4- pathology of non-ischaemic myocardial disease

Question 1

what is cardiomyopathy?

Answer 1

disease of cardiac muscle
= can result in changes in size & thickness of heart

Question 2

what are the 5 types of cardiomyopathy?

Answer 2

1. dilated
2. hypertrophic
3. restrictive
4. arrhythmogenic right ventricular dysplasia
5. amyloidosis

Question 3

what is dilated cardiomyopathy?

Answer 3

when the heart is massive (2 or 3 times normal size, 1000g over usual 450g)
- the heart is floppy & flabby

Question 4

what are causes of dilated cardiomyopathy?

Answer 4

• 50% cause is genes = inherited disease, usually affect desmin, dystrophin which are genes for muscle dystrophy (more info from geneticists)
• alcoholism (not sure if it’s due to toxins or nutritional deficiency that are associated)
• doxorubicin (old fashion chemotherapy agent)
• also cardiac infection like myocarditis (discussed below)
• childbirth, late in pregnancy or post-partum (unusual cause of maternal death)

Question 5

what is the histology of dilated cardiomyopathy?

Answer 5

non-specific features (just bigger cells so not obvious down microscope)

Question 6

what is hypertrophic cardiomyopathy?

Answer 6

massive LV muscle which means not much space for blood to fill
- big muscle so strong systolic contractions
- it’s diastolic dysfunction, problem with filling of heart which means can obstruct some blood from coming through

(cause of sudden death)

Question 7

what are the causes of hypertrophic cardiomyopathy?

Answer 7

genetic - myosin & tropomyosin

Question 8

what is restrictive cardiomyopathy?

Answer 8

= lack of compliance (stiff - no give)
- diastolic dysfunction as the stiffness means doesn’t fill well

(can look normal but can also have 2 big atria because no give in ventricles)

Question 9

what are the causes of restrictive cardiomyopathy?

Answer 9

usually deposition of something:
- metabolic products e.g. iron
- amyloid
- sarcoid - multi system granulomatous disorder
- tumours (rare)
- radiation fibrosis

Question 10

what is arrhythmogenic right ventricular dysplasia?

Answer 10

• autosomal dominant (inherited - low penetrance, means if you express the gene you will have it but could not have gene)
• can have syncope & funny turns
• diagnosis can be difficult = lots of non-specific features
• the ventricle is mostly replaced by fat, this can be tricky because RA often looks quite fatty

Question 11

what is myocarditis?

Answer 11

inflammation of the heart

• usually infectious (viral, bacterial, fungal, protozoal, helminthic)
• also can be non infectious, usually hypersensitivity immune reaction (maybe in response to infection like poststreptococcal and rheumatic fever) - example = systemic lupus erythematosus = hypersensitivity reaction that can be associated with myocarditis (but not commonly)

Question 12

what are the most common viral infections that cause myocarditis?

Answer 12

= remember coxsackie A & B and ECHO virus

also lots of weird ones like chagas disease (trypanosomiasis in south america but not here), lymes disease caused by bug (borrelia burgdorferi) from tick bites and this can cause myocarditis and sometimes cause AV block and sudden death

Question 13

what are the defining features of myocarditis on microscope?

Answer 13

defining feature = aschoff bodies

aschoff body = rheumatic granuloma (big macrophages surrounding these dead & dying areas of collagen)

Question 14

what is amyloid?

Answer 14

• abnormal deposition of any protein
• lots of proteins in body so lots of different types of amyloids
• they tend to form beta pleated sheet
• hard to get rid of so builds up and impairs function

Question 15

what are some forms of amyloid?

Answer 15

AA amyloid = related to chronic diseases like rheumatoid arthritis, lupus (part of immune response leads to abnormally folded proteins)

AL = abnormal immunoglobulin - in setting of hematological neoplasia and cancers

(L for light chains)

rarer forms = haemodialysis associated (beta 2 microglobulin deposition), also forms in diabetes and alzheimer’s

• amyloid can affect heart, sometimes it can be isolated to the heart (there can be senile cardiac amyloidosis)

Question 16

what does amyloid look like under microscope?

Answer 16

amyloid = looks like waxy pink material

= stains positively stain called “congo red”

= exhibits apple green birefringence (looks apple green colour under polarized light)

Question 17

what is pericarditis?

Answer 17

inflammation

• common infection = ECHO virus, can occur from infection elsewhere
• it’s serous fluid but if suppurative (pussy) then suggests bacterial (think about tuberculous)

can see it post MI = dressler’s syndrome (extension of infection from myocardium to pericardium)

Question 18

what are causes of pericarditis?

Answer 18

infection, immune mediated and some rare stuff like uraemia, connective diseases like rheumatoid & lupus are associated with serosal surfaces and also can occur as result of exposure of antigens to heart that weren’t exposed to before MI - see like 6 weeks later

Question 19

what is endocarditis?

Answer 19

= inflammation again (commonly on rheumatic valves)

• usually talking about bacterial infection on valves (strep viridans most common)

normally: there are colonies of bugs on valves called vegetation and these are loose, friable things and if high blood flow can ping off and cause emboli

Question 20

what are causes of endocarditis?

Answer 20

• bacterial infection on valves
• HACEK = haemophilus, actinobacillus, Cardiobacteria, Eikenella, kingella
• IV drug users can have Staph Aureus more common
• Prosthetic valves - S epidermidis
• lupus e.g. libman sacks

*can also get non-bacterial thrombotic endocarditis which is non invasive (doesn’t destroy valves)

Question 21

what are clinical features of endocarditis?

Answer 21

• osler nodes = painful red or purple nodules that develop on pads of fingers & toes
• janeway lesions = non-tender, small, erythematous or hemorrhagic macules or papules on palms or soles
• roth spots = retinal hemorrhages with pale or white center
• splinter hemorrhages = small areas of bleeding under fingernails & toenails
• systemic emboli - brain, kidney, lungs

Question 22

what is carcinoid heart disease?

Answer 22

• carcinoid tumours - neoplasms of neuroendocrine cells (classification keeps changing so tricky)
• carcinoid syndrome - mets to the liver
  
  • 5HIAA hormone released (serotonin, bradykinin, histamine)
  • flushing of skin, nausea, vomiting, right sided cardiac valve disease
  • tricuspid & pulmonary insuffiency

Question 23

what are tumours of
a) myocardium
b) blood vessels

Answer 23

a) rhabdomyomas
b) angiomas, angiosarcomas

Question 24

what is myxoma?

Answer 24

most common tumour (still rare)
- 90% in atria (usually rare)
- can cause ball valve obstruction & myxoid emboli - obstruction of flow and can lead to emboli

Question 25

what is carneys syndrome?

Answer 25

• get multiple myxoma’s in skin
• pigmented skin lesions
• neurofibromas
• pancreatic & thyroid tumours