2. Aims
♥ Anatomy and physiology of the heart
♥ Understanding the ECG
♥ Ischaemia and myocardial infarction
♥ Caring for the cardiac patient
♥ Case studies
5. Blood Flow Through the Heart
♥ Blood flows from SuperiorBlood flows from Superior
and Inferior Vena Cava toand Inferior Vena Cava to
the Right Atriumthe Right Atrium
♥ Flows through theFlows through the
Tricuspid (AV) Valve toTricuspid (AV) Valve to
the Right Ventriclethe Right Ventricle
♥ Blood leaves the RVBlood leaves the RV
through the pulmonarythrough the pulmonary
trunktrunk
♥ Enters lungs via the RightEnters lungs via the Right
and Left pulmonaryand Left pulmonary
arteriesarteries
6. Blood Flow Through The Heart
♥ After gas exchange inAfter gas exchange in
the lungs, blood isthe lungs, blood is
transported to the lefttransported to the left
atrium through the Rightatrium through the Right
and Left pulmonary veinsand Left pulmonary veins
♥ Blood flows through theBlood flows through the
Mitral Valve into the LeftMitral Valve into the Left
VentricleVentricle
♥ The Left Ventricle is theThe Left Ventricle is the
main pump that pumpsmain pump that pumps
the blood to the body viathe blood to the body via
the aortathe aorta
7. The Layers Of The Heart Wall
♥ Epicardium – outer layer, also called the
visceral layer
♥ Myocardium – middle layer, composed of
cardiac muscle tissue, thicker at the left
ventricle to give more pumping power
♥ Endocardium – inner layer, lines the heart
chambers and the valves
9. The Coronary Arteries
♥ Right Coronary Artery –
supplies the RA, RV and a
portion of the LV
♥ Left Main Coronary Artery
– divides into:
♥ Left Anterior Descending –
supplies the anterior part
of the LV and the septum
♥ Circumflex – supplies the
LA and posterior LV
10. The Conduction System
♥ Heart is an efficientHeart is an efficient
pump because it is co-pump because it is co-
ordinated by theordinated by the
conduction systemconduction system
♥ It controls the heart viaIt controls the heart via
a network ofa network of
specialised fibres whichspecialised fibres which
initiate and conduct theinitiate and conduct the
electrical impulse thatelectrical impulse that
results in muscleresults in muscle
contractioncontraction
12. Lead Placement
♥Limb leads – Ride YourLimb leads – Ride Your
Green Bike!Green Bike!
♥V1- 4th intercostal space toV1- 4th intercostal space to
the right of sternumthe right of sternum
♥V2- As above but to the leftV2- As above but to the left
♥V3- Midway between V2V3- Midway between V2
and V4 (do V4 first)and V4 (do V4 first)
♥V4- Mid clavicular, 5thV4- Mid clavicular, 5th
intercostal spaceintercostal space
♥V5- Anterior axillary line,V5- Anterior axillary line,
horizontal to V4horizontal to V4
♥V6- Mid axillary line,V6- Mid axillary line,
horizontal to V4 and V5horizontal to V4 and V5
♥Shave excess hair
♥For limb leads place at wrists
and close to ankle
♥If patient shaking go for bony
areas
13. Artifact
It is important that an ECG is free from anyIt is important that an ECG is free from any
artifact when using it to make a diagnosis.artifact when using it to make a diagnosis.
Causes of artifact can be:Causes of artifact can be:
--Poor application of ECG electrodes (Dried out gel, airPoor application of ECG electrodes (Dried out gel, air
trapped under electrode & patient hair preventing goodtrapped under electrode & patient hair preventing good
skin contactskin contact
-Patient’s movement-Patient’s movement
-Electrical interference-Electrical interference
-Cable movement-Cable movement
-Vehicle movement-Vehicle movement
15. Lead Views
♥ Limb leads look from a
‘vertical plane’
♥ I and AVL look from the
left side - lateral wall
♥ II, III and AVF look up
from the bottom of the
heart – inferior wall
♥ AVR looks from the
right, but use that to tell
you if the leads are on
wrong!
19. Right Sided and Posterior ECGs
♥ Right sided should be
done if patient is having
an Inferior MI
♥ Could change
management of
hypotension in post MI
patient
♥ Look for ST elevation in
rV4
♥ Ensure is clearly
labelled
♥ Posterior ECG – may
not change treatment
20. ECG Paper
♥ Paper speed should be set to
25mm/sec
♥ Each small square = 0.04 sec
♥ Each large square = 0.20 sec
♥ 5 small squares = 0.20 sec
denoted by a heavy line
21. Electrical Events Of The Cardiac
Cycle
♥ Resting Heart Muscle =
Polarised
♥ Contraction caused by
stimulation =
Depolarisation
♥Heart muscle cells returnHeart muscle cells return
to resting state followingto resting state following
stimulation =stimulation =
RepolarisationRepolarisation
♥Resultant depolarisationResultant depolarisation
and repolarisation areand repolarisation are
represented on the ECGrepresented on the ECG
by characteristicby characteristic
waveforms: The PQRSTwaveforms: The PQRST
ComplexComplex
22. The ECG Complex
♥ P wave = Atrial
Depolarisation
♥ QRS complex =
Ventricular
Depolarisation
♥ ST segment = time
between Ventricular
Depolarisation and
Ventricular
Repolarisation
♥ T wave = Ventricular
Repolarisation
24. The P Wave
♥ Represents depolarisation of
atrial muscle cells
♥ Precedes each QRS
complex
♥ Normally positive
♥ Gently rounded
♥ Height <3mm
♥ Width <0.11sec
♥ Measured from very
beginning to the end of the
waveform
25. The PR Interval
♥ Measured from the
beginning of the P wave to
the beginning of the QRS
complex
♥ Represents total amount of
time required for
depolarisation of atria and
for impulse to travel
through the AV node
♥ Normal width = 0.12-0.20
sec (3-5 small squares)
PR interval
26. The QRS Complex
♥ Represents ventricular
depolarisation
♥ Results of simultaneous
depolarisation of both
ventricles
♥ Follows each P wave
♥ Q wave not normally
present, but small Qs
maybe visible
♥ Predominantly positive
♥ Width <0.11 sec
27. The ST Segment
♥ Interval between the end
of the QRS and beginning
of the T wave
♥ Represents beginning of
ventricular repolarisation
♥ Normally Isoelectric –
neither above or below the
baseline
♥ Shape and postion may
be altered due to
ischaemia, drug or
metabolic effects
29. The T Wave
♥ Normally follows a QRS
complex
♥ Represents the end of
repolarisation of the
ventricles
♥ Should be a positive
deflection
30. The QT Interval
♥ Represents the time from
start of ventricular
depolarisation to end of
ventricular repolarisation
♥ QT interval varies
depending on rate. Is
longer with bradycardia
and shorter with
tachycardia
♥ Is influenced by electrolyte
imbalance, ischaemia and
drugs
QT interval
32. Pathological Q Waves
The following factors must be taken into
consideration when assessing the Q wave
significance in AMI
– The presence of associated LBBB
– The width and depth of the Q wave
– The specific leads in which the Q wave appear
– The number of leads in which the Q wave appear
– Other ECG evidence of a MI
34. “Big Square Method”
♥ Easy but only accurate if rhythm is regular
♥ Count the number of large squares between two QRS
complexes (R wave to R wave)
♥ Divide the number of large squares into 300
35. 1500 Method
♥ Most precise way to determine rate
♥ Can only be used if rhythm is regular
♥ Count number of small squares between two QRS complexes
(R wave to R wave)
♥ Divide the number of small squares into 1500
36. 6 Second Method
♥ Not very accurate, but easy
♥ Useful when rhythm is irregular
♥ Note the small vertical lines at the top of the
ECG paper. These represent 3 second intervals
♥ Count the number of QRS complexes in 6
seconds and multiply by ten
37. 7 Point Analysis of An ECG
1. Rhythm
Regular?
Irregular?
Irregularly irregular?
2. Rate
Normal?
Bradycardic? <60
Tachycardic? >100
3. P Waves
Present/absent?
A P wave for every QRS
complex?
Same size and shape?
4. PR Interval
Normal? (0.12-0.20sec)
Too short or too long?
5. QRS Complexes
Normal? (<0.11sec)
Too wide?
6. ST segment
Normal?
Elevated/depressed
7. T Wave
Normal?
Unusually raised?
Inverted?
44. Myocardial Infarction
♥ An MI occurs when an area of myocardium becomes
irreversibly necrotic
♥ Most common cause is thromboembolic occlusion of a
coronary artery
45. Myocardial Infarction
♥ An atherosclerotic plaque
ruptures the intima of an
artery causing it to come
into contact with the
circulating blood
♥ The uneven surface allows
platelets to adhere to it.
Therefore forming a clot,
blocking the artery and
stopping blood flow
46. Acute Myocardial Infarction
♥ ST elevation >2mm in V1-V3 and >1mm in all other leads in
>2 contiguous leads1
.
♥ Myocardial injury presents as raised ST1
.
♥ Infarction can present as Q wave1
.
I Lateral
II Inferior
III Inferior
aVR
aVL Lateral
aVF Inferior
V1 Septal
V2 Septal
V3 Anterior
V4 Anterior
V5 Lateral
V6 Lateral
1. The Task Force on the management of acute myocardial infarction of the
European Society of Cardiology. Eur Heart J 2003;24:28-66
47. Evolution Of An Acute MI
A. Before B. Min – h C. 1 day D. 1 week E.Months
infarction after after
after after
49. Care of the cardiac patient
Diagnosis
♥ Patient story
♥ ECG changes
♥ Raised cardiac enzymes
Symptoms
♥ Central chest
pain/tightness or pressure
♥ Severe prolonged pain
♥ Cold and clammy
♥ Nausea and vomiting
♥ Arrhythmias
Treatment
♥ pPCI or thrombolysis
♥ Aspirin
♥ Clopidogrel
♥ LMWH
♥ Beta- blocker
♥ Oxygen
♥ Nitrates
♥ Morphine & anti-emetic
50. Assessment of Pain - PQRST
♥ Position – where is it?
♥ Qualities – what is it like?
what makes it start and stop?
♥ Radiation – does it go anywhere else?
♥ Symptoms – are there any other symptoms?
♥ Timing – when did it start?
how long has it lasted?
56. Dynamic Changes In AMI
Pre-hospital ECG showing possible
hyperacute S-T changes in anterior leads
57. Dynamic Changes in AMI
2nd ECG taken 20mins later, showing
established antero-lateral S-T elevation
58. Bundle Branch Block
♥ Normally both bundle branches transmit a stimulus to
the 2 ventricles simultaneously.
♥ The QRS duration will be less than 0.12 seconds (3
small squares).
♥ If one of the bundle branches is blocked, a ventricle
may be depolarised through an abnormal pathway
outside the main conduction system causing the QRS
duration to be greater than 0.12 seconds.
59. ECG Leads
V6
V5
V2V1
♥ To be able to identify which bundle branch isTo be able to identify which bundle branch is
blocked, you will need to know which leads bestblocked, you will need to know which leads best
show the resulting abnormality.show the resulting abnormality.
♥ The leads looking directly at the right ventricleThe leads looking directly at the right ventricle
are V1 & V2.are V1 & V2.
♥ The leads looking at the left ventricle are V5,V6The leads looking at the left ventricle are V5,V6
& lead I.& lead I.
60. Left Bundle Branch Block
QS
V1
QS
♥ LBBB produces a QS (negative complex) in V1 and wideLBBB produces a QS (negative complex) in V1 and wide
notched complexes in the Left limb / chest leads (I, V5 ¬ched complexes in the Left limb / chest leads (I, V5 &
V6).V6).
I V5 V6
61.
62. Left Bundle Branch Block
♥ This can be a pre-existing condition but is always
pathological.
♥ Causes include either a new or old MI. Can also be a
degenerative change.
♥ It also causes ST / T wave changes, with T wave
inversion in the left ventricular leads.
A new LBBB caused by an Acute
Coronary Syndrome identifies a very
high risk patient associated with > 40%
mortality without treatment
63.
64. AMI ECG Imitators
Caution – the following ECG’s can show ST
segment changes
- Left Bundle Branch Block
- Left Ventricular Hypertrophy
- Paced rhythm
- Ventricular rhythms
- Early reploarisation
- Pericarditis
- Ventricular aneurysm
This shows the importance of using an ECG along with the clinical
findings & not in isolation.
65. Left Ventricular Hypertrophy
Suspect LVH if
♥ The R wave in V5 or V6 exceeds 25mm (5 squares).
♥ The S wave in V1 or V2 exceeds 25mm (5 squares)..
♥ The total of the R wave in V5 or V6 plus the S wave in V1 or V2
exceeds 35mm.
♥ You can also look for evidence of “strain” with ST depression and/or
T wave inversion
