Medical device having precision interconnect

Details Medical device having precision interconnect Medical device having precision interconnect

1999-09-08

2001-07-24

Ballato, Josie (Department: 2836)

Electrical transmission or interconnection systems

Switching systems

Condition responsive

C073S708000, C600S486000

Reexamination Certificate

active

06265792

ABSTRACT:

TECHNICAL FIELD
This invention relates in general to electrical devices, and more particularly, to an electrical device such as an intravascular pressure guide wire having a precision interconnect.
BACKGROUND
Medical guide wires having miniature pressure sensors are well known. Such pressure guide wires typically have a pressure sensor located at the guide wire's distal end that is used to measure the pressure within a patient's artery. Electrical conductors which are connected to the pressure sensor are passed through the inside of the guide wire to a set of electrical contacts or sleeves located at the proximal end of the guide wire. The electrical contacts on the guide wire are mated to external monitoring equipment using an interface cable. The external monitoring equipment can provide pressure information to the attending physician that is useful in the diagnosis for example of an arterial occlusion. An example of such a pressure guide wire is described in U.S. Pat. No. 5,715,827, entitled “Ultra Miniature Sensor and Guide Wire Using The Same and Method”.
In
FIG. 1
there is shown a prior art pressure measuring system
100
comprising a guide wire
10
placed within a patient
12
. The guide wire
10
is used with apparatus
20
that comprises rotary connector assembly
220
and a cable
214
that connects the rotary connector assembly
220
to an interface box
24
. Connector
32
which is part of the rotary connector assembly
220
electrically interconnects with interface box connector
34
.
Interface box
24
is connected by cable
26
to a pressure monitoring console
28
, such as a WAVEMAP™ pressure monitoring instrument manufactured by EndoSonics, Inc., Rancho Cordova, Calif. Console
28
can display both proximal and distal pressure measurements as will has controls for calibrating the pressure wire
10
prior to its usage.
Referring now to
FIG. 2
, there is shown a more detailed view of the prior art pressure guide wire
10
coupled to a rotary connector assembly
220
. As shown therein, pressure guide wire
10
can be manufactured utilizing the various constructions as shown and described in U.S. Pat. Nos. 5,163,445, 5,178,159 and 5,240,437. Guide wire
10
comprises a flexible elongate element
202
having a proximal and distal extremities
204
and
206
and which can be formed of suitable material such as stainless steel. The guide wire having an outside diameter for example of 0.018 inch or less and having a suitable wall thickness as for example, 0.001″ to 0.002″ and conventionally called a “hypotube” having a typical length of approximately 150-170 centimeters. A semiconductor pressure sensor
208
is located at the distal extremity of guide wire
10
.
The proximal end of guide wire
10
is slid into a rotary connector
210
of the type described in U.S. Pat. Nos. 5,178,159 and 5,348,481 which is part of the rotary connector assembly
220
. A torquer
230
is typically clipped-on by a physician distal to the rotary connector
210
. Rotation of the torquer
230
causes rotation of guide wire
10
when used in connection with a catherization procedure in a manner well known to those skilled in the art. The proximal extremity
204
of the guide wire
10
is removably disposed within housing
212
of the type described in U.S. Pat. Nos. 5,178,159, 5,348,481 and 5,358,409. Located close to the distal extremity of guide wire
10
is a pressure sensor
208
which is used to measure pressure within a patient's blood vessels.
Electrical contacts located within housing
212
make electrical contact with electrically conductive sleeves (not shown in
FIG. 2
) located on the proximal extremity
204
of guide wire
10
. The electrical contacts located in housing
212
allow for rotation of the guide wire while maintaining electrical contact with the conductive sleeves found in guide wire
10
, these conductive sleeves are electrically coupled to pressure sensor
208
. The electrical contacts in housing
212
are electrically connected to cable
214
that terminates in connector
32
.
The connector
32
is connected to another mating connector
34
located on the interface box
24
. Interface box
24
provides signal buffering and voltage level adjustments between guide wire
10
and pressure monitoring console
28
. The electrically conductive sleeves
302
,
304
and
306
, which are located at the proximal extremity of guide wire
10
, are shown in FIG.
3
.
In
FIG. 4
there is shown an electrical schematic representation of the pressure sensor
208
which comprises two variable resistors
402
and
404
whose resistance values vary with changes in pressure as is known in the art. Pressure sensor
208
can be a semiconductor having a diaphragm as is well known in the art. The two resistors
402
and
404
are connected to the three electrically conductive sleeves or bands
302
,
304
and
306
located on the proximal extremity of guide wire
10
as shown.
FIG. 5
shows an exploded isometric view of the prior art rotary connector assembly
220
including rotartary connector
210
and housing
212
. In operation, the proximal extremity of the flexible elongate member or pressure guide wire
10
is inserted into bore
501
with one hand while holding the rotary connector with the other hand. The nose piece
503
and the collar
504
are then pulled with fingers in a proximal direction against the force of the spring
508
to release the collet
502
and allow it to open. The guide wire
10
can then enter the bore
501
and pass through the inside of collet
502
and through bearing
510
. The guide wire
10
is then pushed further in until conductive sleeve
302
is making electrical contact with contact member
546
, conductive sleeve
304
is making electrical contact with contact member
544
and conductive sleeve
306
is making electrical contact with contact member
542
.
Housing members
514
and
530
retain contacts
542
,
544
and
546
. A retaining ring
506
, which is inserted through an opening in bearing
510
, engages with and retains collet
502
. Connector
32
provides an interconnection with the interface box
24
through a cable as shown in FIG.
1
.
A problem with the above noted design is that sometimes as the guide wire
10
is being rotated, the contact resistance between electrically conductive sleeves
302
,
304
and
306
located on the guide wire
21
and the corresponding electrical contacts located in housing
212
varies. This contact resistance variation is assumed to be caused by microscopic particles that get lodged between the pressure guide wire's conductive bands
302
,
304
and
306
and the corresponding spring contacts
546
,
544
and
542
. This change in contact resistance causes an error in the pressure measurement as determined by pressure monitoring console
28
, since this change in contact resistance affects the measurement of pressure sensor resistors
402
and
404
.
An electrically equivalent circuit showing this change in contact resistance is shown in FIG.
8
. Pressure sensor
208
is shown coupled to sleeve contacts (conductive bands)
302
,
304
and
306
via electrical conductors. Sleeve contact
302
is shown coupled to contact
546
, sleeve contact
304
is shown coupled to contact
544
and sleeve contact
306
is shown coupled to contact
542
. Variable resistors
802
,
804
and
806
represent the variable contact resistance caused by the rotating connector interface. The resistance of resistors
802
,
804
and
806
vary as the pressure guide wire is rotated. As shown, contact resistance
802
is in series with sensor resistor
402
and contact resistance
806
is in series with sensor resistor
404
and thus any change in the contact resistance will affect the measurement of sensor
208
. A need thus exists in the art for a solution that can minimize electrical interconnection problems as the one described above.


REFERENCES:
patent: 4366714 (1983-01-01), Adorni
patent: 5163445 (1992-11-01), Christian et al.
patent: 5178159 (1993-01-01), Christian
patent: 5240437

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