Variable stiffness distal extension for blood pump systems

Abstract

A system and method for providing a blood pump system having a distal extension with variable stiffness are disclosed. The distal extension with variable stiffness may have at least one section of continuously variable stiffness, resulting in a stiffness profile that decreases distally along the length of the distal extension. Variable stiffness may be achieved by changing one or more radial dimensions of the extension. For example, in some embodiments, the outer diameter of the distal extension may decrease along at least a portion of the distal extension. The distal extension may include a lumen configured to accommodate an element extending longitudinally.

Description

Technology Field

[0001] This application claims priority to U.S. provisional patent application No. 62 / 835,636 filed on April 18, 2019. Background Technology

[0002] Blood pump assemblies, such as intracardiac or intravascular blood pumps, can be introduced into the heart to deliver blood from the heart into the arteries. These mechanical circulatory support devices are often introduced to support cardiac function after a patient has experienced a cardiac episode. One type of device is a set of devices known as an "impeller" heart pump. Some blood pump assemblies can be introduced percutaneously through the vascular system during cardiac procedures. Specifically, blood pump assemblies can be inserted into the left ventricle across the valves into the ascending aorta via a catheter insertion procedure through the femoral artery or the axillary / subclavian artery. The inserted blood pump assembly can be configured to draw blood from the left ventricle of the heart through a cannula and discharge it into the aorta. The blood pump assembly can also be configured to draw blood from the inferior vena cava and discharge it into the pulmonary artery. Some mechanical circulation support devices are driven by onboard motors, while others are driven by external motors and drive cables. [Prior Art] US 2012 / 172655 A1 (July 5, 2012) US 2017 / 232169 A1 (August 17, 2017) WO 2018 / 089970 A1 (May 17, 2018)

[0003] The inventors recognized that the stability of a blood pump assembly within the ventricle can affect the use and performance of the pump. For example, if the blood pump assembly is placed too close to the apex of the ventricle, cardiac tissue may be aspirated into the pump, leading to arrhythmia problems; if the blood pump assembly is placed too deep within the ventricle, the outlet may be located at the aortic valve. Additionally, the operation of the blood pump within the heart or the movement of the heart muscle itself can generate a flow field that displaces the pump in place. When a blood pump is moved from its selected operating position, the pump's location must be changed, and typically, the pump must be turned off to change this location. Such relocation consumes valuable time and generally interferes with patient care. In any case, frequent relocation of the heart pump within the patient may damage either the pump or the heart. Therefore, it is highly desirable to reduce potential damage to the patient's heart and vascular system while maintaining and improving pump and flow stability. Distal extensions, particularly traumatic extensions such as pigtails, can advantageously stabilize the pump within the heart while reducing or minimizing the occurrence of trauma to the vascular system or the heart.

[0004] In some cases, to effectively stabilize the blood pump system while avoiding or minimizing trauma to the heart, it is desirable to have a blood pump system with a distal extension having lower stiffness in the distal portion than in the proximal portion. While the stiffer proximal portion can reduce buckling and provide a desired standoff distance between the pump components (e.g., pump inlet or outlet) and the heart tissue, the less stiff distal portion can help prevent damage to the heart tissue. Some pumps use a distal extension comprising two sections, each having different stiffness characteristics, where the distal section has lower stiffness characteristics than the proximal section. Such pumps are disclosed, for example, in U.S. Patent No. 9,814,814, and generally exhibit a stepwise stiffness profile in which each section of the distal extension has a unique stiffness. Therefore, the stepwise change in stiffness is abrupt. Consequently, the mechanical properties of such a distal extension are limited by the number of selected sections and the material used for these sections.

[0005] The inventors have recognized numerous advantages associated with a distal extension for a cardiac pump system or other medical device exhibiting a continuous stiffness profile. A continuous stiffness profile as used herein does not have abrupt step changes, but rather does not have approximately constant incremental changes in stiffness over at least a portion of the length of the distal extension. The resulting profile is sloped and step-like. The slope of the stiffness profile can be of any functional form over a portion of the length of the distal extension, such as constant, variable, etc. As such, the stiffness profile can be linear, non-linear, etc. For example, a distal extension having a continuous stiffness profile may be better suited to a wider range of anatomical dimensions than a distal extension having a step stiffness profile. Furthermore, the distal extension described herein facilitates retrograde crossing of the aortic valve without a guidewire, for example, relocating a pump that has inadvertently moved out of the ventricle and / or inserting the pump into the ventricle with completely "wireless access" (i.e., without the need for an access guidewire). In some cases, such wireless access can be achieved through the continuous deflection of the distal extension as it advances toward the aortic valve. Specifically, instead of becoming trapped at the apex of the aortic valve, the continuous advancement of the distal extension can cause it to deflect to form a loop-like structure, which can subsequently escape across the valve into the left ventricle.

[0006] According to some embodiments, the system, method, and apparatus described herein provide a variable stiffness distal extension for a blood pump system or other suitable medical device. Generally, the variable stiffness distal extension has at least one section of continuous variable stiffness and creates a continuous stiffness profile that decreases along the distal direction over at least a portion of the distal extension. Continuous variable stiffness can be achieved by continuously varying at least one radial dimension of the distal extension. For example, in one embodiment, the varying radial dimension may be the outer diameter of the distal extension, while the inner diameter of the distal extension forming the inner lumen is kept constant. In this embodiment, the thickness of the wall formed by the inner and outer diameters varies according to the outer diameter. In one exemplary embodiment, the outer diameter of the distal extension decreases along the distal direction while the inner diameter is kept constant. In such an embodiment, the thickness of the wall decreases along the distal direction. The continuous stiffness profile can be selected by adjusting the outer diameter of the distal extension and can generally be selected to have lower stiffness corresponding to a smaller outer diameter. For example, in the aforementioned implementation, the proximal portion of the distal extension having a thicker wall thickness may exhibit greater stiffness, and the stiffness may decrease continuously along the distal direction in at least a portion of the distal extension as the wall thickness decreases.

[0007] According to a first embodiment of the present disclosure, a variable stiffness distal extension for a blood pump system comprises an integrally formed body. The integrally formed body further comprises a distal end and a proximal end. An outer wall extends between the distal end and the proximal end. An inner wall extends between the distal end and the proximal end. The inner wall forms an inner lumen. The inner lumen is configured to accommodate a guidewire and may also be configured to accommodate an element extending in another longitudinal direction. For example, an additional element that may be configured to accommodate the inner lumen is a guidewire loading aid that may be pre-assembled into the inner lumen. In another example, the additional element may be a stylet. The inner lumen has a constant diameter between the distal and proximal portions. The integrally formed body further comprises a proximal portion. The proximal portion of the integrally formed body is configured to be connected to a blood pump system. The proximal portion has a first inner diameter along the inner wall and a first outer diameter along the outer wall. The proximal portion further comprises a distal tip portion. The distal tip portion of the proximal part has a second inner diameter along the inner wall and a second outer diameter along the outer wall. The first outer diameter formed by the outer wall of the distal extension decreases continuously along the proximal part in the distal direction toward the second outer diameter.

[0008] According to a first embodiment of the present invention, a variable stiffness distal extension for a blood pump system comprises an integrally formed body, wherein the body comprises a distal end, a proximal end, an outer wall extending between the distal end and the proximal end, an inner wall forming a lumen extending between the proximal end and the distal end—the lumen is configured and arranged to accommodate a longitudinally extending element—a proximal portion configured to be connected to the blood pump system, and a distal portion extending distally from the proximal portion, wherein the outer diameter of the integrally formed body formed by the outer wall decreases continuously along at least a portion of the proximal portion in the distal direction, and the inner lumen has a constant inner diameter between the proximal end and the distal end. The integrally formed body further comprises a proximal portion. The proximal portion of the integrally formed body is connected to the blood pump system. The proximal portion has a first outer diameter along the outer wall and a first inner diameter along the inner wall. The proximal portion comprises a distal tip portion. The distal tip portion of the proximal part has a second inner diameter along the inner wall and a second outer diameter along the outer wall. The first outer diameter formed by the outer wall of the distal extension is continuously reduced along the proximal part in a distal direction toward the second outer diameter.

[0009] The first outer diameter and the second outer diameter may be selected to form a specific stiffness profile. In some embodiments, the first outer diameter at the proximal end of the distal extension is about 1 millimeter to about 7.5 millimeters. In some embodiments, the second outer diameter at the proximal end of the distal extension is about 0.5 millimeters to about 5 millimeters. In some embodiments, the first outer diameter at the proximal end of the distal extension is about 2.5 millimeters to about 5 millimeters. In some embodiments, the second outer diameter at the proximal end of the distal extension is about 3 millimeters to about 4 millimeters. In some embodiments, the first outer diameter at the proximal end of the distal extension is about 3 millimeters to about 4.5 millimeters. In some embodiments, the second outer diameter at the proximal end of the distal extension is about 3.5 millimeters to about 4 millimeters. In some embodiments, the first outer diameter at the proximal end of the distal extension is about 4 millimeters. In some implementations, the second outer diameter at the distal end of the distal extension is approximately 3.75 millimeters. Any of the above ranges for the first outer diameter at the proximal end of the distal extension may be combined with any of the above ranges for the second outer diameter at the distal end of the distal extension to create a desired variation in diameter along the length and to create a desired thickness and stiffness profile of the distal extension. For example, when the first outer diameter is 9 mm at the proximal end, the second outer diameter may be 4 mm at the distal end. Also, when the first outer diameter is 1 mm at the proximal end, the second outer diameter may be 0.6 mm at the distal end.

[0010] At least one advantage of tapering the first outer diameter of the proximal portion in the distal direction is that the section of the proximal portion having a larger outer diameter will be more rigid than the section having a smaller outer diameter. Thus, the rigidity of such an embodiment is reduced in the distal direction. Reduced rigidity in the distal direction is desirable for several reasons, at least one of which is that a softer distal end can help avoid a variable-rigidity distal extension that causes damage to the vascular system when the extension crosses the vascular system. Similarly, a reduced-rigidity distal end can help avoid a distal extension that causes damage to the patient's heart valves and / or heart chambers (e.g., ventricular wall tissue) when the extension is introduced and positioned within the patient's heart.

[0011] Furthermore, according to some aspects, the more rigid proximal portion of the distal extension can help stabilize the pump within the ventricle by allowing the nearest portion of the distal extension to maintain its length when the thrust generated by the operation of the pump causes the most distal portion of the distal extension to bend and / or buckle. For example, the more rigid proximal portion can form a desired "isolation" distance to maintain a desired gap between the pump component (e.g., pump inlet) and the ventricular wall or other tissues of the heart.

[0012] In an additional implementation, the variable stiffness distal extension may further include at least a third axial portion distal to the first axial portion and the second axial portion. While an extension having only two axial portions may have a fragmentary stiffness profile, an integrally formed extension having a diameter decreasing in the distal direction may have a relatively continuous and smooth stiffness profile.

[0013] A specific shape of the distal tip portion may be selected to achieve the desired stability of the pump within the heart. The distal tip may generally include any curved shape. In some implementations, the variable stiffness distal extension may have a j-shaped distal tip portion. In some implementations, the j-shaped distal tip portion has a radius of curvature between about 5 millimeters and about 15 millimeters. In other implementations, the j-shaped distal tip portion has a radius of curvature between about 7.5 millimeters and about 12.5 millimeters. In a specific implementation, the j-shaped distal tip portion has a radius of curvature of about 10 millimeters. In additional implementations, the variable stiffness distal extension may have a pigtail-shaped distal tip portion. In certain implementations, the radius of curvature of the pigtail-shaped distal tip portion is constant. In some implementations, the pigtail-shaped distal tip portion has a radius of curvature between about 5 millimeters and about 15 millimeters. In another embodiment, the pigtail-shaped distal tip portion has a radius of curvature between about 7.5 millimeters and about 12.5 millimeters. In a specific embodiment, the pigtail-shaped distal tip portion has a radius of curvature of about 10 millimeters. In some embodiments, the radius of curvature of the pigtail-shaped distal extension decreases in the distal direction. In some embodiments, the radius of curvature at the distal end of the distal tip portion is about 10% to about 50% smaller than the radius of curvature at the proximal end of the distal tip portion. In another embodiment, the radius of curvature at the distal end of the distal tip portion is about 20% to about 40% smaller than the radius of curvature at the proximal end of the distal tip portion. In a specific embodiment, the radius of curvature at the distal end of the distal tip portion is about 30% smaller than the radius of curvature at the proximal end of the distal tip portion. In another implementation, the radius of curvature at a point along the distal extension is inversely proportional to the distance from the origin to the point along the distal extension so that the distal extension takes the shape of an Euler spiral.At least one advantage of having a J-shaped or pigtail-shaped distal tip is that such a geometry can help stabilize the pump within the patient's ventricle.

[0014] In certain implementations, the variable stiffness distal extension may additionally include a lumen. In such implementations, the lumen extends along the entire length of the distal extension. The lumen may also form the inner diameter of the distal extension. The size and shape of the lumen may be configured to accommodate a guide wire or additional elements other than the guide wire. For example, the additional elements may be a guide wire loading aid (e.g., a guide wire loading lumen) or a stylet. In some implementations, the inner diameter of the distal extension (which may be formed by the lumen) is constant along the entire length of the distal extension.

[0015] In some embodiments, the inner diameter formed by the lumen may be between about 0.1 millimeters and about 5.5 millimeters. In additional embodiments, the inner diameter may be between about 1 millimeter and 3 millimeters. At least one advantage of incorporating a lumen with a constant inner diameter is that it can create a desired continuous stiffness profile when combined with a distal extension of a continuously changing outer diameter. Additionally, the inner lumen is generally useful because it allows for the introduction of a guide wire while maintaining a small insertion profile and enabling the device to maintain a continuous stiffness profile. In other embodiments, the inner diameter of the distal extension formed by the lumen decreases continuously between the proximal end of the first axial portion and the distal end of the first axial portion. In some embodiments, the inner diameter of the distal extension decreases from about 5.5 millimeters at the proximal end of the first axial portion to about 0.1 millimeters at the distal end of the first axial portion. In another embodiment, the inner diameter of the distal extension is reduced from about 3 millimeters at the proximal end of the first axial portion to about 1 millimeter at the distal end of the first axial portion.

[0016] At least one advantage of a lumen having a decreasing inner diameter between the proximal end of the first axial portion and the distal end of the first axial portion is that a preferred continuous stiffness profile can be obtained by combining a decreasing outer diameter and a decreasing inner diameter.

[0017] In another embodiment, a variable stiffness distal extension for a blood pump system comprises a flexible extended body. The flexible extended body of the distal extension has a distal end and a proximal end. The flexible extended body may further comprise an outer wall. The outer wall is configured to extend between the distal end and the proximal end of the distal extension. The flexible extended body is further composed of a first axial portion, a second axial portion, and a distal tip portion. The second axial portion is distal to the first axial portion and is formed integrally with the first axial portion. The distal tip portion is located distal to the second axial portion. The distal tip portion is further formed integrally with the second axial portion. The outer diameter of the outer wall of the flexible extended body is configured to decrease continuously from the proximal end of the distal extension to the distal end of the distal extension. At least one advantage of the continuously decreasing outer diameter of the outer wall is that the section along the length of the distal extension with a larger outer diameter increases stiffness, while the section with a smaller outer diameter decreases stiffness, so that a distal extension with an outer diameter decreasing distally also decreases distally. As previously discussed, a continuous stiffness profile decreasing distally can provide many advantages. For example, a flexible distal end can allow a physician to easily introduce the distal extension into the patient's vascular system without damaging the vascular system. Furthermore, the relatively stiff proximal end of the distal extension, corresponding to the section with a larger outer diameter, can help stabilize the pump by allowing the closest part of the distal extension to maintain its length (e.g., the desired "isolation" distance) when the thrust generated by the pump's operation causes the most distal part of the distal extension to bend and / or buckle. Similarly, the relatively stiff proximal end of the distal extension, corresponding to the section with a larger outer diameter, can help stabilize the heart valve and the pump within the patient's heart chamber.

[0018] In some embodiments, the outer diameter of the distal extension decreases continuously from about 6 millimeters at the proximal end of the first axial portion to about 0.5 millimeters at the distal end of the first axial portion. In other embodiments, the outer diameter of the distal extension decreases continuously from about 4 millimeters at the proximal end of the first axial portion to about 2 millimeters at the distal end of the first axial portion. In certain embodiments, the outer diameter of the distal extension is constant between the proximal end of the second axial portion and the distal end of the second axial portion. In some embodiments, the first axial portion has a first stiffness. Additionally, the second axial portion has a second stiffness. In some embodiments, the first stiffness is greater than the second stiffness. As previously discussed, because the proximal and distal portions are stiff, the physician can manipulate the extension through the patient's vascular system, whereas because the distal end is flexible, the extension can advance through the vascular system without damaging the vascular system.

[0019] In certain embodiments, the distal extension further comprises a third pigtail-shaped portion. The third pigtail-shaped portion has a third stiffness. This third stiffness is smaller than the second stiffness. In some embodiments, the first axial portion has a first axis. The second axial portion has a second axis. In certain embodiments, the first axis is not parallel to the second axis. In some embodiments, the first axis and the second axis are oriented at a predetermined angle relative to each other. In some embodiments, this angle is in the range of about 0 to about 50 degrees. In other embodiments, the angle is in the range of about 10 to about 40 degrees. In yet another embodiment, the angle between the first axis and the second axis is in the range of about 15 to about 35 degrees. In certain embodiments, the angle between the first axis and the second axis is about 30 degrees. The specific angle at which the first axis and the second axis are oriented may be selected to produce specific structural characteristics of the distal extension. For example, the angle can be selected to allow the physician to easily manipulate the extension through the patient's vascular system. The angle may also be adjusted to maximize the ease with which the pump and extension cross the aortic valve. Additionally, the angle can be selected to provide the most stable configuration of the blood pump system within the ventricle.

[0020] In some implementations, the distal extension may be formed integrally from one or more materials. For example, the distal extension may be formed from a single material having varying dimensions along the length of the distal extension to provide desired mechanical properties. Alternatively or additionally, the material of the distal extension may vary along the length of the distal extension. For example, the distal extension may be formed as a composite structure comprising two or more materials, and the composition of the two or more materials may vary along the length of the distal extension. In another example, the material of the distal tip section may be selected to have lower stiffness than the material of the proximal section. In this regard, it should be understood that by varying the material and / or dimensions of the distal extension, desired mechanical responses, such as a stiffness profile that varies along the length of the distal extension, can be achieved.

[0021] Generally, the material(s) of the distal extension may be selected so that the distal extension has a sufficiently smooth surface to prevent biological contamination, fouling, and / or adhesion of the distal extension. In this way, the material of the distal extension may help reduce or prevent thrombus formation. In certain embodiments, the distal extension comprises polyurethane. In other embodiments, the distal extension comprises polyamide. The polyamide may comprise PEBAX or nylon. In further embodiments, the distal extension may comprise an elastomeric polymer or an elastomer. The elastomer may comprise one or more silicone-based polyurethanes or one or more polycarbonate-based polyurethanes. One of these polycarbonate-based polyurethane elastomers is 55D Pellethane®. In other embodiments, the elastomer comprises a blend of these silicone or polycarbonate-based polyurethanes with another elastomer or a compound of these silicone or polycarbonate-based polyurethanes with another elastomer. Elastomer blends and compounds may contain different proportions of these polymers. In other embodiments, the distal extension may comprise a blend or compound of the said elastomer in addition to additives, fillers, and colorants. For example, the use of additives, fillers, and colorants may be used to enhance any combination of fluoroscopic visualization, ultrasound imaging visualization, and stiffness control of the distal extension. Furthermore, it should be understood that the distal extension described herein may be formed in any suitable manner. For example, the distal extension may be formed by a suitable molding and / or extrusion process.

[0022] In additional embodiments, the outer diameter of the distal extension decreases continuously in the distal direction at the third portion of the distal extension. In some embodiments, the outer diameter of the distal extension decreases continuously over the entire length of the third portion. In other embodiments, the outer diameter of the distal extension decreases continuously over the first 10% to about 60% of the length of the third portion. In a specific embodiment, the outer diameter of the distal extension decreases continuously over the first about 20% to about 50% of the length of the third portion. In other embodiments, the outer diameter of the distal extension decreases continuously over the first about 30% to about 40% of the length of the third portion. In some embodiments, the outer diameter of the distal extension decreases continuously over the first about 35% of the length of the third portion. In some embodiments, the outer diameter of the distal extension decreases at the third portion to about 55% to about 95% of the outer diameter of the distal extension of the first portion. In another embodiment, the outer diameter of the distal extension is reduced to about 65% to about 85% of the outer diameter of the distal extension of the first part in the third part.

[0023] In a specific embodiment, the outer diameter of the distal extension is reduced in the third part to about 75% of the outer diameter of the distal extension of the first part. In other embodiments, the second part comprises a material having a first bending modulus, and the third part comprises a material having a second bending modulus. In some embodiments, the first bending modulus is larger than the second bending modulus. For example, the first bending modulus may be larger than the second bending modulus by a factor between about 1 and about 5. In other examples, the first bending modulus may be larger than the second bending modulus by a factor between about 1.5 and about 3.5. In one example, the first bending modulus may be larger than the second bending modulus by about 2 factors. The exact ratio of the bending modulus of the material of the second part to the material of the third part results in a relatively smooth stiffness profile along the length of the distal extension and prevents the transition point between the second part and the third part from becoming a trajectory of twist.

[0024] In a specific embodiment, the first axial portion, the second axial portion, and the third distal tip portion are each formed in size and shape such that the first axial portion is stiffer than the second axial portion and the second axial portion is stiffer than the third distal tip portion. In another embodiment, the third distal tip portion is configured to have lower stiffness than the second axial portion. In another embodiment, the outer diameter of the distal extension decreases at the third distal tip portion. In a specific embodiment, the outer diameter of the distal extension decreases between the proximal and distal ends of the third distal tip portion. In a specific embodiment, the inner diameter of the third portion of the distal extension is constant along the third portion.

[0025] In another embodiment, the blood pump system includes a distal flexible extension. The blood pump system consists of a catheter and a blood pump. The blood pump has a distal end and a proximal end. The system further includes a cannula, which is coupled to the distal end of the blood pump, and includes a cage positioned distal to the cannula. A variable stiffness distal extension is attached to the cage. The variable stiffness distal extension may be any of the extensions described in the application.

[0026] In some embodiments, the blood pump system is configured to be inserted through the patient's vascular system without a guidewire. In these embodiments, the distal extension may contain a partial lumen, or the distal extension may be solid throughout its entire length. In other embodiments, the blood pump system is configured to be inserted through the patient's vascular system using a guidewire. In these embodiments, the distal extension may contain an internal lumen throughout its entire length. In a specific embodiment, the variable stiffness distal tip is configured to create a stiffness gradient between the proximal end of the variable stiffness distal tip and the distal position of the proximal end of the variable stiffness distal tip. In other embodiments, the variable stiffness distal tip of the blood pump system is configured across the aortic valve. Brief explanation of the drawing

[0027] FIG. 1 illustrates an exemplary example of a variable stiffness distal extension formed integrally including an inner lumen. FIG. 2 illustrates an exemplary example of a variable stiffness distal extension integrally formed including first and second axial portions. FIG. 3 illustrates an exemplary example of an integrally formed end extension including a variable outer diameter and a variable inner diameter. FIG. 4 illustrates an exemplary example of an integrally formed end extension including a variable outer diameter and a constant inner diameter. FIGS. 5a to 5c illustrate three exemplary examples of integrally formed distal extensions including variable inner diameter and variable outer diameter. FIG. 6a illustrates an exemplary example of a pigtail-shaped distal tip having a constant radius of curvature. FIG. 6b illustrates an exemplary example of a pigtail-shaped distal tip having various radii of curvature. FIG. 7a illustrates an exemplary example of a j-shaped distal tip portion. FIG. 7b illustrates an exemplary example of a distal extension having first and second axial portions and a j-shaped distal tip. Specific details for implementing the invention

[0028] Specific exemplary embodiments will be described to provide an overall understanding of the systems, methods, and devices disclosed herein. While the embodiments and features described herein are specifically described for use in relation to cardiac pumps, it will be understood that the teachings may be adapted and applied to other pumps and other types of medical devices.

[0029] The system, method, and apparatus described herein provide a variable stiffness distal extension integrally formed for a blood pump system. Generally, the system comprises an extension having a proximal portion and a distal tip portion. In such an implementation, the proximal portion may have an outer diameter greater than the outer diameter of the distal tip portion. The outer diameter of the proximal portion of the distal extension is generally configured to decrease in the distal direction. This gradual decrease in the outer diameter along the length of the distal extension creates a continuous stiffness profile along the length of the distal extension that decreases in the distal direction.

[0030] The relatively soft distal end of the distal extension, created by this continuous stiffness profile, allows the extension to be introduced into the patient's vascular system without damaging the vascular system when it contacts the patient's vessel wall, and in some cases, helps facilitate the crossing of the aortic valve without the use of a guidewire. At the same time, the relatively stiff proximal end of the distal extension, created by this continuous stiffness profile, allows the extension to be easily manipulated through the vascular system by a physician and can help form the desired "isolation" distance when the pump is positioned in the ventricle as previously described. The outer diameter can be adjusted along the length of the distal extension to establish and maintain the desired continuous stiffness profile along the length of the distal extension.

[0031] FIG. 1 illustrates an exemplary example of a variable stiffness distal extension (100) integrally formed for a blood pump system including an inner lumen. The distal extension (100) further comprises a body (102), a distal end (104), a proximal end (106), an outer wall (108), an inner wall (110), an inner lumen (112), a proximal portion (114), a first inner diameter (116), a first outer diameter (118), a distal tip portion (120), a second inner diameter (122), a second outer diameter (124), and a distal tip (126). The proximal end (106) of the body (102) of the distal extension (100) is configured to be attached to a blood pump system. The outer wall (108) of the distal extension (100) forms at least a first outer diameter (118) and a second outer diameter (124). At the proximal end (106) of the body (102), the first outer diameter (118) decreases continuously in the distal direction toward the second outer diameter (124) at the distal end (104) of the body (102). The distal tip (126) extends from the distal end of the distal tip portion (120). As shown in FIG. 6, in some embodiments, the distal tip (126) is configured to have a pigtail shape. As shown in FIG. 7, in other embodiments, the distal tip (126) is configured to have a "j" shape. The distal tip (126) may additionally include any other curved shape. The distal tip (126) may help stabilize the pump within the ventricle and may help prevent heart tissue from being sucked into the pump during operation.

[0032] In some embodiments, the first outer diameter (118) at the proximal end (106) of the distal extension (100) is between about 1 millimeter and about 7.5 millimeters. In this embodiment, the second outer diameter (124) at the distal end (104) of the distal extension (100) is between about 0.5 millimeters and about 5 millimeters. In another embodiment, the first outer diameter (118) at the proximal end (106) of the distal extension (100) is between about 2.5 millimeters and about 5 millimeters. In this embodiment, the second outer diameter (124) at the distal end (104) of the distal extension (100) is between about 3 millimeters and about 4 millimeters. In a specific embodiment, the first outer diameter (118) at the proximal end (106) of the distal extension (100) is between about 4 millimeters and about 6 millimeters. In this embodiment, the second outer diameter (124) at the distal end (104) of the distal extension (100) is between about 3 millimeters and about 4 millimeters. In a further embodiment, the first outer diameter (118) at the proximal end (106) of the distal extension (100) is about 4 millimeters. In this embodiment, the second outer diameter (124) at the distal end (104) of the distal extension (100) is about 3.75 millimeters. At least one advantage of the reduction from the first outer diameter (118) to the second outer diameter (124) in the distal direction is that the proximal part (114) of the body (102) having the larger diameter is stronger than the distal part (120) of the body (102) having the smaller diameter. As such, the stiffness of such an implementation decreases in the distal direction. As previously discussed, such an arrangement having a continuously variable stiffness profile can allow a physician to guide expansion through the patient's vascular system more easily and to do so without damaging the patient's vascular system. The inner wall (110) forms an inner lumen (112), a first inner diameter (116), and a second inner diameter (122). In some implementations, as illustrated in the exemplary example shown in FIG. 1, the first inner diameter (116) and the second inner diameter (122) are equivalent, that is, the inner diameter over the entire length of the body (102) is constant.

[0033] Alternatively, the first inner diameter (116) may also be larger than the second inner diameter (122), corresponding to a decrease in the first inner diameter (116) distally along the length of the body (102). In some embodiments, the first inner diameter (116) formed by the inner lumen (112) may be between about 0.1 millimeters and about 5.5 millimeters. In additional embodiments, the first inner diameter (116) may be between about 1 millimeter and 3 millimeters. In some embodiments, the second inner diameter (122) formed by the inner lumen (212) may be between about 0.5 millimeters and about 5.5 millimeters. In additional embodiments, the second inner diameter (122) may be about 2 millimeters.

[0034] FIG. 2 illustrates another exemplary example of an integrally formed variable stiffness distal extension (200) for a blood pump system having a first axial portion (214) and a second axial portion (220) offset from each other by an angle (222). The distal extension (200) further comprises a body (202), a distal end (204), a proximal end (206), an outer wall (208), an inner wall (210), an inner lumen (212), a first axial portion (214), a first inner diameter (216), a first outer diameter (218), a second axial portion (220), an angle (222), a distal tip (224), a second outer diameter (226), a second inner diameter (228), a first axis (230), and a second axis (232). The proximal end (206) of the body (202) of the distal extension (200) is configured to be attached to a blood pump system. The outer wall (208) of the distal extension (200) forms a first outer diameter (218) and a second outer diameter (226). At the proximal end (206) of the body (202), the first outer diameter (218) may decrease continuously in the distal direction toward the second outer diameter (226) at the distal end (204) of the body (202).

[0035] As previously discussed, the variable stiffness distal extension may further include at least a third axial portion distal to the first axial portion (214) and the second axial portion (220). The formed extension, with a diameter decreasing in the distal direction, may have a relatively continuous and smooth stiffness profile. In some embodiments, the first axial portion (214) comprises a first material, the second axial portion (220) comprises a second material, and the third axial portion comprises a third material. For example, the second axial portion (220) may comprise a material having a first bending modulus, and the third portion may comprise a material having a second bending modulus. In some embodiments, the first bending modulus is greater than the second bending modulus. For example, the first bending modulus may be greater than the second bending modulus by a factor between about 1 and about 5. In other examples, the first bending modulus may be greater than the second bending modulus by a factor between about 1.5 and about 3.5. In one example, the first bending modulus may be about a factor of 2 larger than the second bending modulus. The exact ratio of the bending modulus of the second part material to the material of the third part prevents a relatively smooth stiffness profile along the length of the distal extension and a distinct transition point between the second and third parts from becoming a trajectory of twist and / or bending. As previously discussed, at least one advantage of the reduction from the first outer diameter (218) to the second outer diameter (226) in the distal direction is that the stiffness of such an implementation decreases in the distal direction. Thus, a physician can more easily guide the extension having this continuously variable longitudinal stiffness profile through the patient's vascular system and do so without damaging the patient's vascular system. The inner wall (210) forms the inner lumen (212), the first inner diameter (216), and the second inner diameter (228).

[0036] As illustrated in FIG. 2, the first inner diameter (216) and the second inner diameter (228) are equivalent, that is, the inner diameter over the entire length of the body (202) is constant. In some embodiments, the first inner diameter (216) is larger than the second inner diameter (228), which corresponds to a decrease in the first inner diameter (216) distally along the length of the body (202). The first axial portion (214) forms the first axis (230). The second axial portion (220) forms the second axis (232). The first axis (230) and the second axis (232) are offset from each other by an angle (222). In some embodiments, the first axis (230) and the second axis (232) are oriented from each other at an angle (222) between about 0 degrees and about 50 degrees. In other embodiments, the angle (222) is in the range of about 10 degrees to about 40 degrees. In yet another embodiment, the angle (222) between the first axis (330) and the second axis (232) is in the range of about 15 degrees to about 35 degrees. In certain embodiments, the angle (222) between the first axis (230) and the second axis (232) is about 30 degrees. At least one advantage of having the first axial portion (214) offset from the second axial portion (220) by an angle (222) is that the angle (222) can make it easier for a physician to operate the pump across the aortic valve through the patient's vascular system.

[0037] FIG. 3 illustrates an exemplary profile (300) of an integrally formed variable stiffness distal extension having a variable outer diameter (302), a variable inner diameter (304), a distal end (306), and a proximal end (308). The outer diameter (302) is configured to decrease from the proximal end (308) to the distal end (306). The inner diameter (304) is configured to increase from the proximal end (308) to the distal end (306). In this implementation, the stiffness of the distal extension decreases in the distal direction. One advantage of this configuration is that the rate of decrease of the outer diameter (302) and the rate of increase of the inner diameter (304) can be selected to fine-tune the continuous stiffness profile along the length of the distal extension.

[0038] FIG. 4 illustrates an exemplary profile (400) having a variable outer diameter (402), a constant inner diameter (404), a distal end (406), and a proximal end (408). The outer diameter (402) is configured to decrease from the proximal end (408) toward the distal end (406). This configuration presents a continuous stiffness profile that decreases in the distal direction to the distal extension. This continuous stiffness profile allows the extension to be easily manipulated through the patient's vascular system while preventing damage to the vascular system when the extension is introduced to the patient.

[0039] FIG. 5 illustrates an exemplary profile of an integrally formed variable stiffness distal extension having a variable outer diameter (502), a variable inner diameter (504), a thickness (506), a distal end (508), and a proximal end (510). The variable outer diameter (502) and the variable inner diameter (504) are configured to decrease from the proximal end (510) in the direction of the distal end (508). FIG. 5a, 5b, and 5c illustrate exemplary examples of the rate of decrease of the outer diameter (502) and the inner diameter (504). The relative rate of decrease of the outer diameter (502) and the inner diameter (504) controls the variability of the thickness (506). As shown in FIG. 5a, the outer diameter (502) and the outer diameter (504) decrease at the same rate so that the thickness (506) remains constant. In some implementations, the outer diameter (502) and the outer diameter (504) may decrease at different rates so that the thickness (506) is also variable. FIG. 5b illustrates an inner diameter (504) decreasing at a greater rate than the outer diameter (502). As such, the thickness (506) increases in the distal direction. FIG. 5c illustrates an outer diameter (502) decreasing at a greater rate than the inner diameter (504) so ​​that the thickness (506) decreases in the distal direction. The stiffness of the exemplary example illustrated in FIG. 5c decreases in the distal direction.

[0040] FIGS. 6A and 6B illustrate exemplary examples of a pigtail-shaped distal tip (600). FIG. 6A illustrates a pigtail-shaped distal tip (600) having a constant radius of curvature, and FIG. 6B illustrates a pigtail-shaped distal tip having varying radii of curvature. A pigtail-shaped distal tip (600) generally has a radius of curvature (602, 610), a lumen (604), a distal end (606), and a proximal end (608). The lumen (604) extends along the entire length of the distal tip (600). The radius of curvature (602) is constant or variable along the length of the distal tip (600).

[0041] FIG. 6a illustrates a pigtail-shaped distal tip having a constant radius of curvature (602, 610). FIG. 6b illustrates a pigtail-shaped distal tip having a decreasing radius of curvature (602 and 610), where 602 is greater than 610. The pigtail-shaped distal tip portion has a radius of curvature (602) between about 5 millimeters and about 15 millimeters. In another embodiment, the pigtail-shaped distal tip portion has a radius of curvature (602) between about 7.5 millimeters and about 12.5 millimeters. In a specific embodiment, the pigtail-shaped distal tip portion has a radius of curvature (602) of about 10 millimeters.

[0042] FIG. 6b illustrates a distal tip (600) having various radii of curvature (602, 610). FIG. 6b illustrates an exemplary example of a distal tip (600) in which the radius of curvature (602) decreases from the proximal end (608) to the distal end (606) to produce a radius of curvature (610). In some embodiments, the radius of curvature (610) at the distal end (606) of the distal tip portion (600) is about 10% to about 50% smaller than the radius of curvature (602) at the proximal end (608) of the distal tip portion (600). In another implementation, the radius of curvature (610) at the distal end (606) of the distal tip portion (600) is about 20% to less than the radius of curvature (602) at the proximal end (608) of the distal tip portion (600).

[0043] In a specific implementation, the radius of curvature (610) at the distal end (606) of the distal tip portion (600) is about 30% smaller than the radius of curvature (602) at the proximal end (608) of the distal tip portion (600). In another implementation, the distal tip (600) forms part of an Euler spiral, so that the radius of curvature (602) at a point along the distal tip portion (600) is inversely proportional to the distance of that point along the distal tip portion (600) from the origin.

[0044] FIGS. 7A and 7B illustrate exemplary examples of a J-shaped distal tip (700) having a radius of curvature (702), a lumen (704), a distal end (706), a proximal end (708), a most distal point (710), and an axis (712). FIG. 7A illustrates such a distal tip (700) having a single axial portion, and FIG. 7B illustrates a distal tip (700) having a first axial portion (714) and a second axial portion (716). The lumen (704) extends along the entire length of the distal tip (700). The J-shaped distal tip (700) may have a constant radius of curvature (702). In some embodiments, the radius of curvature (702) may decrease along the length of the distal tip (700). In another implementation, the radius of curvature (702) may increase along the length of the distal tip (700). The j-shaped distal tip (710) is configured such that the line tangent to the most distal point (710) is parallel to the axis (712) along the length of the distal extension.

[0045] The foregoing is merely illustrative of the principles of the present disclosure, and the device may be implemented in aspects other than those described, provided for illustrative purposes rather than as a limitation. It should be understood that while the device disclosed herein is illustrated for use in a pump, it may be applied to other devices, such as other intravascular medical devices. Variations and modifications will occur to those skilled in the art after reviewing the present disclosure. The disclosed features may be implemented in any combination and subcombination (including multiple dependent combinations and subcombinations) together with one or more other features described herein. Various features described or illustrated above, including any components, may be combined or integrated into other systems. Additionally, some functions may be omitted or not implemented.

[0046] Examples of modifications, substitutions, and changes that are identifiable by those skilled in the art may be made without departing from the scope of the information disclosed herein. All references cited herein are incorporated by reference in their entirety and become part of this application.

Claims

Claim 1 A variable stiffness distal extension for a blood pump system, comprising a body formed integrally, wherein the body comprises a distal end, a proximal end, an outer wall extending between the distal end and the proximal end, an inner wall forming a lumen extending between the proximal end and the distal end—the lumen is configured and arranged to accommodate an element extending longitudinally—a proximal portion having a distal end and a proximal end—the proximal portion is configured to be connected to a blood pump system—and a distal portion extending distally from the proximal portion, wherein the outer diameter of the body formed integrally by the outer wall decreases continuously along the distal direction from the proximal end of the proximal portion to the distal end, and the inner lumen has an inner diameter that decreases continuously along the distal direction from the proximal end of the proximal portion to the distal end. Claim 2 In claim 1, the element extending in the longitudinal direction is a variable stiffness distal extension comprising at least one of a guide wire, a guide wire loading lumen, or a stylet. Claim 3 In claim 1, the integrally formed body further comprises a variable stiffness distal extension portion including a distal tip portion extending from a distal portion. Claim 4 In paragraph 3, the outer diameter of the integrally formed body is a continuous variable stiffness distal extension at at least one of the distal portion or the distal tip portion. Claim 5 In claim 1, a variable stiffness distal extension having an inner diameter of about 0.1 millimeters to about 3 millimeters. Claim 6 A variable stiffness distal extension for a blood pump system, wherein the distal extension comprises an integrally formed body having an outer wall extending between a distal end and a proximal end, an outer wall extending between the distal end and the proximal end, and an inner wall forming an inner lumen configured to accommodate an element extending between the distal end and the proximal end and extending longitudinally, wherein the integrally formed body comprises: a proximal portion configured to be connected to a blood pump system and having a first inner diameter along an inner wall and a first outer diameter along an outer wall; and a distal tip portion distal to the proximal portion, wherein the distal tip portion has a second inner diameter along an inner wall and a second outer diameter along an outer wall, wherein the first inner diameter and the first outer diameter each decrease continuously in the distal direction along the proximal portion, the variable stiffness distal extension. Claim 7 In paragraph 6, the element extending in the longitudinal direction is a variable stiffness distal extension that is a guide wire loading lumen. Claim 8 In paragraph 1 or 6, the element extending in the longitudinal direction is a variable stiffness distal extension that is a stylet. Claim 9 A variable stiffness distal extension for a blood pump system, wherein the distal extension comprises a distal end, a proximal end, an outer wall extending between the distal end and the proximal end, and an inner wall forming an inner lumen configured to accommodate an element extending between the distal end and the proximal end and extending longitudinally, and comprises a flexible extended body including a first axial portion, a second axial portion, and a distal tip portion, wherein the second axial portion is distal to the first axial portion and is integrally formed with the first axial portion; and the distal tip portion is distal to the second axial portion and is integrally formed with the second axial portion, wherein the outer diameter of the outer wall decreases continuously along the distal direction from the proximal end of the first axial portion to the distal end, and the inner diameter of the inner lumen decreases continuously along the distal direction from the proximal end of the first axial portion to the distal end. Claim 10 In paragraph 6, the distal extension further comprises a portion distal to the proximal portion and proximal to the distal tip portion, wherein the first outer diameter from the proximal end of the proximal portion to the distal end of the proximal portion continuously decreases, and the second outer diameter of the distal tip portion is constant, a variable stiffness distal extension. Claim 11 In claim 1, the outer diameter of the integrally formed body and the inner diameter of the inner lumen are variable stiffness distal extensions that decrease at different rates along the distal direction from the proximal end of the proximal part to the distal end. Claim 12 In paragraph 6, the first inner diameter and the first outer diameter are variable stiffness distal extensions that decrease at different rates in the distal direction along the proximal portion. Claim 13 In claim 9, the outer diameter of the outer wall and the inner diameter of the inner lumen are variable stiffness distal extensions that decrease at different rates from the proximal end to the distal end of the first axial portion. Claim 14 In claim 9, the outer diameter is a variable stiffness distal extension that decreases continuously from 4 mm at the proximal end of the first axial portion to 2 mm at the distal end of the first axial portion. Claim 15 In paragraph 10, the outer diameter of the distal extension is a constant variable stiffness distal extension between the distal end of the second axial portion and the proximal end of the second axial portion. Claim 16 In paragraph 9, the first axial portion has a first stiffness, the second axial portion has a second stiffness, and the first stiffness is greater than the second stiffness, a variable stiffness distal extension. Claim 17 In paragraph 16, the distal tip portion is a third axial portion, and optionally, the third axial portion is a variable stiffness distal extension that is pigtail shaped. Claim 18 In paragraph 17, the third pigtail-shaped portion has a third stiffness, and the second stiffness is a variable stiffness distal extension greater than the third stiffness. Claim 19 In paragraph 9, the first axial portion extends along the first axis, the second axial portion extends along the second axis, and the second axis is a variable stiffness distal extension that is not parallel to the first axis. Claim 20 In claim 19, a variable stiffness distal extension in which the angle between the first axis and the second axis is 0 degrees to about 55 degrees. Claim 21 In claim 20, a variable stiffness distal extension in which the angle between the first axis and the second axis is approximately 15 to approximately 35 degrees. Claim 22 In claim 20, a variable stiffness distal extension in which the angle between the first axis and the second axis is approximately 30 degrees. Claim 23 In claim 1, 6, or 9, the distal extension is a variable stiffness distal extension formed integrally from a single material. Claim 24 In paragraph 3, 6, or 9, the distal tip portion comprises a pigtail portion, and the material of the pigtail portion comprises at least one polymer, a variable stiffness distal extension. Claim 25 In paragraph 24, one or more polymers comprise at least one of polyurethane, polyamide, and elastomer, and optionally the elastomer comprises a thermoplastic polyurethane, a variable stiffness distal extension. Claim 26 In paragraph 25, the polyamide comprises at least one of PEBAX and nylon, a variable stiffness distal extension. Claim 27 In paragraph 24, the material of the pigtail is a variable stiffness distal extension comprising at least one of an additive, a coloring agent, and a filler. Claim 28 In paragraph 3, 6, or 9, the distal tip portion is a variable stiffness distal extension that is j-shaped or pigtail-shaped. Claim 29 A variable stiffness distal extension in claim 1, wherein the proximal part is the first part, the distal part is the second part, and the distal extension further includes a third part located distal to the second part, and the third part is configured to have a smaller stiffness than the second part. Claim 30 In paragraph 29, the outer diameter of the distal extension decreases distally over the length of the third part, or the outer diameter of the distal extension decreases from the proximal end to the distal end of the third part, or the material of the third part has a smaller curvature modulus than the material of the second part, or the inner diameter of the distal extension is a constant variable stiffness distal extension in the third part. Claim 31 In claim 9, the first axial portion, the second axial portion, and the distal tip portion are each formed in size and shape such that the first axial portion is more rigid than the second axial portion and the second axial portion is more rigid than the third distal tip portion, and optionally the third distal tip portion has less rigidity than the second axial portion, a variable rigidity distal extension portion. Claim 32 A variable stiffness distal extension in which the outer diameter of the distal extension is reduced at the third distal tip portion or the outer diameter of the distal extension is reduced between the distal end and the proximal end of the third distal tip portion. Claim 33 A blood pump system comprising: a catheter; a blood pump; a cannula coupled to a distal end of the blood pump; and a variable stiffness distal extension, wherein the variable stiffness distal extension comprises an integrally formed body, wherein the integrally formed body comprises a distal end, a proximal end, an outer wall extending between the distal end and the proximal end, an inner wall forming a lumen extending between the proximal end and the distal end, a proximal portion having a distal end and a proximal end—the proximal portion being coupled to the distal end of the cannula—, and a distal portion extending distally from the proximal portion, wherein the outer diameter of the integrally formed body formed by the outer wall decreases continuously along the distal direction from the proximal end of the proximal portion to the distal end, and the inner lumen has an inner diameter that decreases continuously along the distal direction from the proximal end of the proximal portion to the distal end. Claim 34 In paragraph 33, the blood pump system is configured to be inserted through the patient's vascular system without a guide wire. Claim 35 In paragraph 33, the variable stiffness distal extension is configured to create a stiffness gradient between the proximal end of the integrally formed body and the distal position of the proximal end of the integrally formed body, and / or the variable stiffness distal tip is configured across the aortic valve in a blood pump system. Claim 36 delete Claim 37 delete Claim 38 delete Claim 39 delete Claim 40 delete Claim 41 delete Claim 42 delete Claim 43 delete Claim 44 delete

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