The axis presentation

The ECG AxisAdam Thompson, EMT-P

WARNING

Axis determination is not as difficult to understand as people think. It is the foundation of ECG interpretation. Don’t try to understand everything, choose the method that suits you best!

Cardiology Stuff

Please ask questions!!

Don’t worry, I’ll explain this stuff

The 6-Step Method

• 1. Rate & Rhythm• 2. Axis Determination• 3. Intervals• 4. Morphology• 5. STE-Mimics• 6. Ischemia, Injury, & Infarct

45 y/o Male with Chest Pain

Pathologies

Frontal 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• WPW

• Sometimes Normal, especially in women• Anterior MI• LVH• LAFB• LBBB• Lung Disease

Ventricular Axis

Ventricular Depolarization

What’s Normal?

• The normal QRS Axis is about 60°• This can vary, and the normal range is between 0° to 90°

I+0°

I-

II+

III-

III+

II-

aVR-

aVR+

aVF+

aVF-

aVL+

aVL-

30°

-30°

60°90°

120°

150°

+/-180°

-150°

-120°

-90°-60°

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 Law

I + (-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

– Plug the numbers in.

I + (-II) + III = 0

5 + 10 -15 = 0

Einthoven’s Law

The equilateral triangle

Electrical Axis

Ventricular depolarization

Mean Vector

Mean Vector

The Hexaxial Reference System

I

IIIII

Hexaxial Diagram

Hexaxial Diagram

I

IIIII aVF

aVLaVR

I+0°

I-

II+

III-

III+

II-

aVR-

aVR+

aVF+

aVF-

aVL+

aVL-30°

-30°

60°90°120°

150°

+/-180°

-150°

-120°-90° -60°

The Hexaxial Reference System

I+0°

I-

II+

III-

III+

II-

aVR-

aVR+

aVF+

aVF-

aVL+

aVL-30°

-30°

60°

90°120°

150°

+/-180°

-150°

-120°

-90°-60°

The Hexaxial Method

We only need to concentrate on the first six leads

The Hexaxial Method

The Hexaxial Method

Step 1: Find the equiphasic lead

I+0°I-

II+

III-

III+

II-

aVR-

aVR+

aVF+

aVF-

aVL+

aVL-

30°

-30°

60°90°120°

150°

+/-180°

-150°

-120°

-90° -60°

Step 4: Is the perpendicular lead positive or negative?

QRS Axis

ERAD LAD

RAD Normal

180 0

-90

90

The Hexaxial Method

The Hexaxial Method

Let’s try another one

The Quadrant Method

ERAD LAD

RAD Normal

180 0

-90

90

Quadrant Method

- I I +

aVF -

Negative QRS Complex in aVF

Positive QRS Complex in aVF

aVF +

- I I +

aVF +

aVF -

Positive QRS in Lead I

Negative QRS in Lead I

Quadrant method

Is Lead I up or down?

Quadrant Method

- I I +

aVF +

aVF -

Quadrant method

Is aVF up or down?

Quadrant Method

- I I +

aVF +

aVF -

Quadrant Method

- I I +

aVF +

aVF -

ERAD LAD

RAD Normal

180 0

-90

90

Quadrant Method

Frontal Plane Axis Pathologies

Print Master

Fascicular Block

If all else fails…

Precordial Axis

Limb Leads Precordial Leads

Lead I aVR V1 V4

Lead II aVL V2 V5

Lead III aVF V3 V6

Pathologies


ERAD-90 to 180



-30 to -90


Rotation







The Precordial Axis

V1

V2

V3

V4

V5V6

Precordial Axis

Normal R-wave progression

Precordial Axis

Early R-wave progression

Precordial Axis

Late R-wave progression

Bundle Branch Blocks


1

2

3

Left Bundle Branch Block

V1


1

2

3

Right Bundle Branch Block

V1


V1

V1


= RBBB

= LBBB

V1

V1 GT

BBBs

BBBs

RBBB Morphologies

LBBB Morphologies

Pathologies


ERAD-90 to 180



-30 to -90


Rotation









Practice

Practice

Practice

Pathologies


ERAD-90 to 180



-30 to -90


Rotation







45 y/o Male with Chest Pain

The End

Questions?

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The axis presentation