Electrocardiography

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Chapter 16

• Electrocardiography

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Vocabulary

• Amplify
• Arrhythmia
• Atrium
• Automaticity
• Cardiac arrest
• Defibrillation
• Electrocadiography

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Continued

• Fibrillation
• Myocardial infarction
• Myocardium
• Pacemaker
• Pericarditis
• Rhythm strip
• Ventricle

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EKG

• What is it?

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Did you know that your body produces electricity?

• How?
• Electrolytes

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ElectrolytesProduce Ions which produce
electricity

• Magnesium Mg
• Sodium Na
• Potassium K
• Calcium Ca
• Chloride Cl-

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Electrocardiograph

• A graphic representation of the electrical
  activity (currents) that are produced by the
  heart during contraction (systole) and relaxation
  (diastole).
• Records the amount electrical activity, the time
  required for the electrical activity to travel
  through the heart, and the rate and rhythm of the
  heart.

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Major Electrolytes Na and K

• Remember the Sodium-Potassium Pump?
• Depolarization vs. Repolarization
• See Board

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The Sodium-Potassium Pump

• When the heart is at rest, there are more Na
  ions (carry electrical charge) on the outside of
  the cell. When the cardiac muscle cell is
  stimulated, Na rushes into the cell and pushes
  K out this is depolarization.
• Repolarization occurs when the Sodium-Potassium
  pump moves Na out of the cell and lets K back
  in.

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Depolarization/Repolarization

• Without this phenomena, the cardiac cells would
  not be stimulated and no action would take place.
  
• Without these electrolytes, this action would be
  impossible.
• Any alteration in your electrolyte balance can
  cause muscle/cardiac abnormalities.

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Anatomy Review-Circulation

• Blood enters the right atrium via the Superior
  and Inferior Vena Cava. From the right atrium
  through the tricuspid through the pulmonary
  valve, to the pulmonary artery to the lungs to
  pick up oxygen.
• Back in through the pulmonary veins, to the left
  atrium, through the bicuspid, to the left
  ventricle, through the aortic semi-lunar valve
  to the aorta to systemic circulation.

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The Conduction System

• Cardiac Cycle one complete heartbeat
• Driven by an internal conduction system.
• Depolarization causes the myocardium to contract.
• Repolarization allows the myocardium to relax.
• Remember that the heart, although it works as one
  unit, is actually two separate pumps.

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The Pump

• The two atria contract together---then relax
• The two ventricles contract togetherthen relax.
• The atria and the ventricles are considered
  separately on the EKG.

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The Waves
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Isoelectric Line
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The P Wave
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The P Wave

• Represents atrial excitation or depolarization.
• This impulse/wave comes from the SA nodethe
  hearts internal pacemaker.

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The P-R Segment QRS Complex
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The P-R Interval

• The time it takes from the beginning of atrial
  contraction to the beginning of ventricular
  contraction (Q wave).
• The PR segment reflects the time it takes the
  impulse to go through the AV node to the Bundle
  of His, the bundle branches and the Purkinje
  fibers.

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The ST Segment

• Represents the time from the end of ventricular
  contraction (depolarization) to the beginning of
  ventricular recovery (repolarization)remember
  Na and K

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The T Wave

• Represents full muscle recovery---complete
  repolarization and the activity can now start
  over.

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Normal EKG
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EKG Paper

• To move horizontally across EKG paper time.
• The Universal speed for recording an EKG is 25 mm
  per second.
• If the heart rate is rapid (tachycardia) the
  speed should be increased.
• You must let the MD know that you changed the
  speed.

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Classroom Assignment

• Answer the following questionsturn in for a quiz
  grade

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Artifacts

• Abnormal tracings that occur during an
  EKGunwanted activity not caused by the hearts
  electrical activity.

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Artifacts

• Somatic Tremor
• Wandering Baseline
• Alternating Current interference

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Wandering Baseline
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Reasons for Wandering Baseline

• Electrodes too tight or too loose
• Tension on an electrode
• Too little gel
• Corroded or dirty electrode
• Skin creams/lotionselectrode wont stick

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Somatic Tremor
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Reasons for Somatic Tremor

• Client is tense
• Movement or talking
• Uncomfortable position
• Nervous disorder--Parkinsons

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Alternating Current Interference

• Improper grounding of the machine
• Presence of other electrical equipment in the
  room.
• Electrical wiring
• Faulty technique

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Questions

• 1. Draw and label the waves, intervals and
  segments of an EKG---explain what each segment
  signifies.
• 2. Explain what is happening in the heart during
  depolarization and repolarization.
• 3. Visit http//www.heartinfo.org/ 3D tool
• 4. Take each of the artifacts discussed and
  describe how, if they occurred, would you
  intervene to correct the occurrence.