Linear eversion catheter system with position indicating indicia

An everting catheter system comprising an outer tube having an outer catheter lumen and an opening leading from the outer catheter lumen, an inner catheter movable longitudinally in the outer catheter lumen and having an inner catheter lumen and an everting element coupled to the outer catheter and the inner catheter so that with movement of the inner catheter distally in the outer catheter lumen, the everting element can be everted through the opening. An elongated instrument is movable longitudinally in the inner catheter lumen relative to the inner catheter. Indicia are provided on the inner catheter and the instrument for indicating at least one longitudinal position of the instrument relative to the distal end of the everting element.

BACKGROUND OF THE INVENTION 
An everting catheter typically includes an outer catheter having an outer 
catheter lumen and an inner catheter movable longitudinally in the outer 
catheter lumen and having an inner catheter lumen. An everting element is 
coupled to the outer catheter and the inner catheter so that, with 
movement of the inner catheter distally in the outer catheter lumen, the 
everting element can be everted through an opening in the outer catheter. 
An everting catheter of this type can be inserted through a passage in the 
human body with the everting element in an inverted position. An 
elongated, flexible instrument can then be introduced through the inner 
catheter lumen and the everted everting element to position the instrument 
into a desired body region and accomplish any of a variety of medical 
procedures and/or viewing of internal body regions. 
In order that any of these functions can be properly carried out, it is 
commonly necessary to know the location of the distal end of the 
instrument in relation to the distal end of the everting element. This may 
be necessary, for example, to prevent the instrument from extending 
distally beyond the everting element where the instrument might cause 
injury to delicate body tissues or organs. 
Prior art techniques for ascertaining the position of the instrument in 
relation to the distal end of the everting element include ultrasound and 
fluoroscopy. Unfortunately, neither of these techniques is satisfactory 
for use in the fallopian tubes. More specifically, ultrasound is 
uncomfortable for the patient and does not locate the distal end of the 
instrument in relation to the distal end of the everting element as 
precisely as desired. In this regard, it is important that the instrument 
not extend beyond the distal end of the everting element because of the 
very delicate nature of the fallopian tubes. Fluoroscopy is also not 
suitable because of the possibility that the X-rays will be detrimental to 
the patient's fertility. 
SUMMARY OF THE INVENTION 
This invention provides an everting catheter system which solves these 
problems. With this invention, the instrument can be accurately located 
relative to the distal end of the everting element, and this is 
accomplished without the need for relatively expensive position-detecting 
equipment, such as ultrasound or fluoroscopy equipment. In fact, the 
everting catheter system of this invention accomplishes the 
position-detecting function very inexpensively. Moreover, the 
position-detection technique of this invention is very easy to use and is 
unlikely to introduce error in ascertaining the position of the instrument 
relative to the distal end of the everting element. 
Ascertaining the position of the distal end of the instrument relative to a 
distal opening in the outer catheter is relatively easy because the distal 
opening is typically fixed, and the instrument moves with respect to it. 
However, determining the relative position of the distal ends of the 
instrument and the everting element is more complex because the instrument 
and the everting element are independently movable. Moreover, because of 
the nature of an everting catheter, the distal end of the everting element 
moves only one-half as far as the inner catheter. 
With this invention, indicia on the inner catheter and the instrument 
indicate at least one longitudinal position of the instrument relative to 
the distal end of the everting element. Preferably, the indicia indicate a 
plurality of longitudinal positions of the instrument relative to the 
distal end of the everting element, and these positions may be anywhere 
from the fully inverted position to the fully everted position. For use in 
the fallopian tubes, one important position that can be detected by this 
invention is when the distal end of the instrument is closely adjacent the 
distal end of the everting element, and this can be accomplished even when 
the everting element is between the fully inverted and fully everted 
positions. 
In one preferred form, the indicia on the inner catheter are exposed to an 
extent which is related to the longitudinal position of the inner catheter 
in the outer catheter lumen, and the indicia on the instrument are exposed 
to an extent which is related to the longitudinal position of the 
instrument in the inner catheter lumen. With this arrangement, the 
longitudinal position of the instrument relative to the distal end of the 
everting element is related to the exposed indicia on both the inner 
catheter and the instrument. In addition, the indicia on the inner 
catheter indicate the position of the distal end of the everting element 
relative to the distal opening of the outer catheter so that the extent to 
which the everting element is everted is known. 
Indicia have the advantage of being very inexpensive and easy to use. In 
addition, indicia can accurately show the position of the instrument 
relative to the distal end of the everting element. 
The indicia can be of any type that will accomplish this purpose. For 
example, the indicia may include numbers and even longitudinal stripes of 
varying width. However, to simplify the system and thereby minimize the 
likelihood for error that could cause patient injury, the indicia 
preferably include a first set of spaced apart marks on the inner catheter 
and a second set of spaced apart marks on the instrument. These marks may 
be provided in any form which is human or machine readable; however, 
because these procedures are normally carried out by hand, human readable 
marks are preferred. 
Because the distal end of the everting element moves at only one half the 
rate of the inner catheter, the adjacent marks on the inner catheter are 
spaced apart a distance which is twice the distance that adjacent marks on 
the instrument are spaced apart. More specifically, the position of the 
distal end of the instrument relative to the distal end of the everting 
element can be expressed as a function P=I+S-K where P is the distance 
between the distal ends of the instrument and the everting element, I is 
the number of the exposed marks of the inner catheter, S is the number of 
exposed marks of the instrument and K is a constant. K can be defined in 
different ways. For example in one particular kind of everting catheter, K 
may be equal to the number of exposed marks of the inner catheter when the 
everting element is fully inverted or the number of exposed marks on the 
instrument when the everting element is fully everted and the distal end 
of the instrument is substantially at the distal end of the everting 
element. K may also be the number of exposed marks on the instrument when 
the distal end of the instrument is within the extension of the inner 
catheter lumen defined by the everting element and is spaced from the 
distal opening of the outer catheter about one half the distance that the 
distal end of the inner catheter is spaced from the distal opening of the 
outer catheter, and the everting element is fully inverted. K may also 
equal one half the sum of the exposable marks of the first and second set 
of marks. Preferably, the number of exposable marks on the instrument 
equals the number of exposable marks on the inner catheter. 
The indicia on the instrument also include a baseline indicator which, in 
the preferred embodiment, is also spaced a distance X from an adjacent 
mark of the set of marks on the instrument. The baseline indicator is used 
to define a 0 or baseline position and is not considered as a mark usable 
in P=I+S-K formula. Thus, by placing the instrument at a location in the 
inner catheter lumen such that the baseline indicator is either barely 
visible or just hidden, the exposed marks can be counted, and this is 
regarded as a baseline or 0 position of the instrument. Although the 
baseline indicator can be eliminated if desired, its use is preferred so 
that the 0 or baseline position can be accurately established; however, 
the baseline indicator is not counted in determining the location of the 
instrument relative to the distal end of the everting element. The indicia 
on the inner catheter may also include a baseline indicator which is also 
not counted in the P=I+S-K formula. 
The 2-to-1 spacing of the marks on the inner catheter of the instrument is 
not essential. However, it greatly simplifies use of the catheter system 
in that the location of the distal end of the instrument relative to the 
distal end of the everting element can be determined by simply counting 
the total number of exposed marks. In the preferred system, K equals 10, 
and a total of 10 exposed marks, i.e. P=0, means that the distal end of 
the instrument is at, or closely adjacent., the distal end of the everting 
element. 
If P is greater than 0, the distal end of the instrument is within the 
everting element, and if P is negative, the distal end of the instrument 
extends distally beyond the distal end of the everting element. Moreover, 
the numerical value of P indicates the number of units of spacing between 
the distal ends of the instrument and the everting element. For example, 
if the adjacent marks on the instrument are spaced apart 1 centimeter and 
the adjacent marks on the inner catheter are spaced apart 2 centimeters, 
then if P equals 3, the physician knows that the distal end of the 
instrument is within the everting element and spaced 3 centimeters 
proximally of the distal end of the everting element. 
Of course, the condition of P equals 0 need not indicate that the distal 
end of the instrument is precisely at the distal end of the everting 
element, and to provide a safety factor, the P equals 0 condition may 
indicate that the distal end of the instrument is closely adjacent the 
distal end of the everting element and may be slightly within the everting 
element. In a broader sense, the P equals 0 condition may identity any 
desired or known orientation of the distal ends of the instrument and the 
everting element. 
The instrument may be any elongated instrument for examination of an 
interior body region or for carrying out a medical procedure on an 
interior body region. This invention is particularly adapted for use with 
a scope which enables interior body regions to be seen and which should 
not extend significantly or at all distally of the distal end of the 
everting element; however, this invention is not limited to this 
particular kind of instrument. 
The invention, together with additional features and advantages thereof may 
best be understood by reference to the following description taken in 
connection with the accompanying illustrative drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows a catheter system 11 which is particularly adapted for 
accessing the fallopian tubes; however, it should be understood that the 
features of this invention are also applicable to catheter systems adapted 
for other purposes. The catheter system 11 generally comprises an outer 
catheter 13, and inner catheter 15, an everting element 17 (FIG. 2B) and 
an elongated instrument 19. The outer catheter 13 includes an elongated, 
flexible catheter body 21 and an outer catheter fitting 23 coupled to the 
proximal end of the catheter body 21. The outer catheter 13 has an outer 
catheter lumen 25 (FIG. 2B) which extends from a proximal opening 27, 
which is provided by the outer catheter fitting 23 to a distal opening 29 
(FIG. 2B) which, in this embodiment, is at the distal end of the catheter 
body 21. Of course, the catheter body 21 may have multiple lumens, if 
desired, and the distal opening 29 need not be at the distal end of the 
catheter body. 
The catheter body 21 has a distal end portion 31 which, in its unstressed 
condition, may be straight or of any other shape designed to best gain 
access to a desired region of the body. As shown in FIG. 1, the distal end 
portion 31 is curved and forms a portion of a circular arc in the 
unstressed condition, and this facilitates access to the ostia of the 
fallopian tubes. However, the shape of the distal end portion 31 forms no 
part of this invention, and the distal end portion is shown for 
convenience in FIGS. 2B, 3B, 4B, 5B and 6B as linear. 
The outer catheter 13 may be of conventional construction, and the catheter 
body 21 may be constructed of a flexible, biocompatible polymeric 
material. The outer catheter fitting 23 has an injection leg 33 through 
which an inflation media can be supplied to the outer catheter lumen 25 to 
control the inversion and eversion of the everting element 17 in a known 
manner. 
The inner catheter 15 is extendible through the proximal opening 27 of the 
outer catheter 13 and is movable longitudinally in the outer catheter 
lumen 25. The inner catheter 15 also includes a catheter body 35 and an 
inner catheter fitting 37 coupled to the proximal end of the catheter body 
35. The inner catheter 15 has an inner catheter lumen 39 (FIG. 2B) which 
extends between a proximal opening 41 provided by one leg of the inner 
catheter fitting 37 and a distal opening 43 (FIG. 2B) at the distal end 44 
of the catheter body 35. 
The catheter body 35 may be flexible or rigid depending upon the nature and 
purpose of the catheter system 11. However, in this embodiment, a distal 
region of the catheter body 35 is flexible such that the portion of the 
catheter body 35 that is within the distal end portion 31 in all positions 
of the inner catheter 15 relative to the outer catheter 13 is flexible. 
The fitting 37 has an injection leg 45 which can be used, for example, for 
injecting irrigation fluid, a contrast dye or drugs into the inner 
catheter lumen 39. The leg 45 can also be used for aspiration, if desired. 
The everting element 17 (FIG. 2B) is a thin, flexible membrane which is 
constructed of a suitable polymeric material. The everting element 17 is 
bonded as by an adhesive to the catheter body 21 of the outer catheter 13 
closely adjacent the distal opening 29 and to a distal tip region of the 
catheter body 35 of the inner catheter 15 in accordance with known 
techniques. This forms a chamber 47 with the catheter body 21 of the outer 
catheter 13. Consequently, inflation media from the injection leg 33 
acting in the chamber 47 can bring about inversion and eversion of the 
everting element 17. The everting element 17 has a distal end 49 which, in 
the position of FIG. 2B, is substantially at the distal opening 29. The 
everting element 17 forms an extension 50 of the inner catheter lumen 39. 
The instrument 19 is elongated and flexible. The instrument 19 is 
introduced to the inner catheter lumen 39 through the proximal opening 41 
and can be moved both proximally and distally relative to the inner 
catheter 15 independently of the inner catheter. The instrument 19 
terminates distally in a distal end 51 (FIG. 2B). In this embodiment, the 
instrument 19 is an endoscope for examination of the fallopian tubes. 
Because the everting element 17 is coupled at one end to the inner catheter 
15, these two members move together during the inversion and eversion. 
However, because the everting element 17 forms a double layer as best 
shown in FIGS. 4B, 5B and 6B, the inner catheter 15 must move 
longitudinally for 2 centimeters for each centimeter of movement of the 
distal end 49. Accordingly, locating the distal end 51 of the instrument 
with respect to the distal end 49 of the everting element is complicated 
by two factors, i.e., these distal ends are movable independently of each 
other and the inner catheter 15 moves twice the distance of the distal end 
49 of the everting element. 
In order to be able to know the longitudinal position of the instrument 19 
relative to the distal end 49 of the everting element 17, this invention 
provides indicia 53 and 55 on the inner catheter 15 and the instrument 19, 
respectively. The indicia 53 on the inner catheter 15 are exposed to an 
extent which is related to the longitudinal position of the inner catheter 
in the outer catheter lumen 25. The indicia 53 also indicate the position 
of the distal end 49 of the everting element 17 relative to the distal 
opening 29 of the outer catheter 13. Similarly, the indicia 55 are exposed 
to an extent which is related to the longitudinal position of the 
instrument 19 in the inner catheter lumen 39. As explained more fully 
below, the longitudinal position of the instrument 19 relative to the 
distal end 49 of the everting element 17 is related to the exposed indicia 
53 and 55 on both the inner catheter 15 and the everting element 17. 
The indicia 53 on the inner catheter 15 includes a first set of marks 57 
and an optional baseline indicator 58, and the indicia 55 of the 
instrument 17 includes a second set of marks 59 and a preferred, but not 
essential, baseline indicator 61. Adjacent marks 57, as well as the 
baseline indicator 58 and the adjacent mark 57, are spaced apart by a 
distance 2X, and adjacent marks 59, as well as the baseline indicator 61 
and the adjacent mark 59, are spaced apart by one half that amount, i.e., 
by a distance X. In this embodiment, there are a total of ten of the marks 
57 and ten of the marks 59, and the distance X is 1 centimeter. Except for 
the indicia 53 and 55, the catheter system 11 may be conventional. 
FIG. 2B shows the everting element 17 in the fully inverted position, and 
in that position, all 10 of the indicia 57 on the inner catheter 15 are 
exposed as shown in FIG. 2A with the baseline indicator 58 being located 
at the proximal opening 27 of the fitting 23. For an outer catheter 13 and 
an inner catheter 15 of the construction shown in FIG. 2B, the instrument 
19 is within the extension 50 of the inner catheter lumen 39 and is spaced 
from the distal opening 29 of the outer catheter 13 about one half the 
distance that the distal end 44 of the inner catheter 15 is spaced from 
the distal opening 29. This relationship would not exist, if for example, 
the inner catheter 15 were longer so that the distal end 44 were located 
distally of the position shown in FIG. 2B. In this position, all 10 of the 
marks 59 are exposed, with the baseline indicator 61 being located at the 
proximal opening 41 of the fitting 37. 
The location of the distal end 51 of the instrument 19 in relation to the 
distal end 49 of the everting element 17 can be ascertained from the 
formula P=I+S-K where P is the distance between the distal ends 49 and 51, 
I is the number of exposed marks 57 of the inner catheter 15, S is the 
number of exposed marks 59 of the instrument 19 and K is a constant. In 
this embodiment, K is 10. Although this number and arrangement of the 
marks 57 and 59 are preferred, other numbers and spacings of marks can be 
employed, if desired. For example, by employing additional marks 59 
distally of the baseline indicator 61, exact positions of the distal end 
51 of the instrument 19 relative to the distal end 49 of the everting 
element 17 can be determined even if the instrument is moved proximally 
from the position shown in FIG. 2B. Exposable marks are the number of 
marks 57 and 59 which are visible with the inner catheter 15 and the 
instrument 19 in their most proximal positions. In this embodiment as 
referred to above, there are 10 of the marks 57 and 59. Exposed marks are 
the marks 57 and 59 which are visible and not at the proximal openings 27 
or 41. The baseline indicators 58 and 61 are not considered as exposed or 
exposable marks. 
Applying the above formula to FIGS. 2A and 2B, it can be seen that P equals 
10 plus 10 minus 10 or 10. Accordingly, the distal end 51 of the 
instrument 19 is spaced 10 units proximally of the distal end 49 of the 
everting element 17 as shown in FIG. 2B. In this case, the units are 
centimeters, and so the spacing between the distal ends 49 and 51 is 10 
centimeters. 
In FIGS. 3A and 3B, the instrument 19 is moved proximally in the inner 
catheter lumen 39 so that the most proximal mark 59 is at the proximal 
opening 41, and so none of the marks 59 is exposed. In this position, the 
distal end 51 of the instrument is essentially in the plane occupied by 
the distal end 49 of the everting element 17. The inner catheter 15 is in 
the same position as in FIGS. 2A and 2B. Accordingly, by applying the 
formula above, it can be seen that 0 plus 10 minus 10 equals 0 which 
notifies the physician that the distal end 51 is at, or substantially at, 
the distal end 49. 
In FIGS. 4A and 4B, the everting element 17 is everted out of the distal 
opening 29, and the inner catheter 15 is advanced such that the most 
proximal mark 57 is at the proximal opening 27, and so none of the marks 
57 is exposed. The instrument 19 is also moved proximally such that the 
baseline indicator 61 is at the proximal opening 41, and 10 of the marks 
59 are exposed as shown in FIGS. 4A. Applying the above formula, 10 plus 0 
minus 10 equals 0 which again indicates to the physician that the distal 
end 51 of the instrument is at, or substantially at, the distal end 49 of 
the everting element 17. In the position of FIGS. 4A and 4B, the distal 
end 51 is at, or substantially at, the distal end 49, and K is equal to I, 
i.e. the number of exposed marks 59 on the instrument. 
In FIGS. 5A and 5B, the everting element 17 is partially everted out of the 
distal opening 29, and the inner catheter 15 is positioned accordingly as 
shown in FIG. 5A such that the fifth mark 57 is at the proximal opening 
27, and 5 of the marks 57 are exposed. Similarly, the instrument 19 is 
moved within the inner catheter lumen 39 such that 5 of the marks 59 are 
exposed. Applying the above formula, 5 plus 5 minus 10 equals 0 which 
again informs the physician that the distal end 51 of the instrument 19 is 
at, or substantially at, the distal end 49 of the everting element 17. 
In FIGS. 6A and 6B, the inner catheter 15 is in the same position as in 
FIGS. 5A and 5B, and the everting element 17 is partially everted to the 
same extent as in FIGS. 5A and 5B so that 5 of the marks 57 are exposed. 
However, the instrument 19 is located proximally of the position it 
occupies in FIGS. 5A and 5B such that the distal end 51 is retracted from 
the distal end 49 as shown in FIG. 6B. Consequently, the second 
distal-most mark 59 is at the proximal opening 41, and there are 8 of the 
marks 59 exposed. Applying the formula, 8 plus 5 minus 10 equals 3 which 
informs the physician that the distal end 51 is located 3 centimeters 
proximally of the distal end 49. 
Many other relative positions of the distal ends 49 and 51 can be 
determined utilizing the indicia 53 and 55, and the examples given above 
are purely illustrative. It should, however, be noted that, by moving the 
instrument 19 distally from the position shown in FIGS. 6A and 6B until 
the most proximal mark 59 is at the proximal opening 41 would cause the 
distal end 51 to protrude distally of the distal end 49. In this event, 
the physician would be informed by the fact that the formula would yield 0 
plus 5 minus 10 equals -5 which is notification that the distal end 51 of 
the instrument 19 extends 5 centimeters beyond the distal end 49 of the 
everting element 17. 
Although an exemplary embodiment of the invention has been shown and 
described, many changes, modifications and substitutions may be made by 
one having ordinary skill in the art without necessarily departing from 
the spirit and scope of this invention.