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PATHOLOGY > Myocardial diseases > Flashcards

Myocardial diseases Flashcards

1
Q

Define cardiomyopathies

A

Cardiac diseases due to intrinsic myocardial dysfunction are termed cardiomyopathies (heart muscle diseases)

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2
Q

What are primary and secondary cardiaomyopathies?

A
  1. Primary – confined to myocardium

2. Secondary – cardiac manifestation of a systemic disorder

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3
Q

What are the classification seen in cardiomyopathies?

A
  1. Dilated cardiomyopathy (90% of cases)
  2. Hypertrophic cardiomyopathy
  3. Restrictive cardiomyopathy (least common)
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4
Q

How is dilated cardiomyopathy characterized?

A
  1. Progressive cardiac dilation

2. Contractile (systolic) dysfunction

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5
Q

What is the pathogenesis seen in DCM?

A

• At the time of diagnosis usually DCM has already progressed to end-stage disease

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6
Q

What are the genetic influences seen in DCM?

A
  • 20% to 50% of cases are familial
  • Mutations in > 50 genes have been identified
  • Autosomal dominant inheritance
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7
Q

What are the genes (mutated) involved in DCM?

A
  • Encoding cytoskeletal proteins or

- Proteins that link sarcomere to cytoskeleton (α-cardiac actin )

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8
Q

What happens in the dystrophin gene?

A

dystrophin gene mutations affecting certain cell membrane protein that couples the intracellular cytoskeleton to the ECM

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9
Q

What happens to the genes in the mitochondrial genome?

A

Mutations of genes in mitochondrial genome that encode proteins involved in oxidative phosphorylation or fatty acid β-oxidation.

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10
Q

How is the DCM infection carried out?

A

Through viral

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11
Q

How does the alcohol react to DCM?

A

• Alcohol and its metabolites have a direct toxic effect on myocardium.

• Chronic alcoholism
leads to thiamine deficiency leads to beriberi heart disease.

• Other toxic agents – doxorubicin & cobalt.

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12
Q

How does Peripartum cardiomyopathy occur?

A

Occurs late in gestation or several weeks to months postpartum

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13
Q

What is the etiology seen in Peripartum cardiomyopathy?

A

etiology includes pregnancy-associated hypertension, metabolic derangements (e.g., gestational diabetes) volume overload, nutritional deficiency, metabolic derangements &/or immunologic responses

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14
Q

What is the morphology seen in cardiomyopathy?

A
  • Enlarged & flabby heart with dilation of all chambers.
  • Wall thinning may accompany dilation.
  • Mural thrombi leads to thromboembolism
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15
Q

What is the microscopic features seen in cardiomyopathy?

A
  • Most myocytes are hypertrophied with enlarged nuclei but many are attenuated, stretched & irregular
  • Interstitial & endocardial fibrosis
  • Hemosiderin – Prussian blue staining
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16
Q

What is the clinical features seen in cardiomyopathy?

A
  • Any age – 20 to 50 years is commonest.
  • Presents with signs of slowly progressive CHF.
  • Ineffective contraction leads to in end-stage DCM cardiac ejection fraction is < 25%.
  • Secondary mitral regurgitation.
  • Cardiac arrhythmias.
  • Embolism from intracardiac thrombi.
  • 50% of patients die within 2 years & only 25% survive longer than 5 years.
17
Q

How is hypertrophic cardiomyopathy is characterized?

A
  1. Myocardial hypertrophy
  2. Abnormal diastolic filling
  3. Ventricular outflow obstruction (1/3rd cases)
18
Q

What is the pathogenesis seen in hypertrophic cardiomyopathy?

A

Caused by missense point mutations in the genes encoding sarcomeric proteins.

  • Autosomal dominant transmission.
  • > 400 mutations identified in nine sarcomeric genes.
  • β-myosin heavy chain is the most frequently affected, followed by myosin-binding protein C & troponin T.
  • ↑myofilament activation leads to myocyte hypercontractility (increase in energy use & net –ve energy balance).
19
Q

What are the morphological features seen in hypertrophic cardiomyopathy?

A
  • Massive myocardial hypertrophy without ventricular dilation
  • Asymmetrical septal hypertrophy but also concentric hypertrophy (10%)
  • Banana-like configuration of ventricular cavity
20
Q

What are the clinical features seen in hypertrophic cardiomyopathy

A

• Age of presentation – postpubertal growth spurt • Characterized by a massively hypertrophied left
ventricle & markedly reduced stroke volume
1. Impaired diastolic filling
2. Smaller chamber size
3. Left ventricular outflow tract obstruction

21
Q

What happens if there is a decrease in CO in hypertrophic cardiomyopathies?

A

• ↓C.O. & secondary ↑in pulmonary venous pressure leads to exertional dyspnea & systolic ejection murmur

22
Q

What happens if the LV pressure is increased in hypertrophic cardiomyopathies?

A

• A combination of massive hypertrophy , ↑LV pressure & compromised intramural coronary arteries leads to myocardial ischemia with angina even in the absences of CAD.

23
Q

What are the consequences seen in hypertrophic cardiomyopathy?

A
  • Atrial fibrillation with mural thrombus formation • Ventricular fibrillation
  • Infectious endocarditis of mitral valve
  • CHF
  • SCD
24
Q

What is restrictive cardiomyopathy?

A
  • Primary decrease in ventricular compliance, resulting in impaired ventricular filling during diastole (stiffer wall)
  • Systolic function of left ventricle is unaffected
25
Q

What is the etiology seen in restrictive cardiomyopathy?

A
  • Idiopathic

* Associated with systemic diseases – e.g., radiation fibrosis, amyloidosis, sarcoidosis

26
Q

What is the morphology seen in restrictive cardiomyopathy?

A
  • Almost normal size ventricles or slightly enlarged without dilation of cavities
  • Firm myocardium
  • Dilated both atria
  • Microscopically – interstitial fibrosis
  • Endomyocardial biopsy can reveal a specific etiologic disorders e.g., amyloid, iron overload, sarcoid granulomas.
27
Q

What is myocarditis?

A

Myocarditis encompasses a group of clinical entities in which infectious agents and inflammatory processes primarily target myocardium
• Inflammation– the cause, not the response

28
Q

What is the pathogenesis seen in myocarditis?

A

• Viral infections – most common cause
• Coxsackie viruses A & B & other enteroviruses
• CMV, HIV, influenza virus & others– less common
- Some viruses cause direct cell death
- In most cases the injury results from an immune response directed against virally infected cells

29
Q

What are the morphological features seen in myocarditis?

A
  • Acute myocarditis – normal or dilated heart
  • Ventricular myocardium is flabby & mottled
  • Mural thrombi
30
Q

What are the microscopical features seen in myocarditis?

A
  • Edema
  • Interstitial inflammatory infiltrate
  • Myocyte injury
31
Q

What are the clinical features seen in myocarditis?

A

Broad spectrum of clinical features
• Asymptomatic & recovery without sequelae
• Onset of heart failure or arrhythmias & even SCD
• signs & symptoms including fatigue, dyspnea, palpitations, pain & fever, sometimes acute MI like symptoms
• Occasionally progression to DCM

PATHOLOGY (5 decks)

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