Myocardial Disorders Flashcards
2 classes of primary myocardial disease
- cardiomyopathy (dilated, hypertrophic, restrictive)
2. myocarditis
Primary problem in dilated cardiomyopathy?
systolic failure –> volume overload to increase preload –> all 4 chambers are eccentrically hypertrophied and contraction is worse
Primary problem in hypertrophic cardiomyopathy?
hypertrophy resulting in hypercontractility during systole but poor diastolic LV compliance due to normal ventricular cavity w/tons of concentric hypertrophy and consequent atrial dilation
*normal LVEF
Primary problem in restrictive cardiomyopathy?
poor diastolic compliance due to infiltration of cells (phages/myocytes)/amyloid/collagenthat makes ventricle stiff and consequently lead to atrial dilation
What’s the difference between a primary and secondary cardiomyopathy?
primary is predominantly myocardial vs. secondary is associated w/systemic/multiorgan disease (e.g. amyloidosis, hemochromatosis)
What kinds of proteins are often implicated in primary genetic cardiomyopathies?
- cytoskeletal
- sarcomeric
- ion channels
T/F an individual w/hypertrophic cardiomyopathy may develop DCM late in disease
T
What is the pathogenesis associated with arrhythmogenic RV cardiomyopathy?
defect in desmosomal proteins –> breakdown of myocyte connections (adhesion and communication/gap jxn) in RV –> fat replacement –> RHF + vtach/vfib
What protein is typically responsible in arrhythmogenic RV cardiomyopathy?
plakoglobin
Features of DCM?
- progressive dilation of all four chambers + hypertrophy + increased heart weight
- flabby walls
- endocardial thrombi
- hypertrophied myocytes + stretched thin myocytes + interstitial fibrosis
- reduced LVEF
What are common causes of secondary DCM?
toxins like ethanol, adriamycin, prior myocarditis, pregnancy, hemochromatosis
Pathogenesis of DCM in hemochromatosis
excess iron absorption –> cardiac deposition –> interference w/ metal dependent enzymes for ox phos
- diabetes and cirrhosis
Complications of DCM
- heart failure
- mitral insufficiency
- dysrhythmia
- emboli
Hallmark of Takotsubo cardiomyopathy
catecholamine excess –> reversible systolic dysfunciton with apical ballooning –> ECG looks like an MI
Features of HCM?
- stiff LV w/ impaired filling
- hypercontractile LV
a. w/ LV outflow obstruction in 1/3 of cases–> IHSS/HOCM
b. w/ interventricular septum effects in 90% of cases–> ASH (no dilation but asymmetric hypertrophy) - myocyte hypertrophy and disarray w/ branching
- thickened intramyocardial arteries leading to angina, dysrhythmias
What is the marker of LVOT obstruction in someone with HCM?
septal scar from repeated battering from the anterior leaflet of MV –> bacterial endocarditis
Complications of HCM
- mitral valve endocarditis
2. emboli
What is the difference in genetics between DCM and HCM?
HCM is 100% genetic vs 20-50% in DCM
How does LVOT occur in HOCM?
septal hypertrophy/ASH –> LVOT
+ elongated mitral leaflets –> in systole, can get SAM (systolic anterior motion of mitral valve) due to drag in outflow tract –> mitral regurg due to malcoaptation of of MV + dynamic LVOT
result is initial LVOT + mitral regurg + a dynamic LVOT
Mechanical txs for HOCM
- myomectomy (remove some basal septum)
2. ETOH septal ablation to shrink basal septum aka cause an MI
Clinical manifestations of HOCM
dyspnea, angina, fatigue, syncope
Physical exam in HOCM
- S4 due to diastolic dysfunction
- bifid pulse due to midsystolic obstruction
- murmur of outflow obstruction (crescendo/decrescendo) –> worsens with reduced preload
- mitral regurg
What does the movement do to a murmur of HOCM vs AS? valsalva
reduce preload/afterload –> increase HOCM, reduce in AS
What does the movement do to a murmur of HOCM vs AS? squatting
increase preload/afterload –> reduce murmur in HOCM, increase in AS
What does the movement do to a murmur of HOCM vs AS? standing
reduce preload/afterload –> increase HOCM, reduce in AS
What is a major risk of HCM?
sudden cardiac death –> VT/VF –> implantable defibrillators (AICD)
What is a known cause of collagen deposition leading to restrictive cardiomyopathy?
radiation
3 types of amyloid relevant to the heart
- ig light chain derived associated w/ multiple myeloma (b cell proliferations)
- soluble amyloid associated protein w/ rheumatoid arthritis
- transthyretein w/senile cardiac amyloid
amyloid in old people
transthyretin
amyloid in RA
SAA-soluble amyloid associated protein
amyloid in multiple myeloma
Ig light chain
Features of restrictive cardiomyopathy
- stiff ventricles + large atria
- impaired filling –> decreased CO –> weakness/fatigue
- normal ejection fraction in beginning
- elevated venous pressures/congestion –> JVD, hepatomegaly, ascities, edema
Tx of restrictive cardiomyopathy
- tx of underlying cause
- diuretics (but have to be careful b/c can reduce CO)
- digoxin (not in amyloidosis)
- rhythm drugs
- pacemaker
- anticoagulation
What is myocarditis?
inflammation in myocardium which initiates myocyte damage –> immune, infections, unknown
Immunologic causes of myocarditis?
- acute rheumatic fever
- drug hypersensitivity (eosinophils)
- post-viral (lymphocytic)
- SLE and connective tissue diseases
- transplant rejection
Which infections can lead to myocarditis?
Coxsackie, Chagas, lyme disease
MOA of viral myocarditis
t lymphocytes attack virally infected cells –> cross reacting antibodies
What does a myocarditis heart look like?
dilated, flabby heart like DCM w/normal heart weight
Clinical presentation of myocarditis
flu like illness +/- palpitation +/- chest pain to progressive/fulminant/lethal heart failure
In what cases do we get granulomas w/myocarditis?
sarcoidosis: granulomas are microscopic w/o necrosis (systemic)
giant cell myocarditis: granulomas are macroscopic and necrotizing (only in heart)
