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 content of which is incorporated herein by reference as Appendix A, and U.S. Provisional Patent Application No. 62 / 802,454, filed Feb. 7, 2019, the content of which is incorporated herein by reference as Appendix B.

Background Art

[0002] background After a patient has a heart attack, mechanical circulatory support devices are often introduced to assist the function of the heart. In some applications, a heart pump is inserted into the heart through the patient's vasculature to assist in reducing the load on the heart. The pump can be configured to draw blood from the left ventricle of the heart and pump it into the aorta; or to draw blood from the inferior vena cava (IVC), bypass the right atrium and right ventricle, and pump the blood into the pulmonary artery. Some systems operate the pump with an on-board motor, while other systems 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 vasculature. Other systems use pumps that do not enter the heart but remain in the aorta or other blood vessels.

[0003] Mechanical circulatory support devices (such as intracardiac heart pump assemblies) or other medical devices can be introduced into a patient in a variety of ways. A common technique is to introduce them surgically or percutaneously into the vasculature during a cardiac procedure. For example, a catheterization method using a sheath such as a peel-away introducer sheath can be applied to the femoral artery. In another technique, the sheath can be inserted through an axillary or subclavian insertion site. Alternatively, the sheath can also be inserted at other locations, such as the femoral vein or any route for delivery of a pump to support the left or right side of the heart.

[0004] To form an insertion route for the pump assembly, the introducer sheath can be inserted into the femoral artery through the arterial incision. A portion of the device is then advanced into the artery through the lumen of the introducer sheath. Once the device (e.g., the pump assembly) is inserted, the introducer sheath is peeled away. The repositioning sheath can then be advanced, for example, from above the pump assembly into the arterial incision. Replacing the introducer sheath with the repositioning sheath during the insertion of the medical device improves the fixation of the repositioning sheath to the patient when used with a hemostatic valve, thereby reducing lower limb ischemia and bleeding at the skin insertion site (or intravascular insertion site).

[0005] Peel-away sheaths offer the advantage of forming vascular access and allowing passage of medical devices, and have the option of removing the sheath by separating it into two compartments. As referenced herein, the sheath may be an introducer sheath; a repositioning sheath; or any other peel-away sheath used with a vascular device.

[0006] A flexible and kink-resistant introducer sheath is desirable due to the bending forces the sheath experiences as it is introduced along the introduction route. The route follows the axis of the sheath, passing through the surface arterial incision, then through the tissue, and then into the blood vessel. The route is oblique to the surface of the patient's skin at the insertion site. After reaching the blood vessel, the sheath transitions to follow the route of the vessel (e.g., the femoral artery). The insertion angle may vary depending on the individual patient, procedure, and the operator using the sheath. The vascular axis may vary depending on the patient and the part of the vascular system into which the introducer sheath is inserted. The angle between the insertion axis and the vascular 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 larger this angle, the more likely the introducer sheath is to kink during axial transition. Because any sheath has a finite length, a larger insertion angle is usually required for deeper vessels to maintain a minimum desirable portion (2cm-5cm) of the introducer in the artery. Clinicians using ultrasound typically use a larger insertion angle to aid in the visualization of the access needle, ultimately resulting in a larger sheath insertion angle. In obese patients, some femoral insertions kink because the vessel is relatively deep relative to the insertion point. Tortuosity, particularly in the iliac crest, can also cause the sheath to kink. Percutaneous axillary insertions, in particular, are deeper and require a larger insertion angle than femoral insertions to avoid hitting nerve bundles in areas 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 is done in some catheters. However, structural reinforcement is usually incompatible with peel-away functionality. Preferred reinforcement materials are generally those with a relatively high modulus of elasticity, i.e., materials that can impart relatively high rigidity to the structural reinforcement, such as metals. Due to their material properties, these reinforcement materials also make peel-away of the device difficult or impossible. Polymer reinforcement layers are sometimes used as structural reinforcement, but 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 compared to, for example, metals. [Overview of the project]

[0008] overview The systems, methods, and apparatus described herein provide flexible introducer sheaths having improved kink resistance and improved flexibility, and peel-away sheath functionality, for introducing vascular devices, such as intracardiac blood pump systems or other mechanical circulatory support devices, into a patient's vascular system. Such improved functionality of introducer sheaths can be achieved in a variety of ways, as disclosed herein. Generally, the sheath has at least two compartments of different stiffness, one stiff compartment, and at least one low-stiffness compartment. The improved sheath allows for improved kink resistance. One exemplary configuration having at least one high-stiffness compartment and at least one low-stiffness compartment is a sheath having an inner layer, a second reinforcing layer, and an outer layer. One embodiment provides a multilayer sheath structure including a reinforcing layer configured to have at least two discontinuities along its length. The practitioner can then apply a peel-away force to the sheath and split the sheath along the discontinuities of the reinforcing layer. One or more notches may be included along the sheath, which also facilitate peel-away of the sheath. One or more notches extend from the outermost or innermost part 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 away the sheath. At least one advantage of the notches is their ability to define the line along which the sheath is peeled away, and by aligning those lines with discontinuities in the reinforcing layer, the amount of force required to peel away the sheath can be reduced.

[0009] According to a first aspect of the present disclosure, a peel-away assembly for insertion of 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, the proximal end portion being connected to the peel-away sheath hub. The peel-away sheath body further has an outer layer, an inner layer and a reinforcing layer located between the inner and outer layers. The outer layer defines the outer radius of the sheath, and the inner layer of the peel-away sheath body defines the lumen of the sheath having an inner radius. The inner layer further includes a peel-away line. The peel-away line is configured as a radially extending notch, the notch extending 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 hypotubule has a stiffness greater than at least one of the stiffness of the inner layer and the stiffness of the outer layer. The reinforcing hypotubule extends along the middle 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 proximal 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 approximately 2 cm proximal beyond the distal end of the peel-away sheath hub. A specific longitudinal point where the distal end of the peel-away sheath hub terminates is selected to give the peel-away sheath body the 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 vascular system when the peel-away sheath body is inserted into a patient.

[0010] In another aspect of this 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 lumen extending in the longitudinal direction. In some configurations, the distal end portion and the proximal end portion contain 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 material may differ between the distal end portion and the proximal end portion. For example, the inner layer of the distal end portion may contain PEBAX and the inner layer of the proximal end portion may contain TPU, or vice versa. Similarly, the outer layer material may differ between the distal end portion and the proximal end portion. For example, the outer layer of the distal end portion may contain PEBAX and the inner layer of the proximal end portion may contain TPU, or vice versa. In some embodiments, the reinforcing layer is constructed of different materials between the distal and proximal layers. For example, the reinforcing 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 reinforcing 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 lumen extending in the longitudinal direction. In some embodiments, the reinforcing layer does not extend into the proximal end portion and does not extend 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 reinforcing 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 reinforcing 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 includes SAE 304 stainless steel. In further embodiments, the PEBAX layer includes at least one of PEBAX 3533 to 7233. In some embodiments, the reinforcing layer extends into the proximal end portion. In other embodiments, the reinforcing layer extends into the distal end portion. In some embodiments, the reinforcing layer extends into both the distal and proximal end portions. In some embodiments, the inner diameter of the peel-away sheath body is substantially constant throughout its entire length. In other embodiments, the proximal end portion of the peel-away sheath body may have a smaller outer diameter than the outer diameter of the distal end portion. One advantage of a configuration with a proximal end portion having a reduced outer diameter is that, because there is less material to break, the operator can break the peel-away sheath hub with less force.

[0012] In some configurations, the peel-away sheath body includes an inner layer located at the inner radius, an outer layer located at the 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 where the hydrophilic coating is located extends from the distal end of the peel-away sheath body to about 5 cm to about 2 cm distal to the proximal end of the peel-away sheath body. In other embodiments, the portion of the outer layer where the hydrophilic coating is located extends from the distal end of the peel-away sheath body to about 4 cm to about 3 cm distal to the proximal end of the sheath body. In further embodiments, the portion of the outer layer where the hydrophilic coating is located extends from the distal end of the peel-away sheath body to about 3.5 cm distal to the proximal end of the peel-away sheath body. The hydrophilic coating facilitates the insertion of the peel-away sheath body into the patient's vascular system. If the entire length of the peel-away sheath body is coated with a hydrophilic coating, there is a risk that the peel-away sheath body may be pushed away from the aorta due to the arterial pressure acting on it. Therefore, the proximal end portion of the peel-away sheath body is generally configured without a hydrophilic coating.

[0013] In some configurations, the distal and proximal portions may contain the same material in the same layer. For example, the inner layers of both the distal and proximal portions may contain PEBAX, and the outer layers of both portions may contain TPU. In further embodiments, the intermediate portion contains a different material from the distal and proximal portions. In some embodiments, the reinforcing layer is present only in the intermediate portion of the peel-away sheath body, while the distal and proximal portions of the peel-away sheath body do not. For example, the distal and proximal portions may have an inner PEBAX layer and an outer TPU layer, while the intermediate portion may have an inner PEBAX layer, a stainless steel reinforcing layer, and an outer TPU layer. One advantage of a configuration with a reinforcing layer only in the intermediate portion of the peel-away sheath body is that it is relatively easier to manufacture compared to a configuration with a reinforcing layer along the entire length of the peel-away sheath body. The absence of a reinforcing layer at the distal end of the peel-away sheath body allows for easier formation of a tapered distal tip, as the absence of the reinforcing layer enables the inner and outer layers to reflow. Reflow of the polymer layers provides the peel-away sheath body with increased ability to withstand stress when it is bent as it is introduced into or navigated through the patient's vascular system. The reflow process can generally be controlled by melting the material at various temperatures to achieve various process setpoints. In addition, the absence of a reinforcing layer at the proximal end of the peel-away sheath body helps stabilize the injection molding process, allowing the polymer layers of the peel-away sheath body to be molded to the peel-away sheath hub with consistent properties.

[0014] The length of the peel-away sheath body where the reinforcing layer extends can be adjusted to prevent kinking along a specific portion of the peel-away sheath body. For example, in some embodiments, the reinforcing layer is present in the middle portion but not in the distal end portion. In such embodiments, the reinforcing layer may extend over a variable length of the proximal end portion of the peel-away sheath body. For example, the proximal end of the reinforcing layer may terminate at the same major axis point where the distal end of the sheath hub terminates. In other embodiments, the reinforcing layer may extend proximal beyond the distal end of the peel-away sheath hub. In some embodiments, the reinforcing layer extends proximal about 2 cm beyond the distal end of the peel-away sheath hub. In other embodiments, the reinforcing layer extends proximal about 1 cm beyond the distal end of the peel-away sheath hub. The specific point where the reinforcing 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 of the peel-away sheath body may include a tapered tip designed to reduce trauma to the vascular system when the peel-away sheath body is inserted into the patient.

[0015] The reinforcing layer has material properties that favorably provide improved kink resistance to the peel-away sheath assembly. For example, one such property of the reinforcing 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. As an example, the modulus of elasticity of the reinforcing layer is the modulus of elasticity of the reinforcing layer material, which is higher than that of the inner or outer layer material. In some embodiments, the rigidity of the reinforcing layer material is higher than that of the inner or outer layer material. In some configurations, the rigidity of the reinforcing layer material is about 18 to about 12,000 times that of the inner or outer layer material. In other configurations, the rigidity of the reinforcing layer material is about 100 to about 9,000 times that of the inner or outer layer material. In other embodiments, the stiffness of the reinforcing layer material is about 75 to 100 times that of the inner or outer layer material. In further embodiments, the stiffness of the reinforcing layer material is about 400 to 500 times that of the inner or outer layer material. In certain configurations, the stiffness of the reinforcing layer material is about 1,000 to 7,000 times that of the inner or outer layer material. In further configurations, the stiffness of the reinforcing layer material is about 4,000 times that of either the inner or outer layer material. In some embodiments, the selected geometry and thickness of the reinforcing layer, along with the thicknesses of the inner and outer layers, can result in a change in the relative stiffness of the reinforcing 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 thermoplastic resins. For example, the inner and outer layer materials can be PEBAX or TPU. The thickness of the inner layer can be about 0.001 inches to about 0.015 inches. Furthermore, the thickness of the outer layer can be about 0.001 inches to about 0.015 inches. The total wall thickness of the embodiment is about 0.016 inches or less.

[0017] The reinforcing layer conveniently provides kink resistance while enabling the peel-away functionality of the peel-away sheath assembly. The reinforcing layer includes at least two discontinuities on its surface. For example, the discontinuities are slits or openings on the surface of the reinforcing layer. By applying slits or openings of various configurations to the surface of the reinforcing layer, the flexibility and kink resistance of the peel-away sheath assembly can be adjusted. In some embodiments, at least two discontinuities are oriented on the surface of the reinforcing layer perpendicular to the long axis of the peel-away sheath body. This alignment conveniently forms a line along the length of the peel-away sheath body that is structurally weaker than the rest 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 the sharp edges left by the laser cutting. The laser cutting leaves at least two discontinuities along the surface of the hypotube. In other embodiments, the reinforcing layer is a braided filament or a coiled filament. In these embodiments, the braid or coil is essentially configured to have discontinuities along its surface. In further embodiments, the hypotube consists of two C-shaped halves extending along the longitudinal axis along the length of the sheath body.

[0019] The length of the discontinuity in the reinforcing layer is sized along 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 fabrication. For example, the discontinuity must be large enough to accommodate one of the mandrel projections so that a notch can be fabricated. 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 called the critical gap width, within which the sheath retains all of the above desirable properties only within the length of the discontinuity. In some embodiments, the critical gap width may be in the range of about 0.1 to about 1.5 mm.

[0020] In further embodiments, a series of discontinuities are formed along the surface of the reinforcing layer. In some embodiments, the discontinuities are parallel to one another. In some embodiments, the discontinuities are at various angles to the surface of the reinforcing layer so that they are not parallel to one another or equally spaced. In some embodiments, each discontinuity has the same length along the circumference of the sheath. Alternatively, the discontinuities may have a variable length 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 reinforcing 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 in 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 other examples, the distance between two consecutive discontinuities may be greater at the proximal and distal ends of the peel-away sheath body and smaller towards the middle of the length of the peel-away sheath body. In such examples, the distal and proximal ends of the peel-away sheath body have increased kink resistance compared to the middle of the length of the peel-away sheath body, and the middle of the length of the peel-away sheath body has increased flexibility compared to the distal and proximal ends of the peel-away sheath body. In other examples, the surface of the reinforcing layer has oblique 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 gives the sheath different flexibility and kink resistance. In addition, different discontinuity configurations can accommodate different peel-away wires on the peel-away sheath body.

[0021] The discontinuity may include a first set and a second set of discontinuities, 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 a certain angle along the circumference of the reinforced layer. The angle of offset between the first and second discontinuity axes may range from about 0° to about 180°. In some configurations, the discontinuity may be a slit extending along the circumference of the reinforced layer. Depending on the number of discontinuities at a given longitudinal position on the sheath, the reinforced layer may include multiple arcuate segments separated by the discontinuities. In certain embodiments, the arcuate segments are two C-shaped halves.

[0022] In addition to circumferential discontinuities, the reinforcing layer may have a series of openings extending around it. The openings may be circular, elliptical, rhomboid, or any other shape that generally allows reflow of the inner and outer layers through the openings. The openings may form rings around the reinforcing layer at certain points along the long axis. In some embodiments, the rings of openings are regularly spaced around the hypo tube along its length. For example, there may be rings of openings every 1.2 inches along the length of the reinforcing layer. In other embodiments, the rings of openings may extend around the reinforcing layer every 0.6 inches along its length. In certain embodiments, the rings of openings may extend around the reinforcing layer every 0.75 inches along its length. In further embodiments, the rings of openings may extend around the reinforcing layer every 1.05 inches along its length. In other embodiments, the rings 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 certain range of surface area. For example, in some embodiments, each opening may be about 5 to about 25 mm. 2 In other embodiments, the surface area of ​​each opening is approximately 10 to 20 mm. 2 In a particular embodiment, the surface area of ​​each opening is approximately 15 mm². 2One advantage of incorporating a series of openings that extend circumferentially along the length of the reinforcing layer is that it may allow the inner and outer layers to reflow through the openings, thereby providing greater adhesion between the inner and outer layers.

[0023] As described above, the reinforcing layer can be formed from hypotube, braided filament, or coiled filament. In one embodiment where the reinforcing layer is formed from braided filament, the braided filament has 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 filament may also have a round cross-section with a diameter of about 0.0005 inches to about 0.007 inches. The braided filament may contain multiple strands and may have a PPI (picks per inch) of about 7 to about 60. In another embodiment where the reinforcing layer is formed from coiled filament, the coiled filament has 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, coiled filaments can also have a round cross-section with a diameter of approximately 0.0005 inches to approximately 0.007 inches. Coiled filaments can contain multiple strands, and coiled filaments can have approximately 16 to approximately 75 WPI (wraps per inch). At least one advantage of a reinforced layer formed with coiled or braided filaments is the presence of gaps between each wrap or weave of the filament, which reduces the amount of force required to peel away the reinforced layer and sheath as a whole, as well as discontinuities in hypotube reinforced layers. Furthermore, 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 select the size of the gap, i.e., the WPI, i.e., the size of the gap between braided filaments, while simultaneously using the same manufacturing process for the reinforced layer with respect to various applications.

[0024] The rigidity or flexibility of a peel-away sheath assembly can be adjusted based on incorporating reinforcing layers into all or some portions of the peel-away sheath body. In some embodiments, the reinforcing layer includes circumferential discontinuities on its surface, which may be slits or openings. For example, in some embodiments, a portion of the peel-away sheath body may not have a reinforcing 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 rigid distal sheath (e.g., without a distal reinforcing layer) together with a more rigid proximal or intermediate sheath (e.g., with a reinforcing layer). Other embodiments have a less rigid proximal sheath (e.g., without a proximal reinforcing layer) together with a more rigid distal or intermediate sheath (e.g., with a reinforcing layer). For example, the distal end portion of the peel-away sheath body may be designed without a reinforcing layer, while the proximal or intermediate section will have a reinforcing layer. At least one advantage of the absence of a reinforcing layer in the distal section of a peel-away sheath body is that the inner and outer layers can be reflowed more easily without the inclusion of a reinforcing layer, which may allow for easier formation of a tapered tip. In other examples, the proximal end portion has three layers, including a reinforcing layer, while 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 where the distal end portion does not have a reinforcing layer, the inner and outer layers consist of the same inner and outer material. However, the inner and outer layers can also be made of 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 reinforcing layer, but the middle portion, distal end portion, or both do. In further embodiments, the middle portion of the sheath does not have a reinforcing layer, but the proximal end portion, distal end portion, or both do. In further embodiments, the reinforcing layer is present in alternating segments of the sheath.At least one advantage of the partial reinforcement layer is that the sheath can have different rigidities along its length, for example at its proximal and distal ends, to assist in sheath insertion. For example, the lower rigidity of the distal end portion advantageously minimizes trauma to the vasculature. As another example, the higher rigidity of the proximal end portion advantageously maintains the kink resistance of the peel-away sheath body by varying the rigidity. Varying the rigidity of the material of the layer of the peel-away sheath body and, in turn, varying the rigidity of the portion of the peel-away sheath body can vary the rigidity of the peel-away sheath assembly as a whole to promote, for example, kink resistance.

[0025] As detailed above, the length of the peel-away sheath body where the reinforcement layer extends can be adjusted to prevent kinking along a particular portion 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 in the proximal end portion. For example, the proximal end of the reinforcement layer can terminate at the same longitudinal location where the sheath hub terminates. In other embodiments, the proximal end of the reinforcement layer can extend proximally relative to the distal end of the peel-away sheath hub. For example, the reinforcement layer can terminate from about 0 cm to about 2 cm proximal to the distal end of the peel-away sheath hub. The specific distance between the point where the reinforcement layer terminates and the point 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 to have a peel-away line extending along its length, and the peel-away line is aligned with one or more discontinuities in the reinforcing layer of the peel-away sheath body. The alignment can be achieved, for example, in the longitudinal direction along the peel-away sheath body by placing the discontinuities at the same circumferential position as the peel-away line. Aligning the peel-away line of the peel-away sheath body with at least one circumferential discontinuity in the reinforcing layer allows the peel-away sheath body to be peeled away more easily. In some applications, the peel-away sheath body is peeled away along its entire length without breaking the reinforcing layer. For example, in an embodiment having a reinforcing layer only at the distal end portion of the peel-away sheath body, the operator begins removal of the peel-away sheath assembly at the proximal end portion by breaking the inner and outer layers. In an embodiment having a reinforcing 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 reinforcing layer and then breaks only the inner and outer layers while separating the distal end portion of the peel-away sheath body.

[0027] The peel-away sheath hub is configured to provide a handle for the operator to hold the peel-away sheath assembly. In addition, the operator initiates peeling away 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 may have a proximal discontinuity, and the distal cylindrical portion may 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 against 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 can facilitate the removal of the peel-away hub together 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 break the reinforcing layer.

[0028] In further embodiments, the distal end portion of the peel-away sheath assembly is configured to have 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 reinforcing layer is present, the notches are aligned with the discontinuity in the reinforcing layer so that at a given longitudinal point along the length of the peel-away sheath body, the notches are located in the same circumferential position as the discontinuity. At least some advantages of alignment between the notches and the discontinuity in the reinforcing layer are 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 adaptations, peel-away occurs without breaking the reinforcing layer. In some embodiments, the notches are internal diameter notches extending from the innermost surface of the inner layer through the reinforcing layer. In further embodiments, the internal diameter notches terminate before 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 reinforcing layer. In further embodiments, the outer diameter notch terminates before 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, with each pair of peel-away lines extending along the length of the peel-away sheath body, allowing the peel-away sheath assembly to 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 lines with the discontinuities in the reinforcing layer for improved peel-away functionality.

[0029] Another embodiment provides a peel-away sheath assembly for the insertion of a blood pump. The peel-away sheath assembly comprises a peel-away sheath hub and a peel-away sheath body, the peel-away sheath body having 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 in the longitudinal direction. The peel-away sheath body further includes an inner layer located at the inner radius, an outer layer located at the outer radius, and a reinforcing layer located at a radius between the inner and outer radii. In certain embodiments, there is a hydrophilic coating on at least a portion of the outer layer. In some embodiments, the portion of the outer layer where the hydrophilic coating is located 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 where the hydrophilic coating is located extends from the distal end of the sheath body to about 4 cm to about 3 cm distal to the proximal end of the sheath body. In yet another embodiment, the portion of the outer layer where the hydrophilic coating is located extends from the distal end of the sheath body to about 3.5 cm distal to the proximal end of the sheath body. The hydrophilic coating facilitates the insertion of the sheath body into the patient's vascular system. If the entire length of the sheath body is coated with a hydrophilic coating, there is a risk that the sheath body may be pushed away from the aorta due to the arterial pressure acting on the sheath body; therefore, 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 may be internal diameter notches extending from the inner surface of the inner layer through the reinforcing layer and terminating before or within the outer layer. At least one advantage of internal diameter notches is their relative ease of manufacture compared to external diameter notches. In addition, the notches may be external diameter notches extending from the outer surface of the outer layer through the reinforcing layer and terminating before or within the inner layer. At least one advantage of external diameter notches is their relative ease of sheath peel-away compared to internal diameter notches.

[0031] In addition, the peel-away sheath body may have at least one pair of diametrically opposed internal notches extending through the inner layer. In some embodiments, the internal notches terminate before the outer layer. In other embodiments, these notches terminate within the outer layer. The peel-away sheath body further includes at least one pair of diametrically opposed external notches extending through the outer layer. In some embodiments, the external notches terminate before the inner layer. In other embodiments, the notches terminate within the inner layer. As described above, the notches help to align the peel-away line with the discontinuity of the reinforcing layer. The specific notch configuration used, in particular whether internal or external diameter notches are used, and where each notch terminates along the length of the sheath, can be selected based on the geometry of the reinforcing layer to obtain the desired peel-away sheath assembly flexibility and kink resistance.

[0032] In some embodiments, the internal notch extends along the first segment of the peel-away sheath body, and the external notch extends along the second segment of the peel-away sheath body. In some embodiments, the first and second segments partially overlap in the longitudinal direction. The overlapping segments can act as a transition region between the first and second peel-away sheath body segments. In other embodiments, the first and second segments fully overlap in the longitudinal direction. In some embodiments, the first segment corresponds to the proximal end portion of the peel-away sheath body, and the second segment corresponds to the 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 internal diameter notch is that it can enable overmolding onto a hub by allowing the polymer layer of the sheath body to reflow without heat transfer melting the sheath layer and sealing the notch during the injection molding process. At least one advantage of the outer diameter notch is that it can accommodate a variety of reinforcing layers. At least one advantage of using the outer diameter notch is improved manufacturability. This is because the outer diameter notch can be used with a variety of hypotube geometries, a variety of braided filament geometries, and a variety of coiled filament geometries. As detailed below in relation to Figure 14, after the assembly of various layers, the operator can select the position of the outer diameter notch depending on the geometry of the reinforcing layer.

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

[0034] Peel-away sheath hubs are manufactured by injection molding, in which peel-away sheath hub material is placed in a mold along with at least two inserts. In some embodiments, the peel-away sheath hub has a proximal conical section and a distal cylindrical section. Each of the proximal conical and distal cylindrical sections includes 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, when the inserts are removed, a recessed space remains in the shape of the inserts. The space left by the removal of the inserts forms a discontinuity in the longitudinal direction along the length of the peel-away sheath hub. The discontinuities are aligned with each other and with the peel-away lines on the sheath body, which facilitates the peel-away of the peel-away sheath body. With the circumferential discontinuities aligned with the peel-away lines in the peel-away sheath body, the peel-away sheath hub can be fused to the peel-away sheath body.

[0035] A sheath body is provided according to further embodiments of the present disclosure, comprising 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 may have a first stiffness, and the second material may have a second stiffness different from (e.g., lower than) the first stiffness. The first and second strips are adjacent and oriented, for example, spirally, extending from the distal end to the proximal end of the sheath body. The spiral or spiral structure, as well as the alternating first and second strips of different stiffnesses, improves flexibility by reducing the force required to bend the introducer sheath. Furthermore, kink resistance is improved by increasing the introducer sheath's ability to deform in the flexible section during compression along the inner diameter of the bending radius and tensile along the outer diameter of the bending radius, and by increasing the diameter crush strength with the stiffer section. The improved flexibility and increased kink resistance are beneficial in procedures requiring a high insertion angle, 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 a sheath is obtained having 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 adapted to increase flexibility (e.g., bending) while minimizing kinking.

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

[0038] In certain embodiments, the first and second strips have the same width. In some embodiments, the widths of the first and second strips are 1 mm. According to other embodiments, the first and second strips 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 widths of the first and second strips is that the composite properties of the sheath can be altered to obtain the desired stiffness and bending stiffness 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 and second notches can be aligned axially along the length of the sheath body and can be oriented opposite to each other. In certain embodiments, the first and second notches are on the inner surface of the sheath body. According to other embodiments, the first and second notches are on the outer surface of the sheath body. According to certain embodiments, the sheath body is divided into two along the first and second notches during peel-away of the sheath body. At least one advantage of the notches is that they can improve the ease of peel-away of the sheath body when the dividing 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 a particular embodiment, 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] An introducer sheath for inserting a blood pump is provided according to further embodiments of the present disclosure. The introducer sheath comprises a sheath body and a sheath hub. For example, an embodiment of the sheath body of the present disclosure. The sheath body may include a first strip of a first material having a first rigidity, a second strip of a second material having a second rigidity, and a first lumen defined by the first and second strips. The first rigidity may be greater than the second rigidity. The first and second strips may be adjacent and spirally oriented from the distal end to the proximal end of the sheath body. The sheath hub may include a proximal end and a distal end defining the second lumen. The distal end of the sheath hub may be attached to the proximal end of the sheath body. The alternating helical structure of first and second strips with different stiffnesses improves flexibility by reducing the force required to bend the introducer sheath, and also improves strength by increasing the column strength of the introducer sheath (the axial force required to cause buckling). The improved flexibility and increased column strength are beneficial in procedures using high insertion angles, such as subclavian insertion sites.

[0042] In some embodiments, the first lumen and the second lumen are in fluid communication. Various instruments can be sequentially inserted and retrieved through both the first and second lumen of the sheath, and after the instruments have been positioned in the desired location, the sheath can be peeled away.

[0043] The sheath hub may include a hemostatic valve sized to prevent fluid from leaking out of the proximal end of the hub.

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

[0045] A method for manufacturing a flexible introducer sheath body is provided according to further embodiments of the present disclosure. The method includes winding a first strip of a first material and a second strip of a second material onto a mandrel while keeping them adjacent to each other, and fixing both strips together (e.g., by heating) so that they are adjacent and have peel-away functionality. The method may include fixing the first distal end of the first strip and the second distal end of the second strip. The method may include fixing the first proximal end of the first strip and the second proximal end of the second strip. The method may also include placing heat shrink tubing on the first strip, the second strip and the mandrel. Furthermore, 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] A sheath body is provided according to further embodiments of the present disclosure, comprising 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 may have a first rigidity, and the second material may have a second rigidity different from that of the first material. The first and second strips are oriented adjacent to the lumen, extending, for example, in a spiral from the distal to the proximal end of the sheath body. The lumen may be made of a third material having the same or different rigidity as the first and / or second material.

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

[0048] At least one advantage of the manufacturing method is its ability to form sheaths with composite material properties tuned to provide improved bendability and higher kink resistance. In addition, the manufacturing method enables the production of sheath bodies with smooth inner and outer surfaces. [Brief explanation of the drawing]

[0049] The aforementioned and other objectives and advantages will become clear when the following detailed explanation is considered in conjunction with the attached drawings. Throughout the drawings, similar part numbers refer to similar parts. [Figure 1] A peel-away sheath assembly is shown, including the peel-away sheath body and peel-away sheath hub. [Figure 2] Figure 2A shows a cross-section of a peel-away sheath body with a continuous second layer perimeter, viewed from a point along the long axis. Figure 2B shows a cross-section of the peel-away sheath body, viewed from a point along the long axis that crosses a circumferential discontinuity in the second layer. [Figure 3A] This shows an axial cross-section of the peel-away sheath body. [Figure 3B] This shows possible designs for laser-cut hypotube. [Figure 3C] This shows possible designs for laser-cut hypotube.

[0050] [Figure 4-1] Possible configurations for internal and external diameter notches are shown along the axial cross-section. [Figure 4-2] Possible configurations for internal and external diameter notches are shown along the axial cross-section. [Figure 5] Possible configurations for internal and external diameter notches are shown along the circumferential cross-section. [Figure 6] The cross-section shows the inner layer, reinforcement layer, and third layer. [Figure 7] The isometric view shows the proximal portions of the peelaway sheath hub and peelaway sheath body. [Figure 8] This shows a circumferential cross-section of the peel-away introducer sheath within the cylindrical portion of the peel-away sheath hub. [Figure 9] This shows a circumferential cross-section of the introducer peelaway sheath within the conical portion of the peelaway sheath hub. [Figure 10] The image shows a top view of the proximal end portion of the peelaway sheath hub and peelaway sheath body. [Figure 11] This shows a cross-section of a laser-cut hypotube with an internal notch at the circumferential discontinuity. [Figure 12] This shows a cross-section of a peel-away introducer sheath where the mold is located on the fractured wall surface. [Figure 13] This shows a cross-section of a peel-away introducer sheath where the mold is not present on the fractured wall surface. [Figure 14] This describes an exemplary method for manufacturing a specific embodiment of a peel-away sheath assembly. [Figure 15] This shows an exemplary longitudinal section of a peel-away introducer sheath, where the reinforcing layer extends into the peel-away sheath hub. [Figure 16] An isometric view of an exemplary introducer sheath assembly is shown, including an exemplary expandable sheath body with two material strips bonded to an exemplary sheath hub. [Figure 17] An isometric view of an exemplary flexible sheath body having a first strip and a second strip is shown. [Figure 18] Figure 17 shows an example of a flexible sheath body. [Figure 19]Figure 17 shows a schematic profile of the flexible sheath body, with the first and second strips having width and twist angle. [Figure 20] Figure 17 shows a cross-sectional view of the flexible sheath body having a first notch and a second notch on its inner surface. [Figure 21] Figure 20 shows an isometric view of the flexible sheath body. [Figure 22] Figure 17 shows a cross-sectional view of the flexible sheath body having a first notch and a second notch on its outer surface. [Figure 23] Figure 22 shows an isometric view of the flexible sheath. [Figure 24] Figure 17 shows an exemplary method for manufacturing the flexible sheath body. [Figure 25] A cross-sectional view of a flexible sheath body having a lumen and a first and second notch on its outer surface is shown. [Modes for carrying out the invention]

[0051] Detailed explanation To provide an overall understanding of the systems, methods, and apparatus disclosed herein, certain exemplary embodiments are described. While the embodiments and features described herein are described specifically in relation to percutaneous cardiac pump systems and their associated uses, it will be understood that these teachings may be adapted to and applied to other mechanical circulatory support devices and other types of medical devices, such as electrophysiological study and catheter ablation devices, angiography and stent placement devices, angiography catheters, peripheral puncture central venous catheters, midline catheters, peripheral catheters, inferior vena cava filters, abdominal aortic aneurysm treatment devices, thrombectomy devices, TAVR delivery systems, cardiac treatment and cardiac support devices, such as balloon pumps, cardiac support devices implanted using surgical incisions, and other venous or arterial-based intraluminal introduction catheters and devices.

[0052] The systems, methods, and apparatus described herein provide flexible introducer sheaths having peel-away sheath functionality with improved kink resistance and improved flexibility. Such improved functionality of introducer sheaths can be achieved in various ways, as disclosed herein. Generally, the sheath has at least two compartments of different stiffness, one stiff compartment, and at least one low-stiffness compartment. The improved sheath allows for improved kink resistance. One exemplary configuration having at least one stiff compartment and at least one low-stiffness compartment is a sheath having an inner layer, a second reinforcing layer, and an outer layer. In such embodiments, the reinforcing layer may include laser-cut hypotube or braided or coiled filaments. Another configuration having at least one stiff compartment and at least one low-stiffness compartment, as disclosed in application No. 62 / 672,212, reproduced below in Appendix A, includes a single layer of stiff strands and a low-stiffness strand wound in a helical configuration. By fabricating the low-rigidity compartment of the introducer sheath with a different polymer material, the introducer sheath also allows the sheath to be peeled away more easily. Using high-rigidity and low-rigidity materials in either the same or different layers is an improvement over typical peel-away sheaths that use only one material with constant rigidity, forcing a choice between kink resistance and flexibility. In clinical scenarios requiring peel-away sheaths at large insertion angles, improving both kink resistance and 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 subclavian axillary access due to sensitive anatomical landmarks and nerve bundles in the area adjacent to the axillary insertion site. In addition, the presence of discontinuities in the reinforcing layer and / or notches in the sheath layer reduces the force applied to peel away the sheath.

[0053] Figure 1 shows an exemplary peel-away sheath assembly 100, which includes 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 reinforcing 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 the long axis of the sheath body 103. As will be further described below in relation to Figures 2-6, the peel-away sheath assembly 100 has a multilayer design to provide both flexibility and kink resistance. The sheath body 103 includes an inner layer 110 located at the first innermost radius, a reinforcing layer 112 located at the second radius, and an outer layer 114 located at the third outermost radius. The inner layer 110 and the outer layer 114 contain the same thermoplastic resin with respect to the inner layer 110 and the outer layer 114, respectively. Alternatively, the inner layer 110 and the outer layer 114 may contain different thermoplastic resins. The reinforcing layer 112 has different material properties from the inner layer 110 and the outer layer 114. For example, the reinforcing layer is more rigid than at least one of the inner layer 110 and the outer layer 114. The exemplary embodiment shown in Figure 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 where the hydrophilic coating is located 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 other embodiments, the portion of the outer layer where the hydrophilic coating is located extends from the distal end of the sheath body to approximately 4 cm to 3 cm distal to the proximal end of the sheath body. In yet another embodiment, the portion of the outer layer where the hydrophilic coating is located extends from the distal end of the sheath body to approximately 3.5 cm distal to the proximal end of the sheath body. As described above, the hydrophilic coating facilitates the insertion of the sheath body into the patient's vascular system. If the entire length of the sheath body is coated with a hydrophilic coating, there is a risk that the sheath body may be pushed away from the aorta due to the arterial pressure acting on the sheath body; therefore, a portion of the sheath body is generally configured without a hydrophilic coating.

[0054] The reinforcing layer can be a hypotube, braided filament, or coiled filament. The reinforcing layer is configured to have at least two discontinuities on its surface. For example, a hypotube in the reinforcing layer can be configured to have a series of slits on its surface. Such slits allow the hypotube to have improved flexibility as well as providing improved kink resistance, given its inherent stiffness. 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 reinforcing layer is the presence of discontinuities between each wrap or braid of the filament, which reduces the amount of force required to peel away the reinforcing layer and sheath as a whole. Furthermore, additional discontinuities between each wrap of the filament allow for greater flexibility. At least one advantage of filaments is the ability to adjust the size of the discontinuities, i.e., select WPI (wraps per inch), while using the same manufacturing process for the reinforcing layer, for various applications. One further advantage of filaments is their ability to maintain a given size of the discontinuity while adjusting the separation distance between discontinuities by changing the size of the filament. Both filament and hypotube configurations can be realized through a variety of peel-away wire designs. One advantage of reinforcement layers constructed from hypotube or coiled filaments is that the thickness of the layer can be configured to be constant throughout the entire length of the layer.

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

[0056] As will be described below in relation to Figures 2 and 3, the reinforcing layer can be a laser-cut hypo tube. The hypo tube can be machined to have at least two discontinuities on its surface. In some embodiments, the discontinuities extend along a portion of the circumference of the hypo tube and are circumferential discontinuities. In other embodiments, the discontinuities extend along the length of the hypo tube and are longitudinal discontinuities. In other embodiments, the discontinuities may extend in both the circumferential and longitudinal directions. In certain embodiments, a typical 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 of various sizes and shapes. For example, the discontinuities can be rectangular, circular, elliptical, and rhombic.

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

[0058] Section 200 shows the inner layer 202 located at the inner radius, the reinforcing layer 204 located at the intermediate radius, and the outer layer 206 located at the outermost radius. The center of Figure 2A shows the first lumen 208. Figure 2A is viewed from a point along the sheath body, along the long axis, where the reinforcing layer 204 has a continuous circumference. The inner layer 202, the reinforcing layer 204, and the outer layer 206 are concentric. As defined herein, “concentric” means that each layer shares the same center, the outer layer 206 completely encloses the reinforcing layer 204 and the inner layer 202, and the reinforcing layer 204 completely encloses the inner layer 202.

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

[0060] In Figures 2A and 2B, the material properties of the reinforcing layer 204 conveniently provide improved flexibility and kink resistance to the sheath assembly. For example, one such property is the stiffness of the reinforcing 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 property of the reinforcing layer material 204 is its modulus of elasticity, which can also be higher than at least one of the moduli of elasticity of the materials of the inner layer 202 or the outer layer 206. The first inner layer 202 material and outer layer 206 material can be thermoplastic resins, which can be at least one of PEBAX or TPU. The reinforcing layer 204 material can be at least one of LCP, PEBAX, stainless steel, Nitinol, or Kevlar. The thickness of the inner layer 202 can be 0.001 inches to 0.015 inches. Furthermore, the thickness of the outer layer 206 can be 0.001 inches to 0.015 inches. The total wall thickness of the embodiment is 0.016 inches or less.

[0061] Figure 3A shows an exemplary longitudinal section 300 of a peel-away sheath assembly, where the major axis of the sheath body is in the plane of the page. The section shows an inner layer 302 at the inner radius, a reinforcing layer 304 at the middle radius, and an outer layer 306 at the outer radius. The reinforcing layer 304 has a discontinuity 308. In some embodiments, the discontinuity 308 is a circumferential discontinuity. Together, the three layers define a first lumen 310. Within the reinforcing layer 304, the circumferential discontinuity 308, which separates the rib 309, is connected by the reinforcing layer 304. The circumferential discontinuity 308 has a finite arc length and does not extend to the full length of the circumference of the reinforcing layer 304. The circumferential discontinuity 308 may have different arc lengths and may have different widths. The arc length of the circumferential discontinuity 308 may be approximately 0.5 cm to 1 cm. Similarly, the width of the circumferential discontinuity portion 308 may be approximately 0.1 to 0.5 cm, approximately 0.2 to 0.4 cm, and approximately 0.3 cm.

[0062] Figure 3B shows one configuration of discontinuities 322 and 324 in the reinforcing layer 320, where each discontinuity 322 and 324 in the hypotube has the same length along the circumference of the hypotube. The discontinuities in Figure 3B are equally spaced along the long axis, and the discontinuities consist of a first set and a second set of discontinuities. The discontinuities located at the same circumferential position as the first slit 322 constitute the first set, and the discontinuities located at the same circumferential position as the second slit 324 define the second set. Each discontinuity in each set of discontinuities has a center. The center of the first set of discontinuities defines the first discontinuity axis, and the center of the second set of discontinuities defines the second discontinuity axis. In some embodiments, as shown in Figure 3B, the first and second slit axes are offset by some angle. The angle at which the two slit axes are offset can be 0°, such that all slits along the length of the hypotube have their centers on the same axis. The angle at which the slit axes are offset ranges from 0 to about 18°. In one example, the angle at which the slit axes are offset is 0°, corresponding to a state where each slit has its center on the same axis. In another example, the angle at which the slit axes are offset is 180°, corresponding to a state where the two slit axes face each other diametrically. As defined herein, “facing diametrically” means that the 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 discontinuity has a different length 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 greater kink resistance at the distal end while providing easier peel-away capability at the proximal end.In another example, the slits may be closest at both ends of the sheath body and more spaced in the middle of the sheath body's length, providing kink resistance in the middle of the sheath body while allowing the ends of the sheath to be easily peeled away. As described above in relation to the filament reinforcement layer, the discontinuities may be of different sizes and shapes. Configurations with a hypotube reinforcement layer may also have discontinuities of different sizes and shapes.

[0063] In some embodiments, the hypotube may be configured to have a spine connecting a series of ribs. “Spine” as defined herein means a portion of the hypotube extending continuously in the longitudinal direction parallel to the first lumen of the sheath body. “Rib” as defined herein means a portion of the hypotube connected at only one end to a spine and extending circumferentially from the spine. In some embodiments, there is only one rib, and the hypotube resembles a single C-shape extending in the longitudinal direction along the length of the sheath body. In other embodiments, there may be several ribs. The ribs may be separated in the longitudinal direction by circumferential discontinuities. In other embodiments, there may 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 desired kink resistance and flexibility. Ribs closer together provide greater kink resistance. Ribs further apart provide greater flexibility and ease of peeling away.

[0064] Figure 3C shows another configuration of discontinuities 332 and openings 334 in the reinforcing layer 330. In Figure 3C, the circumferential discontinuity 332 is oriented to extend along the periphery of the reinforcing layer. The inclusion of openings 334 helps in the adhesion of the inner and outer layers to the reinforcing layer 330 during manufacturing. The openings 334 can be configured in a variety of shapes. The openings 334 may be, for example, circular, elliptical, or rhomboid. As detailed earlier, 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, the openings 334 may be included every 0.7 inches along the length of the reinforcing layer 330. In other embodiments, the openings 334 may be placed every 0.9 inches along the length of the reinforcing layer. In certain embodiments, the openings 334 may be placed every 1.1 inches along the length of the reinforcing layer. As detailed earlier, the openings 334 may have a certain range of surface area. For example, in some embodiments, each opening 334 is approximately 5 to approximately 25 mm. 2 In another embodiment, the surface area of ​​each opening 334 is approximately 10 to 20 mm. 2 In a particular embodiment, the surface area of ​​each opening 334 is approximately 15 mm². 2 The incorporation of the openings allows the inner and outer layers of the sheath body to bond better to each other during manufacturing. This increased bonding allows the sheath body to better withstand stress when bent. The reflow process is also controlled to obtain polymer reflow into circumferential slits configured along the length of the hypo tube. The slits, which do not contain polymer, allow the slits to function as compression and expansion zones, which increases the flexibility of the sheath body.

[0065] Figures 4A–4E show several possible configurations of internal and external diameter notches. In such configurations, the notches define a peel-away line along which the operator can peel and separate the sheath assembly. Figures 4A–4E show the inner layer 402, the reinforcing layer 404 and the outer layer 406, as well as the sheath lumen 408. An exemplary notch 410 is also shown. Figure 4A shows an embodiment having only an internal diameter notch. The internal diameter notch in Figure 4A starts from the innermost surface of the inner layer 402, penetrates the reinforcing layer 404, and terminates within the outer layer 406. In another embodiment, the external diameter notch 410 starts from the innermost surface of the inner layer 402, penetrates the reinforcing layer 404, and terminates before the outer layer 406. Embodiments including an internal diameter notch (Figure 4A) are relatively easy to manufacture.

[0066] Figure 4B shows an embodiment having only an outer diameter notch. In Figure 4B, the outer diameter notch starts from the outermost surface of the outer layer 406, penetrates the reinforcing layer 404, and terminates within the inner layer 402. In another embodiment, the outer diameter notch in Figure 4B starts from the outermost surface of the outer layer 406, penetrates the reinforcing layer 404, and terminates before reaching the inner layer 402. The embodiment including the outer diameter notch (Figure 4B) exhibits higher performance in terms of peel-away functionality than the configuration having only an inner diameter notch.

[0067] Figure 4C shows an embodiment having both an internal and external diameter notch, where the two types of notches do not overlap axially along the length of the sheath body. Figure 4D shows an embodiment where the notches partially overlap axially along the length of the sheath body. Figure 4E shows an embodiment where the notches completely overlap axially along the length of the sheath body. In one embodiment, the external diameter notch extends along at least the distal end of the distal portion of the sheath body, and the internal diameter notch extends along all of the proximal end of the sheath and at most along the proximal end of the distal portion of the sheath body. In another embodiment, in addition to both the internal and external diameter notches overlapping and extending along any portion of the first section of the sheath body, the external diameter notch extends along at least the distal end of the distal portion of the sheath body, and the internal diameter notch extends along all of the proximal portion of the sheath and at most along the proximal end of the proximal portion of the sheath body.

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

[0069] Figure 5B shows a circumferential section 520 of a sheath body having an inner layer 522, a reinforcing layer 524, and an outer layer 526. The three layers define a first lumen 528 extending along the long axis of the sheath body. A diametrically opposed outer diameter notch 530 extends from the innermost surface of the outer layer 522, penetrates the reinforcing layer 524, and terminates within the inner layer 526. As described in relation to Figures 4A-E, a configuration with an outer diameter notch, as in Figure 5A, has improved peel-away performance, while a configuration with an inner diameter notch, as in Figure 5B, is easier to manufacture. Some embodiments have only an inner diameter notch, and other embodiments have only an outer diameter notch. Further embodiments may have both an inner diameter notch and an outer diameter notch, where the inner diameter notch extends exclusively from the outer diameter notch along the length of the sheath body. Further embodiments may have a portion of the sheath body having both internal and external diameter notches. Some other embodiments may have both areas where only one notch is visible and areas where two types of notches overlap in the longitudinal direction.

[0070] Similarly, Figure 6 shows a cross-section 600 of the sheath layers, including the inner layer 602, the reinforcing layer 604, and the 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] Figure 7 shows an isometric view 700 of the sheath hub 701 and the proximal portion 706 of the 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 peelaway line of the sheath body 707 so that at a given major axis point along the length of the sheath body having the discontinuity, the peelaway line is located at the same circumferential position as the discontinuity. In some embodiments, the discontinuities 703 and 705 are circumferential discontinuities.

[0072] Figure 8 shows a circumferential cross-section 800 of the distal cylindrical portion 810 of the sheath hub viewed from the line A-A' (see Figure 7). The inner layer 802, together with the reinforcing layer 804 and the outer layer 806, defines the first lumen 808. The discontinuity 812 in the cylindrical portion 810 of the sheath hub is aligned with the peel-away line of the sheath body to facilitate sheath removal and is a circumferential discontinuity in some embodiments. The discontinuity 812 is also aligned with the discontinuity in the proximal conical portion of the sheath hub to facilitate sheath removal. The discontinuity in the proximal conical portion of the sheath hub is a circumferential discontinuity in some embodiments. As detailed in relation to Figure 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. When the insert is removed after fusion, a circumferential discontinuity 812 remains in the cylindrical portion 810 of the sheath hub.

[0073] Figure 9 shows a circumferential cross-section 900 of the proximal conical portion 910 of the sheath hub viewed from the line B-B' (see Figure 7). The inner layer 902 defines the first lumen 908. The discontinuity 912 in the conical portion 910 of the sheath hub can be aligned with the discontinuity in the distal cylindrical portion of the sheath hub to facilitate sheath removal, and the distal cylindrical portion of the sheath hub can also be aligned with the peel-away line of the sheath body. In some embodiments, the discontinuity 912 is a circumferential discontinuity. As detailed in relation to Figure 12 and previously detailed in relation 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 manufactured by placing an insert in the sheath hub material and then fusing the sheath hub material to the sheath body. After fusion, when the insert is removed, a circumferential discontinuity 912 remains in the conical portion 910 of the sheath hub. In addition, as shown in the exemplary embodiment of Figure 9 (and as will be further detailed below in relation to Figure 12), only the inner sheath layer exists in the proximal conical portion of the sheath hub. As will be further detailed below in relation to Figure 12, the inner layer 902 has a specific 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 layer distal to the proximal conical portion 910. The thickness of the inner layer 902 in the proximal conical portion 910 can be selected so that a reduced diameter section is created in the proximal conical portion 910. The reduced diameter section may have an outer diameter smaller than the total thickness of the relatively distal layer, or it may have an outer diameter equal to the total thickness of the relatively distal layer. The presence of only one sheath layer within the proximal conical portion 910 of the sheath hub reduces the amount of material that the operator must break to detach the sheath, thereby allowing for a smaller breaking force to be applied by the operator.

[0074] Figure 10 shows a top view 1000 of the sheath hub 1001 and the proximal portion 1006 of the sheath body. The sheath hub 1001 includes a proximal conical portion 1002 and a distal cylindrical portion 1004. A discontinuity 1003 is present in the conical portion 1002 of the sheath hub, and a discontinuity 1005 is present in the cylindrical portion of the sheath hub. In some embodiments, the discontinuities 1003 and 1005 are circumferential discontinuities. The circumferential discontinuities 1003 and 1005 are aligned with the peelaway line of the sheath body. The proximal end 1006 of the sheath body is joined to the sheath hub 1001 at the distal conical portion 1004. Figure 7 also shows the lines A-A' and B-B', and exemplary cross-sections of the hub in the cylindrical and conical portions as seen from these lines are shown in Figures 8 and 9, respectively.

[0075] The manufacture of peel-away sheaths includes the manufacture of multilayer sheath bodies, the manufacture of sheath hubs, and the assembly of the sheath hubs and sheath bodies. Specific notches and layer configurations can be configured for ease of manufacture. For example, the absence of reinforcing layers in the proximal portion of the sheath helps stabilize the injection molding process. In addition, the use of internal diameter notches ensures that the notches are not sealed when the polymer layers reflow during the manufacturing process. As will be described in more detail below in relation to Figure 14, multilayer sheath bodies are manufactured through a thermal shrinkage process. Thermal shrinkage is also called lamination.

[0076] In one manufacturing method, the innermost first layer material, the reinforcing second layer material, and the outermost third layer material are placed on a mandrel. These layers are then heat-shrinkable. For example, PTFE heat-shrink material is used.

[0077] In another method, the innermost first layer is placed on a mandrel and heat-shrunk, at which point the reinforcing second layer material and the outermost third layer material are placed on top of the heat-shrunk first layer. Then, the heat-shrunk first layer, the reinforcing second layer material, and the outermost third layer material are wrapped and heat-shrunk together.

[0078] In yet another method, each layer is sequentially heat-shrunk onto a mandrel. First, the innermost first layer is placed on the mandrel and heat-shrunk. Next, the heat-shrunk first layer is coated with the reinforcing second layer material. Then, the two layers are heat-shrunk. Next, the two heat-shrunk layers are coated with the outermost third layer material. Finally, the three layers are wrapped and heat-shrunk.

[0079] When manufacturing a sheath body with an internal diameter notch, the mandrel used for heat shrinkage includes a higher spine, and the heat shrinkage of the layer using the mandrel forms a sheath body with an internal diameter notch in the shape of the mandrel spine. When manufacturing a sheath body with an external diameter notch, the outermost third layer is constructed using a mold during heat shrinkage, and the mold has the shape of the external diameter notch. After heat shrinkage, when the mold is removed, an external diameter notch in the shape of the mold remains. As will be further detailed below in relation to Figure 11, the circumferential discontinuity must be large enough to allow at least the mandrel to extend through the discontinuity during manufacturing and to provide improved flexibility. The size of the discontinuity must not be smaller than the size of the protrusion of the mandrel used for manufacturing. 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, and then the arc segments may be heat-shrunk onto the heat-shrunk innermost first layer. This can be done to ensure that the increasing number of hypotube arc segments are properly bonded to the innermost first layer before the incorporation and heat-shrinking of the outermost third layer. In addition, when the reinforcing layer is a hypotube containing multiple arc segments, the innermost first layer may be heat-shrunk, and then the arc segments may be individually heat-shrunk onto the heat-shrunk first layer. Similarly, the aforementioned braided and coiled filament structures can also be heat-shrunk onto the heat-shrunk innermost first layer, and then the outermost third layer may be heat-shrunk to ensure proper adhesion of the filament layer to the innermost first layer.

[0081] When the sheath is removed from the patient, the sheath hub is peeled away in addition to the sheath body. As described above, and also in relation to Figures 12 and 13, the sheath hub is manufactured using injection molding, in which 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, at least one insert is removed. As such, the sheath hub is configured during manufacturing to include a fracture wall in the form of a recessed space of at least one shape. This recessed space helps the practitioner to peel away the sheath hub. Figure 12 shows a cross section 1200 of an introducer sheath with the mold at the fracture wall surface. The fracture wall is configured to have the shape of the two inserts after they have been removed from the sheath hub material. In other configurations, one insert may be used, and in further embodiments, three or more inserts may be used. In addition, Figure 12 shows a diameter reduction section 1210. Since the inner layer may be configured to extend further in the proximal direction than the reinforcing layer or outer layer, the reduced diameter section 1210 corresponds to a proximal segment along the sheath body that may contain only the inner layer. The reduced diameter section 1210 has a thickness of 1211. Layer 1212 has a thickness of 1213, and layer 1214 has a thickness of 1215. In some embodiments, the thickness 1211 is less than the sum of the thicknesses 1213 and 1215. In other embodiments, the thickness 1211 is equal to the thickness 1213, so that the reduced diameter section 1210 and layer 1212 form a single continuous layer. In other embodiments, the thickness 1211 is less than the thickness 1213. As mentioned above, one advantage of the absence of a reinforcing 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. Figure 13 shows a cross-section 100 of the introducer sheath where the mold is not on the fracture wall surface, illustrating how the insert is positioned relative to the sheath hub.

[0082] Figure 11 shows a cross-section 1100 of a laser-cut hypo tube 1104 having an internal notch 1108 in the circumferential gap 1110. The inner layer 1102, reinforcing layer 1104, and outer layer 1106 are configured to have an internal notch in the circumferential gap to enhance peel-away functionality. As previously stated, the discontinuity must be large enough to allow at least one internal or external diameter notch to extend through it and to provide improved flexibility, but at the same time, it must be small enough to provide improved kink resistance. In some embodiments, the width of the circumferential gap 1110 is in the range of about 0.1 to about 1.5 mm. In other embodiments, the width of the circumferential gap 1110 is in the range of about 0.3 to about 1.2 mm. In certain embodiments, the width of the critical gap 1110 is in the range of about 0.5 to about 1.0 mm. In further embodiments, the width of the critical gap 1110 is in the range of 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] Figure 14 shows a flowchart for the manufacture of a peel-away sheath assembly for cardiac pump introduction in a particular embodiment. Process 1400 begins with step 1402, in which an operator coats a mandrel with a first layer of the first material. In some embodiments, the first layer material is a thermoplastic resin, including one of PEBAX or TPU. In step 1404, the operator heat-shrinks the first layer. This involves coating the first layer material with a heat-shrink material and heating the layer and the heat-shrink material. After heat-shrinking the first layer, in step 1406, the operator coats the heat-shrinked first layer with a second layer of reinforcing second layer material. Then, in step 1408, the operator coats the second layer of reinforcing second layer material with the outermost layer of the third layer material. In step 1410, the operator heat-shrinks the heat-shrinked first layer, reinforcing second layer, and third layer material together. As previously detailed in relation to Figure 3C, openings in the reinforcing layer, forming a ring around the reinforcing layer at regular longitudinal spacing along the length of the sheath body, allow the inner and outer layers to reflow. This reflow provides better adhesion between the inner and outer layers, which allows the sheath body to better accept stress when it is bent. The manufacturing process is controlled so that the reflow of the inner and outer layers into the circumferential slits does not occur. 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 may have at least one higher spine so that the thermal shrinkage of the first layer material leaves at least one internal notch in the thermally shrunk first layer. In another embodiment, the operator selects the position of each external notch based on the geometry of the thermally shrunk reinforcing layer. In another embodiment of the method, the operator does not need to subject the first layer to thermal shrinkage before thermal shrinking the second and outermost third reinforcing layers. In other words, the operator can heat-shrink the first, second, and third layers simultaneously for the first time.

[0084] Figure 15 shows a longitudinal section 1500 of a sheath body 1502 having an inner layer 1504, an outer layer 1506, a reinforcing layer 1508, a sheath hub 1510, a reinforcing 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 where the reinforcing layer 1508 extends can be adjusted to prevent kinking along a particular portion of the sheath body 1502. For example, in some embodiments, the reinforcing layer 1508 is not present in the distal portion 1514 but is present in the intermediate portion 1516. In such embodiments, the reinforcing layer 1508 may extend to various depths into the proximal portion 1518, as indicated by the reinforcing hub length 1512. For example, the proximal end of the reinforcing layer 1508 may terminate at the same longitudinal point where the sheath hub 1510 terminates. In other embodiments, as illustrated in Figure 15, the reinforcing 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 reinforcing layer 1508 may terminate at a longitudinal point proximal to the longitudinal point where the sheath hub 1510 terminates. The longitudinal point where the reinforcing layer 1508 terminates may be given by the reinforcing hub length 1512. For example, the reinforcing hub length 1512 can extend into the sheath hub 1510 to a desired depth to produce desired kink resistance along a particular length of the sheath. The reinforcing hub length 1512 may be 2 cm in length, for example, so that the reinforcing layer 1508 terminates 2 cm distal to the longitudinal point where the sheath hub 1510 terminates. In other embodiments, the reinforcing hub length 1512 may be 1 cm such that the reinforcing layer 1508 terminates 1 cm distal to the longitudinal point where the sheath hub 1510 terminates. In further embodiments, the reinforcing hub length 1512 may be zero such that the reinforcing layer 1508 terminates at the longitudinal point where the sheath hub 1510 terminates. The specific distance between the point where the reinforcing layer terminates and the point where the sheath hub terminates can be selected to produce a specific kink resistance between those two points along the length of the sheath body. The surface of the reinforcing layer is configured to have discontinuities to facilitate the peel-away of the reinforcing layer.In embodiments where the peel-away process begins within the sheath hub and includes a reinforcing layer extending into the sheath hub, the peel-away of the reinforcing layer becomes easier because the practitioner can directly apply a peel-away sheath force to a portion of the sheath body containing the reinforcing layer.

[0085] Figure 16 shows an exemplary introducer sheath assembly 1600, including a sheath body 1700 (further described in relation to Figure 17) coupled to a sheath hub 1602. As will be described in further detail below in relation to Figures 17-19, the sheath body 1700 has a helical design including two strips 1706 and 1708 of materials having different stiffnesses. At least one advantage of this two-material helical design is the ability to obtain a sheath with composite material properties for improved flexibility while improving kink resistance. In one aspect, the sheath body 1700 may have a ring design including alternating rings of materials having different stiffnesses. In another aspect, the sheath body 1700 may have a longitudinal strip design including alternating strips of materials having different stiffnesses. Both the sheath body 1700 and the sheath hub 1602 have a proximal end and a distal end. 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 is bonded or joined to the proximal end of the sheath body. Alternatively, the distal end of the sheath hub is formed integrally 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 may be formed of two diametrically opposed tabs or any other geometry suitable for gripping. The gripping surface 1604 facilitates the peel-away of the sheath hub 1602 and the sheath body 1700. During the peel-away of the sheath, a force is applied to the gripping surface 1604 (for example, tabs as shown in Figure 16), and the sheath hub 1602 is divided in two along its long axis, starting from the notch 1606. The notch 1606 can be aligned axially along the length of the sheath hub and oriented opposite to each other. The notch 1606 on the sheath hub 1602 may 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 force to the gripping surface 1604 of the sheath hub 1602, which causes the sheath hub to break along the notch 1606.As will be further described below in relation to Figures 20-23, the sheath body may have the notch on the inner surface of the sheath body 1700 (Figures 20 and 21) or on the outer surface of the sheath body 1700 (Figures 22 and 23). The notch along the sheath body 1700 may be replaced with a cut. To facilitate the peel-away of the sheath hub 1602 and the sheath body 1700, the notch on the sheath body 1700 may be aligned with the notch 1606. At least one advantage of the notch or cut on the sheath body 1700 is that it may improve the ease with which the seal can be peeled away by cutting both helical strips of the sheath. The sheath body 1700 can be separated into two pieces by first fracturing the sheath hub 1602, and then applying further force to the gripping surface 1604 of the sheath hub 1602, which causes the sheath body 1700 to fracture 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 the 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. The hemostatic valve can be sized to prevent fluid from leaking out of the proximal end of the hub during insertion of the medical device.

[0087] Figures 17 and 18 show an exemplary sheath body 1700 (e.g., the sheath body 1700 in Figure 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 helices, extending from the distal end 1702 to the proximal end 1704 of the sheath body 1700 to form a cylindrical lumen. As will be described in more detail below in relation to Figure 19, the inner diameter of the lumen, the widths of the first strip 1706 and the second strip 1708, and the helix angle are related and corresponding values ​​are selected to obtain the desired sheath characteristics. The lumen can be sized to allow insertion of a medical device. For example, the lumen can be sized to allow insertion of a transcutaneous 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 vena cava 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 having different flexibility and rigidity. For example, the first strip 1706 is made of a first material having a first rigidity, and the second material is made of a second material having a second rigidity. The rigidity of the first material can be higher than that of the second material. 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 may be made of PEBAX 7233, and the second strip 1708 may be made of EVA. At least one advantage of having a first strip and a second strip with different material properties placed side by side is the ability to select a specific stiffness for the introducer sheath as a whole.

[0089] The distal end 1702 of the sheath body 1700 may include a tapered tip. The tapered tip maintains a constant inner diameter of the lumen of the sheath body 1700, but taperes 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, it 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, it can be manufactured by thermoforming a small tube of the selected tapered tip material onto the distal end 1702 of the sheath body 1700. One advantage of a tapered tip is that it can minimize trauma to the vascular system when inserting the sheath, while maintaining desirable material properties for the sheath.

[0090] Figure 19 shows a schematic profile of the flexible sheath body 1700 of Figure 17, where the first strip 1706 has a first width 1710 and the second strip 1708 has a second width 1712. Figure 19 also shows the helix angle 1714. The helix 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 two widths, 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 case, 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 case, 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 helix angle can vary from 0° to 90°. In a helical design, the helix angle 1714 is preferably in the range of 60° to 80°. As described above, the sheath body 1700 can also alternatively have a ring design that includes alternating rings of materials with different rigidities or a longitudinal strip design that includes alternating strips of materials with different rigidities. If a ring design is used, the helix 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 helix 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 may have notches to facilitate peel-away of the sheath body 1700. The notches are triangular and may form part of the wall of the sheath body 1700. The wall of the sheath body 1700 may have a thickness in the range of 0.1 mm to 1.67 mm. The notches may occupy 50% to 90% of the total wall thickness. For example, the thickness of the notches may 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 may be aligned axially along the length of the sheath body 1800 and oriented opposite to each other. The first internal notch 1802 and the second internal notch 1804 extend along the inner surface of the sheath body 1800. As will be further described below in relation to Figure 9, the first internal notch 1802 and the second internal notch 1804 can be formed on the mandrel during the manufacture of the sheath body 1800. Similarly, the internal notch 1606 of the sheath hub 1602 can be formed on the core pin during the 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 sheath peel-away by cutting the helices of the first strip 1706 and the second strip 1708.

[0092] Alternatively, the notches on the sheath body may also 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 may be aligned axially along the length of the sheath body 1900 and oriented opposite to each other. 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 into the sheath hub 1602 by skiving, at least partially. In another aspect, the outer notch 1606 of the sheath hub 1602 may be formed by the geometry in the mold during the manufacture of the sheath hub 1602. Providing notches on the outer surface of the sheath provides a smooth, circular inner surface of the sheath to facilitate the passage of instruments and devices to be inserted.

[0093] The sheath body 1700 can be manufactured 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. Figure 24 shows process 1900 for manufacturing the flexible sheath body 1700 by lamination, as described above in relation to Figure 17. In step 1702, the first strip 1706 of the first material and the second strip 1708 of the second material are wrapped around the mandrel adjacent to each other. As described above in relation to Figure 17, the first strip 1706 and the second strip 1708 can be made of materials having different flexibility and rigidity. For example, the first strip 1706 can be made of a first material having first rigidity, and the second material can be made of a second material having second rigidity. The rigidity of the first material can be higher than that of the second material.

[0094] In step 1904, the first distal end of the first strip 1706 and the second distal end of the second strip 1708 are secured. For example, the first distal end of the first strip 1706 and the second distal end of the second strip 1708 can be clamped in place to a mandrel. Alternatively, both distal ends can be enclosed within a restraining sheath or held in place with temporary adhesive.

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

[0096] In step 1908, the first strip 1706, the second strip 1708, and the heat shrink tubing are placed on the mandrel. When heat is applied to the heat shrink tubing, it heats the first strip 1706 and the second strip 1708, causing them to bond to each other along the helical edges 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 heat the heat shrink tubing can be a laser beam or any other suitable heating method.

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

[0098] In step 1912, when the heat shrink tubing is removed, the bonded first strip 1706 and second strip 1708 remain on the mandrel.

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

[0100] As described above, the sheath body can be fabricated from two strips of material having different rigidities. Alternatively, the sheath body may also include a lumen made of a third material. Figure 25 shows an exemplary sheath body 2100 including a first strip 2102 made of a first material, a second strip 2104 made of a second material, and a lumen 2106. In one view, the sheath body 2100 includes a ring design that includes alternating rings of material having different rigidities. In another view, the sheath body 2100 includes a longitudinal strip design that includes alternating strips of material having different rigidities. The lumen 2106 may be made of a third material having the same or different rigidity as the first and / or second material. In one view, the lumen 2106 may be made of the same material as the first strip 2102 or the second strip 2104. In another view, the lumen 2106 may be fabricated from a slippery material such as PTFE or FEP. Similar to the sheath body 1800 detailed in relation to Figures 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 may be aligned axially along the length of the sheath body 2100 and oriented opposite to each other. The first external notch 2108 and the second external notch 2110 may 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 may pass through the thickness of the first strip 2102 and the second strip 2104 and then, partially, but not completely, pass through the thickness of the lumen 2106. As described above, the first external notch 2108 and the second external notch 2110 may be cut into the sheath body 2100 by skiving. Alternatively, as detailed in relation to Figures 20 and 21, the notch may be on the inner surface, and the first strip 2102 and the second strip 2104 may be surrounded by the outer tube.By including the lumen 2106 in the sheath body 2100, consistent and smooth tear propagation can be achieved compared to the sheath bodies 1700, 1800, and 1900. Extending the first external notch 2108 and the second external notch 2110 partially through the thickness of the lumen 2106 increases the likelihood of tear propagation along the notch and decreases the likelihood of tear propagation along the interface between the first and second strips.

[0101] The foregoing is merely illustrative of the principles of the present disclosure, and the apparatus may also be realized in aspects other than those presented herein for illustrative purposes only, not for limitation. Although the apparatus disclosed herein is shown in relation to the use of a blood pump in percutaneous insertion, it will be understood that it may also be applicable to apparatus in other applications requiring hemostasis.

[0102] After considering this disclosure, those skilled in the art will likely envision variations and modifications. The disclosed features can be realized in any combination and partial combination (including multiple dependent and partial combinations) with one or more other features described herein. These various features, including any of their components, may be combined or integrated as other systems. Furthermore, certain features may be omitted or not realized at all.

[0103] Examples of modifications, substitutions, and alterations are readily apparent to those skilled in the art and can be implemented without departing from the scope of the information disclosed herein. All references cited herein are incorporated by reference as a whole and constitute part of this application.

Claims

1. A method for manufacturing a peel-away sheath assembly for insertion of a blood pump, comprising a peel-away sheath body and a peel-away sheath hub, The process of coating the mandrel with the first layer of the first material; A step of coating the mandrel with the first layer, and then heat-shrinking the first layer; A step of coating the heat-shrunk first layer with a second layer of the second material which is a reinforcing layer, and the outermost third layer of the third material; and The process of forming a peel-away sheath body by heat-shrinking the first layer, the second layer, and the outermost third layer. Methods that include...

2. The method according to claim 1, wherein the mandrel has a raised projection configured to leave at least one inner diameter notch in the heat-shrunk sheath body, the at least one inner diameter notch extending from the innermost surface of the first layer, passing through the second layer, and terminating before or within the outermost third layer.

3. The method according to claim 2, wherein at least one internal diameter notch defines at least one peelaway line.

4. The method according to claim 1, wherein the first material is a thermoplastic resin.

5. The method according to claim 4, wherein the thermoplastic resin includes PEBAX.

6. The method according to claim 4, wherein the thermoplastic resin includes TPU.

7. The method according to claim 1, wherein the heat shrinking of the first layer includes covering the first layer with a heat shrinkable material and heating the first layer and the heat shrinkable material.

8. The method according to claim 7, wherein the heat shrinkable material is a polytetrafluoroethylene (PTFE) heat shrinkable material.

9. The method according to claim 1, wherein the outermost third layer is formed using a mold during thermal shrinkage, and the mold is configured to leave at least one outer diameter notch in the peel-away sheath body.

10. The method according to claim 9, wherein at least one outer diameter notch penetrates the second layer from the outermost surface of the outermost third layer and terminates before or within the first layer.

11. The method according to claim 10, wherein at least one outer diameter notch defines at least one peelaway line.

12. A method for manufacturing a peel-away sheath assembly for insertion of a blood pump, comprising a peel-away sheath body and a peel-away sheath hub, The process of coating the mandrel with the first layer of the first material; A step of heat-shrinking the first layer; A step of coating the mandrel with a second layer of a second material, wherein the mandrel is already coated with the first layer and the second layer is a reinforcing layer; A step of heat-shrinking the second layer while the second layer is positioned on the first layer and the mandrel; The process of coating the mandrel with a third layer of the third material; and The process of heat-shrinking the third layer while it is positioned on the second layer, the first layer, and the mandrel to form a peel-away sheath body. Methods that include...

13. The method according to claim 12, wherein the mandrel has a raised projection configured to leave at least one inner diameter notch in the peelaway sheath body, the at least one inner diameter notch extending from the innermost surface of the first layer through the second layer and terminating before or within the third layer.

14. The method according to claim 13, wherein the at least one internal diameter notch defines at least one peelaway line.

15. The method according to claim 12, wherein the steps of heat-shrinking the first layer, heat-shrinking the second layer, and heat-shrinking the third layer are performed simultaneously.

16. The method according to claim 12, wherein the step of heat-shrinking the second layer is performed after the step of heat-shrinking the first layer.

17. The method according to claim 16, wherein the steps of heat-shrinking the second layer and heat-shrinking the third layer are performed simultaneously.

18. The method according to claim 12, wherein the third layer is formed using a mold during thermal shrinkage, and the mold is configured to leave at least one outer diameter notch in the peel-away sheath body.

19. The method according to claim 18, wherein at least one outer diameter notch penetrates the second layer from the outermost surface of the third layer and terminates before or within the first layer.

20. The method according to claim 19, wherein at least one outer diameter notch defines at least one peelaway line.

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