Variable-stiffness distal extension part for blood pump system

Abstract

To disclose a system and a method for providing a blood pump system having a variable-stiffness distal extension part.SOLUTION: A variable-stiffness distal extension part may have at least one section of continuously varying stiffness, resulting in a stiffness profile that decreases in a distal direction along a length of the distal extension part. The varying stiffness may be accomplished by varying one or more radial dimensions of the extension part. For example, in some implementations, an outer diameter of the distal extension part may decrease along at least a portion of the distal extension part. The distal extension part may include a lumen configured to receive a longitudinally extending element.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Cross - reference to related applications This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62 / 835,636, filed on April 18, 2019, the disclosure of which is incorporated herein by reference.

Background Art

[0002] Background of the invention To deliver blood from the heart to the arteries, a blood pump assembly such as an intracardiac blood pump or an intravascular blood pump may be introduced into the heart. Such mechanical circulatory assist devices are often introduced to assist the heart's function after a patient has had a heart attack. One such class of devices is a set of devices known as the "Impella" heart pump. Some blood pump assemblies can be introduced percutaneously through the vasculature during heart surgery. Specifically, the blood pump assembly can be inserted into the left ventricle across the valve and into the ascending aorta through the femoral artery or the axillary / subclavian artery by a catheter technique. The inserted blood pump assembly can be configured to draw blood from the left ventricle of the heart through a cannula and discharge the blood into the aorta. The blood pump assembly can also be configured to draw blood from the inferior vena cava and discharge the blood into the pulmonary artery. Some mechanical circulatory assist devices are powered by an internal motor, while others are powered by an external motor and a drive cable.

Summary of the Invention

[0003] The inventors understood that the stability of the 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 ventricular apex, heart tissue can be sucked into the pump, leading to problems with arrhythmias, and if the blood pump assembly is placed deep within the ventricle, the outlet may be within the aortic valve or within the ventricle. Further, the operation of the blood pump within the heart or the movement of the myocardium itself can create a flow field that displaces the position of the pump in situ. When the blood pump is displaced from its selected operating position, repositioning of the pump is required, and such repositioning generally requires turning the pump off. Such repositioning consumes valuable time and generally interferes with patient care. In some cases, frequent repositioning of the heart pump within the patient can also damage one or both of the pump and the heart. Therefore, it is highly desirable to reduce potential damage to the patient's heart and vasculature while maintaining and improving pump and flow stability. Distal extensions, particularly non-invasive extensions such as pigtails, can advantageously stabilize the pump within the heart while reducing or minimizing the occurrence of trauma to the vasculature or heart.

[0004] In some cases, it is desirable to have a blood pump system with a distal extension having a lower stiffness than the proximal portion at the distal portion in order to effectively stabilize the blood pump system while avoiding or minimizing trauma to the heart. The more rigid proximal portion can reduce buckling and provide a desired stand-off distance between the pump component (e.g., pump inlet or outlet) and the heart tissue, while the less rigid distal portion can help avoid damage to the heart tissue. Some pumps use a distal extension that includes two sections, each having different stiffness characteristics and the distal section having a lower stiffness characteristic than the proximal section. Such pumps are disclosed, for example, in U.S. Patent No. 9,814,814 and generally exhibit a stepped stiffness profile, with each section of the distal extension having its own stiffness. The change in stiffness is thus abrupt. The mechanical properties of such a distal extension are thus constrained by the number of selected sections and the materials used for these sections.

[0005] The inventors recognized and understood the many advantages associated with distal extensions of heart pump systems or other medical devices that exhibit a continuous stiffness profile. As used herein, a continuous stiffness profile does not have abrupt step changes, but rather has a substantially constant incremental change in stiffness over at least a portion of the length of the distal extension. The resulting profile is more gradient-like than stepped. The gradient of the stiffness profile can be in any functional form, i.e., constant, variable, etc., over a portion of the length of the distal extension. Thus, the stiffness profile can be linear, non-linear, etc. For example, a distal extension having a continuous stiffness profile may be more suitable for a wider range of anatomical dimensions than a distal extension having a stepwise stiffness profile. Further, the distal extensions described herein facilitate retrograde crossing of the aortic valve without the need for a guidewire, for example, to reposition a pump that has inadvertently migrated from the ventricle and / or to facilitate complete “wireless access” (i.e., access without the need for a guidewire) of the pump to the ventricle. In some cases, such wireless access can be achieved by the continuous deflection of the distal extension as the distal extension is advanced against the aortic valve. In particular, the continuous advancement of the distal extension allows the distal extension to deflect and form a loop structure without being captured by the tips of the aortic valve and subsequently escape beyond the valve and into the left ventricle.

[0006] In some aspects, the systems, methods, and apparatuses 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 that creates a continuous stiffness profile where the stiffness varies continuously and decreases over at least a portion of the distal extension along the distal direction. The continuously varying stiffness can be achieved by continuously varying at least one radial dimension of the distal extension. For example, in one implementation, the varying radial dimension can be the outer diameter of the distal extension, and the inner diameter of the distal extension that defines the lumen is held constant. In this implementation, the wall thickness defined by the inner and outer diameters varies with the outer diameter. In an exemplary implementation, the outer diameter of the distal extension decreases along the distal direction while the inner diameter is held constant. In such an implementation, the wall thickness decreases along the distal direction. The continuous stiffness profile can be selected by adjusting the outer diameter of the distal extension, and lower stiffness generally corresponds to a smaller outer diameter. For example, in the implementation described above, the proximal portion of the distal extension with a larger wall thickness can exhibit a higher stiffness, and the stiffness can decrease continuously along at least a portion of the distal extension in the distal direction as the wall thickness decreases.

[0007] According to a first aspect of the present disclosure, a variable stiffness distal extension for a blood pump system includes a monolithic body. The monolithic body further includes 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 a lumen. The lumen is configured to receive a guide wire and can be configured to receive other longitudinally extending elements. For example, an additional element that can be configured to be received by the lumen is a guide wire loading aid that can be pre-assembled within the lumen. In another example, the additional element can be a stylet. The lumen has a constant diameter between the distal end and the proximal end. The monolithic body further includes a proximal portion. The proximal portion of the monolithic 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 includes a distal tip portion. The distal tip portion of the proximal portion has a second inner diameter along the inner wall and a second outer diameter along the outer wall. A first outer diameter defined by the outer wall of the distal extension continuously decreases proximally along the proximal portion in a distal direction towards the second outer diameter.

[0008] The first outer diameter and the second outer diameter can be selected to provide a particular stiffness profile. In some implementations, the first outer diameter at the proximal end of the distal extension is from about 1 millimeter to about 7.5 millimeters. In such implementations, the second outer diameter at the distal end of the distal extension is from about 0.5 millimeter to about 5 millimeters. In other implementations, the first outer diameter at the proximal end of the distal extension is from about 2.5 millimeters to about 5 millimeters. In such implementations, the second outer diameter at the distal end of the distal extension is from about 3 millimeters to about 4 millimeters. In certain implementations, the first outer diameter at the proximal end of the distal extension is from about 3 millimeters to about 4.5 millimeters. In such implementations, the second outer diameter at the distal end of the distal extension is from about 3.5 millimeters to about 4 millimeters. In further implementations, the first outer diameter at the proximal end of the distal extension is about 4 millimeters. In such implementations, the second outer diameter at the distal end of the distal extension is about 3.75 millimeters. Any of the above ranges of the first outer diameter at the proximal end of the distal extension provides a desired change in diameter along the length of the distal extension and can thus be combined with any of the above ranges of the second outer diameter at the distal end of the distal extension to provide the desired thickness and stiffness profile of the distal extension. For example, if the first outer diameter is 9 millimeters at the proximal end, the second outer diameter can be 4 millimeters at the distal end. Additionally, if the first outer diameter is 1 millimeter at the proximal end, the second outer diameter can be 0.6 millimeter at the distal end.

[0009] At least one advantage of tapering the first outer diameter of the proximal portion in the distal direction is that a section of the proximal portion having a larger outer diameter is more rigid than a section having a smaller outer diameter. Thus, the rigidity in such an aspect decreases in the distal direction. The reduction of rigidity in the distal direction is desirable for many reasons, and at least one of the reasons is that a more flexible distal end can help avoid the extension causing damage to the vascular structure when the variable-rigidity distal extension crosses the vascular structure. Similarly, the distal end with reduced rigidity can help avoid the extension causing damage to the patient's heart valve and / or heart chamber (e.g., ventricular wall tissue) when the distal extension is introduced and positioned within the patient's heart.

[0010] Furthermore, according to some aspects, the more rigid proximal portion of the distal extension can help stabilize the pump within the ventricle by maintaining its length at the most proximal portion of the distal extension when the thrust generated by the operation of the pump bends and / or buckles the most distal portion of the distal extension. For example, the more rigid proximal portion can define a desired "stand-off" distance to maintain a desired spacing between the pump component (e.g., the pump inlet) and the ventricular wall or other tissue within the heart.

[0011] In some implementations, the variable-rigidity distal extension can further include a second axial portion distal to the first axial portion. In a further implementation, the variable-rigidity distal extension can further include at least a third axial portion distal to the first and second axial portions. An extension having only two axial portions can include a discrete rigidity profile, while an integrally formed extension having a diameter that decreases in the distal direction can have a relatively continuous and smooth rigidity profile.

[0012] The specific shape of the distal tip portion can be selected to achieve the desired stability of the pump within the heart. The distal tip portion can generally include any curved shape. In some implementations, the variable stiffness distal extension can have a J-shaped distal tip portion. In some implementations, the J-shaped distal tip portion can have a radius of curvature of from about 5 millimeters to about 15 millimeters. In other implementations, the J-shaped distal tip portion can have a radius of curvature of from about 7.5 millimeters to about 12.5 millimeters. In a particular implementation, the J-shaped distal tip portion has a radius of curvature of about 10 millimeters. In further implementations, the variable stiffness distal extension can have a pigtail-shaped distal tip portion. In a particular implementation, the radius of curvature of the pigtail-shaped distal tip portion is constant. In some implementations, the pigtail-shaped distal tip portion can have a radius of curvature of from about 5 millimeters to about 15 millimeters. In other implementations, the pigtail-shaped distal tip portion can have a radius of curvature of from about 7.5 millimeters to about 12.5 millimeters. In a particular implementation, the pigtail-shaped distal tip portion has a radius of curvature of about 10 millimeters. In some implementations, the radius of curvature of the pigtail-shaped distal extension decreases in the distal direction. In some implementations, 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 other implementations, 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 particular implementation, the radius of curvature of the distal end of the distal tip portion is about 30% smaller than the radius of curvature of the proximal end of the distal tip portion. In other implementations, the radius of curvature at a point along the distal extension is inversely proportional to the distance of that point along the distal extension from the origin such 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 portion is that such a shape can help to stabilize the pump within the patient's ventricle.

[0013] In certain embodiments, the variable stiffness distal extension may further include a lumen. In such embodiments, the lumen extends along the entire length of the distal extension. The lumen may also define the inner diameter of the distal extension. The lumen may be sized and shaped to accommodate a guidewire or additional elements other than the guidewire. For example, the additional element may be a guidewire loading aid (e.g., a guidewire loading lumen) or a stylet. In some embodiments, the inner diameter of the distal extension (which may be defined by the lumen) is constant along the entire length of the distal extension. In some embodiments, the inner diameter defined by the lumen may be from about 0.1 millimeter to about 5.5 millimeters. In further embodiments, the inner diameter may be from about 1 millimeter to 3 millimeters. At least one advantage of incorporating a lumen having a constant inner diameter is that it can provide a desired continuous stiffness profile when connected to a distal extension with a continuously varying outer diameter. Additionally, the inner lumen is generally useful as it allows for the introduction of a guidewire 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 defined by the lumen continuously decreases 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 millimeter at the distal end of the first axial portion. In other embodiments, the inner diameter of the distal extension decreases 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. At least one advantage of a lumen having an inner diameter that decreases between the proximal end of the first axial portion and the distal end of the first axial portion is that a desired continuous stiffness profile can be achieved by combining the decreasing inner diameter with a decreasing outer diameter.

[0014] In another aspect, a variable stiffness distal extension for a blood pump system includes a flexible elongate body. The flexible elongate body of the distal extension has a distal end and a proximal end. The flexible elongate body may further include an outer wall. The outer wall is configured to extend between the distal end and the proximal end of the distal extension. The flexible elongate body is further configured with 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 integrally formed with the first axial portion. The distal tip portion is disposed distal to the second axial portion. The distal tip portion is further integrally formed with the second axial portion. The outer diameter of the outer wall of the flexible elongate body is configured to continuously decrease from the proximal end of the distal extension to the distal end of the distal extension. At least one advantage of continuously decreasing the outer diameter of the outer wall is that the stiffness of the sections along the length of the distal extension having a larger outer diameter increases, and the stiffness of the sections having a smaller outer diameter decreases, so that the continuous stiffness profile of the distal extension having an outer diameter decreasing in the distal direction also decreases in the distal direction. As described above, a continuous stiffness profile decreasing in the distal direction can provide many advantages. For example, the flexible distal end may enable a physician to easily introduce the distal extension into the patient's vascular structure without damaging the vascular structure. Further, the relatively stiff proximal end of the distal extension corresponding to the section having a larger outer diameter can help to stabilize the pump within the ventricle by maintaining its length at the most proximal portion of the distal extension when the thrust generated by the operation of the pump bends and / or buckles the most distal portion of the distal extension (e.g., by defining a desired "standoff" distance). Similarly, the relatively stiff proximal end of the distal extension corresponding to the section having a larger outer diameter can help to stabilize the pump within the patient's heart valve and heart cavity.

[0015] In some embodiments, the outer diameter of the distal extension continuously decreases from about 6 millimeters at the proximal end of the first axial portion to about 0.5 millimeter at the distal end of the first axial portion. In other embodiments, the outer diameter of the distal extension continuously decreases 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 and the distal end of the second axial portion. In some embodiments, the first axial portion has a first rigidity. Further, the second axial portion has a second rigidity. In some embodiments, the first rigidity is greater than the second rigidity. As described above, the physician can manipulate the extension through the patient's vasculature because the proximal end of the extension is rigid, while the flexible distal end allows the extension to be advanced through the vasculature without damaging the vasculature.

[0016] In certain embodiments, the distal extension further includes a third pigtail-shaped portion. The third pigtail-shaped portion has a third rigidity. This third rigidity is less than the second rigidity. 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 an angle to each other. In some embodiments, this angle ranges from about 0 degrees to about 50 degrees. In other embodiments, this angle ranges from about 10 degrees to about 40 degrees. In yet other embodiments, the angle between the first axis and the second axis ranges from about 15 degrees 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 can be selected to provide certain structural characteristics of the distal extension. For example, this angle can be selected to enhance the ease with which the physician can manipulate the extension through the patient's vasculature. Also, this angle can be adjusted to maximize the ease with which the pump and the extension cross the aortic valve. Additionally, this angle can be selected to provide the most stable configuration of the blood pumping system within the ventricle.

[0017] In some implementations, the distal extension can be integrally formed from one or more materials. For example, the distal extension can be formed from a single material having various 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 can be formed as a composite structure including two or more materials, and the composition of the two or more materials can vary along the length of the distal extension. In another example, the material of the distal tip section can be selected to have a lower stiffness than the material of the proximal section. In view of the above, it should be understood that by varying the material and / or dimensions of the distal extension, a desired mechanical response, such as a stiffness profile that varies along the length of the distal extension, can be achieved.

[0018] Generally, the material(s) of the distal extension can be selected such that the distal extension has a sufficiently smooth surface to avoid or prevent biological contamination, deposits, and / or adhesion of the distal extension. In this way, the material of the distal extension can help reduce or prevent thrombus formation. In certain implementations, the distal extension includes polyurethane. In other implementations, the distal extension includes polyamide. The polyamide can include PEBAX or nylon. In further implementations, the distal extension can include an elastomeric polymer, i.e., an elastomer. The elastomer can include one or more silicone-based polyurethanes or one or more carbonate-based polyurethanes. One such carbonate-based polyurethane elastomeric polymer is 55D Pellethane®. In another implementation, the elastomer includes a blend of these silicone or carbonate-based polyurethanes with other elastomers, or a compound of these silicone or carbonate-based polyurethanes with other elastomers. The elastomer blends and elastomer compounds can contain such polymers in different ratios. In other implementations, the distal extension can include a blend or compound of the above elastomers in addition to additives, fillers, and colorants. For example, the use of additives, fillers, and colorants can be used to enhance any combination of fluoroscopic visualization, ultrasound visualization, and adjustment of the stiffness of the distal extension. Further, it should be understood that the distal extensions described herein can be formed by any suitable method. For example, the distal extension can be formed by suitable molding and / or extrusion processes.

[0019] In a further implementation form, the outer diameter of the distal extension continuously decreases in the distal direction in the third portion of the distal extension. In some implementation forms, the outer diameter of the distal extension continuously decreases over the entire length of the third portion. In other implementation forms, the outer diameter of the distal extension continuously decreases over the first approximately 10% and approximately 60% of the length of the third portion. In a specific implementation form, the outer diameter of the distal extension continuously decreases over the first approximately 20% and approximately 50% of the length of the third portion. In other implementation forms, the outer diameter of the distal extension continuously decreases over the first approximately 30% and approximately 40% of the length of the third portion. In some implementation forms, the outer diameter of the distal extension continuously decreases over the first approximately 35% of the length of the third portion. In some implementation forms, the outer diameter of the distal extension in the third portion decreases to approximately 55% to approximately 95% of the outer diameter of the distal extension of the first portion. In other implementation forms, the outer diameter of the distal extension in the third portion decreases to approximately 65% to approximately 85% of the outer diameter of the distal extension of the first portion. In a specific implementation form, the outer diameter of the distal extension in the third portion decreases to approximately 75% of the outer diameter of the distal extension of the first portion. In other implementation forms, the second portion includes a material having a first flexural modulus, and the third portion includes a material having a second flexural modulus. In some implementation forms, the first flexural modulus is greater than the second flexural modulus. For example, the first flexural modulus may be approximately 1 to approximately 5 times greater than the second flexural modulus. In another example, the first flexural modulus may be approximately 1.5 to approximately 3.5 times greater than the second flexural modulus. In one example, the first flexural modulus may be approximately 2 times greater than the second flexural modulus. The exact ratio of the flexural modulus of the material of the second portion to the material of the third portion can be selected to provide a relatively smooth stiffness profile along the length of the distal extension and to prevent the transition point between the second portion and the third portion from becoming the center of torsion.

[0020] In certain embodiments, the first axial portion, the second axial portion, and the third distal tip portion are each sized and shaped 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 other embodiments, the third distal tip portion is configured to have a lower stiffness than the second axial portion. In other embodiments, the outer diameter of the distal extension decreases at the third distal tip portion. In certain embodiments, the outer diameter of the distal extension decreases between the proximal end and the distal end of the third distal tip portion. In certain embodiments, the inner diameter of the third portion of the distal extension is constant along the third portion.

[0021] In another aspect, the blood pump system includes a flexible distal extension. The blood pump system includes a catheter and a blood pump. The blood pump has a distal end and a proximal end. The system further includes a cannula coupled to the distal end of the blood pump and a cage disposed distally of the cannula. A variable stiffness distal extension is attached to the cage. The variable stiffness distal extension can be any of the extensions described in this application.

[0022] In some embodiments, the blood pump system is configured to be inserted through a patient's vasculature without a guidewire. In such embodiments, the distal extension can include a partial lumen or can be solid throughout its length. In other embodiments, the blood pump system is configured to be inserted through a patient's vasculature using a guidewire. In such embodiments, the distal extension can include a lumen throughout its entire length. In certain embodiments, the variable stiffness distal tip is configured to create a stiffness gradient between the proximal end of the variable stiffness distal tip and a position distal to the proximal end of the variable stiffness distal tip. In other embodiments, the variable stiffness distal tip of the blood pump system is configured to cross the aortic valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above-mentioned other objects and advantages will become apparent by considering the following detailed description in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like parts throughout.

[0024]

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DETAILED DESCRIPTION OF THE INVENTION

[0025] Detailed description To provide an overall understanding of the systems, methods, and devices disclosed herein, specific exemplary aspects are described. The aspects and features described herein are specifically described in the context of use related to pumps for the heart, but it will be understood that the teachings can be adapted and applied to other pumps and other types of medical devices.

[0026] The systems, methods, and devices described herein provide an integrally formed variable stiffness distal extension for a blood pump system. Generally, the system includes an extension having a proximal portion and a distal tip portion. In such an implementation, the proximal portion may have an outer diameter that is larger 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 progressive decrease in the outer diameter along the length of the distal extension forms a continuous stiffness profile along the length of the distal extension that decreases in the distal direction. The relatively soft distal end of the distal extension formed by such a continuous stiffness profile allows the extension to be introduced into the patient's vasculature without damaging the vascular structure when the extension contacts the wall of the patient's blood vessel, and in some cases, can help facilitate crossing the aortic valve without using the aforementioned guidewire. At the same time, the relatively stiff proximal end of the distal extension formed by such a continuous stiffness profile allows the extension to be easily manipulated through the vascular structure by a physician and, as described above, can help define the desired "standoff" distance when the pump is placed in the ventricle. To establish and maintain a desired continuous stiffness profile along the length of the distal extension, the outer diameter can be adjusted along the length of the distal extension.

[0027] Figure 1 shows an illustrative example of an integrally formed variable stiffness distal extension 100 for a blood pump system including a lumen. The distal extension 100 includes a body 102, a distal end 104, a proximal end 106, an outer wall 108, an inner wall 110, a 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 the blood pump system. The outer wall 108 of the distal extension 100 defines at least a first outer diameter 118 and a second outer diameter 124. The first outer diameter 118 of the proximal end 106 of the body 102 continuously decreases in the distal direction toward the second outer diameter 124 of the distal end 104 of the body 102. The distal tip 126 extends from the distal end of the distal tip portion 120. As will be described later in connection with FIG. 6, in some implementations, the distal tip 126 is configured to be pigtail-shaped. As will be described later in connection with FIG. 7, in other implementations, the distal tip 126 is configured to be "J"-shaped. The distal tip 126 may further include any other curved shape. The distal tip 126 can help to stabilize the pump within the ventricle and can help to avoid the heart tissue being sucked into the pump during operation.

[0028] In some embodiments, the first outer diameter 118 of the proximal end 106 of the distal extension 100 is from about 1 millimeter to about 7.5 millimeters. In such embodiments, the second outer diameter 124 of the distal end 104 of the distal extension 100 is from about 0.5 millimeter to about 5 millimeters. In other embodiments, the first outer diameter 118 of the proximal end 106 of the distal extension 100 is from about 2.5 millimeters to about 5 millimeters. In such embodiments, the second outer diameter 124 of the distal end 104 of the distal extension 100 is from about 3 millimeters to about 4 millimeters. In certain embodiments, the first outer diameter 118 of the proximal end 106 of the distal extension 100 is from about 4 millimeters to about 6 millimeters. In such embodiments, the second outer diameter 124 of the distal end 104 of the distal extension 100 is from about 3 millimeters to about 4 millimeters. In further embodiments, the first outer diameter 118 of the proximal end 106 of the distal extension 100 is about 4 millimeters. In such embodiments, the second outer diameter 124 of the distal end 104 of the distal extension 100 is about 3.75 millimeters. At least one advantage of the decrease in the first outer diameter 118 to the second outer diameter 124 in the distal direction is that the proximal portion 114 of the body 102 having a larger diameter is more rigid than the distal portion 120 of the body 102 having a smaller diameter. Thus, the rigidity of such embodiments decreases in the distal direction. As described above, such a configuration having a continuously variable rigidity profile may enable a physician to more easily guide the extension through a patient's vasculature and do so without damaging the patient's vasculature. The inner wall 110 defines a lumen 112, a first inner diameter 116, and a second inner diameter 122. In some embodiments, including the illustrative example shown in FIG. 1, the first inner diameter 116 and the second inner diameter 122 are equal, i.e., the inner diameter is constant throughout the length of the body 102.

[0029] Alternatively, the first inner diameter 116 can be made larger than the second inner diameter 122 in correspondence with a distal direction decrease of the first inner diameter 116 along the length of the body 102. In some implementations, the first inner diameter 116 defined by the lumen 112 can be from about 0.1 millimeter to about 5.5 millimeters. In further implementations, the first inner diameter 116 can be from about 1 millimeter to 3 millimeters. In some implementations, the second inner diameter 122 defined by the lumen 212 can be from about 0.5 millimeter to about 5.5 millimeters. In further implementations, the second inner diameter 122 can be about 2 millimeters.

[0030] FIG. 2 shows another illustrative example of a monolithic 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 includes a body 202, a distal end 204, a proximal end 206, an outer wall 208, an inner wall 210, a 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 defines a first outer diameter 218 and a second outer diameter 226. The first outer diameter 218 of the proximal end 206 of the body 202 can continuously decrease distally toward the second outer diameter 226 of the distal end 204 of the body 202.

[0031] As described above, the variable stiffness distal extension may further include at least a third axial portion that is distal to the first axial portion 214 and the second axial portion 220. An extension having only two axial portions may include a discrete stiffness profile, while an integrally formed extension having a diameter that decreases distally may have a relatively continuous and smooth stiffness profile. In some implementations, the first axial portion 214 includes a first material, the second axial portion 220 includes a second material, and the third axial portion includes a third material. For example, the second axial portion 220 may include a material having a first flexural modulus, and the third portion may include a material having a second flexural modulus. In some implementations, the first flexural modulus is greater than the second flexural modulus. For example, the first flexural modulus may be about 1 to about 5 times greater than the second flexural modulus. In another example, the first flexural modulus may be about 1.5 to about 3.5 times greater than the second flexural modulus. In one example, the first flexural modulus may be about 2 times greater than the second flexural modulus. The exact ratio of the flexural modulus of the material of the second portion to the material of the third portion can be selected to provide a relatively smooth stiffness profile along the length of the distal extension and to avoid a distinct transition point between the second and third portions from becoming the center of torsion and / or buckling.

[0032] As described above, 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 form decreases in the distal direction. Therefore, there is a possibility that a physician can more easily guide an extension having such a continuously variable longitudinal stiffness profile through a patient's vasculature and can do so without damaging the patient's vasculature. The inner wall 210 defines a lumen 212, a first inner diameter 216, and a second inner diameter 228. In some implementation forms, including the illustrative example shown in FIG. 2, the first inner diameter 216 and the second inner diameter 228 are equal, that is, the inner diameter is constant over the entire length of the main body 202. In some implementation forms, the first inner diameter 216 is larger than the second inner diameter 228 in correspondence with the reduction of the first inner diameter 216 in the distal direction along the length of the main body 202. The first axial portion 214 defines a first axis 230. The second axial portion 220 defines a second axis 232. The first axis 230 and the second axis 232 are offset from each other by an angle 222. In some implementation forms, the first axis 230 and the second axis 232 are oriented at an angle 222 of about 0 degrees to about 50 degrees with respect to each other. In other implementation forms, the angle 222 is in the range of about 10 degrees to about 40 degrees. In still other implementation forms, 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 a particular implementation form, the angle 222 between the first axis 230 and the second axis 232 is about 30 degrees. At least one advantage of offsetting the first axial portion 214 from the second axial portion 220 by the angle 222 is that the angle 222 can enable a physician to more easily manipulate the pump through a patient's vasculature and across the aortic valve.

[0033] FIG. 3 shows an exemplary cross-section 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 such an implementation, the stiffness of the distal extension decreases in the distal direction. One advantage of such a configuration is that the rates of decrease of the outer diameter 302 and increase of the inner diameter 304 can be selected to finely tune a continuous stiffness profile along the length of the distal extension.

[0034] FIG. 4 shows an exemplary cross-section 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 towards the distal end 406. This configuration provides the distal extension with a continuous stiffness profile that decreases in the distal direction. Such a continuous stiffness profile can allow the extension to be easily maneuvered through a patient's vasculature while also avoiding damaging the vasculature when the extension is introduced into the patient.

[0035] FIG. 5 shows an exemplary cross-section 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. Both the variable outer diameter 502 and the variable inner diameter 504 are configured to decrease in the direction from the proximal end 510 to the distal end 508. FIGS. 5A, 5B, and 5C show illustrative examples of the reduction rates of the outer diameter 502 and the inner diameter 504. The relative reduction rates of the outer diameter 502 and the inner diameter 504 control the variability of the thickness 506. 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 such that the thickness 506 is also variable. FIG. 5B shows an inner diameter 504 that decreases at a greater rate than the outer diameter 502. Thus, the thickness 506 increases in the distal direction. FIG. 5C shows an outer diameter 502 that decreases at a greater rate than the inner diameter 504 such that the thickness 506 decreases in the distal direction. The stiffness of the illustrative example shown in FIG. 5C decreases in the distal direction.

[0036] Figures 6A-6B show illustrative examples of a pigtail-shaped distal tip 600. FIG. 6A shows a pigtail-shaped distal tip 600 having a constant radius of curvature, and FIG. 6B shows a pigtail-shaped distal tip having a variable radius of curvature. The pigtail-shaped distal tip 600 generally has radii of curvature 602 and 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 can be configured to be constant or variable along the length of the distal tip 600. FIG. 6A shows such a pigtail-shaped distal tip having constant radii of curvature 602 and 610. FIG. 6B shows a pigtail-shaped distal tip having decreasing radii of curvature 602 and 610 where 602 is greater than 610. In some implementations, the pigtail-shaped distal tip portion has a radius of curvature 602 of about 5 millimeters to about 15 millimeters. In other implementations, the pigtail-shaped distal tip portion has a radius of curvature 602 of about 7.5 millimeters to about 12.5 millimeters. In a particular implementation, the pigtail-shaped distal tip portion has a radius of curvature 602 of about 10 millimeters. FIG. 6B shows a distal tip 600 having variable radii of curvature 602 and 610. Specifically, FIG. 6B shows an illustrative example of a distal tip 600 where the radius of curvature 602 decreases from the proximal end 608 to the distal end 606 to result in a radius of curvature 610. In some implementations, the radius of curvature 610 of the distal end 606 of the distal tip portion 600 is about 10% to about 50% smaller than the radius of curvature 602 of the proximal end 608 of the distal tip portion 600. In other implementations, the radius of curvature 610 of the distal end 606 of the distal tip portion 600 is about 20% to about 40% smaller than the radius of curvature 602 of the proximal end 608 of the distal tip portion 600. In a particular implementation, the radius of curvature 610 of the distal end 606 of the distal tip portion 600 is about 30% smaller than the radius of curvature 602 of the proximal end 608 of the distal tip portion 600. In other implementations, the distal tip 600 forms part of an Euler spiral such 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.

[0037] Figures 7A-7B illustrate an exemplary J-shaped distal tip 700 having a radius of curvature 702, a lumen 704, a distal end 706, a proximal end 708, a distal most point 710, and an axis 712. FIG. 7A shows such a distal tip 700 having a single axial portion, and FIG. 7B shows such 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 implementations, the radius of curvature 702 may decrease along the length of the distal tip 700. In other implementations, the radius of curvature 702 may increase along the length of the distal tip 700. The J-shaped distal tip 700 is configured such that the tangent to the distal most point 710 is parallel to the axis 712 along the length of the distal extension.

[0038] The foregoing are merely examples of the principles of the present disclosure, and the apparatus may be implemented by aspects other than those described for purposes of illustration and not limitation. Although the apparatus disclosed herein is shown for use in a pump, it should be understood that it may be applied to other devices such as other intravascular medical devices. After considering the present disclosure, those skilled in the art will envision variations and modifications. The features of the disclosure may be implemented in any combination and sub-combination (including multiple dependent combinations and partial combinations) with one or more other features described herein. The various features described or illustrated above may be combined or integrated in other systems, including any of their components. Further, certain features may be omitted or not implemented.

[0039] Examples of changes, substitutions, and modifications can be verified by those skilled in the art and made without departing from the scope of the information disclosed herein. All references cited herein are hereby incorporated by reference in their entirety and form a part of this application.

Claims

1. a distal end, a proximal end, an outer wall extending between the distal end and the proximal end, an inner wall extending between the distal end and the proximal end and defining a lumen configured to receive an element extending in a longitudinal direction, a proximal portion configured to be connected to a blood pump system, a distal portion extending distally from the proximal portion comprising an integrally formed body comprising wherein an outer diameter of the integrally formed body defined by the outer wall continuously decreases along at least a portion of the proximal portion along a distal direction, and the lumen has a constant inner diameter between the proximal end and the distal end, a variable stiffness distal extension for a blood pump system.

2. The variable stiffness distal extension according to claim 1, wherein the element extending in the longitudinal direction comprises at least one of a guide wire, a guide wire loading lumen, or a stylet.

3. The variable stiffness distal extension according to claim 1, wherein the integrally formed body further comprises a distal tip portion extending from the distal portion.

4. The variable stiffness distal extension according to claim 3, wherein the outer diameter of the integrally formed body is constant in at least one of the distal portion or the distal tip portion.

5. The variable stiffness distal extension according to claim 1, wherein the inner diameter is from about 0.1 millimeter to about 3 millimeters.

6. a distal end and a proximal end, an outer wall extending between the distal end and the proximal end, an inner wall extending between the distal end and the proximal end and forming a lumen configured to receive an element extending in a longitudinal direction having a proximal portion configured to be connected to a blood pump system and having a first inner diameter along the inner wall and a first outer diameter along the outer wall, a distal tip portion distal to the proximal portion and having a second inner diameter along the inner wall and a second outer diameter along the outer wall further comprising an integrally formed body comprising wherein the first outer diameter continuously decreases along the proximal portion in a distal direction, and the lumen has a constant diameter between the distal end and the proximal end, a variable stiffness distal extension for a blood pump system.

7. The variable stiffness distal extension according to claim 6, wherein the element extending in the longitudinal direction is a guide wire loading lumen.

8. The variable stiffness distal extension according to claim 1 or 6, wherein the element extending in the longitudinal direction is a stylet.

9. a distal end and a proximal end, An outer wall extending between the distal end and the proximal end and having is further composed of 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, the distal tip portion is distal to the second axial portion and is integrally formed with the second axial portion, the outer diameter of the outer wall continuously decreases from the proximal end to the distal end, a flexible and elongated body including a variable stiffness distal extension for a blood pump system.

10. A portion that is distal to the proximal portion and proximal to the distal tip portion is further included, the first outer diameter continuously decreases from the proximal end to the distal end of the proximal portion, and the second outer diameter of the distal tip portion is constant, The variable stiffness distal extension according to claim 6.

11. A lumen that extends over the entire length of the variable stiffness distal extension and defines the inner diameter of the distal extension including a variable stiffness distal extension according to any one of claims 1, 6, or 9.

12. The variable stiffness distal extension according to claim 11, wherein the inner diameter of the distal extension is sized and shaped to accommodate an element through the lumen.

13. The variable stiffness distal extension according to claim 1, wherein the inner diameter of the distal extension is from about 0.1 millimeter to about 3 millimeters.

14. The variable stiffness distal extension according to claim 9, wherein the inner diameter of the distal extension continuously decreases between the proximal end and the distal end of the first axial portion.

15. The variable stiffness distal extension according to claim 9, wherein the outer diameter continuously decreases from 4 mm at the proximal end of the first axial portion to 2 mm at the distal end of the first axial portion.

16. The variable stiffness distal extension according to claim 10, wherein the outer diameter of the distal extension is constant between the proximal end and the distal end of the second axial portion.

17. The variable stiffness distal extension according to claim 9, wherein 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.

18. The variable stiffness distal extension according to claim 17, wherein the distal tip portion is a third axial portion.

19. The variable stiffness distal extension according to claim 18, wherein the third axial portion is in a pigtail shape.

20. The variable stiffness distal extension according to claim 19, wherein the third pigtail-shaped portion has a third stiffness and the second stiffness is greater than the third stiffness.

21. The variable stiffness distal extension according to claim 9, wherein the first axial portion has a first axis, the second axial portion has a second axis, and the second axis is not parallel to the first axis.

22. The variable stiffness distal extension according to claim 21, wherein the angle between the first axis and the second axis is about 0 to 50 degrees.

23. The variable stiffness distal extension according to claim 22, wherein the angle between the first axis and the second axis is about 15 to 35 degrees.

24. The variable stiffness distal extension according to claim 22, wherein the angle between the first axis and the second axis is about 30 degrees.

25. The variable stiffness distal extension according to any one of claims 1, 6, or 9, which is integrally formed from a single material.

26. The variable stiffness distal extension according to any one of claims 3, 6, or 9, further comprising a pigtail portion wherein the material of the pigtail comprises at least one polymer.

27. The variable stiffness distal extension according to claim 26, wherein the at least one polymer comprises at least one of polyurethane, polyamide, and elastomer.

28. The variable stiffness distal extension according to claim 27, wherein the polyamide comprises at least one of PEBAX and nylon.

29. The variable stiffness distal extension according to claim 27, wherein the elastomer comprises thermoplastic polyurethane.

30. The variable stiffness distal extension according to claim 26, wherein the material of the pigtail further comprises at least one of an additive, a colorant, and a filler.

31. The variable stiffness distal extension according to any one of claims 3, 6, 9, wherein the distal tip portion is J-shaped or pigtail-shaped.

32. The proximal portion is a first portion, the distal portion is a second portion, and a third portion distal to the second portion, which is configured to have a lower stiffness than the second portion. further comprising the variable stiffness distal extension according to claim 1.

33. The variable stiffness distal extension according to claim 32, wherein the outer diameter of the distal extension decreases in the distal direction over the length of the third portion.

34. The variable stiffness distal extension according to claim 32, wherein the outer diameter of the distal extension decreases between the proximal end and the distal end of the third portion.

35. The variable stiffness distal extension according to claim 32, wherein the material of the third portion has a lower flexural modulus than the material of the second portion.

36. The variable stiffness distal extension according to claim 32, wherein the inner diameter of the distal extension is constant in the third portion.

37. The variable stiffness distal extension according to claim 9, wherein the first axial portion, the second axial portion, and the distal tip portion are each sized and shaped 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.

38. The variable stiffness distal extension according to claim 37, wherein the third distal tip portion is configured to have a lower stiffness than the second axial portion.

39. The variable stiffness distal extension according to claim 37, wherein the outer diameter of the distal extension decreases at the third distal tip portion.

40. The variable stiffness distal extension according to claim 38, wherein the outer diameter of the distal extension decreases between the proximal end and the distal end of the third distal tip portion.

41. A catheter, A blood pump, A cannula connected to the distal end of the blood pump, And a variable stiffness distal tip attached to a cage distal to the cannula A blood pump system comprising.

42. The blood pump system according to claim 41, configured to be inserted through a patient's vasculature without a guidewire.

43. The blood pump system according to claim 41, wherein the variable stiffness distal tip is configured to create a stiffness gradient between the proximal end of the variable stiffness distal tip and a position distal to the proximal end of the variable stiffness distal tip.

44. The blood pump system according to claim 41, wherein the variable stiffness distal tip is configured to cross the aortic valve.

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