12 lead-lesson 2
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Transcript of 12 lead-lesson 2
12-Lead 12-Lead ElectrocardiographyElectrocardiography
a comprehensive course
Adam Thompson, EMT-P, A.S.Adam Thompson, EMT-P, A.S.
Lesson
2
Resources
• http://www.blaufuss.org/ECGviewer/indexFrame2.html• ems12lead.com/
The 6-Step Method
• 1. Rate & Rhythm1. Rate & Rhythm
• 2. Axis Determination2. Axis Determination
• 3. Intervals3. Intervals
• 4. Morphology4. Morphology
• 5. STE-Mimics5. STE-Mimics
• 6. Ischemia, Injury, & Infarct6. Ischemia, Injury, & Infarct
Lesson Two
• Frontal Axis determination tutorial
• Precordial Axis rotation
• Pathologies that cause axis deviation
Objectives
• Learn how to determine the frontal axis.
• Distinguish between the different causes of axis deviation.
• Learn how to identify rotation of the precordial axis.
Axis Determination
• Critical Skill!• Use the hexaxial reference system for
the frontal plane.• Identify clockwise or counterclockwise
rotation of R-wave progression.
PathologiesFrontal Plane Axis Precordial Axis
ERAD-90 to 180
Right Axis Deviation90 to 180
Pathological Left Axis Deviation-30 to -90
Early TransitionCounterclockwise
Rotation
Late TransitionClockwise Rotation
• Ventricular Rhythm• Paced Rhythm• Dextrocardia• Electrolyte derangement
• May be normal• LPFB• Pulmonary disease• RVH• RBBB• WPW• Dextrocardia•Venrticular Rhythm
• Pregnancy• LAFB• WPW• Pulmonary disease• LBBB• Hyperkalemia• Q-waves, MI
• Posterior wall infarction• RVH• RBBB
• Sometimes Normal, especially in women• Anterior MI• LVH• LAFB• LBBB• Lung Disease
Willem Einthoven
Won the Nobel Prize in Physiology or Medicine in 1924 for inventing the string galvanometer which was the first EKG.
Einthoven’s Triangle
• Electrically, leads I, II, & III form an equilateral triangle.
• Einthoven’s LawI + (-II) + III = 0
Einthoven’s Law
• How it works
• Lead I– The R wave is about 7 1/2 mm tall.– The S wave is about 2 1/2 mm deep.
– Subtract the S wave from the R wave • you come up with 5 mm.
Einthoven’s Law
• Lead I = 5mm
• Lead II– It’s essentially a monophasic
QS complex. – About -10 mm.
Einthoven’s Law
• Lead I = 5mm
• Lead II = -10mm
• Lead III– R wave that is about 1 mm high.– The S wave is about 16 mm deep. – Subtract the S wave from the R wave.– -15 mm.
Einthoven’s Law
• Lead I = 5mm
• Lead II = -10mm
• Lead III = -15mm
Einthoven’s Law
• Lead I = 5mm
• Lead II = -10mm
• Lead III = -15mm– Plug the numbers in.
• I + (-II) + III = 0• 5 + 10 -15 = 0
Einthoven’s Law
The equilateral triangle
Electrical Axis
What is the heart’s electrical axis?
The first area to depolarize (1) is the interventricular septum
1
3
22
3
4
Mean vector
Cardiac vector
Electrical Axis
What is the heart’s electrical axis?
Next, the area around the left and right ventricular apex (2) depolarizes from a endocardial-to-epicardial direction (inside-out).
1
3
22
3
4
Mean vector
Cardiac vector
Electrical Axis
What is the heart’s electrical axis?
Finally, the lateral walls of the left and right ventricle depolarize (3) and last the high lateral wall of the left
ventricle (4).
1
3
22
3
4
Mean vector
Cardiac vector
Electrical Axis
What is the heart’s electrical axis?
The big arrow is the heart’s mean (average) electrical vector. If you averaged the millions of cardiac vectors,
you would get the “mean vector”.
1
3
22
3
4
Mean vector
Cardiac vector
Mean Electrical Vector
+
+
+ A B A
B
Mean vector moves towards positive electrode = positive QRSMean vector moves towards positive electrode = positive QRSMean vector moves away from positive electrode = negative QRSMean vector moves away from positive electrode = negative QRSMean vector is perpendicular to positive electrode = equiphasic QRSMean vector is perpendicular to positive electrode = equiphasic QRS
Mean Electrical Vector
Red arrow is heart’s
mean electrical vector
Mean Electrical Vector
Lead I views the heart’s
Vector similar to the
image on the left.
Leads II & III do the same
from their angles.
Einthoven’s Triangle
=
Hexaxial Reference System
The arrows and lead
names are placed on
the side of the
positive electrode.
I
IIIII
Hexaxial Reference System
The augmented leads provide the other 3 leads of the hexaxial reference system.
Hexaxial Reference System
Hexaxial Reference System
I
IIIII
+
aVF
aVLaVR
=
Hexaxial Reference System
Hexaxial Reference SystemHexaxial Reference System
QuickTime™ and ampeg4 decompressor
are needed to see this picture.
Hexaxial Reference System
• Lead I cuts through body horizontally
• aVF cuts through body vertically• II, III, aVF are inferior• III & aVL are reciprocal
Hexaxial Reference System
How to use it
Hexaxial Reference System
Find the most equiphasic lead
Hexaxial Reference System
Find the most equiphasic lead
Hexaxial Reference System
• When the mean axis is perpendicular to the positive electrode, the QRS is equiphasic.
+
+
+ A B A
B
Hexaxial Reference System
Find Lead I on the
reference diagram.
Find the lead
perpendicular to
Lead I
Hexaxial Reference System
Find Lead I on the
reference diagram.
Find the lead
perpendicular to
Lead I
Hexaxial Reference System
Look at aVF, is it positive or negative?
Hexaxial Reference System
Since aVF is positive,
look at the measure
next to the side with
the up arrow.
Axis is about +90
Hexaxial Reference System
About +90
Axis Determination
• Is that too much work?• You’re first time is always the hardest.• The more you do this, the easier it is to
do.• Eventually, you won’t need any
diagrams.
Axis Determination
Lets practice…
Axis Determination
Find the most equiphasic lead.
Axis Determination
Looks like Lead II…
Axis Determination
Lead aVF
Axis Determination
Which lead is
perpendicular to
aVF?
Axis Determination
Which lead is
perpendicular to
aVF?
Axis Determination
Is Lead I positive or negative?
Axis Determination
Since Lead I is
Positive, the
axis is about 0
Axis Deviation
• So what is a normal axis?
• Why does it matter if an axis is deviated?
Normal Axis
• The normal quadrant for the QRS axis is the Southeast quadrant.
• From 0 to 90
Left Axis Deviation
• From -90 to 90• This is considered the
Northeast quadrant.
Left Axis Deviation
• From 0 to -30• This is considered
physiological left axis deviation
• Pathological axis deviation is from -30 to -90
• Most common cause is left anterior fascicular block
Right Axis Deviation
• From 90 to -180• Negative QRS in Lead I • Positive QRS in aVF
– Possible Left Posterior Fascicular Block
– Q-Waves from lateral MI– Right Ventricular
Hypertrophy– Pulmonary Disease.
Extreme Right Axis Deviation
• Called ERAD• From -90 to -180• QRS in I, II, & III are negative• Probably ventricular
– Idioventricular– Paced rhythm
Cheat SheetNormal
Axis
0 to 90
Physiologic
Left
0 to -30
Pathologic
Left
-30 to -90
Right Axis
90 to 180
Extreme Right Axis
-90 to 180
Indeterminate
Axis
?
Lead I
Lead II
Lead III
Practice
Look at leads I, II, & III
Cheat SheetNormal
Axis
0 to 90
Physiologic
Left
0 to -30
Pathologic
Left
-30 to -90
Right Axis
90 to 180
Extreme Right Axis
-90 to 180
Indeterminate
Axis
?
Lead I
Lead II
Lead III
Practice
Normal Axis
Practice
Normal Axis
Practice
Which lead is equiphasic?
Practice
Which lead is equiphasic?
Practice
• Lead aVL is equiphasic
• Lead II is perpendicular to aVL
• Lead II is positive
Practice
About 60?
Quadrant Method
• Much easier to do. • Faster and more practical for rapid
interpretation. • Does not give you a very close
estimate.
Quadrant Method
ERAD LAD
RAD Normal
180 0
-90
90
Quadrant Method
ERAD LAD
RAD Normal
- I I +
aVF +
aVF -
Quadrant Method
- I I +
aVF +
aVF -
Positive QRS in Lead I
Negative QRS in Lead I
Practice
Lets take a look
Quadrant Method
- I I +
aVF +
aVF -
Quadrant Method
aVF +
- I I +
aVF -
Negative QRS Complex in aVF
Positive QRS Complex in aVF
Practice
Lets take a look
Quadrant Method
- I I +
aVF +
aVF -
Quadrant Method
- I I +
aVF +
aVF -
Quadrant Method
ERAD LAD
RAD Normal
180 0
-90
90
Quadrant Method
Lead I aVF
Normal Positive (+) Positive (+)
RAD Negative (-) Positive (+)
LAD Positive (+) Negative (-)
ERAD Negative (-) Negative (-)
Frontal Axis
Modern 12-Lead monitors do a pretty good job estimating the QRS Axis.
Frontal Axis
Precordial Axis
• Sometimes called Z axis
• Clockwise or Counterclockwise rotation
Precordial Axis
Precordial Leads = V Leads
Sometimes called Chest Leads
Precordial Axis
• The main impulse travels down then to the left.
1
3
22
3
4
Mean vector
Cardiac vector
Precordial Axis
1
3
22
3
4
Mean vector
Cardiac vector
V1 V2
V3V4 V5
V6
Precordial Axis
Lets pretend the impulse is a delivery truck that has a positive front end and a negative back end.
+-
Precordial Axis
Precordial Axis
V1 V2 V3 V4 V5 V6
Precordial Axis
V1 V2 V3 V4 V5 V6
+
Precordial Axis
V1 V2 V3 V4 V5 V6
+
Precordial Axis
V1 V2 V3 V4 V5 V6
+-
Precordial Axis
V1 V2 V3 V4 V5 V6
+-
Precordial Axis
V1 V2 V3 V4 V5 V6
+-
Precordial Axis
V1 V2 V3 V4 V5 V6
+-
Prec ordial Axis
V1 V2 V3 V4 V5 V6
+-
Precordial Axis
V1 V2 V3 V4 V5 V6
+-
Precordial Axis
• The normal transition zone is between V3 and V4.
• V1 should be predominately negative.
• V6 should be mostly positive.
Precordial Axis
Lets take a look at a 12-lead
Precordial Axis
Is V1 mostly negative?
Precordial Axis
Is V6 mostly positive?
Precordial Axis
Where is the transition?
Precordial Axis
The Precordial Axis is Normal
Precordial Axis
Now picture the precordial leads in this pattern.
V1
V2
V3
V4
V5V6
Precordial Axis
V1
V2
V3
V4
V5V6
Normal transition
Precordial Axis
V1
V2
V3
V4
V5V6
Early transition = Counterclockwise Rotation
Precordial Axis
V1
V2
V3
V4
V5V6
Late transition = Clockwise Rotation
Precordial Axis
Precordial Axis
Early Transition - Counterclockwise Rotation
Precordial Axis
Early Transition - Counterclockwise Rotation
Precordial Axis
Another Example
Precordial Axis
Late Transition - Clockwise Rotation
PathologiesFrontal Plane Axis Precordial Axis
ERAD-90 to 180
Right Axis Deviation90 to 180
Pathological Left Axis Deviation-30 to -90
Early TransitionCounterclockwise
Rotation
Late TransitionClockwise Rotation
• Ventricular Rhythm• Paced Rhythm• Dextrocardia• Electrolyte derangement
• May be normal• LPFB• Pulmonary disease• RVH• RBBB• WPW• Dextrocardia•Venrticular Rhythm
• Pregnancy• LAFB• WPW• Pulmonary disease• LBBB• Hyperkalemia• Q-waves, MI
• Posterior wall infarction• RVH• RBBB
• Sometimes Normal, especially in women• Anterior MI• LVH• LAFB• LBBB• Lung Disease
Fascicles
• Right Bundle Branch– 1 Fascicle
• Left Bundle Branch– 2 Fascicles
• Left Anterior• Left Posterior
Fascicular Blocks
Left AnteriorFascicular Block
Left PosteriorFascicular Block
Fascicular Block
• Bifascicular Block– Right Bundle Branch Block (RBBB) with either:
• Left Anterior Fascicular Block (LAFB)• Left Posterior Fascicular Block (LPFB)
– Only one fascicle remaining
• Trifascicular Block– RBBB with LAFB/LPFB and 1st degree AV Block– May degrade into lethal arrhythmia rapidly
Practice
Practice
Identify the rate & regularity
Practice
Identify the rate & regularity
Practice
Identify the rate & regularity
Practice
Identify the rate & regularity
1 2 3
Practice
Identify the rate & regularity
1 2 3
300 ÷ 3 = 100
Practice
Identify the rhythm
HR ≈ 100
Practice
Identify the rhythm
HR ≈ 100
Practice
Identify the rhythm
HR ≈ 100
Practice
Normal Sinus Rhythm
HR ≈ 100
Normal Sinus
Practice
Frontal Axis?
HR ≈ 100
Normal Sinus
Practice
Frontal Axis?
HR ≈ 100
Normal Sinus
Practice
Frontal Axis?
HR ≈ 100
Normal Sinus
Practice
• Equiphasic lead is aVF.
• Find lead perpendicular to aVF
Practice
• Equiphasic lead is aVF.
• Find lead perpendicular to aVF
Practice
Frontal Axis?
HR ≈ 100
Normal Sinus
Practice
• Lead I is positive
• Frontal axis is about 0
Practice
• Lead I is positive
• Frontal axis is about 0
• That is in normal quadrant.
Practice
Frontal Axis = Normal, about 0
HR ≈ 100
Normal Sinus
Frontal axis is normal
Practice
Precordial Axis
HR ≈ 100
Normal Sinus
Frontal axis is normal
Practice
Early Transition, Counterclockwise Rotation
HR ≈ 100
Normal Sinus
Frontal axis is normal
Practice
Lets try another
Practice
Practice
Determine Rate & Rhythm
Practice
Determine Rate & Rhythm
HR ≈ 75
Normal Sinus
Practice
Determine Frontal Axis
HR ≈ 75
Normal Sinus
Quadrant Method
ERAD LAD
RAD Normal
180 0
-90
90
Practice
Determine Frontal Axis
HR ≈ 75
Normal Sinus
Quadrant Method
Lead I aVF
Normal Positive (+) Positive (+)
RAD Negative (-) Positive (+)
LAD Positive (+) Negative (-)
ERAD Negative (-) Negative (-)
Cheat SheetNormal
Axis
0 to 90
Physiologic
Left
0 to -30
Pathologic
Left
-30 to -90
Right Axis
90 to 180
Extreme Right Axis
-90 to 180
Indeterminate
Axis
?
Lead I
Lead II
Lead III
Practice
Determine Frontal Axis
HR ≈ 75
Normal Sinus
Practice
Determine Precordial Axis
HR ≈ 75
Normal Sinus
Pathological Left Axis
Precordial Axis
V1
V2
V3
V4
V5V6
Early transition = Counterclockwise Rotation
Practice
Determine Precordial Axis
HR ≈ 75
Normal Sinus
Pathological Left Axis
Counterclockwise Z
PathologiesFrontal Plane Axis Precordial Axis
ERAD-90 to 180
Right Axis Deviation90 to 180
Pathological Left Axis Deviation-30 to -90
Early TransitionCounterclockwise
Rotation
Late TransitionClockwise Rotation
• Ventricular Rhythm• Paced Rhythm• Dextrocardia• Electrolyte derangement
• May be normal• LPFB• Pulmonary disease• RVH• RBBB• WPW• Dextrocardia•Venrticular Rhythm
• Pregnancy• LAFB• WPW• Pulmonary disease• LBBB• Hyperkalemia• Q-waves, MI
• Posterior wall infarction• RVH• RBBB
• Sometimes Normal, especially in women• Anterior MI• LVH• LAFB• LBBB• Lung Disease
Lesson Two
“Its finally over”
…Well almost.
More to come in lesson three.