Myocardial Infarction

Question 1

Define acute myocardial infraction

Answer 1

Implies cell death due to prolonged ischaemia

Question 2

What is the aetiology of myocardial infarction?

Answer 2

Ischaeimia and thrombus/embolism

Question 3

What are the risk factors associated?

Answer 3

Age
Diabetes
Smoking
Hypertension

Question 4

What does the necrosis process from the first time to over 14 days involve?

Answer 4

<24hour = early coagulative necrosis 
1-3day = extensive necrosis 
-acute inflammation + neutrophil 
3-14 day = macrophage + granulation in margin
>14 day = contracted scar forms

Question 5

Roughly, describe the 5 classification types for MI

Answer 5

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

Question 6

What can type 1 MI also be caused by?

Answer 6

Coronary vasospasm: cocaine, triptans and 5-FU
Coronary dissection
Embolism of coronary artery
Inflammation of coronary artery

Question 7

Describe the difference between the 2 types of STEMI and NSTEMI

Answer 7

STEMI:
Coronary artery blocked completely
Transmural MI

NSTEMI
Not completely blocked
Subendocardial MI

Question 8

What are the symptoms of MI?

Answer 8

Acute central chest pain
Breathlessness 
Cough
Dypneoa 
Nausea 
Radiation of pain to arm, neck, back and stomach 
Sweating

Question 9

What are the risk factors of MI?

Answer 9

Age 
Male 
Diabetes/Obesity/Hyperlipiadaemia 
FH
High BP
Smoker

Question 10

Which gender is MI common in?

Answer 10

Male

Question 11

What are the signs of MI?

Answer 11

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

Question 12

What are the potential complications of MI?

Answer 12

DARTH VADER

Death
Arrythmias
Rupture
Tamponade
Heart failure

Valve diseae
Aneurysm of ventricle 
Dressters syndrome 
thrombo Embolism 
Recurance/Regurg

Question 13

What are the investigation techniques for ECG?

Answer 13

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

Question 14

Which artery is the problem for inferior, anterior and posterior MI?

Answer 14

Inferior = Right coronary artery 
Anterior = Left anterior descending coronary artery 
Posterior = Circumflex coronary artery

Question 15

If you have an anterolateral ST elevation, which artery is blocked and what type of MI is this?

Answer 15

Acute STEMI MI due to blocked LAD

Question 16

What are the diagnosis investigation techniques?

Answer 16

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

Question 17

What are the cardiac emzyme/biomarkers?

Answer 17

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

Question 18

What is the treatment for STEMI?

Answer 18

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

Question 19

Whats the difference between Cath and thrombolysis?

Answer 19

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

Question 20

What is the treatment of NSTEMI?

Answer 20

Less time sensitive but still reperfusion via PCI ( not thrombolysis )

Question 21

What is unstable angina and medications for it?

Answer 21

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

Question 22

What are medications used for all conditions in MI?

Answer 22

GTN:

• vasodilator: open coronary a
• Sublingual/IV

Opiates eg Morphine

• pain relief
• vasodilate

Anti-thrombotic:

1. 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

Question 23

What is the risks associated with PCI?

Answer 23

Bleeding 
Blood vessel damage
MI or stroke 
Coronary perforation 
Contrast nephropathy

Question 24

What is an option that can be used for treatment of 3 vessel disease and LMS disease?

Answer 24

Coronary artery bypass graft

Question 25

What are mechanical complications in treatment?

Answer 25

Myocardial rupture - tamponde
Acute ventricular septal defect
Mitral valve dysfunction due to papillary muscle rupture