142: Myocardial Pathology Flashcards
Describe arrhythmogenic cardiomyopathy
- Genetic
- Myocardium is replaced by fibrosis and adipocytes
- Fibrosis starts at epicardian surface and works in
- Dilated RV, can also effect LV
- Causes arrythmias and sudden death in young, healthy people
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)
- Recent viral infection
- Idiopathic dilated cardiomyopathy (very bad, low recovery rates, possibly genetic)
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 have cardiac toxic effects. Kill the cancer cells, but damage heart muscle.
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
Interfere with diastolic function (impaired ventricular filling)
-
Endomyocardial fibroelastosis
- Genetic disease causing thickening of wall
- Amyloidosis
Which cardiomyopathy has provided a “model for the genetics of CV disease?”
Hypertrophic cardiomyopathy
Many families have defects in genes encoding the contracticle machinery
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 -> CONCENTRIC 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?
Chaga’s disease
(Caused by Trypanosoma Cruzi parasite)
Which bacteria are most likely to cause myocarditis?
Overall, bacterial infections are a RARE cause of myocarditis.
- Corynebacterium diphtheriae
- Mycobacterium tuberculosis
- Treponema pallidum (Syphillis)
- Leptospira (Leptospirosis)
What is the most common cause of hypertrophic cardiomyopathy?
Genetic
What are the most common causes of secondary cardiomyopathy/specic heart muscle disease?
(only including diseaes discussed in detail)
-
Sarcoidosis: systemic granulomatous disease that can effect myocardium
- -> Heart block if in Bundle of His
- Amyloidosis: biventricular hypetrophy, small chambers, wax-like, shiny. Appears apple green using Congo Red Stain
Both are inflitrative
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 -> eccentric 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/physical causes of secondary cardiomyopathy?
- Alcohol (1/3 of all Dilated Cardiomyopathies)
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 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 the definition of a secondary cardiomyopathy?
Cardiomyopathy has a recognized, extrinsic cause (drug toxicity), or is part of a systemic process (amyloidosis)
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
