This invention relates to the removal of material from body lumens and cavities and in particular to the optical removal of obstructive material from blood vessels, such as partial blockages and chronic total occlusions, achieved by navigating an interventional device through a patient vasculature.
Various attempts have been made to provide for the removal of material from body lumens, such as blood vessels. For example, rotating burrs have been developed which can be navigated through the lumen to mechanically remove material forming blockages in the lumen. One example of such a device is disclosed in U.S. Pat. Nos. 6,740,103 and 6,733,511 for magnetically navigable and/or controllable device for removing material from body lumens and cavities, incorporated herein by reference. Other devices have attempted to use energy (for example radio-frequency (RF) energy or optical energy) to ablate the material forming blockages in the lumen. One problem with the adoption of ablative technologies for use in chronic total occlusion (CTO) therapy has been the inability to adequately navigate to the CTO and then clear a path through the CTO. The key to the use of interventional and ablative technologies is in the ability to plan the procedure, guide the minimally invasive surgery, monitor and control the progress of the intervention, and verify that the therapy objectives have been met. In particular, monitoring and controlling the ablative device during the intervention is necessary to remove the CTO without damaging the vascular wall.
Many of the laser ablation devices presently available on the market use a fiber bundle and have outer diameters ranging from about 0.9 mm to about 4.9 mm, the larger devices having an interior lumen that allows the device to be inserted over an already placed guidewire. Many occlusions, such as those affecting the coronary arteries, are located in relatively small vessels distant from the medical device insertion point. Reaching such lesions is facilitated by use of small diameter devices that are more maneuverable at branch points and within convoluted anatomy. However, incorporating any kind of conventional directional control in such small devices has been difficult; devices utilizing internal cabling systems or similar mechanical control mechanisms for remote operation of the distal end are typically too large for access to small arteries. Another difficulty with at least some of the available devices is that the devices typically only clear an opening through a lumen with a dimension equivalent to the diameter dimension of the device, which must necessarily be small in order to reach occlusions in small arteries. Still another difficulty with at least some of the devices has been ablatively operating the devices in curved lumens. The devices tend to clear a path extending beyond the distal end and aligned with the axis of the device at the distal end, which makes it difficult to advance a device along a curved path. These two later difficulties compound: the path cleared by the device through an occlusion, being not significantly larger than the device diameter, precludes reorientation of the device tip to follow the curvature of the vessel within which the occlusion is lodged. These and other difficulties have limited the usefulness of ablative devices for clearing body lumens and vessels.
The present invention discloses ablative devices that address a number of the problems encountered with application of the currently available designs. In one embodiment a device is provided that provides ablative energy at an angle relative to the longitudinal axis of the device. This permits the device to clear a path through a curved lumen. Through operation of the ablative energy concurrently with rotation of the device distal end, such a design also permits clearing a path that is at least somewhat larger than the device itself. A number of embodiments of optical ablation devices are disclosed wherein magnetically responsive elements can be provided to allow the distal end to be oriented or positioned with an externally applied magnetic field. Through the magnetic forces and torques exerted on the device distal end, magnetic navigation enables easier progression of the therapy device to the blockage and improved maneuverability of the device in clearing a path through the occlusion.
A first embodiment of a device for ablating material from a body lumen in accordance with the principles of this invention comprises an elongate element having a longitudinal axis and an essentially circular cross-section. The element has a proximal end, a distal end, and lumen therebetween. The device further comprises means for delivering optical energy from the distal end of the elongate element at an angle with respect to the longitudinal axis of the distal end. This means could be at least one, and preferably a bundle, of optical fibers. These optical fibers may be bent adjacent the distal end at an angle or multiplicity of angles with respect to the longitudinal axis of the elongate element to direct optical energy from the distal end of the device at an angle or angles with respect to the longitudinal axis. Alternatively, the distal ends of the optical fibers can be beveled and optically coupled to a lens for delivering the optical energy at an angle with respect to the longitudinal axis of the device; in yet a further embodiment, groups of one or more optical fibers can be beveled and each group optically coupled to one of a multiplicity of lenses for delivering optical energy at a range of angles with respect to the device longitudinal axis.
In accordance with several embodiments of this invention, magnetically responsive elements can be provided to allow the distal end of the device to be oriented using an externally applied magnetic field. These magnetically responsive elements can comprise permanent or permeable magnetic material and/or electromagnetic coils. The orientation of the distal end of the device, and thus the direction of the delivery of the optical energy can be controlled by controlling the direction of the applied magnetic field, and by controlling the rotation of the device with respect to the longitudinal axis through torques applied at the device proximal end.
Thus, devices of the various embodiments of this invention provide ablative energy at an angle or at a multiplicity of angles relative to the longitudinal axis of the device, permitting the device to clear a path through a curved lumen. Through rotation of the distal end with respect to its longitudinal axis, as induced for instance by mechanical torques applied at the device proximal end, the device can clear a path that is at least somewhat larger than the device itself. These and other embodiments and advantages of the present invention will become apparent from the following detailed description, and the accompanying drawings, which illustrate by way of example the features of the invention.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
A first embodiment of a device for ablating material from a body lumen is indicated generally as 100 in
More specifically, and as shown in
The device 100 preferably also includes at least one magnetically responsive element adjacent the distal end of the element for orienting the distal end in an applied magnetic field of about 0.1 Tesla, and more preferably in an applied magnetic field of about 0.08 Tesla, and still more preferably in an applied magnetic field of about 0.06 Tesla. The one or more magnetically responsive elements can comprise magnetic bodies, such as magnetic rings 128, which can be made of a permanent magnetic material such as neodymium-iron-boron (Nd—Fe—B), but could alternatively comprise a permeable magnetic material such as Hiperco. Alternatively, or in addition, the magnetically responsive element could comprise an electromagnetic coil 150.
In use, the device 100 is connected to a source of optical energy, such as a laser. Optical energy is conducted by the fiber optic bundle 112 from the proximal end 114 to the distal end 116. Because of the bend in the fiber optic bundle, the optical energy emanates from the distal end of the device at an angle with respect to the longitudinal axis of the device. The magnetically responsive elements help to orient the device so that it can be navigated through the body lumen, and in particular help to navigate the device through bends and branches in the body lumen, and to control the orientation of the device to clear a wide path through the body lumen.
As illustrated in
Moreover, if the device is rotated, it is possible to clear a path larger than the device itself. For example, and as illustrated generally by 400,
A second embodiment of a device for ablating material from a body lumen is indicated generally as 500 in
The device 500, like device 100, preferably also includes at least one magnetically responsive element 540 adjacent the distal end of the element for orienting the distal end of the element in an applied magnetic field of about 0.1 Tesla, and more preferably in an applied magnetic field of about 0.08 Tesla, and still more preferably in an applied magnetic field of about 0.06 Tesla. The one or more magnetically responsive elements can comprise magnetic bodies, such as magnetic rings 542, which can be made of a permanent magnetic material such as neodymium-iron-boron (Nd—Fe—B), but could alternatively comprise a permeable magnetic material such as Hiperco. Alternatively, or in addition, the magnetically responsive element could comprise an electromagnetic coil.
In use, the device 500 is connected to a source of optical energy, such as a laser. Optical energy is conducted by the fiber optic bundle 512 from the proximal end 514 to the distal end 516. Because of the lens 518, the optical energy emanates from the distal end of the device at an angle with respect to the longitudinal axis of the device. This facilitates clearing a path through a bending lumen, more so than a device that has a straight fiber optic end aligned with the longitudinal axis of the device. Moreover, if the device 500 is rotated, it is possible to clear a path opening within a vessel larger than the device itself, as illustrated in
Various embodiments offer trade-offs between ease of manufacturability, magnitude of the resulting magnetic moment, and ease of operation.
In accordance with a preferred embodiment of a method of ablating material from a body lumen to form a passage therein in accordance with the principles of this invention, a device such as device 100 or device 500 is disclosed comprising an elongate element having a longitudinal axis, and a fiber optic bundle for delivering optical energy from the distal end of the device at an angle with respect to the longitudinal axis of the device. The device can be navigated through a body lumen such as a blood vessel, by applying a magnetic field from an external source to orient the device and then mechanically advancing the device in the desired direction. Once at the site of a blockage, optical energy can be provided to the proximal end of the fiber optic bundle, which conducts the energy through the device and out the distal end of the device at an angle with respect to the longitudinal axis to ablate material blocking the vessel. The emitted radiation forms a path at an angle or angles with respect to the current orientation of the device, facilitating navigating the device through a bend or a branch in the blood vessel. The distal end of the device can be oriented in the direction of the cleared path, for example by applying the appropriate magnetic field from an external source magnet, and the device advanced through the bend or branch by repeating these steps. The device can also be rotated about its longitudinal axis, so that the path formed by the ablative beam sweeps a cone extending from the distal end of the device, clearing an area larger than the cross sectional area of the device.
Although the present invention has been described with respect to several exemplary embodiments, there are many other variations of the above-described embodiments that will be apparent to those skilled in the art, even where elements have not explicitly been designated as exemplary. It is understood that these modifications are within the teaching of the present invention, which is to be limited only by the claims appended hereto.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/711,776, filed Aug. 26, 2005, the entire disclosure of which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
60711776 | Aug 2005 | US |