Cardiomyopathies 1 Flashcards by Kyra Porter

cardiomyopathy - definition & major categories

*a myocardial disorder in which the heart muscle is structurally and functionally abnormal, in the absence of coronary artery disease, hypertension, valve disease, and congenital heart disease sufficient to cause the observed myocardial abnormality
*note - the left atrium is dilated in all of them, which reflects long-standing increase in preload (LV EDP)
*categories:
-dilated cardiomyopathy
-restrictive cardiomyopathy
-hypertrophic cardiomyopathy
*arrhythmogenic right ventricular cardiomyopathy (ARVC)
-unclassifiable

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dilated cardiomyopathy - overview

*a condition characterized by the stretching and thinning of one or both ventricles of the heart, leading to impaired contractility
*most common cardiomyopathy
*cardiac ischemia is the most common cause

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dilated cardiomyopathy - pathogenesis

*myocyte injury → decreased contractility → decreased stroke volume →
1. increased ventricular filling pressures → pulmonary congestion (dyspnea, orthopnea, rales) and systemic congestion (JVD, hepatomegaly, edema)
2. LV dilation → mitral regurgitation
3. decreased forward cardiac output → fatigue, weakness

note - most people with dilated cardiomyopathy present with CHF

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dilated cardiomyopathy - systolic, diastolic, and RV function

systolic dysfunction: decreased LV ejection fraction; LV remodeling occurs as a means to preserve stroke volume/cardiac output
diastolic dysfunction: always present in those with systolic dysfunction; contributes significantly to development of symptoms
right ventricular function: oftentimes noted to be normal, but as LV failure worsens, can cause RV to start to fail, which is a very POOR PROGNOSTIC SIGN; RV systolic dysfunction is often an exclusion to more advanced therapy

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dilated cardiomyopathy & wall stress

*hearts with dilated cardiomyopathy are under more wall stress than normal-sized hearts and are more susceptible to ischemia (b/c dilated hearts use more oxygen per gram of tissue than a normal-sized heart)

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gross appearance of dilated cardiomyopathy

*externally: dilated heart appears more like a ball (normal heart appears more like a cone)
*internally: cords and tendons on the inside of the dilated heart are more visible and appear stretched

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etiologies of dilated cardiomyopathy

*idiopathic
*coronary artery disease
*myocarditis
*HIV
*peripartum
*alcohol
*drug-induced
*familial

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ischemic dilated cardiomyopathy

*caused by infarction of a coronary artery

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viral myocarditis - overview

*one of the most common causes of “idiopathic” cardiomyopathy
*in young adults, up to 20% of all cases of sudden death are due to myocarditis

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etiologies of viral myocarditis (common viral pathogens)

*coxsackie virus (enterovirus) = most common
*HIV
*other viruses:
-parvovirus B19
-HHV6
-influenza
-adenovirus
-echovirus
-CMV

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viral myocarditis - risk factors

*immunologic mechanism (develops weeks after the original infection)
*enhanced susceptibility: radiation, malnutrition, steroids, exercise, previous myocardial injury
*tends to be more aggressive and fulminant in infants and pregnant women

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major risk factors of a myocardial biopsy

pericardial effusion
ventricular fibrillation

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cardiac MRI and myocarditis

*looking for a band of brightness along the surface of the heart (scar)
*the white-color at surface of heart (epicardium) indicates scar/injury from viral infection or inflammation

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HIV cardiomyopathy

*characterized as symptomatic systolic dysfunction associated with a dilated left ventricle
*median survival was less than 3 months prior to the introduction of anti-retroviral meds to treat HIV
*in late 1980s, roughly 1/3 of all HIV-related cardiac deaths were due to dilated cardiomyopathy

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advances in HIV cardiomyopathy

*with consistent access to antiretroviral medications and early initiation of treatment, myocarditis and dilated cardiomyopathy have virtually disappeared
*burden of cardiac disease in HIV patients now is transitioning toward increasing atherosclerosis and ischemic heart disease

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peripartum cardiomyopathy

*clear relationship to recent pregnancy:
-symptoms can start during third trimester, and usually start within one to five months postpartum
*no identifiable cause or pre-existing cardiac disease
*exact etiology unclear (maternal autoimmune response, inflammation/myocarditis)
-evidence of inflammation on heart biopsy is a GOOD prognostic sign

peripartum cardiomyopathy - risk factors

*maternal age > 30 yo
*twins or triplets
*preeclampsia or pregnancy-induced HTN
*long-term (>4 wks) use of tocolytic tx (tocolytics prevent premature birth in certain situations)
*cocaine use

peripartum cardiomyopathy - prognosis

*1/3 recover completely
*1/3 stabilize (never quite normal again, but stable)
*1/3 progress (get worse and worse)
note - high risk for thromboembolism (DVT, arterial thomboembolism, etc)

peripartum cardiomyopathy in women with persistent LV dysfunction (do not have complete recovery)

*high risk of death or permanent worsening of cardiomyopathy with subsequent pregnancy
*advice to patient = NEVER GET PREGNANT AGAIN
*surgical sterilization is highly recommended

peripartum cardiomyopathy in women with complete recovery

*substantial risk of recurrent cardiomyopathy with subsequent pregnancy and may not return to normal next time
*no clear guidelines due to no way to predict outcomes:
-persistent LV dysfunction: subsequent pregnancy is an unbelievably bad idea
-presumed complete recovery: subsequent pregnancy is still a potentially bad idea

peripartum cardiomyopathy - treatment

*guideline-directed medical therapy for CHF
*cannot give ACE inhibitors/ARBs while pregnant or breast feeding
*consider anticoagulation due to higher risk of thromboembolism

acute effects of alcohol on LV function in healthy subjects

*light intoxication: LVEF decreased by 5%
*heavy intoxication: LVEF decreased by 11%
*findings suggest that in healthy subjects alcohol intoxication causes a dose-dependent impairment of cardiac contractility

alcoholic cardiomyopathy

*caused by long-term, excessive use of alcohol
*cardiac contractility reduced due to the direct effect of ethanol
*usually occurs in males age 30-50
*may be complicated by vitamin deficiencies, particularly B1, which causes tachycardia, vasodilation, and dilated CM in its own right
*treatment:
-abstain from alcohol
-guideline-directed medical therapy for CHF

tachycardia-mediated cardiomyopathy

*atrial fibrillation with rapid ventricular response most likely rhythm issue
*rate must be continuously elevated for weeks on end
*prognosis very good if tachycardia can be eliminated
*if you care tachycardia and LVEF normalizes, then you cured tachycardia-mediated cardiomyopathy
*if you cure tachycardia and LVEF stays low: most likely, the tachycardia is a symptom, not the cause

familial cardiomyopathy

*a family history of dilated cardiomyopathy without other cause *in general, genetic testing is not performed b/c it does not change management *mutations in various proteins identified, including cytoskeletal proteins, myofibrillar proteins, and nuclear membrane proteins

Chagas disease

*Chagas disease is a tropical parasitic disease caused by the protist **Trypanosoma cruzi** *after 8-12 weeks, individuals enter the chronic phase of disease and most do not produce further symptoms *some people develop further symptoms 10-30 years after initial infection, including enlargement of the ventricles, leading to heart failure *some experience an enlarged esophagus or an enlarged colon

distribution of Chagas disease

*predominantly in Central and South America

Chagas disease & cardiac complications

*most common cardiac complications of Chagas disease are: -LV dilation and dysfunction -LV aneurysm -CHF -thromboembolism -ventricular arrhythmias -sudden cardiac death -cardiac conduction system abnormalities *CHF usually appears at least 20 years after original infection

restrictive cardiomyopathy - overview

*primary problem = **very stiff ventricle in the absence of significant hypertension or aortic stenosis** *LV is unable to relax, leading to HFpEF [increased LVEDP and increased RVEDP; s/s of left or right CHF] *systolic function may or may not be normal *prognosis is poor for most types

restrictive cardiomyopathy - pathogenesis

*rigid myocardium → 1. increased diastolic ventricular pressure → venous congestion → JVD, hepatomegaly, ascites, peripheral edema, dyspnea, orthopnea, rales 2. decreased ventricular filling → decreased cardiac output → weakness, fatigue *most people with restrictive cardiomyopathy present with CHF

types of restrictive cardiomyopathy

1. infiltration of myocardium (amyloid, sarcoid) 2. fibrosis or scarring (scleroderma, Loeffler's endocarditis) 3. abnormal deposition in myocardium (hemochromatosis [deposition of iron], Fabry's disease)

cardiac amyloidosis restrictive cardiomyopathy

*comprises a group of disorders characterized by the extracellular deposition of ABNORMALLY-FOLDED FIBRILLARY PROTEINS, leading to loss of normal tissue architecture *CARDIAC AMYLOIDOSIS IS THE POSTER-CHILD for restrictive cardiomyopathy

AL amyloidosis restrictive cardiomyopathy

*L, think **leukemia/lymphoma** *AL amyloidosis is due to **deposition of protein derived from IMMUNOGLOBULIN LIGHT CHAIN FRAGMENTS** *age of onset: 60 yrs *highest incidence in those with **plasma cell dyscrasia** in which a monoclonal immunoglobulin is detectable in the serum or monoclonal light chains in the urine

AA amyloidosis restrictive cardiomyopathy

*A, think arthritis *amyloidosis associated with **chronic inflammatory states** such as rheumatoid arthritis, spondyloarthropathy, or inflammatory bowel disease

AF amyloidosis restrictive cardiomyopathy

*F, think Fogey/Familial *can happen in one of 2 ways: 1. **deposition of otherwise normal (wild-type) transthyretin** in myocardium and other sites as a consequence of age (age of onset > 75) 2. genetic syndrome involving a **mutation in transthyretin which leads to early deposition of transthyretin** in the heart and other organs (age of onset 30-50)

amyloidosis restrictive cardiomyopathy - diagnostic testing

*fat-pad biopsy showing reflection/refraction of light with Congo Red Stain *cardiac MRI: significant amount of amyloid deposition changes the magnetic properties of the heart; myocardium turns black before blood *EKG showing LOW VOLTAGE; may have a pseudo-infarct pattern

amyloidosis restrictive cardiomyopathy - echo findings

*thickened walls in LV and RV *thickened heart valves

novel therapies for TTR cardiac amyloidosis

*tafamidis binds to TTR tetramer to slow disease progression *inotersen and patisiran work by cleaving to and disabling amyloid messenger RNA, a mechanism known as RNA silencing; siRNA drugs produce a reduction in circulating familial and wild-type TTR of ~80%