Bifurcation stent and delivery system

The present invention is directed to a device comprising a catheter tube, which includes a round opening and two platinum radio-opaque markers on its distal end; a guide-wire; a balloon, which includes a wedge-shaped opening; and a stent, which includes an elliptical-shaped opening and three platinum radio-opaque markers. The invention is also directed to methods for using the device for deploying stents to treat bifurcation lesions.

FIELD OF THE INVENTION

The present invention relates generally to medical devices and medical methods. More particularly, the present invention relates to devices and methods useful for deploying stents to treat bifurcation lesions.

BACKGROUND OF THE INVENTION

Atherosclerosis is the progressive narrowing and hardening of arteries over time. The process is characterized by plaque buildup on the inside of the arteries. Atherosclerosis is known to occur to some degree with aging, but other risk factors that accelerate this process have been identified, including high cholesterol, high blood pressure, smoking, diabetes and a family history for atherosclerotic disease.

Percutaneous transluminal coronary angioplasty is a common procedure used by doctors to treat atherosclerosis. The procedure involves mechanically dilating a narrowed or totally-obstructed artery by passing a balloon catheter through the artery to the area of plaque buildup and inflating the balloon, which compresses the plaque and increases the interior diameter of the artery. Doctors generally use a guide-wire across the arterial blockage to advance the balloon catheter to the site of the blockage.

During angioplasty, doctors may also place a stent in the newly widened artery to hold up the artery and decrease the risk of restenosis or re-narrowing of the artery. Stent installation generally follows the same angioplasty procedure, except the balloon is attached to a stent and together they are positioned at the site of blockage using a guide-wire. The balloon is then inflated to push the stent against the artery wall, which anchors the stent in place. The balloon is then deflated and removed along with the catheter and the guide-wire.

Although the use of a stent during angioplasty is generally preferred, doctors have found it difficult, if not impossible, to safely and effectively deploy the stent in bifurcated arteries—arteries divided into two equally important branches or, alternatively, a main artery branch giving away to a side branch. Specifically, inflating the balloon and pushing the stent against the artery wall in one branch may force plaque into the other branch of the artery, effectively blocking that branch, which could cause a heart attack if the artery supplies blood to the heart or a stroke if the artery supplies blood to the brain.

Alternatively, doctors have tried to use two guide-wires (one in each arterial branch) so that a balloon can be advanced to each branch and inflated either substantially simultaneously or in closely spaced intervals. In the event a stent is advanced into a bifurcation lesion after both branches have been dilated, the guide-wire not used for placement of the stent must be removed because the guide-wire would become permanently trapped in the arterial wall when the stent is deployed. Additionally, if the second guide-wire, which was not used for stenting, is removed and the stent is deployed using the first guide wire, some of the plaque residue can be squeezed into the side branch creating a blockage.

SUMMARY OF THE INVENTION

The present invention provides devices for treating bifurcation lesions. In one embodiment, the device comprises a substantially cylindrical housing sized to fit in the internal volume of an artery, an opening in the housing between the proximal and distal ends of the housing, and at least one metal radio-opaque marker on the housing. The opening in the housing can accommodate the passage of a standard balloon catheter. The device preferably includes three metal radio-opaque markers on the housing, which are spaced at approximately 90 degree angles relative to the opening in the housing and which are used to identify the location of the device for alignment with an arterial branch. The metal radio-opaque markers may be gold, platinum or any other suitable metal.

In some embodiments, the device includes a balloon, which may be attached to the housing. The balloon includes an opening that may be substantially equidistant from the proximal and distal ends of the balloon. Preferably, the opening in the balloon is wedge-shaped.

Some embodiments of the device further include a catheter tube with an opening located near the catheter's distal end. The catheter tube includes at least one metal radio-opaque marker located substantially near the opening of the catheter tube, and preferably includes two metal radio-opaque markers on opposite sides of the opening. The metal radio-opaque markers on the catheter tube identify the position of the opening relative to the opening of an arterial branch which, when the openings in the housing, the balloon and the catheter tube are aligned, allows passage of a guide-wire through the openings and into an arterial branch.

The present invention also provides methods for deploying stents to treat bifurcation lesions. In one embodiment, the method comprises the steps of accessing the internal volume of an artery, which is divided into a first and second branch; inserting a balloon catheter, which comprises a first catheter tube, a first balloon and a first stent, into the internal volume; using a first guide-wire to advance the balloon catheter to a site of plaque buildup substantially near the two branches; positioning the balloon catheter substantially at the center of the plaque buildup in a first branch; advancing a second guide-wire through the first catheter tube to a position substantially near the center of the first balloon; using at least one metal radio-opaque marker on the balloon catheter as a guide to align openings in the first catheter tube, the first balloon and the first stent, respectively, with an opening to the second branch; advancing the second guide-wire into the second branch through the openings in the first catheter tube, first balloon and first stent; inflating the first balloon to deploy the first stent; deflating the first balloon; advancing a third guide-wire into the second branch and withdrawing the first balloon and first catheter tube and the first and second guide-wires; using the third-guide wire to advance a second balloon catheter, which comprises a second catheter tube, a second balloon and a second stent, to the second branch through the first stent; advancing a fourth guide-wire into the first branch; using the fourth guide-wire to advance a third balloon catheter, which comprises a third catheter tube and a third balloon, to the site of the previously deployed first stent in the first branch; inflating the second and the third balloons, whereby the second stent is deployed in the second branch; and deflating the second and third balloons and removing them from the internal volume. In another embodiment, the method comprises the steps of accessing the internal volume of an artery, which is divided into a first and second branch; inserting a balloon catheter, which comprises a first catheter tube, a first balloon and a first stent, into the internal volume; using a first guide-wire to advance the balloon catheter to a site of plaque buildup substantially near the two branches; positioning the balloon catheter substantially at the center of the plaque buildup in a first branch; advancing a second guide-wire through the first catheter tube to a position substantially near the center of the first balloon; using at least one metal radio-opaque marker on the balloon catheter as a guide to align openings in the first catheter tube, the first balloon and the first stent, respectively, with an opening to the second branch; advancing the second guide-wire into the second branch through the openings in the first catheter tube, first balloon and first stent; inflating the first balloon to deploy the first stent; deflating the first balloon and withdrawing the first balloon and first catheter tube while leaving the first and second guide-wires in the first and second branches; advancing a second balloon catheter, which comprises a second catheter tube, a second balloon and a second stent, to the second branch through the first stent; advancing a third balloon catheter, which comprises a third catheter tube and a third balloon, to the site of the previously deployed first stent in the first branch; inflating the second and the third balloons, whereby the second stent is deployed in the second branch; and deflating the second and third balloons and removing them from the internal volume.

DETAILED DESCRIPTION

In the following paragraphs, the present invention will be described in detail by way of example with reference to the attached drawings. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention. As used herein, the “present invention” refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the “present invention” throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s).

A. Devices of the Present Invention

Referring now to the figures, which are illustrative of multiple embodiments of the present invention only and are not for purposes of limiting the same,FIG. 1depicts a device in accordance with one embodiment of the present invention. The balloon catheter illustrated inFIG. 1includes a hollow catheter tube10with a proximal end12and a distal end14. Preferably, the proximal end12of the catheter tube10is rigid torsionally so that it can transmit rotation from its proximal end12to its distal end14yet flexible enough to bend as necessary to follow the curve of the patient's arteries. It is also preferred that the distal end14of the catheter tube10is capable of bending so that it can be steered and directed as it is advanced through the patient's arteries. Accordingly, the catheter tube10may be made from any standard material suitable for such purposes, such as a suitable silicone, polyurethane or polyethylene. The catheter tube10may have any suitable length and preferably has a length of about 160 cm. The catheter tube10may have any suitable internal diameter, and preferably has internal diameter of about 0.33 mm (1 French).

A conventional adapter (not illustrated) may be attached to the proximal end12of the catheter tube10to facilitate attachment of the catheter tube10to an inflation/deflation device (not illustrated). The inflation/deflation device may be any suitable device known in the art, and preferably is a syringe. The catheter tube10may also include an inflation lumen (not illustrated) extending between the proximal end12of the catheter tube10and the balloon30. The inflation lumen delivers fluid to the balloon30to inflate the balloon30.

FIG. 1further illustrates a device according to the present invention, including a guide-wire20, with a proximal end22and a distal end24, which may be advanced inside the hollow catheter tube10. The guide-wire20may have any suitable cross-section and preferably has a cross-section of about 0.014 in. The guide-wire20may have any suitable length. The present invention may also include a second guide-wire40, a third guide-wire200, and a fourth guide-wire210, each of which may have any suitable length, any suitable cross-section, and preferably has a cross-section of about 0.014 in. Second guide-wire40is advanced through opening42in the proximal end12of the catheter tube10. Guide-wire20, second guide-wire40, third guide-wire200, and fourth guide-wire210need not have identical or substantially identical specifications, so long as each has suitable specifications.

The balloon catheter includes a balloon30(illustrated in its inflated configuration inFIG. 1), which has a proximal end32and a distal end34, and which substantially surrounds the distal end14of the catheter tube10. The balloon30may be made of any suitable material, such as a flexible polymer (e.g., nylon or polyethylene), and preferably is fabricated from a semi-compliant material that can be upsized to a larger diameter at pressure greater than 10 atmospheres (mm Hg) allowing the balloon30to inflate from a collapsed configuration to an expanded configuration and also to deflate after inflation to selectively return to the collapsed configuration. The pressures, however, at which the balloon30inflates and deflates may vary in accordance with the particular catheter and balloon design requirements. The balloon30may have any suitable length. The balloon30may have any suitable diameter and preferably has a diameter between about 3.0 mm and about 4.5 mm. In other embodiments, the balloon30may not substantially surround the distal end14of the catheter tube10, but instead may include a hollow shaft (not illustrated), which has a similar interior diameter to the catheter tube10and which bonds to the distal end14of the catheter tube10by adhesive or heat bonding.

FIG. 1illustrates how the distal end14of the catheter tube10or hollow shaft includes an opening18large enough to accommodate the guide-wire20. The opening18is preferably round, but may be any suitable shape or configuration. The round opening18may have any suitable diameter and preferably has a diameter of about 0.4 mm. The distal end14of the catheter tube10includes at least one metal radio-opaque marker38near the opening18in the catheter tube10or hollow shaft, and preferably includes two metal radio-opaque markers38on opposite sides of the opening18as illustrated inFIG. 1. The metal can be any suitable metal, such as platinum or gold, and preferably is gold. A doctor can use the metal radio-opaque markers38to verify the position of the opening18in the catheter tube10relative to the opening of the arterial side branch so that they are properly aligned for advancement of the second guide-wire40into the side branch as explained further below.

With further reference toFIG. 1, the balloon30also includes an opening36on one side between the proximal32and distal end34, which can be aligned to expose the opening18in the catheter tube10or hollow shaft and the metal radio-opaque markers38. Preferably, the opening36is substantially centered between the proximal end32and distal end34. It is also preferred that the opening36is rectangular or wedge shaped, but it may be any other suitable shape or configuration. The opening36may have any suitable length and preferably has a length of about 3.0 mm. The opening36may have any suitable depth and preferably has a depth of about 1.5 mm.

As illustrated inFIGS. 2A-C, the device according to the present invention also includes a stent50. With the exception of the opening54and the metal radio-opaque markers52, as discussed below, the stent50of the present invention may have the same or a similar structure as other standard stents known in the industry (e.g., the ACS Multilink stent). For example, as illustrated inFIG. 3(prior art), a conventional stent in its expanded form may include a multiplicity of longitudinally extending sets of zig-zag struts60. The stent50housing may also be fabricated from any suitable material and by any method known in the art, and preferably is fabricated by laser machining of a cylindrical, thin-walled stainless steel tube.

The stent50housing includes an opening on its proximal56and distal ends58, as well as an opening54on one side of the housing between the proximal56and distal ends58. The opening54may be any suitable shape, but is preferably elliptical so that it can more easily be expanded without fracturing the stent50. The opening54may be any suitable distance from the proximal56and distal ends58of the stent50, but is preferably equidistant from the proximal56and distal ends58of the stent50. The diameter of the opening54may be between about 2.0 mm and about 4.0 mm, and preferably is about 3.0 mm so that it can accommodate the passage of a standard balloon.

In one embodiment, as illustrated inFIGS. 2A-C, the stent50housing is cylindrical in shape and is attached to the balloon30by any suitable method, but preferably it is crimped on the balloon30so that opening54is aligned with the opening36in the balloon30. Accordingly, the stent50housing is positioned on the balloon30so that opening54in the stent50aligns with the opening36in the balloon30and the opening18in the catheter tube10, and exposes the catheter tube's10metal radio opaque markers38, allowing the doctor to align the device with the arterial side branch80for advancement of a second guide wire40that is used to deploy a second stent110in the arterial side branch80.

The stent50housing may also include one or more metal radio-opaque markers52. The one or more radio-opaque markers52may facilitate alignment of the opening54in the stent50with the openings18and36in the catheter tube10and balloon30, respectively, and the center of the side branch80. The stent50may have any suitable number of metal radio-opaque markers52, and preferably has three metal radio-opaque markers52. The metal radio-opaque markers52may be any suitable structure and are illustrated as round or semispherical beads. Although the metal radio-opaque markers52may be arranged in any suitable pattern, it is generally preferred that the markers52are arranged at 90 degree intervals relative to the opening54around the circumference of the stent50as illustrated inFIGS. 2A-C. Stated differently, it is generally preferred that a metal radio-opaque marker52is disposed 180 degrees from the center of opening54and that additional metal radio-opaque markers52are disposed 90 degrees from the center of opening54and 180 degrees from one another. The metal radio-opaque markers52may be attached to the stent50by any suitable method known in the art, such as welding. The metal can also be any suitable metal, such as platinum or gold, and preferably is gold.

B. Methods of the Present Invention

In addition to the devices described above, the present invention also includes methods of using the devices of the present invention and any other suitable devices in the treatment of bifurcation lesions. As shown inFIG. 4, the illustrated bifurcated artery has a main branch70and a side branch80. The main branch has a proximal portion72and a distal portion74. The artery has plaque buildup90starting near the proximal end72of the main branch70and extending around the bifurcation and into both the side branch80and the distal end74of the main branch70.

As an introductory matter, the methods according to the present invention involve accessing the internal volume of an artery of interest. This is generally done by cleaning the insertion area with a sterilized solution, covering it with sterile drapes, numbing it with a local anesthetic, making an incision and inserting a plastic sheath. The insertion area may be any suitable area, but preferably is the femoral artery. In some embodiments, the balloon catheter, which contains the balloon30and the stent50, may then be advanced through the sheath to the bifurcated artery with the plaque buildup. In other embodiments, progressively larger balloons may be used to enlarge the opening before advancing the balloon catheter, which contains the balloon30and the stent50.

As illustrated inFIG. 5, the guide-wire20is advanced from the catheter tube10, down into the main branch70and across the plaque buildup90so that its distal tip is positioned in the distal segment74of the main branch70. The balloon catheter, which contains the uninflated balloon30and the stent50, is advanced to the site of the plaque buildup90in the main branch70. The balloon30and stent50are then positioned at the center of the plaque buildup90in the main branch70. Once properly positioned, the balloon30is inflated to a suitable pressure, preferably 2-3 atmospheres. Once inflated, balloon30can accommodate a second guide-wire40, which is advanced through the catheter tube10.

The second guide-wire40is advanced from the proximal end12of catheter tube10to a position substantially near the center of balloon30.FIG. 5illustrates how, using the metal radio-opaque markers38and52as a guide, the balloon catheter is torqued to align the openings18,36and54in the catheter tube10, the balloon30and the stent50, respectively, with the opening of the side branch80. In an embodiment with three metal radio-opaque markers52, the stent is rotated until the two metal radio-opaque markers52that are disposed 90 degrees from opening54are positioned such that they appear superimposed when visualized, for example, by fluoroscopy. The stent50is then rotated such that the metal radio-opaque marker52disposed 180 degrees from opening54is lined up directly opposite side-branch80. This proper alignment permits advancement of the second guide-wire40into the side branch80, as illustrated inFIG. 6. In one embodiment, the second guide-wire40is advanced through opening42in the proximal end12of catheter tube10. Orthogonal views generated by any method known in the industry can be used to confirm advancement of the second guide-wire40into the side branch80. Preferred methods of visualization include fluoroscopy and cineangiography.

Once the second-guide wire40has been advanced into the side branch80through the openings18,38and54in the catheter tube10, the balloon30and the stent50, respectively, the balloon30is inflated deploying the stent50. The balloon30may be inflated for any suitable amount of time and preferably for about two minutes to press open the blockage and create a channel that increases blood flow through the artery. The balloon30may be inflated to any suitable pressure, preferably from about 9 to about 11 atmospheres. The patient may experience chest pain during the procedure because the artery is completely blocked while the balloon30is inflated.

In some embodiments, once the stent50is deployed, the balloon30is deflated and a third guide-wire200is advanced outside of the balloon30in the main branch70and into the side-branch80. The balloon catheter is withdrawn along with guide-wire20and second guide-wire40, leaving the third guide-wire200in the main branch70and side branch80. Using the third guide-wire200, a second balloon100and stent110are advanced into the side branch80through the previously placed stent50. The stent110may have any suitable diameter and preferably has a diameter of about 3.0 mm. Stent110may be similar to, or different than, stent50. In some embodiments, instead of advancing a third guide-wire200into side-branch80, second guide-wire40is not removed and is reused in advancing second balloon100and stent110.

In some embodiments, a fourth guide-wire210is then advanced through stent50and into the distal portions of main branch70. A third balloon120is then advanced over fourth guide-wire210and positioned at the site of the previously deployed stent50in the main branch70. Both the second balloon100and the third balloon120are deployed substantially simultaneously, in the side branch80and the main branch70, respectfully, preferably using the “kissing balloon” technique as described below. This also serves to deploy the second stent110in the side branch70. In some embodiments, instead of advancing a fourth guide-wire210into branch70, guide-wire20is not removed and is reused in advancing third balloon120.

FIG. 7illustrates the kissing balloon technique. The illustrated bifurcated artery has a main branch70and a side branch80. The main branch has a proximal portion72and a distal portion74. The artery has plaque buildup90starting near the proximal end72of the main branch70and extending around the bifurcation and into both the side branch80and the distal end74of the main branch70. In the kissing balloon technique illustrated inFIG. 7, a pair of balloon catheters are inserted through the main branch70with one of the balloons100and120being disposed in each of the side branch80and the distal end74of the main branch70. The proximal ends of the balloons100and120typically remain in the main branch70and contact or “kiss” each other.

The balloons100and120are then deflated and removed, while the stents50and110remain permanently in place to hold the artery open. In some embodiments, the stents50and110are drug-eluting stents coated with an agent that inhibits restenosis. In one embodiment, the agent is an antibiotic called sirolimus (also called rapamycin), which is slowly released into the artery. Sirolimus is a cytostatic drug, which inhibits cell growth and division, and T-Cell activation and proliferation. T-cells initiate an inflammatory response that commonly follows implantation, and inflammation can lead to restenosis. The agent may be released into the artery for any suitable number days after implantation, and preferably for about 30 days after implantation. Clopedigrol (Plavix®) may also be prescribed for the patient. Clopedigrol is a potent aspirin-like medicine that reduces the risk for development of blood clots inside the stents50and110during the first few weeks after implantation.

After the procedure, the sheath or sheaths are removed and pressure is applied to the area—usually for five to fifteen minutes—to close off holes in the arteries made by insertion of the sheaths. A gauze dressing is taped to the area and the patient must lie on their back for four to six hours, while normal blood clotting seals the holes in the arteries. Alternatively, holes made in the femoral artery can be sealed immediately after catheterization by stitching them closed or plugging them with collagen. If either of these methods is used, the patient may be able to sit up within an hour of the procedure and begin walking within several hours.

In some embodiments, the above described or other suitable balloon angioplasty procedure may be performed after removal of arterial plaque by atherectomy. The atherectomy may be of any suitable type, and preferably is either laser, rotational, directional or transluminal extraction atherectomy. In laser atherectomy, a laser attached to the tip of a thin flexible catheter emits short pulses of light that ablate plaque. The patient may be injected with tagged antibodies that attach to the plaque and “guide” the laser pulses to the plaque, avoiding damage to the artery walls with the laser beam. Rotational atherectomy, or rotablation, may be used to treat arteries with very long, calcified or solid blockages or arteries with plaque that has regrown inside a stent by using a burr, or surgical drill bit, tipped with very fine diamond chips to pulverize the plaque, which is then suctioned out continuously. Directional atherectomy employs a catheter tipped with a device consisting of a cup-shaped blade and a container. The blade cuts away plaque from the artery and deposits it into the container. When the catheter and device are withdrawn, the plaque is removed from the body. Transluminal extraction atherectomy involves a special catheter tipped with a hollow tube and rotating blades. As the blades cut plaque away from the arterial wall, the debris is suctioned out of the body through the tube.

Thus, it is seen that devices and methods for treating bifurcation lesions are provided. One skilled in the art will appreciate that the present invention can be practiced by other than the various embodiments and preferred embodiments, which are presented in this description for purposes of illustration and not of limitation, and the present invention is limited only by the claims that follow. It is noted that equivalents for the particular embodiments discussed in this description may practice the invention as well.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not of limitation. Likewise, the various diagrams may depict an example architectural or other configuration for the invention, which is done to aid in understanding the features and functionality that may be included in the invention. The invention is not restricted to the illustrated example architectures or configurations, but the desired features may be implemented using a variety of alternative architectures and configurations. Indeed, it will be apparent to one of skill in the art how alternative embodiments may be implemented to achieve the desired features of the present invention. Also, a multitude of different constituent part names other than those depicted herein may be applied to the various parts of the devices. Additionally, with regard to operational descriptions and method claims, the order in which the steps are presented herein shall not mandate that various embodiments be implemented to perform the recited functionality in the same order unless the context dictates otherwise.