Myocardial infarction

Question 1

Definition

Answer 1

Most common reason is atherosclerosis, plaque build up in the arteries that compromises blood flow to your heart, leading to the deoygenation causing death of tissue

Question 2

What is the process of an MI

Answer 2

he heart must pump blood around the body but also to itself
- When there’s a reduction in blood flow to through the coronary arteries this is termed as ischaemic heart disease
- Most common cause is when a plaque builds up in the arteries.
- Within the coronary artery the plaque ecludes the vessel reducing blood flow. This can lead to angina- irritation of heart muscle causing chest pain but no muscle death.
- However, in MI, the top of the plaque gets knocked off exposing the contents of the plaque.
- Platelets start to aggregate around the top of the plaque which leads to a clot or a thrombus.
This stops blood getting pass completely, a full occlusion. No blood passes.

Question 3

Why don’t we give o2 in an MI

Answer 3

The passageways that 02 aspires to go down to oxygenate the cells is blocked so delievering more o2 to pts with an MI has no positive impact

Question 4

what do you give in an MI and why

Answer 4

• aspirin to reduce blood clots
• GTN to attempt vasodilation

Question 5

Oxygen in an MI

Answer 5

• Without Oxygen, cells switch from aerobic to anaerobic metabolism
• This means ATP is used faster than it can be replaced
• Therefore hydrogen ions and lactic acid accumulate causing further damage to the myocardium

Question 6

What else do oxygen deprivation cause?

Answer 6

• Electrolyte disturbances- specifically loss of potassium, calcium and magnesium from cells.
• This leads to loss of contractility and reduction in pumping

Question 7

What are the two types of MI

Answer 7

Stemi and N-stemi

Question 8

Describe a STEMI

Answer 8

• Full thickness infarct meaning the whole muscle wall dies
• ECG: ST elevation
• Elevation in cardiac enzymes- troponin due to necrosis

Question 9

Describe a N-STEMI

Answer 9

• Partial thickness infarct meaning partial muscle wall dies
• ECG: ST depression or T wave inversion
• Elevation in cardiac enzymes- tropin due to necrosis

Question 10

Symptoms of MI

Answer 10

• crushing chest pain
• pain in the jaw/ arm radiating
• SOB
• Sweating, clammy
• Nausea
• Dizziness, may be a LOC
• No pleuritic pain
• Not relieved in positional changes

Question 11

Risks of MI

Answer 11

• High BP
• Smoking
• Diabetes
• Lack of exercise
• Obesity
• High blood cholestrol
• Poor diet

Question 12

Differential diagnosis of MI

Answer 12

• Pericarditis
• Ascending aoritc anerysm
• Non ischaemic cardiac injury