US20100249491A1 - Two-piece transseptal cannula, delivery system, and method of delivery - Google Patents

Abstract

A cannula assembly for directing blood from the heart of a patient and a minimally invasive method of implanting the same. The cannula assembly includes a flexible cannula body having a proximal end and a distal end with a receiving portion, and a transseptal tip having a distal end and a proximal end with an engaging portion. First and second anchors are coupled to the transseptal tip and configured to be deployed from a contracted state to an expanded state. The engaging portion of the transseptal tip is operable to removably engage the receiving portion of the flexible cannula body in vivo.

Description

• This application claims the priority of U.S. Provisional Patent Application Ser. No. 61/163,931, filed on Mar. 27, 2009 (pending), the disclosure of which is incorporated by reference herein.
TECHNICAL FIELD
• The present invention generally relates to a method of implanting a circulatory assist system, and more particularly, to the method of implanting a cannula assembly of the circulatory assist system.
BACKGROUND
• The human heart is the muscle that is responsible for pumping blood throughout the vascular network. Veins are vessels that carry blood toward the heart while arteries are vessels that carry blood away from the heart. The human heart consists of two atrial chambers and two ventricular chambers. Atrial chambers receive blood from the body and the ventricular chambers, which include larger muscular walls, pump the blood from the heart. A septum separates the left and the right sides of the heart. Blood from the veins of the vascular network enters the right atrium from the superior and inferior vena cava and moves into the right ventricle. From the right ventricle, the blood is pumped to the lungs via pulmonary arteries to become oxygenated. Once the blood has been oxygenated, the blood returns via pulmonary veins to the heart by entering the left atrium. From the left atrium, the blood enters the left ventricle and is pumped into the aorta and then into the arteries of the vascular network.
• For the vast majority of the population, the events associated with the movement of blood happen without circumstance. However, for many people the heart fails to provide adequate pumping capabilities. These heart failures may include congestive heart failure (commonly referred to as heart disease), which is a condition that results in any structural or functional cardiac disorder. The structural or functional disorder impairs the ability of the heart to fill with or pump blood throughout the body. Presently, there is no known cure for heart disease and long-term treatment is limited to a heart transplant. With only a little over 2,000 patients receiving a heart transplant each year, and over 16,600 more on the waiting list for a heart, there is a persisting need for a cure or at the minimum a means of improving the quality of life of those patients on the waiting list.
• One such means of bridging the time gap while awaiting a transplant is a circulatory assist system. Circulatory assist devices were developed over a decade ago and provide assistance to a diseased heart by way of a mechanical pump. In this way, the circulation of blood through the vascular network is aided despite the presence of diseased tissue. Traditionally, these circulatory assist devices include an implantable pump, a controller (internal or external), and inflow and outflow tubes connecting the pump to the vascular network. FDA approved circulatory assist devices may be used to partially relieve symptoms of breathlessness and fatigue associated with severe heart failure and can drastically improve a patient's quality of life.
• However, the conventional surgical process associated with the circulatory assist system is highly invasive. At the very least the procedure involves a thoracotomy, i.e., the opening of the thoracic cavity between successive ribs to expose the internal organs. More typical is cardiac surgery, generally known as open-heart surgery, where the sternum is cut and split to expose the internal organs. Once the thoracic cavity is accessed, the physician must enter the pleural space and puncture both the pericardium and the myocardial wall. There are great risks and an extensive recovery time associated with the invasive nature of the implantation surgery. As such, some patients with severe symptoms are not healthy enough for surgery to receive a circulatory assist system.
• The transseptal cannula, described in related U.S. patent application Ser. No. 12/256,911, the disclosure of which is incorporated herein by reference, provides greater accessibility to the circulatory assist device to those patients that would receive the most benefit by minimizing the invasiveness of the implantation surgery. Yet, there continues to be a need to implement additional features that would further facilitate the delivery of the transseptal cannula and/or that would allow the physician to maintain greater control over the transseptal cannula device during the surgical procedure.
SUMMARY
• In one illustrative embodiment, the present invention is directed to a cannula assembly. The cannula assembly includes a flexible cannula body having distal and proximal ends with a lumen extending therebetween. The distal end of the flexible cannula body includes a receiving portion. A transseptal tip has a distal end and a proximal end with an engaging portion. The engaging portion of the transseptal tip is operable to connect to the receiving portion of the flexible cannula body, in vivo. First and second anchors are coupled to the transseptal tip and are configured to be deployed from a contracted state to an expanded state. The first and second anchors are also configured to engage opposite sides of a heart tissue when in the expanded state.
• The first and second anchors can each include a plurality of struts extending generally transverse to a lengthwise central axis of the flexible cannula body. The plurality of struts can be formed from a superelastic material and can be folded to a position that is generally parallel with the lengthwise central axis when in the contracted state.
• Another illustrative embodiment of the present invention includes a transseptal tip delivery system in combination with the cannula assembly. The transseptal tip delivery system includes a delivery catheter and a delivery sheath. The delivery catheter has distal and proximal ends and a lumen extending therebetween. The distal end of the delivery catheter includes a receiving portion that is operable to removably disengage the engaging portion of the transseptal tip in vivo. The delivery sheath receives the delivery catheter with the transseptal tip and moves relative thereto. Moving the delivery sheath can deploy the first and second anchors into the expanded state.
• Another illustrative embodiment of the present invention includes a cannula guide in combination with the cannula assembly. The cannula guide includes an expandable member having distal and proximal tapers and an alignment section therebetween. A body of the cannula guide extends proximally from the expandable member. The expandable member of the cannula guide is configured to engage an inner surface of the transseptal tip and to resist movement of the transseptal tip from the heart tissue while the flexible cannula body is connected to the engaging portion of the transseptal tip, in vivo.
• In another illustrative embodiment of the present invention, a method of implanting the cannula assembly within a heart tissue of a patient is provided. The method includes introducing the transseptal tip to the heart tissue, directing the flexible cannula body to the transseptal tip, and connecting the receiving portion of the flexible cannula body to the engaging portion of the transseptal tip, in vivo.
• The method of implanting can include deploying the first and second anchors to engage opposite sides of the heart tissue in the expanded state. The deploying can further include deploying a plurality of struts comprising the first and second anchors from a position generally parallel with a lengthwise central axis of the flexible cannula body to a position generally transverse to the lengthwise central axis.
• The method of implanting can further include advancing and deploying an anchoring guide-element after deploying the first anchor and before deploying the second anchor. The anchoring guide-element includes a body portion having distal and proximal ends and an anchoring portion on the distal end of the body portion. The anchoring portion is configured to be deployed from a contracted state to an expanded state that is generally transverse to the length-wise central axis of the body portion. The anchoring portion in the deployed state resists retraction of the anchoring guide-element from the heart tissue.
• The steps of introducing, directing, and deploying can be performed from a primary incision site that is located substantially near a superficial vein of the lower thorax. The method can also be transferred from the primary incision site to a secondary incision site located substantially near a superficial vein of the upper thorax.
• Another illustrative embodiment of the present invention includes an introducer assembly for introducing a surgical device into the vascular system. The introducer assembly includes a removable dilator and an introducer. The removable dilator has an attachment mechanism for removably attaching an introducer set. The introducer receives the removable dilator with the introducer set and maintains a puncture through the vascular wall.
• In another illustrative embodiment of the present invention, a method of introducing a surgical device into the vascular network of a patient with the introducer assembly is described. The method includes attaching the introducer set to the removable dilator. The introducer set and removable dilator are received by the introducer. A guide-wire punctures a vessel wall and the introducer assembly is advanced over the guide-wire, as a unit, until the hub of the introducer contacts an external surface of the vessel. The removable dilator and introducer set are removed and a surgical device is directed through the introducer and into the vascular network.
• In yet another illustrative embodiment of the present invention, a method of in vivo coupling of the flexible cannula body to the transseptal tip is described. The flexible cannula body includes a first marker on the receiving portion and the transseptal tip includes a second marker on the engaging portion. The method includes directing the flexible cannula body to the transseptal tip. The receiving portion of the cannula is coupled to the engaging portion of the transseptal tip until the first marker overlays the second marker.
• Another illustrative embodiment of the present invention includes a method of aligning the flexible cannula body to the transseptal tip, in vivo. The method includes directing a cannula guide to the transseptal tip. The expandable member of the cannula guide is inflated to engage the inner surface of the transseptal tip. The cannula is advanced over the proximal taper of the cannula guide to the proximal end of the transseptal tip.
• In yet another illustrative embodiment of the present invention, a method of removing a circulatory assist device is described. The method includes disengaging the flexible cannula body from the pump. The flexible cannula body is then uncoupled and retracted from the transseptal tip. The transseptal tip is then sealed.
BRIEF DESCRIPTION OF THE FIGURES
• FIG. 1 is a diagrammatic view of an exemplary method of accessing the intra-atrial septum of the human heart, shown in cross-section.
• FIG. 1A is an assembled side elevational view of an introducer assembly, shown in cross-section.
• FIG. 2A is a disassembled side elevational view of a transseptal access system, including a delivery sheath, a dilator, and a transseptal needle.
• FIG. 2B is an assembled side elevational view of the transseptal access system, including the delivery sheath, a dilator, and the transseptal needle.
• FIGS. 3A-3C are diagrammatic views of an exemplary method of accessing the left atrium by puncturing the intra-atrial septum of the human heart, shown in partial cross-section.
• FIG. 4A is a disassembled side elevational view of an anchoring guide-element and a delivery device for the anchoring guide-element, shown in partial cross-section.
• FIG. 4B is an assembled side elevational view, in partial cross-section, of the anchoring guide-element and the delivery device for the anchoring guide-element.
• FIG. 4C is a diagrammatic view of an exemplary method of advancing the assembled anchoring guide-element and delivery device to the left atrium of the human heart, shown in cross-section.
• FIG. 5A is a disassembled side elevational view of a transseptal tip and a delivery catheter.
• FIG. 5B is an assembled cross-sectional view of the transseptal tip and the delivery catheter.
• FIG. 5C is a perspective view of the transseptal tip.
• FIG. 5D is an assembled cross-sectional view of the transseptal tip and the delivery catheter.
• FIG. 5E is a diagrammatic view of an exemplary method of loading the assembled transseptal tip and delivery catheter into a hub of a delivery sheath.
• FIGS. 6A-6D are diagrammatic views of an exemplary method of deploying a first anchor of the transseptal tip and the plurality of struts of the anchoring guide-element within the left atrium, shown in cross-section.
• FIG. 6E is a perspective view of the deployed first anchor of the transseptal tip and the deployed plurality of struts of the anchoring guide-element within the left atrium.
• FIG. 6F is a diagrammatic view of an exemplary method of deploying a second anchor of the transseptal tip within the right atrium, shown in cross-section.
• FIGS. 6G-6H are diagrammatic views of an exemplary method of removing and retracting the delivery catheter from the transseptal tip, shown in cross-section.
• FIGS. 6I-6K are diagrammatic views of an exemplary method of transitioning the anchoring guide-element from a primary incision site to a secondary incision site, shown in cross-section.
• FIG. 6L is a diagrammatic view of an exemplary method of advancing a cannula guide to the transseptal tip, shown in cross-section.
• FIG. 6M is a side elevational view of a flexible cannula body.
• FIGS. 6N-6O are diagrammatic views of an exemplary method of advancing and attaching the flexible cannula body to the transseptal tip, shown in cross-section.
• FIG. 6P is a diagrammatic view of an exemplary method of removing the cannula guide and anchoring guide-element from the transseptal tip, shown in cross-section.
• FIG. 6Q is a diagrammatic view of the assembled flexible cannula body and the transseptal tip implanted within the intra-atrial septum, shown in cross-section.
• FIG. 6R is a diagrammatic view of an illustrative circulatory assist system positioned in the human heart, shown in cross-section.
• FIGS. 7A-7B are diagrammatic views of an exemplary method of removing the circulatory assist system, shown in cross-section.
• FIGS. 7C-7E are diagrammatic views of an exemplary method of removing the flexible cannula body from the transseptal tip, shown in cross-section.
• FIG. 7F is a diagrammatic view of an exemplary method of sealing the transseptal tip after the flexible cannula body has been removed, shown in cross-section.
• FIG. 7G is a diagrammatic view of the sealed transseptal tip after the flexible cannula body has been removed, shown in cross-section.
DETAILED DESCRIPTION
• Implanting a circulatory assist system can begin with a percutaneous transseptal crossing procedure.FIG. 1 illustrates a portion of the procedure where the physician creates aprimary incision site10 in a patient12 that is substantially near a superficial vein. A suitable superficial vein for theprimary incision site10 can include a peripheral vein, such as the right or leftfemoral veins18,22, or others known by one skilled in the art. It is generally preferred that theprimary incision site10 is inferior to asecondary incision site24 that is substantially near a peripheral vein of the upper thorax, such as the left or rightsubclavian veins26,30; the left or rightjugular veins34,38; at the junction between the left or rightsubclavian vein26,30 and the adjoiningjugular vein34,38; or other suitable peripheral veins known by one skilled in the art.
• The use of aprimary incision site10 is preferred for accessing a heart tissue, such as anintra-atrial septum42, due to the angle of theheart48 with respect to theinferior vena cava50. Theprimary incision site10 is also well suited for the embodiments of the present invention because the angle between theinferior vena cava50 and theintra-atrial septum42 allows the physician to apply greater force for inserting a transseptal tip (described below) into theintra-atrial septum42.
• The physician may use a custom introducer assembly to create and maintain the incision into each of the superficial veins. The details of theintroducer assembly51 are shown inFIG. 1A and generally include anintroducer52 and aremovable dilator53 that are used in cooperation with commercially available introducer sets, in a manner that is described below.
• The customizedintroducer52 includes ahub54 and asheath55 that extends distally from thehub54. Thesheath55 of theintroducer52 is constructed from a mid-to-high durometer material such that thesheath55, once inserted, does not collapse under the pressure of the wall of the superficial vein. The sheath material can be a high density polyethylene having a low coefficient of friction to ensure that surgical devices move with ease through the lumen of theintroducer52. Alternatively, a low friction coating can be applied thereto. In yet other embodiments, thesheath55 can include braid or coil structures, formed from materials such as stainless steel wire, Nitinol, or other materials known in the art, to provide additional structural stability when needed. Generally, thesheath55 of theintroducer52 should be sufficient in length to extend within the lumen of the superficial vein while thehub54 remains proximal to the incision site. A suitable length can be about 10 cm; however, this should not be considered limiting.
• Thehub54 of theintroducer52 includes a sealing mechanism, illustrated herein as an O-ring56, for sealing against theremovable dilator53 or any other subsequently introduced surgical device. Accordingly, the O-ring56 should have an inner diameter that is sufficiently equal to the nominal outer diameter of theremovable dilator53. Because the O-ring56 would not prevent bleeding through theintroducer52 once theremovable dilator53 has been removed, a silicone plug (not shown) can be used to seal thehub54 of theintroducer52 at the O-ring56. Alternatively, other sealing mechanisms, such as a hemostatic seal or a grommet, can be used. The hemostatic seal or grommet would automatically provide a fluidic seal against the interstitial pressures when theremovable dilator53 or other surgical device is not present in theintroducer52.
• FIG. 1A further illustrates the details of theremovable dilator53, which include ahub57 and adilator sheath58 extending distally from thehub57. Thedilator sheath58 can be formed by a melt flow process to create adistal taper60 as an attachment mechanism for attaching to an introducer set61. For example, thedistal taper60 forms a frictional fit with the introducer set61, which is conventionally used for obtaining vascular access. Suitable introducer sets61 may include those that are commercially available, such as the COOK CHECK-FLO PERFORMER introducer set having asheath introducer62, adilator63, and a guide-wire64. Thedistal taper60 can be constructed to fit any commercially available introducer set61 having a particular size, for example those having 12.0 French or 6.0 French dilators. In some embodiments, thesheath introducer62 can include a flushing side-arm port65 for removing fluid from the incision site.
• Though not specifically shown, thehub57 of theremovable dilator53 can include a proximal seal as the attachment mechanism in alternative or in addition to thedistal taper60. Suitable proximal seals can include, for example, an O-ring to proximally couple and seal theremovable dilator53 against the introducer set61.
• In operation, the commercial introducer set61 is inserted through the lumen of theremovable dilator53, which is then, in turn, loaded into theintroducer52. The guide-wire64 of the introducer set61 is advanced to puncture the wall of the superficial vein. The introducer set61,removable dilator53, andintroducer52 are then backloaded, as a unit, over the guide-wire64 and to the wall of the superficial vein. The puncture within the wall of the superficial vein undergoes a first dilation to a first diameter with thedilator63 and then a second dilation to a second diameter by theremovable dilator53. Finally, with continued advancement, thesheath55 of theintroducer52 enters the lumen of the superficial vein until a distal end of thehub54 of theintroducer52 contacts an external surface of the incision site. If desired, the guide-wire64 can then be removed from the superficial vein.
• Theintroducer52,removable dilator53, and introducer set61 can remain within the wall of the superficial vein, as a unit, until a larger surgical device is needed. Accordingly, the physician can decouple theremovable dilator53 with the introducer set61, as a unit, from theintroducer52. Theintroducer52 remains extended through the wall of the superficial vein to maintain a vascular network access point, which allows the physician to advance larger surgical devices into the vascular network with little to no friction from the contracting wall of the superficial vein.
• Referring again toFIG. 1, once the primary andsecondary incision sites10,24 are made, and the custom introducer assembly is properly positioned, the physician can direct a capture device, such as astandard snare device66, from thesecondary incision site24, down thesuperior vena cava67, theright atrium68, theinferior vena cava50, the rightfemoral vein18, and out of theprimary incision site10. Thestandard snare device66 can include abody69 that extends between the primary andsecondary incision sites10,24 and asnare loop70 on a distal end of thebody69. Though not shown, in some embodiments, thesnare loop70 can remain within the rightfemoral vein18 and not extend externally from theprimary incision site10.
• The method continues with the physician removing the dilator53 (FIG. 1A) and the introducer set61 (FIG. 1A) from thehub54 of theintroducer52 extending from theprimary incision site10 to allow passage of atransseptal access system74 into the vascular network for making a percutaneous transseptal crossing. Thetransseptal access system74 is then inserted through thesnare loop70, into theprimary incision site10, up the rightfemoral vein18, theinferior vena cava50, and into theright atrium68. It would be understood that theintroducer assembly51 remains fully assembled at thesecondary incision site24.
• FIG. 2A illustrates the details of the disassembledtransseptal access system74, which includes adelivery sheath78, adilator82, and atransseptal needle84.
• Thedelivery sheath78 has aflexible body90 with a distal end, a proximal end, and a lumen extending between. Ahub94 is positioned on the proximal end of theflexible body90. Theflexible body90 of thedelivery sheath78 is custom sized to facilitate the delivery of a transseptal tip (discussed below) and can be constructed as three thin-layer walls. The exterior layer can be constructed of materials such as polyurethane, Nylon-11, Nylon-12, or PEBAX, thermoplastic elastomers, copolymers, or blends of urethanes; the interior layer can be a liner made from etched polytetrafluorethylene (ePTFE), urethane, or Nylon with hydrogel coating; and the mid-layer can be constructed from a braided material or a coiled member, such as stainless steel wire, Nitinol, or polyetheretherketones (PEEK) fibers to provide structural stability to theflexible body90. The interior layer, or liner, can be extruded and placed upon a mandrel with the mid-layer and the exterior layer respectively formed or otherwise placed over the interior layer. Polyurethane is then placed over the entire assembly and heat shrink wrapped over theflexible body90 for stability. Alternatively, theflexible body90 of thedelivery sheath78 can be laminated by a reflow process. In some instances, a superelastic coil (nickel titanium, NiTi, or stainless steel) or a metallic braid can be included to further increase the rigidity of thedelivery sheath78. The superelastic coil or metallic braid can enhance the maneuverability of theflexible body90. A polymeric layer can surround the superelastic coil or braid to reduce friction as theflexible body90 moves within the vascular network. It would also be permissible for theflexible body90 to include a lubricious material, such as HYDROMED or a polyamide, to reduce friction as a delivery catheter (described below) moves within theflexible body90.
• In some embodiments, theflexible body90 can further include amarker98 constructed from a metallic material, such as gold (Au) or platinum (Pt), or from a polymeric material embedded with a dense powder, such as tungsten (W). Themarker98 aids the physician in positioning thedelivery sheath78 in vivo.
• Thehub94 of thedelivery sheath78 can include amain port102 having a hemostasis valve (described below) to prevent blood from exiting thedelivery sheath78 during the introduction and/or removal of other surgical devices, such as thedilator82. Aside port106 permits limited fluidic access via atubing108 and avalve110.
• Referring still toFIG. 2A, the details of thedilator82 will now be described. Thedilator82 has adilator body114, adilator tip118, and adilator hub122. Thedilator body114 is custom sized to facilitate the delivery of the transseptal tip (discussed below). Thedilator body114 anddilator tip118 can be constructed from a polymer with a low coefficient of friction, such as fluoropolymer. Thedilator tip118 should be constructed with sufficient rigidity to dilate an opening through the heart tissue. Thedilator hub122 allows thedilator82 to be flushed with saline prior to insertion into the vascular network.
• In some embodiments, it would be permissible for the distal ends of thedelivery sheath78 and thedilator82 to include a preformed shape that is directed toward the intra-atrial septum42 (FIG. 1).
• FIG. 2A also illustrates thetransseptal needle84, which can be any device that has ahollow needle tip126, ahollow needle body130, and aneedle hub134, such as the Brockenbrough transseptal needle. Theneedle hub134 can be used in monitoring the patient's blood pressure while thetransseptal needle84 punctures the intra-atrial septum42 (FIG. 1).
• FIG. 2B illustrates the assembledtransseptal access system74.
• With the details of thetransseptal access system74 described in some detail, the method of percutaneous transseptal crossing can continue with reference toFIGS. 3A-3C.
• FIG. 3A illustrates thetransseptal access system74 as thetransseptal needle84 creates apuncture138 in theintra-atrial septum42 and enters theleft atrium46. Thedilator tip118 is then advanced over thetransseptal needle84 and dilates thepuncture138 through theintra-atrial septum42.
• FIG. 3B illustrates the continued advancement of thedilator82 such that thepuncture138 is further dilated to a diameter that is approximately equal to the diameter of thedilator body114. This further dilation allows thedelivery sheath78 to advance over thedilator82, through the dilatedpuncture138, and to enter theleft atrium46. Once thedelivery sheath78 is within theleft atrium46, thedilator82 and thetransseptal needle84 are retracted, as illustrated inFIG. 3C.
• With the delivery sheath78 (FIG. 3C) in place, the physician can then use an anchoring guide-element to aid in the method of implanting the transseptal tip (discussed below). The anchoring guide-element may then also be used to facilitate the redirecting of the implanting procedure from the primary incision site10 (FIG. 1) to the secondary incision site24 (FIG. 1).
• FIG. 4A illustrates an exemplary embodiment of the anchoring guide-element142, though additional detail is provided in U.S. patent application Ser. No. 12/256,911. The anchoring guide-element142 has abody portion146 and an anchoringportion150 on the distal end of thebody portion146.
• Thebody portion146 can be constructed from a central core made from a metallic material, such as stainless steel or nickel titanium (NiTi) and covered with a polymeric material to reduce the friction between the anchoring guide-element142 and any surgical device that is advanced over the anchoring guide-element142. Thebody portion146 should be flexible enough to prolapse upon itself. The proximal end of thebody portion146 may include anatraumatic coil154 constructed from wound radiopaque metal wire (for example, platinum (Pt)).
• The anchoringportion150 has a plurality ofstruts158 attached to ahub160. Thehub160 has atip transition section162, astrut retaining ring166, and atip170. Thetip170 can be machined from a dense, radiopaque metallic material, such as platinum (Pt) or tantalum (Ta), and coated with a material to prevent galvanic corrosion with the plurality ofstruts158. Thetip170 secures thebody portion146 to the anchoringportion150 by either laser welding or a chemical bonding process. Thestrut retaining ring166 can be constructed of similar material as thetip170 and secures the plurality ofstruts158 to the anchoringportion150. Thetip transition section162 can be constructed of similar materials but should be devoid of any sharp edges that may catch or snag on other surgical devices when removing the anchoring guide-element142.
• The plurality ofstruts158 can be constructed from a sheet of superelastic, metallic material (e.g. NiTi) or MP35N, which allows each of the plurality ofstruts158 to be folded and/or held in a position that is parallel to central axis of thebody portion146. Once released, the plurality ofstruts158 will automatically spring to a deployed state that is transverse to the central axis. While fourstruts158 are shown, this number is not so limited. Rather, embodiments could be envisioned where two struts or up to eight struts can be necessitated for a particular physician's needs or preference.
• Continuing withFIG. 4A, adelivery device174 for the anchoring guide-element142 is shown. Asheath tip178 of thedelivery device174 receives the proximal end of thebody portion146 of the anchoring guide-element142. As thebody portion146 is pulled through thesheath tip178 and asheath body182, the plurality ofstruts158 contacts thesheath tip178 and is folded from the position transverse to the central axis to the position that is parallel to the central axis. Thesheath body182 is constructed from etched polytetrafluorethylene (ePTFE) or fluorinated ethylene propylene (FEP) so as to allow minimal clearance between the lumen of thesheath body182 and thebody portion146 of the anchoring guide-element142. This construction facilitates the delivery of the anchoring guide-element142 because thebody portion146 construction of the anchoring guide-element142 lacks sufficient column strength to advance the folded plurality ofstruts158 through the delivery sheath78 (FIG. 3C) to the desired location. This minimal clearance can further aid the physician in deploying the plurality ofstruts158.
• FIG. 4B illustrates the anchoring guide-element142 fully loaded within thedelivery device174 with the plurality ofstruts158 deflected to the position parallel to the central axis. Thedelivery device174 and anchoring guide-element142 are then ready to be back-loaded through the hub94 (FIG. 2A) of the delivery sheath78 (FIG. 2A).
• FIG. 4C illustrates the advancement of thedelivery device174 and the anchoring guide-element142 through thedelivery sheath78 until the distal end of thesheath tip178 begins to emerge from thedelivery sheath78.
• The method for implanting thetransseptal tip186 now continues with reference toFIGS. 5A-5E.FIG. 5A illustrates the details of thetransseptal tip186, which include adistal end190 and aproximal end194 having an engagingportion198. The engagingportion198 is operable to connect to a receiving portion (described below) of a flexible cannula body (described below) or a receiving portion of a delivery catheter (described below) in vivo. In a preferred embodiment, thetransseptal tip186 is constructed from titanium alloy, such asTiAl 6Va EL 1, by standard turning, wire electrical discharge machining (EDM), or other machining processes. Alternatively, thetransseptal tip186 can be constructed from a polymeric material (for example, nylon) that is compounded using radiopaque filler that is typically encapsulated within the polymer matrix. The radiopaque filler can include platinum-iridium (Pt:Ir), stainless steel, tungsten (W), or tantalum (Ta) and allows for the in vivo visualization of thetransseptal tip186 by non-invasive devices, such as X-ray, real-time fluoroscopy, or intracardiac echocardiograph.
• First andsecond anchors202,206 are coupled to thetransseptal tip186. The first andsecond anchors202,206 are configured to be deployed from a contracted state to an expanded state. Once in the expanded state, thefirst anchor202 will engage the intra-atrial septum42 (FIG. 1) within the left atrium46 (FIG. 1) while thesecond anchor206 will engage the intra-atrial septum42 (FIG. 1) within the right atrium68 (FIG. 1). Additionally, it is possible to construct the first andsecond anchors202,206 in a way such that thesecond anchor206 is larger than thefirst anchor202. This configuration is more desirable than the reverse because the right atrium68 (FIG. 1) is larger in volume than the left atrium46 (FIG. 1); however, the invention should not be considered so limited. While the first andsecond anchors202,206 are described in some detail below, additional details and features are disclosed in U.S. patent application Ser. No. 12/256,911.
• Continuing withFIG. 5A, thedelivery catheter210 for thetransseptal tip186 is shown. Thedelivery catheter210 has aproximal end214 and adistal end218 that includes a receivingportion222. The receivingportion222 is operable to removably disengage the engagingportion198 of thetransseptal tip186 in vivo. Thedelivery catheter210 can be made from a polymer (such as Pebax or polyurethane) and can be reinforced with ametallic coil226 or braid (not shown) or stiffening stylet to enhance the response of thedelivery catheter210. To further increase the torque response, thecoil226 can be constructed to wind in a direction that is similar to the direction of rotation used to disengage the receivingportion222 from the engagingportion198. Thedelivery catheter210 can further include amarker230 near thedistal end218 of thedelivery catheter210. Themarker230 may be constructed from a radiopaque material to enhance in vivo visualization.
• FIG. 5B illustrates thetransseptal tip186 and thedelivery catheter210 with greater detail. The engagingportion198 can be constructed as a low profile, coarse,male thread232 for threadably engaging the receivingportion222 of thedelivery catheter210 or of the flexible cannula body (described below). The low profile and coarse construction of thethread232 aids in preventing cross threading during the in vivo disassembly of thetransseptal tip186 from thedelivery catheter210 or during the in vivo assembly of the flexible cannula body, described in detail below. Thethreads232 can be molded as part of thetransseptal tip186 during construction. Alternatively, thethreads232 are machined after molding and polished to remove any rough edges.
• In another embodiment, not specifically shown, the engagingportion198 can include a first magnet with a polarity that is opposite to a second magnet on the receivingportion222 of thedelivery catheter210. The magnetic field between the first and second magnets should be sufficiently strong to resist decoupling without an appropriate amount of force. Generally, the magnetic field should be sufficiently strong to resist decoupling of the receivingportion222 from the engagingportion198 due to the frictional force of blood pumping through thetransseptal tip186 and flexible cannula body (described below). Other alternative means of engaging can include adhesives or frictional fit.
• Thedistal end190 of thetransseptal tip186 is shown to include a shape that will reduce fluidic drag and can be coated with a material that prevents thrombus growth; however, thetransseptal tip186 should not be considered to be limited to the shape specifically shown.
• Thetransseptal tip186 also includes alumen234 extending between the distal and proximal ends190,194. Once thetransseptal tip186 is implanted, thelumen234 creates a shunt through the intra-atrial septum42 (FIG. 1).
• Thetransseptal tip186 can further include one ormore rings238 provided for several reasons. Theserings238 can act in a manner such as to engage the first andsecond anchors202,206. In this way, therings238 can act in conjunction withclamps242 to affix the first andsecond anchors202,206 on thetransseptal tip186. Therings238 could also be used in seating the first andsecond anchors202,206 and keyed in a way so as to maintain an orientation of the first andsecond anchors202,206.Suitable clamps242 can include configurations as shown or others such as, but not limited to, swage or crimp-style clamps. Theclamps242 could alternately be attached to thetransseptal tip186 by adhesive, welding, or tying.
• In construction, therings238 can advantageously be molded as a portion of thetransseptal tip186. Alternatively, therings238 are swaged or crimped into place after thetransseptal tip186 is constructed. In some embodiments, therings238 can optionally be constructed of radiopaque materials such as to aid in localization of thetransseptal tip186. Alternatively, a separate radiopaque band (not shown) can be constructed and placed sufficiently near therings238.
• FIG. 5B further illustrates that the receivingportion222 of thedelivery catheter210 may be constructed as thefemale counterpart thread244 to thethread232 of the engagingportion198. Thethreads244 of thedelivery catheter210 can be constructed from a radiopaque material to allow for fluoroscopic visualization, from a polished metallic material (such as titanium (Ti)), or from a molded polymeric material (such as nylon) that is compounded using radiopaque filler (such as tantalum (Ta)). The proximal end of the receivingportion222 can further include one ormore barbs246.Barbs246 provide resistance against the undesired removal of the receivingportion222 from thedelivery catheter210. A tie (not shown) can also be included external to thedelivery catheter210 at thebarbs246 to further secure thedelivery catheter210 to the receivingportion222. In some embodiments, the proximal end can include a shape that will reduce fluidic drag; however, the proximal end should not be considered to be limited to the shape specifically shown.
• FIG. 5C illustrates with greater detail thetransseptal tip186 with the first andsecond anchors202,206. Each of the first andsecond anchors202,206 generally includes a plurality ofstruts250 extending from a central ring portion (not shown) such that the plurality ofstruts250 and central ring portion are etched as a single unit from the same piece of superelastic material. Alternatively, it would be possible to permanently affix each of the plurality ofstruts250 to a separately manufactured central ring portion, such as by welding or other means. It should be appreciated that while four struts are shown peranchor202,206, this number is not so limited. Rather, embodiments could be envisioned where fewer or more struts can be necessitated for a particular physician's needs or preference. Generally, three or more struts are preferred.
• The first andsecond anchors202,206 can be at least partially constructed from a superelastic material (such as nickel titanium (NiTi)) or by chemically etching the parts from flat sheet stock, electropolishing the etched parts to remove rough edges generated during the formation process, and then heating the parts to a superelastic state. While the preferred materials are specifically taught herein, other suitable biocompatible, non-compliant, flexible material would be sufficient for thetransseptal tip186 or theanchors202,206.
• FIG. 5C also illustrates that thefirst anchor202 can be offset with respect to thesecond anchor206. This is the preferred configuration of the deployed anchors202,206 because of the particular load-bearing benefits. However, it would also be possible to includeanchors202,206 with no offset if the particular need would arise, though this is not shown.
• As illustrated in phantom inFIG. 5C, theanchors202,206 can each respectively include aporous polymeric structure252 over the plurality ofstruts250. In function, theporous polymeric structure252 provides a larger surface to engage the intra-atrial septum42 (FIG. 1) than the plurality ofstruts250 alone. Further, theporous polymeric structure252 allows for tissue in-growth, where the tissue can grow and become embedded within theporous polymeric structure252 to provide greater structural stability and sealing capacity. While either or both of theanchors202,206 can include theporous polymeric structure252, it is generally preferred that only thesecond anchor206, which will reside along the intra-atrial septum42 (FIG. 1) within the right atrium68 (FIG. 1), will include theporous polymeric structure252. This configuration is preferred because the right atrium68 (FIG. 1) is larger in volume than the left atrium46 (FIG. 1); however, the invention should not be considered so limited. Suitable materials for theporous polymeric structure252 can include, but are not limited to, polyester monofilament or multifilament yarn; ePTFE monofilament or multifilament yarn; or fluorinated polyolefin fibers or yarns, which can be woven, braided, knitted, or felted into a proper configuration. Theporous polymeric structure252 can further include various intrinsic configurations including weaves, braids, or knits having two or three-dimensional honeycombs, circular, flat, or tri-axial tubular structures. In other embodiments, theporous polymeric structure252 can be constructed from an ePTFE piece in tubular, cylindrical, or sheet form. Generally, theporous polymeric structure252 will be constructed by etching or laser cutting a shape from two sheets of a stock material (such as those described above). The shapedpolymeric structures252 are then ultrasonically welded together such that the shapedpolymeric structures252 capture the plurality ofstruts250 therebetween.
• FIG. 5D illustrates the assembleddelivery catheter210 andtransseptal tip186.
• FIG. 5E illustrates an exemplary method of loading the assembleddelivery catheter210 andtransseptal tip186 into thehub94 of thedelivery sheath78. Because the first andsecond anchors202,206 naturally expand to a position that is transverse to the lengthwise central axis, it is necessary to fold the first andsecond anchors202,206 to a position that is parallel to the lengthwise central axis and thus suitable for loading the first andsecond anchors202,206 into thedelivery sheath78. Various manners of folding the first andsecond anchors202,206 are disclosed in U.S. patent application Ser. No. 12/256,911; however, other methods of folding theanchors202,206 would be known. For example, the physician can simply deflect thefirst anchor202 distally while thesecond anchor206 is deflected proximally. The proximal and distal folding of theanchors202,206 is preferred because this configuration provides the greatest distance between the foldedanchors202,206 and can enhance the physician's control over the delivery of theanchors202,206. Aloading tube254 is used to open thehemostatic valve258 within thehub94 of thedelivery sheath78 to permit passage of various surgical devices into the lumen of thedelivery sheath78. The inner diameter of theloading tube254 should be sufficiently similar to the inner diameter of thedelivery sheath78 to create asmooth transition262 from theloading tube254 and thedelivery sheath78. A positive stop (not shown) within thehub94 provides a tactile feedback to the physician to ensure that theloading tube254 is properly seated prior to advancing thetransseptal tip186. Theloading tube254 can be constructed from a polymer (fluoropolymer) that minimizes friction with thetransseptal tip186.
• With thetransseptal tip186 and theanchors202,206 now loaded into thedelivery sheath78, the method of introducing thetransseptal tip186 to the intra-atrial septum42 (FIG. 1) can proceed as shown inFIGS. 6A-6H.
• FIG. 6A illustrates thetransseptal tip186 that has been advanced to theintra-atrial septum42 within theright atrium68. Thetransseptal tip186 can then be advanced to the distal end of thedelivery sheath78.
• Deploying thefirst anchor202, as illustrated inFIG. 6B, begins with the physician confirming that thetransseptal tip186 is advanced to the distal end of thedelivery sheath78 within theleft atrium46. The confirmation can be accomplished by in vivo localization of themarker230 near theintra-atrial septum42. After the confirmation, thedelivery catheter210 andtransseptal tip186 are advanced further into theleft atrium46 while thedelivery sheath78 is held in position. In this way, thetransseptal tip186 extends beyond thedelivery sheath78, and thefirst anchor202 is deployed within the volume of theleft atrium46. Once deployed, thefirst anchor202 can have a diameter that is at least about 1.1 times, but smaller than about 3 times, the diameter of thepuncture138 through theintra-atrial septum42 created by thetransseptal tip186; however, the diameter of thefirst anchor202 in the expanded state is limited primarily by the patient's anatomy. The physician can ensure proper deployment of thefirst anchor202 by in vivo visualization of a radiopaque marker (not shown) on the plurality ofstruts250 of thefirst anchor202.
• Once the proper deployment of thefirst anchor202 is confirmed, the plurality ofstruts158 of the anchoring guide-element142 can be deployed, as shown inFIG. 6C. Accordingly, the position of thetransseptal tip186 is maintained while the anchoringportion150 of the anchoring guide-element142 is advanced beyond thesheath tip178. In this way, the plurality ofstruts158 is deployed within the volume of theleft atrium46. The physician can ensure proper deployment of the plurality ofstruts158 by in vivo visualization of a radiopaque marker (not shown) on the plurality ofstruts158.
• Once proper deployment of the plurality ofstruts158 is confirmed, the anchoring guide-element142 and thedelivery catheter210 with thetransseptal tip186 are retracted until the plurality ofstruts158 contacts thedistal end190 of thetransseptal tip186 and thefirst anchor202 contacts theintra-atrial septum42 within theleft atrium46, as shown inFIG. 6D. Thedelivery device174 for the anchoring guide-element142 can now be fully retracted.
• FIG. 6E illustrates the deployedfirst anchor202 and the deployed plurality ofstruts158 with respect to theintra-atrial septum42.
• To deploy thesecond anchor206, as shown inFIG. 6F, the physician advances a deflatedballoon catheter266 into the lumen of thedelivery catheter210. Theballoon270 of thesuitable balloon catheter266 can be constructed of a compliant to non-compliant material, including Nylon-11, Nylon-12, polyurethane, polybutylene terephthalate (PBT), PEBAX, or polyethylene terephthalate (PET). Theballoon270 is then coupled to the distal portion of acatheter shaft274, which can be constructed of the same or a different material as theballoon270. Coupling of theballoon270 to thecatheter shaft274 can be by thermal bonding, adhesives, solvent, or covalent bonding. A radiopaque marker (not shown) can be included upon the distal end of thecatheter shaft274 for providing in vivo localization and alignment of theballoon270 within thelumen234 of thetransseptal tip186.
• Once theballoon270 of theballoon catheter266 is within thelumen234 of thetransseptal tip186, aninflation fluid271 is used to inflate theballoon270 until it contacts the inner diameter of thetransseptal tip186. This contact may be used to stabilize the position of thetransseptal tip186 during the deployment of thesecond anchor206.
• To deploy thesecond anchor206, thedelivery sheath78 is retracted once again, while the positions of the transseptal tip186 (via thedelivery catheter210 and the inflated balloon catheter266) and the anchoring guide-element142 are maintained. This retraction can be aided by the in vivo visualization of themarker98 on thedelivery sheath78. After sufficient retraction, thesecond anchor206 is deployed and engages theintra-atrial septum42 within theright atrium68. The physician can then confirm that thesecond anchor206 is fully deployed by in vivo visualization of a radiopaque marker (not shown) on the plurality ofstruts250 of thesecond anchor206.
• After confirming that thesecond anchor206 is fully deployed and thedelivery sheath78 is fully retracted, thedelivery catheter210 can be removed from thetransseptal tip186. To remove thedelivery catheter210, as shown inFIG. 6H, theballoon catheter266 remains in contact with the inner surface of thetransseptal tip186 while thedelivery catheter210 is uncoupled from thetransseptal tip186 and fully retracted. Theballoon catheter266 is then deflated and retracted as well.
• As noted above, the use of the primary incision site10 (FIG. 1) is useful for gaining direct access to the intra-atrial septum42 (FIG. 1) and for applying the force necessary to introduce the transseptal tip186 (FIG. 5A) to the intra-atrial septum42 (FIG. 1). However, the remainder of the surgical procedure is preferably accomplished from a secondary incision site24 (FIG. 1). The secondary incision site24 (FIG. 1) allows the physician to use a shorter length of flexible cannula body than if the primary incision site10 (FIG. 1) had been used; however, the method should not be considered so limited. The snare device66 (FIG. 1) is utilized to transition, or move, the operation procedure from the primary incision site10 (FIG. 1) to the secondary incision site24 (FIG. 1).
• FIG. 6I illustrates thebody portion146 of the anchoring guide-element142 extending through thesnare loop70 after the delivery sheath78 (FIG. 6H) and the balloon catheter266 (FIG. 6H) have been retracted from theprimary incision site10.
• FIG. 6J shows thesnare device66 as the physician begins retracting thebody69 of thesnare device66 and transitioning from theprimary incision site10 to thesecondary incision site24. Because the plurality ofstruts158 are secured at theintra-atrial septum42 within theleft atrium46, the plurality ofstruts158 will resist the removal of the anchoring guide-element142 from theintra-atrial septum42. By retracting thesnare device66, aprolapsed portion278 of thebody portion146 is formed. After continued retraction of thesnare device66, the proximal end of thebody portion146 extends through thesecondary incision site24, as shown inFIG. 6K.
• In some embodiments, such as those disclosed in U.S. patent application Ser. No. 12/256,911, the proximal end of thebody portion146 could remain extended through theprimary incision site10 while a medial section of thebody portion146 extends externally from thesecondary incision site24. This embodiment can prevent an inadvertent application of too much force to the anchoringportion150, thereby causing the anchoringportion150 to pull through theintra-atrial septum42.
• With thebody portion146 of the anchoring guide-element142 extending from thesecondary incision site24, the method of advancing the flexible cannula body can continue with reference toFIGS. 6L-6R. However, before the flexible cannula body can be directed into thesecondary incision site24, the dilator53 (FIG. 6K) and the introducer set61 (FIG. 6K) are removed from thehub54 of theintroducer52 extending from thesecondary incision site24 in a manner that is similar to the methods described above.
• FIG. 6L illustrates the advancement of acannula guide282 to thetransseptal tip186, which can be used to align the flexible cannula body (described below) with thetransseptal tip186. Thecannula guide282 includes abody286 and aexpandable member290 having analignment section294, aproximal taper298, and adistal taper302. Theexpandable member290 can be made from a polymeric material and is injection molded or blow molded onto thebody286; however, it is possible to construct thebody286 and theexpandable member290 separately and adhere the components by a chemical adhesion process. Thedistal taper302 is constructed to allow thecannula guide282 to enter the previously implantedtransseptal tip186 while theproximal taper298 is constructed to guide the flexible cannula body onto thealignment section294 in a manner that is described in detail below.
• Thebody286 can be an extruded polymeric material with amarker306 positioned within thealignment section294 to indicate the center of thealignment section294 once assembled. Themarker306 may be constructed from a metallic material, such as gold (Au) or platinum (Pt) or from a polymeric material embedded with a dense powder, such as tungsten (W).
• Thecannula guide282 can then be back-loaded over the anchoring guide-wire142 and advanced to thetransseptal tip186, as shown inFIG. 6L. In some embodiments, it may be preferred for the flexible cannula body (described below) to be back-loaded with thecannula guide282, as a unit, over the anchoring guide-element142. As thecannula guide282 is slowly advanced, thedistal taper302 enters thetransseptal tip186. Yet further advancement causes thealignment section294 to enter thelumen234 of thetransseptal tip186.
• With thecannula guide282 advanced to thetransseptal tip186, thetransseptal tip186 is ready to receive theflexible cannula body310.FIG. 6M illustrates theflexible cannula body310, which includes aproximal end314 and adistal end318 having a receivingportion322. The walls of theflexible cannula body310 are preferably constructed from a biodurable, low durometer thermoplastic or thermoset elastomer material. Specifically, this can include an extruded aliphatic, polycarbonate base polyurethane; aliphatic polyether polyurethane; aromatic polyether polyurethane; aromatic polycarbonate based polyurethane; silicone modified polyurethane, thermoplastic elastomers, copolymers, or blends of urethanes; or silicone that will conform to the tortuosity of the vasculature in which it will reside. At least a portion of theflexible cannula body310 can further include a reinforcing member that provides support and to minimize the chance of kinking. The reinforcing member may be ametallic coil326 or braid (not shown) to enhance the torque response of theflexible cannula body310. As described previously with the delivery catheter210 (FIG. 5A), to further increase the torque response, thecoil326 can be constructed to wind in a direction that is similar to the direction of rotation used to engage the receivingportion322 to the engaging portion198 (FIG. 6N). The reinforcing member will typically terminate prior to the distal and proximal ends318,314 of theflexible cannula body310 so that the distal and proximal ends318,314 are not reinforced and remain pliable.
• Antimicrobial agents can be embedded within the flexible cannula body material prior to the forming process to effectively reduce or eliminate the presence of bio-film and reduce the potential for infection. Alternatively, the antimicrobial agent may be applied to the surface of theflexible cannula body310 after the molding process is complete.
• In some embodiments, a lubricious coating or layer can be included on the exterior of theflexible cannula body310. Such a lubricious layer would aid in the movement of theflexible cannula body310 with respect to the vascular network. Suitable materials for the layer would include etched polytetrafluorethylene (ePTFE), fluorinated ethylene propylene (FEP), ethylene vinyl acetate (EVA), polyvinylidene difluoride (PVDF), high density polyethylene (HDPE), PEBAX, or polyamide materials coated with a lubricious coating similar to HYDROMED.
• Once theflexible cannula body310 is properly formed, it is cut to the desired length. The pliableproximal end314 can be flared for coupling theflexible cannula body310 to a pump (described below) of the circulatory assist device. Alternatively, theproximal end314 can be formed to be about twice the thickness of the remainder of theflexible cannula body310, which can also assist in coupling theflexible cannula body310 to the pump of the circulatory assist device.
• The pliabledistal end318 of theflexible cannula body310 may also be flared for receiving the engagingportion198 in a manner that is described in greater detail below.
• Theflexible cannula body310 can include amarker330 sufficiently near the receivingportion322 and made from a dense metal, such as gold (Au) or platinum (Pt), for providing in vivo localization of the receivingportion322.
• Turning now toFIG. 6N illustrating the flexible cannula body with greater detail, the receivingportion322 can include aninternal seal ring342 within aring groove346. Theseal ring342, once assembled with the engagingportion198, will allow blood flow to transition smoothly from thetransseptal tip186 to theflexible cannula body310, as described in greater detail below. This smooth blood flow also minimizes the potential for thrombus formation between thetransseptal tip186 and theflexible cannula body310. Alumen transition350 can also be provided to further minimize the potential from thrombus formation.
• The receivingportion322 can be coupled to theflexible cannula body310 by any of a variety of means, including mechanical lock, melt flow, or adhesive bonding. By way of example, the mechanical lock can bebarbs354 or other external features that enhance the securement force between thetransseptal tip186 and theflexible cannula body310.
• With the details of theflexible cannula body310 described, the method of coupling theflexible cannula body310 to thetransseptal tip186 continues with reference toFIG. 6N.FIG. 6N illustrates thecannula guide282 fully inserted within thelumen234 of thetransseptal tip186 such that themarker306 aligns with theproximal end194 of thetransseptal tip186. Theexpandable member290 is then inflated such that an outer diameter of adistal portion295 of thealignment section294 engages the inner diameter of thetransseptal tip186. Theexpandable member290, as shown, can be stepped such that aproximal portion296 of thealignment section294 is expandable to a diameter that is slightly less than a diameter of thedistal portion295. This configuration allows thedistal portion295 to contact the inner diameter of thetransseptal tip186 while maintaining a smaller profileproximal portion296 that will allow theflexible cannula body310 to slide over thecannula guide282 and couple to thetransseptal tip186.FIG. 6N also illustrates that in some embodiments, it is permissible for thedistal taper302 of thecannula guide282 to extend beyond thedistal end190 of thetransseptal tip186 and advance the anchoringportion150 of the anchoring guide-element142 slightly distally from thetransseptal tip186; however, this is not required.
• With thecatheter guide282 positioned within thetransseptal tip186, the physician can advance the receivingportion322 of theflexible cannula body310 to the engagingportion198 within theright atrium68. The receivingportion322 has a taperedthread334 that matches thethread232 of the engagingportion198 of thetransseptal tip186, described previously. Thethread334 can be a low profile, highly polished, coarsefemale thread334 that prevents cross threading during engagement of the receivingportion322 with the engagingportion198 of thetransseptal tip186. A lead-in338 to the receivingportion322 can be tapered to allow for alignment of thetransseptal tip186 and the receivingportion322. The receivingportion322 can be a radiopaque material, a polished metallic material (such as titanium (Ti)), or a molded polymeric material (such as nylon) that is compounded using radiopaque filler (for example tantalum (Ta)). In some embodiments, the receivingportion322 can be coated with a material to prevent thrombus growth.
• FIG. 6O illustrates the attaching of theflexible cannula body310 to thetransseptal tip186. The receivingportion322 initially engages theproximal taper298 of thecannula guide282. With further advancement, the receivingportion322 engages thealignment section294 and eventually thetransseptal tip186. Then, while the position of thetransseptal tip186 is maintained by thecannula guide282, the receivingportion322 of theflexible cannula body310 threadably engages the engagingportion198 of thetransseptal tip186 until themarker330 of theflexible cannula body310 is aligned with themarker306 of thecannula guide282. This alignment of themarkers306,330 ensures full engagement and seating of the receivingportion322 onto the engagingportion198. With full engagement, two seals are created: an external seal and an internal seal. The external seal is formed between the receivingportion322 and the mostproximal clamp242. The internal seal is formed between the engagingportion198 and theseal ring342.
• Although it is not specifically shown, the inner diameter of thetransseptal tip186 can be large enough that an embodiment of theflexible cannula body310 traverses the lumen of thetransseptal tip186 and is attached to thedistal end190 of thetransseptal tip186 within theleft atrium46. Appropriate attachment means can include screw threads as described above, magnets, adhesives, or other known means. The attachment can be strengthened by including a porous polymeric material, such as the porous polymeric structure252 (FIG. 5C) described previously with the first andsecond anchors202,206 (FIG. 5C).
• FIG. 6P illustrates the deflation and retraction of thecannula guide282 as well as the retraction of the anchoring guide-element142. The anchoring guide-element142 is removed by maintaining the position of thetransseptal tip186 by theflexible cannula body310 and retracting thebody portion146 of the anchoring guide-element142. This retraction movement will force the anchoringportion150 against thetransseptal tip186, causing the deflection of the plurality ofstruts158 into thelumen234 of thetransseptal tip186. Once the plurality ofstruts158 is deflected, the anchoring guide-element142 is retracted through the lumen of theflexible cannula body310 and out of the secondary incision site24 (FIG. 1), leaving theflexible cannula body310 andtransseptal tip186 implanted, as shown inFIG. 6Q.
• FIG. 6R illustrates the implantedtransseptal tip186 and theflexible cannula body310 as a portion of the circulatory assist system. In that regard, theflexible cannula body310, which extends from thetransseptal tip186 to the secondary incision site24 (via thesuperior vena cava67 and right subclavian vein30), is attached to theinput port358 of theimplantable pump362. Aseparate outflow cannula366 is attached to anoutput port370 of theimplantable pump362, which is then surgically attached so as to communicate with a suitable superficial artery, such as the rightsubclavian artery374. At this time, the physician can position theimplantable pump362 subcutaneously or submuscularly within thesecondary incision site24 or maintain thepump362 externally even after thesecondary incision site24 is closed.
• As also shown inFIG. 6R, thepump362 is operably associated with acontroller378, which can also be implanted or remain external to thepatient12. Asignal transmission382 means is provided between thepump362 and thecontroller378 and can be either a hard-wired or a wireless communications device. In operation, thecontroller378 can regulate the pumping action of thepump362. Additionally, amemory device386 can be included within thecontroller378 that will record pump activity for subsequent physician evaluation and interaction.
• The completed flow of blood according to a preferred embodiment and as shown inFIG. 6R will be as follows: oxygenated blood will travel from theleft atrium46 via the natural path into theleft ventricle390 to theaorta394. From theaorta394, blood moves into the leftsubclavian artery398, the leftcommon carotid402, and thebrachiocephalic trunk406, which supplies oxygenated blood to the rightcommon carotid410 and the rightsubclavian artery374. Oxygenated blood will also enter thetransseptal tip186 andflexible cannula body310 from theleft atrium46. Blood entering theflexible cannula body310 will travel through the lumen of theflexible cannula body310 to theimplantable pump362. Theimplantable pump362 actively pumps blood into theoutflow cannula366 and into the rightsubclavian artery374. From here, the blood is directed into the remainder of the vascular network.
• In some patients, there may be a time after the surgery in which the circulatory assist device is no longer necessary. Thus, it would be beneficial to remove the unnecessary components, such as theimplantable pump362 andflexible cannula body310. Accordingly, one exemplary method of reversing the procedures is illustrated inFIGS. 7A-7G.
• The reverse procedure begins, as illustrated inFIG. 7A, with the physician once again creating an incision near thesecondary incision site24. It would be appreciated that while this procedure will be illustrated from thesecondary incision site24, a similar procedure could also be directed from the primary incision site10 (FIG. 1) or any other appropriate incision site location. It would also be possible for the physician to again use the introducer assembly51 (FIG. 1A) at thesecondary incision site24, though this is not shown.
• With thesecondary incision site24 created, the physician accesses theimplantable pump362 and disconnects theflexible cannula body310 from theinput port358 of theimplantable pump362. Theflexible cannula body310 is then sealed with asuitable cap411. The physician then cuts and ligates theoutflow cannula366 near the rightsubclavian artery374. Theimplantable pump362 with theoutflow cannula366 can then be removed from thesecondary incision site24.
• FIG. 7B illustrates the directing of a guide-wire412 through the lumen of theflexible cannula body310 and into theleft atrium46. While a standard j-shape413 guide-wire412 has been illustrated, it would be understood that other guide-wire shapes, including the anchoring guide-element142 (FIG. 4A) described above, could also be used. Further, while the procedure has been illustrated with thecap411 removed, it would be understood that a suitable sealing device capable of permitting passage of the guide-wire412 could also be used.
• FIG. 7B further illustrates the re-advancing of thecannula guide282 along the guide-wire412 to thetransseptal tip186.
• Once theexpandable member290 is within thetransseptal tip186, as shown inFIG. 7C, it is inflated such that thedistal portion295 of thealignment section294 contacts the inner diameter of thetransseptal tip186 and secures the position of thetransseptal tip186. Theproximal portion296 is stepped such that thealignment section294 does not contact an inner surface of theflexible cannula body310, which also increases the ease of removal. With the position of thetransseptal tip186 secured, the physician can then begin uncoupling theflexible cannula body310 from thetransseptal tip186. Uncoupling of theflexible cannula body310 can occur in a manner that is similar to the method described previously for uncoupling the delivery catheter210 (FIG. 6G) from thetransseptal tip186.
• WhileFIG. 7C illustrates the use of thecannula guide282 in this exemplary procedure, it would be understood that another balloon catheter or device could be used to stabilize the position of thetransseptal tip186 while theflexible cannula body310 is removed.
• FIG. 7D illustrates the retraction of theflexible cannula body310 from thetransseptal tip186. Subsequently, theexpandable member290 of thecannula guide282 is deflated and retracted from thetransseptal tip186, though this step is not specifically shown.
• Finally, the present embodiment includes closing off the shunt created between the left andright atriums46,68 by thetransseptal tip186. One manner of closing off the shunt is for the physician to direct aclosure device422 over the anchoring guide-element142 and through thetransseptal tip186, as illustrated inFIG. 7E.Appropriate closure devices422 can include adistal end426, aproximal end430, and a sealingmatrix434 extending therebetween. Suitable commercially available closure devices can include atrial septal defect closure devices, such as the BIOSTAR by NMT Medical, Inc. or the AMPLATZER Septal Occluder by AGA Medical Corp.
• FIG. 7F illustrates the release of theclosure device422 such that the sealingmatrix434 expands to form first and second fluid-tight seals436,438 at the distal and proximal ends190,194, respectively, of thetransseptal tip186. Alternatively as shown in phantom, the first and second fluid-tight seals440,442 could extend to include the first andsecond anchors202,206. With the fluid-tight seals436,438 in position, the guide-wire412 and anydelivery devices444 associated with the delivery and/or deployment of theclosure device422 are retracted from thetransseptal tip186 and the secondary incision site24 (FIG. 7A).
• With the implantable pump362 (FIG. 7A) and flexible cannula body310 (FIG. 7A) removed, the physician sutures the incisions created in the rightsubclavian vein30 thesecondary incision site24, as shown inFIG. 7G.
• While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or in any combination depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims.

Claims (56)

1. A cannula assembly, comprising:

a flexible cannula body having distal and proximal ends with a lumen extending therebetween, the distal end including a receiving portion;

a transseptal tip having distal and proximal ends, the proximal end including an engaging portion operable to connect to the receiving portion of the flexible cannula body in vivo; and

first and second anchors coupled to the transseptal tip and configured to be deployed from a contracted state to an expanded state, the first and second anchors configured to engage opposite sides of a heart tissue in the expanded state.

2. The cannula assembly ofclaim 1, wherein the engaging portion of the transseptal tip has a threaded surface for threadably engaging the receiving portion of the flexible cannula body.

3. The cannula assembly ofclaim 1, wherein each of the first and second anchors further comprises a plurality of struts extending generally transverse to a lengthwise central axis of the flexible cannula body.

4. The cannula assembly ofclaim 3, wherein the plurality of struts are formed from a superelastic material and are folded to a position generally parallel with the lengthwise central axis when in the contracted state and extend to a position transverse to the lengthwise central axis when in the expanded state.

5. The cannula assembly ofclaim 4, wherein the superelastic material is a tubular structure, a wire, or a flat sheet stock.

6. The cannula assembly ofclaim 3, wherein the plurality of struts of the second anchor further includes a porous polymeric structure.

7. The cannula assembly ofclaim 3, wherein the plurality of struts of the first anchor further includes a porous polymeric structure.

8. The cannula assembly ofclaim 1, wherein the receiving portion of the flexible cannula body further includes a seal ring that engages the proximal end of the transseptal tip and forms a fluid-tight seal within the receiving portion.

9. The cannula assembly ofclaim 1, wherein at least a portion of the flexible cannula body is reinforced with a coil or a braid to increase a torque response of the flexible cannula body.

10. The cannula assembly ofclaim 9, wherein the distal and proximal ends of the flexible cannula body are not reinforced.

11. A transseptal tip delivery system in combination with the cannula assembly ofclaim 1, further comprising:

a delivery catheter having distal and proximal ends and a lumen extending therebetween, the distal end including a receiving portion operable to removably disengage the engaging portion of the transseptal tip in vivo; and

a delivery sheath configured to receive the delivery catheter and the transseptal tip and move relative thereto for deploying the first and second anchors into the expanded state.

12. The transseptal tip delivery system ofclaim 11, wherein the delivery catheter is configured to move the transseptal tip relative to the delivery sheath.

13. The transseptal tip delivery system ofclaim 11 further comprising:

a balloon catheter configured to engage an inner surface of the transseptal tip and to resist movement of the transseptal tip from the heart tissue while the receiving portion of the delivery sheath is disengaged from the engaging portion of the transseptal tip.

14. The transseptal tip delivery system ofclaim 11, wherein the delivery catheter is reinforced with a coil or a braid along at least a portion of its length to increase a torque response of the delivery catheter.

15. A cannula guide in combination with the cannula assembly ofclaim 1, comprising:

an expandable member having distal and proximal tapers and an alignment section therebetween; and

a body extending proximally from the expandable member, the expandable member configured to engage an inner surface of the transseptal tip and to resist movement of the transseptal tip from the heart tissue while the receiving portion of the flexible cannula body is connected to the engaging portion of the transseptal tip.

16. The cannula guide ofclaim 15, wherein the proximal taper is configured to direct the receiving portion of the flexible cannula body to the engaging portion of the transseptal tip.

17. The cannula guide ofclaim 15, wherein the expandable member includes a distal portion for engaging the inner surface of the transseptal tip and a proximal portion having a diameter that is less than a diameter of the distal portion.

18. A method of implanting a cannula assembly within a heart tissue, the cannula assembly including a flexible cannula body having distal and proximal ends with a lumen extending therebetween, the distal end including a receiving portion, a transseptal tip having distal and proximal ends, the proximal end including an engaging portion operable to connect to the receiving portion of the flexible cannula body in vivo, and first and second anchors coupled to the transseptal tip, the first and second anchors configured to be deployed from a contracted state to an expanded state and to engage opposite sides of the heart tissue, the method comprising:

(a) introducing the transseptal tip into the heart tissue;

(b) directing the flexible cannula body to the transseptal tip; and

(c) in vivo connecting the receiving portion of the flexible cannula body to the engaging portion of the transseptal tip.

19. The method according toclaim 18, wherein connecting includes threadably engaging the receiving portion of the flexible cannula body to the engaging portion of the transseptal tip.

20. The method according toclaim 19, wherein the engaging portion of the transseptal tip includes a threaded surface for threadably engaging the receiving portion of the flexible cannula body.

21. The method according toclaim 18, wherein introducing the transseptal tip further comprises:

directing the transseptal tip to the heart tissue; and

deploying the first and second anchors to engage the opposite sides of the heart tissue in the expanded state.

22. The method according toclaim 21, wherein the deploying of the first and second anchors further includes deploying a plurality of struts of the first and second anchors from a position generally parallel with a lengthwise central axis of the flexible cannula body to a position generally transverse to the lengthwise central axis.

23. The method according toclaim 22, wherein the plurality of struts are formed from a superelastic material.

24. The method according toclaim 22, wherein deploying the plurality of struts further includes deploying a porous polymeric structure to engage at least one side of the heart tissue.

25. The method according toclaim 18, wherein directing the transseptal tip further comprises:

threadably engaging a receiving portion of a delivery catheter to the engaging portion of the transseptal tip; and

advancing the delivery catheter with the transseptal tip to the heart tissue.

26. The method according toclaim 25 further comprising:

advancing a delivery sheath through the heart tissue, the delivery sheath including proximal and distal ends and a lumen therebetween;

back-loading the delivery catheter with the transseptal tip through the lumen of the delivery sheath to the heart tissue;

deploying the first anchor by advancing the delivery catheter with the transseptal tip beyond the distal end of the delivery sheath; and

deploying the second anchor by retracting the delivery sheath.

27. The method according toclaim 26 further comprising:

disengaging the delivery catheter from the transseptal tip; and

retracting the delivery catheter from the heart tissue.

28. The method according toclaim 26 further comprising:

advancing an anchoring guide-element through the delivery catheter and the transseptal tip before deploying the first anchor, the anchoring guide-element including a body portion having a distal end and a proximal end, and an anchoring portion at the distal end of the body portion, wherein the anchoring portion is configured to be deployed from a contracted state generally parallel to a lengthwise central axis of the body portion to an expanded state generally transverse to the lengthwise central axis and is operable to resist retraction through the heart tissue; and

deploying the anchoring portion after deploying the first anchor and before deploying the second anchor.

29. The method according toclaim 28, wherein the introducing, directing, and deploying are performed from a primary incision site located substantially near a superficial vein of the lower thorax.

30. The method according toclaim 29 further comprising:

creating a secondary incision site substantially near a superficial vein of the upper thorax;

directing a capture device through the secondary incision site to the primary incision site, the capture device operable to redirect the body portion of the anchoring guide-element from the primary incision site to the secondary incision site; and

transferring a proximal end of the body portion of the anchoring guide-element from the primary incision site to the secondary incision site and before directing the flexible cannula body.

31. The method according toclaim 30, wherein the superficial vein of the upper thorax is a subclavian vein, a jugular vein, or a junction between a subclavian vein and an adjoining jugular vein and the superficial vein of the lower thorax is a femoral vein.

32. The method according toclaim 18, wherein steps (a), (b), and (c) are performed percutaneously with at least one catheter.

33. The method according toclaim 18, further comprising:

directing the transseptal tip to the heart tissue without puncturing a pericardium or a myocardial wall.

34. The method according toclaim 18, wherein the introducing, directing, and deploying are performed from a primary incision site located substantially near a superficial vein of the lower thorax.

35. The method according toclaim 18 further comprising:

directing a cannula guide to the transseptal tip before directing the flexible cannula body, the cannula guide comprising an expandable member having distal and proximal tapers and an alignment section therebetween and a body extending proximally from the expandable member.

36. The method according toclaim 35, wherein the distal taper and at least a portion of the alignment section traverse the lumen of the transseptal tip.

37. The method according toclaim 35, wherein the alignment section contacts an inner surface of the transseptal tip.

38. The method according toclaim 35, wherein the proximal taper guides the flexible cannula body onto the transseptal tip.

39. The method according toclaim 35, wherein the expandable member includes a distal portion and a proximal portion having a diameter that is less than a diameter of the distal portion, wherein the method further comprises:

inflating the expandable member such that the distal portion engages an inner surface of the transseptal tip.

40. An introducer assembly for introducing surgical devices into the vascular system, the introducer assembly comprising:

a removable dilator having an attachment mechanism; and

an introducer including a hub and a sheath extending distally from the hub, the introducer operable to receive the dilator in a movable manner and to maintain a puncture through a vascular wall.

41. The introducer assembly ofclaim 40, wherein the hub of the introducer further includes a hemostatic seal, a grommet, or an O-ring.

42. The introducer assembly ofclaim 40, wherein the removable dilator and the introducer are attached together with a frictional fit operable to prevent leakage of blood from the vascular system.

43. The introducer assembly ofclaim 40, wherein the introducer set includes a sheath introducer, a vascular dilator, and a guide-wire.

44. A method of introducing a surgical device into the vascular network of a patient with an introducer assembly, the introducer assembly including a removable dilator having an attachment mechanism for removably attaching an introducer set and an introducer including a hub and a sheath extending distally from the hub, the method comprising:

attaching the introducer set to the attachment mechanism of the removable dilator, the introducer set including a sheath introducer, a vascular dilator, and a guide-wire;

receiving the removable dilator and the introducer set into the introducer;

creating a puncture in a vessel wall of a blood vessel with the guide-wire;

advancing the introducer assembly over the guide-wire and into the blood vessel, thereby dilating the vessel wall until the hub of the introducer contacts an external surface of the blood vessel;

removing the removable dilator and the introducer set; and

directing the surgical device through the introducer and into the blood vessel.

45. The method according toclaim 44, wherein the directing of the surgical device further includes opening a hemostatic seal within the hub of the introducer.

46. The method according toclaim 44 further comprising:

sealing a proximal end of the hub of the introducer after removing the removable dilator.

47. A method of in vivo coupling a flexible cannula body to a transseptal tip, the flexible cannula body having distal and proximal ends with a lumen extending therebetweeen, the distal end including a receiving portion having a first marker, and the transseptal tip having distal and proximal ends, the proximal end including an engaging portion having a second marker, the method comprising:

directing the flexible cannula body to the transseptal tip;

in vivo localizing the first and second markers;

coupling the receiving portion of the flexible cannula body to the engaging portion of the transseptal tip; and

continuing the coupling until the first marker overlays the second marker.

48. The method of in vivo coupling according toclaim 47, wherein the coupling includes threadably engaging the receiving portion of the flexible cannula body to the engaging portion of the transseptal tip.

49. The method of in vivo coupling according toclaim 47, wherein the coupling includes magnetically attaching the receiving portion of the flexible cannula body to the engaging portion of the transseptal tip.

50. A method of aligning a flexible cannula body to a transseptal tip, in vivo, the flexible cannula body having distal and proximal ends with a lumen extending therebetween, the distal end including a receiving portion, and the transseptal tip having distal and proximal ends, the proximal end including an engaging portion, the method comprising:

directing a cannula guide to the transseptal tip, the cannula guide comprising an expandable member having distal and proximal tapers and an alignment section therebetween and a body extending proximally from the expandable member, the alignment section configured to engage an inner surface of the transseptal tip and to resist movement of the transseptal tip;

inflating the expandable member such that the expandable member engages the inner surface of the transseptal tip; and

advancing the flexible cannula body over the proximal taper to the engaging portion of the transseptal tip.

51. The method according toclaim 50, wherein the inflating includes inflating distal and proximal portions of the expandable member such that the distal portion engages the inner surface of the transseptal tip and the proximal portion is inflated to a diameter that is less than a diameter of the distal portion.

52. A stepped balloon for in vivo alignment of a cannula to a trans-tissue device, the stepped balloon comprising:

an expandable member having distal and proximal tapers and an alignment section therebetween, the alignment section having a distal portion and a proximal portion that is expandable to a diameter that is less than a diameter of the distal portion, the alignment section configured to engage an inner surface of the trans-tissue device; and

a body extending proximally from the expandable member.

53. A method of removing a circulatory assist device, the circulatory assist device including a transseptal tip, a pump, and a flexible cannula body extending proximally from the transseptal tip to the pump, the method comprising:

disengaging the flexible cannula body from the pump;

uncoupling the flexible cannula body from the transseptal tip;

retracting the flexible cannula body; and

sealing the transseptal tip.

54. The method according toclaim 53 further comprising:

advancing a cannula guide to the transseptal tip before uncoupling the flexible cannula body from the transseptal tip, the cannula guide comprising an expandable member having distal and proximal tapers and an alignment section therebetween and a body extending proximally from the expandable member, the alignment section configured to engage an inner surface of the transseptal tip.

55. The method according toclaim 53, wherein the sealing further includes directing a closure device to the transseptal tip and deploying the closure device to seal a lumen of the transseptal tip.

56. The method according toclaim 55, wherein the closure device is an atrial septal defect closure device.

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