Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1998-12-15
2001-04-10
Dawson, Glenn K. (Department: 3734)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S095040, C604S528000, C600S139000, C600S146000
Reexamination Certificate
active
06213974
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to medical devices, and more particularly to a steerable catheter having a segmented tip configured for improved steerability, a tip assembly providing improved resistance to steering wire pull-through, and an improved one-piece inlet housing.
2. Description of Related Art
Medical practitioners frequently gain access to internal regions of a patient's body through the use of medical catheters in a variety of medical procedures, in order to reduce or eliminate the need for more invasive procedures. For example, medical catheters may be used to access internal body regions with a fiberoptic scope, light bundles, and/or other surgical instruments or devices, for a variety of diagnosis, treatment and/or material delivery purposes.
Steerable catheters have been developed to provide improved access to internal tissue. These catheters typically include a flexible catheter shaft and steering wires for controlling the flexure of the catheter shaft. A problem common to many previously existing steerable catheters is the retention of the steering wire or wires within the flexible material of the catheter shaft. The steering wire or wires typically comprise a small diameter length of high tensile strength material, whereas the flexible catheter shaft material typically must be relatively soft in order to provide sufficient flexibility. Thus, in many instances, the steering wire will cut through the flexible catheter shaft material, or will otherwise become disattached from the catheter shaft, rendering the catheter inoperable or compromising its utility. This problem is especially troublesome with small diameter catheters having one or more instrument access lumens therethrough, due to the reduced material thickness of the catheter.
Various approaches have been proposed for addressing the problem of steering wire detachment, a number of which are described in applicant's previous U.S. patent application Ser. Nos. 08/777,548 and 09/126,863, the content of which are incorporated herein by reference. Previously developed devices and methods have met with varying degrees of success, but none have proven fully successful for all applications.
An additional problem that has been found problematic in some previously known catheter designs results from the use of standard Touhy-Borst assemblies
10
, as shown in
FIG. 1
, as the catheter inlet. The standard Touhy-Borst assembly
10
typically comprises a two-piece housing, having a first housing component
12
coupled to a second housing component
14
by means of a threaded luer
16
or other coupling. The use of this type of two-piece housing results in increased assembly time and expense, and presents a risk of detachment during use. Additionally, the coupling
16
permits relative rotational movement between the first housing component
12
and the second housing component
14
. This is disadvantageous as it is has been found desirable to maintain the flush port
18
in a fixed position relative to the catheter housing. The standard Touhy-Borst assembly
10
is typically affixed to the catheter housing by means of mounting wings
20
provided on the second housing component
14
. Even if the wings
20
are rigidly attached to second housing component
14
, the rotational movement permitted at coupling
16
allows movement of the first housing component
12
and the flush port
18
thereof. In addition, the standard Touhy-Borst assembly
10
presents several steps or discontinuities
22
a
,
22
b
,
22
c
within its internal passage. These discontinuities present obstructions to instrument passage, and can result in abrasive wear and tear on sensitive instruments. The standard Touhy-Borst assembly
10
is also less than fully satisfactory for use as a catheter inlet housing, as it typically includes only two mounting wings
20
. It has been found desirable to provide additional mounting wings angularly spaced about the circumference of the inlet housing for more accurate positioning. It has also been found desirable to increase the thickness and contact area of the mounting wings to provide more secure attachment to the catheter body housing.
Thus, it has been found that a need exists for an improved steerable catheter device, and for an improved catheter shaft, tip assembly, and inlet housing for catheters. It is to these and other needs that the present invention is primarily directed.
SUMMARY OF THE INVENTION
Briefly described, in preferred form, one aspect of the present invention provides a tip assembly for a steerable catheter, which assembly includes a catheter shaft having first and second steering wire lumens extending lengthwise therethrough. One or more access lumens may optionally be provided through the length of the catheter shaft, for permitting passage of a fiberoptic endoscope and other instruments, infused fluids, aspirated materials, and/or otherwise accessing internal regions. The tip assembly further includes a continuous length of steering wire having a first leg extending through the first steering wire lumen, a second leg extending through the second steering wire lumen, and a looped segment connecting the first and second legs. The looped segment of steering wire may optionally include a coined or otherwise formed expanded outer dimension. A first wear-resistant sleeve is preferably provided within the first steering wire lumen adjacent the looped segment of steering wire, and a second wear-resistant sleeve is preferably provided within the second steering wire lumen adjacent the looped segment of steering wire. The wear-resistant sleeves and coined portion of the steering wire provide improved resistance against steering wire pull-through or detachment from the soft material of the catheter shaft.
In another aspect, the present invention preferably comprises a segmented catheter shaft for a steerable catheter. The segmented catheter shaft preferably includes a first shaft segment having a rear distal end for connection to a catheter body housing, and a front distal end opposite the rear distal end. The segmented catheter shaft preferably further includes a tip segment having a first end fused to the front distal end of the first shaft segment, and a second end opposite the first end. The first shaft segment is preferably relatively stiff to prevent buckling of the catheter shaft, whereas the tip segment is relatively flexible, as compared to the first shaft segment, for improved steerability. The segmented catheter shaft preferably further includes an end segment having a first end fused to the second end of the tip segment, and a second end opposite the first end. In preferred form, the segmented catheter shaft also includes first and second steering wire lumens extending lengthwise through the first shaft segment, the tip segment, and the end segment; and optionally includes one or more access lumens extending throughout the length of the catheter shaft. A continuous length of steering wire is preferably provided, having a first leg extending through the first steering wire lumen and a second leg extending through the second steering wire lumen. A looped segment of the length of steering wire connects the first and second legs, extending across the second end of the end segment of the catheter shaft. A cover segment is preferably also provided, overlying at least a portion of the second end of the end segment, and encapsulating the looped segment of steering wire between the second end of the end segment and the cover segment. The end segment and cover segment are preferably formed of relatively stiff materials of construction, as compared to the tip segment, to resist steering wire pull-through. Wear-resistant sleeves can be provided in the steering wire lumens of the end segment to provide improved resistance to steering wire pull-through.
Another aspect of the present invention provides a method of forming a segmented catheter shaft. The method preferably comprises providing a first shaft segment, a tip segmen
Biggs Robert C.
Nardeo Mahase
Smith Gary A.
Dawson Glenn K.
Gardner & Groff, P.C.
Maynard Jennifer
Visionary Biomedical, Inc.
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