Patent Description:
Stents have been used for many years to treat vessel disorders by allowing flow and/or preventing vessel narrowing. Narrowing vessels disrupt blood flow and can create pressure imbalances in the vasculature. Such conditions can eventually lead to serious cardiovascular compromise and/or death. For many years the definitive treatment for such disorders was the surgical repair or replacement of the vessel segment through open heart surgery, but such surgeries are dangerous and prone to complication. Open heart surgery in neonatal and young patients may lead to negative developmental effects.

Stents have also been utilized for holding vessels open, but the growth of the patient prevents stents from being implanted at early development states as they would not be able to grow to the adult sizes. Typically, stents have specific, limited ranges of operation.

In view of the foregoing, a need exists for an improved stent for implantation in young patients and subsequent expansion as the patients grow that overcomes the aforementioned obstacles and deficiencies of currently-available stents. D1 (<CIT>) relates generally to expandable stent valve devices for tissue implantation and methods of use. D2 (<CIT>) relates generally to a cardiovascular valve assembly, and more specifically relates to a cardiovascular valve assembly comprised of a resizable base member that remains in a patient, and a valve member that is detachably mountable to the resizable base member. D3 (<CIT>) relates generally to a radially expandable vascular support which has a plurality of mutually flexibly connected meandering ring elements which define a vascular support having a proximal and a distal end and a longitudinal axis, wherein the ring elements along the longitudinal axis of the vascular support are arranged side by side and adjacent ring elements are interconnected by connecting elements.

The present disclosure relates to a growth stent for implantation in young patients according to claim <NUM>. This disclosure also relates to non-claimed methods for making and using such growth stents.

The growth stent can subsequently be expanded to adult vessel sizes as the patients grow, while maintaining proper strength for vessel opening throughout an entire range of expansion. In accordance with a first aspect disclosed herein, there is set forth a catheter insertable and re-expandable growth stent for implantation in a neonate patient, comprising: an elongated stent frame with a plurality of frame struts each having a predetermined frame strut width and a predetermined strut thickness and extending continuously from a proximal end region of said stent frame to a distal end region of said stent frame, adjacent frame struts defining a predetermined number of intermediate frame cells and intersecting to form respective strut junctions with junction widths by which said elongated stent frame expands via a delivery catheter from an initial state with a diameter that is less than eight French (<NUM>) for facilitating insertion via the delivery catheter into a selected lumen of the neonate patient to a first expanded state that has a first predetermined expanded size, shape, diameter, cross-section and/or other dimension that is greater than that of the initial state at implantation, said stent frame in the first expanded state defining an internal channel with a first cross-section, wherein the strut junctions further enable said stent frame to be re-expanded via subsequent introduction of a dilation catheter from the first expanded state to a second expanded state that has a second predetermined expanded size, shape, diameter, cross-section and/or other dimension that is greater than that of the first state as the patient grows, said stent frame in the second expanded state defining the internal channel with a second cross-section being larger than the first cross-section; wherein the elongated stent frame further comprises arcuate members at one or more strut junctions, wherein the arcuate members are thinner than the frame strut width for providing axial flexibility for said stent frame.

In some embodiments of the disclosed growth stent of the first aspect, the stent frame in the second expanded state can continue to support the selected lumen. The stent frame in the first expanded state can define the internal channel with a first cross-section. Additionally and/or alternatively, the stent frame in the second expanded state can define the internal channel with a second cross-section being larger than the first cross-section.

the stent frame in the initial state can have a small implantation size for facilitating insertion into a neonate patient. The implantation size is less than <NUM> French and/or the first cross-section can be less than <NUM> millimeters.

In some embodiments of the disclosed growth stent of the first aspect, the stent frame can be expanded to the second expanded state in a child patient. The second cross-section, for example, can be between <NUM> millimeters and <NUM> millimeters, inclusive.

In some embodiments of the disclosed growth stent of the first aspect, the stent frame can be configured to further expand from the second expanded state to a third expanded state as the patient further grows. The stent frame in the third expanded state, for example, can continue to support the selected lumen. The stent frame optionally can be expanded to the third expanded state in an adult patient. The stent frame in the third expanded state can define the internal channel with a third cross-section being larger than the second cross-section. In some embodiments, the third cross-section can be between <NUM> millimeters and <NUM> millimeters, inclusive.

In some embodiments of the disclosed growth stent of the first aspect, the stent frame can include first and second frame members with respective arcuate members each defining a central recess. The arcuate members can comprise cooperating arcuate members. The arcuate members, for example, can converge to form a central channel as the stent frame expands from the initial state to the first expanded state. The central channel can comprise an intersection of the central recess of the arcuate member of the first frame member and the central recess of the arcuate member of the second frame member. Advantageously, the arcuate members can provide flexibility for the stent frame.

In some embodiments of the disclosed growth stent of the first aspect, the stent frame is provided with a tubular shape. Additionally and/or alternatively, the disclosed growth stent of the first aspect can further comprise one or more leaflets extending from the stent frame into the internal channel and providing a valvular function in the first and second expanded states in selected embodiments.

the stent frame includes a predetermined number of frame cells and a plurality of frame struts, a strut junction between selected frame struts having a junction width that is sufficiently small for facilitating insertion of the stent frame in the initial state and that is sufficiently large for supporting expansion of the stent frame to the first and second expanded states while maintaining strength for supporting the selected lumen.

In some embodiments of the disclosed growth stent of the first aspect, the internal channel can extend between opposite end regions of the stent frame, at least one of the end regions being flared radially outwardly for facilitating an engagement between the stent frame and the selected lumen.

In some embodiments of the disclosed growth stent of the first aspect, the internal channel can extend between opposite end regions of the stent frame, at least one of the end regions being flared radially inwardly or being dulled for reducing risk of an aneurism in the selected lumen.

In some embodiments, the disclosed growth stent of the first aspect can further comprise a fluid-impermeable covering being disposed on at least a portion of the stent frame and preventing leaks due to ingrowth of the selected lumen as the patient grows.

In some embodiments of the disclosed growth stent of the first aspect, the stent frame is delivered to the selected lumen via a first catheter delivery system. The stent frame optionally can be subsequently expanded to the second expanded state via the first catheter delivery system and/or subsequently expanded to the second expanded state via a second catheter delivery system.

In accordance with a second aspect disclosed herein, there is set forth a catheter system, wherein the catheter system comprises means for implanting each embodiment of the growth stent of the first aspect.

In accordance with a third aspect disclosed herein, there is set forth a catheter system, wherein the catheter system comprises means for expanding each embodiment of the growth stent of the first aspect. The expanding means, for example, can include first means for expanding the growth stent from the initial state to the first expanded state and/or second means for expanding the growth stent from the first expanded state to the second expanded state.

In accordance with a fourth aspect disclosed herein, there is set forth a growth stent for implantation in a neonate patient that can comprise:.

In some embodiments of the disclosed growth stent of the fourth aspect, the stent frame in the initial state can have an implantation size that is less than <NUM> French, the first cross-section can be less than <NUM> millimeters, the second cross-section can be <NUM> millimeters and/or the third cross-section can be greater than <NUM> millimeters.

It should be noted that the figures are not drawn to scale and that elements of similar structures or functions may be generally represented by like reference numerals for illustrative purposes throughout the figures. It also should be noted that the figures are only intended to facilitate the description of the preferred embodiments. The figures do not illustrate every aspect of the described embodiments and do not limit the scope of the present disclosure.

Since currently-available stents have specific, limited ranges of operation and, when implanted at early development states are unable to grow to adult sizes, an expandable growth stent that can maintain proper strength throughout a predetermined expansion range can prove desirable and provide a basis for a wide range of system applications, such as implantation in neonates and other young patients and subsequent expansion as the patients grow. This result can be achieved, according to selected embodiments disclosed herein, by a growth stent <NUM> as illustrated in <FIG>.

Turning to <FIG>, the growth stent <NUM> is shown as including an elongated stent frame (or body) <NUM> for forming an internal channel <NUM>. The growth stent <NUM> can be implanted within a vessel (or lumen) <NUM> (shown in <FIG>) of a patient to hold open or otherwise reinforce the lumen <NUM>. The stent body <NUM> can be provided in an initial (or unexpanded or crimped) state as shown in <FIG>. In the initial state, the stent body <NUM> can have any predetermined initial size, shape, diameter, cross-section and/or other dimension for facilitating insertion of the growth stent <NUM> into the lumen <NUM>. The initial size, shape, diameter, cross-section and/or other dimension D of the stent body <NUM> can be application dependent.

Upon being positioned at a selected implantation site <NUM> (or other area of interest) (shown in <FIG>) within the lumen <NUM>, the stent body <NUM> can be expanded from the initial state to a first expanded state as shown in <FIG>. In the first expanded state, the stent body <NUM> can have a first predetermined expanded size, shape, diameter, cross-section and/or other dimension D. The stent body <NUM>, when expanded in the first expanded state, can define the internal channel <NUM>. The internal channel <NUM> can have a first predetermined diameter, cross-section and/or other dimension D<NUM> for facilitating an unobstructed (or normal) flow of a bodily fluid, such as blood, bile or other luminal liquids, through the lumen <NUM> via the growth stent <NUM>.

In selected embodiments, the expanded stent body <NUM> can comprise a body wall <NUM> that defines the internal channel <NUM>. The body wall <NUM>, for example, can include an inner surface <NUM> for defining the internal channel <NUM>. The internal channel <NUM> preferably extends from a proximal end region <NUM> of the stent body <NUM> to a distal end region <NUM> of the stent body <NUM> as illustrated in <FIG>. The growth stent <NUM> thereby can enable the bodily fluid to flow, preferably unobstructed, from the proximal end region <NUM> to the distal end region <NUM> via the internal channel <NUM>. Stated somewhat differently, the growth stent <NUM> can be provided in generally tubular shape.

Advantageously, the stent body <NUM> can be further expanded from the first expanded state to a second expanded state as shown in <FIG>. The stent body <NUM> can be expanded to the second expanded state based upon one or more preselected criteria. Exemplary preselected criteria can include, but are not limited to, a preselected duration after implantation of the growth stent <NUM>, a condition of the lumen <NUM> and/or growth (or other change in size or other condition) of the patient. In the second expanded state, the stent body <NUM> can have a second predetermined expanded size, shape, diameter, cross-section and/or other dimension, which is greater than the first predetermined expanded size, shape, diameter, cross-section and/or other dimension of the stent body <NUM>.

The stent body <NUM>, when expanded in the second expanded state, can define the internal channel <NUM> with a second predetermined diameter, cross-section and/or other dimension D<NUM> for maintaining the unobstructed flow of bodily fluid through the lumen <NUM> via the further-expanded growth stent <NUM>. Stated somewhat differently, the stent body <NUM> can be provided with a tubular shape and/or can have relatively wide securing end portions (not shown) at the proximal and distal end regions <NUM>, <NUM> when expanded in the second expanded state. Although shown and described as having two expanded states with reference to <FIG> for purposes of illustration only, the growth stent <NUM> can support any predetermined number of expanded states. The stent body <NUM>, when expanded in a selected expanded state, can define the internal channel <NUM> with a respective predetermined diameter, cross-section and/or other dimension for maintaining the unobstructed flow of bodily fluid through the lumen <NUM> via the growth stent <NUM>. The predetermined number of expanded states and the associated predetermined diameters, cross-sections and/or other dimensions, for example, can be application-dependent.

The growth stent <NUM> advantageously can be expanded to cover the wide range of anatomical diameters necessary to treat narrowed lesions across an entire lifetime of the patient. Stated somewhat differently, the predetermined number of expanded states supported by the growth stent <NUM> can configure the growth stent <NUM> to provide a wide range of anatomical diameters. The growth stent <NUM>, for example, can be crimped on the delivery catheter <NUM> at small enough sizes for a neonatal patient, such as considerably less than an <NUM> French crimped growth stent <NUM>, with an ability to be expanded later to teen and/or adult sizes of greater than <NUM> in diameter.

<FIG> illustrate selected embodiments of a growth stent frame at various cycles throughout a patient's life, as the diameter of a vessel (or lumen) <NUM> (shown in <FIG>) of the patient grows. In this specific example, the growth stent frame <NUM> can maintain strength at the various diameters. Turning to <FIG>, the growth stent <NUM> is shown in the initial state for implantation. The stent body <NUM>, in the initial state, can have a predetermined initial size, shape, diameter, cross-section or other dimension of, for example, <NUM> for facilitating insertion of the growth stent <NUM> into the lumen <NUM>.

When the growth stent <NUM> is in an expanded state, the stent body <NUM> can define the internal channel <NUM> with any suitable predetermined diameter, cross-section or other dimension D. The stent body <NUM>, for example, can define the internal channel <NUM> with a first predetermined diameter, cross-section or other dimension D of <NUM> as shown in <FIG>, a second predetermined diameter, cross-section or other dimension D of <NUM> as shown in <FIG> and/or a third predetermined diameter, cross-section or other dimension D of <NUM> or more as shown in <FIG>, without limitation. The growth stent <NUM> thereby can be provided to hold open a narrow vessel <NUM> (shown in <FIG>) and allow for normal flow of blood or other bodily fluids.

As an example, the growth stent <NUM> can be implanted in a vessel (or lumen) <NUM> (shown in <FIG>) of an infantile patient through expansion to a diameter of less than <NUM> and have proper strength to be expanded over the course of a patient's lifetime to significantly greater than <NUM>. The exemplary growth stent <NUM> can be tracked through the vessel <NUM> of the infantile patient via a delivery catheter <NUM> of a catheter delivery system <NUM> (collectively shown in <FIG>) that is considerably less than <NUM> French in diameter and, in some embodiments, less than <NUM> French in diameter and beyond.

When provided with the tubular shape, the channel <NUM> formed by the stent body <NUM> can comprise an open channel in the manner illustrated in <FIG>. The growth stent <NUM> optionally can support a valvular function. In selected embodiments, for example, the growth stent <NUM> can include one or more leaflets <NUM> as shown in <FIG>. The leaflets <NUM> can be attached to the inner surface <NUM> of the body wall <NUM> and extend into the channel <NUM> formed by the stent body <NUM>. The leaflets <NUM> thereby can provide the valvular function via the growth stent <NUM>.

An alternative embodiment of the growth stent <NUM> is shown in <FIG>. Turning to <FIG>, the growth stent <NUM> is shown as including an elongated stent frame (or body) <NUM> for forming an internal channel <NUM>. In the manner discussed in additional detail with reference to <FIG>, the growth stent <NUM> can be implanted within a vessel (or lumen) <NUM> (shown in <FIG>) of a patient to hold open or otherwise reinforce the lumen <NUM>. The stent body <NUM> can be provided in an initial (or unexpanded or crimped) state as shown in <FIG>. In the initial state, the stent body <NUM> can have any predetermined initial size, shape, diameter, cross-section and/or other dimension for facilitating insertion of the growth stent <NUM> into the lumen <NUM>. The initial size, shape, diameter, cross-section and/or other dimension D of the stent body <NUM> can be application dependent.

Upon being positioned at a selected implantation site <NUM> (or other area of interest) (shown in <FIG>) within the lumen <NUM>, the stent body <NUM> can be expanded from the initial state to a first expanded state as shown in <FIG>. In the first expanded state, the stent body <NUM> can have a first predetermined expanded size, shape, diameter, cross-section and/or other dimension D. The stent body <NUM>, when expanded in the first expanded state, can define the internal channel <NUM>. The internal channel <NUM> can have a first predetermined diameter, cross-section and/or other dimension D for facilitating an unobstructed (or normal) flow of a bodily fluid, such as blood, bile or other luminal liquids, through the lumen <NUM> via the growth stent <NUM>.

In selected embodiments, the expanded stent body <NUM> can comprise a body wall <NUM> that defines the internal channel <NUM> that preferably extends from a proximal end region <NUM> of the stent body <NUM> to a distal end region <NUM> ofthe stent body <NUM> as illustrated in <FIG>. The growth stent <NUM> thereby can enable the bodily fluid to flow, preferably unobstructed, from the proximal end region <NUM> to the distal end region <NUM> via the internal channel <NUM>. Stated somewhat differently, the growth stent <NUM> can be provided in generally tubular shape and/or can support a valvular function in the manner discussed herein with reference to <FIG>.

As shown in <FIG>, one or more selectedjunctions <NUM> ofthe stent body o(r frame) <NUM> are formed from frame members that include respective arcuate members, such as arcuate members <NUM>, <NUM>. The arcuate members <NUM>, <NUM> each can define a central recess <NUM>. The growth stent <NUM> can expand in the manner discussed herein such that the diameter, cross-section and/or other dimension D ofthe internal channel <NUM> can increase from a smaller dimension DA as shown in <FIG> to a larger dimension DB as shown in <FIG> in the manner discussed herein. The expansion ofthe growth stent <NUM> can comprise expansion between any two predetermined states. For example, the expansion ofthe growth stent <NUM> can comprise expansion from the initial state illustrated in Fig. SA to the first expanded state illustrated in Fig. SB, expansion from the first expanded state illustrated in Fig. SB to the second expanded state illustrated in Fig. SC and/or expansion from the second expanded state illustrated in Fig. SC to the third expanded state illustrated in Fig. SD, or any other expansion of the growth stent <NUM> without limitation.

As the growth stent <NUM> expands, the arcuate members <NUM>, <NUM> can converge. The arcuate members <NUM>, <NUM> thereby can cooperate such that the central recess <NUM> ofthe arcuate member <NUM> can cooperate with the central recess <NUM> ofthe arcuate member <NUM>. The arcuate members <NUM>, <NUM>, in other words, can comprise cooperating arcuate members. The cooperating arcuate members <NUM>, <NUM> thereby can define a central channel <NUM>. The central channel <NUM> can be formed between the cooperating arcuate members <NUM>, <NUM> and comprise an intersection of the central recess <NUM> of the arcuate member <NUM> and the central recess <NUM> of the arcuate member <NUM>.

The arcuate members <NUM>, <NUM> advantageously provide axial flexibility for the growth stent frame <NUM> by being thinner than the strut width <NUM> of the rest of the growth stent <NUM>. In some embodiments, the arcuate members <NUM>, <NUM> can utilize a "c-like" shape to allow deformation that is opposite of the usual column strength provided by the growth stent frame <NUM>. The arcuate members <NUM>, <NUM> can provide a lever point in the structure of the frame <NUM>, potentially allowing for a bend in the frame <NUM> when tracking to a target location or potentially after deployment, depending on the configuration needed for either. The bend can occur by the "c-like" shape deforming to collapse upon itself and/or to open to be more of a straight line, depending on the direction of deformation.

In the manner discussed in more detail above with reference to <FIG> and <FIG>, the growth stent <NUM> of <FIG> advantageously can be expanded to cover the wide range of anatomical diameters necessary to treat narrowed lesions across an entire lifetime of the patient. Stated somewhat differently, the predetermined number of expanded states supported by the growth stent <NUM> can configure the growth stent <NUM> to provide a wide range of anatomical diameters. The growth stent <NUM>, for example, can be crimped on the delivery catheter <NUM> at small enough sizes for a neonatal patient, such as considerably less than an <NUM> French crimped growth stent <NUM>, with an ability to be expanded later to teen and/or adult sizes of greater than <NUM> in diameter.

<FIG> illustrate selected embodiments of a growth stent frame at various cycles throughout a patient's life, as the diameter of a vessel (or lumen) <NUM> (shown in <FIG>) of the patient grows. In this specific example, the growth stent frame <NUM> can maintain strength at the various diameters. Turning to Fig. SA, the growth stent <NUM> is shown in the initial state for implantation. The stent body <NUM>, in the initial state, can have a predetermined initial size, shape, diameter, cross-section or other dimension of, for example, <NUM> for facilitating insertion of the growth stent <NUM> into the lumen <NUM>.

Turning to <FIG>, growth stent geometry, including frame strut width <NUM>, frame thickness <NUM>, number of cells <NUM>, and/or cell angulation <NUM>, can contribute to the ability to maintain strength over the wide range of deployments and expansions. Frame strut width <NUM> and frame thickness <NUM> can be employed to determine the radial force of the growth stent frame <NUM> with the number of cells <NUM> magnifying the impact of these characteristics. In one embodiment, the growth stent frame <NUM> can be optimized to lessen the impact of foreshortening of the growth stent <NUM>. Foreshortening is the length shortening that can occur as the growth stent <NUM> is expanded from the crimped state into the selected expanded state. The cell angulation <NUM> and length of the growth stent cells <NUM> can be optimized to lessen the amount of growth stent foreshortening in order to more predictably deploy the growth stent <NUM> through expansion, such as balloon expansion.

The width of the strut junctions can contribute to an ability of the growth stent <NUM> to be crimped small enough to track through infantile blood vessels <NUM>. Keeping the strut junction width <NUM> small to allow for the number of cells <NUM> in the growth stent <NUM> to be crimped smaller can help facilitate delivery. The junction width <NUM> preferably is large enough to expand over a large range for later expansion without significant frame stress and strain, leading to a small range in order to optimize the growth stent junction width <NUM> for this purpose. Growth stent frame material can enable these properties, allowing for strength across the wide range of operation despite the thin-walled nature of the growth stent <NUM> to allow the growth stent <NUM> to be crimped to small enough sizes to be delivered into neonatal patients.

The growth stent frame <NUM> may be optimized to allow for a thicker wall thickness <NUM> from the initial tubing utilized for the metal structure. Limiting junction width <NUM> to a minimum with relation to the strut width <NUM> can allow for an increase in wall thickness <NUM> of the frame <NUM>, which can prevent the growth stent <NUM> from having a spring-like reaction when radial force is applied. Therefore, the crush resistance of the frame <NUM> can be increased, lessening the effect of recoil from the vessel <NUM>, increasing the radial force of the growth stent <NUM> across all diameters necessary for expansion and providing a rigid structure to hold the vessel <NUM> open.

Because of the strength needed for this patient population and a desire for the frame to be crimped to exceedingly small diameters, specific formulas exist for calculating strut width <NUM>, wall thickness <NUM>, junction size, and number of cells <NUM> that create an optimized version that allows for re-expansion over the large range of use for the growth stent <NUM>. One exemplary formula for optimizing the growth stent <NUM> is set forth in Equation <NUM>. According to Equation <NUM>, the smallest crimp diameter of the growth stent <NUM> can be represented as: <MAT> wherein SW represents a strut width <NUM>, J represents a junction width <NUM>, N represents a number of cells <NUM>, and ST represents a strut thickness from the wall thickness <NUM> of the initial tubing. Equation <NUM> allows for certain parameters to be set based upon the recoil strength necessary to maintain proper strength across the desired range of use, by increasing the strut thickness <NUM> and maintaining the ability to be crimped to desired small diameters. By minimizing the junction as only slightly larger than the strut width <NUM> of the growth stent <NUM>, the smallest crimp diameter may be calculated as a function of strut width <NUM> and junction width <NUM> multiplied by the number of cells <NUM> in accordance with Equation <NUM>.

In some embodiments of the growth stent <NUM>, a thickness <NUM> of the body (or frame) wall <NUM> can be minimized to prevent thrombus and/or stenosis of the vessel <NUM>. Increasing the thickness <NUM> of the frame wall <NUM> can lessen the diameter of the vessel <NUM> after expansion as the frame wall <NUM> can provide blockage of the vessel <NUM>. Additionally and/or alternatively, an increase in the thickness <NUM> of the frame wall <NUM> can provide more material for thrombus attachment. More material in the stent frame <NUM> can allow for more endothelization, allowing for cells <NUM> to attach to the foreign body.

In an optimized embodiment of the growth stent <NUM>, the factors of strength and thickness <NUM> can be calculated to produce the best results for a growing patient. Utilizing vessel strength research, the growth stent frame may be optimized to allow for adequate strength across the varied range of operation utilizing one of more of the above factors. The growth stent <NUM> may have specific parameter ranges that are unique to this application, differentiating it from conventional stent frames. When attaching a resulting stent radial force and crush force as an output, for example, Equation <NUM> may be optimized for strength, allowing for an optimized stent frame <NUM> for growth over a specific range.

Equation <NUM> assumes that a measured length of the growth stent frame strut is constant and determined because changing the strut length can impact the output strength. In one optimized embodiment of the growth stent <NUM>, the strut length can be determined to ensure that the stent frame <NUM> does not experience high levels of stress and strain that may lead to frame complications such as deformation and/or fracture. Increasing the length of the strut itself can increase the diameter of expansion but can decrease the resulting radial force. Therefore, an optimized embodiment of the growth stent <NUM> may contain the smallest strut length that allows for the stress and strain on the stent frame <NUM> to be acceptable across the intended diameter range of the growth stent <NUM>.

Once the smallest strut length for the growth stent <NUM> is determined, Equation <NUM> may be utilized to optimize the frame <NUM>. While two or more factors, or, in some cases, all factors may be changed in concert, certain parameter changes can show a pattern with regard to output radial strength of the frame <NUM>, allowing for varied embodiments of the same stent structure to serve the purpose of a growth stent <NUM>. In some embodiments of the growth stent <NUM>, these parameters can be optimized for a small enough minimum crimp to not cause harm to vessels <NUM> of neonatal patients while providing adequate strength at large adult vessel sizes unlike commercially-available stents that are optimized for very specific adult-size diameter ranges.

The growth stent <NUM> preferably possesses adequate radial strength to keep the vessel <NUM> open at a specified diameter, such as by using the stent expansion system <NUM> (shown in <FIG>), such as a balloon, to expand the growth stent <NUM> to the specific diameter and the growth stent frame <NUM> containing enough radial strength to maintain the specific diameter without support from the balloon. However, radial strength and other properties of the growth stent <NUM> may affect the fatigue potential of the growth stent frame <NUM>. Fatigue can result from continuous and repetitive motion creating stress and strain on the frame <NUM>.

In some embodiments, one or more of the properties of the stent frame <NUM> can be optimized to ensure that unacceptable fatigue does not occur over the lifetime of the growth stent <NUM>. This can be done in a variety of ways. Exemplary manners for avoiding unacceptable fatigue can include increasing the radial strength of the growth stent <NUM> to limit cyclical compression and expansion in the vessel <NUM> and/or increasing the length of the struts themselves to create more relaxed cell structures that are less susceptible to fatigue. The level of ductility in the metal or other material chosen for the stent frame <NUM> may also factor into the level of strain. Excess fatigue and strain on the growth stent frame <NUM> may lead to deformation and/or potential fracture of the metal or other material forming the growth stent <NUM>.

In some embodiments of the growth stent <NUM>, the frame <NUM> can be cut from a tube using a laser cutting machine (not shown). The laser cutting machine can finely cut through the wall thickness <NUM> of the tubing to create the cell structure. After cutting, the unwanted material can be stripped and/or removed from between the cell struts that have been cut. In many cases, the laser cutting machine can leave rough edges on the growth stent frame <NUM> and/or the metal frame, which preferably are sanded on the inner diameter to ensure no burrs remain.

Additionally and/or alternatively, some embodiments of the growth stent frame <NUM> can be electropolished to remove the outer layer of metal on the frame <NUM>, smoothing the edges and finishing the frame <NUM> for implantation. Electropolishing in many instances uses electrical current through a liquid bath to evenly distribute the removal of material from the outer layers of the metal on the frame <NUM>, often leaving the growth stent <NUM> with the appearance of shine from the polish. Some embodiments, such as frames utilizing NITINOL or other shape-changing materials, may be shape-set to desired shapes using heat and quenching.

The diameter of the tubing utilized as the base of the stent frame <NUM> may affect the strength of the frame <NUM>. Larger diameter tubes are less trapezoidal if the wall thickness <NUM> of the tubing is maintained. While the stent frame <NUM> may be adjusted to be cut at any diameter of tube as long as the wall thickness <NUM> remains accurate, trapezoidal struts that occur from smaller tubes may lead to less radial strength over the desired range as the strut is made with less material. In an optimized version of the growth stent <NUM>, the frame <NUM> can be cut from a specific tubing thickness <NUM> and/or diameter to ensure proper strength across the entire range of use.

In selected embodiments, the growth stent <NUM> may include a bare metal frame <NUM> and/or have a blood-impermeable covering on a segment of the frame <NUM>. The blood-impermeable covering allows for vessel ingrowth and seals the vessel <NUM> from blood leaking through the growth stent <NUM>. The covering may be of cloth material such as polyethylene terephthalate (PET) and/or a fluoropolymer, such as some polytetrafluoroethylenes. The covering seals and performs across the range of diameters of the growth stent frame <NUM> and is able to be expanded with the frame <NUM> over the lifetime of patient growth. In one embodiment, the blood-impermeable covering can be attached to each diamond-shaped cell of the growth stent <NUM>, form-fitting to each cell. The cloth in this embodiment may be sewed or tacked onto the frame <NUM> using a suture or other suitable tacking method.

In one exemplary embodiment, the blood-impermeable covering can be attached at the distal and proximal ends <NUM>, <NUM> (shown in <FIG>) of the growth stent frame <NUM> and/or at one or more other predetermined locations along the growth stent frame <NUM> to allow for proper expansion. The covering may be attached in any suitable manner, such as through sewing and/or tacking in the manner set forth herein and/or through selective welds to ensure fixture to the frame <NUM>. Additionally and/or alternatively, the growth stent frame <NUM> may be dipped in a polymer that forms a flexible webbing between the cells <NUM> of the frame <NUM> to provide a blood-impermeable covering. In this embodiment, the frame <NUM> can be dipped in a liquid polymer and slowly removed, allowing the polymer to dry and create the flexible covering after removal. The polymer may be cured in air and/or in an oven for desired material properties.

One or both end regions <NUM>, <NUM> of the growth stent <NUM> may be flared outwardly relative to a longitudinal axis of the growth stent <NUM> in some embodiments. The flared end regions <NUM>, <NUM> advantageously can help secure the growth stent <NUM> into place in the wall of the artery or other lumen. The flare may be implemented in any suitable manner. For example, the flare may be implemented by outwardly curving the tips of a selected end region <NUM>, <NUM> using material properties and/or shape-setting. Another embodiment can use expansion from a balloon or other expandable member (not shown) with an outward curve shape. Additionally and/or alternatively, one or both end regions <NUM>, <NUM> may be flared inwardly to prevent aneurysm using similar techniques.

Aneurysms may be similarly prevented through dulling one or both end regions <NUM>, <NUM> of the growth stent <NUM>. Dulled end regions <NUM>, <NUM> may be created in the growth stent <NUM>, in some embodiments, by attaching circular eyelets and/or ends of various sizes to lessen the sharpness of the growth stent frame <NUM>. For example, the end regions <NUM>, <NUM> may be circular, hooked, or have any other non-invasive shape. Another embodiment of the growth stent <NUM> can use features on the growth stent <NUM> to engage with the anatomy and keep the growth stent <NUM> in place. In this embodiment, the growth stent <NUM> can contain sharper edges cut into the growth stent frame <NUM> and/or may utilize a type of barb for fixturing, whether through the growth stent frame <NUM> or the addition of suture knots to provide fixation in the vessel <NUM>.

In another embodiment of the stent frame <NUM>, one or both of the end regions <NUM>, <NUM> may have material removed with relation to the rest of the stent frame <NUM>. The material can be removed, for example, from the strut width <NUM> of the stent frame <NUM>, from the strut thickness <NUM> of the growth stent <NUM> or from both.

Removing the material allows for the thinned end regions <NUM>, <NUM> of the growth stent <NUM> to be more flexible than the thicker stent body <NUM>, allowing for less blood vessel penetration and a potential to be less invasive in the patient's body. Flexibility may be utilized in this embodiment of the frame <NUM> to prevent aneurysms and vessel irritation. If the embodiment of the growth stent <NUM> is balloon dilatable, for example, the thinned end regions <NUM>, <NUM> can cause less resistance to the balloon and may be utilized as tool to prevent movement of the growth stent <NUM> during deployment utilizing the balloon.

The end regions <NUM>, <NUM> of the growth stent <NUM> can engage into the surrounding vessel <NUM> or other anatomy in the narrowed lesion using radial force. Flares at the end regions <NUM>, <NUM> advantageously can be applied for securing the growth stent <NUM> to the surrounding anatomy. The flares serve as a stop, which can secure the growth stent <NUM> in place. When an axial force is applied to the growth stent <NUM>, the flares can push into the surrounding anatomy to resist migration of the growth stent <NUM>.

The flares and growth stent expansion may be done naturally through expanding properties of the growth stent <NUM>, such as material choice, and/or manually through the use of a pressured balloon or other stent expansion system <NUM> to expand the frame <NUM> to a larger diameter than the vessel <NUM>, stretching the walls of the vessel <NUM> and anchoring the growth stent <NUM> within the vessel <NUM> using radial strength. As the patient grows, the diameter of the growth stent <NUM> can increase through material properties and self-expansion and/or through a later balloon dilation to increase the diameter and ensure the growth stent <NUM> maintains fixation through over-expansion and resulting radial force of the frame <NUM>.

The growth stent <NUM> may be made of one or more of a variety of conventional materials for balloon-expanding stents or, in alternative embodiments, for self-expandable growth stents. As non-limiting examples, the growth stent <NUM> may be made of any appropriate material, such as a metal or metal alloy, including stainless steel, cobalt chromium, NITINOL, or Elgiloy, or a polymer, for example. For self-expanding embodiments, the growth stent <NUM> can be made of a shape memory material such as, for example, NITINOL.

The growth stent <NUM> advantageously can be configured for delivery into narrowed vessels <NUM> with an ability to be expanded to a selected expanded state, such as an adult size, and maintain adequate strength for vessel openings over the entire range of necessary expansion. In selected embodiments, a transvascular technique can be used to introduce and implant the growth stent <NUM> in neonates and other young patients using a catheter delivery system <NUM> as shown in <FIG>. Turning to <FIG>, the exemplary catheter delivery system <NUM> can comprise a flexible delivery catheter <NUM> and advantageously can introduce and implant the growth stent <NUM> in a manner that is less invasive than open heart surgery. The delivery catheter <NUM> can be trackable to a heart (or other implantation site <NUM> (shown in <FIG>)) and surrounding vasculature through a vessel <NUM> in the groin or another connecting vessel <NUM>.

An end portion <NUM> of the delivery catheter <NUM> is shown as including an inner shaft <NUM> and an outer shaft <NUM>. One or more of the shafts <NUM>, <NUM> can be made of a flexible plastic, such as Pebax or other Nylons and contain open lumens. The delivery catheter <NUM> preferably comprises a flexible catheter. The flexibility can allow for proper pushability through human vascular to allow the growth stent <NUM> to be delivered to a proper location. The plastics used for the delivery catheter <NUM> can be biocompatible as to not cause harm to the patient.

In selected embodiments, the growth stent <NUM> can be mounted in the initial (or crimped) state on the end portion <NUM> of the delivery catheter <NUM>. In other words, the growth stent <NUM> in the initial state can receive the inner shaft <NUM> via the internal channel <NUM> (shown in <FIG>). The growth stent <NUM> thereby can be disposed between the inner shaft <NUM> and the outer shaft <NUM> of the delivery catheter <NUM>. The end portion <NUM> of the delivery catheter <NUM> likewise can include an optional stent expansion system <NUM>, such as a balloon, for expanding the growth stent <NUM> from the initial state to a predetermined expanded state. In selected embodiments, the stent expansion system <NUM> can be at least partially disposed within the internal channel <NUM> to facilitate subsequent expansion of the growth stent <NUM>.

Once the growth stent <NUM> is properly positioned on the end portion <NUM> of the delivery catheter <NUM>, the catheter delivery system <NUM> can be provided in a closed configuration as illustrated in <FIG>. Stated somewhat differently, the catheter delivery system <NUM> can transition from an open configuration of <FIG> to the closed configuration of <FIG>. Turning to <FIG>, the outer shaft <NUM> of the delivery catheter <NUM> is shown as being moved distally toward an optional nosecone <NUM> of the delivery catheter <NUM>. Stated somewhat differently, the growth stent <NUM> can be disposed between the inner shaft <NUM> and the outer shaft <NUM> when the delivery catheter <NUM> is in the closed configuration. The outer shaft <NUM> thereby can provide a protective shell for the growth stent <NUM> for introduction and advancement through a vessel (or lumen) <NUM> of a patient.

During implantation, the delivery catheter <NUM> of the catheter delivery system <NUM> can track through the vasculature with the growth stent <NUM> and stent expansion system <NUM> covered by the outer shaft <NUM>. The delivery catheter <NUM> thereby can be advanced through the vessel (or lumen) <NUM> of a patient until the end portion <NUM> reaches an implantation site <NUM>, such as a narrowed lesion or other diseased area, as illustrated in <FIG>. Upon becoming disposed adjacent to the implantation site <NUM>, the catheter delivery system <NUM> can be provided in an open configuration as illustrated in <FIG>. Stated somewhat differently, the catheter delivery system <NUM> can transition from the closed configuration of <FIG> to the open configuration of <FIG>.

In the open configuration, the outer shaft <NUM> of the delivery catheter <NUM> can be disposed proximally or away from the nosecone <NUM>. The delivery catheter <NUM> thereby can expose the growth stent <NUM> to the implantation site <NUM>. With the growth stent <NUM> adjacent to the implantation site <NUM>, the stent expansion system <NUM> can be activated to expand the growth stent <NUM> from the initial (or unexpanded or crimped) state as shown in <FIG> to the first expanded state of <FIG>. In selected embodiments, the stent expansion system <NUM> can include a balloon that can be inflated to expand the growth stent <NUM>.

Additionally and/or alternatively, the growth stent <NUM> optionally can be expanded by expanding a distal portion of the growth stent <NUM> while a proximal portion of the growth stent <NUM> is anchored to the delivery catheter <NUM> without use of the stent expansion system <NUM>. Once the distal portion of the growth stent <NUM> is expanded, the proximal portion of the growth stent <NUM> can be disengaged from the delivery catheter <NUM> and expanded into the lumen <NUM>. The proximal portion of the growth stent <NUM>, for example, may be expanded all at once or in stages.

In the first expanded state, the growth stent <NUM> can have a first predetermined expanded size, shape, diameter, cross-section and/or other dimension in the manner set forth in more detail above with reference to <FIG>. The stent expansion system <NUM> can be deactivated, retracting to an initial size. If the stent expansion system <NUM> includes the balloon, the balloon can be deflated. The delivery catheter <NUM> then can be withdrawn from the lumen <NUM> once the growth stent <NUM> in the first expanded state is successfully deployed at the implantation site <NUM> as shown in <FIG>.

The growth stent <NUM> thereby can be implanted with its functional size at the implantation site <NUM>. As needed, the growth stent <NUM> can be further expanded to a larger size, such as a teen size and/or adult size, a later date. In a manner similar to the implantation, for example, another delivery catheter <NUM> can track through the vasculature of the patient and be advanced through the vessel <NUM> until the end portion <NUM> reaches the growth stent <NUM> at the implantation site <NUM>. A stent expansion system <NUM> of the delivery catheter <NUM> can be disposed within the internal channel <NUM> (shown in <FIG>) of the growth stent <NUM> and activated to expand the growth stent <NUM> from the first expanded state of <FIG> to a second expanded state of <FIG>.

In the second expanded state, the growth stent <NUM> can have a second predetermined expanded size, shape, diameter, cross-section and/or other dimension, which is greater than the first predetermined expanded size, shape, diameter, cross-section and/or other dimension of the growth stent <NUM> in the first expanded state, in the manner set forth in more detail above with reference to <FIG>. The stent expansion system <NUM> can be retracted, and the delivery catheter <NUM> can be withdrawn from the lumen <NUM> once the growth stent <NUM> in the second expanded state is successfully deployed at the implantation site <NUM> in the manner set forth above with reference to <FIG>.

The growth stent <NUM> advantageously can be implanted in a neonate patient and expanded as needed throughout the lifetime of the patient. Once delivered and implanted at a certain diameter, the growth stent <NUM> can be expanded to a larger size at a later time. This applies in the case that the vessels initially receiving one embodiment of the growth stent <NUM> are continuing to grow, such as throughout the growth of the patient from infancy to adolescence and adulthood. Because the growth stent <NUM> can have proper strength over all applicable ranges of growth, a separate balloon or other stent expansion system <NUM> at a later point in the growth cycle of the patient can be tracked to the growth stent <NUM> at the implantation site <NUM>. This further expansion of the growth stent <NUM> can occur as necessary for the growth of an individual patient.

In selected embodiments, the delivery catheter <NUM> can comprise a balloon catheter with a balloon <NUM> for expanding the growth stent <NUM>. The balloon catheter can introduce and deploy the growth stent <NUM> in a manner analogous to the manner by the delivery catheter <NUM> is described as introducing and deploying the growth stent <NUM> with reference to <FIG>. Turning to <FIG>, for example, an exemplary method <NUM> for implanting the growth stent <NUM> (shown in <FIG>) via a balloon catheter system is shown. The method <NUM> includes delivering the growth stent <NUM> to the implantation site <NUM> of the vessel (or lumen) <NUM> of a patient (collectively shown in <FIG>), at <NUM>. The balloon catheter can be advanced through the vessel (or lumen) <NUM> of a patient until reaching the implantation site <NUM>.

Upon becoming disposed adjacent to the implantation site <NUM>, the balloon catheter can be provided in an open configuration, or unsheathed, at <NUM>, exposing the growth stent <NUM> to the implantation site <NUM>. Stated somewhat differently, the catheter delivery system <NUM> can transition from the closed configuration of <FIG> to the open configuration of <FIG>. The balloon <NUM> can be filled with fluid and thereby expand in size, at <NUM>. Being disposed in the internal channel <NUM> (shown in <FIG>) of the growth stent <NUM>, the expanding balloon <NUM> can expand the growth stent <NUM> from the initial (or unexpanded or crimped) state as shown in <FIG> to the first expanded state of <FIG>.

The growth stent <NUM> in the first expanded state thus can engage, and/or become embedded into, a wall of the vessel <NUM> at the implantation site <NUM>, at <NUM>. The balloon <NUM> then can be re-compressed and removed from the patient's body, leaving the growth stent <NUM> engaged with the vessel <NUM>. In other words, the growth stent <NUM> can be introduced in the initial state and, once expanded by the balloon <NUM>, can hold the vessel <NUM> open without the support of the balloon <NUM> after the balloon dilation. The growth stent <NUM> in the first expanded state thereby can be successfully deployed at the implantation site <NUM>.

Additionally and/or alternatively, the balloon catheter can include the optional nosecone <NUM> (shown in <FIG>). The nosecone <NUM> can aid with transitions and trackability through the vessel <NUM> and serve as a containing end region for the balloon <NUM> itself. The nosecone <NUM> can be designed using similar plastics as the shafts <NUM>, <NUM>, often with a triangular shape to aid with transitions and tracking through vessels <NUM>. The balloon <NUM> advantageously can be designed with a thin plastic wall that is able to be compressed to fit inside of the delivery catheter <NUM> and ensure the profile is small enough to be inserted in the desired patient's vasculature. The balloon <NUM> can be attached to the inner plastic shaft <NUM> and sealed on the distal end. The inner lumen of the plastic shaft <NUM> can channel inserted fluid, such as saline, from the proximal end of the shaft to the balloon <NUM>. As the balloon <NUM> fills with liquid, the balloon <NUM> can expand to the designed diameter.

When the growth stent <NUM> is crimped onto the balloon <NUM>, the balloon <NUM> may be compressed to small diameters and without built in shoulders to hold the growth stent <NUM> in place. When retracting an outer shaft <NUM> to expose the growth stent <NUM> on the balloon <NUM>, the balloon <NUM> may not have enough resistance to maintain the positioning of the growth stent <NUM> on the balloon <NUM>. In certain embodiments, retracting the outer shaft <NUM> to expose the growth stent <NUM> may cause the outer shaft <NUM> to latch onto the growth stent <NUM> and pull the growth stent <NUM> off of the balloon <NUM>.

In some embodiments of the balloon catheter, this issue may be mitigated through the use of a separate catheter (not shown) disposed between the balloon shaft and the outer shaft <NUM>. This middle catheter may be utilized as a back stop for the growth stent <NUM> during outer shaft retraction. In this embodiment, the outer shaft <NUM> can be retracted over the growth stent <NUM> and the middle catheter as the middle catheter is fixed in relation to the balloon catheter, keeping the growth stent <NUM> in place during exposition. After the growth stent <NUM> and middle catheter are exposed, the middle catheter may then be retracted from over the balloon <NUM> to allow for expansion. This ensures that the growth stent <NUM> remains crimped in the proper position for balloon expansion at the target location <NUM> in the body of the patient.

In another alternative embodiment of the balloon catheter, instead of a back stop for the growth stent <NUM>, the middle catheter can overlaps with the growth stent <NUM>, creating a sock-like attachment to hold the growth stent <NUM> in place. This thin sock-like catheter can maintain stent positioning during outer shaft <NUM> retraction and allow for proper balloon <NUM> inflation. In some embodiments this sock-like catheter can be retracted before balloon <NUM> expansion if it overlaps with the growth stent <NUM>. In other alternative embodiments, the sock-like catheter may only overlap the balloon <NUM> and may be expanded with the balloon <NUM> and removed with the balloon catheter.

In embodiments of the catheter delivery system <NUM> that contain the growth stent <NUM> crimped onto the balloon <NUM>, the growth stent <NUM> can expand with the balloon <NUM> because of the radial pressure from the filled liquid. As liquid is removed from the balloon <NUM>, back pressure can bring the balloon <NUM> back to its original compressed state, leaving the expanded growth stent <NUM> separated from the balloon <NUM> and the balloon catheter. In one embodiment, the balloon catheter may have a handle on the proximal ends of the shafts <NUM>, <NUM> to connect the shafts <NUM>, <NUM>, seal the lumens to prevent blood leak and/or provide an ergonomic grip for an operator. The handle can be made of a hard plastic, soft silicone, and/or other solid materials. The embodiment may also contain an inner-most lumen to track over a guidewire (not shown) in the vasculature. The guidewire can provide a tracking rail to ensure the balloon catheter reaches the target location <NUM> and can be inserted into a lumen on the delivery system.

In selected embodiments, the delivery catheter <NUM> is advanced to the target location <NUM> by way of a femoral vein or artery, depending on the endpoint. Other vessels <NUM> in the patient may be utilized to properly track the delivery catheter <NUM> to the target location <NUM>. The transitions in the material of the delivery catheter <NUM> allow proper trackability to the target location <NUM> despite difficult anatomy.

Additionally and/or alternatively, the catheter delivery system <NUM> can optionally flush air out of the delivery catheter <NUM> before the delivery catheter <NUM> is introduced into the body of the patient to prevent the addition of air molecules into the bloodstream that may cause embolization and other issues in the vessel <NUM>. Flushing air out of a delivery catheter <NUM> may include, for example, flushing air out of the delivery catheter <NUM> with pressurized fluid. The catheter delivery system <NUM> can include the delivery catheter <NUM> and one or more inner lumens (not shown) at least partially disposed within the delivery catheter <NUM>. The inner lumens can define at least one opening for a guidewire (not shown) and at least one opening connected to a balloon. Fluid can introduced into the inner lumens in the opening for a guidewire with at least some of the introduced fluid exiting the inner lumens through a distal opening to remove the air from the delivery catheter <NUM>.

The sizing of the delivered growth stent <NUM> can allow the growth stent <NUM> to be safer for neonates and other younger patients. The growth stent <NUM>, in one embodiment, can be delivered at an outer diameter of less than <NUM> millimeters when in a crimped state, while allowing for later expansion to over <NUM> millimeters in outer diameter in a fully expanded state.

The forgoing primarily describes embodiments of the growth stent <NUM> that are balloon-expandable for purposes of illustration only, not for purposes of limitation. It will be appreciated, however, that the catheter delivery system <NUM> shown and described herein can be readily modified for delivery of self-expandable growth stents, prosthetic heart valves and/or other medical devices. In other words, delivering self-expandable growth stents to an implantation location can be performed percutaneously using modified versions of the delivery devices of the present disclosure. In general terms, an exemplary modified version of the delivery devices can include a transcatheter assembly (not shown) with a delivery sheath and/or additional sheaths as described above. The devices generally further include a delivery catheter, a balloon catheter, and/or a guide wire.

Current market growth stents are unable to cover the total range necessary for the lifetime of the lesion in the patient, specifically a pediatric patient with congenital or anatomical disease. In this case, the growth stent may start small enough to be delivered safely into a neonate but is unable to grow to the adult size. Conversely, a growth stent that expands to large enough for the adult lesion cannot be crimped small enough to be safely implanted in a neonate on a catheter, as neonatal vessels are considerable smaller than an adult vessel.

Varied congenital disease states can be defined as narrowed lesions, such as Tetralogy of Fallot, Aortic Coarctation, various atresia, and various stenosis.

A further understanding of the nature and advantages of the growth stent <NUM> will become apparent by reference to the remaining portions of the specification and drawings. Variations and the optional features noted above may be added to embodiments of the growth stent <NUM>, either alone or in various combinations, as appropriate. Specific numerical values for sizes, shapes, diameters, cross-sections or other dimensions are set forth herein for purposes of illustration only and not for purposes of limitation.

Claim 1:
A catheter insertable and re-expandable growth stent for implantation in a neonate patient, comprising:
an elongated stent frame with a plurality of frame struts (<NUM>) each having a predetermined frame strut width (<NUM>) and a predetermined strut thickness (<NUM>) and extending continuously from a proximal end region (<NUM>) of said stent frame to a distal end region (<NUM>) of said stent frame, adjacent frame struts defining a predetermined number of intermediate frame cells and intersecting to form respective strut junctions (<NUM>) with junction widths (<NUM>) by which said elongated stent frame expands via a delivery catheter (<NUM>) from an initial state with a diameter that is less than eight French (<NUM>) for facilitating insertion via the delivery catheter into a selected lumen of the neonate patient to a first expanded state that has a first predetermined expanded size, shape, diameter, cross-section and/or other dimension that is greater than that of the initial state at implantation, said stent frame in the first expanded state defining an internal channel (<NUM>) with a first cross-section,
wherein the strut junctions (<NUM>) further enable said stent frame to be re-expanded via subsequent introduction of a dilation catheter from the first expanded state to a second expanded state that has a second predetermined expanded size, shape, diameter, cross-section and/or other dimension that is greater than that of the first state as the patient grows, said stent frame in the second expanded state defining the internal channel with a second cross-section being larger than the first cross-section;
wherein the elongated stent frame further comprises arcuate members (<NUM>, <NUM>) at one or more strut junctions (<NUM>), wherein the arcuate members (<NUM>, <NUM>) are thinner than the frame strut width for providing axial flexibility for said stent frame.