Chest pains

Question 1

Risk factors for MI

Answer 1

Diabetes

High blood pressure

High weight

High cholesterol/ triglycerides

Question 2

What are the steps of investigating cause of chest pain?

Answer 2

Triage nurse determines the severity of condition

Attending A&E doctor does full work on the patient to determine the underlying cause

Question 3

What happens to the patients in the resuscitation unit?

Answer 3

Attached to cardiac monitor - able to observe patient continuously

IV access

FBC, blood glucose, urea and electrolytes, lipids, ALT, AST and troponin

ECG - look at dynamic changes, indicating acute ischaemia.

Chest X-ray - to rule out other pathologies

Question 4

What is an important marker for MI?

Answer 4

Troponin

Question 5

In what other conditions are troponin levels elevated?

Answer 5

Heart failure

Renal failure

Pericarditis

Question 6

What happens if the ECG shows ST elevation?

Answer 6

The patient would need urgent assessment by the cardiologist

Transfer to the CATH lab

For percutaneous coronary intervention

To unblock the affected artery

Question 7

What is the treatment for suspected coronary syndrome?

Answer 7

ROMANCE

Question 8

What does ROMANCE stand for?

Answer 8

Reassurance

Oxygen

Morphine

Aspirin

Nitrates

Clopidogrel

Emoxiprin (low molecular weight heparin)

Question 9

What is the effect of nitrates?

Answer 9

Release nitric oxide

Induce vasodilation

Question 10

What is the effect of clopiodogrel?

Answer 10

Antiplatelet agent used to inhibit blood clots in coronary artery disease

Inhibits purinergic P2y receptors

Question 11

What are the steps to determine the type of chest pain the patient is experiencing?

Answer 11

SOCRATES

S - site (where?)
O - onset (is it constant, does it get better?)
C - character (is it sharp, dull or grabbing?)
R - radiation (does the pain permeate anywhere else in the body?)
A - associated symptoms (shortness of breath, palpitation, lightheadedness and syncope)
T - time (does the pain stay and go, is it constant, how long does it last?)
E - Exacerbating and alleviating (is it positional?)
S - severity (how bad is the pain from 1-10?)

Question 12

Why is SOCRATES important?

Answer 12

Knowing these factors about the pain will allow appropriate diagnosis

Question 13

What are possible causes of pain in the chest area?

Answer 13

Acute coronary syndrome

Pneumothorax - most important to exclude

Pulmonary embolism

Aortic dissection

Gastro-oesophageal reflux

Anxiety

Inflammation of rib joint and muscle injuries

Question 14

What does ACS cause chest pains?

Answer 14

Causes chest pains due to significant blockage of the coronary arteries

Question 15

Why does pneumothorax cause chest pains?

Answer 15

Air leaks in space between lung and chest wall causing them to collapse

Chest x-ray needs to be done when patient enters A&E to rule this out

Question 16

What two tests are essential in the diagnosis of ACS?

Answer 16

ECG

Troponin levels

Question 17

What is a STEMI?

Answer 17

ST segment elevation myocardial infarction

Most severe type of MI

Long interruption of the heart’s blood supply

Extensive damage to a large area of the myocardium

Question 18

What is a NSTEMI?

Answer 18

Non-ST segment elevation myocardial infarction

An NSTEMI results from a partial interruption of blood supply to the heart

Smaller region of damage to the myocardium compared to STEMI

ST depression or T wave inversion

Question 19

What is an unstable angina?

Answer 19

Least serious form of ACS

Still a medical emergency

Blood supply is seriously restricted

There is no permanent damage to the myocardium

Negative troponin levels but may have some changes to the ECG

Question 20

What are the three types of ACS?

Answer 20

STEMI

NSTEMI

Unstable angina

Question 21

What are the two main diagnostic tests for acute MI?

Answer 21

12-lead ECG

Troponin

Question 22

When should the ECG performed?

Answer 22

Within 10 minutes of being admitted to hospital with chest pains

Provides key information to help confirm what level and type of damage has been inflected upon the myocardium

Question 23

What is troponin used for?

Answer 23

Primary test to look for myocyte damage/ death

To confirm diagnosis

Question 24

When should troponin be measured?

Answer 24

High sensitivity troponin test can detect raised troponin 3 hours after onset of chest pain

Question 25

Where are the leads in a 12-limb ECG placed?

Answer 25

6 on the chest One on each limb

Question 26

How many leads make up the 12-lead ECG?

Answer 26

10 Obtain 12 electrical views of the heart

Question 27

Why is it important to place the leads correctly?

Answer 27

Angles at which the electrodes look at the heart and the direction of the heart's electrical depolarisation Important to place leads accurately so the tracing is accurate

Question 28

Which are the limb leads?

Answer 28

aVR aVL aVF

Question 29

Which are the chest leads?

Answer 29

V1-V6

Question 30

What does lead II indicate?

Answer 30

Rhythm strip Shows trends in heart rate and basic rhythm

Question 31

Why is it important to understand which lead corresponds to which position?

Answer 31

In order to localise the pathology to a particular heart region

Question 32

What does ST elevation in V3 and V4 indicate?

Answer 32

Anterior MI

Question 33

What does ST elevation in V2, V3 and aVF indicate?

Answer 33

Inferior MI

Question 34

What does ST elevation in V1, aVL, V5 and V6 indicate?

Answer 34

Lateral MI

Question 35

What does ST elevation in V1 and V2 indicate?

Answer 35

Septal MI

Question 36

Anterior MI

Answer 36

ST elevation in V3 and V4

Question 37

Inferior MI

Answer 37

ST elevation in V2, V3 and aVF

Question 38

Lateral MI

Answer 38

ST elevation in V1, aVL, V5 and V6

Question 39

Septal MI

Answer 39

ST elevation in V1 and V2

Question 40

What does the P wave indicate?

Answer 40

Atrial depolarisation

Question 41

What does the QRS complex indicate?

Answer 41

Ventricular depolarisation

Question 42

What does the PR interval indicate?

Answer 42

Time interval between the first deflection of the P wave and the first deflection of the QRS complex Transit time for the electrical signal to travel from the SAN to the ventricles

Question 43

What does the T wave represent?

Answer 43

Ventricular repolarisation

Question 44

What does the ST segment represent?

Answer 44

Period of zero potential between ventricular depolarisation and repolarisation Provides information about the blood supply to the heart If elevated = blood supply is significantly compromised

Question 45

When is ST elevation significant?

Answer 45

When there is more that 1 mm elevation from the baseline in at least 2 adjacent limb leads Or more than 2 mm of elevation in 2 adjacent chest leads Or a new onset left bundle branch block

Question 46

What are characteristics of the ECG in NSTEMI?

Answer 46

Lack specificity Must be interpreted within the context of the clinical scenario Pathological Q wave - indicate MI has happened at some point

Question 47

Characteristics of pathological Q waves

Answer 47

Downward deflection wider than 2 small squares or greater in height than 1/3 of the subsequent T wave

Question 48

How long do pathological Q waves take to develop?

Answer 48

Takes hours to develop

Question 49

How long do pathological Q waves last?

Answer 49

Rarely goes away once developed

Question 50

Absence of pathological Q wave means that MI has not happened TRUE or FALSE

Answer 50

FALSE Absence of pathological Q wave does not eliminate the diagnosis of MI

Question 51

What happens if MI is suspected in patient?

Answer 51

MI is medical emergency When suspected in patient, initial treatment will begin before some tests are carried out to confirm diagnosis

Question 52

What are tests used for diagnosis and monitoring?

Answer 52

Troponin FBC Arterial blood gases Renal function Blood glucose

Question 53

Why is a FBC ordered in MI patients?

Answer 53

Anaemia may precipitate an MI in angina patients

Question 54

Why are arterial blood gases measured in MI patients?

Answer 54

Determine levels of - hypoxia - pH - lactate - glucose - haemoglobin

Question 55

Why are renal function tests ordered in MI patients?

Answer 55

Urea and electrolytes may be dysregulated or worsen due to poor renal perfusion in cardiogenic shock Hypokalaemia may predispose to arrhythmias

Question 56

Why is blood glucose measured in MI patients?

Answer 56

Diabetes must be controlled aggressively after an MI With intravenous insulin infusions

Question 57

What happens after diagnosis of MI?

Answer 57

Admission to cardiac care units Treatments given

Question 58

What causes ST elevation?

Answer 58

Total occlusion of the coronary circulation supplying an area of the heart causes necrosis of the whole wall of the heart This causes the area to depolarise as the ion movements cannot be controlled Electrodes measure the movement of electricity through the heart Depolarisation of the necrosed area travels to the neighbouring areas of the heart This is picked up by the electrodes and causes a negative deflection of the baseline of the ECG rather than a true baseline When positive vector travels away from the electrode it is represented as a negative deflection on the ECG During ST it is back to true baseline - but this is perceived as elevated as initially the potential is affected by the necrosed area

Question 59

Differences in affected areas of the heart in STEMI and NSTEMI

Answer 59

STEMI - transmural infarct NSTEMI - subendocardial infarct as most distal to coronary arteries

Question 60

How can we differentiate NSTEMI from unstable angina?

Answer 60

Cardiac markers Troponin is positive in NSTEMI due to infarct but negative in unstable angina due to ischaemia

Question 61

What is the reason behind the positive deflection in NSTEMI?

Answer 61

NSTEMI is also characterised by infarct area This is depolarised This time the positive vector is travelling towards the electrode This results in positive deflection in the ECG Causes an abnormal positive baseline compared to true baseline So the ST segment reflecting a voltage of 0 appears depressed

Question 62

Why are ST changes acute?

Answer 62

ST changes are acute and disappear over time Infarct tissue Fibrosis does not have ionic leakage as in infarct tissue So there is no baseline shift