Week 9 / CHD Overview

Question 1

Q: What is tissue ischaemia?

Answer 1

A: Reduced blood flow to an organ or tissue.

Question 1

Q: What are the consequences of tissue ischaemia? [2]

Answer 1

A:
Lack of O₂ & nutrient supply

Lack of washout of metabolic waste
[less blood less waste removed]

Question 2

Q: What types of tissue damage can occur in ischaemia?

Answer 2

A: Reversible and irreversible tissue damage.

Question 3

Q: What determines the extent of tissue damage in ischaemia? [2]

Answer 3

A: Determinants of extent of tissue damage
Duration,
Which organ [the brain cant cope],
severity,
tissue type,
collateral circulation

Question 4

Q: What is myocardial ischaemia?

Answer 4

A: Reduced regional blood flow to the heart.

[Myocardial = Heart muscle]

Question 5

Q: How is myocardial ischaemia defined in terms of supply and demand?

Answer 5

A: It is an imbalance between myocardial oxygen demand and supply.

Question 6

Q: What are the two main concepts of myocardial ischaemia?

Answer 6

A:
Exertional (demand) ischaemia: occurs when demand ↑ but supply cannot keep up.

Non-exertional (supply) ischaemia: occurs when supply ↓ regardless of demand.

Question 7

Q: What are the main determinants of myocardial oxygen demand? [3]

Answer 7

A:
Wall stress
Heart rate
Contractility

Question 8

Q: What are the main determinants of myocardial oxygen supply?

Answer 8

A:
Coronary blood flow (CBF) × Arteriovenous O₂ difference (A – V O₂)

Coronary blood flow is near maximum at rest.

Question 9

Q: Why is coronary blood flow (CBF) so important for myocardial oxygen supply?

Answer 9

A: Because the myocardium extracts almost all available O₂ at rest, so increases in demand must be met by ↑ CBF.

Question 10

Q: What is the definition of Coronary Heart Disease (CHD)?

Answer 10

A: Pathological conditions characterised by reduced or inadequate blood flow to the heart.

Question 11

Q: What is the usual cause of reduced blood flow in CHD?

Answer 11

A: Obstructive or constrictive disease of the coronary arteries.

Question 11

Q: What are the alternative names for CHD?

Answer 11

A:

Coronary artery disease (CAD)

Ischaemic heart disease (IHD)
[Broad Term]

Question 12

2025 BHF HeartStats Report

Answer 12

OPEN PP

Question 13

What is the disease process or steps of CHD[4]

Answer 13

1-coronary artery obstruction or
constriction

2- reduced regional blood flow to the heart

3- oxygen & nutrient deprivation and
accumulation of toxic metabolic wastes

4-metabolic dysfunction
[Lack of oxygen from lack of ATP]
contractile dysfunction
[Cant beat due to lack of ATP]
electrical instability
myocardial cell death (infarction)

Question 14

Q: What are the main clinical manifestations of Coronary Heart Disease (CHD)? [3]

Answer 14

A:

Angina pectoris (‘Stable’, ‘Variant’, ‘Microvascular’)

Immediate or sudden cardiac death

Acute Coronary Syndromes (ACS): Unstable angina, Acute MI (NSTEMI, STEMI)

Question 14

Q: What are the three types of angina pectoris seen in CHD?

Answer 14

A:
Stable angina

Variant (Prinzmetal’s) angina

Microvascular angina

Question 15

Q: What conditions are included under Acute Coronary Syndromes (ACS)? [2]

Answer 15

A:

Unstable angina

Acute myocardial infarction (NSTEMI, STEMI)

Question 16

Q: What are the key pathological factors contributing to CHD?
[what can cause / provoke CHD?]

[4]

Answer 16

A:

Atherosclerosis

Coronary thrombosis

Coronary artery spasm

Coronary microvascular dysfunction

Question 17

Q: What is the definition of atherosclerosis?

Answer 17

A: A progressive, degenerative arterial disease characterized by asymmetric deposition of lipids and fibrous tissue on the inside wall of arteries.

Question 18

Q: What percentage of CHD cases are caused by atherosclerosis?

Answer 18

A: More than 90%.

Question 19

Q: What type of process is atherosclerosis?

Answer 19

A: An inflammatory process (response to injury).

Question 20

Q: How does atherosclerosis begin?

Answer 20

A: Early in life as a “fatty streak.”

Question 21

What is the disease process or steps of Atherosclerosis [6]

Answer 21

1-LDL deposition in sub-endothelial space

2-LDL oxidation + Monocyte recruitment into sub-endothelial space

3- Macrophage differentiation + uptake of oxidised LDL

4- Foam cell formation

5-SMC migration, proliferation & de-differentiation

6-Fibrous plaque or atheroma

Question 22

Q: What is the impact of partial coronary occlusion due to atherosclerosis? Q: How does endothelial/vascular dysfunction in atherosclerosis affect coronary function? Q: What is the consequence of ulceration or rupture of an atherosclerotic plaque?

Answer 22

A: Stable angina. A: It can lead to coronary artery spasm. A: Coronary thrombosis.

Question 23

Q: What is the definition of coronary thrombosis?

Answer 23

A: Unwanted formation of a haemostatic plug, thrombus, or blood clot within coronary arteries. [Body is tricked into thinking there is a breach in the wall so unwanted clots are formed]

Question 24

Q: In what percentage of Acute Coronary Syndromes (ACS) is coronary thrombosis seen?

Answer 24

A: ~30–90% (in unstable angina & evolving acute myocardial infarction).

Question 25

Q: On what lesion does coronary thrombosis usually occur?

Answer 25

A: On top of a ruptured atheroma. 👇👇👇 [a fatty substance that builds up in your arteries over time]

Question 25

Q: What two processes are involved in the formation of coronary thrombosis?

Answer 25

A: Platelet aggregation and the coagulation cascade.

Question 26

What is the disease process or steps of Coronary thrombosis ? [4]

Answer 26

1-Rupture or ulceration of atherosclerotic plaque 2-Contact of blood elements with collagen & tissue factor 3a- Platelet adhesion & activation platelet aggregation 👆👇 3b-Activation of coagulation cascade fibrin formation & deposition 4-Thrombus / clot

Question 27

Q: What is the consequence of coronary artery due to thrombosis? [3]

Answer 27

A: Impact on coronary function complete & permanent occlusion of coronary artery ➡ ACS (STEMI) [Acute Coronary Syndrome (STEMI)] Subtotal or intermittent occlusion of coronary artery ➡ ACS (UA / NSTEMI) [Acute Coronary Syndrome (Unstable Angina / NSTEMI).] Thromboembolism in a distal artery

Question 28

Q: What is the definition of coronary artery spasm?

Answer 28

A: A transient, spontaneous coronary vasoconstriction.

Question 29

Q: Where can coronary artery spasm occur? [3]

Answer 29

A: In ‘normal’ coronary arteries At ‘mildly’ atherosclerotic sites During ongoing coronary thrombosis

Question 30

Q: What clinical condition is caused by coronary artery spasm?

Answer 30

A: Variant (Prinzmetal’s) angina.

Question 31

What are the disease mechanism of coronary artery spasm? [3]

Answer 31

1-local endothelial injury increase reactivity to vasoconstrictors 2-abnormal release of vasoconstrictors or local imbalance in release of vasodilators & constrictors 3-smooth muscle cell hypercontraction/hyper-reactivity

Question 32

Whats the impact of coronary artery spasm on coronary function? [2]

Answer 32

1-subtotal or intermittent occlusion of coronary artery 2-complete focal occlusion of coronary artery

Question 33

Q: What is the definition of coronary microvascular dysfunction?

Answer 33

A: Damage to the inner walls of the small coronary blood vessels (coronary microvasculature), leading to microvascular spasms, decreased blood flow to the heart muscle, and reduced coronary flow reserve.

Question 34

Q: What is the coronary microvasculature?

Answer 34

A: Network of small coronary blood vessels (arterioles) that branch off the large epicardial coronary arteries.

Question 35

Q: What types of damage can occur in coronary microvascular dysfunction?

Answer 35

A: Structural: microvascular remodelling Functional: endothelial dysfunction

Question 36

Q: What clinical condition is caused by coronary microvascular dysfunction?

Answer 36

A: Microvascular angina.

Question 37

Coronary Microvascular Dysfunction – Mechanisms & Impact Q: What structural change occurs in microvascular remodelling due to Coronary Microvascular Dysfunction ? what is the consequence of microvascular remodelling?

Answer 37

A: Luminal narrowing of intramural arterioles and capillaries → microvascular obstruction.

Question 38

Coronary Microvascular Dysfunction – Mechanisms & Impact Q: How does endothelial dysfunction contribute to coronary microvascular dysfunction? What does endothelial dysfunction lead too?

Answer 38

A: Impaired vasodilator response → reduced coronary blood flow during exercise or stress.

Question 39

Coronary Microvascular Dysfunction – Mechanisms & Impact Q: What role do smooth muscle cells play in coronary microvascular dysfunction?

Answer 39

A: Functional abnormalities of smooth muscle regulate the arteriolar tone.

Question 40

Coronary Microvascular Dysfunction – Mechanisms & Impact Q: What is the impact of coronary microvascular dysfunction on coronary function?

Answer 40

A: Reduced coronary flow reserve → increased risk of myocardial ischaemia.

Question 41

Coronary Microvascular Dysfunction – Mechanisms & Impact Q: What clinical conditions can result from coronary microvascular dysfunction?

Answer 41

A: INOCA (Ischaemia with No Obstructive Coronary Artery disease, e.g., microvascular angina) MINOCA (Myocardial Infarction with No Obstructive Coronary Artery disease)

Question 42

Atherosclerosis – Progressive Process

Answer 42

Normal Artery │ ▼ Fatty Streak (clinically silent) │ ▼ Fibrous Atherosclerotic Plaque (may cause effort/stable angina) │ ▼ Occlusive Plaque (significant narrowing → worsening angina) │ ▼ Plaque Rupture / Fissure & Thrombosis │ ├─► Unstable Angina ├─► Acute Myocardial Infarction (NSTEMI/STEMI) └─► Sudden Coronary Death

Question 43

Q: What are the main medical risk factors for coronary atheroma and CHD?

Answer 43

A: High blood cholesterol (hypercholesterolaemia) Hypertension Diabetes Obesity

Question 44

Q: What are the main lifestyle/modifiable risk factors for coronary atheroma and CHD?

Answer 44

A: Poor diet Cigarette smoking Physical inactivity

Question 45

What are the disease mechanisms of Coronary Microvascular Dysfunction

Answer 45

microvascular remodelling microvascular obstruction endothelial dysfunction  impaired vasodilator response & reduced coronary blood during exercise or stress functional abnormalities of smooth muscle cells that regulate arteriolar tone