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
What leads and artery are involved in an lateral MI?
I, aVL +/- V5-6
Left circumflex artery
What does a posterior MI show and what artery is involved?
Tall r waves in V1-2
Left circumflex or right coronary artery
What are further diagnostic tools used for STEMI?
Cardiac enzymes (troponin) and protein markers
What is the downside of cardiac enzymes and protein markers?
Might take too long to wait for results
What anti-platelet drugs are used for STEMI and how do they work?
Aspirin- switches off cyclooxygenase system to block thromboxane A2
Clopidogrel- blocks ADP receptors
Ticagrelor or prasugrel can be used instead of clopidogrel
How much aspirin and clopidogrel is given?
300mg
When is clopidogrel given?
Once there are ECG changes or elevation of cardiac markers to back up your diagnosis
How can patients be re-perfused?
Thrombolysis (streptokinase) or PCI (preferred)
When should patients receive thrombolysis?
If PCI cannot be carried out within 90 mins of diagnosis
What should happen to patients after receiving thrombolysis?
Coronary angiography or emergency angioplasty
What is the step by step treatment of STEMI?
Analgesia (IV diamorphine) Anti-emetic (IV metoclopramide) Aspirin and clopidogrel GTN (if BP >90mmHg) Oxygen if hypoxic PCI or thrombolysis
What medications should patients be put on following a STEMI?
Beta blocker, ACE inhibitor, statin and dual antiplatelet therapy (aspirin for life, other for less)
Patients with heart failure can also be put on what drug long term?
Aldosterone antagonists- spironolactone
What lifestyle advice should patients be given following a STEMI?
Stop smoking, cut down alcohol, advice better diet (lots of omega 3), exercise 20-30 mins a day
What are the rules regarding sex after an MI?
Can resume after four weeks and will have no effect on future MIs
What advice should be given about driving following MI?
4 weeks until you start again and no need to tell DVLA (car/bike)
6 weeks until you start again and do need to tell the DVLA (large vehicle)
What is the main arrhythmic complication of a STEMI? How is it treated?
VF- defibrillation
What are structural complications after a STEMI?
Cardiac rupture, VSD, mitral regurgitation with papillary muscle damage, left ventricular aneurysm, pericarditis/Dressler’s syndrome
Which STEMI complication would cause recurrent chest pain and shock, low BP and CO?
Ventricular septal defect
What complication of a STEMI can present as pulmonary oedema?
Mitral regurgitation
What complication of a STEMI will give persistent ST elevation and LV failure?
Left ventricular aneurysm
What is Dressler’s syndrome?
An autoimmune condition cause pericarditis 2-10 weeks post MI
What complications could a new heart sound suggest?
VSD or mitral regurgitation
What can all STEMI complications lead to?
Acute or chronic heart failure and possible cardiogenic shock
What is the difference in pathogenesis of NSTEMI?
Artery is not completely occluded
How is complete occlusion prevented in NSTEMI?
By our bodies own thrombolysis- plasmin
What is the main feature of an NSTEMI?
Chest pain
What is the most important thing to remember about an NSTEMI?
ECG may be normal
What can an ECG of NSTEMI show?
ST depression or T wave inversion
What is a type II MI?
Not caused by a rupture of a plaque but instead by an imbalance of oxygen supply and demand
How is the coagulation cascade blocked in NSEMI?
LMWH
What can be used to prevent progression of NSTEMI to STEMI?
2b3a inhibitors
Patients who are at high risk with identifiable troponin should undergo what?
Coronary angiography and revascularisation
What should long term therapy be for NSTEMI?
Aspirin (life) and clopidogrel (3 months)
What should a patients target cholesterol and BP be following an NSTEMI?
<4mmol/l and <140/85
