Patent ID: 12193674

DETAILED DESCRIPTION

The present invention is directed to various embodiments of a radial support graft device and/or stent-graft useful for various vascular access applications, including but not limited facilitating vascular access in vascular bypass applications, facilitating treatment of atherosclerosis and facilitating arterial venous access for dialysis treatment. In an exemplary embodiment, the devices of the present invention have an expandable flared end, bifurcated design, and/or stent (i.e., radial support structure) pattern configured to facilitate vascular access and substantially sutureless and secure implantation of the device into the vasculature of a patient. Although the present invention will be described with reference to the figures, it should be understood that many alternative forms can embody the present invention. One of skill in the art will additionally appreciate different ways to alter the parameters disclosed, such as the size, shape, or type of elements or materials, in a manner still in keeping with the spirit and scope of the present invention.

Referring now to the exemplary embodiments shown inFIGS.1A through17C, wherein like parts are designated by like reference numerals throughout, these figures illustrate example embodiments of a vascular graft, and methods of producing and using the same according to the present invention. In particular, these embodiments show a vascular graft (e.g., for anastomosis) having an outflow region capable of being expanded, for example, after implantation into a body passageway (e.g., a blood vessel) to restore patency, and methods for using and producing the same.

A vascular graft10, in accordance with an exemplary embodiment of the present invention, is illustrated inFIG.1A. Vascular graft10is configured as a conduit20having a hollow body region43with an internal lumen21formed by wall30. The conduit20comprises at least one inflow aperture32at an inflow end35and an outflow aperture34at an outflow end36of an outflow region42opposite from the at least one inflow aperture32. The inflow end35and outflow end36, of the conduit20are in fluid communication with each other via internal lumen21, which is defined conduit20and extends between the at least one inflow aperture32and the outflow aperture34. The wall30of conduit20is formed by a support structure40and a biocompatible layer50. Support structure40may be any device configured to maintain patency of a vessel. Exemplary support structures40may include stents. In one embodiment support structure40may be an expandable structure and constructed from a shape memory alloy, such as nitinol. In an exemplary embodiment, a biocompatible layer50, which may be configured as a cover, sheath or sleeve, may at least partially or fully cover an exterior surface of support structure40. The support structure40may be separate from the biocompatible layer50, adhered to the biocompatible layer50, at least partially embedded in the material of the biocompatible layer50, or any permutation of the foregoing. The support structure40along the outflow region42is under continuous compressive stress (S) resulting from a continuous applied load caused by the biocompatible layer50against the support structure40. For example, the support structure40may be arranged to springingly or resiliently exert a continuous radially outwardly directed force against the biocompatible layer50, which biocompatible layer50correspondingly exerts the continuous compressive stress on the support structure40.

FIGS.2A,2B, and2Cshow views of the support structure40of the vascular graft10shown inFIG.1A, illustrating the support structure40prior to combination with a biocompatible layer50to form wall30(FIG.2A), after combining the support structure40shown inFIG.2Awith the biocompatible layer50to form wall30(FIG.2B), and after expanding the outflow region42of the support structure40of the vascular graft10shown inFIG.2B(FIG.2C).

InFIG.2A, the support structure40prior to combination with the biocompatible layer50to form the wall30conduit20has varying outer diameter along the length of support structure40. As shown, support structure40has a constant effective outer diameter measurement Dcalong the body region43, and a radially and outwardly flaring effective outer diameter measurement Dincthat increases along at least a portion of the outflow region42towards outflow aperture34to give the outflow region a “flared” shape or appearance, as discussed further below. This outwardly flared configuration of support structure40allows for substantially sutureless attachment and retention of stent graft10within the vasculature of a patient. Upon covering the support structure40with biocompatible layer50, as show inFIG.2A, the flared outflow region42is constricted such that conduit20is reshaped to have a constant effective outer diameter measurement Dcalong the length of body region43and outflow region42, as shown inFIG.2B. In an exemplary embodiment, outflow region42is constructed from a shape-memory alloy, such as a nitinol, that is capable of expanding from its constrained state to achieve and maintain a flared configuration upon application of an expansion force, such as balloon catheter expansion. This shape memory support structure40may be self-expanding, but is unable to assume its flared state without balloon expansion due to the compressive stress applied by biocompatible layer50.2C shows the expanded effective outer diameter measurement Dexpof the support structure40after an external expansion force is applied to the outflow region42of the support structure40inFIG.2B.

FIGS.3A-3O, show various example embodiments of the outflow region42of support structure40, depicting various flared configurations. These illustrations represent the wireframe profile of the support structure40, without depiction its strut pattern. Those skilled in the art will appreciate that a number of different strut patterns can be utilized, and that all such patterns are considered as falling within the scope of the profiles depicted. With regards toFIGS.3K-3O, those skilled in the art will additionally appreciate that the diameter of each support structure segment along the support structure40in the outflow region42may be different, depending on the particular implementation. In the example embodiment ofFIGS.3K and3M, each of the support structure segments is generally constructed from a single zigzag ring (as explained below), such that the support structure segments form a conduit having stepwise increments that increase in diameter as they approach outflow aperture34. In another example embodiment, support structure40may include a plurality of these stepwise increments at a sufficiently frequent intervals such that a portion of outflow region42, i.e. the portion between a proximal and distal end of outflow region42, appear to have a substantially uniform linear change in diameter (e.g.FIG.3A), or alternatively a curvilinear change in diameter (e.g.,FIGS.3F and3I), rather than a stepwise change in diameter. In yet another example embodiment the increments can occur in such a way that the effective outer diameter does not change along at least one segment along the support structure40in the outflow region42(e.g.,FIGS.3B,3C,3G,3J,3L,3M,3N, and3O). In certain example embodiments the increments can occur in such a way that combines any of the configurations above (e.g.,FIGS.3L,3N). Those skilled in the art can readily envision other suitable flared configurations that may be considered to fall within the scope of the present invention.

Turning now toFIG.4, there is illustrated a wire frame design forming an exemplary support structure40construction at outflow region42.FIG.4shows a properly scaled illustration of the support structure40showing the precise relative proportions of the support structure pattern depicted therein in a flat orientation. As shown, the support structure40is constructed of a series of interconnected rings (e.g., R1, Rn, Rn+1, Rn+2, Rn+3, where n=an integer representing), each comprising a substantially zigzag shape comprising a series of peaks and valleys. Once the flattened wire frame is rolled into a three dimensional cylindrical configuration, the peaks or crowns of each ring directly faces and is aligned with a corresponding valley of an adjoining ring and vice versa. This peak to valley arrangement is present throughout the length of support structure40and creates a flexible structure, allowing stent20to bend and turn when implanted.FIG.4illustrates an exemplary strut or stent pattern of support structure40.

In the example shown inFIG.4, the support structure40in the outflow region42has an effective outer diameter measurement Dincthat is incrementally greater at each segment (D, D1, D2, D3) along the support structure40for each incrementally more distal portion or segments extending from the at least one inflow aperture32to the at least one outflow aperture34. In this non-limiting example, the support structure40can be constructed of a series of interconnected rings (e.g., R1, Rn, Rn+1, Rn+2, Rn+3, where n=an integer representing), each comprising a substantially zigzag shape. By way of example, in one embodiment, rings R1and Rnof the support structure40are located in the body region43proximal to the outflow region42, whereas rings R3, R4, and R5are located in the outflow region42, with R5forming an edge of outflow aperture34. Rings R1and Rnof body region43may have the same size and dimension D. Whereas the rings in the body region43are generally have the same size and dimension, rings R3, R4, and R5have incrementally increasing width of a ring (i.e. lengths of the peaks and valleys) D1, D2, and D3. The effective outer diameter measurement of the support structure40increases at each ring segment R as the width of each ring segment D increases. For example, the width D1of ring segment R3is greater than the width D of ring segment Rn, thereby increasing the effective outer diameter measurement of the support structure40at ring segment R3relative to ring segment Rn, the width D2of ring segment R4is greater than the width D1of ring segment R3, thereby increasing the effective outer diameter measurement of the support structure40at ring segment R4relative to ring segment R3, and the width D3of ring segment R5is greater than the width D2of ring segment R4, thereby increasing the effective outer diameter measurement of the support structure40at ring segment R5. The effective outer diameter measurement of this embodiment of support structure40in the outflow region42therefore is incrementally greater at each segment along the support structure40that is incrementally more distal form the at least one inflow aperture32. Although there is shown only 3 ring segments Rn+1, Rn+2, and Rn+3with incrementally increasing dimensions D1, D2, and D3, respectively, it is to be understood that the outflow region42of the support structure40can be provided with more (e.g., 4, 5, 6, etc.) or less (e.g., 2) ring segments R depending on the particular application, as will be appreciated by those skilled in the art.

As shown in the embodiments illustrated inFIGS.3A-3O(described above), any particular segment R (Rn+1, Rn+2, Rn+3) having width D (D1, D2, D3) can be provided with a constant effective outer diameter measurement Dc. In such embodiments, the support structure40flares at each location in the outflow region42in which the effective outer diameter measurement increases and does not flare at each location in which the effective outer diameter measurement remains constant. In some embodiments, the support structure40flares initially, for example, at segment Rn+1due to an incrementally greater width D1relative to width D of Rn, and then levels off at the outflow end36, for example due to a constant effective outer diameter measurement due of the support structure at segments Rn+1and Rn+2(i.e.FIGS.3B-3C). Those skilled in the art will readily appreciate that the length of the initial flare or leveled off section of the outflow region42can vary as desired by increasing the widths D1, or D2and D3, respectively. In certain embodiments illustrated inFIGS.3A through3O(described above), any particular segment R (Rn+1, Rn+2, Rn+3) having width D (D1, D2, D3) can be provided with an effective outer diameter measurement that increases at a greater rate relative to a previous segment R. In certain embodiments illustrated inFIGS.3A through3O(described above), any particular segment R (Rn+1, Rn+2, Rn+3) having width D (D1, D2, D3) can be provided with an effective outer diameter measurement that increases at a lesser rate relative to a previous segment R. It should be appreciated by those of skill in the art that the flared outflow region42can be configured to alter the size and or shape of its flared appearance, as long as the effective outer diameter measurement of the support structure40prior to combination with the biocompatible layer50to form the wall30increases along at least a portion of the outflow region42. Those skilled in the art will appreciate that the appearance (e.g., size, shape, or angle) of the flare in the outflow region42depends, in part, on the widths D1, D2, D3of each ring segment Rn+1, Rn+2, Rn+3, respectively.

Various dimensions D (e.g., D, D1, D2, D3) for ring segments R (e.g., R1, Rn, Rn+1, Rn+2, Rn+3) are contemplated for the support structure40. Table 1 below provides non-limiting examples of dimensions for manufacturing a support structure40having an incrementally increasing effective outer diameter measurement Dincin the outflow region42.

TABLE 1Dimensions for Exemplary Ring Segments Rn+1, Rn+2, Rn+3Constant EffectiveMaximum EffectiveOuter DiameterOuter OutflowMeasurementD (R1− Rn)D1 (Rn+1)D2 (Rn+2)D3 (Rn+3)Diameter(Uncovered)6.0 mm2.18 mm +−2.51 mm +−2.88 mm +−3.10 mm +−11.4-11.6 mm0.45 mm0.45 mm0.45 mm0.45 mm7.0 mm2.04 mm +−2.35 mm +−2.70 mm +−2.90 mm +−12.4-12.6 mm0.45 mm0.45 mm0.45 mm0.45 mm8.0 mm1.89 mm +−2.17 mm +−2.50 mm +−2.69 mm +−13.4-13.6 mm0.45 mm0.45 mm0.45 mm0.45 mm

In the exemplary embodiment shown inFIGS.8A-8Goutlet region42has the same flarable configuration, as shown inFIGS.1A-2Cand as discussed generally above. The inlet region44of this alternative stent graft10may have a pre-fabricated and pre-extended flared configuration prior to implant, as shown inFIGS.8A-8G. Various views of this stent graft embodiment in which support structure40has a pre-fabricated and pre-extended outwardly flaring inflow region44for maintaining or improving patency of the graft along inflow region44. In these examples, the flared shape or appearance is oriented in the opposite direction from the flared shape or appearance at outflow end36. This pre-fabricated and pre-extended flared configuration of inflow region44facilitates friction fitted attachment and positioning within a vasculature.

FIG.8Ashows a side view of the straight vascular graft shown inFIG.1A, illustrating the flared configuration of the inflow region44of the support structure40prior to combination with the biocompatible layer50to form wall30.FIG.8Bshows a schematic view of the straight vascular graft shown inFIG.1A, illustrating the pre-fabricated, pre-extended flared configuration of the support structure40along the inflow region44and expandable out flow region42after combining the support structure40shown inFIG.8Awith the biocompatible layer50to form the wall30.FIG.8Bshows the vascular graft after inflow region44has been expanded.FIG.8Cshows a schematic view of the straight vascular graft shown inFIG.1A, illustrating the expanded effective outer diameter measurement Dexpof the support structure40along the outflow region42.FIG.8Dshows a side wireframe view of the support structure40shown inFIGS.8A and8D.FIG.8Eis a perspective, schematic view showing an actual construction of the support structure40shown inFIG.8A.

With particular reference toFIG.8E, it is evident that the pre-fabricated, pre-expanded flared shape or appearance of the inflow region44is achieved by a similar design methodology to the one described inFIG.4in which ring segments R1and R2of the support structure40are provided with different widths D2, D1, respectively, from each other, as well as different widths D from the ring segments R3to Rn, where n=an integer. The different widths D (e.g., D2, D1, D) of ring segments R (e.g., R1, R2, R3to Rn, where n=an integer) impart the effective outer diameter measurements Dincwhich provide the support structure40along the outflow region42with a flared appearance.

The outflow region42of support structure40may be configured in the same manner as that discussed above and shown inFIG.4B.FIG.8Fshows a schematic view of the support structure40useful for inflow region44according to an exemplary construction. The construction can be utilized for at least two objectives. In a first embodiment, the flared inflow region44creates a pre-fabricated, pre-expanded flared configuration prior to implant. In another embodiment, the pre-expanded and flared configuration provides a locally increased inside diameter that provides space for receiving (e.g., as in a socket) a lumen distinct from biocompatible layer50, although possibly constructed of the same base material as biocompatible layer50. For example, an extension lumen51having a wall thickness that is thicker than layer50may be inserted into the constructed socket such that the inner luminal surface of the extension lumen51will be substantially flush with or at least the same approximate diameter as the inner luminal surface of conduit body portion43.

FIG.8Fshows a scaled illustration of the support structure40showing the precise relative proportions of the support structure pattern depicted therein. Each ring forming conduit body portion43comprises a series of peaks and valleys, best shown as Rnand R3inFIG.8F. The peaks or crowns of each of these rings directly face and are aligned with a corresponding valley of an adjoining ring, and struts connecting adjoining rings builds flexibility into the graft to facilitate in-situ bending. A proximal inflow region35of support structure40includes a plurality of rings in which the peaks or crowns of a ring R2faces the peaks and crowns of adjoining rings R1while the valleys of ring R2directly faces and aligns with valleys of adjoining rings R1to provide additional stiffness at inflow region35.

As is shown inFIG.8F, ring segments R1and R2, which are located proximal to the inflow end35of the inflow region44of the support structure40, are provided with greater widths D2, D1, respectively, than ring segments R3to Rn(where n=an integer), which are located in the body region43of support structure40. Providing ring segment R2with a greater width D1than the width D of ring segment R3causes the wall30adjacent to ring segment R2to flare outward as illustrated by the angled R2segment shown inFIG.8D. The effective outer diameter measurement Dincof the inflow region44shown in this example consists of ring segment R1which comprises a constant effective outer diameter measurement along its width D2, as is illustrated by the line extending along the longitudinal width of ring segment R1shown inFIG.8D. It should be appreciated by those skilled in the art, however, that the support structure40proximal to the inflow region44can be configured in any desirable manner which maximizes patency of the inflow region while vascular graft10is implanted in a body lumen.

Looking now atFIGS.2B and8B, there is shown a schematic view of an embodiment of the vascular graft10shown inFIGS.1A and8Adepicting the generally uniform effective outer diameter measurement of the support structure40after combining the support structure40shown inFIGS.2A and8Awith the biocompatible layer50to form the wall30. Application of biocompatible layer50to an exterior surface of support structure40so as to form wall30places the support structure40in the outflow region42under continuous compressive radial stress S (e.g., radial compressive stress) resulting from a continuous applied load to support structure40by compressing the biocompatible layer50against the support structure40. Generally, the compressive stress S resulting from the continuous applied load in the outflow region42is greater than a compressive stress S0resulting from the applied load in the body region43. Those skilled in the art will appreciate that the compressive stress S resulting from the continuous radially applied load in the outflow region42generally changes along the length of outflow region42as the effective outer diameter of the support structure40in the outflow region42changes. As is shown inFIGS.2B and8B, for example, the compressive stress S experienced by the support structure40resulting from the continuous applied load in the outflow region42incrementally increases along the length of support structure40as it approaches outflow aperture34, i.e. compressive stress S is greater at each segment along the support structure40that is incrementally more distal from the at least one inflow aperture32at the inflow end35. In this example, the compressive stress S is at a minimum Sminat a proximal area of outflow region42and increases, as the effective outer diameter of the support structure40(prior to combination with the biocompatible layer50to form wall30) increases, to a maximum compressive stress Smaxproximal to the outflow end36.

The compressive stress S causes an elastic deformation of the support structure40in the outflow region42. As will be appreciated by those skilled in the art, the extent of the elastic deformation is a function of the compressive stress S resulting from the applied load caused by the biocompatible layer50. In the example shown inFIGS.2B and8B, the elastic deformation of the support structure40in the outflow region42is incrementally greater at each segment along the support structure40that is incrementally more distal from the at least one inflow aperture32, as illustrated by the increasing compressive stress from a minimum compressive stress Sminto a maximum compressive stress Smax.

In contrast to the deformation inducing compressive stress S along the outflow region42, a compressive stress S0resulting from an applied load by biocompatible layer50at inflow distal end35and body region43causes only negligible elastic deformation of the support structure40along the body region43. For the sake of clarity, it is to be understood by those skilled in the art that the negligible compressive stress S0experienced by the support structure40in the body region43resulting from the applied load caused by the biocompatible layer50against the support structure40is negligible relative to the amount of compressive stress S (Sminto Smax) experienced by the support structure40in the outflow region42resulting from the applied load caused by the biocompatible layer50against the support structure40. As used herein, negligible compressive stress S0refers to an amount of compressive stress that is not accompanied by or associated with a change in the effective outer diameter, or is accompanied by or associated with only a very minor amount of change in the effective outer diameter, of the portion or region of the support structure40experiencing the compressive stress S, as will be appreciated by those skilled in the art. In contrast to the negligible compressive stress S0experienced by the support structure40in the body region43after combination with the biocompatible layer50to form wall30, the support structure40in the outflow region42after combination with the biocompatible layer50to form wall30experiences a substantial amount of compressive stress that generally changes as the effective outer diameter measurement of the support structure40prior to combination with biocompatible layer50to form wall30changes. As used herein, “substantial compressive stress” and “continuous compressive stress” are used interchangeably herein to mean an amount of compressive stress that is accompanied by or associated with a change in the effective outer diameter of the portion or region of the support structure40experiencing the compressive stress S in the radial direction, as will be appreciated by those skilled in the art.

The combination of the incrementally greater elastic deformation of the support structure40along the outflow region42with the absence of elastic deformation of the support structure40along the body region43imparts the conduit20with a uniform effective outer diameter measurement, as is illustrated inFIGS.2B and8B. This effective outer diameter measurement comprises a constant effective outer diameter measurement Dcalong the body region43and a constrained effective outer diameter measurement Dconalong the outflow region42. As used herein, “constrained” in connection with “effective outer diameter measurement” refers to the effective outer diameter measurement of the support structure40along the outflow region42under the compressive stress S relative to the effective outer diameter measurement of the support structure40along the outflow region42in the absence of compressive stress S prior to combination of the support structure40with the biocompatible layer50to form the wall30. The constrained effective outer diameter measurement Dconis approximately equal to the constant effective outer diameter measurement Dc. Notably, the compressive stress S resulting from the continuous applied load maintains the support structure40along the outflow region42at the constrained effective outer diameter measurement Dcon.

The elastic deformation of the support structure40along the outflow region42is reversible. The extent to which the elastic deformation of the support structure40along the outflow region42can be reversed depends on a variety of factors, including the length D (e.g., D1, D2, D3) of each ring segment R (e.g., Rn+1, Rn+2, Rn+3), and the amount of counter force applied to the support structure40in the outflow region42, as will be appreciated by those skilled in the art. In this regard, a counter force comprising a radial expansion force applied to the support structure40in the outflow region42causes plastic deformation of the biocompatible layer50. Such counter force causes a reduction of the compressive stress S experienced by the support structure40. In other words, as the counter force increases the plastic deformation of the biocompatible layer50, the compressive stress S experienced by the support structure40decreases, reversing the plastic deformation of the support structure40.

Focusing now onFIGS.2C and8C, there is shown a schematic view of an embodiment of the vascular graft10shown inFIGS.1A and8Adepicting the expanded effective outer diameter measurement Dexpof the support structure40of the vascular graft shown inFIGS.2B and8B, after expanding the outflow region42of the support structure40. As noted above, the expanded effective outer diameter measurement Dexpof the support structure40along the outflow region42results upon application of a counter force comprising a radial expansion force. The present invention contemplates the use of any suitable means for applying such radial expansion force, for example, by advancing a radially expandable device (e.g., a balloon catheter98) along the internal lumen of the conduit20from the at least one inflow aperture32toward the outflow aperture34and expanding the radially expandable element. Other suitable means for applying such radial expansion force are apparent to the skilled artisan.

Those skilled in the art will further appreciate that the present invention contemplates the use of any amount of counter force comprising a radial expansion force which is capable of overcoming the continuous applied load contributed by the biocompatible layer50and thus permits expanding the outflow region42. Preferably, the amount of counter force comprising the radial expansion force used is an amount that results in the atraumatic expansion of the outflow region42within a body lumen. Exemplary ranges of such counter forces will be apparent to the skilled practitioner. For the sake of clarity, however, an exemplary range of counter forces which can result in the atraumatic expansion of the outflow region42in vivo or in situ includes those counter forces which arise from using a semi-compliant balloon that is no more than 2.5 mm (more preferably no more than 2.0 mm) over the effective outer diameter measurement of the outflow region42.

Following application of a counter force comprising a radial expansion force applied to the support structure40in the outflow region42, the graft reconfigures in such a way as to result in a plastically deformed biocompatible layer50. In some instances, following application of a counter force, the vascular graft10reconfigures in such a way as to result in a plastically deformed biocompatible layer50and a compressive stress S experienced by the support structure40that is less than the compressive stress S experienced by the support structure prior40to application of the counter force. In some instances, following application of a counter force, the graft reconfigures in such a way as to result in the support structure40experiencing residual compressive stress S where there was previously continuous compressive stress S (e.g., substantial compressive stress) experienced by the support structure40prior to application of the counter force. As used herein, “residual compressive stress” means an amount of compressive stress S that remains partially as a result of recoil associated with plastic deformation of the biocompatible layer50upon application of the counter force comprising the radial expansion force. Those skilled in the art will appreciate that the amount of such residual compressive stress depends on a variety of factors, including the magnitude of the radial expansion force and the amount of compressive stress S experienced by the support structure40due to the continuous applied load caused by the biocompatible layer50against the support structure40before application of the counter force, for example.

Still looking atFIGS.2C and8C, it is evident that a counter force comprising a radial expansion force applied to the support structure40in the outflow region42reconfigures the support structure40in to the outflow region42from the constrained effective outer diameter measurement Dconshown inFIGS.2B and8Bto an expanded effective outer diameter measurement Dexpshown inFIGS.2C and8Cthat is greater than the constrained effective outer diameter measurement Dconalong at least a portion of the support structure40in the outflow region42. In one embodiment, the change in diameter between the constrained effective outer diameter measurement Dconand the expanded effective outer diameter measurement Dexpis about 0.5 mm to about 2.5 mm or about 1 mm to about 2 mm, and even more 1 mm to 1.5 mm. In accordance with another example embodiment, the expanded effective outer diameter measurement Dexpis at least 1 mm greater than the constrained effective outer diameter measurement Dconalong at least a portion of the support structure40in the outflow region42. Of course, the expanded effective outer diameter measurement Dexpcan be at least 1.10 mm, at least 1.20 mm, at least 1.30 mm, at least 1.40 mm, at least 1.50 mm, at least 1.60 mm, at least 1.70 mm, at least 1.80 mm, at least 1.90 mm, at least 2.0 mm, at least 2.10 mm, at least 2.20 mm, at least 2.30 mm, at least 2.40 mm, at least 2.50 mm, at least 2.60 mm, at least 2.70 mm, at least 2.80 mm, at least 2.90 mm, at least 3.0 mm, at least 3.10 mm, at least 3.20 mm, at least 3.30 mm, at least 3.40 mm, at least 3.50 mm, at least 3.60 mm, at least 3.70 mm, at least 3.80 mm, at least 3.90 mm, at least 4.0 mm, at least 4.10 mm, at least 4.20 mm, at least 4.30 mm, at least 4.40 mm, at least 4.50 mm, at least 4.60 mm, at least 4.70 mm, at least 4.80 mm, at least 4.90 mm, or 5.0 mm or more greater than the constrained effective outer diameter measurement Dconalong at least a portion of the support structure40in the outflow region42, depending on various factors, such as magnitude and duration of the radial expansion force and the length D (e.g., D1, D2, D3, etc.) or amount of ring segments R (e.g., Rn+1, Rn+2, Rn+3, etc.) as will be appreciated by those skilled in the art. In accordance with another example embodiment, the expanded effective outer diameter measurement Dexpof the support structure40along the outflow region42after being reconfigured is at least 1.0 mm greater than the constrained effective outer diameter measurement Dconalong the entire portion of the support structure40in to the outflow region42. In certain example embodiments, the expanded effective outer diameter measurement Dexpcan be at least 1.10 mm, at least 1.20 mm, at least 1.30 mm, at least 1.40 mm, at least 1.50 mm, at least 1.60 mm, at least 1.70 mm, at least 1.80 mm, at least 1.90 mm, at least 2.0 mm, at least 2.10 mm, at least 2.20 mm, at least 2.30 mm, at least 2.40 mm, at least 2.50 mm, at least 2.60 mm, at least 2.70 mm, at least 2.80 mm, at least 2.90 mm, at least 3.0 mm, at least 3.10 mm, at least 3.20 mm, at least 3.30 mm, at least 3.40 mm, at least 3.50 mm, at least 3.60 mm, at least 3.70 mm, at least 3.80 mm, at least 3.90 mm, at least 4.0 mm, at least 4.10 mm, at least 4.20 mm, at least 4.30 mm, at least 4.40 mm, at least 4.50 mm, at least 4.60 mm, at least 4.70 mm, at least 4.80 mm, at least 4.90 mm, or 5.0 mm or more greater than the constrained effective outer diameter measurement Dconalong the entire portion of the support structure40in the outflow region42, as will be appreciated by those skilled in the art.

The support structure40can be constructed from any material that enables the support structure40in the outflow region42to reconfigure from a constrained effective outer diameter measurement Dconto an expanded effective outer diameter measurement Dexpupon application of the counter force. In accordance with one example embodiment, the support structure40is constructed from a shape memory alloy. Exemplary shape memory alloys can be formed from a combination of metals including, but not limited to: aluminum, cobalt, chromium, copper, gold, iron, nickel, platinum, tantalum, and titanium. In accordance with one example embodiment, the support structure40is constructed from nitinol. Other shape memory alloys or other materials which can be used to construct the support structure40are apparent to the skilled artisan.

Those skilled in the art will appreciate that the support structure40can be constructed with a larger or smaller expandable portion. The skilled artisan will also appreciate that the same methodology described above in connection withFIG.3which enables outflow region42to be expandable can be applied to render other portions of the support structure40expandable (e.g., the body region).

The biocompatible layer50can be constructed from any biocompatible material. The material may further be substantially impermeable to fluid in certain embodiments. The material is capable of causing a continuous applied load to place the support structure40under a sufficient continuous compressive stress (e.g., substantial compressive stress as defined herein) to maintain the constrained effective outer diameter measurement Dconof the support structure40along the outflow region42after combining the support structure40with the biocompatible layer50to form the wall30. In accordance with an example embodiment, the biocompatible layer50comprises an expandable polymer. In accordance with an example embodiment, the biocompatible layer50comprises expanded polytetrafluoroethylene (ePTFE).

Generally, as is shown inFIGS.2B-2C and8B-8C, the biocompatible layer50extends at least along the entire longitudinal length of the support structure40from the inflow end35to the outflow end36. As will be appreciated by those skilled in the art, the biocompatible layer50may extend at least partially beyond, or fall short of, the inflow end35and the outflow end36in accordance with acceptable manufacturing specifications. In accordance with one example embodiment, the biocompatible layer50can extend beyond the edge of the inflow end35and the outflow end36and wrap around at least a portion of the interior surface of the support structure40in the form of a cuff.

Referring toFIGS.5A,5B,5C and5D, there are shown example cross-sections of vascular graft10shown inFIGS.1A and8A, depicting various ways in which the biocompatible layer50can be configured. As can be seen in the exemplary embodiments ofFIGS.5A and5C, the biocompatible layer50can comprise a biocompatible outer layer54and a separate biocompatible inner layer55spaced apart therefrom such that outer layer54and inner layer55are positioned on opposite sides of support structure40. As shown inFIGS.5A and5B, the biocompatible outer layer54and the biocompatible inner layer55can be configured as distinct layers of the same substrate continuously wrapped around an end of the support structure40or instead as two separate substrates (i.e., non-continuous) that are positioned at opposite sides of the support structure40. In this example, either the biocompatible outer layer54or the biocompatible inner layer55may extend at least partially beyond and wrap around the edge of the inflow end35and outflow end36to form a cuff, for example, to minimize damage to surrounding tissue during deployment of the vascular graft10. The circled portion ofFIG.5Ais represented asFIG.5Band shows an exploded view of a portion of the biocompatible layer50showing how the biocompatible outer layer54and the biocompatible inner layer55conform to each other and the support structure40as a result of how the layers may be applied, heated, sintered, or otherwise adhered on or to the support structure40, methods of which are known to those of skill in the art. As shown in the example embodiment inFIG.5B, the biocompatible layer50can comprise a biocompatible outer layer54without a biocompatible inner layer55. Those skilled in the art will appreciate, however, that the biocompatible inner layer can help to decrease the likelihood of stenosis or occlusion in the conduit20of the vascular graft10or to alter the fluid impermeability of the wall30.FIGS.5A-5Dshow an example embodiment of the vascular graft10in which the biocompatible layer50encapsulates the support structure40with the biocompatible outer layer54and the biocompatible inner layer55. In this example, the biocompatible outer layer54and the biocompatible inner layer55can be configured to encapsulate the support structure40. All known methods and structures relating to the application or use of a biocompatible layer such as those described herein are anticipated for use in conjunction with the present invention, such that the form of the layer on the support structure is not limited by the particular illustrative examples provided herein.

In an exemplary embodiment, biocompatible layer50is configured as a sheath, sleeve or other covering that binds and applies a compressive stress to support structure40. In an exemplary embodiment, biocompatible layer50, particularly biocompatible outer layer54, is adhesively bound to an exterior surface of support structure40forming a constricting and continuous covering over support structure40. The covering may be constructed from any suitable biocompatible material, particularly ePTFE that is processed to apply a compressive force against support structure40. In an exemplary embodiment, biocompatible layer50, including biocompatible outer layer54and/or biocompatible inner55form hemocompatible coverings configured and adapted for engaging tissue and/or blood. It should be appreciated that the biocompatible layer50described herein is distinguishable from a mere surface modifying coating that is conventionally applied to medical devices for purposes of delivering a therapeutic agent or changing the surface characteristics of a medical device, for example, a hydrophilic coating. Nevertheless, it is contemplated that such surface-modifying coatings, for example a coating comprising a biological oil or fat, as is described in U.S. Pat. No. 8,124,127 (which is incorporated herein by reference in its entirety), can be used to coat at least a portion of a surface of the support structure40or the biocompatible outer54and inner55layers, for reasons that would be evident to those skilled in the art. For example, it may be desirable to coat at least a portion of the interior surface of support structure40or the biocompatible inner layer55with a cured fish oil coating containing an anti-clotting therapeutic agent to prevent or minimize occlusion of the implanted graft.

Turning now toFIG.1B, an alternative embodiment of a vascular graft10′ is shown. Whereas the example shown inFIG.1Adepicts a straight vascular graft10, the vascular graft10′ ofFIG.1Bmay be designed to include a second inflow aperture33to provide a bifurcated or generally T-shaped vascular graft10′, as is depicted in the example shown inFIG.1B. It is to be understood that any description given with respect to components common to both of the grafts10and10′ (i.e., those components identified with the same reference numerals) is generally applicable to both of the embodiments, unless otherwise indicated. As is shown inFIG.1B, a longitudinal axis of the second inflow aperture33intersects a longitudinal axis of the at least one inflow aperture32at a non-parallel angle. As used herein, “non-parallel angle” means an angle in which the longitudinal axis of the at least one inflow aperture32is not parallel to the longitudinal axis of the second inflow aperture33(e.g., greater than 0°). The non-parallel angle can be any non-parallel greater than 0° and less than 180° depending on the particular arrangement needed for the graft implantation. Preferably, the non-parallel angle at which the longitudinal axis of the second inflow aperture33intersects the longitudinal axis of the at least one inflow aperture32is between about 25° and about 45°. In accordance with one example embodiment, the non-parallel angle at which the longitudinal axis of the second inflow aperture33intersects the longitudinal axis of the at least one inflow aperture32is about 35°.

FIGS.6A,6B, and6Cshow various views of embodiments of a support structure40of the bifurcated vascular graft110construction shown inFIG.1B, illustrating the support structure40prior to combination with the biocompatible layer50to form the wall30(FIG.6A), after combining the support structure40shown inFIG.6Awith the biocompatible layer50to form wall30(FIG.6B), and after expanding the outflow region42of the biocompatible layer50covered support structure40of the vascular graft110shown inFIG.6B(FIG.6C). Those skilled in the art will appreciate that the description of the structure, function, and components of the straight vascular graft110above in connection withFIGS.2A-5Cis equally applicable to the bifurcated vascular graft110shown inFIGS.6A-6C.

Referring now toFIGS.7A-7C, there is shown in a top view (FIG.7A), a top wireframe view (FIG.7B), and a side wireframe view (FIG.7C) of an embodiment of a support structure of the vascular graft shown inFIGS.1B,6A-6C, depicting the support structure with only at least one inflow aperture32(see, e.g.,FIG.5A) and an outflow aperture34(see, e.g.,FIG.5C) before the second inflow aperture33is attached to the graft body to form the bifurcated vascular graft10′ shown inFIGS.1B and6A-6C. As will be appreciated by those skilled in the art, the support structure40featured inFIGS.7A-7Cincludes all of the pertinent features of the vascular graft10′ shown inFIGS.6A-6C.FIG.7Ashows a properly scaled illustration of the support structure40showing the precise relative proportions of the support structure and its strut/stent pattern. As shown in the example embodiment inFIGS.7A-7B, the support structure also includes a junction aperture37to which a hollow branch conduit99is connected. Junction aperture37and the second inflow aperture33of branch conduit99is in fluid communication with the at least one inflow aperture32and outflow aperture34. As is shown in the example inFIG.7A, the support structure40can terminate in one or more blunt ends41, for example, to prevent or minimize damage to the biocompatible layer50caused by the support structure40. The blunt ends41can be formed in a keyhole like shape as shown inFIG.7A, or any other shape which enables the blunt ends41to prevent or minimize damage to the biocompatible layer50by the support structure40.

To facilitate attachment of the branch conduit99and its second inflow aperture33to the body region43of the support structure40at junction aperture37, a depression39is provided in the contour of the body region43of support structure40, as is illustrated in the example embodiment inFIG.7C. Branch conduit may then be sewn, sintered or otherwise attached to body region43at depression39.

Turning now toFIGS.9A-9H, there is shown various views of another embodiment of the bifurcated vascular graft410similar to that shown inFIGS.1B,6A-6Cand having a branch conduit99with a pre-fabricated and pre-expanded flared configuration at second inflow aperture33of the branch conduit99prior to implantation. With the exception of this flared configuration, the vascular graft410may have the same structure, components and configuration as that of the vascular graft110ofFIGS.1B and6A-6C. This pre-fabricated, pre-expanded flared configuration anchors and provides rigidity and structure to the adjoining conduit body43. The flared end may also facilitate vascular attachment and implantation.FIG.9Ashows a side view of an embodiment of a support structure40of the bifurcated vascular graft110shown inFIGS.1B,6A-6C, illustrating the support structure40prior to combination with the biocompatible layer50to form wall30.FIG.9Bshows a schematic view of an embodiment of the bifurcated vascular graft110shown inFIG.1B,6A-6Cafter combining the support structure40shown inFIG.9Awith the biocompatible layer50to form wall30.FIG.9Cshows a schematic view of an embodiment of the bifurcated vascular graft410construction shown inFIGS.1B and6A-6Cafter expanding the outflow end36of the support structure40of the bifurcated vascular graft410shown inFIG.9B.FIG.9Dis a perspective, schematic view showing a working prototype of the embodiment of the support structure40shown inFIG.9A.FIG.9Eis a perspective, schematic view of a working prototype of the embodiment of the bifurcated vascular graft shown inFIG.9B, depicting the constrained effective outer diameter measurement Dcon of the support structure40along the outflow region42.FIG.9Fis a perspective, schematic view of a working prototype of the embodiment of the bifurcated vascular graft shown inFIG.9C, depicting the expanded effective outer diameter measurement Dexp of the support structure40along the outflow region42and an expanded effective outer diameter measurement Dexp along an inflow region44proximal to the second inflow aperture33.FIG.9Gis another perspective, schematic view similar toFIG.9Ffurther illustrating a border94which is used inFIG.9Hto show schematically as a detail view of a representative cross-section of an embodiment ofFIGS.9B and9C.

Referring toFIG.9G, an extension conduit51is shown assembled to a flared socket-like construction. Utilizing the flared second inflow aperture33, the extension conduit can connect to the luminal surface of branch conduit99when the branch conduit is covered with the biocompatible layer on one or both of the interior and exterior surfaces of the branch's support structure. When an extension conduit comprising a thicker wall89than the wall thicknesses87and88of the inner biocompatible layer55and outer compatible layer54respectively, the enlargened inner diameter of the branch provides sufficient room for the extension conduit to have a diameter that is substantially the same as the inner diameter of all or at least a majority of the branch conduit's inner luminal diameter.

Those skilled in the art will appreciate that in the example embodiments shown inFIGS.9A-9G, the bifurcated vascular graft110and various features of the support structure40function in substantially the same way as described in the relevant paragraphs above.

In accordance with one example embodiment, a vascular graft110comprises: a conduit20having a wall30, the conduit20comprising: at least one inflow aperture32at an inflow end35at a body region43; and an outflow aperture34at an outflow end36at an outflow region42opposite from the at least one inflow aperture32; wherein the wall30comprises a support structure40and a biocompatible layer50; wherein prior to combination with the biocompatible layer50to form the wall30, the support structure40comprises multiple effective outer diameter measurements along its length comprising a constant effective outer diameter measurement Dcalong the body region, and an effective outer diameter measurement Dincalong the outflow region that is incrementally greater at each segment along the support structure40that is incrementally more distal from the at least one inflow aperture32; wherein after combination with the biocompatible layer50to form the wall30, the support structure40in the outflow region42is under continuous compressive stress S resulting from a continuous applied load caused by the biocompatible layer which maintains the support structure40in the outflow region at a constrained effective outer diameter measurement Dconthat is not incrementally greater at each segment along the support structure that is incrementally more distal from the at least one inflow aperture; and wherein after application of a counter force to the support structure40in the outflow region42the outflow region42is reconfigured from the constrained effective outer diameter measurement Dconto an expanded effective outer diameter measurement Dexp, at least a portion of which is at least one millimeter greater than the constrained effective outer diameter measurement Dcon.

The straight and bifurcated or T-shaped vascular grafts (e.g., the grafts10and110) of the present invention can be used for a variety of applications, including, for example, for replacement or bypass of diseased vessels in patients suffering from occlusive or aneurysmal diseases, in trauma patients requiring vascular replacement, for dialysis access, to improve flow dynamics and reduce arterialized pressure during surgical anastomosis, or other vascular procedures routinely performed by a medical practitioner, as will be apparent to those skilled in the art.

In operation, the present taught vascular grafts (e.g., the grafts10and110) are deployed for implantation into a body passage (e.g., a blood vessel). Embodiments of the present invention contemplate any operable method of deploying a vascular graft10/110for implantation into a body passage safely and effectively. Suitable methods will be apparent to the skilled medical practitioner. For example, one known method of deploying such a graft is to use a sheath with a tear line or “rip cord”. The graft is contained within one or more sheaths for delivery to the desired location, preferably in a compressed condition such that the outer diameter of the sheath(s) is 2 or more millimeters smaller than the vessel the graft (or graft portion) is intended to be implanted within. Once properly located, a cord is pulled to separate the sheath along a tear line, and the sheath is then unwrapped from the graft and removed, leaving the graft in place at least partially due to the graft's self-expanding qualities. The general method of installing a graft using a single sheath in this manner is well known in the art, and as such requires no further description.

Once implanted in a body passage, the outflow region42of the vascular graft10can be expanded to maintain or restore patency of the graft, even after extensive duration of time passing from the time of original implantation (e.g., weeks, months, years). For example, if a portion of the graft collapses (e.g., due to tissue in-growth and eventually thrombosis formation), becomes stenosed, or sustains intimal hyperplasia, patency can be restored by expanding the outflow region42of the vascular graft10according to inventive methods described herein.

FIGS.10A and10Bare schematic illustrations of an expandable device being used to expand the outflow region42of an embodiment of vascular graft10which is provided with a bifurcated construction, although may also be employed for non-bifurcated constructions. More specifically,FIG.10Bis a detail view taken about the border86ofFIG.10A. In the example shown inFIGS.10A-10B, the expandable device comprises a balloon catheter98with a balloon97. Those skilled in the art, however, will appreciate that any expandable device which is capable of applying a counter force comprising a radial expansion force can be used.FIGS.10A-10Bare also instructive as to the installation of the graft110illustrated in this embodiment.

FIG.11is a perspective, schematic view demonstrating an expandable device86being used to expand an outflow region42of a vascular graft110which is provided with a bifurcated construction. The expandable device would be equally applicable to straight vascular grafts such as vascular graft10.

Those skilled in the art will readily envision a variety of methods for expanding an outflow region42of the vascular graft10.

In accordance with an example embodiment, a method100of expanding an outflow region42of an implanted vascular graft10generally comprises the steps of (a) identifying or providing102a vascular graft10having a support structure configured with a flared outflow region42according to any aspect of the present invention; and (b) applying a counter force108to the support structure40in the flared outflow region42to expand the outflow region42.

In step102, the implanted vascular graft10comprises: a conduit20having a wall30, the conduit20comprising: at least one inflow aperture32at an inflow end35of a body region43; and an outflow aperture at the outflow end of an outflow region42opposite from the at least one inflow aperture32; wherein the wall comprises a support structure40and a biocompatible layer50; wherein the support structure40in the outflow region42is under compressive stress S resulting from an applied load caused by the biocompatible layer50. In step108, applying a counter force to the support structure40in the outflow region42reconfigures the support structure40in the outflow region42from a constrained effective outer diameter measurement Dconto an expanded effective outer diameter measurement Dexpthat is greater than the constrained effective outer diameter measurement Dcon, thereby expanding the outflow region42of the implanted vascular graft10.

FIG.12shows a flow chart depicting an exemplary embodiment of a method100of expanding an outflow region42of a vascular graft10according to one aspect of the present invention.

As shown in the exemplary embodiment inFIG.12, a method of expanding an outflow region42of an implanted vascular graft10includes steps102to108. Step102comprises: (a) identifying an implanted vascular graft10described herein. To expand the implanted vascular graft10identified in step102, step108is conducted. Step108comprises: (b) applying a counter force to the support structure40in the outflow region42in accordance with the detailed description herein, thereby expanding the outflow region42of the implanted vascular graft10.

It should be appreciated that although the expandable outflow region42can be expanded at any time post-implantation, in practice the outflow region is advantageously expanded when the outflow region42has collapsed or stenosed or has sustained intimal hyperplasia. In such instances, the outflow region42that has collapsed, stenosed, or sustained intimal hyperplasia impairs patency of a vessel in which the implanted vascular graft10is implanted.

In an exemplary embodiment, applying the counter force comprises expanding an expandable device in the outflow region42of the implanted vascular graft10. In an exemplary embodiment, prior to expanding the expandable device (step108) the expandable device is advanced to the outflow end (step106).

In an exemplary embodiment, prior to advancing the expandable device to the outflow region (step106), the expandable device is introduced into the implanted graft percutaneously (step104). In an exemplary embodiment, after expanding the expandable device10, the expandable device is removed according to step110.

In an exemplary embodiment, the expanded effective outer diameter measurement Dexpis at least one millimeter greater than the constrained effective outer diameter measurement Dcon. In another exemplary embodiment, the expanded effective outer diameter measurement Dexpis at least one millimeter greater than the constrained effective outer diameter measurement Dconalong any portion of the support structure40in the outflow region42.

Contemplated herein are various methods for making a vascular graft10disclosed herein.

FIG.13is a flow chart depicting an exemplary method200of making a vascular graft10according to one aspect of the present invention.

In an exemplary embodiment, a method200of making a vascular graft10having an expandable outflow region comprises steps202to209. In the example shown inFIG.13, the method200proceeds with: (a) providing a support structure (step202) in accordance with the detailed description provided herein. comprising at least one inflow aperture32at an inflow end35of a body region43and an outflow aperture34at an outflow end36of an outflow region42opposite from the at least one inflow aperture32. The support structure40may be sized through the use of various mandrels to have multiple effective outer diameter measurements comprising a constant effective outer diameter measurement Dcalong the body region43of the support structure40in addition to an incrementally increasing effective outer diameter measurement Dincalong the outflow region42of the support structure. It should be appreciated by those skilled in the art that the support structure40provided in step202can include any support structure40contemplated herein, including the embodiments shown inFIGS.2A,5A,7A, and8A, which can be provided with an inflow region44or outflow region42with a flared configuration illustrated inFIGS.3A-3O, or any combination thereof.

Once the support structure40is provided in step202, the method200proceeds with step204which comprises: (b) combining the support structure40with at least one biocompatible layer50to form a conduit20having a wall30comprising the support structure40and the at least one biocompatible layer50.

After combining the support structure40with the biocompatible layer50in step204, the method continues with step206which comprises: (c) inserting a mandrel into the outflow aperture34proximal to the outflow end36of the support structure40.

With the mandrel inserted into the outflow aperture34, the method proceeds with step208, which comprises: (d) constraining the incrementally increasing effective outer diameter measurement Dincalong the outflow region42of the support structure40, for example with a compression wrap, in such a way that a continuous compressive stress S results from a continuous applied load caused by the biocompatible layer50which maintains the support structure40along the outflow region42in a constrained effective outer diameter measurement Dconthat is generally uniform with the constant effective outer diameter measurement Dc.

To conform the biocompatible layer50to the support structure40, the method comprises step209of (e) sintering the biocompatible layer50at a segment in the outflow region42.

FIG.14Ais a perspective, schematic view illustrating step206of a method200of making a vascular graft10according to one aspect of the present invention in which a mandrel is inserted into the outflow end36of the vascular graft10prior to constraining the effective outer diameter measurement along the outflow end of the support structure40with a compression wrap.

FIG.14Bis a perspective, schematic view illustrating a step206of a method200of making a vascular graft10according to one aspect of the present invention in which a compression wrap is used to constrain the effective outer diameter measurement along the outflow end of the support structure40.

In another exemplary embodiment of the invention, a vascular graft510is illustrated inFIGS.15A-C. The graft510is formed by a pair of bifurcated graft subassemblies302aand302b(collectively, the “bifurcated subassemblies302”), arranged as mirror images of each other, and connected by an extension conduit51. Each of the bifurcated subassemblies302, may be arranged, as illustrated, to resemble the bifurcated vascular grafts110. As discussed in more detail with respect toFIGS.16A-16C and17A-17C, further vascular graft embodiments can be formed by exchanging one or both of the bifurcated subassemblies302with graft subassemblies resembling the graft10. Accordingly, the components of the graft510that are akin to those of the grafts10and/or110(e.g., the conduit20, the wall30, the support structure40, the biocompatible layer50, etc.), have correspondingly been given the same reference numerals as those used with respect to the above discussion of the grafts10and110.

FIG.15Aillustrates the bifurcated subassemblies without a biocompatible layer50, whileFIG.15Billustrates the bifurcated subassemblies with both the biocompatible layer50and an extension lumen51establishing a continuous conduit between the subassemblies. In various embodiments, the extension lumen51may be a multilayer laminate configuration of ePTFB and has a thickness89greater than the thickness of the inner layer55and outer layer54of biocompatible layer50.

As illustrated inFIG.15C, the bifurcated subassemblies302aand302bare insertable within a first vessel portion306aand a second vessel portion306b, respectively (collectively the vessel portions306). The conduit section51is arranged as a luminal structure that provides fluid communication, e.g., blood flow, between the bifurcated subassemblies302, and therefore, the vessel portions306. Due to the bifurcations of both of the subassemblies302, at least a portion of blood flow, i.e., the blood flow that is not diverted into the conduit section51, may also continue through and past the subassemblies302. The wall30of the conduit section51may be unreinforced, that is, including only the biocompatible layer50and not the support structure40. It is to be appreciated that the conduit section51may be any desired length. For example, relatively shorter lengths may be used in some embodiments, e.g., to bridge or bypass an occlusion in a blood vessel, while relatively longer lengths are used in other embodiments, e.g., to connect an artery to a vein for assisting in dialysis. In one embodiment, the conduit section51is between about 20 mm and 150 mm, although other lengths are also possible.

It is to be appreciated that the graft510may be used in embodiments in which the vessels306are different parts of the same vessel, or in embodiments in which the vessel portions306are parts of different vessels. For example, if the vessel portions306are part of the same vessel, the graft510may be used to create a bypass of a section of the vessel located between the vessel portions306aand306b. For example, an occlusion, such as plaque buildup, may completely or partially impede or block blood flow within a blood vessel of a patient. In this example, the graft510may accordingly be installed such that the conduit section51provides a bypass of the occlusion when the subassemblies302are installed into the blood vessel on opposite sides of the occlusion.

As another example, in one embodiment, one of the vessel portions306(e.g., the vessel306a) is a part of an artery, and the other of the vessel portions (e.g., the vessel306b) is part of a vein. In this way, the conduit section51diverts a portion of blood flowing through the artery into the vein. For example, this embodiment may be particularly useful in that the conduit section51may provide a suitable target to assist a patient in undergoing dialysis, e.g., with the blood diverted between the artery and vein taken from and re-injected into the conduit section51, thus avoiding unnecessary damage to a patient's vasculature that may result from repeated dialysis treatments. In such embodiments, the ability for the conduit section51to seal after needle punctures is enhanced versus the properties of the vascular graft510that might be covered by a thinner material than used in the conduit section51.

A vascular graft610is illustrated inFIGS.16A-16C, and generally resembles the graft510, e.g., including a pair of graft subassemblies312aand312b(collectively, the “subassemblies312”) connected together by a conduit section51. Unlike the graft510, in which both of the subassemblies302resemble the bifurcated graft110ofFIG.1B, the subassembly312bof the graft610is a straight graft subassembly that generally resembles the straight vascular graft10ofFIG.1A, while the subassembly312ais a bifurcated graft subassembly resembling the graft110. It is noted that due to the lack of bifurcation of the subassembly312bin this embodiment, blood flowing through the vessel portion306bmay be blocked or impeded by the subassembly312b. That is, all or most of the blood flow that is flowing through the vessel portion306bin the direction of the subassembly312afrom the subassembly312bwill be diverted through the conduit section51instead of continuing through the vessel portion306b. Thus, the graft610is particularly advantageous in embodiments in which blood flow through the vessel portion306bon both sides of the subassembly312bis not necessary, e.g., such as when the vessel portions306are part of the same vessel, and an occlusion is present therebetween, and thus a bypass of that occlusion is desired.

A vascular graft710is illustrated inFIGS.17A-17C, and generally resembles the grafts510and/or610, e.g., including a pair of graft subassemblies322aand322b(collectively, the “subassemblies322”) connected together by a conduit section51. Similar to the subassembly312bof the graft610, both of the subassemblies322are straight graft subassemblies, resembling the graft10without bifurcations. For this reason, and similar to the subassembly312b, both of the subassemblies322may block or impede blood flow through the respective vessel portion306in which they are inserted. Thus, the graft710may accordingly be particularly useful in embodiments in which an occlusion is present between the vessel portions306, and thus a bypass of that occlusion is desired.

It is to be appreciated that the subassemblies510,610, and710may include tapered, trumpeted, or flared inflow and/or outflow regions, according to the above descriptions thereof. That is, the support structures40in the subassemblies510,610, and/or710may be arranged and constructed of nitinol or other shape memory material, or otherwise be configured to naturally transition to a radially expanded shape. Additionally, the support structure40may, similar to the above disclosure herein, be further radially expanded by use of an inflatable balloon97or other device inserted within the support structure40.

Numerous modifications and alternative embodiments of the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure may vary substantially without departing from the spirit of the present invention, and exclusive use of all modifications that come within the scope of the appended claims is reserved. Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. It is intended that the present invention be limited only to the extent required by the appended claims and the applicable rules of law.

It is also to be understood that the following claims are to cover all generic and specific features of the invention described herein, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.