Myocardial Infarction Flashcards
What is acute coronary syndrome?
What causes myocardial infarction?
Acute coronary syndromes encompass a spectrum of conditions which include unstable angina, and acute myocardial infarction with or without ST-segment elevation.
MI: Thromboembolism or rupture of plaque
State the differential diagnosis of MI
Indigestion/oesophageal reflux
Angina
Musculoskeletal pains
Panic attacks
Pulmonary embolism
How can you diagnose MI?
ECG = ST elevation (STEMI)
Non-STEMI = unstable angina/partial thickness infarcts
When somebody has a heart attack, the tissue is damaged. Tissue leaks out proteins an enzymes.
- Troponin - released within hrs. Peak is at 36 hrs. Small amounts in unstable angina.
- Creatine kinase
- Aspartate aminotransferase
- Lactate dehydrogenase
The complications of a heart attack is what kills. What are they?
Arrhythmias
Ventricular Fibrillation - major cause of death, require defibrillation with DC shocks
Atrial Fibrillation - does not require treatment unless raisesd ventricular rate = electric shock
Heart block = need of pacemaker
Ischemia
Mechanical complications - necrotic muscle may rupture
What are the goals of treatment in MI?
Pain relief
Restore coronary flow
Prevent further heart attacks
Prevent/reduce arrhythmias
What is first initial treatment (first aid) of MI?
Hospital ASAP
300 mg soluble/chewable aspirin (antiplatelet drug - prevent further platelet aggregation)
- Clopdogrel used if
Oxygen
Nitrates
25% mortality in 1st hr
What is the pain relief used in MI?
Morphine/diamorphine IV
Anti-emetics (for nausea from morphine)
- Cyclizine
- Prochlorperazine
- Metoclopramide
Thrombolysis is an old treatment method to treat MI.
How do they do this?
Thrombolysis dissolves clot to salvage cardiac muscle.
Clot busting drugs activate plasminogen into plasmin which chop the clot up.
Damage si irreversible 6h post MI
What are the contraindication to thrombolysis?
related to bleeding
If pts have:
- peptic ulcer
- pregnancy
- internal bleeding
- recent surgery
- intracerebral haemorrhage
- uncontrolled hypertension.
How does beta-blocker help treat MI?
IV atenolol + metoprolol reduces arrhythmias + improves survival
Improve myocardial perfusion + reduce infarct size
Reduce chance of cardiac rupture
Avoid in bradycardia + heart failure
Orale beta-blockade improves long-term survival
Stoppage increases risk of MI
Antiarhythmic drugs have a limited use in MI, they can increase mortality.
Why is this?
Antiarrhythmic may be proarrhythmic on the ischemic myocardium
Lidocaine for ventricular ectopics
What are the drugs prescribed when pt who suffered MI use?
Aspirin/clopidogrel
Beta-blocker/CCB
ACEi
Statin
Depression
