Upload
others
View
14
Download
1
Embed Size (px)
Citation preview
1
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
2
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
3
Cardiac Arrest Rhythms ............................................................................................................. 53
PEA ........................................................................................................................................ 53
Asystole .................................................................................................................................. 54
VF ........................................................................................................................................... 55
Pulseless VT ........................................................................................................................... 56
Bibliography & Further Reading ................................................................................................. 57
Picture Credits ........................................................................................................................... 59
4
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
5
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
6
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.
7
Figure 1
8
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.
9
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
10
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
11
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
12
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
13
Lead II measures the electrical potential between the left leg and the right arm (inferior
wall of the left ventricle)
Lead III measures the electrical potential between the left leg and the left arm (inferior
wall of the left ventricle)
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
14
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
15
This is another way of showing the directions of the electrical currents recorded by the 12 lead
ECG.
Figure 8
16
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
17
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
18
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
19
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
20
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
21
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
22
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)
23
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.
24
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
25
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
26
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.
27
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.
28
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
29
Interpretation of a 12 lead ECG
Table 1
Waveform Normal Configuration and Duration Physiology
P wave, see figure
27
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
30
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)
31
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
32
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.
33
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.
34
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
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 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
An 79 year old patient attends AED with a history of dizziness, worse when bending
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.
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]
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
3. Figure 3: Clinical Skills Teaching and Learning Centre, University of Liverpool
4. Figure 4: Clinical Skills Teaching and Learning Centre, University of Liverpool
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
6. Figure 6: Clinical Skills Teaching and Learning Centre, University of Liverpool
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
9. Figure 9: Clinical Skills Teaching and Learning Centre, University of Liverpool
10. Figure 10: Clinical Skills Teaching and Learning Centre, University of Liverpool
11. Figure 11: Clinical Skills Teaching and Learning Centre, University of Liverpool
12. Figure 12: Clinical Skills Teaching and Learning Centre, University of Liverpool
13. Figure 13: Clinical Skills Teaching and Learning Centre, University of Liverpool
14. Figure 14: Clinical Skills Teaching and Learning Centre, University of Liverpool
15. Figure 15: Clinical Skills Teaching and Learning Centre, University of Liverpool
16. Figure 16: Clinical Skills Teaching and Learning Centre, University of Liverpool
17. Figure 17: Clinical Skills Teaching and Learning Centre, University of Liverpool
18. Figure 18: Image skin condition- contact dematitis; By Digitalgadget at English Wikipedia -
Transferred from en.wikipedia to Commons, Public Domain, contact dermatitis
19. Figure 19: Clinical Skills Teaching and Learning Centre, University of Liverpool
20. Figure 20: Clinical Skills Teaching and Learning Centre, University of Liverpool
21. Figure 21: Clinical Skills Teaching and Learning Centre, University of Liverpool
22. Figure 22: Clinical Skills Teaching and Learning Centre, University of Liverpool
23. Figure 23: Clinical Skills Teaching and Learning Centre, University of Liverpool
24. Figure 24: Adapted by CSTLC from svg at Clipart: rib cage : rib cage
25. Figure 25: Clinical Skills Teaching and Learning Centre, University of Liverpool
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
28. Figure 28: Clinical Skills Teaching and Learning Centre, University of Liverpool
60
29. Figure 29: Clinical Skills Teaching and Learning Centre, University of Liverpool
30. Figure 30: Clinical Skills Teaching and Learning Centre, University of Liverpool
31. Figure 31: Clinical Skills Teaching and Learning Centre, University of Liverpool
32. Figure 32: Clinical Skills Teaching and Learning Centre, University of Liverpool
33. Figure 33: AF: By James Heilman, MD - Own work, CC BY-SA 3.0, Atrial Fibrillation
34. Figure 34: Clinical Skills Teaching and Learning Centre, University of Liverpool
35. Figure 35: Clinical Skills Teaching and Learning Centre, University of Liverpool
36. Figure 36: Clinical Skills Teaching and Learning Centre, University of Liverpool
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
39. Figure 35: Clinical Skills Teaching and Learning Centre, University of Liverpool
40. Figure 36: Clinical Skills Teaching and Learning Centre, University of Liverpool
41. Figure 41: Clinical Skills Teaching and Learning Centre, University of Liverpool
42. Figure 42: Clinical Skills Teaching and Learning Centre, University of Liverpool
43. Figure 43: LBBB: By James Heilman, MD - Own work, CC BY-SA 3.0, LBBB
44. Figure 44: Clinical Skills Teaching and Learning Centre, University of Liverpool
45. Figure 45: By James Heilman, MD - Own work, CC BY-SA 3.0, Ventricular Ectopic
46. Figure 46: Clinical Skills Teaching and Learning Centre, University of Liverpool
47. Figure 47: Clinical Skills Teaching and Learning Centre, University of Liverpool
48. Figure 48: Clinical Skills Teaching and Learning Centre, University of Liverpool
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.
50. Figure 50: Clinical Skills Teaching and Learning Centre, University of Liverpool
51. Figure 51: Clinical Skills Teaching and Learning Centre, University of Liverpool
52. Figure 52: Inferior MI: By James Heilman, MD - Own work, CC BY-SA 4.0, Inferior MI
53. Figure 53: Clinical Skills Teaching and Learning Centre, University of Liverpool
54. Figure 54: Clinical Skills Teaching and Learning Centre, University of Liverpool
55. Figure 55: Clinical Skills Teaching and Learning Centre, University of Liverpool
56. Figure 56: Clinical Skills Teaching and Learning Centre, University of Liverpool
57. Figure 57: Clinical Skills Teaching and Learning Centre, University of Liverpool
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.
59. Figure 59: Clinical Skills Teaching and Learning Centre, University of Liverpool
60. Figure 60: Clinical Skills Teaching and Learning Centre, University of Liverpool
61. Figure 61: dextracardia By Nevit - Own work, CC BY-SA 3.0, Dextracardia
62. Figure 62: Clinical Skills Teaching and Learning Centre, University of Liverpool
63. Figure 63: Clinical Skills Teaching and Learning Centre, University of Liverpool
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.
66. Figure 66: Clinical Skills Teaching and Learning Centre, University of Liverpool
67. Figure 67: Clinical Skills Teaching and Learning Centre, University of Liverpool
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
69. Figure 69: Clinical Skills Teaching and Learning Centre, University of Liverpool
70. Figure 70: Clinical Skills Teaching and Learning Centre, University of Liverpool
71. Figure 71: Ventricular Fibrillation. By Jer5150 - Own work, CC BY-SA 3.0, Ventricular
Fibrillation
72. Figure 72: Clinical Skills Teaching and Learning Centre, University of Liverpool
73. Diagrams 1-7: Clinical Skills Teaching and Learning Centre, University of Liverpool