Patent ID: 12257425

DETAILED DESCRIPTION

The disclosure relates to devices and methods for treating edema or congestive heart failure. Devices of the disclosure include catheters dimensioned for insertion through a jugular vein, in which the catheters use or include various features each alone or in combination as described herein. Embodiments of the devices include treatment devices in which a flow restrictor such as a balloon is mounted to a cage or housing of an intravascular pump or impeller. In some of those embodiments, a shape of a balloon in a deployed state directs and facilitates blood flow into an inlet of an impeller. In certain embodiments, devices of the disclosure include an impeller that has a smaller diameter proximal end as compared to a distal end to compensate in size for positioning of a balloon on an impeller cage. Aspects of the invention relate to a purge-free system, or purge-free intravascular treatment catheters that do not use a purge fluid to protect an impeller from thrombosis or clotting. In certain embodiments, devices and methods of the disclosure use the release of an anticoagulant such as heparin at an inlet of an impeller cage. Other embodiments of the disclosure relate to devices and methods that use a restrictor such as a balloon to balance pressure and to compensate for downstream flow when an impeller is operated to drain a lymphatic duct. Features and embodiments of the disclosure include edema treatment devices that include an arrangement of lumens that is symmetrical about a drive shaft to impart balance to the drive shaft. In some embodiments, those lumens have a proximal terminus outside of a motor housing and extend down to a distal portion of a catheter. Device of the disclosure may include an atraumatic tip with a thread therein to allow for a smooth material transition. Embodiments of the disclosure may include a guidewire running through an impeller cage. Those embodiments are described and shown in greater detail herein and may be present in any suitable combination in a device of the disclosure.

FIG.1shows a device101for treatment of edema. The device101includes a catheter105comprising a proximal portion109and a distal portion115. An impeller housing203is attached to the distal portion115of the catheter105with an impeller disposed therein. An expandable member301may be aligned over an outside of the impeller housing203. The expandable member301is depicted in a collapsed configuration, and thus appears as little more than a smooth continuation of the impeller housing203.

The device101may include a restrictor801and at least one pressure sensor805. In the depicted embodiment, the restrictor801is proximal to the expandable member301. Preferably, each of the restrictor801and the expandable member301is independently selectively deployable to restrict, impede, guide, or direct fluid flow around the relevant portion of the device101. In preferred embodiments, each of the restrictor801and the expandable member301sits in fluid communication with a dedicated inflation lumen that runs along a length of the catheter105.

One feature of the device101is the impeller205, which is preferably provided within an impeller assembly201that provides the impeller housing203and other mechanical features such as ports and openings useful to pump blood and fluid within blood vessels of a patient.

FIG.2gives a detail view of the impeller assembly201. The impeller assembly201includes an impeller housing203with an impeller205rotatably disposed therein. An expandable301member is aligned over an outside of the impeller housing203. The expandable member is represented inFIG.2using dashed lines (ghosted lines to aid in seeing other features of the device101). The dashed lines represent the location and disposition of the expandable member301in its collapsed or un-deployed state. The impeller housing203is attached to the distal portion115of the catheter105with an impeller disposed therein. An expandable301member is aligned over an outside of the impeller housing203. The expandable member is represented inFIG.2using dashed lines (ghosted lines to aid in seeing other features of the device101). The dashed lines represent the location and disposition of the expandable member301in its collapsed or un-deployed state.

As shown, the impeller comprises205has blades206on a shaft207. A radius measured from an axis of the impeller205to an outer edge of the blades206decreases from a distal to a proximal portion of the impeller. This can be seen in that an outer edge of each blade206includes a dogleg209defining a step-down in radius located adjacent a transition between the distal portion and the proximal portion of the impeller housing203.

When the distal portion115of the device101is inserted into vasculature of a patient and a motor in the motor in the motor housing401is operated, the impeller205rotates and drives fluid (i.e., blood) through the impeller housing203. To that end, a proximal end of the impeller housing203includes one or more inlets255and a distal portion of the impeller housing203comprises one or more outlets227. The impeller shaft207flares outwards near a distal end of the impeller205such that when the impeller205is rotated, the impeller pumps blood through the impeller housing203and out of the one or more outlets227.

FIG.14is a cross-sectional view through the impeller assembly201on the distal portion115of the device101. The impeller assembly201includes an impeller housing203with an impeller205rotatably disposed therein.

The impeller assembly201is connected to the distal portion115of the catheter. The impeller assembly has the impeller205operably disposed within the assembly. The cutaway view of the impeller assembly201shows a proximal portion of the impeller assembly is configured to facilitate flow into an inlet of the impeller assembly without recirculation.

When the impeller205operates within a blood vessel, blood flows through a housing203of the impeller assembly201without recirculation.

As illustrated by the cross-sectional view, in the depicted embodiment, the impeller assembly201comprises a cap249secured to the distal portion115and one or more struts1405extending from the cap249to the housing203. Any one or more of the struts1405may include a lumen415. The housing203has a diameter greater than a diameter of the cap249. It can be seen that structurally, a proximal base of the housing203, the cap249, and the one or more struts105define one or more inlets into the impeller housing201.

In the depicted embodiment, the strut1405has an inflation lumen415extending therethrough for inflating a balloon mounted on the impeller assembly. The strut1405is substantially parallel to an axis of the impeller205and protrudes radially inward from at least a portion of an inner surface of the impeller housing203. When structured as such, each strut1405defines a vane within the impeller assembly201that channels fluid flow when the impeller205operates to thereby prevent the recirculation or vortices.

As shown, the strut1405has a fluidic lumen415extending therethrough. The fluidic lumen415is non-concentric with at least a portion of the body of the strut1405due to material of the strut1405forming the vane within the impeller assembly201. With reference to, e.g.,FIG.3, it can be seen that the device101may include a plurality, e.g., at least three, of the struts. Together, the struts define vanes within the impeller assembly that channels fluid flow when the impeller operates to thereby prevent the recirculation or vortices.

The impeller housing201includes one or more outlets258around a distal portion of the impeller205. Operation of the impeller205within a blood vessel drives blood into the impeller assembly201via the inlets255and out of the impeller assembly201via the outlets258such that the blood exhibits smooth laminar flow without the recirculation or vortices.

FIG.15shows how blood flows through the impeller assembly201via the inlets255and out of the impeller assembly201via the outlets258such that the blood exhibits smooth laminar flow without the recirculation or vortices. The image depicts results of a computerized flow model. The flow model shows that flow through an impeller assembly with a structure of the invention is smooth and does not exhibit recirculation.

Because the model test results show smooth and efficient flow, a device of the invention pumps blood more efficiently than other devices that lack structures as shown herein.

The computer model test results show that flow is smooth and that there are no vortices or recirculation within the flow.

Because devices of the invention are more efficient than other devices and pump blood without vortices or recirculation, devices of the invention are beneficial for treating patients with edema. Thus, using a device of the disclosure, a clinician may perform a method for treating edema. The method includes inserting into an innominate vein of a patient a distal portion115of a catheter. The catheter has an impeller assembly201on the distal portion115. The method includes driving an impeller205disposed within the impeller assembly201to thereby decrease pressure at a lymphatic duct. A proximal portion of the impeller assembly201is configured to facilitate flow into an inlet of the impeller assembly without recirculation as clearly shown in the depicted computer flow model. The catheter may have any of the other features disclosed herein (e.g., a cap secured to the distal portion with one or more struts extending from the cap to support a housing of the impeller assembly in which the housing has a diameter greater than a diameter of the cap, and in which a proximal base of the housing, the cap, and the one or more struts define the inlet).

As shown by the image of results from the computer flow model, the struts define vanes within the impeller assembly that channel fluid flow when the impeller operates to thereby prevent the recirculation or vortices. The flow lines appearing in the computer flow model clear avoid any loops that would appear if the flow had recirculation or vortices. Because flow through the impeller assembly201has no recirculation or vortices, the image from the computer flow model shows only flow lines that do not have loops, circles, spirals, etc.

The impeller housing includes one or more outlets around a distal portion of the impeller. When the impeller is operated within a blood vessel, the impeller drives blood into the impeller assembly via the inlets and out of the impeller assembly via the outlets such that the blood exhibits smooth laminar flow without the recirculation or vortices.

Devices and methods of the disclosure may include other features.

A device101of the disclosure may further include a medicament lumen251extending through the catheter105and terminating substantially at an inlet255of the impeller assembly201. In some embodiments, the impeller assembly201also includes an atraumatic tip231with a threaded fitment237therein to allow for a smooth transition of material properties between the rigid impeller cage203(e.g., a metal) and the softer material of the atraumatic tip239. The tip239preferably includes a suitable soft material such as a polymer. The material may include, for example, polyether block amides such as those sold under the trademark PEBAX by Arkema Inc. (King of Prussia, PA). Although polyether block amides are mentioned in detail, the polymer can comprise any number of other polymers such as polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), polyurethane, polypropylene (PP), polyvinylchloride (PVC), polyether-ester, polyester, polyamide, elastomeric polyamides, block polyamide/ethers, silicones, polyethylene, Marlex high-density polyethylene, linear low density polyethylene, polyetheretherketone (PEEK), polyimide (PI), or polyetherimide (PEI). The threaded fitment237may include a threaded post (e.g., of metal or a plastic such as a polycarbonate) threadingly fitted to both the impeller housing203and the atraumatic tip231. By including a long post for the fitment237(e.g., longer than its own maximal diameter, preferably at least about 2 or 3× longer), the tip231can deform but is prevented from assuming or exhibiting any kinks or discontinuities. Further, as shown, the tip231may include a guidewire lumen239.

The expandable member301on the impeller assembly201is depicted in the collapsed configuration with dashed lines. The impeller assembly201operates as a pump and includes the impeller205disposed within the impeller housing203. In preferred embodiments, the expandable member301comprises an inflatable balloon connected to an exterior surface of the impeller housing203.

FIG.3shows the expandable member301in a deployed state. In the depicted embodiment, the expandable member301is provided as a balloon. As shown, when the balloon is inflated, it defines a torus. An exterior surface of the expandable member301is physically coupled to an exterior surface of the impeller housing203(e.g., the balloon may be cemented to the housing203with an adhesive).

Preferably, the exterior surface of the expandable member301is physically coupled directly to the exterior surface of the impeller housing203without any membrane, sheath, or device101between the exterior surface of the expandable member301and the exterior surface of the impeller housing203. The expandable member301may partially or fully surround the impeller housing203. The expandable member301may be provided as an inflatable balloon that surrounds the impeller housing203.

Devices of the disclosure may include feature to facilitate bonding of the balloon to the impeller housing203. For example, the impeller housing may include metal (e.g., stainless steel, steel, aluminum, titanium, a nickel-titanium alloy, etc.) and a portion of the expandable member301may be fixed to a surface of the metal by an adhesive. To facilitate bonding, at least a portion of the surface of the metal may be impregnated with a polymer. In some embodiments, the metal surface at least at the exterior, proximal portion of the impeller cage203is impregnated with polyurethane to a depth of at least 3 μm.

Using the expandable member301mounted to the impeller cage203, the device101is configured for placement in a body vessel. The impeller housing comprises an axis that may be placed substantially parallel to an axis of the vessel. Preferably, the expandable member301is impervious to flow across the expandable member. The expandable member301is configured in use to appose the wall of a blood vessel and in so doing direct fluid flow to an inlet of the impeller housing203.

In use, the expandable member301anchors or holds the impeller assembly201in a fixed position relative to the axis of the vessel. In that anchored state, the expandable member301conforms to the vessel wall at a region of apposition and the region of apposition comprises a substantially cylindrically segment of the vessel wall. The central axis of the expandable member and the central axis of the impeller housing are preferably substantially the same.

The expandable member is configured, in use, to allow the axis of the impeller housing to articulate relative to the axis of the balloon. The articulation of the impeller relative to the balloon preferably comprises two degrees of freedom.

In some embodiments, the expandable member301comprises a balloon and the membrane of the balloon comprises an omega shape in cross-section.

The impeller housing203may include a tubular member and a wall of the tubular member may include a hole extending through the wall of the tubular member to at least partially define an inflation port for the balloon. Preferably, the inflation port is connected via the catheter to an inflation system exterior of the patient. The connection may include a shaped metal tube or tubing that couples to, and forms a seal with (i.e., “sealingly coupled to”) the inflation port. In certain embodiments, the coupling of the expandable member to the impeller housing comprises at least one circumferential seal around the outside diameter of the housing. More preferably, the coupling of the expandable member to the impeller housing comprises a first circumferential seal around the outside diameter of the housing and a second circumferential seal around the outside diameter, with the second circumferential seal spaced apart axially from the first circumferential seal. In some embodiments, the circumferential seal has an axial length and a part of the seal surrounds an inflation port that extends across the walls of the impeller housing and the expandable member. The impeller housing may include an inflation port positioned between the first circumferential seal and the second circumferential seal.

Referencing back toFIG.2andFIG.3, preferably, the balloon has a collapsed state (FIG.2) for delivery and retrieval and an expanded state (FIG.3). In some embodiments, in the collapsed state at least a portion of the balloon material can slide relative to an axis of the impeller housing (i.e., is axially slidable relative to the impeller housing). For example, at least a portion of the balloon material may be configured to slide proximally during delivery and to slide distally during retrieval. It may be provided that the balloon comprises a toroidal shape with a first neck and a second neck coupled to the impeller housing. Preferably, a distance between the first neck and the second neck is smaller than the circumference of the toroidal shaped balloon.

A coupling between the expandable member301and the impeller housing203may include an interfacial layer. For example, the interfacial layer may include an interpenetrating layer. In certain embodiments, the impeller housing comprises interstices and the interpenetrating layer comprises an interpenetration of material of the membrane into the interstices of the impeller housing. The interpenetrating layer may include a tie layer, which may include an acrylate material.

In some embodiments, the expandable member301is configured to apply a radial outward force to the vessel wall. The device may be configured such that said application of said outward radial force substantially fixes at least a portion of the impeller housing203to a central axis of the vessel. The impeller housing comprises an inner lumen extending from a proximal section of the impeller housing to a distal section of, or outlets of, the housing, the inner lumen configured to house the impeller205. The impeller housing comprises a first diameter adjacent the proximal section and a second diameter adjacent the distal section. In certain embodiments, a diameter of the inner lumen of the impeller housing varies between said proximal section and said distal section. Similarly, a radial dimension of the impeller blades206may vary between said proximal section and said distal section. The diameter of the variation of impeller housing inner lumen diameter may define a tapered, a step, a plurality of steps, a plurality of tapers, a dog bone, a parabola or a combination of these. The impeller blades are configured to be in fluidic engagement with the inner lumen of the impeller housing. Preferably, the impeller blades206are configured to be in clearance with the inner lumen of the impeller housing. The impeller assembly201has at least one inlet opening and at least one outlet opening. The at least one inlet opening and the at least one outlet opening may be separated by a distance of between 1-40 millimeters. Preferably, the at least one inlet opening and the at least one outlet opening are approximately 5 millimeters apart and may position a proximal end of the impeller205approximately 0.5 millimeters from a distal edge of the inlet. This configuration is preferable because it helps minimize recirculation at a transition from inlet to impeller205. In some embodiments, discussed herein, for example, inFIG.25, the distance between the inlet and outlet may be extended to the approx. 25-30 millimeters. This configuration provides a more laminar flow into the impeller205. In other embodiments, the at least one inlet opening and the at least one outlet opening may be approximately 3 millimeters apart to bring the impeller205nearer or just inside the inlet. The at least one inlet opening comprises a proximal end and a distal end. A proximal part of the torus extends proximally of the distal end of the proximal inlet opening to define an entry funnel into the inlet opening. The distal portion115of the catheter101is configured for insertion into a vessel of a patient and the proximal portion109of the catheter is configured to extend exterior of the patient.

The proximal portion109of the catheter101may terminate at the motor housing401.

FIG.4shows a motor housing401connected to the proximal portion109of the catheter105. A motor405is disposed within the motor housing401. A drive cable411extends through the catheter105from the motor405to the impeller. In preferred embodiments, an inflation lumen415extends along the catheter105to the expandable member301. The drive cable411preferably extends through a sleeve within the catheter101, such as an impermeable sleeve121. In purge-free embodiments, the impermeable sleeve121may include a seal at one or both ends to exclude fluids from the drive cable411. The impermeable sleeve121meets the motor housing401at the proximal seal433.

In certain embodiments, the motor405includes a rotor operable to rotate at high speed and the catheter101includes a drive cable411to transmit said rotational speed through the catheter101to the impeller205. The drive cable411may be able to transmit a rotational speed of greater than 5,000 rpms to the impeller205(e.g., >10,000 rpm, >15,000 rpm, or >20,000 rpm). Most preferably, the catheter is configured for heatless operation while transmitting high rotational speeds to the impeller.

The impermeable sleeve121may include a material such as polytetrafluoroethylene (PTFE). For example, the impermeable sleeve121may be provided by thick-walled PTFE tubing. The thick-walled PTFE tubing may have a wall thickness of greater than 75 micrometers, preferably >100 microns, >125 microns, or greater than 150 microns. Optionally, the drive shaft has a second moment of area with a value. The drive cable411may include a cylindrical super-elastic member over at least a portion of the length of the drive shaft. The clearance between the drive shaft may be less than a certain number of micrometers. In some embodiments, the impermeable sleeve121comprises hydrophobic material. The impermeable sleeve121may include a material with a Hildebrand solubility parameter (δ) of less than 16 MPa{circumflex over ( )}(0.5). The impermeable sleeve121may include a material with a Hildebrand solubility parameter of less than 14 MPa{circumflex over ( )}(0.5). For example, 6 of nylon is about 15.7 Mpa{circumflex over ( )}0.5; 6 of polytetrafluoroethylene (PTFE) is about 6.2 MPa{circumflex over ( )}0.5. The impermeable sleeve121may include a PTFE material, and the drive cable411may include a nitinol rod and a gap between the rod and the sleeve may be less than a few microns. Preferably, a concentricity of the rod is greater than 95%. The drive cable may have a first diameter and a second diameter, with the first diameter being slightly larger than the second diameter. The impermeable sleeve may include a polymer material with a dynamic coefficient of friction of less than 0.08, or less than 0.07, 0.06, or 0.05.

Devices of the disclosure are useful for treating edema or congestive heart failure. Using a device of the disclosure, one may operate a pump to promote flow in an innominate vein, resulting in a decrease in pressure at an output of a lymphatic duct, which drains lymph from the lymphatic system. To compensate for what would otherwise be changes in pressure in the circulatory system that would result from operating the pump, the disclosure provides methods to compensate for a pressure change.

FIG.5shows steps of a method501of using the device101for treating edema. The method501includes inserting510the distal portion115of the catheter105into an innominate vein939of a patient, operating515the impeller, and expanding517the expandable member301to thereby decrease pressure at a lymphatic duct907.

The method501may include the use of a device101that includes a catheter105with a proximal portion109and a distal portion115, the distal portion115dimensioned for insertion into a lumen of a patient. The device101includes a pump (e.g., an impeller assembly201) and an expandable member301connected to the pump. When expanded, the expandable member301comprises a toroidal shape, in which a proximal surface of the toroidal shape directs fluid into the impeller housing203. Preferably, an inner radius of the toroidal shape is substantially the same as a radius of the proximal end of the impeller housing203. In some embodiments, the expandable member301comprises an inflatable balloon mounted on the pump. The pump comprises an impeller housing203with an impeller therein, with the balloon mounted around at least a portion of a proximal end of the impeller housing203. The impeller housing203may include a distal portion and a proximal portion, with an external diameter of the proximal portion being smaller than an external diameter of the distal portion. The expandable member301, when not expanded, is disposed around the proximal portion of the impeller housing203. When the balloon is inflated, a surface of the torus is attached to a surface of the impeller housing203. When the expandable member301is not expanded, the distal portion115of the catheter105may be passed through a 12 Fr introducer sheath.

FIG.6is a detail view of the impeller assembly201with the expandable member301in a deployed state. The impeller205sits substantially within and/or just downstream of the deployed restrictor. An inflation lumen415extends through the distal portion115of the catheter and terminates at port601into the expandable member301. Visual inspection of a surface of the expandable member301on a proximal side and an inner surface of the impeller housing203reveals that those surfaces form a smooth continuous surface that funnels fluid, under an impelling power of the impeller, through the impeller housing203. This drives blood through blood vessels and modulates fluid pressure in the vicinity. When operated substantially within an innominate vein, pressure at an outlet of a lymphatic duct decreases, which promotes the drainage of lymph and relief from edema.

FIG.7diagrams a method701for treating edema. The method701includes operating710a pump to increase flow through an innominate vein939of a patient and—subsequent to the operating step—deploying717a restrictor upstream of the pump to thereby restrict flow from a jugular vein to the innominate vein939in order to balance729pressure downstream of the pump. The method701may include operating the pump and then restricting the flow once the increased flow through the innominate vein939affects pressure in the jugular vein.

The method701preferably includes sensing715, with a pressure sensor805, an increase in pressure in the jugular vein that results from the increased flow and restricting the flow in response to sensing the increased pressure in the jugular vein.

FIG.8shows the restrictor801and a pressure sensor805. In fact, as shown inFIG.8, the device101includes pressure sensors805along the catheter105at locations both proximal and distal to the restrictor801. In the depicted embodiment, the pressure sensors805include pressure sensing lumens extending along the catheter105and terminating at the skive-cut sensing apertures along the side of the catheter105. The sensing lumens extend proximally along the catheter to the motor housing401, where the sensing lumens preferably exit the housing401and make fluidic contact with a mechanical pressure sensor device such as a piezoelectric pressure sensor. The interior of the pressure sensing lumens preferably establish at least substantial hydrostatic equilibrium from the skive-cut sensing apertures along the side of the catheter105to the mechanical pressure sensor devices such that a reading from the sensing device(s) is informative of pressure in an area around the restrictor801. Thus the pressure sensors805provide information that can feedback into the method701and be used as information to control deployment717of the restrictor801. The method701preferably includes inserting705the device101comprising the pump into vasculature of a patient prior to the operating710step.

FIG.9shows a device101inserted705into vasculature of a patient. The device101comprises a catheter105dimensioned to be at partially implanted within the vasculature and the pump comprises an impeller assembly201disposed at a distal portion115of the catheter105. The distal portion115is inserted through the jugular vein and down and into the innominate vein939. Preferably a proximal portion109of the catheter105is connected to a motor housing401and the device101one or more pressure sensor805and the deployable restrictor801attached to the catheter105proximal to the pump.

Once the impeller assembly is at least partially within the innominate vein939, the impeller205is spun, which pumps blood through the impeller housing203. This causes a decrease in pressure around an outlet of a lymphatic duct907. The decrease in pressure causes lymph to drain from the lymphatic duct907and into the circulatory system. That drainage of lymph relieves edema or alleviates congestive heart failure. The method701further includes deploying717a restrictor801upstream of the impeller assembly201to thereby restrict flow from a jugular vein to the innominate vein939in order to balance729pressure downstream of the impeller assembly201. The method701may further include sensing715pressure and adjusting735restriction of the flow according to pressure sensed715via one or more of the pressure sensors805.

In some embodiments, the restrictor801includes an inflatable balloon and restricting717the flow includes inflating the restrictor. Optionally the sensing715is performed using a computer system communicatively connected to the pressure sensor(s)805. The method701may include periodically or continually adjusting735inflation of the restrictor according to the sensed pressure.

FIG.10diagrams a related method1001for treating edema. The method1001includes inserting1005a pump into an innominate vein and operating1010the pump to increase flow through an innominate vein939of a patient. A pressure change in a jugular vein of the patient that results from the increased flow is sensed1015, and a restrictor801is adjusted1029to restrict flow from the jugular vein to the innominate vein939based on the sensed pressure. Preferably, the method1001includes inserting1005a catheter105into the innominate vein939. The catheter105comprises the pump, a pressure sensor805, and the restrictor801. The restrictor may include an inflatable balloon and adjusting1029the restrictor may include at least partially inflating and/or deflating the balloon. The sensing1015may be performed using the pressure sensor805. The method1001preferably includes periodically or continually adjusting inflation of the restrictor according to the sensed pressure. The method1001may include adjusting1029the inflation in order to balance pressure downstream of the pump. In preferred embodiments, the pump comprises an impeller assembly201disposed at a distal portion115of the catheter105. A proximal portion109of the catheter105is connected to a motor housing401having a motor405therein operably coupled to the impeller assembly. In certain embodiments, the catheter105is coupled to a computer system operable to read the pressure or control the inflation.

Aspects and embodiments of the disclosure relate to a purge-free system, which may be understood to refer to or include methods and devices for the treatment of edema that do not use a purge system or a purge liquid.

FIG.11is a detail view of features that provide for a purge-free system. The purge-free system may be provided by a device101that includes a catheter105comprising a proximal portion109and a distal portion115, an impeller205connected to the distal portion115of the catheter105, a motor405connected to the proximal portion109of the catheter105, a drive cable411extending through the catheter105from the motor405to the impeller205, and an impermeable sleeve121extending through the catheter105over the drive cable411.

The sleeve121has a distal seal435at the impeller. With reference back toFIG.4, the sleeve121may have a proximal seal433at the motor405. Due to the sleeve121and at least the distal seal435, a body fluid external to the impermeable sleeve121is prevented from entering the impermeable sleeve121and contacting the drive cable411. The sleeve121and at least the distal seal435exclude fluid from the drive cable411.

With reference back toFIG.4, the proximal seal433(seeFIG.4) may include one or more O-rings. Similarly, the distal seal435between the sleeve121and the drive cable411may be provided by an O-ring, or a collar or press-fit, or extended, friction-fit tube. Any suitable seal may be included that prevents blood or bodily fluid from entering the sleeve and making contact with the drive cable121. The drive cable121may be provided by any suitable material including, for example, a nickel-titanium alloy or a braided steel cable. Contact with blood would present a risk of hemolysis or clotting that could interfere with an ability of the drive cable411to rotate freely (e.g., at >5,000 rpm) within the sleeve121and within the catheter105. The sleeve excludes blood and thus obviates concerns about clotting or hemolysis, allowing the drive cable411and impeller205to operate freely without impediment.

Embodiments of the device101may include multiple lumens. For example, the device101may include a first and second inflation lumen415(or a single inflation lumen415). The device may include a medicament lumen251extending through the catheter105. In preferred embodiments, the device101includes at least a first inflation lumen415and a second inflation lumen415, both extending through the catheter105. The first inflation lumen415and the second inflation lumen415have respective first and second proximal ends416(seeFIG.1) accessible outside of the motor housing401. The first lumen and the second lumen are preferably symmetrically disposed about the drive cable411to impart balance to the device101. As shown, the catheter105does not include a purge system or a purge fluid.

With reference back toFIGS.1and3, the device101may include an impeller205sitting in an impeller housing203. The device101includes at least a first expandable member301connected to the distal portion115of the catheter105. The first expandable member301may be connected to the impeller housing203, wherein the device101further comprises a second expandable member801disposed along the catheter105. The first expandable member301may use a toroidal balloon connected directly to a surface of the impeller housing203. The device101may further include at least one pressure sensor805disposed along the catheter105proximal to the impeller. In purge-free embodiments, the distal seal435may be provided using a fitting1107between the impermeable sleeve121and a portion of the impeller205, in which the fitting1107excludes fluids and allows the impeller205and drive cable411to rotate within the device101. The depicted device101is useful for the treatment of edema, and may be characterized as a purge-free device. The purge-free device may be used in a method of treating edema.

FIG.12diagrams a method1201of treating edema using a purge-free device. The method1201includes inserting1205into an innominate vein939of a patient a distal portion115of a catheter105and driving1210an impeller205connected to the distal portion115of the catheter105by means of motor405at a proximal portion109of the catheter105. The motor405is connected to the impeller205by a drive cable411extending through the catheter105, to thereby decrease pressure1217at a lymphatic duct907. An impermeable sleeve121extends through the catheter105over the drive cable411such that body fluid external to the impermeable sleeve is prevented from entering the impermeable sleeve and contacting the drive cable. The impermeable sleeve121and at least the distal seal435exclude1215fluid from entering into the impermeable sleeve121and making contact with the drive cable411.

The method1201may include inflating1229a restrictor disposed along the distal portion115of the catheter105to restrict flow from a jugular vein into the innominate vein939. The inflation1229may be performed using an inflation lumen415extending through the catheter105outside of the impermeable sleeve121. In some embodiments, blood and bodily fluid is excluded1215from the drive cable411using a repulsive gap between the drive cable411and the impermeable sleeve121. For example, the repulsive gap may include a hydrophobic material (PTFE) on one side of the gap, a smooth metallic shaft411on the other and a gap dimension that prevents influx of blood components. For example, a gap dimension of about 0.5 μm should prevent influx of red blood cells, leukocytes, and platelets. It may be found that a gap dimension of 0.1 μm excludes1215all blood and bodily fluid. The drive cable411may not lie concentric with the sleeve121so preferably the gap dimension is the largest gap between the two.

The decreased pressure at a lymphatic duct907promotes drainage from a lymphatic system into a circulatory system. Preferably, the impermeable sleeve121comprises a proximal seal433at a housing of the motor405and a distal seal435at the impeller205. The proximal seal433prevents the blood and bodily fluid from escaping the patient through the motor housing401or the proximal portion109of the catheter105. In some embodiments, the distal seal435comprises a fitting between the impermeable sleeve and a portion of the impeller, wherein the fitting excludes fluids and allows the impeller and drive cable to rotate within the device101.

The method1201may include inflating at least one balloon301,801disposed along the catheter105by means of an inflation lumen415having a proximal end accessible outside of the motor housing401while the distal portion115of the catheter105is inserted into the innominate vein939. In various embodiments, the proximal seal433uses an O-ring; the impermeable sleeve121comprises PTFE; the drive cable411comprises a metal such as a nickel-titanium alloy; either or both of balloon301and restrictor801may comprises polyvinyl chloride, cross-linked polyethylene, polyethylene terephthalate (PET), or nylon; or any combination of the those materials are included. Employing the method1201, blood and bodily fluid are excluded1215from the drive cable411without the use of a purge fluid or purge system.

Other features and benefits are provided by or within the scope of the disclosure.

Methods and devices of the disclosure avoid problems with thrombosis or hemolysis that may otherwise interfere with the functioning of mechanical systems or form surface irregularities that lead to other complications. For example, mechanical system may be most beneficial medically when blood clots or other coagulation-related phenomena are avoided. Accordingly, embodiments of devices and methods of the disclosure are provided that inhibit coagulation, thrombosis, hemolysis, or other issues that may present when treating edema.

Certain embodiments provide a device that operates with benefit from an anticoagulant. The device may include a pump (e.g., an impeller assembly) that is washed with a solution or suspension that comprises an anticoagulant such as, for example, heparin. Where the pump or impeller assembly is provided via a catheter, the catheter may include a lumen, reservoir, port, or other such feature to release the coagulant at or near the pump.

FIG.13illustrates a portion of an intravascular device101for treatment of edema that releases an anticoagulant at an intravascular pump. The device101includes a catheter105, an impeller assembly201mounted at a distal portion115of the catheter105, and a medicament lumen251extending through the catheter105and terminating substantially at an inlet255of the impeller assembly201. When the device101is used (e.g., when the impeller205is operated within a blood vessel of a patient), a medicament released from the medicament lumen251flows through the inlet255and impeller assembly201. Preferably, the catheter105and impeller assembly are dimensioned for insertion through a jugular vein of a patient The device101may include a reservoir in fluid communication with the medicament lumen251. The reservoir may be, for example, a solution bag (aka an “IV bag”) on a rack near the treatment gurney and in fluid communication with the medicament lumen251(e.g., via a Luer lock).

In certain embodiments of an anticoagulant delivery device101, the impeller assembly201has an impeller housing203with an impeller205rotatably disposed therein. The device101preferably includes a motor405connected to a proximal end of the catheter105and operably connected to the impeller205via a drive cable411extending through the catheter105. The medicament lumen241preferably extends through the catheter105(e.g., outside of a sleeve121surrounding the drive cable411) and may terminate at a port252such that an anticoagulant released therefrom washes the impeller205or impeller assembly201. Preferably, the port252is located at the impeller housing203, proximal to the impeller.

To define the inlets255, the catheter105may include a tube with a drive cable extending there through with a cap249connected around a terminal portion of the tube, with the impeller housing203mounted to the cap by a plurality of struts to define inlets255into the impeller housing203. In some embodiments, the cap249seals a terminus of the flexible tube to a shaft of the impeller, and the port252is located in the cap249. Preferably, the impeller housing203includes one or more outlets258around a distal portion115of the impeller, such that operation of the impeller205within a blood vessel drives blood into the impeller assembly201via the inlets255and out of the impeller assembly via the outlets258.

The device101may include an anticoagulant in the reservoir. When the device101is inserted into a blood vessel of a patient and the impeller205is operated, the anticoagulant is released from the port252in the impeller cage201and the released anticoagulant mixes with blood and washes over the rotating impeller205. Any suitable anticoagulant may be used. For example, the anticoagulant may include one or any combination of heparin, tirofiban, warfarin, rivaroxaban, dabigatran, apixaban, edoxaban, enoxaparin, and fondaparinux. Due to the anticoagulant, the device101may be used for the treatment of edema, using the impeller to cause drainage of a lymphatic duct or vessel.

Using such a device, aspects of the invention provide a method for treating edema. The method includes operating a pump to increase flow through an innominate vein939of a patient and releasing an anticoagulant at or adjacent an inlet of the pump. The pump may include an impeller205in a cage203at a distal portion115of a catheter105and the anticoagulant is released from a port252in or adjacent a proximal portion of the cage. Preferably, a proximal end of the catheter105terminates at a housing comprising a motor405, and the motor405is operably coupled to the impeller by a drive cable extending through the catheter105. In this method, the catheter105includes a medicament lumen extending therethrough and terminating at the port. This method may include providing the anticoagulant in a reservoir in fluid communication with the medicament lumen; inserting the catheter105into vasculature of the patient to position the impeller in the innominate vein939; operating the motor405to drive the impeller; and washing the anticoagulant over the impeller by releasing the anticoagulant from the port. Preferably, this method includes operating the pump decreases pressure at a lymphatic duct907, thereby draining lymph from a lymphatic system of the patient. The pump may include an impeller on a distal portion115of a catheter105. This method may include releasing the anticoagulant from a port at a proximal portion109of the impeller, preventing clotting or thrombosis from interfering with operation of the impeller by the release of the anticoagulant, or both. The anticoagulant may include heparin, warfarin, rivaroxaban, dabigatran, apixaban, edoxaban, enoxaparin, or fondaparinux. Using a restrictor801,301, the method may include restricting flow from a jugular vein to the innominate vein939to thereby promote flow from a subclavian vein to the innominate vein939.

FIG.16is a partial cutaway view of an impeller assembly1601. The impeller assembly1601includes an impeller housing1603with an impeller1605rotatably disposed therein. An expandable member1607is attached to an outside of the impeller housing1603. The expandable member1607is depicted in an expanded state.

The impeller assembly1601is may be designed to facilitate a blood flow through the impeller housing1603. To facilitate blood flow, the impeller housing1603may include proximal inlets1655. Preferably, the impeller housing1603includes at least four proximal inlets1655. The proximal inlets1655may be substantially rectangular and may include rounded corners. The impeller assembly1601may also include distal outlets1658. For example, the impeller assembly1601may include four to five distal outlets1658. Preferably, the proximal inlets1655and distal outlets1658include substantially rounded features, such as, rounded corners. Rounded features are preferable because rounded features provide smooth contact surfaces for blood that flows through the impeller housing1603. This may reduce incidences of damage to particles in blood, e.g., blood cells, that occurs when blood strikes a sharp surface.

In preferred embodiments, an expandable member1607is attached to an outer surface of the impeller housing1603. The expandable member1607may comprise a shape that facilitates a flow of blood into the impeller housing1603when the expandable member1607is in an expanded state. In some embodiments, the expandable member1607forms a D shaped ring around a circumference of the impeller housing1603. In other embodiments, the expandable member1607forms an Omega shaped ring around a circumference of the impeller housing1603. In other embodiments, the expandable member1603forms a substantially circular ring around the impeller housing1603.

In an expanded state, a proximal face1613of the expandable member1607may be substantially aligned with a distal portion1615of the proximal inlets1655. A distal face1617of the expandable member1607may be substantially aligned with the proximal extent1619of the distal outlets1658.

In preferred embodiments, the expandable member1607comprises an elastomeric membrane, for example, a polyurethane membrane. The expandable member1607may be a balloon. The balloon may comprise a low durometer material, for example, a durometer of <80 shore D hardness, or <70 shore D hardness, or less than 60 shore D hardness, or between 60 shore A hardness and 60 shore D hardness.

The expandable member1607may include a fluidically sealed space, i.e., an inflation space1623, that is radially expandable relative to the impeller housing1603. The impeller assembly1601may include an inflation tube1627connecting the inflation space1623to a lumen of the catheter1602. The inflation tube1627may extend between the catheter1602and the inflation space1623, for example, parallel to a proximal strut1633. The inflation tube1627may extend exterior of the proximal strut1633(as shown). Alternatively, the inflation tube1627may extend interior to the proximal strut1633. The inflation tube1627may connect with the inflation space1623by extending through a wall of the expandable member1607. Alternatively, the inflation tube1627may connect with the inflation space1623by extending through an interface between the expandable member1607and the impeller housing1603, or by extending through a wall of impeller housing1603. The fluidically sealed space1623may comprise an inflation port for expanding the expandable member1607.

The inflation tube1627may comprise an outer surface and a lumen. The inflation tube1627preferably provides a sealingly penetrate into the inflation space1623. The penetration of the inflation tube1627into the inflation space1623may comprise a seal of the region of penetration. The seal may comprise a melting or bonding operation.

FIG.17is a side view of an impeller assembly1701. An expandable member1707, e.g., a balloon, is attached to an outer surface of an impeller housing1703. The expandable member1707may be substantially torpid in shape. The expandable member1707is depicted with muted lines to reveal structures beneath the expandable member1707. A proximal face1713of the expandable member1707extends over a distal inlet region1715. In this configuration, the proximal face1713of the expandable member1707provides a funnel to converge blood flow towards inlets of the impeller housing1703thereby facilitating blood flow through the device.

The impeller assembly1701is dimensioned for inserting into an innominate vein. The expandable member1707is dimensioned such that in a deployed state, the expandable member1707opposes walls of the innominate vein to impede, guide, or direct a flow of blood into the impeller housing1703. In some embodiments, an inner diameter of the expandable member1707is substantially equivalent to the outer diameter of the impeller housing1703. The inner diameter of the expandable member1707may extend over a portion of the proximal inlets. This arrangement helps funnel blood into the impeller assembly1701without the distal edge of the inlets disrupting blood flow. In some embodiments, the proximal inlets are substantially D shaped with rounded features to prevent shearing of blood cells.

The expandable member1707may comprises a bonded region, the bonded region comprising a substantially cylindrical section where the expandable member1707is bonded to the impeller assembly1701. In some embodiments, the inlet region may comprise a conical element1737coaxial with the impeller. The conical element1737may be proximal to the impeller and may be configured to minimize flow recirculation regions.

FIG.18shows an exemplary inlet region1855of an impeller assembly1801. The inlet region1855comprises a conical element1837with flow directing features projecting radially outward from a surface of the conical element1837. The flow directing features may be aligned with proximal struts. A drive element1839may extend through the conical element1837and connect with an impeller disposed inside the impeller assembly1601. In the shown embodiment, an inflation lumen1827is exterior of the impeller assembly1801.

FIG.19shows an inlet region1955with an internal inflation lumen. The inflation lumen is internal to the impeller housing1903. The inflation lumen may connect to and extend through the conical element1937. The inflation lumen may, for example, extend through a wall of the impeller housing1903. Alternatively, the inflation lumen may be interiorly located within the impeller housing1903.

FIG.20is a detailed view of a proximal inlet2055. The proximal inlet2055is defined by proximal struts2033. The proximal struts2033extend parallel to one another connecting a proximal portion2041of the impeller housing2003to a distal portion2043of the impeller housing2003. The proximal struts2033are designed such that when the catheter is operating inside a patient's body, the proximal struts2033may separate and direct a flow of blood into the impeller housing2003without inducing a recirculation flow pattern. The proximal struts2033may include a proximal and distal rim2045,2047. The proximal struts2033and rims2045,2047may, for example, define a generally rectangular inlet region2055. In some embodiments, the generally rectangular inlet region2055comprises a curved rectangular inlet. The curved rectangular inlet may have, for example, a bevel around at least a portion of a rim2045,2047of the inlet2055. The bevel may provide a gentle transition region for blood to flow into the impeller housing2003.

In some embodiments, the proximal struts2033comprise a substantially constant width along a length of the proximal strut2033. In other embodiments, the width of the proximal struts2033may vary, for example, the width of the proximal struts2033may be greater at a proximal end than at a distal end, or vice versa. The proximal struts2033may comprise a first wall thickness and a second wall thickness, wherein said first wall thickness is greater than said second wall thickness. In some embodiments, the proximal struts2033may comprise a tapered wall thickness.

Preferably, the impeller housing2003is substantially cylindrical in shape for easy passage through an innominate vein. The impeller housing2003may comprise a plurality of inner diameters for manipulating a flow of blood through the impeller housing2003and such that the flow of blood experiences minimal disturbances such as recirculation or vortices within, or near, the impeller assembly2001. For example, the impeller housing2003may comprise a first inner diameter D1 and at least a second inner diameter D2 wherein the first inner diameter is greater than said at least second diameter. In some embodiments, the impeller housing2003may comprise stepped portions defined by changes in inner diameters. In some embodiments, the impeller housing2003may comprise, for example, a tapered diameter, defined by a diminished or reduced internal diameter along the length of the impeller housing2003toward one end.

FIG.21shows a side view of an impeller assembly2101with rectangular proximal inlets2155. This configuration may reduce recirculation of blood at a proximal area of the impeller assembly2101by providing a larger inlet area at the distal-most region of the inlet2147.

FIG.22shows an impeller assembly2201with arcuate proximal struts2233. The arcuate proximal struts2233extend longitudinally and radially. In some embodiments, the arcuate proximal struts2233comprise tubular members. The tubular members may be welded to the impeller assembly2201, connecting a proximal portion2241of the impeller housing2203to a distal portion2243of the impeller housing2203. The arcuate proximal struts2233may connect to a proximal portion2241of the impeller housing2203integral with the catheter shaft. The arcuate proximal struts2233may comprise a monolithic structure. The monolithic structure may comprise a 3D printed structure.

The impeller assembly2201may be distally mounted to a catheter shaft (not shown) comprising a plurality of lumens and at least one of the lumens sealingly connected to an expandable member2207attached to an outer surface of the impeller housing2203.

FIG.23shows a side view of a proximal portion of an impeller assembly2301. The proximal portion of the impeller assembly2301includes a proximal hub2383, a proximal inlet2355, and a body section2385. The proximal hub2383may be configured to facilitate a smooth flow pattern as fluids, e.g., blood, are directed into the proximal inlet2355. The hub2383may comprise a substantially circular outer geometry in axial cross section for easy movement within a vein. The hub2383may comprise a tapered geometry. For example, a cross-sectional diameter of the hub2383may decrease along a length of the hub2383from a first end to a second end. The hub2383may have a tapered outer geometry that may comprise a proximal diameter, an intermediate diameter, and a distal diameter wherein the intermediate diameter is greater than either the proximal diameter or the distal diameter and the transition between proximal, intermediate, and distal diameters is substantially smooth. The curve between the proximal, intermediate, and distal diameters may be without an inflection point.

FIG.24shows an impeller assembly2401. The impeller assembly2401includes an impeller housing2403with an impeller2405rotatably disposed therein. An expandable member2407depicted with ghosted lines is attached to an outer surface of the impeller housing2403, the expandable member2407is shown in an expanded state.

The impeller assembly2401is designed to facilitate the flow of blood through the impeller housing2403. The impeller assembly2401may include fillets2435under the proximal end of the proximal struts2433to provide mechanical support and prevent recirculation of blood in these regions when the catheter is inside a vein. In some embodiments, the proximal struts2433taper towards their distal ends.

FIG.25shows an elongated impeller assembly2501. The elongated impeller assembly2501includes an expandable member2507spaced apart from a proximal inlet region2555. The expandable member2507may be, for example, approximately 1-25 cm from the proximal inlet region2555. Preferably, the expandable member is at least 1 cm from the proximal inlet region2555.

FIG.26shows a cross-sectional view of an impeller assembly2601. The impeller assembly2601includes an impeller housing2603with an impeller2605rotatably disposed therein. The impeller assembly2601includes a distal portion2645. The distal portion2645may include a tip2647that is substantially disc shaped. The distal portion2645may have at least a partially flat surface. The disc-shaped tip2647may be spaced apart from a proximal surface of the distal portion2645.

The impeller2605may comprises a substantially fixed axial position relative to the impeller housing2603. The distal portion2645may comprise a substantially fixed axial position relative to the impeller housing2603. The fixed axial positions of the impeller2605and the distal portion2645may define a distal gap2651between the distal portion2645and the impeller2605. The gap2651is preferably greater than Sum. The gap2651may be greater than 10 um or 20 um. The gap2651may be preferably less than 150 um, 120 um, or 100 um. Ideally, the gap2651is between 25 um and 50 um.

FIG.27is a cross-sectional view of an impeller assembly2601inside a vein2756. The impeller assembly2701comprises an impeller housing2703with an impeller2705inside. The impeller housing2703has an expandable member2707attached to an outer surface of the impeller housing2703.

The impeller2705includes at least one blade2753. The blade2753comprises a proximal end and a distal end. A core diameter of the impeller2705comprises a proximal end and a distal end. The core diameter proximal end is proximal of the proximal end of the blade2753. The core diameter distal end and the blade distal end terminate substantially at the same axial region. The core diameter is smallest at the proximal end of the impeller2705and largest near the distal end of the core diameter. The core diameter may comprise a curved tapered surface.

The proximal end of the impeller2705core diameter may be spaced apart from the distal end of a cuff2761. The proximal end of the impeller2705core diameter and the distal end of the cuff2761comprise a controlled proximal gap. The gap2751is preferably greater than Sum. The gap2751may be greater than 10 um or 20 um. The gap2751may be preferably less than 150 um, 120 um, or 100 um. Ideally, the gap2751is between 25 um and 50 um.

The impeller2705may comprise an inner diameter, the inner diameter extending through at least a portion of the length of the impeller2705and being coaxial with the impeller2705. The impeller2705may comprise a bearing arrangement distal of the distal surface. The bearing surface may include a ball bearing arrangement, for example, a ceramic bearing arrangement or a PTFE or PEEK bearing surface arrangement.

FIGS.28A-Fillustrates attachment and folding of an expandable member2807. In particular, these drawings detail attachment of the expandable member2807to an outer surface of an impeller housing2803as wells as folding of the expandable member2807when the expandable member is inflated or when the catheter is being delivered or retrieved.

FIG.28Ais a partial cross-sectional view of an impeller assembly2801. A portion of the cross-section demarcated by dashed lines and labeled B shows a portion of the expandable member2807and is enlarged inFIG.28B. The expandable member2807includes at least one coupling2863attaching the expandable member2807with the impeller housing2803. The coupling2863may create a sealed annular space in the expandable member2807.

The coupling2863may comprise a laser weld joint, a solvent weld joint, an adhesive weld joint, a hot air or heated surface weld joint, or any other similar type of attachment. The coupling2863may comprise a prepared outer surface of the impeller housing2803onto which the expandable member2807is attached. For example, the impeller housing2803may be prepared such that the impeller housing2803includes at least one of a primed surface, a chemically activated surface, a plasma activated surface, a mechanically abraded surface, a laser ablated surface, an etched surface, or a textured surface. The prepared outer surface of the impeller housing2803may comprise a surface roughness, a patterned surface, or a high energy surface.

Referring toFIG.28B, the expandable member2807may include at least one neck2867, the neck2867may be dimensioned for joining with the impeller housing2803. The expandable member2807may comprises a joint distal end2831and a joint proximal end2832. The shape of the distal end2831may be configured to change as the expandable member is inflated/deflated (compareFIGS.28B,28D, and28E) or when the catheter is moved inside a vein. In particular, the joint distal end2831may comprise a distal neck segment joined to the impeller housing2803and a distal transition segment2845that is integral with the neck2867but not attached to the impeller housing2803. As the expandable member2807is inflated, the distal transition segment2867may fold inward. The joint proximal end may comprise a neck2832joined to the impeller housing2803and a proximal transition segment that is integral with the neck but not joined to the impeller housing. The expandable member2807may be configured to be substantially rigid in the expanded configuration. The expandable member2807may be configured to be conformable in the expanded configuration. The expandable member2807may be made from a polyurethane, or pebax or nylon material. The expandable member2807may be made from polytetrafluoroethylene.

FIG.28Cis a partial cross-sectional view of the impeller assembly2801in which the expandable member2807is partially inflated. The portion of the partial cross-section showing the expandable member2807(labeled D) is enlarged inFIG.28D. Notably, the shape of the distal neck changes as the expandable member2807is inflated (compareFIG.28Din which the expandable member is partially inflated toFIG.28Bin which the expandable member is fully inflated).

FIG.28Eis a partial cross-sectional view of the impeller assembly2801with moderately inflated expandable member2807. The portion of the partial cross-section showing the expandable member2807(labeled F) is enlarged inFIG.28F. In particular, the expandable member2807is inflated more than the expandable member2807illustrated inFIG.28D. Upon inflating the expandable member2807, the distal transition segment2845may fold outward eliminating a potential recirculation zone at the interface between the balloon and housing2803.

FIG.29shows an impeller assembly2901with an expandable member2907having an elongated surface2974for interfacing with a wall of a blood vessel. The elongated surface2974increases an interaction between the blood vessel and the impeller assembly2901to restrict movement of the impeller assembly inside the blood vessel. The expandable member2907may comprise a compliant material. The compliant material may be a polyurethane or silicone. The compliant material may stretch 100% to 800%, thus creating an elongated surface2974. In other embodiments, the expandable member2907may comprise a non-compliant material, which may expand to one specific size or size range, even as internal pressure increases.

FIG.30shows an impeller assembly3001with a two-part expandable member3007. The two-part expandable member3007includes a first part3065comprising a compliant material and a second part3066comprising a non-compliant material. The first part3065and second part3066may be attached to each other and to the impeller housing3003to define an annular space for inflation. Preferably, the first part3065of the expandable member3007comprises a portion of the expandable member3007that interacts with a wall of a blood vein during operating of the catheter.

FIG.31is a partial cross-sectional view of a distal portion of a catheter3101. The distal portion of the catheter3101is attached to an impeller housing3103with an expandable member3107mounted to an outer surface of the impeller housing3103. The impeller housing3103is connected to a distal portion of a catheter3101by a plurality of proximal struts3133. The proximal struts3133preferably comprise a flexible material, for example, latex, silicone, or Teflon, to provide for easier navigation inside a vein of a patient. The proximal struts3133may be configured to conform to anatomical curvatures. A drive shaft3139connecting a motor to an impeller disposed inside the impeller housing3103may comprise a flexible drive cable.

FIG.32is a partial cross-section of a self-expanding impeller assembly3201. The impeller assembly3201comprises an impeller housing3203with an impeller3205disposed therein. An expandable body3207is attached to a surface of the impeller housing3203between proximal inlets3255and distal outlets3258.

In an expanded configuration, the expandable body3207is configured to oppose a wall of a vein over a longitudinal segment of the vein. The longitudinal segment of apposition extends proximal of the proximal inlets3255. The longitudinal segment of apposition extends distal of the distal inlets3258. The expandable body3207is configured to provide a proximal flow directing funnel that extends from a region of apposition with the vessel wall to the distal end of the inlets3255. The proximal flow directing funnel is configured to promote converging flow pattern at the entrance to the proximal inlets3255. The expandable body3207may be configured to provide a distal flow directing funnel that extends from a proximal region of the outlets3258to a region of apposition with the vessel wall to the distal end of the outlets3258. The distal flow directing funnel may be configured to promote diverging flow pattern distal of the exit of the outlets3258. The diverging flow pattern may be configured so as to impart a gradual deceleration of fluid distal of the outlets and maintain a larger proportion of the pressure gain developed by the impeller3205by reducing recirculating or negative velocity flow patterns.

The expandable body3207may comprise a nitinol membrane, a non-compliant membrane, or a porous membrane. The longitudinal segment of the expandable body3207may comprise a compliant material. Preferably, the flow directing funnels of the expandable body3207comprise a relatively less compliant material (or a semi compliant material or a non-compliant material).

The catheter3200may comprise a plurality of pull wires3279attached to the expandable body3207and configured to facilitate collapse of the expandable body3207in preparation for the removal of the catheter3200from the body.

FIG.33shows a partial cross-section of an impeller assembly3301. The impeller assembly3301comprises proximal struts3333attaching a proximal portion3341of the impeller assembly3301to a distal portion3343of the impeller assembly3301. At least one proximal strut3333comprises an inflation lumen, i.e., an integrated inflation channel, extending through the proximal strut3333to an interior of an expandable member3307that is attached to an outer surface of the impeller assembly3301. The inflation lumen provides a structure for inflating the expandable member3307. The inflation lumen is preferably terminated within the inlet to minimize disruption to the flow inside the housing. This is facilitated by the more proximally positioned expandable member3307.

FIG.34shows an inlet3433of an impeller assembly3401. The inlet3433is configured to provide easier fluid flow into the assembly3401. This configuration includes a proximal hub3480with at least one flow basin3481. The flow basin3481extends from a proximal region of the proximal hub3480and terminates at the inlet3433. The flow basin3481extends between a first and second strut3433,3434. The flow basin3481may be configured to modulate a flow of blood upstream of the inlets. For example, the flow basin3481may progressively slope inwards along the length of the flow basin3481towards the inlet3433.

FIG.35is an exemplary catheter system3500. In particular,FIG.35illustrates a catheter3500according to aspects of the invention to show interactions between an impeller assembly3501of the catheter3500and a blood vessel wall3556. The catheter3500includes the impeller assembly3501, a catheter shaft3581, a proximal expandable member3508, a hub3583and a motor (not shown).

The impeller assembly3501is dimensioned for placement inside a blood vessel with a shaft3581extending from the impeller assembly3501to a position exterior of the patient. The shaft3581may comprise a multilumen shaft. A first proximal expandable member3508is attached to the shaft3581and may be configured to restrict a flow of blood to the impeller assembly3501.

A motor may be connected to an impeller housed within the impeller assembly3501and may be configured to drive the impeller at high RPMs. The impeller assembly3501may comprise a distal expandable member3507mounted onto an outer surface of an impeller housing3503and wrapping around the impeller housing3503, for example, like an expandable ring. The distal expandable member3503may be configured to appose a vessel wall3556during operation of the catheter.

The proximal expandable member3508may be mounted on the catheter shaft3581proximal of the impeller assembly3501. The proximal expandable member3508may be spaced apart from the impeller assembly3501. For example, the proximal expandable member3508may be a distance of 1-10 cm upstream of the impeller assembly3501, preferably about no more than about 5 cm.

The proximal expandable member3508may be dimensioned for placement (inflation) between the vessel access site and an outflow port of a thoracic duct3585. The expandable members3507,3508are preferably configured to atraumatically contact a vessel wall.

In some embodiments, a proximal expandable member3508may be configured to reduce a volume of blood flowing in the vessel by impeding a flow of flood. The proximal expandable member3508may be configured to adjust the volume of blood flowing in the vessel by impeding, restricting, guiding, or directing the flow of blood. For example, the proximal expandable member3508may include an orifice for fluid to flow across the expandable member3508while the expandable member3508is in an expanded state. For example, the orifice may substantially comprise one of an annular ring or a crescent shape with a lumen through a body of the expandable member3508. The orifice may comprise a valley or a recess in the outer surface of the expandable member3508. The orifice may comprise a channel underneath the expandable member3508. The expandable member3508may comprise a shape that defines the orifice. For example, the expandable member3508may be shaped at least partially as a spherical, conical, or cylindrical shape and the orifice comprises an annular ring or a crescent. The expandable member3508shape may comprise, for example, a double D shape and the orifice may be defined by surfaces between the two joining shapes. The expandable member3508may comprise a helical shape wrapped around the catheter shaft3581and the orifice may comprise a channel defined by a space between adjacent spirals.

The proximal expandable member3581may comprises a compliant material and the compliant material may comprise a compliance-pressure relationship. The expandable member3581may be processed so the compliance pressure relationship is repeatable. The expandable member3581may comprise an annealed member. The expandable member3581may be configured to achieve a precise diameter at a given pressure. The expandable member3581may be configured to have minimal hysteresis when inflated, deflated and inflated again.

The hub3583may be configured to facilitate inflation of a distal expandable member3507, and may be configured to at least partially inflate the proximal expandable member3508. For example, the hub3583may include access to one or more lumens that extend through the catheter shaft3581and connect to a proximal and/or distal expandable member3508,3507. The expandable members can be inflated by infusing a fluid into the lumens at the hub3583. The hub3583may be configured to inflate the proximal expandable member3508into apposition with an innominate vessel.

The device may comprise a connector cable3585configured to connect the catheter to a console (not shown), the console may comprise a computer with hardware, software and a user interface. The console can be configured to operate the device.

FIG.36shows a catheter3600with an expandable member3608slidably mounted along a shaft3681of the catheter3600. The catheter3600comprises a first catheter shaft3681and a second catheter shaft3682. The catheter3600includes an impeller assembly3601attached to a distal end of the first catheter shaft3681. The proximal expandable member3608mounted near a distal end of said second catheter shaft3682.

The first catheter shaft3681may comprise a multilumen tubing wherein a first lumen is configured to facilitate inflation of a distal expandable member3607and a second lumen is configured to transmit mechanical or electrical energy to facilitate the operation and control of an impeller disposed within the impeller assembly3601.

The second catheter shaft3682may comprise a multilumen tubing wherein a first lumen is configured to encapsulate the first catheter shaft3681and a second lumen is configured to inflate the proximal expandable member3608. The first and second catheter shafts3681,3682may be configured to facilitate relative axial movement (indicated by arrows) between the distal expandable member3607and the proximal expandable member3608. The relative axial movement may be limited distally. The relative axial movement may be is limited proximally. The catheter3600may include a first stop and a second stop and axial movement of second shaft3682may be limited by the first and second stops. The first and second stops may be mounted on the first shaft3681, exterior of the patient (inside or around the hub). The axial movement may comprise fine movements. The fine movements may comprise, for example, a thread or ratchet mechanism.

Relative axial movement between the distal expandable member3607and the proximal expandable member3608may provide better anatomical placement, i.e., accurate placement of the distal expandable member3607in the innominate vein and then accurate placement of the proximal expandable member3608between the vessel wall access site and the thoracic duct.

The first and second shafts3681,3682may extend exterior of the patient. The second shaft3682may be coupled and decoupled to the first shaft during use. In a collapsed state, the catheter may be dimensioned for advancement through a valve and lumen of a sheath. The second shaft3682may comprise a distal segment and a proximal segment. The distal segment may comprise a tubular member and an inflation lumen with the proximal expandable member sealingly welded (bonded) to a distal segment so as to create an inflation space in the expandable member3607that is in fluid communication with the inflation lumen.

The proximal segment of the second shaft may comprise an inflation lumen and a member configured to transmit axial push and pull forces to the distal segment of the second shaft3682. The proximal segment of the second shaft may be concentric or eccentric with the first shaft. The inflation lumen of the proximal segment may be integral with a wall of the proximal segment of the second shaft.

FIG.37shows a fluid channel across an expandable member3708that allows a controlled amount of blood flow. The proximal expandable member3708may be configured to oppose a wall of a vessel. The proximal expandable member3708may comprise a flow channel3706, the flow channel3706defining a lumen through the body of the expandable member3708. Flow is indicated by black arrows. The flow channel3706may comprise a collapsed state and an expanded configuration. The flow channel3706may be configured to expand when the expandable member3708is inflated. The expandable member3708may comprise at least one inner membrane, the inner membrane may be configured to support the body flow channel3706in the expanded state. The proximal expandable member3708may be configured to allow 100 ml or more fluid to cross the expandable member3708per minute.

FIG.38shows a catheter3800with an alternative bypass channel3806. A second shaft3882comprises a tubular member with a distal end and a proximal end and a lumen3883extending through both distal and proximal ends. The lumen3883may be sized to provide a fluid flow pathway underneath the inflated expandable member3808in a distal segment. The second shaft3882may comprise an entry port3885at the proximal end of the distal segment of the second shaft3882, the entry port may be configured to facilitate blood flow into said fluid flow pathway.

FIG.39shows a patient interface3900with a sheath3904in situation. A proximal expandable member, a flow entry port, and pressure sensor, may be on the sheath. The catheter system may comprise a catheter and a flow control sheath3904, the catheter comprising an impeller assembly at a distal end of an elongated shaft, the flow control sheath3904comprising a flow restrictor, a fluid channel and a pressure sensor.

The system may be configured for transdermal insertion into a vein of a patient3908. Insertion of the catheter comprises transdermal insertion in a region of the neck. The flow control sheath3904may be configured for placement so as to provide an access platform for other components of the system. The flow control sheath3904may comprise a flow restrictor adjacent a tip. The flow restrictor may comprise an expanded state and a collapsed state. In the collapsed state the flow restrictor may be configured to collapse completely onto the shaft of the sheath. In the collapsed state, the OD of the flow restrictor may be substantially the same as the shaft of the sheath. The restrictor may sit in an annular recess in a diameter of the shaft of the flow control sheath in the collapsed configuration. In the expanded configuration, the flow restrictor may be configured to at least partially restrict fluid flow through the jugular vein. The flow restrictor may be configured to control the rate of flow through the jugular vein. The flow restrictor may be configured to prevent inadvertent displacement of the flow control sheath during the procedure.

The flow control sheath may comprise a pressure sensor, the pressure sensor may be configured to measure pressure in a vein upstream of the restrictor. The sheath may comprise a lumen in a wall of the sheath and the pressure sensor may be positioned in said lumen. The pressure sensing lumen may comprise a port, the port may be configured to establish a hydrostatic connection between blood in the vein and the pressure sensor. The pressure sensor and the pressure sensing lumen may be sized to prevent blood flow ingress into the pressure sensing lumen.

FIG.40shows a patient interface4000with a sheath4004held in situation by an adhering membrane4010. The adhering member4010helps maintain a sterile region around an access site and secures a hub4080of the sheath4004to the skin. This reduces irritation to the patient by movement of the hub4080made by accidental forces. The membrane4010may be shaped so as to allow second or tertiary layers to be added to tie all of the various system elements of the sheath4004or catheter together or to the skin.

FIG.41shows a flow control sheath4150. Shown are various features of the flow control sheath4150according to some preferred embodiments. In particular, the flow control sheath4150may include a restrictor4151(shown in an inflated state), a sheath tip4152, a port4153, a pressure sensor4154, a sheath shaft4155, and a hub4159, the hub4159including a pressure sensor lead4156, an inflation side port4157, a flushing and infusion side port4158. At least one suturing hole may be added to the hub4159to facilitate fixation to the patient.

FIG.42shows a proximal portion of a catheter system4200. A catheter4269that is similar to the catheter described inFIG.40is disposed within a catheter sheath4280. The catheter4269includes a shaft4270, a proximal expandable member4271(depicted in an expanded state), and a catheter pressure sensor4273. The sheath4280includes a sheath tip4272, a sheath pressure sensor4274, a sheath shaft4275, a pressure sensor lead4276, an inflation side port4277, and hub4278.

FIG.43illustrates a locking mechanism4300for fixing a catheter shaft4392to a hub4391of a sheath4390during therapy. The locking mechanism4300includes an arm4396with a catheter shaft grip4395attached to a distal end of the arm4396. When engaged, the catheter shaft grip4395attaches to the catheter shaft4392preventing movement. The locking mechanism4300is advantageous because it prevents migration of a distal expandable member of the catheter system, described above, during therapy. The locking mechanism4300is configured to lock the catheter shaft4392to the sheath4390during at least a portion of the procedure.

The locking mechanism4300may be configured for easy engagement and disengagement. The locking mechanism may be configured to prevent relative movement between the catheter distal balloon and the access sheath4390. The locking mechanism4300may comprise a clip4395on locking mechanism4300; the clip on mechanism4300may be configured to be clipped onto the catheter shaft4392from one side of the shaft4392. The locking mechanism4300may be pre-mounted on the catheter shaft4392such that the locking mechanism4300may slide into position when fixation is required.

The locking mechanism may be integral with the sheath. The locking mechanism may optionally attach to the sheath. Preferably, the locking mechanism may be a Tuohy Borst type locking mechanism.

FIG.44shows the locking mechanism4300engaged with the catheter shaft.

FIG.45shows a schematic of a push lock mechanism4500.

FIG.46shows an alternative locking mechanism4600. The locking mechanism4600includes an arm4696attached to a hub4691of a sheath4690. The arm4696includes a catheter shaft grip4695attached to a distal end of the arm4696. When engaged, the catheter shaft grip4695attaches to the catheter shaft4692preventing movement. A further embodiment of a locking system may include a C shaped shaft which may be secured over the catheter shaft proximal to the sheath. The shaft would be configured so that when the shaft is slid into the sheath hub it creates an interference lock between the catheter shaft OD and Sheath ID.

FIG.47is a partial cutaway of a jugular vein4752showing a flow control sheath4750inserted therein. The restrictor4751of the sheath4750is shown in a deployed state with the restrictor4751opposing a wall of the jugular vein4752. In a preferred position, the shaft4755of the sheath4750terminates adjacent to a junction of the subclavian vein4753and the thoracic duct4756. The hub4759is external to the jugular vein4752.

FIG.48shows an indwelling catheter system4800according to aspects of the invention. The indwelling catheter system4800includes a catheter shaft4851with an impeller assembly4861mounted to a distal portion thereof. The catheter shaft4851includes a proximal expandable member4850attached to an outer surface of the catheter shaft4851. The proximal expandable member4850comprises a flow channel4854that allows fluid to bypass the proximal expandable member4850at a controllable rate.

FIG.49is a cross-section taken along line A-A ofFIG.48to reveal internal lumens of the catheter shaft4851. The internal lumens extend internally through the catheter shaft4851. Shown is a proximal expandable member lumen4901for delivering fluids, i.e., gas or a liquid, used to inflate the proximal expandable member4850. A separate distal expandable member lumen4902is provided for delivering fluids to inflate the distal expandable member4862. The separate lumens allow the proximal and distal expandable members4850,4862to be manipulated independently of one another during therapeutic treatments. A pressure sensor lumen4966is provided for sending and receiving electrical signals with one or more pressure sensors disposed on the catheter system4800. One or more reinforcement lumens4930may be provided to reinforce the catheter4800so that the catheter4800can be more easily navigated through the body.

FIG.50is an indwelling catheter5000. The catheter5000includes mechanical components, e.g., an impeller5005and/or drive shaft5007, and a purge system. The purge system operates to exclude biological fluids and materials from the catheter5000and mechanical components operating within the catheter5000. In that manner, body fluids are prevented from entering the crevasses of the catheter5000, ensuring smooth and efficient operation of the mechanical parts, e.g., impeller5005and drive shaft5007, within the catheter5000while also preventing the patient's body fluid from travelling to a proximal portion of the catheter5000outside of the patient's body, where it could leak out of the catheter. The purge system would further prevent air entering the vein though the same channels.

The catheter5000may be used to reduce pressure in a region of a venous system. The catheter5000includes an impellor assembly5009mounted at the distal end of the catheter5000. The impellor assembly5009comprises an expandable member5013, a cage5015with an inlet region5017and an outlet region5019and an impellor therein. The impellor5005may rotate at high RPMs within the cage5015. The impellor5005may further include a distal surface, a proximal surface and an impellor blade surface. The distal surface, proximal surface and impeller blade surface configured to rotate in close proximity to adjacent surfaces inside the cage, but without contacting said adjacent surfaces.

The impellor assembly5009may further comprise a cuff5023. The cuff5023may include a distal surface5025and a proximal surface5027. The impeller5005rotates in clearance of the distal surface of a cuff5023.

The clearance between the cuff distal surface5025and the impeller5005comprises a proximal gap5029and the proximal gap5029is configured to remain fixed during operation. The proximal gap5029is configured to define a transition between a static cuff and a rotating impeller5005. The proximal gap5029is configured to allow blood to flow across the proximal gap5029without flow disturbance, flow recirculation, or vortices. The proximal gap5029may be in fluid communication with a catheter lumen which is in fluid communication with a fluid reservoir exterior of the patient. The proximal gap5029may be configured to prevent blood flow from entering the proximal gap5029.

In preferred embodiments, the proximal gap5029includes a resistive fluid pressure configured to prevent blood from entering the proximal gap. For example, the resistive fluid may be a purge fluid delivered from a fluid reservoir external to the patient. The purge fluid can be used to purge or flush the proximal gap5029clearing debris; for example, as described in co-owned U.S. Provision Application 62/629,914, which is incorporated herein by reference. The resistive fluid pressure may comprise a hydrostatic fluid pressure, which may include a pulse of fluid pressure. The fluid pressure comprises a solution that may include saline, dextrose or a heparin solution.

The viscosity of the purge solution may be tailored to effectively purge small gaps and orifices. The solution may also be immiscible with blood to prevent blood contact with the purges surfaces. For example, the solution may be a hydrophobic solution. In some embodiments, the proximal gap5029may include a seal, such as, for example, a spring loaded seal.

A clearance between a distal-most surface of the impellor5005and a tip5031comprising a bearing housing5033may comprise a distal gap5041and the distal gap5041may be configured to remain fixed during operation. The distal gap5041may be configured to define a transition between a rotating impeller5005and a static tip5031. The distal gap5041may be configured to allow blood to flow across the distal gap without flow disturbance, recirculation, or vortices.

In preferred embodiments, the distal gap5041is in fluid communication with a catheter lumen which is in fluid communication with a fluid reservoir exterior of the patient. The distal gap5041may be configured to prevent blood flow from entering the distal gap, for example, by providing a purge from the fluid reservoir as discussed above. The distal gap5041may comprise a resistive fluid pressure configured to prevent blood from entering the distal gap. The resistive fluid pressure comprises a hydrostatic fluid pressure. The resistive fluid pressure comprises a pulse of fluid pressure. The fluid pressure comprises a solution, for example, a saline, dextrose or a heparin solution. The viscosity of the purge solution may be tailored to effectively purge small gaps and orifices. The solution may also be immiscible with blood to prevent blood contact with the purges surfaces. The solution may be a hydrophobic solution. The distal gap5041may comprise a seal, such as, for example, a spring loaded seal.

FIG.51is an expanded view of dotted circle B ofFIG.50according to an embodiment of the invention. In this embodiment, fluid is delivered from a purge channel5101extending along a central lumen of the device. The purge channel may be external to a PTFE liner that surrounds a central lumen of the catheter.

FIG.52is an expanded view of dotted circle B ofFIG.50according to another embodiment of the invention. In this embodiment, purge fluid is delivered from the reservoir exterior of the patient via a purge channel5201that travels through a lumen used for inflating the expandable member5013. The purge channel5201is external to a PTFE liner of a drive cable.

FIG.53is an expanded view of dotted circle B ofFIG.50according to a different embodiment of the invention. In this embodiment, purge fluid is delivered from a purge channel5301, the purge channel5301extending through a PTFE liner that surrounds a drive lumen.

FIG.54illustrates a distal flush of an indwelling catheter5400. The flush, i.e., purge fluid, is delivered via a lumen5403of the expandable member5407. The purge travels through the lumen5403and through a distal bearing housing5411, preventing blood flood flow into bearings of the catheter. The purge fluid flows into the distal gap5431flushing and preventing blood from filling the distal gap5431. The purge fluid travels down a second lumen5437to a proximal gap5439and flushes blood from the proximal gap5439.

FIG.55illustrates distal flush of an indwelling catheter5500according to a different embodiment. In this embodiment, the purge fluid is delivered via a purge lumen5505that is separate and distinct of the lumen for inflating the expandable member5507. The purge travels through the purge lumen5505and into a distal bearing housing5511, thereby preventing blood flood flow into bearings of the catheter. The purge fluid flows into the distal gap5531flushing and preventing blood from filling the distal gap5531. The purge fluid then travels down a second lumen5537to a proximal gap5539to flush blood from the proximal gap5539.

FIG.56shows an indwelling catheter5600with a purge system. The catheter5600includes a central lumen5603optimized for transporting purge fluid and maintaining concentricity of the catheter5600assembly. The internal structures of the central lumen5306can have various configurations some of which are detailed below in cross-sections taken through a cuff5606along line A-A.

FIG.57shows a cross-section of the central lumen5603taken along line A-A ofFIG.56according to one embodiment of the invention. In this embodiment, a purge channel5709is external to a drive shaft5711that connects a motor to an impeller of the device. Between the purge channel and the drive shaft5711is a profiled extrusion5713. The profiled extrusion5713includes a number of projections5715, for example, at least two projections5715, and preferably three projections5715, the projections5715extend outward from a central hub5717that encases the drive shaft5711. The profiled extrusion5713optimizes a purge cross sectional area and also helps to maintain assembly concentricity.

FIG.58shows a cross-section of the central lumen5603taken along line A-A ofFIG.56according to a different embodiment of the invention. In this embodiment, a purge channel5809is in association with the drive shaft5711connecting the motor to the impeller of the device. The purge channel5809is defined by a profiled extrusion5813. The profiled extrusion5813includes a number of projections5815, for example, at least two projections5815, and preferably three projections5815, the projections5815extending inward from an outer hub5817that encases the drive shaft5711. The profiled extrusion5813defines and optimizes a purge cross-sectional area and maintains assembly concentricity.

FIG.59shows a cross-section of the central lumen5603taken along line A-A ofFIG.56according to another embodiment of the invention. In this embodiment, the central lumen5603houses a coil drive shaft5905connecting the motor to the impeller of the device. A purge channel5909surrounds the coil drive shaft5905. The purge channel5909is defined by an outer hub5911that encases the coil drive shaft5905.

FIG.60shows an optimized guide surface6001of a cage inlet6003. With reference toFIG.27, the optimized guide surface6001comprises a portion of a cuff6007that tapers towards the impeller6011in harmony with an outer boundary surface6015. The optimized guide surface6001maintains axial momentum and prevents recirculation of fluid6017flowing into the cage assembly6021. In particular, the optimized guide surface6001tapers in a manner that creates a flow field convergence and minimizes fluid divergence in the inlet region6003. The optimized guide surface6001may comprise a curved tapered section. The optimized guide surface6001may be configured to smoothly reduce the cross sectional area along the length of the inlet6003. For example, the change in cross sectional area of the optimized guide surface6001along the length of the inlet6003may be less than or equal to about 1 mm2. The optimized guide surface6001may comprise a curved taper. The optimized guide surface6001may comprises a cylindrical section. The optimized guide surface6001may comprise a substantially conical section.

In some embodiments, the outer boundary surface6015tapers over at least a portion of the inlet region6003. With reference toFIG.17, the outer boundary surface6015may comprise a proximal surface of an expandable member. Alternatively, the outer boundary surface6015may comprise an inner surface of the cage.

FIG.61shows a suboptimal guide surface6105. The suboptimal guide surface6105may cause disturbances in flow6107of fluid flowing into the inlet region6111. In particular, the suboptimal guide surface6105comprises a steeper profile as compared to the optimized guide surface6017ofFIG.60. The steeper profile causes changes in axial momentum and fluid divergence of blood flowing into the inlet region6111. These disturbances in flow6107are prevented by with the optimized guide surface6017.

FIG.62shows a cage inlet6201. Illustrated is an optimal configuration where fluid flow6207is aligned with the inlet6201along an optimized guiding surface6017. The flow6207is primarily in the X-direction with no rotational component which promotes a smoothly flowing inlet6201.

FIG.63shows a suboptimal inlet6301configuration. This suboptimal configuration includes a steep guide surface6105that causes recirculation and stalls the flow in the inlet. A rotational component of the velocity dominates and carries the flow underneath the inlet struts6215. This phenomenon creates disrupted flow6217in the inlet6301and reduces the effectiveness of the inlet6301to guide flow towards the impeller.

INCORPORATION BY REFERENCE

References and citations to other documents, such as patents, patent applications, patent publications, journals, books, papers, web contents, have been made throughout this disclosure. All such documents are hereby incorporated herein by reference in their entirety for all purposes.

EQUIVALENTS

Various modifications of the invention and many further embodiments thereof, in addition to those shown and described herein, will become apparent to those skilled in the art from the full contents of this document, including references to the scientific and patent literature cited herein. The subject matter herein contains important information, exemplification and guidance that can be adapted to the practice of this invention in its various embodiments and equivalents thereof.