Intravascular delivery system and method for percutaneous coronary intervention - Patents.com

Abstract

The subject guide catheter extension / pre-dilatation system includes an outer delivery sheath, an inner member extending within the sheath, and a mechanism for engaging / disengaging the inner member from the sheath. The inner member is configured with a tapered distal tip having a delivery microcatheter and a pre-dilation balloon member attached to the tapered distal tip proximal to the microcatheter. The outer delivery sheath and inner member are modified for operation of different engagement / disengagement mechanisms. The delivery microcatheter provides improved mobility of the balloon member to the treatment site in an atraumatic, rapid, and convenient manner. During cardiac surgery, a guidewire and guide catheter are advanced within a blood vessel to near the treatment site. The inner member and outer delivery sheath are then advanced, in an engaged state, along the guidewire inside the guide catheter to the treatment site. Once at the treatment site, the balloon member is inflated for the pre-dilatation procedure. The inner member is then separated from the outer delivery sheath and retracted, and a stent is delivered to the treatment site inside the outer delivery sheath.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This PCT patent application claims priority to U.S. patent application Ser. No. 16 / 793,120, filed February 18, 2020, which is a continuation-in-part (CIP) of U.S. patent application Ser. No. 16 / 132,878, filed September 17, 2018, which is a continuation-in-part (CIP) of U.S. patent application Ser. No. 16 / 132,878, filed February 20, 2018, which is a continuation-in-part (CIP) of U.S. patent application Ser. No. 15 / 899,603, filed February 20, 2018, which is a continuation-in-part (CIP) of U.S. patent application Ser. No. 16 / 132,878, which is a continuation-in-part (CIP) of U.S. patent application Ser. No. 15 / 899,603, filed February 20, 2018, which is a continuation-in-part (CIP) of U.S. patent application Ser.

[0002] (Incorporated by reference) Currently pending U.S. patent applications Ser. Nos. 16 / 793,120, 16 / 132,878, and 15 / 899,603 are hereby incorporated by reference.

[0003] The present invention relates to minimally invasive devices for therapeutic use in the human vasculature, such as the coronary arteries, and in particular to a delivery system for percutaneous coronary intervention particularly adapted for endovascular balloon angioplasty and coronary stent delivery, enhanced by a pre-dilated guide catheter extension function.

[0004] Additionally, the present invention relates to medical devices designed for the atraumatic, convenient, and rapid delivery of various interventional devices, such as pre-dilated balloons or stents, as well as exchange of coronary artery (or other blood vessel) catheters within a patient's body to facilitate percutaneous revascularization.

[0005] Additionally, the present invention is directed to an intravascular delivery system having a small, tapered, soft distal tip that allows for exceptional deliverability of a targeted interventional device over conventional balloon angioplasty catheters, along with substantially atraumatic movability to the lesion site for treatment.

[0006] The present invention further relates to an intravascular guide catheter extension / pre-dilation system that uses an inner member (interventional device delivery catheter subsystem) that is placed in place inside an outer member (outer delivery catheter subsystem), the inner member being formed with a distal coil reinforced tapered section that interfaces with a slightly tapered distal end of the outer member. These are dimensioned to create a low profile and a substantially "seamless" transition at the interface between the distal ends of the outer member (outer catheter) and inner member (inner catheter) at the transition point where the distal portion of the inner catheter engages or enters the outer member. This configuration is highly beneficial for atraumatic smooth passage of the inner and outer members as a single unit along a diseased vessel.

[0007] The present invention further relates to an intravascular guide catheter extension / pre-dilatation system comprised of an outer catheter (member) and an inner catheter (member) displaceable inside the outer catheter along the outer catheter, the distal tapered soft tip of the outer catheter being formed as an expandable flexible low durometer elastomeric member having an inner diameter in a contracted state that is smaller than the outer diameter of the distal portion of the inner catheter in the region of engagement with the outer catheter. This configuration achieves a reversible elastic engagement between the outer and inner catheters at their distal ends, which ensures that the flared distal end of the outer catheter returns to its contracted outer diameter when the inner catheter is removed from the outer catheter, reducing (or eliminating) "fishmouthing" at the distal junction of the outer and inner members as the system navigates successive bends in the blood vessel.

[0008] Additionally, the present invention relates to an intravascular guide catheter extension / pre-dilation system configured with outer and inner catheters that are displaceable relative to one another, with the proximal end of the outer catheter having an inlet configuration that provides increased reinforcement, improved mid-shaft stent entry, prevention of stent embolization, increased flexibility, and improved flow rate of contrast injection fluid.

[0009] Furthermore, the present invention relates to an intravascular guide catheter extension / pre-dilatation system designed with a mid-shaft interconnection (locking) mechanism that can be activated / deactivated by a physician to either (1) controllably engage the inner and outer members for movement together within the guide catheter along a guidewire, or (2) separate the inner and outer catheters for retraction of the inner catheter from the outer member (catheter) as required in an intravascular procedure. The inner member can carry an interventional device (such as a pre-dilatation balloon member or stent) attached to its tapered coil-reinforced distal end, and the locking mechanism provides a smooth and reversible engagement / disengagement procedure. Furthermore, this mid-shaft reversible lock prevents forward movement of the inner member relative to the outer member as the system is advanced or retracted, ensuring that the position of the distal "seamless" transition of the inner and outer catheters remains essentially fixed in place axially during movement of the subject system.

[0010] Additionally, the present invention relates to an intravascular guide catheter extension / pre-dilation system configured with a tapered, coil-reinforced shaft at its distal end for mounting and carrying a balloon member, providing "seamless" entry and smooth delivery of the balloon member, integral with the coil-reinforced delivery sheath of the outer catheter, to the desired treatment site.

[0011] Additionally, the present invention is directed to an intravascular guide catheter extension / pre-dilatation system featuring an embodiment of a monorail microcatheter with rapid exchange (RX) capability for use with short guidewires, configured with a coil-reinforced microcatheter in which a distal tapered soft end of the inner catheter provides additional kink resistance and "pushability" while still maintaining flexibility for navigating tortuous vasculature. [Background technology]

[0012] Coronary artery occlusive disease or other diseases in the peripheral vasculature are often treated by balloon angioplasty and / or stent placement. Advancement of a revascularization device, such as a balloon or stent delivery system within a blood vessel to the treatment site can be difficult for a physician when the vessel is tortuous and / or calcified.

[0013] Coronary stents, commonly used in a procedure called percutaneous coronary intervention (PCI), are tubular devices placed in the coronary arteries that supply blood to the heart to keep the arteries open for the treatment of coronary heart disease. Stents help improve blood flow in the coronary arteries and relieve chest pain, and have been shown to improve survivability in cases of acute myocardial infarction.

[0014] Treatment of blocked coronary arteries with stents follows essentially the same steps as other angioplasty procedures, but with an important difference: a compressed stent mounted on a balloon significantly reduces the flexibility of the balloon, making it difficult to advance smoothly through the coronary artery. This can make it difficult or impossible to deliver the stent to the treatment site, and there is a risk that the undeployed stent may become dislodged from the delivery balloon.

[0015] Intravascular imaging can be used to assess the thickness and hardness (calcification) of the lesion, which affects the deliverability of a stent. Cardiologists use this information to decide whether to treat the lesion with a stent, and if so, what type and size of stent should be used. Stents, both bare metal and drug-eluting stents, are most often sold as a unit in which the stent in its collapsed (pre-expanded) form is mounted on the outside of a balloon catheter.

[0016] Physicians can perform "direct stenting," where a stent is advanced through the blood vessels to the lesion and expanded. However, to facilitate stent delivery in more difficult lesions, it is common to pre-dilate the occlusion before delivering the stent.

[0017] Pre-dilatation is accomplished by passing a conventional balloon catheter through the lesion and inflating it to increase the diameter of the lesion. A balloon catheter is a type of "soft" catheter with an inflatable balloon at its tip that is used in catheterization procedures to enlarge narrow openings or passageways in the body. After pre-dilatation, the pre-dilatation balloon is removed and a stent catheter is advanced through the blood vessel to the lesion, inflated, and left at the lesion site as a permanent implant to open the blood vessel as a "scaffolding."

[0018] Balloon catheters used in angioplasty have either an over-the-wire (OTW) or rapid exchange (RX) design. The balloon catheter is slid over a guidewire that can be loaded into the balloon catheter through a hub (in over-the-wire variants) or RX port (in the case of rapid exchange variants of balloon catheters). In over-the-wire balloon catheters, a concentric lumen for passing the guidewire runs through the catheter from the proximal hub to the balloon, while in rapid exchange (RX) balloon catheters, a lumen for guidewire passage runs from the RX port inside the catheter to the balloon, allowing passage of the guidewire.

[0019] Revascularization devices typically use a guiding catheter to deliver such devices to the site of treatment. "Backing up" the advancement of a revascularization device into a coronary artery using only a guiding catheter can be limited and difficult, especially when a stent is placed using a radial access guiding catheter.

[0020] To facilitate delivery of revascularization devices to a desired site, guide catheter extension systems have been designed and used in cardiac surgery.

[0021] For example, guide extension systems such as the "Guideliner™" are manufactured by Teleflex. This guide extension system is described in U.S. Patent No. 8,292,850 to Root et al., which describes a coaxial guide catheter threaded through a lumen of a guide catheter for use with an interventional cardiology device insertable into a branch artery branching off the aorta.

[0022] The Root coaxial guide catheter extends through the lumen of the guide catheter and past its distal end and is inserted into the branch artery. Root uses a guide extension supported by a tapered inner catheter. The purpose of the inner catheter is to provide an atraumatic tip to avoid vessel injury when the guide extension is advanced into the proximal portion of the coronary vessel to provide additional "back-up" support for delivery of a stent or balloon.

[0023] Another guide extension system, such as "Guidezilla™," is designed and manufactured by Boston Scientific. This guide extension system is described in U.S. Patent No. 9,764,118 to Anderson et al. The Anderson guide extension system uses a pusher member having a proximal portion having a proximal stiffness, a distal portion having a distal stiffness different from the proximal stiffness, and a transition portion that provides a smooth transition between the proximal and distal portions. A distal tubular member is attached to the pusher member and has an outer diameter larger than the outer diameter of the pusher member.

[0024] U.S. Patent Application Publication No. 2017 / 0028178 by Ho describes a guide extension system that uses a slit catheter that can expand upon insertion of a balloon or stent delivery system. Additionally, Ho's guide extension uses a rigid pushrod to aid in delivery of the guide extension to the treatment site.

[0025] The Guideliner™ and Guidezilla™ systems, as well as the Ho system, support the concept of advancing a guide extension system partially through the guide catheter and into the coronary artery to achieve additional “back-up” support for delivery of a balloon dilatation catheter and / or a stent delivery catheter to the intended treatment site.

[0026] The function of these guide extensions is to allow for closer access to the lesion to provide additional support as the interventional device traverses the lesion to be treated. However, despite the additional support, it may still be difficult or nearly impossible for a pre-dilation balloon catheter or stent delivery system to pass through the lesion to be treated due to fibrosis, calcification, previous stent struts within the lumen, and / or angular geometry at the lesion site.

[0027] One of the limitations of currently used guide extension devices is that they use relatively blunt, large diameter cylindrical distal ends. Due to the relatively large profile of the distal edge, the deliverability of the guide extension is often limited and it can only be advanced to the proximal or mid-portion of the coronary artery to be treated. Even after balloon pre-dilatation of the lesion, it is very rare, if not impossible, for the guide extension to reach the actual lesion to be treated with angioplasty or stenting. These "blunt-ended" tubular guide extension devices fail relatively frequently and can cause serious dissection complications. Published data indicates that "blunt-ended" tubular guide extension systems can fail in up to 20% of cases and cause serious coronary artery dissections in approximately 3% of cases.

[0028] U.S. Patent Application Publication No. 2011 / 0301502 by Gill describes a catheter with a longitudinal extension that allows the diameter of the positioning device to be smaller than the stent delivery system. However, the Gill device does not envisage an inner catheter to allow easy and atraumatic crossing of the lesion to be treated. The Gill system simply serves as a cover for the stent delivery system and can be removed after the stent delivery system has been advanced due to the longitudinal extension.

[0029] While the concept of an inner tapered piece of a guide extension catheter is seen in the Root device, the prior art systems use a very short taper and do not envision the taper as an elongated integral part of the overall system, nor do they envision attaching a pre-dilated balloon to a tapered delivery microcatheter that is brought to the intended treatment area. Additionally, the prior art does not envision a substantially "step-free" interface between the inner catheter and the outer guide extension inside the blood vessel, nor does it envision the inner and outer catheter members reversibly mating or locking together to allow the entire system to be easily moved as one integral device.

[0030] Neither Root nor other prior art systems describe, anticipate, or envision a balloon (and / or stent) delivery system having an elongated tip with a very small profile that would be beneficial in achieving coaxial delivery of the guide catheter extension / balloon system to and past the target lesion. Such embodiments have not previously been commercially available, and the description of the tapered tip inner device is intended only as a mechanism for bringing the blunt tip of the guide catheter extension proximally out of the guide catheter, and never as a mechanism for delivering the balloon (and / or stent) to and past the target treatment area within the vessel, nor does it envision the unitary nature of the inner and outer members and the "stepless" interconnection that would allow for passage of the outer delivery "sheath" member across the target lesion.

[0031] Thus, devices and methods that allow the distal portion of a tubular guide extension system to be delivered to, and ideally past, the lesion to be treated are believed to have significant advantages over conventional guide extension devices such as "Guideliner™" (Teleflex) or "Guidezilla™" (Boston Scientific).

[0032] None of the conventional balloon catheters (over-the-wire or quick exchange) are integrated with an outer delivery sheath and use a tapered delivery microcatheter at the distal end of the catheter to which an interventional device (e.g., balloon or stent) is secured for atraumatically advancing inside the blood vessel to and past the lesion. Furthermore, none of the conventional balloon catheters are interconnected to an outer delivery sheath (guide catheter extension subsystem) via an interconnection mechanism that is activated to allow the conventional balloon catheter and outer delivery sheath to move together as a single unit and is deactivated to allow the balloon catheter to be withdrawn from the outer delivery sheath while preventing forward displacement of the balloon catheter relative to the outer delivery sheath.

[0033] It would be highly desirable and efficient to provide an intravascular delivery system that can deliver an interventional device (e.g., a pre-dilation balloon), along with a guide catheter extension subsystem (such as an outer delivery sheath), to and past a lesion in a substantially atraumatic and convenient manner.

[0034] Furthermore, it would be highly desirable to provide an intravascular delivery system having outer and inner catheters, both of which feature reinforced distal ends having a compact, tapered distal tip configuration with a "seamless" distal boundary to ensure that the system can be advanced atraumatically to the lesion for treatment.

[0035] In addition, it would be desirable to facilitate percutaneous revascularization procedures by using a balloon attached to a coil-reinforced tapered distal tip of an inner balloon catheter housed within the outer delivery sheath of an outer catheter, the inner balloon catheter comprising an elongated tapered coil-reinforced microcatheter distal to the tapered distal tip for carrying an interventional device (pre-dilation balloon and / or stent) to and past the lesion to be treated. This would represent a significant improvement over conventional guide catheter extension and pre-dilation systems. [Prior art documents] [Patent documents]

[0036] [Patent Document 1] U.S. Patent No. 8,292,850 [Patent Document 2] U.S. Pat. No. 9,764,118 [Patent Document 3] US Patent Application Publication No. 2017 / 0028178 [Patent Document 4] US Patent Application Publication No. 2011 / 0301502 Summary of the Invention

[0037] It is therefore an object of the present invention to provide a medical device for intravascular application that can deliver an interventional device (such as a balloon or stent) to and past an occlusive lesion in a coronary artery in an efficient and minimally traumatic manner.

[0038] Another object of the present invention is to provide an intravascular delivery system that uses a coaxial, highly flexible delivery catheter device having an outer catheter and an inner catheter that interface with each other at their distal ends in a "seamless" manner, which is beneficial in achieving "crossability" of a pre-dilation balloon (or other interventional device) and has a small profile that enhances efficient and safe distal delivery of a guide extension device.

[0039] It is a further object of the present invention to use a highly flexible coil-reinforced distal tapered elongated microcatheter tip to deliver a pre-dilation balloon (or another interventional device) to and / or past a target lesion in a diseased human coronary artery being treated with angioplasty (or stenting).

[0040] It is a further object of the present invention to provide a guide catheter extension / pre-dilatation system that uses an outer catheter (outer delivery sheath subsystem) and an inner catheter (interventional device delivery subsystem) housed inside and interchangeably connected to the outer sheath of the outer catheter, both of which are deliverable to or beyond the area of ​​a therapeutic lesion within a blood vessel, the inner catheter having at its distal end a delivery tapered microcatheter having attached a pre-dilatation balloon member (or other interventional device) that slides along a guidewire in a substantially atraumatic manner.

[0041] A further object of the present invention is to provide a guide catheter extension subsystem (outer member) integrated with a pre-dilation balloon (or other interventional device) subsystem (inner member), which is coupled together (via a locking mechanism) so that the outer and inner members are displaced together (as the "whole system") along the guidewire to the lesion site. After the pre-dilation procedure, the guide catheter extension subsystem (comprised of an outer delivery sheath) can be decoupled from the inner member and advanced past the lesion as needed. The inner member (interventional device delivery subsystem) can then be withdrawn. If necessary for the surgical procedure, the outer delivery sheath of the outer member can remain within the guide catheter to facilitate delivery of a stent (or other interventional device) inside the outer delivery sheath to the lesion site. The outer delivery sheath can then be withdrawn after the stent (or other interventional device) has been delivered to the lesion and deployed for final treatment.

[0042] It is a further object of the present invention to provide a guide catheter extension / pre-dilatation system that includes a "locking mechanism" operably coupled between the inner member and the outer member (outer sheath) to allow both members to pass together as a single unit for convenient and safe delivery of the pre-inflated balloon and outer sheath to and past the treatment site.

[0043] It is a further object of the present invention to provide a guide extension system comprising a pre-dilated balloon (or other interventional device) delivery catheter that can be delivered to a treatment site inside a vasculature in an atraumatic manner to achieve easy passage of the balloon (or other interventional device) and guide extension system to expedite cardiac surgery, which allows percutaneous coronary intervention to be performed with lower radiation exposure than would be achieved using conventional systems, with the added advantage of substantially no risk of stent embolization or drug loss (due to drug-eluting stents) from the stent delivery system.

[0044] It is a further object of the present invention to provide an intravascular guide catheter extension / pre-dilation system comprising coaxial inner and outer catheters which are displaceable relative to one another and yet are increasingly flexible, yet are reinforced with coil reinforcement along their length to achieve improved contrast injection flow rates and embolic protection, wherein the tapered distal end of the outer catheter can be elastically stretched to provide strong contact with the distal portion of the inner catheter and a substantially step-free (smooth) outer surface at the interface between the inner and outer catheters.

[0045] The present system and method address an intravascular delivery system configured for controllably displacing along a guidewire within a vessel of a subject. The system is formed with a proximal portion, a distal portion, and an intermediate portion located between the proximal portion and the intermediate portion. The system includes an outer member formed by a flexible, substantially cylindrically contoured, elongated outer delivery sheath defining a sheath lumen having a proximal end and a distal end. The outer delivery sheath extends between the intermediate portion and the distal portion and is configured with a tapered outer tip at the distal end of the sheath lumen. The tapered outer tip of the outer member located at the distal end of the outer delivery sheath is configured with a wall extending in a cylindrical manner between a distal edge and a proximal edge of the tapered outer tip. The wall of the tapered outer tip has an inner diameter and an outer diameter. The inner diameter and the outer diameter of the wall of the tapered outer tip gradually decrease in dimension from the proximal edge to the distal edge of the tapered outer tip. The proximal (wire or hypotube) element (push or pull) connected to the tubular structure of the outer member may be of small profile and "flexible" (not "rigid") to allow for improved fit inside the guide catheter and a smaller profile than the rigid "push" elements in conventional guide extension catheters (such as Root). This is possible because of the "pushability" of the "whole system" that is achieved through the locked integral connection between the outer catheter (with the hypotube push / pull element) and the inner catheter (guide extension tube).

[0046] The system further includes an inner member (inner catheter) having an elongate body defining an internal channel extending along a longitudinal axis. The inner member extends internally along a sheath lumen of the outer member (outer catheter) in a controllable relationship with the outer delivery sheath. The inner member elongate body has a tapered distal portion, the tapered distal portion comprising a tapered delivery catheter having an outer diameter and an elongate body of a predetermined length. The inner member tapered delivery catheter is displaceable past the distal end of the outer sheath. It is important that the inner diameter of the wall of the tapered outer tip of the outer member is smaller than the outer diameter of the tapered distal portion of the inner member in the region where these two elements form a distal junction.

[0047] An interconnect mechanism is operatively coupled between the inner and outer members and is controllably actuated to operate the guide catheter extension / pre-dilatation subsystem in an engaged or separated mode of operation. In the engaged mode of operation, the inner and outer members of the guide catheter extension subsystem are engaged for controllable common displacement along the guidewire. This also allows for improved "pushability" of the system (with the outer member connected and locked to the inner member) even though the connected pusher (push / pull element) of the outer member has a small profile and is flexible (as flexible as or more flexible than the outer tubular sheath of the outer catheter). In the separated mode of operation, the inner and outer members are separated to retract the inner member from the outer member after a pre-dilatation procedure or stent delivery.

[0048] The distal portion of the inner member interfaces at its outer surface with the inner surface of the tapered outer tip of the sheath lumen such that the dimensional transition between the outer diameter of the outer tip of the sheath lumen and the outer diameter of the distal tip of the inner member forms a substantially step-free boundary transition therebetween.

[0049] The tapered outer tip of the outer member has a configuration that allows it to resiliently expand. At its proximal end (also referred to herein as the outer member shaft intermediate portion), the outer sheath is configured with an entrance opening whose circumference exceeds the circumference of the tubular body of the outer sheath. In some embodiments, the entrance opening at the proximal end of the outer sheath is funnel-shaped.

[0050] The outer sheath is preferably reinforced along its length. The outer member includes a distal soft tip encapsulating material at its distal end that encases the reinforced sheath of the outer member. The distal soft tip encapsulating material is a flexible, low durometer elastomeric material having an increasing gradient of durometer from the distal end to the proximal end of the sheath.

[0051] The outer member further includes a distal lubricous liner sandwiched between the outer surface of the outer sheath and the inner surface of the distal soft tip encapsulation material.

[0052] The delivery catheter is preferably a microcatheter, which is formed of a flexible material and can have differential flexibility along its length, with the flexibility of the microcatheter increasing towards its distal end.

[0053] A balloon catheter is attached to the tapered distal portion of the inner member adjacent the tapered delivery microcatheter, and an inflation lumen extends within the inner member between the balloon members of the proximal and distal portions to provide a fluid passage between an external balloon inflation system and the balloon member. The balloon member can be in an inflated or deflated state. In the deflated state, the balloon member is displaced within the vessel. The balloon member is controllably transformed to an inflated configuration after being positioned at least in alignment with the treatment site for the pre-dilatation procedure.

[0054] The elongate body of the inner member and the microcatheter are reinforced with coils along their lengths.

[0055] An outer catheter pusher / puller element configured with a flattened portion at its distal end is secured to the proximal end of the outer catheter outer sheath. Preferably, the outer member pusher / puller is configured with a channel extending along its length and communicating with the sheath lumen to prevent emboli. This proximal (push and pull) element connected to the outer catheter outer sheath tubular structure may be of small profile and "flexible" (not "rigid") to allow for better fit inside the guiding catheter and a smaller profile than the rigid "push" elements in conventional guide extension catheters (such as Root).

[0056] The interconnection mechanism may include a snap-fit ​​locking mechanism comprising a proximal coupler disposed at a proximal end of the sheath of the outer member (catheter) and a cooperating element disposed on an outer surface of the elongated body of the inner member (catheter). The proximal coupler may include a distal solid ring and an intermediate split ring disposed at a predetermined distance from the solid ring, while the cooperating member includes a member selected from a group including a shift intermediate locking ring, a square annular ring, a snap-fit ​​cage, and other similar members. The cooperating member is attached to the outer surface of the elongated body of the inner member. When the cooperating member is engaged and locked between the distal solid ring and the intermediate split ring in a snap-fit ​​manner, a locked engagement between the outer member and the inner member is achieved. The pusher / puller elements and couplers of the outer catheter may be made from a memory metal (e.g., Nitinol, etc.) to prevent deformation during antegrade or retrograde movement of the outer member and to prevent deformation of the mid-shaft coupler (also referred to herein as the proximal coupler) when a stent or other device is passed through the mid-shaft of the outer catheter.

[0057] The proximal coupler further includes a proximal tapered split ring at its proximal end that reinforces the funnel-shaped proximal inlet of the outer member and prevents damage or permanent deformation of the funnel-shaped proximal inlet caused by displacement of the inner member or the stent delivery system at the funnel inlet. The coupler and shaft intermediate inlet can have an inlet opening (or "mouth") whose circumference is larger than the circumference of the flexible tubular outer sheath structure of the outer member.

[0058] The subject intravascular system further includes a guidewire that can be advanced within the subject's vasculature at least to the treatment site, and the guide catheter extension subsystem is configured for controllable displacement along the guidewire. In one embodiment of the system, an elastic outer jacket encases the inner member at least at its proximal end and encases the inner member's pusher / puller at least along its distal end. The proximal end of the inner member is connected to the pusher / puller by fusing the elastic outer jacket to a length of the inner member's proximal end and supporting the inner member's pusher / puller snugly within the elastic outer jacket.

[0059] The push / pull element of the outer catheter (or its outer jacket) may be color coated to have a distinctive color to distinguish it from the push / pull element of the inner catheter, as well as the usual gray or silver color of the coronary guidewire, or the elastomeric outer jacket of the inner member may be color coated to distinguish the pusher / puller of the inner member from the color of other elements of the subject system for the convenience of the surgeon.

[0060] These and other objects and advantages of the present invention will become apparent to those skilled in the art from a review of the detailed description of the invention in conjunction with the patent drawings. [Brief description of the drawings]

[0061] [Figure 1] 1 shows a schematic of a subject guide catheter extension / pre-dilatation system advanced to a target site within a coronary artery. [Figure 2A] 1 is a schematic illustrating a subject guide catheter extension / pre-inflation system showing the assembled inner and outer catheters. [Figure 2B] 1 illustrates a schematic of a subject guide catheter extension / pre-inflation system, detailing the inner catheter. [Figure 2C]1 illustrates a schematic of a subject guide catheter extension / pre-inflation system, detailing a mid-portion of the subject system. [Figure 3A] FIG. 1 is a view of the intermediate portion of a subject inner catheter, showing a longitudinal cross section of an inflation lumen hypotube interconnected with an inflation lumen distal shaft within the inner catheter. [Figure 3B] FIG. 13 is a view of the intermediate portion of a subject inner catheter, detailing a longitudinal cross section of the skived portion of the inflation lumen hypotube. [Figure 3C] FIG. 13 is a diagram of the midsection of a subject inner catheter, showing a longitudinal cross-section of the inner catheter showing the RX guidewire (GW) port formed in the inflation lumen distal shaft. [Figure 3D] FIG. 3D is a view of the intermediate portion of a subject inner catheter, showing an isometric view of the RX port portion of the inner catheter shown in FIG. 3C. [Figure 4] FIG. 13 shows a longitudinal cross-section of the inner catheter detailing the distal end of the inflation hypotube at the junction with the inflation lumen distal shaft. [Figure 5A] 1 illustrates a distal portion of the subject system, showing an inflatable balloon member. [Figure 5B] 1 illustrates a distal portion of the subject system, showing a balloon member in a deflated state. [Figure 5C] 1 shows the distal portion of the subject system, detailing the inflation cavity / balloon junction. [Figure 6] Figure 6A shows a longitudinal cross section of the distal portion of a subject inner catheter, detailing the 3 mm distal and proximal tapers of the balloon, and Figure 6B shows a longitudinal cross section of the distal portion of a subject inner catheter, detailing the 6 mm distal and proximal tapers of the balloon. [Figure 7] The distal tip of the outer catheter is shown. [Figure 8A] 17 details the interface of the inner and outer catheters at their distal ends, showing the tapered distal end of the inner catheter. [Figure 8B]The interface of the inner and outer catheters at their distal ends is shown in detail, with a somewhat enlarged view of the connection point between the inner and outer catheters. [Figure 9] Figure 9A depicts an alternative embodiment of an elastically stretchable distal tip of an outer catheter configured with an expandable split ring, Figure 9B depicts an alternative embodiment of an elastically stretchable distal tip of an outer catheter configured with an expandable tip scaffold, Figure 9C depicts an alternative embodiment of an elastically stretchable distal tip of an outer catheter configured with a slit, and Figure 9D depicts an alternative embodiment of an elastically stretchable distal tip of an outer catheter configured with a slit. [Figure 10] FIG. 10A shows a side view of an embodiment of a proximal portion of a subject outer catheter option. FIG. 10B shows a side view of an embodiment of a proximal portion of a subject outer catheter option. FIG. 10C shows an isometric view of an embodiment of a proximal portion of a subject outer catheter option. FIG. 10D shows a side view of an embodiment of a proximal portion of a subject outer catheter option. FIG. 10E shows an isometric view of an embodiment of a proximal portion of a subject outer catheter option. FIG. 10F shows a side view of an embodiment of a proximal portion of a subject outer catheter option. FIG. 10G shows an isometric view of an embodiment of a proximal portion of a subject outer catheter option. [Figure 11] Figure 11A details the coupler design at the proximal end of the outer catheter, showing an isometric view of a flattened hypotube pusher, Figure 11B details the coupler design at the proximal end of the outer catheter, showing an isometric view of the proximal end of the outer catheter, and Figure 11C details the coupler design at the proximal end of the outer catheter, showing a side view of the coupler at the proximal end of the outer catheter featuring a snap-fit ​​locking mechanism. [Figure 12]12A, 12B, and 12C show alternative embodiments of the proximal portion of a subject outer catheter, each of which is an isometric view of a proximal coupler, an encapsulated proximal coupler, and a side view of an encapsulated proximal coupler, respectively. [Figure 13] Figures 13A and 13B show isometric views of yet another embodiment of a proximal coupler at the proximal end of an outer catheter. [Figure 14] Figure 14A shows an embodiment of a weld ring at the proximal inlet of the outer catheter, showing a weld ring coupler, and Figure 14B shows an embodiment of a weld ring at the proximal inlet of the outer catheter, showing an encapsulated weld ring coupler. [Figure 15] Figures 15A, 15B, 15C, 15D show a further alternative embodiment of the proximal coupler of the outer catheter, a side view of a window with a circular outline of the funnel, an isometric view of a window with a circular outline of the funnel, a side view of a triangular window of the funnel, and an isometric view of a triangular window of the funnel. [Figure 16] FIG 16A is an isometric view of the hypotube pusher flushing lumen concept showing an isometric view of the proximal coupler of the outer catheter coupled to the pusher, FIG 16B is a cross-sectional isometric view of FIG 16A showing the flow paths within the pusher, and FIG 16C is a isometric view of the hypotube pusher flushing lumen concept showing the procedure of injecting flushing fluid between the inner and outer catheters. [Figure 17]Figure 17A shows a subject shaft intermediate annular circular ring locking mechanism, showing an "unlocked" mode of operation. Figure 17B shows a subject shaft intermediate annular circular ring locking mechanism, showing a "locked" mode of operation. Figure 17C shows a subject shaft intermediate annular circular ring locking mechanism, showing a view of the annular circular ring in the subject locking mechanism. [Figure 18] Figure 18A details the annular circular ring locking mechanism of the subject matter shown in Figures 17A and 17B, showing a proximal coupler configured with a locking pocket for engagement with the annular circular ring (of Figure 17C), and Figure 18B details the annular circular ring locking mechanism of the subject matter shown in Figures 17A and 17B, showing a longitudinal cross-section of the inner / outer catheters locked together. [Figure 19] FIG. 19A illustrates an alternative subject matter embodiment of a locking mechanism featuring a mid-shaft "square" annular ring, showing an inner catheter with a ring-like locking mechanism. FIG. 19B illustrates an alternative subject matter embodiment of a locking mechanism featuring a mid-shaft "square" annular ring, showing the ring of the inner catheter mated to the proximal coupler of the outer catheter. FIG. 19C illustrates an alternative subject matter embodiment of a locking mechanism featuring a mid-shaft "square" annular ring, showing a cross-section of the square annular ring. [Figure 20A] 13 shows an alternative "snap-fit ​​cage" locking mechanism, and an inner catheter with a welded cage lock. [Figure 20B] 13 shows an alternative "snap-fit ​​cage" locking mechanism, showing the cage lock by welding the inner catheter to the proximal coupler of the outer catheter. [Figure 20C] FIG. 13 illustrates an alternative “snap-fit ​​cage” locking mechanism, showing an isometric view of welded cage elements. [Figure 21] FIG. 13 is a side view of another embodiment of a proximal coupler of an outer catheter featuring two locking slots. [Figure 22]Figure 22A depicts a monorail microcatheter embodiment of the subject system, showing an isometric view of the monorail microcatheter embodiment, and Figure 22B depicts a monorail microcatheter embodiment of the subject system, showing a side view taken along line AA. [Figure 23A] 1A-1C are detailed views of a subject monorail microcatheter embodiment, showing an isometric view of a proximal portion of an inner catheter connected to an inner catheter hypotube pusher. [Figure 23B] 1A-1C show detailed views of a subject monorail microcatheter embodiment, detailing the proximal end of the pusher at a somewhat enlarged scale. [Figure 23C] 1A-1C are side views of a proximal portion of an inner catheter connected to a hypotube pusher, detailing a subject monorail microcatheter embodiment. [Figure 24] 24A and 24B show isometric and side views of an embodiment of a coil-reinforced balloon catheter of the subject system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0062] 1-24B, a subject intravascular delivery system 10 is shown that includes a guide catheter extension subsystem (also referred to herein as an outer catheter or outer member) and an interventional device delivery subsystem (also referred to herein as an inner catheter or inner member) that cooperate under the control of a surgeon during cardiac surgery. While the interventional device delivery subsystem can be used for the delivery of a variety of cardiac interventional devices, in one of the embodiments, by way of example only and without limiting the scope of the invention to this particular embodiment, the subject interventional device delivery subsystem is further described as being configured for the delivery of a balloon member to perform a pre-dilatation procedure.

[0063] In the exemplary embodiments described herein, the subject system 10 may be referred to herein as a guide catheter extension / pre-dilatation system that may be used in cardiac surgery together with a guide wire 12 and a guide catheter 14. As shown in FIG. 1, in the initial stages of cardiac surgery, a guide wire (GW) 12 is moved into a blood vessel 16 by a surgeon. A guide catheter 14 is advanced through the blood vessel 16 (such as the aorta) along the guide wire 12 to a position adjacent an entrance 18 of a coronary artery 20. The guide wire 12 may be used to guide the guide catheter 14 in cardiac surgery, after which the subject guide catheter extension / pre-dilatation system 10 (inside the guide catheter 14) may be extended within the artery 20 toward a target location 22, as described in detail in the following paragraphs.

[0064] 2A-2C, a subject guide catheter extension / pre-dilatation system 10 includes a balloon catheter subsystem 34 (also referred to herein as an inner catheter, inner member, or pre-dilatation subassembly) and a guide catheter extension subsystem 36 (also referred to herein as an outer catheter). The inner catheter 34 interacts with the outer catheter 36 and can be engaged or disengaged from the outer catheter 36 as required in the cardiac procedure.

[0065] The subject system 10 includes a proximal portion 38, a distal portion 40, and an intermediate portion 42 extending between and interconnecting the proximal portion 38 and the distal portion 40. A pre-dilated balloon member 44 is carried on the distal portion 40 of the inner catheter 34. Additionally, the distal portion 40 of the inner catheter 34 may be configured with an elongated tapered microcatheter 46, as will be described in more detail in the following paragraphs.

[0066] The subject guide extension / pre-dilation system 10 is extended within the lumen (inner channel) 48 of the guide catheter 14, as shown in FIG. 1. To ensure that the subject guide extension / pre-dilation system 10 reaches and possibly passes through the target location 22, the subject guide extension / pre-dilation system 10 is advanced through the guide catheter 14, past the distal end 50 of the guide catheter 14 and deep into the coronary artery 20. By extending past the distal end 50 of the guide catheter 14, the subject system 10 provides proper accessibility of the pre-dilation balloon 44 to the target location 22, and by extending past the entrance 18 of the coronary artery 20, it stabilizes the positioning of the guide catheter 14 and allows for improved accessibility of the subject system 10 to the coronary artery 20 and the target site 22.

[0067] As shown in Figures 1, 2A and 2B, 3C and 3D, 4, 5A-5C, and 6A, the guidewire 12 extends within the guide catheter extension / pre-dilation system 10 and exits the system 10 with the distal end of the GW 12 past the outermost end 52 of the distal section 40 and the proximal end of the GW 12 in the intermediate section 42.

[0068] In operation, the inner catheter 34 and outer catheter 36 are coupled together and advanced (as a single unit) along the inner guidewire 12 of the guide catheter 14 disposed within the blood vessel 16, extending past the distal end 50 of the guide catheter 14 to reach the target lesion site 22. Once the target balloon catheter subsystem (inner member) 34 reaches the lesion site 22 and the balloon member 44 is aligned and positioned at the lesion site 22, the intended pre-dilatation procedure can be performed. Once pre-dilatation has been performed, the outer catheter (also referred to herein as the outer member) 36 can be advanced across the lesion as an integral unit with the inner catheter (also referred to herein as the inner member) 34, after which the inner catheter 34 can be decoupled from the outer catheter 36 in order to withdraw the inner catheter from the outer catheter.

[0069] Alternatively, after performing the pre-dilation procedure, the inner catheter 34 can be disconnected from the outer catheter 36 while the outer catheter 36 is advanced across the dilated lesion. In addition, the outer catheter 36 may be left in the vicinity of the lesion after pre-dilation is performed and the inner catheter 34 is removed.

[0070] In either situation, the outer member (catheter) 36, which is left adjacent the lesion after pre-dilation, can be used to deliver a stent to the lesion site inside the outer member (catheter) 36. Once the stent is placed (deployed) at the lesion site, the outer member 36 is removed from the guide catheter 14.

[0071] As will be presented in further paragraphs, in the subject systems, forward displacement of the inner catheter 34 inside the outer catheter 36 is prevented. Exclusively, rearward or removal displacement of the inner member 34 relative to the outer member 36 is permitted to support retraction of the inner member from the outer member after pre-dilatation of the lesion.

[0072] 2A-2C, the proximal portion 38 of the subject guide extension / pre-dilation system 10 is represented by the balloon inflation hub 56 of the inner member 34 (best shown in FIG. 2B) and the proximal end 58 of the outer member 36.

[0073] 2B, 3A-3D, 4, and 5C, inner member (also referred to herein as the balloon catheter subsystem or pre-dilation balloon delivery subsystem) 34 is configured with an internal inflation channel 60 extending between the inflation hub 56 and the pre-dilation balloon member 44. The internal inflation channel 60 serves as a passageway for inflation air between a balloon inflation system 62 (shown diagrammatically in FIG. 2B) and the balloon member 44 for controlled inflation / deflation of the balloon member 44 as prescribed by the cardiac procedure.

[0074] The internal inflation channel 60 is defined by an inflation lumen hypotube 64 and an inflation lumen distal shaft 66 which are interconnected in a fluid tight manner and nested together.

[0075] The expansion hub 56, located at the proximal end 68 of the inner member 34, is configured with an internal conical channel 70 that is connected to the balloon expansion system 62 (as shown diagrammatically in FIG. 2B) by a proximal opening 72.

[0076] Balloon inflation system 62 may be a manual or automatic system. In a preferred automatic embodiment, balloon inflation system 62 includes an electronic subsystem, a pneumatic subsystem, and control software with a corresponding user interface. The electronic subsystem provides power to a solenoid pressure valve (fluidly connected to balloon inflation hub 56) to control the pressurization / depressurization of balloon member 44 with a fluid or air flow under the control of the control software.

[0077] 2B, the internal conical channel 70 of the balloon inflation hub 56 is configured with a distal opening 74 connected to the inflation lumen hypotube 64. The proximal end of the inflation lumen hypotube 64 is connected to the distal opening 74 of the internal conical channel 70 of the balloon inflation hub 56 in a fluid-tight manner to support the passage of inflation air between the balloon member 44 and the inflation system 62.

[0078] The inflation lumen hypotube 64 extends through the entire length of the proximal portion 38 and a portion of the intermediate portion 42 of the subject system 10, terminating at a distal end 78 in the distal portion 40, as shown in FIGS. 2B and 4.

[0079] 2B, a flexible serrated member 80 is provided at the proximal end 76 of the inflation lumen hypotube 64 which is connected to the distal end 82 of the balloon inflation hub 56. The serrated flexible member 80 supports the proximal end 76 of the inflation lumen hypotube 64 and provides for flexible bending of the structure as it is manipulated by the surgeon.

[0080] As shown in Figures 2A-2C, 3A-3D, 4, and 5C, the inflation lumen distal shaft 66 extends between the proximal portion 38 along the intermediate portion 42 and terminates at the distal portion 40. Figure 3A details the junction between the inflation lumen hypotube 64 and the inflation lumen distal shaft 66. The inflation lumen hypotube 64 does not extend all the way through the inner member 34, but rather terminates at a distal end 78 (as shown in Figures 2B and 4).

[0081] 3B-3D, the inflation lumen hypotube 64 has a skived distal portion 90 that is coaxially encased by the wall of the inflation lumen distal shaft 66, such that the inflation lumen hypotube 64 cooperates with the inflation lumen distal shaft 66 to provide a sealed fluid communication between the balloon inflation system 62 and the interior chamber 92 of the balloon member 44, as shown in FIGS. 5A-5C, for controlled inflation / deflation of the balloon member 44 as required in cardiac surgery.

[0082] 2B and 3C-D show that the inflation lumen distal shaft 66 is configured with a rapid exchange (RX) guidewire (GW) port 94 where the GW lumen 96 begins at its proximal end 98. The GW lumen 96 extends between the RX GW ports 94 inside the inflation lumen distal shaft 66 over the entire length of the distal portion 40 of the inner catheter 34. The GW lumen 96 forms an internal channel with a proximal end 98 corresponding to the RX GW port 94 and a distal end 100 corresponding to the outermost distal end 52 of the distal portion 40 of the inner member 34. As shown in FIGS. 6A-B, in the distal portion 40, the GW lumen 96 extends past the distal end 102 of the inflation lumen distal shaft 66. The distal end 100 of the GW lumen 96 constitutes a gradually tapered section 104 which may be in the form of a delivery microcatheter 46.

[0083] 2A-2B, 5A-5C, 6A-6B, and 24A-24B, the inner catheter (also referred to herein as the balloon catheter subsystem) 34 is configured with a tapered distal section (also referred to herein as a tapered distal tip) 162 at the distal portion 40. The tapered distal section 162 includes a pre-dilated balloon member 44 secured to the tapered distal section 162 proximate the microcatheter 46. The pre-dilated balloon member 44 is secured to the inner member's tapered distal section (tip) 162 to support a pre-dilation / stenting procedure as required for the treatment of the patient's heart.

[0084] The balloon member 44 has a proximal portion 112 and a distal portion 114. The balloon member 44 is attached (secured) to the distal portion 40 adjacent the delivery microcatheter 46 with the proximal portion 112 attached to the distal end 102 of the inflation lumen distal shaft 66 and the distal portion 114 of the balloon 44 attached to the outer surface of the microcatheter 46.

[0085] As shown in Figures 5A-5C, the pre-expansion balloon 44 is attached at its proximal portion 112 to the proximal portion 204 of the distal tip 162 that is aligned adjacent to the outer tip 164 of the sheath 120, and at its distal portion 114 to the distal end 166 of the distal portion (tip) 162 of the inner member 34.

[0086] The balloon member 44 can be intermittently in a contracted (folded) configuration and an inflated (expanded) configuration. The contracted (folded) configuration is used during insertion and / or withdrawal of the subject system from the blood vessel. The balloon is inflated (expanded) when in position (target site 22) to open the blood vessel and compress the plaque for a pre-dilatation procedure or a stenting procedure (if a stent is delivered to the treatment site on the balloon). When inflated, the balloon 44 is in the inflated / open configuration shown in Figures 2A and 2B, 5A, 5C, 6A and 6B, and 24A and 24B for pre-dilatation of the diseased blood vessel. When deflated, the balloon member 44 is in the contracted configuration shown in Figure 5B.

[0087] The balloon 44 can have a smooth surface, or a "chocolate" configuration. A "chocolate" balloon catheter is an over-the-wire balloon dilatation catheter with a braided shaft and an atraumatic tapered tip. The balloon is constrained by a Nitinol structure that creates small "pillows" and grooves in the balloon upon expansion.

[0088] 2A, 2C, 5A-5C, 7, 8A-8B, 9A, 9C-9D, 10A-10G, 11C, 12B-12C, 13A-13B, 14B, 15A-15D, 16A-16B, 17A-17B, 18A-18B, 19B, 20A-20B, 21, and 24A-24B, the outer catheter (also referred to as the guide catheter extension subsystem) 36 is formed with a cylindrical outer delivery sheath 120 having an inner channel 122 extending inwardly therealong. A coupler mechanism 130 is formed in surrounding relationship to a proximal end 132 of the cylindrical sheath 120.

[0089] At the proximal end 58, the outer catheter 36 includes an outer member pusher (also referred to herein as a pusher / puller) 134, which in one embodiment may be a solid wire that may have a rounded wire proximal portion 136 and a flattened distal portion 138 that may be welded or otherwise fixedly attached to the proximal end 132 of the sheath 130, as shown in Figures 10B-10G, 11A-11C, 12A-12C, 13A-13B, 14A-14B, 15A-15D, 16A-16B, 17A-17B, 18A-18B, 19B, and 22. In another embodiment, the push / pull element 134 may be constructed of a hypotube.

[0090] Alternatively, the round pusher wire can be welded to a flat wire, which is welded or otherwise securely attached to the proximal end 132 of the sheath 120.

[0091] In yet another alternative embodiment of the outer member 36, a round wire can be welded or otherwise secured to two flat wires, which are then welded or otherwise secured to the proximal end 132 of the sheath 120.

[0092] The flat profile of the pusher wire portion is welded to the proximal coupler 130 of the outer sheath 120 such that when the inner member 34 is inserted into the outer member (catheter) 36, the pusher wire does not create an obstruction to the rotational or longitudinal movement of the proximal coupler 130 of the outer member 36 and the inner catheter 34 inside the sheath 120 as required in the procedure. The proximal push-pull element 134 advances or retracts with the outer tubular sheath 120 and is preferably flexible (not rigid). The pusher / puller 134 may be flexible (not rigid) with a flexibility along its longitudinal axis that matches or exceeds the flexibility of the tubular outer delivery sheath 120 of the outer catheter 36.

[0093] For convenience to the surgeon performing the coronary intervention procedure in manipulating the outer member 36 to position the outer delivery sheath 120 together with the balloon delivery subsystem 34 at a desired location relative to the lesion 22 within the diseased vessel, the outer catheter pusher 134 may be provided at its proximal end with a proximal handle 140, shown in FIG. 10F.

[0094] The proximal push / pull element 134 (made of wire or hypotube) connected to the outer member tubular structure 120 has a small profile and is flexible (not "rigid") to achieve improved fit inside the guide catheter and a smaller profile than the rigid "push" elements in conventional guide extension catheters (such as Root). This is possible because of the "pushability" of the "whole system" achieved through the locked integral connection between the outer catheter (with the hypotube push element) and the inner catheter (guide extension tube).

[0095] Additionally, the inner catheter (inner member) 34 may include an inner member pusher (also referred to herein as a pusher / puller) 142 (shown in FIG. 2A ) that may be attached to the expansion hub 56 to facilitate withdrawal of the inner member 34 from the outer member 36 as required in a coronary intervention procedure and to control the engagement / disengagement therebetween during various stages of cardiac surgery. The inner member pusher / puller 142 may be formed with an inner member pusher / puller handle for convenience to the surgeon performing the procedure.

[0096] The handles of the pushers of the inner and outer members can be configured with a mechanism (detailed in U.S. patent application Ser. No. 15 / 899,603, incorporated herein by reference) that allows for additional releasable locking of the inner and outer members relative to one another to enhance integral cooperation of the inner and outer members in the engaged operating mode.

[0097] The inner member 34 may be in either an over-the-wire or RX configuration. In one of the embodiments detailed herein, the guidewire 12 extends through an RX GW port 94 formed at the proximal end of the tubular inflation lumen distal shaft 66 into the inner channel 146 of the GW lumen 96, as shown in Figures 3C and 3D and 4. In the distal portion 40 of the subject system 10, the guidewire 12 extends within the GW lumen along the delivery tapered microcatheter 46 (at the tapered portion 104) and exits from the distal end 100 of the GW lumen 96 at the outermost end 52 of the inner member 34, as shown in Figures 2A and 2B, 5A and 5B, and 6A and 6B.

[0098] The outer delivery sheath 120 of the outer member 36 is fabricated from a flexible cylindrical tubular body 150 that extends substantially the length of the intermediate portion 42 of the subject system 10. By manipulating the outer member pusher 134, the surgeon actuates the integral advancement of the outer delivery sheath 120 and the inner member 34 along the guide catheter 14. Once the pre-dilatation procedure has been performed (as will be detailed in further paragraphs), the surgeon controls the required linear rearward displacement of the inner member 34 relative to the sheath 120 of the outer member 36 by manipulating the outer member pusher 134 and / or the inner member pusher 142.

[0099] As shown in Figures 8A-8B and 9A-9D, the interface between the outer tip 164 of the sheath 120 and the distal tip 162 of the inner member 34 facilitates displacement of the distal tip 162 of the inner member 34 relative to the outer tip 164 of the sheath 120, essentially facilitating displacement of the distal tip 162 relative to the outer tip 164 of the sheath 120 as required in cardiac surgery.

[0100] The distal end 160 of the sheath 120, as well as the outer tip 164, are formed of a flexible material that allows for easy retraction of the distal tip 162 of the inner member 34 therethrough. A rectangular wire helical coil may be used for the distal end 160 of the sheath 120 and the outer tip 164.

[0101] At its proximal end 132, the sheath 120 of the outer catheter 36 is configured with an inlet "opening" (or "mouth") 210 whose circumference exceeds the circumference of the outer member flexible tubular sheath 120, as shown in Figures 10A-10G. The inlet 210 (also referred to herein as the "mouth") to the inner channel 122 of the sheath 120 can be configured in a variety of variations. For example, as shown in Figure 10A, the inlet 210 has a funnel shape 211 with an eccentric opening (as shown in Figure 10A), or contoured with a concentric obtuse angle (as shown in Figures 10B and 10C), or with a concentric slope (as shown in Figures 10D and 10E), or with a concentric concave contour (as shown in Figures 10F and 10G). The pusher 134 is attached to a predetermined point of the funnel-shaped outer catheter proximal inlet 210.

[0102] As shown in Figures 2A, 2C, 7, and 8A-B, the outer delivery sheath 120 of the outer catheter 36 extends between a proximal end 132 located at the intermediate portion 42 of the subject system 10 and a distal end 160 located at the distal portion 40. At the distal portion 40 of the subject guide catheter extension / pre-dilation system 10, the inner member 34 is configured in a tapered configuration 104 having a distal tapered portion (also referred to herein as a distal tapered tip) 162 that may be formed with a microcatheter 46, as shown in Figures 2A-B, 5A-B, 6A-B, 8A, 22A-B, and 24A-B. The microcatheter 46 is a long, thin member having a length in the cm range, e.g., 1-3 cm. The microcatheter 46 has a tapered conical profile shape at its distal end 52 with a diameter not exceeding 1 mm. The microcatheter 46 may be integrally formed with the tapered distal tip 162 of the inner member 34 .

[0103] 2A, 5A-5C, 7, and 8A-8B, at a distal end 160, the outer delivery sheath 120 is formed with an outer tip 164 having a tapered conical profile configuration that may be interconnected with a distal tip 162 of the inner member 34. The outer tip 164 of the outer member 36 provides a smooth distal taper transition between the distal end 160 of the sheath 120 and the distal portion 40.

[0104] 2A, 5A and 5B, 6A and 6B, 8A and 8B, 22A and 22B, and 24A and 24B, the distal tip 162 of the inner catheter 34 is shown to have a tapered configuration that gradually changes from the point of interconnection with the outer tip 164 of the sheath 120 to the distal end 166 of the distal tip 162. The microcatheter 46 extends from the distal end 166 of the distal tapered section 162 of the inner member 34 at an integral connection (approximately 1-3 cm in length) and terminates at the outermost distal end 52.

[0105] The subject guide catheter extension / pre-dilation system 10 can be configured to have a microcatheter flexibility differential with the distal portion being more flexible by either varying the durometer of the plastic (polymer) components from the proximal to the distal portion of the outer delivery sheath (i.e., a higher durometer in the proximal portion compared to the distal portion) and / or varying the frequency (pitch) of the windings of the helical coil of wire in the microcatheter 46 in the direction from the proximal to the distal portion, such that the distal portion of the microcatheter 46 is more flexible and trackable than the proximal portion of the microcatheter delivery device, has a significantly smaller profile, and is more flexible than the distal portion of the guide catheter extension subsystem (outer delivery sheath).

[0106] Additionally, the system 10 may include wires that are radiopaque so that the balloon member 44, microcatheter 46, and outer delivery sheath 120 may be easily visualized using fluoroscopy. It is envisioned that the distal tip 162 (as shown in FIG. 5A and in FIGS. 6A and 6B ) includes radiopaque markers 264, 266 near the proximal and distal portions 112, 114 of the balloon 44. The radiopaque markers 264, 266 allow the surgeon (operator) to visualize the location of the balloon member 44 relative to the lesion location 22.

[0107] Additionally, the outermost distal tip 52 of the microcatheter delivery portion 46 and the tip 160 of the sheath 120 can have one or more radiopaque markers 268, 270 (shown in FIGS. 2B and 5A) to allow the surgeon to distinguish the radiopaque markers, which is particularly important when the microcatheter is passing through an occlusive lesion and a balloon member carried adjacent the microcatheter is held in place.

[0108] 7, in one embodiment, the outer catheter 36 is configured with a catheter shaft coil reinforcement system 170 disposed on (or embedded in) the inner surface 152 of the sheath 120. Preferably, a lubricious liner 172 is disposed inside the shaft 120. The shaft reinforcement coil 170 may be disposed inside the shaft 120 in contact with the lubricious liner 172, i.e., in surrounding relationship with the surface of the lubricious liner 172 that covers the inner surface 152 of the shaft 120. A distal soft tip jacket 174 is attached to the distal end of the outer catheter shaft 120 along a longitudinal axis 176 of the outer catheter 36.

[0109] The distal soft tip jacket 174 may be adhered to the shaft 120 at the end 175 (as shown in FIG. 7) or may cover a length of the outer surface 173 of the shaft 120 .

[0110] A distal soft tip jacket 174 extends past the coil reinforcement 170 and the lubricious liner 172 at the distal end 160 of the shaft 120 and terminates in a tapered section 178 having a distal edge 184 and a proximal edge 182 .

[0111] The lubricious liner 172 may be formed from a PTFE material. The distal soft tip jacket 172 may be formed from a highly flexible, low durometer elastomeric Pebax material that transitions to a higher durometer along the longitudinal axis 176 toward the proximal end 132 of the sheath 120.

[0112] 7 and 8A-8B, in one preferred embodiment, the inner diameter of the sheath 120 at the inner surface 152 is about 0.048 inches, while the outer diameter of the shaft 120 at the outer surface 173 is 0.058 inches. The inner diameter of the tapered section 178 of the outer catheter 36 at its distal edge 184 is about 0.045 inches, while the outer diameter of the tapered section 178 at its distal edge 184 is about 0.047 inches. The slope between the outer diameter of the sheath 120 (0.058 inches) and the outer diameter of the taper 178 (0.047 inches) defines the taper of the outer surface, while the slope between the inner diameter of the sheath 120 (0.048 inches) and the inner diameter of the taper 178 at its distal edge 184 (0.045 inches) defines the taper of the inner surface. The distal wall 180 of the tapered section 178 has a decrease in thickness from the interface 182 (between the sheath 120 and the tapered section 178 ) to the outermost edge 184 of the tapered section 178 of the distal soft tip jacket 174 .

[0113] 7 in conjunction with FIGURES 8A and 8B, the outer diameter of the tapered element 104 of the inner catheter has an outer diameter of approximately 0.046 inches, which is approximately 0.001 inches larger than the inner diameter (0.045 inches) of the distal tip of the outer catheter at its outermost distal edge 184. This difference between the outer diameter of the tapered element 104 of the inner catheter 34 and the inner diameter at the distal edge 184 of the outer tip 164 of the outer catheter results in stretching of the distal soft tip jacket 174 in the tapered section 178 when it interferes with the tapered element 104 of the inner catheter. Such a configuration provides a nearly seamless transition between the distal tip of the inner catheter 34 and the distal tip of the outer catheter 36, as well as a compact distal profile due to compression of the distal tip of the inner catheter 34 by the tapered element 178 of the outer catheter 36. When the inner catheter 34 is removed, the elastomeric properties of the distal tip of the distal soft tip jacket 174 of the outer catheter 36 allow the tapered section 178 to return to its original inside diameter (0.045 inches).

[0114] In the unengaged operating mode, the inner diameter of the wall 180 of the tapered outer tip 164 of the outer member 36 is smaller than the outer diameter of the inner member 34. In the engaged operating mode, the tapered outer tip 164 of the outer member 36 and the inner member 34 interact such that the dimensional transition between the outer diameter of the tapered outer tip 164 of the sheath lumen 120 and the outer diameter of the distal portion of the inner member 34 forms a substantially step-free boundary transition therebetween.

[0115] 9A-9D, several embodiments of expandable tapered designs are contemplated for the tapered section 178. As shown in FIG. 9A, the elasticity of the distal tapered section 178 of the outer catheter 36 is increased by an expandable split ring 190 affixed to the tapered section 178 that allows the distal outer tip 164 to expand (when interfacing with the inner catheter 34). The expandable split ring 190 has slits 192 that allow the ring 190 to expand and contract in response to interference at the distal end between the inner and outer catheters. This structure provides additional reinforcement to prevent permanent deformation of the tapered section 178 upon removal of the inner catheter 34 and delivery of a stent (or balloon).

[0116] 9B, in an alternative embodiment of the outer catheter 36, the tapered section 178 may be configured with an expandable tip scaffold 194 fabricated from NiTi wire and configured with a distal end 196 and a proximal end 198 having a diameter larger than that of the distal end 196. Due to its flexibility, the expandable scaffold 194 expands and contracts as needed to provide additional support to resist permanent deformation of the jacket 174 at the tapered section 178 upon removal of the inner catheter and delivery of a stent or balloon member.

[0117] Another alternative embodiment of the tapered section 178 at the distal end of the sheath 120 is shown in Figures 9C and 9D where the wall 180 of the tapered section 178 is shaped with a slit 200 extending longitudinally along the length of the tapered section 178 that flares apart along its circumference. When the tapered section 178 interfaces with the distal end of the inner member 34, the slit 200 temporarily flares to accommodate the distal tip 162 of the inner catheter 34. This design can prevent permanent deformation of the jacket 174 at the tapered section 178 that can be caused by removal of the inner catheter 34 or during delivery of a stent / balloon.

[0118] An important "seamless" aspect of the subject system is that the transition between the outer diameter of the outer tip 164 of the sheath 120 (at its tapered portion 178) and the outer diameter of the distal tip 162 of the inner member 34 forms a substantially gradual (smooth) transition therebetween.

[0119] As shown in Figures 2C, 10A-10G, 11A-11C, 12A-12C, 13A and 13B, 14A and 14B, and 15A-15D, the subject system is constructed in the intermediate portion 42 by an interconnection mechanism 220 including a proximal coupler 130 formed at the proximal end 132 of the sheath 120 of the outer member 36, and a cooperating mechanism 222 formed on the outer surface of the inner member 34 (as shown in Figures 17A and 17B, 18B, 19A and 19B, and 20A-20C).

[0120] The subject guide catheter extension / pre-dilatation system 10 can operate in an inner / outer catheter engagement mode and an inner / outer catheter decoupling mode, which is accomplished by controlling an interconnect mechanism 220. The subject interconnect mechanism 220 is configured to engage / disengage the inner and outer catheters 34, 36 (as required in cardiac surgery) while preventing undesired forward displacement of the inner member 34 inside the outer delivery sheath 120. The engagement mode of operation allows for improved "pushability" of the "whole system" (with the outer catheter 36 connected and locked to the inner catheter 34), even though the connected push / pull element 134 of the outer member 36 is configured as a small profile flexible element (as flexible as or more flexible than the outer tubular sheath 120 of the outer catheter 36).

[0121] The interconnection unit 220 operates based on interference between the proximal coupler 130 configured on the proximal end 132 of the sheath 120 and the cooperating mechanism 222 configured on the outer surface 224 of the inner member 34 when the inner surface 152 of the tubular body 150 of the sheath 120 (at the proximal end 132) engages with the outer surface 224 of the cooperating mechanism 222 (on the inner member 34).

[0122] By way of example, several interconnection mechanisms are envisioned that may be applied to the subject guide catheter extension / pre-dilatation system 10. The subject engagement mechanisms are configured for controllable engagement / disengagement between the inner member 34 and the outer member 36, as well as preventing forward movement of the inner member 34 relative to the outer delivery sheath 120 beyond a predetermined position.

[0123] For example, as shown in Figures 11A-11C, the laser cut coupler 130 can be comprised of a proximal open (split) ring 240 and a pair of distal rings including a solid distal ring 242 and an open (split) distal ring 244. The proximal open ring 240 and the distal rings 242 and 244 are integrally formed with a coupler base 246. The coupler 130 can be formed from stainless steel or heat set NiTi. The pusher / puller element 134 and the shift mid coupler (also referred to herein as the proximal coupler) 130 of the outer catheter 36 can be made from a memory metal (such as, for example, Nitinol) to prevent deformation during antegrade or retrograde movement of the outer member and to prevent deformation of the mid-shaft coupler 130 as a stent (or other device) passes through the mid-shaft portion of the outer catheter 36.

[0124] The open ring 240 is correlated to the proximal inlet opening (e.g., funnel-shaped) 211 of the outer catheter 36 (shown in Figs. 10A, 10D, 10E, and 11C). The proximal open ring 240 allows the inlet 211 to expand into the funnel 210 as needed for the entry / removal of the inner catheter 34 as needed in the surgical procedure. As shown in Figs. 10A, 10D, 10E, and 11A-11C, the proximal open ring 240 provides support for the proximal opening 210 of the funnel-shaped proximal end of the sheet 120. The proximal ring 240 reinforces the inlet opening ("mouth") 211, prevents damage or permanent deformation of the inlet opening, and supports the elastic properties of the sheath 120 at the inlet opening 210. The distal rings 242, 244 form a snap-fit ​​locking mechanism that is separate from the proximal open ring 240 of the funnel. The distal ring 242 does not expand (is the outline of a closed circle), but the opening of the split ring 244 widens upon displacement of the inner catheter 34 relative to the proximal coupler 130 of the outer catheter 36 .

[0125] The base 246 of the coupler 130 may be flat or preferably slightly arcuate (in cross section) to match the cooperating distal end 250 of the pusher 134, which has either a flat or crescent (in transverse) profile, as shown in Figures 11B and 11C. The pusher 134 may be fabricated from stainless steel or NiTi. The distal end 250 of the pusher 134 is welded (glued, adhered, or otherwise attached) to the base member 246 of the coupler 130. A PTFE liner 172 (also shown in Figure 7) may encase the coupler 130, as shown in Figure 11C.

[0126] The sheath 120 is disposed in surrounding relationship to the coupler and a PTFE liner 172. A Pebax encapsulation similar to the distal soft tip jacket 174 at the distal end 160 of the sheath 120 (shown in FIG. 7) may be used at the proximal end 132 of the sheath 120. The length of the catheter shaft coil reinforcement 170 (also shown in FIG. 7) at the distal end of the outer catheter 36 may extend to the proximal end of the outer catheter 36.

[0127] As shown in Figures 11A-11C, 17A-17C, and 18A-18B, the cooperating mechanism 222 for the particular embodiment shown in Figures 11A-11C further includes a shaft mid-locking ring 252 (shown in Figures 17B, 17C, and 18B) for a snap-fit ​​lock.

[0128] Another embodiment of the outer catheter proximal inlet configuration shown in FIGS. 12A-12C is similar to that shown in FIGS. 11A-11C, with certain modifications including the following. (a) additional thickness and additional material around the base 246 of the coupler 130; (b) modified surface treatment (e.g., bead blasting) to improve adhesion of the polymer encapsulation, and (c) the use of encapsulation with a hard polymer (such as nylon) to provide additional support to the funnel to prevent damage that could prevent passage of the stent.

[0129] An additional embodiment of coupler 130 at the proximal inlet 210 (shown in FIGS. 13A and 13B) features an open ring (rib) 256 that reinforces the inlet port 210. A snap-fit ​​lock 260 is represented by at least two open rings 262 at the distal end of coupler 130. Coupler 130 is preferably a laser cut coupler formed from either stainless steel or heat set NiTi, as shown in the variation shown in FIGS. 13A and 13B.

[0130] The hypotube pusher / puller 134 may be flattened at its distal end 250 and is welded to the base 246 of the coupler 130. A PTFE liner 172 extends under the coupler 130 and a Pebax encapsulation 174 encases the coupler 130 with the pusher 134 attached. A catheter shaft coil reinforcement structure 170 extends along the shaft 120 of the outer catheter 36 from its distal end to its proximal end. A snap-fit ​​lock 260 cooperates with a circular ring embodiment of the cooperating mechanism 222 shown in Figures 17A-17C and 18B. In some embodiments, the encapsulation 174 and / or the pusher / puller 134 may be color coated with a prominent color, as shown in Figure 11A, to distinguish the outer member pusher / puller 134 from other elements of the subject configuration for the convenience of the surgeon and safety of the procedure.

[0131] 14A and 14B, the coupler 130 has individual rings 266, 268 welded to the distal end 250 of the pusher 134. As shown, the locking mechanism 260 is formed by a solid distal ring 266 and an intermediate split ring 268, with each ring 266, 268 welded to the pusher 134. A proximal tapered split ring 270 is also welded to the pusher 134. This design provides increased flexibility regarding the size and configuration of each ring 266, 268, and 270 and supports the creation of a variety of funnel shapes / sizes as opposed to laser cut couplers which are limited to a single diameter.

[0132] 15A and 15B show another variation of the proximal coupler 130 featuring a funnel window that improves contrast injection flow rate by providing an additional open cross-sectional path for fluid flow. As shown in FIGS. 15A and 15B, circular openings 272 are formed in the sheath 120. The openings 272 are arranged in a predetermined pattern that is unobstructed by the proximal split ring 274 and distal rings 276, 278 of the snap-fit ​​locking structure 280. As shown in FIGS. 15C and 15D, the coupler 130 is formed with triangular openings 282 formed in the sheath 120 in a manner that is unobstructed by the proximal and distal rings 274, 278, 276 of the snap-fit ​​locking structure 280.

[0133] Although only circular and triangular openings 272, 282, respectively, are shown in Figures 15A-15D, other configurations of cutouts in the plastic encapsulation are contemplated in the subject anatomy to allow injected contrast fluid to pass through the cutouts.

[0134] 16A, 16B, and 16C, another embodiment of the proximal end of the outer catheter 36 is shown, which is specifically designed as a potential solution to prevent undesirable embolic situations in the event of air inadvertently being injecting with fluid between the inner and outer catheters 34, 36. To prevent this, a flush lumen 290 is incorporated into the pusher 134 via a flat hypotube. A luer hub is connected to the proximal end of the hypotube (pusher 134) as shown in FIG. 16C, thus allowing the surgeon to inject fluid between the inner and outer catheters via the hypotube 134. When fluid enters the outer catheter lumen 292 via a channel 290 in the hypotube 134, the ingress of air bubbles between the inner and outer catheters is prevented.

[0135] 17A-17C, the interconnection unit 220 between the proximal couplers 130 shown in FIGS. 11A-11E, 12A-12C, 13A-13B, 14A-14B, and 15A-15D includes a cooperating member 222 in the form of an annular circular ring 252 (also referred to herein as an intermediate locking ring) formed on the outer surface 224 of the inner catheter 34. The stainless steel annular ring 252 is contoured with a fully rounded surface that allows for minimal reversible engagement / disengagement from the required split ring mechanism of the outer catheter coupler 130. The ring 252 shown in FIG. 17C has a rounded contour on the outer surface 302 for a smooth locking / unlocking action. The inner surface 304 of the ring 252 is also a smooth structure that engages with the outer surface 224 of the inner catheter 34.

[0136] Figure 17A shows a disconnected configuration of the inner catheter 34 relative to the outer catheter 36. Figure 17B depicts a locked and engaged configuration when the inner catheter 34 is received and locked inside the opening 210 at the proximal end of the sheath 120 such that the ring 252 engages the snap-fit ​​lock 306 formed by the distal solid ring 308 and the middle split ring 310. When in this position, the proximal angled split ring 312 surrounds the inner catheter 34 and the ring 252 is locked into the snap-fit ​​lock 306, thus engaging the inner and outer catheters for surgical manipulation as required in the surgical procedure.

[0137] During longitudinal movement of the inner catheter 34 inside the outer catheter 36, as the ring 252 passes the proximal angled split ring 312 and the middle split ring 310, the arms of these rings are spread apart from their original positions to provide sufficient space for the passage of the ring 252. When in place, i.e., when the ring 252 is received between the rings 308 and 310, the arms of the angled split ring 312 and the split ring 310 return to their original closed positions. The ring 252 is captured between the rings 308, 310 and locked therebetween with a snap fit, thus preventing relative displacement of the inner and outer catheters.

[0138] 18A and 18B, which detail the structure shown in Figures 17A-17C, show that a portion (pocket) 316 of the sheath 120 of the outer catheter 36 is not reinforced by the coil 170 and flexes when the mid-shaft locking ring 252 is inserted between the solid distal ring 308 and the mid-split ring 310 of the snap-fit ​​lock 306. The flexed portion 316 of the sheath 120 between the rings 308 and 310 provides additional retention force to maintain the inner catheter 34 and outer catheter 36 in locked engagement.

[0139] A stainless steel annular ring 252 can be attached to the outer surface 224 of the inner catheter shaft 34 by adhesive. The shape of the locking ring (perfectly circular surface) allows for smooth reversible engagement / disengagement with the laser cut features of the coupler 130 of the outer catheter. The distal ring 308 of the snap-fit ​​lock 306 prevents further distal movement of the inner catheter 34, while the middle split ring 310 opens upon contact with the shaft mid-locking ring 252, providing a tactile snap. The proximal angled split ring 312 allows the funnel 211 to open to a larger inner diameter than the inner diameter of the remainder of the shaft 120. It also allows for smooth passage of the shaft mid-locking ring 252.

[0140] Interference between the unreinforced shaft pocket 316 and the shaft mid-locking ring 252 provides retention of the inner catheter 34 to the outer catheter 36 until the user attempts to remove the inner catheter 34 from the outer catheter 36, thus disengaging the snap-fit ​​lock between the two. The force required to disengage the locking mechanism can be adjusted from 0.1 to 2.0 pounds.

[0141] 19A-19C, another alternative embodiment of the shaft mid-lock is shown that includes a square annular ring 320 (formed of a metal or polymeric material). Unlike the ring 252 shown in FIGS. 17A-17C and 18B, the ring 320 has a square cross-section 321 as shown in FIG. 19C. The square annular ring 320 is attached to the outer surface 224 of the inner catheter 34 using a heat-sealed Pebax encapsulation 322. Alternatively, it may be glued to the outer surface 224 of the inner catheter. As shown in FIG. 19B, when the inner catheter is in the locked position, the square annular ring 320 snaps into a snap-fit ​​lock 324 formed by a solid ring 326 and a split ring 328, such that the encapsulation 322 contacts the inner surface 152 of the sheath 120 and the ring 320 sits between the rings 326 and 328.

[0142] In a further alternative embodiment shown in Figures 20A-20C, the mid-shaft locking mechanism 220 is formed with a cooperating member 222 in the form of a cage-like structure 330 having two NiTi rings 332, 334 connected to each other via several (e.g., four) NiTi shape-setting wires 336. As shown in Figure 20A, the cage 330 is attached to the outer surface 224 of the inner catheter 34 by either adhesive or heat-sealed Pebax encapsulation 338. Each of the wires 336 has an arcuate extension 340 left free from the encapsulation 338 as shown in Figures 20A and 20B.

[0143] 20B, in the locked configuration, the cage structure 330 fits into the coupler 130 of the outer catheter. An unencapsulated arcuate portion 340 of each wire 336 extends away from the wires 336 of the cage 330 outside of the encapsulation 338. When the cage 330 is received between the ring 342 and split ring 344 of the snap-fit ​​mechanism 346, the locking mechanism 346 is actuated and the inner and outer catheters 34, 36 are engaged.

[0144] With further reference to FIG. 21, the proximal coupler 130 of the outer catheter 36 can include two locking slots 350 , 352 formed by rings 354 and 356 connected by a connecting element 358 .

[0145] 17A-17C, 18A and 18B, 19A and 19B, 20A-20C, as well as 10A-10G, 11A-11C, 12A and 12B, 13A and 13B, 14A and 14B, 15A-15D, and 21, when the surgeon linearly displaces the inner member 34 within the internal channel 122 of the proximal coupler 130, the snap-fit ​​annular ring 252, 320, or cage 330 enters the channel 122 between the arms of the proximal rings 240, 312, which flexibly bend outward to allow forward movement of the inner catheter 34 (towards the distal tip 162). As the snap-fit ​​annular ring 252, 320 or cage 330 passes further through the intermediate split ring 244, 262, 268, 310, 328 of the snap-fit ​​locking mechanism, the arms of the angled proximal ring return to their original position while the arms of the intermediate split ring flex outward to allow the ring 252, 320 of the cage 330 to be positioned between the distal solid ring and the intermediate split ring. When the ring / cage 252, 320, 330 snaps between the rings of the snap-fit ​​locking mechanism, the arms of the intermediate split ring return to their original position.

[0146] To separate the inner member 34 from the outer member 36, the surgeon pulls the inner member 34 from the interior channel of the proximal coupler 130. In removing the snap-fit ​​annular ring / cage 252, 320, 330 from the channel, the pulling action bends the arms of the intermediate split ring outwardly, allowing the snap-fit ​​annular ring / cage 252, 320, 330 to pass between them, thus releasing the inner catheter 34 from the proximal coupler 130 of the outer catheter 36.

[0147] 3D , the inflation lumen distal shaft 66 of the intermediate section 42 of the subject guide catheter / pre-dilation extension system 10 can be manufactured with a braided reinforcement structure 260. The braided reinforcement member 260 forms a somewhat flexible tube that is connected to a cooperating mechanism 222 of the interconnect unit 220 of the inner member 34. A RX (Rapid Exchange) port 94 can be formed through the wall of the braided reinforced inflation lumen distal shaft 66 for passing a guidewire 12 therethrough.

[0148] The braided reinforcement structure 260 may consist of a metal pattern or wire within the braided reinforced inflation lumen distal shaft 66 to prevent kinking which would impart longitudinal stiffness to the shaft 66. The metal braid 260 may be embedded in the braided reinforced shaft 66 to add increased flexibility necessary for retraction of the inner member 34 relative to the outer delivery sheath 120 during surgery.

[0149] A helical coil of rectangular wire (e.g., made from a shape memory alloy such as Nitinol) having a wire thickness of about 1 mil to 3 mils can be embedded in the braid 260. The coil can be formed with a very thin coating of plastic disposed on its inner and outer surfaces, which facilitates reducing the wall thickness of the inflation lumen distal shaft 66 to less than 7 mils, preferably about 5 mils.

[0150] The principle of reinforcing a tubular member with or forming a tubular member from a catheter shaft coil reinforcement 170 in the form of a rectangular wire helical coil 262 can be applied to the outer delivery sheath 120 (as shown in Figures 7, 8B, 9A-9D, 10A, 11C, 12B and 12C, 13A and 13B, 14B, 15A-15C, 16A and 16B, 17A and 17B, 18A and 18B, 19B, 20B, and 21) and the microcatheter 46 (as shown in Figures 2A and 2B, 5A, 22, and 24A-24B) in the subject guide catheter extension / pre-dilation system 10. The outer delivery sheath 120 and / or the microcatheter 46 may have such rectangular wire helical coils embedded in predetermined locations along the length of their walls, such as at the proximal and / or distal ends.

[0151] Alternatively, the entire length of the outer delivery sheath 120 and / or microcatheter 46 can be formed with a rectangular wire helical coil. The pitch between the coils can be adjusted to provide a gradient of flexibility along the length of the tubular member (sheath 120 and / or microcatheter 46) that increases toward the distal end to facilitate an atraumatic procedure.

[0152] 22A-22B and 23A-23C, rather than utilizing a standard over-the-wire (OTW) guidewire lumen, a monorail rapid exchange (RX) design of the inner catheter 34' can be implemented to allow for the use of a short guidewire. In the embodiment shown in FIGS. 22A-22B, which depict an isometric view of a subject coil-reinforced inner member shaft 400 and a side view thereof taken along line AA, the distal portion 40' of the inner member 34' includes a tapered element 402 attached to the outer surface 224 of the inner member 34. The outer shaft 400 of the inner member 34' is a coil reinforced with a coil reinforcement structure 404 that extends from a distal tip 406 to the RX inlet port 94 shown in FIGS. 2A-2C and 3C-3D. The distal tip 406 is a tapered soft tip that interfaces with the inner surface of the outer catheter 36 along with the tapered element 402 when the inner catheter 34' is loaded into the outer catheter 36 as required in a surgical procedure.

[0153] The distal portion 40' includes a concentric guidewire lumen 408 that communicates with the RX inlet port at the proximal end of the inner catheter 34 (shown in Figures 2A-2C and 3C-3D).

[0154] As shown in Figures 23A-23C, the proximal end 412 of the monorail microcatheter embodiment shown in Figures 22A and 22B utilizes a machined hypotube pusher 414. The proximal end 412 of the coil reinforced inner member shaft 416 and the hypotube pusher 414 are encased within a proximal outer jacket 418 that extends from (and includes) the coil reinforced inner member shaft 416 (which functions as the guidewire lumen 408) and the hypotube pusher 414, shown in Figures 22A and 22B as a tube along the proximal end 412 of the monorail microcatheter embodiment of the inner member 34'.

[0155] 23A and 23B features an RX guidewire "notch" termination / entrance 420 that is fabricated by puncturing the proximal outer jacket 418. The coil reinforced inner member shaft 416 is then inserted into the proximal outer jacket tube 418 via the RX entry "notch" 420. A machined hypotube 415 is further inserted into the proximal outer jacket tube 418 via its lumen 422, and the polymers of the coil reinforced inner member shaft 416 and the proximal outer jacket tube 418 are fused together to connect the inner member shaft 416 and the pusher 414, thus forming the proximal end 412 of the monorail microcatheter inner member 34'.

[0156] For the convenience of the surgeon, the push / pull element 134 of the outer catheter 36 can be color coated, as shown in Figure 11A, to have a distinctive color to distinguish it from other elements of the system, such as the push / pull element of the inner catheter 34, as well as the usual gray or silver color of the coronary guidewire or stent delivery system used to deliver the device. Alternatively, the proximal outer jacket 418 of the push / pull element 414 may be color coated such that its color is distinct from the colors of other elements in the system of interest.

[0157]

[00113] With further reference to Figures 24A and 24B, which depict an embodiment 500 of an additional coil-reinforced balloon catheter of the inner catheter, this structure combines the reinforced shaft characteristics of the microcatheter 46 with the reinforced shaft characteristics of the dilatation balloon 44 having the following attributes: a. the coil reinforced shaft 502 provides additional kink resistance and pushability while still maintaining flexibility to navigate tortuous vasculature; b. The longer distal tip 504 of the structure includes a small profile tapered soft tip for easily crossing stenoses and narrow lesions.

[0158] 24A and 24B, the distal portion 504 of the subject structure 500 includes an inner member shaft 500 reinforced with a coil reinforcement structure 506 that extends the length of the inner member shaft 500. A distal tapered element 508 is disposed on the inner member shaft 500 and extends between ends 510 and 512 in surrounding relationship to the inner member shaft 500. A distal tapered soft tip 514 may be in the form of a microcatheter 46 disposed at the end of the coil reinforced shaft 500.

[0159] 22A and 22B, balloon member 44 is disposed on inner member shaft 500 and radiopaque markers 264 and 266 are disposed on inner member shaft 500 within balloon member 44. At its proximal end 516, balloon member 44 interfaces with outer tip 164 of proximal tapered element 178 of outer member sheath 120. At its distal end 518, balloon member 44 closely surrounds shaft 500.

[0160] 1-24B, in operation to perform a cardiac procedure, and in particular a pre-dilatation routine, the proximal end of the coronary guidewire 12 is threaded into the RX port 94 formed in the inflation lumen distal shaft 66, through the inner channel (GW lumen 96) of the inner member 34, and extended toward and past the outermost distal end 52 of the microcatheter 46. The guide catheter 14 is then advanced into the blood vessel 16 of the target.

[0161] The outer delivery sheath 120 of the outer member 36, with the inner member 34 locked therein, is then initially placed into the inner channel 48 of the guide catheter 14 along with the microcatheter 46, and both the inner and outer members 34, 36 as a single unit are advanced together within the guide catheter 14 towards the treatment site 22. The outer member sheath 120 and the inner member 34 can be displaced together by pushing the outer member pusher 134. This action causes the microcatheter 46 of the inner member 34 to slide along the GW 12 with the outer member 36 until it extends past the distal end 50 of the guide catheter 14 and reaches the lesion site 92. At this stage of the procedure, the balloon member 44 is in a deflated configuration.

[0162] The guidewire 12 extending past the distal end 50 of the guide catheter 14 serves as a guide for sliding the microcatheter 46 (with the deflated balloon 44 attached to its distal tip 162) toward the treatment site 26.

[0163] The balloon member 44 (positioned at the treatment site 22) is then inflated by a balloon inflation system 62 connected to the inflation hub 56 via an inflation lumen formed by the inflation lumen distal shaft 66 and the inflation lumen hypotube 64 to compress the plaque and widen the blood passageway within the blood vessel 16.

[0164] Subsequently, once the lesion has been dilated, the balloon 44 can be deflated and the outer delivery sheath 120 can be advanced across the lesion 22 as an integral unit with the inner member 34 (in the engaged operating mode), after which the inner member can be decoupled (unlocked) from the outer delivery sheath 120 and removed from the sheath 120.

[0165] Alternatively, inner member 34 can be decoupled and withdrawn from sheath 120 immediately after lesion dilation, while outer member 36 is advanced across lesion 22.

[0166] The sheath 120 may be left in place proximal to the treatment site (immediately after dilation of the lesion).

[0167] After inner member 34 is retracted, the stent may be delivered to site 22. The stent may be introduced in its closed configuration inside sheath 120 into vessel 16. Once in place, a stent support balloon (not shown) may be inflated to open the stent. Outer delivery sheath 120 is then removed, leaving the open stent in vessel 16.

[0168] While the invention has been described with reference to particular forms and embodiments thereof, it will be understood that various modifications other than those mentioned above may be resorted to without departing from the spirit or scope of the invention as defined in the appended claims. For example, elements specifically illustrated and described may be replaced with functionally equivalent elements, certain features may be used independently of other features, and in certain cases, the location of certain elements, steps or processes may be reversed or interleaved, all of which does not depart from the spirit or scope of the invention as defined in the appended claims. [Appendix 1] 1. An intravascular delivery system configured for controllably displacing a blood vessel of a subject, the delivery system having a proximal portion, a distal portion, and an intermediate portion located between the proximal portion and the intermediate portion, the delivery system comprising: an outer member formed by a flexible, substantially cylindrically contoured, elongated outer delivery sheath defining a sheath lumen having a proximal end and a distal end, the outer delivery sheath extending between the intermediate portion and the distal portion, the outer member configured with a tapered outer tip at the distal end of the sheath lumen; an outer member, the tapered outer tip of the outer member at the distal end of the outer delivery sheath comprising a wall extending in a cylindrical manner between distal and proximal edges of the tapered outer tip, the wall having an inner diameter and an outer diameter, the inner diameter and the outer diameter of the wall gradually decreasing in a direction from the proximal edge to the distal edge of the tapered outer tip; an inner member having an elongate body defining an interior channel extending along a longitudinal axis and extending along an interior of the sheath lumen of the outer member in controllable relationship with the outer delivery sheath, an inner member, the elongate body of the inner member having an outer diameter and a tapered distal portion configured with a tapered delivery catheter having an elongate body length, the tapered delivery catheter being displaceable past the distal end of the sheath, the wall of the tapered outer tip of the outer member at least temporarily interfaces with the distal portion of the inner member, the inner diameter of the wall of the tapered outer tip of the outer member being less than the outer diameter of the distal portion of the inner member at the interface between the wall of the tapered outer tip of the outer member and the distal portion of the inner member; an interconnect mechanism disposed in operative association with the inner and outer members, the interconnect mechanism being controllably actuable to operate the guide catheter extension / pre-dilatation subsystem in an engaged or disengaged mode of operation; It is equipped with in the engaged mode of operation, the inner and outer members of the guide catheter extension subsystem are engaged for controllably displacing together along a guidewire, the inner member being unable to independently displace relative to the outer member when engaged; An intravascular delivery system, wherein in the separated mode of operation, the inner and outer members are separated to retract the inner member from the outer member. [Appendix 2] the tapered distal section of the inner member interfaces at its outer surface with an inner surface of the tapered outer tip of the sheath lumen; the tapered outer tip of the outer member is an elastomeric tapered outer tip; in the separated mode of operation, the inner diameter of the wall of the tapered outer tip of the outer member is smaller than the outer diameter of the inner member; 2. The intravascular system of claim 1, wherein in the engaged operating mode, the tapered outer tip of the outer member and the inner member interact such that a dimensional transition between an outer diameter of the tapered outer tip of the sheath lumen and an outer diameter of the distal portion of the inner member forms a substantially step-free interface therebetween. [Appendix 3] 2. The system of claim 1, wherein the sheath is reinforced along its length and the outer member further comprises a distal soft tip encapsulating material at its distal end that encapsulates the reinforced sheath of the outer member, the distal soft tip encapsulating material being a flexible, low durometer elastomeric material having an increasing gradient durometer value from the distal end to the proximal end of the sheath. [Appendix 4] 4. The system of claim 3, wherein the outer member further comprises a distal lubricous liner sandwiched between an outer surface of the sheath and an inner surface of the distal soft tip encapsulation material. [Appendix 5] the delivery catheter is a microcatheter; a balloon member attached to the tapered distal portion of the inner member proximate to the tapered delivery microcatheter; an inflation lumen extending within the inner member between the balloon members of the proximal and distal portions and providing a fluid passage between an external balloon inflation system and the balloon members; 2. The system of claim 1, further comprising: [Appendix 6] 6. The intravascular system of claim 5, wherein the balloon member has a proximal portion having a proximal diameter that is greater than a distal outer diameter at its distal portion. [Appendix 7] 6. The intravascular system of claim 5, wherein the balloon member has an inflated state and a deflated state, and in the deflated state, the balloon member is displaced within the blood vessel, and the balloon member is controllably changed to the inflated state after being positioned at least in alignment with a treatment site for a pre-dilatation procedure. [Appendix 8] 6. The system of claim 5, wherein the elongate body of the inner member and the microcatheter are coil reinforced along their lengths, and the tapered distal portion of the inner member comprises a distal taper element disposed on the coil reinforced elongate body. [Appendix 9] 3. The system of claim 2, wherein the outer delivery sheath of the outer member has a tubular body having a first predetermined circumference, the tubular body of the outer member extending between the tapered outer tip at the distal end of the outer delivery sheath and the proximal end, at which the outer delivery sheath is configured with an entrance opening having a second predetermined circumference, the second predetermined circumference of the entrance opening exceeding the first circumference of the tubular body of the outer delivery sheath. [Appendix 10] 10. The system of claim 9, wherein the tapered outer tip of the outer member has a resiliently expandable configuration and the entrance opening at the proximal end of the outer sheath is contoured into a funnel shape. [Appendix 11] an outer member pusher configured with a flattened portion at a distal end and secured to the proximal end of the sheath of the outer member; Further equipped with 3. The intravascular system of claim 2, wherein the outer member pusher is configured with a channel extending along its length, the channel communicating with the sheath lumen. [Appendix 12] 12. The intravascular system of claim 11, wherein the outer sheath of the outer member is a flexible sheath having a first flexibility along its length and the outer member pusher is a flexible member having a second flexibility along its length, the second flexibility being substantially the same as or greater than the first flexibility. [Appendix 13] 2. The intravascular system of claim 1, wherein the interconnection mechanism comprises a snap-fit ​​mechanism comprising a proximal coupler disposed at a proximal end of the sheath of the outer member and a cooperating element disposed on an outer surface of the elongate body of the inner member, the proximal coupler comprising a distal solid ring and an intermediate split ring disposed a predetermined distance from the solid ring, the cooperating member comprising a member selected from the group comprising a shaft intermediate locking ring, a square annular ring, and a snap-fit ​​cage, the cooperating member being attached to the outer surface of the elongate body of the inner member and releasably locked in a snap-fit ​​manner between the distal solid ring and the intermediate split ring to engage the outer and inner members. [Appendix 14] 14. The intravascular system of claim 13, wherein the cooperating member is secured to the outer surface of the inner member in surrounding relationship thereto, and the proximal coupler further includes a proximal angled split ring at a proximal end thereof. [Appendix 15] 15. The system of claim 14, further comprising a window system formed in the sheath at its proximal end. [Appendix 16] 6. The intravascular system of claim 5, wherein the microcatheter is formed of a flexible material having differential flexibility along its length, the flexibility of the microcatheter increasing toward its distal end. [Appendix 17] 17. The intravascular system of claim 16, wherein the microcatheter includes a rectangular wire helical coil extending along the length of the microcatheter, the pitch of the rectangular wire helical coil varying along the length of the microcatheter such that the flexibility of the microcatheter increases toward its distal end. [Appendix 18] The intravascular system of claim 1, further comprising a rectangular wire helical coil member forming at least a portion of a wall of each of the members selected from the group consisting of the outer delivery sheath of the outer member, the delivery catheter, the elongate body of the inner member, and combinations thereof, wherein the rectangular wire helical coil is formed of a shape memory alloy such as Nitinol or is formed of a radiopaque material. [Appendix 19] the tapered delivery catheter structure being a microcatheter formed with a longitudinally extending lumen for sliding along a guidewire; an inner member pusher coupled at a distal end thereof to a proximal end of the inner member; an outer member pusher coupled at a distal end thereof to the proximal end of the outer member; Further comprising: 2. The intravascular system of claim 1, wherein the outer member pusher is color coated, the color coating having a color distinct from the color of the guidewire and the color of the inner member and the inner member pusher. [Appendix 20] 1. An intravascular system comprising a guide catheter extension subsystem cooperating with a guidewire, comprising: A guide catheter extension subsystem having a proximal portion, a distal portion, and an intermediate connecting portion interconnected between the proximal and distal portions. Equipped with The guide catheter extension subsystem includes: an outer member formed by a flexible, substantially cylindrically contoured, elongated sheath having a reinforcing structure along the sheath, the sheath defining a sheath lumen having a proximal end and a distal end, the sheath extending between the intermediate connection portion and the distal portion of the guide catheter extension subsystem, the outer member having a distal soft elastomeric tip disposed at a distal end of the sheath lumen, the distal soft elastomeric tip configured with a cylindrical wall having a thickness that decreases from a proximal edge to a distal edge of the distal soft elastomeric tip, the wall having an inner diameter at the distal edge; an inner member having a coil reinforced elongate body defining an interior channel extending along a longitudinal axis, the inner member extending internally along the sheath lumen in controllably displaceable relationship with the sheath, the inner member having a tapered distal section at its distal end configured with a tapered delivery catheter structure, the tapered distal section of the inner member having a length of coil reinforced elongate body, the inner member elongate body having an outer diameter that exceeds the inner diameter of the wall of the outer member distal soft elastomeric tip, the tapered distal section of the inner member resiliently interfaces at its outer surface with an inner surface of the distal soft elastomeric tip of the sheath, the tapered delivery catheter structure being displaceable past the distal end of the sheath; an interconnection mechanism disposed in operative association with the inner and outer members of the guide catheter extension subsystem and controllably actuated to intermittently operate the guide catheter extension subsystem in an engaged or disengaged mode of operation, wherein in the engaged mode of operation, the outer surface of the tapered distal tip of the inner member and the outer surface of the wall of the distal soft elastomeric tip of the outer member form a substantially smooth transition therebetween; The present invention is configured to include In the engaged mode of operation, the inner and outer members of the guide catheter extension subsystem engage together for controllably displacing along a guidewire; An intravascular system, wherein in the decoupled mode of operation, the inner and outer members are decoupled for controllable, independent linear or rotational displacement relative to one another. [Appendix 21] 21. The system of claim 20, wherein the sheath is configured with an entrance opening at a proximal end thereof having an outer circumference that exceeds an outer circumference of the tubular body of the sheath, the entrance opening being reinforced by an angled split ring element attached proximate to the entrance opening. [Appendix 22] further comprising a guidewire capable of being advanced within a subject's vasculature to at least a treatment site; the guide catheter extension subsystem is configured to be controllably displaced along the guidewire; an inner member pusher coupled at a distal end thereof to a proximal end of the inner member; an outer member pusher coupled at a distal end thereof to the proximal end of the outer member; an elastomeric jacket encasing the inner member at least at the proximal end thereof and encasing the inner member pusher at least along the distal end thereof; Including, 21. The intravascular system of claim 20, wherein the tapered delivery catheter structure is a microcatheter formed with a longitudinally extending lumen for sliding along the guidewire. [Appendix 23] 23. The intravascular system of claim 22, wherein the outer member pusher is color coated, the color coating having a color distinct from the color of the guidewire and the color of the elastomeric jacket surrounding the inner member and the inner member pusher.

Claims

1. 1. An intravascular delivery system configured for controllably displacing a blood vessel of a subject, the delivery system having a proximal portion, a distal portion, and an intermediate portion located between the proximal portion and the distal portion, the delivery system comprising: an outer member formed by a flexible, substantially cylindrically contoured, elongated outer delivery sheath defining a sheath lumen having a proximal end and a distal end, the outer delivery sheath extending between the intermediate portion and the distal portion and configured with a tapered outer tip, the proximal end of the outer member outer delivery sheath configured to have a mouth, the mouth configured with a funnel shape having an off-center opening; an outer member, the tapered outer tip of the outer member at the distal end of the outer delivery sheath comprising a wall extending in a cylindrical manner between distal and proximal edges of the tapered outer tip, the wall having an inner diameter and an outer diameter, the inner diameter and the outer diameter of the wall gradually decreasing in a direction from the proximal edge to the distal edge of the tapered outer tip; an inner member having an elongate body defining an interior channel extending along a longitudinal axis and extending along an interior of the sheath lumen of the outer member in controllable relationship with the outer delivery sheath, an inner member, the elongate body of the inner member having a proximal end and a tapered distal portion configured with a tapered delivery catheter having an outer diameter and an elongate body length, the tapered delivery catheter being displaceable past the distal end of the outer delivery sheath, the wall of the tapered outer tip of the outer member at least temporarily interfaces with the distal portion of the inner member, and the inner diameter of the wall of the tapered outer tip of the outer member at the interface between the wall of the tapered outer tip of the outer member and the distal portion of the inner member is less than the outer diameter of the distal portion of the inner member; an interconnection mechanism controllably actuable to operate the inner and outer members in an engaged or separated mode of operation, the interconnection mechanism including a proximal coupler formed at the proximal end of the outer delivery sheath of the outer member and a cooperating mechanism formed on an outer surface of the inner member, the proximal coupler including a proximal split ring and a pair of distal rings including a solid distal ring and a split distal ring, the proximal split ring correlating with a mouse funnel shape, the solid distal ring and the split distal ring forming a snap-fit ​​locking mechanism separate from the proximal split ring; It is equipped with in the engaged mode of operation, the inner and outer members are engaged for controllably displacing together along a guidewire, the inner member being unable to independently displace relative to the outer member when engaged; An intravascular delivery system, wherein in the separated mode of operation, the inner and outer members are separated to retract the inner member from the outer member.

2. the tapered distal portion of the inner member interfaces at its outer surface with an inner surface of the tapered outer tip; the tapered outer tip of the outer member comprises an elastomeric material; in the separated mode of operation, the inner diameter of the wall of the tapered outer tip of the outer member is smaller than the outer diameter of the inner member; 2. The intravascular delivery system of claim 1, wherein in the engaged mode of operation, the tapered outer tip of the outer member and the inner member interact such that a dimensional transition between the inner diameter of the wall of the tapered outer tip and the outer diameter of the inner member forms a substantially step-free interface therebetween.

3. 2. The intravascular delivery system of claim 1, wherein the outer delivery sheath is reinforced along its length, and the outer member further comprises a distal soft tip encapsulating material at its distal end that encapsulates the outer delivery sheath of the outer member, the distal soft tip encapsulating material being a flexible, low durometer elastomeric material having an increasing gradient of durometer from the distal end to the proximal end of the outer delivery sheath.

4. The intravascular delivery system of claim 3 , wherein the outer member further comprises a distal lubricous liner sandwiched between an exterior surface of the outer delivery sheath and an interior surface of the distal soft tip encapsulation material.

5. the tapered delivery catheter is a microcatheter; a balloon member attached to the tapered distal portion of the inner member proximate to the tapered delivery microcatheter; an inflation lumen extending within the inner member between the balloon members of the proximal and distal portions and providing a fluid passage between an external balloon inflation system and the balloon members; The intravascular delivery system of claim 1 , further comprising:

6. The intravascular delivery system of claim 5 , wherein the balloon member has a proximal portion having a proximal diameter that is greater than a distal outer diameter at a distal portion thereof.

7. 6. The intravascular delivery system of claim 5, wherein the balloon member has an inflated state and a deflated state, in which the balloon member is displaced within the blood vessel, and the balloon member is controllably changed to the inflated state after being positioned at least in alignment with a treatment site for a pre-dilatation procedure.

8. The intravascular delivery system of claim 5 , wherein the elongate body of the inner member and the microcatheter are reinforced with coils along their lengths.

9. 3. The intravascular delivery system of claim 2, wherein the outer delivery sheath of the outer member has a tubular body having a first predetermined circumference, the tubular body of the outer member extending between the tapered outer tip at the distal end and the proximal end of the outer delivery sheath, at the proximal end where the outer delivery sheath is configured with an entrance opening having a second predetermined circumference, the second predetermined circumference of the entrance opening exceeding the first predetermined circumference of the tubular body of the outer delivery sheath.

10. The intravascular delivery system of claim 9 , wherein the tapered outer tip of the outer member has a resiliently expandable configuration.

11. an outer member pusher configured with a flattened portion at a distal end and secured to the proximal end of the outer delivery sheath of the outer member; Further equipped with The intravascular delivery system of claim 2 , wherein the outer member pusher is configured with a channel extending along its length, the channel communicating with the sheath lumen.

12. 12. The intravascular delivery system of claim 11, wherein the outer delivery sheath of the outer member is a flexible outer delivery sheath having a first flexibility along its length and the outer member pusher is a flexible member having a second flexibility along its length, the second flexibility being substantially the same as or greater than the first flexibility.

13. 2. The intravascular delivery system of claim 1, wherein the cooperating mechanism includes a member selected from the group including a mid-shaft locking ring, a square annular ring, and a snap-fit ​​cage, and the cooperating mechanism is attached to the outer surface of the elongate body of the inner member.

14. The intravascular delivery system of claim 13 , wherein the cooperating feature is secured to the outer surface of the inner member in surrounding relationship therewith.

15. The intravascular delivery system of claim 14, further comprising a fenestration system formed in the outer delivery sheath at a proximal end thereof.

16. 6. The intravascular delivery system of claim 5, wherein the microcatheter is formed of a flexible material having differential flexibility along its length, the flexibility of the microcatheter increasing towards its distal end.

17. 17. The intravascular delivery system of claim 16, wherein the microcatheter includes a rectangular wire helical coil extending along the length of the microcatheter, the pitch of the rectangular wire helical coil varying along the length of the microcatheter such that the flexibility of the microcatheter increases toward its distal end.

18. 2. The intravascular delivery system of claim 1, further comprising a rectangular wire helical coil member forming at least a portion of a wall of each of the members selected from the group consisting of the outer delivery sheath of the outer member, the delivery catheter, the elongate body of the inner member, and combinations thereof, wherein the rectangular wire helical coil is formed of a shape memory alloy such as Nitinol or is formed of a radiopaque material.

19. the tapered delivery catheter being a microcatheter formed with a longitudinally extending lumen for sliding along a guidewire; an inner member pusher coupled at a distal end thereof to the proximal end of the inner member; an outer member pusher coupled at a distal end thereof to the proximal end of the elongate body of the outer member; Further comprising: The intravascular delivery system of claim 1 , wherein the outer member pusher is color coated, the color coating having a color distinct from the color of the guidewire and the color of the inner member and the inner member pusher.

20. The intravascular delivery system of claim 1 , wherein the cooperating mechanism includes an annular ring.

21. The intravascular delivery system of claim 1 , wherein the solid distal ring is not expanded and the opening of the split distal ring widens upon relative displacement of the inner member to the proximal coupler of the outer delivery sheath.

22. The intravascular delivery system of claim 1 , wherein the proximal split ring provides a funnel-shaped support for the mouse at the proximal end of the outer delivery sheath.

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