Unit 6 - Cardiovascular system 6

Question 1

What is myocardial oxygen balance?

Answer 1

Ratio of oxygen supply to oxygen demand

Question 2

What is oxygen supply increased by?

Answer 2

Either increasing arterial oxygen content or increasing coronary blood flow

Question 3

What is an increase in blood pressure or heart rate met with?

Answer 3

A proportionate increase in coronary blood flow

Question 4

When does myocardial ischaemia develop?

Answer 4

When blood supply to the myocardium is inadequate to meet the metabolic demands of the tissue

• absolute reduction at rest
• supply ischaemia
• relative reduction in face of increased muscle work
• demand ischaemia

Question 5

What percentage of cases is myocardial ischaemia associated with critical stenosis of one or more coronary arteries?

Answer 5

95%

- practically unknown in absence of coronary artery disease

Question 6

What is chronic stable angina?

Answer 6

Critical stenosis (narrowing) of one or more epicardial coronary arteries due to atherosclerosis

• advanced and stable plaques in one or more multiple locations
• fixed stenosis

Question 7

What is the main symptom of chronic stable angina?

Answer 7

Typical pattern of demand ischaemia
- angina pain develops on exertion
reproducibly relieved by rest or nitrovasodilator

Question 8

What is the characteristic pain pattern of chronic stable angina?

Answer 8

Referred pain

referred pain to the chest and upper left arm

Question 9

What is silent ischaemia?

Answer 9

Evidence of myocardial ischaemia in the absence of chest discomfort

Question 10

What percentage of transient ischaemic episodes in stable coronary artery disease are NOT associated with pain?

Answer 10

70%

Question 11

Which group of patients is silent ischaemia particularly seen in?

Answer 11

Diabetic patients

- sensory neuropathy

Question 12

What can be used to diagnosis silent ischaemia?

Answer 12

Exercise or stress testing along with ambulatory ECG

- Holter monitor

Question 13

What are the three other types of ischaemia?

Answer 13

• Prinzmetal’s (variant) angina
• cardiac syndrome X
• unstable (crescendo) angina

Question 14

What is Prinzmetal’s (variant) angina?

Answer 14

Occurs at rest due to coronary artery spasm/constriction

- rare

Question 15

What is Cardiac syndrome X?

Answer 15

Angina without epicardial coronary arteries

• more likely to be a microvascular disease
• more common in women

Question 16

What is unstable (crescendo) angina?

Answer 16

Sudden onset
- at rest
- exercise
An acute coronary syndrome
- thrombosis leads to occlusion at site of plaque

Question 17

What can chronic coronary disease lead to?

Answer 17

Cardiomyopathy resulting in reduced left ventricle output

Question 18

What does chronic hypoperfusion lead to?

Answer 18

Reduced output in viable myocardium
- hibernating myocardium
Reversible with revascularisation

Question 19

What is an acute coronary syndrome?

Answer 19

Umbrella term

• blood supply to the heart is suddenly blocked
• unstable angina
• acute myocardial infarction (AMI)

Question 20

What is the difference between unstable angina and acute myocardial infarction?

Answer 20

Unstable angina - obstruction typically incomplete
Acute myocardial infarction - usually fully occluded vessel
- rendering distal myocardium ischaemic

Question 21

What process precipitates coronary thrombosis?

Answer 21

Fissuing

Atheromatous plaque rupture

Question 22

What is a coronary thrombosis?

Answer 22

Formation of a blood clot in a coronary artery

Question 23

What can the formation of a coronary thrombosis be related to?

Answer 23

Increase in emotional or physical stress
Circadian rhythm
- sympathetic nervous system
- temperature changes
- heart rate in the morning

Question 24

What are the symptoms of acute coronary syndromes?

Answer 24

Chest pain
- tightness
- pressure
- discomfort
Pain or discomfort in one or both arms
Shortness of breath
Feeling dizzy or lightheaded
Nausea and/or diaphoresis
Anxiety
Symptoms steadily worsen
- unrelieved by rest or nitrates

Question 25

How is an acute coronary syndrome diagnosed?

Answer 25

Symptoms
ECG
Biomarkers

Question 26

What is STEMI?

Answer 26

ST elevation myocardial infarction

Question 27

What is NSTEMI?

Answer 27

Non-ST elevation myocardial infarction

Question 28

What biomarkers appear in plasma in hours post onset of symptoms indicative of muscle damage, both for NSTEMI and STEMI?

Answer 28

• troponins

- creative kinase isoforms

Question 29

When is treatment initiated for muscle damage seen in NSTEMI or STEMI?

Answer 29

Before results of bloods

- especially if diagnostic ECG present

Question 30

What is the molecular pathology of Myocardial infarction?

Answer 30

Deprivation of an area of the myocardium of oxygenated blood flow
- hypoxia
- cessation of mitochondrial oxidative phosphorylation
- reduction in source of ATP
Anaerobic glycolysis attempts to compensate
- demand outweighs supply
- only 7% requirement produced
H+ and lactate build up
- production of ROS
- impaired contraction
- impaired contracture
Cell death by oncosis, apoptosis and autophagy
- coagulation necrosis at tissue level
- infarct progress from endocardium to epicardium
- little or not collateral circulation

Question 31

What is a major determinant of irreversible injury following an MI?

Answer 31

Time

Question 32

What are the complications following an MI?

Answer 32

Cardiogenic shock
Heart failure
Arrhythmia

Question 33

Where is the majority of cholesterol produced?

Answer 33

Liver

- contribution from diet