Rapidly inflatable balloon catheter and method

A catheter having first and second lumens and a balloon adjacent the distal end of the catheter, with the first and second lumens extending to the interior of the balloon. Air can be purged from the catheter by introducing a purging liquid in series through the first lumen, the balloon and the second lumen. Following purging, an inflation liquid is introduced in parallel through the first and second lumens to rapidly inflate the balloon. The balloon is rapidly deflated by discharging the inflation liquid from the balloon in parallel through the first and second lumens.

BACKGROUND OF THE INVENTION 
In percutaneous transluminal angioplasty, a dilation catheter is inserted 
into an artery to dilate the artery. For this purpose, the typical 
dilation catheter has an inflatable balloon adjacent its distal end and a 
balloon inflation lumen through which the balloon is inflated and 
deflated. Inflation is accomplished by forcing an appropriate inflation 
liquid through the lumen to the balloon, and deflation is accomplished by 
withdrawing the liquid from the balloon. Inflation of the balloon dilates 
the adjacent regions of the artery to provide lower restriction to blood 
flow through the artery. 
In carrying out the dilation procedure, it is necessary to repeatedly 
inflate and deflate the balloon to repeatedly dilate the artery. During 
the time that the balloon is inflated, blood flow through the artery is 
blocked. For this reason, it is necessary that the inflation and deflation 
of the balloon be carried out as rapidly as possible. This is difficult to 
do because the balloon inflation lumen is long and of small diameter, and 
consequently, the balloon inflation lumen presents a substantial 
resistance to the flow of the inflation liquid to and from the balloon. 
One other complicating factor is that air must be purged from the balloon 
before the dilation catheter is used for its intended purpose. This can be 
accomplished, for example, by inserting a vent tube through the balloon 
inflation lumen into the balloon. A purging liquid is then introduced 
through the balloon inflation lumen, and the air within the balloon is 
vented through the vent tube. One example of such an arrangement is shown 
in Simpson et al U.S. Pat. No. 4,323,071. One problem with this procedure 
is that the insertion of the vent tube must be carefully carried out not 
to damage the ballon and may be cumbersome if the vent tube is attempted 
to be taken out to obtain a larger inflation lumen. 
SUMMARY OF THE INVENTION 
This invention provides a dilation catheter and method which eliminate the 
need for vent tube insertion. In addition, with this invention, the 
balloon of the dilation catheter can be rapidly inflated and deflated so 
that useful dilation pressure can be applied for the maximum length of 
time. 
This invention provides a catheter assembly adapted to dilate a tubular 
body member, such as an artery, which comprises a catheter having distal 
and proximal ends, means for defining at least first and second lumens, 
and a balloon adjacent the distal end with the first and second lumens 
extending to the interior of the balloon. The catheter assembly preferably 
also includes a through lumen that may be used, for example, for a guide 
wire, monitoring of pressure distally of the balloon, and the infusion of 
a contrast medium or medication. 
To purge air from the balloon, the first and second lumens are used in 
series. More specifically, a purging liquid is passed in series through 
the first lumen, the balloon and the second lumen to purge air from the 
balloon out through the second lumen. Thus, no insertable vent tube is 
required. 
Thereafter, the first and second lumens are used in parallel for inflating 
and/or deflating of the balloon. Preferably, the first and second lumens 
are used in parallel for both inflation and deflation of the balloon. This 
is accomplished by passing an inflation liquid through both of the first 
and second lumens to inflate the balloon and discharging the inflation 
liquid from the balloon through both of the first and second lumens. 
The purging of air from the balloon is preferably carried out with the 
balloon pointed downwardly. Following the purging cycle, the catheter can 
be inserted into the vascular system of the patient to dilate a region of 
the vascular system. 
The catheter assembly includes means for introducing the purging liquid, 
means for introducing the inflation liquid and means for discharging the 
inflation liquid from the balloon. Although these means can be of various 
different constructions, the catheter preferably includes a connector 
located proximally of the balloon, and the means for introducing the 
purging liquid is removably coupled to the connector. This permits such 
means to be removed from the connector and replaced with the means for 
introducing the inflation liquid. 
In a preferred construction, the means for introducing the purging liquid 
includes a purge fitting having a first leg communicating with the first 
lumen at the connector and a second leg receiving the second lumen. The 
first leg is communicable with a source of the purging liquid. The purge 
fitting can be removed and replaced with, for example, a syringe which can 
introduce the inflation liquid and enable discharge of the inflation 
liquid from the balloon. 
Another feature of this invention is that the distal tip of the catheter 
through which the through lumen extends is flexible, of small 
cross-sectional area and devoid of sharp shoulders. This facilitates 
insertion and movement of the catheter into and through the vascular 
system and minimizes the likelihood of damage to the tissue. This feature 
can be used with advantage with or without the balloon purging and 
inflation and deflation features of this invention. 
This feature can be embodied, for example, in a catheter which includes a 
catheter body and an extension tube coupled to the catheter body in 
communication with the through lumen in the catheter body and having a 
passage therethrough which forms an extension of the through lumen. The 
balloon has an inflatable portion in communication with a balloon 
inflation lumen, attachment portions on opposite sides of the inflatable 
portion sealed to the catheter body and the tube, respectively, and an at 
least somewhat flexible tubular distal portion extending distally beyond 
the tube to form an extension of the through lumen and to define a distal 
end of the catheter. The tubular distal portion is preferably of smaller 
cross-sectional area than the tube and is smoothly blended into such 
smaller cross-sectional area to avoid the presence of any sharp or abrupt 
corners shoulders. Preferably, the tubular distal portion is more flexible 
than regions of the catheter body adjacent the tube. 
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 assembly 11 which includes a catheter 13, a purge 
fitting 15 and a Y-fitting 17, both of which are coupled to the catheter. 
The catheter assembly also includes a conventional guidewire introducer 19 
partially within the proximal end of the Y-fitting 17. 
The catheter 13 includes a catheter body 21, a balloon 23, a vent-inflation 
extension 25, a through lumen extension 27 and connectors 29 and 31 which 
define the proximal end of the catheter 13 coupled to the proximal ends of 
the extensions 25 and 27, respectively. The catheter 13 also includes a 
sleeve 33 for encasing portions of the extensions 25 and 27 and the 
catheter body 21. 
The catheter body 21 may be in the form of an elongated, flexible, 
cylindrical tube (FIG. 4) of a suitable plastic material having suitable 
internal partitions defining portions of balloon lumens 35 and 37 and a 
through lumen 39. The balloon lumens 35 and 37 extend from the proximal 
end of the catheter body 21 to the interior of the balloon 23 at the 
distal end of the catheter body 21 as shown in FIGS. 5 and 6. The balloon 
lumens 35 and 37 are extended proximally of the catheter body 21 by the 
extension 25 which comprises an outer tube 41 (FIG. 3) and inner tubes 43 
and 45 extending through parallel passages 47 of the outer tube. The outer 
tube 41 extends within the sleeve 33, and the inner tubes 43 and 45 are 
received within the lumens 35 and 37 of the catheter body 21 and suitably 
retained therein. Similarly, the connector 29 is suitably mounted on the 
outer tube 41. As shown in FIG. 2, the inner tube 43 terminates at an 
inner face 49 of the connector 29, and the inner tube 45 extends 
completely through a passage 51 in the connector and completely through 
the connector. 
The through lumen 39 is extended proximally by the extension 27 which 
extends into the sleeve 33 and a proximal portion of the through lumen 39 
in the catheter body 21. The sleeve 33 surrounds the extensions 25 and 27 
and the catheter body 21 in a known manner. The Y-fitting 17, which is 
releasably coupled to the connector 31, has a leg 53 which is open to the 
through lumen 39 to permit the obtaining of blood pressure or blood 
samples, the infusion of medication, etc. The Y-fitting 17 has a second 
leg 55 in which the guidewire introducer 19 is mounted to permit insertion 
of a guidewire (not shown) through the through lumen 39. 
The through lumen 39 is extended distally by a tube 57 and a tubular distal 
portion 59 of the balloon 23 as shown by way of example in FIG. 5. 
Although various constructions are possible, the tube 57 is received 
within a distal end portion of the lumen 39 of the catheter body 21 and is 
retained therein in any suitable manner, such as by an adhesive or heat 
sealing. The tube 57 is elongated and flexible and may be constructed of a 
suitable plastic material. The tube 57 has an axial passage 61 extending 
through it which forms an extension of the through lumen 39. Preferably, 
radiopaque bands 63 are suitably retained on the tube 57 within the 
balloon 23 to permit the physician to ascertain the location of the 
balloon when it is in the patient's vascular system. 
The balloon 23, which is adjacent the distal end of the catheter body 21, 
has an inflatable portion 65, attachment portions 67 and 69 on opposite 
sides of the inflatable portion 65 which are sealed to the catheter body 
21 and the tube 57, respectively, and the tubular distal portion 59. The 
balloon 23, which is constructed of a suitable plastic, such as 
polyethylene, may have the attachment portions 67 and 69 shrunk onto the 
catheter body 21 and the tube 57. By tightly shrinking the attachment 
portion 67 onto the catheter body 21, the catheter body may be compressed 
somewhat radially inwardly to form an inwardly extending annular shoulder 
71 which tends to make the periphery of the attachment portion 67 
approximately coextensive with the periphery of the catheter body 21. This 
minimizes changes in cross section along the length of the catheter 13. 
The tube 57 extends completely through the inflatable portion 65, which is 
of larger cross-sectional area than the tube and the catheter body 21. 
However, the tube 57 does not project completely through the balloon 23 in 
that the tubular distal portion 59 extends distally of the tube 57 to form 
the distal end 73 of the catheter 13. The tubular distal portion 59 is of 
smaller cross section than the tube 57 and is smoothly and gradually 
blended into such smaller cross section by an inclined annular wall 
section 75 which extends distally from the distal end of the tube 57. The 
tubular distal portion 59 terminates distally in a cylindrical section 77 
which defines a distal port 79 at the distal end 73. 
The balloon 23 is integrally constructed, and the tubular distal portion 59 
is resiliently flexible. Preferably, the tubular distal portion 59 is more 
flexible than regions of the catheter body 21 adjacent the tube 57. 
First means is provided for introducing a purging liquid to the lumen 35. 
Although this means can take different forms, in the embodiment 
illustrated, it includes the purge fitting 15 and a vent tube 81 carried 
by the purge fitting. As shown in FIG. 2, the purge fitting 15 is 
removably coupled to the connector 29 in a conventional manner. The purge 
fitting 15 is in the form of a Y-fitting having a first leg 83 in 
communication with the lumen 35 through a common passage 85 and a passage 
51 of the connector 29. The inner tube 45, which defines the proximal 
extension of the lumen 37, extends completely through the passage 51 of 
the connector 29 and into the passage 85 of a second leg 87 of the purge 
fitting 15. The vent tube 81 is slidably received within the passage of 
the second leg 87, and the vent tube slidably receives the proximal end of 
the inner tube 45 as shown in FIG. 2. The vent tube 81 terminates in a 
vent opening 88. 
With the purge fitting 15 coupled to the connector 29, the catheter 
assembly 11 can be used to purge air from the balloon 23 as shown in FIG. 
7. The first leg 83 is coupled to a source of the purging liquid (not 
shown), and the distal end of the balloon is pointed downwardly. The 
purging liquid is then passed in series through the first leg 83, the 
passages 85 and 51, the lumen 35, the inflatable portion 65 of the balloon 
23, the lumen 37 and the vent tube 81. The passing of the purging liquid 
in series through the lumens 35 and 37 forces the air in the balloon out 
through the lumen 37 and the vent tube 81 to the atmosphere. The purging 
liquid is passed in series through the lumens 35 and 37 in this fashion at 
least until the purging liquid emerges from the vent opening 88. At this 
time, it is known that all of the air has been purged from the balloon 23. 
Means is also provided for introducing an inflation liquid to the balloon 
23 and for discharging the inflation liquid from the balloon. Although 
this means can take different forms, in the embodiment illustrated, it 
includes a syringe 89 (FIG. 8) for accomplishing both of these purposes. 
More specifically, the purge fitting 15 is removed from the connector 29, 
and the syringe 89 is attached to the proximal end of the connector. The 
vent tube 81 can be easily removed with the purge fitting 15 by pulling it 
off the proximal end of the inner tube 45. The syringe 89 includes the 
usual barrel 91 and plunger 93 which is movable to the right (as viewed in 
FIG. 8) on a discharge stroke and to the left (as viewed in FIG. 8) in a 
suction stroke. 
With the syringe 89 charged with inflation liquid, the plunger 93 on the 
discharge stroke introduces an inflation liquid in parallel through both 
of the lumens 35 and 37 to inflate the balloon as shown in dashed lines in 
FIG. 8. More specifically, the inflation liquid from the barrel 91 is 
forced through the passage 51 to the lumen 35 and forced directly from the 
barrel into the inner tube 45. Similarly, by moving the plunger 93 on the 
suction stroke, the inflation liquid is discharged from the balloon 23 in 
parallel through both of the lumens 35 and 37 to deflate the balloon and 
move the inflation liquid back into the barrel 91. Because both of the 
lumens 35 and 37 are used in parallel to inflate and deflate the balloon 
23, inflation and deflation of the balloon takes place very rapidly. 
In use of the catheter assembly 11, air is first purged from the balloon 23 
as described above. Next, the catheter is inserted into the vascular 
system of the patient using known techniques to place the balloon 23 in 
the region of the vascular system, such as an appropriate artery, which is 
to be dilated. After the purge fitting 15 has been replaced with the 
syringe 89, the balloon 23 is inflated as described above to dilate the 
desired region of the vascular system and then deflated to discontinue 
dilation. Inflation and deflation of the balloon 23 are carried out 
rapidly. The dilation procedure may be carried out repeatedly within the 
artery before the catheter is removed from the patient's vascular system. 
The purging liquid and the inflation liquid may be the same liquid and may 
be any of a variety of known solutions, such as a mixture of Renographen 
and saline. 
During the insertion of the catheter 13, the tubular distal portion 59, 
being of small diameter, passes through the artery wth relative ease. The 
inclined wall section 75 provides essentially no shoulder that could cause 
damage to the tissue. In addition, the flexible nature of the tubular 
distal portion 59 further minimizes likelihood of injury to the tissue. 
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.