acute myocardial infarction Flashcards
pathophysiology
usually due to thrombotic occlusion of coronary vessel caused by rupture of plaque - ischaemia
or ischaemia caused by increased oxygen demand eg HTN or decreased supply eg coronary artery spasm, embolism, arrythmia, hypotension
epidemiology
- 46% in men
0. 87% in women
clinical presentation: signs
dizziness nausea sob sweating no sign at all! chest pain
clinical presentation: symptoms
chest pain - radiates to left arm sob sweating nausea vomiting fatigue
characteristic ECG changes for MI
complete coronary occlusion : ST elevation -> Q waves (at 3days)
partial coronary occlusion : ST depression, T wave inversion, may be normal -> No Q waves (at 3days)
other diagnostic aids for MI
blood tests - check troponin, immediate point of care test
check Hb, kidney function, cholesterol
classification
type 1 : spontaneous MI type 2 : MI secondary to ischaemia type 3 : post-mortem type 4a : percutaneous coronary intervention type 4b : stent thrombosis type 5 : bypass
type 1
spontaneous and the ‘typical’ MI
atherosclerosis originates from damage to endothelium and build-up of cholesterol
type 2
secondary to ischaemia
common event in hosp where patients with SCAD +/- previous coronary intervention are unwell and put additional stress on heart that’s not normally not present
sufficient imbalance between supply of blood and demand for blood then myocardium becomes ischaemic without plaque rupture event
type 3
post-mortem
type 4
related to percutaneous coronary intervention - ie caused by angioplasty procedure blocking side branch or damaging main coronary artery -> ischaemia
related to stent thrombosis
if patients stop anti-platelets early post-angioplasty or continue to smoke, stents can occlude (STEMI - if complete sudden thrombosis or NSTEMI if gradual re-stenosis over time)
type 5
related to bypass graft (CABG) operation
STEMI
non-STEMI
diagnosis
detection of cardiac cell death : +ve cardiac biomarkers
AND one of :
symptoms of ischaemia
new ECG changes
evidence of coronary problem on coronary angiogram or autopsy
evidence of new cardiac damage on another test
aetiology
main = coronary heart disease
coronary heart disease
major blood vessels that supply heart are occluded with fatty deposits of cholesterol, known as plaques
before a heart attack, 1 bursts, causing a blood clot to develop at site of rupture - may block supply of blood to heart -> ischaemia -> heart attack
treatment
GTN spray (glycerol trinitrate)
vasodilator
sub-lingual or as IV infusion
opiates (eg morphine)
- relieve anxiety
- venodilate - haemodynamic benefits ?
thrombolysis
very strong blood thinning med
given in back of ambulance
often prompt transfer to cardiac centre with cath lab
risks of thrombolysis
bleeding
contraindications = previous stroke, previous intracranial bleed
caution = recent surgery, on warfarin, severe HTN
reperfusion therapy
mechanical = cath lab with balloons and stents = primary pci
pharmacological = strong blood thinner
risk factors
male age known CV disease HTN high cholesterol diabetes smoking FH
other causes of chest pain
pulmonary = PE, pneumonia, pleurisy, pneumothorax
emotional = anxiety/depression
GI = ulcer disease, hiatal hernia, pancreatitis
MSK = costochondritis, arthritis, muscular spasm, bone tumour
coronary disease is ___ most common cause of ____ in scotland
2nd
death
