12-Lead Electrocardiography

a comprehensive course

Adam Thompson, EMT-P, A.S.

Axis

Practice

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

Axis0 to 90

PhysiologicLeft

0 to -30

PathologicLeft

-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

END

1. Rate & Rhythm2. Axis Determination3. Intervals4. Morphology5. STE-Mimics6. Ischemia, Injury, & Infarct