Catheter for uniform distribution of therapeutic fluids

A vascular catheter for delivering a uniform flow of therapeutic fluid over a length of the catheter. The catheter is particularly suitable for delivering thrombolytic agents to a thrombus or clot in a patient's arterial system. In a preferred embodiment, the catheter has a relatively thick-walled tubular body with a central lumen for advancement over a guidewire and a plurality of fluid delivering lumens disposed within the relatively thick wall. Each of the smaller lumens has a single flow passageway to discharge therapeutic fluid to the exterior of the catheter.

BACKGROUND OF THE INVENTION 
This invention generally relates to a vascular catheter for the delivery of 
therapeutic fluids and particularly for the uniform delivery of 
thrombolytic fluids to a vascular location of a patient having a thrombus 
or clot. 
The utilization of therapeutic fluids containing tissue plasminogen 
activator (TPA), urokinase and streptokiase have shown promise in the 
treatment of thrombus or clots in a patient's arterial have been limited 
by the fact that the patient's total body is medicated in order to effect 
sites in the patient's arterial vasculature. Direct delivery of 
thrombolytic fluids to the target tissue would allow for a much more 
effective treatment procedure. However, there have been no effective 
delivery systems available. More particularly, there has not been 
available a delivery system which can deliver a uniform flow of such 
therapeutic fluids along the length of a thrombus in a patient's artery. 
The present invention satisfies that need. 
SUMMARY OF THE INVENTION 
The present invention is directed to a multilumen vascular catheter which 
provides a more uniform and thus more effective delivery of fluids 
containing drugs or therapeutic agents to a desired vasculature location. 
The vascular catheter in accordance with the present invention generally 
comprises an elongated tubular body having a relatively large inner lumen, 
with an axial opening in the distal end thereof, which is adapted to 
receive a guidewire and a plurality of relatively small lumens which 
direct fluid containing drugs, therapeutic agents and the like to the 
distal portion of the tubular body. Each of the smaller lumens has a 
single flow passageway in fluid communication therewith which extends 
through the wall of the tubular body and is open to the exterior of the 
catheter to discharge fluid therefrom. The flow passageways are spaced 
longitudinally along a length of the tubular body and have essentially 
equivalent minimum transverse cross-sections to provide a uniform fluid 
flow over said length. Preferably, the passageways are spirally arranged 
to ensure uniform flow around the periphery of the catheter. 
In a preferred embodiment the tubular body has a relatively thick walled 
cylindrical shape with the relatively large diameter lumen adapted to 
receive the guidewire, being centrally disposed. A plurality small 
diameter lumens are provided which extend longitudinally through the 
relatively thick wall of the tubular body. 
The proximal end of the catheter is provided with an adapter which directs 
fluids through one arm thereof to the small diameter lumens and one arm to 
direct a guidewire through the relatively large diameter. If desired, each 
of the small diameter lumens can be provided with separate fluid sources 
in order to more accurately deliver fluid therethrough. 
The minimum transverse cross-sectional area of the flow passages ranges 
from about 0.00005 in.sup.2 to about 0.002 in.sup.2 for fluid flows of 
about 0.1 to about 1.5 cc's per minute at lumen pressures of about 2 to 
about 5 psi. The cross-sectional areas can be varied depending upon the 
fluid flow rate desired, the viscosity and density of the fluid and the 
fluid pressure available. The number of flow passageways can number from 2 
to up to 12 or more, but generally only 4-8 are needed. The spacing 
between the passageways is preferably uniform but may vary from about 0.5 
to about 5 cm. 
Typically a guidewire is directed through a patient's arterial system to a 
location therein having a thrombus or clot which occludes or partially 
occludes the artery. The distal portion of the guidewire is advanced 
through the clot, then the vascular catheter of the invention is mounted 
onto the guidewire and advanced thereover until the distal portion of the 
catheter having the flow passageways in the wall thereof is in position 
within the thrombus. Fluid containing thrombolytic agents such as 
urokinase, streptokinase, tissue plasminogen activator (TPA) and the like 
is then directed through the small diameter lumens and the flow passageway 
associated with each of such lumens to the exterior of the catheter into 
the thrombus. The fluid flow rate is relatively low as is the pressure to 
allow the fluid to penetrate through and dissolve the clot. The flow out 
of the passageways is uniform over the length of the catheter containing 
such passageways. In this manner, a uniform thrombolysis is effected. 
After this treatment, the stenotic region can be treated by balloon 
dilatation, atherectomy and the like to provide increased blood flow 
through the region.

DETAILED DESCRIPTION OF THE DRAWINGS 
Reference is made to FIGS. 1-3 which illustrate a vascular catheter 
assembly 10 embodying features of the invention. The catheter assembly 10 
generally comprises a tubular body 11 which has a central lumen 12 adapted 
to receive a guidewire 13 and a relatively thick cylindrical wall 14 which 
has a plurality of relatively small diameter lumens 15 disposed 
longitudinally therein which are adapted to direct fluid through the flow 
passageways 16. Preferably, the small diameter lumens are equally spaced 
within the wall 14 about the central lumen 12. 
An adapter 17 is provided on the proximal end 18 of the tubular body 11. A 
first arm 20 thereof is adapted to deliver fluid from a source (not shown) 
to the small diameter lumens 15 and a second arm 21 is adapted to direct 
the guidewire 13 into the central lumen 15. A torquing knob 22 is provided 
on the proximal end of the guidewire 13 to facilitate the guidance thereof 
through the patient's vasculature. Reference is made to U.S. Pat. No. 
4,554,929; U.S. Pat. No. 4,545,390; and U.S. Pat. No. 4,721,117 for a more 
detailed description of guidewires, which are incorporated herein by 
reference. 
The distal end of the tubular body 11 generally has a tapered body 23 which 
is formed of a plastic material softer than the material from which the 
tubular body 11 is made in order to minimize trauma to the arterial lining 
during the advancement of the catheter through a patient's artery. The 
tapered body 23 blocks off the distal ends of the small diameter lumens 
15. 
The length of the vascular catheter will vary depending upon the use 
thereof. For example, for peripheral uses, lengths may be from about 70 to 
about 100 cm, whereas for coronary uses lengths may vary from about 120 to 
about 175 cm. The outer diameter of the tubular body 11 may vary from 
about 0.05 to about 0.10 inch. Typical diameters of the large diameter 
inner lumen is about 0.025 to 0.045 inch and for the small diameter lumens 
15 are about 0.005 to about 0.025 inch. The flow passageways 16 are 
preferably uniformly spaced along a length of the tubular body 11 from 
about 0.5 to 5 cm and the total length of the treating section of the 
catheter extends from about 2 to about 20 cm. 
The tubular body 11 can be made of conventional plastic materials such as 
polyethylene, polyvinylchloride and the like. Preferably, the stiffness of 
the tubular body decreases in the distal direction. Stiffness in the 
proximal portion of the tubular body is desirable from the standpoint of 
pushability but flexibility is more desirable in the distal portion in 
order to pass through the patient's tortuous vasculature. The proximal 
portion can be provided with greater stiffness by making this portion with 
higher density plastics, e.g. polyethylene, than the distal end. The 
distal tip is preferably formed of a much softer plastic to avoid trauma 
to the blood vessel lining when advancing the catheter therethrough. 
The flow passageways 16 through the wall of the tubular body can be formed 
by drilling (e.g., mechanical or laser) or by notching the exterior wall 
to expose the small diameter lumens. The flow passageways are preferably 
spiralled about the tubular body of the catheter, as shown in the 
drawings, to provide a more uniform flow surrounding the catheter. 
While the description of the invention herein has been directed to a 
catheter for the delivery of thrombolytic fluids, it should be obvious 
that other fluids can be delivered and that other treatments can be 
performed. Additionally, while only one source for treatment fluid is 
shown for the small diameter lumens, each of said lumens can be provided 
with its own source of such fluid and the flow therethrough regulated 
independently. Other modifications and improvements can be made to the 
invention without departing from the scope thereof.