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Components of Pacing Leads: Design and Performance Factors. Pacing Lead Activity. 70 bpm 100,000 beats / day 37,000,000 beats / year. Pacing Lead Components. Objectives Be awareness of how leads play a critical role in the reliability of a pacing system -- A lead is not “just a wire”.

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pacing lead activity
Pacing Lead Activity
  • 70 bpm
  • 100,000 beats / day
  • 37,000,000 beats / year
pacing lead components
Pacing Lead Components

Objectives

  • Be awareness of how leads play a critical role inthe reliability of a pacing system -- A lead is not“just a wire”.
  • Demonstrate an understanding of design and technology that influence potential performance and reliability of a lead -- All leads are not created equal.
  • Demonstrate an understanding of lead assembly process
pacing lead components4
Pacing Lead Components
  • Conductor
  • Connector Pin
  • Insulation
  • Electrode
  • Lead Assembly

Tip Electrode

Conductor

Insulation

Connector Pin

conductor
Conductor
  • Purpose
    • Deliver electrical impulses from IPG to electrode
    • Return sensed intracardiac signals to IPG

Conductor

conductor types
Conductor -- Types
  • Types
    • Unifilar
    • Multifilar
    • Cable
conductor construction
Conductor -- Construction
  • Unipolar Construction
conductor unipolar construction
Unipolar lead

1 pacing conductor

IPG case (“can”)for sensing

Conductor -- Unipolar Construction
conductor unipolar construction9
Conductor -- 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
conductor construction10
Conductor -- Construction
  • Bipolar Construction
    • Co-axial
    • Co-radial

Tip electrode coil

Indifferent electrode

coil

Outer insulation

Tip electrode coil

Indifferent electrode coil

Integral insulation

conductor construction11
Conductor -- Construction
  • Bipolar Construction
    • Parallel Coils
    • Coil / Cables
conductor bipolar construction
Bipolar

1 pacing conductor

1 sensing conductor

Conductor -- Bipolar Construction
conductor bipolar construction13
Conductor -- 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
conductor material
Conductor -- Material
  • Typical Conductor Materials
    • MP35N (nickel alloy)
    • MP35N silver cored
connector
Connector
  • Purpose
    • Connects lead to IPG, and provides a conduit to:
      • Deliver current from IPG to lead
      • Return sensed cardiac signals to IPG

Connector

connector is 1 standard
Connector -- IS-1 Standard
  • IS-1 Standard Connectors
  • Sizes Prior to IS-1 Standard
    • 3.2 mm low-profile connectors
    • 5/6 mm connectors
insulation
Insulation
  • Purpose:
    • Contain electrical current
    • Prevent corrosion

Insulation

insulation properties
Insulation -- Properties
  • Properties of Insulation Materials
    • Tensile strength
    • Elongation
    • Tear strength
    • Abrasion
    • Compression set
    • Crush (cyclic compression)
    • Creep
insulation type
Insulation -- Type
  • Insulation Types
    • Silicone
    • Polyurethane
    • Fluoropolymers (PTFE, ETFE)
insulation type20
Insulation -- Type
  • Silicone
    • Advantages
      • Inert
      • Biocompatible
      • Biostable
insulation type21
Insulation -- Type
  • Silicone
    • Disadvantages
      • High friction coefficient (sticky)
      • Handling damage
      • Size (for some types of silicone)
insulation type22
Insulation -- Type
  • Polyurethane
    • Advantages
      • Biocompatible
      • High tear strength
      • Low friction coefficient
      • Less fibrotic
      • Small lead diameter
insulation type23
Insulation -- Type
  • Polyurethane Disadvantages
    • Environmental Stress Cracking (ESC)

Crazing or cracking of the polyurethane due to exposure to the in-vivo environment and internal material stresses

    • Metal Ion Oxidation (MIO)

Oxidative degradation of the polyurethane insulation

insulation small size
Insulation -- Small Size

New 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
electrodes
Electrodes
  • Purpose
    • Deliver a stimulus to myocardium
    • Detect (sense) intracardiac signals

Tip Electrode

Ring Electrode

electrodes26
Electrodes
  • Optimal Performance Factors
    • Low, Stable Thresholds
    • High Pacing Impedance
    • Low Source Impedance
    • Good Sensing
electrodes27
Electrodes
  • Characteristics and Design Factors that Impact Electrical Performance
    • Fixation mechanism
    • Polarity
    • Surface material
    • Size
    • Surface structure
    • Steroid elution
electrodes fixation mechanism
Electrodes -- Fixation Mechanism
  • Passive Fixation Mechanism – Endocardial
    • Tined
    • Finned
    • Canted/curved
electrodes fixation mechanism29
Electrodes -- Fixation Mechanism
  • Passive Fixation Applications – Endocardial
    • Trabeculated ventricle
    • Atrial appendage present
    • Traditional pacing sites
electrodes fixation mechanism30
Electrodes – Fixation Mechanism
  • Active Fixation Mechanism – Endocardial
    • Fixed screw
    • Extendible/retractable
electrodes fixation mechanism31
Electrodes -- Fixation Mechanism
  • Active Fixation Applications -- Endocardial
    • Smooth ventricular walls
    • Atrial appendage is missing/malformed
    • Alternate pacing site
electrodes fixation visualization
Electrodes -- Fixation/Visualization

Fluoroscopic Visual Quality of Passive Fixation Leads

CapSure®

CapSure SP® Novus

CapSure Z® Novus

electrodes fixation visualization33
Electrodes -- Fixation/Visualization

Fluoroscopic Visual Quality of Active Fixation Leads

space

Extended Retracted

Fixed Screw

SureFix

CapSureFix®

electrodes fixation mechanism34
Electrodes -- Fixation Mechanism
  • Fixation Mechanism –

Myocardial / Epicardial

    • Stab-in
    • Screw-in
    • Suture-on
electrodes polarity
Electrodes -- Polarity
  • Characteristics and Design Factors that Impact Electrical Performance
    • Fixation mechanism
    • Polarity
    • Surface material
    • Size
    • Surface structure
    • Steroid elution
electrodes surface material
Electrodes -- Surface Material
  • Characteristics and Design Factors that ImpactElectrical Performance
    • Fixation mechanism
    • Polarity
    • Surface material
    • Size
    • Surface structure
    • Steroid elution
electrodes surface material37
Electrodes -- Surface Material
  • Surface Material
    • Polished platinum
    • Activated carbon
    • Platinized metal
electrodes surface material38
Electrodes -- Surface Material
  • Surface Material Characteristics
    • Corrosion Resistant
    • Biocompatible
    • Reduced Polarization
electrodes size
Electrodes -- Size
  • Characteristics and Design Factors that Impact

Electrical Performance

    • Fixation mechanism
    • Polarity
    • Surface material
    • Size
    • Surface structure
    • Steroid elution
electrodes size40
Electrodes -- Size
  • Reducing Electrode Size
    • Increases Impedance
    • Reduces Current Drain
    • Increases Longevity
electrodes size impedance
Electrodes -- Size/Impedance

1500

Size = Impedance

1000

Pacing Impedance (Ohms)

500

0

0

1

2

3

4

5.5

6

Geometric Tip Electrode Surface Area (mm2)

electrodes size current drain
Electrodes -- Size/Current Drain
  • Reducing electrode size
    • Increased impedance
    • Lower outputs, reduces current drain
    • Increases longevity

Increasedimpedance at thetip electrode

Smaller current

drain (less current doessame amount of work)

Largercurrentdrain

electrodes size longevity
Electrodes -- Size/Longevity
  • Impact of Pacing Impedance on Longevity

Medtronic.Kappa™ DR Model KDR701

Total Pulse Width 0.4 ms in both chambers Lead A = 3.5 V A = 2.5 V A = 2.5 V Impedance V = 3.5 V V = 2.5 V V = 1.5 V

500  6.3 Yr 7.7 Yr 8.1 Yr

600  6.6 Yr 8.0 Yr 8.3 Yr

1000  7.7 Yr 8.6 Yr 8.8 Yr

1200  8.0 Yr 8.8 Yr 9.0 Yr

100% pacing at 60 ppm

electrodes size polarization
Electrodes -- Size/Polarization
  • Reducing Electrode Size
    • Increases polarization
electrodes size polarization45

+

-

-

+

+

-

+

+

+

Current

Tissue

-

Current

+

+

-

+

+

+

+

-

-

Electrodes -- Size/Polarization
  • Polarization Layering Effect
electrodes surface structure
Electrodes -- Surface Structure
  • Characteristics and Design Factors that ImpactElectrical Performance
    • Fixation mechanism
    • Polarity
    • Surface material
    • Size
    • Surface structure
    • Steroid elution
electrodes surface structure47
Electrodes -- Surface Structure
  • Porous Electrode Surface

15KV x2500 12.0V Medt

CapSure®

8.0 mm2Porous Electrode

CapSure® SP Novus

5.8 mm2 Platinized Porous Electrode

CapSure® Z Novus

1.2 mm2 Platinized Porous Electrode

electrodes surface structure48
Electrodes -- Surface Structure
  • Benefits of a Porous Electrode Surface
    • Reduces Polarization
    • Improves Sensing
    • Promotes Tissue In-Growth
electrodes size and surface structure
Electrodes -- Size and Surface Structure

Increased Porosity

Smaller Size

Increases electrode tissue impedance

Reduces polarization

Decreased current drain

Longevity Increases!

electrodes steroid elution
Electrodes -- Steroid Elution
  • Characteristics and Design Factors that ImpactElectrical Performance
    • Fixation mechanism
    • Polarity
    • Surface material
    • Size
    • Surface structure
    • Steroid elution
electrodes steroid elution51
Electrodes -- Steroid Elution
  • Type - Steroid in matrix

Porous, Platinized Tipfor Steroid Elution

Silicone Rubber PlugContaining Steroid

Tines forStable Fixation

electrodes steroid elution52
Electrodes – Steroid Elution

Excitable

Cardiac

Tissue

Excitable

Cardiac

Tissue

Non-Excitable

Fibrotic

Tissue

IMPLANT

CHRONIC

(8 weeks or longer)

electrodes steroid elution53
Electrodes -- Steroid Elution

Benefits 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
    • Improved consistent sensing characteristics
electrodes steroid elution54
Electrodes -- Steroid Elution

5

  • Effect of Steroid on Stimulation Thresholds

4

Smooth Metal Electrode

3

Volts

Textured Metal Electrode

2

1

Steroid-Eluting Electrode

0

0

1

2

3

4

5

6

7

8

9

10

11

12

Implant Time (Weeks)

Pulse Width = 0.5 msec

electrodes steroid elution55
Electrodes -- Steroid Elution
  • Steroid Enhances Sensing
    • Steroid elution stabilizes electrode sensing performance
    • Improved r-wave sensing: + 5-10 mV
    • Improved p-wave sensing: + 0.5-1.0 mV
    • Stable, acute atrial sensing
    • Clinical benefits
      • Less postoperative atrial sensing loss
      • Can use higher atrial sensitivities
electrode summary
Electrode -- Summary

Design Factors that Impact Lead Electrical Performance

  • Fixation Mechanism
  • Polarity
  • Surface Material
  • Size
  • Surface Structure
  • Steroid Elution
lead summary

Tip Electrode

Conductor

Insulation

Connector Pin

Lead Summary
  • Lead environment is hostile
  • Leads are complex
  • Lead performance