Cardiac Pathology Flashcards
What is atherosclerosis?
A chronic inflammation of the intima in the large arteries, characterised by intimal thickening and lipid accumulation
Explain the pathogenesis of atherosclerosis
1) Endothelial injury
2) LDL enter the intima and is trapped
3) LDL is converted into oxidised LDL and causes inflammation
4) Macrophage recruitment to take up the oxidised LDL and convert into foam cells
5) Foam cells apoptose and become the cholesterol core of the plaque
6) Vascular smooth muscle becomes the fibrous cap of the plaque
Where is atherosclerosis more likely to occur?
Near the roots of branches, as there is turbulent flow here, which is more atherogenic.
What is the fate of atherosclerotic plaques?
Obstruction:
- They can stenose an artery
- > 70% stenosis to cause symptoms (angina etc.)
Acute Plaque Change:
- Rupture
- Erosion
- Internal haemorrhage
What are the risk factors for atherosclerosis?
Non-modifiable:
- Age
- Gender
- Familial history (genetics)
Modifiable:
- Type 2 Diabetes Mellitus
- Hypercholesterolaemia
- Hypertension
- Smoking
What coronary arteries are most commonly affected by atherosclerosis?
- Right coronary
- Left mainstem
- Left anterior descending
- Left circumflex
What types of angina are there? How do you differentiate them?
Stable
- On exertion
Unstable
- On rest
Prinzmetal
- Due to coronary artery spasm
What is ischaemic heart disease?
This is a collection of diseases caused by an imbalance of demand and supply of blood to the heart.
- Angina pectoris
- Chronic ischaemic heart disease
- Myocardial infarction
- Sudden cardiac death
What is a myocardial infarction?
Ischaemia of the cardiac muscle leads to necrosis and death. Irreversible damage occurs if this goes on for longer than 20-40 minutes.
What is the epidemiology surrounding myocardial infarction?
Half of all MI-related deaths occur before they reach the hospital
What are the complications of myocardial infarction?
Mechanical:
- Contractile dysfunction, leading to cardiogenic shock
- Congestive cardiac failure
- Cardiac rupture of free wall, septum or papillary muscle
- Ventricular aneurysm, increasing the likelihood of thrombi
Arrhythmias:
- VF can occur in the first 24 hours and commonly causes sudden cardiac death
- Electric instability is a common complication of MIs
Pericardial:
- Post-MI pericarditis (Dresser’s Syndrome): fever, chest pain and effusion
- Pericardial effusion +/- tamponade
- Fibrinous pericardium
Mural thrombus:
- Can occur in ventricular aneurysms
- Can dislodge and spread to brain or other tissues
What are the histological findings of myocardial infarction?
0 - 6 hours: no changes
6 - 24 hours: oedema, loss of nuclei, necrotic cell death
1 - 4 days: infiltration of macrophages
5 - 10 days: removal of debris
1 - 2 weeks: granulation tissue, new blood vessels
Weeks - months later: strengthening, scar tissue
When are cardiac muscle ruptures most likely to occur after a myocardial infarction?
Within the first 10 days; this is due to the weakened wall with macrophage infiltration. As scar tissue begins to develop, the scar tissue is far more fibrous and strong, and this occurs later.
What is reperfusion injury?
As the tissue may be necrotic, reperfusion quickly can cause inflammation, calcium overload and a ‘stunned’ myocardium
What is the definition of sudden cardiac death?
Cardiac death in a previously asymptomatic patient, or death within one hour of symptoms onset.
What is heart failure?
Insufficiency of the heart s a pump