摘要:
Implantable medical leads include a shield that is guarded at a termination by having a first portion and second portion of the shield, where the first portion is between a termination of the shield at the second portion and an inner insulation layer surrounding the filars. The first portion may reduce the coupling of RF energy from the termination of the shield at the second portion to the filars. The first and second portions may be part of a continuous shield, where the first and second portions are separated by an inversion of the shield. The first and second portions may instead be separate pieces. The first portion may be noninverted residing between the termination at the second portion and inner layers, or the first portion may be inverted to create first and second sub-portions. The shield termination at the second portion is between the first and second sub-portions.
摘要:
Implantable medical leads include a shield that is guarded at a termination by having a first portion and second portion of the shield, where the first portion is between a termination of the shield at the second portion and an inner insulation layer surrounding the filars. The first portion may reduce the coupling of RF energy from the termination of the shield at the second portion to the filars. The first and second portions may be part of a continuous shield, where the first and second portions are separated by an inversion of the shield. The first and second portions may instead be separate pieces. The first portion may be noninverted residing between the termination at the second portion and inner layers, or the first portion may be inverted to create first and second sub-portions. The shield termination at the second portion is between the first and second sub-portions.
摘要:
Shields within implantable leads increase the torsional stiffness of the leads. The torsional stiffness may be reduced by cutting the shield axially to break the circumferential mechanical continuity of the shield. The circumferential shielding continuity of the shield may be re-established to preserve the shielding effect in various manners. The shield may overlap onto itself to close the slot created by the cut. A shield patch may be placed across the slot created by the cut. The shield may be located between two insulation layers of the lead. The shield may be cut and then the slot closed prior to application of the outer insulation layer. The outer insulation layer may then be added over the shield. The outer insulation layer may be compliant so that once covered, the circumferential mechanical continuity of the shield remains broken.
摘要:
Shields within implantable leads increase the torsional stiffness of the leads. The torsional stiffness may be reduced by cutting the shield axially to break the circumferential mechanical continuity of the shield. The circumferential shielding continuity of the shield may be re-established to preserve the shielding effect in various manners. The shield may overlap onto itself to close the slot created by the cut. A shield patch may be placed across the slot created by the cut. The shield may be located between two insulation layers of the lead. The shield may be cut and then the slot closed prior to application of the outer insulation layer. The outer insulation layer may then be added over the shield. The outer insulation layer may be compliant so that once covered, the circumferential mechanical continuity of the shield remains broken.
摘要:
A shield located within an implantable medical lead may be terminated in various ways. The shield may be terminated by butt, scarf, lap, or other joints between insulation layers surrounding the lead and an insulation extension. For lap joints, a portion of an outer insulation layer may be removed and a replacement outer insulation layer is positioned in place of the removed outer insulation layer, where the replacement layer extends beyond an inner insulation layer and the shield. The replacement layer may also lap onto a portion of the insulation extension. Barbs may be located between the replacement layer and the inner insulation layer or the insulation extension. The shield wires have ends at the termination point that may be folded over individually or may be capped with a ring located within one of the insulation layers of the jacket.
摘要:
Radiopaque markers represent that a lead is suitable for a particular medical procedure such as a magnetic resonance image scan and are added to the lead or related device. The markers may be added after implantation of the lead in various ways including suturing, gluing, crimping, or clamping a radiopaque tag to the lead or to the device. The markers may be added by placing a radiopaque coil about the lead, and the radiopaque coil may radially contract against the lead to obtain a fixed position. The markers may be added by placing a polymer structure onto the lead where the polymer structure includes a radiopaque marker within it. The polymer structure may include a cylindrical aperture that contracts against the lead to fix the position of the structure. The polymer structure may form a lead anchor that includes suture wings that can be sutured to the lead.
摘要:
A shield located within an implantable medical lead may be terminated in various ways at a metal connector. The shield may be terminated by various joints including butt, scarf, lap, or other joints between insulation layers surrounding the lead and an insulation extension. The shield may terminate with a physical and electrical connection to a single metal connector. The shield may terminate with a physical and electrical connection by passing between an overlapping pair of inner and outer metal connectors. The metal connectors may include features such as teeth or threads that penetrate the insulation layers of the lead. The shield may terminate with a physical and electrical connection by exiting a jacket of a lead adjacent to a metal connector and lapping onto the metal connector.
摘要:
Grounding of a shield that is located in an implantable medical lead may be done in many ways. The shield may be grounded directly to tissue from the lead body at one or more points along the lead body. The pathway for grounding may be a direct current pathway or be capacitively coupled. The pathway for grounding may utilize an exposed or nearly exposed shield at one or more points along the lead body. A jacket forming the lead body may have an outer layer removed at these points to provide the RF pathway to ground. Alternatively, the jacket may be doped with conductive particles at these points. Metal conductors such as ring electrodes and/or lead anchors may be attached to the lead at one or more points to provide the RF pathway to ground.
摘要:
Implantable medical leads are shielded with a braided shield that surrounds an inner layer of insulation. An outer layer of insulation may also surround the shield. The shield is designed with parameters that limit the passage of radio frequency energy, particularly in the magnetic resonance imaging spectrum, to filars that are surrounded by the inner layer of insulation. The braided shield has a plurality of parameters and corresponding ranges. The parameters include one or more of braid angle, wire size, number of wires wound per direction, number of wires in a bundle, wire spacing in an axial dimension, ultimate tensile strength, cross-sectional wire shape, material, and distance from termination to a nearest electrode. Additional parameters of the lead related to the shielding also include one or more of inner insulation thickness, and outer insulation thickness.
摘要:
Grounding of a shield that is located in an implantable medical lead may be done in many ways. The ground pathway may couple to the shield at a point that is outside of a header of an implantable medical device to which the implantable medical lead is attached. The ground pathway may couple to the shield at a point that is within the header of the implantable medical device. The ground pathway may terminate at the metal can of the implantable medical device. As another option, the ground pathway may terminate at a ground plate that is mounted to the header. The ground pathway may be direct current coupled from the shield to the can or ground plate. Alternatively, the ground pathway may include one or more capacitive couplings that provide a pathway for induced radio frequency current.