Cardiomyopathy Flashcards
What is cardiomyopathy?
Heart disease resulting from an abnormality in myocardium
What do cardiomyopathies produce?
Abnormalities in cardiac wall thickness, chamber size, mechanical and/or electrical dysfunction
What is the difference between primary or secondary cardiomyopathy?
Primary - Confined to heart muscle
Secondary - Myocardial involvement as a component of systemic or multiorgan disorder
What is the 1995 WHO Classification of Cardiomyopathy?
- Dilation: Enlarged, Systolic dysfunction
- Hypertrophic: Thickened, Diastolic dysfunction
- Restrictive: Diastolic dysfunction
- Arrhythmogenic RV dysplasia: Fibrofatty replacement
- Unclassified: Fibroelastosis, LV noncompaction
What are the characteristics of dilated cardiomyopathy? (4)
Progressive cardiac dilation
Systolic dysfunction
Hypertrophy
Enlarged, heavy, flabby, dilated heart
What are the pathologies formed by dilated cardiomyopathy?
Heart failure
Thrombi formation
Functional regurgitation
What are the etiologies causing dilated cardiomyopathy?
- Ischemic
- Valvular
- Hypertensive
- Familial
- Idiopathic
- Inflammatory (Infectious and Non-infectious)
- Toxic (Alcohol, Anthracyclins, Cocaine)
- Metabolic (Endocrine - thyroid dz, pheochromocytoma, DM, acromegaly)
- Nutritional - Thiamine, selenium, carnitine
- NM (Duchenne’s MD: X-linked)
What is the typical genetic cause of dilated cardiomyopathies by inheritance?
What percentage of dilated cardiomyopathies are due to genetic causes?
20-50% of cases
***Predominately autosomal dominant - Cytoskeletal proteins
X-Linked: Dystrophin gene
Mitochondrial genome: Oxidative phosphorylation and fatty acid B-ox
Specific genes in dilated cardiomyopathies?
Lamin A/C Delta-sarcoglycan Dystrophin Desmin Vinculin Titin Troponin-T Alpha-Tropomyosin Beta-myosin heavy chain Actin Mito DNA mutations
What specific viruses are involved in acute viral myocarditis?
How does it progress in young people?
What is the mechanism?
Coxasackie B or echovirus
Self-limited infection in young people
Mechanism: Is unclear, causes myocyte cell death and fibrosis
Immune mediated injury but no change with immunosuppressive drugs
How are iron overload cardiomyopathies formed?
Hemochromatosis
Multiple transfusions
What are alcohol’s effects related to cardiomyopathy?
Direct toxic effect on myocardium
Indirect toxic effect associated with thiamine deficiency leading to beriberi HD
What are the kinetics of anthracycline toxicity?
Dose-dependent
What is peripartum cardiomyopathy?
What are the probable causes?
Late in pregnancy or several weeks to months postpartum
Probable causes include pregnancy-associated HTN, volume overload, nutritional def., metabolic derangements, immunological reaction, prolactin
What are gross morphological treats of DCM?
Cardiomegaly (2-3 times normal weight): Globular appearance
Four chamber dilation
Variable wall thickness (normal, hypertrophy, flabby)
Mural thrombi
Normal valves typically
Mitral or tricuspid may show functional regurgitation
What histological changes appear for DCM?
Non-specific except for iron overload
Some fibers may appear stretched or irregular; no necrosis
Hypertrophy and fibrosis are usual
What is the annual incidence of idiopathic DCM?
What is the prevalence?
What risk factors are associated?
Incidence: 5-8/100K
Prevalence: 36/100K
RF: Male, black race, HTN, chronic beta-agonist usage
What are the clinical presentations of idiopathic DCM and percentages of?
HF Symptoms (75-85%)
Angina (8-20%)
Emboli: Systemic or pulmonary (1-4%)
Syncope <1%
What age does idiopathic DCM typically manifest?
What are the 2 yr and 5 yr survival rates?
What are the typical causes of death?
Age: 20-50 years
2yr: 50%, 5yr: 25%
Death due to cardiac failure, arrhythmia or thromboembolic complications?
What are the therapeutic options for cardiomyopathy?
What are there indications?
ACE Inhibitors - Symptomatic heart failure and asymptomatic LV dysfunction
ARBs - ACE intolerance
Hydralazine-nitrates - Ace intolerance
Diuretics - Volume overload
Potassium/magnesium - Diuretic-induced depletion
Beta-blockers - Symptomatic HF in addition to ACE inhibitor
Digoxin - Persistent HF despite diuretics, ACE inhibitor
Warfarin - Chronic or paroxysmal atrial fibrillation
LV thrombus or prior embolic event
ICD - Cardiac arrest; uncontrolled VT
What is arrythmogenic right ventricular CM (ARVCM)?
What is the morphological cause?
What gene is thought to cause it?
Also known as arrythmogenic right ventricular dysplasia
Right ventricular failure paired with VTach or VFib
Severely thinned due to loss of myocytes with extensive fatty infiltrates and fibrosis
Autosomal-dom inheritance related to defective cell adhesion proteins in desmosomes
What is the clinical manifestation of ARVCM?
Young adults with arrhythmia leading to possibly sudden death or RV failure
What are the characteristic features of ARVCM’s morphology?
Thin and dilated RV wall with fatty infiltrates - Essential feature
Also interstitial fibrosis
What is hypertrophic CM (HCM)?
What stage of circulation does this affect?
Myocardial hypertrophy, poorly compliant LV myocardium resutling in thick-walled, heavy, hypercontracting heart
Primarily results in diastolic dysfunction due to abnormal filling
What is the gross morphology of HCM?
Massive myocardial hypertrophy - Disproportionate thickening of septum, sub aortic region, ventricle compression
Atrium enlargement due to decreased ventricular compliance
Endocardial thickening and mural plaques in the outflow tracts due to valve contacting septum during contraction (Fcn’al outflow tract obstruction)
What is the histology of HCM?
Marked hypertrophy (>40 microns, normal 15 microns)
Interstitial fibrosis
Myofiber disarray
What is the pathogenesis of HCM?
What is the genetic pattern of HCM?
Missense mutations in genes encoding sarcomeric proteins (>400 mutations in 9 different genes): Myosin heavy chain beta-MHC, myosin binding protein MYBP-C, cardiac TnT
Results in defects in direct sarcomere function, defect in transfer of energy to sarcomere
Familial, autosomal dominant, variable expression
HCM is one of the most common causes of sudden, otherwise unexplained death in young athletes
What are the pathophysiologies of HCM?
- LV Outflow Tract Obstruction
- Mitral Regurgitation
- Diastolic Dysfunction
- Myocardial Ischemia
- Cardiac Arrythmias
What is LV outflow tract obstruction and pathogenesis?
Classic feature of HCM
Present in half of the patients, severity of the obstruction varies
Narrowed LV outflow due to hypertrophied IV septum
Anterior displacement of the mitral valve leaflets during systole (Systolic Anterior Motion of mitral valve - SAM)
What is the venturi effect?
Venturi effect: Anterior mitral valve leaflets & chordae sucked into outflow tract during mid-late systole
Results in obstruction and SAM
What causes diastolic dysfunction in HCM?
Myocardium is stiff, non-compliant
LV diastolic pressure is elevated, impaired filling
What are the mechanisms of ischemia in HCM?
Supply/demand mismatch due to increased muscle mass
Increased wall tension due to impaired relaxation during diastole
Abnormal intramyocardial arteries
What arrhythmias associated in HCM?
Paroxysmal supraventricular arrhythmias
Atrial fibrillation
Non-sustained ventricular tachycardia
Sustained ventricular tachycardia/ventricular fibrillation
What are the clinical features of HCM?
What is the treatment of HCM?
Post-puberty presentation
Symptoms: Asymptomatic, exertional dyspnea, syncope, sudden death in young athletes, atrial fibrillation with mural thrombus formation
Treatment: Surgical excision, ventricular relaxing drug
What are the risk factors for cardiac death?
Marked ventricular wall hypertrophy (>30 mm) Young age at presentation (<40 y) History of syncope History of aborted cardiac arrest Family history of sudden cardiac death Certain genetic mutations
What drugs are used to treat HCM/prevent SCD?
Beta-blockers - Negative inotropic effect
Calcium channel blockers
Disopyramide
What non-pharmacological therapies can be performed to treat HCM/prevent SCD?
Surgical septal myectomy Alcohol-induced septal ablation: 100% alcohol injection in septum, resulting in infarction Dual chamber pacemaker Cardiac transplantation Implantable Cardioverter-defibrillators
What is restrictive CM?
What are the causes of restrictive CM?
Primary decrease in ventricular compliance resulting in impaired ventricular filling during diastole
Idiopathic, post-radiation fibrosis, amyloidosis, sarcoidosis, metastases, inborn errors of metablism
What is the morphology of restrictive CM?
Normal ventricles
Bi-atrial dilation
Firm myocardium
Interstitial fibrosis
What is the histology of restrictive CM?
Patchy or diffuse interstitial fibrosis and disease specific changes
What are the clinical features of restrictive CM?
Congestive heart failure (right and left sided): Severe pulmonary and hepatic congestion
Dx: Endomyocardial biopsy
Similar symptoms as constrictive pericarditis
What are the types of amyloidosis of the heart?
Senile cardiac amyloidosis: Most common with transthyretin deposits in ventricles and atria
Systemic AA or AL amyloidosis
Restrictive hemodynamics - Asymptomatic, pressure atrophy of fibers
What is transthyretin?
Pre-albumin
What is the morphology of amyloids?
Heart- Normal or firm and rubbery
Due to eosinophilic deposits of amyloid
Congo red stain - Produces apple-green birefringence when viewed under polarized light
What is the morphology of Loeffler endomyocarditis?
What is its pathogenesis?
Endomyocardial fibrosis, large mural thrombi, peripheral eosinophilia, eosinophilic infiltrates in organs
Pathogenesis: Eosinophils release MBP which may cause endomyocardial necrosis and scarring
What is endocardial fibroelastosis?
What is the epidemiology?
Uncommon heart disease of obscure etiology with focal or diffuse fibroelastic thickening usually involving mural left ventricular endocardium
Disease of children and young adults in Africa, most common in the first 2 years of life
What are the cardiac effects in iron overload?
Hereditary hemochromatosis Heart is usually dilated Morphology: Heart is rust-brown color Hemosiderin accumulation within cardiac myocytes Fibrosis may be present
Cardiac effects in thyroid disease
What are the histological features of hypothyroidism?
Hyperthyroidism - Tachycardia, palpitations, and cardiomegaly
Hypothyroidism - CO decreased, myxedema heart is flabby, enlarged, and dilated, fluid sometimes accumulates within pericardial sac-myxedema heart
Histological features - Myofiber swelling, loss of striations and basophilic degeneration, interstitial mucopolysaccharide-rich edema fluid
What are the cardiac effects of sarcoidosis?
Restriction, conduction system disease, ventricular arrhythmias (SCD)
What are cardiotoxic drugs?
Lithium, phenothiazines, chloroquine, and cocaine-myocardial injury and sometimes sudden death
What is the cardiac effects of catecholamines?
What is a tumor which results in catecholamine release?
What is Takotsubo cardiomyopathy?
Apical ballooning during systole
Pheochromocytoma
Sudden, intense emotional or physical stress, leading to acute LV dysfunction (Broken heart syndrome)
