Myocardial Infaction Flashcards
(22 cards)
What is MI
Cell death of heart muscle - heart attack
Clinical signs of MI
- low BP
- high HR
Symptoms of heart attack
Sweatiness
Nausea
Excruciating chest pain
Breathlessness
ANGINA/acute coronary syndrome
Angina - what is it
Crushing central chest pain
Radiate to jaw or teeth
Or either arm
Brought on by stress, and lowered by rest and stopping physical exertion
Relieved by rest or GTN within 5 minutes
Also known as chronic coronary syndrome
Why does angina happen?
- chest pain due to myocardial ischaemia
- due to flow limiting atherosclerosis or anaemia etc..
What are most heart attacks caused by?
Describe mechanism
Coronary artery disease when coronary arteries narrow due to atheroma in their walls
- if atheroma is unstable and pieces break off this can lead to blood clot forming
- clot can block coronary arteries
- can starve heart of oxygen = damaged heart muscle (HEART ATTACK!!)
Also called acute soronayr syndroe
What is primary angioplasty
Where a stent is put in coronary artery after a heart attack to open up coronary artery to prevent new heart attack
What lifestyle changes to make to decrease heart attack?
- decrease alcohol
- decrease smoking
- weight loss
- exercise
Type 1 MI
Atherosclerotic plaque rupture in the coronaries, causing an occlusive thrombus (clot which forms over the atherosclerosis)
Or partial occlusion!!!
Most common!!
Type II MI
No plaque rupture and thrombus
- extreme atherosclerosis on both sides of vessel
- vasospasm of coronary arteries (eg: after cocaine ingestion)
- non-atherosclerotic coronary dissection
- oxygen supply and demand mismatch
What happens in heart attack?
Ischaemia
Impaired contraction of myocardium
Abnormal electrical activity can cause dangerous arrhythmias
What is the key aspect of virchows triad in MI
Changes to the vessel wall which causes changes to blood flow (makes it more turbulent), which cuuld rupture
Risk factors in risk calculators
Dyslipidaemia
Smoking
Diabetes
Hypertension
Male
Age
Family history
(Obesity, sedentary lifestyle, renal failure, inflammatory disease, south Asian ethnicity, low birth weight and socioeconomic status are also risk factors but nor on calculators)
What investigations are needed for heart attack
First - gold standard = ECG (determines whether to go for coronary angiography - elevates ST)
- coronary angiogram
- echocardiology
- serum troponing level
What is troponin
- cardiac protein involved in actin and myosin interaction and contractility
- released due to myocardial damage
What is the difference between a STEMI and NSTEMI
STEMI = ST elevation MI
- has ST elevation on heart attack
- raised troponin due to cardiac muscle damage
NSTEMI = non ST elevation MI
- may nor have ST elevation on ECG
- raised troponin due
If no ST elevation and no raised troponin = = unstable angina
Echocardiogram
Ultrasound showing which part of the heart may or may not be contracting
May indicate which coronary artery is blocked depending on which cardiac muscle not contracting
May show scarring
What is coronary angiography
Dye in coronary arteries
Injected
Opacities the vessels
Management of MI
Immediate:
- morphine pain relief
- high flow oxygen
- oral aspirin
- thrombocytes drugs (OLD) replaced with:
Surgical intervention: - primary percutaneous intervention - vessel in arm or leg , balloon to expand narrowed artery and put stent in
Simvastatin - to reduce death by Conor’s heart disease - inhibits HMG CoA reductase - to decrease cholesterol levels
Key drugs for prevention of MIs
- beta blockers - bisoprolol
- antiplatelet drugs: aspirin, P2Y12 inhibitors (prasugrel, ticagrelor, clopidogrel) - reduce platelet activation on stent clots
- ACE inhibitors - ramapril
- glyceryl trinitrate
Why are beta blockers used in MI
Decrease death rates in weeks afterwards:
- protects against arrhythmia
- negatively chronotropic, makes heart go slower, allowing for increased coronary artery filling.
- Reduces sympathetic over activity (and therefore hypertrophic remodelling). - Negatively ionotropic - reduce O2 demand as makes contract less/
Glyceryl trinatrate use and how it helps
- glyceryl trinitrate - spray for angina to increase nitric oxide level
- potent vasodilator for coronary dilatation, decreases preload and after load so heart doesn’t meed to contract as much , allowing for drcreased oxygen consumption!
