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Description  |
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This invention relates to a device facilitating the exchange of dilatation
catheters during angioplasty procedure by the use of an exchange wire
which is adapted to extend through the dilatation catheters.
In the past, there has been an exchange wire utilized in connection with
angioplasty procedures in which one dilatation catheter could be
substituted for another. In this porcedure, it is important that when the
dilatation catheter is being removed that the distal extremity of the
exchange guide wire not be disturbed. in other words, its precise position
in the blood vessel should be retained. The procedure which has been
utilized in the past generally requires two operators (usually both
doctors) to achieve the removal of a dilatation catheter over the exchange
wire and for the insertion of another dilatation catheter over the
exchange wire. In addition to requiring two operators, it has been
necessary to more or less continuously view the exchange procedure under
x-rays to ascertain that the exchange guide wire position in the blood
vessel is not being disturbed. In order to overcome these manpower
problems and the excessive use of x-rays, it is desirable to provide a
device which can accomplish this procedure and at the same time,
accomplish the same with greater precision without the use of x-rays.
In general, it is an object of the present invention to provide a device
for facilitating the exchange of dilatation catheters during an
angioplasty procedure which may be operated by a single individual.
Another object of the invention is to provide a device of the above
character in which the exchange can be accomplished with great precision.
Another object of the invention is to provide a device of the above
character in which the exchange can be accomplished without the use of
x-rays for viewing the exchange procedure.
Another object of the invention is to provide a device of the above
character which can be readily manufactured.
Another object of the invention is to provide a device of the above
character which is intended for a single use and is disposed of after use.
Additional objects and features of the invention will appear from the
following description in which the preferred embodiment is set forth in
conjunction with the accompanying drawings.
FIG. 1A is a top plan view of a device for facilitating the exchange of
dilatation catheters and in addition shows a portion of the angioplasty
assembly utilized mounted on the device.
FIG. 1B is an enlarged portion of a distal extremity of the angioplasty
assembly shown in FIG. 1A.
FIG. 2 is a side elevational view looking along the line 2--2 of FIG. 1A
showing the device of FIG. 1A with the angioplasty assembly removed.
FIG. 3 is an end elevational view looking along the line 3--3 of the device
shown in FIG. 1A with the angioplasty assembly removed.
FIG. 4 is a cross sectional view taken along the line 4--4 of FIG. 2.
FIG. 5 is a cross sectional view taken along the line 5--5 of FIG. 4.
FIG. 6 is a cross sectional view taken along the line 6--6 of FIG. 4.
FIG. 7 is a cross sectional view taken along the line 7--7 of FIG. 4.
In general, the device for facilitating the exchange of dilatation
catheters during an angioplasty procedure is accomplished by the use of an
exchange wire in which the exchange wire extends through the dilatation
catheter and has its distal extremity positioned in a vessel. First means
is provided for frictionally engaging the dilatation catheter for
advancing or retracting the dilatation catheter. Second means is provided
for frictionally engaging the exchange wire for advancing or retracting
the exchange wire. Means is provided for causing operation of the first
and second means in substantial synchronism whereby when the dilatation
catheter is moved in one direction the exchange wire is moved in an
opposite direction so that a dilatation catheter can be removed from a
vessel while retaining the distal extremity of the exchange wire in a
predetermined position and for introducing another dilatation catheter
over the exchange wire while retaining the exchange wire in a
predetermined position.
More particularly, the device 11 for facilitating the exchange of
dilatation catheter during an angioplasty procedure is shown in FIGS. 1-4.
It consists of a housing 12 which carries an angioplasty assembly 13 with
which the device is to be used as hereinafter described. The angioplasty
assembly 13 is of a conventional type such as that supplied by Advanced
Cardiovascular Systems, Inc. of Mountain View, Calif. and consists of a
guiding catheter 16. The guiding catheter 16 includes a hemostatic rotater
17, and a distal side arm adapter 18. The side arm adapter 18 includes a
main arm 19 on which is mounted a rotatable knob 21 and a side arm 22. The
angioplasty assembly 13 also includes a dilatation catheter 26. The
dilatation catheter is provided with first and second lumens (not shown)
which are formed by tubular members 27 and 28 with the tubular member 27
extending through the tubular member 28. The tubular member 28 is provided
with an integrally formed balloon 29. A pair of radiopaque markers 31 are
carried by the inner tubular member 27 and are positioned to generally
define the outer extremities of the balloon 29. An additional radiopaque
marker 32 is provided on the distal extremity of the tubular member 28 for
identifying the distal extremity of the dilatation catheter 26. The
proximal extremity of the dilatation catheter 26 carries an intermediate
side arm adapter 36.
The side arm adapter 36 includes a main arm 37 and side arms 38 and 39. The
side arm 39 carries a rotatable knob 41.
The angioplasty assembly 13 also consists of a proximal side arm adapter 42
mounted upon a hemostatic rotater 43. The hemostatic rotater 43 is mounted
on the main arm 37 of the intermediate side arm adapter 36. The side arm
adapter 42 includes a main arm 44 and a side arm 46. The main arm 44 is
provided with a rotatable knob 47. An exchange wire 49 extends through the
main arm 42 of the proximal side arm adapter 42 through the side arm
adapter 36 of the dilatation catheter 26 and through the end of the
dilatation catheter 26 as shown in FIG. 1B.
The housing 12 of the device 11 is elongate as is shown and is provided
with a large rounded protrusion 12a adjacent at one end of the same. The
housing 12 consists of two parts or half shells 51 and 52 formed of a
suitable material such as plastic. The half shells 51 and 52 are provided
with a plurality of reinforcing ribs 53. Means is provided on the housing
12 for frictional engaging the exchange wire 49 of the angioplasty
assembly 13 and for engaging the dilatation catheter 26 of the angioplasty
assembly. The frictionally engaging means consists of a first means 56 and
a second means 57. The first means 56 consists of a drive roller 58 and a
idler roller 59 whereas the second means consists of a drive roller 61 and
an idler roller 62.
Synchronous drive means is provided for causing rotation of the drive
rollers 58 and 61 and includes a hand operated knob 66 which is carried by
the housing 12. The knob 66 is mounted on the protrusion 12a of the
housing 12. The knob 66 is generally cylindrical in form and is rotatably
mounted over a cylindrical protrusion 67 formed integral with the top half
shell 52. The knob 66 is provided with a plurality of circumferentially
spaced vertically extending ribs 68 to facilitate grasping the outer
circumference of the knob by the hand of the operator. The knob 66 is
provided with a centrally disposed hub 69 which depends downwardly. The
hub 69 is provided with a cylindrical recess 71 opening downwardly and
loosely fitting over an upwardly extending boss 72 formed integral with
the bottom shell 51. The bottom extremity of the hub 69 is provided with
downwardly extending keys 73 which are adapted to seat in or mate with
recesses 74 provided in a main drive gear 76 which is rotatably mounted
upon the upwardly extending boss 72. The knob 66 is retained on the
housing by a pin 75 which extends through the boss and extends upwardly
into the hub 69.
The main drive gear 76 engages idler gears 77 and 78 rotatably mounted upon
upwardly entending bosses 79 and 81 formed integral with the lower top
half shell 52. The idler 78 engages and drives a gear 82. The gear 82
drives gear 83, gear 83 drives gear 84 and gear 86 drives gear 88. The
gears 82, 83, 84 and 86 are all of the same size and are rotatably mounted
on upstanding bosses 87 provided in the top or upper half shell 52. The
gear 86 drives a gear 88 which is mounted on a boss 89. The gear 88 drives
a gear 91. The gear 91 is mounted on a boss 92 also formed integral with
the bottom or lower half shell 51.
The gear 91 drives the roller 61 which extends upwardly through an opening
97 provided in the top or upper shell 52. The roller 61 is generally
cylindrical as shown and is provided with a cylindrically downwardly
opening recess 98 so that the roller fits over the boss 92. The roller 61
is provided with downwardly extending keys 99 which fit into or mate with
recesses 101 provided in the gear 91. The roller 61 is retained on the
housing 12 by a pin 102 which extends through the boss 92 and extends
upwardly into the roller 61.
A sleeve 104 is provided on a roller 61 and is formed of a suitable
elastomeric material such as Neoprene. It is desirable that the sleeve be
formed of a material which will not readily oxidize. The material should
be characterized in having high friction at the surface while still being
compliant so as not to damage the dilatation catheters which are engaged
thereby. It should have a hardness ranging from 20 to 60 Shore A
durometer.
The idler roller 62 cooperating with the roller 61 is provided with a
similar sleeve 106. The idler roller 62 is carried by a release lever 107
which is provided with reinforcing ribs 108. The lever is pivotally
mounted in the housing 12 upon a pin 109. The lever 107 is provided with
an upwardly extending cylindrical boss 111 which extends into a
cylindrical recess 112 provided in the roller 62 (see FIG. 7). A pin 114
extends upwardly through the release lever 107 and into the roller 62 and
secures the idler roller 62 to the release lever 107.
Means is provided for operating the release lever 107 and consists of a pin
116 which is mounted on the outer extremity of the release lever 107 and
extends upwardly through an arcuate slot 117 provided in the upper shell
52. A knob 118 is mounted on the pin 116 and is adapted to be engaged by
the hand. Means is provided for yieldably urging the idler roller 62 into
frictional engagement with the drive roller 61 and consists of a coil
spring 121 which has one end seated within a well provided in the release
lever 107 and having the other hand seated on a protrusion 122 carried by
the lower shell 51. When the knob is engaged by a hand, the release lever
can be operated to move the idler roller 62 out of frictional engagement
with the idler roller 61 against the force of the spring 121.
To accommodate this movement of the idler roller 62, an elongate slot 123
is provided in the upper shell 52.
The gear 82 in addition to driving the gears hereinbefore described to
drive the drive roller 61 also causes rotation of a gear 126 which is
hereinafter described causes rotation of the driver roller 58. The gear
126 is connected to the drive roller 58 in the same manner that the gear
91 is connected to the roller 61 and therefore this connection will not be
described in detail. The roller 58 is provided with a sleeve 127 and
similarly, the idler roller 59 is provided with a sleeve 128. Sleeves 127
and 128 can have the same characteristics as the sleeves 104 and 106. The
idler roller 59 extends through an arcuate slot 129 provided in the upper
shell 52 and is mounted upon a release lever 131 in a manner similar to
that to which the idler roller 62 is mounted upon the release lever 107.
The release lever 131 has one end pivotally mounted in the housing 12 by a
pin 132. The roller 59 is mounted intermediate of the ends of the release
lever 131. The other end of the release lever 131 is provided with a pin
133 which extends upwardly through an arcuate slot 134 provided in the
upper shell 52. A knob 136 is mounted on the pin 133 and is provided to
permit a finger of the hand to move the release lever so as to move the
idler roller 59 out of engagement with the drive roller 58 against the
yieldable force of a spring 138 which has one end mounted in a well
provided in the release lever 131 and having the other end seated on a
protrusion 139 carried by the lower shell 51. The springs 121 and 139 are
sized so as to provide sufficient frictional engagement between the
rollers but insufficient to crush the dilatation catheter 26. It has been
found that a force much in excess of two pounds tends to crush the
dilatation catheter 26 and that a force of approximately one and one-half
pounds is adequate.
It will be noted that the dilatation catheter 28 which is engaged by the
roller 61 and 62 has a diameter which is greater than the diameter of the
exchange wire 49 which is engaged by the rollers 58 and 59. Since it is an
important feature of this invention that the dilatation catheter 28 and
the exchange wire 49 be moved equal distances, there is a need to
compensate for this difference in diameters. As can be appreciated, this
difference in diameters can be compensated for in either of two ways,
either by rotating the two sets of rollers at different speeds to
compensate for the difference in diameters or to change the diameters of
the two sets of rollers. In the present embodiment, the two sets of
rollers are driven at the same speed and the diameters of the two sets of
rollers are different. The diameters of the drive roller 58 and the idler
roller 59 engaging the exchange wire 49 are made slightly smaller than the
diameters of the rollers 61 and 62 engaging the dilatation catheter 26. By
way of example, it has been found that when the diameters of the rollers
58 and 59 are decreased by approximately 0.030ths of an inch with respect
to the diameters of the rollers 61 and 62 that this difference in
diameters will compensate for the differences in the diameters of the
dilatation catheter 26 and the exchange wire 49. This change in thickness
can be readily accommodated by providing elastomeric sleeves of the
desired diameters on the rollers.
The gearing which is hereinbefore described which interconnects the knob 66
with the drive gears 91 and 126 for the drive rollers 61 and 58
respectively is such that the gears 91 and 126 will be driven at the same
speed. The gearing has also been selected that with approximately ten full
revolutions of the knob 66 a complete dilatation catheter exchange can be
accomplished as hereinafter described. Thus the diameter of the gears 76
can be two inches with the gears 77 and 78 having a diameter of 3/4 of an
inch and the gears 82, 83, 84 and 86 having a diameter of one inch, the
gear 88 a diameter of 21/4 inches and the gears 91 and 126 having a
diameter of two inches. The teeth on the gears can have any suitable pitch
12, for example, 32 pitch. They also can have any desired number of teeth
as, for example, the main drive gear 76 can have 96 teeth with the other
gears having proportional numbers of teeth.
The gears can be formed of any suitable material such as plastic. It is
desirable that they be formed of a self lubricating material such as
Nylon. In addition to the gears, the rollers 58, 59, 61 and 62, as well as
the drive knob 76 should be formed of a similar self lubricating material.
Retaining means is provided on the housing 12 for supporting the
angioplasty assembly 13 and for securing it thereto. As shown particularly
in FIG. 1A, this means consists of means for carrying the distal side arm
adapter, the intermediate side arm adapter 36 and the proximal side arm
adapter 42. Means for securing the distal side arm adapter 18 to the
housing 12 consists of a rectangular block 146 formed intergal with the
top shell 52 upon which the side arm adapter 18 rests and two pairs of
spaced apart upstanding clip members 147 and 148 disposed adjacent
opposite ends of the block 146 and adapted to frictionally engage
cylindrical portions of the side arm adapter 18. The clips 147 and 148 are
formed integral with the top shell 52. The clips 147 and 148 serve to
prevent lateral movement of the distal side arm adapter 18. The retaining
means for the side arm adapter 18 also includes means for inhibiting
movement longitudinally of the block 146 and consists of another small
block 149 which is provided with a pair of upstanding spaced apart ears
151. The spaced apart ears 151 are spaced apart a sufficient distance so
as to receive the rotatable knob 21 and to permit rotation of it while the
distal side arm adapter 18 is retained within the clips 147 and 148. By
positioning the rotatable knob 21 between the spaced apart members 151,
the distal side arm adapter 18 is restricted from substantial movement
longitudinally of the block 146.
Similar retaining means is provided for retaining the proximal side arm
adapter 42 on the housing 12 and consists of a block 153 with two pairs of
spaced apart clips 154 and 156 mounted adjacent opposite ends of the block
153. It also includes a block 157 which is provided with spaced apart
upstanding ears 158 which are adapted to receive the rotatable knob 47 of
the proximal side arm adapter 52.
The retaining means for retaining intermediate side arm adapter 36 on the
housing 12 consists of a smaller block 159 and a pair of upstanding pins
161 disposed on the distal side of the block 159. The intermediate side
arm adapter 36 is adapted to rest upon the block 156 and the distal
extremity of the side arm adapter 36 is adapted to rest between the pins
161. The blocks and the clips as well as the members hereinbefore
described all are formed integral with the top shell 52 and are formed of
the same material as the top shell 52.
Means is provided for guiding the exchange wire 49 in through and between
the rollers 58 and 59 and consists of a pair of upstanding hook members
162 and 163 with one hook member 162 being formed integral with the top
shell 52 and with the other hook member 163 extending through a slot 164
provided in the top shell 52 and being secured to the release lever 131.
It can be seen from FIG. 1A, that the hook members 162 and 163 are offset
with respect to each other so that the hook member 163 can overlap the
hook member 162. To insert the exchange wire 49 between the hook members
162 and 163, the hook member 163 is moved away from the hook member 162
for use of the knob 136 to shift the position of the release lever to move
the hook member 163 as well as the idler roller 59 into position so that
the exchange wire can be positioned between the hook members 162 and 163
and between the rollers 58 and 59. As soon as the knob 136 is released,
the spring 138 will urge the release lever 131 into a direction so that
the idler roller 59 engages the exchange wire 49 and so that the hook
member 163 moves into cooperating engagement with the hook member 162 to
retain the exchange wire therein so it cannot be moved in a vertical or
lateral direction with respect to the housing 12.
Similar means is provided for guiding the tubular member 28 of the
dilatation catheter 26 between the rollers 61 and 62 and consists of a
pair of hook members 166 and 167 and a second pair of hook members 168 and
169. The hook members 166 and 168 are formed integral with the top shell
52 and are upstanding therefrom. The hook members 167 and 169 extend
through slots 171 and 172 formed in a top shell 52 and are mounted upon
the release lever 107. The hook members 168 and 169 are offset with
respect to each other in the same manner as the hook members 162 and 163.
Upon operation of the knob 118 to move the idler roller 62 away from the
drive roller 61, the hook members 167 and 169 will be moved with the idler
roller so as to permit the tubular member 28 to be inserted between the
rollers 61 and 62 and to be seated between the pairs of hook members 166,
167, 168 and 169 disposed on opposite sides of the rollers 61 and 62. When
the knob 118 is released, the rollers 61 and 62 will frictionally engage
the tubular member 28 and the hook members will retain the tubular member
28 within the hook members to prevent lateral and vertical movement of the
tubular member 28.
In assemblying the device 11, the gears and release levers can be mounted
in the top shell 52. After this has been accomplished, the bottom shell 51
is secured to the top shell 52 in a suitable manner. For example, male
pins 176 can be provided on the bottom shell 51 and female bosses 177 can
be provided on the top shell. The bosses 177 can be provided with holes
178 which are adapted to receive the pins 176 and to provide an
interference fit so that when the two halves are pressed together, they
cannot hereafter be separated. This type of construction is utilized
because the entire device is a throwaway device after use.
Operation and use of the device in connection with an angioplasty procedure
may now be briefly described as follows. Let it be assumed that an
angioplasty procedure is underway and that a guiding catheter 16 has been
inserted into the patient and that it is disposed in a heart vessel. Also
let it be assumed that a dilatation catheter 26 has been inserted into the
guiding catheter with the use of a conventional guide wire and that it has
been positioned in the desired location to perform a balloon dilatation at
the stenosis in the heart vessel. Let it be assumed that a first balloon
dilatation has been accomplished but that the attending physician desires
to utilize a dilatation catheter having a larger balloon to create the
larger opening in the stenosis. To accomplish this, the guide wire is
removed leaving the dilatation catheter 26 in place and an exchange wire
49 is inserted through the dilatation catheter 26 until its distal
extremity is in the same position as the guide wire previously used for
the dilatation catheter. As soon as this has been accomplished, the device
11 of the present invention can be utilized by positioning the housing 12
along the side of the leg of the patient in such a manner that the portion
12a of the housing extends upwardly from the leg of the patient so that
the knob 66 can be grasped by the attending physician. The physician then
inserts the angioplasty assembly 13 into the device by first operating the
knob 136 to move the idler roller 59 and the hook 163 to out-of-way or
out-of-engagement positions. The exchange wire 49 is then inserted between
the hook members 162 and 163 and between idler roller 59 and the drive
roller 58. Thereafter, the knob 136 can be released so that the exchange
wire 49 is frictionally engaged by the rollers 58 and 59. Thereafter, the
proximal side arm adapter 42 is slipped between the clips 154 and 156 so
that it is seated upon the block 153 with the knob 47 disposed between the
members 158.
The intermediate side arm adapter 36 is also positioned on the block 159
with its distal extremity between the upstanding pins 161. The knob 118 is
then engaged to move the idler roller 62 into an out-of-the-way or
disengaging position and the tubular member 28 of the dilatation catheter
26 is positioned between hook members 168 and 169 and hook members 166 and
167 and between the rollers 61 and 62. Thereafter, the knob 118 is
released to permit the hook members to engage the dilatation catheter 26
and to permit the idler roller 62 to move the tubular member 28 of the
dilatation catheter 26 into frictional engagement with the drive roller
61. Thereafter, the distal side arm adapter 18 is positioned over the
block 146 and slipped into the clips 147 and 148 with the knob 21 between
disposed between the members 151 on the block 149.
As soon as the angioplasty assembly 13 has been mounted on the housing 12,
the physician is ready to undertake the exchange procedure. This is
accomplished by rotating the knob 66 in a counterclockwise direction which
causes the drive rollers 58 and 61 to be rotated in counterclockwise
directions. It should be noted that although rollers 58 and 61 are being
rotated in the same direction as the knob 66, they are located on opposite
sides of the respective elements they engage, that is, the drive roller 58
is in engagement with the exchange wire 49 on the side facing the knob 66
whereas the drive roller 61 engages the tubular member 28 on the side
opposite the side facing the knob 66 and therefore exert frictional forces
upon the respective members in directions which are opposite to each
other. Thus upon counterclockwise rotation of the knob 66, the exchange
wire 49 is moved to the left as viewed in FIG. 1A, and the tubular member
28 is moved to the right as viewed in FIG. 1A. As explained previously,
the diameter of the rollers 58 and 59 and rollers 61 and 62 are such so
that for every increment that the tubular dilatation catheter is advanced,
the exchange wire 49 is advanced by a similar increment. This means that
as the dilatation catheter 26 is withdrawn from the blood vessel through
the guiding catheter 16, the exchange wire 49 is inserted with respect to
the tubular member so that the distal extremity of the exchange wire 49
remains in the exact same position within the blood vessel in the body. As
the dilatation catheter 26 is withdrawn, a loop 181 is formed in the
dilatation catheter as shown in broken lines in FIG. 1A. As the dilatation
catheter 26 is being removed, a larger and larger loop 181 is formed. This
withdrawal procedure is continued until the distal extremity of the
dilatation catheter 26 is clear of the rollers 61 and 62 and the rollers
61 and 62 engage the exchange wire 49. When the distal extremity of the
dilatation catheter clears the knob 21, there may be a tendency for blood
to flow from the guiding catheter 16 and the knob 21 is tightened down so
as to inhibit this flow of blood.
As soon as the distal extremity of the dilatation catheter 26 has cleared
the rollers 61 and 62, the proximal portion of the angioplasty assembly 13
is lifted out of the means provided for securing the intermediate side arm
adapter 36 and the proximal side arm adapter 42 to the housing 12. As the
assembly 13 is removed from the clips on the housing 12, one hand is
utilized for operating the knob 136 so that the exchange wire 49 is
released from between the rollers 58 and 59 and from between the hook
members 162 and 163. The dilatation catheter 26 then can be slipped off of
the exchange wire. As soon as this has been accomplished, another
dilatation catheter having a baloon of the desired size can then be
slipped on to the exchange wire 49. In slipping the new dilatation
catheter over the exchange wire 49, a loop similar to loop 181 can be
formed. The intermediate and proximal side arm adapters 36 and 42 can then
be snapped into place onto the housing 12 in a manner hereinbefore
described. As soon as this has been accomplished, the knob 66 can be
rotated in a clockwise direction to cause the dilatation catheter to be
introduced into the guiding catheter 16 and at the same time causing the
exchange wire 49 to be retracted by a corresponding amount so that the
distal extremity of the exchange wire 49 remains in the same precise
position during the time that the new dilatation catheter is being
advanced until the balloon of the dilatation catheter reaches the desired
position. With the devce of the present invention there is a one-to-one
correspondence between retraction and insertion so that the distal
extremity of the exchange wire remains in the same position throughout the
procedure.
If the physician desires to utilize a different dilatation catheter, the
same procedure can be readily accomplished within a relatively short
period of time so that a plurality of dilatation catheters can be utilized
in connection with forming an opening in a single stenosis if desired.
After the angioplasty procedure has been accomplished, the entire
angioplsty assembly 13 can be removed from the patient. The angioplasty
assembly 13 and the device 11 can then be disposed of. The device 11 is to
be a throw-away device to be utilized with only a single angioplasty
procedure to avoid any possible contamination. It should be appreciated,
however, that if desired the device 11 can be constructed of materials
which would make it possible to sterilize the same so it can be utilized
for successive angioplasty procedures if that is desirable. To make this
possible, it is merely necessary to construct a device of materials which
would facilitate sterilization.
In conjunction with the foregoing, it should be noted thr four rollers have
been utilized for the insertion and extraction procedures hereinbefore
described. It should be appreciated that as few as three rollers could be
utilized for this procedure by utilizing a single drive roller and having
idler rollers engaging opposite sides of the drive roller with the
dilatation catheter being disposed between one idler roller and the drive
roller on one side and the exchange wire being disposed between the other
idler roller and the drive roller. This procedure, however, would make it
more difficult to compensate for the difference in diameters between the
exchange wire and the dilatation catheter.
The use of the device of the present invention is particularly advantageous
in that it makes it possible for a single physician to accomplish the
exchange procedure with great precision and without the necessity of
continuously observing the exchange procedure under x-rays. Therefore this
greatly reduces the amount of exposure that the patient receives from
x-rays during an angioplasty procedure.
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