Myocardial Infarction Flashcards
Define acute myocardial infraction
Implies cell death due to prolonged ischaemia
What is the aetiology of myocardial infarction?
Ischaeimia and thrombus/embolism
What are the risk factors associated?
Age
Diabetes
Smoking
Hypertension
What does the necrosis process from the first time to over 14 days involve?
<24hour = early coagulative necrosis 1-3day = extensive necrosis -acute inflammation + neutrophil 3-14 day = macrophage + granulation in margin >14 day = contracted scar forms
Roughly, describe the 5 classification types for MI
Type 1 = spontaneous and due to primary coronary event eg; plaque erosion, rupture or dissection
Type 2 = Imbalance in supply and demand of O2. Result of ischaemia but not from thrombosis/Embolism
Type 3 = Sudden death + ischaemia + coronary thrombus
Type 4 A = Associated with PCI
Type 4 B = Stent thrombosis
Type 5 = CABG
What can type 1 MI also be caused by?
Coronary vasospasm: cocaine, triptans and 5-FU
Coronary dissection
Embolism of coronary artery
Inflammation of coronary artery
Describe the difference between the 2 types of STEMI and NSTEMI
STEMI:
Coronary artery blocked completely
Transmural MI
NSTEMI
Not completely blocked
Subendocardial MI
What are the symptoms of MI?
Acute central chest pain Breathlessness Cough Dypneoa Nausea Radiation of pain to arm, neck, back and stomach Sweating
What are the risk factors of MI?
Age Male Diabetes/Obesity/Hyperlipiadaemia FH High BP Smoker
Which gender is MI common in?
Male
What are the signs of MI?
Auscultation:
Inspiration crackles
3rd or 4th heart sound
Pansystolic murmur (MR due to necrosis of papillary muscles)
Palpation: Sweating and cool skin Increased heart rate Increased or decreased blood pressure Raised JVP
Inspection
Pallor
What are the potential complications of MI?
DARTH VADER
Death Arrythmias Rupture Tamponade Heart failure
Valve diseae Aneurysm of ventricle Dressters syndrome thrombo Embolism Recurance/Regurg
What are the investigation techniques for ECG?
ECG :
STEMI -> ST elevation initally -> Q wave longer or wider at 3 days
NSTEMI -> initally can have either ST depression, T wave inversion or can be normal
ECG can show specifically where the problem is:
V1-4 is anterior
V5 and 6 is lateral
II, III and VF is inferior
Which artery is the problem for inferior, anterior and posterior MI?
Inferior = Right coronary artery Anterior = Left anterior descending coronary artery Posterior = Circumflex coronary artery
If you have an anterolateral ST elevation, which artery is blocked and what type of MI is this?
Acute STEMI MI due to blocked LAD
What are the diagnosis investigation techniques?
Detection of cardiac cell death eg: a + cardiac biomarker
And also one of:
- ischaemia symptom
- New ECG change
- Angiogram/autopsy change
- Evidence of new cardiac change
Cardiac enzyme/biomarkers could include:
- troponin rise in 2-4h
- Ck-MB: detect reinfarction after MI. Increases at 24h then decreases
What are the cardiac emzyme/biomarkers?
Cardiac enzyme/biomarkers could include:
- troponin rise in 2-4h
- Ck-MB: detect reinfarction after MI. Increases at 24h then decreases
Biomarker release period eg: myoglobin
However other reasons for increase in troponin can be:
- Arrythmia
- Cardiac contusion
- Sepsis
- Renal failure
- Pulm embolism
What is the treatment for STEMI?
Open coronary artery ASAP
Can do reperfusion therapy:
- Mechanical can include PCI: angioplasty, stent
- Pharmalogical can include thrombolysis: tenecteplase given as bolus
Blood tests include troponin, Hb, kidney function and cholestrol
Whats the difference between Cath and thrombolysis?
Thrombolysis works well the earlier its given
Thrombo more likely to cause bleeding
If can get to catch lab in 2 hours, transfer. If not, give thrombolysis
What is the treatment of NSTEMI?
Less time sensitive but still reperfusion via PCI ( not thrombolysis )
What is unstable angina and medications for it?
Acute severe chest but have no ECG and biochemical evidence of MI. Rapidly worsens and no cell death so troponin will not increase.
Medication:
Clopidogrel
LMWH
Enoxaparin
What are medications used for all conditions in MI?
GTN:
- vasodilator: open coronary a
- Sublingual/IV
Opiates eg Morphine
- pain relief
- vasodilate
Anti-thrombotic:
- Antiplatelet:
- Aspirin: 300mg LD, 75mg OD
- Clopidogrel 300 LD, 75 OD
- Ticagrelor 180 LD 90 BD
- Prasugrel 60 LD 10 OD
2.Anticoagulant:
-Heparin: given as infusion
-LMWH
Fondaparinux: 2.5mg od
Other:
- Beta blocker: reduce work heart has to do
- Statin: work independent of cholestrol level
- ACE inhibitor: help heart muscle recover
What is the risks associated with PCI?
Bleeding Blood vessel damage MI or stroke Coronary perforation Contrast nephropathy
What is an option that can be used for treatment of 3 vessel disease and LMS disease?
Coronary artery bypass graft
