Electrocardiograms Part 2

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Electrocardiograms Part 2

• Paper and Time

2
Remember

• To move horizontally (horizontal axis) across EKG
  paper denotes time.
• To move vertically (vertical axis) represents
  voltage.
• The standard speed of EKG paper is 25mm/second.
• Tachycardiaspeed it up
• Bradycardiaslow it down

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The Machine

• Burdik
• Remember that all models are not created equal.

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• http//www.nobel.se/medicine/educational/ecg/index
  .html

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EKG Paper
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Paper

• Each large block on the EKG paper represents 0.2
  seconds.
• Each small block represents 0.04 seconds.
• Soif there are 5 small blocks inside of each
  large block then it makes sense that each large
  block 0.2 seconds
• 0.04x5 0.2

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Voltage

• Each small block represents 1 millimeter.
• Again, since there are five small blocks within
  each large block, horizontally and vertically, 5
  small blocks on the vertical axis 5mm.
• 1 x 5 5mm

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Calculating Rate

• R-R waves
• You can only use R-R waves if the rhythm is
  regular.
• Memorize 300-150-100-75-60
• To use this methoddivide the number of LARGE
  squares into 300
• 300 divided by 2 150
• 300 divided by 3 100, etc.

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What if the rhythm is irregular?

• Cant use the R-R method.
• Most EKG paper is marked every 3 seconds.
  Fifteen large squares 3 seconds because 15 x
  0.2 3 and/or 15 x 5 75 x 0.04 3.
• Soyou can take the number of complexes within a
  six second strip and multiple x 10 for an
  estimation.

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Normal Sinus Rhythm

• The EKG is WNL.
• Rate is between 60-100
• Rhythm is regular
• It has all of its waves and the waves are of
  normal duration.
• Represents an impulse that has started in the SA
  node and followed the normal pathway.

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What is normal duration?

• Each wave has a normal length of time
  (horizontal axis) and a normal voltage (vertical
  axis)-our focus
• P-R interval 0.12-0.2 seconds which is 3-5 small
  boxes.
• QRS complex 0.06-0.12 seconds which is 1.5 3
  small boxes.
• See board

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Common Sinus Rhythms

• Sinusoriginating in the SA node (A)
• Sinus tachycardia 100-180 (C )
• Sinus bradycardia less than 60 (B)
• Sinus arrhythmia varies (D)

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Common Atrial Arrhythmias

• Originate outside of the SA node and above the
  bundle branches
• Premature atrial contractions (PACs) (E)
• Paroxysmal atrial tachycardia (PATs) sudden (F)
• Atrial fibrillation irregular, 150-200 beats per
  minute, no p waves. (G)

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Common Ventricular Arrhythmias

• Premature ventricular contractions No p waves
  and distorted QRS (see H)
• Ventricular tachycardia Regular rhythm most of
  the time---3 or more PVCs, rate 120-250 beats per
  minute (see I)
• Ventricular fibrillation (Bad). Disorganized
  activity in the ventricles. No blood is being
  pumped. Defibrillator. (see J)

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The Leads

• 9 leads12 views!

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The Standard 12-Lead EKG

• Bipolar Leads
• Augmented Leads
• Chest (Precordial) Leads

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Bipolar

• First
• three to
• be
• recorded
• Marked
• Lead I,II,
• III

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Bipolar

• They use two (bi-) limb electrodes to record
  activity from the frontal plane.
• Lead I (RA/LA)
• Lead II (RA/LL)
• Lead III (LA/LL)
• See A

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Einthovens Triangle
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Augmented

• Augment means change
• aVr augmented voltage right
• aVl augmented voltage left
• aVf augmented voltage foot
• Unipolar and also view frontal plane

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Augmented
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Augmented

• aVrmidpoint between left arm and left leg to the
  right arm
• aVlmidpoint between right arm and left leg to
  left arm
• aVfmidpoint between right arm and left arm and
  left leg

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Chest or Precordial Leads

• V1, V2, V3, V4, V5, V6
• Measures activity between 6 points on the chest
  wall and a point within the heart.
• Must use the correct position.

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Precordial/Chest Lead Placement
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Placement

• V1Fourth intercostal space at the right of the
  sternum
• V2Fourth intercostal space at the left of the
  sternum
• V3Midway between V2 and V4 (place V4 first)
• V4Fifth intercostal space MCL
• V5At horizontal level of V4-anterior axillary
  line
• V6At the horizontal level of V4-midaxillary
  line.

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Markings

• Page 720

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Patient Preparation

• See page 722

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Holter Monitor

• Differs from EKG in that it is an ambulatory
  monitoring device.
• The patient wears the monitor for a prescribed
  amount of time and the monitor records any
  cardiac events via an event marker.
• Records approximately 100,000 heart beats.

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Holter Monitor
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Holter Monitor continued

• Typically has 5 leads
• See placement page 732

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EKG Passoffs

• Each student can (a) bring a partner or (b) use
  the manekin for the EKG pass off.
• If you bring a partner (or if you are a partner)
  wear something comfortable under your uniform
  which will allow for easy access---bathing suit
  toptank top, etc.
• We have not used the manekin in the past.
• We will be completing an EKG on the live
  partners.

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Test on Chapter 16

• Option 1 Test on Thursday (tomorrow) and pass
  offs on Monday.
• Option 2 EKGs will be a large part of your final
  which is next Wednesday and we will pass off on
  Monday.
• Option 3 Test on Monday, pass off on Tuesday,
  final on Wednesday.
• Majority will rule but finals are Wednesday.