The invention relates to a medical device for dilation within a body vessel that provides embolic protection and perfusion during the dilation of the body vessel and/or the dilation of a prosthesis to be positioned within the body vessel.
Human blood vessels often become occluded or completely blocked by plaque, thrombi, deposits, or other substances, which reduce the blood carrying capacity of the vessel. Should the blockage occur at a critical place in the circulatory system, serious and permanent injury, or even death, can occur. To prevent this, some form of medical intervention is usually performed when significant occlusion is detected.
A serious example of vascular occlusion is coronary artery disease, which is a common disorder in developed countries and is the leading cause of death in the United States. Damage to or malfunction of the heart is caused by narrowing or blockage of the coronary arteries that supply blood to the heart. The coronary arteries are first narrowed and may eventually be completely blocked by plaque (atherosclerosis), and the condition may further be complicated by the formation of thrombi (blood clots) on roughened surfaces of, or in eddy currents caused by the plaques. Myocardial infarction can result from coronary atherosclerosis, especially from an occlusive or near-occlusive thrombus overlying or adjacent to the atherosclerotic plaque, leading to ischemia and/or death of portions of the heart muscle. Thrombi and other particulates also can break away from arterial stenoses, and this debris can migrate downstream to cause distal embolization.
Various types of interventional techniques have been developed that facilitate the reduction or removal of the blockage in the blood vessel to allow increased blood flow through the vessel. One technique for treating stenosis or occlusion of a blood vessel is balloon angioplasty. A balloon catheter is inserted into the narrowed or blocked area, and the balloon is inflated to expand the constricted area. In many cases, near normal blood flow is restored. However, the application of balloon angioplasty to certain blood vessels has been limited due to the risk of embolism caused by the dislodgement of the stenotic material, which may then move downstream. For example, angioplasty is not the currently preferred treatment for lesions in the carotid artery because of the possibility of dislodging plaque from the lesion, which may then enter the various arterial vessels of the brain and cause permanent brain damage.
Many techniques exist for preventing the release of thrombotic or embolic particles into the bloodstream during such a procedure. Common among these techniques is introduction of an occlusive device or a filter downstream of the treatment area to capture these embolic particles. The particles may then be removed from the vessel with the withdrawal of the occlusive or filtering device. In another common technique, the particles may be removed by an aspiration catheter prior to the withdrawal of the dilation device. Aspiration catheters have also been found useful in removing thrombus prior to crossing underlying atherosclerotic plaque with guidewires and/or treatment catheters. Such preliminary removal of thrombus makes it easier to cross the stenosis and less likely that thrombo-embolic particles will be released into the bloodstream during the procedure. However, both of these techniques require a dilation device and an additional device for preventing the release of thrombotic or embolic particles into the bloodstream.
Another problem with balloon dilators arises from the fact that the balloon is made from essentially impermeable materials. When such a device is expanded to perform the dilation, blood flow is occluded through the blood vessel in which the balloon dilator is being used. Such an occlusion of blood flow may substantially harm the patient, since portions of the body will not receive blood during the procedure. Thus the length of time a balloon dilator may be used to perform a dilation is limited. Occlusion of blood flow is especially an issue when a dilation procedure is being performed in a portion of the circulatory system where there is a branch in the blood vessels, such as where the arch vessels branch from the thoracic aorta. Improper placement of the balloon dilator in the aorta may cause an unanticipated occlusion in blood flow to a branch of the circulation system. In addition to blocking blood flow, impermeable balloon dilators may cause significant blood pressure upstream of the dilator. The increased blood pressure may cause the balloon dilator, and any prosthesis positioned in the blood vessel that was being dilated such as a stent or stent-graft, to effectively be pushed downstream by the blood and moved out of the desired position. As such, accurate placement of prostheses, such as stents and stent-grafts, may be made more difficult.
Therefore, there remains a need in the art for a dilator that addresses the above-described concerns related to occluding blood flow and causing emboli during a dilation procedure.
Embodiments in accordance herewith are directed to a combination dilator-embolic protection device for simultaneously dilating a stenotic body vessel or a tubular prosthesis, providing protection from embolic debris and permitting constant perfusion during the interventional procedure. The device includes an expandable dilator-filtration component having a first filtration segment, a second filtration segment and an interior volume, wherein the first filtration segment has at least one opening of a first size that permits passage of embolic debris into the interior volume and the second filtration segment has openings of a second size that is smaller than the first size, such that the second filtration segment retains the embolic debris within the interior volume. The dilator-filtration component is expandable into apposition with a stenosis or a tubular prosthesis in the body vessel to provide a radial distensible force to dilate the stenotic body vessel or tubular prosthesis while permitting body fluids to perfuse through the treatment area.
In an embodiment, the device includes an elongate shaft component defining a lumen that extends between a proximal end and a distal end thereof and an inner shaft component slidably extending through the lumen of the elongate shaft component and the interior volume of the dilator-filtration component. A distal end of the dilator-filtration component is attached to the inner shaft component proximate a distal end thereof and a proximal end of the dilator-filtration component is attached to the distal end of the elongate shaft portion, such that sliding movement of the inner shaft component relative to the elongate shaft component, or vice versa, reduces the distance between the proximal and distal ends of the dilator-filtration component thereby expanding the component.
The foregoing and other features and advantages of embodiments according to the present invention will be apparent from the following description as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the embodiments described and to enable a person skilled in the pertinent art to make and use the embodiment. The drawings are not to scale.
Specific embodiments are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The terms “distal” and “proximal” are used in the following description with respect to a position or direction relative to the treating clinician. “Distal” or “distally” are a position distant from or in a direction away from the clinician. “Proximal” and “proximally” are a position near or in a direction toward the clinician.
The following detailed description is merely exemplary in nature and is not intended to be limiting. Although the method and apparatus presented describes treatment in the context of blood vessels such as the aorta, the treatment may also be used in any other body passageways where it is deemed useful.
Dilator-embolic protection device 113 also includes an inner shaft component 108 that longitudinally extends the entire length of device 113 through lumen 111 of elongate shaft component 115, an interior volume of expandable dilator-filtration component 114 and distal tip 112. A proximal end (not shown) of inner shaft component 108 extends out of the patient and may be manipulated by a clinician and a distal end of inner shaft component is secured to, or forms a portion of, distal tip 112. Inner shaft component 108 defines a guidewire lumen 110 for receiving a guidewire (not shown) therethrough, such that dilator-embolic protection system 100 may be advanced over an indwelling guidewire to a treatment site within the vasculature. In addition, system 100 may include one or more radiopaque markers (not shown) allowing for accurate positioning of the system within the treatment site.
As shown in
Expandable dilator-filtration component 114 provides a uniform radial distention force to a stenotic body vessel to dilate the body vessel. As discussed with reference to the embodiment of
With reference to
In
Expandable dilator-filtration component 114 has sufficient radial strength to dilate a stenotic vessel as it is being expanded. In the embodiment of
The mesh material is preferably made out of a nickel-cobalt-chromium alloy such as MP35N. The dilator-filtration component 114 can diametrically vary from 20 mm to 40 mm for the aorta for example. The mesh pore size can vary from 50 to 1000 microns which can treat thromboembolic diseases.
Elongate shaft component 115 and inner shaft component 108 may be formed of any suitable flexible polymeric material. Non-exhaustive examples of material for the shaft components are polyethylene terephalate (PET), nylon, polyethylene, PEBAX, or combinations of any of these, either blended or co-extruded. Optionally, a portion of the shaft components may be formed as a composite having a reinforcement material incorporated within a polymeric body to enhance strength, flexibility, and/or toughness. Suitable reinforcement layers include braiding, wire mesh layers, embedded axial wires, embedded helical or circumferential wires, and the like. In an embodiment, the proximal portion of elongate shaft component 115 may in some instances be formed from a metallic tubing, such as a hypotube, or a reinforced polymeric tube as shown and described, for example, in U.S. Pat. No. 5,827,242 to Follmer et al., which is incorporated by reference herein in its entirety. The shaft components may have any suitable working length, for example, 550 mm-600 mm, to extend to a target location within the body vessel.
In an embodiment shown in
In contrast to the previous embodiment, first filtration segment 316 is located distal of second filtration segment 320 such that as a retrograde blood flow passes through dilator-filtration component 314, embolic debris may pass through opening(s) 318 of first filtration segment 316 into the interior of component 314 to be trapped therein by second filtration segment 320, which has smaller dimensioned openings 322.
Expandable dilator-filtration component 314 may be held or biased in its delivery configuration within sheath catheter 306 so that dilator-embolic protection device 313 may be tracked through the vasculature in a low profile. When it is desired to expand dilator-filtration component 314 into the balloon-like radially distensible scaffold configuration, sheath catheter 306 and inner shaft component 308 are moved relative to each other such that expandable dilator-filtration component 314 is released from sheath catheter 306 and allowed to assume its expanded configuration shown in
A handle 330 is shown attached to a proximal end 332 of sheath catheter 306 to facilitate securing a longitudinal position or sliding movement thereof relative to inner shaft component 308. In another embodiment, a handle or knob (not shown) may be attached at a proximal end 334 of inner shaft component 308 in order to facilitate securing a longitudinal position or sliding movement thereof relative to sheath catheter 306.
As shown in
In addition to being utilized for dilating a body vessel, an expandable dilator-filtration component according to an embodiment hereof may be used to expand a tubular prosthesis, such as a stent or stent-graft, within the body vessel.
While various embodiments according to the present invention have been described above, it should be understood that they have been presented by way of illustration and example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. It will also be understood that each feature of each embodiment discussed herein, and of each reference cited herein, can be used in combination with the features of any other embodiment. All patents and publications discussed herein are incorporated by reference herein in their entirety.