Ductal Arterial and Septal Conduit Implants and Related Delivery Systems and Methods - Patent application

Abstract

Embodiments of stents and associated delivery systems for treating congenital heart disease are provided. The devices described herein are configured to insert into a vascular lumen to maintain patency of the conduit and balance flexibility and resistance for delivery via a microcatheter. The devices described herein are configured to transition from a crimped configuration to an expanded configuration. In the crimped configuration, the device has a crimped diameter of less than about 0.7 mm. In the expanded configuration, the device is configured to have an expanded diameter of greater than about 3 mm as measured at the body section. In the expanded configuration, the devices described herein are configured to have a radial force of greater than about 0.20 N / mm at 1 mm compression. Various devices having these characteristics are described herein.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 63 / 211,768, filed June 17, 2021, the entire contents of which are incorporated herein by reference.

[0002] (Incorporated by reference) All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

[0003] The present application relates to the field of cardiovascular implants, in particular stents designed for congenital heart disease. [Background technology]

[0004] The technical challenges faced by pediatric cardiovascular physicians (surgeons and interventionalists alike) have long been ignored, forcing them to use instruments designed for adults and different conditions to treat sick babies with very specific anatomical considerations. One such case is the persistent patency of the ductus arteriosus, a natural conduit present in all newborns but which closes shortly after birth. Another example is the need to create or maintain an opening, or septal conduit, in the septum between the two ventricles of the heart (e.g., the left and right atria) to allow mixing of oxygenated and deoxygenated blood for the health of the patient.

[0005] In certain congenital heart diseases, intermixing of systemic and pulmonary circulation, including maintaining ductal patency and / or providing a septal conduit between the right and left atria, is crucial for neonatal survival without surgical intervention. Although stent-like devices exist to address many cardiovascular diseases, no devices are specifically designed to maintain patency of the neonatal ductus arteriosus or septal conduit. As a result, reinterventions, morbidity, and mortality with current standard of care are unacceptably high. For example, pediatric interventional cardiologists currently repurpose adult coronary arteries into ductal arteries, with an overall mortality rate of ductal reinterventions of approximately 47%. Summary of the Invention [Problem to be solved by the invention]

[0006] Thus, a need exists for a device that adequately maintains patency of the ductus arteriosus in newborns. Additionally, a need exists for a device that provides communication between the right and left atria as a method of providing pressure relieving solution to the pulmonary circulation, as a method of reducing the size of naturally occurring ASDs, or as a method of reducing access ports in transseptal procedures in children born with significant congenital heart disease (e.g., when atrial level mixing is adequate) resulting in reduced morbidity and mortality compared to atrial stent placement. [Means for solving the problem]

[0007] One aspect of the present disclosure is directed to an instrument for insertion into a vascular lumen to maintain patency of the ductus arteriosus, the instrument configured to be delivered via a microcatheter, the instrument comprising: a first end section including a first plurality of struts configured to expand to define a proximal surface having a first diameter, a second end section including a second plurality of struts configured to expand to define a distal surface having a second diameter, a body section extending between the first end section and the second end section and defining a third diameter, the body section including the third plurality of struts, and an instrument lumen extending through the first end section, the body section, and the second end section, the instrument lumen configured to allow blood to flow through the instrument lumen.

[0008] In any of the previous embodiments, the device is configured to transition from a crimped configuration to an expanded configuration such that in the crimped configuration, the crimped diameter of the device is less than about 0.7 mm, and in the expanded configuration, the device is configured to expand to an expanded diameter, measured at the body section, of greater than about 3 mm.

[0009] In any of the previous embodiments, in the expanded configuration, the device has a radial force of greater than about 0.20 N / mm at 1 mm of compression.

[0010] In any of the previous embodiments, in the expanded configuration, the first diameter of the proximal surface is about 20% to about 50% larger than the third diameter of the body section.

[0011] In any of the previous embodiments, in the expanded configuration, the second diameter of the distal surface is about 20% to about 50% larger than the third diameter of the body section.

[0012] In any of the previous embodiments, in the expanded configuration, the first diameter of the proximal face is about 20% to about 50% larger than the third diameter of the body section, and when in the expanded configuration, the second diameter of the distal face is about 20% to about 50% larger than the third diameter of the body section.

[0013] In any of the previous embodiments, the first diameter of the proximal surface is about 20% to about 30% larger than the third diameter of the body section, and the second diameter of the distal surface is about 20% to about 30% larger than the third diameter of the body section.

[0014] In any of the previous embodiments, each of the first plurality of struts has a first length, each of the second plurality of struts has a second length, and each of the third plurality of struts has a third length.

[0015] In any of the previous embodiments, the third length of each of the third plurality of struts is between about 1 mm and 2 mm.

[0016] In any of the previous embodiments, the first length of each of the first plurality of struts and the second length of each of the second plurality of struts is between about 2.5 mm and about 4 mm.

[0017] In any of the previous embodiments, the first plurality of struts of the first end section are arranged in one or more first rings.

[0018] In any of the previous embodiments, the one or more first rings of the first end section include a first end ring including a plurality of struts at a first end, a second ring from the first end including a second plurality of struts from the first end, and a third ring from the first end including a third plurality of struts from the first end.

[0019] In any of the previous embodiments, the first terminal strut length is longer than the second terminal strut length which is longer than the third terminal strut length.

[0020] In any of the previous embodiments, in the expanded configuration, adjacent first struts in each of the one or more first rings form a substantially constant angle.

[0021] In any of the previous embodiments, the substantially constant angle is between about 50 degrees and about 70 degrees.

[0022] In any of the previous embodiments, the substantially constant angle is between about 60 degrees and about 70 degrees.

[0023] In any of the previous embodiments, the one or more first rings includes between 2 and 5 first rings.

[0024] In any of the previous embodiments, adjacent first rings of the first end section are connected via 3 to 9 first bridges.

[0025] In any of the previous embodiments, each first bridge has a first length of about 0.1 mm to about 0.25 mm.

[0026] In any of the previous embodiments, the second plurality of struts in the second end section are arranged in one or more second rings.

[0027] In any of the previous embodiments, the one or more second rings of the second end section include a second end ring including a plurality of struts at the second end, a second ring from the second end including a second plurality of struts from the second end, and a third ring from the second end including a third plurality of struts from the second end.

[0028] In any of the previous embodiments, the second terminal strut length of the second terminal strut is longer than the third strut length from the second terminal of the third strut from the second terminal, and longer than the second strut length from the second terminal of the second strut from the second terminal.

[0029] In any of the previous embodiments, in the expanded configuration, adjacent second struts in each of the one or more second rings form a substantially constant angle.

[0030] In any of the previous embodiments, the substantially constant angle is between about 50 degrees and about 70 degrees.

[0031] In any of the previous embodiments, the substantially constant angle is between about 60 degrees and about 70 degrees.

[0032] In any of the previous embodiments, the one or more second rings includes between 2 and 5 second rings.

[0033] In any of the previous embodiments, the first plurality of struts of the first end section are arranged in one or more first rings and the second plurality of struts of the second end section are arranged in one or more second rings.

[0034] In any of the previous embodiments, the proximal facing end ring comprises a first end plurality of struts each having a first length that is increased by about 100% to about 250% relative to a third length of each of the third plurality of struts.

[0035] In any of the previous embodiments, the distal face terminal ring includes a second terminal plurality of struts each having a second length that is increased by about 100% to about 250% relative to the third length of each of the third plurality of struts.

[0036] In any of the previous embodiments, adjacent second rings of the second end section are connected via 3 to 9 second bridges.

[0037] In any of the previous embodiments, each second bridge has a second length between about 0.1 mm and about 0.25 mm.

[0038] In any of the previous embodiments, the first end section and the second end section are configured to secure the device to at least a portion of the aortic ostium and at least a portion of the pulmonary artery ostium, respectively, such that the body section spans the ductus arteriosus.

[0039] In any of the previous embodiments, the third plurality of struts of the body section are substantially parallel to the longitudinal axis of the device in the expanded configuration.

[0040] In any of the previous embodiments, a terminal subset on the proximal face of the first plurality of struts forms a proximal angle with respect to the longitudinal axis of the device.

[0041] In any of the previous embodiments, the proximal angle is between about 30 degrees and about 110 degrees.

[0042] In any of the previous embodiments, the proximal angle is between about 45 degrees and about 90 degrees.

[0043] In any of the previous embodiments, a terminal subset on the distal face of the second plurality of struts forms a distal angle with respect to the longitudinal axis of the device.

[0044] In any of the previous embodiments, the distal angle is between about 30 degrees and about 110 degrees.

[0045] In any of the previous embodiments, the distal angle is between about 45 degrees and about 90 degrees.

[0046] In any of the previous embodiments, the device further comprises one of an anti-thrombogenic coating, an anti-proliferative coating, and a friction-reducing coating.

[0047] In any of the previous embodiments, the device includes a drug-eluting coating.

[0048] Another aspect of the present disclosure is directed to an instrument for insertion into a vascular lumen to maintain patency of the ductus arteriosus, the instrument configured to be delivered through a microcatheter, the instrument comprising: a first end section including a first plurality of struts configured to expand to define a proximal surface having a first diameter, a second end section including a second plurality of struts configured to expand to define a distal surface having a second diameter, a body section extending between the first end section and the second end section and defining a third diameter, the body section including the third plurality of struts, and an instrument lumen extending through the first end section, the body section, and the second end section, the instrument lumen configured to allow blood to flow through the instrument lumen.

[0049] In any of the previous embodiments, the device is configured to transition from a crimped configuration to an expanded configuration, where in the crimped configuration the device has a crimped diameter of less than about 0.7 mm and where in the expanded configuration the device is configured to expand to an expanded diameter, measured at the body section, of greater than about 3 mm.

[0050] In any of the previous embodiments, in the expanded configuration, the first diameter of the proximal surface and the second diameter of the distal surface are each about 20% to about 50% larger than the third diameter of the body section.

[0051] In any of the previous embodiments, the device, in the expanded configuration, has a first diameter on the proximal surface and a second diameter on the distal surface each having a radial force of greater than about 0.20 N / mm at 1 mm compression.

[0052] In any of the previous embodiments, in the expanded configuration, the diameter is about 1 mm to about 2 mm larger than the third diameter of the body section.

[0053] Another aspect of the present disclosure is directed to a system for delivering an instrument into a lumen of an arterial duct to maintain patency of the lumen of the arterial duct. The system includes a delivery system with a microcatheter and a pusher wire. The pusher wire is configured to advance through a lumen defined by the microcatheter. The pusher wire includes a first hub and an implant receiving section. The implant is configured to be pushed by the first hub when loaded into the implant receiving section of the pusher wire. The implant includes a first end section including a first plurality of struts configured to expand to define a proximal surface having a first diameter, a second end section including a second plurality of struts configured to expand to define a distal surface having a second diameter, a body section extending between the first end section and the second end section and defining a third diameter, the body section including the third plurality of struts, and an implant lumen extending through the first end section, the body section, and the second end section, the implant lumen configured to allow blood to flow through the implant lumen.

[0054] In any of the previous embodiments, the implant is configured to transition from a crimped configuration to an expanded configuration upon exiting the microcatheter, where in the crimped configuration the implant has a crimped diameter of less than about 0.7 mm and where in the expanded configuration the implant is configured to expand to an expanded diameter, measured in the body section, of greater than about 3 mm.

[0055] In any of the previous embodiments, in the expanded configuration, the implant has a radial force of greater than about 0.20 N / mm at 1 mm of compression.

[0056] In any of the previous embodiments, the first hub includes a female connector and the proximal face of the implant includes a complementary male connector configured to interact with the female connector of the first hub.

[0057] In any of the previous embodiments, the proximal face includes a plurality of radiopaque markers, and the first hub is configured to push against the plurality of radiopaque markers to deploy the implant.

[0058] In any of the previous embodiments, the pusher wire further comprises a second hub.

[0059] In any of the previous embodiments, the second hub is configured to interface with an inner diameter of the distal face of the implant such that the pusher wire is configured to be displaced proximally during deployment of the implant.

[0060] In any of the previous embodiments, the first hub defines one or more openings configured to receive a contrast agent therethrough.

[0061] In any of the previous embodiments, the delivery system further comprises a transfer sheath.

[0062] Another aspect of the present disclosure is directed to an implant configured for treatment of congenital heart disease, the implant configured for delivery through a microcatheter, the implant comprising: a first end section including a first plurality of struts configured to expand to define a proximal surface having a first diameter, a second end section including a second plurality of struts configured to expand to define a distal surface having a second diameter, a body section extending between the first end section and the second end section and defining a third diameter, the body section including the third plurality of struts, and an instrument lumen extending through the first end section, the body section, and the second end section, the instrument lumen configured for blood to flow through the instrument lumen.

[0063] In any of the previous embodiments, the implant is configured to transition from a crimped configuration to an expanded configuration, where in the crimped configuration the crimped diameter of the instrument lumen is less than about 0.7 mm, and where in the expanded configuration the implant is configured to expand to an expanded diameter of greater than about 3 mm, measured in the body section.

[0064] In any of the previous embodiments, the implant, in the expanded configuration, has a radial force of greater than about 0.20 N / mm at 1 mm of compression.

[0065] In any of the previous embodiments, the congenital heart defect is a septal defect of the patient's heart, and the implant is configured to be delivered within a septal conduit between two ventricles of the patient's heart.

[0066] In any of the previous embodiments, the congenital heart defect is a ductus arteriosus and the implant is configured to be inserted into the ductus arteriosus to maintain patency of the ductus arteriosus.

[0067] In any of the previous embodiments, the one or more terminal crowns of the distal face have an angle of about 30% to about 110% relative to the longitudinal axis of the body section.

[0068] In any of the previous embodiments, the one or more terminal crowns on the proximal face have an angle of about 30% to about 110% relative to the longitudinal axis of the body section.

[0069] Another aspect of the present disclosure is directed to a method of maintaining communication through the atrial septum of a heart, the method including advancing a distal end of a stent delivery system into the right atrium, the stent delivery system including a microcatheter, the method further including advancing the distal end of the stent delivery system across the septum, deploying a distal end section of the stent into the left atrium to secure the distal end section of the stent to a wall of the septum facing the left atrium, deploying a body section of the stent into the septum, and deploying a proximal end section of the stent into the right atrium to secure the proximal end section of the stent to a wall of the septum facing the right atrium.

[0070] In any of the previous embodiments, the stent has a radial force of about 0.2 N / mm or greater at about 1 mm of compression.

[0071] In any of the previous embodiments, the diameter of one or both of the proximal and distal ends of the stent is about 20% to 40% larger than the diameter of the body section of the stent.

[0072] In any of the previous embodiments, advancing the distal end section of the stent delivery system across the septum includes advancing the distal end section of the stent delivery system across one of a hole, an atrial septal defect, or a septal incision.

[0073] In any of the previous embodiments, deploying the distal end section of the stent into the left atrium includes applying tension or force to the proximal end section of the stent delivery system to secure the distal end section of the stent to the septal wall.

[0074] In any of the previous embodiments, the stent has a length of about 3 mm to about 10 mm.

[0075] In any of the previous embodiments, the diameter of the body section of the stent is from about 4 mm to about 5 mm.

[0076] Another aspect of the present disclosure is directed to a method of maintaining patent ductus arteriosus in a pediatric patient, the method including deploying with a microcatheter a distal end section of a self-expanding stent at a first end of a lumen defined by the ductus arteriosus, securing at least a portion of a distal surface of the distal end section of the self-expanding stent such that the distal surface at least partially circumferentially covers the pulmonary artery ostium, deploying with a microcatheter a proximal end section of the self-expanding stent such that a body section of the self-expanding stent covers an entire length of the lumen defined by the ductus arteriosus, and securing at least a portion of a proximal surface of the proximal end section of the self-expanding stent such that the proximal surface at least partially circumferentially covers the aortic ostium.

[0077] In any of the previous embodiments, the self-expanding stent, when deployed, has a radial force of about 0.2 N / mm or greater at about 1 mm of compression.

[0078] In any of the previous embodiments, the method further includes administering a prostaglandin to the pediatric patient to dilate the lumen defined by the ductus arteriosus of the pediatric patient.

[0079] Another aspect of the present disclosure is directed to a method of maintaining patent ductus arteriosus in a pediatric patient in which the diameter of the ductus arteriosus is greater than the diameter of a body section of a stent, the method including deploying, with a microcatheter, a distal end section of a self-expanding stent into a first end of a lumen defined by the ductus arteriosus, securing at least a portion of a distal surface of the distal end of the stent such that the distal surface at least partially circumferentially covers the distal end of the ductus arteriosus, deploying, with a microcatheter, a proximal end section of the stent such that the body section of the stent is within the entire length of the lumen defined by the ductus arteriosus, and securing at least a portion of a proximal surface of the proximal end section of the stent such that the proximal surface at least partially circumferentially covers the ostium of an adjacent artery.

[0080] The features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: [Brief description of the drawings]

[0081] [Figure 1A] ~ [Figure 1D] FIG. 1 illustrates one embodiment of a method for maintaining ductus patency by approaching the ductus arteriosus from the aorta. [Figure 2A] ~ [Figure 2D] FIG. 1 illustrates one embodiment of a method for maintaining ductus arteriosus by approaching the ductus arteriosus from the pulmonary artery. [Figure 3A] FIG. 1 illustrates one embodiment of an exemplary stent in a two-dimensional (2D) crimped configuration configured to maintain lumen or duct patency (once expanded in vivo). [Figure 3B] FIG. 3B is an enlarged two-dimensional view of the first end section of FIG. 3A. [Figure 3C] FIG. 3B is an enlarged two-dimensional view of the body section of the stent of FIG. 3A. [Figure 3D] FIG. 3B shows the stent of FIG. 3A in an expanded configuration. [Figure 3E] FIG. 3E is a schematic diagram of the stent of FIG. 3D. [Figure 4A] FIG. 1 shows one embodiment of a stent for maintaining lumen or duct patency. [Figure 4B] FIG. 4B is an enlarged view of an end section of the stent of FIG. 4A. [Figure 5A] ~ [Figure 5C] 5A-5C show angiographic examples of various vascular anatomies, where FIG. 5A shows Type I vascular anatomies, FIG. 5B shows Type II vascular anatomies, and FIG. 5C shows Type III vascular anatomies. [Figure 6] 13A-13C show another embodiment of a body section of a stent that accommodates hairpin turns. [Figure 7] 13A-13C show another embodiment of a distal end of a stent for maintaining lumen or duct patency. [Figure 8A] ~ [Figure 8B] 8A-8B show an exemplary stent for maintaining lumen or duct patency in a first, shortened configuration (FIG. 8A) and a second, elongated or expanded configuration (FIG. 8B). [Figure 9] 1 is a perspective view of an end section of an exemplary stent secured within a test lumen and configured to maintain lumen or duct patency. [Figure 10] 13A-13C show another embodiment of a stent end section in a 2D crimp configuration. [Figure 11A]1A-1C show an embodiment of a stent configured to be anchored mid-lumen within a body lumen or conduit. [Figure 11B] ~ [Figure 11C] 11B shows various degrees of deployment or expansion of the stent of FIG. 11A. [Figure 12] 13A-13D show one embodiment of a locking mechanism between adjacent stent rings or between a stent and a hub of a delivery system. [Figure 13] 13A-13C show another embodiment of a locking mechanism between adjacent stent rings or between a stent and a hub of a delivery system. [Figure 14] 13A-13C show another embodiment of a stent end section in a 2D crimp configuration. [Figure 15] 13A-13C show another embodiment of the body section of a stent in a 2D crimp configuration. [Figure 16] 13A-13C show another embodiment of the body section of a stent in a 2D crimp configuration. [Figure 17A] ~ [Figure 17B] 1A-1D show male portions of a stent and female portions of a delivery system, respectively, that allow for controlled deployment and / or elongation or expansion of the stent during deployment. [Figure 18] 13A-13C show another embodiment of a stent body section in a 2D crimp configuration. [Figure 19] 1 is a side profile of one embodiment of an end section of a stent for maintaining lumen or duct patency. [Figure 20] 13 is a side profile of another embodiment of an end section of a stent for maintaining lumen or duct patency. [Figure 21] 13 is a side profile of another embodiment of an end section of a stent for maintaining lumen or duct patency. [Figure 22] 13A-13C show another embodiment of a stent having an expanded, bulging body section for anchoring the stent within a lumen or conduit. [Diagram 23]13A-13C show another embodiment of a stent having flared or flanged end sections for anchoring the stent within a lumen or conduit. [Figure 24] 13A-13C show another embodiment of an end section of a stent for maintaining lumen or duct patency. [Figure 25A] ~ [Figure 25D] FIG. 1 illustrates a method of stent deployment through a microcatheter. [Figure 26A] ~ [Figure 26D] 1A-1C illustrate a method of deploying a stent in a septal conduit. [Figure 27A] 1 is a perspective view of an embodiment of a stent configured for deployment within a septal conduit. [Figure 27B] FIG. 27B is a side view of the stent of FIG. 27A. [Figure 28] FIG. 1 illustrates one embodiment of a delivery system including a pusher wire, a stent, and a microcatheter for any of the stent embodiments described herein. [Figure 29] 1 is a schematic diagram illustrating various anatomical considerations regarding a stent and associated delivery system. [Diagram 30] FIG. 1 illustrates one embodiment of a delivery system for any of the stent embodiments described herein. [Diagram 31] FIG. 13 shows another embodiment of a delivery system for any of the stent embodiments described herein. [Diagram 32] FIG. 13 shows another embodiment of a delivery system for any of the stent embodiments described herein. [Diagram 33] FIG. 2 is a partial view of one embodiment of a pusher wire of a delivery system for any of the stent embodiments described herein. [Diagram 34] FIG. 13 is a partial view of another embodiment of a pusher wire of a delivery system for any of the stent embodiments described herein. [Diagram 35]FIG. 13 is a partial view of another embodiment of a pusher wire of a delivery system for any of the stent embodiments described herein. [Diagram 36] 13A-13C show another embodiment of a pusher wire of a delivery system for any of the stent embodiments described herein. [Figure 37] 13A-13C show another embodiment of a pusher wire of a delivery system for any of the stent embodiments described herein. [Figure 38] FIG. 1 shows crush test data for various stent designs described herein. [Figure 39] FIG. 13 shows crush test data for various stent designs described herein with varying number of crowns per ring. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0082] The illustrated embodiments are merely examples and are not intended to limit the present disclosure. The schematic diagrams are depicted to illustrate features and concepts and are not necessarily drawn to scale.

[0083] The above is a summary and is therefore necessarily limited in detail. The above aspects, as well as other aspects, features, and advantages of the present technology, are described below in conjunction with various embodiments. The inclusion of the following embodiments is not intended to limit the disclosure to these embodiments, but rather to enable anyone skilled in the art to make and use the contemplated invention(s). Other embodiments may be utilized, and modifications may be made, without departing from the spirit or scope of the subject matter presented herein. The aspects of the present disclosure as described and illustrated herein can be arranged, combined, modified, and designed in a variety of different formulations, all of which are expressly contemplated and form part of the present disclosure.

[0084] Described herein are various embodiments of methods, stents, and delivery systems that can be used to treat congenital heart defects such as patent ductus arteriosus and septal duct defects. The various embodiments described herein are designed to address the technical challenges faced by physicians treating neonatal or pediatric patients, including appropriately sized delivery systems, end-to-end coverage of the defect (e.g., duct or conduit), navigation and deployment through tortuous anatomy, fixation of the stent in dilated ducts or thick-walled septal conduits, and precise placement to avoid protrusion of the stent into the aorta and pulmonary artery or ventricles. A stent specifically designed and tested for this purpose and patient population would reduce reinterventions, morbidity, and potential mortality in patients with ductus-dependent circulation or septal defects.

[0085] As used herein, "user" may include, but should not be limited to, physicians, assistants, doctors, nurses, interventionists, healthcare providers, technicians, radiologists, and the like.

[0086] As used herein, a "patient" includes, but is not limited to, a fetus, a neonate, a child, an infant, a premature baby, a baby, and the like.

[0087] As used herein, the terms "ductus" and "ductus arteriosus" may be used interchangeably.

[0088] In some embodiments, as used herein, "total tube length" can be measured from the aortic orifice to the pulmonary artery orifice, from a first tube end (e.g., of the aorta) to a second tube end (e.g., of the pulmonary artery), along the outer edge of the tube bend, along the inner edge of the tube bend, through the centerline of the tube bend, etc., based on anatomical imaging.

[0089] As used herein, "proximal" and "distal" are dependent on the approach of the delivery system. For example, if the vessel is approached from the aorta, the pulmonary artery may be considered distal to the aorta and delivery system. If the vessel is approached from the pulmonary artery, the aorta may be considered distal to the pulmonary artery and delivery system. For a septal conduit, if the septum is approached from the right atrium, the left atrium may be considered distal to the right atrium and delivery system. Thus, in some cases, the terms first end and second end are used interchangeably with the terms proximal end and distal end to illustrate the interchangeability of these terms and their dependence on the type of procedure being performed.

[0090] introduction

[0091] Congenital heart disease (CHD) is a condition that is present at birth and can affect the structure or function of an individual's heart. CHD is the most common type of birth defect, affecting approximately 1% of babies born in the United States each year. There are two types of CHD: (A) patent ductus arteriosus and (B) septal defect (e.g., atrial septal defect, ventricular septal defect, or atrioventricular septal defect), each of which is described in turn below.

[0092] (A) Patent ductus arteriosus

[0093] Approximately 2,000 babies born in the United States may benefit from a ductus arteriosus stent and are divided into two groups: patients with ductus-dependent pulmonary circulation and patients with ductus-dependent systemic circulation. The devices, systems and methods described herein provide an improved method for adequately maintaining ductal patency in pediatric patients.

[0094] Patients with ductus-dependent pulmonary circulation are typically treated with a modified BT shunt (MBTS), a procedure in which the patient is placed on cardiopulmonary bypass via thoracotomy (potentially detrimental to brain development) and a plastic conduit is placed to provide flow to the systemic and pulmonary circulation. MBTS carries a 7.2% morbidity and 13.1% mortality risk in the United States. Alternatively, ductal stenting has been shown to be superior, with potentially lower mortality rates not higher than MBTS, to providing ductus-dependent pulmonary circulation without the need for cardiopulmonary bypass. Reintervention rates are 47% for stenting with reuse of traditionally used coronary stents (i.e., off-label use). Reintervention rates are higher when the stent extends partially or completely into the pulmonary artery and places one of the pulmonary artery branches, occurring in 21.9% of cases of reuse of a coronary stent. Stents and delivery systems designed and tested to maintain ductus arteriosus patency could transition patients from open surgery to a less invasive approach, reducing mortality compared to MBTS and reducing reinterventions compared to reused coronary artery stents.

[0095] Patients with ductal dependent systemic circulation typically have hypoplastic left heart syndrome (HLHS). The first of three stage palliative procedures for HLHS is typically performed in the first two weeks of life. Hybrid procedures including ductal stenting can prevent the need to place such patients on bypass. Some centers have had good results with hybrid stage I palliative procedures, but results have been inconsistent and challenges remain with the use of reusable stents in ducts. The stents, systems, and methods described herein address the HLHS patient population.

[0096] Problems with the practice of using reused stents in the arterial vessel include: 1) a lack of understanding of vascular tissue-stent interactions to select a stent with the appropriate radial force; 2) difficulty in measuring the three-dimensional (3D) vessel with two-dimensional (2D) angiography, making stent sizing difficult; 3) the mechanical properties of the stent and delivery system can vary in vessel tortuosity and length, further complicating stent sizing; 4) difficulty in precise stent placement to prevent protrusion into the surrounding artery; 5) the delivery system is designed for adult vessels, so there is a risk of injury to smaller, more fragile vessels by percutaneous access to the stent placement site; 6) the delivery system does not accommodate the approach angle or deployment in tortuous vascular anatomy; and 7) the inability to precisely control vessel diameter at stent placement with prostaglandin titration makes it difficult to lock in the desired stent diameter to control blood flow.

[0097] Conventional coronary artery stents repurposed for vascular stenting in duct-dependent pulmonary circulation are balloon-expandable and designed to push obstructive atherosclerotic disease out of the vascular lumen, which is not the use case for ductal stenting where the stent needs to function in thin-walled, healthy vessels. Balloon-expandable coronary artery stents repurposed for vascular stenting have many limitations that make them less than optimal for vascular stenting. For example, the implants generally assume the shape of a straight balloon upon delivery, making them less conformable; they cannot elastically deform or rebound; they shorten anteriorly with balloon deployment, making sizing more difficult; their straight design without additional fixation mechanisms requires the stent diameter to be the same as the vessel diameter upon deployment; and they are less durable against fatigue. In addition, the delivery systems are generally balloon-mounted stents, which have a stiff distal end that makes it difficult to pass through tortuous anatomy without inducing vasospasm, and they often require a 4F sheath to traverse the vessel, further increasing the risk of spasm due to the large size of the sheath compared to the vessel size. Furthermore, stents that are flexible enough while loaded into a delivery system to traverse tortuous anatomy generally lack sufficient radial force to maintain patency of the lumen.

[0098] 5A-5C illustrate three major ductal anatomies encountered in duct-dependent pulmonary circulation. FIG. 5A illustrates a Type I ductal anatomies, e.g., short ducts that are substantially straight or linear. FIG. 5B illustrates a Type II ductal anatomies, e.g., long ducts that are more tortuous. FIG. 5C illustrates a Type III ductal anatomies, e.g., ducts with greater than 360 degree curves. The present invention advantageously provides systems, devices, and methods for stenting shorter to long ducts, including those with tortuous and looped ducts. The ducts may range in length from about 8 mm to about 28 mm, but it will be understood that they may be shorter or longer depending on the patient's anatomy. Additionally, the devices, systems, and methods described herein can substantially conform to the ductal anatomy, reducing the likelihood of unnatural straightening or lengthening of the duct. For example, as shown in FIG. 6, the body section 610 is configured to conform to the hairpin curve of the patent lumen (such a feature may be a feature of any of the body sections of the stents described herein). Thus, any of the stents (or features thereof) and methods described herein, and particularly Figures 1A-4B and 6-25D, may be configured to treat any of the vascular anatomical structures described above or elsewhere herein.

[0099] (B) Septal defect

[0100] Approximately 20,000 babies born each year in the United States have some form of septal defect (SD; atrial, atrioventricular, or ventricular). Currently, depending on the size and severity of the conduit, cardiac catheterization or open-heart surgery is recommended to close the conduit and restore normal blood flow. However, in certain rare cases, septal stent placement may be used to treat ventricular hypertension due to outflow obstruction. For example, up to 16,000 patients born each year could benefit from atrial septal resection.

[0101] In a typical heart, the atria are the two upper chambers of the heart, separated into the left and right atria by the atrial septum. In healthy infants, the atrial septum prevents oxygenated and deoxygenated blood from mixing. A naturally occurring hole between the two atria, the patent foramen ovale, is present in the fetal circulation but becomes hemodynamically insignificant soon after birth. However, in some infants with congenital heart disease, an opening must be created between the two atria because the pressure in the left atrium is too high and oxygenated and deoxygenated blood needs to mix at the atrial level. In some infants, the foramen ovale closes prematurely, and a septal resection device may be required to create a new conduit. Conditions in which creating a septal conduit is useful include: hypoplastic left heart syndrome (HLHS), other single ventricles with restrictive septum, transposition of the great arteries (TGA) with restrictive septum, pediatric pulmonary hypertension, extracorporeal membrane oxygenation decompression, and pulmonary vein stenosis.

[0102] Traditionally, the atrial septum is traversed by a balloon, inflated, and pulled across the atrial septum to tear it open. Balloon-assisted stenting does not allow for control of the size of the atrial septal opening, and often results in a large hole that closes, so it is not performed for patients who require a precise hole size. If a particular patient requires a precise hole size, a balloon-expandable stent is placed across the atrial septum and expanded to the desired diameter. The stent controls the diameter of the opening and ensures a reliable opening. However, there are several problems with current stents and delivery systems for treating SD. For example, conventional and reused stents can migrate or be too long, creating a risk of thrombosis and difficulty in placement. Conventional or reused stents can be tied off in the middle to create an hourglass shape to prevent migration, but such solutions are not satisfactory. Additionally, for example, conventional or reused stents can be difficult to place because they are not appropriately sized for the target anatomy in the pediatric patient population, which can also result in a risk of migration and / or thrombosis. Additionally, for example, the delivery systems are not adequately sized and not flexible enough for the target pediatric patient population, causing trauma to the blood vessels and heart during deployment.

[0103] Thus, a stent specifically tailored for treating SD or creating a septal fistula is needed to overcome the challenges of conventional or reusable stents. The stents and delivery systems described herein overcome these challenges for at least the following reasons: (1) the stent includes first and / or second end sections that are flared so that the stent can be anchored within the septal fistula, thus preventing migration and / or stretching within the atrial chamber, (2) the stent is configured to be crimped to a diameter sufficient to be delivered through a microcatheter (by adjusting strut length, strut thickness, strut width, number of crowns, number of bridges, etc., as described elsewhere herein), and (3) the stent is configured to have sufficient radial resistance once expanded (by adjusting strut length, strut thickness, strut width, number of crowns, number of bridges, etc., as described elsewhere herein).

[0104] Various stent embodiments and delivery systems described herein may be used to treat CHD, including septal defects, patent ductus arteriosus, and patent septal ducts. Additionally, various stent embodiments, delivery systems, and methods described herein overcome the technical challenges identified above. For example, the stents described herein may be deliverable using a microcatheter. Using a microcatheter places stringent requirements on the size of the stent in a crimped state. However, such a stent must also have sufficient radial force in an expanded state to prevent the patent vessel or septal duct from closing. The stents described herein may be made using Nitinol that is shape-fixed and thus configured to self-expand. The stent in the expanded state has a tailored radial force, as described elsewhere herein. Additionally, the stents described herein may be configured to be anchored in a vessel or septal duct to provide end-to-end coverage of the lumen or duct. Such anchoring may be achieved by proximal and / or distal end sections that include one or more mechanisms for anchoring the stent in the duct, as described elsewhere herein.

[0105] Various stent embodiments described herein include a first end section including a first plurality of struts configured to expand to define a proximal face having a first diameter, a second end section including a second plurality of struts configured to expand to define a distal face having a second diameter, and a body section extending between the first and second end sections and defining a third diameter, the body section also having a third plurality of struts.

[0106] The first end section and / or the second end section may include rows, struts, crowns, and / or bridges configured to act as flanges or fixation mechanisms to secure the struts to the anatomical structure. The first end section and / or the second end section described herein may have a length of about 1 mm to about 3 mm, about 1.5 mm to about 2.5 mm, about 2 mm, etc. Each end section may include about 1 to about 5 rings and / or about 3 to about 9 bridges or connectors.

[0107] In some embodiments, the stent has a diameter of about 3 mm to about 5 mm (5 diameters in 0.5 mm increments) for duct-dependent pulmonary circulation, a diameter of about 5 mm to about 10 mm (6 diameters in 1 mm increments) for duct-dependent systemic circulation, and a diameter of about 4 mm to about 5 mm for septal conduits. The stent flanges, flares, or cuffs (at the first and / or second end sections) allow the interventionist to select a smaller stent diameter for the duct or septal conduit without risking stent migration by fixing the stent without the need for full wall apposition, optimizing the final duct or conduit size and thus pulmonary blood flow after iprostaglandin infusion is stopped (in the case of the ductus arteriosus) or after mixing of oxygenated and deoxygenated blood (in the case of the septal conduit).

[0108] The stents described herein are adaptable in situ, allowing for deployment of a preformed first end section (e.g., a first flange or a first flare) that secures the stent to a distal end (e.g., the ostium of the pulmonary artery in the case of duct-dependent pulmonary circulation, or the aorta in the case of duct-dependent systemic circulation, or the septal wall of a ventricle) and a second end section (e.g., a second flange or a second flare) at a proximal end. The flanges at the proximal and distal ends ensure end-to-end coverage of the vessel or conduit.

[0109] Clinical outcomes with ductal stenting have shown significant improvements in mortality and emergency interventions for patients with ductal-dependent lung disease. When delivered to the anatomy and deployed in a manner that provides complete coverage, stents have been shown to be safe and effective, with recent technical success rates well over 90%, high survival rates, and a long-term solution to prevent ductal occlusion that cannot be achieved by administration of prostaglandins alone.

[0110] method

[0111] One embodiment of a method of deploying any of the stents described herein includes moving a microcatheter-based delivery system to the distal end of the vessel, withdrawing a distal end section (e.g., flange or flare) from the sheath that engages the vessel ostium at the pulmonary artery wall, and continuing to withdraw the stent from the sheath while applying light tension to effectively stretch the stent across the vessel, and positioning the proximal end section (e.g., flange) at the vessel ostium to ensure end-to-end coverage between the end sections without the stent protruding on either side of the vessel. This slight increase in stent and vessel length of about 3-5 mm allows the interventionist to compensate for vessel length measurements that are inherently inaccurate by several millimeters due to 2D measurements of the tortuous 3D vessel anatomy and changes in vessel length during stent placement. This length adjustability between the end sections (e.g., flanges) allows coverage of the most common vessel lengths, from about 8 mm to about 28 mm, with only seven different stent lengths. For example, Figures 8A-8B show a stent in a first, shortened configuration having a length of about 15 mm (Figure 8A) and the same stent in a second, elongated or expanded configuration having a length of about 20 mm (Figure 8B). The stent shown in Figure 8B is expanded (relative to the stent in Figure 8A), corresponding to a difference in tube length of about 5 mm.

[0112] In some embodiments, as shown in Figures 1A-1D and 2A-2D, a stent having fixation mechanisms at the first and second end sections may be partially (approximately 50%) deployed at the distal end of a first vessel (pulmonary artery) with the distal end section engaging the pulmonary artery wall adjacent the vessel. The interventionist may apply tension while deploying the latter portion of the stent, effectively slightly compressing the length of the arterial vessel. This slight increase in vessel length allows the interventionist to compensate for inherent inaccuracies in vessel length measurements due to 2D measurements of the tortuous 3D vessel structure and changes in vessel length due to stent placement. The distal and proximal end sections also provide mechanisms for fixation of the stent without full wall apposition during stent deployment. Fixation mechanisms at one or both end sections allow the stent to be placed in vessels with diameters larger than the diameter of the stent without risk of the stent migrating downstream.

[0113] 1A-1D and 2A-2D show two methods of deploying a stent in the ductus arteriosus. FIGS. 1A-1D show one embodiment of a method of delivering any of the stents described herein to the ductus arteriosus from the aorta to the pulmonary artery. FIG. 1A shows one embodiment of a method of advancing a delivery system 130 through the aorta 100 and the ductus arteriosus 120 to approach the pulmonary artery 110. As shown in FIG. 1B, the delivery system 130 restrains the stent body and releases the first or distal end section 116 which expands outward to the diameter of the lumen of the duct 120 or a portion thereof. In some embodiments, the diameter of the stent is undersized relative to the diameter of the lumen defined by the duct, e.g., due to prostaglandin therapy or the selected size of the stent, as described elsewhere herein. The first end section 116, which may include any one or more of the features illustrated in Figures 3A-4B, 7, 9-14, 17A-17B, 19-25D, 27A-27B of any of the stent embodiments described herein, is at least partially secured to the vessel lumen and / or at least partially circumferentially covers the ostium of the pulmonary artery 110. As shown in Figure 1C, the constrained (by the microcatheter) stent body 118 is released from the delivery system 130. In some embodiments, the constrained rings of the stent body are released individually, segment by segment (each segment includes one or more rings or multiple rings), subset by subset (a subset includes one or more segments), or collectively from the distal end of the delivery system and expanded until the entire length of the vessel is covered. The second, or proximal, end section is released to expand outward. A second end section 122 of any of the stents described herein, which may include any one or more of the features illustrated in Figures 3A-4B, 7, 9-14, 17A-17B, 19-25D, 27A-27B, is at least partially secured to the lumen of the tube 120 and / or at least partially circumferentially covers the ostium of the aorta 100, as shown in Figure 1D. Advantageously, this method of delivering any of the stents described herein may be used to increase pulmonary circulation in a patient, but may also be used to increase systemic circulation.

[0114] 2A-2D further illustrate an embodiment of a method for delivering any of the stents described herein to the ductus arteriosus from the pulmonary artery to the aorta. FIG 2A illustrates an embodiment of a method for approaching the aorta 200 through the pulmonary artery 210 and the ductus arteriosus 220 with a delivery system 230. As shown in FIG 2B, the delivery system 230 releases a first or distal end section 222 that expands outwardly to the diameter of the lumen of the duct 220 or a portion thereof. In some embodiments, the diameter of the stent is undersized relative to the diameter of the lumen defined by the duct, e.g., due to prostaglandin therapy or the selected size of the stent, as described elsewhere herein. The first end section 222, which may include any of the features illustrated in Figures 3A-4B, 7, 9-14, 17A-17B, 19-25D, 27A-27B of any of the stent embodiments described herein, is at least partially secured to the lumen of the tube and at least partially circumferentially covers the ostium of the aorta 200. As shown in Figure 2C, the constrained stent body 218 is released from the delivery system 230. In some embodiments, the constrained rings are individually released from the distal end of the delivery system and allowed to expand until the entire length of the tube 220 is covered, and the second, or proximal, flanged end is released to expand outward. A second flanged end 216, which may include any one or more of the features illustrated in Figures 3A-4B, 7, 9-14, 17A-17B, 19-25D, and 27A-27B of any of the stents described herein, is at least partially secured to the lumen of the tube 220 and at least partially circumferentially covers the ostium of the pulmonary artery 210, as shown in Figure 2D. Advantageously, this method of delivering any of the stents described herein may be used to increase systemic circulation in a patient, but may also be used to increase pulmonary circulation.

[0115] In some embodiments of FIG. 1A or FIG. 2A, a method of delivering any of the stents described elsewhere herein includes advancing a wire through the vessel, advancing an elongate body (e.g., a microcatheter) over the wire and through the vessel, removing the wire from the lumen of the elongate body, and inserting the stent into the elongate body, e.g., using a delivery sheath. Further, with respect to FIG. 1B and 2B, the method further includes advancing a stent through the lumen of the elongate body, e.g., using any of the pusher wires disclosed herein, and deploying the stent, as shown in more detail in FIG. 1C-1D and FIG. 2C-2D. In some embodiments, deploying includes first deploying a distal end section of the stent into the pulmonary artery (or alternatively the aorta), and then pulling back on the elongate body (microcatheter) and pusher wire to tension the stent and secure it at the mouth of the vessel. Deploying may also include continuing to pull back on the microcatheter to withdraw the stent from the sheath and deploy it. For example, the length and / or flexibility of the stent can be adjusted by pulling back on both the microcatheter and the pusher wire.

[0116] 25A-25D show stent deployment via a microcatheter 2700. The stent continues to be deployed such that the distal end section 2710 of the stent is advanced from the microcatheter 2700 (FIG. 25A), one or more end section struts and / or one or more end section rings 2710 gradually flare as the stent is advanced from the microcatheter (FIGS. 25B-25C), the stent is advanced to deploy the body section 2720 of the stent (FIG. 25D), and finally the proximal end section is deployed. In some embodiments, as the distal end section of the stent is deployed, the delivery system (e.g., catheter 2700 relative to the pusher wire 2730) may be slightly tensioned to align the distal end section with the ostium. In some embodiments, as the body section 2720 of the stent is deployed, the delivery system (e.g., catheter) 2700 may be advanced or retracted to adjust the length of the stent during deployment. Additionally, the distal tip or distal end segment of the catheter may be aligned with the opposing ostium or septum wall of the vessel when the proximal end section of the stent is deployed. The general method illustrated in Figures 25A-25D, as well as the general method illustrated in Figures 1A-1D and 1A-1D and 2A-2D, may be used with any of the stent embodiments described herein.

[0117] Any of the methods described herein may optionally include administering a prostaglandin to the patient to expand the ductus arteriosus. By delivering the prostaglandin to the stent, the patient's risk of vasospasm, a life-threatening condition, is significantly reduced. While the ductus is expanding, the delivery system is configured to constrain and deploy any of the stent embodiments described herein within the ductus arteriosus. In some embodiments, the outer diameter of the ductus arteriosus when expanded with the prostaglandin is in the range of about 20% to about 50%, about 50% to about 100%, about 60% to about 120%, about 75% to about 140%, about 40% to about 140%, about 30% to about 100%, about 80% to about 120%, about 70% to about 110%, about 90% to about 150%, etc., greater than the outer diameter of any of the stents described herein when in an expanded, deployed configuration.

[0118] Any one or more of the foregoing steps may be performed with or without contrast. For example, injection of contrast may occur between the sheath and the microcatheter, through an empty microcatheter, through one or more side holes in the sidewall of the microcatheter, through one or more holes in the hub of the pusher wire, and / or through a gear-shaped hub on the pusher wire (i.e., the hub may include or define one or more cutouts or recessed areas along its circumference or on the outer surface of the hub). The gear shape provides additional space for the contrast to flow. Various features of the delivery system are described in further detail below.

[0119] 26A-26D illustrate a method of deploying a stent in a septal conduit 2630. FIG. 26A illustrates an exemplary heart 2600 having a hypoplastic left ventricle. The heart 2600 includes an aorta 2610, a superior vena cava 2620, an inferior vena cava 2640, a septal defect 2630, a ductus arteriosus 2650, a left ventricle 2660, a right ventricle 2698, a right atrium 2670, and a left atrium 2680. As shown in FIG. 26A-26D, one embodiment of a method of treating a septal defect includes advancing a stent delivery system 2690 into the right atrium 2670 of a patient, as shown in FIG. 26A. Advancing may include accessing the vasculature via the femoral vein or another access point (e.g., the radial vein, the carotid artery, etc.). Advancing may include advancing the stent delivery system 2690 through the inferior vena cava 2640 into the right atrium 2670. As shown in FIG. 26B, the method includes advancing the stent delivery system 2690 across the septum. In some embodiments, advancing the stent delivery system 2690 across the septum includes crossing a foramen ovale, an atrial septal defect, or a septal resection. As shown in FIG. 26C, the method includes deploying a distal end 2692 of a stent from the stent delivery system 2690 into the left atrium 2680. The steps of FIG. 26C may further include loading a stent into a proximal end of the stent delivery system 2690 and advancing the stent through the stent delivery system 2690 until the stent approaches the distal end of the stent delivery system 2690. Additionally or alternatively, the steps of FIG. 26C may include applying tension or force toward the proximal end of the delivery system 2690 as the stent is deployed to secure the distal end 2692 to the septal wall between the right atrium 2670 and the left atrium 2680. As shown in Figure 26D, the method includes advancing a body section 2694 of the stent from a distal end of a stent delivery system 2690 across the septal wall to deploy a proximal end 2696 of the stent into the right atrium 2670. The step shown in Figure 26D may further include anchoring the stent to the septum. Any of the stent embodiments described herein may be used in combination with the methods shown in Figures 26A-26D.For example, the body sections of any of the stents described herein may be lengthened or shortened for application in the treatment of a septal defect. Additionally, although the method of Figures 26A-26D is illustrated in a patient having a hypoplastic left ventricle, one skilled in the art will appreciate that similar devices and associated methods may be used to treat any septal defect.

[0120] Equipment

[0121] Each of the stent designs described herein allows coverage of the most common vessel lengths of about 8 mm to about 28 mm, e.g., stent diameters between about 3 mm to about 5 mm for duct-dependent pulmonary circulation, or about 5 mm to about 10 mm for duct-dependent systemic circulation. Additionally, the various stent designs described herein may be optimized for septal conduits to allow coverage of the septal conduits. For example, the septal device in the body section may have a diameter of about 4 mm to about 5 mm and a length of less than about 8 mm.

[0122] The technical problem that the stent designs described herein attempt to solve is how to make a stent that crimps to a small enough flexible diameter so that it can be delivered through a microcatheter, while at the same time having sufficient radial force to maintain patency of a vessel or lumen. Achieving sufficient radial force in a stent that crimps to a small diameter while still being flexible is difficult because there is limited room for metal in the stent structure. The amount of metal available in the stent is determined by the crimp diameter. Therefore, the length, width, and thickness of the struts, the number of struts per ring (divided by 2 to get the number of crowns per ring), and the number of bridges between adjacent rings as described herein are important in achieving this crimp diameter while still providing sufficient flexibility and radial force during expansion. For example, the ratio of the number of crowns to the number of bridges in the body section is important in achieving sufficient flexibility in tortuous vasculature while maintaining sufficient radial force necessary to maintain a patent vessel or conduit actively closing. In some embodiments, for stent embodiments described herein, the ratio of the number of crowns to the number of bridges in the body section can be from about 6:2 to about 12:8 or from about 6:3 to about 9:3. Further, for example, the number of crowns can be from about 6 crowns to about 12 crowns, such that the number of struts per ring is from about 12 struts to about 24 struts and the number of bridges is from about 3 to about 9. Thus, there is a tight balance between flexibility and deliverability in radial forces.

[0123] Table 1 below shows a qualitative scoring of stent flexibility and deliverability based on various strut, crown, and bridge counts. All struts across all tested embodiments had the same strut thickness, and the angle between adjacent struts in each ring was similar. Strut length in each embodiment was slightly varied to accommodate changes in crown and / or bridge counts. Strut width, strut thickness, and strut length are described with respect to Figures 3A-3E. The data presented in Table 1 suggests that a crown to bridge ratio of about 6:3 to about 9:3 may be important to achieve sufficient radial force to maintain a patent ductus arteriosus or septal conduit while achieving sufficient crimp diameter and flexibility for delivery via a microcatheter.

[0124] [Table 1]

[0125] To add an indication of structural strength to the qualitative flexibility assessment in Table 1, crush testing was performed as a surrogate for radial force. Literature data suggests that stent crush testing correlates well with stent radial force, at least for most stents (Brandt-Wunderlich, C. et al., Support function of self-expanding nitinol stents-Are radial resistive force and crush resistance comparable?, Current Directions in Biomedical Engineering, 2010). Engineering) 2019;5(1)p465-468, the entire contents of which are incorporated herein by reference. The stents were crushed 50% between parallel plates (each stent body section had a resting diameter of 4 mm and was crushed 2 mm) between which each stent was positioned using a HF-5 Digital Push-Pull Gauge Force Gauge HF-5N with a linear fixture (Baoshishan® Force Test Stand Hand Wheel Operated Push-Pull Test Stand Tension Compression Load Tester with Digital Displacement Scale and HJJ-001 Clamp x 2). The results are shown in FIG. 38.

[0126] As shown in FIG. 38, the stent with 8 crown to 8 bridge ratio had the highest strength (e.g., approximately 50 g), while reducing the number of bridges to a ratio of 8 crown to 4 bridges resulted in a slight decrease in strength (e.g., approximately 45 g). The stent with 9 crown to 3 bridge ratio showed a further decrease in strength, but still a significant strength of approximately 29 g. However, while the 8 crown:8 bridge and 8 crown:4 bridge designs exhibited high strength, they each lacked flexibility (see Table 1), making them difficult to deliver and / or position. In contrast, the 9 crown:3 bridge design exhibited a balance between strength and flexibility, improving deliverability and positioning while maintaining sufficient radial strength to keep the duct patent.

[0127] Figures 3A-3E show one embodiment of a stent for the treatment of congenital heart disease. The stent shown in Figures 3A-3E provides a technical solution to the above-mentioned technical problems, as illustrated by various stent design features described below and elsewhere herein.

[0128] 3A illustrates one embodiment of a stent 310 in a 2D crimped configuration. As shown, the stent 310 has a first end section 312a defining a proximal face 308a, a second end section 312b defining a distal face 308b, and a body section 314 between the first end section 312a and the second end section 312b.

[0129] The first end section 312a may include one ring, two or more rings, or multiple rings. As shown in this embodiment, the first end section 312a includes a terminal ring 306a including a plurality of struts 304a each having a length 320L, a penultimate ring 318a including a plurality of struts 304d each having a length 322L, and a penultimate ring 319a including a plurality of struts 304f each having a length 323L. The length 320L of each strut 304a may be substantially similar to the length 322L of each strut 304d and / or the length 323L of each strut 304f. Preferably, the length 320L is greater than the length 322L which is greater than the length 323L such that the strut length increases from the body section 314, toward the first end section 312a, and toward the proximal face 308a. In other embodiments, length 323L is greater than length 322L which is greater than length 320L such that the strut length decreases from body section 314, to first end section 312a, and further toward proximal face 308a. To further reiterate, lengths 322L and 323L may be substantially the same, or lengths 320L and 322L may be substantially the same, or lengths 320L and 323L may be substantially the same. Strut lengths 320L, 322L, and 323L may each be between about 2.5 mm and 4.5 mm. Preferably, length 320L of each strut 304a is between about 1.9 mm and about 2.3 mm, length 322L of each strut 304d is between about 1.6 mm and about 2.0 mm, and length 323L of each strut 304f is between about 1.3 mm and about 1.7 mm. As shown in Figure 3D, proximal surface 308a of first end section 312a (shown in Figure 3A) has a diameter 344 (measured at terminal crown 316a of terminal ring 306a) that is about 110% to about 180%, about 120% to about 170%, about 130% to about 160%, e.g., about 150%, about 155%, or about 160% larger than diameter 342 of body section 314. Proximal surface 308a includes one, more than one, or a plurality of radiopaque markers 336a.Alternatively, the radiopaque marker 336a may be replaced with a connecting element, such as a male or female connector, configured to connect with a complementary feature (e.g., a female or male connector, respectively) on the delivery system. The rings 306a and 318a, as well as the rings 318a and 319a, are connected to each other via one or more bridges 302a. As shown in FIG. 3B, each bridge 302a has a length 304L between about 0.1 mm and about 0.25 mm. There may be from about 3 to about 9 bridges.

[0130] The second end section 312b includes one ring, two or more rings, or a plurality of rings. As shown in this embodiment, the second end section 312b includes a terminal ring 306b including a plurality of struts 304c each having a length 328L, a penultimate ring 318b including a plurality of struts 304e each having a length 326L, and a penultimate ring 319b including a plurality of struts 304g each having a length 325L. The length 328L of each strut 304c may be substantially similar to the length 326L of each strut 304e and / or the length 325L of each strut 304g. Preferably, the length 328L is greater than the length 326L which is greater than the length 325L of each strut 304g, such that the strut length increases from the body section 314 to the second end section 312b and further toward the distal face 308b. In other embodiments, length 325L is greater than length 326L which is greater than length 328L such that the strut length decreases from body section 314 to second end section 312b and further toward distal face 308b. In further variations, lengths 328L and 326L may be substantially the same, or lengths 328L and 325L may be substantially the same, or lengths 326L and 325L may be substantially the same. Strut lengths 326L, 328L, and 325L may each be between about 2.5 mm and about 4.5 mm. Preferably, length 328L of each strut 304c is between about 1.9 mm and about 2.3 mm, length 326L of each strut 304e is between about 1.6 mm and about 2.0 mm, and length 325L of each strut 304g is between about 1.3 mm and about 1.7 mm. As shown in Figure 3D, distal surface 308b of second end section 312b (shown in Figure 3A) has a diameter 346 (measured at terminal crown 316b of terminal ring 306b) that is about 110% to about 180%, about 120% to about 170%, about 130% to about 160%, such as about 150%, about 155%, or about 160% larger than diameter 342 of body section 314. Distal surface 308b includes one, more than one, or a plurality of radiopaque markers 336b.Alternatively, the radiopaque marker 336b may be replaced with a connecting element, such as a male or female connector, configured to connect with a complementary feature (e.g., a female or male connector, respectively) on the delivery system. Rings 306b and 318b, as well as rings 318b and 319b, are connected to one another via one or more bridges 302c. As shown in FIG. 3B, each bridge 302c has a length 304L of about 0.1 mm to about 0.25 mm. There may be about 3 to about 9 bridges between each pair of adjacent rings.

[0131] The body section 314 includes a plurality of rings 334, each including a plurality of struts 304b. The body section 314 may include one ring or more than one ring (e.g., in the case of a septal defect embodiment), or two or more rings or multiple rings (e.g., in the case of a patent ductus arteriosus embodiment). For example, there may be about one ring, about two to about six rings, or about three to about ten rings. The struts 304b of the body section 314 each have a length 324L. As shown in FIG. 3A, in any of the stent embodiments described herein, the length 324L of each of the struts 304b may be about 0.6 mm to about 1.6 mm, preferably about 0.8 mm to about 1.4 mm. The rings 334 of the body section 314 may be connected via a plurality of bridges 302b, for example, about three to about nine bridges 302b between each pair of adjacent rings. As shown in Figures 3B-3C, for any of the stents described herein, each bridge 302a, 302c, 302b has a length 304L, 338L, respectively, ranging from about 0.1 mm to about 0.25 mm.

[0132] As shown in Figures 3B-3C, for any of the stent embodiments described herein, struts 304a, 304b, 304c can each have a width 324W of about 0.08 mm to about 0.1 mm. As shown in Figures 3B-3C, for any of the stent embodiments described herein, struts 304a, 304b, 304c can each have a thickness of about 0.09 mm to about 1.1 mm.

[0133] Struts 304a, 304c in first end section 312 and second end section 312b, respectively, are longer than struts 304b in body section 314 to accommodate greater expansion while maintaining the angle between adjacent struts in each ring substantially constant or equal. For example, as shown in FIG. 3D, angle 332 of strut 304a relative to longitudinal axis 330 is between about 50 degrees and about 70 degrees, or between about 60 degrees and about 70 degrees, preferably about 65 degrees.

[0134] In some embodiments, the stents described herein have an open cell design such that the distance between adjacent rings in the first section, the body section, and / or the second section is from about 0.1 mm to about 0.2 mm, or from about 0.12 mm to about 0.16 mm.

[0135] As shown in FIG. 3A, the diameter 340 of the stent 310 in the crimped configuration is about 0.5 mm to about 0.75 mm, preferably about 0.60 mm to about 0.70 mm. FIG. D shows the stent of FIG. 3A in an expanded configuration, for example after deployment from a microcatheter. The diameter 342 of the body section 314 of the expanded stent 300 is about 3 mm to about 10 mm, about 3 mm to about 4.5 mm, about 5 mm to about 9 mm, about 6 mm to about 10 mm, etc., depending on the diameter of the target lumen. For example, the diameter of at least a portion of the lumen defined by the duct is about 4 mm to about 8 mm, and the outer diameter of the body section of the stent is about 3 mm to about 4.5 mm. Further, for example, the diameter of at least a portion of the lumen defined by the ductus arteriosus is about 5 mm to about 10 mm, and the outer diameter of the body section of the stent is about 5 mm to about 9 mm. In yet another example, at least a portion of the lumen defined by the tube has a diameter of about 5 mm to about 9 mm, and the body section of the stent has an outer diameter of about 6 mm to about 10 mm.

[0136] In the expanded configuration, the stent 300 has a radial force of greater than about 0.20 N / mm, between about 0.20 N / mm and about 0.35 N / mm, between about 0.25 N / mm and about 0.31 N / mm, between about 0.25 N / mm and about 0.27 N / mm, or between about 0.30 N / mm and about 0.31 N / mm at a compression of about 1 mm. For example, when the stent is compressed to a diameter of about 4 mm to about 3 mm, the radial force is about 0.25 N / mm to about 0.27 N / mm. In another example, when the stent is compressed from a diameter of about 4 mm to about 2 mm, the radial force is about 0.30 N / mm to about 0.31 N / mm.

[0137] In some embodiments, the stents shown in Figures 3A-3E are configured to be secured within a blood vessel having a diameter that is about 20% to about 140%, about 40% to about 140%, about 20% to about 100%, etc., larger than the diameter of the body section of the stent.

[0138] 3A-3D, the stent 300 includes an open cell design such that the stent 300 does not kink at a radius of curvature of about 4 mm or more, or at a radius of curvature of about 2 mm or more. For example, the stent 300 may kink at a radius of curvature of about 2 mm or less.

[0139] FIG. 3E illustrates an example of various parameters of a stent 300b for a particular vessel having at least certain dimensions. One skilled in the art will appreciate that dimensions may need to be scaled up or down depending on the size of the target vessel. The stent 300b in the expanded configuration has a body section 314 having a length 348 of about 6 mm to about 12 mm, preferably about 8 mm to about 10 mm, depending on the length specification. The stent 300b has a first end section 312a and a second end section 312b, each end having a length 350 of about 3 mm to about 6 mm, preferably about 4 mm to about 5 mm. The diameter 342 of the body section 314 is about 3 mm to about 6 mm, preferably about 3.5 mm to about 4.5 mm, depending on the target vessel specification. The proximal face diameter 344 or distal face diameter 436 is about 6 mm to about 8 mm, preferably about 6.5 mm to about 7.5 mm, depending on the target vessel specification.

[0140] 4A-4B show another embodiment of a stent 400 having a proximal face 410 at a first end section 402 that secures the stent 400 at a proximal end and a distal face 420 at a second end section 406 that secures the stent 400 at a distal end, thus ensuring end-to-end coverage of a vessel regardless of the length of the stent. The first and second end sections 402, 406 may be configured to slightly compress the vessel so that the entire vessel is covered by the stent. Additionally, as shown in FIG. 4B, the anchoring mechanism of the stent 400 includes adjacent end struts 426 joined at terminal crowns 424 on the proximal and / or distal faces. The adjacent end struts 426 joined at terminal crowns 424 form an angle 425 of about 75 degrees to about 110 degrees with respect to a longitudinal axis 422 of the stent 400.

[0141] 7 and 9, which illustrate various embodiments of stents having first and / or second end sections defining proximal or distal faces, respectively, and including adjacent end struts joined at terminal crowns that are angled relative to the longitudinal axis of the stent body. As shown in Figures 4A-4B, 7, 9, 11A, and 19-24, adjacent end struts joined at terminal crowns may take on a variety of shapes and configurations.

[0142] FIG. 7 illustrates a petal-shaped end section or flange forming the proximal or distal face of the stent. For example, the petal-shaped flange 700 may include first angled struts 702 and second angled struts 704 joined by a crown 706. The angle 708 between adjacent struts 702, 704 may be between about 15 degrees and about 50 degrees, giving the flange a petal-like appearance and an open cell structure. The end struts 702, 704 joined by the end crown 706 may be angled relative to the longitudinal axis of the body section of the stent. For example, the angle may be between about 50 degrees and about 115 degrees, as shown and described elsewhere herein. In contrast to the flange 700 illustrated in FIG. 7, the stent illustrated in FIG. 9 includes one or more star-shaped flanges 900 at the distal and / or proximal ends to facilitate fixation in a test lumen 910. The struts 904 are joined to adjacent struts 902 along at least a portion of the adjacent struts 902, 904 and at the crowns 906 such that the angle at the end regions 912 between adjacent struts 902, 904 is less than about 5 degrees.

[0143] Reference is now made to Figure 10, which is a magnified, two-dimensional view of a portion of a stent 1000 according to one embodiment. Section 1010 is either a first end section or a second end section and includes a number of terminal struts 1012a, 1012b, ... 1012n forming terminal rings. Adjacent terminal struts 1012a, 1012b are joined at terminal crowns 1018. Body section 1010 also includes a number of struts 1014 arranged in a number of rings. Terminal struts 1012a, 1012b have a length 1020 that is greater than a length 1022 of struts 1014 in body section 1010. For example, length 1020 of strut 1012a or 1012b may be two to about four times greater than length 1022 of strut 1014. For example, the length 1020 of strut 1012a or 1012b may be from about 2 mm to about 6 mm, while the length 1022 of strut 1014 may be from about 0.5 mm to about 2 mm. Adjacent rings may be connected by bridges 1016. For example, the bridges may be angled relative to the longitudinal axis of the stent, at least in the compressed configuration.

[0144] In some embodiments, the first and / or second end sections may be configured to anchor the stent in the middle of a vessel, as opposed to the end of the vessel, the mouth of the vessel, or the septal wall. Alternatively, the stent may be flared or flanged at only one end, such as the first end section or the second end section, as shown in FIG. 11A. For example, in FIG. 11A, compare the angle 1102 of the terminal crown 1106 at the first end section 1100 and the angle 1104 of the terminal crown 1108 at the second end section 1110, both relative to the longitudinal axis 1120 of the stent 1150. The angle 1102 of the first end section 1100 may be about 45 degrees to about 75 degrees, while the angle 1104 of the second end section 1110 may be about 15 degrees to about 45 degrees, such that the first end section 1100 is configured to anchor the stent at the ostium of the vessel, while the second end section 1110 is configured to anchor the stent at the midsection of the vessel. The angles between adjacent struts in each end ring of the first and second end sections may be substantially constant or similar, while the angle of the end crowns relative to the longitudinal axis is adjusted for either end vessel anchoring or mid-vessel anchoring. As shown in Figures 11B-11C, the end rings, crowns, struts, etc. can still anchor the stent in place while allowing the length (measured at the body section and the second end section) to be adjusted. Figures 11B-11C show adjustment of the stent length from about 13 mm (Figure 11B) to about 16 mm (Figure 11C). As shown in Figures 11B-11C, the stent length measurements focus on the functional length (not including the flare extending from the vessel) because the anchoring struts at the mid-vessel section become part of the body section and are therefore functional length. Figure 23, described in more detail below, shows another embodiment of a stent that may be configured to be anchored at a mid-vessel.

[0145] 14-16 and 18 show various crown and bridge configurations of the end and / or body sections of various stent embodiments in 2D in their as-cut, pre-expanded configurations. FIG. 14 shows one embodiment of a crown-bridge configuration at the end section 1420 (proximal or distal) of a stent. Adjacent end struts 1406a, 1406b are joined by internal crowns 1400, and adjacent penultimate struts 1408a, 1408b are joined by crowns 1402. The internal crowns 1400 and crowns 1402 are connected via bridges 1404. Stated another way, all internal crowns 1400 (as opposed to external or face crowns on the proximal or distal faces) are connected to the crowns of the penultimate struts 1408a, 1408b via bridges 1404. In the crimped or unexpanded configuration, the bridge 1404 between the end 1406 and the penultimate strut 1408 is substantially parallel to the longitudinal axis 1403 of the end section 1420. In this embodiment, the end section and the penultimate strut are about 2 mm to about 2.5 mm long, preferably about 2.25 mm long. In some embodiments, the crown-bridge configuration of FIG. 14 is configured to allow proximal and / or distal expansion (symmetric or asymmetric) to a diameter of about 5 mm to about 6 mm, preferably about 5.5 mm.

[0146] Another embodiment is shown in Figure 15. The stent of Figure 15 has nine crowns per row and three bridges per row. The bridges 1504 are angled relative to the longitudinal axis 1520 of the section 1500 (main body section or end section). For example, terminal strut 1506a is joined to adjacent terminal strut 1506b at an internal crown 1510, penultimate strut 1508a is joined to adjacent strut 1508b at a crown 1502. The internal crown 1510 is offset relative to the crowns 1502 (in a compressed, 2D, or other non-expanded configuration) such that the bridges 1504 are angled relative to the longitudinal axis of the device. In some embodiments, this structure increases flexibility.

[0147] FIG. 16 shows another embodiment of the connection regions of the stent. In this embodiment, the number of crowns in the body region is constant, but the number of bridges in each connection region alternates between more and fewer. For example, connection region 1620 includes four bridges 1610a between adjacent rings 1602, 1604, connection region 1640 includes two bridges 1606 between adjacent rings 1604, 1608, and connection region 1630 includes four bridges 1610b between adjacent rings 1608, 1612. The number of bridges alternates in each connection region relative to the number of connection regions in the adjacent connection regions. By alternating the number of bridges between the rings, each bridge is configured to be substantially parallel to the horizontal or longitudinal axis 1650 of the stent. In some embodiments, the stent of FIG. 14 also alternates between rings with more and fewer crowns and connection regions with more and fewer bridges. Alternating the number of crowns per ring and / or the number of bridges between rings can improve strength while maintaining sufficient flexibility (see, for example, Table 1).

[0148] FIG. 39 shows additional crush test data performed with similar parameters as above for stents with such alternating crown and / or bridge count configurations. Compared to the strength of a 9 crown:3 bridge stent (shown in FIGS. 38-39), a stent with alternating 8 crowns and 12 crowns with 4 bridges between each ring has increased strength (e.g., about 37 g) and is very flexible (see Table 1). A stent with alternating 6 crowns and 9 crowns with 3 bridges between each ring has an even greater increase in strength (e.g., about 50 g) and a slight decrease in flexibility (see Table 1) compared to an 8-12 crown:4 bridge design. In some embodiments, alternating crown and / or bridge counts at least slightly decrease flexibility while simultaneously increasing strength. Such designs can be a good balance between flexibility, deliverability, and strength.

[0149] 18 shows another embodiment of the connection region of the stent. Adjacent struts 1850 are joined with curved or looped crowns 1860 such that the crowns 1860 are connected to adjacent rings via bridges 1820 (e.g., parallel or angled relative to the longitudinal axis of the stent). In another embodiment, adjacent struts 1840 are joined with crowns 1810 having a substantially flat or slightly concave top. The concave or flat crowns 1810 may or may not be connected to adjacent rings via bridges. In some embodiments, this design may provide more pushability when advancing, e.g., ring 1804 may push against ring 802 or ring 802 may push against ring 1804 during delivery.

[0150] 19-21 are various schematic diagrams of end sections of a stent. For example, the configurations shown in FIGS. 19-21 may be part of a first end section defining a proximal surface and / or a second end section defining a distal surface. The configurations shown in FIGS. 19-21 may be applied to any of the stent embodiments described elsewhere herein. In one embodiment, as shown in FIG. 19, the end sections of the stent may be at an angle (in an expanded configuration) to the longitudinal axis of the stent. The angle 1920 may be from about 80 degrees to about 100 degrees, or substantially or about 90 degrees, such that the terminal crowns 1900 of the terminal struts 1910 are substantially perpendicular to the longitudinal axis 1950 of the stent. In another embodiment, as shown in Figure 20, one or more end struts 2000 of the stent may be gradually flared, for example along an arcuate path 2020, with the elongated section of the strut 2000 forming an angle 2010 of about 30 degrees to about 60 degrees relative to the longitudinal axis 2050 of the stent. In another embodiment, as shown in Figure 21, one or more end struts 2100 of the stent may be gradually flared, with the elongated section forming an angle 2110 of about 70 degrees to about 90 degrees relative to the longitudinal axis 2150 of the stent. Each of the embodiments shown in Figures 19-21 have end struts that are longer than the struts in the main body section of the stent.

[0151] 22, the body section 2340 of the stent 2300 may include an expanded lumen 2310 in a region of the body section 2340. For example, this region may be substantially centrally located or may be closer to the distal end 2320 or the proximal end 2330 of the stent 2300. The bulges or protrusions 2310 may be substantially circumferentially disposed, focal, or otherwise shaped.

[0152] In yet another embodiment, as shown in the schematic diagram of FIG. 23, one or more end struts 2410 may be folded back toward the proximal end 2422 of the stent 2400 such that the angle 2420 of the strut 2410 relative to the longitudinal axis 2430 is between about 120 degrees and about 170 degrees.

[0153] 24 illustrates another embodiment of an end section 2550 of a stent 2500 having a cuff shape. For example, the end section 2550 may include a parallel section 2540 relative to a longitudinal axis 2510 of the body section 2560 to give it a cuff-like appearance. Further illustratively, the distal end 2550 of the stent 2500 has a diameter 2520 that is larger (e.g., about 5% to about 50% larger) than a diameter 2530 of the body section 2560 of the stent 2500.

[0154] In some embodiments, shortened versions of any of the stent designs described herein may also be used to maintain communication between two chambers of the heart, such as the left and right atria, or the inferior venous baffle or conduit and the right atrium (e.g., Fontan perforation). For example, this may maintain patency of a septal resection or foramen ovale. In some embodiments, as shown in FIG. 27A, a shortened stent 2800 may include one or two rings 2810 (e.g., terminal rings substantially perpendicular to the longitudinal axis of the stent) in the body section with flared end sections 2820, 2830 on one or both of the first and second ends. This design may also be delivered through a microcatheter using any of the pusher wire designs described herein. FIG. 27B shows a side view of the stent of FIG. 27A for use as a septal conduit. 27B, septal conduit 2900 includes a body section 2940 having a ring 2910 (although body sections having more than one ring or multiple rings are contemplated), a first end section 2950 defining a first side 2970, and a second end section 2960 defining a second side 2980. First side 2970 may include ring 2930 and second side 2980 may include ring 2920, although end sections with multiple rings are contemplated herein. Indeed, any of the stent embodiments described herein may be adapted for use in treating a septal conduit defect.

[0155] In some embodiments, any of the stents described herein may include anti-thrombotic, anti-restenotic surface treatment(s) or coating(s), anti-proliferative coatings, friction reducing coatings, or any other coating(s) known in the art. Additionally, any of the stents described herein may be configured as a drug-eluting stent.

[0156] In any of the stent embodiments described herein, two or more rings of the body section, the first end section, and / or the second end section may be anchored together to form a segment. Anchoring adjacent rings together may prevent the rings from reversing orientation during deployment and scaling at a bend, where two unconnected stent rings or segments would pivot like protruding scales at a bend, creating a potential kink point. For example, an electrochemical reaction may be used to separate a connecting section between two adjacent sections. In some embodiments, a hook system may be used to connect adjacent segments and the deployment catheter may be twisted to disengage the segments. Additionally, in some embodiments, a segment may be nested within an adjacent ring such that the next segment may be rotated to disengage the segment. In embodiments that rely on such rotation, rotation may be desired only when the segment is disengaged so that the stent can be advanced through tortuous anatomy without disengaging (or disengaged only when properly positioned). Thus, one or more portions of each segment may not be connected to an adjacent segment to limit rotation other than when disengaged.

[0157] 12-13 show various examples of locking mechanisms. FIG. 12 shows a lollipop or paddle structure that can be used to lock adjacent segments of a stent together or to lock a stent to a delivery system for deployment. For example, a first side 1202 of one segment or stent has a female mating portion 1200 and a second side 1204 of an adjacent segment or delivery system has a male mating portion 1210 (e.g., a paddle or lollipop). In another embodiment, as shown in FIG. 13, each segment 1300, 1310 can include a bias cut pattern for nesting with adjacent segments or locking the stent to a delivery system. Furthermore, one skilled in the art will appreciate that a stent can include a male connector 1210 while a delivery system includes a female connector 1200.

[0158] In some embodiments, the stents described herein (1) are manufacturable in diameters from about 3 mm to about 5 mm in 0.5 mm increments, (2) are deliverable through a 4F sheath or smaller, and (3) have at least an average radial force ranging from about 0.20 N / mm at 1 mm compression to about 0.3 N / mm at 2 mm compression. In some embodiments, the stents may additionally or alternatively completely cover a majority of the vascular anatomy (e.g., 4 out of 6 vessels in a development model with vessel lengths ranging from about 8 mm to about 28 mm) without extending more than about 2 mm to about 3 mm into either the aorta or pulmonary artery.

[0159] Delivery System

[0160] Any of the stents described herein may be delivered via a microcatheter-based delivery system. A typical delivery system is shown in FIG. 28 and includes a microcatheter 2840 and a pusher wire 2850 configured to deliver a stent 2860. Any of the delivery systems described herein may be smaller, more flexible, and less traumatic to the vessel or chamber than sheath or rigid balloon expandable systems. For example, interventionists claim that a 2.7F microcatheter will traverse 100% of the vessel anatomy it encounters, while less flexible balloon delivery systems are often unable to navigate the vessel due to their stiffness.

[0161] In some embodiments, the microcatheter-based delivery system may use laser cut hypotube technology that allows for greater flexibility with thinner walls, seamless transition zones, and lower kink radius than standard braided configurations. The microcatheter-based delivery system described herein (1) has an outer diameter of approximately 2.7F, allowing for angiographic contrast flow during stent placement through the sheath while fitting through a 3.3F sheath with reduced crossing profile compared to 3.3F or 4F sheaths or balloon expandable coronary stents, minimizing iatrogenic vessel injury, (2) allows access from any of the femoral, carotid, or axillary arteries without excessive length for ease of use in pediatric patients, as access to the vessel from these vessels may be required to obtain the required trajectory, and (3) allows existing 0.014" guidewires to follow the ductus arteriosus through two or more full 360 degree turns (e.g., type III ductal tortuosity index, as shown in FIG. 5C).

[0162] In some embodiments, the stent and delivery system are uniquely designed for neonatal ductus arteriosus stenting, overcoming the anatomical challenges of small, tortuous vessels prone to spasm while allowing for placement of an appropriately sized stent throughout the vessel without protruding into surrounding vessels.

[0163] FIG. 29 shows a schematic of various anatomical considerations in the design of a stent and delivery system. For example, a microcatheter delivery system moving through an aorta 3050 to a vessel 3060 may be segmented into multiple zones, each having its own bend radius, length, and durometer, as shown in FIG. 29. As shown in FIG. 29, when approaching the vessel 3060 from the aorta 3050, a catheter zone 3010 is configured to advance through the descending femoral artery 3000 to have a bend radius of about 7 mm to about 8 mm, a length of about 52 cm to about 59 cm, and a durometer of about 40 to about 90 Shore A. A catheter zone 3020 is further configured to advance through the femoral artery 3000 to have a bend radius of about 4 mm to about 5 mm, a length of about 4 cm to about 6 cm, and a durometer of about 40 to about 90 Shore A. The catheter zone 3030 is then configured to advance through the femoral artery 3000 proximate the aortic arch 3050, with a bend radius of about 1 mm to about 4 mm and a durometer of about 20 to about 40 Shore A. The catheter zone 3040 is configured to navigate the aortic arch 3050, with a bend radius of about 2.5 mm, a length of about 0.5 cm to about 1 cm, and a durometer of about 20 to about 40 Shore A. The catheter is further configured to navigate the lower portion of the aortic arch 3050 and enter the ductus arteriosus 3060, which has a length of about 8 mm to about 28 mm. The catheter distal tip 3070 deploys the stent 3090. While FIG. 29 illustrates an approach to the vessel from the aorta, one skilled in the art will appreciate that an approach to the vessel from the pulmonary artery 3080 is also possible, both approaches being shown above in FIGS. 1A-1D and 2A-2D. The stent and / or delivery catheter may similarly be manufactured to have flexibility properties that suit the specific requirements of each zone.

[0164] An embodiment of the stent delivery system may use a microcatheter made with laser cut hypotube technology that allows for greater flexibility with thinner walls, seamless transition zones, and lower kink radius than standard braided configurations. Additionally, a microcatheter delivery system with braided or coiled reinforcement and variable durometer outer polymer jacket and / or multiple transition zones formed by changes in the coil pitch or braid per inch cross (PIC) may be used to deliver the stent. The delivery system may be configured to fit through a 4F sheath to minimize iatrogenic vessel injury. In some embodiments, the delivery system allows access through any of the femoral, carotid, or axillary arteries, as it may be necessary to access the vessel from these vessels to obtain the required trajectory. The delivery system may be configured to follow over an existing guidewire through a vessel that rotates 360 degrees or more (Type III vessel tortuosity index, FIG. 5C). As described above, the stent and delivery system are uniquely designed for neonatal vascular stenting, overcoming the anatomical challenges of small and tortuous vessels while allowing for the placement of an appropriately sized stent throughout the vessel without protruding into the surrounding vessels.

[0165] In some embodiments, any of the delivery systems described herein may be configured to deploy a variety of devices, including, but not limited to, a stent (any of the embodiments described herein), a flow restrictor, an occluder, a septal conduit device (FIGS. 27A-27B), or an implant. An array of such devices may be referred to herein as an implant.

[0166] In some embodiments, the implant may be disengaged from the delivery system by applying a voltage to release a connector between the implant and the delivery system, by using one or more sugar moieties that dissolve to separate the implant from the delivery system, by using a softer hub (e.g., silicone) to compress the end of the implant to hold it in place, by having a lock and key mechanism via a marker on the implant and a hub on the delivery system (e.g., FIG. 31), by having a lock and key mechanism between adjacent implant segments such that each implant crest to valley is reversibly connected to keep the segments nested, by having a torsion mechanism to adjust the length between the segments (e.g., with struts in between that are intended to twist), and / or by having a design that promotes unidirectional deployment (e.g., by allowing subsequent implant segments to have larger diameters as the implant advances toward the aorta (or pulmonary artery, depending on the approach), also aiding in the deployment of one segment at a time by nesting). In some embodiments of a torsion mechanism, the torsion mechanism may be reserved for proximal end deployment on the aortic side (or pulmonary artery, depending on the approach).

[0167] 30-37 show various pusher wire embodiments that may be used or adapted for use with any delivery sheath and microcatheter known in the art. FIG. 30 shows a pusher wire 3100 with a first hub 3110 and a second hub 3140 that may be used to manipulate and / or deliver any of the stents described herein within a catheter delivery system. While the embodiment of FIG. 30 is shown with two hubs, one skilled in the art will understand that this embodiment may also function with a single hub near the proximal end of the pusher wire. The outer diameter of the hub 3110 may be substantially similar to the outer diameter of the microcatheter. The proximal end 3110a of the hub 3110 tapers toward the proximal end 3150 of the pusher wire 3100, and the distal end 3140a of the hub 3140 tapers toward the distal end 3160 of the pusher wire 3100. Alternatively, as shown in Figure 36, the first and second hubs 3710, 3740 of the pusher wire 3700 may each have a substantially uniform or consistent outer diameter or circumference (e.g., may not be tapered). Returning to Figure 30, the implant may be disposed between the hubs 3140, 3110 at the implant receiving section 3120 (shown in Figure 36 as implant receiving section 3720 between the hubs 3710, 3740). As shown in Figures 30 and 36, the distal ends 3130, 3730 of the pusher wires 3100, 3700 may each include a soft or flexible segment of leading wire that extends approximately 5 cm beyond the distal ends 3130, 3770 of the distal hubs 3140, 3740, respectively. The implant section 3120 may comprise a soft polymer (e.g., about 25D to about 35D durometer polymer or silicone) having a diameter approximately equal to the inner diameter of an implant (e.g., a crimped stent) positioned thereover. The implant section 3120 may be configured to engage the implant and help control the positioning of the implant during deployment. In some embodiments, the diameter 3180 of the distal hub 3140 is substantially equal to or similar to the inner diameter of a crimped stent located within the microcatheter and beneath the stent.The distal hub 3140 may engage one or more features on the distal end of the stent, such as a radiopaque marker, to allow the stent to be under tension within the microcatheter or to stretch the stent during deployment.

[0168] 31-32 show another embodiment of a pusher wire. As shown in FIG. 31, the pusher wire 3200 includes a proximal end 3240, a distal end 3230, and a hub 3210 that is used to push a stent within a microcatheter delivery system. The hub 3210 may be approximately equal to or comparable to the outer diameter of the microcatheter. As shown in FIGS. 31-32, the hub 3210 defines one or more grooves or cutouts 3220 configured to reversibly mate with one or more features located at the proximal end of an implant. Features of the hub 3210 are configured to control the deployment of the implant and optionally the extension or positioning of the implant. The distal end 3230 of the pusher wire 3200 may include a soft or flexible segment of a leading wire beyond the distal end 3250 of the hub 3210, as described above.

[0169] FIG. 32 and FIGS. 17A-17B show various close-up views of the embodiment of FIG. 31 and the interaction between the pusher wire and the stent. As shown in FIGS. 17A-17B and similar to FIG. 12, the proximal end 1700 of the stent may include a delivery system connector 1710 (e.g., a male connector, paddle, lollipop, etc.). For example, adjacent struts 1712, 1714 may be joined at an external crown 1716 that is attached to the delivery system connector 1710. The delivery system connector 1710 is configured to be coupled to a complementary connector 1720 (shown in FIG. 17B) to allow for elongation or expansion of the stent during deployment, for example as part of the hub of the delivery system. Although a male connector is shown on the stent and a female connector on the delivery system, one of ordinary skill in the art will appreciate that a female connector may be on the stent and a male connector on the delivery system. The length of the male portion (of the delivery system connector 1710) is about 1.0 mm to about 2 mm, preferably about 1.5 mm.

[0170] FIG. 32 shows a pusher wire 3300 engaged with a stent 3310. The pusher wire 3300 includes a hub 3320 that is coupled to the stent 3310 at a hub-stent interface 3330. As shown in this embodiment, the stent 3310 includes a proximal male connector 3340 that is complementary to the female connector 3350 of the hub 3320. The pusher wire 3300 may optionally include a second hub 3360 configured to be disposed under the stent 3310 disposed on the pusher wire 3300 to control the release and / or extension of the stent. The distal end 3370 of the pusher wire 3300 may be radiopaque and may include a polymer jacket and / or a hydrophilic coating. The proximal end 3380 of the pusher wire 3300 may include a variable stiffness core wire including, for example, Nitinol and / or stainless steel with a polymer jacket.

[0171] FIG. 33 shows a pusher wire 3400 with two hubs 3410, 3440 used to push a stent through a delivery system. In some embodiments, one or both hubs 3410, 3440 are approximately the same as the outer diameter of the microcatheter. An implant is configured to be disposed between the hubs 3410, 3440 at the implant section 3420. The implant section 3420 may include or be formed of a soft polymer that is approximately the same as the inner diameter of the crimped stent. The implant section 3420 may be configured to engage the implant to facilitate controlling the position of the implant during deployment. One or both of the hubs 3410, 3440 may define one or more openings 3430 to allow contrast or other injectate to pass through the pusher wire 3400 during delivery.

[0172] 34 shows a pusher wire 3500 with one or more hubs 3510 (e.g., a second hub may be disposed distal to the hub 3510) and an implant section 3520, as described elsewhere herein, but in this embodiment, the hub 3510 defines one or more recesses, grooves, slits, or slots 3530 to allow contrast media or other injectates to pass through the pusher wire 3500 and implant during delivery.

[0173] Figure 37 shows another embodiment of a pusher wire 3800 that is similar to the embodiment of Figure 30, except that in the embodiment of Figure 37, the tapered sections 3810a, 3830a of one or both of the hubs 3810, 3830, respectively, define one or more openings 3820 to allow contrast or other injectate to pass through the pusher wire 3800 and implant during delivery. Any of the hub embodiments described herein may have one or more features or define one or more openings or slits to allow contrast or other injectate to pass through.

[0174] 35 shows a pusher wire 3600 with a distal end segment 3610. The distal end segment 3610 may include a flat ribbon tip, a polymer tip, or a coil to create an atraumatic, flexible tip. In some embodiments, the distal end segment 3610 extends beyond the tip of the stent during delivery to allow the pusher wire 3600 to remain anchored within the branch pulmonary artery during stent delivery and maintain wire position through the vessel. The distal end segment 3610 of the pusher wire 3600 may also have a Nitinol shape-set expanding element that helps secure the pusher wire 3600 in place.

[0175] In this specification, when a feature or element is referred to as being "on" another feature or element, it may be directly on the other feature or element, or there may be intervening features and / or elements present. In contrast, when a feature or element is referred to as being "directly on" another feature or element, there are no intervening features or elements present. Also, when a feature or element is referred to as being "connected," "attached," or "coupled" to another feature or element, it will be understood that it may be directly connected, attached, or coupled to the other feature or element, or there may be intervening features or elements present. In contrast, when a feature or element is referred to as being "directly connected," "directly attached," or "directly coupled" to another feature or element, there are no intervening features or elements present. Although described or illustrated with respect to one embodiment, the features and elements so described or illustrated may be applicable to other embodiments. Also, those skilled in the art will understand that a reference to a structure or feature that is located "adjacent" to another feature may have overlapping or underlying portions of the adjacent feature.

[0176] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present invention. For example, as used herein, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly indicates otherwise. Furthermore, as used herein, it will be understood that the terms "comprises" and / or "comprising" specify the presence of stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as " / ."

[0177] Spatially relative terms such as "under," "below," "lower," "over," "upper," and the like may be used herein to describe the relationship of one element or feature to another element(s) or feature(s) as depicted in the figures for ease of description. It will be understood that the spatially relative terms are intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, an element described as "under" or "beneath" the other element or feature would be oriented "over" the other element or feature. Thus, the exemplary term "below" may encompass both an orientation above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein will be interpreted accordingly. Similarly, terms such as "upwardly," "downwardly," "vertically," "horizontally," and the like are used herein for descriptive purposes only, unless specifically indicated otherwise.

[0178] In this specification, the terms "first" and "second" may be used to describe various features / elements (including steps), but these features / elements should not be limited by these terms unless the context dictates otherwise. These terms may be used to distinguish one feature / element from another. Thus, a first feature / element described below may be referred to as a second feature / element, and similarly, a second feature / element described below may be referred to as a first feature / element, without departing from the teachings of the present invention.

[0179] Throughout this specification and the claims that follow, unless the context otherwise requires, the word "comprise" and variations such as "comprises" and "comprising" mean that various components may be used together in methods and articles (e.g., compositions and apparatuses, including apparatus and methods). For example, the term "comprising" is understood to mean the inclusion of any described element or step, but not the exclusion of any other elements or steps.

[0180] As used in this specification and claims, including as used in the examples, unless expressly specified otherwise, all numerical values ​​may be read as being preceded by the word "about" or "approximately", even if the term is not expressly indicated. The phrase "about" or "approximately" may be used in describing a size and / or location to indicate that the stated value and / or location is within a reasonable expected range of value and / or location. For example, a numerical value may have a value of ±0.1% of the stated value (or range of values), ±1% of the stated value (or range of values), ±2% of the stated value (or range of values), ±5% of the stated value (or range of values), ±10% of the stated value (or range of values), etc. Additionally, a numerical value provided herein should be understood to include about that value or approximately that value, unless the context indicates otherwise. For example, if the value "10" is disclosed, then "about 10" is also disclosed. Any numerical ranges mentioned herein are intended to include all subranges subsumed therein. Also, as would be well understood by one of ordinary skill in the art, when a value is disclosed, it is understood that "less than or equal to that value," "greater than or equal to that value," and possible ranges between values ​​are also disclosed. For example, when a value "X" is disclosed, not only "less than or equal to X" but also "greater than or equal to X" (e.g., X is a numerical value) are disclosed. It is also understood that data is provided throughout this application in many different formats, and that this data represents endpoints and starting points, and ranges for any combination of the data points. For example, when a specific data point "10" and a specific data point "15" are disclosed, it is understood that greater than, greater than, less than, less than, or equal to "10" and "15," as well as between "10" and "15," are also considered to be disclosed. It is also understood that each unit between two particular units is also disclosed. For example, when 10 and 15 are disclosed, 11, 12, 13, and 14 are also disclosed.

[0181] Although various exemplary embodiments have been described above, any of a number of modifications may be made to the various embodiments without departing from the scope of the invention as set forth in the claims. For example, the order in which the various described method steps are performed may often be changed in alternative embodiments, and in other alternative embodiments, one or more method steps may be omitted entirely. Any feature of the various apparatus and system embodiments may be included in some embodiments and not included in other embodiments. Thus, the foregoing description has been provided primarily for illustrative purposes and should not be construed as limiting the scope of the invention as set forth in the claims.

[0182] The examples and illustrations contained herein are illustrative and not limiting, showing specific embodiments in which the subject matter may be practiced. As mentioned, other embodiments may be utilized and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of the present disclosure. Such embodiments of the present subject matter may be referred to herein, individually or collectively, by the term "invention" for convenience only, and there is no intention to spontaneously limit the scope of the present application to any single invention or inventive concept when multiple inventions are actually disclosed. Thus, although specific embodiments have been illustrated and described herein, any arrangement designed to achieve the same purpose may be substituted for the specific embodiment illustrated. The present disclosure is intended to cover any adaptations or variations of the various embodiments. Combinations of the above embodiments, as well as other embodiments not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description. [Explanation of symbols]

[0183] 100 Aorta 116 Distal Section 118 Stent body 120, 220 ductus arteriosus 222 End Section 130, 230 Delivery systems 304, 702, 704 Strut 306a End Ring 308a Proximal aspect 308b Distal surface 310 Stents 312 End Section 314 Main Section 318a Second to last ring 319a Third ring from the end 400 stents 802 Ring 1016 Bridge 1018, 1108 Terminal Crown 1402 Crown 1404 Bridge 1406 End Strut 1408a, 1408b penultimate strut 1502 Crown 1508b Strut 1510 Internal Crown 1520 Longitudinal axis 1602, 1604, 1608 Rings 1610 Bridge 1620 Connection Area 1650 Longitudinal axis 1804 Ring 1820 Bridge 1840, 1850 strut 1860 Crown 2600 Heart 2610 Aorta 2620 Superior vena cava 2630 Septal duct 2640 Inferior vena cava 2650 Ductus arteriosus 2660 Left ventricle 2692 Distal end 2694 Body Section 2698 Right ventricle 2670 Right atrium 2680 Left atrium 2690 Stent Delivery System 2700 Microcatheter 2710 Distal Section 2720 ​​Main Section 2730 Pusher Wire

Claims

1. An instrument for insertion into a blood vessel lumen to maintain the patency of an arterial vessel, A first end section including a first plurality of struts configured to expand and define a proximal surface having a first diameter, A second end section including a second plurality of struts configured to expand and define a distal surface having a second diameter, A body section extending between the first end section and the second end section and defining a third diameter, the body section having a third plurality of struts, An instrument lumen extending through the first end section, the body section, and the second end section and configured such that blood flows through the instrument lumen, The instrument is configured to transition from a crimped configuration to an expanded configuration, in which the crimped diameter of the instrument is less than the lumen diameter of a 2.7Fr catheter, and in which the instrument is configured to expand to an expanded diameter of greater than about 3 mm as measured in the body section, The instrument has a radial resistance force greater than about 0.20 N / mm at a compression of 1 mm in the expanded configuration.

2. The instrument according to claim 1, wherein in the expanded configuration, the first diameter of the proximal surface is about 20% to about 50% greater than the third diameter of the body section, and in the expanded configuration, the second diameter of the distal surface is about 20% to about 50% greater than the third diameter of the body section.

3. Each of the first plurality of struts has a first length, each of the second plurality of struts has a second length, and each of the third plurality of struts has a third length, The third length is shorter than the first length, The third length is shorter than the second length, The instrument according to claim 1. **Claim 4**: The apparatus according to claim 3, wherein each of the first end section and the second end section has a length of about 1 mm to about 3 mm, and each of the third lengths of the plurality of third struts is about 1 mm to about 2 mm. **Claim 5**: The apparatus according to claim 1, wherein the plurality of first struts of the first end section are arranged in one or more first rings, and the one or more first rings include 2 to 5 first rings. **Claim 6**: The apparatus according to claim 5, wherein adjacent first rings of the first end section are connected via 3 to 9 first bridges. **Claim 7**: The apparatus according to claim 6, wherein each first bridge has a first length between about 0.1 mm and about 0.25 mm. **Claim 8**: The plurality of second struts of the second end section are arranged in one or more second rings, and the one or more second rings of the second end section include a second end ring including a plurality of struts at the second end, a second second ring from the end including a plurality of struts second from the second end, and a second third ring from the end including a plurality of struts third from the second end, and the second end strut length of the struts at the second end is longer than the second second from the end strut length of the struts second from the second end, and the second second from the end strut length of the struts second from the second end is longer than the second third strut length of the struts third from the second end, The apparatus according to claim 1. **Claim 9**: The apparatus according to claim 1, wherein the first end section and the second end section are each configured to fix the apparatus to at least a part of the aortic orifice and at least a part of the pulmonary artery orifice such that the body section straddles the arterial vessel. **Claim 10**: The apparatus according to claim 1, wherein a distal subset at the proximal surface of the first plurality of struts forms a proximal angle with respect to the longitudinal axis of the instrument, and a distal subset at the distal surface of the second plurality of struts forms a distal angle with respect to the longitudinal axis of the instrument. **Claim 11**: The apparatus according to claim 10, wherein each of the proximal angle and the distal angle is from about 30 degrees to about 110 degrees. **Claim 12**: The apparatus according to claim 11, wherein each of the proximal angle and the distal angle is from about 45 degrees to about 90 degrees. **Claim 13**: An apparatus for insertion into the lumen of an arterial vessel to maintain the patency of the arterial vessel, a first end section including a first plurality of struts configured to expand and define a proximal surface having a first diameter; a second end section including a second plurality of struts configured to expand and define a distal surface having a second diameter; a body section extending between the first end section and the second end section and defining a third diameter, the body section having a third plurality of struts, the body section having a crown-to-bridge ratio of from about 6:3 to about 9:3; an instrument lumen extending through the first end section, the body section, and the second end section, the instrument lumen being configured such that blood flows through the instrument lumen; and the instrument is configured to transition from a crimped configuration to an expanded configuration, in the crimped configuration, the crimp diameter of the instrument is sized to pass through the lumen of a microcatheter, and in the expanded configuration, the instrument is configured to expand to an expanded diameter of greater than about 3 mm as measured in the body section; the instrument has a radial resistance greater than about 0.30 N / mm at a compression of 1 mm in the expanded configuration; an instrument. **Claim 14**: The instrument according to claim 13, wherein in the expanded configuration, each of the first diameter of the proximal surface and the second diameter of the distal surface is about 1 mm to about 2 mm larger than the third diameter of the body section. **Claim 15**: A delivery system comprising a microcatheter and a pusher wire, wherein the pusher wire is configured to advance through a lumen defined by the microcatheter, and the pusher wire includes a first hub and an implant receiving section configured to receive the instrument. The instrument according to claim 13, comprising. **Claim 16**: The instrument according to claim 13, wherein a terminal subset at the proximal surface of the first plurality of struts forms a proximal angle with respect to the longitudinal axis of the instrument, and a terminal subset at the distal surface of the second plurality of struts forms a distal angle with respect to the longitudinal axis of the instrument. **Claim 17**: The instrument according to claim 16, wherein each of the proximal angle and the distal angle is about 30 degrees to about 110 degrees. **Claim 18**: The instrument according to claim 13, wherein the third diameter of the body section in the expanded configuration is at most about 50% smaller than the lumen of the arterial duct in prostaglandin. **Claim 19**: The instrument according to claim 18, wherein in the expanded configuration, the first diameter of the proximal surface is about 20% to about 50% larger than the third diameter of the body section, and in the expanded configuration, the second diameter of the distal surface is about 20% to about 50% larger than the third diameter of the body section. **Claim 20**: Each of the first plurality of struts has a first length, each of the second plurality of struts has a second length, and each of the third plurality of struts has a third length. The third length is shorter than the first length. The third length is shorter than the second length. The instrument according to claim 13. **Claim 21**: The instrument according to claim 20, wherein each of the first end section and the second end section has a length of about 1 mm to about 3 mm, and the third length of each of the plurality of third struts is about 1 mm to about 2 mm. **Claim 22**: A delivery system comprising a microcatheter and a pusher wire, wherein the pusher wire is configured to advance through a lumen defined by the microcatheter, and the pusher wire includes a first hub and an implant receiving section configured to receive the instrument. The instrument according to claim 1, comprising.

Images