SM 146a - Myocardial Pathology Flashcards by Madeleine (she/her) Horvath

LV hypertrophy is present in hypertrophic cardiomyopathy, but also in highly-trained athletes.

Describe the differences in histology

Hypertrophic cardiomyopathy
- Genetic cause
- Myofibers go in all directions
- Myocyte branching
- Asymmetric septal hypertrophy
Highly-Trained athletes
- Physiologic result of an adjustment to increased volume (due to increased venous return)
- Myocytes are organized; usually in the same direction to maximize efficiency of contraction
- Symmetric hypertrophy
- Reversible

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Describe the features of hypertrophic cardiomyopathy

Idiopathic hypertrophy
- Not caused by increased hemodynamic load
Hypertrophy involves the septum more commonly than the free wall
- Obstruction of outflow -> Subaortic stenosis
- Resistance to ventricular filling
Small LV chamber
- Not dilated
Wall thickening

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What are the most common causes of dilated cardiomyopathy?

(aka congestive cardiomyopathy)

Alcohol (1/3 of all DCM)
Pregnancy (peripartum)
Genetic influence
Recent viral infection

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What are the most common immune-mediated causes of pericarditis? (3)

Systemic Lupus Erythematous

Rheumatic Fever

Rheumatoid Arthritis

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In general, how are tumors of the heart treated?

What is the major side effect of these drugs?

Immune checkpoint inhibitors

Nivolumab
Ipilimumab

These drugs increase the patient’s risk of myocarditis; they attack the tumor and the normal heart tissue

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What are the most common viral causes of pericarditis? (2)

Coxsackie virus

ECHO (Enteric Cytopathic Human Orphan) Virus

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What do all cardiomyopathies have in common?

Intrinsic myocardial dysfunction

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What are the symptoms of hypertrophic cardiomyopathy?

Sudden cardiac death
Angina
Syncope
Systolic murmur

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Describe the most common causes of restrictive cardiomyopathy

Loeffler’s endocarditis
- Hypereosinophilia and fibrous thickening of the endocardium, usually with large thrombi against the ventricle walls (https://www.orpha.net/consor/cgi-bin/OC_Exp.php?Expert=75566&lng=EN)
Endomyocardial fibrosis
- In Sub-Saharan Africa
Primary endocardial fibroelastosis
- In children, usually due to ischemia/hypoxia in fetal development
Carcinoid syndrome
- Due to tumor
Infiltrative process -> myocardial restrictive cardiomyopathy
- Amyloidosis
- Fibrosis

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Which cardiomyopathy has provided a “model for the genetics of CV disease?”

Hypertrophic cardiomyopathy

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What is Loeffler’s Endocarditis?

Hypereosinophilia and fibrous thickening of the endocardium, usually with large thrombi against the ventricle walls

(https://www.orpha.net/consor/cgi-bin/OC_Exp.php?Expert=75566&lng=EN)

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What are the most common storage-disorder causes of secondary cardiomyopathy?

Glycogen storage
Hunter-hurler

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What are the most common parasitic causes of myocarditis?

T. Cruzi -> Chagas disease

Toxoplasmosis

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Describe the features of restrictive cardiomyopathy

Stiff left ventricle
- -> Inhibition of diastolic ventricular filling
- -> Left heart failure
Myocardial restrictive cardiomyopathy ->
- Thickening
- Inelasticity
- Sometimes dilation

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Describe the effects of isometric exercise on the heart

(Isometric exercise = weightlifting)

Isometric exercise -> Hypertrophy

Mass/volume ratio increases
Hypertrophy is the result of increased systemic pressure during exercise

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What is the most common cause of myocarditis?

Viral

(Coxsackie is the most common viral cause)

What is the most common cause of congestive heart failure in the world?

Chagas disease

(Caused by Trypanosoma Cruzi, carried by the Reduviid bug)

Which bacteria are most likely to cause myocarditis?

Corynebacterium diphtheriae
Mycobacterium tuberculosis
Treponema pallidum (Syphillis)
Leptospira (Leptospirosis)

What is the most common cause of hypertrophic cardiomyopathy?

Genetic

What causes primary endocardial fibroelastosis?

Ischemia/hypoxia in fetal development

Leads to restrictive cardiomyopathy

What are the most common causes of secondary cardiomyopathy?

Toxic/physical
- Alcohol, cobalt, anthracycline drugs
Metabolic
- Vitamin deficiency
- Hemochromatosis
- Hypo/hyperthyroid
Storage
- Glycogen
- Hunter-hurler
Infiltrative
- Sarcoidosis aka Granulomatosis
  - -> Heart block if in Bundle of His
- Amyloidosis
- Tumor
Neruomuscular
- Muscular Dystrophy
- Friedrich’s Ataxia
Inflammatory
Collagen Diseases
Immune-mediated (hypersensitivity)

[Note: there are individual cards for each sub-group]

What are the most common infiltrative causes of secondary cardiomyopathy?

Sarcoidosis aka Granulomatosis
- -> Heart block if in Bundle of His
Amyloidosis
Tumor

What are the most common viral causes of myocarditis? (4)

Coxsackie (most common)
ECHO (Enteric Cytopathic Human Orphan) Virus
Influenza
CMV (in immunosuppressed patients)

How can you distinguish between restrictive and constrictive cardiomyopathy?

Both have LV diastolic dysfunction

Restrictive
- Reduced compliance is caused by abnormal elastic properties of the myocardium and/or intercellular matrix
Constrictive
- Reduced chamber compliance is imposed by the external pericardial constraint

(http://www.onlinejacc.org/content/67/17/2061)

Describe the effects of isotonic exercise on the heart (Isotonic exercise = cardio)

Isotonic exercise -\> hypertrophy * Mass/volume ratio stays the same * Hypertrophy is the result of **adjusting to increased volume** due to increased venous return

What are the most common toxic/phsical causes of secondary cardiomyopathy?

* Alcohol (1/3 of all Dilated Cardiomyopathies) * Cobalt * Anthracycline drugs

Describe the physical features of dilated cardiomyopathy (aka congestive cardiomyopathy)

* 4-chamber dilation * Due to stretch beyond optimal preload * Normal wall thickness * Hypertrophy * Thrombi

How do bacterial infections cause myocarditis?

Often, the myocardium isn't directly infected by the bacteria. However, toxins/other factors secreted by bacteria can damage the myocardium Ex: *C. diptheriae* toxin

What are the most common metabolic causes of secondary cardiomyopathy?

* Vitamin deficiency * Hemochromatosis * Hypo/hyperthyroid

What are the most common bacterial causes of pericarditis?

Pyogeni bacteria Tubercle Bacili

What is a cardiac myxoma? What are the symptoms?

A tumor of the heart (rare) * May be in the LA (75%) or mitral valve * Impaired LV filling * Diastolic murmur that varies with position * Ball-like; mobile * Benign, surgically treatable

What is Dressler's Syndrome?

An immune system response after damage to heart tissue or to the pericardium, from events such as a heart attack, surgery or traumatic injury *(https://www.mayoclinic.org/diseases-conditions/dresslers-syndrome/symptoms-causes/syc-20371811)*

What is the definition of a secondary cardiomyopathy?

Cardiomyopathy has a recognized, extrinsic cause, or is part of a systemic process Ex: Toxicity, nutrient deficiency, congenital collagen disorder, etc.

What are the most common neuromuscular causes of secondary cardiomyopathy?

* Muscular Dystrophy * Friedrich's Ataxia

What is the definition of a primary cardiomyopathy?

* Disease process is intrinsic to the myocardium * Unknown or idiopathic cause * Not associated with generalized disease processes