SM 146a - Myocardial Pathology Flashcards
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
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
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
What are the most common immune-mediated causes of pericarditis? (3)
Systemic Lupus Erythematous
Rheumatic Fever
Rheumatoid Arthritis
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
What are the most common viral causes of pericarditis? (2)
Coxsackie virus
ECHO (Enteric Cytopathic Human Orphan) Virus
What do all cardiomyopathies have in common?
Intrinsic myocardial dysfunction
What are the symptoms of hypertrophic cardiomyopathy?
- Sudden cardiac death
- Angina
- Syncope
- Systolic murmur
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
Which cardiomyopathy has provided a “model for the genetics of CV disease?”
Hypertrophic cardiomyopathy
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)
What are the most common storage-disorder causes of secondary cardiomyopathy?
- Glycogen storage
- Hunter-hurler
What are the most common parasitic causes of myocarditis?
T. Cruzi -> Chagas disease
Toxoplasmosis
Describe the features of restrictive cardiomyopathy
- Stiff left ventricle
- -> Inhibition of diastolic ventricular filling
- -> Left heart failure
- Myocardial restrictive cardiomyopathy ->
- Thickening
- Inelasticity
- Sometimes dilation
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
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
- Sarcoidosis aka Granulomatosis
-
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
