Proximal end fitting with an improved seal for use in a catheter guidewire assembly

The invention comprises a proximal end fitting for use within a guidewire assembly wherein the proximal end fitting comprises an elongated radially compressible tube. When in use, the tube is compressed against the O-ring seal in the fitting to better facilitate the seal between the O-ring and the guidewire and thereby better control blood reflux.

DESCRIPTION 
1. Technical Field 
This invention is in the general field of surgical instruments and relates 
specifically to proximal end fittings. These fittings are used with 
catheter guidewire assemblies in cardiovascular and endovascular 
procedures to facilitate the placement of catheters within the vasculature 
of patients. 
2. Background 
The general procedure for placing catheters within vessels is to track a 
guidewire through the vessel to the desired position and advance the 
catheter over the guidewire. Guidewires are required because the catheters 
themselves do not have sufficient column strength or torqueability to be 
able to be tracked or steered through the vessel. See, for instance, U.S. 
Pat. No. 4,884,579. 
Normally, blood pressure within a catheter guidewire assembly is controlled 
by a compression ring seal made out of rubber or rubber-like material. 
This method restricts wire movement when the seal is too tight and is 
inefficient when the seal is too loose. The purpose of the present 
invention, therefore is to control blood reflux into the catheter while 
the catheter is being positioned at a predetermined vessel site without 
impeding guidewire movement. When the device is used in conjunction with a 
compression ring seal, the guidewire can be captured and higher pressure 
can be controlled. When the compression ring seal is released, the 
guidewire movement is unrestricted. 
DISCLOSURE OF THE INVENTION 
The invention comprises a proximal end fitting for use within a guidewire 
assembly. An elongated, radially compressible plastic tube is connected 
through the proximal end fitting such that when a catheter is being 
positioned at an arterial site, blood reflux will be controlled. 
More specifically, the invention comprises an improvement to a conventional 
proximal end fitting for a guidewire assembly. The conventional fitting 
comprises a tubular body having a proximal end and a distal end and a 
lumen between the ends through which a guidewire extends. The distal end 
contains a fitting for sealingly receiving the proximal end of the 
catheter. A compressible O-ring is positioned within the lumen, and a 
coaxially movable means fits into the proximal end of the body such that 
when it is moved into place, it compresses the O-ring. The O-ring thus 
forms a seal about the guidewire. 
The improvement of the present invention comprises an elongated radially 
compressible plastic tube extending distally from the coaxially movable 
means, coaxially about the guidewire through the O-ring and a substantial 
portion of the lumen. This tube serves to better facilitate the seal 
between the O-ring and the guidewire.

MODES FOR CARRYING OUT THE INVENTION 
FIGS. 1 and 2 illustrate the preferred embodiment of the proximal end 
fitting of the invention. 
FIG. 1 depicts the entire catheter guidewire assembly. The assembly 
includes the guidewire 11, the catheter 12 and the proximal end fitting 
13. As shown in FIG. 1, the guidewire is a flexible torqueable wire having 
an overall length of between about 70-300 cm between its proximal and 
distal ends (14 and 15, respectively) and a maximum outer diameter of 
between about 0.2 mm and 1.0 mm. Distal portion 15 of guidewire 11 is 
fully or partially encased in a soft flexible sleeve. 
As further shown in FIG. 1, the catheter includes an elongated tubular 
member 19 having proximal and distal ends 20 and 21, respectively. The 
tubular member is preferably between about 50-300 cm in length and 
typically between about 100-200 cm in length. Catheter 12 includes a 
relatively stiff proximal segment 22 and a relatively more flexible distal 
segment 23 with a segment 24 between the proximal and distal ends composed 
of the overlapping coaxial tubes of the proximal and distal segments. 
Proximal end 27 of catheter 12 is sealingly attached to the distal portion 
15 of proximal end fitting 13. As shown in FIG. 2, the proximal end 
fitting comprises a tubular body 28 having a proximal and distal end 29 
and 30, respectively, and a lumen 31 extending between the two ends. The 
lumen has an overall length of between about 2 and 10 cm, more preferably 
between about 4 and 6 cm and most preferably about 5 cm. The inner 
diameter of the lumen is between about 2.0 and 4.0 mm, more preferably 
between about 2.20 and 2.25 mm and most preferably about 2.25 mm. The 
outer diameter of the lumen is between about 4 and 8 mm, more preferably 
between about 5 and 6 mm and most preferably 5.5 mm. 
A side port 32 may be included in proximal end fitting 13 in order to allow 
for the introduction of fluid material into the catheter lumen 33. Such 
materials include radio-opaque agents for viewing blood vessel anatomy and 
blood flow characteristics in the target region; vaso-occlusive agents, 
such as suspensions of collagen fibers which can be used to produce 
small-artery vaso-occlusion in the tissue region supplied by the target 
vessel; and pharmacological agents, such as antitumor drugs which are 
effective against identified disease states at the target site. 
Further embodiments of the above described catheter guidewire assembly are 
described in U.S. Pat. No. 4,955,862 which is herein incorporated by 
reference in its entirety. 
Proximal end fitting 13 of the present invention further comprises an 
axially movable means that can be received within the proximal end 29 of 
the tubular body 28. An elongated radially compressible tube 37 extends 
distally from the axially movable means coaxially about guidewire 11 
through O-ring 38 to facilitate the seal between the guidewire and the 
O-ring. The O-ring may be positioned anywhere within the proximal end of 
the lumen proximal to the side port such that when the O-ring is 
compressed a seal will be created about the guidewire to avoid reflux of 
fluid. In the preferred embodiment depicted in FIGS. 1 and 2, the O-ring 
is positioned at the distal end of the threaded portion of proximal end 
fitting 13 such that when the axially movable means 10 is threadedly 
connected to the proximal end fitting, compression of O-ring 38 results. 
In the preferred embodiment depicted in FIGS. 1 and 2, the axially movable 
means comprises an end cap 36. The end cap comprises a central shaft 39 
through which lumen compressible tube 37 is attached. The method of 
construction of the compressible tube is described below. A first collar 
40 concentrically surrounds central tubular shaft 39. This collar has a 
smooth outer surface and a threaded inner surface such that when end cap 
36 is axially rotated, the threads on the collar connect with threads on 
the outer surface of the proximal end of tubular body 28. 
A second collar 41 concentrically surrounds first collar 40 and central 
tubular shaft 39. This collar has a smooth inner surface and an outer 
surface with ribs 42. These ribs allow for ease in gripping the end cap so 
that the end cap can be rotated and threadedly attached to tubular body 
36. 
RADIALLY COMPRESSIBLE TUBE CONSTRUCTION 
A wire mandrel with an outside diameter of 0.38 mm is placed inside a 
polypropylene tube with an inside diameter of 0.46 mm and an outside 
diameter of 0.76 mm that is approximately 12 cm long to form a wire 
mandrel and polypropylene tube assembly. The wire mandrel and 
polypropylene tube assembly is then inserted into a heat-shrink 
polyethylene tube expanded to about 2.54 mm inside diameter with a wall 
thickness of about 0.051 mm. The entire assembly is heated to the melting 
point (approximately 200.degree. C.) of the polypropylene tubing. The 
heat-shrink tube will cause the polypropylene to collapse over the mandrel 
and have a precise inside diameter. The mandrel is removed when the 
material is cooled. In the preferred embodiment of the present invention, 
the polymer tube is trimmed to about 10 cm in length such that the tube 
coaxially surrounds the guidewire to a point just beyond where proximal 
end 27 of catheter 12 is attached to distal end 15 of proximal end fitting 
13. The polymer tube may be trimmed to any convenient length such that it 
aids in sealingly connecting the O-ring and the guidewire. 
TEST CHARACTERISTICS 
A Tracker 25 catheter (Target Therapeutics, Inc., San Jose, Calif.) 
equipped with a 0.36 mm Seeker guidewire (Target Therapeutics, Inc.) and 
the proximal end fitting of the invention is filled with 30 percent 
contrast medium. The guidewire is positioned so that the wire is about 10 
cm from the tip of the catheter. The tip of the catheter is sealed using a 
hemostat. The compressible plastic tube (37 in the drawings) is positioned 
over the wire in such a manner that part of the tube can be captured by 
the O-ring seal of the fitting. An indeflator filled with contrast medium 
is attached to the side port of the fitting. The O-ring seal of the 
fitting is tightened slightly to capture the compressible tube. The 
guidewire is checked for movement. Air is vented from the system. Pressure 
is then applied on the indeflator for one minute at 10 psi. The end of the 
compressible tube was checked for leakage. The applied pressure was 
increased at 10 psi increments up to 120 psi. Ten samples were tested. The 
results are shown in FIG. 4. (In FIG. 4, "n.1." means "no leakage.") 
Using the same assembly described, with no pressure applied to the system, 
the ring seal was compressed until the guidewire was captured. After five 
minutes, the ring seal was released and the guidewire checked for 
movement. The procedure was repeated ten times. Ten samples were tested. 
Wire movement was not effected under any conditions tested. 
Modifications of the above-described modes for carrying out the invention 
that are obvious to persons of skill in the mechanical, surgical 
instrument, and catheter/guidewire arts or related fields are intended to 
be within the scope of the following claims.