Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
1999-06-02
2001-02-20
Getzow, Scott M. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
Reexamination Certificate
active
06192280
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to implantable medical leads, and more particularly to implantable leads placed by means of a guidewire.
Most commercially available cardiac pacing and defibrillation leads are placed by means of a stylet which is inserted into a central lumen through the lead, and is used to assist in pushing the lead through the vascular system and guiding it to a desired location. More recently, leads placed by means of a guidewire extending entirely through the lead and out its distal end have been introduced. Although such leads are new to commercial distribution, the basic idea of the guidewire placed lead goes back quite some time. One early example of a guidewire placed pacing lead is disclosed in U.S. Pat. No. 3,769,984 issued to Muench. In this lead, a central lumen extending through the lead and out its distal end is provided which may be used for pressure measurement or for use of a guidewire for guiding the lead during its insertion. In this lead, the guidewire lumen extends along the entire length of the lead body. Similar leads are disclosed in U.S. Pat. No. 5,755,766 issued to Chastain et al, and U.S. Pat. No. 5,800,495 issued to Machek et al.
In the context of coronary angioplasty catheters, the use of guidewires to place catheters within the vascular system has evolved to include the use of a “monorail” system, in which the guidewire lumen extends over only a distal portion of the catheter body. This basic approach has been adapted to cardiac pacing leads and cardioversion leads as well, as disclosed in U.S. Pat. No. 5,003,990 issued to Osypka, U.S. Pat. No. 5,755,765 issued to Hyde et al, U.S. Pat. No. 5,381,790 issued to Kenasaka and U.S. Pat. No. 5,304,218 issued to Alferness.
In guidewire implanted leads, there is a danger of blood entering the lumen of the lead body through the opening at the distal end of the lead through which the guidewire exits. It has been suggested in the anonymous publication “Guidewire Placement of Electrical Lead” published as publication no. 35442 in Research Disclosure, October 1993, that a pierceable silicone rubber membrane may be located at the distal tip of the lead, to prevent fluid entry into the lead body during and after placement of the lead.
SUMMARY OF THE INVENTION
The present invention is directed toward a guidewire placed lead employing a seal at its distal end in order to prevent entry of body fluid into the lead. Rather than being located inside a bore within the electrode or simply stretched across the distal tip of the electrode, the seal is particularly designed to allow radial or lateral expansion of the outer circumference of the seal due to passage of the guidewire through the seal. Such a design reduces the force required to pass the guidewire through the seal, while retaining a good sealing characteristics.
In two preferred embodiments of the invention, the seal extends a distance distally from the tip electrode, and includes a hollow, resilient, cup-shaped seal member, configured so that the seal can readily expand radially as the guidewire passes through it. The seal is preferably pre-pierced, to define a path through which the guidewire may pass. A third embodiment of the invention locates the seal within the body of the electrode, but configures the electrode so that it may be radially or laterally expanded, also allowing radial or lateral expansion of the seal during passage of the guidewire. In this case, the electrode may be rendered expandable by means of one or more slits arranged along the electrode body, extending from a point proximal to the guidewire seal. In this embodiment, the seal is also preferably pre-pierced to define a path through which the guidewire may pass.
REFERENCES:
patent: 3769984 (1973-11-01), Muench
patent: 4355646 (1982-10-01), Kallok et al.
patent: 5003990 (1991-04-01), Osypka
patent: 5304218 (1994-04-01), Alferness
patent: 5381790 (1995-01-01), Kanesaka
patent: 5487385 (1996-01-01), Avitall
patent: 5584873 (1996-12-01), Shoberg et al.
patent: 5755765 (1998-05-01), Hyde et al.
patent: 5755766 (1998-05-01), Chastain et al.
patent: 5800495 (1998-09-01), Machek et al.
“Guidewire Placement of Electrical Lead” published as publication No. 35442 in Research Disclosure, Oct. 1993.
Hine Douglas S.
Sommer John L.
Duthler Reed A.
Getzow Scott M.
Medtronic Inc.
Patton Harold R.
Wolde-Michael Girma
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