Patent Description:
This application is directed to a catheter pump for mechanical circulatory support of a heart, and related components, systems and methods. In particular, this application is directed to reliable coupling of components that are subject to dynamic loads applied between a plurality of catheter bodies.

Heart disease is a major health problem that has high mortality rate. Physicians increasingly use mechanical circulatory support systems for treating heart failure. The treatment of acute heart failure requires a device that can provide support to the patient quickly. Physicians desire treatment options that can be deployed quickly and minimally-invasively.

Intra-aortic balloon pumps (IABP) are currently the most common type of circulatory support devices for treating acute heart failure. IABPs are commonly used to treat heart failure, such as to stabilize a patient after cardiogenic shock, during treatment of acute myocardial infarction (MI) or decompensated heart failure, or to support a patient during high risk percutaneous coronary intervention (PCI). Circulatory support systems may be used alone or with pharmacological treatment.

In a conventional approach, an IABP is positioned in the aorta and actuated in a counterpulsation fashion to provide partial support to the circulatory system. More recently minimally-invasive rotary blood pump (see e.g. <CIT>) have been developed in an attempt to increase the level of potential support (i.e., higher flow). Rotary pumps have become more common recently for treating heart failure. A rotary blood pump is typically inserted into the body and connected to the cardiovascular system, for example, to the left ventricle and the ascending aorta to assist the pumping function of the heart. Other known applications include pumping venous blood from the right ventricle to the pulmonary artery for support of the right side of the heart. An aim of acute circulatory support devices is to reduce the load on the heart muscle for a period of time, to stabilize the patient prior to heart transplant or for continuing support. Rotary blood pumps generally utilize an electric motor which drives an impeller pump at relatively high speeds. In the case where the pump is remote from the motor, for example where the impeller is in the body and the motor is outside the body, there is a need for a robust and reliable connection between the motor and the impeller. There may also be the need for forming a flexible connection between the motor shaft and the impeller to allow free movement of various pump components during use and when pushing through the vasculature to the treatment location. There is also the continuing need to provide these system components in a compact, efficient form factor to allow for percutaneous approaches.

There is a need for improved mechanical circulatory support devices for treating acute heart failure. Fixed cross-section ventricular assist devices designed to provide partial or near full heart flow rate are either too large to be advanced percutaneously (e.g., through the femoral artery without a cutdown) or provide insufficient flow.

In one embodiment, a catheter pump includes a catheter body having at least one lumen therethrough, and comprising a distal end and a proximal end. An expandable impeller assembly includes an expandable impeller and an expandable cannula coupled to the distal end of the catheter body and housing the expandable impeller, the expandable cannula comprising a substantially straight segment having a distal inlet and a proximal outlet, the substantially straight segment configured to straddle an aortic valve. The catheter body comprises a proximal vessel contact zone and a distal vessel contact zone that are each proximal to the substantially straight segment, the proximal vessel contact zone and distal vessel contact zone configured to provide a force against an aortic arch to stabilize the expandable impeller assembly across the aortic valve.

In another embodiment, a catheter pump assembly is disclosed. The catheter pump assembly can include a pump including an impeller assembly and a catheter body disposed proximal to and supporting the pump. The catheter body can include relatively hard sections adjacent to a relatively softer middle section such that the middle section is configured to contact a wall of an aorta of a patient. The catheter body can include relatively hard sections adjacent to a relatively softer middle section such that the middle section facilitates bending relative to the relatively hard sections. The catheter body can include relatively hard sections adjacent to a relatively softer middle section such that when the pump assembly is positioned at a target location (e.g., across a valve), the middle section is configured to bend and the relatively hard sections are configured to remain substantially straight.

In accordance with the invention, a catheter pump assembly is disclosed. The catheter pump assembly includes a pump including an impeller assembly. A catheter body is disposed proximally of and configured to couple with the impeller assembly, the catheter body having a vessel wall contact surface, the catheter body configured to cause the vessel wall contact surface to bear against an outer radius of an aortic arch. A bending section is disposed between the vessel wall contact surface and the impeller assembly, the bending section being more flexible than the catheter body at the location of the vessel wall contact surface such that loads applied distal the vessel wall contact surface result in flexing at the bending section.

In another embodiment, a method is disclosed. The method can include advancing a distal portion of a catheter assembly including an impeller assembly and a catheter body to a treatment location of a patient. The method include contacting an outer surface of the catheter body with a contact zone of an inner wall of an aorta of the patient to secure at least the distal portion of the catheter assembly against the aorta of the patient, the inner wall being located adjacent to the junction of the ascending aorta and the aortic arch. The method can include activating the impeller assembly to pump blood across the aortic valve. The method can include maintaining the contact between the outer surface of the catheter body and the contact zone while the impeller assembly is activated.

An aspect of at least one of the embodiments disclosed herein is the realization that the connection of a flexible proximal body to a more rigid distal segment of a catheter assembly can be better secured with an robust mechanical interface between one or more features of these components. For example, a distal end of the flexible proximal body can be fitted with a device or structure providing an interface that mechanically engages the flexible proximal body and that can be directly joined, e.g., welded, to a structure to which a load is applied.

In one embodiment, a catheter pump assembly is provided that includes an elongate polymeric catheter body, a cannula, and a tubular interface. The elongate polymeric catheter body has a proximal end and a distal end. The cannula has an expandable portion disposed distally of the elongate polymeric catheter body. The cannula can also have another tubular portion that is proximal to the distal portion. The tubular interface has an outer surface configured to be joined to the tubular portion of the cannula and an inner surface. The inner surface is disposed over the distal end of the elongate polymeric catheter body. The tubular interface has a plurality of transverse channels extending outward from the inner surface of the tubular interface. An outer surface of the elongate polymeric catheter body projects into the transverse channels to mechanically integrate the elongate polymeric catheter body with the tubular interface.

In another embodiment, a catheter pump assembly is provided that includes an elongate polymeric catheter body, a tubular member, and a mechanical interface. The elongate polymeric catheter body has a proximal end and a distal end. At least a portion of the tubular member is disposed distally of the elongate polymeric catheter body. The mechanical interface is disposed between a portion of the elongate polymeric catheter body and the tubular member. The mechanical interface is configured to mechanically integrate with a surface of the elongate polymeric catheter body.

In another embodiment, a catheter pump assembly is provided that includes an elongate catheter body, a metallic tubular member, and first and second mechanical interfaces. The elongate catheter body has a proximal portion and a distal portion. The metallic tubular member is disposed at least partially distally of the elongate catheter body. The first mechanical interface has a first portion joined to the distal portion of the elongate catheter body and a second portion welded to the metallic tubular member. The second mechanical interface is disposed on an outside surface of the catheter pump assembly. The second mechanical interface has a deflectable member configured to be disposed adjacent to the outside surface of the catheter pump assembly in a first configuration. The deflectable member is configured to be disposed inward of the outside surface of the catheter pump assembly in a second configuration. When in the second configuration, the deflectable member mechanically and securely engages the outside surface of the catheter pump assembly with a structure disposed inward of the second mechanical interface.

In another embodiment, a method is provided for coupling components of a catheter pump assembly together. An elongate polymeric tubular body is provided that has a proximal end and a distal end. A metallic tubular body is provided that has a proximal portion and a distal portion. A mechanical interface having a first interface zone and a second interface zone is positioned such that the first interface zone is disposed over a portion of the elongate polymeric tubular body adjacent to the distal end thereof. The polymer is then caused to flow into the first interface zone, whereby the elongate polymeric tubular body becomes joined with the first interface zone of the mechanical interface. The metallic tubular body is coupled with the second interface zone of the mechanical interface.

In one approach, the polymer is caused to flow by heating the elongate polymeric tubular body to cause at least a portion of elongate polymeric tubular body adjacent to the distal end thereof to transition to a state with low resistance to deformation.

In another embodiment, a catheter pump assembly is provided that includes a proximal portion, a distal portion, and a catheter body having a lumen extending therebetween along a longitudinal axis. The catheter pump assembly also includes a torque assembly that has a first portion disposed in the lumen of the catheter body and a second portion disposed distal of the first portion. The second portion coupled with an impeller. The torque assembly causes the impeller to rotate upon rotation of the first portion of the torque assembly. The catheter pump assembly also includes a thrust bearing and a thrust bearing brace. The thrust bearing is disposed within the catheter pump assembly adjacent to the distal end of the catheter body. The thrust bearing resists movement of the torque assembly along the longitudinal axis. The thrust bearing brace is disposed on the outside surface of the torque assembly. The thrust bearing brace has a distal face that is directly adjacent to a proximal face of the thrust bearing.

In another embodiment, a catheter assembly is provided that includes an elongate flexible body, a torque assembly, a bearing assembly, and a sleeve. The elongate flexible body is disposed along a proximal portion of the catheter assembly and has a proximal infusate channel formed therein. The torque assembly extends through the elongate flexible body. The bearing assembly comprises a housing having an outer surface and a bearing surface disposed within the housing. The bearing surface provides for rotation of the torque assembly within the bearing housing. The sleeve comprises and an inner surface configured to be disposed over the outer surface of the housing of the bearing assembly and a fluid communication structure that extends through the walls of the sleeve. The catheter assembly also includes a distal infusate channel in fluid communication with the proximal infusate channel, the distal infusate channel disposed over the outer surface of the bearing housing and through side walls of the slot.

In another embodiment, a catheter pump assembly is provided that includes a proximal portion, a distal portion, and a catheter body having a lumen extending along a longitudinal axis between the proximal and distal portions. The catheter pump assembly also includes an impeller disposed at the distal portion and a stator disposed distal of the impeller to straighten flow downstream from the impeller. The stator is collapsible from a deployed configuration to a collapsed configuration.

In another embodiment, a catheter system is provided that includes an elongate polymeric catheter body, a cannula, and at least one expandable component disposed within the cannula. The elongate polymeric catheter body has a proximal end and a distal end. The cannula has an expandable portion disposed distally of the elongate polymeric catheter body. The catheter system also includes an elongate sheath body that has a retracted position in which the elongate sheath body is proximal of the expandable portion of the cannula and the at least one expandable component and a forward position in which the elongate sheath body is disposed over the expandable portion of the cannula and the at least one expandable component. A first segment of the elongate sheath body disposed over the expandable portion of the cannula and the at least one expandable component is configured to resist kinking to a greater extent than a second segment of the elongate sheath body disposed adjacent to the first segment.

An exemplary embodiment falling under the claimed invention is shown in <FIG> A more complete appreciation of the subject matter of this application and the various advantages thereof can be realized by reference to the following detailed description, in which reference is made to the accompanying drawings in which:.

More detailed descriptions of various embodiments of components for heart pumps useful to treat patients experiencing cardiac stress, including acute heart failure, are set forth below.

A high performance catheter pump is desired to provide sufficient output to approach and in some cases exceed natural heart output. Performance of this nature can be achieved with inventive components disclosed herein.

<FIG> show aspects of a catheter pump <NUM> that can provide high performance including flow rates similar to full cardiac output. The pump <NUM> includes a motor driven by a controller <NUM>. The controller <NUM> directs the operation of the motor <NUM> and an infusion system <NUM> that supplies a flow of infusate in the pump <NUM>. A catheter system <NUM> that can be coupled with the motor <NUM> houses an impeller within a distal portion thereof. In various embodiments, the impeller is rotated remotely by the motor <NUM> when the pump <NUM> is operating. For example, the motor <NUM> can be is disposed outside the patient. In some embodiments, the motor <NUM> is separate from the controller <NUM>, e.g., to be placed closer to the patient. In other embodiments, the motor <NUM> is part of the controller <NUM>. In still other embodiments, the motor is miniaturized to be insertable into the patient. Such embodiments allow the drive shaft to be much shorter, e.g., shorter than the distance from the aortic valve to the aortic arch (about <NUM> or less). Some examples of miniaturized motors catheter pumps and related components and methods are discussed in <CIT>; <CIT>; <CIT>; <CIT>.

<FIG> illustrates one use of the catheter pump <NUM>. A distal portion of the pump <NUM> is placed in the left ventricle LV of the heart to pump blood from the LV into the aorta. The pump <NUM> can be used in this way to treat patients with a wide range of conditions, including cardiogenic shock, myocardial infarction, and acutely decompensated heart failure, and also to support a patient during a procedure such as percutaneous coronary intervention. One convenient manner of placement of the distal portion of the pump <NUM> in the heart is by percutaneous access and delivery using the Seldinger technique or other methods familiar to cardiologists. These approaches enable the pump <NUM> to be used in emergency medicine, a catheter lab and in other non-surgical settings.

<FIG> shows features that facilitate small blood vessel percutaneous delivery and high performance up to and in some cases exceeding normal cardiac output in all phases of the cardiac cycle. In particular, the catheter system <NUM> includes a catheter body <NUM> and a sheath assembly <NUM>. An impeller assembly <NUM> is coupled with the distal end of the catheter body <NUM>. The impeller assembly <NUM> is expandable and collapsible. In the collapsed state, the distal end of the catheter system <NUM> can be advanced to the heart. In the expanded state the impeller assembly <NUM> is able to pump blood at high flow rates. <FIG> and <FIG> illustrate the expanded state. The collapsed state can be provided by advancing a distal end <NUM> of an elongate body <NUM> distally over the impeller assembly <NUM> to cause the impeller assembly <NUM> to collapse. This provides an outer profile throughout the catheter assembly <NUM> that is of small diameter, for example <NUM> French as discussed further below.

In some embodiments, the impeller assembly <NUM> includes a self-expanding material that facilitates expansion. The catheter body <NUM> on the other hand preferably is a polymeric body that has high flexibility. When the impeller assembly <NUM> is collapsed, as discussed above, high forces are applied to the impeller assembly <NUM>. These forces are concentrated at a connection zone, where the impeller assembly <NUM> and the catheter body <NUM> are coupled together. These high forces, if not carefully managed can result in damage to the catheter assembly <NUM> and in some cases render the impeller within the impeller assembly <NUM> inoperable. A reliable mechanical interface is provided to assure high performance. While this interface is extremely beneficial for an assembly with an expandable impeller disposed in an expandable cannula, it also applies to assemblies including a fixed diameter impeller, which may be disposed in an expandable cannula or even in a non-expandable portion in fluid communication with an expandable cannula. In one variation, the impeller is disposed proximal of an expandable cannula in a rigid segment (e.g., a pump ring) and an expandable cannula is provided. The mechanical interfaces and inner and outer sheath assemblies facilitate the collapse of the cannula in such embodiments. A further design permits the impeller to be withdrawn into a rigid structure, e.g., a pump ring, to collapse the impeller before the cannula is collapsed.

The mechanical components rotatably supporting the impeller within the impeller assembly <NUM> permit high rotational speeds while controlling heat and particle generation that can come with high speeds. The impeller may be rotated as speeds above <NUM> RPM, above <NUM> RPM, above <NUM>,<NUM> RPM, above <NUM>,<NUM> RPM, above <NUM>,<NUM> RPM, above <NUM>,<NUM> RPM, or above <NUM>,<NUM> RPM. The infusion system <NUM> delivers a cooling and lubricating solution to the distal portion of the catheter system <NUM> for these purposes. However, the space for delivery of this fluid is extremely limited. Some of the space is also used for return of the infusate. Providing secure connection and reliable routing of infusate into and out of the catheter assembly <NUM> is critical and challenging in view of the small profile of the catheter body <NUM>.

Various aspects of the pump and associated components are similar to those disclosed in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>: <CIT>;<CIT>; <CIT>; <CIT>;<CIT>;<CIT>; <CIT>; <CIT>; and<CIT>; and <CIT>.

<FIG> show a first embodiment of a working end of a catheter assembly <NUM> forming a part of one embodiment of the catheter pump <NUM>. The catheter assembly <NUM> is similar to the catheter system <NUM> except as discussed differently below. The catheter assembly <NUM> includes an elongate catheter body <NUM>. A proximal end of the catheter body <NUM> can be coupled with a motor housing. A distal portion of the catheter body <NUM> is coupled to a cannula <NUM> configured to house a high flow rate impeller <NUM>. The exemplary catheter pump can be configured to produce an average flow rate of <NUM> liters / minute or more at physiologic conditions, e.g., at the typical systolic pressure of a patient needing treatment, such as <NUM> mmHg. In various embodiments, the pump can be configured to produce a maximum flow rate (e.g., low mm Hg) of greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, or greater than <NUM> Lpm. In various embodiments, the pump can be configured to produce an average flow rate at <NUM> mmHg of greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, greater than <NUM> Lpm, or greater than <NUM> Lpm.

In some embodiments both the cannula <NUM> and the impeller <NUM> are actuatable from a first configuration for delivery through a patient to a working site to a second configuration for generating high flow at the working site. The first configuration may be a low profile configuration and the second configuration may be an expanded configuration. The low profile configuration preferably enables access via a femoral artery or other peripheral blood vessel without excessive obstruction of blood flow in the vessel, as discussed further below.

The catheter body <NUM> preferably has a plurality of lumens, including a first lumen <NUM> adapted for housing a drive shaft <NUM>, a second lumen 140B for conveying a medical fluid distally within the catheter body <NUM>, and a third lumen 140C for anchoring a bearing housing <NUM> to the catheter body <NUM>. The drive shaft <NUM> extends proximally within the catheter body <NUM> from the impeller <NUM>. The drive shaft <NUM> couples with the motor at the proximal end and with the impeller <NUM> at the distal end thereof. The drive shaft <NUM> can be formed with any suitable structure, but should be sufficient flexible to traverse at least from a peripheral (e.g., femoral) artery to a heart chamber, such as the left ventricle, as well as sufficiently durable to rotate at a high speed for several hours, for several days, and in some cases, months. The drive shaft <NUM> can be coupled with an impeller assembly <NUM> including an expandable impeller 112A) disposed on a tubular body 112B <FIG> and <FIG> shows these structures. The impeller 112A preferably includes an elastomeric polymer structure that can be formed as a unitary body. The tubular body 112B can be a metal hypotube. The tubular body 112B can be received in a distal portion of the drive shaft <NUM>.

Any suitable material or combination of materials can be used for the catheter body <NUM> or catheter bodies 104A and <NUM> discussed below and provided in some embodiments. In one embodiment, the catheter body <NUM> has an inner layer <NUM> surrounding the lumen <NUM> that comprises high density polyethylene (HDPE). For example, Marlex <NUM> HDPE can be disposed about the lumen <NUM>. If a composite structure is used to form the catheter body <NUM>, the inner layer <NUM> has a thickness that is sufficient to withstand wear caused by interaction with the drive shaft <NUM>, which can be rotated at a very high speed in some applications, for example from <NUM>,<NUM> - <NUM>,<NUM> revolutions per minute. The inner layer can have a thickness of <NUM> inches.

The second lumen 140B extends from a proximal end in fluid communication with a source of infusate, which can be a medical fluid (e.g., saline), to a distal end adjacent to the impeller assembly <NUM>. For example, the second lumen 140B can have an outlet disposed adjacent to a flow channel formed in or about the bearing housing <NUM>. Examples of bearing housing flow channels are shown in <FIG>, <FIG>, and in <CIT>. In one embodiment of the catheter body 104A, the second lumen 140B is generally circumferentially elongated, for example having two sides that are curved with an arc length of about <NUM> inches and two sides that are straight, disposed along a radial direction of the catheter body <NUM> and about <NUM> inches in length. A proximal end of the second lumen 140B is coupled with a port, which may be similar to the luer <NUM> in <FIG>, or other fluid connection device. Any suitable connection between a port and lumen can be used, e.g., a skived connection can be used.

The third lumen 140C can be used to enhance the security of the connection between the catheter body <NUM>, 104A and the bearing housing <NUM>. For example, the third lumen 140C can be sized to receive a plurality of, e.g., two, pull wires <NUM>. The pull wires <NUM> can take any suitable form, but preferably are sized to be easily received within the lumen 140C. In one embodiment, the lumen 140C is spaced apart from but about the same size as the second lumen 140B and the pull wires are generally rectangular in shape, e.g., having a thickness of about <NUM> inches and a width of about <NUM> inches. The pull wires <NUM> can be formed of any material that is sufficiently rigid in tension, e.g., of stainless steel with pull strength of at least about 300ksi. In one arrangement, the pull wires <NUM> extend at least about three inches into the elongate body <NUM> in the third lumen 140C and extend out of the third lumen 140C to overlay the bearing housing <NUM> as shown in <FIG>.

<FIG> shows one approach to compactly arranging the pull wires <NUM> and structure coupled together thereby. In particular, a proximal portion160A of the wires is received within a distal length of the third lumen 140C and a distal portion 160C of the wires is disposed distal of the catheter body <NUM>. A transition 160B is provided between the zones 160A, 160C causing the proximal portion 160A to be disposed closer to the longitudinal axis of the impeller catheter assembly <NUM> than is the distal portion 160C. This permits the outer surface of the catheter body <NUM> to be closer to the longitudinal axis of the catheter assembly <NUM> than if the pull wires were straight with the distal portion 160C in the same position as illustrated.

Providing a plurality of pull wires provides redundancy in the connection between the catheter body <NUM>, 104A and the bearing housing <NUM>. In some cases, this redundancy is not needed and a single wire can be used. The redundancy is beneficial, however, because substantial tension force is applied at this connection point when the expandable cannula <NUM> is collapsed. In one technique relative motion is provided between the catheter body <NUM>, 104A and an outer sheath disposed over the catheter body until the outer sheath slides over a proximal portion of the cannula <NUM>. Further relative motion causes the cannula <NUM> to be compressed, but not without a substantial force being applied thereto. This force is born at several points, including at the junction between the catheter body <NUM>, 104A and the bearing housing <NUM>. Disconnection of the bearing housing <NUM> would be problematic, requiring complex procedures to extract the disconnected distal working end of the catheter assembly <NUM>.

The pull wires <NUM> preferably are located close together on the same side of the catheter body <NUM>, 104A. This arrangement enhances bending flexibility, which is beneficial if tortuous vasculature must be traversed to deliver the catheter assembly <NUM> to a treatment site, e.g., a heart chamber. <FIG> illustrate other techniques for enhancing the security of the connection of the bearing housing <NUM> to a catheter body.

In some embodiments, placing a radiopaque marker on a distal portion of the catheter assembly <NUM> is advantageous to confirm the location of the working end, e.g., of the cannula <NUM> and/or impeller <NUM> prior to and/or after deployment.

Gross mechanical properties of the catheter body <NUM> can be varied along the length thereof to provide appropriate flexibility and maneuverability within the vasculature to facilitate delivery and operation of the catheter pump into which the catheter assembly <NUM> is incorporated. For example, in one embodiment, the catheter body <NUM> is stiffest near the distal end where the catheter body <NUM> is joined to the working end. In one embodiment, a distal section of the catheter body <NUM> comprises a relatively soft or flexible material, such as Pebax®. Pebax® is a thermoplastic elastomer, such as a polyether block amide, marketed by Arkema of France. In various embodiments, the material has a hardness of about 100D or less, 75D or less, 72D or less, 60D or less, or 50D or less. In various embodiments, the material has a flexural modulus of less than about <NUM> MPa, less than about <NUM> MPa, less than about <NUM> MPa, less than about <NUM> MPa, less than about <NUM> MPa, or less than about <NUM> MPa. A proximal section of the catheter body <NUM> may comprise a material, such as Vestamid®. In various embodiments the material has a hardness greater than about 40D, greater than about 50D, greater than about 60D, or greater than about 72D. In various embodiments, the material has a tensile strength of about <NUM> MPa. In various embodiments, the material has a flexural modulus of greater than about <NUM> MPa, greater than about <NUM> MPa, greater than about <NUM> MPa, greater than about <NUM> MPa, greater than about <NUM> MPa, greater than about <NUM> MPa, greater than about <NUM> MPa, or greater than about <NUM> MPa. Vestamid is a thermoplastic elastomer marketed by Evonik Industries® of Germany known to have high elasticity and good recovery. Between these relatively hard sections ends, a middle section of the catheter body comprises a material having a lower hardness. In an exemplary embodiment, the middle section is formed of MX1205 Pebax®. In an exemplary embodiment, the relatively hard sections are formed of Vestamid. The low hardness section provides a softer structure in the vicinity of the aortic arch, where the catheter may be resting on the vessel wall in use. One or more intermediate hardness sections can be provided between the distal, proximal and middle sections. These arrangements are also relevant to the other inner catheter bodies discussed herein, including bodies 104A, <NUM>. In various respects, the hardness of the material refers to the bending or torsional stiffness of the respective material. For example, in various embodiments, the relatively hard sections generally require a meaningfully higher moment before they bend relatively to the relatively softer materials. In various embodiments, the relatively hard section resist deformation in use compared to the relatively soft sections which are configured to deform (e.g., bend).

Alternately, or in addition to these features, the catheter body <NUM> can have different diameters along its length to provide several important performance benefits. The diameter of a proximal portion of the catheter body <NUM> can be relatively large to enhance pushability and trackability of the catheter assembly <NUM>. The diameter of a distal portion of the catheter body <NUM> can be relatively small to enhance flexibility of the distal tip and also to match the profile of the bearing housing <NUM> such that the lumens 140B align with flow channels at least partly defined by the bearing housing (e.g., the slots <NUM> discussed below). The enlarged diameter and enhanced hardness at the proximal end both contribute to the maneuverability of the catheter assembly <NUM>. These arrangements are also relevant to the other inner catheter bodies discussed herein, including bodies 104A, <NUM> and the catheter assemblies 100A, <NUM>, and <NUM> (discussed below).

In addition to the foregoing structures for varying the stiffness, along the length of the catheter body <NUM>, a separate stiffening component, such as a braid <NUM>, can be disposed in the catheter body <NUM>, 104A. In one embodiment, a <NUM> inch by <NUM> inch flat wire of 304V stainless steel is embedded in the catheter body <NUM>, 104A and the braid includes a <NUM> ppi configuration. The braid <NUM> can be positioned in any suitable location, e.g., between an inner layer <NUM> and an outer layer, as shown in <FIG> of the drawings.

As discussed above, the catheter assembly <NUM> preferably also includes an outer sheath or sheath assembly <NUM> provided over the elongate body <NUM>, 104A to aid in delivering, deploying and/or removing the impeller <NUM>. The outer sheath <NUM> can include an elongate body <NUM> (see <FIG>) comprising an inner surface surrounding a lumen disposed therein. The inner lumen can comprise a low friction material or layer. For example, a thickness of PTFE can be provided adjacent the inner lumen. In one embodiment, one or more separate materials can be provided at an outer surface of the elongate body <NUM>.

The elongate body <NUM> preferably is connected at the proximal end with a proximal hub and/or a suitable connector, such as a Tuohy Borst connector. The proximal hub can include a luer fitting.

The outer sheath <NUM> also may have varied hardness or other gross mechanical properties along its length to provide appropriate flexibility and maneuverability within the vasculature to facilitate delivery and operation of the catheter pump into which the outer sheath is incorporated, and also to facilitate collapse of the cannula <NUM> after deployment thereof. <FIG> illustrates schematically bulk property variation in two embodiments of the sheath assembly <NUM>. In particular, an elongate body extending between the proximal and distal ends of the sheath assembly <NUM> has different hardness at different locations along the length. The different hardnesses enhance the maneuverability of the sheath assemblies 88A, 88B to minimize kinking of the elongate body as the catheter assembly <NUM> is tracking toward the heart and/or when the elongate body is used to collapse an expandable cannula or impeller, as discussed elsewhere herein.

The elongate body of the sheath assembly 88A has a proximal portion "A" with a highest hardness. The proximal portion A can comprise vestamid or other similar material. A portion "B" distal of the proximal portion A and residing over a zone of the cannula in which the impeller I and the distal bearing support S (if present) are housed can have a hardness that is lower than that of the portion A. Portion B can comprise 55D pebax. In some embodiments, as discussed further below a segment of portion B can act as a radiopaque marker for the sheath during delivery and/or removal of the catheter pump from the patient. A portion "C" disposed distal of the portion B can comprise a material with the lowest hardness of the elongate body of the sheath assembly 88A, e.g., can comprise MX1205. A portion "D" at the distal end of the elongate body of the sheath assembly 88A can have a relatively high hardness, e.g., 72D pebax. The sheath assembly 88A upon distal movement over the expanded cannula initially contacts the cannula with the relatively hard material of portion D. The relatively soft portion C may contact the vasculature as the catheter assembly <NUM> is advanced, and its relatively soft structure is biocompatible. Portion B has a hardness that is high enough to protect the zones I and S of the cannula, impeller, and support. Portion A is the hardest of the materials used in the sheath assembly 88A, to aid in maneuverability.

The elongate body of the sheath assembly 88B has a proximal portion and distal bearing zone portion "A" with a highest hardness. The proximal portion A can comprise vestamid or other similar material. A portion "B" between the proximal portion A and the distal bearing zone portion A. The portion B resides adjacent to the transition from the catheter body <NUM> to the cannula proximal portion <NUM> and can have a hardness that is lower than that of the portion A. Portion B can comprise 55D pebax. Portions C and D in the sheath assembly 88B are the same as in the sheath assembly 88A. A portion E is disposed between the portions A and C, e.g., distal of the portion A disposed over the distal bearing support. Portion E can include a series of progressively softer lengths, e.g., a first length of 72D pebax, a second length of 63D pebax, and a third length of 55D pebax. Other materials and hardnesses can be used that provide good resistance to kinking in the delivery of the catheter assembly <NUM> and/or in the process of re-sheathing the expanded cannula and impeller.

<FIG> is a schematic side view of a distal portion of a catheter assembly <NUM>', in accordance with various embodiments. As with the embodiments described above, the catheter assembly <NUM>' can comprise an impeller assembly <NUM> having an impeller <NUM> disposed inside an expandable and collapsible cannula <NUM>. An inlet <NUM> and an outlet <NUM> can be defined in the cannula <NUM>, such that during operation of the catheter assembly <NUM>', the impeller <NUM> draws blood into the cannula <NUM> by way of the inlet <NUM> and expels blood out of the cannula <NUM> by way of the outlet <NUM>. An atraumatic tip <NUM> can be disposed distal the cannula <NUM>, and can be configured to provide an atraumatic contact interface when the tip <NUM> contacts the anatomy. As explained above, a sheath assembly <NUM>' can be disposed about a catheter body <NUM>, within which are provided one or more supply and waste lumens and a drive shaft that imparts rotation to the impeller <NUM>.

<FIG> is an enlarged view of the sheath assembly <NUM>' shown in <FIG>. The sheath assembly <NUM> can comprise a catheter body having an internal lumen. As shown in <FIG>, and as explained herein, the sheath assembly <NUM>' can be translated proximally P relative to the impeller assembly <NUM> to expose the impeller assembly <NUM>. As the impeller assembly <NUM> is exposed from the proximally sliding sheath assembly <NUM>' (or by relative motion between the sheath assembly <NUM>' and the impeller assembly <NUM> including by advancing the catheter body <NUM> relative to the sheath assembly <NUM>'), the impeller <NUM> and the cannula <NUM> can self-expand into a deployed configuration. The pump, of which the catheter assembly <NUM>' is a part, can be activated to pump blood through the cannula <NUM>. In the deployed configuration, the pump can provide improved flow rates and patient outcomes as compared with non-expandable and other smaller diameter catheter pumps. After the procedure, the sheath assembly <NUM> can be moved distally D relative to the impeller assembly <NUM> to contact the cannula <NUM> and cause the cannula <NUM> and impeller <NUM> to move to a stored configuration. Relative motion between the sheath assembly <NUM>' and the impeller assembly <NUM> including by retracting the impeller assembly <NUM> into the sheath assembly <NUM>' can also be provided. Once stored, the impeller assembly <NUM> and sheath assembly <NUM> can be withdrawn from the anatomy.

The sheath assembly <NUM>' can include a sheath body <NUM> that defines an interior lumen in which the impeller assembly <NUM> is stored during insertion and/or removal of the catheter assembly <NUM>' from the anatomy. As shown in <FIG>, the sheath body <NUM> can comprise a multi-layered structure of different materials. For example, an inner liner <NUM> can be provided to enable reduced friction during use. For example, the liner <NUM> can comprise a material with a low co-efficient of friction, such as one or more of a suitable polymer, such as polytetrafluoroethylene (PTFE). The sheath assembly <NUM>' can comprise an outer jacket <NUM> disposed about the inner liner <NUM>. The inner liner <NUM> can have a wall thickness sufficiently small so as to enable flexibility during use. The wall thickness of the inner liner <NUM> can be in a range of <NUM> inches to <NUM> inches, in a range of <NUM> inches to <NUM> inches, or in a range of <NUM> inches to <NUM> inches, e.g., about <NUM> inches.

As explained above with respect to <FIG>, the outer jacket <NUM> can be formed of a plurality of materials having different stiffnesses (e.g., varying along a length of the sheath assembly <NUM>') and/or elasticities to reduce kinking during use of the catheter assembly <NUM>. For example, the outer jacket <NUM> can comprise one or more of MX1205, Pebax 55D, Pebax 72D, and Vestamid. In one embodiment Vestamid is provided in a proximal portion 153A that extends from a proximal end of the outer jacket <NUM> to a location adjacent to the distal end. The proximal portion 153A has stiffness configured for advancing the catheter assembly <NUM>' to the heart by way of the aorta. A braided structure <NUM> can be provided along at least a portion of the length of the sheath assembly <NUM>' to provide reinforced mechanical strength, e.g., improved longitudinal or axial strength and improved radial strength. In one embodiment a stiffness contribution by the braided structure <NUM> varies along the length of the sheath assembly <NUM>', for example providing a denser braid in the proximal portion 153A than in portions of the sheath assembly <NUM>' distal the proximal portion 153A. The braided structure <NUM> can be provided radially between the outer jacket <NUM> and the inner liner <NUM> in various embodiments. In various other embodiments, the braided structure <NUM> can be integrated or embedded within the outer jacket <NUM> or within the inner liner <NUM>. The braided structure <NUM> can comprise a matrix or mesh of metallic material that is shaped in a tubular profile. In various embodiments, the braided structure <NUM> can comprise stainless steel, for example stainless steel 304V full hardness. The inner diameter of the sheath body <NUM> can be in a range of <NUM> inches to <NUM> inches, e.g., in a range of <NUM> inches to <NUM> inches (for example, about <NUM> inches). The outer diameter of the sheath body <NUM> can be in a range of <NUM> inches to <NUM> inches, or in a range of <NUM> inches to <NUM> inches, e.g., about <NUM> inches. A length of the sheath body <NUM> can be in a range of <NUM> to <NUM>, or in a range of <NUM> to <NUM>, e.g., about <NUM> +/- <NUM>.

The sheath assembly can include a distal tip <NUM> at the distalmost end of the sheath assembly <NUM>', such that the distal tip <NUM> contacts the proximal portion of the cannula <NUM> (e.g., contacts the cannula mesh at or near the outlet <NUM>) when the sheath assembly <NUM>' is urged distally D to collapse the impeller assembly <NUM>. Beneficially, the distal tip <NUM> can comprise a material that is suitably flexible so as to expand outwardly to accommodate forces imparted on the tip <NUM> by the wall of the cannula <NUM>. For example, when the distal tip <NUM> is urged distally D over the cannula <NUM>, the cannula <NUM> may impart radially outward forces to the distal tip <NUM>. The tip <NUM> can be sufficiently flexible as to accommodate the radially outward forces without excessively yielding or breaking, but may be sufficiently stiff so as to ensure collapse of the cannula <NUM>. For example, the distal tip <NUM> can expand radially outward to receive the cannula <NUM>, and portions of the jacket <NUM> directly proximal the tip <NUM> may provide a stiffer collapsing portion so as to cause the cannula <NUM> and impeller <NUM> to collapse into the sheath assembly <NUM>'. In various embodiments, the distal tip <NUM> can be made of an elastic polymer, such as PTFE. In other embodiments, the distal tip can include a combination of materials including PEBAX. In one arrangement, a PEBAX cylindrical member is joined to a proximal portion of a distal-most portion 153E by a folded over zone of the liner <NUM>. In other words, the liner <NUM> can be disposed on the inside of the sheath assembly <NUM>' and a length of the liner can be folded over and around the PEBAX cylindrical member such that the end of the liner <NUM> can be disposed proximal of the distal end of and around radially outward of the inside lumen of the sheath assembly <NUM>'. In some embodiments, the outer diameter of the distal tip <NUM> can be slightly smaller than the outer diameter of the sheath body <NUM>. The outer diameter of the distal tip <NUM> can be in a range of <NUM> inches to <NUM> inches, or in a range of <NUM> inches to <NUM> inches, for example about <NUM> inches.

In addition, the sheath assembly <NUM>' can comprise one or more position markers 155a, 155b, 155c that are configured to indicate to the clinician the position and/or orientation of the impeller assembly <NUM>. A second portion 153B of the sheath body <NUM> disposed distal the proximal zone 153A can extend from proximal of the markers 155b, 155c to distal thereof. The second portion 153B can be configured with less stiffness than the proximal portion 153A. The second portion 153B can have a portion of the braided structure <NUM> that is less stiff, e.g., lower braid density, than the portion of the braided structure <NUM> in the proximal portion 153A. The second portion 153B can comprise a material that is less stiff than the material in the proximal portion 153A. The second portion 153B can be formed of 55D PEBAX. <FIG> shows that the second portion 153B can span the location of the markers 155b, 155c. A third portion 153C disposed distal the second portion 153B can have a lesser stiffness than in the second portion 153B. Any technique for providing a less stiff configuration in the third portion 153C can be provided as discussed above. The third portion 153C can extend from the second portion to a proximal end of the marker 155a. A fourth portion 153D can correspond to the marker 155A. The fourth portion 153D can have any suitable configuration. In one embodiment, the fourth portion 153D is stiffer than the third portion 153C. In one embodiment, the fourth portion 153D has the same stiffness as the second portion 153B.

The position markers 155a-155c can comprise radiopaque markers that are visible to the clinician using, for example, an x-ray fluoroscope. The position markers 155a-155c can comprise a Pebax 55D material with a radiopaque component, such as <NUM>% tungsten. The distal-most marker 155a can be used during delivery of the catheter assembly <NUM> to provide the clinician with an estimated real-time position of the distal portion of the catheter assembly <NUM> as the catheter assembly <NUM> is inserted into, or removed from, the anatomy of the patient. For example, the clinician can view the distal-most marker 155a in real-time on a display device to guide the catheter assembly <NUM> to the treatment location. The middle marker 155b and the proximal marker 155c can be used to position the catheter assembly <NUM> relative to the treatment region to provide accurate of the catheter assembly <NUM> prior to unsheathing the cannula <NUM>. For example, in some embodiments, the clinician can view the middle and proximal markers 155b, 155c to ensure that the markers 155b, 155c are near (e.g., are straddling) the aortic valve before initiation of a left ventricular assist procedure.

<FIG> are fluoroscopic views of an example method for deploying the catheter assembly <NUM>' in connection with operating a pump. In <FIG> a catheter C is positioned on the aorta side of the aortic valve and contrast is injected into the aorta to identify the location of the aortic valve AV. <FIG> shows that hereafter, the catheter assembly <NUM>' is advanced into the patient, up the descending aorta AD, down the ascending aorta AA and into the heart across the aortic valve AV. In one technique, the position of the marker 155a can be confirmed to be in the left ventricle. The position of the proximal two marker bands 155b, 155c can be confirmed to be at the aortic valve AV. In one technique, the band 155b can be distal the valve AV and the band 155c can be proximal the valve. The band 155a can be disposed over the inlet <NUM> and the bands 155b, 155c can be at or distal to the outlet <NUM>.

<FIG> shows that after the catheter assembly <NUM>' is positioned across the aortic valve AV and when so positioned, the catheter assembly <NUM>' follows the outer radius of the aortic arch AAr.

<FIG> shows that following the deployment of the catheter assembly <NUM>' across the ventricle, the catheter assembly <NUM>' provides for proper positioning and orienting across the aortic valve. For example, it may be desired to provide a substantially straight segment <NUM> from proximal to the outlets <NUM>, through the aortic valve AV and into the ventricle. The straight segment <NUM> can include the location of the impeller <NUM> in one embodiment. The straight segment <NUM> can extend proximally and distally of the impeller <NUM> in one embodiment. In accordance with the invention, the configuration of the catheter assembly <NUM>' provides that a bending zone or bending section <NUM> is disposed proximal of the straight segment <NUM>. The bending zone <NUM> can be disposed distally of a distal vascular contact zone DVZ. The distal vascular contact zone DVZ can correspond to where an outside surface of the sheath body <NUM> contacts the wall of the ascending aorta. The vascular contact zone DVZ is located at or between the junction between the ascending aorta and the aortic arch such that the straight segment <NUM> is not required to bend to reach the aortic valve AV.

Further stability of the catheter assembly <NUM>' can be provided by a technique in which a proximal vessel contact zone PVZ is provided. The proximal vessel contact zone PVZ can be located at or distal the junction of the aortic arch and the descending aorta. The catheter assembly <NUM>' is configured by the stiffness and/or the resilience of the components thereof to generate a restoring force. The restoring force can arise due to stiffness of, the elasticity of, or the stiffness and the elasticity of the catheter assembly <NUM>' when the curved shaped is formed when the normally straight catheter assembly <NUM>' is deployed around the outer radius of the aortic arch. The restoring force can act on the walls of the aorta to provide an additional stabilizing force to help retain the catheter assembly <NUM>' in place around the outer radius of the aortic arch. This force combined with focusing the flex point between the distal contact zone DVZ and the outlet <NUM> provide greater stability of the working elements and outflow of the catheter pump.

As shown in <FIG>, for left ventricular assist procedures, the impeller assembly <NUM> can be positioned so that it straddles the aortic valve AV, with the inlet <NUM> disposed in the left ventricle LV and the outlet <NUM> disposed in the aorta Ao. The impeller assembly <NUM> can be activated to pump blood proximally from the left ventricle LV through the inlets <NUM> and into the cannula <NUM>. Blood can be ejected through the outlet <NUM> and into the aorta Ao. During pumping, it can be important to maintain the impeller assembly <NUM> at a relatively stable position relative to the aorta <NUM> and aortic valve <NUM>. Stability can be provided by the structures and techniques discussed above. Stable positioning can have a number of benefits including maintaining the pumping effectiveness of the catheter pump. Stability can reduce uncontrolled and repeated impact on the walls of the aorta in the aortic arch. Stability can reduce or eliminate the motion of the distal portion of the catheter assembly <NUM>' within the anatomy. Furthermore, the position of the inlet <NUM> and outlet <NUM> straddling the aortic valve AV can be maintained. That is, if the distal portion of the catheter assembly <NUM>' is mobile within the anatomy, there is a risk that both the inlet <NUM> and the outlet <NUM> will be in the aorta during some or all of the operation of the pump or the inlet <NUM> and the outlet <NUM> will be in the left ventricle LV during some or all of the operation of the pump. These conditions can prevent direct pumping from the heart and reduce the effectiveness of the heart pump.

Beneficially, the outer sheath assembly <NUM>' disclosed herein can have a variable stiffness along its length, as explained herein, which can enable the sheath assembly <NUM>' to bear gently but consistently against one or both of the proximal contact zone PVZ and the distal contact zone DVZ during operation of the catheter pump. In contrast, conventional catheter based heart pump devices are much more flexible and move cyclically from the outer radius of the aortic arch to the inner radius thereof, and then back to the outer radius. Advantageously, the sheath assembly <NUM>' can contact one or both of the distal and proximal contact zones DVZ, PVZ to maintain the position of the impeller assembly <NUM> during operation. This improvement over conventional catheter based heart pump helps to maintain stable relative position of these components, e.g., providing a more consistent tip-gap between an outer tip of the blades of the impeller <NUM> and the inner wall of the cannula <NUM>. This improvement over conventional catheter based heart pump devices also provides more consistent and predictable interaction between the atraumatic tip <NUM> and the inner walls of the ventricle to reduce any adverse side effects of disposing the distal portion of the catheter assembly <NUM>' within the left ventricle.

<FIG> incorporate the discussion above and illustrate additional features and embodiments. <FIG> and <FIG> illustrate aspects of a mechanical interface between a bearing housing 146A and the catheter body 104A. In particular, a coupler <NUM> is provided between the bearing housing 146A and the catheter body 104A. The coupler <NUM> (also shown in <FIG>) is similar to the coupler <NUM> disclosed in <CIT>. In this configuration a thrust bearing <NUM> is provided in the bearing housing 146A. In some embodiments, a thrust bearing brace <NUM> is disposed just proximal of the thrust bearing <NUM>. The thrust bearing brace <NUM> can take any suitable form, but preferably provides a shoulder or other radial protrusion from the outer surface to the impeller shaft 112B that abuts a proximal face of the thrust bearing <NUM>. The thrust bearing brace <NUM> minimizes or completely prevents movement of the thrust bearing <NUM> on the impeller shaft 112B. Such movement is possible because the impeller on the impeller shaft 112B generates significant distally oriented thrust. In some assemblies, the thrust bearing <NUM> is interference fit onto the impeller shaft 112B. When sized and fit properly, this connection maintains the relative position of thrust bearing <NUM> to the impeller shaft 112B under the thrust forces that are applied. The thrust bearing brace <NUM> provides redundancy of this connection. In one embodiment, the thrust bearing brace <NUM> comprises a short hypotube that is coupled with, e.g., laser welded to the impeller shaft 112B. The weld completely prevents relative axial movement between the impeller shaft 112B and the thrust bearing brace <NUM>. The abutment between the trust bearing <NUM> and the thrust bearing brace <NUM> prevent relative movement between the thrust bearing <NUM> and impeller shaft 112B if the coupling between the impeller shaft 112B and the thrust bearing <NUM> loosens.

<FIG> shows that an outer surface of the bearing housing 146A can be covered by a cylindrical sleeve <NUM>. The sleeve has at least one slot <NUM> formed therein. The slot <NUM> can be circumferentially aligned to or otherwise in fluid communication with the second lumen 140B such that infusate fluid flowing distally in the lumen enters the slot and can be directed distally in a space formed between the bearing housing 146A, the sleeve <NUM> and an outer sleeve, that may be a proximal portion <NUM> of the frame-like structure of the cannula <NUM>. This structure is shown in <FIG> and <FIG>. In <FIG>, the cannula <NUM> is displaced proximally to reveal the sleeve <NUM>, which would be covered by a proximal cylindrical portion <NUM> of the cannula <NUM> when the catheter assembly <NUM> is assembled. A difference between the impeller assembly/catheter body interface of the embodiment of <FIG>and the embodiment of <FIG> is that the sleeve 216A includes recess 220A in fluid communication with the lumen 140B. The recesses 220A are fluid flow structures. Other ports into the inside of the bearing housing 146A can be accessed through apertures <NUM> that do not extend to the proximal end of the sleeve <NUM>. The apertures are fluid communication structures through which fluid can flow into the bearing housing. Flow from the lumen 104B to the apertures <NUM> can be provided through a circumferential space defined between the outer surface of the sleeve <NUM> and an inner surface of the proximal portion <NUM> of the cannula <NUM>. In some cases, the apertures <NUM> are additionally or alternately adapted to receive components of secondary mechanical interface discussed below. In other embodiments, troughs are formed in an outer surface of the bearing housing are enclosed by the inner surface of the sleeve <NUM> to form enclosed flow channels for infusate.

Catheter pumps incorporating the catheter assembly and variation thereof can be configured to deliver average flow rates of over <NUM> liters/minute for a treatment period. For example, a treatment period can be up to <NUM> days for acute needs, such as patient in cardiogenic shock. Catheter pumps incorporating the catheter assembly <NUM> or such modifications thereof can be used for shorter periods as well, e.g., for support during high risk catheter or surgical procedures.

Also, catheter pumps incorporating the catheter assembly <NUM> or modifications thereof can be used for left or right side heart support. Example modifications that could be used for right side support include providing delivery features and/or shaping a distal portion that is to be placed through at least one heart valve from the venous side, such as is discussed in <CIT>; <CIT>; and <CIT>. For example, the catheter assembly <NUM> or modifications thereof can be configured to be collapsed to be deliverable through a <NUM> French introducer sheath and can be expanded to up to <NUM> French when deployed. In one embodiment, the outer profile of the catheter assembly <NUM> or modifications thereof is approximately <NUM> French, but can be any size that is insertable into a femoral artery without requiring surgical cutdown. The catheter assembly <NUM> can be as large as <NUM>. 5F to be inserted through a 13French introducer sheath. One method involves deployment of the cannula <NUM>, having an expandable nitinol structure, across the aortic valve. In this position, the impeller <NUM> can be disposed on the aorta side of the valve and a distal length of the cannula <NUM> within the ventricle.

In other embodiments, the outer profile of the catheter assembly <NUM> or modifications thereof is less than <NUM> French, e.g., about <NUM> French. The <NUM> French configuration can be useful for patients with lower flow needs, e.g., about <NUM> liters per minute or less at physiologic conditions. In another example, an <NUM> French configuration can be useful for patients with lower flow needs, e.g., about <NUM> liters per minute or less at physiologic conditions.

<FIG>illustrate additional embodiments in which the structural integrity of a catheter assembly <NUM> is enhanced to provide security in connection with sheathing an expandable portion. <FIG> shows that a distal portion of the catheter assembly <NUM> includes components similar to those hereinbefore described. In particular, the catheter assembly <NUM> includes a catheter body <NUM>, an expandable cannula <NUM> and an expandable impeller <NUM>. The catheter body can take any suitable form. In one embodiment, the catheter body <NUM> has variable hardness along its length.

The cannula <NUM> includes a self-expanding structure enclosed in a polymeric film. The self-expanding structure can be a distal portion of a member having a non-expanding tubular portion <NUM> proximal of the self-expanding structure. The tubular portion <NUM> plays a role in anchoring the cannula <NUM> to the catheter body <NUM>.

<FIG> shows that a support member <NUM> can be positioned within the cannula <NUM> to prevent unacceptable variance in the gap between the tip of the impeller <NUM> and the inside surface of the cannula. More details of this structure are set forth in <CIT>. Successful collapse of the cannula <NUM>, the impeller <NUM>, and the support <NUM> focuses forces on a joint between the cannula <NUM> and the catheter body <NUM>.

<FIG> illustrate features that enhance the security of the connection catheter body <NUM> and the cannula <NUM>. In <FIG>, no separate structure is shown between the catheter body <NUM> and the non-expanding tubular portion <NUM>. These structures are joined in other manners, such as indirectly by the force transfer capability of the pull wires discussed above and/or by an adhesive. In <FIG>, the distal end of the catheter body <NUM> is coupled with a ferrule <NUM>. The ferrule <NUM> is an example of a structure to mechanically join the catheter body <NUM> to the cannula <NUM>. In one embodiment, the ferrule <NUM> includes a distal zone <NUM> for mechanically joining the ferrule <NUM> to the catheter body <NUM>. The distal zone <NUM> is also configured to mechanically couple with the cannula <NUM>, for example by welding. A plurality of apertures <NUM> is provided in one embodiment for mechanically joining the ferrule <NUM> to the catheter body <NUM>. The apertures <NUM> enable the material of the catheter body <NUM> to extend into the distal zone <NUM>. In one technique the ferrule <NUM> is disposed over the catheter body <NUM> which extends into the apertures <NUM>.

The apertures <NUM> can be arranged in multiple zones. In one embodiment a first zone is disposed distally of the second zone. The first zone can be disposed adjacent to the distal end of the ferrule <NUM> and the second zone is disposed proximal of the first zone. The first zone can include four apertures 344A spaced evenly about the periphery of the body of the ferrule. The second zone can include a plurality of (e.g., four) apertures 344B spaced evenly about the periphery of the body of the ferrule <NUM>. A specific advantageous embodiment provides four apertures 344B in the second zone. The apertures 344B of the second zone can be spaced evenly about the body of the ferrule <NUM>. Preferably the apertures <NUM> of the first and second zones are offset to provide a great deal of redundancy in the security of the connection of the catheter body <NUM> to the ferrule <NUM>. For example, the apertures <NUM> in the first and second zones can be offset by one-half the circumferential distance between adjacent apertures <NUM>.

The ferrule <NUM> also includes a proximal zone <NUM> disposed proximally of the aperture <NUM>. The proximal zone <NUM> preferably is configured to provide an excellent fluid seal between the ferrule and the non-expandable tubular portion <NUM> of the cannula <NUM>. In one embodiment, the proximal zone <NUM> includes a plurality of recesses <NUM> in the outer surface of the proximal portion <NUM>. The recesses <NUM> can take any form consistent with good sealing, and in one embodiment the recesses are turns of a continuous helical groove in the outer surface of the ferrule <NUM>. The helical groove is configured to receive a sealant that can bridge from the base of the grooves to the inner surface of the proximal portion <NUM> of the cannula <NUM>. In one embodiment, the sealant includes an adhesive that can flow into the helical groove and be adhered to the inner surface of the proximal portion <NUM> of the cannula <NUM>.

Although the weld and adhesive that can be formed or disposed between the ferrule <NUM> and the proximal portion <NUM> of the cannula <NUM> can provide excellent security between these components of the catheter assembly <NUM>, a supplemental securement device <NUM> can be provided in some embodiments. <FIG> illustrates one embodiment in which a mechanical securement device <NUM> is provided. The mechanical securement device <NUM> includes a cantilevered member that can be deformed from the non-expandable proximal portion <NUM> of the cannula <NUM> into corresponding recesses disposed inward of the securement device.

In one embodiment, a recess <NUM> is provided within the catheter assembly <NUM> to receive the securement device <NUM>. The recesses <NUM> can be formed in an internal structure disposed within the proximal portion <NUM>. In a first variation, a sleeve <NUM> is provided immediately within the non-expandable proximal portion <NUM> of the cannula <NUM>. The sleeve <NUM> is provided and fills the volume between a bearing housing <NUM> and the proximal portion <NUM>. The bearing housing <NUM> facilitates rotation of the impeller shaft and the flow of infusate. The sleeve <NUM> has slots and/or other fluid communication structures formed therein that direct flow from channels in the catheter body <NUM> to flow channels in the bearing housing <NUM>. In one embodiment, the sleeve <NUM> has a plurality of small apertures that are disposed between flow slots. The apertures and slots can be similar is shape and form to the apertures <NUM> and slots <NUM> discussed above.

In other embodiment, apertures can be formed in the bearing housing <NUM>. For example, the bearing housing <NUM> can have a plurality of channels aligned with flow passages in the catheter body <NUM>. In such embodiment, apertures for receiving the securement device <NUM> can be provided directly in the bearing housing <NUM>. In another variation, apertures are provided that extend through the sleeve <NUM> and into the bearing housing <NUM>.

Modifications of catheter pumps incorporating the catheter assembly <NUM> can be used for right side support. For example, the elongate body <NUM> can be formed to have a deployed shape corresponding to the shape of the vasculature traversed between a peripheral vascular access point and the right ventricle.

Any suitable manufacturing method can be used to cause a portion of the catheter body <NUM> to be disposed in the apertures <NUM>. For example, in one the catheter body <NUM> and the cannula <NUM> are to be joined. The cannula <NUM> has the tubular portion <NUM> which is to be disposed over the catheter body <NUM>. The ferrule <NUM> is a metallic body that is an important part of one form of a mechanical interface. The ferrule <NUM> has an inner surface and apertures <NUM> that act as a first interface zone and an outer surface that acts as a second interface zone. The ferrule <NUM> is positioned such that the inner surface is disposed over the outer surface of short length of the catheter body <NUM> adjacent to the distal end thereof.

In one technique, the outer surface of the catheter body <NUM> is mechanically coupled to the ferrule <NUM> by a process that involves heating. The distal portion of the catheter body <NUM> and the ferrule <NUM> are heated sufficiently to cause at least a portion of the catheter body to transition to a state with low resistance to deformation. The low resistance state can be a fluid state or just a state in which the material of the catheter body <NUM> if more malleable. In the state having low resistance to deformation, the catheter body <NUM> flows through or protrudes into the apertures344. Because the material is formed continuously from a location inside the inner surface of the ferrule to outside the inner surface, a strong mechanical coupling is provided between these components.

The tubular portion <NUM> of the cannula <NUM> can be coupled with the ferrule <NUM> by any suitable technique. In one embodiment, the tubular portion <NUM> and the ferrule <NUM> are indirectly coupled through sleeve <NUM> discussed more below. In particular, the distal end of the ferrule <NUM> can be welded to the proximal end of the sleeve <NUM> and a second connection can be provided between the portion <NUM> and the sleeve as discussed elsewhere herein. In another embodiment, the ferrule <NUM> can be directly connected by a suitable technique, such as welding if suitable materials are provided. These structures are also illustrated in <FIG> below, which shows further details of the connection by the ferrule <NUM>.

The foregoing technique of heating the catheter body <NUM> to cause the material thereof to be coupled with the proximal portion 160A of the pull wire(s) <NUM>. Another technique for joining the pull wires <NUM> to the catheter body <NUM> is by an epoxy or other adhesive at the proximal end of the wires and/or catheter body <NUM>. A distal section of the pull wires <NUM> within the catheter body <NUM> can be left un-adhered to the catheter body, such that this section of the pull wires <NUM> can move relative to the catheter body or "float" to enhance flexibility of the distal portion of the catheter body in some embodiments. The proximal portion 160A provides a first interface zone of a mechanical interface between the catheter body <NUM> and the bearing housing <NUM>. The distal portion 160C provides a second interface zone that can be coupled with the bearing housing <NUM> by a suitable technique, such as welding. In another embodiment, the sleeve <NUM>, 216A is formed of a material to which the pull wires can be welded or otherwise mechanically secured.

<FIG> illustrates an additional optional feature that can facilitate treatment with a catheter pump including the catheter assemblies disclosed herein or any of the pumps discussed in <CIT> and <CIT>. A deployment system is provided by combining the catheter assembly <NUM> (or any other discussed or claimed herein) with a guide wire guide <NUM>. The guide wire guide <NUM> can be configured as a small elongate tubular member sized to be advanced in a lumen formed in the drive shaft <NUM>. The guide wire guide <NUM> includes a lumen that is sized to receive a guidewire (not shown). The wall thickness of the guide wire guide <NUM> is thin enough to fit within the allotted tolerance for tracking the catheter assemblies discussed herein through the vasculature. The guide wire guide <NUM> wall thickness is also thin enough to permit the guide wire guide <NUM> to be withdrawn from between the guide wire and the catheter assembly once the guidewire is in place without damaging either of these structures or disrupting the position of guidewire excessively. In various embodiments, the guide wire guide <NUM> includes a self-healing member that remains within the catheter assembly when the tubular portion is removed. The self-healing member has an end wall that re-seals when the guidewire is removed. Thus, the guide wire guide <NUM> facilitates loading the catheter assemblies onto a guidewire for a percutaneous delivery within a patient.

<FIG>show details of a catheter assembly <NUM> having a stator assembly <NUM> disposed in a distal portion thereof. The stator assembly <NUM> enhances the performance of a catheter pump including the catheter assembly <NUM>. The stator assembly <NUM> can include a stator blade body <NUM> having one or a plurality of, e.g., three, blades <NUM> extending outwardly from a central boy <NUM>. The stator blade body <NUM> is at a downstream location of the impeller <NUM>. In a percutaneous left ventricle application, the stator blade body <NUM> is disposed proximal of the impeller <NUM>. In a percutaneous right ventricle application, the stator blade body <NUM> is located distal of the impeller <NUM>. In a trans apical approach to aid the left ventricle, which might be provided through ports in the chest wall or via thoracotomy or mini-thoracotomy, the stator blade body <NUM> is disposed distal of the impeller <NUM>.

The stator blades <NUM> are configured to act on the fluid flow generated by the impeller <NUM> to provide a more optimal fluid flow regime downstream of the stator assembly <NUM>. This fluid flow regime can correspond to a more optimal fluid flow regime out of the outlet of the catheter pump. The stator blades <NUM> preferably convert at least the radial component of flow generated by the impeller <NUM> to a flow that is substantially entirely axial. In some cases, the stator blades <NUM> are configured to reduce other inefficiencies of the flow generated by the impeller <NUM>, e.g., minimize turbulent flow, flow eddies, etc. Removing the radial components of the flow can be achieved with blades that are oriented in an opposite direction to the orientation of the blades of the impeller <NUM>, for example, clockwise versus counterclockwise oriented blade surface.

While the stator blades <NUM> act on the flow generated by the impeller <NUM>, the fluids also act on the stator assembly <NUM>. For example, the stator blade body <NUM> experiences a torque generated by the interaction of the blades <NUM> with the blood as it flows past the stator assembly <NUM>. A robust mechanical interface <NUM> is provided between the central body <NUM> and a distal portion of the catheter assembly <NUM>. A bearing housing <NUM> is provided that is similar to the bearing housing <NUM>, except as described differently below. The bearing housing <NUM> includes an elongate portion <NUM> that projects into a lumen of the central body <NUM>. The elongate portion <NUM> preferably has an outer periphery that is smaller than an outer periphery of a portion of the bearing housing <NUM> immediately proximal of the elongate portion <NUM>.

This structure provides an interface <NUM> disposed between the elongate portion and the portion just distal thereto. The interface <NUM> can be a shoulder having a radial extent that is approximately equal to that of the central body <NUM>. In some embodiments, a flush surface is provided between the outer surface of the central body <NUM> and a distal outer surface of the sleeve <NUM> such that the radial extent of the shoulder of the interface <NUM> is less than that of the central body <NUM> by an amount approximately equal to the thickness of the sleeve <NUM>. The interface <NUM> can also or alternately includes an engagement feature between the inner surface of the lumen of the central body <NUM> and the outer surface of the elongate portion <NUM>. In one embodiment, the outer surface of the elongate portion <NUM> has a helical projection or groove and the central body <NUM> has corresponding and mating helical grooves or projections. These features can be or can be analogous to screw threads. Preferably the helix portion is arranged such that the torque felt by the stator assembly <NUM> generates a tightening of the engagement between the elongate portion <NUM> and the central body <NUM>. The projections or grooves in the central body <NUM> can be formed by molding the central body <NUM> over the elongate projection <NUM>.

A small gap is provided between the stator assembly <NUM> and the impeller <NUM> such that no or minimal contact is provided between these components, but the flow between the blades of these structures smoothly transitions between the blades thereof. Such an arrangement is useful in that the impeller <NUM> rotates at more than <NUM>,<NUM> RPM while the stator assembly <NUM> is stationary.

While the robust mechanical interfaces between the catheter body <NUM> and the cannula <NUM> is important to the catheter assembly <NUM> the interface is even more important in certain embodiments of the catheter body <NUM> that are actuated to a collapsed state prior to being removed from the patient. In such embodiments, the deployed working end preferably is collapsed, including the cannula <NUM>, the stator blade body <NUM>, and the impeller <NUM>. This can be done by providing distal relative motion of the sheath assembly <NUM>. The forces applied by the sheath assembly <NUM> to the catheter body <NUM>, stator blade body <NUM>, and the impeller <NUM> and focused at the mechanical joints are enhanced due to the presence of the stator blade body <NUM>.

One will appreciate from the description herein that the catheter assembly may be modified based on the respective anatomy to suit the desired vascular approach. For example, the catheter assembly in the insertion state may be shaped for introduction through the subclavian artery to the heart. The catheter pump may be configured for insertion through a smaller opening and with a lower average flow rate for right side support. In various embodiments, the catheter assembly is scaled up for a higher flow rate for sicker patients and/or larger patients.

Claim 1:
A catheter pump assembly, comprising:
a pump including an impeller assembly (<NUM>);
a catheter body (<NUM>) disposed proximally of and configured to couple with the impeller assembly (<NUM>), the catheter body (<NUM>) having a vessel wall contact surface, the catheter body (<NUM>) configured to cause the vessel wall contact surface to bear against an outer radius of an aortic arch; and
a bending section (<NUM>) disposed between the vessel wall contact surface and the impeller assembly (<NUM>), the bending section (<NUM>) being more flexible than the catheter body (<NUM>) at the location of the vessel wall contact surface such that loads applied distal the vessel wall contact surface result in flexing at the bending section (<NUM>).