Myocarditis, Cardiomyopathies and Hypertensive Heart Disease Flashcards
cardiomyopathy
•abnormality or disease of the cardiac muscle cells, occurring in the absence of other known mechanisms for myocardial injury (excluding, for example, ischemic heart disease, valvular and congenital abnormalities, hypertensive heart disease, etc…)
primary cardiomyopathy
•primary involvement is myocardial and of unknown etiology
secondary cardiomyopathy
•associated with, but not completely explained by, another form of heart disease (e.g. myocarditis) or secondary to a systemic condition (e.g. pregnancy, amyloidosis or hematochromatosis) 1. not all patients with myocarditis develop a cardiomyopathy 2. only rare pregnant women develop postpartum cardiomyopathy
dilated cardiomyopathy
•60% of cases present with idiopathic, primary form of dilated cardiomyopathy, many of which are also familial and heritable - gene mutations •the other 40% present as secondary cardiomyopathy including: 1. alcoholism 2. previous myocarditis 3. pregnancy (postpartum cardiomyopathy) 4. exposure to certain drugs or toxins, especially doxorubicin (a chemotherapy agent) •physiologic consequences: systolic disorder (decreased contractility of LV with decreased ejection fraction), with LV hypertrophy and dilatation, and arrhythmias; may result in heart failure or sudden death
hypertrophic cardiomyopathy
•hypertrophy of ventricular septum (often asymmetric, being most prominent near the mitral valve; septum markedly hypertrophied but other areas of the ventricle are not) •myocyte disarray seen in septum •100% of cases are associated with gene mutations that encode various sarcomere proteins •physiologic consequences: diastolic disorder (decreased LV compliance with decreased LV filling), with asymmetric septal hypertrophy (but no dilatation) and dynamic LV outflow tract obstruction; often results in sudden death at a young age, especially in young athletes
– Increased blood flow pulls the anterior leaflet of the mitral valve into the outflow tract, where the septum is already protruding
– Obstruction increases with decreased ventricular volume and decreases with increased ventricular volume
– Exacerbated by exercise
restrictive cardiomyopathy
- increased cardiac wall stiffness )decreased compliance) which limits ventricular stretch and results in decreased cardiac filling •50% of cases are associated with amyloidosis - myocardium becomes stiff and waxy •blood eosinophilia (35% of cases) –> endocardial fibrosis and stiffening of the ventricles •other rare associations also occur •physiologic consequences: diastolic disorder (decreased ventricular compliance with decreased ventricular filling), bilateral dilation and usually normal systolic function, may result in heart failure or sudden death
- least common
arrhythmogenic cardiomyopathy
- rare •fibrosis and fatty replacement of the ventricles, esp right ventricle, with right ventricular dilatation •many cases are familial, associated with gene mutations •physiologic consequences: systolic disorder (decreased contractility of involved ventricle (s), with decreased ejection fraction, especially of the RV), with arrhythmias, often results in sudden death at a young age
- AKA: Arrhythmogenic Right Ventricular Dysplasia
- Etiology: genetic
- Develops gradually
- Ultimately, right ventricle is severely thinned
– Myocyte loss
– Fatty infiltration
– Interstitial fibrosis
• May progress to involve left side as well
myocarditis
inflammatory disease of the heart, characterized by inflammatory infiltrates in the myocardium, associated with myocyte damage
clinical features of myocarditis
•arrhythmias, EKG changes, heart failure, fever, fatigue, dyspnea
etiologies of myocarditis
- infectious (particularly viral (e.g. Coxsackie virus, influenza) but may be bacterial, TB, fungal or parasitic (Chaga’s disease) 2. hypersensitivity or autoimmune reactions (e.g. drug reactions, systemic lupus erythematosus) 3. rejection of cardiac implant 4. idiopathic (sarcoidosis, Fiedler’s myocarditis, idiopathic giant cell myocarditis)
pathologic features of myocarditis
•gross: may appear normal or with dilated ventricles, often the heart appears “flabby” •microscopic: disintegration or necrosis of myocytes, associated with inflammatory cell infiltrates (typically mononuclear in viral myocarditis and transplant rejection, neutrophilic in bacterial infections, eosinophilic in hypersensitivity myocarditis and granulomatous in fungal, TB or giant cell myocarditis)
outcome of myocarditis
•most patients recover •treatment is supportive •sudden death may result from arrhythmia or hear failure •long term prognosis is variable •important outcome in some patients is evolution into dilated cardiomyopathy
systemic hypertension
•persistent systolic pressure greather than 140mmHg or diastolic pressure greater than 90 mmHg •prevalence in US is 20-35% of the adult population; African Americans, women and elderly adults are at greater risk •about 95% of cases are idiopathic (“essential hypertension”) •rare cases are due to renal arterial narrowing or tumors (pheochromocytomas) that produce vasoactive hormones that constrict blood vessels
criteria for diagnosing hypertensive heart disease
- cardiac enlargement, characterized by LV hypertrophy without dilatation 2. absence of other etiologic factors which would produce LV hypertrophy 3. history of hypertension
pathogenesis of hypertensive heart disease
•vascular changes: systemic arterioles become narrowed (arteriosclerosis), increased peripheral vascular resistance (increased afterload) —> LV hypertrophy •mild myocardial hypoxia: increasing size of myocytes, diffusion distance increases for O2 transport from capillaries to individual myocytes, leading to mild hypoxia in the myocardium
•left ventricular hypertrophy without dilatation and a normal heart
•normal heart and left ventricular hypertrophy with dilation
- myocarditis
- In acute phase, may show mottling of the myocardium, dilated chambers, and flabby/floppy consistency
- In chronic/healed disease, after inflammation resolves, looks like every other dilated cardiomyopathy
- lymphocytic myocarditis
- Most common type of myocarditis
- Infiltrate is predominantly lymphocytes
- Typical of viral etiology, transplant rejection
- parasitic myocarditis - Chaga’s disease
- Myofiber filled with trypanosomes at arrow
- Affects up to ½ of population in endemic areas of S. America.
- Most cases involve heart
- Inflammatory infiltrate of neutrophils, lymphs, macrophages, occasional eosinophils
- Parasites seen in scattered myofibers
- Individual fiber necrosis
•hypersensitivity myocarditis
– Prominent eosinophils
– Associated with drug allergies
•giant cell myocarditis
– Prominent giant cells
– Often extensive necrosis
– Poor prognosis
-granulamatous
- healed myocarditis
- Healed myocardium may show no residual changes or only nonspecific patchy fibrosis, as seen here
- Once healed, causes of myocarditis are indistinguishable
- dilated cardiomyopathy
- Whatever the etiology, the morphology is the same:
– Heart is large, heavy and flabby
– Dilation of all 4 chambers
• Mural thrombi are common
- Myocyte hypertrophy
- Patchy interstitial fibrosis
– Local ischemic injury (remember pathologic hypertrophy is relatively hypoxic)
• NOT SPECIFIC
- hypertrophic cardiomyopathy
- Thick walled, heavy, without dilation
- Usually, septum is disproportionately thickened (“asymmetric septal hypertrophy”) , especially in subaortic region
– “banana” shaped LV
• Hypertrophy is symmetrical in @ 10%
- microscopic hypertrophic cardiomyopathy
- Myofiber disarray
– Haphazard disorganization of myocytes
– Disorganization of contractile elements within the cells
• Extreme hypertrophy of myocytes
– Degree rarely seen in anything else
– Not specific
• Interstitial and replacement fibrosis (due to ischemia- pressure on local vessels)
– Not specific
•restrictive cardiomyopathy
-cardiac amyloidosis
• May occur with or without systemic amyloidosis
– “senile cardiac amyloidosis”
- Usually leads to restrictive physiology but may produce dilation, arrhythmias, valve disease as well
- Gross
– Varies from normal to firm and thickened
– Small semitranslucent nodules (“drops of wax”) on the atrial endocardial surfaces, particularly the left
•restrictive cardiomyopathy
-cardiac amyloidosis microscopic
Amyloid deposits in interstitium, valves, endocardium, intramural coronary arteries
- Rings around myocytes and capillaries
- Can cause vascular compression and occlusion
endomyocardial diseases
•restrictive cardiomyopathy
-endomyocardial disease
• Endomyocardial fibrosis
– Affects ventricles only
– Children in tropical areas
– Etiology unknown
• Loeffler endomyocarditis
– Damage by eosinophils leads to endomyocardial fibrosis
– May accompany eosinophilic leukemia
• Endocardial fibroelastosis
– Congenital, often associated with other anomalies
– Most common in first two years of life
– Usually left ventricle only
- hypertension
- Narrowing of systemic arterioles results in increased peripheral vascular resistance (increased afterload)
- To compensate, left ventricle undergoes hypertrophy
– Myocytes increase in size
– Wall may be over 2 cm thick
– Heart weight may exceed 500 g
– No ventricular dilation
