Acute Coronary Syndromes Flashcards
What is the outcome of blood vessel narrowing
Inadequate oxygen delivery for tissue needs
Ischaemia in infected tissue
If persisting irritation and damage, specialised tissue becomes fibrotic
What is the outcome of blood vessel occlusion
No oxygen delivery causing more severe pain and tissue death and loss of function
What are the main arteries supplying blood to the heart and where do they come from
Right coronary artery
Left anterior descending artery
Circumflex coronary artery
Come from the root of aorta
At which HRs are cardiac problems most often found
Fast HRs because as HR increases, the time period for diastole reduces, compromising cardiac blood flow
When are coronary arteries tested
During exercise or at high HR
Where does atherosclerosis happen
At areas of stress to the artery and where there is turbulent blood flow
What happens in atherosclerosis
The change in blood flow causes damage to the interior surface of the artery and allows accumulation of fat within the surface which forms the atherosclerotic plaque
These gradually increase in size and narrow the vessel, reducing blood flow
Describe atherosclerosis as an acute coronary syndrome
Atherosclerosis attracts platelets to the vessel which will attract clotting factors and eventually cause occlusion of the vessel
What is spasm of the artery and how is it often termed
Muscle within vessel walls can contract causing narrowing of the artery often termed Prinzmetal’s angina
Describe the line between reversible and irreversible ischaemia
Reversible if less that 20 minutes occlusion, if occlusion takes longer than 20 minutes to clear, there will be permanent cardiac muscle damage
What are the different acute coronary syndromes
Stable angina
Unstable angina
STEMI
NSTEMI
Describe stable angina
Atherosclerosis restricts blood flow
If oxygen requirements beyond the plaque is higher than the tissue can deliver, the patient can have anaerobic metabolism and eventually lactic acidosis in the tissue, causing angina pain
When can stable angina be reversed
Reversible if oxygen requirements are reduced - can be done by stopping the exercise or increasing blood flow through the area
Describe the ECG of stable angina
Normal ECG
Describe the troponin levels for stable angina
Troponin stable as there is little cardiac death
Describe unstable angina
Patient can develop pain at any time because build up of plaque remains stable but clot on surface doesn’t extend to occlude the lumen
The clot will gradually be removed by the body and the lumen will open again
Isn’t associated with exercise so can be very difficult to differentiate from MI
Describe the ECG of unstable angina
Depression of the ST segments and inversion of the T waves
Describe the troponin levels for unstable angina
Stable as there is little cardiac death
Describe a STEMI
Often transmural changes - thickness of cardiac muscle wall changes
Atherosclerosis has developed a clot which has increased to occlude the vessel completely so no blood or oxygen can pass to the tissues
Describe an NSTEMI
No ST elevation, may be depression
Associated with a sub-endo cardiac infarct - interior layer of care disc muscle is infected
What cardiac biomarkers exist
Myoglobin
CK-MB
Troponin
Rank the cardiac biomarkers in effectiveness
Myoglobin is less effective
CK-MB used to be the preferred test but troponin is much more specific and easier to access
When should troponin be tested and why
Patient needs test done when they arrive at the hospital and 24 hours later
If raised troponin at time of admission, it is clear the patient has an MI
Troponin will have a peak between 24-48 hours
