Patent Description:
The use of percutaneous endovascular procedures has been well established as a minimally invasive technique to deliver a variety of clinical treatments in the patient's vasculature. Such procedures include, for example, the use of a percutaneous endovascular catheter, which may be used in various applications, including delivering and deploying stent grafts.

A common heart disease is atherosclerotic cardiovascular disease, caused by the buildup of plaque or stenoses in blood vessels of a patient. This affliction affects not only veins and arteries, but also dialysis access systems such as fistulas or grafts. Generally, arteries are susceptible to the buildup of plaque. The venous system, however, may have lesions that are generally fibrous in nature, typically in the form of scar tissue. Where there is prolonged or enlarged buildup in the vessels, blood may be dangerously inhibited from passing through the vessel. This can lead to complications of the vasculature system, Document <CIT> relates to a cutting stent.

Document <CIT> relates to an extraction device for removing a thrombus from within a blood vessel.

The invention relates to a catheter system as defined in claims <NUM> and <NUM>.

A catheter used for percutaneous endovascular procedures is described. The catheter may be configured to be used for engagement and treatment of obstructive lesions in a patient's vasculature. The catheter may include a tube having a leading edge that is configured to score or cut a lesion in a vasculature. The tube may be an expandable outer tube, and placed around an inflatable inner tube, such that inflation of the inner tube expands the outer tube. Expansion of the inner tube may connect or laterally lock the inner tube to the outer tube, allowing both tubes to move in unison through the vasculature. The leading edge can score or cut lesions as it moves in the vasculature.

According to one embodiment, an endovascular catheter system is configured to remove a blockage in a vessel of a patient. The catheter comprises an inflatable inner tube and an expandable outer tube. The inner tube is configured to operate in a deflated configuration and an inflated configuration. The outer tube is configured to advance longitudinally over the inner tube when the inner tube is in the deflated configuration. The outer tube includes a leading edge having blocking-cutting features configured to remove at least a portion of the blockage in the vessel. The outer tube is made of a radially-expandable material such that inflation of the inner tube to the inflated configuration when the outer tube is located about the inner tube causes the outer tube to expand radially.

In another embodiment, an endovascular catheter system includes an inner tube extending between a proximal end and a distal end, the distal end being a tapered distal end tapering radially inwardly. A sleeve extends between a proximal end and a distal end and configured to slide over the inner tube. The distal end of the sleeve and the tapered distal end of the inner tube define a radial gap therebetween. The distal end of the sleeve includes blockage-cutting features configured to remove blockages within a blood vessel of a patient.

Further disclosed but not claimed is, a method for treating a blood vessel having blockages therein is provided. The method includes tracking an inner tube along a guidewire to a desired location in the blood vessel, then advancing an outer tube over the inner tube, wherein the outer tube includes blockage-cutting features, then inflating the inner tube to expand the outer tube, then advancing the inner tube and outer tube together through the blood vessel to enable the blockage-cutting feature to cut blockages in the blood vessel.

Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.

Directional terms used herein are made with reference to the views and orientations shown in the exemplary figures. A central axis is shown in the figures and described below. Terms such as "outer" and "inner" are relative to the central axis. For example, an "outer" surface means that the surfaces faces away from the central axis, or is outboard of another "inner" surface. Terms such as "radial," "diameter," "circumference," etc. also are relative to the central axis. The terms "front," "rear," "upper" and "lower" designate directions in the drawings to which reference is made.

Unless otherwise indicated, for the delivery system the terms "distal" and "proximal" are used in the following description with respect to a position or direction relative to a treating clinician. "Distal" and "distally" are positions distant from or in a direction away from the clinician, and "proximal" and "proximally" are positions near or in a direction toward the clinician. For the stent-graft prosthesis, "proximal" is the portion nearer the heart by way of blood flow path while "distal" is the portion of the stent-graft further from the heart by way of blood flow path.

Although the description is in the context of treatment of blood vessels such as the aorta, coronary, carotid and renal arteries, the invention may also be used in any other body passageways where it is deemed useful.

The use of percutaneous endovascular procedures has been well established as a minimally invasive technique to deliver a variety of clinical treatments in the patient's vasculature. One unmet challenge still to be addressed by commercially-available devices is the ability to remove a blockage (such as plaque from hard, calcified occluded lesions) from a blood vessel in order to restore the physiological blood flow through the vessel. References to a "blockage" herein is intended to refer to one or more lesions, stenoses, plaque, or any other similar type of infliction or obstruction within a blood vessel that would constrict blood flow within that vessel.

Therefore, according to various embodiments described herein, an endovascular catheter is disclosed with blockage-cutting features. The blockage-cutting features may include teeth, serrations, or the like and may be located at a leading edge of a lumen in the catheter, for example. As the lumen is advanced along the blood vessel, the blockage-cutting features can cut or score the blockage. Also, the diameter of the lumen may be adjustable. In embodiments explained herein, an inflatable tube may be placed inside the lumen, wherein inflation and deflation of the tube may corresponding expand and contract the lumen.

Referring to <FIG>, an occluded arterial blood vessel <NUM> is shown with various blockages <NUM> that, if left untreated, may inhibit blood flow through the vessel <NUM>. The blood vessel <NUM> has an outer diameter (OD) and an inner diameter (ID). The OD is defined between an outer wall <NUM> of the vessel <NUM>. The ID is constricted and varies drastically throughout the vessel <NUM> due to the prevalence of blockages <NUM> therein.

A guidewire <NUM> is shown inserted in the vessel <NUM>. The guidewire <NUM> can be inserted into the blood vessel <NUM> via an endovascular procedure in which the guidewire <NUM> is first inserted into the patient's skin, and is fed along one or more blood vessels until arriving at the desired blood vessel <NUM> for treatment to take place. The guidewire <NUM> may be made of various thicknesses, materials, and flexibilities. For example, the guidewire <NUM> may be a nitinol guidewire such as NITREX or BABYWIRE.

In one embodiment, a shaft or inner tube <NUM> is provided over the guidewire <NUM>. The inner tube <NUM> can also be referred to as a lumen, catheter tube, inner shaft, or the like. The inner tube <NUM> can be or include a dedicated lumen <NUM> for tracking over the guidewire <NUM>. In application, once the guidewire <NUM> is properly positioned in the desired vessel <NUM>, the lumen <NUM> can be slid over the guidewire <NUM> and advanced along the guidewire <NUM> until the inner tube <NUM> itself reaches the desired location in the vessel <NUM>.

<FIG> shows the inner tube <NUM> located at an initial or first linear position within the vessel <NUM>, prior to treatment of the blockages <NUM>. As will be explained below and shown in the remaining Figures, the inner tube <NUM> can be advanced further into the blood vessel <NUM> during cutting or scoring of the blockages <NUM>.

The inner tube <NUM> can also include or be coupled to an inflatable element <NUM> (e.g., an inflatable balloon or the like) that can adjust in diameter. The inflatable element <NUM> can assume both a deflated configuration and an inflated configuration. The inflatable element <NUM> is shown in the deflated configuration in <FIG>. The inflatable element <NUM> may be integrally formed with the inner tube <NUM>. For example, the inflatable element <NUM> and the lumen <NUM> may be a singular component. The inflatable element <NUM> may be a sealed chamber disposed radially outward of a central aperture or dedicated lumen of the inner tube <NUM> (that receives the guidewire <NUM>) so that a fluid medium (e.g., water or saline) performing the inflation of the inflatable element <NUM> is kept separate and does not contact the guidewire <NUM>. In another embodiment, the inflatable element <NUM> is a separately-attached component that is configured to assemble to an outer surface of the inner tube <NUM> or lumen <NUM>. In another embodiment, the inner tube <NUM> can have a multi-lumen design and structure, with one lumen dedicated to the inflatable element <NUM> and another dedicated to contain the guidewire <NUM>.

<FIG> illustrates an introduction of an outer tube <NUM> into the treatment area of the vessel <NUM>. The outer tube <NUM> can also be referred to as a sleeve, lumen, catheter tube, or the like. The outer tube <NUM> can be a single-lumen configuration with blockage-cutting tips at a distal end thereof (as will be described further below). The outer tube <NUM> is made of a flexible yet durable material, allowing the outer tube <NUM> to slide over the outer diameter of the inner tube <NUM>. The outer tube <NUM> is designed to have rigid longitudinal mechanical properties such that mechanical forces transmitted to the outer tube <NUM> from the proximal end thereof (e.g., from the operator of the catheter) would be mechanically transferred to a distal end <NUM> with high efficiency (high "pushability"). The outer tube <NUM> can be made of, for example, Nitinol, or a combination or Nitinol with other metals and polymers, or other super-elastic alloys due to their elasticity and ability to deform and recoil back to their initial shape without any permanent changes. A material structure similar to that of the covered stents (e.g., polymer fabric sewn onto super-elastic, expandable metal frame) can also be appropriate.

As shown in <FIG>, the outer tube <NUM> can be slid over a proximal end of the inner tube <NUM>, and advanced toward the distal end of the inner tube <NUM>. In <FIG>, the inner tube <NUM> and its inflatable element <NUM> are maintained in the deflated configuration, allowing ease of longitudinal movement of the outer tube <NUM> relative to the inner tube <NUM>. In this configuration, the unbiased, natural-state inner diameter of the outer tube <NUM> exceeds at least a portion of the outer diameter of the inner tube <NUM> and/or inflatable element <NUM> to facilitate the relative movement of the outer tube <NUM> along the inner tube <NUM>. The inner tube <NUM>, the outer tube <NUM>, and any associated handle or control device (not shown) can be referred to as a catheter or a catheter system for placement along the guidewire <NUM>.

<FIG> shows further advancement of the outer tube <NUM> relative to the inner tube <NUM>. The inner tube <NUM> and its inflatable element <NUM> may be maintained in the deflated configuration to allow the further advancement of the outer tube <NUM> relative to the inner tube <NUM>. During advancement of the outer tube <NUM>, the flexible material properties of the outer tube <NUM> are such that the outer tube <NUM> can conform to the shape of the inner tube <NUM> during such advancement.

Once the distal end <NUM> outer tube <NUM> has reached a desired location along the distal portion of the inner tube <NUM>, the inflatable element <NUM> can be inflated to the inflated configuration. According to one embodiment, the inflation of the inflatable element <NUM> can be performed by an operator, such as a surgical technician. The operator can pump fluid (e.g., saline, etc.) into the inflatable element <NUM>, thus expanding the diameter of the inflatable element <NUM>. The design of the inflatable element <NUM> can be such that a direct relationship exists between the inflation pressure used by the operator and the outer dimension of the inflatable element <NUM>, so that inflation to a given pressure will result in a given, known outer diameter of the inflatable element <NUM>. The inflation process would allow the operator to control the dimensional profile of the distal end of the device with respect to the blood vessel through changes in inflation pressure.

The material of the outer tube <NUM> may be such that it maintains a generally uniform diameter throughout the length of the outer tube <NUM>, regardless of the shape or size of the inner tube <NUM>. This can be seen in <FIG>, for example, in which the distal end of the inner tube <NUM> begins to taper inwardly toward the guidewire <NUM> while the diameter of the outer tube <NUM> remains constant. This can create a radial gap <NUM> between the inner tube <NUM> and the outer tube <NUM> at the distal end <NUM> of the outer tube <NUM>. This also keeps radial separation between the blockage-cutting features <NUM> (described below) and the inner tube <NUM>, allowing the blockage-cutting feature to slice through the blockage without interference from the inner tube <NUM>.

Inflation of the inflatable element <NUM> can provide at least two functions. First, the inflation couples the inner tube <NUM> to the outer tube <NUM> via an outwardly-directed force between an outer surface of the inner tube <NUM> and an inner surface of the outer tube <NUM>. This force, via inflation, allows the inner tube <NUM> and outer tube <NUM> to move along the guidewire <NUM> in unison; as either the inner tube <NUM> or outer tube <NUM> is forced along the guidewire <NUM>, the other of the inner tube <NUM> or outer tube <NUM> will be moved along with. It can be said that the inner tube <NUM> and outer tube <NUM> are therefore laterally locked. Second, the inflation expands the size of the diameter of the outer tube <NUM>. A controlled amount of inflation may be provided by the operator, and therefore the size of the diameter of the outer tube <NUM> can be correspondingly controlled. This allows the operator to expand or contract the size of the blockage-cutting tips at the distal end <NUM> of the outer tube <NUM>, thus altering the size of the cutting to be performed on the blockages <NUM>, as will be described further below.

<FIG> shows advancement of the laterally-locked inner tube <NUM> and outer tube <NUM> in unison. Since, as explained above, the inner tube <NUM> and outer tube <NUM> are locked due to the inflation of the inner tube <NUM>, the inner tube <NUM> and outer tube <NUM> can be moved together along the vasculature in the distal direction. This movement may be performed by a surgical technician via a pushing motion, or operation of a handle, for example. In some embodiments, the movement of the outer tube <NUM> may be only axial in nature (e.g., in the direction of the blood vessel). The axial movement may be continuous or it may be reciprocating (e.g., alternating between pushing and retracting, like a jack-hammer). In other embodiments, the outer tube <NUM> may be rotated as it is advanced axially. Either type of motion may be performed manually by a physician or technician. However, in other embodiments, the motion may be performed using a motor (e.g., electric motor) coupled to the outer tube <NUM> and/or inner tube <NUM>. The motor may be controlled by a physician/technician directly or it may be controlled by a robotic surgery system. The direction of rotation and/or axial motion and/or radial velocity of the controlled system can be modulated in relation to the dimension, location, morphology of the vessel and blockage.

As shown in <FIG>, the distal end <NUM> of the outer tube <NUM> is provided with blockage-cutting features <NUM>. The blockage-cutting features may include teeth, serrations, or the like and may be located at a leading edge (e.g., the distal end <NUM>) of the outer tube <NUM>. In one embodiment, the blockage-cutting features are teeth arranged annularly about the circumference of the distal end <NUM> with the points of the teeth directed parallel to the central longitudinal axis of the outer tube <NUM>. The blockage-cutting features may be triangular in shape, with or without additional serrations thereon. In at least one embodiment, the cutting features extend completely around the circumference of the distal end <NUM> of the outer tube, although in other embodiments there may be annular gaps between cutting sections.

In another embodiment, the blockage-cutting features may be arranged at a location more proximal than the distal end <NUM>. In an embodiment, the blockage-cutting features may additionally or alternatively face radially outwardly from the central axis of the outer tube <NUM>.

As can be seen in comparing <FIG> with <FIG>, as the outer tube <NUM> is moved along the vessel <NUM>, various blockages <NUM> have been scraped to widen the overall blood-flow diameter within the vessel <NUM>. As the outer tube <NUM> is moved along the vessel <NUM>, the blockage-cutting feature <NUM> engage the blockages <NUM> and remove at least a portion of the blockages <NUM>. This creates an overall unobstructed blood-flow diameter within the vessel <NUM> of an amount at least equivalent to the diameter of the outer tube <NUM>.

To create a wider diameter of the outer tube <NUM>, and therefore a wider blood-flow diameter within the vessel <NUM>, the inner tube <NUM> can be further inflated. <FIG> illustrates one embodiment of this. In <FIG>, it can be seen that the inner tube <NUM> has been further inflated via similar operations as described above. This correspondingly expands the diameter of the outer tube <NUM>, allowing the blockage-cutting features <NUM> to engage certain blockages <NUM> that may not have been engageable when the outer tube <NUM> was its previous diameter (e.g., <FIG>). By selectively inflating and deflating the inner tube <NUM> during operation, a surgical technician can select the proper diameter for cutting or scoring the various blockages <NUM>, <NUM> within the vessel <NUM>. This also allows the overall dimensions of the outer tube <NUM> to be varied for different sizes of blood vessels. For example, as the inner tube <NUM> and outer tube <NUM> are inserted into the patient, they may initially travel along smaller vessels (e.g., iliac artery) until reaching a larger vessel (e.g., aorta). As the inner tube <NUM> and outer tube <NUM> enter the aorta, the inner tube <NUM> can be inflated to a larger size to provide a larger cutting profile than was previously provided during travel in the iliac artery. Also, <FIG> shows the overall catheter system being slightly retracted, illustrating one embodiment of proximal and distal movement being possible during a procedure.

In one example, the outer tube <NUM> and blockage-cutting features <NUM> may make multiple passes at the same location in a blood vessel to sequentially increase the size of the unobstructed vessel. A first pass may be performed with the outer tube at a first diameter to remove a portion of a blockage. After the first pass, the outer tube <NUM> and inner tube <NUM> may be retracted and the diameter of the inflatable element may be increased, thereby also increasing the diameter of the outer tube <NUM>. A second pass may then be performed to remove an additional radial thickness of the blockage due to the increased diameter of the outer tube <NUM>. Additional cycles of retracting, increasing the diameter, and performing another pass may be sequentially performed until the physician has removed a desired amount of the blockage. The number of passes may depend on the magnitude of the blockage, the hardness of the blockage (e.g., harder blockages may need smaller/more passes), the size of the vessel, or other factors. This process may be repeated at multiple axial locations in the vessel.

<FIG> shows an embodiment similar to <FIG>, except now showing an outer tube <NUM> with more flexibility at a proximal end <NUM> thereof, and the inner tube <NUM> and outer tube <NUM> being advanced more through the vessel <NUM>. In this embodiment, the outer tube <NUM> is relatively rigid at its distal end <NUM> so that the radial gap <NUM> is maintained between the inner tube <NUM> and the outer tube <NUM>. Meanwhile, the outer tube <NUM> can be relatively flexible (e.g., more flexible than the distal end <NUM>) at its proximal end <NUM> such that the outer tube <NUM> conforms to the shape of the inner tube <NUM> at the proximal end <NUM>. And, with advancement of the catheter system, the blockages <NUM> once present in <FIG> are now removed.

After the blockages are cut or scored according to the teachings above, the blockage can be extracted and removed from the vessel <NUM>. In one example, the removed material may be extracted with a separate removal system, not shown herein. In another example, the cut/scored material may be lodged between the outer tube <NUM> and the inner tube <NUM>/inflatable element <NUM>. For example, when the inflatable element <NUM> is deflated, the outer tube <NUM> may attempt to return to its natural diameter, thereby trapping the removed material between itself and the inflatable element <NUM>. Once a certain amount of the blockage has been removed, the inner and outer tubes may be removed from the body to clear away the removed material. If additional blockages remain to be removed, the inner and outer tubes may be re-inserted and additional removal steps may be performed. This process may be repeated as many times as necessary.

In another example, an aspiration system may be incorporated into the system, either as a separate component or as part of one of the components described herein. The aspiration system may be disposed proximal to the distal end <NUM> of outer tube <NUM> such that it can aspirate/suck removed material once it is cut/scored. The aspiration system may be connected to a source of vacuum/suction in the operating room. By intermittently or continuously aspirating, more cutting passes may be performed without removing the outer tube from the body. In embodiments, the teachings above may be implemented into an atherectomy system, such as a rotational or directional atherectomy system, that includes an atherosclerosis-removal feature, for example.

Embodiments disclosed herein illustrate the outer tube <NUM> being separately attached around the inner tube <NUM>. However, in another embodiment, the outer tube <NUM> is integral with the inflatable member <NUM> (e.g., balloon) such that the blockage-cutting features are part of a single, unitary device surrounding the guidewire <NUM>.

Claim 1:
An endovascular catheter system configured to remove a blockage (<NUM>) in a vessel (<NUM>) of a patient, the endovascular catheter comprising:
an inflatable inner tube (<NUM>) configured to operate in a deflated configuration and an inflated configuration; and
an expandable outer tube (<NUM>) configured to advance longitudinally over the inner tube (<NUM>) when the inner tube (<NUM>) is in the deflated configuration, the outer tube (<NUM>) including a leading edge having blockage-cutting features (<NUM>) configured to remove at least a portion of the blockage (<NUM>) in the vessel (<NUM>);
wherein the outer tube (<NUM>) is made of a radially-expandable material such that inflation of the inner tube (<NUM>) to the inflated configuration when the outer tube (<NUM>) is located about the inner tube (<NUM>) causes the outer tube (<NUM>) to expand radially.