Steerable light diffusing catheter

A steerable catheter is disclosed which can treat luminal surfaces such as those occurring in the vascular tree, pulmonary tree, gastrointestinal tract, urological organs, etc. with Photodynamic Therapy (PDT) or other optical diffusing treatments. The catheter, which may include an inflatable balloon portion, has a light diffusing tip which can be deflected allowing the catheter to be steered precisely. The light diffusing tip on the steerable catheter is able to gain access to and enter virtually any sub-branch of the luminal system being treated. Since this catheter does not require a guidewire lumen for insertion, the profile is reduced. A low profile device allows treatment light to be delivered to the walls of the most distal, small diameter lumen.

BACKGROUND OF INVENTION 
1. Field of the Invention 
This invention relates to a device for delivering light to a target 
situated beneath the skin of a patent for the diagnosis and/or treatment 
of a medical disease. 
2. Reference to a Copending Patent Application 
Reference is made to copending U.S. patent application Ser. No. 08/039,978 
filed Mar. 30, 1993 and still pending, entitled "Transluminal Hyperthermia 
Catheter and Method for Use", having one inventor (Hugh L. Narciso, Jr.) 
in common with the present application. 
3. Prior Art 
Photodynamic Therapy (PDT) has been shown to be an effective method for 
treating tumors. PDT has also been proposed for the treatment of 
cardiovascular disease. Recently, the utility of PDT for the treatment of 
Benign Prostatic Hypertrophy (BPH) has been demonstrated. Delivery of 
light from a source (i.e. a laser) to the treatment site has been 
accomplished through the use of single fiber delivery systems with special 
light diffusing tips. As the field of PDT matures, new light delivery 
systems will be needed to treat specific sites. One such need is the 
ability to treat a small diameter lumen with a very flexible light 
diffusing catheter. 
Delivery systems for PDT are well known in the art. Some examples include a 
single fiber cylindrical diffuser (Doiron, et al, U.S. Pat. No. 
5,196,005), a spherical diffuser (McCaughan U.S. Pat. No. 4,693,556), a 
microlensing system (Narciso Jr., et al, U.S. Pat. No. 5,231,684), and an 
over-the-wire cylindrical diffusing multifiber optic catheter (Narciso 
Jr., U.S. Pat. 5,169,395), etc. While these systems have their uses in 
delivering diffuse light, they are generally not suitable for very small 
luminal applications. 
A light diffusing catheter for use in the vascular tree is described by 
Narciso in U.S. Pat. No. 5,169,395. This device, which is designed to 
deliver therapeutic levels of light to a treatment site within the body is 
introduced into the body percutaneously and advanced to the target site 
via a guidewire. The guidewire acts as track to lead the catheter, 
permitting advancement only where the guidewire directs it. With a 
dedicated guidewire lumen, this catheter has a larger profile than is 
desirable for advancement into very small lumens. If an alternate guiding 
and steering method (to the guidewire method) can be employed, the overall 
catheter diameter can be substantially reduced thus allowing its use in 
small diameter tubular tissue such as blood vessels, small diameter lumen 
of the pulmonary tree, gastrointestinal tract, urological tract, and so 
forth. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to provide a steerable light 
diffusing catheter with a tip that can be deflected during advancement of 
the catheter through the lumen of a tubular tissue. 
It is a further object of the present invention to provide a light 
diffusing catheter wherein the tip can be deflected by extracorporeal 
means. 
It is a further object of the present invention to provide a low profile 
light diffusing catheter which is can gain access to, and entry into, 
small diameter tubular tissue. 
It is a further object of the present invention to provide a light 
diffusing catheter which is flexible. 
It is a further object of the present invention to provide a light 
diffusing device which is easily constructed at low cost. 
It is yet a further object of the present invention to provide a method in 
which said catheter may be used for both diagnostic and therapeutic 
applications. 
The present invention solves the problems associated with the prior art 
light delivery catheters. Other objects as well as the scope and 
applicability of the present invention will become apparent to one skilled 
in the art from the following detailed description of the invention taken 
in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The Steerable Light Diffusing (SLID) catheter of the present invention is 
useful for delivering light during a medical treatment such as 
Photodynamic Therapy, Photochemical Therapy, Photoablation Therapy, 
Photothermal Therapy, Light Induced Hyperthermia, Light Induced 
Photocoagulation, Tissue Welding, Light Surgery, Photodynamic Dosimetry, 
or Photo-Fluorescence Dosimetry. The SLID catheter of the present 
invention is also useful for fluorescence detection of abnormal cells and 
for diagnosis. The SLID catheter of the present invention overcomes the 
problems of steerability, flexibility, and large profile to reach small 
diameter lumen which cannot be accessed with prior art devices. 
FIG. 1 shows a preferred embodiment of the Steerable Light Diffusing (SLID) 
catheter. The SLID catheter is generally indicated at the numeral 10. A 
fiber optic connector (11) is in optical communication with a light source 
(not shown). The light from the light source is delivered to a single 
fiber optic or bundle of optical fibers enclosed within the catheter 
sheath (12). The internal components of the distal catheter are separated 
at the Y-adapter (13) into the fiber optic port (14) and the tip 
deflection arm (15). Along the length of the tip deflection arm (15) is a 
spring loaded tip deflection controller (16). The tip deflection 
controller (16) can be placed in any one of a series of slots which cause 
the tip to deflect a predetermined angle (i.e. 5, 15, 30, 45 degrees) or 
it may be infinitely adjustable and operable as a joystick. The deflecting 
tip wire, deflecting tip wire lumen, and the fiber optic (not shown in 
FIG. 1) are contained within the opaque catheter body (17) which is welded 
to an optically clear light diffuser tip (18) which tip (18) is terminated 
in a rounded cap (19). The materials used for the diffusing tip (18), the 
catheter body (17) and the catheter sheath (12) can be any suitable 
biocompatible plastic which has the optical and thermal properties 
required for this device to be operable such as Teflon.RTM., polyester, 
polyurethane, polyethylene, polyethylene terephthalate, and so forth, or 
any sensible combination thereof. 
FIGS. 2a and 2b illustrate longitudinal cross-sectional views of the distal 
end (20) of the SLID catheter (10) tip which includes from (FIG. 1) the 
rounded cap (19), and the diffuser tip (18). The fiber optic core and 
cladding (21) surrounded by a fiber optic buffer (25), delivers light 
energy from the light source (not shown) to the optical diffusing material 
(22). The optical diffusing material (22) is made from any optically clear 
flexible polymer (27) such as silicone or with optical scattering centers 
(28) such as alumina, titanium oxide, diamond dust, or calcium carbonate 
embedded therein. By varying the concentration of scattering centers (28) 
in the optically clear polymer (27) from lowest at the fiber optic 
(21)/diffusing material (22) interface to greatest at the rounded cap 
(19), either discretely or continuously, the light output distribution 
from the diffuser tip (18) can be made uniform both radially and axially. 
Embedded within the optical diffusing material (22) is a deflecting wire 
(23). The deflecting wire (23) is anchored within the rounded tip (19) 
distally and is introduced into the optical diffusing material (22) by 
means of the dedicated deflecting tip lumen (24). The deflecting wire (23) 
can be fabricated from any of a large number of metals which have the 
tensile strength and memory to deflect and return to its original position 
such as NITINOL, stainless steel, or tantalum. 
FIG. 2c is a cross-sectional view of the light diffusing tip illustrating 
the relief (26) cut into the outer tubing of the tip (18) at 180 degrees 
of rotation from the deflecting wire (23) to facilitate the deflection of 
the tip (18). 
FIG. 3 is a second preferred embodiment of the deflecting tip catheter 
generally shown at 30. The fiber optic connector (11) receives light 
energy from a light source, which light source is connected to the fiber 
optic tip by means of the fiber optic connector (11) (not shown) and 
transmits that light energy along the fiber optic contained within the 
catheter sheath (12). The fiber optic (21) is contained within the length 
of the catheter from the fiber optic connector (11) to the distal portion 
of the catheter body (17). The opaque catheter body (17) is welded to the 
optically clear diffuser tip (18) which terminates in the rounded cap 
(19). Between the catheter sheath (12) and the catheter body (17) is a 
torquing device (31) which is used to translate the rotation of the 
catheter to the rounded tip (19) from the portion of the catheter which is 
not introduced into the body. 
FIGS. 4a and 4b are cross sectional views of the catheter tip shown in FIG. 
3. The catheter body (17) is welded to the optically clear diffuser tip 
(18) which terminates in the rounded tip (19). The diffuser tip (18) is 
fabricated from a material which has memory to return the diffuser tip to 
a curved position in the most relaxed state. This is accomplished through 
the use of a plastic material with memory or the incorporation of a wire 
or spring within the wall of the diffuser tip (18) such as that used in 
catheter guidewires. Since wire is reflective and not transmissive to 
light, if wire is used, the catheter diffuser tip (18) must be extended to 
allow the deflecting portion of the catheter to extend beyond the light 
diffusing portion of the tip. The fiber optic (21) surrounded by a fiber 
optic buffer (25) is fixed concentrically in the lumen created by the 
catheter body (17) by a spacer (41). 
FIG. 5 is a third preferred embodiment of the SLID catheter generally 
indicated at 50. The fiber optic (21), catheter sheath (12), fiber optic 
port (14), tip deflection arm (15), and the tip deflection controller (16) 
have the same function and arrangement as described in FIG. 1. The 
Y-adapter (13) is replaced with a three arm adapter (51) which 
incorporates a balloon inflation/deflation port (52). The balloon 
inflation/deflation port (52) allows the addition of a fluid through an 
inflation/deflation channel (not shown in this figure) created within the 
external sheath (53) to the balloon (54) which terminates in the rounded 
cap (19). Distal and proximal to the balloon are marker bands (55) for 
visualization under X-ray fluoroscopy. 
FIGS. 6a, 6b and 6c are cross sectional views of the catheter tip shown in 
FIG. 5. The fiber optic core and cladding (21) is surrounded by a fiber 
optic buffer which in turn is surrounded by the optical scattering mixture 
(22) which in turn is surrounded by the catheter body (17) which in turn 
is surrounded by the inflation/deflation channel (62) which in turn is 
surrounded by the external sheath (53). Between the catheter body (17) and 
the fiber optic buffer is the dedicated deflecting tip lumen (24) which 
surrounds the deflecting wire (23). 
The internal construction is identical to that shown in FIG. 2 with the 
addition of the external sheath (53) which creates the inflation/deflation 
channel (61). The inflation/deflation channel delivers the inflation fluid 
(62) to the balloon (54) and thus inflates the balloon (62). On each side 
of the balloon (62) is placed a marker band (55) for visualization under 
X-ray fluoroscopy. 
The diameter of the catheter without the balloon can be made as small as 
0.028"based on an optical fiber with a 200 micron core or smaller if a 
smaller core optical fiber (i.e. 50-100 microns in diameter) is employed. 
With the addition of the balloon, the catheter can be used to treat 
lesions in vessel with a diameter less than one millimeter. 
The above is a detailed description of three particular embodiments of the 
invention. It is recognized that departures from the disclosed embodiments 
may be within the scope of this invention and that obvious modifications 
will occur to a person skilled in the art. The full scope of the invention 
is set out in the claims that follow and their equivalents. Accordingly, 
the claims and specification should not be construed to unduly narrow the 
full scope of protection to which the invention is entitled.