PBL 5 - Angina + Myocardial Infarction

Question 1

Explain exactly what is meant by ‘acute myocardial infarction’ (AMI) (1 mark)

Answer 1

A coronary artery becomes blocked by a thrombus (1/2 mark), causing death (necrosis) (1/2 mark) from ischaemia to some part of the myocardium.

Question 2

Describe three typical characteristics of the chest pain experienced by someone experiencing an AMI (3 marks)

Answer 2

Intense and unremitting for 30-60 minutes

2) Retrosternal and often radiates up to the neck, shoulder, and jaw and down to the ulnar aspect of the left arm
3) Usually described as a pressure sensation that also may be characterized as squeezing, aching, burning, or even sharp
4) In some patients, the symptom is epigastric, with a feeling of indigestion or of fullness and gas

Question 3

In the context of myocardial infarction, what do the terms STEMI and nonSTEMI stand for?

Answer 3

STEMI means ST elevation myocardial infarction (1/2 mark) , nonSTEMI is no ST elevation myocardial infarction (1/2 mark)

Question 4

4. What is the significance of a new Q wave in the ECG of a person suffering from a myocardial infarction ? (1 mark)

Answer 4

A new Q wave indicates there is a zone of myocardium that has undergone irreversible damage.

Question 5

5. Which two classes of enzymes would be measured in the blood on a patient with a suspected AMI? (2 marks) Explain the difference in the time course of the changes in these two enzymes (2 marks)

Answer 5

MB subtype of the enzyme creatine kinase: (1 mark: ½ mark for creatine kinase) CK-MB levels increase within 3-12 hours of the onset of chest pain (1/2 mark) , and return to baseline after 48-72 hours (1/2 mark)

Cardiac troponins T (1/2 mark) and I (1/2 mark) The cardiac troponins are released within 4–6 hours of an attack of MI (1/2 mark) and remain elevated for up to 2 weeks (1/2 mark)
 
 

Question 6

What is the main difference between stable and unstable angina

Answer 6

In stable angina symptoms only appear during exercise or exertion. (1 mark).

Question 7

What does a raised C-reactive protein level indicate? (

Answer 7

It is a blood marker for inflammation OR it is a marker for increased heart disease risk

Question 8

Explain the difference between dyspnea and orthopnea (

Answer 8

Dyspnea is painful or difficult breathing. (1/2 mark). Orthopnea is difficulty breathing when lying down. (1/2 mark)

Question 9

Explain why Mr O’Conlan has pains in his left upper arm. (

Answer 9

Pain fibres from the heart converge in the spinal cord with pain fibres from the arm and neck (1 mark). Because we have no sensory map of the inside of our body when either set are active the person will feel pain in the arm or neck (1 mark)

Question 10

Apart from calcium channel blockers and aspirin, List the three other drug types most commonly used to treat angina and explain briefly how each one works (3 marks)

Answer 10

Nitrates (1/2 mark) ; eg glyceryl trinitrate (nitroglycerin, GTN)
These drugs release nitric oxide causing coronary vasodilatation (1/2 mark) (and opening of collateral vessels)
Beta-blockers; eg atenolol, metoprolol, propranolol. (1/2 mark)
These drugs have negative inotropic and chronotropic effects due to competitive blockade of cardiac beta-receptors. (1/2 mark)
ACE inhibitors eg captopril (1/2 mark)
Vasodilators that relax coronary vascular smooth muscle by blocking conversion of angiotension 1 to angiotensin 2. (1/2 mark)

Question 11

List four major reversible risk factors for angina

Answer 11

Smoking, Hypertension, Hyperlipidaemia, Obesity, Physical inactivity

Question 12

Define the terms tachypnea and dyspnea (2)

Answer 12

Tachypnoea – Abnormally rapid breathing >16 breaths per minute
Dyspnoea – Difficult or laboured breathing

Question 13

What causes angina (1)

Answer 13

insufficient blood supply to the myocardium leading to ischaemia
Usually atherosclerosis with a narrowed lumen (as you exercise the demand increases to flow isn’t sufficient)

Question 14

What are risk factors for angina – reversible and irreversible? (4)

Answer 14

Reversible - Diabetes, obesity, poor diet, hypertension

Irreversible - Age, male, ethnicity, family history

Question 15

What changes on the ECG can be seen during the exercise stress test? (2)

Answer 15

ST depression
T wave inversion
Pathological Q waves

Question 16

What is the action of Aspirin, calcium antagonists and statins + why is he given these? (3)

Answer 16

Aspirin - COX 1 + 2 inhibitors, anti platelet (blocks thromboxane) decreases probability of vlot forming
Calcium channel antagonist - Amlodipene, diltiazem, verapamil, Causes systemic and coronary vasodilation with negative ionotropic effects for diltiazem and verapamil. Inhibits ca mediated muscle contraction
Statins - Competitive inhibitor of HMG CoA reductase - inhibits formation of excess cholesterol in the blood –> reduces the growth of the atheroma

Question 17

What 2 other drug treatments could he be given and what is the mechanism of these? (2)

Answer 17

BB - atenolol, propanolol, negatively ionotropic and chronotropic
Nitrates - Glyceryl trinitrate given sublingually, causes coronary vasodilation by an action on the vascular smooth muscle

Question 18

How do you diagnose a AMI? (2)

Answer 18

ECG
	ST elevation – In 2 or more adjacent ECG leads 
	T wave inversion
	Pathological Q waves- dead zone of myocardium --> irreversible 
Cardiac enzymes
-C reactive protein
-Troponin
-Creatine kinase
- AST
- Lactate dehydrogenase 
- Myoglobin

Question 19

How do you treat STEMI? (2)

Answer 19

Oxygen
Aspirin
Pain relief 
Percutaneous coronary intervention 
Thrombolytics

Question 20

What is reperfusion therapy? (2)

Answer 20

Thrombolytics
and surgery (PCI)
combined to treat STEMI

Question 21

How do you treat NSTEMI? (2)

Answer 21

Aspirin
Clipidogrel
Factor Xa inhibitor

Question 22

Why would you give streptokinase? (1)

Answer 22

To break down fibrin directly

TPA

Question 23

What complications can occur after an AMI? (3)

Answer 23

Afib
2nd MI
Heart failure
Mitral regurgitation

Question 24

How can a MI patient be managed? (2)

Answer 24

Aspirin for a year

Question 25

What medications must a MI patient have on discharge? (2)

Answer 25

Aspirin
Beta-blocker
In most cases an angiotensin converting enzyme inhibitor
In those with an elevated cholesterol a statin
They should understand the reasons underlying the prescription of these drugs and the
need for long-term treatment

Question 26

What is coronary rehabilitation? (2)

Answer 26

Health education

Supervised aerobic exercise

Question 27

How can angina lead to an AMI? (2)

Answer 27

If blood clot grows and blocks the artery

Question 28

Angina symptoms

Answer 28

Crushing pain
Sweating
Fainting
Breathlessness

Question 29

What is the pathophysiology of MI

Answer 29

o Triggering event causes disrupting of unstable atherosclerotic plaque in c.a –> rupture –>clotting cascade –> occlusion of the artery
o Impaired blood flow to heart – ischaemic cascade, heart cells die and do not grow back, collagen scar forms in their place
o Calcium can deposit in the CA and can be detected with CT scans

Question 30

Why can you have diaphoresis in an MI

Answer 30

extreme sweating, light headedness

due to surge of catecholamines from Sns in response to pain

Question 31

What is acute Coronary Syndrome

Answer 31

Unstable angina
NSTEMI
STEMI

Question 32

Pathological Q wave

Answer 32

a dead zone of myocardium that has undergone irreversible damage and
death.