Cardiac Dysrhythmias

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Cardiac Dysrhythmias
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Sinus Dysrhythmias

• Bradycardia - A Sinus Rhythm That Is lt60 BPM
• Tachycardia - A Sinus Rhythm That Is gt 100 BPM

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• Respiratory Arrhythmia
• During Inspiration Expiration, The R-R Interval
  Expands Contracts

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• R-R Interval Widens During Expiration
• R-R Interval Shortens During Inspiration

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Sinus Arrest

• Sinus Arrest Occurs Because The Sinoatrial Node
  Ceases To Fire

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Sinus Arrest
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Escape Or Rescue Beats

• Secondary Pacemakers Rescue The Heart Create
  Escape Or Rescue Beats

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• Rescue Beats May Have Their Origin High Up In The
  Atria Or Down Low Close To The AV Node Or Even In
  The Ventricles.

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• If The Ectopic Pacemaker Is Close To The SA Node,
  It Will Be An Atrial Escape Beat. It Will Have
  These Features
• The Escape Beat Is Delayed
• P Wave Is Irregularly Shaped
• A Normal QRS Complex

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Atrial Escape Or Rescue Beat
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• If The Rescue Beat Is Close To The AV Node, Then
  It Will Likely Be A Junctional Escape Beat

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• Characteristics Of A Junctional Escape Beat
• A Rescue Beat Is Delayed
• No P Wave
• The QRS Is Normal
• Rate Will Be Slower

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Junctional Rescue Or Escape Beat
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• If The Rescue Beat Is Located In The Ventricles,
  Then It Is A Ventricular Pacemaker That Is
  Activated To Rescue The Heart

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• Characteristics Of A Ventricular Rescue Beat Are
  
• No P Wave
• A Rescue Beat Is A Delayed Beat
• Wide Bizarre QRS Complex
• Rate Will Be Very Slow

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• Ectopic Pacemakers Have Their Own Firing Rates
• A Maxim The Lower Your Go Into The Heart To
  Find A Pacemaker, The Slower The Rate

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Ectopic Pacemaker Rates

• Atrial Pacemakers 60-80 BPM
• Junctional Pacemakers 40-60 BPM
• Ventricular Pacemakers 30-45 BPM

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• What Can Cause The SA Node To Go Into Sinus
  Arrest ?
• Cardiovascular Disease
• Increased Vagal Tone
• Infection
• Drugs - Digitalis, Quinidine

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Wandering Pacemaker

• A Wandering Pacemaker Is A Condition In Which You
  Have Two Or More Pacemakers Competing For Control
  Over The Hearts Rhythm

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• Characteristics Of A Wandering Pacemaker
• P Waves Have Different Shapes
• PR Intervals Are Grossly Within Normal Limits But
  Are Slightly Variant From Each Other
• QRS Complexes Are Normal

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Wandering Pacemaker
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Wandering Atrial Pacemaker
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Sick Sinus Syndrome

• Patient Hx. Of Supraventricular Tachdysrhythmias
  Like Atrial Fibrillation Or Atrial Flutter
• Significant Ischemic Heart Disease

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• Sick Sinus Syndrome Characterized By
• Irregular Heart Rate Deteriorating Into Extreme
  Bradycardia
• Episodes Of Syncope
• Leads To Pacemaker Implant

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Sick Sinus Syndrome
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Ectopic Supraventricular Dysrhythmias

• Unsustained SVTDs
• PACs Or APBs
• PJBs

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Premature Atrial Contractions (PACs Or APBs)

• Characteristics Of PACs
• It Is A Premature Beat
• P Wave Is Irregularly Shaped
• Normal QRS

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• Causes Of PACs
• Stress
• Caffeine
• Tobacco Use

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• Digitalis Toxicity
• Old MIs
• Low Blood Potassium Levels
• Low Blood Magnesium Levels

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Premature Atrial Contraction
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Premature Atrial Contraction
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• PACs Can Deteriorate Into
• Atrial Flutter
• Atrial Fibrillation
• Supraventricular Tachycardia

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Premature Junctional Beats (PJBs)

• PJBs Occur from An Ectopic Focus Close To The AV
  Node

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• Characteristics Of PJBs
• The Beat Is Premature
• There is No P Wave
• QRS Complex Is Normal

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Premature Junctional Beat
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Sustained Supraventricular Dysrhythmias

• Sustained SVTDs Are
• PSVT or PAT
• Atrial Flutter
• Atrial Fibrillation

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PSVT Or PATs

• Common Dysrhythmia
• Instigated Often By A Premature Atrial Beat Or A
  Premature Junctional Beat

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• Causes Are
• Ischemic Heart Disease
• Re-Entry Phenomenon
• Stress
• Drugs

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• Characteristics Of PSVT Are
• P Waves Are Absent - P Waves Are Hidden If They
  Are Present
• Repeating Pattern Of QRS-T
• Very High Heart Rates Of 150 - 250 BPM

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Paroxysmal Atrial Tachycardia
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• Carotid Massage Can Bring A Person Out Of PSVT
• PSVT Can Be Stopped With Cardioversion, Valsalva
  Coughing

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Exercise

• Can I Exercise A Patient With PSVT Or SVT ?
• No !! This Patient Has An Uncontrolled Atrial
  Dysrhythmia

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Atrial Flutter

• Atrial Flutter Is Also Known As The Sawtooth
  Pattern

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• Characteristics Of Atrial Flutter
• High Rate Of P Wave Appearance Of 250-350
• QRS Complex Is Followed By A Regular Pattern Of P
  Waves - 21, 31 or 41 Block

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• QRS Complexes Are Normal Regular
• No Visible T Waves
• No Visible S-T Segment
• No Visible PR Interval

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• Causes Of Atrial Flutter
• Ischemic Heart Disease
• PACs
• Re-Entry Phenomenon

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• Pulmonary Emboli
• Stress
• MIs
• Cor Pulmonale
• Valvular Heart Disease

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Atrial Flutter
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Exercise

• Can I Exercise A Patient With Atrial Flutter ?
• No !! This Patient Has An Uncontrolled Atrial
  Dysrhythmia

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Atrial Fibrillation

• Some Causes Are
• MIs
• Pulmonary Embolism
• Hypertension
• CAD
• Heart Valve Disease

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• Characteristics Are
• High Rates Of Atrial Discharge Of Between 350-500
  BPM
• Flat Or Undulating Baseline
• Absent P Waves
• Irregularly Timed Normal QRS Complexes

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Atrial Fibrillation
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Atrial Fibrillation
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Exercise

• Can I Exercise A Patient In Atrial Fibrillation ?
• NO !! - The Patient Has An Uncontrolled Atrial
  Dysrhythmia

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Symptoms

• What Will The Patient Feel With A
  Supraventricular Tachydysrhythmia ?
• Lightheadedness
• Dizziness Or Syncope
• Shortness Of Breath
• Palpitations
• Angina

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• Can A Patient Chronically Live With These
  Dysrhythmias ?
• Yes, But There Are Some Inherent Dangers !

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Inherent Dangers

• Supraventricular Tachydysrhythmias Can Cause The
  Formation Of Blood Clots In The Atria.

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• Patients Can Auto-Embolize Organ Systems If The
  Heart Spontaneously Converts Out Of The
  Dysrhythmia

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• Patients Must First Be Anti-Coagulated Then
  Converted Out Of The Dysrhythmia

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Ectopic Ventricular Dysrhythmias

• Premature Ventricular Contractions (PVCs)
• Ventricular Tachycardia
• Ventricular Fibrillation

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Premature Ventricular Contractions

• PVCs Occur In Normal Hearts As Well As Those
  With Pathology
• People With Thousands Of PVCs Per Day Can Be
  Normal
• PVCs Can Also Be An Ominous Sign Of Disease

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• Characteristics Of PVCs Are
• PVCs Are Premature Beats
• The P Wave Is Absent
• QRS Complex Is Wide Bizarre
• A Compensatory Pause Follows The PVC

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Premature Ventricular Contractions
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Premature Ventricular Contractions
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• PVCs May Appear Randomly
• PVCs May Appear In Patterns
• Bigeminy
• Trigeminy

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Bigeminy
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Bigeminy
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Trigeminy
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• Quadrigeminy
• Couplets
• Triplets

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Couplets
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Triplets
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• Couplets Are Scary But Triplets Are Really
  Frightening
• Triplets Are A Hairs Breath Away From
  Ventricular Tachycardia

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Multiform PVCs
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Rules Of Malignancy

• An Ordering System For Grading The Severity Of
  Ventricular Ectopies

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From Least Severe To Most Severe

• Frequent Single Focus PVCs
• Runs Of PVCs
• Quadrigeminy
• Trigeminy
• Bigeminy

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• Appearance Of Multifocal PVCs
• RT On T Phenomenon
• Ventricular Tachycardia
• Ventricular Fibrillation

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RT On T Phenomenon

• Thought To Be Very Dangerous
• A PVC Occurs During Ventricular Depolarization

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RT On T Phenomenon

• Why Is It Dangerous ?
• The Cardiac Cells Are Various Stages Of
  Depolarization - Some Have Repolarized While
  Others Are In Various Stages Of Repolarization

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• A Stimulus That Occurs Before Repolarization Is
  Finished Will Set Off A Disorganized Electrical
  Response To The Stimulus May Set The Heart Up
  For A Malignant Ventricular Ectopy Like V-Tach Or
  V-Fib.

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Exercise

• Can I Exercise A Patient Who Is Having PVCs ?

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• Yes, You Can Exercise A Patient Having PVCs.
  However, They Should Only Be Occasional Single
  Focus Single PVCs.

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• If The Exercise Regimen Makes The Incidence Of
  PVCs Occur More Often Or If The PVCs Become
  More Malignant, Exercise Should Be Terminated.

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• A Person Should Not be Exercised When They Are
  Displaying Multiforme PVCs Or Any PVC Rhythm
  (Bigeminy, etc.) Until Cleared By Their
  Cardiologist

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The ACSM Guidelines

• The ACSM Guidelines State If There Is A
  Noticeable Change In Heart Rhythm.

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• ...or Signs Of Poor Perfusion Light Headedness,
  Confusion, Ataxia, Pallor, Cyanosis, Nausea, Or
  Cold Clammy Skin Then
• STOP THE EXERCISE !!!
• Table 3-10, pp 42, 5th edition

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Ventricular Tachycardia

• Ventricular Tachycardia Is Defined As A Run Of
  Three Or More Consecutive PVCs
• The Rate Is Usually Between 100-200 BPM

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• Short Runs Of V-Tach Will Make The Patient Feel
• Dizzy
• Have Palpitations
• Feel Faint
• Be Short Of Breath

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• Sustained Runs OF V-Tach Will Render The Patient
  Unconscious Because The Cardiac Output Is So
  Negatively Effected As To Decrease Perfusion To
  The Brain The Heart.

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Ventricular Tachycardia
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• Ventricular Tachycardia Will Degenerate Quickly
  Into Ventricular Fibrillation

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• The Patient In V-Tach Must Be Supported With CPR
  Methods Must Be Cardioverted Electrically Or
  Pharmacologically Out Of This Fatal Rhythm

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• Both V-Tach V-Fib Are Absolute Medical
  Emergencies Requiring High Level Medical
  Management

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Ventricular Fibrillation

• V-Fib Is Seen In Hearts That Are Dying
• Electrical Activity is Completely Chaotic
• No Meaningful Cardiac Output Is Occurring

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• V-Fib Is Characterized By
• No True QRS Complexes
• A Wandering Or Undulating Baseline
• No Recognizable Atrial Wave Forms
• No Recognizable T Waves

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• The Patient Must Be Supported By CPR Methods
  Must Be Electrically Cardioverted Out Of This
  Rhythm Or Death Ensues

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Ventricular Fibrillation
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Exercise

• Exercise Cannot be Sustained In Patients With
  V-Tach Or V-Fib Because 99.99 Of The Time They
  Will Be Unconscious - Exercise Is Never An Option

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Atrioventricular Blocks

• First Degree AV Blocks
• Second Degree AV Blocks
• Mobitz Type I (Wenckebach Block)
• Mobitz Type II
• Third Degree AV Blocks

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First Degree AV Blocks

• Characterized By
• Prolonged PR Interval gt 5 mm
• Every QRS Is Preceded By A P Wave
• Every QRS Is Normal
• No Dropped Beats

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First Degree AV Block
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First Degree AV Block
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• Causes
• Drug Toxicity
• Ischemic Heart Disease Of The Hearts Conduction
  System
• Myocarditis

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• First Degree AV Block Does Appear In Healthy
  Individuals As Well As In Those With Ischemic
  Heart Disease

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Exercise

• Can I Exercise A Patient In First Degree AV Block
  ?
• Yes, But The Rhythm Must Not Degenerate During
  Exercise To Second Degree AV Block.

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• Also, The Rhythm Had To Have Been Present Before
  Exercise Started. If A Patient Is Normal On
  Their EKG Before Exercise Degenerates Into
  First Degree AV Block, Exercise Must Stop !!

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• First Degree AV Block Is Generally Not Considered
  To Be A Highly Malignant Dysrhythmia

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Second Degree AV Block Mobitz Type I Or A
Wenckebach Block
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• Second Degree AV Block Or A Mobitz Type I AV
  Block Is Characterized By
• Progressively Lengthening PR Interval
• A Sudden Dropped QRS Complex
• Return Of A Normal Rhythm
• A Repeating Cycle

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Mobitz Type I
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Exercise

• Can I Exercise A Patient In A Mobitz Type I
  Second Degree AV Block ?

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• Yes, Providing The Dysrhythmia Does Not
  Degenerate During Exercise.
• The Patient Must Also Have Been Cleared For
  Exercise

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• A Problem Does Exist With A Mobitz Type I AV
  Block !!
• You Have To Be Concerned That It Will Degenerate
  Into A Mobitz Type II AV Block

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Second Degree AV Block Mobitz Type II
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• Characteristics Are
• A Series Of Normal Beats
• All PR Intervals Are Normal Duration
• Sudden Dropped Beat - No QRS
• Normal Rhythm Re-Established
• Cycle Begins Again

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Mobitz Type II
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Mobitz Type II
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• Mobitz Type II AV Block Is A Dangerous
  Dysrhythmia Because Of The High Likelihood That
  It Will Convert To A Third Degree AV Block.

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Exercise

• Can I Exercise A Patient In A Mobitz Type II AV
  Block ?
• No. The Risk Is Too High That The Patient Will
  Convert To Third Degree AV Block.

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• A Patient With A Mobitz Type II AV Block Is Going
  Eventually Convert To A Third Degree Block Is A
  Candidate For A Surgically Implanted Pacemaker

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Third Degree AV Block

• This Is A Serious Condition In Which There Is No
  Communication Of The SA Node With The AV Node.
  It Is Also Called Complete Heart Block.

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• The Atria Beat At Their Own Rate While The
  Ventricles Beat At Their Own Rate

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• The P Waves Appear Are Not Connected To Any QRS
  Complex
• The QRS Are Abherrantly Wide
• Ultimate Ventricular Rate Is Often Very
  Bradycardic

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3rd Degree AV Block
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• Most Patients In Third Degree AV Block Require
  The Implantation Of A Pacemaker.

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Bundle Branch Blocks

• Right Bundle Branch Block
• RSR (Bunny Ears) In V1-V4
• Loss Of The R Wave Progression
• ST Segment Depression In V1 - V4
• T Wave Inversion In V1 - V4
• Wide QRS Complexes

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• Can you exercise a patient in RBBB ?
• Yes as long as they have been cleared by their
  physician.

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• Left Bundle Branch Block
• Loss of the R wave progression
• Huge S waves in V1 - V4
• RSR in V4 - V6
• Wide QRS complexes
• ST segment depression in V4 - V6
• T Wave inversion in V4 - V6

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• Can you exercise a person in LBBB ?
• Yes, as long as the patient has been cleared by
  their physician.