Pathology 3 - Myocardial Diseases Flashcards
What is meant by cardiomyopathies
A diverse group of disorders with a primary myocardial dysfunction
What are the secondary myocardial changes
ischemic, hypertensive. valvular defects
what can secondary myocardial changes lead to?
Extrinsic cardiomyopathy
primary pathology outside myocardium
What are the 3 types of cardiomyopathies
- Dilated Cardiomyopathy
- Hypertrophic Cardiomyopathy
- Restrictive Cardiomyopathy
What is dilated cardiomyopathy
Extensive dilation of the 4 chambers
Most common (90% of cases)
What is hypertrophic cardiomyopathy
Hypertrophy of the ventricle
What is restrictive cardiomyopathy
The shape of the heart is more or less normal
There is interference with the relaxation the ventricles during diastole
What is seen in this gross specimen
Dilated Cardiomyopathy
Heart is doubled/tripled in size
What is seen in this gross specimen
Dilated cardiomyopathy with left ventricular mural thrombosis
How does dilated cardiomyopathy cause thrombosis
Dilation of the chambers cause slowing of blood flow
Stasis of blood can cause thrombus to form on the wall
what are the complications of mural thrombi ?
During contraction the thrombus can easily detach and travel to the systemic circulation and cause:
- Cerebral infarction
- Renal / Intestinal infarction
- severe impairment in the lower limbs (DVT) -> amputation
What is the etiology DCM
- Genetic (20-50 %)
- Myocarditis ( Coxsackie B , sometimes A)
- Peripartum CM
- Toxic CM (Alcoholic, Cocaine, Cytotoxic- drugs/chemotherapy, Cobalt-isotopic substances)
- Iron overload (hemochromatosis)
What is seen in the gross picture of DCM
- Dilation of all 4 chambers
- 2-3 times the normal size
- Systolic dysfunction (impaired contractility)
- Mural thrombi
- Functional Mitral or Tricuspid Regurgitation
- Aortic incompetence
How does DCM cause Functional Mitral or Tricuspid Regurgitation/Aortic incompetence
Severe dilation will cause pulling/ traction on the valve ring = open valve
so although the valves are structurally normal they are functionally impaired
What is the microscopic picture of DCM
Non-specific
- hypertrophied myocytes with enlarged nuclei, loss of striction
- some atrophied myocyte
- interstitial fibrosis
Compare the two images
Top: normal cardiac muscle fibers
Bottom: DCM - Hypertrophied myocytes with enlarged nuclei
what is seen in this image
Hypertrophic Cardiomyopathy
Particularly the left ventricle and septum causing asymmetric hypertrophy
What is the etiology of HCM
Almost exclusively genetic
Usually seen in younger patients due to genetic disorder
Pathophysiology of HCM
- Asymmetric myocardial hypertrophy (10% concentric)
- Greater thickening of septum than LV free wall
- Obstruction of blood flow (HOCM) 1/3 of cases
- Diastolic dysfunction and impaired compliance
What is the differential diagnosis of HCM
symmetric/concentric hypertrophy due to HTN/aortic stenosis
How does HCM cause diastolic dysfunction
extensive hypertrophy causes a rigidity in the muscle = interferes with relaxation during diastole
What is seen in this image
HCM: thickness of the septum > LV free wall
small number of patients can show symmetry
What is seen in this image
Concentric hypertensive hypertrophy (NOT HCM)
What is seen in the gross picture of HCM
- Ventricular hypertrophy (no dilation)
- Reduced LV cavity
- Altered configuration of ventricular cavity ‘banana-like’
What is seen in this image
Banana-shaped ventricle due to hypertrophic obstructive cardiomyopathy (HOCM)
What is myocardial disarray
seen in HCM
What is seen in this image
HCM: enlarged muscle fibers, myocardial disarray
What is the microscopic picture seen in HCM
- Severe myocyte hypertrophy
- Myofiber disarray
- Interstitial and replacement fibrosis
- Intramural coronary dysplasia
What is intramural coronary dysplasia
Medial thickening & Luminal narrowing seen in HCM
What is seen in this image
Green circle: Intramural coronary dysplasia
Yellow circle: Enlarged muscle fibers (whorled arrangement, myofiber disarray )
Black bracket: interstitial fibrosis
What are the 2 main causes of RCM
- Endomyocardial Fibrosis
- Infiltrative (eg. Amyloidosis, Sarcoidosis)
Pathophysiology of RCM
Diastolic dysfunction & Impaired compliance
Due to rigidity
What is seen in the gross picture of RCM
- Ventricles are normal/slightly enlarged
- Cavities not dilated
What is seen in the microscopic picture of RCM
- Endomyocardial fibrosis
- Amyloid, sarcoid granuloma, etc.
- Interstitial fibrosis
What is seen in this image
Loss of trabeculation - Endomyocardial fibrosis
RCM
What stain is used in this slide and what does it show
Masson’s stain (fibrous tissue stained blue)
Endomyocardial Fibrosis
What is Endomyocardial Fibrosis
Fibrosis under endocardium and inner layer of myocardium
What is seen in these pictures
Amyloidosis RCM
Left: amyloid is stained pink by H&E
Right: amyloid stained greenish by Sulphated Alcian Blue
What is seen in this image
Cardiac Sarcoidosis
Granuloma, giant cells and some inflammatory cells
What is myocarditis and what are the affects
Inflammation of myocardium
Generalized, regional, focal
What are the causes of myocarditis
- Direct involvement (infected valve may spread to adjacent myocardium)
- Hypersensitivity due to certain drugs
- Toxins
What is the prognosis of myocarditis
- Immediate effects can be serious (acute HF = sudden death)
- Recovery is common
What are the types of Myocarditis
- Viral
- Bacterial
- Toxic
- Immunological
- Giant Cell (GCM)
Describe the Causes of Viral Myocarditis
- Caused by Coxsackie B or A
sometimes influenza, HIV, COVID-19
Describe the Presentation of Viral Myocarditis
- Generalised interstitial inflammation
- Mainly lymphocytes, some macrophages
- Can be asymptomatic (subclinical)
- Can cause sudden death
What is seen in this image
viral myocarditis
- myocardial fibers with early necrotic changes
- many lymphocytes some macrophages
What is the pathophysiology of bacterial myocarditis
- Direct spread from infected valves/bloodstream
- Focal suppuration
- Necrosis, polymorphic infiltration, interstitial edema
What is seen in this image
Bacterial myocarditis
- Focus with necrosis tissue, bacterial colonies, polymorphs infiltration and between interstitial
What is seen in this image
bacterial myocarditis (slightly darker than normal tissue)
What causes Toxic Myocarditis
- Toxins of bacteria (Diphtheria - Typhoid - Pneumonia)
- Drugs or Chemicals
Describe the presentation of Toxic Myocarditis
- Generalized muscle damage with foci of necrosis
- Infiltrate with lymphocytes and macrophages
Describe Causes of Immunological Myocarditis
Rheumatic, SLE (Libman Sacks)
What is Giant Cell Myocarditis
Rare inflammatory disease o myocardium
- Affects previously healthy young adults
- Commonly fatal
- Etiology unknown
What is the presentation of GCM
- Yellow-grey or grey foci throughout myocardium
- Mural thrombi
What is seen in this image
GCM
- Multifocal necrosis
- Inflammatory infiltrate of lymphocytes and histiocytes
- Multinucleated giant cells
