Acute MI Flashcards
what happens to the lumen of an artery in atherosclerosis?
it becomes narrowed so less blood passes through to adequately supply the heart + other organs
what causes chronic stable angina?
fixed stenosis in a coronary artery
when does pain from stable angina come on?
only when demand is put on the heart i.e. during exercise
what should patients do when the pain from stable angina comes on?
sit down and use their GTN spray
how does GTN spray relieve chest pain in angina?
lowers BP
reduces afterload
can cause vasodilation
is stable angina an acute coronary syndrome?
no
where does cardiac chest pain radiate?
down the left arm and up the jaw
what is an acute coronary syndrome?
any acute presentation of coronary artery disease
STEMI, NSTEMI, unstable angina
what are the two types of MI?
non st elevation = NSTEMI
st elevation = STEMI
what is the pathogenic trigger for acute MI?
spontaneous plaque rupture causing thrombosis, resulting in occlusion of a vessel
what is the response to a plaque rupture by the circulating blood?
the blood starts to clot as it reacts like this is a vascular injury
platelets form a monolayer over the rupture and encourage the adhesion of more and more platelets
what do platelets release that activates more platelets and how?
ADP and other activators via degranulation
what do activated platelets express and what does this ultimately cause?
they express adhesion receptors for leukocytes
this allows WBC’s to bind and the coagulation cascade starts
what intracellular enzyme system helps activate more platelets during clotting and how?
cyclooxygenase
produces thromboxane A2, which activates platelets and promotes thrombosis
how does aspirin stop platelet aggregation?
it stops the cyclooxygenase system, halting production of thromboxane A2
name three ADP receptor antagonists
clopidogrel
prasugrel
ticagrelor
how do ADP receptor antagonists stop platelet aggregation?
they stop ADP binding to platelets and activating them
describe the chest pain associated with an MI
severe, crushing, central chest pain
radiates to the jaws and arms (especially the LA)
what can pain from MI often be associated with?
sweating
nausea and vomiting
what ECG changes can be seen in acute STEMI?
ST elevation
T wave inversion
pathological Q waves
how is ST elevation in a STEMI defined
> 1mm in two adjacent limb leads
>2mm in at least two contiguous precordial leads
what may be seen on ECG if a patient has had a previous MI?
Q waves
T wave inversion
ST elevation in which leads suggests an inferior MI?
II
III
AVF
ST elevation in which leads suggests an anterior MI?
V1-V6
what enzyme may be used as a marker for MI?
creatinine kinase (CK)
what protein marker is used in MI?
troponin
why is troponin a good marker for MI?
it is highly specific for cardiac muscle damage
what should be given IMMEDIATELY to patients with ECG changes/elevated troponin?
aspirin and ticagrelor
how should aspirin be taken in MI?
should be chewed to make it work faster
what does thrombolysis do?
breaks up a clot
what is the initial management of an MI?
morphine + anti-emetic oxygen if hypoxic nitrate (GTN) aspirin clopidogrel etc.
when is thrombolysis done in MI?
if primary angioplasty is not available in the first 120 mins
what is PCI?
percutaneous coronary intervention (angioplasty)
name an arrhythmic complication of MI
ventricular fibrillation
how is ventricular fibrillation treated?
defibrillation
what two types of troponin are cardiac specific?
T and I
