Patent Description:
Arteries of the heart, and more specifically coronary arteries, may sometimes be occluded or narrowed by atherosclerotic plaques or other lesions. These afflictions are generally referred to as coronary heart disease or a stenosis, and result in inadequate blood flow to distal arteries and tissue. Heart bypass surgery may be a viable surgical procedure for certain patients suffering from coronary heart disease. However, traditional open surgery may inflict significant patient trauma and discomfort and require extensive recuperation times. Further, life threatening complications may occur due to the invasive nature of the surgery and the necessity for stoppage of the heart during such a surgery.

To address these concerns, efforts have been made to perform interventional cardiology procedures using minimally invasive techniques. In an example, percutaneous transcatheter (or transluminal) delivery and implantation of interventional coronary devices are employed to overcome the problems presented by traditional open surgery. In such a procedure, a guide catheter is first inserted through an incision into a femoral (transfemoral), or radial (transradial) artery of a patient. For example, the Seldinger technique may be utilized in either method for percutaneously introducing the guide catheter. In such methods, the guide catheter is advanced through the aorta and inserted into the opening of an ostium of a coronary artery. A guidewire, or other interventional coronary devices, such as a catheter mounted stent and/or balloon catheter, may be introduced through the guide catheter and maneuvered/advanced through the vasculature and the stenosis of the diseased coronary artery. However, when attempting to pass through a difficult stenosis, or when conducting a radial intervention using a small diameter guide catheter, the guide catheter may not have adequate back support, and continued application of force to advance the interventional coronary device though the stenosis may cause the distal end of the guide catheter to dislodge from the opening of the ostium of the coronary artery, resulting in potential damage to the surrounding tissue.

In order to prevent the guide catheter from dislodging, interventional cardiologists sometimes would deep seat the guide catheter into the coronary artery. The term "deep seat" or "deep seating" means that the guide catheter would be pushed farther downstream into the coronary artery. However, deep seating the guide catheter risks the guide catheter damaging the coronary artery wall (dissection or rupture), occluding the coronary artery, and interfering with blood flow to the coronary artery.

One attempt to provide additional support to a guide catheter that has gained acceptance is the use of a guide extension catheter. The guide extension catheter is deployed within a lumen of the guide catheter and extends distally from the distal end of the guide catheter into the coronary artery. Their smaller size, as compared to the guide catheter, allows the guide extension catheter to be seated more deeply in the coronary artery with less potential damage. The guide extension catheter provides additional support to the guide catheter to aid in delivery of interventional coronary devices. In cases with a difficult stenosis or radial interventions, the use of the guide extension catheter reduces the risk of dislodging the guide catheter from the opening of the ostium of the coronary artery during treatment. However, their smaller size may pose difficulty in receiving an interventional coronary device within the passageway of the distal shaft of the guide extension catheter. As an example, an interventional coronary device such as a catheter with a stent mounted on an outer surface of a balloon may catch, snag, or otherwise become snared on the entry port of the distal shaft of the guide extension catheter.

Accordingly, there exists a need for an improved guide extension catheter that provides easier entry into the passageway of the distal shaft and reduces catching, snagging or snaring of interventional coronary devices advancing into the passageway.

Embodiments hereof relate to a guide extension catheter including a push member and a distal shaft. The push member includes a segment having a first surface and a second surface opposite the first surface. The segment includes a groove in the first surface. The second surface of the segment is substantially flat. The distal shaft is coupled to the push member and includes a passageway. The segment of the push member including the groove adjacent the distal shaft. Further features of the guide extension catheter of the present invention are defined in claim <NUM>.

Embodiments hereof further relate to a coronary treatment system including a guide extension catheter of claim <NUM>, a guide catheter, and an interventional coronary device wherein the groove of the push member is configured to guide the interventional device into the passageway of the distal shaft. The guide catheter includes a lumen configured to receive the guide extension catheter and the interventional coronary device therethrough.

The foregoing and other features and advantages of the invention will be apparent from the following description of embodiments thereof as illustrated in the accompanying drawings.

Specific embodiments of the present invention are now described with reference to the figures, wherein like reference numbers indicate identical or functionally similar elements. The terms "distal" and "proximal" are used in the following description with respect to a position or direction relative to the treating clinician. "Distal" and "distally" refer to positions distant from or in a direction away from the clinician. "Proximal" and "proximally" refer to positions near or in a direction toward the clinician.

Although the description of embodiments hereof are in the context of treatment of blood vessels such as the coronary arteries, the invention may also be used in any other body passageways where it is deemed useful. The description uses the unit "inch", wherein <NUM> inch corresponds to <NUM>.

<FIG> illustrates a coronary treatment system <NUM> including a guide extension catheter <NUM>, a guide catheter <NUM>, and an interventional coronary device <NUM>. The guide catheter <NUM> and the guide extension catheter <NUM> are configured to deliver the interventional coronary device <NUM> to a desired treatment location. In the embodiment shown in <FIG>, the desired treatment location is in a coronary artery CA that is accessed through the aorta AA.

The guide catheter <NUM> may be utilized to access the aorta AA as shown in <FIG>. Generally, the guide catheter <NUM> includes a lumen sized to receive an auxiliary device or devices (e.g. the guide extension catheter <NUM> and/or the interventional coronary device <NUM>). The guide catheter <NUM> is configured to deliver the auxiliary device(s) such as the guide extension catheter <NUM> and the interventional coronary device <NUM> to a desired treatment location.

The interventional coronary device <NUM> may be any device suitable for treating an abnormal condition of a coronary artery, such as, but not limited to a stenosis. Non-limiting examples of interventional coronary device <NUM> include guidewires, balloon catheters, stent catheters, and FFR catheters.

<FIG> illustrate the guide extension catheter <NUM> in accordance with an embodiment hereof. Referring to <FIG>, the guide extension catheter <NUM> includes a push member <NUM> coupled to a distal shaft <NUM>. The push member <NUM> is coupled to the distal shaft <NUM> at a transition joint <NUM>. In an embodiment, the guide extension catheter <NUM> may be approximately <NUM> in length, with the distal shaft <NUM> of the guide extension catheter <NUM> being between <NUM> and <NUM> in length. However, this is not meant to limit the design and the guide extension catheter <NUM> and/or the distal shaft <NUM> thereof may be longer or shorter.

The push member <NUM>, also referred to as a proximal shaft or pushwire, includes a proximal end <NUM> and a distal end <NUM>. The push member <NUM> is configured to transfer motion applied at the proximal end <NUM> to the distal end <NUM>. Further, the push member <NUM> is configured to transfer motion applied to the proximal end <NUM> to the coupled distal shaft <NUM> coupled to the push member <NUM>. Stated more plainly, the push member <NUM> is configured such that movement of the push member <NUM> also moves the distal shaft <NUM>.

In the invention, the push member <NUM> includes a proximal segment <NUM>, an intermediate segment <NUM>, and a distal segment <NUM>. The proximal segment <NUM> extends distally from the proximal end <NUM> of the push member <NUM>, the distal segment <NUM> extends proximally from the distal end <NUM> of the push member <NUM>, and the intermediate segment <NUM> is disposed between the proximal segment <NUM> and the distal segment <NUM>. The push member <NUM> may be formed of materials such as, but not limited to stainless steel, nickel-titanium alloys (e.g. NITINOL), high performance alloys that are cobalt, chromium, molybdenum and/or nickel based (e.g. MP35N, L605, ELGILOY), or other materials suitable for the purposes described herein.

As shown in <FIG> and <FIG>, the intermediate segment <NUM> of the push member <NUM> is generally rectangular in cross-section, and includes a first surface <NUM> and a second surface <NUM> opposite the first surface <NUM>. The first surface <NUM> and the second surface <NUM> are both substantially flat. The term "flat" as used herein means that the surfaces are horizontal or not curved such that if a flat surface were placed on a table, the flat surface and the table surface would be parallel. The term "substantially" or "generally" as used herein, particularly with respect to the term "flat", means within normal manufacturing tolerances. The proximal segment <NUM> may be generally rectangular in cross section, similar to the intermediate segment <NUM>, but need not be. The proximal segment <NUM> may be other shapes in cross-section, such as generally circular, oval, oblong, or other shapes suitable for the purposes described herein.

As shown in <FIG>, the intermediate segment <NUM> of the push member <NUM> includes a groove <NUM> formed in the first surface <NUM>. The groove <NUM> faces an extended central longitudinal axis LA1 of the distal shaft <NUM>. The groove <NUM> is configured to guide the interventional coronary device <NUM> into a passageway <NUM> of the distal shaft <NUM>. The groove <NUM> includes a proximal end <NUM> and extends distally to a distal end <NUM>. The groove <NUM> is tapered from the distal end <NUM> to the proximal end <NUM>. "Tapered" as used herein, means that the groove <NUM> becomes progressively smaller from the distal end <NUM> to the proximal end <NUM>. In other words, the groove <NUM> becomes progressively larger from the proximal end <NUM> to the distal end <NUM>. In the embodiment of <FIG>, the groove <NUM> has a first depth D1 and a first width W1 at the proximal end <NUM>, as shown in <FIG>, and a second depth D2 and a second width W2 at the distal end <NUM>, as shown in <FIG>. The first depth D1 is less than the second depth D2, and the first width W1 is less than the second width W2. Thus, as shown in <FIG>, which are cross-sectional illustrations of the intermediate segment <NUM> of the push member <NUM>, the groove <NUM> begins at the proximal end <NUM> with the first width W1 and the first depth D1, and the groove <NUM> widens and deepens distally along the length of the groove <NUM>. Thus, <FIG> shows an intermediate point between the proximal end <NUM> and the distal end <NUM> where the groove <NUM> has a third width W3 and a third depth D3, which are larger than the first width W1 and the first depth D2, respectively, but smaller than the second width W2 and the second depth D2, respectively. In an embodiment, the groove <NUM> widens and deepens linearly as the groove <NUM> extends distally. However, this is not meant be limiting, and the groove <NUM> may have other profiles, including non-linear profiles. In an embodiment, the first depth D1 of the groove <NUM> may be between <NUM> and <NUM> (<NUM> inch and <NUM> inch) inclusive and the second depth D2 may be betweent <NUM> and <NUM> (<NUM> inch and <NUM> inch) inclusive. By "inclusive" it is meant that the values at each end of the range are included in the range. In an embodiment, the first width W1 of the groove <NUM> may be between <NUM> and <NUM> (<NUM> ibnch and <NUM> inch) inclusive and the second width W2 may be between <NUM> and <NUM> (<NUM> inch and <NUM> inch) inclusive.

The groove <NUM> is formed in the first surface <NUM> of the intermediate segment <NUM> of the push member <NUM> by methods such as, but not limited to a skiving/swaging process, laser removal process, other mechanical removal processes, or other processes suitable for the purposes described herein.

As shown in <FIG> and <FIG>, a surface <NUM> of the groove <NUM> at the distal end <NUM> of the groove <NUM> is aligned with an inner surface <NUM> of an adjacent portion of the distal shaft <NUM>. An embodiment for enabling this alignment is shown in <FIG>, <FIG>, and <FIG>. In particular, the distal segment <NUM> of the push member <NUM> extends distally from a distal end <NUM> of the intermediate segment <NUM>. The distal segment <NUM> includes a proximal end <NUM> abutting the distal end <NUM> of the intermediate segment <NUM>, and a distal end <NUM>. In the embodiment shown in <FIG>, <FIG>, and <FIG>, the distal segment <NUM> extends distally from the distal end <NUM> of the intermediate segment <NUM> such that a shoulder <NUM> is formed between the surface <NUM> of the groove <NUM> and an upper surface <NUM> of the distal segment <NUM>. Stated another way, the shoulder <NUM> is formed where the distal end <NUM> of the intermediate segment <NUM> meets the proximal end <NUM> of the distal segment <NUM>. In the embodiment of <FIG>, <FIG>, and <FIG>, a shoulder <NUM> is also formed between the second surface <NUM> of the intermediate segment <NUM> and a lower surface <NUM> of the distal segment <NUM>. The distal segment <NUM> of the push member <NUM> may be formed by a separate piece attached to the intermediate segment <NUM>, or by methods such as, but not limited to, a laser removal process, machining, or other processes suitable for the purposes described herein. While the distal segment <NUM> is shown in <FIG> with a rectangular cross-section with a smaller width than the intermediate segment <NUM>, this is not meant to limit the design and other cross-sectional shapes and widths of the distal segment <NUM> may be utilized. For example, and not by way of limitation, distal segment <NUM> may be curved to match the curvature of the distal shaft <NUM>.

Although the proximal segment <NUM>, the intermediate segment <NUM>, and the distal segment <NUM> of the push member <NUM> have been described as a single component, this is not meant to be limiting. The proximal segment <NUM>, the intermediate segment <NUM>, and/or the distal segment <NUM> may be formed as separate components and coupled together to form the push member <NUM>.

In an embodiment, the distal shaft <NUM> includes a proximal end <NUM> and a distal end <NUM>. The distal shaft <NUM> is generally tubular and includes a wall <NUM> and the passageway <NUM>, as shown in <FIG>, <FIG>, <FIG>, and <FIG>. The passageway <NUM> is sized to receive the interventional coronary device <NUM>. The distal shaft <NUM> may be formed of various materials, non-limiting examples of which include polymers and braided polymers.

In the embodiment of <FIG>, a transition joint <NUM> between the push member <NUM> and the distal shaft <NUM> includes the distal segment <NUM> of the push member <NUM> and a proximal portion <NUM> of the distal shaft <NUM>. The transition joint <NUM> may be formed by overlapping the distal segment <NUM> of the push member <NUM> and the proximal portion <NUM> of the distal shaft <NUM>, with the distal segment <NUM> disposed between layers of the distal shaft <NUM>. The transition joint <NUM> is thus configured to couple the push member <NUM> to the distal shaft <NUM> and to transfer motion of the push member <NUM> to the distal shaft <NUM>. In other embodiments, the distal segment <NUM> of the push member <NUM> may be attached to the distal shaft <NUM> such that the upper surface <NUM> of the distal segment <NUM> is attached to an outer surface of the wall <NUM> of the distal shaft <NUM>, or such that the lower surface <NUM> of the distal segment <NUM> is attached to an inner surface of the wall <NUM>. The distal segment <NUM> may be attached to the wall <NUM> via a mechanical bonding (e.g. adhesives, welding, thermal bonding, clips, etc.) or other bonds suitable for the purposes described herein.

<FIG> illustrates an example of the distal shaft <NUM>, wherein the distal shaft <NUM> includes an inner liner <NUM>, an outer jacket <NUM> and a support structure <NUM>. The inner liner <NUM> is of a generally tubular shape and forms an inner surface <NUM> of the distal shaft <NUM>. The inner liner <NUM> is configured to provide the distal shaft <NUM> with a low friction inner surface such that the interventional coronary device <NUM> may be advanced/retracted easily through the passageway <NUM> of the distal shaft <NUM>. The inner liner <NUM> may be formed from materials such as, but not limited to polytetrafluoroethylene (PTFE), perfluoroalkoxy alkanes (PFAs), high-density polyethylene (HDPA), or other materials suitable for the purposes described herein. The outer jacket <NUM> is of a generally tubular shape and forms an outer surface <NUM> of the distal shaft <NUM>. The outer jacket <NUM> is configured to provide flexibility to the distal shaft <NUM>. The outer jacket <NUM> may be formed from materials such as, but not limited to, thermoplastic elastomers, such as but not limited to polyether block amides (e.g. PEBAX®, VESTAMID®), nylon, or other materials suitable for the purposes described herein. The support structure <NUM> is a generally tubular helically wound wire member <NUM> (also known as a filament). The support structure <NUM> is embedded between the inner liner <NUM> and the outer jacket <NUM>. The support structure <NUM> is configured to provide strength and rigidity to the distal shaft <NUM>. The support structure <NUM> may be bonded between the inner liner <NUM> and the outer jacket <NUM> by methods such as, but not limited to heat, fusion, adhesives, or other suitable methods. The support structure <NUM> may be formed from materials such as, but not limited to, stainless steel, nickel-titanium alloys (e.g. NITINOL), or other materials suitable for the purposes described herein.

Referring back to <FIG>, a method for delivery the coronary interventional device to a desired treatment location not forming part of the invention may be described. The guide catheter <NUM> is advanced into the aorta AA and a distal end of the guide catheter <NUM> is disposed within an opening of an ostium OS of the coronary artery CA.

The guide extension catheter <NUM> is advanced through the guide catheter <NUM> until the distal end <NUM> of the distal shaft <NUM> is disposed distal of the distal end <NUM> of the guide catheter <NUM>, and within the coronary artery CA proximal of the desired treatment location.

The interventional coronary device <NUM> is advanced through the guide catheter <NUM> adjacent or alongside the push member <NUM> of the guide extension catheter <NUM>, as shown in <FIG>. As the interventional coronary device <NUM> is advanced distally, a distal portion of the interventional coronary device <NUM> rides in the groove <NUM> (not visible in <FIG>, but shown in <FIG>) of the push member <NUM> of the guide extension catheter <NUM>. The groove <NUM> guides the interventional coronary device <NUM> into the proximal end <NUM> of the distal shaft <NUM>. More specifically, and as best shown in <FIG>, an outer surface of the interventional coronary device <NUM> (visible in <FIG>) may ride along the surface <NUM> of the groove <NUM>. The outer surface <NUM> of the interventional coronary device <NUM> may be shaped similar to the groove <NUM> such that the interventional coronary device <NUM> is guided along the groove.

Claim 1:
A guide extension catheter (<NUM>) comprising:
a push member (<NUM>) including a segment (<NUM>) having a first surface (<NUM>) and a second surface (<NUM>) opposite the first surface, wherein the segment (<NUM>) includes a groove (<NUM>) in the first surface (<NUM>) and wherein the groove has a surface (<NUM>), and wherein the second surface is substantially flat; and
a distal shaft (<NUM>) having a proximal section (<NUM>) and coupled to push member at a transition point and including a passageway, characterized in that the push member includes a proximal segment (<NUM>), an intermediate segment (<NUM>), and a distal segment (<NUM>), wherein the segment with the groove is the intermediate segment (<NUM>), wherein the distal segment (<NUM>) has an upper surface (<NUM>), wherein the push member further comprises a shoulder (<NUM>) disposed between a distal end (<NUM>) of the intermediate segment (<NUM>) and a proximal end (<NUM>) of the distal segment (<NUM>) such that the shoulder is disposed between the first surface (<NUM>) of the intermediate segment (<NUM>) and the upper surface (<NUM>) of the distal segment (<NUM>), and wherein the shoulder (<NUM>) is formed between the surface (<NUM>) of the groove (<NUM>) and the upper surface (<NUM>) of the distal segment (<NUM>), and wherein the intermediate segment (<NUM>) of the push member including the groove is disposed adjacent the distal shaft (<NUM>),
wherein the transition joint (<NUM>) is formed by overlapping the distal segment (<NUM>) of the push member (<NUM>) and the proximal portion (<NUM>) of the distal shaft (<NUM>), and
wherein the surface (<NUM>) of the groove (<NUM>) at the distal end (<NUM>) of the groove (<NUM>) is aligned with an inner surface (<NUM>) of an adjacent portion of the distal shaft (<NUM>).