Peel-away sheath assembly

Abstract

To provide a system and a method for a multi-layer peel-away sheath assembly for insertion of a blood pump including a sheath body.SOLUTION: A sheath body comprises multiple layers including a reinforcing layer 320. The reinforcing layer improves flexibility and kink resistance of the assembly. The reinforcing layer can comprise LCP, PEBAX, stainless steel, Nitinol, or Kevlar(R). The reinforcing layer may be a laser-cut hypotube or a braided or coiled filament. A first layer material and a third layer material are thermoplastics, including PEBAX or TPU. The reinforcing layer has at least one of discontinuous parts 322, 324, which is aligned with peel-away lines in the sheath body to allow an operator to peel-away the assembly. The peel-away lines are formed of inner, outer notches, or both.SELECTED DRAWING: Figure 3B

Description

[Technical Field]

[0001] Related Applications This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 672,212, filed May 16, 2018, the contents of which are incorporated herein as Appendix A, and to U.S. Provisional Patent Application No. 62 / 802,454, filed February 7, 2019, the contents of which are incorporated herein as Appendix B. [Background technology]

[0002] background After a patient suffers a heart attack, a mechanical circulatory assist device is often introduced to support the heart's function. In some indications, a heart pump is inserted into the heart through the patient's vascular system to help unload the heart. The pump may be configured to draw blood from the heart's left ventricle and push it into the aorta; or to draw blood from the inferior vena cava (IVC), bypassing the right atrium and right ventricle, and pushing the blood into the pulmonary artery. Some systems operate the pump with an onboard motor, while others operate the pump with an external motor. Still other systems use an extracorporeal pump with a long cannula that reaches the heart through the patient's vascular system. Other systems use a pump that does not enter the heart but remains in the aorta or other blood vessels.

[0003] Mechanical circulatory assist devices (e.g., intracardiac heart pump assemblies) or other medical devices can be introduced into a patient in a variety of ways. A common approach is surgical or percutaneous introduction into the vascular system during a cardiac procedure. For example, catheterization using a sheath, such as a peel-away introducer sheath, can be applied to the femoral artery. In another approach, the sheath can be inserted through an axillary or subclavian insertion site. Alternatively, the sheath can be inserted elsewhere, such as into the femoral vein or any pathway for delivery of a pump to support the left or right side of the heart.

[0004] An introducer sheath can be inserted through the arteriotomy into the femoral artery to form an insertion pathway for the pump assembly. A portion of the device is then advanced through the lumen of the introducer sheath and into the artery. Once the device (e.g., the pump assembly) is inserted, the introducer sheath is peeled away. A repositioning sheath can then be advanced, for example, over the pump assembly and into the arteriotomy. Replacing the introducer sheath with a repositioning sheath during insertion of the medical device can reduce limb ischemia and bleeding at the cutaneous insertion site (or intravascular insertion site) by improving fixation of the repositioning sheath to the patient when used with a hemostatic valve.

[0005] Peel-away sheaths offer the advantage of creating vascular access and allowing passage of a medical device, with the option of removing the sheath by peeling it into two sections. As referred to herein, a sheath can be an introducer sheath; a repositioning sheath; or any other peel-away sheath used with a vascular device.

[0006] A flexible, kink-resistant introducer sheath is desirable due to the bending forces the sheath experiences as it is introduced along the introduction path. The path follows the axis of the sheath through a superficial arteriotomy, then through tissue and into the vessel. The path is oblique to the surface of the patient's skin at the insertion site. After reaching the vessel, the sheath transitions to follow the vessel's (e.g., femoral artery) path. The insertion angle can vary based on the individual patient, procedure, and practitioner using the sheath. The vessel axis can vary depending on the patient and the portion of the vasculature into which the introducer sheath is placed. The angle between the insertion axis and the vessel axis affects the risk of sheath kinking. The angle can range from approximately 15° to approximately 75°, depending on the patient and the location of the procedure. The greater this angle, the greater the likelihood of the introducer sheath kinking during axial transitions. Because any sheath has a finite length, a larger insertion angle is typically required for deeper vessels to maintain the minimum desired portion of the introducer (2 cm to 5 cm) in the artery. Clinicians using ultrasound typically use a larger insertion angle to aid in visualization of the access needle, ultimately resulting in a larger sheath insertion angle. In obese patients, some femoral insertions are prone to kinking because the vessels are relatively deep relative to the insertion point. Tortuosity, particularly in the iliac region, can also cause the sheath to kink. Percutaneous axillary insertions, in particular, require deeper insertion angles and larger insertion angles compared to femoral insertions to avoid impinging on nerve bundles adjacent to the axillary insertion site. Therefore, introducer sheaths used during percutaneous axillary insertions, such as subclavian percutaneous axillary insertions, are more prone to kinking during insertion.

[0007] Several techniques are known to improve kink resistance, such as adding structural reinforcement, as implemented in some catheters. However, structural reinforcement is typically incompatible with peel-away functionality. Preferred reinforcing materials are generally materials with a relatively high modulus of elasticity, i.e., materials that can provide relatively high rigidity to the structural reinforcement, such as metals. Due to their material properties, these reinforcing materials also make peel-away of the device difficult or impossible. While polymer reinforcing layers are sometimes used as structural reinforcement, their ability to improve kink resistance and flexibility is limited due to their inherent material properties. Polymers and layers constructed from polymers have much lower modulus of elasticity and rigidity than, for example, metals. Summary of the Invention

[0008] overview The systems, methods, and devices described herein provide a flexible introducer sheath with peel-away sheath functionality with improved kink resistance and flexibility for introducing a vascular device, such as an intracardiac blood pump system or other mechanical circulatory assist device, into a patient's vasculature. Such an introducer sheath with improved functionality can be achieved in various ways, as disclosed herein. Generally, the sheath has at least two sections with different stiffnesses: one stiff section and at least one low-stiffness section. The improved sheath allows for improved kink resistance. One exemplary configuration with at least one high-stiffness section and at least one low-stiffness section is a sheath having an inner layer, a second reinforcement layer, and an outer layer. One embodiment provides a multi-layer sheath structure including a reinforcement layer configured with at least two discontinuities along its length. A practitioner can then apply a peel-away force to the sheath, splitting it along the discontinuities in the reinforcement layer. One or more notches may also be included along the sheath, which can facilitate peel-away of the sheath. The one or more notches extend from the outermost or innermost surface of the sheath body and penetrate some of the sheath layers. The notches can be configured as a series of separate notches or as a continuous peel-away line along the length of the sheath. The alignment of the notches defines the peel-away line along which the practitioner peels the sheath away. At least one advantage of the notches is the ability to define the lines along which the sheath will peel away, and aligning those lines with discontinuities in the reinforcement layers can reduce the amount of force required to peel the sheath away.

[0009] According to a first aspect of the present disclosure, a peel-away assembly for insertion into a blood pump includes a peel-away sheath hub and a peel-away sheath body. The peel-away sheath body has a proximal end portion, a distal end portion, and an intermediate portion, with the proximal end portion connected to the peel-away sheath hub. The peel-away sheath body further includes an outer layer, an inner layer, and a reinforcing layer positioned between the inner and outer layers. The outer layer defines an outer radius of the sheath, and the inner layer of the peel-away sheath body defines a sheath lumen having an inner radius. The inner layer further includes a peel-away line. The peel-away line is configured as a radially extending notch, which extends continuously in the longitudinal direction to form a line extending along the inner layer of the peel-away sheath body. The reinforcing layer is configured as a hypotube having two C-shaped halves extending in the longitudinal direction to form a circumferential discontinuity. The reinforcing hypotube has a stiffness greater than at least one of the stiffness of the inner layer and the stiffness of the outer layer. The reinforcing hypotube extends along the intermediate portion of the peel away sheath body but not into the distal end portion. The reinforcing layer may extend into the proximal end portion. Within the proximal end portion of the peel away sheath body, the reinforcing layer extends proximally beyond the distal end of the peel away sheath hub and terminates within the peel away sheath hub. In some embodiments, the reinforcing layer extends proximally about 2 cm beyond the distal end of the peel away sheath hub. The particular longitudinal point where the distal end of the peel away sheath hub terminates is selected to provide the peel away sheath body with desired kink resistance and flexibility along the length of the peel away sheath body. The distal end portion of the peel away sheath body may include a tapered tip designed to reduce trauma to the vasculature when the peel away sheath body is inserted into a patient.

[0010] According to another aspect of the present disclosure, a peel-away sheath assembly includes a peel-away sheath hub and a peel-away sheath body. The peel-away sheath body has a proximal end portion connected to the peel-away sheath hub and a distal end portion, which together define a first longitudinally extending lumen. In some configurations, the distal end portion and the proximal end portion comprise different materials. For example, the distal end portion may have an inner PEBAX layer, a stainless steel reinforcement layer, and an outer TPU layer. The proximal end portion may have an inner PEBAX layer and an outer TPU layer. In addition, the inner layer materials may be different between the distal end portion and the proximal end portion. For example, the inner layer of the distal end portion may comprise PEBAX and the inner layer of the proximal end portion may comprise TPU, or vice versa. Similarly, the outer layer materials may be different between the distal end portion and the proximal end portion. For example, the outer layer of the distal end portion may comprise PEBAX and the inner layer of the proximal end portion may comprise TPU, or vice versa. In some embodiments, the reinforcement layer is constructed of different materials between the distal and proximal layers. For example, the reinforcement layer may be stainless steel in the distal portion and Nitinol in the proximal portion. The proximal end portion may have an inner diameter equal to the inner diameter of the distal end portion.

[0011] According to another aspect of the present disclosure, a peel-away sheath body has a proximal end portion, an intermediate portion including a reinforcement layer, and a distal end portion. The proximal end portion is connected to a peel-away sheath hub. The proximal end portion, intermediate portion, and distal end portion define a first longitudinally extending lumen. In some embodiments, the reinforcement layer does not extend into the proximal end portion or into the distal end portion. For example, the distal end portion includes an inner polymer layer and an outer polymer layer, the intermediate portion includes an inner polymer layer, a reinforcement layer, and an outer polymer layer, and the proximal end portion includes an inner polymer layer and an outer polymer layer. For example, the distal end portion may include an inner PEBAX layer and an outer TPU layer, the intermediate portion may include an inner PEBAX layer, a stainless steel reinforcement layer, and an outer TPU layer, and the outer proximal end portion may include an inner PEBAX layer and an outer TPU layer. In some embodiments, the stainless steel comprises SAE 304 stainless steel. In further embodiments, the PEBAX layer comprises at least one of PEBAX 3533 to 7233. In some embodiments, the reinforcement layer extends into the proximal end portion. In other embodiments, the reinforcement layer extends into the distal end portion. In some embodiments, the reinforcement layer extends into both the distal end portion and the proximal end portion. In some embodiments, the inner diameter of the peel away sheath body is substantially constant throughout its length. In other embodiments, the proximal end portion of the peel away sheath body can have an outer diameter that is smaller than the outer diameter of the distal end portion. One advantage of a configuration with a reduced outer diameter proximal end portion is that an operator may apply less force to break the peel away sheath hub because there is less material to break.

[0012] In some configurations, the peel-away sheath body includes an inner layer located at an inner radius, an outer layer located at an outer radius, and a reinforcing layer located at a radius between the inner and outer radii. In certain embodiments, a hydrophilic coating is present on at least a portion of the outer layer. In some embodiments, the portion of the outer layer on which the hydrophilic coating is disposed extends from the distal end of the peel-away sheath body to about 5 cm to about 2 cm distal from the proximal end of the peel-away sheath body. In other embodiments, the portion of the outer layer on which the hydrophilic coating is disposed extends from the distal end of the peel-away sheath body to about 4 cm to about 3 cm distal from the proximal end of the sheath body. In a further embodiment, the portion of the outer layer on which the hydrophilic coating is disposed extends from the distal end of the peel-away sheath body to about 3.5 cm distal from the proximal end of the peel-away sheath body. The hydrophilic coating facilitates insertion of the peel-away sheath body into a patient's vasculature. The proximal end portion of the peel-away sheath body is generally configured without a hydrophilic coating because if the entire length of the peel-away sheath body were coated with a hydrophilic coating, the peel-away sheath body could be pushed out of the aorta due to arterial pressure acting on the peel-away sheath body.

[0013] In some configurations, the distal end portion and the proximal end portion may include the same material in the same layer. For example, the inner layer of both the distal end portion and the proximal end portion may include PEBAX, and the outer layer of both the distal end portion and the proximal end portion may include TPU. In further embodiments, the intermediate portion includes a different material from the distal end portion and the proximal end portion. In some embodiments, the peel-away sheath body has a reinforcement layer only in the intermediate portion, and no reinforcement layer in the distal end portion and the proximal end portion. For example, the distal end and proximal end portions may have an inner PEBAX layer and an outer TPU layer, and the intermediate portion may have an inner PEBAX layer, a stainless steel reinforcement layer, and an outer TPU layer. One advantage of a configuration with a reinforcement layer only in the intermediate portion of the peel-away sheath body is that it is relatively easy to manufacture compared to a configuration with a reinforcement layer throughout the entire length of the peel-away sheath body. The absence of a reinforcing layer at the distal end portion of the peel-away sheath body allows for easier formation of a tapered distal tip because the absence of a reinforcing layer allows the inner and outer layers to reflow. The reflow of the polymer layers provides the peel-away sheath body with an increased ability to accommodate stresses when the peel-away sheath body is introduced into or bent as it is navigated through a patient's vasculature. The reflow process can generally be controlled by melting the materials at different temperatures and achieving different process settings. Additionally, the absence of a reinforcing layer at the proximal end portion of the peel-away sheath body helps stabilize the injection molding process, allowing the polymer layers of the peel-away sheath body to mold to the peel-away sheath hub with consistent properties.

[0014] The length of the peel away sheath body along which the reinforcement layer extends can be adjusted to prevent kinking along a particular portion of the peel away sheath body. For example, in some embodiments, the reinforcement layer is present in the intermediate portion but not in the distal portion. In such embodiments, the reinforcement layer can extend over a variable length of the proximal end portion of the peel away sheath body. For example, the proximal end of the reinforcement layer can terminate at the same longitudinal point where the distal end of the sheath hub terminates. In other embodiments, the reinforcement layer can extend proximally beyond the distal end of the peel away sheath hub. In some embodiments, the reinforcement layer extends proximally about 2 cm beyond the distal end of the peel away sheath hub. In other embodiments, the reinforcement layer extends proximally about 1 cm beyond the distal end of the peel away sheath hub. The particular point at which the reinforcement layer terminates can be selected to adjust the kink resistance of the sheath body along the length of the peel away sheath body. The distal end portion of the peel away sheath body may include a tapered tip designed to reduce trauma to the vasculature when the peel away sheath body is inserted into a patient.

[0015] The reinforcement layer has material properties that advantageously impart improved kink resistance to the peel-away sheath assembly. For example, one such property of the reinforcement layer is its rigidity, which is higher than that of the inner or outer layer. Stiffness is defined herein as a property of a material, measured, for example, by Young's modulus or modulus of elasticity, while rigidity is defined herein as the ability of an element (e.g., a sheath) to resist deformation. By way of example, the modulus of elasticity of the reinforcement layer is a modulus of elasticity of the material of the reinforcement layer that is higher than that of the material of the inner or outer layer. In some embodiments, the stiffness of the reinforcement layer material is higher than that of the material of the inner or outer layer. In some configurations, the stiffness of the reinforcement layer material is about 18 times to about 12,000 times the stiffness of the material of the inner or outer layer. In other configurations, the stiffness of the reinforcement layer material is about 100 times to about 9,000 times the stiffness of the material of the inner or outer layer. In other embodiments, the stiffness of the reinforcement layer material is about 75 to about 100 times the stiffness of the inner or outer layer material. In further embodiments, the stiffness of the reinforcement layer material is about 400 to about 500 times the stiffness of the inner or outer layer material. In certain configurations, the stiffness of the reinforcement layer material is about 1,000 to about 7,000 times the stiffness of the inner or outer layer material. In further configurations, the stiffness of the reinforcement layer material is about 4,000 times the stiffness of either the inner or outer layer material. In some embodiments, the selected geometry and thickness of the reinforcement layer, along with the thickness of the inner and outer layers, can result in changes in the relative stiffness of the reinforcement layer, inner layer, and outer layer.

[0016] In some configurations, the reinforcing layer material can be LCP, PEBAX, stainless steel, Nitinol, or Kevlar. The inner and outer layer materials are thermoplastics. For example, the inner and outer layer materials can be PEBAX or TPU. The inner layer thickness can be from about 0.001 inches to about 0.015 inches. Additionally, the outer layer thickness can be from about 0.001 inches to about 0.015 inches. The total wall thickness of embodiments is about 0.016 inches or less.

[0017] The reinforcement layer advantageously provides kink resistance while enabling the peel-away functionality of the peel-away sheath assembly. The reinforcement layer includes at least two discontinuities on its surface. For example, the discontinuities are slits or openings in the surface of the reinforcement layer. Various configurations of slits or openings can be applied to the surface of the reinforcement layer to adjust the flexibility and kink resistance of the peel-away sheath assembly. In some embodiments, the at least two discontinuities are oriented on the surface of the reinforcement layer in a direction perpendicular to the longitudinal axis of the peel-away sheath body. This alignment advantageously forms a line of structural weakness along the length of the peel-away sheath body relative to the remainder of the peel-away sheath body, reducing the force required to peel away the peel-away sheath assembly along this line.

[0018] In some embodiments, the reinforcing layer is a hypotube. The hypotube is laser cut and electropolished to blunt any sharp edges left by the laser cut. The laser cut leaves at least two discontinuities along the surface of the hypotube. In other embodiments, the reinforcing layer is a braided or coiled filament. In these embodiments, the braid or coil is inherently configured to have discontinuities along its surface. In a further embodiment, the hypotube is composed of two C-shaped halves extending longitudinally along the length of the sheath body.

[0019] The length of the discontinuity in the reinforcing layer is sized around the circumference of the sheath to balance the various mechanical properties of the sheath. The circumferential length of the discontinuity must be large enough to allow for notch creation. For example, the discontinuity must be large enough to accommodate one of the mandrel protrusions so that a notch can be created. At the same time, the circumferential length of the discontinuity must be small enough so that the sheath resists buckling or kinking during insertion. As such, there is a critical size of the circumferential discontinuity, also referred to as the critical gap width, such that only within the length of the discontinuity does the sheath retain all of the above-mentioned advantageous properties. In some embodiments, the critical gap width can range from about 0.1 to about 1.5 mm.

[0020] In further embodiments, a series of discontinuities are configured along the surface of the reinforcement layer. In some embodiments, the discontinuities are parallel to one another. In some embodiments, the discontinuities are at various angles relative to the surface of the reinforcement layer such that they are not parallel or equally spaced relative to one another. In some embodiments, each discontinuity has the same length along the circumference of the sheath. Alternatively, the discontinuities can have varying lengths along the circumference of the peel away sheath body. In some embodiments, the discontinuities are equally spaced along the length of the peel away sheath body. In other examples, the discontinuities are variably spaced along the length of the reinforcement layer to vary the properties of the peel away sheath assembly along the length of the peel away sheath body. For example, the distance between two consecutive discontinuities at the proximal end portion of the peel away sheath body may be smaller so that the proximal end portion of the peel away sheath body has greater flexibility than the distal end portion of the peel away sheath body. In another example, the distance between two consecutive discontinuities may be greater at the proximal and distal end portions of the peel-away sheath body and smaller toward the middle of the peel-away sheath body's length. In such an example, the distal and proximal end portions of the peel-away sheath body have increased kink resistance compared to the middle of the peel-away sheath body's length, and the middle of the peel-away sheath body has increased flexibility compared to the distal and proximal end portions of the peel-away sheath body. In another example, the surface of the reinforcing layer has diagonal discontinuities, so that the surface cross-section of the sheath passing through the slit is elliptical. Varying the discontinuity configuration along the surface of the reinforcing layer can provide different flexibility and kink resistance to the sheath. Additionally, different discontinuity configurations can accommodate different peel-away lines on the peel-away sheath body.

[0021] The discontinuities may include a first set and a second set, each discontinuity in each set having a center. The center of the first set of discontinuities defines a first discontinuity axis, and the center of the second set of discontinuities defines a second discontinuity axis. The first and second discontinuity axes may be offset by an angle along the circumference of the reinforcing layer. The angle by which the first and second discontinuity axes are offset may range from about 0° to about 180°. In some configurations, the discontinuities may be slits extending along the circumference of the reinforcing layer. Depending on the number of discontinuities at a given longitudinal position on the sheath, the reinforcing layer may include multiple arc-shaped segments separated by the discontinuities. In certain embodiments, the arc-shaped segments are two C-shaped halves.

[0022] In addition to the circumferential discontinuities, the reinforcing layer may have a series of openings extending around the reinforcing layer. The openings may be circular, oval, diamond-shaped, or generally any other shape that allows for reflow of the inner and outer layers through the openings. The openings may form rings around the reinforcing layer at regular longitudinal points. In some embodiments, there are rings of openings around the hypotube at regular intervals along its length. For example, there may be a ring of openings every 1.2 inches along its length. In other embodiments, the ring of openings may extend around the reinforcing layer every 0.6 inches along its length. In certain embodiments, the ring of openings may extend around the reinforcing layer every 0.75 inches along its length. In further embodiments, the ring of openings may extend around the reinforcing layer every 1.05 inches along its length. In other embodiments, the ring of openings may extend around the reinforcing layer every 0.9 inches along its length. Each opening in each ring of openings may have a range of surface areas. For example, in some embodiments, each opening may have an area of ​​about 5 to about 25 mm. 2 In another embodiment, the surface area of ​​each opening is about 10 to about 20 mm 2 In certain embodiments, the surface area of ​​each opening is about 15 mm 2At least one advantage of incorporating a series of circumferentially extending openings along the length of the reinforcing layer is that it may allow reflow of the inner and outer layers through the openings, providing greater adhesion of the inner and outer layers to one another.

[0023] As described above, the reinforcing layer can be formed from hypotubes, braided filaments, or coiled filaments. In one embodiment in which the reinforcing layer is formed from braided filaments, the braided filaments have a flattened cross-section with a height of about 0.0005 inches to about 0.007 inches and a width of about 0.005 inches to about 0.060 inches. Alternatively, the braided filaments can have a round cross-section with a diameter of about 0.0005 inches to about 0.007 inches. The braided filaments can include multiple strands, and the braided filaments can have a picks per inch (PPI) of about 7 to about 60. In another embodiment in which the reinforcing layer is formed from coiled filaments, the coiled filaments have a flattened cross-section with a height of about 0.0005 inches to about 0.007 inches and a width of about 0.005 inches to about 0.060 inches. Alternatively, the coiled filament can have a round cross-section with a diameter of about 0.0005 inches to about 0.007 inches. The coiled filament can include multiple strands, and the coiled filament can have a wraps per inch (WPI) of about 16 to about 75. At least one advantage of a reinforcement layer formed with coiled or braided filaments is the presence of gaps between each wrap or weave of the filament, which, like discontinuities in the hypotube reinforcement layer, reduces the amount of force required to peel away the reinforcement layer and sheath as a whole. Additionally, larger gaps between each wrap or weave of the filament allow for greater sheath flexibility. At least one advantage of braided or coiled filaments is the ability to adjust the size of the gap, i.e., WPI, and select the size of the gap between braided filaments, while still being able to use the same manufacturing process for the reinforcement layer for various applications.

[0024] The stiffness or flexibility of the peel-away sheath assembly can be adjusted based on incorporating a reinforcement layer into all or some portions of the peel-away sheath body. In some embodiments, the reinforcement layer includes circumferential discontinuities in its surface, which may be slits or openings. For example, in some embodiments, a portion of the peel-away sheath body is free of a reinforcement layer, but instead, the peel-away sheath body relies on partial reinforcement in selected areas along its length for its kink resistance. Some embodiments have a less stiff distal sheath (e.g., without a distal reinforcement layer) with a more stiff proximal or intermediate sheath (e.g., with a reinforcement layer). Other embodiments have a less stiff proximal sheath (e.g., without a proximal reinforcement layer) with a more stiff distal or intermediate sheath (e.g., with a reinforcement layer). For example, the distal end portion of the peel-away sheath body may be designed without a reinforcement layer, while the proximal or intermediate section would have a reinforcement layer. At least one advantage of the absence of a reinforcement layer in the distal section of the peel-away sheath body is that it may allow for easier formation of a tapered tip because the inner and outer layers can reflow more easily without the inclusion of a reinforcement layer. In another example, the proximal end portion has three layers, including a reinforcement layer, and the distal end portion has only an inner layer of the first layer material and an outer layer of the outer layer material. The inner and outer layer materials can be at least one of PEBAX or TPU. In some embodiments in which the distal end portion does not have a reinforcement layer, the inner and outer layers comprise the same inner and outer materials. However, the inner and outer layers can also be different materials. For example, the inner layer can be PEBAX and the outer layer can be TPU. In other embodiments, the proximal end portion of the sheath does not have a reinforcement layer, but the intermediate portion, the distal end portion, or both include one. In a further embodiment, the intermediate portion of the sheath does not have a reinforcement layer, but the proximal end portion, the distal end portion, or both include such a layer. In a further embodiment, reinforcement layers are present in alternating segments of the sheath.At least one advantage of the partial reinforcement layer is that the sheath can have different stiffnesses along its length, for example, at its proximal and distal end portions, to aid in sheath insertion. For example, a lower stiffness at the distal end portion advantageously minimizes trauma to the vasculature. As another example, a higher stiffness at the proximal end portion advantageously maintains the kink resistance of the peel away sheath body through the varying stiffness. Varying the stiffness of the materials of the layers of the peel away sheath body, and in turn, varying the stiffness of portions of the peel away sheath body, can vary the stiffness of the peel away sheath assembly as a whole, for example, to promote kink resistance.

[0025] As detailed above, the length of the peel away sheath body along which the reinforcement layer extends can be adjusted to prevent kinking along certain portions of the peel away sheath assembly. For example, in some embodiments, the reinforcement layer is present in the intermediate portion but not in the distal end portion. In such embodiments, the reinforcement layer can extend over a variable length into the proximal end portion. For example, the proximal end of the reinforcement layer can terminate at the same longitudinal point where the sheath hub terminates. In other embodiments, the proximal end of the reinforcement layer can extend more proximally than the distal end of the peel away sheath hub. For example, the reinforcement layer can terminate about 0 cm to about 2 cm proximal from the distal end of the peel away sheath hub. The specific distance between where the reinforcement layer terminates and where the peel away sheath hub terminates can be selected to create a particular kink resistance between those two points along the length of the peel away sheath body.

[0026] The kink-resistant peel-away sheath body is also configured with a peel-away line extending along its length, the peel-away line aligned with one or more discontinuities in the reinforcement layer of the peel-away sheath body. Alignment can be achieved longitudinally along the peel-away sheath body, for example, by positioning the discontinuities at the same circumferential position as the peel-away line. Aligning the peel-away sheath body's peel-away line with at least one circumferential discontinuity in the reinforcement layer can make the peel-away sheath body easier to peel away. In some applications, the peel-away sheath body peels away along its entire length without breaking the reinforcement layer. For example, in embodiments having a reinforcement layer only at the distal end portion of the peel-away sheath body, the operator initiates removal of the peel-away sheath assembly at the proximal end portion by breaking the inner and outer layers. In embodiments having a reinforcement layer only at the proximal end portion of the peel away sheath body, the operator begins removal of the sheath at the proximal end portion by breaking the reinforcement layer, and then breaks only the inner and outer layers while detaching the distal end portion of the peel away sheath body.

[0027] The peel-away sheath hub is configured to provide a handle for an operator to hold the peel-away sheath assembly. Additionally, the operator initiates peel-away of the peel-away sheath assembly from the peel-away sheath hub. In some designs, the peel-away sheath hub has a proximal conical portion and a distal cylindrical portion. The proximal conical portion can have a proximal discontinuity, and the distal cylindrical portion can have a distal discontinuity. In some embodiments, the first and second discontinuities are circumferential discontinuities. The discontinuities are aligned with each other, and the distal end of the distal circumferential discontinuity abuts the proximal end of at least one peel-away line extending along the length of the peel-away sheath body. At least one advantage of this alignment is that it facilitates removal of the peel-away hub along with the peel-away sheath body by reducing the force required to peel away the peel-away sheath assembly, thereby ensuring that the operator does not need to tear the reinforcement layer.

[0028] In further embodiments, the distal end portion of the peel-away sheath assembly is configured with at least one pair of diametrically opposed notches along its length, the notches extending through the inner or outer surface of the peel-away sheath body to provide peel-away functionality. If a reinforcement layer is present, the notches align with discontinuities in the reinforcement layer such that, at a given longitudinal point along the length of the peel-away sheath body, the notches are located at the same circumferential position as the discontinuities. At least some benefits of the alignment between the notches and the discontinuities in the reinforcement layer include the ability to define a peel-away line and reduce the amount of force required to peel away the peel-away sheath body, thereby enabling an operator to peel away the peel-away sheath assembly. In some applications, the peel-away occurs without rupturing the reinforcement layer. In some embodiments, the notches are inner diameter notches extending from the innermost surface of the inner layer through the reinforcement layer. In further embodiments, the inner diameter notches terminate short of the outer layer. In other embodiments, the inner diameter notch terminates within the outer layer. In other embodiments, the notch is an outer diameter notch extending from the outermost surface of the outermost layer through the reinforcement layer. In further embodiments, the outer diameter notch terminates short of the inner layer. In other embodiments, the outer layer notch terminates within the inner layer. In embodiments having diametrically opposed notches, the notches define a pair of diametrically opposed peel-away lines on the surface of the peel-away sheath body, each pair of peel-away lines extending along the length of the peel-away sheath body, and the peel-away sheath assembly can be separated along the peel-away lines. In some embodiments, the peel-away lines extend along the inner surface of the peel-away sheath body. In other embodiments, the peel-away lines extend along the outer surface. The notches can help reduce the amount of force required to peel away the peel-away sheath assembly. As mentioned above, the notches can also help align the peel away line with the discontinuity in the reinforcement layer for improved peel away functionality.

[0029] Another aspect provides a peel-away sheath assembly for insertion into a blood pump. The peel-away sheath assembly includes a peel-away sheath hub and a peel-away sheath body. The peel-away sheath body has a proximal end portion connected to the peel-away sheath hub and a distal end portion. The peel-away sheath body defines a first lumen extending longitudinally. The peel-away sheath body further includes an inner layer located at an inner radius, an outer layer located at an outer radius, and a reinforcing layer located at a radius between the inner and outer radii. In certain embodiments, a hydrophilic coating is present on at least a portion of the outer layer. In some embodiments, the portion of the outer layer on which the hydrophilic coating is disposed extends from the distal end of the peel-away sheath body to about 5 cm to about 2 cm distal from the proximal end of the peel-away sheath body. In another embodiment, the portion of the outer layer on which the hydrophilic coating is disposed extends from the distal end of the sheath body to about 4 cm to about 3 cm distal from the proximal end of the sheath body. In a further embodiment, the portion of the outer layer on which the hydrophilic coating is disposed extends from the distal end of the sheath body to about 3.5 cm distal from the proximal end of the sheath body. The hydrophilic coating facilitates insertion of the sheath body into a patient's vascular system. Because coating the entire length of the sheath body with a hydrophilic coating could cause the sheath body to be pushed out of the aorta due to arterial pressure acting on the sheath body, a portion of the sheath body is generally configured without a hydrophilic coating. The sheath body of this embodiment further includes at least one pair of diametrically opposed notches extending through at least one of the inner or outer layers.

[0030] In a further embodiment, the diametrically opposed notches can be inner diameter notches that extend from the inner surface of the inner layer through the reinforcement layer and terminate short of or within the outer layer. At least one advantage of inner diameter notches is their relative ease of manufacture compared to outer diameter notches. Additionally, the notches can be outer diameter notches that extend from the outer surface of the outer layer through the reinforcement layer and terminate short of or within the inner layer. At least one advantage of outer diameter notches is their relative ease of facilitating peel-away of the sheath compared to inner diameter notches.

[0031] Additionally, the peel-away sheath body may have at least one pair of diametrically opposed internal notches extending through the internal layer. In some embodiments, the internal notches terminate short of the external layer. In other embodiments, the notches terminate within the external layer. The peel-away sheath body further includes at least one pair of diametrically opposed external notches extending through the external layer. In some embodiments, the external notches terminate short of the internal layer. In other embodiments, the notches terminate within the internal layer. As discussed above, the notches serve to align the peel-away line with discontinuities in the reinforcement layer. The specific notch configuration used, particularly whether internal or external diameter notches are used and where along the length of the sheath each notch terminates, can be selected based on the geometry of the reinforcement layer to achieve the desired peel-away sheath assembly flexibility and kink resistance.

[0032] In some embodiments, the inner notch extends along a first segment of the peel away sheath body, and the outer notch extends along a second segment of the peel away sheath body. In some embodiments, the first segment and the second segment overlap partially in the longitudinal direction. The overlapping segment can serve as a transition region between the first and second peel away sheath body segments. In other embodiments, the first segment and the second segment overlap completely in the longitudinal direction. In some embodiments, the first segment corresponds to a proximal end portion of the peel away sheath body, and the second segment corresponds to a distal end portion of the peel away sheath body. In some embodiments, the first segment extends along the entire length of the peel away sheath body. An advantage of having an inner diameter notch is that during the injection molding process, heat transfer can melt the sheath layer, allowing the polymer layer of the sheath body to reflow without sealing the notch, thereby enabling overmolding onto the hub. At least one advantage of the outer diameter notch is its ability to accommodate a variety of reinforcement layers. At least one advantage of using an outer diameter notch is improved manufacturability because the outer diameter notch can be used with a variety of hypotube geometries, braided filament geometries, and coiled filament geometries. As described in more detail below in connection with FIG. 14, after assembly of the various layers, an operator can select the location of the outer diameter notch depending on the geometry of the reinforcement layer.

[0033] Also disclosed is a method for manufacturing the claimed peel-away sheath assembly, including a peel-away sheath body and a peel-away sheath hub. The layers of the multi-layer peel-away sheath assembly can be heat-shrunk in one step or layer by layer. An exemplary method includes a first step of coating a mandrel with a first layer of a first material. After coating the mandrel with the first layer, an operator heat-shrunk the first layer of the first material. In a third step, an operator coats the heat-shrunk first layer with a second layer of a reinforcement layer material. The operator then coats the second layer of a second material with an outermost third layer of a third material. The third step includes coating the heat-shrunk first layer with a second layer of a second material and an outermost third layer of a third material, where the second layer is the reinforcement layer. Finally, all layers are heat-shrunk together to obtain the final peel-away sheath assembly. In some embodiments, the layers are heat-shrunk using a PTFE heat shrink material. In embodiments having notches, the inner notch is manufactured using a mandrel with radial protrusions, and the outer notch is manufactured by laser cutting or by pressing the mandrel with radial protrusions against the outer surface of the sheath.

[0034] The peel-away sheath hub is manufactured by injection molding, placing the peel-away sheath hub material into a mold with at least two inserts. In some embodiments, the peel-away sheath hub has a proximal conical section and a distal cylindrical section. The proximal conical section and the distal cylindrical section each include a discontinuity, which in some embodiments is a circumferential discontinuity. After the peel-away sheath hub is molded and fused to the peel-away sheath body, the inserts are removed, leaving a recessed space in the shape of the insert. The space left by the removal of the insert forms a longitudinal discontinuity along the length of the peel-away sheath hub. The discontinuities can align with each other and with the peel-away lines on the sheath body to facilitate peel-away of the peel-away sheath body. The peel-away sheath hub can be fused to the peel-away sheath body with the circumferential discontinuities aligned with the peel-away lines in the peel-away sheath body.

[0035] According to a further embodiment of the present disclosure, a sheath body is provided, including a first strip of a first material, a second strip of a second material, and a lumen defined by the first and second strips. The first material can have a first stiffness, and the second material can have a second stiffness different from (e.g., lower than) the first stiffness. The first and second strips are adjacently oriented, extending from the distal end to the proximal end of the sheath body, for example, helically. The helical or spiral structure and the alternating first and second strips of different stiffness improve flexibility by reducing the force required to bend the introducer sheath. It also improves kink resistance by increasing the ability of the introducer sheath to deform in the flexible section when compressed along the inner diameter of the bend radius and when tensioned along the outer diameter of the bend radius, and by increasing the diametral crush strength through the stiffer section. Improved flexibility and increased kink resistance are beneficial for procedures requiring high insertion angles, such as those using percutaneous axillary insertion.

[0036] In one embodiment, the first and second strips are not cut perpendicular to the orientation of the first and second strips. At least one advantage of this configuration is that it results in a sheath with material properties that are a composite of the material properties of each strip, without requiring a reinforcing coil or braid to surround the sheath. In particular, this configuration produces a sheath with composite material properties tailored to enhance flexibility (e.g., bending) while minimizing kinking.

[0037] In some embodiments, the first material is a polyether block amide (PEBA) or polyethylene, and the second material is a PEBA or a thermoplastic elastomer.

[0038] In certain embodiments, the first strip and the second strip have the same width. In some embodiments, the width of the first strip and the second strip is 1 mm. According to other embodiments, the first strip and the second strip have different widths. In some embodiments, the width of the first strip is 3 mm and the width of the second strip is 1 mm. At least one advantage of varying the width of each of the first and second strips is that the composite properties of the sheath can be changed to achieve the stiffness and bending stiffness desired for a particular introducer sheath.

[0039] In some embodiments, the sheath body includes a wall having a thickness and a first notch and a second notch therein. The first notch and the second notch can be axially aligned along the length of the sheath body and can be oriented opposite one another. In certain embodiments, the first notch and the second notch are on an inner surface of the sheath body. According to other embodiments, the first notch and the second notch are on an outer surface of the sheath body. According to certain embodiments, the sheath body is split along the first notch and the second notch during peel-away of the sheath body. At least one advantage of the notches is that they can improve the peel-away ease of the sheath body when the split line passes through both the first and second strips of material of different thicknesses.

[0040] In some embodiments, the sheath body includes a tapered tip. According to certain embodiments, the tapered tip includes a first material and a second material. In other embodiments, the tapered tip includes only the first material. According to some embodiments, the tapered tip includes only the second material.

[0041] According to a further embodiment of the present disclosure, an introducer sheath for insertion of a blood pump is provided. The introducer sheath includes a sheath body and a sheath hub. For example, see the sheath body embodiment of the present disclosure. The sheath body can include a first strip of a first material having a first stiffness, a second strip of a second material having a second stiffness, and a first lumen defined by the first and second strips. The first stiffness can be greater than the second stiffness. The first and second strips can be oriented adjacently and helically from the distal end to the proximal end of the sheath body. The sheath hub can include proximal and distal ends defining a second lumen. The distal end of the sheath hub can be attached to the proximal end of the sheath body. The helical structure of alternating first and second strips of different stiffness improves flexibility by reducing the force required to bend the introducer sheath, and improves strength by increasing the column strength (the axial force required to cause buckling) of the introducer sheath. Improved flexibility and increased column strength are beneficial for procedures using high insertion angles, such as subclavian insertion sites.

[0042] In some embodiments, the first and second lumens are in fluid communication, and various instruments can be inserted and withdrawn sequentially through both the first and second lumens of the sheath to achieve placement of the device at the desired location, after which the sheath can be peeled away.

[0043] The sheath hub can include a hemostasis valve sized to prevent fluid from exiting the proximal end of the hub.

[0044] In some embodiments, the sheath hub includes a first notch and a second notch. The first notch and the second notch can be axially aligned along the length of the sheath hub and can be oriented opposite one another. In certain embodiments, the first notch and the second notch can be on an inner surface of the sheath hub. In other embodiments, the first notch and the second notch can be on an outer surface of the sheath hub.

[0045] According to a further embodiment of the present disclosure, a method of manufacturing a flexible introducer sheath body is provided. The method includes wrapping a first strip of a first material and a second strip of a second material in adjacent relation around a mandrel and securing the strips together (e.g., by heating) so that they are adjacent and have peel-away functionality. The method may include securing a first distal end of the first strip and a second distal end of the second strip. The method may include securing a first proximal end of the first strip and a second proximal end of the second strip. The method may also include placing heat shrink tubing over the first strip, the second strip, and the mandrel. Additionally, the method may include heating the first strip and the second strip. The method may further include removing the heat shrink tubing. The method may also include removing the first strip and the second strip from the mandrel.

[0046] According to a further embodiment of the present disclosure, a sheath body is provided, including a first strip of a first material, a second strip of a second material, and a lumen defined by the distal and proximal ends of the sheath body. The first material can have a first stiffness, and the second material can have a second stiffness different from the first stiffness. The first and second strips are oriented adjacently over the lumen, extending from the distal end to the proximal end of the sheath body in, for example, a helical manner. The lumen can be made of a third material having the same or different stiffness as the first and / or second materials.

[0047] In some embodiments, the sheath body includes an outer wall having a first thickness, an inner wall having a second thickness, and first and second notches in the outer wall, which can be axially aligned along the length of the sheath body and oriented opposite one another.

[0048] At least one advantage of the manufacturing method is the ability to form a sheath with tailored composite material properties to provide improved bending flexibility and greater kink resistance. Additionally, the manufacturing method allows for the production of a sheath body with smooth inner and outer surfaces. [Brief explanation of the drawings]

[0049] These and other objects and advantages will become apparent from the following detailed description considered in conjunction with the accompanying drawings, in which like reference numerals refer to like parts throughout. [Figure 1] 1 illustrates a peel-away sheath assembly including a peel-away sheath body and a peel-away sheath hub. [Figure 2] 2A shows a longitudinal cross-section of a peel-away sheath body having a circumferentially continuous second layer, and FIG. 2B shows a longitudinal cross-section of the peel-away sheath body across a circumferential discontinuity in the second layer. [Figure 3A] 1 shows an axial cross section of a peel-away sheath body. [Figure 3B] 1 shows possible designs for laser cut hypotubes. [Figure 3C] 1 shows possible designs for laser cut hypotubes.

[0050] [Figure 4-1] Possible configurations of the inner and outer diameter notches are shown along an axial cross section. [Figure 4-2] Possible configurations of the inner and outer diameter notches are shown along an axial cross section. [Figure 5] Possible configurations of the inner and outer diameter notches are shown along a circumferential cross section. [Figure 6] 1 shows a cross section showing the inner layer, the reinforcing layer and the third layer. [Figure 7] 12A shows an isometric view of the proximal portion of the peel away sheath hub and peel away sheath body. [Figure 8] 10 illustrates a circumferential cross section of a peel-away introducer sheath within a cylindrical portion of a peel-away sheath hub. [Figure 9] 10 illustrates a circumferential cross section of the introducer peel-away sheath within the conical portion of the peel-away sheath hub. [Figure 10] 10 illustrates a top view of the proximal end portion of the peel away sheath hub and peel away sheath body. [Figure 11] 1 shows a cross section of a laser cut hypotube with an internal notch at the circumferential discontinuity. [Figure 12] 1 shows a cross section of a peel-away introducer sheath with the mold at the break wall. [Figure 13] 1 shows a cross section of a peel-away introducer sheath with no mold on the fracture wall. [Figure 14] 1 illustrates an exemplary method of manufacturing a particular embodiment of a peel-away sheath assembly. [Figure 15] 1 illustrates an exemplary longitudinal cross section of a peel-away introducer sheath in which the reinforcement layer extends into the peel-away sheath hub. [Figure 16] 1 illustrates an isometric view of an exemplary introducer sheath assembly including an exemplary expandable sheath body including two strips of material coupled to an exemplary sheath hub. [Figure 17] 1 illustrates an isometric view of an exemplary flexible sheath body having a first strip and a second strip. [Figure 18] 18 shows an exemplary view of the flexible sheath body of FIG. 17. [Figure 19]18 shows a schematic profile of the flexible sheath body of FIG. 17, with the first strip and the second strip having a width and a twist angle. [Figure 20] 18 shows a cross-sectional view of the flexible sheath body of FIG. 17 having a first notch and a second notch on the inner surface. [Figure 21] 21 shows an isometric view of the flexible sheath body of FIG. 20. [Figure 22] 18 shows a cross-sectional view of the flexible sheath body of FIG. 17 having a first notch and a second notch on an outer surface thereof. [Figure 23] 23 shows an isometric view of the flexible sheath of FIG. 22. [Figure 24] 18 illustrates an exemplary method for manufacturing the flexible sheath body of FIG. 17. [Figure 25] 1 shows a cross-sectional view of a flexible sheath body having an inner lumen and first and second notches on an outer surface. DETAILED DESCRIPTION OF THE INVENTION

[0051] Detailed Description To provide a general understanding of the systems, methods, and devices disclosed herein, certain exemplary embodiments will be described. While the embodiments and features described herein are specifically described with reference to use in connection with a percutaneous heart pump system, it will be understood that the present teachings may be adapted and applied to other mechanical circulatory assist devices and other types of medical devices, such as electrophysiology study and catheter ablation devices, angioplasty and stenting devices, angiography catheters, peripherally inserted central venous catheters, midline catheters, peripheral catheters, inferior vena cava filters, abdominal aortic aneurysm repair devices, thrombectomy devices, TAVR delivery systems, cardiac therapy and cardiac assist devices, such as balloon pumps, cardiac assist devices implanted using a surgical incision, and other venous or arterial-based intraluminal introducer catheters and devices.

[0052] The systems, methods, and devices described herein provide flexible introducer sheaths with peel-away sheath functionality, improving kink resistance and flexibility. Such improved functionality can be achieved in various ways, as disclosed herein. Generally, the sheath has at least two sections with different stiffnesses: one stiff section and at least one low-stiffness section. The improved sheath provides improved kink resistance. One exemplary configuration with at least one stiff section and at least one low-stiffness section is a sheath having an inner layer, a second reinforcement layer, and an outer layer. In such embodiments, the reinforcement layer may include laser-cut hypotubes or braided or coiled filaments. Another configuration with at least one stiff section and at least one low-stiffness section includes stiff and low-stiffness strands wound in a helical configuration in a single layer, as disclosed in Application Serial No. 62 / 672,212, reproduced below in Appendix A. By fabricating the low-stiffness section of the introducer sheath from a different polymer material, the introducer sheath also allows the sheath to be peeled away more easily. Using high-stiffness and low-stiffness materials, either in the same layer or in different layers, is an improvement over typical peel-away sheaths, which use only one material with a constant stiffness, forcing a choice between kink resistance and flexibility. In clinical scenarios requiring a peel-away sheath with a large insertion angle, improving kink resistance while also improving flexibility is highly desirable. Such clinical scenarios include femoral access in obese patients due to the distance between the vessel and the insertion point, and infraclavicular axillary access due to sensitive anatomical landmarks and nerve bundles in the area adjacent to the axillary insertion site. Additionally, the presence of discontinuities in the reinforcement layer and / or notches in the sheath layer reduces the force required to peel away the sheath.

[0053] FIG. 1 illustrates an exemplary peel-away sheath assembly 100, including a sheath handle 101, a sheath hub 102, a sheath body 103, a proximal end 104, a distal end 106, a sheath body lumen 108, a sheath body inner layer 110, a reinforcement layer 112, and an outer layer 114. The sheath hub 102 is coupled to the sheath body 103, which has a proximal end 104 and a distal end 106. The sheath hub 102 is coupled to the proximal end 104 of the sheath body 103. The sheath body 103 defines a first lumen 108 extending along a longitudinal axis of the sheath body 103. As further described below in connection with FIGS. 2-6, the peel-away sheath assembly 100 has a multi-layer design to provide both flexibility and kink resistance. The sheath body 103 includes an inner layer 110 located at a first, innermost radius, a reinforcing layer 112 located at a second radius, and an outer layer 114 located at a third, outermost radius. The inner layer 110 and the outer layer 114 comprise a thermoplastic resin, which may be the same for each of the inner layer 110 and the outer layer 114. Alternatively, the inner layer 110 and the outer layer 114 may comprise different thermoplastic resins. The reinforcing layer 112 has different material properties than the inner layer 110 and the outer layer 114. For example, the reinforcing layer is stiffer than at least one of the inner layer 110 and the outer layer 114. The exemplary embodiment shown in FIG. 1 may further include a hydrophilic coating on at least a portion of the outer layer. In some embodiments, the portion of the outer layer on which the hydrophilic coating is disposed extends from the distal end of the sheath body to about 5 cm to about 2 cm distal from the proximal end of the sheath body. In another embodiment, the portion of the outer layer on which the hydrophilic coating is disposed extends from the distal end of the sheath body to about 4 cm to about 3 cm distal from the proximal end of the sheath body. In a further embodiment, the portion of the outer layer on which the hydrophilic coating is disposed extends from the distal end of the sheath body to about 3.5 cm distal from the proximal end of the sheath body. As discussed above, the hydrophilic coating facilitates insertion of the sheath body into a patient's vascular system. Because coating the entire length of the sheath body with a hydrophilic coating could cause the sheath body to be pushed out of the aorta due to arterial pressure acting on the sheath body, a portion of the sheath body is generally configured without a hydrophilic coating.

[0054] The reinforcement layer can be a hypotube, braided filament, or coiled filament. The reinforcement layer is configured to have at least two discontinuities on its surface. For example, the hypotube of the reinforcement layer can be configured to have a series of slits on its surface. Such slits not only provide improved kink resistance given its inherent stiffness, but also allow the hypotube to have improved flexibility. As another example, the second layer of braided or coiled filament includes discontinuities between the filament braids or wraps. At least one advantage of a filament reinforcement layer is the presence of discontinuities between each wrap or braid of filament, which reduces the amount of force required to peel away the reinforcement layer and sheath as a whole. Furthermore, the additional discontinuities between each wrap of filament allow for greater flexibility. At least one advantage of filaments is the ability to adjust the size of the discontinuities, i.e., the wraps per inch (WPI), for various applications while using the same manufacturing process for the reinforcement layer. One additional advantage of filaments is the ability to maintain a given size of the discontinuities while adjusting the spacing between the discontinuities by varying the size of the filament. Both filament and hypotube configurations can be achieved with a variety of peel-away wire designs. One advantage of reinforcing layers constructed from hypotubes or coiled filaments is that the thickness of the layer can be configured to be constant throughout the length of the layer.

[0055] The sheath body is also configured with a peel-away line extending along its length, the peel-away line overlapping at least one circumferential discontinuity in the reinforcing layer of the sheath. At least one benefit of the overlap between the peel-away line of the sheath and the at least one circumferential discontinuity in the reinforcing layer is the ability to peel away the sheath without rupturing the reinforcing layer.

[0056] As described below in connection with Figures 2 and 3, the reinforcing layer can be a laser-cut hypotube. The hypotube can be machined to have at least two discontinuities in its surface. In some embodiments, the discontinuities extend along a portion of the circumference of the hypotube and are circumferential discontinuities. In other embodiments, the discontinuities extend along the length of the hypotube and are longitudinal discontinuities. In other embodiments, the discontinuities may extend in both the circumferential and longitudinal directions. In certain embodiments, a representative circumferential cross-section includes several circumferential discontinuities, as shown, for example, in Figures 5A-B and described in further detail below. For example, as shown in Figures 5A-B, the discontinuities can be two or more slits. In other embodiments, the discontinuities can be various sizes and shapes. For example, the discontinuities can be rectangular, circular, oval, and diamond-shaped.

[0057] In one embodiment, the slits in the surface of the hypotube are parallel to one another and equally spaced along the length of the hypotube, as shown in Figure 3B. In such an embodiment, there are two different circumferential cross sections that can be seen along the length of the hypotube. The first circumferential cross section is shown in Figure 2A.

[0058] Cross section 200 shows inner layer 202 located at the inner radius, reinforcing layer 204 located at the intermediate radius, and outer layer 206 located at the outermost radius. The center of Figure 2A shows first lumen 208. Figure 2A is a view from a longitudinal point along the sheath body where reinforcing layer 204 has a continuous circumference. Inner layer 202, reinforcing layer 204, and outer layer 206 are concentric. As defined herein, "concentric" means that each layer shares the same center, that outer layer 206 completely surrounds reinforcing layer 204 and inner layer 202, and that reinforcing layer 204 completely surrounds inner layer 202.

[0059] A second exemplary circumferential cross-section is shown in FIG. 2B. Cross-section 220 shows inner layer 222 located at the inner radius, reinforcing layer 224 located at the intermediate radius, and outer layer 226 located at the outermost radius. The center of FIG. 2B shows first lumen 230. The cross-section of FIG. 2B is taken along the sheath body from a longitudinal point where reinforcing layer 224 has a circumferential discontinuity 228 corresponding to the slit in the laser-cut hypotube. As such, the cross-section of FIG. 2B shows a discontinuous reinforcing layer. At least one circumferential discontinuity 228 defines a line that provides peel-away functionality to the sheath.

[0060] 2A and 2B, the material properties of the reinforcement layer 204 advantageously provide the sheath assembly with improved flexibility and kink resistance. For example, one such physical property is the stiffness of the reinforcement layer, which is higher than the stiffness of at least one of the materials of the inner layer 202 or the outer layer 206. Another such physical property of the reinforcement layer material 204 is its modulus of elasticity, which may also be higher than the modulus of elasticity of at least one of the materials of the inner layer 202 or the outer layer 206. The first inner layer 202 material and the outer layer 206 material may be thermoplastic, and the thermoplastic may be at least one of PEBAX or TPU. The reinforcement layer 204 material may be at least one of LCP, PEBAX, stainless steel, Nitinol, or Kevlar. The thickness of the inner layer 202 may be between 0.001 inches and 0.015 inches. Additionally, the thickness of the outer layer 206 may be between 0.001 inches and 0.015 inches. The total wall thickness of an embodiment is 0.016 inches or less.

[0061] FIG. 3A shows one exemplary longitudinal cross-section 300 of a peel-away sheath assembly, with the longitudinal axis of the sheath body lying in the plane of the page. The cross-section shows an inner layer 302 at the inner radius, a reinforcement layer 304 at the intermediate radius, and an outer layer 306 at the outer radius. The reinforcement layer 304 has discontinuities 308, which in some embodiments are circumferential discontinuities. Together, the three layers define a first lumen 310. Within the reinforcement layer 304, circumferential discontinuities 308, which separate ribs 309, are connected by the reinforcement layer 304. The circumferential discontinuities 308 have a finite arc length and do not extend the entire circumference of the reinforcement layer 304. The circumferential discontinuities 308 may have different arc lengths and may have different widths. The arc length of the circumferential discontinuities 308 may be approximately 0.5 cm to 1 cm. Similarly, the width of the circumferential discontinuity 308 can be about 0.1-0.5 cm, about 0.2-0.4 cm, and about 0.3 cm.

[0062] FIG. 3B illustrates one configuration of discontinuities 322 and 324 in the reinforcing layer 320, in which each discontinuity 322 and 324 of the hypotube has the same length along the circumference of the hypotube. The discontinuities in FIG. 3B are equally spaced longitudinally, and the discontinuities include a first set and a second set of discontinuities. The discontinuities located at the same circumferential position as the first slits 322 constitute the first set, and the discontinuities located at the same circumferential position as the second slits 324 define the second set. Each discontinuity in each set of discontinuities has a center. The center of the first set of discontinuities defines a first discontinuity axis, and the center of the second set of discontinuities defines a second discontinuity axis. In some embodiments, as shown in FIG. 3B, the first and second slit axes are offset by some angle. The angle by which the two slit axes are offset can be 0°, such that all of the slits along the length of the hypotube are centered on the same axis. The angle by which the slit axes are offset can range from 0° to about 18°. In one example, the slit axes are offset by 0°, corresponding to each slit being centered on the same axis. In another example, the slit axes are offset by 180°, corresponding to two slit axes being diametrically opposed to one another. As defined herein, "diametrically opposed" means that two features of the embodiment are separated by a 180° offset along the sheath body. In other examples, the axes may be offset by an angle of about 30 to about 150°. In other examples, the axes may be offset by an angle of about 60 to about 120°. In other examples, the axes may be offset by an angle of about 90°. In other examples, the discontinuities have different lengths along the surface of the hypotube. In other examples, the slits are variably spaced along the length of the hypotube to achieve varying flexibility along the sheath. For example, the spacing can be fixed in the proximal portion of the sheath and may increase distally to provide easier peel-away capability at the proximal end while providing greater kink resistance at the distal end.In another example, the slits may be closest at both ends of the sheath body and have greater spacing in the middle of the length of the sheath body to provide kink resistance in the middle of the sheath body while allowing the distal ends of the sheath to be easily peeled away. As discussed above with respect to the filament reinforcement layer, the discontinuities can be of different sizes and shapes. Configurations with hypotube reinforcement layers can also have discontinuities of different sizes and shapes.

[0063] In some embodiments, the hypotube can be configured with a spine connecting a series of ribs. As defined herein, a "spine" refers to a portion of the hypotube that extends continuously in a longitudinal direction parallel to the first lumen of the sheath body. As defined herein, a "rib" refers to a portion of the hypotube that is connected to the spine at only one end and extends circumferentially from the spine. In some embodiments, there is only one rib, and the hypotube resembles a C-shape extending longitudinally along the length of the sheath body. In other embodiments, there can be several ribs. The ribs can be separated longitudinally by circumferential discontinuities. In other embodiments, there can be two or more spines, each connected to a set of ribs. In all such embodiments, the number and spacing of the ribs can be optimized to produce the desired kink resistance and flexibility. Ribs spaced closer together provide greater kink resistance. Ribs spaced farther apart provide greater flexibility and ease of peel-away.

[0064] FIG. 3C illustrates another configuration of discontinuities 332 and openings 334 in the reinforcing layer 330. In FIG. 3C, the circumferential discontinuities 332 are oriented to extend along the periphery of the reinforcing layer. The inclusion of openings 334 aids in bonding the inner and outer layers to the reinforcing layer 330 during manufacturing. The openings 334 may be configured in a variety of shapes. The openings 334 may be circular, oval, or diamond-shaped, for example. As discussed above, the openings 334 are configured to extend along the periphery of the reinforcing layer 330. The openings 334 may be oriented at regular intervals along the length of the reinforcing layer 330. For example, an opening 334 may be included every 0.7 inches along the length of the reinforcing layer 330. In other embodiments, the openings 334 may be positioned every 0.9 inches along the length of the reinforcing layer. In certain embodiments, the openings 334 may be positioned every 1.1 inches along the length of the reinforcing layer. As discussed above, the openings 334 may have a range of surface areas. For example, in some embodiments, each opening 334 has a length of about 5 to about 25 mm 2 In another embodiment, the surface area of ​​each opening 334 is about 10 to about 20 mm 2 In a particular embodiment, the surface area of ​​each opening 334 is about 15 mm 2 The incorporation of the apertures allows the inner and outer layers of the sheath body to better adhere to one another during manufacturing. This increased adhesion allows the sheath body to better accommodate stresses when bent. The reflow process is also controlled to result in polymer reflow into the circumferential slits configured along the length of the hypotube. The slits, which remain free of polymer, allow the slits to function as compression and expansion zones, which enhance the flexibility of the sheath body.

[0065] Figures 4A-4E illustrate several possible configurations of inner and outer diameter notches. Such configurations define peel-away lines along which a practitioner can peel the sheath assembly apart. Figures 4A-4E illustrate the inner layer 402, reinforcement layer 404, and outer layer 406, as well as the sheath lumen 408. An exemplary notch 410 is also shown. Figure 4A illustrates an embodiment with only an inner diameter notch. The inner diameter notch in Figure 4A begins at the innermost surface of the inner layer 402, penetrates the reinforcement layer 404, and terminates within the outer layer 406. In another embodiment, the outer diameter notch 410 begins at the innermost surface of the inner layer 402, penetrates the reinforcement layer 404, and terminates short of the outer layer 406. The embodiment including an inner diameter notch (Figure 4A) is relatively easy to manufacture.

[0066] Figure 4B shows an embodiment having only an outer diameter notch. The outer diameter notch in Figure 4B starts at the outermost surface of the outer layer 406, penetrates the reinforcement layer 404, and terminates within the inner layer 402. In another embodiment, the outer diameter notch in Figure 4B starts at the outermost surface of the outer layer 406, penetrates the reinforcement layer 404, and terminates short of the inner layer 402. The embodiment including an outer diameter notch (Figure 4B) provides better performance for peel-away functionality than configurations having only inner diameter notches.

[0067] Figure 4C illustrates an embodiment having both inner and outer diameter notches, where the two types of notches do not longitudinally overlap along the length of the sheath body. Figure 4D illustrates an embodiment in which the notches partially overlap longitudinally along the length of the sheath body. Figure 4E illustrates an embodiment in which the notches completely overlap longitudinally along the length of the sheath body. In one embodiment, the outer diameter notches extend along at least the distal end of the distal portion of the sheath body, and the inner diameter notches extend along all of the proximal end of the sheath and up to the proximal end of the distal portion of the sheath body. In another embodiment, in addition to both inner diameter notches and outer diameter notches extending overlappingly along any portion of the first section of the sheath body, the outer diameter notches extend along at least the distal end of the distal portion of the sheath body, and the inner diameter notches extend along all of the proximal portion of the sheath and up to the proximal end of the proximal portion of the sheath body.

[0068] 5A shows a circumferential cross section 500 of a sheath body having an inner layer 502, a reinforcement layer 504, and an outer layer 506. The three layers define a lumen 508 extending along the longitudinal axis of the sheath body. Diametrically opposed outer diameter notches 510 extend from the outermost surface of the outer layer 506, through the reinforcement layer 504, and terminate within the inner layer 502.

[0069] FIG. 5B shows a circumferential cross-section 520 of a sheath body having an inner layer 522, a reinforcement layer 524, and an outer layer 526. The three layers define a first lumen 528 extending along the longitudinal axis of the sheath body. Diametrically opposed outer diameter notches 530 extend from the innermost surface of the outer layer 522, through the reinforcement layer 524, and terminate within the inner layer 526. As discussed in connection with FIGS. 4A-E, configurations with outer diameter notches, such as in FIG. 5A, have improved peel-away performance, while configurations with inner diameter notches, such as in FIG. 5B, are more easily manufactured. Some embodiments have only inner diameter notches, while other embodiments have only outer diameter notches. Further embodiments may have both inner and outer diameter notches, with the inner diameter notches extending exclusively from the outer diameter notches along the length of the sheath body. Further embodiments may have portions of the sheath body with both inner and outer diameter notches, and some other embodiments may have both areas where only one notch is found and areas where the two types of notches are found overlapping longitudinally.

[0070] 6 similarly shows a cross section 600 of the layers of the sheath, including an inner layer 602, a reinforcing layer 604, and an outer layer 606. A discontinuity 610 can be seen in the reinforcing layer 604. In some embodiments, the discontinuity 610 is a circumferential discontinuity.

[0071] 7 shows an isometric view 700 of a sheath hub 701 and a proximal portion 706 of a sheath body 707. The sheath hub includes a proximal conical portion 702 having a circumferential discontinuity 703 and a distal conical portion 704 having a circumferential discontinuity 705. The distal conical portion 704 of the sheath hub 701 is attached to the proximal portion 706 of the sheath body 707. The discontinuities 703 and 705 are configured to align with the peel-away lines of the sheath body 707 such that at a given longitudinal point along the length of the sheath body having the discontinuities, the peel-away lines are located at the same circumferential position as the discontinuities. In some embodiments, the discontinuities 703 and 705 are circumferential discontinuities.

[0072] FIG. 8 shows a circumferential cross-section 800 of a distal cylindrical portion 810 of a sheath hub taken along line A-A' (see FIG. 7). An inner layer 802, together with a reinforcement layer 804 and an outer layer 806, defines a first lumen 808. A discontinuity 812 in the cylindrical portion 810 of the sheath hub aligns with a peel-away line in the sheath body to facilitate sheath removal and, in some embodiments, is a circumferential discontinuity. The discontinuity 812 also aligns with a discontinuity in the proximal conical portion of the sheath hub to also facilitate sheath removal. The discontinuity in the proximal conical portion of the sheath hub, in some embodiments, is a circumferential discontinuity. As described in more detail with respect to FIG. 12, the discontinuity 812 in the cylindrical portion 810 of the sheath hub is manufactured by placing an insert in the sheath hub material and then fusing the sheath hub material to the sheath body. After fusing, the insert is removed, leaving a circumferential discontinuity 812 in the cylindrical portion 810 of the sheath hub.

[0073] FIG. 9 illustrates a circumferential cross-section 900 of a proximal conical portion 910 of a sheath hub, taken along line B-B′ (see FIG. 7 ). An inner layer 902 defines a first lumen 908. A discontinuity 912 in the conical portion 910 of the sheath hub can align with a discontinuity in the distal cylindrical portion of the sheath hub to facilitate removal of the sheath, which also aligns with a peel-away line in the sheath body. In some embodiments, the discontinuity 912 is a circumferential discontinuity. As described in detail with respect to FIG. 12 and previously described with respect to the circumferential discontinuity in the distal cylindrical portion of the sheath hub, the circumferential discontinuity 912 in the conical portion 910 of the sheath hub is fabricated by placing an insert in the sheath hub material and then fusing the sheath hub material to the sheath body. Removal of the insert after welding leaves a circumferential discontinuity 912 in the conical portion 910 of the sheath hub. Additionally, as shown in the exemplary embodiment of FIG. 9 (and as described in further detail below in connection with FIG. 12 ), only the inner sheath layer is present in the proximal conical portion of the sheath hub. As described in further detail below in connection with FIG. 12 , the inner layer 902 has a particular thickness. The thickness of the inner layer 902 in the proximal conical portion 910 of the sheath hub can be less than the thickness of the layers distal to the proximal conical portion 910. The thickness of the inner layer 902 in the proximal conical portion 910 can be selected to provide a tapered section in the proximal conical portion 910. The tapered section can have an outer diameter that is less than the total thickness of the relatively distal layers, or it can have an outer diameter that is equal to the total thickness of the relatively distal layers. The presence of only one sheath layer in the proximal conical portion 910 of the sheath hub reduces the amount of material that the operator must break to separate the sheath, allowing the operator to apply less breaking force.

[0074] FIG. 10 shows a top view 1000 of a sheath hub 1001 and a proximal portion 1006 of a sheath body. The sheath hub 1001 includes a proximal conical portion 1002 and a distal cylindrical portion 1004. A discontinuity 1003 exists in the conical portion 1002 of the sheath hub, and a discontinuity 1005 exists in the cylindrical portion of the sheath hub. The discontinuities 1003 and 1005, in some embodiments, are circumferential discontinuities. The circumferential discontinuities 1003 and 1005 are aligned with the peel-away line of the sheath body. The proximal end 1006 of the sheath body is coupled to the sheath hub 1001 at the distal conical portion 1004. FIG. 7 also shows lines A-A' and B-B', and exemplary cross sections of the hub through the cylindrical and conical portions are shown in FIGS. 8 and 9, respectively.

[0075] The manufacture of a peel-away sheath involves the manufacture of a multilayer sheath body, the manufacture of a sheath hub, and the assembly of the sheath hub and sheath body. Particular notches and layer configurations can be configured for ease of manufacturing. For example, the absence of a reinforcing layer in the proximal portion of the sheath helps stabilize the injection molding process. Additionally, the use of internal diameter notches ensures that the notches do not seal when the polymer layers reflow during the manufacturing process. As described in more detail below in connection with FIG. 14, the multilayer sheath body is manufactured through a heat shrinking process. Heat shrinking is also referred to as lamination.

[0076] In one manufacturing method, an innermost first layer material, a reinforcing second layer material, and an outermost third layer material are placed over a mandrel. These layers are then heat shrunk, for example, using PTFE heat shrink.

[0077] In another method, the innermost first layer is placed over a mandrel and heat shrunk, at which point the reinforcing second layer material and the outermost third layer material are placed over the heat shrunk first layer, and the heat shrunk first layer, reinforcing second layer material, and outermost third layer material are then lapped and heat shrunk together.

[0078] In yet another method, each layer is heat shrunk sequentially onto a mandrel. The innermost first layer is placed onto the mandrel and heat shrunk. The heat shrunk first layer is then coated with a reinforcing second layer material. The two layers are then heat shrunk together. The two heat shrunk layers are then coated with an outermost third layer material. The three layers are then lapped and heat shrunk together.

[0079] When fabricating a sheath body with an internal diameter notch, the mandrel used for heat shrinking includes a raised spine, and heat shrinking the layers using the mandrel forms a sheath body with an internal diameter notch in the shape of the mandrel spine. When fabricating a sheath body with an external diameter notch, the outermost third layer is configured using a mold during heat shrinking, with the mold having the shape of the external diameter notch. After heat shrinking, the mold is removed, leaving an external diameter notch in the shape of the mold. As described in more detail below in connection with FIG. 11 , the circumferential discontinuity must be large enough to at least allow the mandrel to extend through the discontinuity during fabrication and to provide improved flexibility. The size of the discontinuity should not be smaller than the size of the protrusion of the mandrel used in fabrication. However, the discontinuity must also be small enough to provide improved kink resistance. If the discontinuity is too large, the sheath will buckle.

[0080] Similar manufacturing methods exist for any configuration of the reinforcing second layer. For example, when the reinforcing layer is a hypotube having multiple hypotube arc segments, the innermost first layer may be heat-shrunk, followed by heat-shrunking of the arc segments onto the heat-shrunk innermost first layer. This can be done to ensure that an increasing number of hypotube arc segments are properly bonded to the innermost first layer before assembling and heat-shrunking of the outermost third layer. Additionally, when the reinforcing layer is a hypotube containing multiple arc segments, the innermost first layer may be heat-shrunk, followed by heat-shrunking of the arc segments individually onto the heat-shrunk first layer. Similarly, the braided and coiled filament structures described above can be heat-shrunk onto the heat-shrunk innermost first layer, followed by heat-shrunking of the outermost third layer to ensure proper adhesion of the filament layers to the innermost first layer.

[0081] When the sheath is removed from the patient, the sheath hub, in addition to the sheath body, is peeled away. As previously described and with reference to FIGS. 12 and 13, the sheath hub is manufactured using injection molding, in which the sheath hub material is placed into a sheath hub mold, and the mold is configured to have at least one insert. In some embodiments, two inserts are used. After the sheath hub is molded and fused to the sheath body, the at least one insert is removed. As such, the sheath hub is configured during manufacturing to include a break-away wall in the form of at least one shaped recessed space. This recessed space helps the practitioner easily peel away the sheath hub. FIG. 12 shows a cross-section 1200 of an introducer sheath in which the mold is at the break-away wall. The break-away wall is configured to have the shape of the two inserts after they are removed from the sheath hub material. In other configurations, a single insert may be used, and in further embodiments, three or more inserts may be used. Additionally, FIG. 12 shows a reduced diameter section 1210. The inner layer may be configured to extend proximally farther than the reinforcement layer or the outer layer, such that reduced diameter section 1210 corresponds to a proximal segment along the sheath body that may include only the inner layer. Reduced diameter section 1210 has a thickness 1211. Layer 1212 has a thickness 1213, and layer 1214 has a thickness 1215. In some embodiments, thickness 1211 is less than the sum of thicknesses 1213 and 1215. In other embodiments, thickness 1211 is equal to thickness 1213, such that reduced diameter section 1210 and layer 1212 form one continuous layer. In other embodiments, thickness 1211 is less than thickness 1213. As previously mentioned, one advantage of the absence of a reinforcement layer in the proximal portion of the sheath is the stabilization of the injection molding process, which allows the polymer layers of the sheath body to be molded to the sheath hub with consistent properties. FIG. 13 shows a cross section 100 of an introducer sheath without the mold broken wall showing how the insert sits relative to the sheath hub.

[0082] FIG. 11 shows a cross section 1100 of a laser-cut hypotube 1104 having an internal notch 1108 in a circumferential gap 1110. The inner layer 1102, reinforcement layer 1104, and outer layer 1106 are configured with the internal notch in the circumferential gap to enhance peel-away functionality. As previously mentioned, the discontinuity must be large enough to allow at least one inner or outer diameter notch to extend therethrough and provide improved flexibility, while simultaneously being small enough to provide improved kink resistance. In some embodiments, the width of the circumferential gap 1110 ranges from about 0.1 to about 1.5 mm. In other embodiments, the width of the circumferential gap 1110 ranges from about 0.3 to about 1.2 mm. In certain embodiments, the width of the critical gap 1110 ranges from about 0.5 to about 1.0 mm. In further embodiments, the width of the critical gap 1110 ranges from about 0.7 to about 0.8 mm. In a particular embodiment, the width of the critical gap 1110 is approximately 0.761 mm.

[0083] FIG. 14 shows a flowchart for manufacturing a peel-away sheath assembly for the introduction of a heart pump, according to certain embodiments. Process 1400 begins at step 1402, in which an operator coats a mandrel with a first layer of a first material. In some embodiments, the first layer material is a thermoplastic resin, including one of PEBAX or TPU. At step 1404, the operator heat-shrinks the first layer. This involves coating the first layer material with heat-shrink material and heating the layer and the heat-shrink material. After heat-shrinking the first layer, at step 1406, the operator coats the heat-shrunk first layer with a second layer of reinforcing second layer material. Then, at step 1408, the operator coats the second layer of reinforcing second layer material with an outermost layer of third layer material. At step 1410, the operator heat-shrinks the heat-shrunk first layer, reinforcing second layer, and third layer materials together. As described above in connection with FIG. 3C, the openings in the reinforcing layer, which form rings around the reinforcing layer at regular longitudinal intervals along the length of the sheath body, allow the inner and outer layers to reflow. This reflow provides better adhesion of the inner and outer layers to each other, which allows the sheath body to better accommodate stresses when bent. The manufacturing process is controlled to prevent reflow of the inner and outer layers into the circumferential slits. The absence of polymer layers from the slits allows the slits to function as compression and expansion zones, providing improved flexibility to the sheath body. In a further embodiment of the method, the mandrel used in manufacturing can have at least one raised spine, such that heat shrinking of the first layer material leaves at least one internal notch in the heat-shrunk first layer. In another embodiment, the operator selects the location of each external notch based on the geometry of the heat-shrunk reinforcing layer. In another embodiment of the method, the operator does not need to subject the first layer to heat shrinking before heat-shrunking the second reinforcing layer and the outermost third layer. That is, for the first time, an operator can heat shrink the first, second, and third layers simultaneously.

[0084] 15 shows a longitudinal cross section 1500 of a sheath body 1502 having an inner layer 1504, an outer layer 1506, a reinforcement layer 1508, a sheath hub 1510, a reinforcement hub length 1512, a distal portion 1514, an intermediate portion 1516, and a proximal portion 1518. As previously mentioned, the length of the sheath body 1502 over which the reinforcement layer 1508 extends can be adjusted to prevent kinking along particular portions of the sheath body 1502. For example, in some embodiments, the reinforcement layer 1508 is absent from the distal portion 1514 but present in the intermediate portion 1516. In such embodiments, the reinforcement layer 1508 can extend to various depths into the proximal portion 1518, as indicated by the reinforcement hub length 1512. For example, the proximal end of the reinforcement layer 1508 can terminate at the same longitudinal point where the sheath hub 1510 terminates. In other embodiments, as shown in exemplary FIG. 15 , the reinforcement layer 1508 may terminate at a longitudinal point distal to the longitudinal point where the sheath hub 1510 terminates. In other embodiments, the proximal end of the reinforcement layer 1508 may terminate at a longitudinal point proximal to the longitudinal point where the sheath hub 1510 terminates. The longitudinal point where the reinforcement layer 1508 terminates may be determined by the reinforcement hub length 1512. For example, the reinforcement hub length 1512 can extend to a desired depth into the sheath hub 1510 to create a desired kink resistance along a particular length of the sheath. The reinforcement hub length 1512 may be, for example, 2 cm long, such that the reinforcement layer 1508 terminates 2 cm distal to the longitudinal point where the sheath hub 1510 terminates. In other embodiments, the reinforcement hub length 1512 may be 1 cm, such that the reinforcement layer 1508 terminates 1 cm distal to the longitudinal point where the sheath hub 1510 terminates. In further embodiments, the reinforcement hub length 1512 may be zero, such that the reinforcement layer 1508 terminates at the longitudinal point where the sheath hub 1510 terminates. The specific distance between the point where the reinforcement layer terminates and the point where the sheath hub terminates can be selected to create a particular kink resistance between those two points along the length of the sheath body. The surface of the reinforcement layer is configured with discontinuities to facilitate peel-away of the reinforcement layer.Peel-away begins in the sheath hub, and for embodiments having a reinforcement layer that extends into the sheath hub, peel-away of the reinforcement layer is facilitated because the practitioner can apply the peel-away sheath force directly to the portion of the sheath body that includes the reinforcement layer.

[0085] FIG. 16 illustrates an exemplary introducer sheath assembly 1600 including a sheath body 1700 (described further in connection with FIG. 17 ) coupled to a sheath hub 1602. As described in further detail below in connection with FIGS. 17-19 , the sheath body 1700 has a helical design including two strips 1706 and 1708 of material having different stiffnesses. At least one advantage of this bi-material helical design is the ability to obtain a sheath with composite material properties for improved flexibility while also improving kink resistance. In one aspect, the sheath body 1700 can have a ring design including alternating rings of material having different stiffnesses. In another aspect, the sheath body 1700 can have a longitudinal strip design including alternating strips of material having different stiffnesses. Both the sheath body 1700 and the sheath hub 1602 have proximal and distal ends. The distal end of the sheath hub 1602 is coupled to the proximal end of the sheath body 1700. For example, the distal end of the sheath hub can be glued or bonded to the proximal end of the sheath body. Alternatively, the distal end of the sheath hub can be integrally formed with the proximal end of the sheath body. The sheath hub 1602 includes a gripping surface 1604 and a notch 1606. The gripping surface 1604 can be formed with two diametrically opposed tabs or any other geometry suitable for gripping. The gripping surface 1604 facilitates peeling away of the sheath hub 1602 and sheath body 1700. During sheath peel-away, a force is applied to the gripping surface 1604 (e.g., tabs as shown in FIG. 16 ), bisecting the sheath hub 1602 along its longitudinal axis, starting at the notch 1606. The notches 1606 can be axially aligned along the length of the sheath hub and oriented opposite each other. The notch 1606 on the sheath hub 1602 can be on the inner surface of the sheath hub 1602 or on the outer surface of the sheath hub 1602. The sheath hub 1602 can be separated into two pieces by applying a force to the gripping surface 1604 of the sheath hub 1602, causing the sheath hub to break along the notch 1606.As described in more detail below in connection with FIGS. 20-23, the sheath body can have notches on the inner surface of the sheath body 1700 ( FIGS. 20 and 21 ) or on the outer surface of the sheath body 1700 ( FIGS. 22 and 23 ). The notches along the sheath body 1700 can be replaced with cuts. To facilitate peeling away the sheath hub 1602 and sheath body 1700, the notches on the sheath body 1700 can align with the notches 1606. At least one advantage of notches or cuts on the sheath body 1700 is that they can improve the ease with which the seal can be peeled away by severing both spiral strips of the sheath. The sheath body 1700 can be separated into two pieces by breaking the sheath hub 1602 and then applying additional force to the gripping surface 1604 of the sheath hub 1602, causing the sheath body 1700 to break along the notch in the sheath body 1700.

[0086] The lumen of the sheath body 1700 and the lumen of the sheath hub 1602 are in fluid communication, allowing passage of a medical device between the sheath hub 1602 and the sheath body 1700. In one aspect, the sheath hub 1602 includes a hemostatic valve, which can be sized to prevent fluid from exiting the proximal end of the hub during insertion of a medical device.

[0087] 17 and 18 illustrate an exemplary sheath body 1700 (e.g., the sheath body 1700 of FIG. 16 ) including a distal end 1702, a proximal end 1704, a first strip 1706, and a second strip 1708. The first strip 1706 and the second strip 1708 are oriented as alternating or complementary spirals that extend from the distal end 1702 to the proximal end 1704 of the sheath body 1700 to form a cylindrical lumen. As described in more detail below in connection with FIG. 19 , the inner diameter of the lumen, the width of the first strip 1706 and the second strip 1708, and the twist angle are interrelated, and corresponding values ​​are selected to obtain desired sheath characteristics. The lumen can be sized to allow for the insertion of a medical device. For example, the lumen can be sized to allow for the insertion of a percutaneous pump. The inner diameter of the lumen can range from 3 Fr (1 mm) to 23 Fr (7.67 mm). The length of the sheath body 1700 can range from 7 cm (e.g., for percutaneous axillary / subclavian insertion) to 45 cm (e.g., for transfemoral insertion). For percutaneous access via the axillary / subclavian artery, the sheath body length can be shorter. In contrast, for percutaneous access via the femoral artery, a longer sheath body is required.

[0088] The first strip 1706 and the second strip 1708 are made of materials with different flexibility and stiffness. For example, the first strip 1706 is made of a first material having a first stiffness, and the second material is made of a second material having a second stiffness. The first stiffness can be higher than the second stiffness. Examples of materials that can be used as the first and second materials include polyether block amide (PEBA) materials, polyethylene materials, and thermoplastic elastomers. Examples of PEBA materials that can be used as the first and second materials include PEBAX 7233 and PEBEX 3533, respectively. Low-density polyethylene (LDPE) and high-density polyethylene (HDPE) are examples of polyethylene materials that can be used as the first material. Examples of thermoplastic elastomers that can be used as the second material include styrene ethylene butylene styrene (SEBS) and ethylene vinyl acetate (EVA). For example, the first strip 206 can be made of PEBAX 7233, and the second strip 1708 can be made of EVA. At least one advantage of juxtaposing first and second strips having different material properties is the ability to select a particular stiffness for the introducer sheath as a whole.

[0089] The distal end 1702 of the sheath body 1700 can include a tapered tip. The tapered tip maintains a constant inner diameter of the lumen of the sheath body 1700 but tapers the outer wall of the sheath body 1700 to allow for a smooth transition at the distal end 1702 of the sheath body 1700. The tapered tip can be formed from a first material of the first strip 1706, a second material of the second strip 1708, both the first and second materials, or a third material. If the tapered tip is formed from both the first and second materials, the tapered tip can be manufactured by thermoforming the sheath body 1700 in a mold. If the tapered tip is formed from only the first material, only the second material, or only the third material, the tapered tip can be manufactured by thermoforming a small tube of the selected tapered tip material onto the distal end 1702 of the sheath body 1700. At least one advantage of a tapered tip is that it may minimize trauma to the vasculature when inserting the sheath, while maintaining desirable material properties for the sheath.

[0090] FIG. 19 shows a schematic profile of the flexible sheath body 1700 of FIG. 17 , in which the first strip 1706 has a first width 1710 and the second strip 1708 has a second width 1712. Also shown in FIG. 19 is a twist angle 1714. The twist angle 1714 is defined as the arctangent of the ratio of the inner diameter of the lumen of the sheath body 1700 to the thicker of the first width 1710 and the second width 1712. The first width 1710 and the second width 1712 can range from 0.17 mm to 3.83 mm. In one aspect, the first width 1710 and the second width 1712 can be the same width. For example, the first width 1710 and the second width 1712 can be 1 mm. In another aspect, the first width 1710 and the second width 1712 can be different widths. For example, the first width 1710 can be 3 mm and the second width can be 1 mm. The twist angle can vary from 0° to 90°. In a helical design, the twist angle 1714 is preferably in the range of 60° to 80°. As described above, the sheath body 1700 can alternatively have a ring design including alternating rings of material with different stiffnesses or a longitudinal strip design including alternating strips of material with different stiffnesses. If a ring design is used, the twist angle 1714 is 90° because each ring is perpendicular to the lumen of the sheath body 1700. If a longitudinal strip design is used, the twist angle 1714 is 0° because each strip is parallel to the lumen of the sheath body 1700.

[0091] As described above, the sheath body 1700 can have a notch that facilitates peel-away of the sheath body 1700. The notch can be triangular and form a portion of the wall of the sheath body 1700. The wall of the sheath body 1700 can have a thickness ranging from 0.1 mm to 1.67 mm. The notch can occupy 50% to 90% of the total wall thickness. For example, the notch thickness can be 0.05 mm to 1.5 mm. Figures 20 and 21 show an exemplary sheath body 1800 including a first internal notch 1802 and a second internal notch 1804. The first internal notch 1802 and the second internal notch 1804 can be axially aligned along the length of the sheath body 1800 and oriented opposite each other. The first internal notch 1802 and the second internal notch 1804 extend along the inner surface of the sheath body 1800. 9, the first internal notch 1802 and the second internal notch 1804 can be formed on a mandrel during manufacture of the sheath body 1800. Similarly, the internal notch 1606 of the sheath hub 1602 can be formed on a core pin during manufacture of the sheath hub 1602. Providing notches on the inner surface of the sheath body helps maintain the smooth, circular outer profile of the sheath body while allowing for easier peel-away of the sheath by breaking the helices of the first strip 1706 and the second strip 1708.

[0092] Alternatively, the notches on the sheath body can be on the outer surface of the sheath body. Figures 22 and 23 show an exemplary sheath body 1900 including a first outer notch 1902 and a second outer notch 1904. The first outer notch 1902 and the second outer notch 1904 can be axially aligned along the length of the sheath body 1900 and oriented opposite one another. The first outer notch 1902 and the second outer notch 1904 can be cut into the sheath body 1900 by skiving. Similarly, the outer notch 1606 of the sheath hub 1602 can be cut, at least in part, into the sheath hub 1602 by skiving. In another aspect, the outer notch 1606 of the sheath hub 1602 can be formed by geometry in a mold during manufacturing of the sheath hub 1602. Providing the notches on the outer surface of the sheath provides a smooth, circular inner surface of the sheath to facilitate the passage of inserting instruments and devices.

[0093] The sheath body 1700 can be fabricated using a lamination process in which a first strip 1706 and a second strip 1708 are wrapped around a lamination mandrel and heated to bond them together. FIG. 24 illustrates a process 1900 for manufacturing the flexible sheath body 1700 by lamination, as described above in connection with FIG. 17 . In step 1702, a first strip 1706 of a first material and a second strip 1708 of a second material are adjacently wrapped around a mandrel. As described above in connection with FIG. 17 , the first strip 1706 and the second strip 1708 can be made of materials having different flexibilities and stiffnesses. For example, the first strip 1706 can be made of a first material having a first stiffness, and the second material can be made of a second material having a second stiffness. The first stiffness can be higher than the second stiffness.

[0094] At step 1904, the first distal end of first strip 1706 and the second distal end of second strip 1708 are secured. For example, the first distal end of first strip 1706 and the second distal end of second strip 1708 can be clamped in place relative to a mandrel. Alternatively, the distal ends can be confined within a constraining sheath or held in place by a temporary adhesive.

[0095] At step 1906, a first proximal end of first strip 1706 and a second proximal end of second strip 1708 are secured. Any of the methods used to secure the distal ends of strips 1706 and 1708 can be used to secure the proximal ends of strips 1706 and 1708.

[0096] At step 1908, heat shrink tubing is placed over the first strip 1706, the second strip 1708, and the mandrel. When heat is applied to the heat shrink tubing, it heats the first strip 1706 and the second strip 1708, bonding them to each other along the helical edge of each strip. The heat shrink tubing can be made of polytetrafluoroethylene (PTFE) material, fluorinated ethylene propylene (FEP), or other suitable heat shrink material. The energy source used to apply heat to the heat shrink tubing can be a laser beam or any other suitable heat generating method.

[0097] At step 1910, the heat shrink tubing, first strip 1706, and second strip 1708 are heated. During heating, the heat shrink tubing material remains intact (i.e., does not melt), but first strip 1706 and second strip 1708 reflow and bond together along the helical edge of each strip.

[0098] At step 1912, the heat shrink tubing is removed, leaving the adhered first strip 1706 and second strip 1708 on the mandrel.

[0099] In step 1914, the sheath body 1700 formed by the bonded first and second strips 1706 and 1708 is removed from the mandrel. For example, the timing at which the bonded strips can be removed from the mandrel as a whole can depend on the amount of time required for the bonded strips to cool down after the heat shrinking process is complete. As described above in connection with FIGS. 19 and 20 , the mandrel can include protrusions having triangular geometries that can form internal notches 1802 and 1804 on the sheath body 1700. The triangular geometries on the mandrel can be axially aligned along the length of the mandrel and oriented opposite each other. The triangular geometries on the mandrel can have the desired dimensions of the internal notches 1802 and 1804. For example, the height of the triangular geometries on the mandrel can range from 0.05 mm to 1.5 mm. At least one advantage of the above manufacturing method includes the ability to obtain a sheath by uniformly bonding strips of two different materials to obtain a sheath with composite material properties that have improved flexibility and kink resistance for introducing the sheath into the patient's vasculature.

[0100] As described above, the sheath body can be made from two strips of material having different stiffnesses. Alternatively, the sheath body can include a lumen made from a third material. FIG. 25 shows an exemplary sheath body 2100 including a first strip 2102 made from a first material, a second strip 2104 made from a second material, and a lumen 2106. In one aspect, the sheath body 2100 includes a ring design including alternating rings of materials having different stiffnesses. In another aspect, the sheath body 2100 includes a longitudinal strip design including alternating strips of materials having different stiffnesses. The lumen 2106 can be made from a third material having the same or different stiffness as the first and / or second material. In one aspect, the lumen 2106 can be made from the same material as the first strip 2102 or the second strip 2104. In another aspect, the lumen 2106 can be made from a slippery material such as PTFE or FEP. Similar to the sheath body 1800 detailed in connection with FIGS. 20 and 21 , the sheath body 2100 includes a first external notch 2108 and a second external notch 2110. The first external notch 2108 and the second external notch 2110 can be axially aligned along the length of the sheath body 2100 and oriented opposite one another. The first external notch 2108 and the second external notch 2110 can pass through the thickness of the first strip 2102 and the second strip 2104. Alternatively, the first external notch 2108 and the second external notch 2110 can pass through the thickness of the first strip 2102 and the second strip 2104 and continue partially, but not completely, through the thickness of the lumen 2106. As described above, the first external notch 2108 and the second external notch 2110 can be cut into the sheath body 2100 by skiving. Alternatively, as detailed in connection with Figures 20 and 21, the notches can be on the interior surface such that the first strip 2102 and second strip 2104 are surrounded by an outer tube.The inclusion of the lumen 2106 in the sheath body 2100 achieves a consistent and smooth tear propagation compared to the sheath bodies 1700, 1800, and 1900. Having the first external notch 2108 and the second external notch 2110 extend partially through the thickness of the lumen 2106 increases the likelihood that the tear will propagate along the notch and decreases the likelihood that the tear will propagate along the interface between the first strip and the second strip.

[0101] The foregoing is merely illustrative of the principles of the present disclosure, and the device may be implemented with aspects other than those presented by way of example and not limitation. It will be understood that while the device disclosed herein is shown for use in percutaneous insertion of a blood pump, it may also be adapted for use in devices in other applications requiring hemostasis.

[0102] Variations and modifications will occur to those skilled in the art after considering this disclosure. The disclosed features may be implemented in any combination and subcombination (including multiple subcombinations and subcombinations) with one or more other features described herein. The various features, including any component parts thereof, may be combined or integrated into other systems. Moreover, certain features may be omitted or not implemented.

[0103] Examples of changes, substitutions and variations are ascertainable by one skilled in the art and can be made without departing from the scope of the information disclosed herein. All references cited herein are incorporated by reference in their entirety and constitute a part of this application.

Claims

1. below: With peel away sheath hub; A peel away sheath body, a proximal end connected to the peel away sheath hub; Distal end, an outer layer defining an outer radius of the peel away sheath body; an inner layer defining a first lumen of the peel away sheath body having an inner radius; and a reinforcing layer located between the inner radius and the outer radius and having a stiffness greater than at least one of the stiffness of the inner layer and the stiffness of the outer layer; Includes peel away sheath body and A peel away sheath assembly for insertion of a blood pump, comprising:

2. 10. The peel away sheath assembly of claim 1, wherein the reinforcing layer is a hypotube.

3. 3. The peel away sheath assembly of claim 1 or 2, wherein the reinforcing layer includes at least two circumferential discontinuities.

4. 4. The peel away sheath assembly of claim 1, wherein each of the at least two circumferential discontinuities comprises a slit formed in a surface of the hypotube.

5. 5. The peel away sheath assembly of any one of claims 1 to 4, wherein the slits on the surface of the hypotube are parallel to each other and equally spaced along the length of the hypotube.

6. 6. The peel away sheath assembly of any one of claims 1 to 5, wherein the slits on the surface of the hypotube have a circumferential length, and wherein the length of the slits is substantially the same for all of the slits.

7. The slits are as follows: a first set of slits, each slit in the first set of slits having a center, the centers of each slit in the first set of slits forming a first slit axis along a length of the hypotube; a second set of slits, each slit in the second set of slits having a center, the centers of each slit in the second set of slits forming a second slit axis along the length of the hypotube; and and wherein the second slit axis is offset from the first axis by an angle.

8. further comprising first and second peel away lines on a surface of the peel away sheath body; 8. The peel-away sheath assembly of any one of claims 1 to 7, wherein at any longitudinal position along the peel-away sheath body, a first slit axis is at the same circumferential position as the first peel-away line and a second slit axis is at the same circumferential position as the second peel-away line.

9. 9. The peel away sheath assembly of any one of claims 1 to 8, wherein at least one of the peel away lines is located on an inner surface of the peel away sheath body.

10. The peel away sheath assembly of any one of claims 1 to 8, wherein at least one of the peel away lines is located on an outer surface of the peel away sheath body.

11. 11. The peel away sheath assembly of any one of claims 1 to 10, wherein the first and second peel away lines are diametrically opposed to one another.

12. Peel away sheath hub, a proximal cone-shaped portion, and Distal cylindrical section 12. The peel away sheath assembly of claim 1, further comprising:

13. 13. The peel away sheath assembly of any one of claims 1-12, wherein the proximal conical portion comprises a proximal circumferential discontinuity and the distal cylindrical portion comprises a distal circumferential discontinuity.

14. The peel away sheath assembly of any one of claims 1 to 13, wherein the proximal circumferential discontinuity and the distal circumferential discontinuity are longitudinally aligned.

15. The peel away sheath assembly of any one of claims 1 to 14, wherein a distal end of the distal circumferential discontinuity abuts a proximal end of at least one peel away line along a surface of the peel away sheath body.

16. 16. The peel away sheath assembly of any one of claims 1 to 15, wherein the inner layer and the outer layer comprise a thermoplastic resin.

17. The peel away sheath assembly of any one of claims 1 to 16, wherein the thermoplastic resin is at least one of PEBAX or TPU.

18. 18. The peel away sheath assembly of any one of claims 1-17, wherein the reinforcement layer is at least one of LCP, PEBAX, stainless steel, Nitinol, or Kevlar.

19. 19. The peel away sheath assembly of any one of claims 1 to 18, wherein the reinforcement layer is present only on a distal portion of the peel away sheath body.

20. The peel away sheath assembly of any one of claims 1 to 18, wherein the reinforcement layer is present only in a proximal portion of the peel away sheath body.

21. 19. The peel away sheath assembly of any one of claims 1 to 18, wherein the reinforcing layer is present only in an intermediate portion of the peel away sheath body.

22. 19. The peel away sheath assembly of any one of claims 1 to 18, wherein the reinforcement layers are present in alternating portions along a length of the peel away sheath body.

23. The peel away sheath assembly of any one of claims 1-22, wherein the hypotube is configured as two C-shaped halves.

24. 24. The peel away sheath assembly of any one of claims 1 to 23, wherein the peel away line on the inner surface of the peel away sheath body extends along an entire length of the peel away sheath body.

25. 25. The peel away sheath assembly of any one of claims 1-24, wherein the hydrophilic coating covers at least a portion of an outer layer of the peel away sheath body.

26. 26. The peel away sheath assembly of any one of claims 1 to 25, wherein the portion of the outer layer coated with the hydrophilic coating extends from the distal end of the peel away sheath body to about 5 cm distal from the proximal end of the peel away sheath body.

27. 27. The peel away sheath assembly of any one of claims 1 to 26, wherein the portion of the outer layer coated with the hydrophilic coating extends from the distal end of the sheath body to about 2 cm distal from the proximal end of the peel away sheath body.

28. below: With peel away sheath hub; A peel away sheath body, a proximal end connected to the peel away sheath hub; Distal end, an outer layer defining an outer radius of the peel away sheath body; an inner layer defining a first lumen of the peel away sheath body, the inner layer having an inner radius; a reinforcing layer located between the inner radius and the outer radius; and a pair of diametrically opposed notches extending radially through at least one of the inner layer or the outer layer; Includes peel away sheath body and A peel away sheath assembly for insertion of a blood pump, comprising:

29. 29. The peel away sheath assembly of any one of claims 1-28, wherein the notch is an inner diameter notch extending from the innermost surface of the inner layer through the reinforcement layer.

30. The peel away sheath assembly of any one of claims 1-29, wherein the notch terminates before the outer layer.

31. The peel away sheath assembly of any one of claims 1-30, wherein the notch terminates in the outer layer.

32. 32. The peel away sheath assembly of any one of claims 1-31, wherein the notch is an outer diameter notch extending from an outermost surface of the outer layer through the reinforcing layer.

33. The peel away sheath assembly of any one of claims 1-32, wherein the notch terminates short of the inner layer.

34. The peel away sheath assembly of any one of claims 1-33, wherein the notch terminates within the inner layer.

35. 35. The peel away sheath assembly of any one of claims 1 to 34, wherein a pair of diametrically opposed notches define a pair of diametrically opposed peel away lines on a surface of the peel away sheath body, each of the pair of peel away lines extending along a length of the peel away sheath body, and the peel away sheath body can be separated along the peel away lines.

36. 36. The peel away sheath assembly of any one of claims 1 to 35, wherein a surface of the peel away sheath body is an inner surface.

37. The peel away sheath assembly of any one of claims 1 to 36, wherein the surface of the peel away sheath body is an exterior surface.

38. The peel away sheath assembly of any one of claims 1 to 37, wherein the reinforcement layer is present only on a proximal portion of the peel away sheath body.

39. 39. The peel away sheath assembly of any one of claims 1-38, wherein at any longitudinal location along a peel away sheath body having a pair of diametrically opposed notches, each notch in the pair of notches is located at the same circumferential location as a peel away line defined by the notch.

40. below: With peel away sheath hub; A peel away sheath body, a proximal end connected to the peel away sheath hub; Distal end, an outer layer defining an outer radius of the peel away sheath body; an inner layer defining a first lumen of the peel away sheath body, the inner layer having an inner radius; a reinforcing layer located between the inner radius and the outer radius; at least one pair of diametrically opposed internal notches extending through the internal layer to a fourth radius between the internal radius and the third radius; and at least one pair of diametrically opposed second external notches extending through the outer layer to a fifth radius between the inner radius and the third radius; Includes peel away sheath body and A peel away sheath assembly for insertion of a blood pump, comprising:

41. a first internal notch extending along a first longitudinal segment of the peel away sheath body; The peel away sheath assembly of any one of claims 1-40, wherein a second external notch extends along a second longitudinal segment of the peel away sheath body.

42. The peel away sheath assembly of any one of claims 1 to 41, wherein the first segment and the second segment partially overlap in the longitudinal direction.

43. The peel away sheath assembly of any one of claims 1-42, wherein the first segment and the second segment completely overlap.

44. 44. The peel away sheath assembly of any one of claims 1 to 43, wherein at least one pair of diametrically opposed first internal notches and at least one pair of diametrically opposed second external notches define a pair of diametrically opposed peel away lines, each of the pair of peel away lines extending along a length of the peel away sheath body, along which the peel away sheath body can be separated.

45. The peel away sheath assembly of any one of claims 1-44, wherein each peel away line of a pair of peel away lines is formed by both an inner notch and an outer notch.

46. 46. ​​The peel away sheath assembly of any one of claims 1-45, wherein the reinforcement layer includes a first set of discontinuities extending along the length of the sheath and a second set of discontinuities extending along the length of the peel away sheath body.

47. The peel-away sheath assembly of any one of claims 1 to 46, wherein at any longitudinal position along the peel-away sheath body, an axis of a first set of discontinuities is at the same circumferential position as a first peel-away line and an axis of a second set of discontinuities is at the same circumferential position as a second peel-away line.

48. 1. A method for manufacturing a peel-away sheath assembly for insertion into a blood pump, the peel-away sheath assembly including a peel-away sheath body and a peel-away sheath hub, the method comprising: coating a mandrel with a first layer of a first material; heat shrinking the first layer; coating the heat shrunk first layer with a second layer of a second material, which is a reinforcing layer, and an outermost third layer of a third material; and heat shrinking the first, second and third layer materials. A method comprising:

49. 49. The method of manufacturing a peel-away sheath assembly for insertion into a blood pump as described in any one of claims 1 to 48, wherein the mandrel has a raised protrusion configured to leave at least one internal diameter notch in the heat-shrunk sheath body, the at least one internal diameter notch extending from the innermost surface of the first layer, passing through the second layer, and terminating short of or within the third layer.

50. below: With peel away sheath hub; A peel away sheath body, a proximal end connected to the peel away sheath hub, a middle segment, a distal end, a proximal segment between the proximal end and the middle segment, and a distal segment between the middle segment and the distal end; an outer layer defining an outer radius of the sheath; an inner layer defining a first lumen of the peel away sheath body having an inner radius; and a reinforcing layer located in the intermediate segment between the inner layer and the outer layer, the reinforcing layer having a stiffness greater than at least one of the stiffness of the inner layer and the stiffness of the outer layer; Includes peel away sheath body and A peel away sheath assembly for insertion of a blood pump, comprising:

51. The peel away sheath assembly of any one of claims 1-50, wherein the reinforcement layer is located in the proximal segment.

52. The peel away sheath assembly of any one of claims 1-51, wherein the reinforcement layer is located in the distal segment.

53. below: With peel away sheath hub; A peel away sheath body, a proximal end connected to the peel away sheath hub, a middle segment, a distal end, a proximal segment between the proximal end and the middle segment, and a distal segment between the middle segment and the distal end; an outer layer defining an outer radius of the peel away sheath body and comprising an outer layer material; an inner layer defining a first lumen of the sheath having an inner radius and comprising an inner layer material; a reinforcing layer located in the intermediate segment between the inner layer and the outer layer, the reinforcing layer including a material having a stiffness greater than at least one of the stiffness of the inner layer material and the stiffness of the outer layer material; Includes peel away sheath body and A peel away sheath assembly for insertion of a blood pump, comprising:

54. The peel away sheath assembly of any one of claims 1-53, wherein the reinforcement layer is located in the proximal segment.

55. The peel away sheath assembly of any one of claims 1-54, wherein the reinforcement layer is located in the distal segment.

56. below: With peel away sheath hub; A peel away sheath body, a proximal end connected to the peel away sheath hub; Central longitudinal section, Distal end, an outer layer defining an outer radius of the peel away sheath; an inner layer defining a peel away sheath body lumen, the inner layer having an inner radius; a reinforcing hypotube located between the inner layer and the outer layer, the hypotube having a stiffness greater than at least one of the stiffness of the inner layer and the stiffness of the outer layer; Including, the reinforcing hypotube is configured with two longitudinally extending C-shaped halves, the reinforcing hypotube being configured to extend along the central longitudinal section; the inner layer further includes a peel-away line extending longitudinally and continuously along the sheath body; Peel Away Sheath Body and A peel away sheath assembly for insertion of a blood pump, comprising:

57. The peel away sheath assembly of any one of claims 1-56, wherein the reinforcing hypotube is configured to extend into a proximal portion of the peel away sheath body.

58. The peel away sheath assembly of any one of claims 1-57, further comprising a hydrophilic coating extending on a longitudinal portion of the outer layer.

59. A sheath body for insertion of a blood pump, comprising: a first strip of a first material having a first stiffness; and a second strip of a second material having a second stiffness Including, the first stiffness is greater than the second stiffness; the first strip and the second strip are adjacently and helically oriented from the distal end to the proximal end of the sheath body; Sheath body.

60. 60. The sheath body of any one of claims 1-59, wherein the first material comprises one of a polyether block amide (PEBA) and a polyethylene, and the second material comprises one of a PEBA and a thermoplastic elastomer.

61. The sheath body of any one of claims 1-60, wherein the first strip and the second strip have the same width.

62. The sheath body of any one of claims 1-61, wherein the first width of the first strip and the second width of the second strip are 1 mm.

63. The sheath body of any one of claims 1-62, wherein the first strip and the second strip have different widths.

64. The sheath body of any one of claims 1-63, wherein the first width of the first strip is 3 mm and the second width of the second strip is 1 mm.

65. a wall having a thickness; and A first notch and a second notch in the wall. Further comprising: the first notch and the second notch are axially aligned along a length of the sheath body and oriented opposite one another; The sheath body of any one of claims 1 to 64.

66. The sheath body of any one of claims 1-65, wherein the first notch and the second notch are on an inner surface of the sheath body.

67. The sheath body of any one of claims 1-66, wherein the first notch and the second notch are on an outer surface of the sheath body.

68. The sheath body of any one of claims 1 to 67, wherein the sheath body is split in two along the first notch and the second notch during peel away of the sheath body.

69. The sheath body of any one of claims 1-68, further comprising a tapered tip.

70. The sheath body of any one of claims 1-69, wherein the tapered tip comprises a first material and a second material.

71. The sheath body of any one of claims 1-70, wherein the tapered tip comprises only the first material.

72. The sheath body of any one of claims 1-71, wherein the tapered tip comprises only the second material.

73. below: a sheath body having a proximal end and a distal end, a first strip of a first material having a first stiffness; a second strip of a second material having a second stiffness; wherein the first stiffness is greater than the second stiffness; wherein the first strip and the second strip are contiguous and spirally oriented from the distal end to the proximal end of the sheath body; and a first lumen defined by the first strip and the second strip; a sheath body including: a sheath hub having a proximal end and a distal end defining a second lumen, wherein the distal end of the sheath hub is attached to the proximal end of the sheath body; Sheath Hub and an introducer sheath for insertion of a blood pump,

74. The introducer sheath of any one of claims 1-73, wherein the first lumen and the second lumen are in fluid communication.

75. The introducer sheath of any one of claims 1-74, wherein the sheath hub further comprises a hemostatic valve sized to prevent fluid from exiting a proximal end of the hub.

76. the sheath hub further includes a first notch and a second notch; The introducer sheath of any one of claims 1-75, wherein the first notch and the second notch are axially aligned along a length of the sheath hub and oriented opposite one another.

77. The introducer sheath of any one of claims 1-76, wherein the first notch and the second notch are on an inner surface of the sheath hub.

78. The introducer sheath of any one of claims 1-77, wherein the first notch and the second notch are on an outer surface of the sheath hub.

79. 1. A method of manufacturing a flexible introducer sheath body, comprising: wrapping a first strip of a first material and a second strip of a second material in adjacent relation around a mandrel; securing a first distal end of the first strip and a second distal end of the second strip; securing a first proximal end of the first strip and a second proximal end of the second strip; placing a heat shrink tube over the first strip, the second strip and the mandrel; heating the first strip and the second strip; removing the heat shrink tubing; and removing the first strip and the second strip from the mandrel. A method comprising:

80. A sheath body for insertion of a blood pump, comprising: a first strip of a first material having a first stiffness; a second strip of a second material having a second stiffness; wherein the first stiffness is greater than the second stiffness; and a lumen defined by the distal and proximal ends of the sheath body; Including, the first strip and the second strip are adjacently and helically directed over the lumen from the distal end to the proximal end of the sheath body. Sheath body.

81. The sheath body of any one of claims 1-80, wherein the second stiffness is greater than a third stiffness of the lumen.

82. an exterior wall having a first thickness; an inner wall having a second thickness; and A first notch and a second notch in the outer wall. Further comprising: The sheath body of any one of claims 1-81, wherein the first notch and the second notch are axially aligned along a length of the sheath body and oriented opposite one another.

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