Pathology 3 - Myocardial Diseases Flashcards
(55 cards)
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’
