Invented by Steven J. Rychnovsky, John A. Franco, Jeffrey A. Vasek, C. T. Lo Blong, John S. Hill, Adgero Biopharmaceuticals Holdings Inc
The Adgero Biopharmaceuticals Holdings Inc invention works as followsThe present invention provides improved catheters that deliver light to target tissues within blood vessels or other hollow organs. The improved catheter has an optical fiber which transmits light to the light treatment zone from the light source located at the proximal part of the shaft. A catheter shaft inflation lumen is used to fill an occlusion ball at the distal end adjacent to the treatment zone. Infusion fluid is delivered to the hollow organ via an infusion lumen that connects to a plurality infusion ports located at the light-treatment zone.
Background for Light delivery catheter
PDT is a medical therapy that uses light-activated photosensitive dyes in order to induce a positive biological response. These dyes or photosensitizers elicit biological responses when they are irradiated by light in a specific wavelength range, but remain inert if not irradiated.
PDT has a promising application in treating cardiovascular diseases such as vulnerable plaques, atherosclerosis, and restenosis. These applications involve the injection of photosensitizers in the blood vessel that needs to be treated. Then, light is delivered to the target tissue through a catheter. Blood tends to reduce the light intensity in the treatment area, which can be a challenge for PDT or other endovascular treatments. If blood is not removed from the light path, it can significantly reduce the PDT effect. This effect is present for all PDT treatments, but it is more pronounced for those using shorter wavelengths (e.g. less than 610nm), when light is attenuated by blood.
Balloon Catheters have been used to try and eliminate blood during the delivery of light. One common method is to insert a light emitting fiber into a transparent or opaque angioplasty style balloon. Inflating the balloon displaces the blood from the area of light treatment. “This approach is used almost exclusively in most cardiovascular PDT techniques.
For example, Spears, U.S. Pat. No. No. 4,512,762 discloses a catheter with flexible optical fibres that transmit light from an outside source to illuminate the interior of the balloon. The blood between the balloon wall and the diseased vascular walls is displaced by inflation of the ball. Narciso, U.S. Pat. are other examples of PDT caths that use an optical element in a displacement ball. Nos. 5,169,395; 5,441,497; 5,700,243; Leone, U.S. Pat. Nos. 5,797,868; 5,891,082; EP 0 732 085; EP 0 732 079; Ligtenberg et al., EP 0 732 079 A1; Bower et al., U.S. Pat. Nos. 6,013,053; 6,086,558; Overholt et al., U.S. Pat. No. 6,146,409; Aita et al., U.S. Pat. No. 6,132,423; and Amplatz et al., U.S. Pat. No. 5,620,438.
The displacement balloon method described in the patents above has a significant flaw: it does not fully displace blood. Some blood remains trapped between the outer surface of the balloon and the inner surface of the vessel wall. In this case, a balloon at least twice as long as the treatment zone is required to achieve adequate displacement. Non-compliant materials are used to achieve a cylindrical form that matches the vessel shape. This is because these materials maintain their shape after inflation. In order to avoid injury due to mechanical trauma caused by inflation of a noncompliant cylindrically shaped balloon, the balloon must be inflated at a low pressure. A balloon that is inflated with low pressure cannot displace blood in the surrounding area. The angioplasty ball is therefore a compromise, as under-inflation can prevent mechanical trauma but not achieve adequate blood removal. Over-inflation, on the other hand, will result in better blood removal with an increased risk of mechanical injury.
One way to overcome the shortcoming in angioplasty design is to use a ‘weeping ball? as described in Kume et al., U.S. Pat. No. 5,876,426; Leone, U.S. Pat. No. 5,709,653; and Amplatz et al., U.S. Pat. Nos. Nos. These patents each disclose a catheter with an angioplasty style porous balloon that releases fluid to flush out blood around the perimeter of the balloon. These weeping balls may be more effective at removing blood than standard angioplasty balloons but they have some serious shortcomings. As an example, fluid flushed in this manner will tend to take the easiest path to the blood vessel opening, leaving pockets between the balloon wall and the vessel. When the balloon deflates, blood can be drawn into the balloon and reduce the light intensity delivered during subsequent inflation cycles.
Other shortcomings can be caused by the non-compliant materials used in the balloons. The patents above all disclose a light-delivery catheter with an elongated tubular balloon that extends down the length the catheter, at least as far as the light treatment zone. Saab explains this in “Applications for High-Pressure Balloons within the Medical Device Industry”. Medical Device and Diagnostic Industry (September 2000), pg. In order to achieve this tubular shape, an inflated balloon must be made of a material that is relatively non-compliant, (i.e. less elastic), and will maintain its shape after inflation. Non-compliant balloons, which are rigider and do not conform with the shape of vessels, have a higher tendency to cause mechanical injury to vessels. The injury response that results can lead to restnosis.
The non-compliant balloon has a limited ability to treat tortuous long vessels. It is important to fully inflate an angioplasty ball when using a light-emitting element. This will ensure that blood is adequately displaced. This can be a challenge in tortuous vessels and especially if treatment length exceeds 1-2 cm. The non-compliant balloon inflates in a straight, not curving line when it is inflated. This causes mechanical trauma to vessels as the balloon straightens them.
The non-compliant balloon is also limited in its ability to treat vessels with small diameters. The non-compliant balloon must be mounted on the catheter shaft, overlapping the treatment zone. The use of a non-compliant angioplasty balloon increases the diameter of the device within the treatment zone. This limits access to smaller vessel diameters.
Another shortcoming of non-compliant balloons is the treatment of vessels with a diameter that tapers or changes in any other way along the length of the section being treated. It is necessary to blow up the balloon when using an angioplasty-style balloon in order to move the blood. It can lead to injury in the smaller diameter areas of the vessel that is being treated because these balloons have a constant size along their length.
Furthermore non-compliant devices are limited in their ability to treat multiple vessels diameters using a single device. The device must be sized correctly for the vessel being treated when using angioplasty devices. This means that an extensive stock of devices must be maintained and that the vessel shapes that can be treated are limited.
The present invention provides improved light delivery catheters having these and other features and advantages. The present invention provides light delivery catheters that have these features and benefits, as well as others.
The present invention provides improved catheters that deliver light to target tissues within blood vessels or other hollow organs. A catheter shaft with a light-treatment zone is used to create an improved catheter. Light is transmitted to the light-treatment zone by a light guide in the catheter. This light guide can be an optical fiber. A light treatment area is located at the distal end. An occlusion ball is placed on the distal portion of the catheter shaft. Fluid is delivered to the balloon through an inflation lumen within the catheter shaft. This inflation lumen is in fluid communication with a source of inflation fluid at the proximal tip of the shaft. Infusion fluid is delivered to the light-treatment zone by an infusion lumen within the catheter shaft. The infusion fluid comes from a source of infusion fluid at the proximal part of the shaft. The light treatment area has a plurality of infusion port in fluid communication with an infusion lumen. This allows infusion fluid to be delivered into the hollow organ.
The invention also includes light delivery catheters with features that allow for detection of light emitted. In one embodiment of the catheter, a light-delivery optical fiber terminates at the distal end in the light treatment area. In one embodiment, a second light detection fiber is incorporated into the catheter shaft to detect light emitted from the first optical fibre and transmit the detected light towards the proximal portion of the shaft. In another embodiment, fluorescent material is incorporated in the distal end to the catheter shaft so that it emits fluorescent light when exposed to the light emitted by the optical fiber. This emission can propagate to the proximal optical fiber end to monitor light delivery.
Another feature of the invention is improved infusion lumens that can be used with light delivery catheters. In one embodiment, infusion lumens have a larger diameter near the proximal than the distal ends of the catheter. The transition from the larger to smaller diameter occurs at the distal tip of the catheter proximal the light treatment zone. This allows for much higher flow rates at a given pressure compared to what would be possible with the same diameter infusion lumens on the proximal and distal ends, where the shaft is smaller.
The following detailed description and appended claims as well as the accompanying drawings will make it clearer what the invention is all about.
FIG. 1A shows a schematic side view of a catheter for light delivery;
FIG. The cross-sectional image of the light delivery capillar of FIG. The plane of the cross section coincides with the location of the shaft where discrete flush ports were created at the periphery.
FIG. “FIG. 1A;
FIG. “FIG.Click here to view the patent on Google Patents.