Cardiomyopathy and anti-arrythmatic Flashcards
What are the features of the heart in dilated cardiomyopathy?
progressive cardiac dilation
systolic dysfunction
hypertrophy
enlarged, heavy flabby heart
What are common causes of dilated cardiomyopathy?
ischemia valvular HTN idiopathic familial inflammmatory-infectious toxic metabolic nutritional neuromusc
What percentage of dilated myopaties are indicated by genetic casues?
20-50% majority autosomal dominant mutations encoding cytoskeleton proteins
What viruses have been linked to dilated cardiomyopathy?
coxasckie B or echovirus, self limited in young ppl
unclear mecchanism
What two ways can alcohol cause dilated cardiomyopathy?
alcohol: direct toxic effect myocardium
alcohol: indirect toxic effect associated with thiamine disease (beriberi disease0
What chemotherapy drug can lead to dilated cardiomyopathy
doxorubicin as well as other anthracyclines, which is dose dependent
What is the dilated cardiomyopathy due to pregnancy?
peripartum cardiomyopathy; late in pregnancy or several weeks to months posptartum; probable cause HTN volume overload nutritional def prolactin
What is the dilated cardiomyopathy gross morphology?
four chamber dilation variable thickness mural thrombi valves are normal, but may have tricuspid or mtiral regurg cardiomegaly
What is the histology associated with dialted cardiomyopathy?
myocyte hypertrophy
interstital & endocardial fibrosis; no necrsois
not specific for DCM unless iron overload is cause adn iron present
What puts you at increased risk for idiopathic dilated cardiomyopathy
black
male
HTN
chronic Beta-agonist; relatively rare
How does idiopathic dilated cardiomyopathy usually present?
heart failure symtpoms
or anginal chest pain
occasionally sudden death
What are the treatmments for dilated cardiomyopahty?
ACE inhibitor, other diuretics potassium/magnesium beta blocker digoxin in face of persistnent syndromes wafarin-with thrombus/afib ICD- MI oruncontrolled vT
What is the definition of arrhythmogenic right ventricular cardiomyopathy?
inherited disease of cardiac muscle
right ventricle failure and various rythm disturbance
sudden death possible
–right ventricle is severely thinned bc of loss of myocytes with extensive fatty infiltration and fibrosis—
What is the inheritance of arrhythmogenic right ventricular cardiomyopathy?
autosomal dominant
Where is the defect in arrhythmogenic right ventricular cardiomyopahty?
defective cell adhesion proteins in desmosomes that link adjacent cardiac myocytes
What is the clinical syndrome associated with arrhythmogenic right ventricular cardiomyopathy?
young adults
arrhythmia (VTach)
sudden death
right ventricular failure
What is the morphology of arrhythmogenic right ventricular cardio?
thin & dilated right ventricular wall with fatty infiltration (essential feature) and intersitial fibrosis
What is hypertrophic cardiomyopathy?
myocardial hypertrophy, with abnormal diastolic filling, poorly complian
heart is thick-walled, heavy and hypercontracting
priimarily diastolic dysfunction, systolic functio usually perserved
ventricular outflow obstruction
What is the gross morphology of HCM
massive myocardial hypertrophy, frequent disporportionate thickening of septum
endocardial thickening and mural plaques in outflow tract
What is the histology of HCM?
marked hypertrophy
intersitial fibrosis
myofiber disarray
intersitial fibrosis
What are the mutations associated with HCM?
increase myofilament activation resutling in myocyte cotnractility
missesnse in sarcomeric proteins
myosin heavy chain
myosin binding protein
cardiac TnT
DEFECTS IN DIRECT SARCOMERE FUNCTION
DEFECT IN TRANSFER OF ENERGY TO SARCOMERE
What is the genetic inheritance of HCM?
prognosis correlated with mutation
familiail, AD, Variable expression
one of the most common causes of sudden unexplained death in athletes
What are the arrythmias associated with HCM?
paroxysmal supraventricular arrthmias
Afib
Non-sustained ventricular tachy
sustained ventricular tachy/ventricular fibrillation
What are the clinical features of HCM?
presentation after puberty
asymptomatic frequently
sudden death in young athletes
syncope due to left ventricular outflow obstruction
Tx: surgical excision, ventricular relaxing drugs
What are the risk facctors for cardiac death in HCM?
marked ventricular hypertrophy young age hypotension on excercise syncope hx of aborted cardiac rest FHx of sudden cardiac death certain geneti mutations
What is used to treat HCM
Beta blockers
What is a dual chamber pacemaker used for?
HCM, used in pts with sxs who cant tolerate surgical therapy
How do you prevent sudden cardiac death in HCM pts?
pts at high risk receive implantable cardioverter-defibrillators
What is restrictive cardiomopathy?
primary deccrease in ventricular compliance resulting in impaired ventricular during
-idiopathic
-secondary to
-post radiation fibrosis
-amyloidosis
sarcoidosis
metastases
inborn error of metabolism
What is restrictive cardiomyopathy morphology gross?
- normal ventricles
- bi-atrial dilation
- firm myocardium
- interstital fibrosis
What si restrictive cardiomyopathy histology?
patchy or diffuse intersitial fibrosis and disease specific changes
What is the clinical features of RCM?
congestive heart failure --severe pulmonary congestion --hepatic congestion similar S/S as constricitve pericarditis Dx: endomyocardial biopsy
What happens in senile cardiac amyloidosis?
transthyretin (prealbumin)-deposits in ventricles and atria
>60 yrs of age
AA majority
What are the restrictive hemodynamics?
asymptomatic
pressure atrophy of fibers
deposition in regions of conduction system leads to arrhythmiass
Loeffler endomyocarditis?
endomyocardial fibrosis, large mural thrombi, peripheral eosinophilia, eosinophilic infiltrates in organs
Endocardial fibroelastosis is indicated by what?
common first two years of life, in young children in africa, focal or diffuse fibroelatic thickening
What can hyperthyroidism cause with respect to the heart?
tachy, palpitations and cardiomegaly
What can hypothyroidism cause with respect to the heart?
CO is decreased
flabby, enlarged and dilated
myofiber swelling
What is the effect of catecholamines on the heart when induced either in intesnse stress or froma pheochromocytoma?
takotsubo cardiomyopathy
What is afterdepolarizations?
spontaneous action potentials during or immediately after phase 3 repolarization. Produced by abnormal Ca2+ influx during or after phase 3 of ventricular action potential
leading to premature contractions and ventricular tachycardia
observeed with digoxin toxicity and conditions that prolong QT interval
Quinidine therapy results in what?
action potential prolognation increased QT duration, early afterdepolarizations and torsade de pointes
Class 1 are sodium channel blockers do what?
bind fast sodium channels in the open and inactivated states and dissociate from channels during resting state
What is in ddrug class 1a?
quinidine, procainamide, disopyramide
What is the drug dissociationrate of drug class 1a?
slow
What is the drug dissociation of drug class 1B?
lidocaine, mexilitene; rapid
What is drug dissociation rate of class 1C?
very slow
What is drug class 1a mechanism of action?
slow phase 0, and conduction velocity and prolong action portential duration and refactory period
proarrhythmic
Class 1b drugs does what?
greater affinity for inactivated vs open channel
What is special about lidocaine?
extensive first pass hepatic inactivation; more active in ischemic tissue due to less negative resting membrane, minimal effect on normal cardiac tissue
What is class 1c drugs?
block fast sodium chanels more potently than class 1 agents, slow conduction throughout heart, less effect on K+ current
What is flecainide used to treat
SVT and VT,
may inhibit Ca2+ releases from cardiac SR
What is propafenone side effects?
ventricular proarrhythmia, agranulocytosis, anemia, thrombocytopenia
What are class II Beta-blockers do?
inhibit sympathetic activation of cardiac autmoaticity and conduction
effect mainly occurs at AV node refactory period;
What are class III anti-arrhythmic drugs?
block potassium recitifier, demonstrate reverse-use dependence
with more potent Kv block occuring at slower heart rates.
What is amiodarone?
iodinated compound, half life approx 40 days
decrease SA node automaticity, decrease AV conduction velocity
What are the side effects of amiodarone?
hypothyroidism, hyperthyroidism, neulogic toxicity, and more
QT prolongation
What does amiodarone block?
Ikr and Iks
What does sotalol do?
selectively blocks beta-adrenoreceptors and delayed recitifier potassium channel
slow AV conduction velocity
blocks Ikr
What does dofetilide do?
block rapidly activating delayed recitifier channel,may prolong QT and produce TdP; blocks Ikr
What does class 4 drugs do?
block voltage gated L type Ca2+ channels
decrease AV node conduction
What is adenosine?
elimination half life rapid, decrease action potential duration and hyperpolarizing membrane potential in atrium SA and AV node
What does digoxin do?
Na-K-ATPase membrane pump,; increase itnracellular Na+ cocentration. Increase through automatic nervous system
What does class I and III act through which cells?
ventricular action potential
What does calss II and IV drugs act through cells?
SA node
