11

Rob LeindersSlides: Tim Jongen

Medtronic Bakken Research Center

Bioelectronica en Nanotechnologie

2008 - 2012

Module: Pacemaker Basics

2Recommended Literature Foundation of Cardiac Pacing. Sutton, Bourgeois, 1991, ISBN 0-

87993-337-2

Design of Cardiac Pacemakers. Webster 1993, ISBN 0-7803-1134-5

Rapid Interpretation of EKGs. Dubin 1970, SBN 0-912912-00-6 The evolution of pacemakers: An electronics perspective, from the

hand crank to advanced wavelet analysis. Haddad AP, Houben RP, Serdijn WA. IEEE Eng Med Biol Mag. 2006 May-Jun; 25(3):38-48

3Pacemaker Basics EGM / ECG

Electrophysiology Measuring Signals 12 Lead ECG

Diseases Bradycardia Tachycardia

Pacemaker: Basics Components Overview Simplified Pacemaker Output Pulse: Width / Amplitude / Capacitor

Sensing Why Sensing Oversensing Undersensing Sensing Hardware

Frequency spectrum Filters Analog to Digital Conversion

Pacemaker: Current Devices ICDs Leads

Unipolar / Bipolar Low voltage / High voltage Active / Passive Fixation Lead Design Lead Implantation

24Practicum

Building a Pacemaker

Program a Pacemaker Simulations with Patient Simulator

11EGM / ECG Measuring Signals

ECG

EGM

2

3Cardiac Conduction - Sinus Node

The Hearts Natural Pacemaker Rate of 60-100 bpm at rest

Sinus Node(SA Node)

24Cardiac Conduction - AV 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)

5Cardiac Conduction - HIS Bundle

Begins conduction to the ventricles

AV Junctional Tissue: Rates between 40-60 bpm

Bundle of His

6Cardiac Conduction - Purkinje Fibers

Bundle Branches and Purkinje Fibers

Moves the impulse through the ventricles

Provides Escape Rhythm: 20-40 bpm

Purkinje Network

37Normal Sinus Rhythm

8Impulse Formation in SA Node

9Atrial Depolarization

410Delay at AV Node

11Conduction through Bundle Branches

12Conduction through Purkinje Fibers

513Ventricular Depolarization

14Plateau Phase of Repolarization

15Final Rapid (Phase 3) Repolarization

616AutomaticityCardiac 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

17Measuring Signals

18ECG

719ECG

20EGM / ECG

21ECG

Precordial Leads: V1 V2 V3 V4 V5 V6

82212 Lead ECG

23EGM Electrogram

Measure locally in Atria or Ventricles

Lead II and RV electrogram Lead II and HRA electrogram

11Diseases Bradycardia

Tachycardia

2Bradycardia

Patient has a slow (Brady: slowness) heart rhythm: Sinus Arrest Brady/Tachy Syndrome Sinus Bradycardia

Exit Block Bi/Trifascicular Block AV Block

3Sinus 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

24Sinus Bradycardia Sinus Node depolarizes very slowly If the patient is symptomatic and the rhythm is persistent and irreversible, may

require a pacemaker

5Brady/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

6Exit Block Transient block of impulses from the SA node

Sinus Wenckebach is possible, but rare Pacing is rare unless symptomatic, irreversible, and persistent

37First-Degree AV Block Standard PR interval 120 200 ms

Delayed conduction through the AV

In most cases no symptoms. No medications or PM therapy is needed. Correcting electrolyte imbalances is standard therapy

8Second-Degree AV Block

Type 1: Wenkebach prolongation of PR interval Type 2: no prolongation

9Third-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

410Fascicular Block

Right bundle branch block and left anterior hemiblock

Right bundle branch block and left posterior hemiblock

Complete left bundle branch block

11Trifascicular 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

12Chronotopic Incompetence

CO = SV x HR Healthy hearts are able to increase peak CO by

up to 5x baseline with exercise Chronotopic Incompotence patients are only able

to increase CO x2 over baseline

513Tachycardia

Sinus Tachycardia

Premature Contractions Atrial Tachycardia

Accelerated Junctional Rhythm Accelerated Idioventricular Rhythm (AIVR)

Atrial Flutter Atrial Fibrillation AVRT/AVNRT Ventricular Tachycardia Ventricular Fibrillation

14Sinus Tachycardia

Origin: Sinus Node Rate: 100-180 bpm Mechanism: Abnormal or Hyper Automaticity (for example, exercise)

15Atrial Tachycardia

Origin: Atrium - Ectopic Focus

Rate: >100 bpm

Mechanism: Abnormal Automaticity

616Premature Beats - PAC

Origin: Atrium (outside the Sinus Node) Mechanism: Abnormal Automaticity

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

17

Origin: AV Node Junction

Mechanism: Abnormal Automaticity

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

Premature Beats - PJC

18

Origin: Ventricles

Mechanism: Abnormal Automaticity Characteristics: A broad complex occurring earlier than expected,

followed by a compensatory pause

Premature Beats - PVC

719PVC Patterns

Bigeminy- Every other beat

Trigeminy- Every third beat

Quadrigeminy- Every fourth beat

20

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

21Accelerated 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

822Accelerated Idioventricular Rhythm

Origin: Ventricle Mechanism: Abnormal Automaticity Rate: Ventricular rate >sinus rate, but

925Reentry

26Reentry

27Atrial Flutter

Origin: Right and Left Atrium

Mechanism: Reentry, circus tachycardia

Rate: 250 400 bpm

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

10

28

Origin: Right and/or left atrium, pulmonary veins Mechanism: Multiple wavelets of reentry Atrial Rate: > 400 bpm Characteristics: Random, chaotic rhythm; associated with irreg. ventricular rhythm

Atrial Fibrillation (AF)

29Atrial Fibrillation (AF)

30AF 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

11

31

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

32Atrial Flutter vs. Atrial FibrillationSummary of Disease Characteristics

Atrial Flutter Atrial Fibrillation

Atrial Rate 250 to 400 bpm 400 bpm

Ventricular Rate/Rhythm Usually regular Varies with conductionGrossly irregular

Pattern Saw tooth baseline Irregular or almost flat baselineIrregularly irregular

Underlying Mechanism Reentry via macro re-entrant circuit

Typically multiple wavelet reentry

33AVRT - AV Re-entrant TachycardiaAn SVT caused by the existence of an extra

pathway from the atria to the ventricles Extra pathway + AV Node = reentry

Two Types Orthodromic Antidromic

12

34

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.

35

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.

36

Origin: A - V conduction outside the AV node (bundle of Kent). The Wolff pathway conducts faster than the AV node

Characteristics: Short PR Interval (< 120 ms), wide QRS (> 110 ms), delta wave Sudden cardiac death in these individuals is due to the propagation of an atrial arrhythmia to the ventricles at a very high rate.

Wolff-Parkinson-White

13

37

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

AVNRT - AV Node Re-entrant Tachycardia

38AVRT 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 presentTreatment: Ablation Rarely is a ICD implanted

39Monomorphic VT Origin: Ventricles (Single Focus) Mechanism: Reentry initiated by abnormal automaticity

or triggered activity Characteristics: Rapid, wide and regular QRS. A-V

disassociation

14

40

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

41

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

42

Origin: Ventricle Mechanism: Multiple wavelets of reentry Characteristics: Irregular with no discrete QRS

Ventricular Fibrillation (VF)

11Pacemaker Basics Components Overview

Simplified Pacemaker

Output Pulse Capacitor Width Amplitude Strength Duration Curve+

2Pacemaker Overview Pulse Generator

Battery, sensing, pulse formation Control (counter), telemetry

Wires (Leads)

3Pacemaker Principle of Operation

24Pacemaker Output

Output pulse Anodal/Cathodal Pulse width Amplitude

5Pacemaker Output

Delivered energy: Strength duration curve

6Pacemaker Output

11Sensing Why Sensing Noise Oversensing Undersensing Sensing Hardware

Frequency spectrum Filters Analog to Digital Conversion

2Sensing Sensing is the ability of the pacemaker to see

when a natural (intrinsic) depolarization is occurring Pacemakers sense cardiac depolarization by

measuring changes in electrical potential of myocardial cells between the anode and cathode

3EGM / ECG

Intrinsic deflection on an EGM occurs when a depolarization wave passes directly under the electrodes

Two characteristics of the EGM are: Signal amplitude Slew rate

24Slew Rate - Change in Voltage with Respect to the Change in Time

The longer the signal takes to move from peak to peak: The lower the slew rate The flatter the signal

Higher slew rates (number in mV) translate to greater sensing Measured in volts per second Vo

ltage

Time

Slope

Slew rate= Change in voltageTime duration ofvoltage change

5Sense and Respond to Cardiac Rhythms Accurate sensing enables the pacemaker to

determine whether or not the heart has created a beat on its own

The pacemaker is usually programmed to respond with a pacing impulse only when the heart fails to produce an intrinsic beat

6Accurate Sensing...

Ensures that undersensing will not occur

Ensures that oversensing will not occur

Provides for proper timing of the pacing pulse

37Undersensing . . . Pacemaker does not see the intrinsic beat, and

therefore does not respond appropriately

Intrinsic beat not sensed

Scheduled pace delivered

VVI / 60

8Oversensing

An electrical signal other than the intended P or R wave is detected

Marker channel shows intrinsic

activity...

...though no activity is present

VVI / 60

9Sensitivity

The Greater the Number, the Less Sensitive the Device to Intracardiac Events

410SensitivityAm

plitu

de (m

V)

Time

5.0

2.5

1.25

11Sensitivity

Ampl

itude

(mV)

Time

5.0

2.5

1.25

12Sensitivity

Ampl

itude

(mV)

Time

5.0

2.5

1.25

513Noise

Sensing amplifiers use filters that allow appropriate sensing of P waves and R waves and reject inappropriate signals

Unwanted signals most commonly sensed are: T waves Far-field events (R waves sensed by the atrial channel) Skeletal myopotentials (e.g., pectoral muscle myopotentials)

14Noise

Electrophysiological signals and interferenceMyopotentials in unipolar EGM resulting from pectoral muscles=> Intermittent, baseline variations

Electromagnetic interference (main 50/60 Hz) picked up by electrode tip- IPG can loop=> Superimposed variations

RV current of injury, (artificial) ST-segment shift. Disappears after approximately 30 min after lead implant

15Accurate Sensing is Dependent on . . . The electrophysiological properties of the

myocardium The characteristics of the electrode and its

placement within the heart The sensing amplifiers of the pacemaker

616Factors That May Affect Sensing Are: Lead polarity (unipolar vs. bipolar) Lead integrity

Insulation break Wire fracture

EMI Electromagnetic Interference

17Unipolar Sensing

Produces a large potential difference due to: A cathode and anode

that are further apart than in a bipolar system

_

18Bipolar Sensing

Produces a smaller potential difference due to the short interelectrode distance Electrical signals from

outside the heart such as myopotentials are less likely to be sensed

719An Insulation Break

May Cause Both Undersensing or Oversensing Undersensing occurs when inner and outer conductor

coils are in continuous contact Signals from intrinsic beats are reduced at the sense

amplifier and amplitude no longer meets the programmed sensing value

Oversensing occurs when inner and outer conductor coils make intermittent contact Signals are incorrectly interpreted as P or R waves

20A Wire Fracture

Can Cause Both Undersensing and Oversensing

Undersensing occurs when the cardiac signal is unable to get back to the pacemaker intrinsic signals cannot cross the wire fracture

Oversensing occurs when the severed ends of the wire intermittently make contact, which creates potentials interpreted by the pacemaker as P or R waves

21Sensing Hardware

11

Pacemakers

2Pacemaker Parts

PacemakerCan

Connector Block

Leads

SensingCircuit

OutputStage

Battery

BatteryEOL circuit

TelemetrySystem

Antenna

Sensor(s)

SensorInterfaceFeed-throughs

Bonding wires

Mechanical Electronics

Timing/ControlCircuits

TelemetryProtocol SW

SoftwareAlgorithms

Memory

Microprocessor

AD Converter

Software Other

Hybrid

3

Telemetry

24Pacemaker Telemetry

Pacemaker TelemetryVoltage

regulators Transceiver

DecodingCoding

Logic control unitTimebase

Telemetry front-end

Coupled coils175 KHz AM, PModulatedMicroWatts power uplink

5RF Telemetry products

TEL A/B/V, Used by CRDM

TEL N, used by Neuro

Range: Less then 50 cm

RF freq: 175 kHz

6RF Telemetry products -2

TEL C Conexus currently in use by CRDM

Later also by Neuro

Range: Up to 10 meters

RF band: 402 - 405 MHzMICS: Medical Information Communication Service

37

RAMware

8RAMwhere?

PacemakerCan

Connector Block

Leads

SensingCircuit

OutputStage

Battery

BatteryEOL circuit

TelemetrySystem

Antenna

Sensor(s)

SensorInterfaceFeed-throughs

Bonding wires

Mechanical Electronics

Timing/ControlCircuits

TelemetryProtocol SW

SoftwareAlgorithms

Memory

Microprocessor

AD Converter

Firmware Other

Hybrid

9Device Memory

ROM(Read Only Memory)

EEPROM(Electrically Erasable Programmable ROM)

RAM(Random Access Memory)

Firmware

Programmed Parameters RAMware

Working data Diagnostic data RAMware

410RAMware download

(1) RAMware download(2) call RAMware

initializationfunction

&

RAMware Media

11

Algorithms

12Algorithms Rate-Responsiveness

Based on activity (also possible on QT interval) Day and night difference

Managed Ventricular Pacing If not needed, pacing should be avoided Switch between DDD(R) and AAI(R)

Mode Switch What happens during AF when PM is programmed in DDD

mode Switch between DDD(R) and DDIR

513Algorithms (cont)

Additional chamber: LV pacing Rate dependant AV interval Rate-drop response PVC response

11

ICD

2ICD

Implantable Cardioverter Defibrillator

Whats the function Sense Detect Therapy Pace

3

CPU/Memory The processor chip analyses electrical signals from the heart and determines whether any shocks are necessary. The chip runs at less than 100 kHz

ICD ComponentsICD Components

GEM DR Dual Chamber, Rate Responsive ImplantabDefibrillator

BatteryThe special batteries, made of lithium silver vanadium oxide, last six years or more, even though they have less energy than a standard laptop battery

TransformerFor serious heart disturbances requiring a higher shock, a transformer converts low-voltage battery power into a higher voltage.

CasingThe I.C.D. is encased in titanium. Scar tissue grows around it, locking it in place. The device is sealed shut to prevent leakage, so when the battery dies, the entire device must be replaced

ConnectorsA lead with three connections provides sensing capabilities and a pathway for high-energy shocks to one of the hearts lower chambers. A second lead with only one connection provides sensing and pacing to an upper chamber.

BeeperA warning beeper indicates a low battery or another problem that a doctor should check out. There are no warnings to signal a large shock to the patient.

CapacitorsSimilar to the ones used in camera flashes, capacitors can take up to 10 seconds to draw enough energy (30-40 J) from the battery for a large shock. Charge times for smaller shocks are much shorter.

AntennaCommunication between the I.C.D. and the programmer is made through low-frequency radio waves sent from the unit's antenna to a doughnut-shaped receiver held over the patient's chest

LeadsFlexible wires convey sensing information to the I.C.D. and carry electric shocks to the heart. A patient may receive one or two leads depending on the nature of the heart problem. They are covered with silicone insulation.

Marquis DR Implantable Defibrillator

24ICD Specs

Combined with: Pacemaker Cardiac Resynchronization

Longevity 7-10y

37 cc / 68 g

5ICD Sensing

6ICD Detection

Detection of VT/VF based on: Rate Duration (Morphology)

37ICD Therapy

8ICD Settings

9ICD - Shock

Shocking: 35 J charged in 8 s Defibrillation (VF) Cardioversion (VT)

Shock Delivery waveform

410ICD Shock (cont)

11ATP

11

Pacing Leads

2Pacing Lead Lifetime Activity 70 bpm 100,000 beats/day 37,000,000 beats/year 500,000,000 beats/13.5 years

3

Conductor Tip Electrode Insulation Connector Pin

Pacing Lead Components Conductor Connector Pin Insulation Electrode Lead Assembly

24Conductor Purpose

Deliver electrical impulses from IPG to electrode Return sensed intracardiac signals to IPG

Conductor

5Conductor -- Types Types

Unifilar

Multifilar

Cable

6Conductor -- Construction Unipolar Construction

37Conductor -- Unipolar Construction Unipolar lead

1 pacing conductor IPG case (can)

for sensing

8Conductor -- Unipolar Construction Unipolar Lead Characteristics

Larger pacing spikes on EKG Small diameter lead body Less rigid lead body More susceptible to oversensing May produce muscle and nerve stimulation

9Conductor -- Construction Bipolar Construction

Co-axial

Co-radial

Outer insulation

Tip electrode coilIndifferent electrode

coilIntegral insulation

Tip electrode coil

Indifferent electrodecoil

410Conductor -- Construction Bipolar Construction

Parallel Coils

Coil/Cables

11Conductor -- Bipolar Construction Bipolar Lead Characteristics

Larger diameter lead body Tend to be stiffer Less susceptible to oversensing Unipolar programmable Less likely to produce muscle and nerve stimulation

12Conductor -- Material Typical Conductor Materials

MP35N (nickel alloy) MP35N silver cored

513Connector Purpose

Connects lead to IPG, and provides a conduit to: Deliver current from IPG to lead Return sensed cardiac signals to IPG

Connector

14Connector -- IS-1 Standard IS-1 Standard Connectors

Sizes Prior to IS-1 Standard 3.2 mm low-profile connectors 5/6 mm connectors

15Insulation Purpose:

Contain electrical current Prevent corrosion

Insulation

616Insulation -- Properties Properties of Insulation Materials

Tensile strength Elongation Tear strength Abrasion Compression set Crush (cyclic compression) Creep

17Insulation -- Type Insulation Types

Silicone Polyurethane Fluoropolymers (PTFE, ETFE)

18Insulation -- Type Silicone

Advantages Inert Biocompatible Biostable

Disadvantages High friction coefficient (sticky) Handling damage Size (for some types of silicone)

719Insulation -- Type Polyurethane

Advantages Biocompatible High tear strength Low friction coefficient Less fibrotic Small lead diameter

Disadvantages

ESC MIO

20Insulation -- Type Fluoropolymers (PTFE, ETFE)

Advantages Inert Most biocompatible High tensile strength Small size

Disadvantages Stiff when >0.003 More prone to creep Difficult to manufacture without pinholes

21Insulation -- Small SizeNew Insulation Materials Facilitate the Benefits of Smaller Lead Diameters Smaller introducer size Easier insertion/passage through smaller veins More flexible lead bodies Two leads through one introducer Less intrusive

822Electrodes Purpose

Deliver a stimulus to myocardium Detect (sense) intracardiac signals

Optimal Performance Factors Low, Stable Thresholds High Pacing Impedance Low Source Impedance Good Sensing

Tip Electrode Ring Electrode

23Electrodes Characteristics and Design Factors that Impact

Electrical PerformanceFixation mechanism Polarity Surface material Size Surface structure Steroid elution

24Electrodes -- Fixation Mechanism Passive Fixation Mechanism Endocardial

Tined

Canted/curved

925Electrodes Fixation Mechanism Active Fixation Mechanism Endocardial

Fixed screw

Extendible/retractable

26Electrodes -- Fixation/Visualization

Fluoroscopic Image of Leads

CapSure CapSure SP

NovusCapSure Z

Novus CapSureFixExtended Retracted Fixed Screw

space

27Electrodes -- Fixation Mechanism Fixation Mechanism Myocardial/Epicardial

Stab-in

Screw-in

Suture-on

10

28Electrodes -- Surface Material Surface Material

Polished platinum Activated carbon Platinized metal

Surface Material Characteristics Corrosion Resistant Biocompatible Reduced Polarization

29Electrodes -- Size

Reducing Electrode Size Increases Impedance Reduces Current Drain Increases Longevity

Disadvantage: Increase polarization

30Electrodes - Size/Polarization

Current Current Tissue

- + -

++

+++ -+

-

-++++ +--

Polarization Layering Effect

11

31Electrodes -- Surface Structure Porous Electrode Surface

CapSure8.0 mm2

Porous ElectrodeCapSure SP Novus5.8 mm2 Platinized Porous Electrode

CapSure Z Novus1.2 mm2 Platinized

Porous Electrode

15KV x2500 12.0V MDT

32Electrodes -- Surface Structure Benefits of a Porous Electrode Surface

Reduces Polarization

Improves Sensing

Promotes Tissue In-Growth

33Electrodes -- Steroid Elution

Tines forStable Fixation

Silicone Rubber PlugContaining Steroid

Porous, Platinized Tipfor Steroid Elution

Type - Steroid in matrix

12

34Electrodes Steroid Elution

IMPLANT CHRONIC(8 weeks or longer)

ExcitableCardiacTissue

Non-ExcitableFibroticTissue

ExcitableCardiacTissue

35Electrodes -- Steroid ElutionBenefits of Steroid Elution Excellent Electrode-tissue Biocompatibility:

Fewer and less active inflammatory cells Less fibrotic development

Improved Electrode Performance: No significant threshold peaking nor chronic threshold

increases, virtually eliminatingexit block

Improved consistent sensing characteristics

36Electrodes -- Steroid Elution Effect of Steroid on Stimulation Thresholds

Pulse Width = 0.5 msec

03 6

Implant Time (Weeks)

Textured Metal Electrode

Smooth Metal Electrode

1

2

3

4

5

Steroid-Eluting Electrode

0 1 2 4 5 7 8 9 10 11 12

Volts

13

37Leads - LV

CollegePM0_EGM_ECG1_Diseases2a_PacemakerBasics3_Sensing2b_Pacemakers2c_ICDBasics4_Leads