Acute MI Flashcards
How do platelets initiate the build up of atheromatous plaques?
They form a monolayer and initiate a cascade which causes platelet clumping to attract other platelets
What do platelets release when they are activated?
ADP and thromboxane A2 through the cyclooxygenase system
What is produced at the end of the clotting process?
A thrombus
What is the first effect of the build-up of plaque?
Stable angina- a fixed stenosis which results in a demand led ischaemia that is usually predictable and safe
Does pain from angina radiate?
Yes often down the left arm as well as other sites
What is the second effect of the build-up of plaque?
Acute coronary syndrome- a dynamic stenosis with a supply led ischaemia which is unpredictable and dangerous
What are important factors in determining the cause of a plaque rupture?
Thickness of the fibrous cap ad lipid content of plaque
Are old or new plaques more likely to rupture?
New
What other factors can increase the risk of a plaque rupture?
Bending of an artery or sudden change in intra-luminal pressure
What occurs when a coronary artery is completely occluded?
STEMI
What will a STEMI ultimately lead to?
Heart failure
What are some symptoms of heart failure?
Breathless, cough, PND, orthopnoea,
What is typical STEMI pain?
Central crushing chest pain radiating to arm and jaw, similar to angina but worse and not relieved by GTN
What are some associated symptoms of a STTEMI?
Sweating, nausea and vomiting
What are non-cardiac differentials of STEMI?
Pneumothorax (sudden), pleuritic pain of pneumonia, MSK pain or heartburn
What is the first ECG change to occur in a STEMI?
ST elevation
What ECG changes may show a bit later on a STEMI?
T wave inversion or Q waves
What are Q waves?
Downward deflections between the p wave and QRS
What are the rules with regards to ST elevation?
ST elevation must be 1cm or greater in 2 adjacent limb leads or 2cm or greater in 2 contiguous precordial leads (or new onset LBBB)
What leads and artery are involved in an inferior MI?
II, III, aVF
Right coronary artery
What leads and artery are involved in an anteroseptal MI?
V1-4
Left anterior descending artery
What leads and artery are involved in an anterolateral MI?
I, aVL, V4-6
Left anterior descending or left circumflex