CVS - chest pain and ischaemic heart disease

Question 1

What are potential causes of chest pain?

Answer 1

1. Musculoskeletal pain (ribs and muscles)
2. Pneumonia
3. MI or angina
4. Cholecystitis (gallbladder inflammation)
5. GORD

Question 2

Describe the differences in pain between MI, pericarditis and aortic dissection:

Answer 2

All central pain.

1. Ischaemia - tightening pain
2. Pericarditis - sharp pain
3. Dissection - tearing pain

Question 3

What is the imbalance that leads to ischaemic heart disease?

Answer 3

An imbalance of myocardial oxygen supply and myocardial oxygen demand.

Question 4

What is the direction of coronary blood flow?

Answer 4

Epicardium -> endocardium

Question 5

Which muscle of the heart is most vulnerable to ischaemia?

Answer 5

Sub endocardial muscle

Question 6

What is the most common cause of IHD?

Answer 6

Fixed narrowing of coronary arteries due to atherosclerosis.

Question 7

Where are collateral arteries found in the heart?

Answer 7

There are none between major arteries (they are functional end arteries) but some are found between smaller arteries and arterioles.

Question 8

What two main factors determine myocardial oxygen supply?

Answer 8

1. Coronary blood flow

2. Oxygen carrying capacity of blood

Question 9

What two factors determine coronary blood flow?

Answer 9

1. Perfusion pressure (diastolic BP)

2. Coronary artery resistance

Question 10

What are the three factors that myocardial oxygen demand depend on?

Answer 10

1. Heart rate
2. Wall tension
3. Contractility

Question 11

What determines the wall tension of the heart?

Answer 11

Preload and afterload

Question 12

List some non-modifiable risk factors for coronary artery disease:

Answer 12

1. Increasing age
2. Male gender (females catch-up after menopause)
3. Family history

Question 13

List some modifiable risk factors for coronary artery disease:

Answer 13

1. Hyperlipidaemia
2. Smoking
3. Hypertension (high diastolic or systolic)
4. Diabetes (doubles IHD risk)
5. Lack of exercise
6. Obesity

Question 14

Describe a stable atheromatous plaque:

Answer 14

It has a small necrotic core, thick fibrous cap and so is less likely to rupture.

Question 15

Describe an vulnerable/unstable atheromatous plaque:

Answer 15

It has a large necrotic core, thin fibrous cap and therefore the cap is less likely to rupture.

Question 16

Name three acute coronary syndromes:

Answer 16

Unstable angina, NSTEMI and STEMI.

Question 17

What are typical features of chest pain?

Answer 17

1. Central (sometimes on left or right side)
2. Tightening/ constricting
3. Characteristic pattern of radiation.

Question 18

What coronary pathology can stable plaques cause?

Answer 18

Stable angina

Question 19

What coronary pathology can ruptured plaques cause?

Answer 19

Acute coronary syndromes: unstable angina, NSTEMI and STEMI.

Question 20

What is the difference between stable angina and acute coronary syndromes?

Answer 20

Stable angina has no pain at rest but is precipitated by stress or exertion - which is relived within 5 minutes by nitrates or rest. ACSs have pain at rest or minimal exertion which is not relieved by nitrates and is of longer duration.

Question 21

How does a plaque form a thrombus?

Answer 21

1. Fibrous cap undergoes rupture or fissuring
2. Exposes blood to the thrombogenic material in the necrotic core
3. Platelet ‘clot’ followed by fibrin thrombus.

Question 22

How does sub-endocardial ischaemia present itself on the ECG?

Answer 22

ST segment depression of >1mm.

Question 23

Why is aspirin given for IHD?

Answer 23

It reduces platelet aggregation and therefore reduces thrombus formation.

Question 24

Why are statins given for IHD?

Answer 24

Decrease LDL cholesterl and therefore slow the progression of atherosclerosis and increase the plaque stability.

Question 25

Why are long-lasting (transdermal or oral) nitrates given for IHD?

Answer 25

They cause venodilation and therefore reduce preload (decrease wall tension) and therefore myocardial oxygen demand.

Question 26

Why are calcium channel blockers given for IHD?

Answer 26

They cause peripheral vasodilatation and therefore reduce afterload and therefore myocardial oxygen demand.

Question 27

Why are beta-blockers given for IHD?

Answer 27

They reduce heart rate and contractility and therefore myocardial oxygen demand.

Question 28

List two revascularisation techniques:

Answer 28

1. PCI: percutaneous coronary intervention (angioplasty and stenting) 2. CABG: coronary artery bypass grafting.

Question 29

How is it determined which revascularisation technique is best for a patient?

Answer 29

They undergo coronary angiography which identifies the sites of occlusion. The choice of procedure is influenced by these findings.

Question 30

Which blood vessels are used for graft for CABG?

Answer 30

1. Internal mammary artery (internal thoracic artery) 2. Radial artery 3. Saphenous vein (using reversed segment of vein)

Question 31

What is the difference in blood flow between NSTEMI and STEMI?

Answer 31

NSTEMI blood flow obstruction is typically incomplete whereas STEMI is complete obstruction.

Question 32

How does a STEMI cause ST elevation?

Answer 32

Total occlusion of an artery causes transmural (full-thickness) injury which extends to the sub-epicardial area. ECG leads that face that area

Question 33

How do you localise ST depression?

Answer 33

You can't! Unlike ST elevation it cannot be localised.

Question 34

What are the diagnostic criteria for ST elevation?

Answer 34

Elevation greater than 1 small square in limb leads or 2 small squares in chest leads above the baseline. Seen in two contiguous leads.

Question 35

Why is it important to recognise a STEMI?

Answer 35

90% are due to total occlusion and there if proved benefit from EMERGENCY RE-OPENING of the artery.

Question 36

How can NSTEMIs and unstable angina be differentiated?

Answer 36

No biomarkers (e.g. troponin I) of myocyte necrosis seen in blood test of unstable angina as no myocyte necrosis has occurred.

Question 37

What ECG changes may be seen in unstable angina or NSTEMI?

Answer 37

ST depression in leads facing injured area and/or T wave inversion. ECG may be normal.

Question 38

What clues in the history of a patient with unstable angina MAY enable you to diagnose unstable angina over acute MI?

Answer 38

1. Acute worsening of stable angina 2. Angina at rest 3. Recent onset of new, effort limiting angina. 4. Or the story may be the same as in acute MI.

Question 39

List some examination finding in an acute myocardial infarction:

Answer 39

1. Patient anxious, distressed 2. Sweating, pallor 3. Cold, clammy skin 4. Tachycardia/ arrhythmias (+/-) 5. Low BP (+/-) 6. Signs of heart failure: S3/S4, crackles in lung bases (left ventricular failure).

Question 40

When do troponin levels peak? How long does it take their levels to decline?

Answer 40

Peak: 18-36 hours Decline: slowly, up to 10-14 days

Question 41

When do CK-MB (creatine kinase cardiac isoform) levels peak? How long does it take them to decline? When is it useful to measure?

Answer 41

Peak: 24 hours Decline: back to normal 48-72 hours Uses: when new episode of chest pain occurs within 10 days (troponin levels will be high from previous episode still but CK-MB will have come back down).