Ischaemic Heart Disease Flashcards
(49 cards)
What is the definition of ischaemic heart disease?
pathophysiological syndromes due to inadequate blood supply to the myocardium
What are the 2 reasons why there may be inadequate blood supply to the myocardium in IHD?
- reduced coronary blood flow due to atheroma +/- thrombus
2. myocardial hypertrophy due to systemic hypertension
What are the 5 factors involved in preventing IHD?
- stop smoking
- lose/manage weight
- lower blood pressure
- encourage exercise
- calculate risk and prescribe relevant treatment
What is the main risk score calculation used in IHD?
The Framingham risk score calculation
It estimates a patient’s 10 year risk of having a heart attack
What are 2 other commonly used risk calculators?
- SCORE
2. QRISK3
What is involved in the pathogenesis of IHD?
- acute and/or chronic ischaemia
- loss of autoregulation of coronary blood flow with >75% vessel occlusion
- low diastolic flow leading to subendocardial hypoperfusion
- myocyte dysfunction/death from ischaemia
When is recovery possible from IHD?
If there is rapid reperfusion within 15-20 minutes
At what point does IHD become symptomatic?
When there is >75% vessel occlusion
This is critical stenosis and gives angina-like symptoms
What are the 4 IHD syndromes?
- angina pectoris
- acute coronary syndrome
- sudden cardiac death
- chronic ischaemic heart disease
What typically causes acute ischaemia?
- atheroma + acute thrombosis/haemorrhange
Lipid rich plaques are most at risk
What does acute ischaemia in the heart lead to?
regional transmural myocardial infarction
this is different to a subendocardial MI
If someone has an MI and dies within 24 hours, what morphology would be present?
Morphology would be normal
e.g. in a sudden cardiac death
What would the MI morphology look like after 1-2 days?
it would be pale and oedematous
there would be neutrophils and myocyte necrosis
What would the MI morphology look like after 3-4 days?
it would be yellow with a haemorrhagic edge
there would be macrophages and myocyte necrosis
What would the MI morphology look like after 1-3 weeks?
it would be red-grey to grey-white
it becomes pale and thin
granulation tissue forms, followed by fibrosis
What would the MI morphology look like after 3-6 weeks?
there would be a dense fibrous scar
What is a ‘STEMI’?
ST-elevation myocardial infarction
What causes a STEMI?
blockage of one of the major coronary arteries
this is the most serious type of heart attack caused by COMPLETE OCCLUSION of a coronary artery
What is an example of an NSTEMI?
subendocardial MI
What is an NSTEMI?
non-ST-elevation myocardial infarction
an acute ischaemic event causing myocyte necrosis
What is the perfusion of the subendocardial myocardium like under normal conditions?
it is relatively poorly perfused under normal conditions
What can lead to the subendocardial myocardium infarcting without any acute coronary occlusion?
- stable atheromatous occlusion of the coronary circulation
- an acute hypotensive episode
this can lead to subendocardial MI
What is the most common blood marker of cardiac myocyte damage?
Troponins T and I
Under what circumstances may troponins T and I be raised?
- post-MI
- pulmonary embolism
- heart failure
- myocarditis