9 - myocardial infarctions

Question 1

What is a myocardial infarction?

Answer 1

The death of myocardial cells as a result of heart muscle cells as a result of a lack of oxygen due to a lack of bloodflow

Question 2

Define morbidity

Answer 2

The condition of suffering from a disease

Question 3

What is the cause of a myocardial infarction

Answer 3

The supply of blood to coronary muscle is seriously reduced, usually as a result of atheromatous plaque rupture with overlying thrombosis

Question 4

What are the consequences of an atheroma

Answer 4

Artery narrowing - leading to ischemia, hypoxia, angina and pain
Thrombus formation - can lead to MI
Bleeding in plaque - can cause MI
Aneurysm

Question 5

Define atherosclerosis

Answer 5

The thickening and hardening of a high pressure artery wall caused by atheroma

Question 6

Define atheroma

Answer 6

Lipid accumulation in the inner lining of the arteries

Question 7

How do you diagnose acute myocardial infarctions?

Answer 7

Altered level of troponin plus chest pain, ECG abnormalities or imaging evidence

Question 8

How does an MI appear on an ECG

Answer 8

An elevated ST region

Question 9

Give some examples of cardiac biomarkers

Answer 9

Creatine kinase (non specific muscle enzyme), myoglobin (non specific - cleared quickly) and troponin I and T (specific)

Question 10

How can you treat myocardial infarctions?

Answer 10

Thrombolytic agents - streptokinase and tissue plasminogen activator
Anticoagulant - heparin
Coronary angioplasty
Coronary bypass

Question 11

What is a coronary bypass?

Answer 11

Using a blood vessel from another region of the body to divert blood around a blockage in the coronary artery

Question 12

What is a coronary angioplasty?

Answer 12

Catheter inflated in the obstructed vessel to remove obstruction and enable blood flow

Question 13

What are four consequences of an atheroma

Answer 13

• artery narrowing leading to ischaemia, hypoxia, angina and pain
• thrombus formation in the plaque that can lead to myocardial infarctions and cerebrovascular accidents
• bleeding into the plaque which can lead to myocardial infarctions if this occurs in the coronary arteries
• aneurysm

Question 14

What does the left coronary artery supply?

Answer 14

• circumflex branch which provides blood to the left ventricle and left atrium
• anterior intraventricular branch which provides blood to both ventricles

Question 15

What does the right coronary artery supply?

Answer 15

Marginal branch - right ventricle

Posterior interventricular branch - both ventricles

Question 16

What is the structure of the artery?

Answer 16

• tunica intimia which consists of the endothelium, basement membrane and the internal elastic lamina
• tunica media which consists of smooth muscle and the external elastic lamina
• tunica externa which consists of elastic and collagen tissue