Histopathology - Cardiac Pathology Flashcards by Annie Rees

What is atherosclerosis?

Chronic inflammation in the tunica intima (innermost layer) of large arteries characterised by intimal thickening + lipid accumulation

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What are the steps of atherogenesis?

Endothelial injury causes accumulation of LDL
LDL enters intima + is trapped in sub-intimal space
LDL -> oxidised LDL, causes inflammation
Macrophages take up oxidised LDL via scavenger receptors + become foam cells
Apoptosis of foam cells causes inflammation + cholesterol core of plaque
Increase in adhesion molecules on endothelium (bc of inflammation) = more macrophages + T cells enter plaque
VSMC form fibrous cap, separating thrombogenic core from lumen

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What are the principal components of an atherosclerotic plaque?

Cells
ECM (inc. collagen)
Intracellular + Extracellular lipid

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What are some modifiable and non-modifiable RFs of Atherosclerosis?

Modifiable:
- T2DM
- HTN
- Hypercholesterolaemia
- Smoking

Non-modifiable:
- Gender (M>F)
- Increasing age
- FHx

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What is Ischaemic Heart Disease?

A group of conditions that occur when oxygen supply > demands of myocardium due to narrowed coronary vessels

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What are some features of stable angina?

~70% vessel occlusion
Pain on exertion

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What are some features of unstable angina?

~90% vessel occlusion
Pain at rest + on exertion
High likelihood of impending infarction

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What are some features of prinzmetal angina?

Rare
Due to coronary artery spasm (from cocaine use), not atherosclerosis

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Is there muscle death in angina?

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What is the pathogenesis of a myocardial infarction?

Sudden change in plaque
Platelet aggregation
Vasospasm
Coagulation
Thrombus evolves
» myocardial necrosis secondary to ischaemia

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What happens in severe ischaemia of a myocardial infarction?

Lasts >20-40 mins
Irreversible injury
Myocyte death

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What are some common atherosclerotic plaque sites?

First few cm of LAD, LCX
RCA

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What are some complications of a myocardial infarction?

DARTH VADER
- D: Death
- A: Arrhythmias
- R: Rupture
- T: Tamponade
- H: Heart Failure

V: Valve disease
A: Aneurysm
D: Dressler syndrome
E: Embolisation
R: Recurrence + regurgitation

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What are histological findings of an MI over time?

< 6hrs: NORMAL
6-24hrs: Loss of nuclei, homogenous cytoplasm, necrotic cell death
1-4d: Infiltration of polymorphs then macrophages
5-10d: Debris removal
1-2wks: Granulation tissue, new blood vessels, myofibroblasts, collagen synthesis
Wks-mnths: Strengthening, decellularising SCAR TISSUE

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What is heart failure?

Heart’s inability to pump sufficient blood to supply the demand of the body

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What is preload?

An initial stretch of cardiomyocytes before contraction due to ventricular filling (increasing will increase SV)

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What is afterload?

The pressure of vessels against which heart must contract to eject blood (increasing will decrease SV)

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What are some causes of heart failure?

IMHC
- Ischaemic heart disease
- Myocarditis
- HTN
- Cardiomyopathy (dilated)

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What are some complications of heart failure?

Sudden death
Systemic emboli
Arrhythmias

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What are histological complications of heart failure

Pulmonary oedema with superimposed infection
Hepatic cirrhosis (nutmeg liver)

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What is LV heart failure?

Pooling of blood within pulmonary circulation due to high pressures in left side of heart

Leads to decreased peripheral blood pressure and flow

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What are some symptoms of LV heart failure?

Dyspnoea
Orthopnoea
PND
Wheeze
Fatigue
Pulmonary oedema

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What is RV heart failure?

Minimal pulonary congestion but engorgement of systemic and portal venous systems

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What are some causes of RV heart failure?

Most common = secondary to LVF
Chronic severe pulmonary HTN

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What are some symptoms of RV heart failure?

- Peripheral oedema - Ascites - Facial engorgement - Nutmeg liver

What is nutmeg liver?

The congestion and stasis of venous blood in the liver

What is the general histology seen in cardiomyopathy?

- Dilated heart - Scarring + thinning of the walls - Fibrosis + replacement of ventricular myocardium

What is dilated cardiomyopathy?

The loss of myocytes

What is hypertrophic cardiomyopathy?

A defect in β-myosin heavy chains A/w sudden death

What is restrictive cardiomyopathy?

Impaired compliance

What is the mechanism of HF in dilated cardiomyopathy + some causes?

Systolic dysfunction - Idiopathic - Alcohol - Thyroid disease - Myocarditis

What is the mechanism of HF in hypertrophic cardiomyopathy + some causes?

Diastolic dysfunction - Genetic - Storage diseases

What is the mechanism of HF in restrictive HF + some causes?

Diastolic dysfunction - Sarcoidosis - Amyloidosis

What is the mode of inheritance of hypertrophic cardiomyopathy?

Autosomal dominant

What is seen on histology of hypertrophic cardiomyopathy?

Myocyte disarray (arrhythmogenic)

What is hypertrophic obstructive cardiomyopathy?

Septal hypertrophy resulting in an outflow tract obstruction

What is arrhythmogenic right ventricular cardiomyopathy?

Myocyte loss with fibrofatty replacement typically affecting the right ventricle

What systems does rheumatic fever affect?

- Heart: pancarditis - Joints: arthritis + synovitis - Skin: erythema marginatum + subcutaneous nodules - CNS: encephalopathy + Sydenham's chorea

When does rheumatic fever present?

- Develops 2-4wks post-strep throat infection Peak age of onset = 5-15 years

What is the diagnostic criteria for rheumatic fever?

Group A strep infection + 2 major criteria, or 1 major + 2 minor criteria - Jones' criteria Major (CASES): - C: Carditis - A: Arthritis - S: Sydenham's chora - E: Erythema marginatum - S: Subcutaneous nodules Minor criteria: - Fever - Raised ESR/CRP - Migratory arthralgia - Prolonged PR interval - Prev. Rh Fever - Malaise - Tachycardia

Which valves are affected in rheumatic fever?

- 70% mitral valve only - 25% affects mitral + aortic valves

What is the main pathogen causing rheumatic fever?

Lancefield group A strep

What is seen on histology of rheumatic fever?

- Beady, fibrous vegetations - Aschoff bodies - Anitschkov myocytes

What is the treatment for rheumatic fever?

Benzylpenicillin (erythromycin if allergic)

What is infective endocarditis?

The colonisation of the endothelium

What can cause bacteraemia in infective endocarditis?

- Poor dental hygiene - IVDU - Soft tissue infection - Dental treatments - Cannulae/lines - Cardiac surgery/pacemakers

What are the acute causative organisms in infective endocarditis and where do they spread?

- Staphylococcus. aureus - Strep. pyogenes - Aorta

What are the subacute causative organisms in infective endocarditis and where do they spread?

Strep. viridians - Staphylococcus epidermidis - HACEK - Coxiella - Mycoplasma - Candida - Chordae

What are the HACEK bacteria causing endocarditis?

Unusual bacteria - H: Haemophilus - A: Aggregatibacter - C: Cardiobactam - E: Eikenella - K: Kingella

What is antigenic mimicry?

Cell-mediated immunity and antibodies. to streptococcal antigen cross-react with myocardial antigens

What is the pathology of rheumatic heart disease + some characteristics of its vegetations?

- Antigenic mimicry - Verrucae (small, warty vegetations on closure line of valve leaflet)

What is the pathology of infective endocarditis + some characteristics of its vegetations?

- Colonisation or invasion of heart valves or mural endocardium by microbe - Large, irregular masses on valve cusps, extends into chordae

What is the pathology of non-bacterial thrombotic endocarditis (Marantic) + some characteristics of its vegetations?

- DIC/hypercoagulable state - Small, bland vegetations on closure lines - formed of thrombi

What is the pathology of Libman-Sacks endocarditis + some characteristics of its vegetations?

- Unknown (a/w SLE + APLS) - <2mm warty vegetations, sterile + platelet rich

What are some clinical features of infective endocarditis?

- Constitutional = fever, malaise, rigors, anaemia - Cardiac = new murmur (MR/AR) - Immune phenomena = ROTH SPOTS, Osler's nodes, HAEMATURIA (secondary to glomerulonephritis) - Thromboembolic phenomena = janeway lesions, septic abscesses, microemboli, SPLINTER HAEMORRHAGES, SPLENOMEGALY

Which valves are usually involved in infective endocarditis?

Mitral/aortic valve UNLESS IVDU when right-sided valves are involved

What criteria is used to diagnose infective endocarditis?

Duke criteria Require for diagnosis: - 2 major - 1 major + 3 minor - 5 minor

What is the Duke criteria?

Major: - +ve blood culture growing typical IE organisms or 2 +ve cultures >12hrs apart - Evidence of vegetation/abscess on echo/new regurge murmur Minor: - RF - Fever >38C - Thromboembolic phenomena - Immune phenomena - +ve blood cultures not meeting major criteria

What is the treatment for infective endocarditis?

- Broad spectrum Abx once cultures taken - Subacute: benzylpenicllin + gentamicin / vancomycin Acute: flucloxacillin (MSSA) / rifampicin + vancomycin + gentamicin (MRSA)

What is the pathophysiology and some causes of aortic stenosis?

- Narrowed aortic valve, high velocity, high pressure - Calcification (old age), congenital bicuspid valve

What is the pathophysiology + some causes of aortic regurgitation?

- Incompetent aortic valve blood flows back into LV after systole - Infective endocarditis, diessecting aortic aneurysm, LV dilation, connective tissue disease

What is the pathophysiology + some causes of mitral stenosis?

- Narrowed mitral valve high velocity, high pressure flow - Back pressure in left atrium dilatation - Rheumatic fever

What is the pathophysiology + some causes of mitral regurgitation?

- Incompetent mitral valve blood flows back into left atrium during systole - Infective endocarditis, connective tissue disease, post-MI, rheumatic fever, left ventricular dilation

What is chronic rheumatic valve disease?

Thickening of the valve leaflet, especially along closure/fusion lines. Thickening, shortening + fusino of chordae tendinae - Predominantly left-sided - Mitral > Aortic > Tricuspid > Pulmonic

What is the clinical presentation of mitral valve prolapse?

- Middle aged woman - SOB + chest pains - Mid-systolic click + late systolic murmur

What is pericarditis?

Inflammation of the pericardium

What are the types + some causes of pericarditis?

- Fibrinous (MI, uraemia) - Purulent (staphylococcus) - Granulomatous (TB) - Haemorrhagic (tumour, TB, uraemia) - Fibrous/constrictive (any of the above)

What is a pericardial effusion and it's usual cause?

Serous fluid in the pericardial sac - Exudative fluids occur secondary to infection/inflammation/malignancy/autoimmune processes in pericardium - Chronic heart failure

What is a haemopericardium?

Myocardial rupture from myocardial infarction or trauma

Histopathology - Cardiac Pathology Flashcards

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