Patent Application
20060270981
n/a
n/a
The present invention relates to a medical device, and more particularly to a coolant injection tube for a thermal treatment medical device.
Medical devices are known for thermally treating tissue on the exterior and the interior of the body. One category of such devices is the minimally-invasive, catheter-based device that is introduced into the vasculature. One feature of these devices is means by which the device is positioned at the treatment site. For example, some devices are actively steered through the vasculature using a steering or deflection mechanism, such as a pull-wire; whereas other devices are introduced over a wire that has already been guided to a selected location, wherein the wire acts as a guide that leads the device to the treatment site. Although a device can be configured so that the guiding wire is substantially external to the device, most known devices include a central longitudinal lumen that receives the wire.
Another feature of the minimally-invasive, catheter-based, thermal-treatment device is the thermal treatment mechanism. One category of devices thermally treats tissue by cooling it, wherein cooling is effected by injecting coolant into a portion of the device, such as a distal device portion that has advantageous thermal transfer properties, and placing the distal device portion near or in contact with the tissue. The distal end portion can have a fixed diameter that is substantially the same as the diameter of the remainder of the catheter or it can have a variable diameter, such as is provided by a balloon. However, regardless of whether the whether the distal end portion is of fixed or variable diameter, the overall size of the device and the injection tube are limited by the dimensions of the vasculature. Typical devices are 5 mm to 7 mm in diameter. Given the small device size, it has proven challenging to cool or freeze warm bodily tissue to a temperature near or well below freezing. Accordingly, it is important to maximize the cooling potential of the coolant by delivering or injecting it at a particular location within the device.
In order to cool other than a small spot, devices as depicted in U.S. Pat. No. 6,235,019 provide multiple coolant injection tubes. Alternately, as shown in U.S. Pat. No. 5,899,898, a single injection tube can be provided with openings along its length. Although such coolant injection structures can be very desirable for created an elongated cooling zone, they are less suitable for balloon devices or over-the-wire devices. With respect to an over-the-wire device, it will be noted that a relatively large central passage for the wire actually blocks or isolates the injection lying at one side of the passage from the opposite side of the passage, thereby insulating the masked side of the device and creating uneven cooling.
Although not directed to issues related to an over-the-wire device, U.S. Pat. No. 6,551,274 illustrates a loosely coiled injection tube. However, as with the linear injection tubes having a series of longitudinal ports, at regular intervals along the device, the central structure masks the injection tube.
In view of the preceding, it is believed that an improved injection tube would be desirable for use with over-the-wire devices or other devices that have structures other than an injection tube in the cooling chamber of the device.
The present invention provide an improved injection tube for use with over-the-wire devices or devices that have structures other than an injection tube in the cooling chamber of the device. In an exemplary embodiment a medical includes a steering element and a fluid injection tube, wherein a portion of the fluid injection tube is wound around the steering element. The steering element can include a passage for a guide wire.
More particularly, the medical device includes a catheter having a proximal end and a distal end, the catheter defining a lumen; a passage for a guide wire disposed within the lumen so as to be coaxial with the lumen and having an open proximal end that is substantially coterminous with the proximal end of the catheter and an open distal end that is substantially coterminous with the distal end of the catheter; a fluid injection tube, wherein a portion of the fluid injection tube is wound around the passage for the guide wire; and a plurality of radially spaced injection ports in the portion of the fluid injection tube that is wound around the passage for the guide wire.
A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:
Referring to
However, referring to
At least a portion of the fluid injection tube 10 is wound around a structure 20 that passes through or is contained within the lumen 12 such as another tube, a wire, a shim, or a spring. In the illustration of
Continuing to refer to
The fluid injection tube 10 can be apertured or plugged at its distal end, and/or it can include multiple radially-spaced injection ports 30 helically wound portion 28. The radially spaced injection ports 30 can be equally spaced apart; and, in an exemplary embodiment, four injection ports 30 are spaced 90 degrees apart on the distalmost winding. As to materials, the longitudinal portion 26 can be made of polyimide and helically wound portion 28 can be made of stainless steel. When coolant in liquid, gas, or mixed phase state exits the ports 30 (as shown by a stylized spray pattern), the coolant expands and/or fills the lumen or space 12 and then is evacuated through the return lumen 19.
In an exemplary embodiment, the longitudinal portion 26 includes 0.0126″ polyimide tubing and helically wound portion 28 is a stainless steel coil having a 0.022″ outer diameter and a 0.014 inner diameter. There are four 0.0025″ laser drilled ports in the helically wound portion that are equally spaced.
It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope and spirit of the invention, which is limited only by the following claims.
