and preload; pulmonary hypertension and tricuspid regurgitation, pulmonic/aortic stenosis and valve insufficiency [end stage heart]
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With concentric hypertrophy, there is __________ dysfunction; sarcomeres are added ___________.
diastolic (heart cannot relax to accommodate volume); in parallel
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With eccentric hypertrophy, there is ___________ dysfunction; sarcomeres are added ____________.
systolic (heart cannot contract very well); in series (along their long axis as opposed to along their width)
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What kind of hypertrophy do you see with end stage heart disease?
mixed cardiac hypertrophy
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Hypertrophic cells have impaired __(2)__ over time, and _________ density does not keep up with hypertrophy, leading to... (4)
contraction and compliance; capillary density; degeneration, necrosis, or apoptosis, and replacement fibrosis
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What morphologic changes are associated with cardiac degeneration? (2)
sarcoplasmic vacuolation (distended SR), myofibrillar lysis
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Delivery of intracellular components to lysosomes for degradation in order to generate energy so it can stay alive.
autophagy
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Uncontrolled cell death that is ALWAYS considered pathologic, stimulating tissue reaction.
necrosis
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Programmed cell death that can either be pathologic or physiologic.
apoptosis
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What are causes of necrosis? (4)
ischemia, hypoxia, oxidative injury (toxins, inflammatory mediators- membrane damage), mitochondrial excitotoxicity (too much Ca2+- catecholamines)
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Accumulation of intracellular calcium with hypercontraction of cardiomyocytes.
contraction band necrosis (histopath change)
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Coronary blood flow is determined by... (3)
pressure gradient, time in diastole, coronary vascular resistnace
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Ischemic injury often manifests in the _____________.
subendocardial myocardium
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Ischemic damage is usually _________ than hypoxic damage.
worse than
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What nutritional deficiencies cause myocardial necrosis in cattle, sheep, and pigs? Even if these nutrients are adequate in diet, what else can lead to the same effects?
Vit E and Selenium; exposure to oxidative agents (drugs or Se agonists)
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What are causes of nutritional myocardial necrosis? (3)
Vit E/Se deficiency/ exposure to antagonists, free radical injury, rapid postnatal growth
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Toxic myocardial degeneration/necrosis can be caused by... (7)
Doxorubicin, Ionophores, Cardial glycosides, Gossypol (plant), Saccharated iron, Thallium, Blister beetle (cantharidin)
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Myocardial fibrosis is deposition of __________; it is a non-specific response to... (4)
type I collagen; cell death, senescence, inflammation, direct stimulation of fibroblasts
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What are important mediators of myocardial fibrosis? (2)
angiotensin II, TGF-beta
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Replacement fibrosis is when collagen ____________; reactive fibrosis is ___(3)___.
replaces cardiomyocytes; perivascular, interstitial, and/or subendothelial
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Fibrosis impacts... (4)
contractile function, compliance, electrical conduction, cardiomyocyte perfusion
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More important than amount of fibrosis is __________ of fibrosis.
location (within the heart)
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What are the components of Virchow's triad for thrombosis?
endothelial damage, altered blood flow, hypercoaguability
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What is the difference between a pale and a hemorrhagic infarct?
- pale: artery is occluded, so no blood can enter
- hemorrhagic: vein is occluded, so blood can enter but cannot leave
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__________ is sequelae of thrombosis, which consists of activation of ___________, including __(2)__.
Thrombolysis; fibrinolytic (plasmin) system; plasminogen activators and factor XII dependent pathway
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How is thrombus recanalization used to stage lesions? (3)
- no evidence of thrombus recanalization- less than 3 days
- hypercellularity- a few days old
- recanalization- more chronic lesion
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What are causes of myocardial infarctions? (3)
primary vascular disease (atherosclerosis- humans and pigs, vasculitis), thrombosis, thromboembolic disease
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With feline hypertrophic cardiomyopathy (HCM), there is __________ dysfunction, __________ hypertrophy, and maybe __(2)__ of the _________.
diastolic; concentric; infarction or thinning; LV apex
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What breed has heritable feline hypertrophic cardiomyopathy (HCM)?
Maine Coon
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What must you rule out before you can diagnose feline HCM? (2) Why?
r/o hyperthyroidism (T4 is tropic for heart muscle--> hypertrophy) and systemic hypertension (heart muscle is working harder--> hypertrophy)
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What are lesions commonly associated with feline HCM? (6)
thickened LV, myofiber disarray, dilated LA--> turbulent blood flow--> +/- LA thrombus--> +/- saddle thrombus
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What histologic findings are associated with canine dilated cardiomyopathy (DCM)? (5)
fibrosis, attenuated wavy myofibers, fatty infiltration, fibrofatty replacement, cardiomyocyte atrophy
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What causes secondary dilated cardiomyopathy in cats? (6)
ischemia, cellular infiltration (inflammatory, neoplastic), nutritional (taurine deficiency), toxic, volume overload (compensation), sustained tachycardia
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How is ARVC definitively diagnosed?
EKG
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What breeds are at risk for arrhythmogenic RV cardiomyopathy?
Boxers and Bulldogs
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With arrhythmogenic RV cardiomyopathy, there is _________ hypertrophy and __________ dysfunction; it is caused by...
eccentric; systolic; an intrinsic defect in cardiac muscle (intercalated discs)
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Mixed hypertrophy is seen with __________; on histology, there is...
end stage heart; extensive fibrous replacement of myocardium (cardiomyopathy of volume overload)
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Myocarditis is hard to distinguish from __(2)__ grossly; they are distinguished by _________.
necrosis and fibrosis; histopathology
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Suppurative myocarditis:
Gross appearance:
Pathogenesis:
Specific examples: (4)
- Suppurative myocarditis:
- Gross appearance: red- hemorrhage/congestion
- Pathogenesis: hematogenous spread of pathogens
- Specific examples: Clostridium chaveoi (cattle), Histophilus somni (cattle), Erysipelothrix (swine), Streptococcus (pigs)
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What is the gross appearance of necrotizing myocarditis?
small white foci [need histo to confirm necrosis]
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Viral myocarditis is __(2)__; specific examples include... (5)
necrotizing, lymphoplasmacytic; [birds] WNV and polyoma virus, [ruminants] foot and mouth dz, [dogs] parvovirus and CHV
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Trypanosoma cruzi causes ___________ myocarditis.
lymphoplasmacytic
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What is eosinophilic myocarditis associated with? (2)
parasitic (Trichinella, Cystiercus), immune mediated
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What is pyogranulomatous and granulomatous myocarditis associated with? (5)
macrophages, higher order bacteria, immune mediated, fungal, +/- toxic
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Describe the gross morphology of endomyocardial fibrosis in cats? (3)
band of fibrous tissue bridging LV, severe LA enlargement, +/- diffuse endomyocardial scarring
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How is endomyocardial fibrosis in cats thought to occur?
stressful event--> post-inflammatory--> death
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What systemic lesions occur with right-sided heart failure? (3)
hepatic congestion, splanchnic congestion, effusions
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What systemic lesion is associated with left sided heart failure?
pulmonary edema
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Pulmonary edema associated with left-sided heart failure leads to... (4)
occludes airspaces, impairs perfusion, decreased lung compliance, dilation of pulmonary veins leading to bronchoconstriction
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Degenerative valve disease is most frequently associated with the _________ valve; grossly, it appears...
mitral; raised, smooth, white, glistening nodules.
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What causes degenerative valve disease?
multifactorial: thought to have a genetic component
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What is the "jet lesion" associated with?
linear endocardial proliferation and fibrosis due to degenerative valve disease
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What is the gross pathology associated with endocarditis? (3) Histological appearance? (4)
thickened, roughened valve, vegetative projection; fibrin, neutrophils, necrotic debris, bacteria
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What are causes of endocarditis? (5)
recurrent bacteremia, sepsis, thromboembolic disease, immune mediated disease, cardiac disease
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Endocarditis is usually associated with the ________ valve in cattle and _________ valve in dogs.
tricuspid/pulmonic; mitral/aortic
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What are specific etiologic causes of endocarditis? (6)
T. pyogenes (cattle), Erysipelothrix (pigs), Strep equi (horses), Staph/Strep/Bartonella (dogs)
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What is endocardial ulceration and mineralization associated with?
uremia
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Acute infectious pericarditis has ____________; chronic manifests as ____________.
fibrinosuppurative exudate; fibrous adhesions
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What are specific etiologic causes of infectious pericarditis? (3)
T. pyogenes (cattle), Strep/Actinobacillus (horses)
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Describe hemangiosarcoma clinically. (5)
endothelial neoplasia, mets widely, aggressive [rupture, hemopericardium, tamponade]
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What are predilection sites for hemangiosarcoma? (2)
right atrium and auricle, spleen
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What is you top differential for white infiltrating tissue in the myocardium of a cow? How about in a cat?
- Cow: BLV--> lymphosarcoma
- Cat: spontaneous, FeLV
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Describe the gross appearance of heart base tumors? (3)
solid white mass around aorta, pericardial effusion, indistinguishable grossly from ectopic thyroid carcinoma
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Where would mesothelioma occur in the heart?
lining pericardial cavity and epicardium
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How does mesothelioma of the heart appear grossly? (2)
velvety mesothelial surface, solid white nodules
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