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Arrhythmias and DevicesModule 1

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Objectives

• Recognize typical rhythms and rhythm disorders

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Arrhythmias and DevicesOverview

• The Conduction System

– Normal Conduction

– Automaticity & Action Potential

– Causes of Rhythm Disorders

• Rhythm Disorders

– Categories

• Disorders of Impulse Formation

• Disorders of Impulse Conduction

– Mechanisms

• Arrhythmia Recognition and Classification

– Bradycardias

– Tachycardias

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Cardiac ConductionSinus Node

• The Heart’s ‘Natural Pacemaker’

– Rate of 60-100 bpm at rest

Sinus Node(SA Node)

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Cardiac ConductionAV Node

• Receives impulses from SA node

• Delivers impulses to the His-Purkinje System

• Delivers rates between 40-60 bpm if SA node fails to deliver impulses

Atrioventricular Node (AV Node)

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Cardiac ConductionHIS Bundle

• Begins conduction to the ventricles

• AV Junctional Tissue:

– Rates between 40-60 bpm

Bundle of His

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Cardiac ConductionPurkinje Fibers

Bundle Branches and Purkinje Fibers

• Moves the impulse through the ventricles for contraction

• Provides ‘Escape Rhythm’:

– Rates between 20-40 bpm

Purkinje Network

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Normal Sinus Rhythm

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Impulse Formation in SA Node

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Atrial Depolarization

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Delay at AV Node

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Conduction through Bundle Branches

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Conduction through Purkinje Fibers

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Ventricular Depolarization

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Plateau Phase of Repolarization

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Final Rapid (Phase 3) Repolarization

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Normal ECG Activation

This pattern of depolarization results in efficient mechanical contraction – which is the purpose – to pump blood.

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Reading ECG Squares Intervals and Timing

Horizontal axis – time:

• Each small square = 40 ms

• Each block = 200 ms (5 ea. 40 ms squares)

Converting this to a rate in bpm:

• 1 min = 60,000 ms, so:

• 60,000/ms = bpm

– 60,000/600ms = 100 bpm

Pacemakers and ICDs calculate intervals (ms), not in rates (bpm)

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ECGs Annotation

Normal Ranges in Milliseconds:

• PR Interval 120 – 200 ms

• QRS Complex 60 – 100 ms

• QT Interval 360 – 440 ms

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Status Check

This ECG shows a QRS duration of about 100 ms – a normal duration.

If this represents efficient ventricular contraction…

…then what effect could a QRS duration of 200 ms have on mechanical efficiency and cardiac output?

Click for Answer

Inefficient contraction

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Status Check

Match the term on the left with the description on the right

• P-R Interval

• AV Node

• Purkinje Network

• Bundle Branches

Click for Answer

Normally 120-200 ms

Escape rate is 40-60 bpm

Depolarizes the Ventricles

Connect His bundle to Purkinje network

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We’ve Seen How the Normal Pattern of Conduction Occurs But:

• What triggers the depolarization – what causes that first cell to depolarize?

• If a cell depolarizes, why does it result in depolarization in other cells?

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Automaticity

Cardiac Cells are unique because they spontaneously depolarize

• Upper (SA Node)

– 60-80 bpm

• Middle (AV Junction)

– 40-60 bpm

• Lower (Purkinje Network)

– 20-40 bpm

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Automaticity

Once a pacemaker cell initiates an impulse, its neighboring cells follow suit – like dominos.

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Action Potential of a Cardiac Cell

5 Phases Phase 0

– Rapid or upstroke depolarization with an influx of sodium ions into the cell

Phase 1

– Early rapid repolarization with transient onward movement of potassium ions

Phase 2

– Plateau Phase: Continued Influx of Sodium and slow Influx of Calcium

Phase 3

– Repolarization: Potassium outflow

Phase 4

– Resting Phase

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Action Potential of a Cardiac Cell

5 Phases Phase 0

– Rapid or upstroke depolarization with an influx of sodium ions into the cell

Phase 1

– Early rapid repolarization with transient onward movement of potassium ions

Phase 2

– Plateau Phase: Continued Influx of Sodium and slow Influx of Calcium

Phase 3

– Repolarization: Potassium outflow

Phase 4

– Resting Phase

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Action Potential of a Cardiac Cell

5 Phases Phase 0

– Rapid or upstroke depolarization with an influx of sodium ions into the cell

Phase 1

– Early rapid repolarization with transient onward movement of potassium ions

Phase 2

– Plateau Phase: Continued Influx of Sodium and slow Influx of Calcium

Phase 3

– Repolarization: Potassium outflow

Phase 4

– Resting Phase

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Action Potential of a Cardiac Cell

5 Phases Phase 0

– Rapid or upstroke depolarization with an influx of sodium ions into the cell

Phase 1

– Early rapid repolarization with transient onward movement of potassium ions

Phase 2

– Plateau Phase: Continued Influx of Sodium and slow Influx of Calcium

Phase 3

– Repolarization: Potassium outflow

Phase 4

– Resting Phase

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Action Potential of a Cardiac Cell

5 Phases Phase 0

– Rapid or upstroke depolarization with an influx of sodium ions into the cell

Phase 1

– Early rapid repolarization with transient onward movement of potassium ions

Phase 2

– Plateau Phase: Continued Influx of Sodium and slow Influx of Calcium

Phase 3

– Repolarization: Potassium outflow

Phase 4

– Resting Phase

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Action Potential of a Cardiac Cell

5 Phases Phase 0

– Rapid or upstroke depolarization with an influx of sodium ions into the cell

Phase 1

– Early rapid repolarization with transient onward movement of potassium ions

Phase 2

– Plateau Phase: Continued Influx of Sodium and slow Influx of Calcium

Phase 3

– Repolarization: Potassium outflow

Phase 4

– Resting Phase

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Action Potential of a Cardiac Cell

Refractory Periods • ERP - Effective Refractory Period

– AKA: Absolute Refractory Period

– Phases 0, 1, 2, and early Phase 3

– A depolarization cannot be initiated by an impulse of any strength

• RRP - Relative Refractory Period

– Late Phase 2 and early Phase 3

– A strong impulse can cause depolarization, possibly with aberrancy

– “R on T” phenomena

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Causes of Rhythm Disorders

Congenital

• Present at birth due to genetics, or conditions during the peri-natal environment

Cardiac and other diseases

• Myocardial Infarction, high blood pressure, cardiomyopathy, valvular heart disease

Acquired

• Medications (even anti-arrhythmic Rx), diet pills, cold remedies, illegal drugs, caffeine and/or alcohol abuse, tobacco use...

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Causes of Rhythm Disorders

Secondary to other conditions

• Hyper-Thyroid

• Neurocardiogenic Syncope

- Hypersensitive Carotid Sinus Syndrome (CSS)

- Vasovagal Syncope (VS)

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Disorders of

Rhythm Disorders 2 Categories

Impulse Formation

Impulse Conduction

• Abnormal Automaticity

• Triggered Activity

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Rhythm Disorders 2 Categories

Impulse Formation

• Abnormal Automaticity

• Triggered Activity

Bradycardia: Abnormally slow rates usually due to diseaseTachycardia: Excessively rapid rates due to ANS

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Rhythm Disorders 2 Categories

Impulse Formation

• Abnormal Automaticity

• Triggered ActivityDepolarization occurring in Phase 3 or 4 of the action potential can trigger arrhythmias

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Mechanisms of Rhythm Disorders Triggered Activity

Early Afterdepolarization • Potential Causes:

- Low potassium blood levels

- Slow heart rate

- Drug toxicity (ex. Quinidine causing

Torsades de Pointes type of VT)

Late Afterdepolarization• Potential Causes:

- Premature beats

- Increased calcium blood levels

- Increased adrenaline levels

- Digitalis toxicity

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Rhythm Disorders Two Categories

Impulse Formation

Impulse Conduction

• Abnormal Automaticity

• Triggered Activity

• Slow or Blocked Conduction• Reentry

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Mechanisms of Rhythm Disorders Slowed or Blocked Conduction

• Impulse generated normally

• Impulse slowed or blocked as it makes its way through the conduction system

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Rhythm Disorders Two Categories

Impulse Formation

Impulse Conduction

• Abnormal Automaticity

• Triggered Activity

• Slow or Blocked Conduction• Reentry

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Mechanisms of Rhythm DisordersReentry Model

Conduction paths are “mirrored”

Pathway A:

• Slow conduction but short (fast) refractory

Pathway B:

• Fast conduction but long (slow) refractory period

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By the time the slow antegrade conduction is complete, the fast pathway is no longer refractory, allowing retrograde conduction to occur.

Mechanisms of Rhythm DisordersReentry Model

A premature event occurs, which is conducted down the slow pathway. During this “antegrade” conduction, the fast or “retrograde” pathway is still refractory

This “circus” mechanism is maintained as long as the relationship between fast and slow conduction, and fast/slow refractoriness persists.

A premature event occurs, which is conducted down the slow pathway. During this “antegrade” conduction, the fast or “retrograde” pathway is still refractory.

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Mechanisms of Rhythm DisordersReentry Model

These are sometimes referred to as “circus tachycardias.” This mechanism explains one common arrhythmia seen in the EP lab: AV node re-entrant tachycardia.

Note the almost simultaneous depolarization of the atria and ventricles.

V-V Intervals ms

A-V Intervals ms

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Terminating Reentry

• Spontaneous termination

– Another premature beat that disturbs the underlying conduction/refractoriness relationships

• Pace the heart at a rate above the tachycardia rate

– Abruptly stop pacing

– This is how implantable cardioverter-defibrillators can stop VT without a shock (ATP)

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Disorders of

Bradycardia Classifications

Impulse Formation

Impulse Conduction

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Bradycardia Classifications

Impulse Formation

Impulse Conduction

• Sinus Arrest

• Brady/Tachy Syndrome

• Sinus Bradycardia

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Sinus Arrest

• Failure of sinus node discharge

• Absence of atrial depolarization

• Periods of ventricular asystole

• May be episodic as in vaso-vagal syncope, or carotid sinus hypersensitivity

– May require a pacemaker

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Sinus Bradycardia

• Sinus Node depolarizes very slowly

• If the patient is symptomatic and the rhythm is persistent and irreversible, may require a pacemaker

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Brady/Tachy Syndrome• Intermittent episodes of slow and fast rates from the SA node

or atria

• Brady < 60 bpm

• Tachy > 100 bpm

• AKA: Sinus Node Disease

– Patient may also have periods of AF and chronotropic incompetence

– 75-80% of pacemakers implanted for this diagnosis

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Impulse Formation

Impulse Conduction

• Sinus Arrest

• Brady/Tachy Syndrome

• Sinus Bradycardia

• Exit Block

• Bi/Trifascicular Block

• 1st Degree AV Block

• 2nd Degree AV Block

• 3rd Degree AV Block

Bradycardia Classifications

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Exit Block

• Transient block of impulses from the SA node

– Sinus Wenckebach is possible, but rare

• Pacing is rare unless symptomatic, irreversible, and persistent

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First-Degree AV Block

• PR interval > 200 ms

• Delayed conduction through the AV Node

- Example shows PR Interval = 320 ms

- Not an indication for pacing

- Some consider this a normal variant (not an arrhythmia)

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Second-Degree AV Block – Mobitz I

• Progressive prolongation of the PR interval until there is failure to conduct and a ventricular beat is dropped

• AKA: Wenckebach block– Usually not an indication for pacing

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Second-Degree AV Block – Mobitz II

• Regularly dropped ventricular beats

– 2:1 block (2 P-waves for every 1 QRS complex)

– Atrial rate = 75 bpm, Ventricular rate = 42 bpm

• A “high grade” block, usually an indication for pacing

– May progress to third-degree, or Complete Heart block (CHB)

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Third-Degree AV Block

• No impulse conduction from the atria to the ventricles

– Atrial rate = 130 bpm, Ventricular rate = 37 bpm

– Complete A – V disassociation

– Usually a wide QRS as ventricular rate is idioventricular

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Fascicular Block

Right bundle branch block

and left anterior hemiblock

Right bundle branch block and left posterior hemiblock

Complete left bundle branch block

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Trifascicular Block

• Complete block in the right bundle branch, and

• Complete or incomplete block in both divisions of the left bundle branch

• Identified by EP Study

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Impulse Formation

Impulse Conduction

• Sinus Arrest

• Brady/Tachy Syndrome

• Sinus Bradycardia

• Exit Block

• Bi/Trifascicular Block

• 1st Degree AV Block

• 2nd Degree AV Block

• 3rd Degree AV Block

Bradycardia Classifications Summary

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Status Check

• What is the most likely rhythm disorder that might result in a patient getting a pacemaker?

– Sinus node disease

• Sinus node disease is otherwise known as?

– Brady-tachy syndrome

• What are some symptoms a patient might complain of?

– Fatigue, shortness of breath, palpitations, inability to perform activities of daily living, vertigo, syncope, racing heart at rest, slow pulse rate

Click for Answer

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Status Check

• What are some simple diagnostic tests used to make this diagnosis?

– 12-lead ECG, GXT, Ambulatory ECG (Holter)

Click for Answer

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Terms Describing Ventricular Tachycardias• Paroxysmal (may be used with VT or SVT)

– Ectopic focus, sudden onset, abrupt cessation

• Sustained (usually used with VT)

– Duration of > 30 seconds

– Requires intervention to terminate

• Non-Sustained (usually used with VT)

– At least 6 beats or < 30 seconds

– Spontaneously terminates

• Recurrent (usually used with VT)

– Occurs periodically

– Periods of no tachycardia are longer than periods of tachycardia

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Terms Describing Ventricular Tachycardias

• Monomorphic

– Single focus

– Complexes are similar with equal intervals

• Polymorphic

– Multiple foci

– Complexes appear different with varied intervals

• Incessant

– Long periods of tachy, short periods of NSR

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Terms Describing SVT

• SVTs (Supraventricular Tachycardia)—originating from above the ventricles

–Paroxysmal: Sudden onset and spontaneous cessation

–Persistent: Requires intervention to terminate, usually >24-48 hour duration

–Permanent or Chronic: Unable to terminate

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Disorders of

Tachycardia Classifications

Impulse Formation

Impulse Conduction

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Tachycardia Classifications

Impulse Formation

Impulse Conduction

• Sinus Tachycardia

• Premature Contractions

• Atrial Tachycardia

• Accelerated Junctional Rhythm

• Accelerated Idioventricular Rhythm (AIVR)

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Sinus Tachycardia

• Origin: Sinus Node

• Rate: 100-180 bpm

• Mechanism: Abnormal or Hyper Automaticity (for example, exercise)

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Atrial Tachycardia

•Origin: Atrium - Ectopic Focus

•Rate: >100 bpm

•Mechanism: Abnormal Automaticity

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Premature Beats Premature Atrial Contraction (PAC)

• Origin: Atrium (outside the Sinus Node)

• Mechanism: Abnormal Automaticity

• Characteristics: An abnormal P-wave occurring earlier than expected, followed by compensatory pause

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• Origin: AV Node Junction

• Mechanism: Abnormal Automaticity

• Characteristics: A normally conducted complex with an absent P-wave, followed by a compensatory pause

Premature Beats Premature Junctional Contraction (PJC)

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• Origin: Ventricles

• Mechanism: Abnormal Automaticity

• Characteristics: A broad complex occurring earlier than expected, followed by a compensatory pause

Premature Beats Premature Ventricular Contraction (PVC)

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PVC Patterns

Bigeminy- Every other beat

Trigeminy- Every third beat

Quadrigeminy- Every fourth beat

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• Origin: Varies within the Ventricle

• Mechanism: Abnormal Automaticity

• Characteristics: Each premature beat changes axis; implies a different focus

of origin for each beat

• Note: PVCs by themselves are not a predictor of VT/VF, nor do they imply

the need for a defibrillator

Multifocal PVC

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Accelerated Junctional Rhythm

• Origin: AV Node or Junctional Tissue

• Mechanism: Abnormal Automaticity• Characteristics: Occurs when AV nodal cells depolarize at a rate

faster than the sinus node

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Accelerated Idioventricular Rhythm

• Origin: Ventricle

• Mechanism: Abnormal Automaticity

• Rate: Ventricular rate >sinus rate, but <VT

• Characteristic: May dominate and take over the underlying rhythm

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Accelerated Idioventricular Rhythm

Sinus Rhythm being taken over by an Idioventricular Rhythm

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Tachycardia ClassificationsBased on disorder

Impulse Formation

Impulse Conduction

• Sinus Tachycardia

• Premature Contractions

• Atrial Tachycardia

• Accelerated Junctional Rhythm

• Accelerated Idioventricular Rhythm (AIVR)

• Atrial Flutter

• Atrial Fibrillation• AVRT/AVNRT• Ventricular Tachycardia

• Ventricular Fibrillation

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Atrial Flutter

•Origin: Right and Left Atrium

•Mechanism: Reentry, circus tachycardia, may be “clockwise” or “counter-clockwise”

•Rate: 250 – 400 bpm

•Characteristics: Rapid, regular P-waves, regular R-waves

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• Origin: Right and/or left atrium, pulmonary veins

• Mechanism: Multiple wavelets of reentry• Atrial Rate: > 400 bpm• Characteristics: Random, chaotic rhythm; associated with irregular

ventricular rhythm

Atrial Fibrillation (AF)

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Atrial Fibrillation (AF)

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AF Mechanism

• Paroxysmal: Sudden onset and spontaneous cessation

• Persistent: Requires intervention to terminate, usually > 24-48 hour duration

• Permanent or Chronic: Unable to terminate

• “AF begets AF”

– The more frequent the AF the more frequently it will re-occur and episodes tend to last longer

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Mutifocal Atrial Tachycardia • Mechanism: Abnormal Automaticity

(multi-sites) • Characteristics: Many depolarization

waves; activation occurs asynchronouslyNot commonly used terms anymore,

usually just called “AF”

Other AF Mechanisms

Single Foci• Mechanism: Abnormal Automaticity (single-

focus, usually in the Posterior Left Atrium)• Characteristics: Rapid discharge; single

ectopic site • Parasystole – rare

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Atrial Flutter vs. Atrial Fibrillation

Summary of Disease Characteristics

Atrial Flutter Atrial Fibrillation

Atrial Rate 250 to 400 bpm 400 bpm

Ventricular Rate/Rhythm

Usually regular Varies with conduction

Grossly irregular

Pattern Saw tooth baseline Irregular or almost flat baseline

“Irregularly irregular”

Underlying Mechanism Reentry via macro re-entrant circuit

Typically multiple wavelet reentry

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AVRTAV Re-entrant Tachycardia

• An SVT caused by the existence of an extra pathway from the atria to the ventricles

– Extra pathway + AV Node = reentry

• Two Types

– Orthodromic

– Antidromic

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Orthodromic• Mechanism: Reentry

• Rate: 180 - 260 bpm+

• Characteristics: Extra electrical pathway to ventricles

AVRT

Accessory PathwayConduction to the ventricles via the AV node (normal conduction) - then from Ventricles to the Atria via the accessory pathway. Produces narrow complex SVT.

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Antidromic• Mechanism: Reentry

• Rate: 180 - 260 bpm+

• Characteristics: Extra electrical pathway to ventricles. Wide-complex QRS.

AVRT

Accessory PathwayConduction to ventricles via the accessory pathway. The impulse is then conducted retrograde to atrial via the AV node. Produces a wide-complex SVT.

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• Origin: A - V conduction outside the AV node. The Wolff pathway conducts faster than the AV node

• Mechanism: Reentry

• Rate: 180-260 bpm – can be faster

• Characteristics: Short PR Interval (< 120 ms), wide QRS (> 110 ms), obvious delta wave

Wolff-Parkinson-White

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• Origin: AV Node• Mechanism: Reentry• Rate: 150 - 230 bpm, faster in teenagers• Characteristics: Normal QRS with absent P-waves

AVNRTAV Node Re-entrant Tachycardia

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AVRT vs. AVNRT

• AVRT

– 180 – 260 bpm

– Narrow QRS if orthodromic

– Wide QRS if antidromic

– Delta wave + in SR

– PR < 120 msec

– 1:1 Conduction

• AVNRT

– 150 – 230 bpm

– Narrow QRS

– Short RP

– No delta waves

– Initiating PR long

– P-waves buried in QRS

– Conduction 1:1, or 2:1 when distal block present

Treatment:

• Ablation

• Rarely is a pacemaker implanted

– Perhaps if AV node is injured during ablation

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Tachycardia ClassificationsBased on disorder

Impulse Formation

Impulse Conduction

• Sinus Tachycardia

• Premature Contractions

• Atrial Tachycardia

• Accelerated Junctional Rhythm

• Accelerated Idioventricular Rhythm (AIVR)

• Atrial Flutter

• Atrial Fibrillation• AVRT/AVNRT• Ventricular Tachycardia

• Ventricular Fibrillation

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Monomorphic VT Classification Based on ECG Morphology

• Origin: Ventricles (Single Focus)

• Mechanism: Reentry initiated by abnormal automaticity or triggered activity

• Characteristics: Rapid, wide and regular QRS. A-V disassociation

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• Origin: Ventricles (Wandering Single Focus)

• Mechanism: Reentry with movement in the circuit initiated by abnormal automaticity or triggered activity

• Characteristics: Wide and irregular QRS Complex that changes in axis

Polymorphic VT

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• Origin: Ventricle

• Mechanism: Reentry (movement in focus)

• Rate: 200 – 250 bpm• Characteristics: Associated with Long QT interval; QRS changes axis

and morphology with alternating positive/negative complexes

Torsades de Pointes“Twisting of the points”

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• Origin: Ventricle

• Mechanism: Multiple wavelets of reentry

• Characteristics: Irregular with no discrete QRS

Ventricular Fibrillation (VF)

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Tachycardia ClassificationsSummary

Impulse Formation

Impulse Conduction

• Sinus Tachycardia

• Premature Contractions

• Atrial Tachycardia

• Accelerated Junctional Rhythm

• Accelerated Idioventricular Rhythm (AIVR)

• Atrial Flutter

• Atrial Fibrillation• AVRT/AVNRT• Ventricular Tachycardia

• Ventricular Fibrillation

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Status CheckIdentify the Rhythm

• Ventricular Tachycardia

• Sinus Bradycardia

• Complete Heart Block

• Atrial Fibrillation

• Ventricular Fibrillation

Click for Answer

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Status CheckIdentify the Rhythm

• Ventricular Tachycardia

• Sinus Bradycardia

• Complete Heart Block

• Atrial Fibrillation

• Ventricular Fibrillation

Click for Answer

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Status CheckIdentify the Rhythm

• Ventricular Tachycardia

• Sinus Bradycardia

• Complete Heart Block

• Atrial Fibrillation

• Ventricular Fibrillation

Click for Answer

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Status CheckIdentify the Rhythm

• Ventricular Tachycardia

• Sinus Bradycardia

• Complete Heart Block

• Atrial Fibrillation

• Ventricular Fibrillation

Click for Answer

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Status Check

• Ventricular Tachycardia

• Sinus Bradycardia

• Complete Heart Block

• Atrial Fibrillation

• Ventricular Fibrillation

Click for Answer

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Upcoming Modules

• The Fundamentals of Cardiac Devices

• Basic Concepts—Electricity and Pacemakers

• Applying Electrical Concepts to Pacemakers

• Pacemaker Basics

• Single and Dual Chamber Pacemaker Timing

• Advanced Pacemaker Operations

• Pacemaker Patient Follow-up

• Pacemaker Troubleshooting

• Pacemaker Automatic Features

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Disclosure

NOTE:

This presentation is provided for general educational purposes only and should not be considered the exclusive source for this type of information. At all times, it is the professional responsibility of the practitioner to exercise independent clinical judgment in a particular situation.

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Brief Statements

Indications

• Implantable Pulse Generators (IPGs) are indicated for rate adaptive pacing in patients who ay benefit from increased pacing rates concurrent with increases in activity and increases in activity and/or minute ventilation. Pacemakers are also indicated for dual chamber and atrial tracking modes in patients who may benefit from maintenance of AV synchrony. Dual chamber modes are specifically indicated for treatment of conduction disorders that require restoration of both rate and AV synchrony, which include various degrees of AV block to maintain the atrial contribution to cardiac output and VVI intolerance (e.g. pacemaker syndrome) in the presence of persistent sinus rhythm.

• Implantable cardioverter defibrillators (ICDs) are indicated for ventricular antitachycardia pacing and ventricular defibrillation for automated treatment of life-threatening ventricular arrhythmias.

• Cardiac Resynchronization Therapy (CRT) ICDs are indicated for ventricular antitachycardia pacing and ventricular defibrillation for automated treatment of life-threatening ventricular arrhythmias and for the reduction of the symptoms of moderate to severe heart failure (NYHA Functional Class III or IV) in those patients who remain symptomatic despite stable, optimal medical therapy and have a left ventricular ejection fraction less than or equal to 35% and a QRS duration of ≥130 ms.

• CRT IPGs are indicated for the reduction of the symptoms of moderate to severe heart failure (NYHA Functional Class III or IV) in those patients who remain symptomatic despite stable, optimal medical therapy, and have a left ventricular ejection fraction less than or equal to 35% and a QRS duration of ≥130 ms.

Contraindications

• IPGs and CRT IPGs are contraindicated for dual chamber atrial pacing in patients with chronic refractory atrial tachyarrhythmias; asynchronous pacing in the presence (or likelihood) of competitive paced and intrinsic rhythms; unipolar pacing for patients with an implanted cardioverter defibrillator because it may cause unwanted delivery or inhibition of ICD therapy; and certain IPGs are contraindicated for use with epicardial leads and with abdominal implantation.

• ICDs and CRT ICDs are contraindicated in patients whose ventricular tachyarrhythmias may have transient or reversible causes, patients with incessant VT or VF, and for patients who have a unipolar pacemaker. ICDs are also contraindicated for patients whose primary disorder is bradyarrhythmia.

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Brief Statements (continued)

Warnings/Precautions

• Changes in a patient’s disease and/or medications may alter the efficacy of the device’s programmed parameters. Patients should avoid sources of magnetic and electromagnetic radiation to avoid possible underdetection, inappropriate sensing and/or therapy delivery, tissue damage, induction of an arrhythmia, device electrical reset or device damage. Do not place transthoracic defibrillation paddles directly over the device. Additionally, for CRT ICDs and CRT IPGs, certain programming and device operations may not provide cardiac resynchronization. Also for CRT IPGs, Elective Replacement Indicator (ERI) results in the device switching to VVI pacing at 65 ppm. In this mode, patients may experience loss of cardiac resynchronization therapy and / or loss of AV synchrony. For this reason, the device should be replaced prior to ERI being set.

Potential complications

• Potential complications include, but are not limited to, rejection phenomena, erosion through the skin, muscle or nerve stimulation, oversensing, failure to detect and/or terminate arrhythmia episodes, and surgical complications such as hematoma, infection, inflammation, and thrombosis. An additional complication for ICDs and CRT ICDs is the acceleration of ventricular tachycardia.

• See the device manual for detailed information regarding the implant procedure, indications, contraindications, warnings, precautions, and potential complications/adverse events. For further information, please call Medtronic at 1-800-328-2518 and/or consult Medtronic’s website at www.medtronic.com.

Caution: Federal law (USA) restricts these devices to sale by or on the order of a physician.

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Brief Statement: Medtronic Leads

Indications

• Medtronic leads are used as part of a cardiac rhythm disease management system. Leads are intended for pacing and sensing and/or defibrillation. Defibrillation leads have application for patients for whom implantable cardioverter defibrillation is indicated

Contraindications

• Medtronic leads are contraindicated for the following:

• ventricular use in patients with tricuspid valvular disease or a tricuspid mechanical heart valve.

• patients for whom a single dose of 1.0 mg of dexamethasone sodium phosphate or dexamethasone acetate may be contraindicated. (includes all leads which contain these steroids)

• Epicardial leads should not be used on patients with a heavily infracted or fibrotic myocardium.

• The SelectSecure Model 3830 Lead is also contraindicated for the following:

• patients for whom a single dose of 40.µg of beclomethasone dipropionate may be contraindicated.

• patients with obstructed or inadequate vasculature for intravenous catheterization.

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Brief Statement: Medtronic Leads (continued)

Warnings/Precautions

• People with metal implants such as pacemakers, implantable cardioverter defibrillators (ICDs), and accompanying leads should not receive diathermy treatment. The interaction between the implant and diathermy can cause tissue damage, fibrillation, or damage to the device components, which could result in serious injury, loss of therapy, or the need to reprogram or replace the device.

• For the SelectSecure Model 3830 lead, total patient exposure to beclomethasone 17,21-dipropionate should be considered when implanting multiple leads. No drug interactions with inhaled beclomethasone 17,21-dipropionate have been described. Drug interactions of beclomethasone 17,21-dipropionate with the Model 3830 lead have not been studied.

Potential Complications

• Potential complications include, but are not limited to, valve damage, fibrillation and other arrhythmias, thrombosis, thrombotic and air embolism, cardiac perforation, heart wall rupture, cardiac tamponade, muscle or nerve stimulation, pericardial rub, infection, myocardial irritability, and pneumothorax. Other potential complications related to the lead may include lead dislodgement, lead conductor fracture, insulation failure, threshold elevation or exit block.

• See specific device manual for detailed information regarding the implant procedure, indications, contraindications, warnings, precautions, and potential complications/adverse events. For further information, please call Medtronic at 1-800-328-2518 and/or consult Medtronic’s website at www.medtronic.com.

Caution: Federal law (USA) restricts this device to sale by or on the order of a physician.