Perfusion dilatation catheter and method of manufacture

Perfusion dilatation catheter and method of manufacturing the same. The catheter has an elongated flexible shaft with an inflatable balloon mounted near the distal end of the shaft. A first lumen in the shaft communicates with the balloon for inflating and deflating the balloon. A second lumen extends between the proximal and distal ends of the shaft and is adapted to receive a guide wire. Openings formed in the side wall of the shaft on the proximal and distal sides of the balloon communicate with the second lumen to provide a path for blood to flow past the balloon when it is inflated.

This invention pertains generally to medical appliances, and more 
particularly to a perfusion dilatation catheter and method of 
manufacturing the same for use in coronary angioplasty. 
In percutaneous transluminal coronary angioplasty, catheters are inserted 
into the cardiovascular system through the femoral or brachial arteries 
under local anesthesia. A preshaped guiding catheter is positioned in the 
coronary artery, and a dilatation catheter having a distensible balloon 
portion is advanced through this catheter into the branches of the 
coronary artery until the balloon portion traverses or crosses a stenotic 
lesion. The balloon portion is then inflated with a fluid to compress the 
atherosclerosis in a direction generally perpendicular to the wall of the 
artery, thereby dilating the lumen of the artery. 
A guide wire is often employed to facilitate placement of the dilatation 
catheter beyond the distal end of the guiding catheter. The guide wire is 
inserted through the guiding catheter, and the dilatation catheter is 
advanced along the guide wire to the desired position in the vascular 
system. 
Since the inflated balloon occludes the flow of blood in the artery or 
other vessel being treated, the balloon can only be inflated for a limited 
time, typically on the order of 15-60 seconds. A longer inflation time 
would be desirable since it would increase the probability that the vessel 
would remain open after the catheter is removed. With catheters heretofore 
provided, however, the only way to prolong the inflation is to use 
repeated short inflations. 
It is in general an object of the invention to provide a new and improved 
dilatation catheter and method of manufacturing the same. 
Another object of the invention is to provide a dilatation catheter and 
method of the above character wherein the catheter provides blood flow 
around the inflated balloon and permits prolonged inflation times. 
These and other objects are achieved in accordance with the invention by 
providing a dilatation catheter having an elongated flexible shaft in 
which first and second lumens are formed. An inflatable balloon is mounted 
on the shaft toward the distal end, and the first lumen extends between 
the proximal end of the shaft and the balloon, communicating with the 
interior of the balloon through an elongated opening in the side wall of 
the shaft. The second lumen extends between the proximal and distal ends 
of the shaft, and openings in the side wall on the proximal and distal 
sides of the balloon provide blood flow past the balloon through this 
lumen.

As illustrated in the drawings, the catheter comprises an elongated 
flexible shaft 11 with an inflatable balloon 12 near the distal end of the 
shaft. Lumens 13, 14 are formed in the shaft. The two lumens are 
positioned side by side, and each has a generally semicircular 
cross-section. Lumen 13 is of smaller diameter than lumen 14, and it 
extends between the proximal end of the shaft and the balloon, 
communicating with the interior of the balloon through an elongated 
opening 16. This lumen is utilized for inflating and deflating the 
balloon. Lumen 14 extends between the proximal and distal ends of the 
shaft and is adapted to receive a guide wire. 
A small vent tube 17 is removably inserted into the catheter to provide 
communication with the interior of balloon 12. The vent tube is fabricated 
of a material such as plastic, stainless steel or another suitable metal, 
or glass, and it passes through lumen 13 and opening 16 to the interior of 
the balloon. 
Opening 14 is formed by cutting away a portion of the side wall of shaft 11 
adjacent to lumen 13 to form a channel which extends substantially the 
length of the balloon. The side wall is cut away to a depth of about 
one-third of the diameter of shaft 11. A strip 18 of radiopaque material 
such as gold is mounted on the bottom wall of lumen 13 through opening 16. 
This strip extends substantially the length of the balloon. The deflated 
balloon can be folded into the cut-away area provided by opening 16 to 
give the catheter a relatively low profile. 
A fluoroscopically visible tip marker 19 is provided near the distal end of 
the catheter. In the embodiment illustrated, this marker comprises a band 
of radiopaque material which surrounds shaft 11 and is secured in place by 
heat sealing between the shaft and the tip of the balloon. 
Lumen 13 terminates near the distal end of balloon 12, and lumen 14 has a 
generally circular cross-section in the distal tip portion of the shaft. 
The diameter of this lumen is reduced at the distal end to provide a 
closer fit with the guide wire. 
A plurality of openings 21 are formed in the side wall of shaft 11 on the 
proximal and distal sides of balloon 12. These openings communicate with 
lumen 14, and they provide a path for blood flow past the balloon when the 
balloon is inserted in the vascular system and inflated. There are 
preferably about 3 such openings on the distal side of the balloon and 5-9 
such openings on the proximal side. These openings are preferably cut in 
the form of notches, rather than drilled holes, and they have a generally 
semicircular shape when viewed from the side in a direction generally 
perpendicular to the axes of the openings. This shape of holes has been 
found to provide a better blood flow than holes drilled through the side 
wall in a radial direction. 
In FIG. 1, the catheter is illustrated in connection with a three-arm 
adapter 23. This adapter has a central port 24 which communicates with 
lumen 14, a side port 26 which communicates with lumen 13, and a side port 
27 which also communicates with lumen 13. A guide wire (not shown) and/or 
contrast media can be inserted through port 24, and a fluid can be 
introduced and discharged through port 26 to inflate and deflate the 
balloon. Vent tube 17 is inserted and removed through side port 27, and 
this port is sealed by means of a thumb screw 28 and a resilient seal (not 
shown). 
Operation and use of the catheter are as follows. The catheter is inserted 
into the body of a patient and advanced along a guide wire (not shown) to 
position balloon 12 adjacent to the lesion to be treated. Vent tube 17 is 
inserted through lumen 13 and opening 16, and the distal end portion of 
the vent tube is positioned near the distal end of the balloon. Thumb 
screw 28 is tightened to compress the seal ring and form a fluid-tight 
seal around the proximal end portion of the vent tube. The balloon is 
primed or prepared for use by introducing a pressurized fluid through port 
26 and displacing trapped air from the balloon through vent tube 17. When 
all of the air has been removed, vent tube 17 is removed, and port 27 is 
sealed closed. Thereafter, the balloon can be inflated and deflated as 
desired through port 26. While the balloon is inflated, blood can flow 
past the balloon through openings 21 and lumen 14. This permits the 
balloon to remain inflated for substantially longer than is possible with 
other dilatation catheters where the blood flow is cut off. 
The perfusion catheter is particularly suitable for use in treating 
leasions which have become segmented. These lesions have a flap, and they 
are difficult to keep open after a standard balloon has been removed. The 
perfusion catheter permits the flap to be held against the vessel wall for 
a substantially longer period of time and at a lower balloon pressure than 
with a standard balloon catheter. With a standard catheter, the balloon 
might be inflated at a pressure of about 90-100 psi for 30-50 seconds. 
With the perfusion catheter, the balloon might, for example, be inflated 
at a pressure of 60 psi for 2-15 minutes or longer. The prolonged 
treatment greatly increases the chance that the vessel will remain open 
when the catheter is removed. 
Shaft 11 and lumens 13, 14 are formed by an extrusion process. Opening 16 
is cut in the side wall of the shaft, and radiopaque marker 17 is applied 
to the bottom wall of lumen 13 beneath the opening. Balloon 12 and 
radiopaque tip marker are mounted on the shaft and affixed by heat sealing 
the end portions of the balloon to the shaft. Openings 21 are cut in the 
shaft from the side with a circular cutter. 
The invention has a number of important features and advantages. It permits 
blood to flow past the balloon when it is inflated, and this permits the 
balloon to remain inflated substantially longer than is possible with 
balloon catheters heretofore provided. The prolonged treatment increases 
the chances that the vessel will remain open after the catheter is 
removed. With the deflated balloon folded into the cut-away area, the 
catheter has a relatively low profile. 
It is apparent that a new and improved dilatation catheter and method of 
manufacturing the same have been provided. While only certain presently 
preferred embodiments have been described in detail, as will be apparent 
to those familiar with the art, certain changes and modifications can be 
made with departing from the scope of the invention as defined by the 
following claims.