Electrical Flowof the Heart

NRSG450 Module Two

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Background of Electrical Flow of the Heart

• The flowing electricity is summarized to give a general direction. This is called the vortex.

• The vortex is the electrical direction viewed on the monitor.

• Electrical flow toward a positive electrode gives a upward deflection. Flow away from the positive electrode gives a downward deflection.

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Lead II

+

-

Background of Electrical Flow of the Heart

• The electrical activity of the heart is examined from several different views or directions, commonly called leads.

• The common leads are six limb leads and six chest leads. Many more leads are possible and are used in special situations.

• Most patients with a non-cardiac condition are monitored in Lead II.

• Cardiac patient monitoring is based on the expected problems, usually MCL1 &/ MCL 5/6

Reading Electrical Flow of the Heart• 12 Lead EKG

I

IIII

III

AVR

AVL

AVF

VI or MCLI

V2 or MCL2

V3 or MCL3

V4 or MCL4

V5 or MCL5

V6 or MCL6

Lead II monitoring strip

Reading the Electric Flow of the Heart

The EKG Rhythm Strip

• A straight line is called the isoelectric line. It is seen when no electrical flow is detected in the heart.

Reading the Electrical Flow of the Heart

Reading the Electrical Flow of the Heart

The electrical activity of the heart is picked up be electrodes, travels through the wires to a heated stylus and transferred to specially designed EKG paper.

Reading the Electrical Flow of the Heart

• EKG is recorded on graph paper traveling at 25mm per second

• The horizontal axis is time.– 1 small block=1mm=0.04 sec– 5 small blocks= 1 big block =

5mm = 0.2 sec– 5 big blocks = 1 second– 30 big blocks = 6 seconds

• The vertical axis is voltage.– 1 small block = .01 mv– 10 small blocks=2 big blocks = 1

mv

Reading the Electrical Flow of the Heart

• One heart beat or an electrical wave propagation

Depolarization wave

Heart muscle contraction

Reading the Electrical Flow of the Heart

San

San Diego Paramedics

Reading the Electrical Flow of the Heart

DRAG LABELS TO CORRECT LOCATION AND REBUILD

THE CHART

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Anchoring the Information• Label the waves.

p

p

p

p

p

p

p

p p

p

p p

p

p

p

qrs qrs

qrs qrs

qrs qrs

qrs qrs

qrs

qrs

qrs

qrs

T

T T

TT

T T

T

T

T

T

T

pr

pr = 0.44

pr = 0.20

= 0.12

QRS = .06

QRS = o.o4

QRS = o.o6

DRAG LABELS TO CORRECT LOCATION AND REBUILD

THE CHART

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Reading the Electrical Flow of the Heart

• p wave = atrial depolarization• Accounts for the time electrical

stimulation moves across the atria.

• Duration 0.06 – 0.12 sec (2 small blocks> 4 small blocks)

• Located before QRS complex• Height 2-3 mm (0.2-0.3 mv)• Shape rounded & positive

(upright)

Suran Dutsan@ rutgers.edu

Reading the Electrical Flow of the Heart

• PR interval involves the atrial and nodal depolarization

• Measure from beginning of p wave to the beginning of the QRS

• Duration 0.12 – 0.20 sec

Reading the Electrical Flow of the Heart

• Ventricular depolarization is represented by the QRS complex

location

Location follows the PR interval.Duration 0.06 - 0.12 secondsAmplitude dependent on Lead (~5-30 mm)Configuration dependent on Lead Deflection usually a combination of negative and positive, varies with leads

Schwimmin

Reading the Electrical Flow of the Heart

• ST segment from the end of the S wave to the beginning of T wave

• Usually isoelectric, • May be from -0.5 - +1 mm

from the isoelectric line

Reading the Electrical Flow of the Heart

• T wave is ventricular repolarization

Location follows the s waveConfiguration is round & smooth (looks like a big p wave)Deflection is usually positive

Reading the Electrical Flow of the Heart

• QT segment is measured from the beginning of the QRS complex to the end of the T wave.

• Duration is rate dependent

• Not routinely measured

Reading theElectrical Flow of the Heart

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