EKG Interpretation

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EKG Interpretation

• Just the beginning

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King County

• Introduction
• Cardiac monitoring has been routinely used in the
  Fire Service for many years
• Not without some liability
• Intent of this course is to provide the basics in
  cardiac rhythm interpretation

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Introduction cont.

• This course is not intended to teach diagnosis of
  heart disease
• Lead II is not sufficient for EKG diagnosis
• Recognition of the cardiac cycle will aid in the
  understanding of EKGs
• In order to remain proficient it is necessary to
  commit time to ongoing training in EKG
  interpretation

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Objectives

• Understand basic cardiac terminology
• Describe the anatomy of the heart
• Identify the electrical conduction system
• Identify abnormal electrical cardiac activity

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Objectives

• Identify common cardiac rhythms
• Identify and effect appropriate therapy for the
  patient on a monitor

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Course Completion

• Participants are expected to pass a written exam
  and achieve a 70 score
• Practical exam will include correct
  interpretation of static rhythms, 70 passing
  score

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Primary Obligation

• It cannot be overemphasized that the primary
  obligation for non-cardiac arrest patients is
  ABCs
• Attention to the patients symptoms
• Vital Signs, physical exam
• Any necessary treatment with application of the
  monitor only when basic life support has been
  completed

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Anatomy Physiology

• Heart is a muscle
• Divided into four chambers
• Receives blood from the body via the inferior and
  superior vena cavae
• Chambers separated by valves
• Coronary arteries supply blood to the myocardium

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Electrical Conduction System

• Specialized system of interconnected cells spread
  throughout the entire heart
• Provides and conducts the signal to the heart
  muscle to contract in a coordinated fashion

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Sinoatrial (SA) Node

• Collection of electrical tissue that is the
  normal point of origin of electrical activity
• Named because it is located in the sinus part of
  the atria
• Generates P waves

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Atrioventricular (AV) Node

• A way station that receives the impulses from the
  atria
• Named because it is located between the atria and
  the ventricles
• Actually used to slow impulses from the atria to
  the ventricles

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Bundle of His

• Receives impulses from the AV node and passes
  them through the left and right bundle branches
  in the ventricular septum

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Purkinje Fibers

• Last receiving point of the electrical impulses
• Fibers located in the ventricular musculature
• Rapidly conducts impulses causing ventricular
  contraction

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Automaticity

• Any portion of the conduction system or heart
  muscle may initiate an electrical impulse
• When the AV Node fails to generate an impulse,
  another cell/area of the heart will initiate
  electrical activity

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Secondary Pacemakers

• Any portion of the heart may initiate an
  electrical impulse and becomes a secondary
  pacemaker
• Determining the location of a secondary pacemaker
  will become clearer as we proceed through this
  curriculum

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Electrocardiographic paper
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EKG paper

• Grid of standard dimensions
• Simply used as a measurement of time
• Each small box represents 0.04 seconds
• Larger bolded boxes are .20 seconds
• Important to remember these values as they aid in
  the identification of virtually all EKG strips

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The Cardiac Cycle

• P wave- indicates atrial depolarization
• PR interval- the interval from the beginning of
  the P wave to the beginning of the QRS complex
• PR interval represents the time from atrial
  depolarization to the beginning of ventricular
  repolarization

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Cardiac Cycle

• Normal PR interval should not exceed 0.2 seconds
  or one large bolded square on the EKG paper
• QRS complex- represents electrical depolarization
  of the ventricle
• Normal duration of the QRS complex is from
  0.08-0.10 seconds (2 to 3 small boxes on the EKG
  paper

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Cardiac Cycle

• T wave- represents repolarization of the
  myocardium

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Normal Sinus Rhythm

• Characteristics-
• P wave for each QRS
• PR interval normal, lt0.20 seconds
• QRS complex is normal, lt0.10 seconds
• Uniform in shape
• Rate is regular and is between 60-100

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Normal Sinus Rhythm

• Most common rhythm seen in acute MI
• Does not indicate that the patient is stable or
  that there is an absence of heart disease
• Indicates that the origin of the impulse is from
  the SA Node
• Indicates normal function of the electrical system

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Normal Sinus Rhythm
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Normal Sinus Rhythm
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Sinus Tachycardia

• Characteristics-
• P wave for each QRS
• PR interval is normal, lt 0.20 seconds
• QRS complex is narrow, lt 0.10 seconds
• Uniform in shape
• Rate is regular, gt 100/minute

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Sinus Tachycardia

• Accelerated discharge of electrical impulses from
  the sinus node
• Treatment is attention to symptoms
• Underlying cause is the concern
• Causes include shock, stimulants, acute MI where
  decrease in cardiac output causes heart rate
  increase

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Sinus Tachycardia
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Sinus Tachycardia
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Supraventricular Tachycardia

• P waves may not be seen due to accelerated rate
• QRS complex is narrow, lt 0.10 seconds
• Uniform in shape
• Rate is regular, gt 150/ minute
• Patients heart rate is too fast

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Supraventricular Tachycardia
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Supraventricular Tachycardia
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Sinus Bradycardia

• Characteristics-
• P wave for each QRS
• PR interval is normal, lt 0.20 seconds
• QRS complex is normal, lt 0.10 seconds
• Uniform in shape
• Rate is regular, lt 60/ minute

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Sinus Bradycardia

• Transmission of impulses from the SA node is
  slowed to lt 60/ minute
• Heart rates less than 50/ minute should never be
  considered to be normal
• Beta blockers, digoxin, hypoxia, being athletic
  or with history of a slow heart rate can be the
  cause
• Patients heart rate is too slow

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Sinus Bradycardia
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Sinus Bradycardia
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Premature Ventricular Contractions

• Characteristics-
• Early occurring beats that have a characteristic
  compensatory pause
• Premature QRS complex that is wide and bizarre,
  conduction time gt 0.10 seconds
• Same shape except when from different focus in
  the heart

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Premature Ventricular Contractions

• Can occur in a healthy individual
• Viewed with caution in the patient who presents
  with cardiac symptoms
• Significant if occur in 2s (couplets), 3s
  (triplets),run of 4 is Ventricular Tachycardia
• Frequent occurring with syncope be cautious

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Premature Ventricular Contractions
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Ventricular Tachycardia

• Characteristics-
• P waves are usually present but are obscured by
  wide, rapidly occurring QRS complex
• QRS complex is wide gt 0.10 and bizarre
• Uniform in shape typically
• Rate is regular and gt 150/ minute

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Ventricular Tachycardia

• Life threatening arrythmia
• Rapid rate decreases cardiac output
• Place patient supine, anticipating shock
• Cause can be electrical and not always acute MI
• If patient unconscious and pulseless is a a
  shockable rhythm

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Ventricular Tachycardia
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Ventricular Tachycardia
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Idioventricular Rhythm

• Characteristics-
• P waves typically obscured or follow the QRS
  complex
• QRS complex is wide, gt 0.10 seconds
• Sometimes uniform in shape
• Rate is irregular, most often seen with rate lt
  40/minute

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Idioventricular Rhythm

• Observed after defibrillation can be endpoint
  in arrest resuscitation attempt
• Conduction system above the ventricles fails to
  generate an electricle impulse
• Inherent rate of 30-40/minute
• Will likely be in cardiac arrest
• If unconscious and B/P lt60, initiate CPR

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Idioventricular Rhythm
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Ventricular Fibrillation

• Characteristics-
• P waves are absent
• QRS complex absent
• Baseline wavy, chaotic and inconsistent
• Rhythm irregular
• Rate is not countable

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Ventricular Fibrillation

• Sudden death cardiac arrest immediately follow
  the onset
• Immediately defibrillate with 200 joules and
  proceed with standing orders
• Remember that we now do CPR for 2 minutes between
  shocks

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Asystole

• Characteristics-
• P waves are not present
• QRS complex is not present
• Absence of any complexes indicate complete
  cessation of electrical activity
• The heart is motionless

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Asystole
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Pacemakers

• Characteristics-
• P waves sometimes are visible but are not
  associated
• QRS complex of times is wide, gt 0.10 seconds
• Preceded by a small spike with either a negative
  or positive deflection

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Pacemakers

• Presence of a pacemaker indicates that there is
  an underlying rhythm disturbance, usually heart
  block
• Technology makes it harder to see when they are
  present
• Failure can occur, look for pacer spikes without
  complex initiated

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Pacemakers

• Look for the presence of Ventricular Fibrillation
  in the patient who is in cardiac arrest
• Spikes will appear even in the presence of
  fibrillatory waves

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Paced Rhythm
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Paced Rhythm (AV Sequential)
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Atrial Pacemaker
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Pacemaker Failure
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Sinus Arrhythmia

• Characteristics-
• P waves for each QRS
• PR interval is lt 0.20 seconds
• QRS complex is narrow, lt 0.10 seconds
• Rate varies, will speed up during inhalation and
  slow down on expiration

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Sinus Arrythmia

• This rhythm is commonly found in healthy children
  or athletic adults
• Treat specific complaint or injury

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Sinus Arrythmia
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Atrial Flutter

• Characteristics-
• P waves are referred to as flutter waves and are
  uniform in shape, resembling a sawtooth pattern,
  mirror effect
• QRS complex is narrow, lt 0.10 seconds
• Rate is both regular and irregular
• Can be rapid, often seen at 150/minute

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Atrial Flutter

• This rhythm is rarely seen in patients with
  healthy hearts
• Can be seen in patients with heart disease, acute
  MI, lung disease and pulmonary embolism
• Likes to go fast, needs ALS eval and is never
  normal for patients

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Atrial Flutter
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Atrial Fibrillation

• Characteristics-
• P waves are not clearly visible or uniform for
  each QRS complex
• QRS complex is typically narrow, but can be wide
• Is irregular-irregular, depending on ventricular
  response can be rapid

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Atrial Fibrillation

• Cells within the atria fire chaotically
• Will be observed to have a rapid ventricular
  response with new onset
• Digoxin, beta blockers, calcium channel blockers
  can be used to control rate
• Also coumadin prescribed to reduce the incidence
  of clots in the heart chambers

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Atrial Fibrillation
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Atrial Fibrillation
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Atrial Fibrillation
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Atrial Fibrillation
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Nodal Rhythm

• Characteristics-
• P waves are absent
• QRS complex is narrow, lt 0.10 seconds
• Uniform in shape
• Rate is regular, typically gt 40/minute but may be
  in excess of 100/minute

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Nodal Rhythm

• Nodal rhythm occurs when the SA node fails to
  function
• Expect to see narrow QRS complex, lt0.10 seconds
• Can be caused by Digitalis Toxicity, acute MI,
  hypoxia, diseased sinus node
• In some patients this may be their normal rhythm

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Nodal Rhythm
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Nodal Rhythm
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Accelerated Nodal Rhythm
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First Degree Heart Block

• Characteristics-
• P wave for each QRS
• PR interval is gt0.20 seconds
• Rate is regular
• QRS complex is narrow, lt 0.10 seconds
• Uniform in shape

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First Degree Heart Block

• Occurs when there is delayed conduction of an
  impulse through the AV node
• Patients presentation dictates need for
  intervention
• Some patients may have first degree heart block
  as their primary rhythm

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First Degree Block
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First Degree Heart Block
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First Degree Heart Block
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First Degree Heart Block
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Second Degree Heart BlockWenckebach, Mobitz Type
1

• Characteristics-
• P waves are present
• P wave occurs at a regular rate
• QRS complex is uniform in shape and narrow, lt0.10
  seconds
• PR interval progressively lengthens until QRS
  complex is dropped

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Wenckebach, Mobitz Type 1

• Sinus impulse is progressively delayed through
  the AV node until no conduction occurs
• Causes include ischemic heart disease, acute MI,
  digitalis toxicity
• Patients presentation determines intervention,
  if ventricular rate is slow the patient may not
  have symptoms

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Wenckebach, Mobitz Type 1
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Wenckebach, Mobitz Type 1
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Wenckbach, Mobitz Type 1
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Second Degree Heart Block Mobitz Type II

• Characteristics-
• P waves are present
• P waves occur at a regular rate
• PR interval is fixed , may be prolonged
• On occasion there will be more than one P wave
  for each QRS complex

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Mobitz Type II

• QRS complex may be narrow, lt 0.10 or may be wide,
  gt 0.10
• Series of non conducted P waves may be seen
  (atrial depolarization only)
• Ratio at which the QRS complex is conducted
  varies and is noted as a ratio, 21, 31, etc.
  (Ps for each QRS complex)

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Mobitz Type II

• Most often seen in the setting of acute MI
• Frequently have syncope associated due to the
  slow rate
• Commonly progresses to complete heart block
• ALS evaluation paramount, since patient will
  often times be in shock

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Mobitz Type II
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Mobitz Type II
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Mobitz Type II
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Third or Complete Heart Block

• Characteristics-
• P waves occur at a regular interval, typically at
  a rate of 60-100 beats/min.
• P waves do not have a fixed, or constant
  relationship to the QRS complex
• PR interval abnormally prolonged, gt 0.20 and
  changing

92
Complete Heart Block

• QRS complex may be narrow, lt 0.10 or wide, gt 0.10
  depending on where in the heart the impulse
  originates
• QRS rate is usually constant, typically between
  20-40 beats/min.
• Indicates that there is no transmission of
  impulses between the atria and the ventricles

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Complete Heart Block

• Often occurs in the setting of acute MI
• Can occur with Digitalis toxicity, elderly with
  conduction system problems
• May present with syncope
• This type of heart block may be transient
• ALS evaluation paramount, since patient will
  often times be in shock

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Complete Heart Block
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Complete Heart Block
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Complete Heart Block
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P.E.A.Pulseless Electrical Activity

• Characteristics-
• P waves may be present
• PR interval may be normal, lt 0.20 sec.
• QRS complex may be narrow, lt 0.10 or wide, gt 0.10
• Rate can be regular or irregular
• Can be normal rhythm

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P.E.A

• Pulseless Electrical Activity is indicated by the
  absence of a detectable pulse and the presence of
  some type of electrical activity
• Seen during cardiac arrest secondary to acute MI,
  pulmonary embolus, cardiac tamponade, tension
  pneumothorax or a hypovolemic state

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P.E.A. (sinus tachycardia)
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Treatment Protocols

• Do not attempt to treat any patient from what is
  seen on the monitor alone, unless V. Tach with
  unconsciousness or V. Fib.
• Patient presentation will direct intervention
• Request ALS evaluation when possible lethal
  arrythmias are identified

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Ongoing Education

• It is recommended that EMTs receive regular
  ongoing education to remain proficient at EKG
  recognition
• Quarterly review/refresher by a paramedic or
  equivalent
• Attach EKG strips to your MIRF forms for
  department reviewer for feedback and
  identification confirmation

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EKG Interpretation

• Questions?
• The end or just the beginning?