Myocardial Infarction Flashcards
When will ischaemia lead to infarction
Causes tissue death if blockage persists for over 20 minutes
Blockages of which arteries in the body cause infarction to which areas
Heart - coronary artery atheroma
Limb - femoral and popliteal arteries
Brain - carotid arteries - embolic stroke
What is a myocardial infarction
When there is a blockage of a coronary artery without a collateral supply so all tissue distal to the blockages will be lost
What is the strategy for treating infarction
Reduce tissue loss from necrosis by opening blood flow to ischaemic tissues through thrombolysis, angioplasty and stenting, or bypass obstruction
What is a stroke
Embolisation from carotid artery made of platelets, which are removed quickly from circulation so patency of vessels will open again naturally
What are the symptoms of MI
Amplified version of angina - central crushing chest pain
Why does a patient feel pain during an MI
ANS relays pain signals from heart to brain causing autonomic systems to be activated through the thalamus, so patient can’t ignore the pain
What are the different leads on a 12 lead ECG
I II III AVR AVL AVF Chest leads - V1 - V6
Describe the ECG changes seen after an MI
ST elevation Eventually a Q wave will develop T wave inverts ST normalises Q wave persists If someone has had a previous MI, the Q deflection is much larger
What is thrombolysis
Using a chemical drug such as streptokinase or plasminogen activator to dissolve blood clots
How should a patient who has just had an MI be treated
Aim to get patient to hospital alive
Analgise, give aspirin and reassure
Patient may develop sudden cardiac rhythm changes which could lead to cardiac arrest - give BLS
How should an MI patient be treated in hospital
Aim to restore oxygen to the area of infarcted tissue
Up to 3 hours from onset - angioplasty and stenting can be carried out
Up to 6 hours from onset - thrombolysis if suitable
Which drugs can be used to prevent future MIs
Aspirin
Beta blockers
ACE inhibitors
What are the complications of MI
Death - usually due to sudden arrhythmia at time of MI
Post MI arrhythmias
Heart failure
Ventricular hypofunction and mural thrombosis
DVT and pulmonary embolism
