L9 - Coronary artery disease Flashcards
Coronary artery disease
Inadequate BS to myocardium
How might chest pain be relieved?
Relieved by rest and/or nitroglycerine
Role of ACE inhibitors
- reduction of angiotenin II (v.constrictor)
- increase of bradykinin (v.dilator)
Angiotensin II
Vasoconstrictive effects that increase oxidative stress.
Promote inflammation and thrombosis
Bradykinin
promotes vasodilation which counter acts the harmful effects of angiotensin II.
Action of nitrates on smooth muscle
- relax VSM
- reduce myocardial oxygen demand by inducing systemic vasodilation
Action of nitrates on arteries and vein
By dilating veins
- nitrates reduce the pressure of the blood returning to the heart (preload)
By dilating arteries
- nitrates reduce the pressure against which the heart has to pump (afterload)
BOTH decrease oxygen demand
Myocardial infarction
Irreversible death of heart muscle secondary to prolonged lack of oxygen supply.
State types of acute coronary syndrome (3)
- Unstable angina
- STEMI
- NSTEMI
Unstable angina
- Partial rupture of an artery
- Does not cause permanent damage to the heart
STEMI
- complete occlusion of BV lumen
- results in transmural injury and infarct to myocardium
- rise in troponin
How a NSTEMI occurs?
Where is the resulting injury?
- plaque ruptures
- thrombus formation
- causes partial occlusion to vessel
- results in injury and infarct to subendocardial myocardium
Troponin
Contractile protein that is not normally found in serum.
Only released when myocardial necrosis occurs.
Major features MI
- ECG
- diagnostic tests
- persistent ECG ST segment elevation
- presence of cardiac biomarkers
Describe how a reperfusion injury may occur?
- Restoration of BF to damaged myocardium triggers further ischaemic cellular damage
- interaction between oxygen free radicals and intracellular calcium, leading to acceleration of myocardial damage and death
