Cardiac Monitoring Skills
Module One
NRSG450
Goals
• Student Will Be Able To Discuss Cardiac Monitoring And Correctly
Place Chest Leads.
• Student Will Be Able To Interpret A Rhythm Strip For Cardiac Rate,
Wave Morphology, Direction, Duration And Relationships To Other
Waves.
• Student Will Recognize Normal From Abnormal Rhythms.
• Student Will Recognize Basic Sinus, Atrial, Junctional And
Ventricular Rhythm Variations.
• Student Will Identify Lethal Rhythms.
Background of Electrical Flow of
the Heart
Electricity stimulates the heart muscle to contract. It
spreads through the heart sequentially changing the
polarity of the cell’s interior from negative to positive
(depolarization). This causes contraction of the muscle. The
internal cell positive polarity changes back to negative
(repolarization) and the muscle relaxes. This process
proceeds through cell-to-cell communication and high speed
tracts in the atria and ventricles.
www.guidant.com
Anchoring the Information
• Electricity stimulates the heart muscle to contract.
• The internal cell is Negatively charged at rest.
• Stimulating the change of the cell’s internal and external
polarity is called Depolarization.
• Depolarization produces Contraction of the muscle.
• Repolarization is the return of the internal cell negative
polarity and muscle Relaxation.
• Depolarization and repolarization occur Sequentially.
• These processes proceed through Cell-to-cell
communication and high speed tracts.
TAKE THE QUIZ ON THE NEXT SLIDE AND TEST YOUR
KNOWLEDGE OF WHAT YOU HAVE JUST LEARNED.
Action Potential Curve
Background of Electrical Flow of
the Heart
Butler.cc.tut.fi
Intracellular
Cell wall
Extracellular
Depolarization-repolarization involves the exchange movement
of sodium and potassium across the cell wall with calcium
modulation. This exchange sets the rate of the electrical
spread. This process, including a rest period, is called the
action potential curve.
Background of Electrical Flow of
the Heart
• Each heart cell is able to start the depolarization
process – automaticity.
• Excitability is term given to a cell responsiveness to
a electric stimulus.
• The ability of a cell to transmit a stimulus to another
cell is contractivity.
• Contractility is a measure of the cell’s ability to
contract upon electrical stimulus.
• These processes are influenced by the autonomic
nervous systems & medications.
Background of Electrical Flow of
the Heart
• The sino-atrial (SA) node is usually the
group of cells that trigger depolarization.
This is why the SA node is known as the
heart’s pacemaker.
• The SA node usually sets the heart’s rate
at 60 – 100 beats per minute.
Anchoring the Information
• Depolarization and repolarization involves the
exchange movement of Sodium and Potassium
across the cell wall with calcium modulation.
• This exchange sets the Rate of the electrical spread
and muscle Contraction.
TAKE THE QUIZ ON THE NEXT SLIDE AND TEST YOUR
KNOWLEDGE OF WHAT YOU HAVE JUST LEARNED.
Anchoring the Information
Automaticity
• Ability to start the depolarization process.
Autonomic nervous system
• Measure of cell’s ability to contract.
Conductivity
• Cell’s responsiveness to a electric stimulus.
Contractility
• Ability of cell to transmit a stimulus to another cell.
Excitability
• These processes are influenced by the autonomic nervous
systems & medications
TAKE THE QUIZ ON THE NEXT SLIDE AND TEST YOUR
KNOWLEDGE OF WHAT YOU HAVE JUST LEARNED.
Background of Electrical Flow of
the Heart
• The flowing electricity is
summarized to give a general
direction. This is called the
vortex.
Lead II
-
• 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.
cc.stimula.edu
+
Background of Electrical Flow of
the Heart
• 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
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
DRAG LABELS TO CORRECT
LOCATION AND REBUILD THE
CHART
CLICK FORWARD BUTTON TOADVANCE TO NEXT SLIDE
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
l
o
Location
follows the PR interval.
c
Duration 0.06 - 0.12 seconds
a
Amplitude
dependent on Lead (~5-30 mm)
t
Configuration
dependent on Lead
i
Deflection
usually a combination of negative
o positive, varies with leads
and
n
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 wave
Configuration 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 the
Electrical Flow of the Heart
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