Histo: Vascular and Cardiac Pathology Pt.1 Flashcards
What is atherosclerosis?
A disease characterised by atheromatous deposits and fibrosis of the inner layer (tunica intima) of arteries
List some risk factors for atherosclerosis.
- Age
- Sex
- Genetics (familial hypercholesterolaemia)
- Hyperlipidaemia
- Hypertension
- Smoking
- Diabetes mellitus
- Obesity
RFs have multiplicative effect
Outline the pathogenesis of atherosclerosis.
- Endothelial injury causes accumulation of LDL
- LDL enters intima and is trapped in sub-intimal space
- LDL is converted into modified and oxidised LDL causing inflammation
- Macrophages take up ox/modLDL via scavenger receptors and become foam cells
- Apoptosis of foam cells causes inflammation and cholesterol core of plaque
- Increase in adhesion molecules on endothelium due to inflammation results in more macrophages and T cells entering the plaque
- Vascular smooth muscle cells form the fibrous cap, segregating the thrombogenic core from the lumen
What is a fatty streak?
- Earliest change in atherosclerosis
- Lipid-filled foamy macrophages deposit in the intima
- No flow disturbance
NOTE: presence in pretty much everyone > 10 years old
What makes up an atherosclerotic plaque?
3 components:
- Cells - SMC, macrophages, other leukocytes
- ECM including collagen
- Intracellular and extracellular lipid
> > Causes local flow disturbance
What is critical stenosis?
- Point at which oxygen demand is greater than supply
- Occurs at around 70% occlusion
- Causes stable angina
List three types of acute plaque change.
- Rupture - exposes prothrombogenic plaque contents
- Erosion - exposes prothrombogenic subendothelial basement membrane
- Haemorrhage into plaque - increases size
In which patients does acute plaque change tend to happen?
Patients with mild-to-moderate atheroma (large plaques tend to be very stable)
List some features of vulnerable plaques.
- Large lipid core
- Thin fibrous cap
What is the leading cause of death worldwide for both sexes?
Ischaemic heart disease
List the possible presentations of ischaemic heart disease.
- Angina pectoris
- MI
- Chronic ischaemic heart disease with heart failure
- Sudden cardiac death
What degree of stenosis is required for:
- Chest pain precipitated by exercise
- Chest pain at rest
- 75% stenosis
- 90% stenosis
Where are the most clinically significant sites for atheromatous plaques within the coronary circulation?
- First few centimetres of the LAD and left circumflex
- Entire length of right coronary artery
What is angina pectoris?
- Transient ischaemia that does not produce myocyte necrosis
- Types: stable, unstable, prinzmetal (due to artery spasm)
What are the characteristics of stable angina?
- Precipated by exertion
- Relieved by rest
- No plaque disruption
