Inflow cannula including expandable sleeve and methods of implanting same

Disclosed herein is an inflow cannula for an implantable blood pump assembly. The inflow cannula includes a tubular body that extends from a proximal end to a distal end. The tubular body includes a proximal portion adapted for connection to a pump housing, and a distal portion adapted for positioning within an opening formed in a heart. The inflow cannula further includes an expandable sleeve coupled to an exterior surface of the distal portion. The sleeve has a first portion coupled to the distal portion of the tubular body, and a second portion extending from the distal end of the tubular body. The second portion is deployable from a first, stored configuration to a second, deployed configuration in which the second portion expands radially to engage and conform to an endocardial surface of the heart.

BACKGROUND OF THE DISCLOSURE

a. Field of the Disclosure

The present disclosure relates generally to mechanical circulatory support systems, and more specifically relates to inflow cannulas of blood pump assemblies that include an expandable sleeve configured to alleviate risks associated with stasis or areas of low blood flow around the inflow cannula.

Ventricular assist devices, known as VADs, are implantable blood pumps used for both short-term (i.e., days, months) and long-term (i.e., years or a lifetime) applications where a patient's heart is incapable of providing adequate circulation, commonly referred to as heart failure or congestive heart failure. A patient suffering from heart failure may use a VAD while awaiting a heart transplant or as a long term destination therapy. In another example, a patient may use a VAD while recovering from heart surgery. Thus, a VAD can supplement a weak heart (i.e., partial support) or can effectively replace the natural heart's function. VADs can be implanted in the patient's body and powered by an electrical power source inside or outside the patient's body.

In certain applications, an inflow cannula of the VAD is implanted within the left ventricle of a patient's heart to supply blood from within the ventricle to a pump of the VAD. In some instances, blood flow around the inflow cannula may be reduced, resulting in areas of low blood flow or stasis. These areas of low blood flow and stasis, in combination with prothrombotic myocardium tissue around the hole formed in the patient's heart, are potential sites of thrombus formation within the ventricle.

Accordingly, a need exists for improved inflow cannulas for VADs that reduce or eliminate areas of low blood flow or stasis around the inflow cannula.

SUMMARY OF THE DISCLOSURE

The present disclosure is directed to an inflow cannula for an implantable blood pump assembly. The inflow cannula includes a tubular body that extends from a proximal end to a distal end. The tubular body includes a proximal portion adapted for connection to a pump housing, and a distal portion adapted for positioning within an opening formed in a heart. The inflow cannula further includes an expandable sleeve coupled to an exterior surface of the distal portion. The sleeve has a first portion coupled to the distal portion of the tubular body, and a second portion extending from the distal end of the tubular body. The second portion is deployable from a first, stored configuration to a second, deployed configuration in which the second portion expands radially to engage and conform to an endocardial surface of the heart.

The present disclosure is further directed to an implantable blood pump assembly that includes a housing, a rotor, a stator, and an inflow cannula. The housing defines an inlet, an outlet, and a flow path extending from the inlet to the outlet. The rotor is positioned within the flow path and is operable to pump blood from the inlet to the outlet. The stator is positioned within the pump housing and is operable to drive the rotor. The inflow cannula has a proximal portion adapted for coupling to the housing inlet, and a distal portion opposite the proximal portion. The implantable blood pump assembly further includes an expandable sleeve coupled to an exterior of the distal portion of the inflow cannula. The sleeve has a first portion coupled to the distal portion of the inflow cannula, and a second portion extending from a distal end of the inflow cannula. The second portion is deployable from a first, stored configuration to a second, deployed configuration in which the second portion expands radially to engage and conform to an endocardial surface of a heart.

The present disclosure is further directed to a method for implanting an inflow cannula within a heart of patient. The method includes positioning a distal portion of the inflow cannula within a hole formed in the heart. The inflow cannula includes an expandable sleeve that has a first portion coupled to the distal portion of the inflow cannula, and a second portion extending from a distal end of the inflow cannula. The method further includes securing the inflow cannula to the heart, and deploying the second portion of the sleeve from a first, stored configuration to a second, deployed configuration such that the second portion of the sleeve expands radially and engages and conforms to an endocardial surface of the heart.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure is directed to implantable blood pump assemblies and, more specifically, to inflow cannulas of implantable blood pump assemblies that are configured to reduce potential areas of thrombus formation within the heart following implantation of the blood pump assembly. In particular, embodiments of the inflow cannulas disclosed herein include an expandable sleeve configured to occupy or fill the space around the distal end of the inflow cannula that is positioned within a ventricle of the heart. The area occupied by the expandable sleeve might otherwise be associated with areas of low blood flow or stasis. By occupying this space, the expandable sleeve is positioned to capture or trap thrombi formed on the endocardial tissue beneath the sleeve, thereby preventing the thrombi from detaching and being released into a patient's blood stream. Additionally, embodiments of the expandable sleeves disclosed herein provide a smooth contour along the endocardial surface of the heart, and fill gaps or spaces between the distal end of the inflow cannula and the endocardial surface, thereby avoiding sharp corners or curves at the interface between the inflow cannula and endocardial wall that might otherwise result in low blood flow or stasis. The inflow cannulas of the present disclosure thereby facilitate reducing areas of low blood flow or stasis along the distal end of the inflow cannula. Additionally, embodiments of the expandable sleeves are constructed from materials that promote tissue reendothelialization along the endocardial surface, and thereby facilitate faster healing of a patient following an implant procedure.

Further, embodiments of the expandable sleeves disclosed herein have a flexible, yet resilient construction such that, when the sleeve is deployed, the sleeve is biased or forced outward against the endocardial surface of the heart. The expandable sleeves thereby facilitate preventing tissue from occluding or growing over the flow path opening at the distal end of the inflow cannula, and maintaining an open flow path through the inflow cannula. Further, by reducing the risk of tissue overgrowth, the expandable sleeves of the present disclosure facilitate reducing or minimizing the length that the inflow cannula protrudes into the heart ventricle.

Referring now to the drawings,FIG. 1is an illustration of a mechanical circulatory support system10implanted in a patient's body12. The mechanical circulatory support system10includes an implantable blood pump assembly14that includes a blood pump16, a ventricular cuff18, and an outflow cannula20. The mechanical circulatory support system10also includes an external system controller22and one or more power sources24.

The blood pump assembly14can be implemented as or can include a ventricular assist device (VAD) that is attached to an apex of the left ventricle, as illustrated, or the right ventricle, or both ventricles of the heart26. With additional reference toFIG. 2, the blood pump assembly14can be attached to the heart26via the ventricular cuff18which is sewn to the heart26and coupled to the blood pump assembly14, as described further herein. The other end of the blood pump assembly14connects to the ascending or descending aorta via the outflow cannula20so that the blood pump assembly14effectively diverts blood from the weakened ventricle and propels it to the aorta for circulation to the rest of the patient's vascular system. The VAD can include a centrifugal (as shown) or axial flow pump as described in further detail herein that is capable of pumping the entire output delivered to the left ventricle from the pulmonary circulation (i.e., up to 10 liters per minute).

FIG. 1illustrates the mechanical circulatory support system10during battery powered operation. A communication line28connects the implanted blood pump assembly14to the external system controller22, which monitors system10operation. In the illustrated embodiment, the communication line28is shown as a driveline that exits through the patient's abdomen30, although it should be understood that the blood pump assembly14may be connected to the external system controller22via any suitable communication line, including wired and/or wireless communication. The system can be powered by either one, two, or more batteries24. It will be appreciated that although the system controller22and power source24are illustrated outside/external to the patient body, the communication line28, system controller22and/or power source24can be partially or fully implantable within the patient, as separate components or integrated with the blood pump assembly14.

FIG. 3is an illustration of an implantable blood pump assembly100suitable for use in the mechanical circulatory support system10ofFIG. 1, where the blood pump assembly100is shown in an operational position implanted in a patient's body.FIG. 4is a schematic cross-sectional view of the blood pump assembly100ofFIG. 3. In the illustrated embodiment, the blood pump assembly100is a left ventricular assist blood pump assembly connected to the left ventricle LV of the heart H.

The blood pump assembly100includes a blood pump102including a circular shaped housing104having a first outer face or wall106and a second outer face or wall108. The blood pump assembly100further includes an inflow cannula110(generally, an inlet conduit) that, in the illustrated embodiment, extends from the first outer wall106of the pump housing104. When the blood pump assembly100is implanted into a patient's body, as shown inFIG. 3, the first outer wall106of the housing104is positioned against the patient's heart H, and the second outer wall108of the housing104faces away from the heart H. The inflow cannula110extends into the left ventricle LV of the heart H to connect the blood pump assembly100to the heart H. The second outer wall108of the housing104has a chamfered edge109to avoid irritating other tissue that may come into contact with the blood pump assembly100, such as the patient's diaphragm.

The blood pump assembly100further includes a stator112, a rotor114, and an on-board controller116, all of which are enclosed within the pump housing104. In the illustrated embodiment, the stator112and the on-board controller116are positioned on the inflow side of the pump housing104toward the first outer wall106, and the rotor114is positioned along the second outer wall108. In other embodiments, the stator112, the rotor114, and the on-board controller116may be positioned at any suitable location within the pump housing104that enables the blood pump assembly100to function as described herein. Power is supplied to operational components of the blood pump assembly100(e.g., the stator112and the on-board controller116) from a remote power supply via a power supply cable120.

With additional reference toFIG. 4, the pump housing104defines an inlet122for receiving blood from a ventricle of a heart (e.g., left ventricle LV), an outlet124for returning blood to a circulatory system, and a flow path126extending from the inlet122to the outlet124. The pump housing104further defines an internal compartment128separated from the flow path126, for example, by one or more dividing walls130. The pump housing104also includes an intermediate wall132located between the first outer wall106and the second outer wall108, and a peripheral wall134that extends between the first outer wall106and the intermediate wall132. Together, the first outer wall106, the dividing wall130, the intermediate wall132, and the peripheral wall134define the internal compartment128in which the stator112and the on-board controller116are enclosed.

In the illustrated embodiment, the pump housing104also includes a cap136removably attached to the pump housing104along the intermediate wall132. The cap136is threadably connected to the pump housing104in the illustrated embodiment, although in other embodiments the cap136may be connected to the pump housing104using any suitable connection means that enables the blood pump assembly100to function as described herein. In some embodiments, for example, the cap136is non-removably connected to the pump housing104, for example, by welding. The removable cap136includes the second outer wall108, the chamfered edge109, and defines the outlet124. The cap136also defines a volute138that is in fluid communication with the outlet124, and a rotor chamber140in which the rotor114is positioned. The cap136can be attached to the pump housing104using any suitable connection structure. For example, the cap136can be engaged via threads with the peripheral wall134to seal the cap136in engagement with the peripheral wall134.

The rotor114is positioned within the blood flow path126, specifically, within the rotor chamber140, and is operable to rotate in response to an electromagnetic field generated by the stator112to pump blood from the inlet122to the outlet124. The rotor defines a central aperture142through which blood flows during operation of the blood pump102. The rotor114includes impeller blades144located within the volute138of the blood flow path126, and a shroud146that covers the ends of the impeller blades144facing the second outer wall108to assist in directing blood flow into the volute138.

In the illustrated embodiment, the rotor114includes a permanent magnet148that defines the central aperture142. The permanent magnet148has a permanent magnetic north pole N and a permanent magnetic south pole S for combined active and passive magnetic levitation of the rotor114and for rotation of the rotor114. In operation, the stator112is controlled to drive (i.e., rotate) the rotor and to radially levitate the rotor114by generating electromagnetic fields that interact with the permanent magnetic poles S and N of the permanent magnet148.

Any suitable stator112can be employed to rotate the rotor114. The stator112generally includes a plurality of winding structures that generate suitable electromagnetic fields that interact with the rotor114to cause rotor114to rotate and levitate. In the illustrated embodiment, the stator112includes a plurality of pole pieces150arranged circumferentially at intervals around the dividing wall130. The example blood pump assembly100includes six pole pieces150, two of which are visible inFIG. 4. In other embodiments, the blood pump assembly100can include more than or less than six pole pieces, such as four pole pieces, eight pole pieces, or any other suitable number of pole pieces that enables the blood pump assembly100to function as described herein. In the illustrated embodiment, each of the pole pieces150includes a drive coil152for generating an electromagnetic field to rotate the rotor114, and a levitation coil154for generating an electromagnetic field to control the radial position of the rotor114.

Each of the drive coils152and the levitation coils154includes multiple windings of a conductor wound around the pole pieces150. The drive coils152and the levitation coils154of the stator112are arranged in opposing pairs and are controlled to drive the rotor and to radially levitate the rotor114by generating electromagnetic fields that interact with the permanent magnetic poles S and N of the permanent magnet148. Suitable methods for controlling the stator112and generating electromagnetic fields to rotate and radially levitate the rotor114are described, for example, in U.S. Pat. No. 9,849,224, the entire contents of which are incorporated herein by reference for all purposes. Although the drive coil152and levitation coil154are shown as separate coils in the illustrated embodiment, it should be understood that the drive coil152and levitation coil154may be implemented as a single coil configured to generate electromagnetic fields for both rotating and radially levitating the rotor114.

The inflow cannula110is attached to the pump housing104at the inlet122. The pump housing104includes suitable connecting structure at the inlet122for connecting the inflow cannula110to the pump housing104. In some embodiments, for example, the pump housing104includes a threaded sleeve that threadably engages threads on a downstream or proximal end of the inflow cannula110to connect the inflow cannula110to the pump housing104.

The on-board controller116is operatively connected to the stator112, and is configured to control operation of the pump102by controlling the supply of electrical current to the stator112and thereby control rotation of the rotor114. In some embodiments, the on-board controller116is configured to perform closed-loop speed control of the pump rotor114based on feedback received from one or more sensors (e.g., pressure sensors, flow sensors, accelerometers, etc.) included within the blood pump assembly100. The on-board controller116can be configured to control the rotor114in continuous flow operation and/or pulsatile flow operation.

The on-board controller116can include one or more modules or devices that are enclosed within pump housing104. The on-board controller116can generally include any suitable computer and/or other processing unit, including any suitable combination of computers, processing units and/or the like that may be communicatively coupled to one another (e.g., on-board controller116can form all or part of a controller network). Thus, on-board controller116can include one or more processor(s) and associated memory device(s) configured to perform a variety of computer-implemented functions (e.g., performing the methods, steps, calculations and/or the like disclosed herein). As used herein, the term “processor” refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field programmable gate array (FPGA), and other programmable circuits. Additionally, the memory device(s) of on-board controller116may generally include memory element(s) including, but not limited to, non-transitory computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s) can generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s), configure the on-board controller116to perform various functions including, but not limited to, controlling the supply of electrical current to the stator112, adjusting the speed of the rotor114, and various other suitable computer-implemented functions.

In the illustrated embodiment, the on-board controller116is implemented as one or more circuit boards156and various components carried on the circuit boards (e.g., processors and memory devices) to control operation of the pump102by controlling the electrical supply to the stator112.

A communication line (e.g., communication line28) couples the blood pump assembly100and on-board controller116to the external system controller22, which monitors system operation via various software applications. The blood pump assembly100itself may also include several software applications that are executable by the on-board controller116for various functions, such as to control radial levitation and/or drive of the rotor114of the pump assembly100during operation. The external system controller22can in turn be coupled to batteries24or a power module (not shown) that connects to an AC electrical outlet. The external system controller22can also include an emergency backup battery (EBB) to power the system (e.g., when the batteries24are depleted) and a membrane overlay, including Bluetooth capabilities for wireless data communication. An external computer that is configurable by an operator, such as clinician or patient, can further be coupled to the circulatory support system10for configuring the external system controller22, the implanted blood pump assembly100, and/or patient specific parameters, updating software on the external system controller22and/or the implanted blood pump assembly100, monitoring system operation, and/or as a conduit for system inputs or outputs.

FIG. 5is a perspective view of one exemplary embodiment of an inflow cannula200suitable for use with the blood pump assembly100ofFIG. 3and the circulatory support system10ofFIG. 1.FIG. 6is a sectional view of the inflow cannula200implanted in a patient's heart H. The inflow cannula200includes a tubular body202extending from a proximal end204to a distal end206, and an expandable tubular sleeve208coupled to the body202. As described further herein, the sleeve208is configured to occupy potential areas of low blood flow or stasis around the inflow cannula200, and thereby reduce or alleviate problems associated with prothrombotic regions of the heart H following implantation of the blood pump assembly100.

The cannula body202includes a proximal portion210adapted for connection to a pump housing, such as the pump housing104, and a distal portion212adapted for positioning within an opening or hole formed in the heart H, as shown inFIG. 6. That is, the distal portion212is sized and shaped to be received within a cored hole formed in the heart H. When the inflow cannula200is implanted in a patient, the distal portion212passes through an opening formed in the heart H. When the blood pump assembly is fully implanted into a patient, as shown inFIGS. 1 and 3for example, the proximal portion210is coupled to and/or housed within the pump housing104.

The proximal portion210has an outer diameter smaller than an outer diameter of the distal portion212in the illustrated embodiment. Further, in the illustrated embodiment, each of the proximal portion210and the distal portion212are cylindrical, although in other embodiments, one or both of the proximal portion210and the distal portion212may be shaped other than cylindrical.

As shown inFIG. 6, the inflow cannula200defines a flow path214for supplying blood from within a ventricle of the heart H (shown as the left ventricle LV inFIG. 6) to the inlet122of the pump housing104(both shown inFIG. 4). In the illustrated embodiment, the flow path214tapers radially inward from the distal end206of the cannula body202to the proximal end204of the cannula body202to form a reduced cross-sectional area along the proximal portion210.

The proximal portion210and the distal portion212of the cannula body202include respective inner surfaces216,218that define the flow path214, and respective exterior surfaces220,222.

The proximal portion210includes a suitable coupler224for coupling to the pump housing104. Suitable couplers include, for example and without limitation, threads, snap-fit couplers, quick-connect couplers, and cuff-locking mechanisms. In the illustrated embodiment, the coupler224is shown as external threads along the proximal portion210of the inflow cannula200.

In some embodiments, the inflow cannula200is coupled or otherwise secured to the heart H by a ventricular cuff226, shown inFIG. 6. The cuff226defines an opening228that receives the inflow cannula200therein. The cuff226includes a suitable coupler (e.g., a clamp (not shown inFIG. 6)) that couples the cuff226to the inflow cannula200. The cuff226may also include a locking mechanism (e.g., a cam (not shown inFIG. 6)) that secures the coupler in a closed position, thereby limiting the possibility of the cuff226accidentally becoming uncoupled from the inflow cannula200. In some embodiments, the cuff226may include a separate coupler for coupling the cuff226to the pump housing104.

In some embodiments, the ventricular cuff226is coupled to the heart H (e.g., using sutures) following a coring process that forms a hole in the patient's heart H. Further, in some embodiments, the inflow cannula200is positioned within and coupled to the heart H (e.g., via the ventricular cuff226) after the cuff226is coupled to the heart H.

It should be understood that the inflow cannula200and ventricular cuff226may have other suitable configurations without departing from some aspects of the present disclosure. Other configurations of inflow cannulas and ventricular cuffs, and techniques for coupling inflow cannulas and ventricular cuffs to a patient's heart, suitable for use with certain aspects of the present disclosure are described, for example, in U.S. Pat. No. 9,981,076, the entire contents of which are incorporated herein by reference for all purposes.

The sleeve208is coupled to the exterior surface222of the distal portion212, and is configured to expand from a first, stored configuration (shown inFIG. 7) to a second, deployed configuration (shown inFIGS. 5 and 6) to occupy a volume around (i.e., radially outward from) the distal portion212of the cannula body202, and thereby fill or occupy areas of potential stasis around the distal portion212of the cannula body202. More specifically, in the illustrated embodiment, the sleeve208extends from a proximal end230coupled to the cannula body202to a free, distal end232, and includes a first portion234coupled to the distal portion212of the cannula body202, and a second portion236extending from the distal end206of the cannula body202. The second portion236is deployable from the stored configuration to the deployed configuration in which the second portion236expands radially to engage and conform to an endocardial surface of the heart H. In the illustrated embodiment, for example, the second portion236of the sleeve208is not directly fixed to the cannula body202and is only secured to the cannula body202via the first portion234of the sleeve208. Once deployed, the second portion236of the sleeve208is therefore free to expand and conform to surfaces surrounding the distal portion212of the cannula body202, such as the endocardial surface of the heart H.

In the illustrated embodiment, the first portion234of the sleeve208is coupled to the distal portion212of the cannula body202by a plurality of crimp rings238. Two crimp rings238are shown inFIG. 5, although the sleeve208may be coupled to the cannula body202using any suitable number of crimp rings, including more than or less than two. Further, in the illustrated embodiment, the sleeve208is fixed to a distal tip240of the cannula body202along the first portion234of the sleeve208such that the first portion234of the sleeve208maintains engagement with the distal portion212of the cannula body202when the sleeve208is in the deployed configuration. Additionally, because the sleeve208is fixed to the distal tip240of the cannula body202along the first portion234of the sleeve208, the second portion236of the sleeve208unfolds about the distal tip240of the cannula body202when the sleeve208is deployed from the stored configuration to the deployed configuration, as illustrated inFIGS. 7-9. In other embodiments, the sleeve208may be coupled to the cannula body202using any suitable couplers or fasteners that enable the sleeve208to function as described herein.

In the stored configuration, shown inFIG. 7, the second portion236of the sleeve208has a smaller diameter than the first portion234of the sleeve208and the distal portion212of the cannula body202. The diameter of the second portion236of the sleeve208in the stored configuration is also smaller than the diameter of the second portion236in the deployed configuration. Prior to delivery and implanting the inflow cannula200in the heart H, the second portion236of the sleeve208can be maintained in the stored configuration to facilitate insertion of the inflow cannula200through the hole formed in the heart H. Once the inflow cannula200is inserted through the hole and secured or coupled to the heart H, the second portion of the sleeve208can be deployed to the deployed configuration.

With reference toFIG. 7, a retainer242is coupled to the distal end232of the sleeve208to maintain the sleeve208in the stored configuration. In the illustrated embodiment, the retainer242is a retaining ring that extends around the distal end232of the sleeve208. In other embodiments, the retainer242can generally include any suitable retaining mechanism that enables the sleeve208to function as described herein. In some embodiments, for example, the inflow cannula200can include a cap fitted around the distal end232of the sleeve208.

Further, in the illustrated embodiment, a release mechanism244is coupled to the retainer242and is operable to release the retainer242from the distal end232of the sleeve208to allow the second portion236of the sleeve208to deploy from the stored configuration to the deployed configuration. In the illustrated embodiment, the release mechanism244is shown disposed outside of the cannula body202and the sleeve208, although in other embodiments, the release mechanism244may be disposed within the sleeve208and/or the cannula body202. In one embodiment, for example, the release mechanism244extends from the distal end232of the sleeve208, through the flow path214defined by the cannula body202, and out of the proximal end204of the cannula body202. In the illustrated embodiment, the release mechanism244is a release line constructed of a wire or thread of material, such as a suture. Further, in the illustrated embodiment, the release line is formed integrally with the retainer. That is, in the illustrated embodiment, the retainer242and release mechanism244are constructed of a continuous wire or thread of material, such as a suture. In other embodiments, such as embodiments including a retaining cap, the release mechanism244may include an elongate object or tool that extends through the cannula flow path214and the sleeve208to push the retainer242up off of the sleeve208and, after the sleeve208is deployed, pull the retainer242back through the flow path214defined by the cannula body202.

In its pre-implant state, the expandable sleeve208is gathered together with the retainer242(e.g., a suture ring) and maintained in the stored configuration such that the sleeve208can fit through a cored hole in the myocardium of the heart H. To implant the inflow cannula200, the inflow cannula200is inserted through the cored hole and secured to the heart H, for example, via the ventricular cuff226. In some embodiments, the ventricular cuff226and inflow cannula200are pre-assembled and implanted together, i.e., as a single unit. In other embodiments, the ventricular cuff and inflow cannula200are implanted separately, i.e., in a sequence. The ventricular cuff226is attached to the heart using suitable attachment means (e.g., sutures). Once the inflow cannula200is secured to the heart (e.g., after the ventricular cuff226is sutured to the heart), the release mechanism244is activated to deploy the sleeve208from the stored configuration to the deployed configuration, allowing the sleeve to expand and relax, and conform to the ventricle walls of the heart H. Once the sleeve208is deployed, the pump housing104can be connected to the inflow cannula200(specifically, the proximal portion210of the cannula body202) and/or the ventricular cuff226. When the pump102is activated and the ventricle refills with blood, the sleeve208will block blood flow from between the sleeve208and the myocardial walls, forming a stationary thrombus that will eventually be covered in re-endothelialized tissue, and never released into the blood stream. Tissue reendothelialization may occur within 30 days following the implant procedure.

With additional reference toFIG. 10, the sleeve208includes a sidewall246that includes an outer layer248and an inner layer250. In this embodiment, the sidewall246is formed by folding a mesh material over onto itself. Accordingly, the sidewall246includes an outer mesh layer248and an inner mesh layer250joined to the outer mesh layer248at a distal tip252of the sleeve208. In other embodiments, the sidewall246may be formed using any other suitable method that enables the sleeve208to function as described herein.

As shown inFIG. 10, the inner layer250is spaced from the outer layer248by a spacing254. The size of the spacing254illustrated inFIG. 10is exaggerated for illustrative purposes. In practice, when the sleeve208is in the stored configuration, the spacing254may be significantly smaller than is shown inFIG. 10, and may even be zero (i.e., the inner layer250is in contact with the outer layer248). As shown inFIG. 12, the inner layer250and outer layer248are not joined or fixed to one another along the second portion236of the sleeve208, other than at the distal tip252. Accordingly, the spacing254between the inner layer250and the outer layer248is permitted to increase or expand when the sleeve208is deployed from the stored configuration to the deployed configuration as shown inFIG. 12) to facilitate filling potential areas of low blood flow or stasis around the distal portion212of the cannula body202. Stated another way, a thickness of the sidewall246, measured from the outer layer248to the inner layer250, may increase when the second portion236of the sleeve208is deployed from the stored configuration to the deployed configuration.

In some embodiments, the sidewall thickness or spacing254between the inner layer250and outer layer248may not change significantly when the sleeve208is deployed. As shown inFIG. 6, for example, where heart tissue is disposed above the distal tip240of the cannula body202, the second portion236of the sleeve208stops expanding when the sleeve208contacts the heart tissue, and the outer layer248and the inner layer250may remain in contact with one another. In other embodiments, for example, where the distal portion212of the cannula body202protrudes a distance into the ventricle of the heart H and the distal tip240is spaced above the heart tissue, the second portion236of the sleeve208may fold over and backward behind the distal tip240of the cannula body202. In such embodiments, the sidewall thickness or spacing254between the outer layer248and the inner layer250may increase to facilitate filling potential areas of low blood flow or stasis.

The sleeve208has a suitably flexible construction to allow the sleeve208(specifically, the second portion236of the sleeve208) to expand from the stored configuration and substantially conform and engage endocardial surfaces of the heart H surrounding the distal portion212of the inflow cannula200. Moreover, the sleeve208has sufficient resiliency to ensure the sleeve (specifically, the second portion236of the sleeve) substantially expands back to the deployed configuration when deployed (e.g., once the retainer242is released from the distal end232of the sleeve208).

In the illustrated embodiment, the sleeve208has a mesh construction formed from a network of intertwined wires or threads to provide suitable flexibility and resiliency. That is, the sleeve208is constructed of a tubular mesh. More specifically, in the illustrated embodiment, the sleeve208is constructed of a braided wire, although in other embodiments, the sleeve208may have a construction other than a braided wire. Further, in some embodiments, the sleeve208is constructed from one or more super elastic materials and/or shape-memory materials. A super-elastic material exhibits pseudo-elastic recovery or “memory” from one shape to another multiple times upon the application and release of deforming stress or force. A small stress or force may induce considerable deformation, but the material or component including such a material recovers its original shape when the deforming force or stress is released. Shape-memory materials are materials that have the ability to “memorize” or retain a previous or initial shape or configuration when subjected to certain stimuli, such as stress or heat. Accordingly, in some embodiments, the sleeve208has shape memory properties that, when activated, bias or force the sleeve208towards the deployed configuration. In such embodiments, the shape-memory material may be activated by heat (e.g., from a patient's heart or other heat source), and force or bias the sleeve208back to its original or deployed configuration to facilitate full deployment of the sleeve208.

Suitable super elastic and shape-memory materials from which the sleeve208can be constructed include, for example and without limitation, nickel-titanium alloys (i.e., nitinol) and polymers. In one particular embodiment, the sleeve208is constructed of a nitinol braid that includes a plurality of intertwined nitinol wires or a single nitinol wire intertwined with itself to form a braided sleeve. Braided nitinol has a demonstrated ability to stop the passage of blood and to promote reendothelialization, which facilitates passivating the area and developing a more hemocompatible environment at the pump-tissue interface.

The thickness or diameter of the wires used to construct the sleeve208may be varied according to a desired stiffness of the sleeve208. For example, a thicker wire may be used to provide a stiffer construction of the sleeve208, whereas a thinner wire may be used to provide a more flexible construction of the sleeve208. In some particular embodiments, the sleeve208is constructed of braided nitinol wire, and the wires have a thickness or diameter in the range of 0.01 millimeters to 0.50 millimeters. In other embodiments, the wires may have any suitable thickness or diameter that enables the sleeve208to function as described herein.

Moreover, in some embodiments, the sleeve208may have a variable stiffness from the proximal end230to the distal end232. For example, a thickness of the wire may vary along a length of the sleeve208to provide stiffer regions and more flexible regions along the length of the sleeve208. Additionally or alternatively, the sleeve208may include one or more structural reinforcing members to selectively increase the stiffness of the sleeve208at desired locations along the length of the sleeve208. In one particular implementation, the first portion234of the sleeve208has a stiffer construction than the second portion236of the sleeve208.

In some embodiments, the sleeve208may include one or more layers that promotes reendothelialization and/or reduced blood flow. By way of example, the outer layer248and/or the inner layer250may be formed of and/or may include a material (e.g., a coating, a patch, etc.) that promotes reendothelialization and/or reduced blood flow in the area adjacent the respective layer. In some embodiments, for example, one or both of the outer layer248and the inner layer250include a polyester patch that promotes reendothelialization and reduced blood flow in the area adjacent the respective layers.

FIG. 11is a flow diagram illustrating one embodiment of a method1100for implanting an inflow cannula, such as the inflow cannula200, within a heart of a patient. In the illustrated embodiment, the method1100includes positioning1102a distal portion of the inflow cannula within a hole formed in the heart. The inflow cannula includes an expandable sleeve, such as the expandable sleeve208, having a first portion coupled to the distal portion of the inflow cannula and a second portion extending from a distal end of the inflow cannula. The method1100further includes securing1104the inflow cannula to the heart, and deploying1106the second portion of the sleeve from a first, stored configuration to a second, deployed configuration such that the second portion of the sleeve expands radially and engages and conforms to an endocardial surface of the heart.

In some embodiments, deploying1106the sleeve includes deploying the sleeve subsequent to the inflow cannula being secured to the heart. That is, the sleeve is deployed only after the inflow cannula is secured to the heart. Further, in some embodiments, deploying1106the sleeve includes releasing a retainer, such as retainer242, coupled to a distal end of the sleeve. In some embodiments, the retainer is a retaining ring. In such embodiments, releasing the retainer can include applying tension to a release line that is coupled to the retaining ring, and that extends from the distal end of the sleeve, through a flow path defined by the inflow cannula, and out of a proximal end of the cannula.

In some embodiments, the method1100further includes attaching a ventricular cuff to the heart. In such embodiments, the inflow cannula can be secured to the heart by the ventricular cuff. In some embodiments, the ventricular cuff defines a central opening, and positioning1102a distal portion of the inflow cannula within the hole formed in the heart includes inserting the distal portion of the inflow cannula through the central opening defined by the ventricular cuff. Further, in such embodiments, securing the inflow cannula to the heart can include coupling the inflow cannula to the ventricular cuff.

In some embodiments, the method1100further includes connecting the inlet cannula to a blood pump assembly, such as the blood pump assembly100. In some embodiments, for example, the method1100includes coupling a proximal portion of the inflow cannula to a pump housing of the blood pump assembly. Additionally, the method1100can include coupling the pump housing to a ventricular cuff attached to the heart.

Although certain steps of the example method are numbered, such numbering does not indicate that the steps must be performed in the order listed. Thus, particular steps need not be performed in the exact order they are presented, unless the description thereof specifically require such order. The steps may be performed in the order listed, or in another suitable order.

Although the embodiments and examples disclosed herein have been described with reference to particular embodiments, it is to be understood that these embodiments and examples are merely illustrative of the principles and applications of the present disclosure. It is therefore to be understood that numerous modifications can be made to the illustrative embodiments and examples and that other arrangements can be devised without departing from the spirit and scope of the present disclosure as defined by the claims. Thus, it is intended that the present application cover the modifications and variations of these embodiments and their equivalents.