Varying-diameter vascular implant and balloon

Variable diameter vascular implant and balloon

FIELD OF THE INVENTION The present invention relates generally to implantable therapeutic devices and specifically to intravascular implants of varying diameter.

BACKGROUND OF THE INVENTION

Endovascular implants or stents are commonly used in the treatment of arterial stenoses and other unwanted constrictions of body passages. Stents typically comprise a metal coil or mesh. An arterial stent, for example, is passed through the vascular system to the point of stenosis in an artery. When the stent is in place, it is expanded to force the artery to open to the desired diameter. Typically, the stent comprises a plastics material which is inserted using a balloon catheter within the stenosis point in a compressed state. The stent is then expanded by balloon inflation. An apparatus and method for holding a stent in a balloon catheter is described, for example, in US Patent 6,364,870.

On the other hand, there are some procedures in which stent implants are required to constrict the diameter of a blood vessel. For example, Ruiz describes an endoluminal stent that has adjustable constriction in US 6,120,534. The stent comprises a deformable mesh having a conical portion and a constriction region which forms a flow limiting constriction. The stent is delivered and displaced within a blood vessel. The constriction region of the mesh is then selectively widened to adjust the flow impedance in the vessel. In particular, Ruiz describes the use of his stent to reduce blood flow in the pulmonary artery as a palliative treatment for children with complex congenital heart malformations.

58 1,587,449 / ΡΤ

Other types of constriction stents and applications of such stents are described by Shalev et. al. in PCT Patent Publication WO100 / 72239. In particular, this publication describes the use of a coronary sinus flow reduction implant to promote angiogenesis in the heart tissues. The implant is inserted through the catheter through a central vein, such as the jugular vein, and brought into the coronary sinus. Alternatively, the implant may be installed in one or more of the coronary veins. Once the implant is in place, it is allowed to expand elastically or to expand plastically using a balloon.

Examples of high pressure balloons traditionally used in angioplasty and recent developments in balloon design are described in an article entitled, Applications of High-Pressure Balloons for Medical Device Industry, Medical Device and Diagnostic Industry Magazine (September 2). . Recent material improvements, balloon shape design and manufacturing technology include, among others, additional lengths, ultra thin walls (to be minimally invasive and of a smaller profile), variable diameters along the length of the balloon, tailor-made shapes and tapered ends and angles.

The specific shape of a high pressure balloon may be dictated by the peculiarities of an anatomical site and / or the requirements of the treatment process. For example, a dog bone balloon may be used for localized delivery of medication to prevent systemic intravenous administration. The ends of the balloon may have the same or different dimensions, depending on the shape of the cavity or vessel. When inflated, the ends seal the area to be treated, and the medication is infused through a hole or series of holes in the narrow central section of the balloon. High pressure balloons are also used for positioning diagnostic devices within vessels or body cavities for ultrasonic imaging and other techniques. Instead of having a complicated conduction or positioning mechanism at the end of a catheter, it can be used

58 1 587 449 / ΡΤ a high pressure balloon for either centering or deflecting the device, precisely positioning it as required.

EP 1 254 644 describes a stent and displacement arrangement including a balloon which is not cylindrical when inflated and thereby causes the stent to assume a non-cylindrical expanded state. In this way, the shape of the stent may suit the geometry of the target zone in a blood vessel while still pressing outwardly against the vessel wall along the entire length of the stent.

US 2002/0183777 describes an angioplasty catheter having a funnel-shaped opening at the distal end to receive a deflated balloon.

US 6,120,534 describes a stent with deformable constrictions for regulating blood flow.

SUMMARY OF THE INVENTION

The present invention provides apparatus for treating a patient's coronary sinus as set forth in claim 1. New devices and methods for displacing an implant in a body passage, such as the coronary sinus, which vary in diameter from one to the other are described herein. long of its length. In stent implantation known in the art, a balloon is typically used, the diameter of which is more or less uniform throughout its length. Therefore, if the diameter of the body passageway varies along the length of the stent, the end of the stent in the widest area of ​​the passageway may be insufficiently expanded so that the stent is not securely attached. Alternatively, the opposite end of the stent in the narrowest region of the body passageway may be substantially expanded beyond the natural diameter of the passageway causing the tissue to deform.

In embodiments of the present invention, on the other hand, the balloon, which is used to expand the implant, has a diameter that varies along its length from a

1 587 449 / ΡΤ such as to roughly match the variable diameter of the body passage. When the implant is in place within the body passage, the balloon is inflated to plastically expand the implant so that the expanded implant diameter roughly coincides with the total diameter of the body passage at two or more points, typically at both ends of the implant. (In the case of a constricted implant, as it may be used in the cardiac sinus to partially constrict blood flow through it, a part of the implant, typically a central part, may remain unexpanded.) As a result, the implant is held securely in place without undue deformation of the body passageway walls.

The implant and balloon, and the insertion method described herein, are particularly useful for restricting coronary sinus blood flow, as described in the above-mentioned PCT publication and US patent application 09 / 534,968, which has been assigned. to the assignee of this patent application and the disclosure of which is incorporated herein by reference. The principles of the present invention, however, may be similarly employed in displacing implants into other veins and arteries of varying diameter, as well as in other medical applications.

Accordingly, a method for displacing an expandable implant in a body passageway of variable diameter, which includes:

selecting a balloon having a radial dimension that varies when the balloon is inflated according to the varying diameter of the body passage;

inserting the balloon in a deflated state into the body passage with the expandable implant adjusted radially around the balloon; and inflating the balloon to cause the implant to open, in response to the variable radial dimension of the balloon, to an expanded shape that approximately coincides with the variable diameter of the body passageway, thereby securing the implant to the body passageway.

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Typically, the method includes attaching the balloon to a catheter and passing the balloon into the body passage using the catheter.

The body passage is a coronary sinus of a patient, and the balloon passage includes:

guiding the catheter through a vascular path into a patient's right atrium; and conducting the catheter into the right atrium to position the balloon and implant into the coronary sinus.

Typically, the selected balloon has distal and proximal ends, and the radial dimension of the distal end is substantially smaller than the radial dimension of the proximal end. In one example, the selected balloon has a generally conical profile.

In other embodiments, the selected balloon includes a proximal segment having a first diameter and a distal segment having a second diameter which is substantially smaller than the first diameter. In one of these embodiments, at least one of the segments terminates in a bulb having a third diameter that is larger than the diameter of at least one of the segments. In another embodiment, the selected balloon includes a neck between the proximal and distal segments, the neck having a third diameter that is smaller than the second diameter.

The method may also include deflating the balloon after the implant has been opened, withdrawing the deflated balloon in a distal direction within a tubular fitting, and withdrawing the balloon-containing fitting from the body passageway. Removal of the deflated balloon in the distal direction may include widening a distal end of the tubular fitting to receive the balloon.

Additionally or alternatively, balloon selection may include measuring the diameter of the body passage at multiple points along the passage, and choosing the balloon

58 1 587 449 / ΡΤ from a selection of available balloons to adjust the radial dimension of the balloon to the measured diameter of the body passage.

When the body passage is a coronary sinus of a patient, the choice of balloon includes fitting the balloon to a region of coronary sinus enlargement adjacent to a patient's right atrium. Typically, the implant includes a constriction, and balloon inflation includes expansion of the implant to match the variable diameter of the coronary sinus except in the constriction to inhibit blood flow through the coronary sinus.

Also described herein is an apparatus for treating a body passageway of varying diameter which includes:

a balloon having a radial dimension that varies when the balloon is inflated according to the varying diameter of the body passage; and an expandable implant, radially adjusted around the balloon, so that when the balloon is inflated into the body passageway, the implant opens in response to the variable radial dimension of the balloon with an expanded shape that approximately coincides with the variable diameter of the body passage, thus securing the implant in the body passage. Typically, the apparatus includes a catheter which is adapted to displace the balloon and implant into the body passageway.

Typically, the balloon is one of a plurality of balloons having varying radial dimensions, which are selectable for insertion into the body passageway, depending upon a measured diameter of the body passage at multiple points along the passageway.

The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together as the drawings, in which:

EP 1 587 449 / EN

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1A is a schematic figurative view of an exemplary implantable device in an unexpanded position in accordance with one embodiment of the present invention;

Fig. 1B is a schematic schematic view of the exemplary implantable device shown in Fig. 1A in an expanded position;

Fig. 2 is a schematic figurative view of an exemplary stent balloon, but is not an embodiment of the present invention;

Fig. 3 is a schematic view of the vascular pathway for a human heart having a coronary sinus;

Fig. 4 is a detailed schematic view of the coronary sinus following expansion of a balloon implantable device shown in Fig. 2, in accordance with one embodiment of the present invention;

Figs. 5 to 7 are schematic figurative views of exemplary stent balloons, Figs. 6 and 7 in accordance with alternative embodiments of the present invention;

Fig. 8 is a schematic figurative view of a deflated balloon within a stent and an accessory used to remove the deflated stent balloon according to one embodiment of the present invention; and Figs. 9A and 9B are detailed schematic views showing the steps in a process of removing a deflated stent balloon in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference is now made to Figs. 1A and 1B which are schematic figurative views of an implantable device

Exemplary 1 587 449 /, 100, in a constricted state and an expanded state, respectively, according to one embodiment of the present invention. Device 100 is adapted for particular use in restricting blood flow through the coronary sinus, as described in the above-mentioned PCT publication WOO1 / 72239 and US patent application 09 / 534,968. Alternatively, devices in accordance with the principles of the present invention may be implanted anywhere in the vascular system as well as in other body passages. For the sake of simplicity and clarity, however, and not limitation, embodiments of the present invention are described hereinafter with reference to implantation of flow constriction devices into blood vessels of varying diameter, such as the coronary sinus.

Device 100 has a tubular overall construction with two expandable ends 110 and a central section 120. Further, alternatively or additionally, device 100 may comprise a mesh or coil as is known in the art. Device 100 comprises a deformable material, such as a suitable metal or plastic, as is known in the art of implantable devices, which is sufficiently flexible to be expanded by inflating a balloon (shown in Fig. 2) but strong enough to retain its shape when it is displaced and expanded within a body passageway, just as stents known in the art. In addition, the shape of the device 100, combined with its flexibility, allows the device to be compactly displaced as shown in Fig. 1A and subsequently expanded as shown in Fig. 1B, either partially or completely within the breast. coronary. A non-expandable constriction member 125 may be fixed around a central section 120 of device 100 to ensure that the central section remains constricted as shown in Fig. 1B.

A flexible sleeve (not shown) may be attached around or within the device 100 to prevent blood from passing through the openings on the sides of the device when it is implanted, so that substantially all of the blood passes through through the central section 120. Typically, the sleeve comprises a fabric

Biocompatible material such as Gore-Tex or Dacron, which is sewn or fixed differently to the device 100. Alternatively, other sleeve materials such as thin plastics or plastics may be used. eraser. Constricting member 125 is fitted around the sleeve over central section 120. As can be seen from Fig. IB, the effect of the constricting element is to maintain a reduced predetermined diameter of the device 100 in the central section region 120 by defining a lumen with a constricted central section diameter. Constraining member 125 may comprise a closed ring made of metal or plastic, or it may alternatively comprise a wire.

Reference is now made to Fig. 2, which is a schematic diagrammatic view of an exemplary high pressure stent balloon 200 used to expand device 100. The balloon 200 has a generally conical shape having a rounded distal end and 210 and an enlarged proximal end 220. The balloon terminates at a conicality 225, which forms a continuation of the channel portion of a catheter (shown in Fig. 4), through which the balloon is inflated and deflated. The balloon 200 typically comprises a non-elastic high pressure material as is known in the art which is designed to apply an outward radial force when inflated as described above in the Medical Device & Diagnostic Industry Magazine article above. In general, device 100 is displaced into a body passageway with deflated balloon 200 concentrically contained within it. The shape of the balloon 200 is adapted such that when the balloon is inflated it expands the device 100 and positions it within a preselected variable diameter body passage, as explained hereinafter.

Balloon 200 is typically made of materials such as poly (ethylene terephthalate) (PET) or nylon. Some considerations for the manufacture of balloon 200 using these materials include: high tensile strength, allowing high operating pressures; the thin wall formation of the balloon, allowing the precise shape of the balloon and the low profile; and low elongation (otherwise known as low recovery). This last consideration ensures

That the balloon 200, when fully under pressure, has relatively unchanged dimensions which ensure that the device 100 is not uncontrollably expanded in a passage of the body. Low elongation also means that the balloon 200 will not be overexpanded at each end of the device 100 and that the balloon expansion force is generally directed radially to expand the device 100 substantially against the walls of the body passageway.

Reference is now made to Fig. 3, which is a schematic view of the vascular pathways for a human heart 300, which has a coronary sinus 302. Coronary sinus 302 comprises a junction of the three largest cardiac veins (not shown), and renders it progressively widens as it empties into a right atrium 306. The diameter of the coronary sinus 302 increases as it opens outward to the right atrium 306.

To implant device 100, the device is passed through the vascular system to a preselected position in coronary sinus 302 using a suitable percutaneous catheter (shown in Fig. 4). Suitable catheterization methods for this purpose are known in the art. During the insertion procedure, device 100 is maintained in the unexpanded configuration shown in Fig. 1A, so that its outer diameter, which is substantially smaller than the blood vessels through which it must pass, allows the attending physician to pass the device through the blood vessels. Typically, the physician inserts the catheter through a jugular vein 310 or a subclavian vein 312, and then guides the catheter into a right atrium 306 through an upper vena cava 308. Another insertion point is through a femoral vein 322, and the catheter is then guided into a inferior vena cava 324 and into the right atrium 306. Once in the right atrium 306, the physician leads the catheter through an acute curve to to guide the device 100 into the coronary sinus 302.

Reference is now made to Fig. 4, which is a detailed schematic view of the coronary sinus 302 following the expansion of the device 100 by the balloon 200, according to one embodiment.

1,587,449 / embodiment of the present invention. A catheter 410 as described hereinabove is used to position the device and balloon in the coronary sinus 302 through the right atrium 306. The balloon 200 is then inflated through catheter 410 and takes a general shape as shown in FIG. figure. The physician may choose the shape of the balloon 200 in advance to optimally match the given dimensions of the coronary sinus of the patient in question. These dimensions can be determined, for example, by fluoroscopic imaging while injecting a contrast agent into the coronary sinus as is known in the art.

When balloon 200 is inflated, it applies a radial force to plastically expand device 100 against the walls of coronary sinus 302. As shown in the figure, due to the variable diameter of balloon 200, the distal end of device 100 is only partially expanded. while the proximal end of device 100 is more fully expanded, reflecting the variable diameter of coronary sinus 302. As indicated above, the balloon 200 does not expand at each end of the device 100. The distal end 210 of the balloon may protrude slightly from the distal end of the device 100. Similarly, the enlarged proximal end 220 and the taper 225 of balloon 200 may protrude from the proximal end of device 100. Because the shape of the device 100 fits the natural shape of the coronary sinus, both the distal and proximal ends of the device press outwardly against the coronary sinus wall with approximately equal force. Thus, device 100 is securely locked in place without exerting excessive pressure against the coronary sinus wall at any point. The central section 120, however, remains constricted due to the presence of the constricting member 125 or other means provided for this purpose.

Once device 100 has been satisfactorily positioned and expanded, balloon 200 is deflated and withdrawn from device 100. Catheter 410 and balloon 200 are then withdrawn from the body. Device 100 remains in place to restrict blood flow through coronary sinus 302. As indicated above, this flow restriction

ΕΡ 1 587 449 / ΡΤ increases the blood pressure in the coronary veins, thereby favoring angiogenesis. Device 100 may be left in place indefinitely, substantially in the form shown in Fig. 4. Alternatively, it may be desirable in some cases to eliminate the flow restriction caused by the device. In such cases, a catheter with a suitable cutting tool may be inserted percutaneously at the location of the device, and the cutting tool may then be used to cut the constricting member 125 or the central section 120. A balloon such as the balloon 200, may then be reinserted through the catheter into device 100 and the balloon may then be inflated to open section 120.

While in the examples described above, device 100 and balloon 200 are shown to have certain particular shapes, alternative shapes and shapes of these elements, which will be apparent to those skilled in the art, are considered to be within the scope of the present invention. . Similarly, the balloons of the general type described above may be used to provide not only device 100 but also other implantable devices for implantation into other body passages of varying diameter, as otherwise known in the art. Furthermore, while the catheter shown herein provides convenient means for delivering implantable devices according to the present invention, the balloons according to the present invention may also be used in conjunction with other means for displacing implants, including both minimally invasive (typically percutaneous) and invasive (ie surgical) types.

For example, Figs. 5 to 7 are schematic figurative views of balloons 500, 600 and 700 which may be used in place of balloon 200, Figs. 6 and 7 according to alternative embodiments of the present invention. Instead of the conical overall profile of the balloon 200, these alternative balloons comprise a wide proximal segment 510 and a narrow distal segment 520. The proximal and distal segments are generally cylindrical and have respective different diameters. Alternatively, the proximal and distal segments may have trapezoidal profiles. For stent implantation in the

These coronary sinuses are typically about 30 mm long, and have diameters of about 10 mm in the wide segment and 7 mm in the narrow segment. Alternatively, larger or smaller dimensions may be used depending on the application requirements and the physiological characteristics of the patient.

In balloon 600, the narrow segment 520 ends distally in a bulb 610, which is wider than the narrow segment. For example, if narrow segment 520 is 7 mm in diameter, bulb 610 may have a diameter of about 8 mm. The bulb assists in opening the upstream end 110 of the stent to secure the stent more securely to the coronary sinus (or other body passage). Additionally or alternatively, the broad segment 510 may terminate proximally in a bulb-like manner.

The balloon 700 comprises the narrow neck 710 between segments 510 and 520. Typically, the neck is about 3 mm in diameter, although smaller or larger dimensions may also be used. Neck 710 fits within central section 120 of stent 100 during stent inflation. It thus prevents balloon 700 from exerting pressure against the non-expanding constricting member 125, and is also useful for facilitating the removal of the stent balloon after the stent implantation procedure is completed.

Fig. 8 is a schematic figurative illustration showing the use of a tubular fitting 820 for removing balloon 200 from the body in accordance with one embodiment of the present invention. In this embodiment, an operator, typically a physician, inserted a guidewire 800 through a patient's vascular system into the coronary sinus using techniques known in the art. Stent 100 and balloon 200 were passed along wire 800 into the coronary sinus, and balloon 200 was inflated to expand the stent to appropriate dimensions. The balloon had an annular cross-section to fit along wire 800, and is inflated and deflated through an annular tube 810. At the stage of the procedure shown in Fig. 8, balloon 200 had been deflated (of equal size). mode through the

1 587 449 / ΡΤ tube 810), and will now be withdrawn along wire 800 from the patient's body by pulling tube 810 proximally out of the body.

The inventors have found that under these circumstances, it is sometimes difficult to extract balloon 200 from stent 100 and through the vascular system. Therefore, to facilitate balloon extraction, the operator inserts the attachment 820 along the wire 800 to a position very close to the balloon 200, and then removes the balloon proximally into the attachment. Once the balloon is retained within the 820 attachment, the balloon containing attachment can be easily removed from the body. Similar types of accessories and methods may be used for inserting and extracting a balloon along other types of guides, such as a monorail guide, as is known in the art.

For these purposes, the fitting 820 typically comprises a small diameter tube, for example about 2.8 mm, with a length of about 500 mm. The tube should be flexible enough to pass through the vascular system, but rigid enough not to deform significantly when the balloon 200 is pulled into it. Accessory 820 may comprise, for example, polyurethane or another biocompatible plastic material having a wall thickness of about 0.4 mm. An additional catheter or other insertion tube (not shown in the figures) may be attached to the proximal end of the fitting 820 for use in advancing the fitting adjacent balloon 200, and then pulling the fitting and balloon out of the body. .

Similar techniques and accessories may be used to insert and remove balloons in other ways, such as those shown in Figs. 5 to 7.

Figs. 9A and 9B schematically show details of the distal end of fitting 820 and its use in capturing balloon 200, in accordance with one embodiment of the present invention. In this embodiment, the distal end of fitting 820 is splined or perforated along splined lines 900. Splined lines are drawn by opening

58 1 587 449 / ΡΤ tears with sufficient outward radial force. A reinforcing ring 910 limits the extent of the tear to a predetermined length from the distal end of the fitting, typically about 3.5 mm. Ring 910 may comprise metal or other radio opaque material, so that the location of accessory 820 is visible on x-ray images.

In operation, the attachment 820 is advanced distally, as shown by arrow 915 in Fig. 9A, until the spline, the distal end of the attachment slides within the expanded proximal end of stent 100. If balloon 200 is sufficiently flaccid therein. At this point, it will be possible to pull the balloon into the fitting 820 by simply pulling the tube 810 proximally as indicated by an arrow 930 in Fig. 9B. If, however, there is residual pressure in the balloon or inherent rigidity of the balloon material, the balloon may tear along the spline lines 900, causing the distal end of attachment 820 to widen through the multi-flap opening 920. These flaps widen outward to create a funnel structure at the distal end of the fitting. This structure can be radially supported by stent 100 as shown in the figure. The funnel assists in the gradual compression of the balloon as it is pulled inward in the direction of arrow 930 so that the balloon slides smoothly into the attachment 820. Other means for widening the distal end of the attachment 820 may, in particular. alternatively be provided, as will be apparent to those skilled in the art.

It will be appreciated that the embodiments described above are cited as an example, and that the present invention is not limited to what has been shown and described herein above. Instead, the scope of the present invention includes both combinations and sub-combinations of the various features described hereinabove, as well as variations and modifications thereof which may occur to persons skilled in the art upon reading the foregoing description. which were not presented in the prior art.