Arrhythmia
Interpretation
Workbook
for FY1 Doctor’s
By
Dr Christopher McAloon
Introduction
Learning Objectives
On completion of this workbook and the
session you should be able to:
1. Correctly recognise and action lifethreatening ECG’s.
2. Correctly analyse and interpret common
tachy/bradyarrhythmias ECG’s.
3. Correctly recognise different types of
tachyarrhythmias
4. Correctly recognise different types of
Bradyarrhythmia’s
What the workbook does
not do?
The workbook is designed to work through
interpreting and recognising different ECG
rhythm, not the entire 12 lead ECG.
In clinical practice this is a continuum, but
is beyond the purpose of the workbook.
Purposely the book does not include
ischaemic ECG’s.
Contents
1. How to use this book
2. Reading rhythm strips
3. The Advanced Life Support
(ALS)Approach
4. Life-threatening ECG’s
5. Tachyarrhythmia’s
6. Bradyarrhythmia’s
7. Continued Learning
8. Evaluation form
1. How to use this book
The workbook will challenge you to interpret
different rhythms in a systematic manner.
The ECG’s will become more challenging as
you become more confident
in
interpretation. Additional reading may be
required to supplement your knowledge.
The interactive key will guide you through
successfully using the workbook.
Interactive Key:
Important
Further reading required
Exercise to be completed
2. Reading rhythm strips
We all have our own system for reading 12
lead ECG’s.
Take a moment to think about your system
to reading ECG’s. Are there any limitations
with your system?
If you have a system that you are happy with
please use it in the workbook.
3. The ALS Approach
The ALS course teaches a very quick and easy
six questions to be asked to interpret
rhythms (not whole ECG’s):
1.
Is there electrical activity?
2.
What is the ventricular (QRS) rate?
3. Is the QRS rhythm regular or
irregular?
4. Is the QRS complex width normal or
prolonged?
5.
Is there atrial activity present?
6. Is the atrial activity related to
ventricular activity, if so how?
Using the ALS Approach interpret this ECG.
Figure 1. ECG gentleman fit and well.
1. Is there electrical activity? Yes / No
2. What is the ventricular (QRS) rate?
QRS rate can be calculated many ways.
One way is:
 One big square on the horizontal axis of an ECG is 0.2
seconds (5 big square is 1 second)
 Count the number QRS complexes in 6 seconds (30
large squares)
 Multiply by 10 = No beats/ minute
3. Is the QRS rhythm regular or irregular?
Sometimes this is obvious from distance!
Mark out the R waves on piece of paper; are the R wave
intervals regular?
4. Is the QRS complex width normal (narrow) or
prolonged (Broad)?
Narrow less than 0.12 seconds/ 3 small squares
Broad > greater than 0.12 sec/ 3 small squares
5. Is there atrial activity present?
Yes/ No
This question purely asks to look at the presence of P waves
only.
6. Is the atrial activity related to ventricular activity, if so
how?
Look to see how / if at all the P wave is associated with the
QRS complex
 Is the interval (PR) consistent with every P wave and
following QRS?
 Is there any relationship at all? If so what?
 If not what is the atrial rate?
What rhythm does Figure 1. ECG
demonstrates?
Figure 1 Interpretation
1. Is there electrical activity? Yes
2. What is the ventricular (QRS) rate? 50 beats per minute
3. Is the QRS rhythm regular or irregular? Regular
4. Is the QRS complex width normal or prolonged?
Narrow
5. Is there atrial activity present? Yes
6. Is the atrial activity related to ventricular activity, if so
how? Yes – Sinus Rhythm
This is a narrow complex, sinus bradycardia,
which is regular.
4. Life – Threatening
Rhythms
There are rhythms we must be able to
recognise as doctors immediately. Firstly
though before we even look at the ECG, we
MUST look at the patient.
Case 1. Man has an ECG
Case 2. Man has an ECG
Both Cases have the same ECG tracing, but
which is the life threatening rhythm?
Case 1 is caused by the Pneumatic drill and the trace is
picking up the vibrations.
Using the ALS Approach describe these
rhythms:
Are they life threatening?
If it is would you shock the patient?
Case 3. Collapsed man
Case 4. Collapsed Woman.
Case 5. Chest pain then collapse.
Answers
Case 3.
No electrical activity activity, collapsed man.
Asystole (check patient – leads could be disconnected!)
Yes this is life threatening. Non-shockable.
Case 4.
Broad complex, Regular Tachycardia, No atrial activity.
Concordant activity, regular.
Supported if fusion/ capture beats.
Ventricular Tachycardia
Life-threatening rhythm, if clinically indicated patient needs
to be shocked!
Case 5.
There is electrical activity, with irregular QRS complexes,
tachycardia approx. 150-180 bpm, No atrial activity.
Disconcordant QRS complexes
Ventricular Fibrillation.
Life threatening rhythm.
Needs to be shocked.
The following page supplements the Cardiac
Arrest (life threatening rhythms)
management, but further reading is required
here.
5. Tachyarrhythmia’s
Let’s get ourselves in the Tachy mood…. What do you
know?
What pulse rate defines tachycardia?
What is a Narrow QRS complex?
What is a Broad QRS complex?
Can you think of rhythms that cause regular Narrow
Complex Tachycardia’s?
Can you think of rhythms that cause irregular Narrow
Complex Tachycardia?
Can you think of rhythms that cause Broad Complex
Tachycardia?
Tachyarrhythmias
Tachycardia is > 100 bpm. All of us can increase our heart
rate, for example when we exercise. This is physiological
and is called Sinus Tachycardia. This is not an arrhythmia.
There are other tachycardia’s which are caused by different
rhythms, many of which are pathological. It can be very
difficult to immediately diagnose as the ECG is going so fast.
Using the ALS approach, we can interpret it first and then
make a diagnosis.
We broadly classify tachyarrhythmias first as Narrow or
Broad (QRS duration). If it is broad in almost all occasions
the tachycardia originates in the ventricles below the
Bundle of His. We have already encountered these rhythms
Ventricular Tachycardia/ Fibrillation.
Rarely Broad Complex Tachycardia’s a can originate above
the ventricle e.g. SVT with aberrancy – having a bundle
branch block pattern. (this is beyond the remit of the book).
Narrow Complex Tachycardia (NCT) originate from atrial
myocardium or the AV junction. These are also called
supraventricular tachycardia (SVT). These can be
subclassified as regular or irregular.
NCT Regular: Atrial Tachycardia, AV-Nodal-Re-entrantTachycardia (AVNRT), AV re-entry Tachycardia (AVRT),
Atrial Flutter with fixed block.
Sounds complicated, but management essentially the same!
NCT Irregular: Atrial Fibrillation, Atrial Flutter with variable
block.
The following flow chart demonstrates management of SVT
based on interpretation.
Clinically you do not need to work out the exact cause for
the arrhythmia, but what the rhythm is e.g. Regular NCT.
The questions to ask are:
1. What is the patient like? (Are they stable?)
2. The ALS Approach questions
What is you interpretation of these ECG’s?
Are they stable clinically?
What would you do next?
Case 6. Young man with palpitations. Well.
Case 7. Man well with dizziness. Stable.
Case 8. Elderly patient with SOB. Stable.
Case 9. Middle aged patient blacked out.
BP 60/20.
Answers
Case 6.
NCT regular at a rate of 150 bpm. No P waves.
Patient stable – no indication for shock.
Carotid sinus massage/ Valsava manoeuvre.
Adenosine challenge (in no contraindication).
Consider B Blocker
Case 7.
NCT regular, rate 150 bpm, 2 P waves to 1 QRS.
Atrial Flutter 2:1. If uncertain:
Patient stable – no indication for shock.
Carotid sinus massage/ Valsava manoeuvre.
Adenosine challenge (in no contraindication).
Case 8.
NCT irregular. Rate 150 bpm. No P waves seen.
Atrial Fibrillation with fast ventricular response.
Patient stable.
Dependent patient, B-Blocker / Digoxin.
Case 9.
BCT, Rate 150 bpm.
Ventricular Tachycardia likely.
Patient unstable – But has a pulse.
Not cardiac arrest yet!
Indication for urgent shock.
5. Bradyarrhythmia’s
Bradycardia is when the QRS rate is less than 60 bpm.
Bradycardia can be physiological, for example during sleep,
in athletes and as a response to certain medication (B
Blocker).
Pathological bradycardia can result from malfunction of the
SA node or from partial/ complete failure of atrioventricular
conduction. This may require a pacemaker.
Bradyarrthymias can be life threatening and can proceed
Cardiac arrest.
There are different Bradyarrthymias; the majority are
referred to as heart block, which refer to partial or
complete blockage of the AV conduction.
Type 1 Heart block
Consistent prolongation PR interval
(>0.2 seconds), can be physiological
Type 2 Heart block
Mobitz Type 1
prolongation after each successive
P wave, until a drop beat
Mobitz Type 2
Intermittent non-coducted P waves
without prolongation.
Can result 2:1, 3:1 block
Complete Heart Block
No association between P
waves and QRS complexes.
QRS can be Broad.
Malfunction of the SA node as in sick sinus syndrome can
lead to ‘junction rhythms’ or ‘escape rhythms’. Atrial
Fibrillation may also present as ‘slow AF’. And this may or
may not be related to rate limiting medication. We will not
explore this any further and focus on the Heart Blocks, but
it is worth being aware of them.
Using the ALS approach to rhythm
Interpretation, decide which heart block is
demonstrated in the ECG’s shown
Case 10.
Case 11.
Case 12.
Answers
Case 10.
Bradycardia at 50bpm, narrow complexes, regular (no drop
beats). There are P waves and they are associated with the
QRS complexes. There are 2 P waves to each QRS complex.
Type 2 Heart Block with a 2:1 block.
Case 11.
Bradycardia at 60 bpm. Narrow complexes, regular (no drop
beats). Atrial activity present. One P wave to one QRS
complex. PR interval prolonged on consistent interval.
Type 1 Heart Block.
Case 12.
This is a difficult ECG. The QRS intervals have a rate of
50bpm. The QRS complexes are regular. The QRS complexes
are Broad. Initially the P waves seem to have varying
prolongation to the QRS complexes. Could it be Type 2
Heart Block (Mobitz 1)? No, the P waves are regular and not
conducting to the ventricles. The other clue is the QRS
width is Broad.
Complete Heart Block.
Management of Bradycardia depends if the
patient is stable. This algorithm details how
to evaluate Bradyarrthymias in terms of
acute management.
6. Continued Learning
I hope you enjoyed using this workbook and
you feel more confident interpreting
rhythms in the clinical setting. The key to
developing confidence is to keep practicing
looking at different rhythms. A reference list
is available at the end of the book for further
reading.
Please complete the evaluation to allow us
to assess the usefulness of the workbook
and what could be done to improve it in the
future.
7. Evaluation
Please could you take a minute to complete the evaluation?
The form is completely anonymous, please be honest.
1, What trainee level are you?
2, What specialities have you performed rotations?
For each statement please circle a rating and please add any
addition comments.
3, The ‘Emergency Rhythm Interpretation’ Workbook was
relevant to my clinical practice.
1 – Strongly Agree; 2-agree; 3 – neutral; 4-disagree; 5strongly disagree
4, The ‘Emergency Rhythm Interpretation’ Workbook was
helpful to my clinical practice.
1 – Strongly Agree; 2-agree; 3 – neutral; 4-disagree; 5strongly disagree
4, I now feel more confident recognising and interpreting
life threatening rhythms.
1 – Strongly Agree; 2-agree; 3 – neutral; 4-disagree; 5strongly disagree
5, I now feel more confident recognising and interpreting
tachyarrhythmia’s
1 – Strongly Agree; 2-agree; 3 – neutral; 4-disagree; 5strongly disagree
6. 6, I now feel more confident recognising and interpreting
Bradyarrhythmia’s
1 – Strongly Agree; 2-agree; 3 – neutral; 4-disagree; 5strongly disagree
7, I will use the ALS approach to interpreting rhythms in my
own clinical practice.
1 – Strongly Agree; 2-agree; 3 – neutral; 4-disagree; 5strongly disagree
8, The information in the workbook was pitched at the right
level.
1 – Strongly Agree; 2-agree; 3 – neutral; 4-disagree; 5strongly disagree
9, The ‘Emergency Rhythm Interpretation’ Workbook was
easy to use.
1 – Strongly Agree; 2-agree; 3 – neutral; 4-disagree; 5strongly disagree
10, What would you do to improve the workbook?
11, Would you recommend the workbook to a friend?
References
1, Resuscitation Council (UK) Cardiac monitoring,
electrocardiography, and rhythm recognition. Advanced Life
Support. Sixth edition. Kent: TT Litho Printers, pp71-88
2, Deakin CD, Nolan JP, Soar J, Sunde K, Koster R, Smith GB,
Perkins GD. 2010. European Resuscitation Council Guidelines
for Resuscitation 2010 Section 4. Adult Advanced Life
Support. Resuscitation. 81 (2010); pp.1305 - 1352