Impeller housing for cardiac support system

Abstract

The disclosure relates to an axial flow heart pump for medical support of a patient. The heart pump can have an impeller housed in an impeller housing. The impeller can have a radius ri and can be configured to rotate about a longitudinal axis. The impeller housing can have an outer radius rh about the longitudinal axis. The impeller housing can have a plurality of longitudinal struts spaced circumferentially to define a plurality of outlet openings. Each of the plurality openings can have an opening arc width less than or equal to a maximum opening arc width wo. Each of the plurality of longitudinal struts can have a width greater than or equal to a minimum width ws. The maximum opening arc width wo can be small enough to prevent a straight object outside of the impeller housing from contacting the impeller.

Description

KARDN.174WO PATENTIMPELLER HOUSING FOR CARDIAC SUPPORT SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No.63 / 738,114, filed December 23, 2024, titled IMPELLER HOUSING FOR CARDIAC SUPPORT SYSTEM, which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] The technology relates generally to components of a cardiac support system including an impeller housing.BACKGROUND

[0003] Cardiogenic shock (CS) is a common cause of mortality, and management remains challenging despite advances in therapeutic options. CS is caused by severe impairment of myocardial performance that results in diminished cardiac output, end-organ hypoperfusion, and hypoxia. Clinically this presents as hypotension refractory to volume resuscitation with features of end-organ hypoperfusion requiring immediate pharmacological or mechanical intervention. Acute myocardial infarction (MI) accounts for over about 80% of patients in CS.

[0004] Miniature, catheter-based intracardiac pumps have been developed for percutaneous insertion into a patient's body as an acute therapy for CS patients. They generally include an elongate body carried on the distal end of a catheter. The pump has a blood intake port configured for positioning in the left ventricle, spaced apart from a blood exit port configured for delivering blood into the ascending aorta. The pump includes a drive portion and a pump portion, which may be positioned within the elongate body of the pump.

[0005] Although current generation pumps have achieved a level of clinical adoption, a variety of areas for improvement remain. These may include adjustments to the sizing and orientation of impeller housing outlet windows of the pumps. Conventional systems often include an impeller housing that has outlet windows where the secants of longitudinal struts defining the outlet windows overlap with a tangent of the impeller. This creates a risk that an object external to the pump laying across the struts may contact the impeller. External objects may includeguidewires or other catheters placed near the pump or even patient tissue. Such interactions can compromise device performance and patient safety, highlighting the need for improved structural configurations that decrease interference while maintaining efficient blood flow.SUMMARY

[0006] The embodiments disclosed herein each have several aspects no single one of which is solely responsible for the disclosure’s desirable attributes. Without limiting the scope of this disclosure, its more prominent features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of the embodiments described herein provide advantages over existing systems, devices and methods for mechanical circulatory support systems.

[0007] The following disclosure describes non-limiting examples of some embodiments. For instance, other embodiments of the disclosed systems and methods may or may not include the features described herein. Moreover, disclosed advantages and benefits can apply only to certain embodiments and should not be used to limit the disclosure.

[0008] An axial flow heart pump is provided. The heart pump can include an impeller housing and an impeller positioned inside the impeller housing. The impeller can be configured to rotate about a longitudinal axis. The impeller can have an impeller radius, n. The impeller housing can have an outer radius. Th, about the longitudinal axis, and a plurality of longitudinal struts spaced circumferentially to define a plurality of outlet openings. Each of the plurality of outlet openings can have an opening arc width less than or equal to a maximum opening arc width w0. Each of the plurality of longitudinal struts can have a width greater than or equal to a minimum width ws. The maximum opening arch width wocan be small enough to prevent a straight object outside of the impeller housing from contacting the impeller.

[0009] In some embodiments of the present disclosure, a secant between adjacent longitudinal struts of the plurality of longitudinal struts can have a radial distance from a center of the impeller that is greater than or equal to the impeller radius n.

[0010] In some embodiments of the present disclosure, the maximum opening arc width Wo can be less than or equal to (2cos-1(x)ri / rh) / (360*2pi*rh).

[0011] In some embodiments of the present disclosure, the impeller radius, the impeller outer radius and the maximum opening arc width can be 2.75 mm, 3.10 mm and 2.975 mm respectively.

[0012] In some embodiments of the present disclosure, the plurality of outlet openings can comprise of six outlet openings.

[0013] In some embodiments of the present disclosure, the longitudinal struts can have a minimum width of 0.6 mm.

[0014] In some embodiments of the present disclosure, at least one longitudinal strut can have an electrical conductor disposed longitudinally thereon.

[0015] In some embodiments of the present disclosure, the impeller housing can be bilaterally symmetrical.

[0016] In some embodiments of the present disclosure, the plurality of outlet openings can comprise an even number of outlet openings.

[0017] In some embodiments of the present disclosure, at least one longitudinal strut can comprise an electrical conductor and can have a minimum width of 0.9 mm.

[0018] In some embodiments of the present disclosure, the impeller housing can comprise a plurality of circumferential struts such that each circumferential strut of the plurality of circumferential struts can connect adjacent longitudinal struts of the plurality of longitudinal struts.

[0019] In some embodiments of the present disclosure, the plurality of circumferential struts can be configured to resist bending of the impeller housing.

[0020] In some embodiments of the present disclosure, the plurality of circumferential struts can be configured to resist deformation of the plurality of longitudinal struts.

[0021] In some embodiments of the present disclosure, the plurality of circumferential struts can be aligned with the circumference of the impeller housing.

[0022] In some embodiments of the present disclosure, the plurality of circumferential struts can comprise a rounded, chamfered, or tapered leading edge.

[0023] In some embodiments of the present disclosure, the plurality of circumferential struts can have a width of 0.6 mm.

[0024] In some embodiments of the present disclosure, the plurality of circumferential struts can be configured to reduce the axial length of the plurality of outlet openings.

[0025] In some embodiments of the present disclosure, the pump can include an inlet portion having an inlet positioned distally from the impeller housing.

[0026] In some embodiments of the present disclosure, the pump can include a connection section that can be configured to couple the impeller housing and the inlet portion.

[0027] In some embodiments of the present disclosure, the pump can include a motor housing positioned proximally to the impeller housing.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings. In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the drawing, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.

[0029] FIG. 1 is a perspective view of a miniature catheter based intracardiac pump in accordance with the present disclosure.

[0030] FIG. 2 is a perspective view of an example impeller housing with three longitudinal struts in accordance with the present disclosure.

[0031] FIG. 3 is a perspective view of an embodiment of an impeller housing in accordance with the present disclosure.

[0032] FIG. 4 is a side view of an embodiment of an impeller housing in accordance with the present disclosure with an impeller positioned inside the impeller housing.

[0033] FIG. 5 is a side view of a portion of the impeller housing of FIG. 3 taken about the longitudinal axis 140.

[0034] FIG. 6 is a cross-sectional view of an embodiment of an impeller housing in accordance with the present disclosure.

[0035] FIG. 7 is a side view of an embodiment of an impeller housing in accordance with the present disclosure illustrating contact with external objects of different sizes.

[0036] FIG. 8 is a side view of an embodiment of an impeller housing in accordance with the present disclosure installed within a pump.

[0037] FIG. 9 is a perspective view of an embodiment of an impeller housing in accordance with the present disclosure with an impeller positioned inside the impeller housing.DETAILED DESCRIPTION

[0038] Generally described, embodiments of the present disclosure provide miniature catheter-based intracardiac pumps providing enhanced characteristics relative to existing pumps. Pumps disclosed herein may include an impeller which is an object configured to rotate with a high angular velocity that may aid in the transmission of blood in the vasculature of, for example, a heart. The impeller may be contained inside an impeller housing which can house the impeller within the pumps disclosed herein. Pumps disclosed herein may have impeller housings that have outlet windows which are geometrically configured for efficient performance.

[0039] Benefits of embodiments of pumps herein may include reducing the risk of objects external to the pump contacting the impeller while the impeller is rotating while also providing sufficient strength to resist bending. For example, a pump in accordance with the present disclosure may include an impeller housing with outlet windows defined by a plurality of longitudinal struts that are sized such that an object laying across the longitudinal struts does not enter the inside of the housing or contact the impeller. External objects that could contact the impeller during the operation of a traditional pump can include guidewires, other catheters near the pump or even patient tissue. Additional benefits of embodiments of pumps described herein may further include reducing the hemolysis damage potential and increasing the blood flow through the pump as a result of a higher pressure difference and torque with the same flow and RPM. Further, embodiments of the pumps described herein may allow for mounting of electrical conductors (e.g.. in the form of a flex printed circuit board (PCB) or other electrical conductorstructure) to one of the struts while maintaining bilateral symmetry to reduce asymmetric hydraulic effects on the impeller which may cause vibration. Edges of windows and circumferential struts may be rounded, chamfered, and / or tapered to reduce hemolysis. Bilateral symmetry and window edge treatments may further reduce vibration while maintaining efficient flow paths. Thus, the present disclosure provides pumps capable of preventing interference with the impeller from external objects while also improving efficiency without added complexity.

[0040] A minimally invasive miniaturized percutaneous mechanical left ventricular support system is provided, configured for treatment of patients experiencing cardiogenic shock. The system can include a low profile (e.g., 18 French to 19 French) mechanical circulatory support (MCS) device which includes an axial rotary pump and an elongate inlet tube, carried by the distal end of a nine French catheter. The system can be positioned to span the MCS device across the aortic valve into the left ventricle, where it actively unloads the left ventricle by pumping blood from the left ventricle into the ascending aorta and systemic circulation, and may provide flow rates of up to about 6 L per minute at 60 mmHg. In some embodiments, flow rates between 0.6 L per minute and 6 L per minute may be provided.

[0041] The MCS system may be a temporary (e.g., generally no more than about 6 days) support system for enhancing cardiac output in cardiogenic shock patients such as caused by a myocardial infarction (e.g., Acute ST-elevation myocardial infarction which is a heart attack in an ST segment which encompasses the region between the end of ventricular depolarization and the beginning of ventricular repolarization on an electrocardiogram (ECG)). A pump of the system is placed across the aortic valve typically via transvascular access and pumps blood from the left ventricle to the ascending aorta. The MCS device of the present disclosure may be similar to the MCS device disclosed in U.S. Patent Application No. 17 / 455662, titled PURGELESS MECHANICAL CIRCULATORY SUPPORT SYSTEM WITH MAGNETIC DRIVE filed on November 18, 2021, the entire contents of which is incorporated by reference herein in its entirety for all purposes and forms a part of this specification.

[0042] Referring to FIG. 1, there is illustrated an example pump 101 in accordance with the present disclosure. The pump 101 includes an impeller housing 100 of the present disclosure (which will be described in greater detail herein). The impeller housing 100 is configured to house an impeller 103 (see FIG. 4) within the pump 101. The impeller 103 insidethe impeller housing 100 may be configured to rotate at a high angular velocity to pump blood, for example, from the left ventricle to the ascending aorta.

[0043] The pump 101 has a connection section 120 positioned distally from the impeller housing 100 and a motor housing 115 positioned proximally from the impeller housing 100. The connection section 120 can connect the impeller housing 100 to other components of the pump 101 such as an inlet portion 105 and a nose or tip 107 of the pump 101. The motor housing 115 can at least partially house a motor that can drive the impeller 103 positioned inside the impeller housing 100. In various embodiments, the motor can drive the impeller by driving a drive magnet positioned in the motor housing 115 that is magnetically coupled to the impeller 103, or the motor can be mechanically coupled to the impeller 103 by a shaft.

[0044] FIG. 2 shows an example impeller housing 200. The example impeller housing 200 of FIG. 2 has outlet windows 128 defined by three struts 138, 139. In the example configuration of FIG. 2, the struts 138, 139 are positioned 120 degrees apart and include two struts 139 having a width of 0.6 mm and one strut 138 having an increased width of 0.9 mm to accommodate a Flex PCB 180. The impeller housing 200 of FIG. 2 has outlet windows 128 large enough that the secants 269 of axial struts 138, 139 (e.g., straight lines between the edges of two adjacent axial struts 138, 139) may overlap with an impeller tangent 270 (e.g., the outer tangent of an impeller disposed within the impeller housing). Such overlap creates a risk of an object external to the pump laying across the struts 138, 139 contacting the impeller 103 during operation. External objects may include guidewires or other catheters placed near the pump, other external structures, or even patient tissue.

[0045] FIG. 3 shows an embodiment of an impeller housing 100 in accordance with the present disclosure. The impeller housing 100 extends along a longitudinal axis 140 and includes an impeller cage portion defined by a plurality of longitudinal struts 138, 139 and one or more circumferential struts 271. The impeller housing 100 can have longitudinal struts 138. 139 which are parallel with the longitudinal axis 140 of the impeller housing 100. Longitudinal struts 138, 139 that are parallel with the longitudinal axis 140 of the impeller housing 100 may be beneficial for an easier placement of a circuit element PCB 180 (see FIG. 8) on one of the struts 138 compared to angled struts. The positioning of the longitudinal struts 138, 139 can define outlet windows 128 in the impeller housing 100 with an outlet window length 261 that may be determined by the whole assembly of the impeller unit (see FIG. 4). The impeller housing 100 can have radialbearing struts 262 which may help hold the impeller 103 and journal bearing collar 264 (see FIG.9). The impeller housing can have circumferential struts 271 which may improve mechanical integrity of the impeller housing 100 by resisting bending of the impeller housing 100 and / or by resisting deformation of the struts 138, 139. In some embodiments (see FIG. 4), circumferential struts 271 are axially located near the magnet container 281 (e.g., between flow channels 284 and gap 282) to reduce flow disruption and shorten axial window length, thereby reducing the longitudinal curving radius an external object would need to penetrate to reach the impeller.

[0046] Due to manufacturability requirements (e.g., machining of metal such as titanium), the width of the longitudinal struts 138, 139 and circumferential struts 271 or similar structural bearings may be limited to a minimum of 0.6 mm. In some embodiments, a Flex PCB 180 (FIG. 8) may be positioned over a conductor mounting strut 138 of the impeller housing 100. This may lead to the requirement that one of the struts, the conductor mounting strut 138, have a width of 0.9 mm. This can be derived from the width of the Flex PCB 180 of 0.7 mm and additionally a protective coating of the Flex PCB 180 of 0.1 mm on each side. To avoid asymmetrical radial forces acting on the impeller 103 which may cause vibration, the outlet windows 128 can be symmetrical (e.g., bilaterally symmetrical, radially symmetrical). Alternatively, a pump 101 that does not have electrical conductors 180 positioned on the impeller housing strut 138 may have all struts 138, 139, 271 having equal widths (e.g., 0.6 mm) and may meet other design inputs to prevent interference by external parts. In some embodiments, two struts 138 are ~0.9 mm wide (one carrying conductors and the other radially opposite to preserve bilateral symmetry), with remaining struts 139 at -0.6 mm.

[0047] FIG. 4 shows an embodiment of the impeller housing 100 with an impeller 103 positioned inside the impeller housing 100. The impeller 103 can have blades 280 mounted to a hub 283 and a magnet container 281 proximal of the blades 280 used to magnetically couple the impeller 103 to a drive magnet driven by a motor in the motor housing 115. Alternatively, the impeller 103 may be mechanically coupled to the motor by a shaft. The length 261 of the outlet windows 128 may be chosen to provide sufficient flow of blood out of the windows and permit blood to flow into a gap 282 between the magnet container 281 where the blood flow is guided past bearing components out of flow channels 284 to cool the bearing. The position and the length 261 of the outlet windows 128 relative to the impeller 103 can permit the outlet windows 128 to overlap with a proximal portion of the impeller blades 280, the flow channels 284, and the gap282. For example, the total outlet window length 261 may be in a range of 8 to 11 mm (e.g., in a range of 9 to 10 mm, about 9.5 mm, etc.).

[0048] FIG. 5 shows a side view of a portion of the impeller housing 100 of FIG. 3 taken about the longitudinal axis 140 in FIG. 3. The figure highlights the outlet windows 128 as defined by the longitudinal struts 138, 139 and circumferential struts 271 as well as highlight the outlet window length 261 of the particular embodiment of the impeller housing 100.

[0049] Referencing FIG. 6 and FIG. 7, embodiments of the present disclosure may advantageously prevent external objects from contacting the impeller 103. To reduce risk of external objects from entering the outlet windows 128 and contacting the impeller 103, the dimensions of the outlet windows can be selected such that a secant 269 across the outer edges of the outlet windows 128 does not pass radially inward of a tangent 270 of the impeller blades 103. For example, in the embodiment depicted in FIGS. 6 and 7, the secant 269 and the tangent 270 are located at the same radial distance outward from the center of the impeller 103. Accordingly, a straight object contacting the two opposing edges of the outlet windows 128 may incidentally contact the impeller 103 but will be prevented from extending into the rotation envelope of the impeller 103, thereby preventing damage to the impeller 103.

[0050] The window width 255, and consequently the opening angle 266, can influence the interference of an external object through an outlet window 128 into the impeller 103 and can be dependent on the diameter of the impeller 267 (e.g., 5.50 mm) and the outer diameter of the impeller housing 268 (e.g., 6.20 mm). The cosine of Vi of the maximum opening angle 266 can be calculated as the radius of the impeller 103 divided by the outer radius of the impeller housing 100 or longitudinal struts 138. 139. For example, if the impeller 103 has a radius of 2.75 mm and the impeller housing 100 has an outer radius of 3.1 mm, the maximum opening angle may be 54.98 degrees.

[0051] The maximum outlet window arc width 255 may be equal to the maximum opening angle 266 divided by 360 degrees multiplied by the outer circumference of the impeller housing, which in the aforementioned example equals 2.975 mm:A. QR°Window width = —:— ■ 2 ■ it ■ 3.1 mm = 2.975 mm360°

[0052] Based on the maximum opening angle 266 and / or maximum outlet window arc width 255 and minimum outlet window strut width 260 and with a requirement of bilateralsymmetry, the quantity of outlet windows 128 or outlet window struts 138, 139 and the width of the struts 260 may be determinedTable 1: Number of Outlet Windows Based on Strut Width, Window Width and Opening Angle

[0053] For example, to ascertain the quantity of outlet windows 128, Table 1 shows calculations of opening angles 266, outlet window arc widths 255, and struts widths 260 for the embodiment where the impeller diameter is 5.50 mm and the impeller housing has an outer diameter of 6.20 mm, for a variety of outlet window 128 quantities (e.g., 3 to 7 outlet windows).

[0054] In embodiments that do not include a strut 138 to position electrical conductors (e.g., conductor 180 of FIG. 8), which may need at least one or two struts 138 having a minimum width of 0.9 mm, the option of six outlet windows 128 may be appropriate. With six outlet windows 128, the opening angle 266 may be smaller than the maximum opening angle 266. With six outlet windows 128, the window width 255 may be smaller than the maximum window width 255. With six outlet windows 128, the strut width 260 may be greater than the minimum strut width 260 that permits manufacturability. Where conductor-bearing struts are present, one or two struts may be widened to ~0.9 mm and positioned radially opposite to preserve bilateral symmetry, with remaining struts at -0.6 mm.

[0055] Furthermore, the total window area may be increased by selecting a number of outlet windows 128 which would have window widths 255 closest to but not surpassing the maximum window width 255 in order to increase blood flow. For example, in this embodiment, selecting six windows 128 may be better than choosing seven windows 128 because six windows 128 provide a greater total window area (e.g., 6 windows * 2.60 mm = 15.6 mm compared to 7 windows * 2.22 mm = 15.54 mm). However, it may be desirable not to increase the window areabeyond the combined area of the six windows 128 because selecting five windows 128 would cause the windows 128 to have an opening angle 266 greater than the maximum opening angle 266. Alternatively, for embodiments wherein the impeller diameter 267 and / or impeller housing diameter 268 are different than this first embodiment, potentially a different quantity of windows 128 may be suitable.

[0056] In some embodiments, where it may be desired to have at least one or at least two struts 138 have a minimum width of 0.9 mm so as to be wide enough to mount a 0.7 mm wide Flex PCB (e.g., electrical conductor 180 of FIG. 8), it can be seen that an arrangement with six windows 128 and six struts 138, 139 with identical widths may not be possible, because either the window width 255 is too big (e.g., three to five windows 128 have windows with widths 255 larger than a maximum allowed window width) and / or the strut width 260 is too little (five to seven windows 128 have struts widths 255 smaller than a minimum required strut width). Therefore, a different arrangement may be desirable.

[0057] Optionally, in some embodiments, all struts 138, 139 may have equal widths 260. In alternative embodiments, as shown in FIG. 8, one strut 138 may be wider than the others to provide space to attach electrical conductors 180, e.g., a Flex PCB, that connects to sensor(s) on the pump. Retainment features (e.g., shallow grooves or micro-textures) and biocompatible adhesives may be used for bonding, with strain relief at transitions to mitigate cyclic loading.

[0058] In further alternative embodiments, two struts 138 may be wider (e.g.. ~0.9 mm wide) than the remaining struts 139 (e.g., 0.6 mm wide). A first wide strut 138 may cany electrical conductors 180. A second wide strut 138 may be positioned radially opposite the first wide strut 138 to maintain bilateral symmetry. To further maintain bilateral symmetry, the quantity of the remaining struts 139 may be an even number (e.g., 2, 4, 6, 8 remaining struts 139 in addition to the two wide struts 138). For example, six outlet windows 128 defined by six struts 138, 139 including two wide struts 138 and four thinner struts 139 may meet all design inputs. An impeller housing 100 having six outlet windows 128 may have the minimum number of windows 128 that meets the requirement to prevent interference of external objects (e.g., window width 255 provides a secant 269 that does not overlap with the impeller tangent 270). This embodiment may also help reduce vibration due to mass and hydraulic symmetry.

[0059] As shown in FIG. 8 and 9, to improve mechanical integrity circumferential struts 271 can be implemented into the geometry of the impeller housing 100. The circumferentialstruts 271 can resist bending of the impeller housing 100. The circumferential struts 271 can resist deformation of the struts 138, 139, as the struts 138, 139 may be quite thin. The circumferential struts may be aligned with the circumference of the impeller housing 100. The circumferential struts 271 may also have a width of 0.6 mm. They may be aligned within the range of the magnet container 281, for example, between the flow channels 284 and gap 282 to reduce interference with the blood flow exiting the outlet windows 128 pushed out by impeller 103 or entering the outlet windows 128 pulled into the gap 282. Optionally, in some embodiments the circumferential struts 271 can have a rounded, chamfered, and / or tapered leading edge, which may result in less hemolysis (see FIG. 5). Optionally, in some embodiments the outer edges of each window 128 may be rounded, chamfered or tapered. Additionally, circumferential struts may be positioned to maintain the window arc width 255 within limits under expected mechanical loads.

[0060] Another functional advantage of the circumferential struts 271 may be the smaller axial length of each opening window 128. This can further reduce the risk of an external object interfering with the impeller 103 since it can reduce the curving radius (in the longitudinal direction), which is needed to interfere with the impeller 103, as shown in Fig. 7. Accordingly, external-object interference risk is reduced without reducing flow area.

[0061] The detailed description herein is directed to certain embodiments of a pump of a mechanical circulatory support (MCS) system and method, and related features. In this description, reference is made to the accompanying drawings. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Thus, in some embodiments, part numbers may be used for similar components in multiple figures, or part numbers may vary from figure to figure. The illustrative embodiments described herein are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented. It will be readily understood that the aspects of the present disclosure and illustrated in the figures can be arranged, substituted, combined, and designed in a wide variety of different configurations by a person of ordinary skill in the art, all of which are made part of this disclosure.

[0062] Reference in the specification to “one embodiment,” “an embodiment”, or “in some embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Moreover, the appearance of these or similar phrases throughout the specification does notnecessarily mean that these phrases all refer to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive. Various features are described herein which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but may not be requirements for other embodiments.

[0063] Reference in the specification to directional terms may be used for purposes of describing the orientation and positioning of components described herein. Accordingly, the following definitions will be used: “lateral” means away from a central longitudinal axis; “proximal” means towards or near a particular reference point; and “distal” means away or far from a particular reference point.

[0064] The foregoing description details certain embodiments of the systems, devices, and methods disclosed herein. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the systems, devices, and methods can be practiced in many ways. It should be noted that the use of particular terminology when describing certain features or aspects of the disclosure should not be taken to imply that the terminology is being re-defined herein to be restricted to including any specific characteristics of the features or aspects of the technology with which that terminology is associated.

[0065] It will be appreciated by those skilled in the art that various modifications and changes may be made without departing from the scope of the described technology. Such modifications and changes are intended to fall within the scope of the embodiments. It will also be appreciated by those of skill in the art that parts included in one embodiment are interchangeable with other embodiments; one or more parts from a depicted embodiment can be included with other depicted embodiments in any combination. For example, any of the various components described herein and / or depicted in the figures may be combined, interchanged or excluded from other embodiments.

[0066] With respect to the use of substantially any plural and / or singular terms herein, those having skill in the art can translate from the plural to the singular and / or from the singular to the plural as is appropriate to the context and / or application. The various singular / plural permutations may be expressly set forth herein for sake of clarity.

[0067] It will be understood by those within the art that, in general, terms used herein are generally intended as “open” terms (e.g., the term “including” should be interpreted as“including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and / or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations).

[0068] Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C. etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and / or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

[0069] The term “comprising” as used herein is synonymous with “including,” “containing,” or “characterized by,” and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.

[0070] The above description discloses several methods and materials of the present disclosure. This disclosure is susceptible to modifications in the methods and materials, as well as alterations in the fabrication methods and equipment. Such modifications will become apparent to those skilled in the art from a consideration of this disclosure or practice of the embodiments disclosed herein. Consequently, it is not intended that this disclosure be limited to the specific embodiments disclosed herein, but that it cover all modifications and alternatives coming within the true scope and spirit of the disclosure as embodied in the attached claims.

Claims

WHAT IS CI Al MED IS:

1. An axial flow heart pump comprising:an impeller configured to rotate about a longitudinal axis and having an impeller radius n about the longitudinal axis; andan impeller housing having an outer radius ih about the longitudinal axis, wherein the impeller housing comprises a plurality of longitudinal struts spaced circumferentially to define a plurality of outlet openings, wherein each of the plurality of outlet openings has an opening arc width less than or equal to a maximum opening arc width w0, wherein each of the plurality of longitudinal struts has a width greater than or equal to a minimum width ws, and wherein the maximum opening arc width wois small enough to prevent a straight object outside of the impeller housing from contacting the impeller.

2. The pump of claim 1, wherein a secant between adjacent longitudinal struts of the plurality of longitudinal struts has a radial distance from a center of the impeller that is greater than or equal to the impeller radius n .

3. The pump of claim 1, wherein the maximum opening arc width w0is less than or equal to (2cos-1(x)ri / ih) / (360*2pi*ih).

4. The pump of claim 3, wherein n = 2.75mm, Th = 3.10 mm, and wo= 2.975 mm.

5. The pump of claim 4, wherein the plurality of outlet openings comprises six outlet openings.

6. The pump of claim 4, wherein ws= 0.6 mm.

7. The pump of claim 1, wherein at least one longitudinal strut of the plurality of longitudinal struts has an electrical conductor disposed longitudinally thereon.

8. The pump of claim 7, wherein the impeller housing is bilaterally symmetrical.

9. The pump of claim 8, wherein the plurality of outlet openings comprises an even number of outlet openings.

10. The pump of claim 9. wherein the at least one longitudinal strut that comprises the electrical conductors has a width of at least 0.9 mm.

11. The pump of claim 1, further comprising a plurality of circumferential struts, wherein each circumferential strut of the plurality of circumferential struts connects adjacent longitudinal struts of the plurality of longitudinal struts.

12. The pump of claim 11 , wherein the plurality of circumferential struts are configured to resist bending of the impeller housing.

13. The pump of claim 11 , wherein the plurality of circumferential struts are configured to resist deformation of the plurality of longitudinal struts.

14. The pump of claim 11, wherein the plurality of circumferential struts are aligned with the circumference of the impeller housing.

15. The pump of claim 11, wherein the plurality of circumferential struts each have a rounded, chamfered, or tapered leading edge.

16. The pump of claim 11, wherein individual struts of the plurality of circumferential struts have a width of 0.6 mm.

17. The pump of claim 11 , wherein the plurality of circumferential struts are configured to reduce the axial length of the plurality of outlet openings.

18. The pump of claim 2 further comprising an inlet portion positioned distally from the impeller housing and comprising an inlet.

19. The pump of claim 18 further comprising a connection section configured to couple the impeller housing and the inlet portion.

20. The pump of claim 19 further comprising a motor housing positioned proximally to the impeller housing.

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