Flashcards in CVS - chest pain and ischaemic heart disease Deck (41)
What are potential causes of chest pain?
1. Musculoskeletal pain (ribs and muscles)
3. MI or angina
4. Cholecystitis (gallbladder inflammation)
Describe the differences in pain between MI, pericarditis and aortic dissection:
All central pain.
1. Ischaemia - tightening pain
2. Pericarditis - sharp pain
3. Dissection - tearing pain
What is the imbalance that leads to ischaemic heart disease?
An imbalance of myocardial oxygen supply and myocardial oxygen demand.
What is the direction of coronary blood flow?
Epicardium -> endocardium
Which muscle of the heart is most vulnerable to ischaemia?
Sub endocardial muscle
What is the most common cause of IHD?
Fixed narrowing of coronary arteries due to atherosclerosis.
Where are collateral arteries found in the heart?
There are none between major arteries (they are functional end arteries) but some are found between smaller arteries and arterioles.
What two main factors determine myocardial oxygen supply?
1. Coronary blood flow
2. Oxygen carrying capacity of blood
What two factors determine coronary blood flow?
1. Perfusion pressure (diastolic BP)
2. Coronary artery resistance
What are the three factors that myocardial oxygen demand depend on?
1. Heart rate
2. Wall tension
What determines the wall tension of the heart?
Preload and afterload
List some non-modifiable risk factors for coronary artery disease:
1. Increasing age
2. Male gender (females catch-up after menopause)
3. Family history
List some modifiable risk factors for coronary artery disease:
3. Hypertension (high diastolic or systolic)
4. Diabetes (doubles IHD risk)
5. Lack of exercise
Describe a stable atheromatous plaque:
It has a small necrotic core, thick fibrous cap and so is less likely to rupture.
Describe an vulnerable/unstable atheromatous plaque:
It has a large necrotic core, thin fibrous cap and therefore the cap is less likely to rupture.
Name three acute coronary syndromes:
Unstable angina, NSTEMI and STEMI.
What are typical features of chest pain?
1. Central (sometimes on left or right side)
2. Tightening/ constricting
3. Characteristic pattern of radiation.
What coronary pathology can stable plaques cause?
What coronary pathology can ruptured plaques cause?
Acute coronary syndromes: unstable angina, NSTEMI and STEMI.
What is the difference between stable angina and acute coronary syndromes?
Stable angina has no pain at rest but is precipitated by stress or exertion - which is relived within 5 minutes by nitrates or rest. ACSs have pain at rest or minimal exertion which is not relieved by nitrates and is of longer duration.
How does a plaque form a thrombus?
1. Fibrous cap undergoes rupture or fissuring
2. Exposes blood to the thrombogenic material in the necrotic core
3. Platelet 'clot' followed by fibrin thrombus.
How does sub-endocardial ischaemia present itself on the ECG?
ST segment depression of >1mm.
Why is aspirin given for IHD?
It reduces platelet aggregation and therefore reduces thrombus formation.
Why are statins given for IHD?
Decrease LDL cholesterl and therefore slow the progression of atherosclerosis and increase the plaque stability.
Why are long-lasting (transdermal or oral) nitrates given for IHD?
They cause venodilation and therefore reduce preload (decrease wall tension) and therefore myocardial oxygen demand.
Why are calcium channel blockers given for IHD?
They cause peripheral vasodilatation and therefore reduce afterload and therefore myocardial oxygen demand.
Why are beta-blockers given for IHD?
They reduce heart rate and contractility and therefore myocardial oxygen demand.
List two revascularisation techniques:
1. PCI: percutaneous coronary intervention (angioplasty and stenting)
2. CABG: coronary artery bypass grafting.
How is it determined which revascularisation technique is best for a patient?
They undergo coronary angiography which identifies the sites of occlusion. The choice of procedure is influenced by these findings.