Lecture 11 Ischaemic Heart Disease I

Question 1

What is meant by ischaemic heart disease

Answer 1

Ischaemic heart disease is a condition where the blood flow in the coronary arteries is restricted by an obstruction

Question 2

What is the significance of IHD as a disease

Answer 2

It kills more people worldwide than any other disease

Question 3

What is the ultimate cause of death in patients with IHD

Answer 3

Acute myocardial infarction

Question 4

What causes IHD

Answer 4

Ischaemic disease occurs when a fatty/fibrous plaque called an atheroma blocks the coronary artery lumen. This means that blood flow to tissues is then restricted leading to ischaemia

Question 5

What happens when ischaemia occurs

Answer 5

Oxygen demand to the myocardium exceeds supply

Question 6

How does IHD usually present

Answer 6

Patients with IHD often present with chest pain. This chest pain can be due to angina or myocardial infarction

Question 7

What is meant by the term angina

Answer 7

Cardiac-related chest pain

Question 8

There are two classes of risk factors in IHD what are they

Answer 8

Modifiable and non-modifiable

Question 9

Give some examples of non-modifiable risk factors in IHD

Answer 9

Age male personal history (positive family history usually 1st degree relative before the age of 65)

Question 10

Give some examples of modifiable risk factors in IHD

Answer 10

Smoking diet/obesity renal disease high blood pressure and diabetes

Question 11

What class of conditions are IHD patients susceptible to when the plaque ruptures

Answer 11

Acute coronary syndromes

Question 12

What are the different types of acute coronary syndromes

Answer 12

Unstable angina non-ST elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI)

Question 13

Which is the most severe form of acute coronary syndrome

Answer 13

STEMI

Question 14

How are the three forms of acute coronary syndromes related

Answer 14

Unstable angina will progress to NSTEMI or potentially STEMI

Question 15

Stable angina is a type of acute coronary syndrome T or F

Answer 15

F – it is not

Question 16

How does stable angina present

Answer 16

Chest pain that occurs with increase physical activity or exertion but with a normal ECG

Question 17

Use the diagrams below to explain the difference between stable and unstable angina

Answer 17

In stable angina the lipid core is often walled-off from the blood flow. In addition a large degree of healing has occurred so that the intimal layer separates and protects atheroma from the blood. This prevents progression to the ACS stage. However in unstable angina there is the addition of a platelet plug fibrous plaque and thrombus consisting of a matured fibrin clot. This has progressed to the stage at which most of the central core of the vessel is blocked

Question 18

What is meant by a mural thrombus

Answer 18

This is where the complete core of the vessel is blocked by clot platelet plug and plaque

Question 19

Anginal pain is always relieved by rest T or F

Answer 19

F – whilst this is true for most angina it is not the case in STEMI

Question 20

Treatments used for angina based around knowing what type of angina the patients have T or F

Answer 20

T

Question 21

How is stable and unstable angina treated

Answer 21

Stable angina patients are treated with nitrates and Ca2+ channel blockers to reduce the cardiac work. They are also treated for the underlying condition for example using statins in high cholesterol. Finally there is a degree of prophylactic treatment using anti-platelet therapy such as aspirin. Meanwhile unstable angina patients are treated as for a myocardial infarction. They are given dual anti-platelet therapy usually consisting of aspirin plus either clopidogrel or ticagrelor

Question 22

Complete the table below distinguishing the acute coronary syndromes

Answer 22

See completed table below

Question 23

Why does the ECG often appear normal in patients with angina

Answer 23

ECG will appear normal in stable and unstable angina unless there is a period of ischaemia at the time in which the ECG is being recorded

Question 24

What is the issue with using troponin levels as an indication of heart attack

Answer 24

Troponin takes a while to rise during a heart attack. Hence if you measure it too early myocyte death may not have occurred yet

Question 25

Which patients are sent straight to tertiary heart attack centres

Answer 25

STEMI

Question 26

What are the broad aims of the treatment for ischaemia

Answer 26

Reopen blocked arteries (stenting) reduce the coagulability of blood (DAPT) control of risk factors and reduce myocardial oxygen demand

Question 27

What is PCI

Answer 27

Percutaneous coronary intervention (PCI) is a non-surgical technique used to widen the artery using dilation from within

Question 28

When is PCI used as the primary treatment

Answer 28

In STEMI patients

Question 29

Why is it important to match the stent size to the size of the patients affected vessels

Answer 29

Important not to be oversized as overdilation will result in massive repair response and further narrowing of the vessel

Question 30

How is the stenosis in the patient’s coronary arteries viewed during stenting

Answer 30

A dye is injected into patients and viewed under fluoroscopy

Question 31

Which drugs are often used in drug eluting stents

Answer 31

Rapamycin and taxol are often used. Rapamycin is a cell cycle blocker that prevents progression between G1 and S phase. These drugs both act to inhibit regrowth of the vessel

Question 32

What is the door-balloon time in STEMI patients

Answer 32

120minutes

Question 33

Outline the mechanism of stenting

Answer 33

The stent is crimped down over a balloon connected to a wire. The balloon and stent inserted and navigated past the point of occlusion in the coronary artery. The balloon is then inflated to 8 atmospheres to extend the stent which is then placed against the vessel wall. Finally the balloon is deflated and removed with the stent remaining in place in the expanded vessel

Question 34

What treatment is usually prescribed alongside stenting

Answer 34

DAPT

Question 35

How many stents do the average patient receive

Answer 35

3-4 stents per person

Question 36

What used to be a major problem in stenting and why

Answer 36

Stenosis was a major problem. This was because the artery walls react badly to foreign bodies. This causes a healing response that actually acts to further narrow the vessel

Question 37

How can restenosis be prevented

Answer 37

Using drug eluting stents that inhibit the repair processes and proliferation of the vascular wall

Question 38

What is the main problem with drug eluting stents

Answer 38

Incidence of stent thrombosis is a problem with drug eluting stents. This is a serious condition with adverse clinical outcomes that occurs due to delayed or incomplete endothelialisation. This is because drug eluting stents prevent some of the healing response which leads to exposure of the metal of the stent to the flow of blood. If part of the blood connects to the metal stent or underlying vessel wall then it is likely that a thrombus will form

Question 39

What treatment is usually prescribed to override the problems with stent thrombosis seen in patients with drug eluting stents

Answer 39

DAPT - aspirin plus an anti-platelet or anti-clotting drugs such as clopidogrel or ticagrelor. This must be continued a long time after the stent is inserted up to 1 year after stenting

Question 40

What are the additional benefits of DAPT

Answer 40

Has a pleiotropic effect on the neutrophils and can reduce incidence of subsequent pulmonary infections

Question 41

Draw a diagram depicting and ST elevated ECG trace

Answer 41

See completed diagram below