EKG Basic

P wave represents the combined depolarization of the atria

0.04 sec long

• 1 big box
• 5 mm high
• 0.2 sec long

• 6 sec long
• Typical view
• multiply by 10 to get heart rate

• Represents the pause while the AV node holds the impulse from the atria
• Allows the complete contraction of the atria
• Should be between .12 - .20 seconds

• Represents the depolarization of the ventricles and the repolarization of the atria
• Repolarization of the atria is hidden by the huge electrical discharge of the ventricles
• Should be less than .12 seconds

first negative deflection after P wave

First positive after P wave

Negative deflection below baseline after R or Q wave

Represents the repolarization of the ventricles

Contains the absolute and relative refractory periods

Juncture point- Where the QRS complex ends and ST begins

• LA Left ARM Black
• LL Left LEG Red
• RA Right ARM White
• RL Right LEG Green
• "Smoke over fire, Snow over Grass"

V1 – V6

4th intercostal space, right of sternum

4th intercostal space, left of the sternum

between V4 and V2

5th intercostal space, mid-clavicular line

lateral to V4, anterior axillary line

lateral to V5, mid-axillary line

Sinoatrial or Sinus Node

Located in the Right Atrium near the Vena Cava

Serves as the heart’s pacemaker

Anterior, middle, and posterior pathways

Transmits the impulse from the SA to AV node through the atria

Found in the walls of the Right Atrium and Septum

Artioventricular Node

Located in the wall of the Right Atrium near the Tricuspid Valve

Responsible for slowing down conduction from the atria to the ventricles

Allows for the “atrial kick” to occur before the ventricles contract

• The portion of the electrical system from the AV node to the Bundle Branches
• Found partially in the lower wall of the Right Atrium and in the Septum

Only route of communication between the atria and ventricles

Begins at the Bundle of His and runs down into the Left Ventricle

The upper portion has fibers that innervate the Left Ventricle and the upper portion of the Septum

First area of the ventricles to fire

Breaks into the Left Anterior and Left Posterior Fascicles

Ends in the Purkinje fibers

Begins at the Bundle of His and runs down into the Right Ventricle

Terminates at the Purkinje fibers

Individual cells just beneath the endocardium

Directly innervate the myocardial cells

Initiate the ventricular depolarization cycle

Help fill the ventricles

Push blood out of the heart

Brings blood back into the heart from the body

Takes blood to the lungs

Brings blood from the lungs into the heart

Takes blood to the body

• Right Atrium
• Tricuspid Valve
• Right Ventricle
• Pulmonic Valve
• Pulmonary Artery
• Lungs

• Pulmonary Veins
• Left Atrium
• Mitral Valve
• Left Ventricle
• Aortic Valve
• Aorta