ECGs Flashcards
What does the ECG represent?
the movement of the negatively charged electrical impulse toward and away from the positive electrode
Lead
the view of the heart’s electrical activity from the perspective of the positive electrode
ECG Basics
Speed: 25mm/sec
Small square: 0.04sec & 1mm x 1mm
Large square: 0.2sec & 5mm x 5mm
3 seconds between short vertical lines
6 Second Method
- find dark line and count 6 across from this (= 6 seconds)
- count QRS complexes in this 6 seconds
- multiply QRS complexes by 10
P Wave
should be present, upright, rounded and precede each QRS complex
R-R Method
Count number of large boxes between two R waves:
1 = 300 b/m 2 = 150 b/m (about 155b/m) 3 = 100 b/m 4 = 75 b/m 5 = 60 b/m 6 = 50 b/m
PR Interval
0.12-0.2 sec (3-5 small squares)
HR <60, maybe >0.2 sec (>5 small squares)
QRS Complex
upright and narrow in Lead I & II (for a normal axis)
< 0.12 sec (<3 small squares)
T Wave
should be upright and rounded
Q-T Interval
should be <0.44 sec (normally between 0.4 and 0.44)
(1 - 11 small boxes)
ST Segment/J Point
should return to isoelectric line and NOT be elevated or depressed
J point is where S wave changes shape or direction
Lead Placement
RA = right arm (white)
LA = left arm (black)
RL = right leg (red)
LL = left leg (green)
V1 = RHS, 4th intercostal space, 1cm outside sternal border
V2 = LHS, 4th intercostal space, 1cm outside sternal border
V4 = 5th intercostal space, mid clavicular line
V3 = between V2 and V4
V6 = follow 5th intercostal space, mid axillar line
V5 = between V4 and V6
Pathological Q Wave
>1mm wide (1 small square); or
>2mm deep (2 small squares); or
>25% depth of preceeding QRS complex
indicates have had a previous STEAC or advancing STEAC or ACS
What are the 12 lead ECG orientation/groupings?
HISAL
Heart Vessels Lead I, aVL, V5 & V6
left circumflex coronary artery
Heart Vessels Lead aVR
aorta
Heart Vessels Lead V1, V2 V3 & V4
left anterior descending coronary artery
Heart Vessels Lead II, Lead III & aVF
right coronary artery
AV Heart Block Poem
1st Degree = far away P (long PR interval)
2nd Degree 1 = longer longer drop (PR gets longer then a QRS drop)
2nd Degree 2 = drop randomly (QRS drops)
3rd Degree = beat independently (no correlation between P and QRS)
starts at the end of the T wave and stops at the start of the next P Wave
TP Segment
starts at the beginning of the QRS complex and stops at the end of the T wave
QT Interval
What wave is atrial depolarisation
P Wave
What represents ventricular depolarisation
QRS Waves (QRS Complex)
What represents ventricular repolarisation
T Wave
(hides atrial repolarisation)
starts at the end of the P wave and ends at the start of the QRS complex
PR Segment
starts at the end of the QRS complex and ends at the start of the T wave
ST Segment
where the QRS complex ends and the start of the ST segment
J Point
starts at the beginning of the P wave and ends at the beginning of the QRS complex
PR Interval
interval between the tips of two consecutive QRS complexes
R-R
Which lead is used when monitoring the heart solely for rhythms?
Lead II (bipolar limb lead)
Limb Leads
I
II
III
vertical plane
AvR is the exact polar opposite of Lead II if normal conduction pathway
Augmented Leads
AvF
AvL
AvR
vertical plane
AvR is the exact polar opposite of Lead II if normal conduction pathway
Precordial Leads
V1-V6
horizontal plane
look inwards
Rhythm
is the distance between the R-R waves the same?
regular
irregular
regulary irregular
irregularly irregular
ST Segment MI Criteria
ST Segment Elevation
- Limb leads >1mm elevation in 2 contiguous leads
- Chest/Precordial leads >2mm elevation in 2 x contiguous leads
ST Segment Depression (reciprocal change)
- Limb leads >1mm elevation in 2 contiguous leads
- Chest/Precordial leads >2mm elevation in 2 x contiguous leads
Diagnosis Proforma
genesis of rhythm + heart rate + infarct pattern and reciprocal changes
eg: sinus rhythm at a rate of 90 with an inferior infarct
Septal Reciprocal Leads
Facing
V1, V2
Reciprocal
None
Anterior Reciprocal Leads
Facing
V3, V4
Reciprocal
None
Anteroseptal Reciprocal Leads
Facing
V1, V2, V3, V4
Reciprocal
None
Lateral Reciprocal Leads
Facing
I, aVL, V5, V6
Reciprocal
II, III, aVF
Anterolateral Reciprocal Leads
Facing
I, aVL, V3, 4, V5, V6
Reciprocal
II, III, aVF
Inferior Reciprocal Leads
Facing
II III, aVF
Reciprocal
I, aVL
Posterior Reciprocal Leads
Facing
None
Reciprocal
V1, V2, V3, V4
HISAL
H - High lateral - I, aVL
I - Inferior - II, III, aVF
S - Septal V1, V2
A - Anterior - V3, V4
L - Lateral - V5, V6
% of Right Ventricular Involvement STEMI/STEAC and its implications
33% - 50%
Right ventricular involvement is precaution for GTN due to right ventricle being preload dependant
When do you use V4R?
when inferior STEMI presents to ascertain right ventricular involvement
What indicates right ventricular involvement in STEMI/STEAC?
ST elevation greater in lead III than lead II
inferior STEMI/STEAC
How does V4R indicate right ventricular involvement?
ST elevation greater than 1mm (1 small box)
What does lack of P wave indicate?
impulse originates in atria, junction or ventricles
What indicates a posterior STEMI?
Deep and long T waves in V1 and V2
Components of haemodynamic stability
HR
BP
GCS
Difference between junctional rhythms and SVT
junctional rhythms typically regular, no P and narrow QRS
Difference between P or T if unsure
it is generally a T if it follows QRS
Three reasons for aVR to be positive
ventricular rhythm
incorrect lead placement
dextracardia (pt’s heart in chest wrong way)
What are the ECG features for LBBB?
- QRS duration > 120ms (0.12 sec)
- big, deep QRS in V1 and V2 (Dominant S wave in V1)
- Bunny ears in V5 and V6
- Absence of Q waves in lateral leads
What are the ECG features for RBBB?
- QRS duration > 120ms (0.12 sec)
- RSR in V1, V2, V3
- Wide, slurred S wave in lateral leads (I, aVL, V5-6)
Rate: 80
Rhythm:irregular
P Wave: upright, present, rounded and precedes each QRS
PR Interval: 0.12 sec (3 small boxes)
QRS: upright, narrow, 0.8 sec (2 small boxes)
ST: isoelectric
T: inversion in lead VR
Groupings: nil
Interpretation:
Sinus arrhythmia at rate of 80bpm
Rate: 58
Rhythm: regular
P Wave: none
PR Interval: unknown
QRS: wide >0.12, prolonged QT
ST: isolectric
T Wave: ok
Groupings: RSR V1, wide slurred S V6, terminal R wave aVR
Interpretation: sinus bradycardia @ 58 with RBBB and prolonged QT interval
Flecainide (cardiovascular drug) OD
Rate: 62
Rhythm: regular
P Wave: present, upright rounded, precedes each QRS
PR Interval: prolonged >0.2 sec
QRS: wide >0.12 sec
ST: isoelectric
T: ok
Groupings: LAFB I, aVL, II, III, aVF, RBBB V1 V2
Interpretation: sinus rhythm @ 62 with borderline 1st degree AV block and bifascicular block (RBBB & LAFB)
Beta blocker toxicity
What is the ECG criteria for Left Anterior Fascicular Block (LAFB)?
- Left axis deviation (usually -45 to -90 degrees)
- qR complexes in leads I, aVL
- rS complexes in leads II, III, aVF
- Prolonged R wave peak time in aVL > 45ms
Rate: 73
Rhythm: regular
P Wave: present, upright, rounded, precedes each QRS
PR Interval: prolonged >0.2 sec
QRS: wide >0.12 sec
ST: isoelectric
T: ok
Groupings: nil
Interpretation: sinus rhythm @ 73 with 1st degree block, RAD & terminal R wave in aVR
Propanolol toxicity
Rate: 47
Rhythm: regular
P Wave: present, upright rounded, precedes each QRS
PR Interval: 0.2 sec
QRS: narrow <0.12 sec, prolonged QT >0.44 sec
ST: isoelectric
T: ok
Groupings: nil
Interpretation: sinus bradycardia @ 47 with prolonged QT interval
Sotalol toxicity (K+ & Beta blockers)
Rate: 80
Rhythm: irregular
P wave: present, dissociated
PR interval: unknown
QRS: accelerated junctional complex
ST: isoelectric
T: ok
Groupings: nil
Interpretation: sinus rhythm @ rate 80 with av dissociation and accelerated junctional complex
Verapamil toicity (Ca++)
What does the QRS interpretation include?
- QRS after each P-wave
- QRS duration 0.08 – 0.10s (2 to 2.5 small squares)
- Q-waves
- QT interval
- Normal R-wave progression in V1 to V6
- Cardiac axis (Normal or deviated)
What leads do you use to interpret cardiac axis?
I
II
III or aVF
What is the normal axis?
QRS axis between -30° and +90°
What is left axis deviation (LAD)?
QRS axis less than -30°
What is right axis deviation (RAD)?
QRS axis greater than +90°
What is Extreme Axis Deviation?
QRS axis between -90° and 180° (AKA “Northwest Axis”)
Is this positive, equiphasic or negative?
positive
Is this positive, equiphasic or negative?
equiphasic
Is this positive, equiphasic or negative?
negative
What is the axis?
Lead I - positive
Lead II - positive
Lead III - positive
normal axis
(0 to +90°)
What is the axis?
Lead I - positive
Lead II - equiphasic
Lead III - positive
LAD
physiological
(0 to -30°)
What is the axis?
Lead I - positive
Lead II - negative
Lead III - negative
LAD
pathological
(-30° to -90°)
What is the axis?
Lead I - negative
Lead II - positive
Lead III - positive
RAD
(90° to 180°)
What is the axis?
Lead I - negative
Lead II - negative
Lead III - negative
Extreme Axis
(-90° to -180°)
What is the axis?
Lead I - equiphasic
Lead II - equiphasic
Lead III - equiphasic
Indeterminate
(?)
What are the ECG features of hyperkalaemia?
- P wave widening/flattening
- PR prolongation
- QRS widening with bizarre QRS morphology
- Peaked T waves
- Bradyarrhythmias: sinus bradycardia, high-grade AV block with slow junctional and ventricular escape rhythms, slow AF
- Conduction blocks (bundle branch block, fascicular blocks)
What ECG changes do you see in Hyperkalemia?
Wide, flat P Wave
Prolonged PR Interval
Widened QRS interval
Tall, peaked T wave
What ECG changes do you see in Hypokalemia?
Inverted T wave
Prolonged U wave
What does left axis deviation mean?
the electrical activity in the heart is traveling towards the left side of the heart, rather than the normal direction towards the right
What conditions can cause left axis deviations?
left ventricular hypertrophy
RBBB
What does right axis deviation mean?
the electrical activity in the heart is traveling towards the right side of the heart, rather than the normal direction towards the left
What conditions can cause right axis deviation?
right ventricular hypertrophy
LBBB
What can cause left axis deviation (LAD)?
Left Ventricular Hypertrophy
LBBB
Inferior AMI
Short and or obese people
Ventricular Pacing
Wolfe Parkinson White syndrome
What can cause right axis deviation (RAD)?
Right Ventricular Hypertrophy
Lateral AMI
Tall thin people
COPD
Pulmonary embolism
Paeds
What can cause extreme axis deviation (RAD)?
Severe Right hypertrophy
Accelerated Idioventricular Rhythm (AIVR)
Idoventricular Rhythm (IVR)
Hyperkalemia
VT
What are the ECG features of a sinus rhythm?
regular rhythm HR between 60-100
Narrow QRS complex
What are the ECG features of atrial fibrillatin?
irregularly irregular rhythm
What are the ECG features of supraventricular tachycardia (SVT)?
regular rhythm
HR >100 (usually >150)
nil P waves or retrograde P waves
What are the ECG features of VT?
essentially regular rhythm
HR >100 (commonly >120)
bizarre wide QRS complex >0.12sec (3 small squares)
What are the ECG features of a 1st degree AV block?
prolonged PR interval >0.2 sec (>5 small squares)
What are the ECG features of a 2nd degree AV block Type 1?
gradually increasing PR interval then dropped beat
What are the ECG features of a 2nd degree AV block Type 2?
Constant PR interval then dropped beats (various ratios)
What are the ECG features of a 3rd degree AV block?
complete dissociation
What ECG changes do you see in unstable angina?
possibly:
hyperacute T-waves
flattening of the T-waves
inverted T-waves
ST depression
What ECG changes do you see in a NSTEMI?
transient ST elevation
ST depression
new T wave inversions
Provide your interpretation of this ECG
Rate: 85bpm
Rhythm: regular
P Wave: present, upright, rounded, precedes each QRS
PR Interval: 0.16 sec
QRS: upright, narrow
ST: >1mm I & aVR, >2mm V1-V4
Sinus rhythm @ rate of 85 with anteroseptal ST elevation with reciprocal changes
Provide your interpretation of this ECG
Ventricular Tachycardia
Provide your interpretation of this ECG
Evolving anterolateral STEMI or extensive anterior STEMI (there are tombstone in all V leads)
Provide your interpretation of this ECG
Pulseless Electrical Activity (PEA)
Provide your interpretation of this ECG
Fine VF
Provide your interpretation of this ECG
Interpret this ECG
Rate: 70bpm
Rhythm: irregular
P wave: not present
QRS: wide @ 0.16 sec
ST: OK
Other: QRS notching in 1, aVL, V5 and V6
Atrial fibrillation @ rate of 70 with LBBB
Diagnose this ECG in a Pt with no pulse
PEA
(pulseless electrical activity)
Diagnose this ECG
Rate: 130bpm
Rhythm: regular
P wave: present, upright, rounded precedes each QRS
PR interval: 1.04 second, wide/abnormal
QRS complex: 0.12 second, normal
ST: normal
Sinus tachycardia @ rate of 130 bpm
Interpret this ECG
Rate: 150
Rhythm: 150
P Wave: present, upright, rounded, precedes each QRS
PR Interval: 0.12sec
QRS: upright, narrow, 0.08sec
ST: NAD
Sinus rhythm @ rate 150
Interpret this ECG
Rate: 170
Rhythm: regular
P Wave: present, upright, precedes each QRS
PR Interval: <0.2 second
QRS: upright narrow 0.08 second
ST: OK?? Slight depression?
Sinus tachycardia @ rate of 170
Interpret this ECG
Rate: 70
Rhythm: regular
P Wave: present, upright, rounded, precedes each QRS
PR Interval: normal 0.15 second
QRS: 0.12 second
ST: NAD
Other: LBBB
Sinus rhythm @ rate 70
Diagnose this ECG
Rate: 60bpm
Rhythm: regular
P Wave: present, upright, rounded
PR Interval: wide 0.26 sec
QRS: Wide 0.2sec
ST: NAD
Other: R wave aVR, Notched QRS in V3 – V6
Sinus rhythm @ rate of 60 with 1st degree block
Diagnose this ECG
Rate: 190bpm
Rhythm: regular
P Wave: present, upright, rounded, precedes each QRS
PR Interval: 0.12 seconds
QRS: upright, narrow, 0.08 seconds
ST: depression in I II III AVf V3 V4 5 V6
Narrow complex tachycardia @ 190 bpm with global ST depression likely rate related
Interpret this ECG
Rate: 90bpm
Rhythm: regular
P waves: present upright rounded, precedes each QRS
PR interval: long 0.204seconds
QRS: upright narrow
ST: 1mm elevation in V3 and V4
Other: 1st degree block
Sinus rhythm @ rate of 90 with first degree block
