US20040078072A1 - Delivery system for a stentless valve bioprosthesis - Google Patents

Abstract

The current invention discloses a catheter and a method for delivering a stentless bloprosthesis in a body channel, the method comprising percutaneously introducing a catheter into the body channel, wherein the catheter contains said stentless bloprosthesis at a retracted state; and disengaging said stentless bioprosthesis out of a distal opening of the catheter by a pulling mechanism associated with the catheter structure.

Description

RELATED APPLICATIONS
• This application claims priority to U.S. Utility application Ser. No. 09/853,463, filed May 10, 2001, the entirety of which is hereby incorporated by reference.[0001]
TECHNICAL INVENTION
• The present invention generally relates to a tubular prosthesis and methods for delivery into a body channel. More particularly, the present invention relates to an improved delivery system for delivering a stentless bioprosthesis comprising a collapsible elastic valve or a biological graft at a desired anatomical site of the body channel for implantation.[0002]
BACKGROUND OF THE INVENTION
• A prosthetic heart valve may be used to replace a diseased natural heart valve in a human patient. Similarly, a prosthetic venous valve may be used to replace a dysfunctional natural venous valve in a patient. Mechanical heart valves typically have a rigid orifice ring and rigid hinged leaflets coated with a blood compatible substance such as pyrolytic carbon. Other configurations, such as ball-and-cage assemblies, have also been used for such mechanical valves. A mechanical heart valve cannot be retracted radially and delivered by a catheter-based delivery system.[0003]
• In contrast to mechanical heart valves, bioprosthetic heart valves comprise valve leaflets formed of biological material. Many bioprosthetic valves include a support structure, or stent, for supporting the leaflets and maintaining the anatomical structure of the valve. Stented bioprosthetic valves generally are prepared by chemically cross-linking a retrieved pig's heart valve, followed by attaching it to a stent. The stent provides structural support to the valve and, with a sewing cuff, facilitates attachment of the valve to the patient by suturing. Gabbay in U.S. Pat. No. 5,935,163 discloses a natural tissue heart valve prosthesis with a substantially flexible annular ring to provide additional support, the entire contents of which are incorporated herein by reference.[0004]
• One of the major functions of stents is to serve as a framework for attachment of the valve and for suturing the valve into place in the human patient. Various stent designs have been implemented in a continuing effort to render valve implantation simpler and more efficient. Inevitably, however, a stent limits interactions with aortic wall dynamics and tends to inhibit natural valve movement. This results in post-operative transvalvular gradients with resultant additional work burden on the heart. In addition, a stent causes a reduction in size of the bioprosthetic valve that can be placed in a particular location, since the stent and sewing cuff occupy space that otherwise would be available for blood flow. Recently biodegradable stents are disclosed, for example, U.S. Pat. No. 5,895,420 to Mirsch II, et al. and U.S. Pat. No. 5,489,297 to Duran, to limit disadvantage of the valve stenting to a shorter time of implantation until it is biodegraded. Both patents are incorporated herein by reference.[0005]
• Some bioprosthetic valve manufacturers have attempted to develop methods and systems to ease the implantation of stented valves, including special catheter-based delivery system. Both of U.S. Pat. No. 5,840,081 and U.S. Pat. No. 6,168,614 to Andersen et al. disclose a minimally invasive percutaneous delivery system with a balloon catheter. A stented valve prosthesis is contractively mounted within a lumen of the catheter during delivery. At a desired anatomical site, the prosthesis is pushed out of the catheter tip and self expands. Lutter et al. reported an experimental study on percutaneous transluminal replacement of the aortic valve (81[0006]^stAmerican Association for Thoracic Surgery Program Book pp. 174, May 6-9, 2001, San Diego, Calif.). They concluded that aortic valve stents with a self-expandable metallic stent can be successfully implanted by transluminal catheter technique without the need of opening the chest.
• Porter in U.S. Pat. No. 5,064,435 discloses a catheter-based apparatus and methods for releasing a self-expandable prosthesis by a conventional pushing mechanism. The above-mentioned approaches are satisfactory for delivering a stented prosthesis having an external rigid support adapted for receiving the pushing force. A self expanding prosthesis often is preferred over a plastically deformed device. Resilient prosthesis can be deployed without dilatation balloons or other stent expanding means. A self-expanding prosthesis can be preselected in accordance with the diameter of the body channel or other anatomic site for fixation. While deployment requires skill in positioning the prosthesis, the added skill of properly dilating the balloon to plastically expand a prosthesis to a selected diameter is not required. Also, the self-expanding prosthesis remains at least slightly compressed after fixation, and thus has a restoring force which facilitates acute fixation.[0007]
• Stentless valves have demonstrated better hemodynamic function than stented valves. This is because a stentless valve is sewn directly into the host tissues, without the need for extraneous structure such as a sewing cuff. Such extraneous structures inevitably compromise hemodynamics. A stentless valve closely resembles a native valve in its appearance and function, and rely upon the patient's tissues to supply the structural support normally provided by a stent. Quintero et al. in U.S. Pat. No. 5,197,979, Nguyen Thien-Nhon in PCT W.O. No. 99/33412, and Vrandecic Peredo in PCT W.O. No. 00/00107 all disclose stentless valve structure and function, the entire contents of which are incorporated herein by reference.[0008]
• The main disadvantage to stentless valves has been in their difficulty of deployment and implantation, particularly in a catheter-based percutaneous route. With recent scientific advancements in robotics, instrumentation and computer technology, a minimally invasive catheter-based delivery system for a stentless bioprosthesis is imminent. There is currently a clinical need for deploying a tubular stentless prosthesis, such as a stentless valve or a vascular graft without a rigid support, into a body channel, preferably by a percutaneous approach. The catheter-based percutaneous delivery system as compared to an open-cavity surgery will greatly reduce the patient's hospital stay and improve recovery.[0009]
SUMMARY OF THE INVENTION
• It is an object of the present invention to provide a method for delivering a stentless bioprosthesis in a body channel, the method comprising percutaneously introducing a catheter into the body channel, wherein the catheter contains the radially elastic stentless bloprosthesis at a retracted state; and disengaging said stentless bloprosthesis out of a distal opening of the catheter by a pulling mechanism. In one embodiment, the pulling mechanism further comprises an engaging element coupling to a distal portion of the stentless bioprosthesis. In another embodiment, the method further comprises separating the stentless bioprosthesis from said engaging element.[0010]
• The stentless bioprosthesis of the present invention has the common characteristics of soft, collapsible radially, collapsible longitudinally, and without any rigid support onto or around the bioprosthesis.[0011]
• It is another object of the present invention to provide a catheter for delivering a tubular prosthesis to an anatomical site in a body channel, the catheter comprising an elongated delivery member located inside the lumen of the catheter, the elongated delivery member having an engaging element at the distal end of the elongated delivery member, wherein the engaging element is adapted for engaging and disengaging a distal portion of the tubular prosthesis. In one embodiment, the catheter further comprises a delivery mechanism at the handle that is coupled to the elongated delivery member. The delivery mechanism is adapted for pulling the distal portion of the tubular prosthesis out of the catheter shaft during a deployment or releasing stage. In another embodiment, the engaging element comprises a plurality of releasable sutures, gripping jaws or bio adhesives.[0012]
• It is still another object of the present invention to provide a method for delivering a tubular stentless prosthesis to an anatomical site in a body channel, the method comprising the steps of introducing a catheter into the body channel, wherein the catheter contains the tubular stentless prosthesis at a retracted state; advancing the catheter to the anatomical site; maintaining a distal portion of the tubular stentless prosthesis in place relative to the anatomical site; disengaging the catheter from the tubular stentless prosthesis adapted for self-expanding said prosthesis from the retracted state; and withdrawing said catheter from the body channel.[0013]
• The tubular stentless prosthesis of the present invention generally includes, but not limited to, a vascular graft, a synthetic vascular graft, a biological vascular graft, a cardiac valve, a valved conduit, a venous valve, and other stentless implantable devices. The “tubular stentless prosthesis” is essentially synonymous with the “longitudinally collapsible prosthesis” in the invention.[0014]
• In a further embodiment, the method comprises another step of coupling the prosthesis into tissue of the body channel, wherein the coupling means may include stapling, adhering, stenting, anchoring and the like.[0015]
BRIEF DESCRIPTION OF THE DRAWINGS
• Additional objects and features of the present invention will become more apparent and the invention itself will be best understood from the following Detailed Description of Exemplary Embodiments, when read with reference to the accompanying drawings.[0016]
• FIG. 1 is an overall view of a delivery catheter of the present invention for delivering a tubular stentless prosthesis into a body channel.[0017]
• FIG. 2 is an enlarged distal portion view of the catheter showing a first stage of the delivery sequences in accordance to the principles of the present invention.[0018]
• FIG. 2A is a transverse view of the section[0019]1-1 of FIG. 2 showing the relative location of the catheter shaft and the prosthesis inside the shaft.
• FIG. 3 is an enlarged distal portion view of the catheter showing a second stage of the delivery sequences in accordance to the principles of the present invention.[0020]
• FIG. 3A is a transverse view of the section[0021]2-2 of FIG. 3 showing the relative location of the catheter shaft and the prosthesis inside the shaft. FIG. 4 is an enlarged distal portion view of the catheter showing a third stage of the delivery sequences in accordance to the principles of the present invention.
• FIG. 5 is an enlarged distal portion view of the catheter showing a fourth stage of the delivery sequences in accordance to the principles of the present invention.[0022]
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
• Referring to FIGS.[0023]1 to5, what is shown is an embodiment of the device delivery system and methods, comprising a delivery catheter adapted particularly for delivering a tubular stentless prosthesis to an anatomical site in a body channel.
• FIG. 1 shows an overall view of a delivery catheter of the present invention for delivering a tubular stentless prosthesis into a body channel. A tubular stentless prosthesis is a prosthesis without a support or stent. Typically such a prosthesis is soft, flexible and very compressible or collapsible either radially or longitudinally. The best handling method is to hold it in its natural position without buckling, compression, or “spaghetti-like” twisting. When such a prosthesis[0024]31 is held horizontally, the best way to move it in an essentially straight manner is to pull thedistal section32 forward rather than push itsproximal end33.
• The[0025]catheter11 of the present invention comprises acatheter shaft17, the catheter shaft having adistal end12, adistal opening16, aproximal end13, and alumen22 between thedistal end12 and theproximal end13. The catheter also comprises adistal section14 that is used to hold the retractedprosthesis31B during the catheter delivery stage. A fully un-retracted (free from constraint) prosthesis31 in the present invention is the one prior to being inserted into thelumen22 or after fully deployed/released from the lumen.
• The catheter also comprises a[0026]handle15 that is attached to theproximal end13 of thecatheter shaft17. There is anelongated delivery member21 located inside said lumen22 (see FIG. 2), wherein the delivery member can be deployed forward or backward axially. The elongated delivery member has anengaging element35A,35B at adistal end26 of theelongated delivery member21, wherein theengaging element35A,35B is adapted for engaging and disengaging adistal portion32 of saidtubular prosthesis31B (see FIG. 3). The tubular prosthesis is characterized by its softness and collapsibility radially and/or longitudinally.
• The engaging element may comprise a plurality of releasable sutures, wherein the sutures may be released from the engaging element by, for example a cutting instrument. The engaging element may also comprise a plurality of releasably gripping jaws, wherein the gripping jaws may be released after the stentless prosthesis is deployed into place. Further, the engaging element may comprise a plurality of heat-disengageable wires, for example the fuse-like safety wires. A moderate heat can be provided through radiofrequency, ultrasound, electromagnetic or the like to disengage the wires from the prosthesis.[0027]
• The catheter further comprises a[0028]delivery mechanism18 at thehandle15, thedelivery mechanism18 is coupled to theelongated delivery member21, wherein thedelivery mechanism18 is adapted for pulling thedistal portion32 of thetubular prosthesis31B out of thecatheter shaft17 during a prosthesis releasing stage.
• The catheter of the present invention may be in the 8 French to 20 French size in diameter. However, the dimension outside this range is also applicable depending on the anatomic site and application. The material for catheters is generally biocompatible and flexible for inserting purposes.[0029]
• The method for delivering a tubular stentless prosthesis[0030]31 to an anatomical site in a body channel may comprise several major steps of (a) introducing a catheter into the body channel, wherein the catheter contains the tubular stentless prosthesis at a retracted state; (b) advancing the catheter to the anatomical site; (c) maintaining a distal portion of said tubular stentless prosthesis in place relative to the anatomical site; (d) disengaging the catheter from the tubular stentless prosthesis adapted for self-expanding said prosthesis from the retracted state; and (c) withdrawing the catheter from the body channel.
• FIG. 2 shows an enlarged[0031]distal portion14 of thecatheter11 showing a first stage of the delivery sequences in accordance to the principles of the present invention. A tubular stentless prosthesis31 can be crimped, compressed, constricted, constrained, contracted, or retracted radially to form a retractedprosthesis31B so as to snugly fit into anarrow lumen22 of thecatheter shaft17 at its distal section for delivering to the anatomical site.
• FIG. 2A shows a transverse view of the section[0032]1-1 of FIG. 2 showing the relative location of thecatheter shaft17 and theprosthesis31B inside the shaft. The catheter has an optional guidewire lumen or channel for riding the catheter shaft over aguidewire23. In one embodiment, theguidewire lumen24 is provided within the elongateddelivery member21. In another embodiment, the guidewire channel is provided at the distal section of the catheter shaft as a rapid exchange type guidewire system. The guidewire lumen is adapted for introducing a guidewire of about 0.014 inch or smaller.
• FIG. 3 shows an enlarged[0033]distal portion14 view of the catheter showing a generally second stage of the delivery sequences in accordance to the principles of the present invention. Thedistal portion32 of theprosthesis31B is pulled out of thedistal opening16 of thecatheter shaft17 by a pulling action from the distal end of theelongated delivery member21. In one embodiment, the pulling action is accomplished by an engaging element, wherein theengaging element35A,35B may have itsengaging points37A,37B at thedistal end26 of theelongated delivery member21 and another engagingpoints36A,36B at thedistal section32 of theprosthesis31B. In a relative sense when thedistal section32 remains fixed relative to an anatomical site, thecatheter11 is viewed as moving backward toward the operator. Thedistal portion32 of theprosthesis31B self-expands radially due to its elastic feature when the constraint is removed.
• To ensure that the self-expanded prosthesis will stay at a desired anatomic site within the body channel, the method may further comprise a step of coupling the prosthesis into tissue of the body channel whenever feasible. The coupling method may include stapling, adhering by a bio-adhesive, such as Bio-glue™ (from CryoLife, Inc., Kennesaw, Ga., USA). The stapling step may include stapling both the distal portion and the proximal portion of the prosthesis into tissue of the body channel, though more than two stapling points is also applicable.[0034]
• FIG. 3A shows a transverse view of the section[0035]2-2 of FIG. 3 showing the relative location of thecatheter shaft17 and theprosthesis31B inside the shaft. In a preferred embodiment, theguidewire lumen24 is provided within the elongateddelivery member21 of thecatheter11 for riding the catheter shaft over aguidewire23.
• FIG. 4 shows an enlarged[0036]distal portion14 view of the catheter showing a generally third stage of the delivery sequences in accordance to the principles of the present invention. The majority of theprosthesis31B is pulled out of thedistal opening16 of thecatheter shaft17 by a pulling action from the distal end of theelongated delivery member21. At this stage, thedistal portion32 and themiddle portion39 of theprosthesis31B self-expands radially due to its elastic feature when the constraint is removed.
• FIG. 5 shows an enlarged[0037]distal portion14 view of the catheter showing a generally fourth stage of the delivery sequences in accordance to the principles of the present invention. Thewhole prosthesis31A is pulled out of thedistal opening16 of thecatheter shaft17 by a pulling action from thedistal end26 of theelongated delivery member21. At this stage, thedistal portion32, themiddle portion39, and theproximal end33 of theprosthesis31B self-expands radially to form theun-constrained prosthesis31A as a result of its elastic feature when the constraint is completely removed.
• To provide an additional therapeutic therapy to the anatomic site, a therapeutic fluid is introduced into the lumen of the catheter shaft. The therapeutic fluid may be selected from a group consisting of an anti-inflammatory solution, an anti-virus solution, an antibiotic solution, an angiogenic fluid, heparin solution, an anti-sense fluid, an anti angiogenic fluid, a biocompatible adhesive, and a combination thereof. Typically a fluid inlet port is provided at about the handle of the catheter and the fluid can be supplied by a syringe or an infusion pump coupling to the fluid inlet port. The biocompatible adhesive, such as Bio-glue™ (from CryoLife, Inc., Kennesaw, Ga., USA) can be used to adhere the distal section of the longitudinally collapsible prosthesis on to the tissue at the anatomic site.[0038]
• From the foregoing description, it should now be appreciated that a method for delivering a stentless bioprosthesis in a body channel, the method comprising percutaneously introducing a catheter into the body channel, wherein the catheter contains the stentless bioprosthesis at a retracted state; and disengaging said stentless bioprosthesis out of a distal opening of the catheter by a pulling mechanism has been disclosed. While the invention has been described with reference to a specific embodiment, the description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications and applications may occur to those who are skilled in the art, without departing from the true spirit and scope of the invention, as described by the appended claims.[0039]

Claims (12)

What is claimed is:

1. A method for delivering a longitudinally collapsible prosthesis to an anatomical site in a body channel, the method comprising:

introducing a catheter into the body channel, wherein the catheter contains a longitudinally collapsible prosthesis in a retracted state;

advancing the catheter to an anatomical site;

maintaining a distal portion of the longitudinally collapsible prosthesis in place relative to the anatomical site by attaching the distal portion of the prosthesis to the interior of the anatomical site;

disengaging the longitudinally collapsible prosthesis from said catheter, wherein the collapsible prosthesis expands from the retracted state to a non-retracted state; and

withdrawing said catheter from the body channel.

2. The method according toclaim 1, wherein the longitudinally collapsible prosthesis is a vascular graft.

3. The method according toclaim 1, wherein the longitudinally collapsible prosthesis is a biological vascular graft.

4. The method according toclaim 1, wherein the longitudinally collapsible prosthesis is a stentless cardiac valve.

5. The method according toclaim 1, wherein the longitudinally collapsible prosthesis is a valved conduit.

6. The method according toclaim 1, wherein the longitudinally collapsible prosthesis is a venous valve.

7. The method according toclaim 1, wherein the step of attaching the distal portion of the prosthesis to the interior of the anatomical site further comprises a step of stapling said prosthesis into the tissue of the body channel.

8. The method according toclaim 1, wherein the step of attaching the distal portion of the prosthesis to the interior of the anatomical site further comprises a step of adhering said prosthesis into the tissue of the body channel.

9. The method according toclaim 1, wherein the step of attaching the distal portion of the prosthesis to the interior of the anatomical site further comprises a step of coupling said prosthesis into the tissue of the body channel.

10. The method according toclaim 1, wherein said distal portion of the longitudinally collapsible prosthesis is maintained in place at a position relative to the anatomical site by an elongated delivery member located within a lumen of the catheter, said elongated delivery member having an engagement element at a distal end of the said elongated delivery member, where in the engaging element is adapted for engaging and digging ht distal portion of said longitudinally collapsible prosthesis. a therapeutic fluid is introduced into the lumen of the catheter shaft.

11. A method for delivering a stentless longitudinally collapsible bioprosthesis in a body channel,

the method comprising percutaneously introducing a catheter into the body channel, wherein the catheter contains said stentless longitudinally collapsible bioprosthesis at a retracted state; and disengaging said stentless bioprosthesis out of a distal opening of the catheter by pulling the distal end of the stentless bioprosthesis.

12. The method according toclaim 11, wherein said pulling mechanism further comprises an engaging element coupling to a distal portion of the stentless longitudinally collapsible bioprosthesis from said engaging element.

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