Patent Description:
Following cardiac shock or due to chronic heart failure, it may be necessary to provide temporary mechanical circulatory assistance. Circulatory assistance can be provided by introducing a balloon into a heart chamber of a patient and causing the balloon to inflate and deflate during diastole and systole respectively. An external pumping unit is often used to inflate the balloon with a drive fluid (e.g. a neutral drive gas, or a liquid). Periodic inflation and deflation of the balloon within the heart chamber displaces the blood within the chamber and provides circulatory assistance to the patient.

Inflatable intraventricular devices are known in the art.

US patent publication <CIT>, which describes an intraventricular balloon device comprising a slender flexible catheter with a proximal end and a distal end. An inflatable balloon is provided near the distal end and the balloon can be brought into its deflected state allowing entry into e.g. the left ventricle. An additional balloon can be provided on the catheter to be lodged within an appropriate blood vessel (e.g. the descending aorta).

International patent publication <CIT> describes a heart support device for circulatory assistance with an internal member configured to be disposed within a heart lumen. The device comprises a dynamic volume body that can be inflated and deflated periodically with the natural (or modified) heart rhythm. The internal member has a substantially stiff wall strengthening portion arranged to engage an inner wall surface of the heart in operation and a dynamic member that is inflatable to assist pumping action of the.

<CIT> discloses a heart support device for circulatory assistance according to the preamble of claim <NUM>.

Although the effect of the above described systems is to displace residual volume of blood from the heart lumen, such displacement devices do not approach the efficiency of natural cardiac motion.

There is thus a need for an improved circulatory assistance device.

The present invention seeks to provide an improved heart support device that can be implanted into a heart lumen with a minimally invasive procedure and is suitable for treating cardiogenic shock/and or chronic heart failure due to a weakened heart wall or scarring of the cardiac tissue and those for whom the risk of percutaneous cardiovascular intervention (PCI) is high. More particularly, the present invention seeks to improve upon existing devices by providing a directional flow structure to direct the flow of blood towards e.g. the aortic valve when the pump is placed in the left ventricle.

According to the present invention there is provided a heart support device for circulatory assistance comprising a chamber body defining a chamber having an internal volume configured to be filled with blood, the chamber body having a first opening, wherein the chamber body and the first opening are dimensioned to be disposed within a chamber of the human heart. A dynamic volume body is configured to be inflated and deflated to alternately increase and decrease the interior volume of the chamber. A catheter comprising at least one lumen is provided in fluid communication with the dynamic volume body and is arranged to deliver fluid to the dynamic volume body to inflate the dynamic volume body. A directional flow structure is also provided to direct a flow of blood out of the chamber in a direction substantially aligned with a direction in which the catheter extends. Since the device is configured for placement in the heart with the catheter extending through the aortic valve, by providing a directional flow device that directs the flow of expelled fluid along the axis of the catheter, the present invention provides directional flow towards the aortic valve in a manner that more closely mirrors natural flow of blood within the heart compared to known devices.

The directional flow structure can be configured in different ways. For example, the directional flow structure can comprise a restricted opening, e.g. a neck at the proximal end of the device that is relatively narrow compared to the chamber. The restricted opening can comprise an elongate tube, a tapered neck or a venturi tube (comprising a tapered inlet cone and a tapered outlet cone). The walls of the neck can be substantially parallel to each other.

According to the invention, the directional flow component comprises a structure that imparts a vortex in the flow of fluid exiting the aperture. The vortex inducing structure can comprise static or movable impeller blades, a torsional balloon that expands with a twisting motion within the chamber, or a combination thereof.

The dynamic volume body can also be configured in different ways. For example, the dynamic volume body can comprise an inflatable membrane disposed within the chamber that is configured to expand within the chamber, thus displacing a volume of blood within the chamber through the aperture. In such embodiments the inflatable membrane can comprise a balloon having a membrane that is substantially more flexible relative to the walls of the chamber. This ensure that as the balloon inflates, it displaces the blood within the chamber, whilst the chamber maintains a stable expanded configuration.

The directional flow structure can comprise a restricted opening which provides a constriction at the first opening.

The heart support device can optionally comprising a support structure configured to support the chamber body in an expanded configuration.

In at least some embodiments, the heart support device may be collapsible to allow insertion of the device into a heart chamber in a minimally invasive manner. The support structure may be inflatable and can be provided in fluid communication with at least one lumen of the catheter to allow the support structure to be inflated.

In at least some embodiments, the support structure can comprise a scaffold formed of a resilient material, which is biased into a second configuration, and is expandable from a first configuration in which the chamber body has a first internal volume to the second configuration in which the chamber body comprises a second internal volume, the second internal volume being larger than the first internal volume.

Optionally, the dynamic volume body is configured to expand the support structure from the first configuration to the second configuration, thereby increasing the internal volume of the chamber.

In at least some embodiments, the dynamic volume body may comprise an inflatable balloon disposed within the chamber. Advantageously, the balloon may be a toroidal balloon.

The chamber body can extend from a proximal end at which the first aperture is located, to a distal end, opposite the proximal end, wherein the balloon is disposed at the distal end of the chamber body. The balloon may be configured to expand proximally to impart directional flow to the blood exiting the chamber.

The chamber body may be further provided with one or more additional openings, disposed at the distal end of the chamber, remote from the first openings. Additional openings at the distal end of the chamber may provide limited backflush from the distal end of the chamber, which can minimise the risk of blood pooling and clotting at the distal end of the chamber.

Advantageously, the additional opening(s) account for approximately <NUM>%-<NUM>% (e.g. <NUM>%) of the cross-sectional flow area into/out of the chamber, whilst the first opening(s) can account for approximately <NUM>-<NUM>% (e.g. <NUM>%).

Additionally or alternatively, the chamber walls can comprise one or more additional side openings configured to provide an additional inlet for blood into the interior of the chamber.

The additional openings can be configured as one-way flow opening(s) that allow flow into the interior volume of the chamber and prevent or inhibit flow out of the chamber.

According to the invention, the device comprises a vortex inducing arrangement. The vortex inducing arrangement can be configured to impart a spiral or vortex flow to fluid exiting the chamber via the outlet opening.

The vortex inducing structure may comprises comprise a plurality of static blades arranged within the restricted opening.

In another group of embodiments, which may be implemented in isolation from or in combination with the embodiments described above, the chamber body can comprise a helical support structure configured to allow for helical collapse of the chamber body.

In yet another group of embodiments, which may be implemented in isolation from or in combination with the embodiments described above, the directional flow structure can comprises a venturi tube. This can maintain a steady directional flow of blood toward the aorta when the device is in use.

In yet another group of embodiments, which may be implemented in isolation from or in combination with the embodiments described above , the chamber body can comprise a longitudinal axis A, and the restricted opening can comprise a tube extending along a second axis, and wherein the first axis and the second axis are not coaxial. Such an arrangement can allow the chamber body to lie against the heart wall, whilst the outlet is position towards the aorta. This arrangement may further improve the directional flow of blood through the aortic valve. As described above, when the heart support device is positioned in the left ventricle, the directional flow structure is configured to direct the flow of blood toward the aortic valve. This may improve the efficiency of the device because it more closely replicates the blood flow seen during uncompromised natural heart function. Moreover, because the heart support device is positioned within the heart chamber, with the aperture located within the heart chamber, before the aortic valve, interference with (potentially resulting in damage to) the aortic valve is minimised.

The present invention will now be described more fully with reference to a number of exemplary embodiments, as shown in the attached drawings in which:.

<FIG> shows an exemplary embodiment of a heart support device for providing circulatory assistance to a patient. In the embodiment shown in <FIG>, the heart support device is positioned within the left ventricle LV. As shown in <FIG>, the heart support device according to the invention comprises a chamber <NUM> defining an internal volume and having at least one aperture <NUM> for fluid communication between the internal volume of the chamber <NUM> and a volume external to the chamber <NUM>. As shown in <FIG>, the chamber <NUM> is dimensioned so that the chamber <NUM> and the aperture <NUM> are disposed within a chamber of the human heart (in this case, the left ventricle LV).

In left ventricular embodiments, the device may have a maximum outer diameter of between <NUM> and <NUM>, more particularly <NUM> and <NUM>. In one example, the chamber has a maximum outer diameter at its widest point of <NUM>.

The length of the device (extending from the aperture to the end opposing the aperture) can be between <NUM> and <NUM>, more particularly between <NUM> and <NUM>. In one embodiment, the device has a length of <NUM>.

The skilled person will understand that the length of device can be adjusted to individual patient needs. For example, for many patients in need of circulatory assistance, the heart wall may be compromised to some degree, leading to a significant increase in the internal volume of the left ventricle compared to healthy individuals. Mapping can be carried out for individual patients can devices for according to individual needs. Alternatively, a range of sizes (small, medium, large) can be made and the appropriate size selected for each individual.

The support device further comprises at least one dynamic volume body <NUM>, configured to be inflated and/or deflated to alternately increase and decrease the available interior volume of the chamber <NUM> (i.e. the volume within the chamber <NUM> that can be filled with blood). A catheter <NUM> comprising at least one fluid lumen <NUM> is in fluid communication with the dynamic volume body <NUM> and is configured to deliver fluid (e.g. a liquid, or a gas such as Helium) to the dynamic volume body <NUM> to inflate and/or deflate the body <NUM>. A directional flow structure <NUM> is further provided to direct a flow of blood out of the chamber <NUM> in a direction substantially aligned with a direction in which the catheter extends.

In addition to displacing a volume of blood within the chamber <NUM> due to periodic increase/decrease the available volume of the chamber, the directional flow structure <NUM> advantageously directs the displaced blood in a direction of the aortic valve, i.e. in a manner that more closely approximates the natural function of the heart. By providing a directional flow structure to direct the flow of blood toward the aortic valve, the flow of blood created by the device more closely mimics the blood flow seen during uncompromised natural heart function, thereby improving the efficiency of the supported heart.

Directional flow structures can be realised in different ways. For example, the directional flow structure <NUM> can comprise a restricted opening at the proximal end of the chamber <NUM> (e,g, a neck). The proximal end of the chamber <NUM> is the end from which the catheter <NUM> extends. The restricted opening <NUM> has a smaller cross-sectional area than the cross-sectional area of the chamber <NUM> and provides a constriction at the first opening. Advantageously, the restricted opening <NUM> has a diameter that is less than (or equal to) the diameter of the aorta (generally <NUM>% or less of the diameter of the main body; in some examples between <NUM> and <NUM>, more particularly between <NUM> and <NUM>, more particularly <NUM>). Advantageously, the restricted opening <NUM> is centred on the catheter <NUM> and comprises a straight sided tube or conduit. The tube can be cylindrical (with parallel walls) or tapered towards the opening. In some embodiments, a venturi tube forms the restricted opening, as described in more detail below.

Directional flow can also be provided by a structure that provides a pumping impulse in the direction of the aortic valve. Embodiments of the present invention comprising different directional flow structures will be described in more detail below.

The heart support device can further comprise a support structure <NUM> configured to support the chamber <NUM> in an expanded configuration. The support structure <NUM> can hold the chamber <NUM> in a stable position such that a balloon or other inflatable member can be inflated within the chamber <NUM> to decrease the available volume (thus forcing blood through the directional flow structure).

To allow the support device to be advanced into the heart lumen via a minimally invasive procedure, the support structure <NUM> can be collapsible. This can allow the device to be advanced into the left ventricle through the aorta (or another natural lumen). The support structure can be biased into an expanded position and maintained in the collapsed position during insertion by way of a guide tube or other tool. As an example, the support structure <NUM> can comprise a shape memory material, e.g. in the form of a collapsible scaffold formed of nitinol or another shape memory material.

Once removed from the guide tube, the support structure <NUM> can return to its expanded configuration.

Alternatively, the support structure <NUM> can comprise an expandable scaffold that can be expanded with a supply of fluid or gas to the scaffold. In other words, in at least some embodiments, the support structure <NUM> is inflatable. In such embodiments, the support structure <NUM> can be provided in fluid communication with at least one lumen of the catheter <NUM> to allow the support structure <NUM> to be inflated after it has been advanced into the heart lumen.

Once the chamber has been expanded to its expanded position, the dynamic volume body can act as a displacement body which is disposed within the chamber, and is expandable to fill an increasing proportion of the internal volume of chamber <NUM>. Because the displacement body (e.g. the balloon <NUM>) is disposed within the chamber, as the balloon inflates, it displaces blood within the chamber, thus forcing it through the aperture <NUM> towards the aortic valve.

The support structure <NUM> can comprise a scaffold formed of a resilient material, which is biased into and expandable from a first configuration in which the chamber body <NUM> has a first internal volume to a second configuration in which the chamber body <NUM> comprises a second internal volume, which is larger than the first internal volume. The resilient material can comprise an elastic or shape-memory material that is biased into an expanded configuration and can be compressed or collapsed whilst the device it advanced through a natural lumen into the heart chamber. In these embodiments, the dynamic volume body <NUM> can be configured to expand the support structure <NUM> from the first configuration to the second configuration, thereby increasing the internal volume of the chamber <NUM>.

Referring again to <FIG>, the dynamic volume body <NUM> can comprise an inflatable balloon <NUM> disposed within the chamber <NUM>. The balloon <NUM> is disposed within the chamber body <NUM>, which can take the form of a cup <NUM>. The cup <NUM> is relatively rigid compared to the balloon <NUM>, once it has been expanded to its expanded configuration. The balloon <NUM> is formed at least partially of a membrane defining an interior volume that is configured to expand upon an increase of fluid (e.g. liquid or gas) within the balloon <NUM>. The membrane can be formed of an elastic material configured to stretch as the interior volume is filled with air, or the membrane can be substantially non-elastic. The cup <NUM> can be formed of an expandable scaffold <NUM> with sidewall(s) <NUM>, which defines the volume of the chamber <NUM>. The sidewalls of the cup can be formed in the manner described in <CIT>, which is hereby incorporated by reference in its entirety. However, in light of the present disclosure, the skilled person will appreciate that other cup constructions are possible.

<FIG> illustrate the configuration of a 'balloon-in-cup' type of heart support device at different stages. In <FIG>, the cup <NUM> is in its expanded configuration within the heart lumen. The balloon <NUM> is empty and the interior volume of the chamber <NUM> is filled with blood B. In Fig. 5B, the balloon <NUM> is inflated by filling the balloon <NUM> with gas or liquid. As the balloon <NUM> inflates, the volume it occupies within the chamber <NUM> increases, and blood B is displaced from the interior volume of the chamber <NUM> and forced through the aperture <NUM> at the proximal end of the chamber. As shown in <FIG>, this causes blood to leave the chamber <NUM> via the aperture and the directional flow structure, thus direction the flow of blood towards the aortic valve AV. As the balloon <NUM> inflates, it occupies an increasing volume within the cup <NUM>, thus displacing the blood filling the chamber <NUM> and forcing it from the chamber <NUM> through the directional flow structure and the aperture <NUM> towards the aortic valve AV.

The balloon <NUM> can be configured in number of different ways. For example, the balloon <NUM> can comprise a balloon <NUM> that is free to expand in all directions (in the manner of a conventional balloon). As the balloon inflated within the chamber body <NUM>, the available internal volume of the chamber decreases and blood is forced from the chamber <NUM> through the aperture <NUM>. Alternatively, and as shown in <FIG>, the balloon <NUM> can comprise a flexible elastic membrane secured within the cup <NUM> to form a sealed cavity that can be filled with inflating fluid. The cup and membrane combination of embodiment can be formed in a similar manner to the device described in <CIT>, except that the walls of the cup that forms the chamber body <NUM> should extend beyond the membrane towards the restricted opening that provides the directional flow control. Advantageously, the balloon <NUM> is provided at the opposite end of the chamber body <NUM> to the first opening <NUM>.

As shown in <FIG>, the cup <NUM> can incorporate a distal portion of the catheter <NUM> with a plurality of fluid ports <NUM> into its sidewall. The openings <NUM> are provided in fluid communication with the interior of the balloon <NUM> and are configured to fill the sealed cavity of the balloon <NUM>. As shown in <FIG>, the balloon can be inflated and deflated by a catheter that is not incorporated into the sidewall. As shown in <FIG>, the balloon <NUM> can comprise a toroidal (or donut shaped) balloon <NUM>. The toroidal balloon <NUM> can be configured to be centrally filled from a plurality of openings <NUM> in the catheter <NUM>. This can provide symmetrical filling of the toroidal balloon <NUM>.

As shown in <FIG>, the chamber <NUM> can extend from a proximal end at which the first aperture <NUM> is located to a distal end, opposite the proximal end. The balloon <NUM> is disposed at the distal end of the chamber <NUM> and is configured to expand proximally. In both of the embodiments shown in <FIG>, the balloon <NUM> is configured such that the flexible membrane expands (upon filling) in a direction towards the direction in which the catheter <NUM> extends. The extension of the flexible membrane in this direction can be configured to cause an impulse to further assist in directional flow control of blood leaving the chamber <NUM> through the aperture <NUM>. In other words, the balloon <NUM> (or balloons) can be configured to inflate asymmetrically, expanding from the distal end toward the proximal end of the chamber <NUM>.

Turning now to <FIG>, the chamber <NUM> can be further provided with additional openings, disposed at the distal end of the chamber <NUM>, remote from the first openings. The additional openings <NUM> provide additional fluid communication between the interior volume of the chamber <NUM> and the volume exterior to the chamber <NUM>. Advantageously, the additional openings <NUM> allow blood from the lower part of the chamber <NUM> to be flushed through the additional openings <NUM> as the available volume of the chamber <NUM> decreases. By providing additional openings to flush blood from the lower part of the chamber <NUM>, the risk of clots forming within the chamber <NUM> is decreased. Moreover, the flow of blood through the additional openings <NUM> flushes blood from the area A between the device and the heart wall, further reducing the risk of clots forming in the LV. Since the primary function of the heart support device is to provide circulatory assistance, the additional opening(s) <NUM> should be smaller than the first opening(s) <NUM>, so that a majority of the blood expelled from the chamber <NUM> is expelled through the first opening(s) <NUM> towards the aorta. In some embodiments, the additional opening(s) <NUM> account for less than <NUM>% of the cross-sectional flow area into/out of the chamber <NUM>, whilst the first opening(s) <NUM> account for <NUM>% or more. Advantageously, the additional opening(s) <NUM> account for approximately <NUM>%-<NUM>% (e.g. <NUM>%) of the cross-sectional flow area into/out of the chamber <NUM>, whilst the first opening(s) <NUM> account for approximately <NUM>-<NUM>% (e.g. <NUM>%). The skilled person will appreciate that this ratio can be modified to suit the particular application/specific patient needs.

Turning now to <FIG>, the chamber <NUM> can comprise one or more additional side openings <NUM> configured to provide an additional inlet for blood into the interior of the chamber <NUM>. The additional side openings <NUM> can comprise one-way valve structures configured to allow the flow of fluid into the chamber <NUM> via the openings <NUM> (and prevent flow in the opposite direction). By providing additional side openings <NUM> on the wall of the chamber <NUM>, the heart support device can draw blood into the chamber <NUM> as the available volume increases from a location within the heart lumen that is remote from the aortic valve. This may prevent undesirable negative pressure behind the aortic valve.

The additional side openings <NUM> can be configured to be self-sealing as the pressure within the chamber <NUM> increases with the decreasing available volume. As shown in <FIG>, the additional side openings <NUM> can be formed at the intersection of a plurality of overlapping panels <NUM>. The panels <NUM> are arranged in a circular overlapping arrangement, with the leading edge 34a of each panel <NUM> overlapping the trailing edge 34b of the next panel <NUM>. As shown in <FIG>, as the available interior volume of the chamber <NUM> increases, the pressure within the chamber <NUM> drops and blood is drawn in through the openings <NUM> between the panels <NUM>. However, as the available interior volume of the chamber <NUM> decreases, the pressure within the chamber <NUM> forces the overlapping portions of the panels <NUM> into contact with each other, thus sealing the openings <NUM> shut (see <FIG>). The blood within the chamber <NUM> is thus forced out of the chamber <NUM> through the opening <NUM>, as shown in <FIG>. As shown in <FIG>, the panels <NUM> can be supported by a plurality of ribs that provide support structure <NUM>.

As an alternative to the panel arrangement shown in <FIG>, the additional openings <NUM> (e.g. see <FIG>) can comprise conventional one-way valves. The skilled person will appreciate that other constructions that allow one way flow through the openings <NUM> can also be employed. In other words, the additional openings can be configured as one-way flow opening(s) <NUM> that allow flow into the interior volume of the chamber <NUM> and prevent or inhibit flow out of the chamber <NUM>.

According to the invention, to further enhance the directional flow out of the chamber <NUM> towards the aortic valve, the directional flow structure <NUM> comprises a vortex inducing arrangement. As shown in <FIG>, the vortex inducing structure can comprise a plurality of static blades <NUM> arranged within the restricted opening <NUM> (e.g. a static impeller arrangement) configured to induce a vortex in the fluid that flows over the blades.

In other embodiments, a vortex or spiral flow towards the aorta can be induced by the manner in which the balloon <NUM> expands. For example, the balloon <NUM> can be wrapped or folded within the chamber such that upon expansion is twists to produce a vortex if flow through the aperture.

In the embodiment shown in <FIG>, the support device comprises a chamber <NUM> formed by a series of panels <NUM> supported by a support structure <NUM>. The support structure <NUM> comprises a plurality of ribs <NUM> that are arranged in a helical fashion, extending from a first common end point <NUM> and, advantageously, meeting at a second common end point <NUM> (for example, as shown in <FIG>). The support structure <NUM> is configured to be collapsed and expanded (during insertion of the device) by twisting the walls of the chamber <NUM> relative to the axis defined between the common end points <NUM>, <NUM>. The relative rotation of the walls of the chamber about the axis can be between <NUM> degree and <NUM> degrees, although other rotations are possible.

In any of the above described embodiments, the directional flow structure can be configured as a venturi tube. The venturi tube can comprise a restricted opening at the exit of the chamber body <NUM> that comprises an entry cone, a constriction, and an exit cone. In one example, the entry cone can comprise a cone of approximately <NUM> degrees, whilst the exit cone can comprise a cone of approximately <NUM> degrees.

As shown in <FIG>, to further optimise the directional flow of blood out of the chamber <NUM>, the restricted opening <NUM> can be angled with respect to the chamber body <NUM>. For example, the chamber body <NUM> can comprise a longitudinal axis A, and the restricted opening <NUM> can comprise a tube that extends along a second axis B, which is not coaxial with the first axis A. The angle ϕ between the restricted opening <NUM> and the longitudinal axis of the chamber body <NUM> can be between <NUM> and <NUM> degrees, more particularly approximately <NUM> degrees. This angle allows the chamber body <NUM> to lie against the wall the left ventricle without obstructing the mitral valve MV, whilst still directing the flow of blood from the chamber <NUM> directly towards the aortic valve AV.

Methods of providing circulatory assistance comprising the above described device also form part of the present disclosure. For example, a method of providing circulatory assistance comprises the steps of placing the device <NUM> with a chamber of the heart such that the aperture of the device and associated directional flow components are disposed within the heart chamber, on a chamber side of the aortic valve. Once placed, the method comprises alternately inflating and deflating the dynamic volume body to displace blood within the chamber such that it is expelled through the aperture in a direction of the aortic valve.

Claim 1:
A heart support device for circulatory assistance, the heart support device comprising:
a chamber body (<NUM>) defining a chamber having an internal volume configured to be filled with blood, the chamber body (<NUM>) having a first opening (<NUM>), wherein the chamber body (<NUM>) and the first opening (<NUM>) are dimensioned to be disposed within a chamber of the human heart;
a dynamic volume body (<NUM>) configured to be inflated or deflated to alternately increase or decrease the interior volume of the chamber;
a catheter (<NUM>) comprising at least one lumen in fluid communication with the dynamic volume body (<NUM>) and configured to deliver fluid to the dynamic volume body to inflate the dynamic volume body; and
a directional flow structure configured to direct a flow of blood out of the chamber in a direction substantially aligned with a direction in which the catheter (<NUM>) extends;
wherein the device further comprises a vortex inducing arrangement.