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Components of Pacing Leads: Design and Performance Factors

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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Components of Pacing Leads: Design and Performance Factors

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  1. Components of Pacing Leads:Design and Performance Factors

  2. Pacing Lead Activity • 70 bpm • 100,000 beats / day • 37,000,000 beats / year

  3. 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

  4. Pacing Lead Components • Conductor • Connector Pin • Insulation • Electrode • Lead Assembly Tip Electrode Conductor Insulation Connector Pin

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

  6. Conductor -- Types • Types • Unifilar • Multifilar • Cable

  7. Conductor -- Construction • Unipolar Construction

  8. Unipolar lead 1 pacing conductor IPG case (“can”)for sensing Conductor -- Unipolar Construction

  9. 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

  10. Conductor -- Construction • Bipolar Construction • Co-axial • Co-radial Tip electrode coil Indifferent electrode coil Outer insulation Tip electrode coil Indifferent electrode coil Integral insulation

  11. Conductor -- Construction • Bipolar Construction • Parallel Coils • Coil / Cables

  12. Bipolar 1 pacing conductor 1 sensing conductor Conductor -- Bipolar Construction

  13. 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

  14. Conductor -- Material • Typical Conductor Materials • MP35N (nickel alloy) • MP35N silver cored

  15. Connector • Purpose • Connects lead to IPG, and provides a conduit to: • Deliver current from IPG to lead • Return sensed cardiac signals to IPG Connector

  16. Connector -- IS-1 Standard • IS-1 Standard Connectors • Sizes Prior to IS-1 Standard • 3.2 mm low-profile connectors • 5/6 mm connectors

  17. Insulation • Purpose: • Contain electrical current • Prevent corrosion Insulation

  18. Insulation -- Properties • Properties of Insulation Materials • Tensile strength • Elongation • Tear strength • Abrasion • Compression set • Crush (cyclic compression) • Creep

  19. Insulation -- Type • Insulation Types • Silicone • Polyurethane • Fluoropolymers (PTFE, ETFE)

  20. Insulation -- Type • Silicone • Advantages • Inert • Biocompatible • Biostable

  21. Insulation -- Type • Silicone • Disadvantages • High friction coefficient (sticky) • Handling damage • Size (for some types of silicone)

  22. Insulation -- Type • Polyurethane • Advantages • Biocompatible • High tear strength • Low friction coefficient • Less fibrotic • Small lead diameter

  23. 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

  24. 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

  25. Electrodes • Purpose • Deliver a stimulus to myocardium • Detect (sense) intracardiac signals Tip Electrode Ring Electrode

  26. Electrodes • Optimal Performance Factors • Low, Stable Thresholds • High Pacing Impedance • Low Source Impedance • Good Sensing

  27. Electrodes • Characteristics and Design Factors that Impact Electrical Performance • Fixation mechanism • Polarity • Surface material • Size • Surface structure • Steroid elution

  28. Electrodes -- Fixation Mechanism • Passive Fixation Mechanism – Endocardial • Tined • Finned • Canted/curved

  29. Electrodes -- Fixation Mechanism • Passive Fixation Applications – Endocardial • Trabeculated ventricle • Atrial appendage present • Traditional pacing sites

  30. Electrodes – Fixation Mechanism • Active Fixation Mechanism – Endocardial • Fixed screw • Extendible/retractable

  31. Electrodes -- Fixation Mechanism • Active Fixation Applications -- Endocardial • Smooth ventricular walls • Atrial appendage is missing/malformed • Alternate pacing site

  32. Electrodes -- Fixation/Visualization Fluoroscopic Visual Quality of Passive Fixation Leads CapSure® CapSure SP® Novus CapSure Z® Novus

  33. Electrodes -- Fixation/Visualization Fluoroscopic Visual Quality of Active Fixation Leads space Extended Retracted Fixed Screw SureFix CapSureFix®

  34. Electrodes -- Fixation Mechanism • Fixation Mechanism – Myocardial / Epicardial • Stab-in • Screw-in • Suture-on

  35. Electrodes -- Polarity • Characteristics and Design Factors that Impact Electrical Performance • Fixation mechanism • Polarity • Surface material • Size • Surface structure • Steroid elution

  36. Electrodes -- Surface Material • Characteristics and Design Factors that ImpactElectrical Performance • Fixation mechanism • Polarity • Surface material • Size • Surface structure • Steroid elution

  37. Electrodes -- Surface Material • Surface Material • Polished platinum • Activated carbon • Platinized metal

  38. Electrodes -- Surface Material • Surface Material Characteristics • Corrosion Resistant • Biocompatible • Reduced Polarization

  39. Electrodes -- Size • Characteristics and Design Factors that Impact Electrical Performance • Fixation mechanism • Polarity • Surface material • Size • Surface structure • Steroid elution

  40. Electrodes -- Size • Reducing Electrode Size • Increases Impedance • Reduces Current Drain • Increases Longevity

  41. 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)

  42. 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

  43. 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

  44. Electrodes -- Size/Polarization • Reducing Electrode Size • Increases polarization

  45. + - - + + - + + + Current Tissue - Current + + - + + + + - - Electrodes -- Size/Polarization • Polarization Layering Effect

  46. Electrodes -- Surface Structure • Characteristics and Design Factors that ImpactElectrical Performance • Fixation mechanism • Polarity • Surface material • Size • Surface structure • Steroid elution

  47. 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

  48. Electrodes -- Surface Structure • Benefits of a Porous Electrode Surface • Reduces Polarization • Improves Sensing • Promotes Tissue In-Growth

  49. Electrodes -- Size and Surface Structure Increased Porosity Smaller Size Increases electrode tissue impedance Reduces polarization Decreased current drain Longevity Increases!

  50. Electrodes -- Steroid Elution • Characteristics and Design Factors that ImpactElectrical Performance • Fixation mechanism • Polarity • Surface material • Size • Surface structure • Steroid elution

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