12-lead ECG

Question 1

Where are the electrodes placed for a 12-lead ECG?

Answer 1

(They will already have their electrodes placed but these will be covered, and you need to indicate where you would put them). You should then attach the appropriate wires.
Limb leads (over bone where possible):  
• right arm (red lead),  
• left arm (yellow lead),  
• left leg (green lead),  
• right leg (black lead)  

Chest leads:
• C1 = 4th intercostal space, right sternal border;
• C2 = 4th intercostal space, left sternal border;
• C3 = half-way between C2 and
• C4; C4 = 5th intercostal space, mid-clavicular line;
• C5 = anterior axillary line at the same horizontal level as C4;
• C6 = mid-axillary line at the same horizontal level as C4 and C5.

Question 2

Equipment

Answer 2

• ECG machine
• Limb leads
• Chest leads
• Disposable electrodes (blue ones)
• Wipes

Question 3

What do the chest leads look at?

Answer 3

Anterior, lateral and occasionally posterior aspects of the heart in a horizontal plane.
C1/2 - right ventricle.
C3/4 - interventricular septum & anterior wall of LV.
C5/6 - anterior & lateral walls of LV

Question 4

What do the limb leads look at?

Answer 4

Inferior and lateral aspects of the heart in a vertical plane.
3 electrodes but 6 directions of view:
- I, II and aVL - LHS heart
- III and aVF - inferior surface of heart
- aVR - right atrium

Question 5

What size are the squares on the ECG paper?

Answer 5

25mm per second

Question 6

Health and safety

Answer 6

Ensure that the equipment is in good working order and has been regularly
checked.
Do not place any fluids on the machine.
Ensure that the patient is safely positioned on bed/couch and at a correct
height for the operator.
Use a new set of disposable electrodes for each patient.
If any faults are
detected they should be reported to the relevant depart as soon as possible.

Question 7

Performance of task

Answer 7

• Gather equipment
• Draw curtains (state)
• Wash hands
• Request the patient removes clothing from upper half of body and trousers rolled up (bras can stay on). Tights and socks removed. (state this)
• Ensure patient is lying comfortably (ask) - ideally supine position
• Ensure skin is dry (not greasy). Shave areas if necessary (state)
• Clean sites with an alcohol swab (state)
• Check for known allergies to the stickers
• Apply electrode accurately (smooth down adhesive) INDICATE ON DIAGRAM
• Connect leads to tabs on the electrodes correctly (for leg leads it is important for the tab to be uppermost to prevent slips) ON PATIENT
• Ask patient to relax and breathe normally and lie still without talking
• Switch on machine and follow instructions on the top
• Check the standard machine settings - speed 25mm/sec, calibration 10mm/mv, AUTO setting (and if required, choose lead II as the monitoring lead).
• Check the leads are all secure then press start
• Obtain ECG
• Check ECG for artefacts & repeat if needed
• Remove the leads and then the electrodes carefully (state you would do this)
• Correctly label the ECG with the patient’s name, number and time/date of recording (state that you would do this)
• Record if there were any problems (state that you would do this)

Question 8

Aftercare

Answer 8

• Ensure patient is comfortable/ok
• Allow them time to redress
• Thank patient
• Check and switch off the machine
• Wash hands

Question 9

How would you inform the patient about the procedure?

Answer 9

‘This ECG will look at the electrical activity of your heart. I am going to attach some stickers to your chest, arms and legs, these will then attach to some leads which will attach to a machine. We will then take a recording of your heart. I will need to expose your chest if that is ok? And would you like a chaperone? I will also need to have access to your ankles, is that ok? You shouldn’t feel any pain’

Question 10

Complications

Answer 10

Redness/itching around electrode site

Question 11

Allergies

Answer 11

Check allergy to stickers