Myocardial Infarction

Question 1

What is the main peri-infarct cause of death?

Answer 1

Ventricular arrhythmias

Question 2

How long post MI do myocardial wall and muscle rupture generally occur?

Answer 2

4-7 days post infarction

Question 3

What is the most likely cause of a Q wave MI?

Answer 3

Completely occlusive thrombus

Question 4

Evolving changes of Acute MI

Answer 4

First few hours = ST elevation
First day = Q wave formation and T wave inversion
Old MI = Q waves +/- inverted T waves

Question 5

What ECG changes must be present to diagnose a STEMI?

Answer 5

> 1mm ST elevation in 2 adjacent limb leads OR
2mm ST elevation in at least 2 contiguous precordial leads OR
New onset bundle branch block

Question 6

Which ECG leads are affected in an inferior infarction?

Answer 6

II, III and aVF

Question 7

Which ECG leads are affected in an anterior infarction?

Answer 7

V1-V6

Question 8

Which ECG leads are affected in an anteroseptal infarction?

Answer 8

V1-V4

Question 9

Which ECG leads are affected in an anterolateral infarction?

Answer 9

I, aVL, V3-V6

Question 10

Early treatment of STEMI

Answer 10

Morphine IV 
Oxygen
Nitrates 
Aspirin 300mg, Clopidogrel 300mg
IV anti-emetic 
Primary angioplasty or thrombolysis

Question 11

What is Aspirin’s mode of action?

Answer 11

Inhibits the COX enzyme, preventing the production of prostaglandin and thromboxane A2 from arachidonic acid
Thromboxane A2 would normally aid the expression of the GP IIb/IIIa binding site on the platelet, allowing for fibrinogen binding

Question 12

What is Clopidogrel’s mode of action?

Answer 12

Inhibits ADP-induced platelet aggregation by irreversibly binding to the ADP platelet receptor
ADP is usually necessary for activation of the G IIb/IIIa receptor

Question 13

Risks of thrombolysis?

Answer 13

Failure to perfuse
Haemorrhage
Hypersensitivity

Question 14

Complications of Acute MI?

Answer 14

Death
Arrhythmic
Structural
Functional

Question 15

What arrhythmic complications might arise from an MI?

Answer 15

Ventricular fibrillation

Question 16

What structural complications might arise from an MI?

Answer 16

Cardiac rupture 
Ventricular septal defect 
Mitral valve regurgitation
Left ventricular aneurysm formation 
Mural thrombus +/- systemic emboli 
Inflammation 
Acute pericarditis 
Dressler's syndrome

Question 17

What functional complications might arise from an MI?

Answer 17

Acute ventricular failure (left, right or both)
Chronic cardiac failure
Cardiogenic shock

Question 18

What do troponins measure?

Answer 18

Embolisation
Microvascular circulation
Myonecrosis
Almost absolute myocardial specificity/high sensitivity

Question 19

Four Phases of Cardiac Rehab

Answer 19

1 - In Patient
2 - Early post discharge period
3 - Structures exercise programme (usually hospital based)
4 - Long term maintenance of physical activity and lifestyle change (usually community based)

Question 20

What is the first stage in the development of atherosclerosis?

Answer 20

Endothelial dysfunction triggered by damage to the endothelium (e.g. smoking, hypertension, hyperglycaemia)

Question 21

What types of early changes occur to the endothelium in the development of atherosclerosis?

Answer 21

Pro-inflammatory
Pro-oxidant
Proliferative
Reduced nitric oxide bioavailability

Question 22

What is the role of LDL in the development of atherosclerosis?

Answer 22

After initial changes to the endothelium, LDL moves into the subendothelial space, causing fatty infiltration

Question 23

What is the role of macrophages in the development of atherosclerosis?

Answer 23

Macrophages phagocytose oxidised LDL in the sub endothelium, and slowly turn into large foam cells
The death of these macrophages further propagates inflammatory processes

Question 24

What is the role of smooth muscle cells in the development of atherosclerosis?

Answer 24

Smooth muscle proliferation and migration from the tunica media into the intimate results in formation of a fibrous capsule covering the fatty plaque formed from the macrophage foam cells