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Basic EKG Rhythm Interpretation

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History of EKG

    • 1755- Galvani discovered that electrical stimulus applied to a motor nerve caused contraction of the associated muscle.
    • 1855- Kollicker and Mueller assumed that the beating of the heart must be due to a rhythmic discharge of electrical stimulus.
    • 1880’s- Ludwig & Waller discovered that this rhythmic electrical activity could be monitored from the patients skin.
    • 1901- Einthoven- developed the Electrocardiogram.

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Types of EKG machines

  • 12 lead
    • Provide a “snapshot” of the electrical activity in the heart in several different leads
  • Continuous
    • Provide a real time picture of the electrical activity in the heart
    • Often combined with a Defibrillator
  • Holter Monitor
    • Worn by patient
    • Record the electrical activity for 24 or 48 hours

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Lead Placement

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EKG Paper

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Waves in the Cardiac Cycle

  • P wave – Atrial Depolarization
  • QRS Complex – Ventricular Depolarization
  • T wave – Ventricular Repolarization

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Intervals

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EKG Rhythm Interpretation

  • Name the place in the conduction system where the impulses originate
      • (Sinus, Atrial, Junctional, Ventricular)
  • Describe the speed
      • (bradycardia, tachycardia)
  • Mention any ectopic beats
      • (PAC’s, PJC’s, multifocal PVC’s, unifocal PVC’s)
  • Mention any conduction defects present
      • (1st, 2nd, or 3rd degree blocks, bundle branch blocks)

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Analyzing an ECG strip

  • Regularity
  • Rate
  • P waves
  • PRI
  • QRS complex

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Regularity

  • If rhythm varies by 0.12 sec between R waves, rhythm is irregular
  • Use calipers or other solid measuring device. (blank card with pencil marks).

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Rate

  • Easiest way to calculate rate is six second method on a marked ECG strip.

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Alternate method of calculating regular rates

  • Count the number of big boxes between QRS complexes
  • 1-Rate of 300 (every big box)
  • 2-Rate of 150 (every other box)
  • 3-Rate of 100 (every third box)
  • 4-Rate of 75 (every fourth box)
  • 5-Rate of 60
  • 6-Rate of 50
  • 7-Rate of 43
  • 8-Rate of 37
  • 9-Rate of 33
  • 10-Rate of 30

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P waves

  • Are P waves present?
  • Are P waves normal?
  • Is there a P wave for every QRS?

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Measure the PR Interval

  • Measure from the start of the P to the start of the QRS
  • Normal PRI is .12 to .20

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Measure the QRS

  • Normal QRS = .12 sec or less.

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sinus

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Normal Sinus Rhythm

      • Rate 60-100
      • Regular
      • P waves present, consistent
      • PR interval .12 - .20 seconds

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Sinus Arrhythmia

      • Rate 60-100
      • Slightly irregular, gradually changes
      • P waves present, consistent
      • PR interval consistent, .12 - .20 seconds

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Sinus Bradycardia

      • Rate <60
      • Regular
      • P waves present, consistent
      • PR interval .12 - .20 seconds

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Sinus Tachycardia

      • Rate 100 - 150
      • Regular
      • P waves present, consistent
      • PR interval .12 - .20 seconds

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Sinus Rhythm with PAC’s

      • Any Rate
      • Regular except where PAC occurs
      • P waves Present, Usually Different for PAC
      • PR interval normal, Usually Different for PAC

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Sinus Rhythm with �Non-Conducted PAC’s

      • Any Rate
      • Regular except where PAC occurs
      • P waves Present, Usually Different for PAC
      • PR interval normal, N/A for PAC

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atrial

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Atrial Tachycardia or�Superventricular Tachycardia

      • Rate >150
      • Regular
      • P waves usually buried in T wave
      • PR interval usually unable to determine

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Atrial Fibrillation

      • Randomly Irregular
      • Any Ventricular Rate
      • NO P waves (May or may not see fibrillation waves)
      • PR interval not measurable

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Atrial Flutter

      • Rate Varies with conduction ratio
      • May be irregular, depending on conduction
      • P waves with V-shaped “sawtooth” pattern (Called Flutter waves)
      • PR interval not measurable

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junctional

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Junctional Rhythms

  • Originate from the area in and or around the AV node (AV junction).
    • AV node is functioning as pacemaker of the heart.
  • Atria usually depolarizes, but conduction path is retrograde (backwards).
    • P-wave will be inverted
    • May be before, buried in, or after the QRS.
    • PR interval normally <.12 sec
  • Ventricles depolarize normally
    • QRS < .12 seconds
  • Regular, rate = 40-60 (can be accelerated)

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Junctional Rhythm

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Accelerated Junctional Rhythm

  • Junctional Rhythm with a rate of 60-100

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Junctional Tachycardia

  • Junctional Rhythm with a rate over 100

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Premature Junctional Contractrions (PJC’s)

  • An early beat that originates from an ectopic pacemaker site in the AV junction.

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Heart Blocks

  • Problems with the conduction system
  • Impulses are delayed, or not conducted at all
  • Usually occur at the AV Junction (AV Blocks)

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Types of Heart Blocks

  • 1st Degree
    • Impulses are delayed, but conducted through to the ventricles
  • 2nd Degree
    • Some impulses are conducted, some are not
  • 3rd Degree
    • No impulses are conducted
    • Also known as “Complete Heart Block”

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First Degree Block

  • Underlying Sinus Rhythm
  • All atrial contractions are conducted
  • Long PR Interval

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Second Degree Blocks

  • Type I (Wenckebach)
    • PR interval increases gradually until an impulse is blocked, then the cycle starts over again

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Second Degree Blocks

  • Type II
    • PR interval is constant
    • Impulses may be dropped occasionally, or as frequently as every other beat

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Third Degree Blocks

  • No Impulses are conducted
  • Escape rhythm present
  • No relationship between p waves and QRS complexes

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Abnormal Conduction through the Ventricles

  • Impulse travels from one side of the ventricles to the other
  • Reasons:
    • If impulse starts in the ventricles
    • If there is a block in one of the bundle branches
  • Results in a wide QRS (> .12 sec)

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V-Tach or SVT with aberrant conduction?

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Sinus Rhythm with �Bundle Branch Block

  • P waves present
  • QRS > .12 sec

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ventricular

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Premature Ventricular Contractions (PVCs)

    • An irritable place in the ventricles

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    • These PVCs are Unifocal (all the same, from a single irritable place in the ventricles)

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Multifocal PVCs

  • All different morphology
  • Many irritable places in the ventricles

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Paired PVCs (Couplets)

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Idioventricular Rhythm�(Ventricular Escape Rhythm)

  • No P waves Present
  • Rate < 40 bpm
  • Regular
  • QRS > .12 second

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Accelerated Idioventricular Rhythm (AIVR)

  • No P waves Present
  • Rate 40 - 100 bpm
  • Regular
  • QRS > .12 second

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Ventricular Tachycardia

  • No P waves Present
  • Rate >100 bpm
  • Regular
  • QRS > .12 second

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Torsades De Pointes or�Polymorphic V-Tach

  • Multiple ectopic sites in ventricles compete
  • Axis shifts around, giving the strip a “twisting” appearance

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Coarse �Ventricular Fibrillation

  • Totally disorganized electrical activity
  • No contraction or cardiac output (COR-0)
  • Deteriorates from coarse to fine to asystole

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Fine Ventricular Fibrillation

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Asystole

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Pacemakers

  • Implanted artificial

impulse generator

    • Usually set at

70-80 bpm

  • Battery powered
    • Usually last 8-10 years
  • Treatment of choice for patients with chronic 3rd Degree Block and Sick Sinus Syndrome
    • Usually Ventricular Pacemakers

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EKGs of Pacemakers

  • When the pacemaker generates an impulse, the EKG records a “spike”
  • If the impulse “Captures”, there is a wide complex