Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
1999-04-23
2001-06-26
Evanisko, George R. (Department: 3737)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
C607S116000, C600S373000
Reexamination Certificate
active
06253111
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to an implantable stimulation lead for use with a cardiac pacemaker, and more specifically, to an implantable stimulation lead having lead body wherein two or more inner conductors are protected from abrasion by a surrounding outer coil.
BACKGROUND OF THE INVENTION
It is known that leads used in cardiac stimulation are often implanted transvenously or transthoracically with the result that the lead body can be physically crushed by either bones (i.e. “first rib-clavicle”) or by tissue (costoclavicular ligament complex, subclavius muscle) and by anchoring sleeves which are tied-down so tightly that the lead body can be crushed or damaged.
The result of these crushing or constrictive stresses, which are made more pronounced by movements of the patient, can become manifested by severe damage to the conductors, such as by abrasion of the insulation of the conductors within the lead body which, in turn, can result in failed conductors and/or failed insulation. This is because the conductors within the lead are usually disposed in close proximity to one another. For example, in a tripolar pacing lead, at least three conductors would be housed within the lead and must be maintained in a spatially disposed relationship with one another.
Conductor mechanical damage including fractures and/or insulation breaks may occur in about 2% to 3% of implanted leads. In patients who are not pacemaker dependent, a failure event is usually not life-threatening, but can require corrective procedures with potential for complications. Mechanical damage can occur as coil deformation, coil fracture, mechanically induced insulation breaches, and insulation wear observed individually or in combination.
SUMMARY OF THE INVENTION
The invention resides in a multi-conductor lead defined by an inner tube having at least two lumens formed therein. About the inner tube is a first coiled conductor, and within the at least two lumens are disposed a respective second and third conductor extending longitudinally therewith.
At the distal end, the first coiled conductor has a portion thereof which is offset wound at a diameter which is smaller than that of the diameter thereof which is coiled about the inner tube so that a connection can be made in-line with the sensor or distal electrode.
An advantage of this arrangement is to provide a multi-conductor lead body having a design which resists mechanical damage, in particular abrasion.
Another advantage is to provide a lead body of the aforementioned type wherein one of the conductors provides a mechanical barrier against the adverse effects of abrasion relative to the remaining conductors in the lead body.
Further, another advantage is to provide a lead body of the aforementioned type which includes a sensor which is capable of connecting to one or more conductors disposed within the tubing, while allowing one conductor to pass through to the distal tip electrode.
In the preferred embodiment, the multi-conductor lead has an inner tube extending concentrically along a central axis thereof, and containing at least two lumens therein. The inner tube has an outer surface defining an outer diameter thereof.
A first coiled conductor is provided and has a predetermined diameter which is slightly greater than the outer diameter of the tubing such that the first conductor is disposed circumferentially about the outer surface of the tubing. An insulation sheath is provided circumferentially about the first conductor.
A second and third conductor are disposed within the at least two lumens in the tubing so as to extend longitudinally therewithin.
At the distal end, the first conductor has an offset portion which is directed for connection to another element of the lead (e.g., a ring electrode or a sensor). Ideally, the first conductor's offset portion is a continual length of the first conductor and ends in a coil portion which has a diameter substantially less than the original diameter of the first conductor length.
In one embodiment of the invention, a sensor is disposed axially in line with the inner tube and has a first and second terminal associated with, and connected to, a selected two of the conductors. The remaining one of the conductors may be selected to pass beneath the sensor to the distal end of the lead body.
Ideally, the first outer conductor is a drawn-filled conductor. The drawn-filled conductor is preferably a silver core MP35N conductor used to reduce the resistance inherent to a large diameter conductor.
REFERENCES:
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patent: 3804098 (1974-04-01), Friedman
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patent: 4559951 (1985-12-01), Dahl et al.
patent: 5275171 (1994-01-01), Barcel
patent: 5324326 (1994-06-01), Lubin
patent: 5330522 (1994-07-01), Kreyenhagen
patent: 5405372 (1995-04-01), Gilljam et al.
patent: 5466253 (1995-11-01), Doan
patent: 5628778 (1997-05-01), Kruse et al.
Evanisko George R.
Pacesetter Inc.
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