Pacemaker Overview

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Pacemaker OverviewPacemaker Overview

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Technical Head

Southampton General

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Indications for PacingIndications for PacingIndications for PacingIndications for Pacing

The normal & pathological ECG

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Impulse Formation and Conduction Disturbances

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““Normal Heart Rhythm” Normal Heart Rhythm” (Function)(Function)

““Normal Heart Rhythm” Normal Heart Rhythm” (Function)(Function)

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Sinoatrial Node

Normal Heart Function

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Atrioventricular Node

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Bundle of HIS


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Left Bundle Branch (LBB)

Anterior Fascicle of LBB

Posterior Fascicle of LBB

Right Bundle Branch (RBB)

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Purkinje Fibers

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Vent. Systole

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Vent. Diastole

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The ECGThe ECG

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Normal Values

• PR Interval: 120 to 210 msec

• QRS Interval: 80 to 110 msec

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60,000 Interval

= Heart Rate

Rate:Interval Relationship

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The Rate isThe Rate is : ? ? : ? ?

Interval : 750 msecInterval : 750 msec


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The Rate isThe Rate is : :750750

Interval : 750 msecInterval : 750 msec

60,0060,0000 80 bpm80 bpm


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The interval is :The interval is : 5050

Rate : 50 bpmRate : 50 bpm

60,0060,0000 1200 ms1200 ms


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Interval (ms) 200 400 600 800 1000 1200 1400 1600

Rate (bpm/ppm) 300 150 100 75 60 50 43 37.5

Interval (ms) 200 400 600 800 1000 1200 1400 1600

Rate (bpm/ppm) 300 150 100 75 60 50 43 37.5

At a paper speed of 25mm/sec


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25 mm is 1 sec.

5 mm = 0.2 sec.

1 mm = 0.04 sec.

25 mm/second


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““Abnormal Heart Rhythm”Abnormal Heart Rhythm”(Indications for Pacing)(Indications for Pacing)

““Abnormal Heart Rhythm”Abnormal Heart Rhythm”(Indications for Pacing)(Indications for Pacing)

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Definitions....

• Bradycardia: R < 60 bpm

• Tachycardia: R > 100 bpm

• Flutter: R > 250 bpm

• Fibrillation: R > 350 bpm

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Pacemaker Indication Classifications

Class I – Conditions for which there is evidence and/or general agreement that permanent pacemakers should be implanted

Class II – Conditions for which permanent pacemakers are frequently used but there is divergence of opinion with respect to the necessity of their insertion

– Class IIa: Weight of evidence/opinion is in favor of usefulness/efficacy

– Class IIb: Usefulness/efficacy is less well established by evidence/opinion

Class III – Conditions for which there is general agreement that pacemakers are unnecessary

JACC Vol. 31, no. 5 April 1998, 1175-1209

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Pacemaker Indication Classifications

• Evidence supporting current recommendations are ranked as levels A, B, and C:

– Level A: Data derived from multiple randomised clinical trials involving a large number of individuals

– Level B: Data derived from a limited number of trials involving comparatively small numbers of patients or from well-designed data analysis of nonrandomised studies or observational data registries

– Level C: Consensus of expert opinion was the primary source of recommendation

JACC Vol. 31, no. 5 April 1998, 1175-1209

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Sinus Node Dysfunction

• Sick Sinus Syndrome• Sinus bradycardia• Sinus arrest• SA block• Brady-tachy syndrome• Chronotropic

incompetence (CI)

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Class I Indications

• Sinus node dysfunction with documentedSinus node dysfunction with documented symptomatic sinus symptomatic sinus bradycardiabradycardia

• Symptomatic chronotropic incompetence

Class II Indications

• Class IIa: Symptomatic patients with sinus node dysfunction and with no clear association between symptoms and bradycardia

• Class IIb: Chronic heart rate < 30 bpm in minimally symptomatic patients while awake

Class III Indications

• Asymptomatic sinus node dysfunction

Sinus Node Dysfunction – Indications for Pacemaker Implantation

JACC Vol. 31, no. 5 April 1998, 1175-1209

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Sinus Node Dysfunction –Sinus Bradycardia

• Persistent slow rate from the SA node. The parameters from this waveform include:– Rate = 55 bpm– PR interval = 180 ms (0.18 seconds)

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Sinus Node Dysfunction –Sinus Arrest

• Failure of sinus node discharge resulting in the absence of atrial depolarisation and periods of ventricular asystole

– Rate = 75 bpm

– PR interval = 180 ms (0.18 seconds)

– 2.8 second arrest

2.8-second arrest

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2.1-second pause

Sinus Node Dysfunction –SA Exit Block

• Transient blockage of impulses from the SA node– Rate = 52 bpm– PR interval = 180 ms (0.18 seconds)– 2.1-second pause

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Sinus Node Dysfunction – Brady-Tachy Syndrome

• Intermittent episodes of slow and fast rates from the SA node or atria– Rate during bradycardia = 43 bpm– Rate during tachycardia = 130 bpm

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Chronotropic Incompetence (CI)

Max

Rest

HeartRate

TimeStart

ActivityStop

Activity

Quick

Unstable

Slow

Normal CI

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AV Block

• First-degree AV block• Second-degree AV block

– Mobitz types I and II• Third-degree AV block

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Class I Indications

• 3rd degree AV block associated with:– Symptomatic bradycardia (including those from arrhythmias and other

medical conditions)

– Documented periods of asystole > 3 seconds

– Escape rate < 40 bpm in awake, symptom-free patients

– Post AV junction ablation

– Post-operative AV block not expected to resolve

• Second degree AV block regardless of type or site of block, with associated symptomatic bradycardia

AV Block – Indications

JACC Vol.. 31, no. 5 April 1998, 1175-1209

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JACC Vol. 31, no. 5 April 1998, 1175-1209


• Class IIa:

– Asymptomatic CHB with a ventricular rate > 40 bpm

– Asymptomatic Type II 2nd degree AV block

– Asymptomatic Type I 2nd degree AV block within the His-Purkinje system found incidentally at EP study

– First-degree AV block with symptoms suggestive of pacemaker syndrome and documented alleviation of symptoms with temporary AV pacing

• Class IIb:

– First degree AV block > 300 ms in patients with LV dysfunction in whom a shorter AV interval results in haemodynamic improvement

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• Asymptomatic 1st degree AV block

• Asymptomatic Type I 2nd degree AV block at supra-Hisian level

• AV block expected to resolve and unlikely to recur (e.g., drug toxicity, Lyme Disease)

JACC Vol. 31, no. 5 April 1998, 1175-1209

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First-Degree AV Block

• AV conduction is delayed, and the PR interval is prolonged (> 210 ms or 0.21 seconds)– Rate = 79 bpm– PR interval = 340 ms (0.34 seconds)

340 ms

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Second-Degree AV Block – Mobitz I (Wenckebach)

• Progressive prolongation of the PR interval until a ventricular beat is dropped

– Ventricular rate = irregular

– Atrial rate = 90 bpm

– PR interval = progressively longer until a P-wave fails to conduct

200 360 400ms ms ms

NoQRS

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Second-Degree AV Block – Mobitz II

• Regularly dropped ventricular beats– 2:1 block (2 P waves to 1 QRS complex)

– Ventricular rate = 60 bpm

– Atrial rate = 120 bpm

P P QRS

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Third-Degree AV Block

• No impulse conduction from the atria to the ventricles– Ventricular rate = 37 bpm– Atrial rate = 130 bpm– PR interval = variable

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Bifascicular / Trifascicular Block

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Class I Indications

• Intermittent 3rd degree AV block

• Type II 2nd degree AV block


• Class IIa: – Syncope not proved to be due to AV block when other causes have been exluded,

specifically VT

– Prolonged HV interval ( >100 ms)

– Pacing-induced infra-Hisian block that is not physiological

• Class IIb: None


• Asymptomatic fascicular block without AV block

• Asymptomatic fascicular block with 1st degree AV block

Bifascicular and Trifascicular Block (Chronic) – Indications

JACC Vol. 31, no. 5 April 1998, 1175-1209

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Bifascicular Block

Right bundle branch block and left

posterior hemiblock

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Bifascicular Block

Right bundle branch block

and left anterior hemiblock

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Bifascicular Block

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

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ECG Recording:ECG Recording:

• Rate

• Rhythm–regular or irregular?–if irregular, is there a pattern?

(e.g. 2:1 or 3:1 block or Wenckebach)

• QRS-complexes? Width?

• P-waves? In what relation to QRS-complexes?

• PR-Interval with normal duration (120-210 ms) or irregular? Continuously increasing P-R interval?

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What is a Pacemaker?What is a Pacemaker?What is a Pacemaker?What is a Pacemaker?

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What is a Pacemaker?What is a Pacemaker?What is a Pacemaker?What is a Pacemaker?

A Pacemaker System consists of a Pulse Generator plus Lead (s)

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What is a Pacemaker?What is a Pacemaker?

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• Pulse generator: power source or battery

• Leads or wires

• Cathode (negative electrode)

• Anode (positive electrode)

• Body tissue

IPG

Lead

Anode

Cathode

Implantable Pacemaker Systems Contain the Following Components:

Implantable Pacemaker Systems Contain the Following Components:

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• Contains a battery that provides the energy for sending electrical impulses to the heart

• Houses the circuitry that controls pacemaker operations

Circuitry

Battery

The Pulse Generator:The Pulse Generator:

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Battery

Connector

Hybrid

Telemetry antenna

Output capacitors

Reed (Magnet) switch

Clock

Defibrillation protection

Atrial connector

Ventricular connector

Resistors

Anatomy of a PacemakerAnatomy of a Pacemaker

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Components of an IPGComponents of an IPG

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What is a Pacemaker?What is a Pacemaker?

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• Deliver electrical impulses from the pulse generator to the heart

• Sense cardiac depolarisation

Lead

Leads Are Insulated Wires That:Leads Are Insulated Wires That:

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Conductor Tip Electrode Insulation Connector Pin

Pacing Lead ComponentsPacing Lead Components

• Conductor

• Connector Pin

• Insulation

• Electrode

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How do pacemakers work?How do pacemakers work?How do pacemakers work?How do pacemakers work?

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How do pacemakers work?• Modes and Codes

– NBG Code– Mode Selection– Indications for Pacing – Pacing Modes

• Sensing & Pacing

• Pacemaker Timing

• Pacemaker Therapies (Operation) & Diagnostics

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Modes and CodesModes and CodesModes and CodesModes and Codes

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NBG CodeI

ChamberPaced

IIChamberSensed

IIIResponseto Sensing

IVProgrammableFunctions/Rate

Modulation

VAntitachy

Function(s)

V: Ventricle V: Ventricle T: Triggered P: Simple programmable

P: Pace

A: Atrium A: Atrium I: InhibitedM: Multi- programmable

S: Shock

D: Dual (A+V) D: Dual (A+V) D: Dual (T+I) C: Communicating D: Dual (P+S)

O: None O: None O: None R: Rate modulating O: None

S: Single (A or V)

S: Single (A or V)

O: None

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Mode Selection for Optimal Mode Selection for Optimal Pacing TherapyPacing Therapy

Mode Selection for Optimal Mode Selection for Optimal Pacing TherapyPacing Therapy

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Providing Optimal Pacing Therapy

Providing Optimal Pacing Therapy

• Heart rate increase

• Stroke volume maximisation

• Atrial based pacing

• Normal ventricular activation sequence

• (Patient outcomes and costs if optimal pacing therapy/mode is not chosen)

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Cardiac OutputCardiac OutputCardiac OutputCardiac Output

Cardiac Output (l/min)=

Heart Rate x Stroke Volume

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Heart RateHeart Rate

x

x

xx

SV

x HR

Age 65-80 (N=16)

130

120

110

100

90

80

70

He

art

Ra

te (

BP

M)

Stro

ke V

olu

me

(mL

/Min

)

Cardiac Output (L/Min)

Rodehefer RJ, Circ.; 69:203, 1984.

6 7 8 9 10 11 12 13 14 15 1613 17 18708090

100110120130140150160

x

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Proven Benefits of Atrial Based PacingProven Benefits of Atrial Based Pacing

Study Results

Higano et al. 1990

Gallik et al. 1994

Santini et al. 1991

Rosenqvist et al. 1991

Sulke et al. 1992

Improved cardiac index during low levelexercise (where most patient activity occurs)

Increase in LV filling

30% increase in resting cardiac output

Decrease in pulmonary wedge pressure

Increase in resting cardiac output

Increase in resting cardiac output, especiallyin patients with poor LV function

Decreased incidence of mitral and tricuspidvalve regurgitation

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Proven Benefits of Atrial Based PacingProven Benefits of Atrial Based Pacing

Study Results

Rosenquist 1988

Santini 1990

Stangl 1990

Zanini 1990

Less atrial fibrillation (AF), less CHF, improved survival after 4 years compared to VVI

Less AF, improved survival after 5 years average

Less AF, improved survival after 5 years compared to VVI

Suppression of atrial dysrhythmias

Improved morbidity (less AF, CHF, embolic events) after 3 plus uears, compared to VVI

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Patient Mode PreferencePatient Mode Preference

DDDR 59%

DDIR 13%Any Dual 9%

No Preference 9%

DDD 5%

VVIR 5%

Sulke N, et al. J AM Coll Cardiol; 17(3):696-706, 1991

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Optimal Pacing Mode (BPEG)

• Sinus Node Disease - AAI (R)

• AVB - DDD

• SND + AVB - DDDR + DDIR

• Chronic AF + AVB - VVI (R)

• CSS / MVVS - DDI

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Alternative Pacing Mode

• Sinus Node Disease - AAI

• AVB - VDD

• SND + AVB - DDD + DDI

• Chronic AF + AVB - VVI

• CSS - DDD / VVI

• MVVS - DDD

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Inappropriate Pacing Mode

• Sinus Node Disease - VVI + VDD• AVB - AAI + DDI• SND + AVB - AAI + VVI• Chronic AF + AVB - AAI/DDD/VDD• CSS - AAI+VDD• MVVS - AAI/VVI/VDD

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Mode Selection Decision TreeDDIR with

SV PVARPDDDR with

MS

N

VVIVVIR

Are they chronic?

Y

Y N

DDD, VDDDDDR DDDR

Y N

Is AV conduction intact?

Is SA node functionpresently adequate?

Symptomaticbradycardia

Are atrial tachyarrhythmias

present?

Is SA node functionpresently adequate?

Is AV conduction intact?

Y

Y N

AAIRDDDR

DDD, DDIwith RDR

N N(SSS) (CSS,VVS)

N

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Summary of Pacemaker Indications• Sinus node dysfunction• AV block (Congenital, acquired, surgical)• Bifascicular and trifascicular block• Hypersensitive Carotid Sinus Syndrome (CSS)• [ Malignant Vasovagal Syncope (MVVS) ]• Pacing after cardiac transplantation• Heart Failure / HOCM / AF• ( AHA/ACC and BPEG indications )

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Pacing ModesPacing ModesPacing ModesPacing Modes

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Output circuit

VVI

AMP

Ventricular Demand

Pacing Modes

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Programmed lower rate 50 mm/s

VVI

Pacing Modes

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Output circuit

VVIR

AMP

Sensor

Ventricular Demand

Pacing Modes

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Sensor indicatedrate

VVIR

Pacing Modes

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Sensor indicatedrate

VVIR

Pacing Modes

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Output circuit

AAI

AMP

Atrial Demand

Pacing Modes

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AAI

Pacing Modes

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Output circuit

AAIR

AMP

Atrial Demand

Sensor

Pacing Modes

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AAIR

Sensor indicated rate

Pacing Modes

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Output circuit

VAT

AMP

Atrial Synchronised

Pacing Modes

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Output circuit

DVI

AMP

A-V Sequential

Output circuit

Output circuit

VDD

AMP

AMP

Pacing Modes

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= Refract.Sensing= Blanking= Refract.periode= Stimulatie

= Sensing

V

A

Pacing Modes

VDD

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Output circuit

DVI

AMP

A-V Sequential

Output circuit

Pacing Modes

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DVI

Pacing Modes

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Output circuit

DVIR

AMP

A-V Sequential

Output circuit

Sensor

Pacing Modes

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Output circuit

DDI(R)

AMP

Output circuit

Timing & Control

AMP

A-V UniversalSensor

Pacing Modes

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Output circuit

DVI

AMP

A-V Sequential

Output circuit

Output circuit

DDD

AMP

A-V Universal

Output circuit

Timing & Control

AMP

Pacing Modes

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Output circuit

DVI

AMP

A-V Sequential

Output circuit

Output circuit

DDDR

AMP

A-V Universal

Output circuit

Timing & Control

AMP

Sensor

Pacing Modes

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Pacing Modes - Summary

Output circuit

VAT

AMP

Atrial Synchronised

Output circuit

AAI

AMP

Atrial Demand

Output circuit

DVI

AMP

A-V SequentialOutput circuit

Output circuit

VDD

AMP

Atrial synchronisedVentricular Inhibited

AMP

Output circuit

DDD

AMP

A-V UniversalOutput circuit

Timing & Control

AMP

Output circuit

VVI

AMP

Ventricular Demand

Health & Medicine

Pacemaker Overview