2nd Exam: Myocardial Disease Flashcards
When does the heart undergo hyperplasia?
never
Causes of hypertrophy:
work (adaptive change), GF’s, i.e., myotrophin causing myocyte hypertrophy (activation of sig pw), inc expression of filament genes
These grow in hypertrophy:
contractile filaments, cytoplasm
3 types of hypertrophy:
concentric, eccentric, compensatory
Myocardium will hypertropy in response to:
an infarct
Types of compensatory hypertrophy:
diffuse, localized
compensatory hypertrophy is a response to:
loss of myocardium, i.e., MI, aging
Concentric hypertrophy is a response to:
pressure overload, hypertension, R ven looks about normal size
Indicative of concentric hypertrophy:
P overload, hypertension, stronger initially, heavy heart, thick ven wall, smaller ven chamber, inc diameter of myoctes, large nuclei, sarcomeres side by side
Sarcomeres are added sided by side in ____ and end to end in ___.
concentric, eccentric
Indicative of eccentric hypertrophy:
V overload, aortic insufficiency/ regurgitation, heavy heart, dil, thin walled ven, inc length of myocytes, sarcomeres end to end, reduced # of cross bridges, chamber/wall thickness more proportional, both ven have larger chambers
Eccentric:
m. lengthening and contracting
TF? In addition to sarcomere being added end to end with eccentric hypertrophy, there is also side to side addition.
T
aortic insufficiency is aka:
aortic regurgitation
How is end diastolic volume effected with aortic insufficiency?
inc
Why does a heart w eccentric hyp look thin even though the chamber is dilating at the same time as hypertrophy?
because it is dilated
Functional issue in aortic insufficiency:
incompetent valve
Heavy heart is characteristic of:
(4) eccentric, concentric, hypertrophic and dilated/ congestive CM:
Laplace’s Law:
tension in wall = (Pressure)(radius) / 2h
What happens as the ven chamber dilates
more tension required to reduce the increased radius (volume)
TF? hypertrophy can be either pathologic or physiologic.
T
Ex of physiologic hypertrophy:
marathon runner
myotrophin:
GF, stimulates heart m., hypertrophy
aging myocardium:
fewer, smaller, weaker myocytes, interstitial fibrosis/ stiffening of heart, compensatory hypertrophy, may be accom by ischemia, hypert., etc.
Effect of reactive interstitial fibrosis:
reduced elasticity, dilation, filling, and CO
What happens after myocardial injury?
compensatory hypertrophy: Larger fibers try to compensate for smaller, weaker
Myofiber hypertrophy:
Hyperchromatic, large, blunt nuclei, large diameter fibers
Atrophic heart fibers are often seen:
in elderly
Cause of atrophy:
unclear
CM’s:
(HARDAR) hypertrophic, aging, restrictive, dilated, arrhythmogenic R ven CM
Ven usually affected be dilated CM’s:
L ven
dilated CM is aka:
congestive CM
Causes of congestive CM’s:
heterogenous group w many causes: BIG MAMA: beriberi, idiopathic, genetic, metabolic, alcohol, myocarditis, age
% of congestive CM’s that are genetic:
30-40%
TF? Inflammation of the heart can cause CM.
T
__ deficiency leads to BeriBeri:
B1
Dilated/ congestive CM:
25-50yo onset, impaired contractility/ dec inotropy, heavy heart, low EF, CHF, dilated ventricles, endocardial fibrosis, mural thrombi (systemic emboli), arrythmias, slow progression, poor prognosis, late stage, more acute disease
Why are dilated CM’s slowly progressive?
bc the diseases that cause them are
This CM often simmers for a long time before it is noticed:
dilated CM
Myopathy in which the heart m is infiltrated by some process like a tumor, heart can’t completely fill:
restrictive CM
3 types of CM’s:
dilated/ congestive, hypertrophic, restrictive
How is the L atrium affect for each CM?
Similar inc in size for all 3
L vent: inc in chamber size, small decrease, if at all, in chamber size, decrease in chamber size:
dilated, restrictive, hypertrophic
Leads to mural thrombus formation in dilated CMs:
blood stasis
Dilated CM pathology:
nonspecific, variation in fiber size, interstitial fibrosis
There is increased ___ in dilated CM:
fibrosis, collagen
Metabolic CM’s:
hemochromatosis, mito d., glycogen/lipid/ mucopolysaccharide/ mineral storage d.’s (i.e., iron, copper)
hemochromatosis
hereditary, iron storage d., iron salt deposition, produces free radicals, leads to DM, CM, liver damage, bronze coloration of skin
Iron is removed from here in hemochromatosis:
hemosiderin
Causes of hemochromatosis (HC):
Hereditary?, hemolysis (anemia), multiple transfusion, iron deposits in liver cells and bile ducts
Why can transfusions lead to HC?
iron overload, body can’t handle
Effects of iron deposition/ HC on heart:
decreased force, brown coloration
Disease of children:
acid maltase deficiency, storage of glycogen in tongue m., macroglossia, heart m. enlarged due to dilation, globular, thick walls, dec contractility, fibers filled w glycogen, mem bound vacuoles, sarc vacuoles, PAS+
AMD sf:
Acid maltase deficiency
PAS stains for:
glycogen/ polysacs
These get filled w glycogen in AMD:
vacuoles, huge, dilated h. chamber
Genetics and Dilated CM:
dominant, recessive, or X-linked (includes dystrophin, some wo Duchenne or Becker type phenotype (muscular dystrophy)), often involves proteins in cytoskeleton, desmin aggregate disease (mutation of cytoskeleton protiens), mutation of a-actin gene
These CM’s are often protein myopathies:
dilated CMs ( L ven )
Wo dystrophin, the h. is:
weaker
Genetic CM’s:
DMD, MyD
Fxn of dystrophin:
connects membane to contratile apparatus
Case: man, substernal, crushing/. burning, elevated serum CK, EKG w ST changes:
acute MI
Type of MI assoc w chest pain:
acute (didn’t we learn that chronic coronary artery obstruction leads to angina? Yes, but this is not a MI)
Artery involved in MI:
coronary a., undergoes thrombosis
Leads to elevated CK levels in blood:
MI, myocardial necrosis
CK is found in __ cells:
myocardial
Causes of myocarditis (inflammation of heart muscle):
viral, bacterial (Rickettsia), fungi (candida), Chagas disease, toxoplasmosis, trichinosis, sarcoidosis, immune related
causes of viral myocarditis:
Coxsackie A and B, echovirus, parvovirus B19, adenovirus, CMV, HIV
Ex’s of bacterial causes of myocarditis:
DR LYENEI: diptheria, rheumatic fever, Rickettsia, Lye, Neisseria
Immune related causes of myocarditis:
Giant cell type, transplatation
Most common viral cause of myocarditis:
Coxsackie
TF? Myocarditis is a disease.
F. not per se, it is inflammation of the h.
Pt: not MI, normal angiogram, no occluded artery, think:
myocarditis
Cx ft of myocarditis:
variable symp, asymptomatic, chest pain, tachycardia, dyspnea, fatigue, EKG change, CHF in severe cases, 7% of autopsies
Acute/ fulminant viral myocarditis (MC):
often viral prodmrom-flulie, fever, arthralgia, possible sudden death
Chronic active or persistent viral MC:
less distinct onset, ven dysfunction, dilated CM
Mechs of viral MCs:
cytotoxic effect, secondary immune response, cytokine mediated
cytotoxic effect leading to viral MC:
due to causative agents (viruses) killing myocyte,
Secondary IR, viral MC:
E.g., coxsackie: IS attacks virus infected myocytes, mostly T cells
Cytokine mediated damage, viral MC’s:
Ex: IL-1, TNF, and ions
TF? Viral cultures of viral MC’s often return a true positive result.
F. often false neg
Self-limited viral MC:
A9
Severe MC:
B3, high mortality
Cellular appearance during viral MC:
lymphocyte infiltration, myocardial cell necrosis
Characteristic to MC:
Myocardial death and inflammation
Etiology of hypertrophic CMs:
familial, often dominant, mutations in sarcomere protein genes, myosin heavy chain most common
Cx px of hypertrophic CMs:
CHF, arrhythmias, sudden, unexplained death in youth
dilated/ congestive CMs are usually related to:
mutations in actin DAHM: dilated: actin, hypertrophic: myosin
Hypertrophic CM:
thick wall, esp. upper septum, heavy, big heart, aortic stenosis, contraction impaired, L ven outflow impaired bc of thick septum, leads to diastolic filling, myocyte hypertrophy, enlarged nuclei, haphazard arrangement of myocardial fibers
Haphazard myoctyte arrangement is indicative of:
hypertrophic CM
heart can’t fill/ dilate properly in this type of CM:
restricvtive
Effect of restrictive CMs on heart:
impaired ven filling, normal contraction
Causes of restrictive CM:
idiopathic, amyloidosis, sarcoidosis, tumor infiltration of h., storage disease (i.e., glycogen (infiltrated, stiffer heart can’t’ pump enough blood)
Arrhythmogenic R ven CM:
sometimes involves L ven, diverse group of d.’s, children, peak onset: 35yo, several possible causes, most likely genetic, dominant inheritance, several genes implicated, thin walled, not hypertrophic, R ven dilated, myocardium replaced by fat and scar tissue.
Cx px of Arrhythmogenic R ven CM:
bundle branch block, arrhythmias, R heart failure, sudden death
Mutations here can lead to arrhythmia:
of adhesion molecules b the myocardial fibers, can lead to sudden death
Genes usually involved in Arrhythmogenic R ven CM:
those encoding components of cardiac desmosomes (cell adhesion molecules, desmoglein 2: 1 of most imp causes
Pathogenesis of Arrythmogenic R ven CM involves:
myocyte loss
Most common mutation of Arryhthmogenic R ven CM:
desmoglein 2 mutation
Appearance of R ven with Arrhythmogenic R ven CM:
transmural fat replaces myocardium along entire lateral border of R ven, wall remains thin
Drinking this can lead to cardiomyopathy:
alcohol
