Performing a 12 lead Electrocardiogram (ECG) and Interpretation … · 2020. 9. 4. · ECG Electrocardiogram Iso-electric line Base line on ECG recording LAD Left Axis Deviation LBBB

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Performing a 12 lead

Electrocardiogram (ECG) and

Interpretation Including

Common Abnormalities Study Guide

Clinical Skills Teaching & Learning Centre Written by: Clinical Skills Lecturing Team

Reviewed by: Dr David Roberts, MBChB system lead for Cardiovascular

Dr Jamie Fanning, Theme Lead Clinical Examination and Procedural Skills

August 2020

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Contents Glossary ....................................................................................................................................... 4

Learning Objectives ..................................................................................................................... 5

Year 2 ....................................................................................................................................... 5

Year 3 ....................................................................................................................................... 5

Introduction .................................................................................................................................. 6

Relevant Physiology and Surface Anatomy ................................................................................. 8

Positioning the leads ............................................................................................................... 12

History ........................................................................................................................................ 16

Preparation ................................................................................................................................ 18

Equipment .............................................................................................................................. 18

Patient safety .......................................................................................................................... 22

Procedure .................................................................................................................................. 24

Post Procedure .......................................................................................................................... 26

Documentation ........................................................................................................................... 27

Other ECG monitoring ............................................................................................................ 27

Interpretation of a 12 lead ECG ................................................................................................. 29

1. Is the rhythm regular or irregular? .................................................................................... 30

2. Calculate the rate ............................................................................................................. 30

3. Can you identify a P wave? .............................................................................................. 32

4. Is there a QRS after every P wave? And is the PR interval normal and constant? .......... 34

5. Look at the QRS width and amplitude .............................................................................. 35

6. Are there abnormal Q waves? .......................................................................................... 38

7. R wave progression ......................................................................................................... 39

8. Look at the ST segment. .................................................................................................. 40

9. Look at the T waves ......................................................................................................... 42

10. Cardiac Axis: ..................................................................................................................... 42

Alternate Lead positions, and how to print a rhythm strip........................................................... 46

Print a rhythm strip .................................................................................................................. 46

A posterior lead ECG .............................................................................................................. 46

Take a right sided ECG, for dextracardia ................................................................................ 46

Some other considerations ........................................................................................................ 48

Case study and results............................................................................................................... 50

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Cardiac Arrest Rhythms ............................................................................................................. 53

PEA ........................................................................................................................................ 53

Asystole .................................................................................................................................. 54

VF ........................................................................................................................................... 55

Pulseless VT ........................................................................................................................... 56

Bibliography & Further Reading ................................................................................................. 57

Picture Credits ........................................................................................................................... 59

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Glossary

aVF Augmented Vector Foot

aVL Augmented Vector Left

aVR Augmented Vector Right

Aberration Aberration (aberrant conduction) is conduction of the

supraventricular impulse to the ventricles in a markedly different

manner from the usual conduction. Aberration is seen as bundle

branch block pattern (wide QRS complex).

ACS Acute coronary syndrome

AVN Atrio-ventricular node

Bpm Beats per minute

Bipolar Leads Leads that utilize a single positive and a single negative electrode

between which electrical potentials are measured.

Broad complex rhythm Rhythm with prolonged QRS

CSTLC Clinical Skills Teaching and Learning Centre

Depolarisation Loss of the difference in charge between the inside and outside of

the plasma membrane of a muscle due to a change in permeability

and migration of sodium ions to the inside of cells, resulting in a

more positive internal charge

ECG Electrocardiogram

Iso-electric line Base line on ECG recording

LAD Left Axis Deviation

LBBB Left bundle branch block

MI Myocardial Infarction

mV Millivolt

Narrow Complex Rhythm Rhythm with a normal QRS

Negative Deflection ECG trace is below the iso-electric line

Positive Deflection ECG trace is above the iso-electric line

PVC Premature ventricular contraction or ventricular ectopic

RBBB Right bundle branch block

Repolarisation After depolarisation, the increased positive charge within the cell

now causes the potassium channels to open, as potassium moves

out of the cell the potential within the cell decreases and approaches

its resting potential once more.

SAN Sino-atrial node

A sinus beat 1 cycle of normal electrical cardiac activity

Unipolar Leads There is a single positive electrode that is referenced against a

combination of the other limb electrodes

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Learning Objectives

Year 2

To understand reasons for recording ECG

To understand the electrophysiology of the heart

To link electrophysiology to practical skill

To be able to carry out ECG recording

To be able to carry out basic ECG interpretation

Year 3

To be able to interpret and recognise some abnormal rhythms

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Introduction

An electrocardiogram (ECG) is a simple test that is used to check the rhythm and electrical

activity of the heart. Small electrodes are attached to the skin of a patient and then wires are

attached to a machine, the electrical signals from the heart are recorded onto a piece of paper

or projected onto a screen, this allows you to interpret if there are any abnormalities in the

heart’s electrical activity. Please be aware that the heart can emit electrical activity which would

show on an ECG, but may not be mechanically functioning, always check the patient before you

review the ECG monitor or trace.

The patient’s history will normally be taken prior to taking an ECG, this could be a short focused

history or a full history depending on clinical need eg; if the patient has cardiac sounding chest

pain, a short focused history prior to ECG would be advised, followed by a full history.

Indications for a 12 lead ECG.

There are many indications for performing a 12 lead ECG.

The ECG may be done in isolation but is normally done with an examination and for any of the

following reasons:

Chest Pain

Shortness of breath

Palpitations

Loss of consciousness

Acutely unwell patients, post cardiac arrest, electrolyte imbalances etc.

Trauma/ or electrocution

Routine/ Occupational Health

Pre-operative

In a patient with acute cardiac chest pain please be aware that an ECG is a priority and should

be done as soon as possible in hospital. Out of hospital an ECG should be done as soon as

possible, but without delaying a patient’s trip to a hospital (NICE 2016 Clinical guideline CG95).

Any transient loss of consciousness – (NICE Clinical guideline CG109) requires an ECG to be

performed as soon as possible, any history of falls, abnormal electrolytes, overdose or any

patient with an abnormal heart rate also require a 12 lead ECG. This list is not exhaustive and

clinical judgement should also come into consideration.

A normal ECG

Below are examples of a normal ECG from the machine at CSTLC, two pages are printed out

(Fig. 1) please bear in mind that the layout may vary from trust to trust, so you must ensure that

you know which trace is related to which lead.

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Figure 1

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Relevant Physiology and Surface Anatomy

All heart muscle is capable of conducting an electrical impulse and initiating a spontaneous

electrical discharge. The 12 lead ECG records electrical activity (not mechanical function) from

the heart as waveforms. The 12 lead records information from 12 different perspectives. The

image in Fig. 2 shows the electrical events of a single cardiac cycle and how they are

represented on ECG paper. Always look at the patient prior to interpreting the ECG.

If you imagine that the ECG paper is a graph, and the horizontal axis is time and vertical is

amplitude.

Figure 2

1 cycle of electrical cardiac activity (single sinus beat) recorded from

Lead II in a healthy volunteer.

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Iso- electric line

Firstly, if you monitor the myocardial

cells that are polarised or in a ready

state, they will produce a line on the

paper, this is called the iso-electric line

(Fig. 3) or base line, this line

represents the resting potential of the

heart. The electrical events of the

cardiac cycle will be represented by

deflections away from this line, as the

cells depolarise and repolarise (see

glossary) they cause deflections above

and below this line.

Something to bear in mind, in theory this line should be straight however when you are

recording the ECG of a patient they have impulses through other muscles such as the

intercostal muscles for breathing so this base line may move slightly up or down like a rolling

wave.

How the ECG trace represents the electrical activity of the heart;

Figure 3

Diagram 1

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Below is the electrical representation of the cardiac cycle on a healthy functioning heart:

1. SAN depolarisation, on the iso-electrical line. The events of the cardiac cycle are initiated

by depolarisation of the sino-atrial node, the sino-atrial node is also called the

pacemaker. The initial electrical impulse (depolarisation) usually begins here.

2. Atrial depolarisation (P wave), the wave of electrical depolarisation is conducted through

the cardiac muscle of both atria, this in turn creates a deflection away from the base line

known as the P wave.

3. Atrial Contraction (P wave), the depolarising wave causes

contraction of the atria pushing blood into the ventricles

4. Atrio-ventricular node (AVN) depolarisation (PR interval), the electrical impulse hits the

fibrous septum and cannot be transmitted through this but it reaches the atrio-ventricular

node which will depolarise, at this point the wave is slowed down enabling the ventricles

Diagram 2

Diagram 3

Diagram 4

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to fill. The phase from the initial impulse from the SA node to the AV node depolarising is

called the PR interval.

5. Ventricular depolarisation (QRS complex) as the AV node depolarises the electrical

impulse is conducted down the ventricular conducting tissue, including the bundle of His,

left & right bundle branches. This happens very rapidly and creates the QRS complex on

the ECG which should be thin and needle like.

Q

R

S

Diagram 5

Diagram 6

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The coordinated, synchronised depolarisation produces an effective contraction of both

ventricles.

6. Ventricular repolarisation (T wave), after depolarisation and contraction the ventricles

repolarise, returning to the resting potential, repolarisation needs to take place otherwise

the ventricular cells could not respond to another impulse.. As this takes place it creates

a deflection away from the baseline known as the T wave. As repolarisation takes place

without the use of the Bundle of His etc., repolarisation takes longer.

Positioning the leads

Positioning of the wires provides 12 different views of the heart from 12 different directions,

which enables the clinician to pinpoint the possible sites of any cardiac abnormalities, such as a

Myocardial Infarction.

The positioning of the limb leads:

There are 4 electrodes attached to 4 wires:

Augmented Leads, these are unipolar leads:

aVR (Augmented Vector Right) positioned right arm, the lead

picks up electrical activity moving towards the right shoulder

aVL (Augmented Vector Left) positioned left arm, the lead

picks up electrical activity moving towards the lateral wall of

the left ventricle

aVF (Augmented Vector Foot) is positioned on the left foot, the

lead picks up electrical activity moving towards the inferior wall

of the left ventricle

Neutral is positioned on the right foot, this completes the

electrical circuit but plays no role in the ECG itself.

Despite there only being 3 wires measuring electrical activity the

machine produces 6 traces for the ECG:

Bipolar Limb Leads are created by measuring the electrical potential between 2 unipolar leads:

Lead I, measures the electrical potential from the left arm across to the right arm (lateral

wall of the left ventricle)

Figure 4

Diagram 7

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Lead II measures the electrical potential between the left leg and the right arm (inferior


Lead III measures the electrical potential between the left leg and the left arm (inferior


All the limb leads view the electrical activity along a single plane, known as the Frontal plane.

Leads I II & III are known as Einthoven’s Triangle.

Fig. 5 depicts how the limb leads view the heart

Please note

the depicted

sinus beat for

each image

appears

different as

the current

generated

moves in a

different

direction in

each image.

The blue lines in the top 3 figures above show which leads the electrical potential is measured

from, the red line shows the direction in which the current flows.

Positive and Negative Deflections

Positive deflections above the iso-electrical line mean the electricity is flowing towards that lead

from the heart, whilst negative deflections below the iso-electrical line mean the electricity is

flowing away from that lead through the heart (Figure 6)

Figure 5

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Figure 6

The Chest Lead positions

Six electrodes placed on the chest wall provide six views of the heart from the front and around

the side

These leads are named V1, V2, V3, V4, V5, & V6, each lead generates a different view of the

heart (see Fig.59). The electrodes should be accurately placed to ensure the correct view as

incorrect placement of wires may result in a misdiagnosis when interpreted later:

Figure 7

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This is another way of showing the directions of the electrical currents recorded by the 12 lead

ECG.

Figure 8

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History

Prior to any clinical examination or procedure a detailed history should be taken from the

patient, this will enable you to tailor the examination to the patient’s presenting complaint and

additional symptoms the patient may elude to when you elicit a full history. For guidance on

history taking please see MBCHB students – Year 2 – History taking.

There are several indications for a performing an ECG, you will need to take a full history and

focus to gain clinical diagnostic reasoning and interpret the ECG.

Taking a focused history will aid reasoning

Consider:

History of presenting complaint:

A description of symptoms, noting the colour of the patient and their vital signs. An

ABCDE assessment may be required.

How and when it started, eg: after exercise or at rest.

Course and pattern of symptoms over time

Pain- consider SOCRATES

Effect on patient

Previous experience of the same or similar

Other relevant symptoms, eg; shortness of breath, tingling, pain or numbness to arm or

jaw, vomiting or nausea, history of collapse.

Past Medical History

Make a note of previous related medical problems including surgery, eg cardiothoracic or

trauma.

Medication history

Ask about medications, and compliance of use, especially consider aspirin or anti-

coagulants

Discuss allergies

Social history

Ask the patient about lifestyle/ work

Be clear about alcohol consumption, smoking history and illicit drug use.

Family history

This should cover all serious medical conditions

Beware of congenital heart disease, bleeding disorders, stroke, or heart attacks, etc.

Review of Systems

Consider tiredness/ malaise

Seizure/ collapse or frequent falls

Shortness of breath

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An 79 year old patient attends AED with a history of dizziness, worse when bending

down

Presenting

Complaint

Patient noticed increased dizziness over last few weeks, it is worse

when he bends down to pick up the post. No history of trauma/ pain,

although his neighbour said that his pulse felt slow, she is a health care

assistant and told him to go to AE.

Past Medical History Normally fairly well, GP had given him some pain killers for a sore knee

but he thinks that is just arthritis.

Family History Nil to note

Social History Retired but active

Review of Systems Maybe slightly short of breath walking up stairs, but nothing too bad.

On examination:

General inspection Looks fairly well, if slightly pale

Tests to consider 1. Vital signs

2. ECG

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Preparation

Equipment ECG machine

Hard surface wipes

Alcohol wipes eg. Sterets®

Disposable razor

Sharps bin

Clinical waste bin

Spare paper

Spare ECG clips

Electrodes

ECG machines:

ECG machines, clips and electrodes come in different

makes and models and with different lead colours,

please follow the Trust and Manufacturer guidelines.

Most ECG machines perform better if they are plugged

in for the procedure but can be done on their battery

supply.

If you have a screen, please ensure the electronic trace

on screen is straight before printing.

An ECG print out will produce evidence of calibration on the trace, this should be confirmed, see

Fig. 11, if the machine does not show this, the machine needs to be changed as it cannot be

relied upon to produce an accurate ECG.

A normal paper speed is 25mm/s, see Fig. 11 a machine can be set slower (eg 50mm/s) to view

each complex in more detail, however, for interpretation

the paper speed should be set to 25mm/s, so please

check the machine prior to recording the ECG. The

correct voltage gain (10mm/mV, on print out next to

speed) should be used to record the ECG, but the voltage

can be increased where the complexes are small, ensure

this is documented.

Figure 9

Figure 10

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For a normal ECG with no highlights: please see Figure 1.

Figure 11

The CSTLC has small, portable devices that are available in The Learning Zone (Fig. 10);

Please be aware of the buttons you may use, see Fig. 12.

Figure 12

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Hard surface wipes:

Use these to wipe the machine and the leads, to reduce the spread of infection

Alcohol wipes eg. Sterets®:

Some places use these occasionally to clean the skin, however soap and water is

recommended

Disposable razor and sharps bin:

You may need to shave excess chest hair, and the razor should go into a sharps bin.

ECG tabs, electrodes or stickers

As muscles produce electrical currents it is advisable to adhere the electrodes of the limb leads

to bony prominences where there is reduced muscle bulk, therefore reducing interference. The

usual placement of the limb electrodes will be the medial malleolus and the radial head.

However, there may be occasions where an area more proximal is used, for example when

patients have a fine tremor, or limb amputations. Different areas/ trusts will use different

electrodes or tabs, please make sure that you are familiar with the equipment used in the

clinical area that you are in, some types of electrodes are shown in Fig. 13

Figure 13

The 12 lead ECG electrodes attach differently depending on the electrodes available.

Please ensure good contact Fig. 13-17 otherwise the ECG will not give an accurate trace.

Consider that patients with hairy chests may require hair removal in order for the electrodes to

have good skin contact

Figure 14 Figure 15

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Please note if electrodes in Fig. 16 &

17 are used, the electrodes need to

be connected to the wires prior to

sticking them on the patient,

otherwise this is very uncomfortable

for the patient

Figure 15

Figure 16

Figure 17

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Subsequent or serial ECGs may be required especially in patients with acute coronary

syndromes, and especially those with current chest pain. It may be appropriate to inform the

patient that another of the ECG’s will or may be done in 30 minutes time and that the stickers

would remain in situ in order to repeat the ECG using the same view.

Do remember that these electrodes need removing, and a plan should be formulated to ensure

that all are removed. Electrodes can cause skin irritation in some patients and in these cases

should not be left on, check the patient’s allergies and enquire after any known skin conditions

when gaining informed consent, e.g. psoriasis can be exacerbated on removal of electrodes,

and gentle removal may be required with the re application of a prescribed cream. The patient

should be encouraged to immediately inform a member of staff if they become itchy or sore

from the electrodes. An example of a skin condition is in Fig 18. If the patent has allergies seek

advice from your supervisor before performing the ECG, without delaying assessment.

Figure 18

Patient safety

Introduce yourself

Check the patient’s identity and allergies

Explain what you want to do

Gain informed consent

Consider an appropriate chaperone

Adequate exposure maintaining dignity

Position the patient appropriately – consider moving and handling

Wear Personal Protective Equipment as required.

Wash your hands before and after you touch the patient (as per WHO guidelines)

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1. On first meeting a patient introduce yourself, confirm that you have the correct patient

with the name and date of birth, if available please check this with the name band, written

documentation and the NHS/ hospital number/ first line of address. You will then need to

input the patient data into the machine, check spellings are correct.

2. Check the patient’s allergy status, being aware of the electrodes that you will be using in

this skill.

3. Ensure the procedure is explained to the patient in terms that they understand, including

explanation of how long this procedure will take, gain informed consent and ensure that

you are supervised, with a chaperone available. Patients will need to be fully undressed

from the waist up, including the removal of bras, if applicable, they need to be fully

informed before you start this procedure.

4. You may explain to the patient that “I will apply several stickers to your arms, chest and

legs, which will connect to wires that monitor (not deliver) electricity and they will give a

print out from your heart, you will need to keep as still as you can but it should take less

than 5 minutes.” The patient needs to stay still whilst the ECG is capturing, talking will

affect the trace

5. The patient should be completely undressed from the waist up including underwear and

at the position of 45 degrees (Campbell et al 2017). The patient needs to be informed

that once the electrodes and leads are on, they can be covered to maintain dignity.

Breast tissue can impede finding the correct landmarks, it may be appropriate to apply

electrodes over breast tissue or under breast tissue. Always ensure that electrodes are

facing the chest wall and not the underside of breast tissue, as this will give inaccurate

results.

6. If the patient has a particularly hairy chest, they may require shaving with a single use

disposable razor (or follow Trust guidelines, remembering a sharps bin) and this should

be included when obtaining consent.

7. If the patient is using emollients, oils or skin creams, these will need to be removed

before attempting to put the stickers in place. Campbell et al (2017) recommend soap

and water and/ or careful exfoliation with a paper towel or gauze. Alcohol wipes were

used in the past and you may see this occasionally in practice. Patients with skin

conditions may have increased sensitivity to the ECG electrodes or alcohol wipes, please

be mindful.

8. Don personal protective equipment as required, especially if you are likely to come into

contact with bodily fluids. Be aware of hand hygiene and preventing the spread of

disease, WHO (2009).

9. Please adhere to infection control requirements, do not let the ECG wires trail on the

floor and return them neatly and untangled back to the machine.

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Procedure

Once you have prepared the patient, the process for capturing an ECG is fairly simple.

Each ECG machine is different, however the principles are the same. Fig 12 shows the buttons

required to perform the ECG:

Turn on the machine once leads are connected

If you have the option of inserting patient details electronically, do so

Ensure the speed and voltage is correct

If you can see an electronic trace on the screen wait until the trace is straight, remind the

patient to stay still

Press auto start, ensuring that your patient remains still

The ECG will print out.

Considerations/ tips to get the best possible trace:

1. If the patient’s skin is damp:

The electrodes may not stick if the patient is wet,

clammy or sweaty, the patient may require drying

first, or skin preparation. Try to attach the limb

wires first as these often adhere better than the

chest leads, do the chest leads last. If the wires

are twisted they can pull on the electrode stickers

(Fig.19), you can twist the ECG clips to help

reduce this (Fig.20).

2. Avoid inaccuracy of lead placement:

Misplaced wires can provide inaccurate ECGs, for

example leads V4, 5 and 6 if placed in the wrong

order could indicate that the patient is experiencing

an ischaemic event. The wires are colour coded or

labelled, please ensure correct placement.

3. Avoid a wandering base line or a poor trace:

The muscle filter (Fig. 22) on the machine can

distort the ECG, and therefore the ECG should be

performed without the muscle filter. If there is

interference then the filter should then be utilised

and this should be documented (Campbell et al;

SCST 2014). So one ECG should be done without

the filter and then one with the filter. Please see

Fig. 21 for evidence of interference, you may have

to ask the patient to hold their breath for a couple

Figure 19

Figure 20

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of seconds whilst recording, also encourage them to remain as still as they can because

muscle movement will cause interference, also be aware that some electrical devices can

affect the printout such as mobile phones.

Figure 22

Figure 21

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Post Procedure

Following the procedure, ensure that:

ECG is showing a trace on all leads,

all documentation is correct

electrodes are removed, unless serial ECGs are required.

patient is covered and that you have washed your hands.

machine and ECG clips are clean and all waste is disposed of.

machine is turned off and plugged back in.

Finally; always ensure ECGs are seen by your supervisor immediately in case any

immediate treatment is required.

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Documentation

A request form or an electronic request may be required before you perform an ECG.

Be cautious in checking documentation, if any details are inaccurate or omitted the ECG could

be stored under the wrong person and have catastrophic consequences for either patient.

On some machines you will need to input all patient details electronically before you begin.

Documentation that needs to be completed or checked following the procedure:

ensure that you have the right patient,

ensure that the patient’s name, D0B, address and hospital/ NHS number are accurate

before storing or imputing into the machine,

that the date and time are correct on the electronic printout,

ensure that it is documented whether the filter was on /off and if the patient was lying at

anything other than 45 degree angle,

also document whether the speed or voltage were altered or document if lead position

was changed, ie; electrodes attached to shoulder,

document that the ECG has been reviewed and the time of the review.

Other ECG monitoring

Other types of monitoring include 3 or 5 lead ECG monitoring or telemetry, these will project

continually onto a monitor, and can also be printed.

Figure 23

These are different from a 12 lead and they can be static or ambulatory, but tend to provide

continuous monitoring.

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3 lead monitoring

Figure 24

Three leads use 2 bipolar leads for monitoring and 1 electrode for a ground electrode. The

leads can use different configurations to produce a Lead I, II or III trace. Lead II is

predominantly used but this can be changed on the machine to lead I or III

There are several modified leads available, please be aware that there are differing electrode

placements depending on requirements and clinical practice.

5 lead monitoring

This uses 5 electrodes and the monitor can display bipolar leads I, II and II and a single unipolar

lead, giving views of I, II, III, aVR, aVL, aVF and V. 5 lead monitoring is

often used for telemetry or patient portable monitoring.

Figure 25

Portable patient

telemetry monitor

Figure 26

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Interpretation of a 12 lead ECG

Table 1

Waveform Normal Configuration and Duration Physiology

P wave, see figure

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Should be upright and symmetrical in

all leads except AVR and V1, where it

may be inverted. Voltage should be <

3mm, duration < 0.10 sec

Atrial Depolarisation

PR Interval Normally isoelectric. Between 0.12

and 0.2 secs (3-5 small squares)

Start of atrial depolarisation

and ventricular depolarisation

QRS complex, see

figure 27

Duration < 0.12 sec (<3 small

squares) Configuration varies from

lead to lead.

Ventricular depolarisation

ST segment Lies on isoelectric line, Important in

MI diagnosis

Pause in ventricular electrical

activity before repolarisation

T wave Symmetrical, usually no more than

half height of QRS, upright in all leads

except AVR and V1.

Ventricular repolarisation

U wave Often absent. Usually small rounded

deflection occasionally seen after the

T wave. Normally in same direction

as T wave.

Uncertain, can occasionally

indicate arrhythmias/

ischaemia/ hyperkalemia/

Ischaemia. (Goldberger et al

2018)

Figure 27

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Interpretation:

Before interpreting the ECG, your priority is to check the patient, if necessary assessing the

patient using an ABCDE approach. If the patient is showing no signs of life, CPR should be

commenced and when appropriate the cardiac arrest rhythm should be identified. There is a

section on cardiac arrest rhythms at the end of this guide.

For a patient that is breathing and has a pulse, take a systematic approach to interpretation

(Resuscitation Council UK 2015) and note any abnormalities, below is a list of an approach to

take, these will then be discussed in further detail:

1. Is the rhythm regular or irregular?

2. Calculate the rate

3. Can you identify a P wave?

4. Is there a QRS after every P wave? And is the PR interval normal and constant?

5. Look at the QRS width and amplitude.

6. Are there abnormal Q waves?

7. Look at R wave progression

8. Look at the ST segment.

9. Look at the T waves.

10. Look at cardiac axis

1. Is the rhythm regular or irregular? Firstly decide if the rhythm is regular or irregular, do this using the lead II rhythm strip. Mark

distance between QRS complexes on a plain piece of paper, then move the paper to see if

the distance between each QRS is the same, if this is the case the rhythm is regular, if not it

is irregular (Fig.28).

Figure 28

2. Calculate the rate If you imagine that the ECG paper is a graph, and the horizontal axis is time and vertical is

amplitude. For this to work, the amplitude set at 1mv and the paper speed needs to be set

at 25mm/sec:

1 small square = 1mm (0.04 sec)

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1 large square = 5mm (0.2 sec)

5 large squares = 1 sec

300 large squares = 1 min

Please see Fig. 29

This can be used to calculate the heart rate from the ECG (Fig. 1). For regular heart

rates count large squares between QRS complexes and divide into 300, eg; 300/ 5 = 60.

So if the heart is mechanically sound this would generate a heart rate of 60 beats per

minute.

For irregular heart rates count QRS complexes in 30 large squares and multiply by 10.

ECG paper

Figure 29

1 small square

1 large square

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Figure 30

Is the rate between 60 and 100, anything over 100 bpm is a tachycardia anything under

60 bpm is termed a bradycardia?

Tachycardic;

Figure 31

A quick way to assess rate to know if it too fast is to remember that 300 divided by 3

equals 100 so when there is less than 3 large squares between QRS in a regular rhythm

it has to be faster than 100bpm.

Bradycardic;

Figure 32

3. Can you identify a P wave? You may not always be able to see P waves especially with

tachycardia, see figure 31. You will also find that no discernable P waves is a typical

example of atrial fibrillation, normally with an irregular rhythm. See Figure 33.

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Figure 33

Figure 34 is an example of an abnormal ECG where there are multiple P waves, but they are

abnormal or “sawtooth” this is atrial flutter, in which case you may want to note how many P

waves there are compared to QRS, in this case four P waves to each QRS: 4:1.

Figure 34

Also consider the size and shape of the P wave, the amplitude of the P wave should be:

< 2.5mm (0.25mV) in the limb leads

< 1.5mm (0.15mV) in the pre-cordial/ chest leads

Atrial enlargements can widen or increase the amplitude of the P wave, hypokalaemia can

cause an increased amplitude of the P wave and hyperkalaemia can result in decreased

amplitude. Peaked P waves can indicate pulmonary hypertension (cor pulmonale from

chronic respiratory disease).

Some abnormalities can result in a bifurcation of the P wave, known as bifid P waves,

notched P waves or P mitrale, this can be as a result of atrial enlargement secondary to

mitral stenosis

Figure 35

You may also see pacing spikes, if your patient has an internal pace maker, these will appear

as vertical lines on your ECG.

Please note any other abnormalities such as inverted P waves and discuss with your

supervisor.

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4. Is there a QRS after every P wave? And is the PR interval normal and

constant? (see Table 1)

In this example the PR interval is prolonged > 5 small squares, but constant, showing a

consistent delay in the conduction between the SA and AV node. This is known to be 1st

degree heart block, and the patient may have no symptoms.

The PR interval could be prolonged progressively, which culminates in a “dropped QRS”, this

would be 2nd degree heart block, Mobitz type I or Wenckebach, the patient may have no

symptoms and this may be normal for your patient, please see the image below:

Figure 37

The PR interval remains constant with intermittently non conducted P waves resulting a

“dropped QRS”, this is known as 2nd degree heart block; Mobitz type II. Patients presenting

with this are at a greater risk of asystole and the ECG should be discussed with your

supervisor as a priority.

Figure 38

In the example below, the P waves are not followed by QRS, if the SA node was acting as

the pacemaker of the heart the blue shaded area shows where a QRS should occur. There is

no correlation between the P waves and the QRS complexes, suggesting that there is a

complete block between the AVN and the ventricles. This is known as a complete A.V. block

or 3rd degree heart block. The QRS can be broad or narrow depending on where the block is,

if it is lower down the bundle branches the QRS rate will be slower and often broader. A

patient presenting with the trace below is at greater risk of asystole and may be

compromised, they may require immediate intervention, for example external pacing.

Figure 36

35

Figure 39

If the P wave is inverted (on the opposite side of the iso-electric line) and there is a PR

interval ≥ 3 small squares or ≥ 0.12s, then the origin is from the atria and could indicate

ectopic atrial rhythm, if the P wave is inverted in the inferior leads but the PR interval is < 3

small squares or 0.12 s this could indicate the origin is in the AV junction.

Atrial ectopic beats, rarely cause symptoms and can be normal, it is where there is an extra

heartbeat, caused by an abnormal electrical signal to the atria, it is also called an atrial

premature beat or premature atrial contraction.

5. Look at the QRS width and amplitude, it should be measured in the lead with the

widest complexes (Morris 2009), it should be < 0.12 seconds or < 3 small squares, please

see Figure 27 for an example of a normal complex and where to measure from (ie: the first

negative deflection of the Q wave until the S wave returns to the iso-electric line). Once you

are regularly looking at ECG’s, any abnormalities will become more obvious, you should

always have the ECG’s checked by your supervisor.

Not every QRS complex contains a Q, an R and an S wave. Every negative deflection is a Q

wave, and the R wave is the first positive deflection in the complex. The S is the 1st negative

deflection following the R wave.

If there is no Q wave, the complex is called an RS complex and if there is no R wave, it is

called a QS complex. There can only be one Q wave but there can be two R waves or two S

waves, a few of the more common combinations are shown below: a normal QRS, a QS

complex, an rS complex, an RS complex and an RSR complex:

Figure 40

Figure 41 is a regular narrow complex tachycardia, depending on the patient, their history

and their symptoms, intervention may be required, it could be a supra-ventricular

tachycardia (SVT), please check the patient.

36

Figure 41

Complexes > 0.12 seconds or more than 3 small squares (broad) indicate abnormal

ventricular depolarisation e.g. bundle branch block, or an aberrantly conducted ventricular

beat.

A broad regular tachycardic trace is shown below, this is ventricular tachycardia (VT), this could be a life threatening trace please check patient and start CPR if there are no signs of life.

Figure 42

Bundle Branch Block:

Recognising a bundle branch block, identify that the QRS has a prolonged duration of > 0.12

secs (>3 small squares). The origin of the ventricular activity must be supraventricular (with

the exception of ventricular beats). Once you suspect a bundle branch block, there are a

couple of ways to identify which it is:

You can use V1 to differentiate between right and left bundle branch blocks:

If the QRS complex in V1 is mainly negative, suspect Left bundle branch block

(LBBB)

If the QRS complex in V1 is mainly positive suspect Right bundle branch block

(RBBB)

or

You can use a W or an M to differentiate between the left and right bundle branch

block

In LBBB there is a “W” (or QRS complex) pattern in V1 and an “M” pattern (or

RSR complex), in V6,

37

In RBBB the pattern in V1 there is an “M” pattern (or RSR complex), and in V6

there is a “W” pattern (or QRS complex).

Please see the next 2 images:

Left Bundle Branch Block:

Figure 43

Right Bundle Branch Block:

Figure 44

38

The patient may be completely asymptomatic with either of these ECG’s or they may be quite unwell, you would treat the patient according to their presentation. A new myocardial infarction could present with a new LBBB. You may need to compare the ECG with any previous ones.

Premature Ventricular Contraction (PVC) or Ventricular Ectopic:

This can be normal and occur in many patients, it is where there is an extra beat caused by

abnormal electrical signals, originating from the ventricles. Caffeine and lack of sleep are

often causes, but they can be caused by cardiomyopathy or electrolyte imbalances, so you

should speak to your supervisor if you find one on the ECG.

An example of a PVC:

Figure 45

6. Are there abnormal Q waves? A Q wave is any negative deflection

that precedes an R wave. If the first deflection of the QRS is

downwards it is called a Q wave, a small Q wave can be normal,

however they are not if they are;

1. > 2 mm deep or

2. >25% the height of the following R wave in depth or

3. > 0.04 seconds wide

Q waves can indicate a previous, or current myocardial infarction.

Figure 46

Fig.46 and

47; examples

of a Q wave.

Normal Figure 47

39

7. R wave progression

The R wave should progress smoothly from V1 to V6, and the height of the R wave can be

compared to the height (positive deflection of the S wave). At this stage the main reason for

checking the R wave progression is to ensure that there is correct lead placement on the

chest wall.

R wave progression can be checked by looking at the QRS complexes. These should be

mainly negative in V1 and V2 and mainly positive in V5 and V6 (Fig 48). There is a gradual

change through these chest leads. If the change is not a gradual progression, check that the

wires and the wire position are correct, otherwise this could be an ischemic or other cardiac

event, see Fig.49.

Ideally in V4 the R wave should be taller than the S wave as pictured here:

Figure 48

Figure 49

40

8. Look at the ST segment.

ST segment changes can indicate acute myocardial ischaemia, which requires immediate

action, any abnormalities should be discussed with your supervisor.

The ST segment is normally the flat isoelectric segment between the end of the S wave and

the beginning of the T wave (see figure 27).

ST Elevation Myocardial Infarction (STEMI): The patient would normally be obviously unwell

and the ECG would show some acute ST segments elevated above the isoelectric line. ST

elevation can present in many ways, it can be concave, convex or straight.

An example of ST segment elevation is imaged below:

Figure 50

Elevation in leads V1-V4 often indicate a lesion in the left anterior descending (LAD) coronary

artery or an anterior STEMI, if the elevation progresses into V5, V6, I and aVL, or an

anterolateral STEMI.

Elevation in leads II, III and aVF is often caused by a lesion in the right coronary artery, and is

referred to as an Inferior STEMI.

(Treatment may depend on the amount of elevation, eg: > 0.2mV in 2 adjacent chest leads or >

0.1mV in 2 or more adjacent limb leads. )

In ECG’s showing ST segment elevation in some leads, there is often ST depression in the

electrically opposite leads, this is known as reciprocal changes.

The images below show ST segment elevation of > 3mm in leads II, III and aVF, with reciprocal

changes (ST depression) in aVL. These are both images of Inferior STEMI’s:

Figure 51

41

Figure 52

ST Depression:

Do the ST segments sag below the isoelectric line? This is called ST depression, this may be

small, or deeper, this can be a sign of ischaemic changes or a non STEMI. The diagram below

shows a normal complex and a complex with ST depression

Figure 53

See Fig. 54, deep ST depression in leads V1 to V3 of >3mm, this could indicate ischaemia or a

myocardial infarction, the patient would need assessing and the ECG would need to be

reviewed by a senior as a priority.

42

Figure 54

9. Look at the T waves A normal T wave is shown in Figure 27, T waves should be smooth, symmetrical and usually

no more than half height of QRS, upright in all leads except AVR and V1

T wave abnormalities can be due to electrolyte imbalances, ischaemia or toxicities, so you

should have a full patient history and bloods should be sent to support diagnosis.

Look at the T- waves:

1. Are they too tall/ peaked (Fig.55)?

2. Are they too small (Fig. 56, in aVL)?

3. Are they inverted (Fig. 57)?

Figure 55

1. Tall peaked T waves, can be caused by hyperkalaemia or in the early stages of MI

2. Low amplitude T waves can be caused by hypokalaemia, hypocalcaemia or

hypomagnesemia.

3. Inverted T waves can be caused by hypokalaemia or during acute MI of post MI

10. Cardiac Axis: The cardiac axis is the general direction that the wave of depolarisation takes through the

heart. The average overall direction of ventricular depolarisation as seen from the front of

the heart.

Figure 56 Figure 57

43

Figure 58

The image above by Pappano 2019 shows magnitude and direction of the QRS complexes

in limb leads I, II, and III, when the mean electrical axis (θ) is 60 degrees (A), 120 degrees

(B), and 0 degrees (C). LA, left arm connection; LL, left leg connection; RA, right arm

connection. The white areas indicate the projection on the frontal plane of QRS waves in

each limb lead, and the large white arrow shows the resultant electrical axis of the cardiac

vector.

Another way of determining the cardiac axis is:

If the QRS complexes in lead I and II are predominantly positive then cardiac axis is

normal.

If lead I is positive and lead II is negative, this indicates Left Axis Deviation (LAD)

If lead I is negative and lead II is positive this indicates Right Axis Deviation (RAD)

Axis deviation can have numerous causes: it could be normal in obese individuals, or tall,

thin individuals, however it could be as a result of a cardiac or respiratory condition and

should be investigated.

How the leads view the heart

The direction of electrical flow enables us to view the heart from different directions;

V1 & V2 look at the anterior septal wall

V3 & V4 look at the anterior wall of the left ventricle

44

V5 & V6 look at the lateral wall of the left ventricle

II, III and aVF look at the inferior wall (could indicate a lesion in the right coronary artery)

I and/ or aVL look at the lateral wall, occasionally lead I may not be affected (could indicate

a lesion in the circumflex artery or the diagonal branch of the LAD artery).

Figures 59 and 60 show how each lead views the heart.

Figure 59

45

Figure 60

When interpreting an ECG, you will be able to identify abnormal flow/electrical pathways due to

arrhythmias, ischaemia and myocardial infarction, and you can assess which wall of the heart

may be affected. Note aVR is not included on the above. Historically it was often ignored as it

frequently displays reciprocal information, there is now much discussion on its importance for

helping diagnose many abnormalities including acute pericarditis or pulmonary embolism

(George et al 2010)

Any abnormalities should be seen by your supervisor in clinical practice.

Note speed

here is 50mm/s

46

Alternate Lead positions, and how to print a rhythm strip

Please ensure all ECG’s are reviewed by your supervisor as soon as possible, you may then

possibly get asked to:

Print a rhythm strip

Take a posterior lead ECG

Take a right sided ECG, for dextracardia.

Print a rhythm strip A rhythm strip may be requested this can mean a print out from a single lead such as in 3 lead

monitoring or press manual button on the 12 lead ECG machine and get a longer print with

more complexes (Fig. 22 shows a “Man Start” next to STOP button)

A posterior lead ECG Occasionally a patient with deep ST depression in anterior leads may require further testing,

and a posterior lead ECG may be required. This is where leads V4, V5 and V6 are removed and

replaced by V7, 8 and 9. The new leads are on the same horizontal plane with V7 in the

posterior axillary line, V8 is placed posterior scapula, and V9 is put at the left spinal border. The

leads have to be hand written on the print out, but this is often done by experienced staff.

Take a right sided ECG, for dextracardia Dextracardia (Fig. 61) - this is one of the abnormalities that

may be discovered, and therefore a 12 lead would need to

be done normally and then on the right hand side of the

patient’s chest. The limb leads would need swapping from

right to left, eg; move Right Arm to Left Arm and Neutral to

Left Leg. The chest leads need to start with V1 in the 4th

intercostal space left sternal edge and end with V6 in the

right mid axillary line on the same horizontal plane as V4.

(Campbell et al 2017)

This should be documented clearly.

Figures 62 & 63 demonstrate how the ECG electrodes are applied to the chest, the electrodes

on the limbs go in the same place but remember to switch the wires Right arm to Left arm etc.

Figure 61

47

Figure 62

Figure 63

48

Some other considerations

The below may be variations of normal ECG’s that you may encounter:

Benign Early Repolarization or “High Take-off”

This is a common phenomenon in the young, the ECG can show what appears to be ST

elevation and the ST segment can merge with the T wave. Safa et al (2017) have currently

found no clear indication that an early repolarisation pattern is a marker for arrhythmias, but

state that 5 - 13% of all adults have an early repolarisation pattern. (Fig. 64)

Figure 64

Sinus arrhythmias:

This is a common condition in young healthy adults and children, it is a variation of normal sinus

rhythm but has an irregular beat, it can be an indicator of good cardiovascular health. This often

disappears as the patient gets older, often by the patient’s 30’s.

To determine sinus arrhythmia, the rate will be irregular with P waves consistent with atrial

activity from the SAN. The rate may vary with the respiratory pattern; faster rate on inspiration

and slower on exhalation due to intermittent vagus nerve activation which occurs during

respiration and causes beat to beat variations in the resting heart rate.

49

Figure 65

Any arrhythmias should be investigated and the ECG should be reviewed by your supervisor.

U wave, This is a repolarization deflection of the Purkinje fibres, it appears after the T wave, as

a small positive deflection, they can become exaggerated with hypokalaemia and in some

cases can be linked with arrhythmias. However they are commonly present on ECG’s.

50

Case study and results


down

Presenting

Complaint

Patient noticed increased dizziness over last few weeks up and it is

worse when he bends down to pick up the post. No history of trauma/

pain, although his neighbour said that his pulse felt slow, she is a

health care assistant and told him to go to AE.

Past Medical History Normally fairly well, GP had given him some pain killers for a sore knee

but he thinks that is just arthritis.

Family History Nil to note

Social History Retired but active

Review of Systems Maybe slightly short of breath walking up stairs, but nothing too bad.

On examination:

General inspection Looks fairly well, if slightly pale

Tests 1. Vital signs: RR: 19, O2 Sats: not a good trace but 96% on room air,

HR: 31, B/P : 101/65, Temp: 36.50C, patient is Alert and BM: 4.6

2. ECG: see below

ECG interpretation

See Fig.65

1. Is the rhythm regular or irregular? 2. Calculate the rate 3. Can you identify a P wave? 4. Is there a QRS after every P wave? And is the PR interval

normal and constant? 5. Look at the QRS configuration 6. Are there abnormal Q waves? 7. Look at R wave progression 8. Look at the ST segment. 9. Look at the T waves. 10. Look at cardiac axis

ECG interpretation

See Fig.65

1. Is the rhythm regular or irregular? - The rhythm is regular 2. The rate: Using 30 large square the QRS rate is 30, or there are

9 large squares between the 1st two QRS in lead II, 300/9 = 33bpm

3. Can you identify a P wave?- Yes there are P waves 4. Is there a QRS after every P wave? And is the PR interval

normal and constant? No there is not a QRS after every P, and no there appears to be no correlation between the P and QRS. As an aside the P waves are regular in their own way and their

51


down

rate can be calculated as 9 P waves in 30 large squares (1 is in the 1st and 3rd QRS) therefore the P wave rate is 90 bpm.

5. Look at the QRS configuration: The QRS is greater than 3 small squares so this is a broad complex QRS

6. Are there abnormal Q waves?: There is nothing to note about the Q waves

7. Look at R wave progression: There is nothing to note about the R waves

8. Look at the ST segment: There is nothing to note about the ST segment

9. Look at the T waves: There is nothing to note about the T waves 10. Look at cardiac axis: Lead I is predominantly positive and Lead

II is predominantly negative-which can indicate a LAD

Clinical Diagnostic

Reasoning

Patient has had increased dizziness over last few weeks, he is

bradycardic, but maintaining his blood pressure, he is conscious and

alert with no chest pain.

His ECG shows a regular broad complex bradycardia with no

correlation between the P and QRS, suggesting that there is a

complete block at the AVN.

This ECG would be classed as Complete or 3rd degree heart block.

Patients with complete heart block are at risk of asystole, this would need reporting

immediately to your supervisor.

Further tests and investigations are required and the patient will need referral to a

cardiologist.

52

Case study ECG

Figure 66

53

Cardiac Arrest Rhythms

In the introduction of this guide there was a paragraph explaining that that the heart can emit

electrical activity which would show on an ECG, but may not be mechanically functioning. This

highlights that the patient should always be checked first before reviewing the ECG monitor or

trace.

Please firstly check that your patient is breathing and showing signs of life before contemplating

performing an ECG, if no signs of life call an ambulance/ MET or cardiac arrest team as per

BLS guidelines.

There are several ECG rhythms that can be associated with cardiac arrest:

PEA (Pulseless Electrical Activity)

Asystole

VF (Ventricular Fibrillation)

Pulseless VT (Ventricular Tachycardia)

PEA PEA or Pulseless Electrical Activity is when electrical activity shows on an ECG, but there is no

mechanical function, the 12 lead can produce what looks like a normal 12 lead ECG trace yet

with no mechanical cardiac activity. The trace can be tachycardic or bradycardic, or similar to

the patient’s rhythm prior to cardiac arrest but with no pulse. Below could represent a PEA:

Figure 67

54

Asystole This rhythm is normally associated with a poor outcome, and is when there is no mechanical or

electrical activity coming from the heart. Asystole or cardiac standstill can display on a screen

as a line.

The ECG below shows a couple of sinus beats before the trace moves to asystole

Figure 68

Notice that the line is not completely straight after the sinus beats, it is normally represented as

a slight undulation of the base line, or a drifting base line.

Points to note:

There can be other reasons for a straight/ or a flat line, the priority is to firstly check and assess

the patient.

If the patient is talking to you it is unlikely to be asystole, and more likely that a wire or electrode

has come off the patient. Leads off can often produce alarms from monitors and are often

represented as a completely straight or dotted line on the ECG trace, (Figure 68).

Figure 69

Another reason that the trace can occur as a flat line, is because the gain needs increasing.

Traces with very low amplitude may mimic asystole, increasing the gain on a monitor can

highlight that the person is actually in a different rhythm such as fine VF.

55

P wave asystole, or ventricular standstill.

Occasionally you may see in a cardiac arrest, p waves only with no QRS, in this case the

patient still needs to be given CPR, however the patient may be a candidate for transcutaneous

pacing by a trained clinician.

An example of P wave asystole or ventricular standstill:

Figure 70

VF This is where the heart is in an abnormal rhythm and is unable to effectively pump

mechanically. It is due to disorganised electrical activity causing the ventricle to twitch or quiver

randomly rather than contract and if intervention is not quick, will result in asystole.

VF is often recognisable on an ECG monitor as an irregular broad complex fast rhythm:

Figure 71

56

Pulseless VT This is where the ventricles are not producing any effective cardiac output, the rate is usually

greater than 180bpm and the QRS complexes are broad. The patient has no pulse and no signs

of life. The cardiac arrest team are required.

This is an introduction to interpretation, it will take many years to master this skill. The best way

to learn arrhythmias is to observe monitored patients where the symptoms they have help make

sense of what you see.

The more ECGs and monitors you can relate to a patient’s history the more sense they will

make. When looking at a patient’s case notes always try to interpret the ECG. The information

printed on the ECG is often incorrect but may be a useful guide, however always read what the

clinician has said as the two may conflict to see how accurate your interpretation is.

Figure 72

57

Bibliography & Further Reading

Campbell B, Richley D, Ross C, Eggett CJ. SCST (2017); CS3 Clinical Guidelines by

consensus; Recording a standard 12 lead electrocardiogram An approved methodology

by the society for Cardiological Science & Technology. Available at: Clinical Guidelines

by Consensus : SCST: Recording a standard 12 Lead ECG [Accessed 03/07/2020]

George, A., Arumugham, P. S., & Figueredo, V. M. (2010). aVR–the forgotten lead.

Experimental & Clinical Cardiology, 15(2), e36.

Goldberger, A. L., Goldberger, Z. D., & Shvilkin, A. (2018). In Goldberger A. L.,

Goldberger Z. D. and Shvilkin A.(Eds.), Chapter 3 - how to make basic ECG

measurements Elsevier. Chapter 3 - How to Make Basic ECG Measurements [Accessed

03/07/2020]

GMC 2018; Outcomes for Graduates; Outcomes for Graduates 2018 [Accessed

03/07/2020]

Hampton, J., & Hampton, J. (2019). The ECG made easy E-book Elsevier Health

Sciences.

Morris, F., Brady, W. J., & Camm, A. J. (2009). ABC of clinical electrocardiography John

Wiley & Sons

NICE; Chest pain of recent onset: assessment and diagnosis; Clinical guideline [CG95]

Published date: March 2010 Last updated: November 2016; NICE guidance: Recent-

onset chest pain of suspected cardiac origin: assessment and diagnosis [Accessed

03/07/2020]

NICE; Transient loss of consciousness ('blackouts') in over 16s; Clinical guideline

[CG109] Published date: August 2010 Last updated: September 2014; NICE Guidance:

Transient loss of consciousness ('blackouts') in over 16s [Accessed 03/07/2020]

Ortega, R., Mazzini, M., Xue, K., & Espaillat, D. (2015). Electrocardiographic monitoring

in adults. N Engl J Med, 372(8), e11. doi:10.1056/NEJMvcm1400705

Resuscitation Council UK (2016). Advanced Life Support, 7th Edition. Resuscitation

Council UK.

https://scst.org.uk/wp-content/uploads/2020/02/SCST_ECG_Recording_Guidelines_2017am.pdf

https://scst.org.uk/wp-content/uploads/2020/02/SCST_ECG_Recording_Guidelines_2017am.pdf

https://doi.org/10.1016/B978-0-323-40169-2.00003-2

https://www.gmc-uk.org/-/media/documents/dc11326-outcomes-for-graduates-2018_pdf-75040796.pdf

https://www.nice.org.uk/guidance/cg95




58

Rosso, R., Glikson, E., Belhassen, B., Katz, A., Halkin, A., Steinvil, A., & Viskin, S.

(2012). Distinguishing “benign” from “malignant early repolarization”: The value of the

ST-segment morphology. Heart Rhythm, 9(2), 225-229.

Safa, R., Thomas, R., & Karpawich, P. P. (2017). Electrocardiographic early

repolarization characteristics and clinical presentations in the young: A benign finding or

worrisome marker for arrhythmias. Congenital Heart Disease, 12(1), 99-104.

WHO (2009); WHO Guidelines on Hand Hygiene in Health Care; First Global Patient

Safety Challenge Clean Care is Safer Care. WHO guidelines on hand hygiene in health

care [Accessed 03/07/2020]

https://www.who.int/gpsc/5may/tools/9789241597906/en/

https://www.who.int/gpsc/5may/tools/9789241597906/en/

59

Picture Credits

1. Figure 1: Clinical Skills Teaching and Learning Centre, University of Liverpool

2. Figure 2: Adapted by CSTLC, Image in public domain: By Created by Agateller (Anthony

Atkielski), converted to svg by atom. - SinusRhythmLabels.png, Public Domain, Single ECG

Complex



5. Figure 5: Einthoven's triangle showing leads I,II,III, aVF, aVL & aVR. Edited from image by

Npatchett - Own work, CC BY-SA 4.0, Einthoven's triangle. This file is licensed under the

Creative Commons Attribution-Share Alike 4.0 International license


7. Figure 7: Chest lead position; Permission for image kindly given from SCST.org.uk

8. Figure 8: Einthoven's Triangle: Author; Npatchett, This file is licensed under the Creative

Commons Attribution-Share Alike 4.0 International license. Image By Npatchett - Own work,

CC BY-SA 4.0, Npatchett- Enthoven's triangle










18. Figure 18: Image skin condition- contact dematitis; By Digitalgadget at English Wikipedia -

Transferred from en.wikipedia to Commons, Public Domain, contact dermatitis






24. Figure 24: Adapted by CSTLC from svg at Clipart: rib cage : rib cage


26. Figure 26: Philips IntelliVue MX40 portable patient telemetry monitor, permission to use

image kindly supplied by Philips.

27. Figure 27: Adapted by CSTLC, Image in public domain: By Created by Agateller (Anthony

Atkielski), converted to svg by atom. - SinusRhythmLabels.png, Public Domain, Single ECG

Complex


https://commons.wikimedia.org/w/index.php?curid=1560893





https://svg-clipart.com/outline/dh7HcaK-rib-cage-clipart



60





33. Figure 33: AF: By James Heilman, MD - Own work, CC BY-SA 3.0, Atrial Fibrillation




37. Figure 37: Mobitz type I: By Npatchett - Own work, CC BY-SA 4.0, Mobitz type I and II heart

block

38. Figure 38: Mobitz type I: By Npatchett - Own work, CC BY-SA 4.0, Mobitz type I and II heart

block





43. Figure 43: LBBB: By James Heilman, MD - Own work, CC BY-SA 3.0, LBBB


45. Figure 45: By James Heilman, MD - Own work, CC BY-SA 3.0, Ventricular Ectopic




49. Figure 49: Jenkins, Dean, MB BCh DipMedEd FRCP; Gerred, Stephen, MBChB FRACP.

Published January 1, 2011. Pages 183-193. © 2011. Abrupt abnormality in R wave

progression. Copyright © 2016 © 2016, Elsevier Limited. All rights reserved.



52. Figure 52: Inferior MI: By James Heilman, MD - Own work, CC BY-SA 4.0, Inferior MI






58. Figure 58: Cardiac Axis: Automaticity: Natural Excitation of the Heart. Pappano, Achilles J.,

PhD, Cardiovascular Physiology, 3, 29-48 Copyright © 2019 Copyright © 2019 Elsevier Inc.

All Rights Reserved.



61. Figure 61: dextracardia By Nevit - Own work, CC BY-SA 3.0, Dextracardia












61

64. Figure 64: Early benign repolarisation: By James Heilman, MD - Own work, CC BY-SA 3.0,

Early Benign Repolarisation

65. Figure 65: The ECG in healthy people Hampton, John R., The ECG In Practice, 1, 1-57

Sinus arrhythmia Note •Marked variation in R-R interval •Constant PR interval •Constant

shape of P wave and QRS complex Copyright © 2013 © 2013 Elsevier Ltd. All rights

reserved.



68. Figure 68: Asystole, a couple beats of normal sinus followed by asystole: By James

Heilman, MD - Own work, CC BY-SA 3.0, Asystole



71. Figure 71: Ventricular Fibrillation. By Jer5150 - Own work, CC BY-SA 3.0, Ventricular

Fibrillation


73. Diagrams 1-7: Clinical Skills Teaching and Learning Centre, University of Liverpool





Performing a 12 lead Electrocardiogram (ECG) and Interpretation … · 2020. 9. 4. · ECG Electrocardiogram Iso-electric line Base line on ECG recording LAD Left Axis Deviation LBBB

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