Catheters with integrated lumen and methods of their manufacture and use

A catheter with at least one integrated lumen and methods of its manufacture and use are provided. A method of manufacture includes: (1) covering a primary mandrel with a first layer, (2) disposing a second layer on the first layer, wherein the second layer has at least one removable secondary mandrel substantially embedded therein, (3) fusing the first layer to the second layer, (4) removing the secondary mandrel from the second layer to form a secondary lumen, and (5) removing the primary mandrel from the first layer to form a primary lumen. The method may further include forming an inflatable balloon at the surface of the second layer where the secondary lumen forms an opening. Also, auxiliary apparatus, such as snare instruments and bundles of optical fibers, may be inserted through the secondary lumen before or during use of the catheter.

BACKGROUND OF THE INVENTION 
This invention relates to medical devices and procedures used during the 
repair, replacement, or supplement of a medical patient's natural body 
organ structures or tissues. In particular, this invention relates to 
catheters with at least one integrated lumen for use in connection with 
such medical procedures and to methods of their manufacture. 
Revascularization of the human heart is a good example of a medical 
procedure that involves the repair and supplement of a patient's body 
organ. Early procedures were known for revascularizing the human heart, 
but there were several disadvantages to these procedures. The earliest 
procedures involved exposing the heart by means of a midline sternotomy 
and stopping the beating of the heart to facilitate performance of the 
procedure. A graft is used to create a new, uninterrupted channel between 
a blood source, such as the aorta, and the occluded coronary artery or 
arteries downstream from the arterial occlusion or occlusions. Such a 
procedure has significant disadvantages, however, because it is highly 
invasive and requires general anesthesia. In fact, these disadvantages 
preclude the use of sternotomy procedures on many patients. 
Less invasive procedures were later developed for revascularizing the 
heart, but these have disadvantages as well. For example, a thoracostomy 
involves surgical creation of ports in the patient's chest to obtain 
access to the thoracic cavity. Specially designed instruments are then 
inserted through the ports. Thoracostomy bypass procedures are less 
traumatic than sternotomy bypass procedures, but they are still too 
traumatic for some patients and may be inadequate when the number of 
surgical bypasses is large. Another procedure, which is known as a 
thoracotomy, revascularizes the human heart by gaining access to the 
thoracic cavity with incisions between the patient's ribs, but this 
procedure may still be too traumatic for some patients. 
Goldsteen et al. U.S. patent application Ser. No. 08/745,618, filed Nov. 7, 
1996, which is hereby incorporated by reference herein, discloses a less 
traumatic surgical technique for revascularizing the human heart. A key 
aspect of that invention involves the use of catheters that are inserted 
into a patient's body through relatively remote entry ports, such as a 
femoral (leg) artery of the patient, a brachial artery of the patient, or 
any other suitable entry point. Control of these instruments throughout 
their use is from a proximal portion that is outside the patient at all 
times. In order to minimize the number of entry ports or to perform any of 
the specialized surgical techniques disclosed therein, a single catheter 
instrument may include two or more lumens. However, as the number of 
lumens increases, conventional manufacturing methods may yield catheters 
that have outer diameters that are undesirably large, which may irritate 
sensitive vessels and preclude their use in narrow vessels. Furthermore, 
such catheters may be difficult to position and secure in a patient's 
body. 
In view of the foregoing, it is an object of this invention to provide less 
traumatic methods and apparatus for revascularizing a patient. 
It is another object of the invention to provide methods of manufacturing 
catheters with integrated lumens without substantially increasing the 
thickness of catheter walls. 
It is still another object of the invention to provide a catheter that can 
create a hemodynamic seal when positioned across vessel walls. 
It is yet another object of the invention to provide a catheter that can be 
positioned in a vessel and used to selectively secure one or more medical 
devices therein. 
SUMMARY OF THE INVENTION 
These and other objects of the invention are accomplished in accordance 
with the principles of the invention by providing a catheter having at 
least one secondary lumen. The catheter includes a first flexible tubular 
layer with a primary lumen or passageway inside, and a second flexible 
layer that is at least partially fused to the outer surface of the first 
layer. The second layer has at least one secondary lumen that is 
substantially integrated into the second layer and opens through the 
second layer at a secondary lumen opening. In a preferred embodiment 
according to this invention, the catheter may further include a structural 
layer that is located substantially between the first and second layers. 
A method for making a catheter in accordance with this invention is also 
provided. In a first step, a primary mandrel is covered with a first layer 
having an outer surface. In a second step, a second layer is disposed on a 
portion of the outer surface of the first layer. The second layer 
substantially forms the catheter wall and has at least one removable 
secondary mandrel substantially embedded therein. In a third step, the 
first layer is fused to the second layer. In a fourth step, the secondary 
mandrels are removed from the second layer to form respective secondary 
lumens. Each of the secondary lumens opens at a surface of the second 
layer at a respective secondary lumen opening. A secondary lumen may 
extend through the first layer if the secondary opening is at the radially 
inner surface of the second layer. And in a fifth step, the primary 
mandrel is removed from the first layer to form a primary lumen. 
Further features of the invention, its nature and various advantages will 
be more apparent from the accompanying drawings and the following detailed 
description of the preferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
According to the present invention, a catheter having at least one 
integrated lumen in a catheter wall, and methods for the manufacture and 
use of such a catheter, are provided. The method of manufacture involves 
covering a primary mandrel with a first layer and fusing a second layer, 
having at least one integrated lumen, to the outer surface of the first 
inner layer. The integrated lumen may be used to position or secure 
medical devices or to deliver fluids to a particular location anywhere 
along the catheter's length. 
As shown in FIG. 1A, catheter 100 includes at least first flexible layer 
110 and second flexible layer 130 around longitudinal axis 160. First 
layer 110 has outer surface 115 and primary lumen 120, which extends 
longitudinally inside first layer 110. Second layer 130 has inner surface 
135 that is at least partially fused to outer surface 115 of first layer 
110. Second layer 130 has secondary lumens 140 and 150 that are 
substantially integrated into second layer 130 and open through second 
layer 130 at respective secondary lumen openings 142 and 152. As will be 
discussed more fully below, catheter 100 may further include structural 
layer 137, such as a metal braid or coil, which is substantially located 
between first layer 110 and second layer 130 for providing some rigidity 
to catheter 100. 
As shown in FIG. 1B, first layer 110 preferably has an elliptical cross 
section, most preferably a substantially cylindrical cross section. First 
layer 110 can be made from any flexible material, such as polymers. 
Polymers that may be used to make first layer 110 according to this 
invention include polytetrafluoroethylene (such as that sold under the 
trademark TEFLON.RTM. by E. I. du Pont de Nemours & Company, of 
Wilmington, Del.), polyetheramide (such as that sold under the trademark 
PEBAX.RTM., by Ato Chemie, of Courbeboie, France), polyamide, or 
polyimide. 
The magnitude of inner diameter 121 of first layer 110 depends on the 
particular vascular intervention for which catheter 100 is used, but can 
certainly range from about 0.050 inches to about 0.225 inches. First layer 
110 is preferably thin and has a wall thickness 122 of between about 0.001 
inches and about 0.003 inches. Second layer 130 may be any polymer that is 
capable of flowing when subject to elevated temperatures during fusing, 
such as polyetheramide, polyamide, or polyimide. Outer surface 115 of 
first layer 110 is preferably roughened to improve adhesion to inner 
surface 135 second layer 130. Outer surface 115 may be roughened 
mechanically or chemically, but any roughening technique may be used. One 
type of chemical etching technique involves exposing the surface to 
tetrafluoroethylene (such as that sold under the trademark 
TETRA-ETCH.RTM., by W. L. Gore & Associates, Inc., of Newark, Del.). 
The second layer has at least one substantially integrated secondary lumen. 
As shown in FIG. 1A, second layer 130 has integrated secondary lumens 140 
and 150. According to this invention, any number of secondary lumens could 
be integrated at nearly any location in second layer 130, depending on the 
particular vascular intervention. For example, two secondary lumens 140 
and 150 provide fluid communication to inflatable balloons 144 and 154 
that can form a hemodynamic seal at a vessel wall. 
The locations of integrated lumens also depend on the particular vascular 
intervention. As best shown in FIG. 1B, catheter 100 has two secondary 
lumens 140 and 150 that are preferably substantially adjacent to inner 
surface 135 of second layer 130 and located on opposite sides of primary 
lumen 120. Secondary lumens 140 and 150 are preferably integrated near 
inner surface 135 to improve the strength of, and prevent kinking in, 
catheter 100. This inner surface arrangement is in contrast to an 
intermediate arrangement, where the secondary lumen is located 
intermediately between inner surface 135 and outer surface 131. That 
intermediate arrangement divides the wall thickness into two thinner 
portions which are not as structurally robust as the inner surface 
arrangement shown in FIGS. 1A and 1B. As shown in FIG. 1A, secondary 
lumens 140 and 150 also extend substantially parallel to longitudinal axis 
160 for at least a portion of catheter 100. 
Although both ends of a secondary lumen are open to provide access to the 
secondary lumen, only the distal end of a secondary lumen is shown in the 
FIGS. That distal opening may be formed at any surface of the second 
layer. For example, FIGS. 2A-2C show catheters having secondary lumen 
openings on the radial outer surface, distal end, and radial inner surface 
of a second layer, respectively. In FIG. 2A, catheter 210 has first layer 
212, structural layer 214, and second layer 216. Second layer 216 of 
catheter 210 has one secondary lumen 218, which has outer secondary lumen 
opening 219 at outer surface 215 of second layer 216. In FIG. 2B, catheter 
220 has first layer 222, structural layer 224, and second layer 226. 
Second layer 226 of catheter 220 has one secondary lumen 228, which has 
distal secondary lumen opening 229 at distal end 225 of second layer 226. 
Finally, in FIG. 2C, catheter 230 has first layer 232, structural layer 
234, and second layer 236. In catheter 230, second layer 236 has one 
secondary lumen 238, which has inner secondary lumen opening 239 at inner 
surface 235 of second layer 236. Catheter 230 also preferably has 
secondary lumen extension 240, which extends through first layer 232. 
Extension 240 extends from secondary lumen opening 239 to extension 
opening 249 located on inner surface 233 of first layer 232. In order to 
provide fluid communication between secondary lumen 238 and extension 240, 
structural layer 234, which acts like a flexible skeleton, is preferably 
porous. Structural layer 234, for example, may be made from any relatively 
stiff structural material, such as stainless steel braid or coil. 
As shown in FIG. 1, catheter 100 may further include one or more inflatable 
balloons 144 and 154. These balloons are formed at respective secondary 
lumen openings 142 and 152 by covering the openings with elastic sheets or 
tubes, preferably bonded to outer surface 131 of second layer 130. 
Balloons 144 and 154 may also be formed from a single elastic sheet that 
covers both openings. In that case, a continuous strip of the sheet may be 
bonded to outer surface 131 of second layer 130 between openings 142 and 
152 to form two separate compartments that are separately inflatable and 
deflatable. On the other hand, the balloons may be in fluid communication 
with each other so that only one secondary lumen is required to inflate or 
deflate, but the balloons in this case would not be independently 
controllable. Fluid communication between the balloons can be obtained by 
only partially bonding the strip of the sheet between the balloons. When 
two balloons are formed adjacent each other for gripping a vascular wall, 
as shown in FIGS. 1A and 3C, proximal secondary lumen opening 142 and 
distal secondary lumen opening 152 preferably have an axial separation 
that is greater than a thickness of the vascular wall. Because secondary 
lumens 140 and 150 extend outside of a patient during catheter use, the 
fluid pressure in the balloons can be monitored at the proximal end of the 
secondary lumen and controlled as desired. 
The elastic sheets used to form balloons 154 and 154 may be bonded to outer 
surface 131 of second layer 130 by adhesive or heat treatment. The elastic 
sheet or tube may be made from any flexible material, such as 
polyurethane, silicone, rubber, and preferably latex materials (such as 
that products sold by The Pioneer Rubber Company, of Willard, Ohio or by 
California Latex Inc., of Pomona, Calif.). Preferably, the modulus of the 
elastic sheet or tube is between about 200 and about 2,500 psi. The outer 
surface of the balloon may be provided with channels to facilitate fluid 
flow when the balloon is inflated in a vessel. When the sheet has an 
annular shape that fits circumferentially around second layer 130, the 
sheet may be bonded to outer surface 131 along the sheet edges or tube 
ends to form an annular balloon. The elastic sheet or tube may be 
preformed before being bonded to outer surface 131 so that the sheet forms 
a hollow ring that opens radially inward. Preferably, the radially outer 
portion of the ring is larger than the radially inner portion of the ring 
so that a cross-section of the ring has a bulbous shape. 
FIG. 3C shows catheter 370 (which is similar to catheter 100) secured to 
vascular wall 380 with a hemodynamic seal. Securing is preferably 
accomplished by at least partially inflating proximal balloon 374, 
inserting distal end 371 of catheter 370 through vascular wall 380 until 
wall 380 presses against inflated proximal balloon 374, and inflating 
distal balloon 372. Inflation of distal balloon 372 secures vascular wall 
380 between balloons 372 and 374 and forms a hemodynamic seal between wall 
380 and balloons 372 and 374. Although preinflation of proximal balloon 
374 may be preferable to avoid over-insertion of catheter 370, both 
balloons may be deflated during the inserting step and inflated after the 
inserting step. 
In addition to providing fluid communication to balloons, the secondary 
lumens may be used to position or secure the catheter itself or other 
auxiliary medical apparatus, or to deliver fluids to a particular location 
along the catheter's length. 
One such medical apparatus is endoscopic snare instrument 350 (see FIG. 
3A). Instrument 350 includes shaft 352 with snare loop 354 at its distal 
end. Loop 354 is substantially closed when it is inside a snare sheath 
(not shown) or secondary lumen 340. Loop 354 may open resiliently to the 
shape shown in FIG. 3A when extended distally through secondary lumen 
opening 356 or when extended distally through secondary lumen opening 366 
beyond distal end 360 of a sheath or secondary lumen 340. 
During operation, snare loop 354 may initially be in an open position in 
primary lumen 320 for subsequent securing of device 390 within primary 
lumen 320. In this case, inner surface 310 of catheter wall 305 may have 
recessed portion 307 for receiving open snare loop 354 so that loop 354 
does not catch on device 390 when it is inserted through primary lumen 
320. Once device 390 is inserted, loop 354 may be retracted into secondary 
lumen 340, as shown in FIG. 3B. In that case, snare loop 354 contracts and 
secures any guide wire, safety wire, or any other medial device 390 inside 
loop 354. As shown in FIG. 3A, a snare may be also be positioned at distal 
end 360 of catheter 300 for holding, snaring, or retrieving. 
An advantage of using a snare instrument in a secondary lumen is that the 
principal catheter function (such as the installation of a new length of 
graft in a patient) and the secondary snare function (such as the securing 
of a device) may be performed simultaneously, eliminating the need to 
exchange one catheter for another during an operation. 
The secondary lumen may guide, in addition to snare instruments, other 
auxiliary apparatus. For example, a secondary lumen may guide a fiber 
optic bundle for transmitting light to the vascular site or for 
transmitting an image of the vascular site to the doctor performing the 
operation. A single bundle of fibers may also perform both functions. 
As described above, catheter 100 may include structural layer 137, such as 
a metal braid or coil. Structural layer 137 is located substantially 
between first layer 110 and second layer 130 for providing mechanical 
rigidity to catheter 100. As explained more fully below, the manufacture 
of catheter 100 involves fusing first layer 110 to second layer 130. In 
order to ensure proper bonding, structural layer 137 must not completely 
separate first layer 110 and second layer 130. Therefore, any porous 
structure that provides contact between first layer 110 and second layer 
130, such as metal braid or coil, would be an appropriate structural 
material. Structural layer 137 may also be embedded directly in second 
layer 130 before bonding first layer 110 to second layer 130. 
FIG. 4 shows an illustrative sequence of steps in accordance with this 
invention for manufacturing a catheter with at least one integrated lumen, 
such as catheter 100 shown in FIG. 1. These steps are described below with 
reference to FIGS. 5A-5F, which show catheter 100 at various intermediate 
manufacturing steps. To some extent these steps have already been 
mentioned, so the discussion of them here may be somewhat abbreviated. 
A method in accordance with this invention for making a catheter with 
integrated lumens involves covering a primary mandrel with a first layer 
and fusing a second layer, which has at least one integrated lumen, to the 
outer surface of the first layer. The exact number and location of the 
secondary lumens is a matter of design. 
In particular, primary mandrel 50 is covered with first layer 110 in step 
410 (see FIG. 5A). In step 414, an optional structural layer 137 may be 
placed over first layer 110 (see FIG. 5B). Then, in step 420, second layer 
130 is disposed over outer surface 115 of first layer 110 and optional 
structural layer 137 (see FIG. 5C). Second layer 130 has at least one 
secondary mandrel, which is preferably substantially embedded in second 
layer 130. FIG. 5C shows second layer 130 with embedded secondary mandrels 
132 and 133. Next, in step 430, first layer 110 is fused to second layer 
130 (FIG. 5D). In step 440, secondary mandrels 132 and 133 are removed 
from second layer 130 to form secondary lumens 140 and 150, each of which 
opens through second layer 130 at respective secondary lumen openings 142 
and 152 (FIG. 5E). In step 445, balloons 144 and 154 may be formed at 
respective secondary lumen openings 142 and 152 (FIG. 5F). And, in step 
450, primary mandrel 50 is removed from first layer 110 to form primary 
lumen 120 (e.g., FIG. 1A). As always, the number, positions, and sizes of 
the integrated secondary mandrels depend on the particular vascular 
operation being performed. 
Also, primary mandrel 50, which forms inner surface 111 of first layer 110, 
can have any cross sectional shape, but preferably has a generally 
elliptical shape. Most preferably, it has a circular cross section (e.g., 
FIG. 1B). These shapes are desirable because they have no sharp corners or 
edges that may snag or cause friction in primary lumen 120 during 
operation. Primary mandrel 50 is preferably made of a material capable of 
withstanding high temperatures and pressures, such as steel, and 
preferably stainless steel, because fusing step 430 may involve such 
conditions. Outer diameter 121 of primary mandrel 50 is preferably between 
about 0.050 inches and about 0.225 inches. For many vascular applications, 
outer diameter 121 of mandrel 50 (or equivalently inner diameter 121 of 
first layer 110) can be about 0.160 inches. 
First layer 110, which covers primary mandrel 50, may be made from any 
flexible material, such as many commonly available polymers. 
Polytetrafluoroethylene is a preferred flexible material. Because one 
function of first layer 110 is to provide a relatively low friction 
internal surface 111 for passing devices in primary lumen 120, the outer 
surface of primary mandrel 50, which may be used to mold inner surface 
111, is preferably smooth. Wall thickness 122 of first layer may be 
between about 0.001 inches and about 0.003 inches. First layer 110 may be 
deposited onto primary mandrel 50 from a vapor or formed by sliding a 
first tubular layer over primary mandrel 50. 
Unlike inner surface 111, outer surface 115 is preferably rough to 
facilitate fusion to inner surface 135 of second layer 130. Therefore, 
outer surface 115 is preferably roughened in step 412 before fusing step 
430 so that surfaces 115 and 135 can fuse properly. Roughening may be 
accomplished by mechanically or chemically etching outer surface 115, such 
as by treatment with tetrafluoroethylene, or molding or extruding first 
layer 110 so that outer surface 115 is initially rough. 
In step 414, structural layer 137 may be inserted over first layer 110 
before disposing step 420, or inserted as an integrated (or embedded) 
portion of second layer 130 during step 420. If first layer 110 is covered 
with structural layer 137 in step 414, structural layer 137 should only 
partially cover first layer 110 so that first layer 110 and second layer 
130 are at least partially in contact with each other for fusing in step 
430. In this way, structural layer 137 is substantially between first 
layer 110 and second layer 130. Structural layer 137 may be any material 
that prevents primary lumen from collapsing, yet provides a flexible 
skeleton that allows catheter 100 to bend as required, such as stainless 
steel in the form of a braid or coil, for example. 
In step 420, after primary mandrel 50 is covered with first layer 110 (and 
optionally structural layer 137), second layer 130 is disposed on at least 
a portion of outer surface 111 of first layer 110. Second layer 130 has at 
least one secondary mandrel (e.g., mandrels 132 and 133) substantially 
embedded therein. The secondary mandrels may be placed between first layer 
110 and second layer 130 and substantially embedded into second layer 130 
during fusing in step 430. Disposing step 320 may include sliding a hollow 
tube over first layer 110 until the tube substantially covers that layer. 
The tube, which becomes second layer 130, may be preformed during 
extrusion or molding so that the tube contains at least one integrated 
secondary lumen with a removable secondary mandrel. Although a secondary 
mandrel helps prevent the secondary lumen from collapsing during fusing 
step 430, in some cases the secondary mandrel may be removed before 
fusing. The tube that forms second layer 130 may also be preformed with an 
integrated lumen but without a secondary mandrel. In that case, the 
secondary mandrel may be embedded into the secondary lumen before fusing 
step 430. 
As described above, secondary lumens 140 and 150 may be integrated anywhere 
in second layer 130. For example, secondary lumens may be integrated 
substantially adjacent to inner surface 135 (as shown in FIG. 1B) or outer 
surface 131 of second layer or tube 130. Secondary lumens 140 and 150 
preferably extend longitudinally for at least a portion of catheter 100, 
but may extend radially (or any direction therebetween) for another 
portion, as shown near lumen openings 142 and 152. In order to ensure that 
catheter 100 will not collapse or break during use, minimum thickness 132 
of second layer 130 is preferably at least about 0.003 inches along a 
substantial length of the secondary lumens. Also, as already described 
above, secondary lumen openings 142 and 152 may be formed at outer surface 
131 (FIGS. 1A and 2A), inner surface 135 (FIG. 2C), or distal end 125 of 
the tube forming second layer 130 (FIG. 2B). As shown in FIGS. 3A and 3B, 
a single lumen may also have more than one opening. 
In fusing step 430, outer surface 115 of first layer 110 is fused to inner 
surface 135 of second layer 130. As shown in FIG. 5D, this may be 
accomplished in a series of sub-steps. In one series of sub-steps, heat 
shrink tubing 162 is placed over second layer 130 in step 431 and heated 
so that it applies a radially inward force against outer surface 131 of 
second layer 130 in step 433. The force, in combination with heat, causes 
first layer 110 to at least partially fuse to second layer 130. Typical 
fusing temperatures range from about 300.degree. F. to about 600.degree. 
F. Preferably, the fusing temperature is about 450.degree. F. After 
heating step 433, heat shrink tubing 162 is preferably removed in step 
435. 
In an alternate series of sub-steps, fusing may be accomplished by 
extruding second layer 130 on first layer 110 in step 432 and embedding 
secondary mandrel 132 and 133 in second layer 130 during extruding in step 
434. Then, in step 436, heat is preferably applied to second layer 130 so 
that first layer 110 fuses to second layer 130. Fusing step 430 may always 
include applying heat to first layer 110 by heating primary mandrel 50 as 
well. 
In step 445, after fusing in step 430, one or more inflatable balloons 144 
and 154 may be formed at integrated secondary lumen openings 142 and 152 
by bonding one or more elastic sheets or tubes around those openings. The 
elastic sheets may be formed from any elastic material, such as 
polyurethane, silicone, rubber, or latex-based materials and bonded to 
second layer 130 by applying sufficient heat and/or adhesive (preferred) 
to a portion of the sheet to cause that portion to partially melt. When 
the melted portion cools, it forms a fluid, or hemodynamic, seal about the 
opening so that balloons 144 and 154, which are formed inside the seal, 
can be inflated and deflated with a fluid, such as a gas or liquid. 
Alternatively, the elastic sheet may be bonded to a surface of second 
layer 130 by applying an adhesive material to a portion of the sheet 
bonded to second layer 130. This works particularly well when the elastic 
sheet is a silicone, rubber, or latex material. As already described 
above, the elastic sheet can have any shape, including any preformed 
shape, as long as it completely covers integrated lumen openings 142 and 
152 and has borders 145 and 155 sufficient for bonding. 
In steps 440 and 450, the primary and secondary lumens are formed by 
removing the primary and secondary mandrels, respectively. For example, in 
step 450, primary lumen 120 is formed by removing primary mandrel 50 from 
inside first layer 110. Also, in step 440, secondary lumens 140 and 150 
are formed by removing secondary mandrels 132 and 133 from second layer 
130. Steps 440 and 450 may be performed in any order and before, during, 
or after balloons 144 and 154 are formed in bonding step 445. However, it 
is preferable that at least step 445 is performed before step 450 so that 
primary mandrel 50 provides structural support during step 445. 
In step 460, one or more auxiliary apparatus may be inserted in the 
secondary lumen. Examples of auxiliary apparatus include endoscopic snare 
instruments (as shown in FIGS. 3A and 3B) and fiber optic bundles. In the 
case of a snare instrument, inserting step 460 may involve inserting the 
instrument so that snare loop 354 of instrument 350 is near the secondary 
lumen opening 356. When snare instrument 350 includes a snare sheath, 
method 400 may further include inserting the sheath in secondary lumen 340 
before or during inserting step 360, in which snare instrument 350 is 
itself inserted so that the snare loop remains fully open when placed in 
the primary lumen. The snare loop may be preformed before being inserted. 
When the auxiliary apparatus includes a fiber optic bundle that has a tip 
portion, the tip portion may be positioned near a secondary lumen opening 
(see FIG. 3A). 
It will be understood that the foregoing is only illustrative of the 
principles of the invention, and that various modifications can be made by 
those skilled in the art without departing from the scope and spirit of 
the invention. For example, the order of some steps in the procedures that 
have been described are not critical and can be changed if desired.