Personalized coronary artery stents

Abstract

Techniques for producing personalized coronary stents are provided. [Solution] A method includes generating a 3D model of a non-stenotic shape of a blood vessel in response to a 3D model of the actual shape of the blood vessel, establishing a parametric description of a stent that is expanded from a collapsed configuration to a final configuration that is apposed to the non-stenotic shape, creating a design for the stent by changing parameters of the parametric description in response to a heuristic design that includes a risk of stent struts breaking during plastic deformation between the collapsed configuration and the final configuration, implementing the stent according to the design for the stent, inserting the stent into the blood vessel in its collapsed configuration, manipulating the stent through the blood vessel to the stenosis, and expanding the stent to its final configuration.

Description

Technical Field

[0001] The present invention relates to medical technology, and more particularly to interventional cardiology.

Background Art

[0002] Cardiovascular diseases are one of the biggest health problems in developed countries. One of the more serious conditions is coronary artery disease (CAD), which typically occurs when a portion of the smooth, elastic inner lining of the coronary arteries becomes hardened, stiffened, and swollen due to calcium deposits, fatty deposits, and abnormal inflammatory cells, leading to the formation of what is called plaque and atherosclerosis. This plaque can create an obstruction (known as stenosis) to the normal supply of oxygenated blood to the myocardium, which can cause chest pain (angina) and ultimately lead to the risk of cardiac arrest.

[0003] Interventional cardiology is a branch of cardiology that specializes in the catheter-based treatment of structural heart diseases such as CAD. One interventional cardiology procedure is known as percutaneous coronary intervention (PCI). In one mode of PCI, a catheter is inserted into a major systemic artery, either in the groin or arm, and manipulated toward the entrance of the coronary artery branches at the origin of the aorta. This catheter takes the form of a thin tube (known as a Judkins catheter) through which radiopaque dyes can be delivered into the bloodstream, allowing visualization of the coronary arteries using a special type of X-ray called fluoroscopy (known as angiography). Other techniques for imaging the coronary arteries (e.g., intravascular ultrasound) may also be used. If the narrowing (stenosis) is deemed severe enough, a common treatment is to insert a stent to restore the artery to its original (non-stenotic) diameter. To place the stent, another catheter is passed through the first catheter and then advanced further to the narrowed portion of the coronary artery. Once the tip is in place, the balloon, which has a stent crimped around it, is inflated. The tip of the balloon compresses the plaque, expanding the stent. Once the plaque is compressed and the stent is in place, the balloon is deflated and withdrawn. The stent remains inside, keeping the artery open.

[0004] PCI generally results in beneficial patient outcomes, but long-term complications such as in-stent restenosis (ISR) or stent thrombosis (ST) can occur. ISR occurs when tissue and plaque grow through the stent wall. ST occurs when blood clots adhere to the stent. Both complications will again obstruct the normal blood flow that the stent was supposed to restore.

[0005] Advances in stent material selection have led to the current generation of stents including drug-eluting stents (coated with drugs that slowly release to prevent cell proliferation and reduce ISR and ST) and bioreabsorbable stents (designed to dissolve into the bloodstream over a long period, giving the artery a chance to heal in a non-stenotic state). While material selection significantly impacts patient outcomes, another crucial characteristic is how well the stent fits into the patient's artery. Ideally, the stent should remain in contact with the arterial wall in a "juxtaposed" state when expanded, without being pushed so far as to damage the endothelium (the layer of cells that make up the inner lining of the arterial wall). In this case, the endothelium should form a thin layer that grows over the stent as the artery heals, but not to the point of causing ISR or ST.

[0006] Currently, stents are manufactured in various lengths and diameters, and the appropriate size is selected by examining the narrowed artery using imaging techniques, such as angiography. One problem with this method is that arteries may be tapered or have some complex shape, and a simple cylindrical structure may not be suitable for maintaining contact with the arterial wall in a juxtaposed position. Therefore, the difference between the shape of a ready-made stent and the shape specific to the patient can be quite large, resulting in complications due to incomplete closure and inappropriate sizing. These differences range from tens to hundreds of microns, but currently employed techniques cannot achieve a more precise control of tolerances. Incomplete closure between the stent and the arterial wall can lead to complex patterns of low wall shear stress (friction on the arterial wall caused by blood flow), resulting in cell proliferation that can lead to ISR and ST.

[0007] Therefore, technologies are needed to address the aforementioned problems. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] U.S. Patent Application No. 15 / 498,159 [Patent Document 2] U.S. Patent Application No. 15 / 498,185 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The principle of the present invention provides a technique for producing personalized coronary artery stents. [Means for solving the problem]

[0010] In a first aspect, the present invention provides a method for providing a stent, comprising: generating a 3D model of the non-stenotic shape of a blood vessel in response to a three-dimensional (3D) model of the actual shape of the blood vessel; establishing a parametric description of the stent that can be extended from a collapsed configuration to a final configuration juxtaposed with the non-stenotic shape, wherein the parametric description includes parameters characterizing the stent's support structure; creating a design for the stent by changing the parameters of the parametric description in response to a design heuristic that includes the risk of the stent's support structure breaking during plastic deformation between the collapsed configuration and the final configuration; and embodying the stent according to the design for the stent.

[0011] In a further embodiment, the present invention provides a device comprising a mandrel having a generally cylindrical, hollow membrane for receiving a balloon, and a plurality of columns protruding from the outer surface of the membrane, wherein at least one of the columns protrudes to a different radius from at least one of the other columns, and a stent supported by the mandrel, wherein the columns of the mandrel abut against the bridge of the stent.

[0012] In a further aspect, the present invention provides a method for providing a stent, comprising inserting a stent having an asymmetrically deflated configuration into a blood vessel; manipulating the stent through the blood vessel to reach a stenosis at a given location in the blood vessel; and expanding the stent from a deflated configuration to an asymmetrically final configuration corresponding to an asymmetrically non-stenotic shape at a given location in the blood vessel.

[0013] In a further aspect, the present invention provides a computer program product for providing a stent, comprising a computer-readable storage medium readable by a processing circuit, the computer-readable storage medium storing instructions to be executed by the processing circuit to carry out a method for carrying out the steps of the present invention.

[0014] In a further aspect, the present invention provides a computer program that is stored on a computer-readable medium and loadable into the internal memory of a digital computer, the computer program comprising a software code portion for performing the steps of the present invention when the program is run on the computer.

[0015] In one embodiment, an exemplary method includes generating a 3D model of the non-stenotic shape of a vessel in response to a 3D model of the actual shape of the vessel. The method further includes establishing a parameter description of a stent that extends from a deflated configuration to a final configuration juxtaposed with the non-stenotic shape, wherein the parameter description includes parameters characterizing the stent's support structure. The method further includes creating a design for the stent by changing the parameters of the parameter description in response to a heuristic design that includes the risk of the stent's support structure breaking during plastic deformation between the deflated configuration and the final configuration. Furthermore, the method includes materializing the stent according to the design for the stent.

[0016] According to another aspect of the present invention, an exemplary apparatus includes a mandrel having a generally cylindrical, hollow membrane for receiving a balloon, and having a plurality of columns projecting from the outer surface of the membrane, wherein at least one of the columns projects to a different radius than at least one of the other columns, and a stent supported by the mandrel, wherein the columns of the mandrel abut against the bridge of the stent.

[0017] According to another aspect of the present invention, an exemplary method includes inserting a stent having an asymmetrically deflated configuration into a blood vessel; manipulating the stent through the blood vessel to a stenosis at a given location in the blood vessel; and expanding the stent from a deflated configuration to an asymmetrically final configuration corresponding to an asymmetrically non-stenotic shape at a given location in the blood vessel.

[0018] According to another aspect of the present invention, a non-transient computer-readable medium embodies computer-executable instructions that, when executed by a computer, cause the computer to perform actions that facilitate any of the exemplary methods discussed above. In one or more embodiments, the computer-executable instructions include instructions that control a 3D printer to embody a stent. According to another aspect of the present invention, the apparatus includes a memory that embodies computer-executable instructions and at least one processor coupled to the memory that operates by the computer-executable instructions to facilitate any of the exemplary methods discussed above.

[0019] As used herein, “facilitating” an act includes performing the act, simplifying the act, assisting in the performance of the act, or causing the act to be performed. Therefore, an instruction running on one processor may facilitate an act performed by an instruction running on a remote processor by transmitting appropriate data or commands to cause the act to be performed or to assist in its performance. To avoid misunderstanding, if an actor facilitates an act in a manner other than performing the act, the act is still performed by some entity or combination of entities.

[0020] One or more embodiments of the present invention or its elements may be implemented in the form of a computer program product including a computer-readable storage medium along with computer-readable program code for performing the indicated method steps. Furthermore, one or more embodiments of the present invention or its elements may be implemented in the form of a system (or device) including memory and at least one processor coupled to the memory and operating to perform the exemplary method steps. In yet another aspect, one or more embodiments of the present invention or its elements may be implemented in the form of means for performing one or more of the method steps described herein, the means may include (i) a hardware module, (ii) a software module stored in a computer-readable storage medium (or more such mediums) and implemented on a hardware processor, or (iii) a combination of (i) and (ii), any of (i) to (iii) implements the particular technology described herein.

[0021] Other features and advantages of the present invention will become apparent from the following detailed description of its exemplary embodiments, which will be read in conjunction with the accompanying drawings.

[0022] Embodiments of the present invention will be described here merely as examples with reference to the accompanying drawings.

Brief Description of the Drawings

[0023] [Figure 1] It is a diagram showing how to create a desired (non - stenotic) blood vessel shape from a 3D model of a stenotic blood vessel according to an exemplary embodiment of the present invention. [Figure 2] It is a diagram showing how to create the design of an individualized coronary stent from a stent template and a desired blood vessel shape according to an exemplary embodiment of the present invention. [Figure 3] It is a diagram showing parameter design for a general - purpose stent template according to an exemplary embodiment of the present invention. [Figure 4] It is a flowchart of a method for creating the final configuration of an individualized coronary stent according to an exemplary embodiment of the present invention. [Figure 5] It is a diagram showing how to create a mandrel shape from a mandrel template and the design of an individualized coronary stent according to an exemplary embodiment of the present invention. [Figure 6] It is a side cross - sectional view of an individualized coronary stent supported by a mandrel within a blood vessel according to an exemplary embodiment of the present invention. [Figure 7] It is an end cross - sectional view of the individualized coronary stent, mandrel, and blood vessel of FIG. 6 according to an exemplary embodiment of the present invention. [Figure 8] It is an end cross - sectional view of the individualized coronary stent and mandrel of FIGS. 6 and 7 in a crimped configuration according to an exemplary embodiment of the present invention. [Figure 9] It is a flowchart of a method for implanting an individualized coronary stent according to an exemplary embodiment of the present invention. [Figure 10] It shows a computer system that may be useful for implementing one or more aspects, or elements, or both of the present invention, and represents a node of cloud computing according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0024] Based on angiography and other imaging techniques, it is possible to construct a detailed three-dimensional (3D) model of a narrowed blood vessel. For example, standard intravascular imaging catheters use optical coherence tomography, which obtains high-resolution images by irradiating lasers radially. By equipping the imaging catheter with an inertial measurement unit ("IMU"), it becomes possible to obtain positional information. Using this positional information, a 3D model of the inside of the blood vessel (i.e., the inside of the narrowed vessel) can be created from the images.

[0025] According to one or more exemplary embodiments, a time-varying 3D model is generated using a catheter with a camera that also carries radiopaque positional markers. For example, the radiopaque positional markers may include a pair of elliptical hoops attached to the catheter so as to remain stationary relative to the camera. The hoops are arranged orthogonally to each other, and each hoop as a whole is radiopaque, so that a complete ellipse can be seen in the angiography from all angles, with the exception that it cannot be seen from an angle parallel to the plane of one of the ellipses, in which case a single line is seen in the angiography. The catheter with a camera is introduced into the patient's vascular system by a guidewire, and camera images are captured from the catheter as the catheter is guided through the vascular system to the target location, generating a 3D model of this target location. In addition to the camera images from the catheter, angiography images of the catheter and guidewire are also captured to define a time-varying reference curve, and accelerometer and gyroscope data of the catheter are recorded. By integrating accelerometer and gyroscope data over time in combination with camera and angiography images, a time-varying 3D model (4D model) of the catheter and target location is created. This disclosure incorporates, by reference, the entire disclosures of U.S. Patent Application No. 15 / 498,159, filed April 26, 2017, “Intravascular Catheter for Modeling Blood Vessels,” and U.S. Patent Application No. 15 / 498,185, filed April 26, 2017, “Intravascular Catheter Including Markers.”

[0026] In particular, these previously filed patent applications disclose a method for generating a four-dimensional model, which includes capturing images of a catheter and a blood vessel as the catheter is guided through a blood vessel to a target location, wherein the catheter is positioned on a guidewire, constructing a time-varying three-dimensional reference curve describing the trajectory of the guidewire, and using this reference curve to construct a time-varying three-dimensional model of an artery. Preferably, these previously filed patent applications further disclose a method for constructing a time-varying three-dimensional reference curve describing the trajectory of a guidewire, comprising the steps of: obtaining at least two angiographic runs from different field angles for a guidewire, as well as a proximal marker, a distal tip marker, and a lens marker, that can be viewed over a complete cardiac cycle; mapping each frame of the at least two angiographic runs to a position within the cardiac cycle; selecting a subset of frames from the at least two angiographic runs that include at least that cardiac cycle; segmenting the proximal marker, the distal tip marker, the lens marker, and the guidewire from that subset of frames; and calculating, over time in a world coordinate system, the intersections between the at least two angiographic runs for each of the proximal marker, the distal tip marker, the lens marker, and the guidewire, and determining the reference curve to be the trajectory of the lens marker as a function of time in the world coordinate system.

[0027] Preferably, these previously filed patent applications relate to a method which further involves constructing a time-varying three-dimensional model of the artery using a reference curve, performing an intravascular imaging retraction at a known velocity while recording the linear and rotational acceleration of the catheter, acquiring at least one angiographic run from the field of view used to determine the trajectory of the guidewire during the intravascular imaging retraction, mapping each frame of the at least one angiographic run to a position within the cardiac cycle, segmenting the catheter lens marker in each frame, and in multiple steps of the intravascular imaging retraction, Further disclosure includes a method comprising: calculating the distance of a lens marker along the guidewire trajectory relative to its starting position using a known velocity of the retraction of intravascular imaging; transforming the orientation of the catheter's lens marker in each frame into a world coordinate system; integrating the linear and rotational accelerations of the catheter forward with respect to the guidewire trajectory using the world coordinate positions of the lens marker; obtaining multiple cross-sectional curves for each frame; mapping each cross-sectional curve to a corresponding point along the guidewire trajectory; and obtaining a time-varying 3D surface model by connecting the cross-sectional curves.

[0028] Furthermore, these previously filed patent applications disclose a method for generating a four-dimensional (4D) model during a percutaneous coronary intervention (PCI) procedure, comprising capturing images of the catheter and a vessel as the catheter is guided through a vessel to a target location, wherein the catheter is positioned on a guidewire and comprises a plurality of markers and a monitoring body, and the images are captured from at least two different viewpoints; segmenting the guidewire and at least one marker from the images; backprojecting the segmented guidewire and at least one segmented marker into three-dimensional (3D) space to define a time-varying reference curve that defines the movement of the monitoring body; recording accelerometer and gyroscope data of the catheter using a combination of sensors as the catheter is withdrawn from the target location; integrating the accelerometer and gyroscope data over time; predicting the linear and rotational positions of the monitoring body in the images; and constructing a 4D model of the monitoring body and a vessel using the predicted linear and rotational positions of the monitoring body, wherein the 4D model includes a time-varying surface representing the vessel.

[0029] Preferably, these previously filed patent applications further disclose a method in which capturing an image includes capturing multiple angiographic images. Preferably, these previously filed patent applications further disclose a method in which capturing an image includes simultaneously capturing different viewpoints over a single cardiac cycle. Preferably, these previously filed patent applications further disclose a method in which capturing an image includes capturing one different viewpoint at a time over consecutive cardiac cycles. Preferably, these previously filed patent applications further disclose a method in which a time-varying reference curve defines the movement of a monitoring body as a set of coordinates in spacetime. Preferably, these previously filed patent applications further disclose a method in which accelerometer and gyroscope data includes measurements of inertial acceleration and rotational position in three dimensions. Preferably, these previously filed patent applications further disclose a method in which drift errors accumulated in accelerometer data are further corrected using magnetometer data.

[0030] However, the exact mode of obtaining a time-varying 3D model may differ; for example, the time-varying 3D model may be obtained by MRI or ultrasound. Thus, it is assumed that the time-varying 3D model can be obtained by any method, the stenosis can be identified using that model, and the model can be smoothed over the stenotic region to create the non-stenotic shape.

[0031] As shown in Figure 1, according to an exemplary embodiment of the present invention, a computer implements a method 300 for generating a 3D model of a non-stenotic shape 302 of a blood vessel in response to a time-varying 3D model of a stenotic shape 304 of a blood vessel obtained by one of the methods described above. In one or more embodiments, the computer averages the time-varying 3D model of the stenotic shape 304 to identify the stenotic portion 306 and generates the non-stenotic shape 302 by smoothing the blood vessel wall 308 over the stenotic portion 306.

[0032] Figure 2 is a block diagram showing a method 400 for creating the final configuration of an individualized coronary stent 402 based on a general-purpose stent template 403 and a 3D model of a non-stenotic shape 302. The individualized coronary stent 402 according to an embodiment of the present invention is appropriately juxtaposed with the non-stenotic shape 302, thereby mitigating the problems associated with the use of off-the-shelf stents.

[0033] To provide an automated method for generating the final configuration of the personalized coronary stent 402, a stent parameter description is required. The parameter description defines several key geometric parameters that can be synchronized with an optimization routine accompanied by a continuum mechanics solver.

[0034] Figure 3 shows detail 500 of a general-purpose stent template 403, which shows two adjacent arches 502, 504 of the general-purpose stent template 403. Each arch 502, 504 is provided with a pair of struts 506, which are joined to each other at the strut intersections (arch apex 508). The apex 508 of the two arches are connected by a bridge 510. Parameters of this particular design include the length (indicated as a) and thickness (indicated as b) of the bridge 510, as well as the thickness (indicated as c) and length (indicated as d) of each strut 506. As part of determining the final configuration for the patient, the software modifies the template parameters so that the final configuration of the stent 402 is juxtaposed with a non-stenotic shape 302, ensuring a low probability of failure during an expansion event.

[0035] Referring again to Figure 2, once the non-stenotic shape 302 is generated, the computer implements a method 400 to determine the final configuration of the personalized coronary stent 402 by adjusting the key shape parameters of the generic stent template 403 using heuristic design. In 404, the computer generates a candidate configuration 406 by relaxing the vertices 508 of the generic stent template 403 so that they are juxtaposed with the 3D model of the non-stenotic shape 302. The computer implements the relaxation by applying a radial inertial force 412 to the generic stent template 403 so that the vertices 508 are uniformly distributed across the non-stenotic vessel shape 302. Next, the computer implements a method 600 (shown in Figure 4) to test the validity of the candidate configuration 406 to the implantation procedure.

[0036] Figure 4 is a flowchart showing a method 600 for testing the validity of candidate configuration 406 for the implantation procedure. In one or more embodiments, the computer tests the validity of the candidate configuration by heuristic design. In one or more embodiments, testing the validity of candidate configuration 406 includes, in 602, facilitating a mechanical stress / strain analysis of the plastic deformation of the stent from candidate configuration 406 to deflated configuration 416 (crimping the stent so that it can be inserted into a blood vessel) using the continuum mechanical solver described above. In one or more embodiments, testing the validity of the candidate configuration further includes, in 604, facilitating a mechanical stress / strain analysis of the plastic deformation of the stent from deflated configuration 416 back to candidate configuration 406 (expanding the stent so that it can be implanted in a blood vessel). In 605, the computer applies a heuristic design to the results of the mechanical stress / strain analyses 602, 604. The heuristic design is, for example, that there is no stent failure after plastic deformation. If the heuristic design is not met, i.e., if the computer identifies any failure during plastic deformation, in 606, the computer generates a modified stent template 418 having different stent column thicknesses (variable stiffness) by modifying one or more of the columns 506 and bridges 510 of the general-purpose stent template 403 by modifying one or more of the parameters a, b, c, and d. In 608, the computer generates a new candidate configuration 420 based on the modified stent template 418 and the non-constricted shape 302.

[0037] In one or more embodiments, the deflated configuration 416 matches the modified stent template 418. In other embodiments, the deflated configuration 416 is a version of candidate configuration 406 that has been plastically deformed (crimped) to fit within the same radius as the modified stent template 418, which will be further described below with reference to Figure 9.

[0038] The computer iterates through blocks 602, 604, 606, and 608 until a candidate configuration 406 satisfies the heuristic design (e.g., no corruption), and in response, the computer facilitates saving the valid candidate configuration 406 as the final configuration of stent 402 in 610.

[0039] Therefore, Method 400 produces a design for a 3D personalized coronary artery stent 402 by changing the parameters of the parameter description of a general-purpose stent "template" design 403, where the parameter description includes parameters that characterize the struts of the stent template. More specifically, Method 400 includes deforming the length and thickness of the struts 506 and bridge 510 so that the shape of the deformed template can be matched to the contour of a complex arterial shape 302 that includes features such as tapering, bulging, and other non-axisymmetric features. To modify the stent template 403, the shape is considered a simplified structure in which the center of mass of a vertex 508 defines a set of coordinates in 3D space, and a linear segment defined by the two coordinates defines a simplified strut or bridge. The point corresponding to the vertex 508 is then moved around repeatedly while maintaining the topological connectivity of the struts 506 and bridge 510 to match the shape to the complexity of the arterial shape 302. The deformation process is carried out by repeatedly moving the point defining the vertices 508 of the stent struts 506 radially inward or outward (depending on whether the starting point is inside or outside the target shape surface 302) until all vertices 508 are within a user-specified distance (juxtaposition tolerance) from the surface. The direction in which the points are moved can be calculated from either the centerline of the stent template 403 or the centerline of the target shape 302, or by using other techniques common in computational geometry. As described above with reference to Figure 4, the parameters of the stent template are repeatedly modified in response to heuristic designs that represent or include the risk of stent strut failure during plastic deformation between the deflated and final configurations of the stent 402.

[0040] Figure 5 is a flowchart illustrating a method 700 for establishing the shape of a mandrel 702 to support a deflated stent 402. The mandrel 702 is fabricated from a mandrel template 704 and the final configuration of the individualized coronary stent 402. The mandrel template 704 has a generally cylindrical body, the majority of which is formed as a relatively thin membrane 705. The mandrel template 704 also includes a number of relatively stiff columns 706 protruding from its membrane 705, and relatively stiff guide sections 707 connected to the ends of its membrane 705. In one or more embodiments, the columns 706 and guide sections 707 can be relatively stiffer by having a thicker cross-section than the membrane 705. The guide sections 707 include a radiopaque marker 708, for example, an elliptical marker similar to those described above for a camera-equipped catheter. This marker 708 is positioned to provide a unique indicator of the mandrel's location and orientation within the angiographic image.

[0041] The mandrel 702 has a relaxed shape and an extended shape. In the relaxed shape, the hollow membrane 705 is relaxed and fits over a standard balloon catheter in an uninflated state. In the extended shape, the hollow membrane 705 is extended over a standard balloon catheter in an inflated state. The membrane 705 is a relatively flexible membrane, while the column 706 is a relatively rigid member attached to the membrane 705 at its base. The mandrel 702 has multiple columns 706, each extending to a radius determined as follows. First, in 710, a model 711 of the concentric, coaxial configuration of the mandrel 702 and the individualized coronary stent 402 is established. Next, in 712, the radial distance 713 from the extended shape of the mandrel 702 to each bridge 510 of the final configuration of the individualized coronary stent 402 is calculated. The radial distance 713 gives the height of the column 706. Thus, assuming uniform radial displacement of the mandrel membrane 705 achieved by inflating a standard balloon catheter, the position and size of the column 706 are selected to expand the individualized coronary stent 402 from its deflated configuration 416 to its final configuration.

[0042] Figure 6 shows a lateral cross-sectional view of the final configuration of an individualized coronary stent 402 supported by its bridge 510 on a column 706 of a mandrel 702 within a vessel wall 308, according to an exemplary embodiment of the present invention. The balloon catheter 802 is shown inflated within the mandrel 702, holding the mandrel in its extended shape. When the balloon catheter 802 becomes deflated, the mandrel elastically returns to its relaxed shape, while the individualized coronary stent 402 plastically deforms into its final configuration and remains juxtaposed with the vessel wall 308.

[0043] Figure 7 shows a cross-sectional view of the end portion of the individualized coronary stent 402, mandrel 702, balloon catheter 802, and vessel wall 308.

[0044] In one or more embodiments, the personalized coronary stent 402 is 3D printed in its expanded state (final configuration) so that it can slide over the balloon catheter 802 and mandrel 702, then plastically crimped onto them and positioned. Alternatively, the personalized coronary stent 402 is 3D printed around the column 706 of the mandrel 702 and then crimped onto the column 706. Primarily for this purpose, the stent design process includes stress / strain analysis of deformation from the final configuration to the deflated configuration and deformation back from the deflated configuration to the final configuration.

[0045] Standard crimping devices for coronary artery stents provide a uniform radial inward displacement, which would be unsuitable for the asymmetrical shape of the individualized coronary artery stent 402. Therefore, referring to Figure 8, a sleeve 1002 is designed and materialized (e.g., 3D printed) along with the individualized coronary artery stent 402. This sleeve 1002 allows the use of a standard crimping device to crimp the stent. The sleeve 1002 has a body 1004 that is essentially the same as the general-purpose stent template and therefore symmetrical, but has a diameter slightly larger than the maximum diameter in the final configuration of the individualized coronary artery stent. The sleeve 1002 includes inwardly projecting finger portions 1006, which are lumps of the same 3D printable material (e.g., polylactic acid) as the rest of the sleeve 1002 and the stent. The finger portion 1006 is printed onto the bridge 1010 of the sleeve 1002 and aligned to be in registry with the bridge 510 of the stent, so that the bridge does not undergo any circumferential displacement during the crimping or expansion process. The length of the finger portion 1006 is defined by calculating the distance between the support sleeve 1002 and the corresponding contact point (bridge 510) of the stent. Thus, Figure 8 shows a deflated configuration 416 of the individualized coronary stent crimped to the column 706 of the mandrel 702 by the sleeve 1002, in an end section view.

[0046] Figure 9 shows a method 1100 for constructing and implanting a personalized coronary stent 402, a mandrel 702, and a sleeve 1002. According to one or more implementations of method 1100, a computing system 10 facilitates the embodiment of the personalized coronary stent 402 in its final configuration. In one or more embodiments, the computing system 10 facilitates the embodiment of the personalized coronary stent 402 by controlling a 3D printer 1103. Thus, in one or more embodiments, in 1102, the computer controls the 3D printer 1103 to 3D print the mandrel membrane 705, the column 706, and the guide section 707. A highly flexible but elastic material (e.g., a stretchable UV-curable elastomer) is used for 3D printing the mandrel 702. Then, in 1104, the computer controls the 3D printer 1103 to 3D print the personalized coronary stent 402. In one or more embodiments, the personalized coronary stent 402 is printed around the column 706 of the mandrel so that the bridge 510 of the stent 402 aligns with the column. Depending on the reference view of the X-ray system to be used during placement, the elliptical marker 708 is selected to have a specific view, which affects the angular position in which the personalized coronary stent 402 and column 706 are printed on the mandrel membrane 705 relative to the marker. Alternatively, in one or more embodiments, the personalized coronary stent 402 is printed separately from the mandrel 702 and then assembled onto the mandrel. A plastically deformable material (e.g., polylactic acid) is used to 3D print the stent 402.

[0047] In 1106, the computer controls the 3D printer 1103 to print the sleeve 1002 and its finger portions 1006. In one or more embodiments, the sleeve 1002 is printed around the individualized coronary stent 402 so that the finger portions 1006 are aligned with the bridge of the stent 402. Alternatively, in one or more embodiments, the sleeve 1002 is printed separately from the stent 402 and then assembled to the stent. A plastically deformable material (e.g., polylactic acid) is used to 3D print the sleeve 1002.

[0048] At 1108, the individualized coronary stent 402, mandrel 702, and sleeve 1002 are fitted around the balloon catheter 802. At 1110, the assembly is crimped onto the balloon catheter 802. At 1111, the sleeve 1002 is removed, for example, by cutting it. Then at 1112, the crimped assembly of the balloon catheter 802, mandrel 702, and individualized coronary stent 402 is inserted into the blood vessel. At 1114, the assembly is guided to its placement site using continuous or periodic angiography to confirm the position and orientation of the assembly within the blood vessel. At 1116, the balloon catheter 802 is inflated to plastically deform the individualized coronary stent 402 and juxtapose it with the blood vessel wall 308. In step 1118, the balloon catheter 802 is deflated, and the catheter and elastic mandrel 702 are retracted through the blood vessel and withdrawn from the insertion site.

[0049] A time-varying model of the blood vessel can be used to assist in stent placement. When a stent is placed in an artery, it can be imagined that the stent will move around due to the movement of the heart, and therefore the movement of the coronary arteries. Consequently, the ellipses on the mandrel will also move around, and their appearance will change in the angiography acquired during stent placement. In one or more embodiments, a non-stenotic shape is generated using a snapshot of the time-varying model, but it is possible to print the mandrel columns and stent onto a mandrel template so that when the stent is properly placed, radiopaque ellipses appear in a specific shape in the angiographic frame that coincides with the corresponding point in the cardiac cycle, as can be seen from the reference field of view (for the X-ray system) and the point in the cardiac cycle from which the snapshot was selected. Furthermore, it is possible to see how the appearance of the ellipses changes as the entire assembly of balloon, mandrel, and stent moves around during the cardiac cycle, thereby providing more information about the current position of the assembly.

[0050] The technology of the present invention can provide quite beneficial technical effects. For example, one or more embodiments can achieve one or more of the following: better juxtaposition of stents with the luminal wall, and development and fabrication of custom stent designs in the laboratory.

[0051] Considering the discussions to date, it is understood that, broadly speaking, an exemplary method according to one aspect of the present invention involves generating a 3D model of the non-stenotic shape of a blood vessel in response to a 3D model of the actual shape of the blood vessel. This method further includes establishing a parameter description of a stent that extends from a deflated configuration to a final configuration juxtaposed with the non-stenotic shape, wherein the parameter description includes parameters characterizing the stent's support structure. This method further includes creating a design for the stent by changing the parameters of the parameter description in response to a heuristic design that includes the risk of the stent's support structure breaking during plastic deformation between the deflated configuration and the final configuration. Furthermore, this method includes embodying the stent according to the design for the stent.

[0052] In one or more embodiments, the method further includes establishing the shape of a mandrel to support a deflated stent configuration and embodying the mandrel according to that shape. In one or more embodiments, establishing the shape of the mandrel includes establishing a plurality of columns projecting from the membrane of the mandrel, wherein at least one of the columns extends to a different radius than at least one of the other columns. Furthermore, in one or more embodiments, establishing the shape of the mandrel includes configuring the columns of the mandrel to support the bridge of a deflated stent configuration. Also in one or more embodiments, establishing the shape of the mandrel includes configuring the columns of the mandrel to also support the bridge of a final configuration stent when the mandrel is extended to its elongated shape. In one or more embodiments, embodying the mandrel includes 3D printing the mandrel, and embodying the stent includes 3D printing the stent around the mandrel so that the bridge of the stent is aligned with the columns of the mandrel.

[0053] In one or more embodiments, materializing the stent includes 3D printing the stent in its final configuration, and exemplary methods further include establishing the shape of a sleeve to facilitate crimping the stent from its final configuration to a deflated configuration, and materializing the sleeve according to that shape. In one or more embodiments, the shape of the sleeve includes a generally cylindrical body and columns projecting inward from the body. According to a particular embodiment, establishing the shape of the sleeve includes configuring the columns of the sleeve to uniformly compress the bridge of the stent radially from its final configuration to its deflated configuration. In one or more embodiments, materializing the sleeve includes 3D printing the sleeve around the stent.

[0054] In one or more embodiments, exemplary methods also include establishing the shape of a mandrel to support a deflated stent, embodying the mandrel according to its shape, positioning the stent in its final configuration around the mandrel, establishing the shape of a sleeve to facilitate crimping the stent from the final configuration into a deflated configuration, embodying the sleeve according to its shape, positioning the sleeve around the stent, and crimping the stent to the mandrel by using the sleeve to distribute a uniform radial force to the asymmetrical bridge of the stent.

[0055] According to another aspect of the present invention, an exemplary apparatus includes a mandrel having a generally cylindrical, hollow membrane for receiving a balloon, and having a plurality of columns projecting from the outer surface of the membrane, wherein at least one of the columns projects to a different radius than at least one of the other columns, and a stent supported by the mandrel, such that the columns of the mandrel abut against the bridge of the stent.

[0056] In one or more embodiments, the device also includes a balloon catheter inserted into the mandrel. In one or more embodiments, the device also includes a sleeve surrounding the stent, the sleeve having inwardly projecting fingers that contact the bridge of the stent opposite the fingers of the mandrel, at least one of the inwardly projecting fingers projecting to a different radius than at least one other of the inwardly projecting fingers.

[0057] In one or more embodiments, the balloon catheter is inserted into the mandrel.

[0058] In one or more embodiments, the mandrel includes an elliptical radiopaque marker.

[0059] According to another aspect of the present invention, an exemplary method includes inserting a stent having an asymmetric deflated configuration into a blood vessel; manipulating the stent through the blood vessel to a stenosis at a given location in the blood vessel; and expanding the stent from a deflated configuration to an asymmetric final configuration corresponding to an asymmetric non-stenotic shape at a given location in the blood vessel. In one or more embodiments, the method also includes supporting the stent with a mandrel having an asymmetric column to support the deflated configuration of the stent at the bridge of the stent during insertion and manipulation of the stent, and expanding the stent includes inflating a balloon within the mandrel.

[0060] According to another aspect of the present invention, a non-transient computer-readable medium embodies a computer-executable instruction that, when executed by a computer, causes the computer to perform actions that facilitate any of the exemplary methods discussed above. In one or more embodiments, the computer-executable instruction includes instructions that control a 3D printer to embody a stent.

[0061] According to another aspect of the present invention, the apparatus includes a memory for embodying computer executable instructions and at least one processor coupled to the memory and operating by the computer executable instructions to facilitate any of the exemplary methods discussed above.

[0062] One or more embodiments of the present invention or its elements can be implemented in the form of a device comprising memory and at least one processor coupled to the memory and operating to perform exemplary method steps. Figure 10 shows an exemplary embodiment of computing system 10, which may be useful in implementing one or more aspects or elements or combination thereof of the present invention, and which also illustrates a computer system according to an embodiment of the present invention. Referring here to Figure 10, computing system 10 is merely an example of a suitable computer system and does not imply any limitation on the scope of use or functionality of the embodiments of the present invention described herein. In any case, computing system 10 can implement or perform any or both of the functions described above.

[0063] Computing system 10 includes computer systems / servers 12 that operate with a number of other general-purpose or dedicated computing system environments or configurations. Examples of well-known computing systems, environments, or configurations, or combinations thereof, that may be suitable for use with computer systems / servers 12 include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics products, network PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments that include any of these systems or devices.

[0064] The computer system / server 12 can be described in the general context of computer system executable instructions, such as program modules executed by the computer system. Generally, program modules may include routines, programs, objects, components, logic, data structures, etc., that perform a specific task or implement a specific abstract data type. The computer system / server 12 may be practiced in a distributed cloud computing environment where tasks are performed by remote processing devices linked over a communication network. In a distributed cloud computing environment, program modules may reside on both local and remote computer system storage media, including memory storage devices.

[0065] As shown in Figure 10, the computer system / server 12 of the computing system 10 is in the form of a general-purpose computing device. The components of the computer system / server 12 may include, but are not limited to, one or more processors or processing units 16, system memory 28, and a bus 18 that connects various system components, including the system memory 28, to the processor 16.

[0066] Bus 18 represents one or more of several types of bus structures, including memory buses or memory controllers using one of a variety of bus architectures, peripheral buses, accelerated graphics ports, and processor or local buses. Examples, but not limited to, these architectures include industry standard architecture (ISA) buses, micro-channel architecture (MCA) buses, extended ISA (EISA) buses, video electronics standards association (VESA) local buses, and peripheral component interconnect (PCI) buses.

[0067] The computer system / server 12 typically includes various computer system-readable media. These media may be any available media accessible by the computer system / server 12, and may include both volatile and non-volatile media, as well as both removable and non-removable media.

[0068] System memory 28 may include computer system-readable media in the form of volatile memory, such as random access memory (RAM) 30, or cache memory 32, or both. The computer system / server 12 may further include other removable / non-removable, volatile / non-volatile computer system storage media. As just one example, storage system 34 may be provided for reading from and writing to a non-removable, non-volatile magnetic medium (not shown, but usually called a “hard drive”). Not shown, a magnetic disk drive may be provided for reading from and writing to a removable, non-volatile magnetic disk (e.g., a “floppy disk”), and an optical disk drive may be provided for reading from or writing to a removable, non-volatile optical disk, such as a CD-ROM, DVD-ROM, or other optical media. In such cases, each may be connected to bus 18 by one or more data medium interfaces. As will be further shown and described below, the memory 28 may include at least one program product having a set (for example, at least one) of program modules configured to perform the functions of embodiments of the present invention.

[0069] For example, but not limited to, an operating system, one or more application programs, other program modules, and program data, as well as a program / utility 40 having a set (at least one) of program modules 42, may also be stored in memory 28. Each operating system, one or more application programs, other program modules, and program data, or any combination thereof, may include an implementation of a networked environment. The program modules 42 generally perform the functions and / or methods of the embodiments of the present invention described herein.

[0070] The computer system / server 12 may also communicate with one or more external devices 14, such as a keyboard, pointing device, or display 24; one or more devices that allow a user to interact with the computer system / server 12; or any device that allows the computer system / server 12 to communicate with one or more other computing devices (e.g., a network card, modem, etc.); or a combination thereof. Such communication can be performed via the input / output (I / O) interface 22. Furthermore, the computer system / server 12 may communicate with one or more networks, such as a local area network (LAN), a general-purpose wide area network (WAN), or a public network (e.g., the Internet); or a combination thereof, via the network adapter 20. As shown, the network adapter 20 communicates with other components of the computer system / server 12 via the bus 18. It should be understood that other hardware components, or software components, or both, which are not shown, may be used in conjunction with the computer system / server 12. Examples include, but are not limited to, microcode, device drives, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data archive storage systems.

[0071] Therefore, one or more embodiments can utilize software that runs on a general-purpose computer or workstation. Referring to Figure 10, such implementations may use, for example, a processor 16, memory 28, and a display 24, and an input / output interface 22 to an external device 14 such as a keyboard or pointing device. As used herein, the term “processor” is intended to include any processing device, such as a CPU (central processing unit), or other forms of processing circuitry, or both. Furthermore, the term “processor” may refer to two or more individual processors. The term “memory” is intended to include memory associated with a processor or CPU, such as RAM (random access memory) 30, ROM (read-only memory), fixed memory devices (e.g., hard drive 34), removable memory devices (e.g., diskettes), and flash memory. Furthermore, as used herein, the phrase “input / output interface” is intended to refer to an interface to, for example, one or more mechanisms for inputting data into a processing unit (e.g., a mouse) and one or more mechanisms for providing results associated with the processing unit (e.g., a printer). The processor 16, memory 28, and input / output interface 22 can be interconnected, for example, via a bus 18 as part of a data processing unit 12. Suitable interconnections via the bus 18 can also be provided, for example, a network interface 20 such as a network card that can be provided to interface with a computer network, and a media interface such as a diskette or CD-ROM drive that can be provided to interface with a suitable medium.

[0072] Accordingly, computer software including instructions or code for carrying out the methods of the present invention as described herein may be stored in one or more associated memory devices (e.g., ROM, fixed or removable memory), loaded partially or entirely (e.g., into RAM) when ready for use, and implemented by the CPU. Such software may include, but is not limited to, firmware, resident software, and microcode.

[0073] A data processing system suitable for storing and / or executing program code includes at least one processor 16 directly coupled to the memory element 28 or indirectly coupled to it through the system bus 18. The memory element may include local memory used during the actual implementation of the program code, mass storage, and cache memory 32 for temporary storage of at least some of the program code to reduce the number of times the code must be read from the mass storage during implementation.

[0074] Input / output, or I / O, devices (including, but not limited to, keyboards, displays, and pointing devices) can be coupled directly to the system or to it via an intermediary I / O controller.

[0075] The network adapter 20 may also be coupled to the system to enable the data processing system to be coupled to other data processing systems, remote printers, or storage devices via an intervening private or public network. Modems, cable modems, and Ethernet(R) cards are just a few of the types of network adapters currently available.

[0076] As used herein, including in the claims, “server” includes a physical data processing system (for example, system 12 shown in Figure 10) on which a server program runs. It will be understood that such a physical server may or may not include a display and a keyboard.

[0077] Any of the methods described herein may include a further step of providing a system comprising a separate software module embodied on a computer-readable storage medium, the module of which may include, for example, any or all of the appropriate elements shown in the block diagram, or described herein, or both, and it will be noted, not limited to, one, part, or all of the described module / block, or submodule / subblock, or both. The method step may then be carried out using the separate software module, or submodule, or both, of the above-described system running one or more hardware processors such as 16. Furthermore, including providing a system having a separate software module, the computer program product may include a computer-readable storage medium having code adapted to be implemented to perform one or more method steps described herein.

[0078] Exemplary system and product details The present invention may be a system, method, or computer program product, or a combination thereof. The computer program product may include one (or more) computer-readable storage media having computer-readable program instructions for causing a processor to implement an aspect of the present invention.

[0079] Computer-readable storage media can be tangible devices capable of holding and storing instructions used by instruction execution devices. Computer-readable storage media may be, but are not limited to, electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination thereof. A more specific, but not exhaustive, list of computer-readable storage media includes portable computer diskettes, hard disks, random-access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), static random-access memory (SRAM), portable compact disk read-only memory (CD-ROM), digital multipurpose disks (DVDs), memory sticks, floppy disks, mechanically encoded devices such as punched cards or grooved structures on which instructions are recorded, and any suitable combination thereof. The computer-readable storage media used herein should not be interpreted as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through optical fiber cables), or electrical signals transmitted through wires.

[0080] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, or a wireless network, or a combination thereof. The network may include copper transmission cables, optical transmission fibers, wireless transmissions, routers, firewalls, switches, gateway computers, or edge servers, or a combination thereof. The network adapter card or network interface of each computing / processing device receives the computer-readable program instructions from the network and transfers those computer-readable program instructions so that they can be stored in the computer-readable storage medium within each computing / processing device.

[0081] Computer-readable program instructions for performing the operations of the present invention may be assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, configuration data for integrated circuits, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk and C++, and procedural programming languages ​​such as the C programming language or similar programming languages. Computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or wide area network (WAN), or it may be connected to an external computer (for example, via the Internet using an Internet service provider). In some embodiments, an electronic circuit including, for example, a programmable logic circuit, a field-programmable gate array (FPGA), or a programmable logic array (PLA) may execute computer-readable program instructions by utilizing state information of computer-readable program instructions for individualizing the electronic circuit in order to carry out aspects of the present invention.

[0082] Aspects of the present invention will be described herein with reference to flowcharts, block diagrams, or combinations thereof of methods, apparatus (systems), and computer program products according to embodiments of the present invention. It will be understood that each block in a flowchart, block diagram, or combination thereof, as well as combinations of blocks in a flowchart, block diagram, or combination thereof, can be implemented by computer-readable program instructions.

[0083] These computer-readable program instructions may be provided to a general-purpose computer, a dedicated computer, or a processor of another programmable data processing device to generate means for implementing functions / actions shown in one or more blocks of a flowchart or block diagram, or a combination thereof, thereby creating a machine. These computer-readable program instructions may also be stored on a computer-readable storage medium such that the computer-readable medium on which the instructions are stored contains a product containing instructions that implements a mode of function / action shown in one or more blocks of a flowchart or block diagram, or a combination thereof, and can instruct a computer, a programmable data processing device, or another device, or a combination thereof, to function in a particular way.

[0084] Computer-readable program instructions may also be loaded into other programmable data processing devices or other devices to generate a computer implementation process in which instructions executed on a computer, other programmable device, or other device implement a function / action shown in one or more blocks of a flowchart or block diagram, or a combination thereof, causing a set of operational steps to be executed on the computer, other programmable device, or other device.

[0085] The flowcharts and block diagrams in the drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or part of an instruction, which contains one or more executable instructions for implementing a particular logical function. In some alternative implementations, the functions shown in the blocks may be performed in an order different from the order shown in the diagram. For example, two blocks shown consecutively may actually be executed substantially simultaneously, or these blocks may be executed in reverse order depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, or both, and combinations of blocks in a block diagram or flowchart, or both, can be implemented by a dedicated hardware-based system that performs a particular function or action, or a combination of dedicated hardware and computer instructions.

[0086] The descriptions of various embodiments of the present invention are presented for illustrative purposes only and are not intended to be exhaustive or limitful to the embodiments disclosed. Many variations and modifications will be apparent to those skilled in the art without departing from the scope of the embodiments described. The terms used herein have been selected to best describe the principles of the embodiments, practical applications, or technologies that are superior to those available on the market, or to enable those skilled in the art to understand the embodiments disclosed herein. [Explanation of symbols]

[0087] 300,400,600,700 method 302 Non-stenotic shape 304 Stenosis shape 306 Stenosis 308 Blood vessel wall 402 Personalized coronary stent 403 General-purpose stent template 406 candidate configurations 416 Shrunken composition 412 Inertia force 418 Modified stent template 420 New candidate configurations 500 Details 502, 504 Arch 506 Post 508 Arch apex 510 Bridge 702 Mandrel 704 Mandrel Template 705 Membrane 706 pillars 707 Guidance Category 708 Marker 802 Balloon Catheter 1002 Sleeves 1006 Finger part 1010 Bridge

Claims

1. A method for manufacturing stents and mandrels, In response to a three-dimensional (3D) model of the actual shape of the blood vessel, a 3D model of the non-stenotic shape of the blood vessel is generated. To establish a parameter description of a stent, wherein the stent includes a plurality of supports, and the stent can be expanded from a predetermined configuration that can be inserted into a blood vessel to a final configuration in which the supports are arranged in a non-stenotic shape by widening the gaps between the plurality of supports, and the parameter description includes parameters that characterize the dimensions of the supports of the stent. The design for the stent is generated by a heuristic design that includes determining, by mechanical stress / strain analysis, whether there is a risk of the support column breaking during the plastic deformation of the stent between the predetermined configuration and the final configuration, and repeating the determination by changing the parameters of the parameter description according to the determination that there is a risk, Establishing the shape of the mandrel supporting the stent of the predetermined configuration, comprising establishing the plurality of columns such that at least one of a plurality of columns, which are more rigid than the membrane and protrude from the flexible membrane of the mandrel, extends to a different distance from the central axis of the mandrel compared to at least one of the other columns, wherein the position and size of the plurality of columns are selected so that the stent expands into the final configuration when the membrane is inflated and uniformly displaced radially, 3D printing the mandrel according to the shape of the mandrel, 3D printing the stent according to the design for the stent, The stent is positioned around the mandrel such that the bridge of the stent aligns with the column of the mandrel, A method that includes this.

2. The method according to claim 1, wherein establishing the shape of the mandrel includes configuring the columns of the mandrel to support the bridge of the stent of the predetermined configuration.

3. The method according to claim 2, wherein establishing the shape of the mandrel involves configuring the columns of the mandrel such that the mandrel also supports the bridge of the stent in the final configuration when it is extended into an elongated shape.

4. The method according to any one of claims 1 to 3, wherein 3D printing of the stent includes 3D printing of the stent around the mandrel.

5. Establishing the shape of a sleeve having a generally cylindrical body and a plurality of finger portions projecting inward from the body, wherein the length of the finger portions is defined based on the distance between the body and the corresponding bridge of the stent in the final configuration, 3D printing the sleeve according to the shape of the sleeve and The method according to any one of claims 1 to 4, further comprising:

6. The method according to claim 5, wherein the shape of the sleeve is established such that each of the finger portions uniformly compresses the bridge of the corresponding stent radially from the final configuration to the predetermined configuration.

7. The method according to claim 5 or 6, wherein 3D printing the sleeve includes 3D printing the sleeve around the stent.

8. A computer program stored on a computer-readable medium and loadable into the internal memory of a digital computer, the computer program including a software code portion for carrying out the method according to any one of claims 1 to 7 when the program is run on the computer.

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