Patent Description:
In some procedures, blood is shunted from one blood vessel to another.

<CIT> describes a device for extracorporeal blood treatment comprising an extracorporeal blood circuit which comprises a first chamber of a dialyzer or filter divided by a semipermeable membrane into the first chamber and a second chamber, and a fluid system which comprises the second chamber of the dialyzer or filter, fluid being removed from the blood circuit via the dialyzer or filter at a predetermined ultrafiltration rate and substitution fluid being fed to the blood circuit upstream or downstream from the dialyzer or filter with a substitute pump, wherein, in order to interrupt the blood treatment, a control unit is provided which is embodied such that, after the reduction of the ultrafiltration rate to a predetermined value, the substitute pump is operated at a predetermined delivery rate for a predetermined time interval.

<CIT> describes a clamp apparatus for selectively occluding a resilient tube to prevent free flow of fluid in the tube. The device comprises a base member to which the resilient IV tube is attached or through which it passes, and a slide clamp that slides relative to the base member and relative to the tube. The aperture in the slide clamp has a relatively open hole at one end, through which the tube passes when the slide clamp is an open position, allowing fluid to flow through the tube. The aperture also has a relatively constricted slot at the other end, through which the tube passes when the slide clamp is in the occluding position, preventing fluid flow through the tube. The slide clamp includes a groove for receiving a cooperatively shaped rib on the base member. The groove and rib are configured to guide relative movement between the slide clamp and the base so as to prevent significant lateral movement.

<CIT> describes a linear flow regulating apparatus for intravenous infusion set, the apparatus comprising: a flow channel unit having a rectangular cross-section that allows a solution to flow therethrough; the flow channel unit comprising: an inlet tube connected at the front end of the flow channel unit to allow the solution to simultaneously flow in over the entire width of the flow channel unit; and an outlet tube connected at the rear end of the flow channel unit to allow the solution to simultaneously flow out over the entire width of the flow channel unit; a control unit that is adapted to be put in or taken out of one side of the flow channel unit to vary a width of a flow passage area of the flow channel unit; and a fine adjustment unit that is formed at a contact region between the flow channel unit and the control unit to adjust a moving distance of the control unit along the width, wherein the control unit varies the flow pas sage area while moving into the inside of the flow channel unit along the width of the flow channel unit so as to linearly regulate the flow rate of the solution, and the flow rate of the solution is linearly proportional to the width of the flow passage area.

There is provided, in accordance with some embodiments of the present invention, an apparatus for shunting blood. The apparatus includes a flow-indication chamber shaped to define an entry port and an exit port, and one or more moveable objects disposed within the flow-indication chamber and configured to move in response to a flowing of the blood from the entry port to the exit port. At least a portion of a wall of the flow-indication chamber is transparent so as to expose the moveable objects to sight.

In some embodiments, the moveable objects include a plurality of beads.

In some embodiments, at least one of the beads includes multiple faces.

In some embodiments, each of the beads is coated with an anticoagulant.

In some embodiments, the moveable objects include a rotational member configured to rotate in response to the blood exerting a force on the rotational member.

In some embodiments, the rotational member includes a wheel including a plurality of spokes.

In some embodiments, the wheel is positioned relative to the entry port and exit port such that each of the spokes, when perpendicular to an unimpeded path of the blood from the entry port to the exit port, intersects the unimpeded path.

In some embodiments, a most proximal point on each of the spokes that intersects the unimpeded path is located between <NUM>% and <NUM>% of a length of the spoke from a proximal end of the spoke.

In some embodiments, the apparatus further includes a filter chamber configured to couple to the flow-indication chamber and to hold a blood filter in the filter chamber.

In some embodiments, the apparatus further includes a threaded ring,.

In some embodiments, the flow-indication chamber is further configured to hold a blood filter therein.

In some embodiments, the apparatus further includes a valve configured to regulate the flowing of the blood through a port selected from the group of ports consisting of: the entry port, and the exit port.

In some embodiments, the valve includes:.

In some embodiments, the spring includes a tension spring.

There is further provided, in accordance with some embodiments of the present invention, a method including coupling an upstream end of a first conduit to a source blood vessel of a subject and a downstream end of the first conduit to an entry port of a shunt. The method further includes coupling an upstream end of a second conduit to an exit port of the shunt and a downstream end of the second conduit to a sink blood vessel of the subject, such that blood flows from the source blood vessel to the sink blood vessel via the shunt, thus causing movement of one or more moveable objects disposed within the shunt, the movement being visible through a wall of the shunt.

In some embodiments, the shunt includes a flow-indication chamber, which contains the moveable objects, and a filter chamber, which is coupled to the flow-indication chamber and holds a blood filter in the filter chamber.

There is further provided, in accordance with some embodiments of the present invention, an apparatus including a chamber shaped to define a fluid port, a first appendage protruding from the chamber and shaped to define a first aperture and a first row of one or more teeth, and a second appendage protruding from the chamber and shaped to define a second aperture and a second row of one or more teeth parallel to the first row of teeth. The second row is configured to interlock with the first row at multiple different relative positions of the first appendage and second appendage in which the second aperture is aligned with the first aperture with different respective degrees of alignment such that a tube, which carries blood to or from the fluid port through the first aperture and second aperture, is constricted with different respective degrees of constriction.

In some embodiments, the chamber is configured to hold a blood filter therein.

In some embodiments, the apparatus further includes one or more moveable objects disposed within the chamber and configured to move in response to a flowing of the blood through the chamber, at least a portion of a wall of the chamber being transparent so as to expose the moveable objects to sight.

In some embodiments, the first appendage and second appendage are continuous with a wall of the chamber.

In some embodiments, the first appendage and second appendage are configured to revert to a default relative position, in which the tube is not constricted, upon a release of the first row and second row from one another.

In some embodiments, each of the teeth in the first row and in the second row is angled backward, such that an advancement of the first row and second row relative to one another constricts the tube.

In some embodiments, the tube is not completely constricted in any of the positions.

There is further provided, in accordance with some embodiments of the present invention, a method including sliding a first appendage, which protrudes from a chamber and is shaped to define a first aperture and a first row of one or more teeth, across a second appendage, which protrudes from the chamber and is shaped to define a second aperture and a second row of one or more teeth parallel to the first row of teeth, such that the second row interlocks with the first row at a relative position of the first appendage and second appendage in which the second aperture is misaligned with the first aperture, thereby constricting a tube that carries blood to or from a fluid port of the chamber through the first aperture and second aperture. The method further includes, subsequently to constricting the tube, releasing the first row and second row from one another, thereby causing the first appendage and second appendage to revert to a default relative position in which the tube is not constricted.

In some cases, it may be necessary to shunt blood from one anatomical site to another. For example, during an operation to remove a clot from a carotid artery of a subject, it may be necessary to shunt blood from the carotid artery to a vein, such as a femoral vein, of the subject. In such cases, a shunting device (or "shunt") is used to carry blood between the sites. However, there is a risk of the blood flow through the shunt slowing or stopping without the physician noticing.

To mitigate this risk, embodiments of the present invention provide a shunt comprising a flow-indication chamber containing one or more moveable objects, which are configured to move in response to the flow of blood through the flow-indication chamber. At least a portion of the wall of the flow-indication chamber is transparent, such that the moveable objects are visible. For example, the wall may comprise a transparent window, and the moveable objects may be disposed behind the window. Thus, a physician may readily check whether the blood is flowing properly through the shunt, by observing the degree of motion of the moveable objects.

In some embodiments, the moveable objects comprise multiple beads suspended in the blood, which rotate and/or change position as the blood flows. In other embodiments, the moveable objects comprise a wheel comprising a plurality of radiating spokes, which rotates as the blood flows across the spokes.

Another challenge is that sometimes it may be necessary to slow or stop the flow of blood through the shunt temporarily, e.g., to allow more blood to flow through the carotid artery to the brain of the subject.

To address this challenge, some embodiments of the present invention equip the shunt with a valve configured to control the rate of flow through the entry port or exit port of the shunt. For example, the valve may comprise a pushable element passing through the wall of the aforementioned flow-indication chamber, along with a spring within the flow-indication chamber, which couples the pushable element to an inner wall of the flow-indication chamber. In its resting state, the spring holds the pushable element away from the port, such that blood freely flows through the port. On the other hand, a pushing force sufficient to overcome the force of the spring may push the pushable element over the port, thereby slowing or stopping the flow of blood.

In other embodiments, the shunt is equipped with a tube constrictor configured to constrict the tube carrying the blood to or from the port. The tube constrictor comprises a pair of parallel arms, which are shaped to define respective apertures and respective rows of teeth. The rows of teeth are configured to interlock with one another at a default position, in which the apertures are aligned with one another, and at one or more other positions, in which the apertures are misaligned by varying degrees. Thus, while the tube passes through the apertures, the tube may be partially or fully constricted by sliding the arms over one another. Subsequently to constricting the tube, to resume regular blood flow, the rows of teeth may be released from one another such that the arms revert to their default positions.

Reference is initially made to <FIG>, which is a schematic illustration of an apparatus <NUM> for shunting blood <NUM>, in accordance with some embodiments of the present invention. An inset portion <NUM> of <FIG> shows part of the interior of apparatus <NUM>.

Apparatus <NUM>, which may be referred to as a "shunt," comprises a flow-indication chamber <NUM> shaped to define an entry port <NUM> and an exit port <NUM>. Blood <NUM> enters flow-indication chamber <NUM> via entry port <NUM>, flows through the flow-indication chamber, and exits the flow-indication chamber via exit port <NUM>.

According to the invention, entry port <NUM> is configured to couple to an entry tube <NUM> (or any other entry conduit, such as a catheter) through which blood <NUM> flows to apparatus <NUM>. For example, entry tube <NUM> may be fittingly inserted into entry port <NUM>, or the entry port may be fittingly inserted into the entry tube.

In some embodiments, apparatus <NUM> further comprises a filter chamber <NUM> configured to couple to flow-indication chamber <NUM> and to hold a blood filter <NUM> in filter chamber <NUM>. Blood filter <NUM> may be secured within the filter chamber using any suitable structural components, such as a plurality of ribs <NUM> as shown in <FIG>, which is described below. Filter chamber <NUM> is shaped to define an entry port <NUM>, through which blood <NUM> enters the filter chamber, and an exit port <NUM>, through which the blood exits the filter chamber.

As shown in <FIG>, the filter chamber may be coupled to the flow-indication chamber downstream from the flow-indication chamber, such that the blood flows through the filter chamber after flowing through the flow-indication chamber. (Optionally, a single common port may function as both exit port <NUM> and entry port <NUM>. ) In such embodiments, exit port <NUM> is configured to couple to an exit tube <NUM> (or any other exit conduit, such as a catheter), which carries the blood from apparatus <NUM>.

Alternatively, the filter chamber may be coupled to the flow-indication chamber upstream from the flow-indication chamber. (Optionally, a single common port may function as both exit port <NUM> and entry port <NUM>. ) In such embodiments, entry port <NUM> of the filter chamber is configured to couple to entry tube <NUM>, and exit port <NUM> of the flow-indication chamber is configured to couple to exit tube <NUM>.

In some embodiments, apparatus <NUM> further comprises a threaded ring <NUM>. Flow-indication chamber <NUM> is configured to screw into one side of threaded ring <NUM>, and filter chamber <NUM> is configured to screw into the other side of the threaded ring such that the two chambers are in fluid communication with one another. For example, as shown in <FIG>, the flow-indication chamber may be screwed into the upstream side of ring <NUM> and the filter chamber may be screwed into the downstream side of ring <NUM>, such that the blood flows directly from exit port <NUM> into entry port <NUM>. Alternatively, the filter chamber may be screwed into the upstream side of ring <NUM> and the flow-indication chamber may be screwed into the downstream side of ring <NUM>, such that the blood flows directly from exit port <NUM> into entry port <NUM>.

In other embodiments, as shown in <FIG>, the flow-indication chamber and filter chamber are coupled to one another via a coupling tube <NUM>.

In yet other embodiments, apparatus <NUM> does not comprise filter chamber <NUM>. In such embodiments, flow-indication chamber <NUM> may be configured to hold blood filter <NUM> therein.

Apparatus <NUM> may shunt blood <NUM> between any two suitable blood vessels of a human or animal subject. In other words, apparatus <NUM> may shunt blood <NUM> from any suitable "source" blood vessel of the subject to any suitable "sink" blood vessel of the subject. For example, apparatus <NUM> may shunt blood from an artery of the subject to a vein of the subject, with entry tube <NUM> delivering blood from the artery and exit tube <NUM> carrying the blood to the vein. As a specific example, apparatus <NUM> may shunt blood from a carotid artery to a femoral vein during an operation to remove a clot from the carotid artery. Alternatively, apparatus <NUM> may shunt blood from a higher-pressure artery to a lower-pressure artery.

To deploy apparatus <NUM>, the upstream end of entry tube <NUM> is coupled to the source blood vessel (e.g., via a stopcock and/or any other suitable equipment), and the downstream end of the entry tube is coupled to the entry port of apparatus <NUM> (e.g., entry port <NUM>, for embodiments in which the flow-indication chamber is upstream from the filter chamber). Similarly, the upstream end of exit tube <NUM> is coupled to the exit port of apparatus <NUM> (e.g., exit port <NUM>, for embodiments in which the flow-indication chamber is upstream from the filter chamber), and the downstream end of the exit tube is coupled to the sink blood vessel (e.g., via a stopcock and/or any other suitable equipment). Subsequently, blood flows from the source blood vessel to the sink blood vessel via apparatus <NUM>.

Apparatus <NUM> further comprises one or more moveable objects <NUM> disposed within flow-indication chamber <NUM> and configured to move in response to the flowing of blood <NUM> from entry port <NUM> to exit port <NUM>. At least a portion of the wall <NUM> of the flow-indication chamber is transparent so as to expose moveable objects <NUM> to sight. For example, wall <NUM> may be entirely transparent, as shown in <FIG> (described below). Alternatively, as shown in <FIG>, the wall may comprise at least one transparent window <NUM>. Thus, the physician may readily check the rate of blood flow through the flow-indication chamber, by observing the degree of movement of moveable objects <NUM>. In some embodiments, the transparent portion of wall <NUM> comprises a magnifying lens, configured to magnify moveable objects <NUM>.

In some embodiments, moveable objects <NUM> comprise a plurality of beads <NUM>, which rotate and/or change position as the blood flows. Typically, beads <NUM> have a density less than that of blood <NUM>, such that the beads remain suspended in the blood. Beads <NUM> may comprise any suitable hemocompatible material such as a metal, plastic, wood, latex, synthetic rubber, or any combination of the above.

In general, each of the beads may have any suitable shape. For example, beads <NUM> may comprise at least one spherical bead 48a. Alternatively or additionally, beads <NUM> may comprise at least one bead comprising multiple faces; such a bead may move more in response to the blood flow, relative to spherical bead 48a, due to the greater force applied to the bead by the blood. Example of beads comprising multiple faces include a cubical bead 48b and a pyramidical bead 48c.

In general, larger beads may be more noticeable than smaller beads; hence, in some embodiments, for each bead <NUM>, the Cartesian distance between any two points on the outer surface of the bead is greater than <NUM>. Alternatively or additionally, for increased movement of the bead, the Cartesian distance between any two points on the outer surface of the bead may be less than <NUM>.

In some embodiments, each of the beads is coated with an anticoagulant, such as heparin.

In some embodiments, for greater visibility, the color of the beads contrasts with that of blood <NUM>. Suitable contrasting colors include black, blue, and white. Alternatively, the beads may have any other color.

In some embodiments, exit port <NUM> is covered with a filter configured to inhibit any of the beads from passing through. Alternatively or additionally, as described above, filter chamber <NUM> may be coupled to the flow-indication chamber downstream from the flow-indication chamber, such that any beads that pass through exit port <NUM> are filtered from the blood by filter <NUM>.

Reference is now made to <FIG>, which is a schematic illustration of apparatus <NUM>, in accordance with some embodiments of the present invention. An inset portion <NUM> of <FIG> shows part of the interior of apparatus <NUM>.

In some embodiments, moveable objects <NUM> comprise a rotational member configured to rotate in response to the blood exerting a force on the rotational member.

For example, moveable objects <NUM> may comprise a wheel <NUM> comprising a plurality of spokes <NUM> (which may also be referred to as "radial members") and configured to rotate in response to blood <NUM> exerting a force on spokes <NUM>. For noticeability, the length of each spoke <NUM> may be greater than <NUM>, and/or the width of each spoke may be greater than <NUM>. Alternatively or additionally, to obviate the need for an overly large flow-indication chamber, the length of each spoke <NUM> may be less than <NUM>, and/or the width of each spoke may be less than <NUM>.

Using two dashed lines, inset portion <NUM> demarcates the unimpeded path <NUM> of the blood, i.e., the path from entry port <NUM> to exit port <NUM> that the blood would follow in the absence of wheel <NUM>. Typically, wheel <NUM> is positioned relative to the entry and exit ports such that each spoke, when perpendicular to path <NUM> at any point along the path, intersects the path. Thus, the flow of blood through the flow-indication chamber generally keeps the wheel rotating in a single direction. For example, in <FIG>, the wheel rotates clockwise, as indicated by a rotation indicator <NUM>.

For example, denoting the end of the spoke closest to hub <NUM> as the proximal end of the spoke and the opposite end as the distal end of the spoke, the most proximal point on the spoke that intersects path <NUM> may be located between <NUM>% and <NUM>% of the length of the spoke from the proximal end of the spoke. (For example, if the spoke is <NUM> long, the most proximal point on the spoke that intersects path <NUM> may be located between <NUM> and <NUM> from the proximal end of the spoke. ) Advantageously, this positioning of the wheel may increase the rotational force to which the wheel is subjected.

In some embodiments, the internal walls <NUM> of flow-indication chamber <NUM> constrict the space within the chamber in which the blood can flow, such that the blood follows path <NUM> at a greater speed and hence, applies greater force to the rotational member.

Typically, as shown in Section A-A, wheel <NUM> is mounted onto a shaft <NUM> (i.e., shaft <NUM> passes through hub <NUM>), such that the wheel rotates about the shaft. Shaft <NUM> is coupled at each of its ends to wall <NUM>.

The rotational member (e.g., wheel <NUM>) may be any suitable color, including a color that contrasts with that of blood, as described above for beads <NUM> (<FIG>).

In alternative embodiments, Doppler ultrasound is used to measure the rate of blood flow. For example, a fixture, shaped to define a socket, may be fitted over one of the tubes, and a standard Doppler ultrasound probe may be inserted into the socket.

In some embodiments, apparatus <NUM> further comprises a valve <NUM> configured to regulate the flow of blood through the flow-indication chamber. Thus, using valve <NUM>, a physician may control the rate at which blood is shunted.

In some embodiments, valve <NUM> comprises a pushable element <NUM> passing through wall <NUM> and configured to cover entry port <NUM> or exit port <NUM> upon being pushed into the flow-indication chamber. Typically, a gasket <NUM> (made of rubber, for example) seals the aperture in wall <NUM> through which the pushable element passes, such that blood does not leak through the wall.

In such embodiments, valve <NUM> further comprises a spring <NUM> coupled to the pushable element (e.g., by virtue of being coupled to a ledge <NUM> coupled to the pushable element) and to an inner wall of the flow-indication chamber (e.g., the inside of wall <NUM>). Spring <NUM> is configured to inhibit the pushable element from covering the entry port or exit port in the absence of any pushing force applied to the pushable element. Thus, to slow or stop the flow of blood, the physician must continuously exert a pushing force to counteract the force applied by the spring, such that the physician is unlikely to forget that the flow has been slowed or stopped.

Typically, as shown in <FIG>, spring <NUM> comprises a tension spring <NUM>. In the absence of any pushing force, spring <NUM> is maximally compressed, such that the tension spring holds the pushable element in its outermost position.

In some embodiments, pushable element <NUM> comprises a neck <NUM> and a foot <NUM>, which protrudes from the end of neck <NUM> that is inside the flow-indication chamber. As neck <NUM> is pushed further into the flow-indication chamber, foot <NUM> covers a greater portion of the entry port or exit port, thereby slowing the flow of blood. Upon the neck being maximally pushed, foot <NUM> completely covers the port, such that the flow is stopped. Optionally, the opposite end of neck <NUM>, which is outside the flow-indication chamber, may terminate at a head <NUM>, which is wider than the neck and thus facilitates the pushing of the neck into the flow-indication chamber.

In other embodiments, valve <NUM> comprises a pullable element passing through wall <NUM> and configured to cover entry port <NUM> or exit port <NUM> upon being pulled.

(It is noted that valve <NUM> may also be combined with any other suitable embodiment of moveable objects <NUM>, such as the embodiment of <FIG>.

Reference is now made to <FIG>, which is a schematic illustration of apparatus <NUM>, in accordance with some embodiments of the present invention.

In some embodiments, apparatus <NUM> comprises tube constrictor <NUM>, which may also be referred to as a "locking clip. " Tube constrictor <NUM> comprises a first appendage 90a, shaped to define a first aperture 92a, and a second appendage 90b, shaped to define a second aperture 92b.

As further described below with reference to <FIG>, tube constrictor <NUM> is configured to control the rate of blood flow through a tube passing through apertures 92a and 92b by constricting the tube with varying degrees of constriction. Thus, apparatus <NUM> need not necessarily comprise valve <NUM> (<FIG>).

For example, tube constrictor <NUM> may provide two degrees of constriction: no (<NUM>%) constriction, and full (<NUM>%) or partial (e.g., <NUM>%-<NUM>%) constriction. Alternatively, tube constrictor <NUM> may provide three or more degrees of constriction. An example of four degrees of constriction is <NUM>%, <NUM>%-<NUM>% (e.g., <NUM>%), <NUM>%-<NUM>% (e.g., <NUM>%), and <NUM>%-<NUM>%.

(In the context of the present application, including the claims, the tube may be considered to be constricted by x% if the rate of blood flow through the tube is (<NUM>-x)% of what the rate would be if the tube were not constricted at all.

According to the invention, flow-indication chamber <NUM> is coupled to filter chamber <NUM> via coupling tube <NUM>, and tube constrictor <NUM> is configured to constrict the coupling tube. For example, as shown in <FIG>, first appendage 90a and second appendage 90b protrude from filter chamber <NUM> in the upstream direction, i.e., the first and second appendages protrude beyond entry port <NUM>, and coupling tube <NUM> carry blood to entry port <NUM> through the first and second apertures. Alternatively, the first and second appendages may protrude from flow-indication chamber <NUM> in the downstream direction, i.e., the first and second appendages may protrude beyond exit port <NUM>, and coupling tube <NUM> may carry blood from exit port <NUM> through the first and second apertures.

According to the invention, tube constrictor <NUM> is configured to constrict entry tube <NUM>. In other words, first appendage 90a and second appendage 90b protrude from flow-indication chamber <NUM> in the upstream direction, i.e., the first and second appendages protrude beyond entry port <NUM>, and entry tube <NUM> carries blood to entry port <NUM> through the first and second apertures. (In this case, flow-indication chamber <NUM> may be coupled to filter chamber <NUM> as in <FIG>, or filter chamber <NUM> may be omitted.

In yet other such embodiments, tube constrictor <NUM> is configured to constrict exit tube <NUM>. In other words, first appendage 90a and second appendage 90b protrude from filter chamber <NUM> in the downstream direction, i.e., the first and second appendages protrude beyond exit port <NUM>, and exit tube <NUM> carries blood from exit port <NUM> through the first and second apertures. (In this case, flow-indication chamber <NUM> may be coupled to filter chamber <NUM> as in <FIG>, or flow-indication chamber <NUM> may be omitted.

For those embodiments in which apparatus <NUM> comprises flow-indication chamber <NUM>, the flow-indication chamber may contain any suitable moveable objects <NUM>, such as wheel <NUM> or beads <NUM> (<FIG>).

In some embodiments, the first and second appendages are continuous with the wall of the chamber from which the appendages protrude, i.e., the wall extends beyond the chamber so as to define the appendages. In other embodiments, the appendages are coupled to the wall of the chamber, e.g., using any suitable adhesive.

Typically, each appendage comprises a back arm <NUM>, which protrudes from the chamber, and a front arm <NUM>, which is angled (e.g., at approximately <NUM> degrees) with respect to back arm <NUM> and is shaped to define the aperture through which the tube passes.

Reference is now made specifically to inset portion <NUM> of <FIG>, which shows the back of front arm <NUM> of first appendage 90a, i.e., the surface of the front arm that faces second appendage 90b.

In addition to first aperture 92a, first appendage 90a (e.g., front arm <NUM> of the first appendage) is shaped to define a first row 94a of one or more teeth <NUM>. Similarly, as shown in <FIG>, second appendage 90b (e.g., front arm <NUM> of the second appendage) is shaped to define a second row 94b of one or more teeth <NUM> parallel to first row 94a. As further described below with reference to <FIG>, second row 94b is configured to interlock with first row 94a at multiple different relative positions of the first appendage and second appendage. In these different positions, second aperture 92b is aligned with first aperture 92a with different respective degrees of alignment such that coupling tube <NUM> (or any other tube passing through the apertures) is constricted with different respective degrees of constriction.

Reference is now made to <FIG>, which are schematic illustrations of tube constrictor <NUM>, in accordance with some embodiments of the present invention.

In <FIG>, the first and second appendages are at a first relative position in which second aperture 92b is aligned with first aperture 92a, such that coupling tube <NUM> is not constricted. Subsequently, one or both of the appendages may be shifted such that the appendages assume a second relative position in which the two apertures are less aligned with one another, and hence tube <NUM> is mostly constricted, as shown in <FIG>.

In some embodiments, as shown in <FIG>, each tooth <NUM> is angled backward (e.g., toward back arm <NUM> of the appendage), such that the tooth comprises a longer front edge <NUM> and a shorter back edge <NUM>. In such embodiments, the tube may be constricted by advancing the two rows of teeth relative to one another, e.g., by pushing at least one front arm <NUM> toward the back arm <NUM> of the other appendage. For example, as indicated in <FIG> by pinch indicators <NUM>, the appendages may be pinched together, e.g., using a forefinger placed on one back arm <NUM> and a thumb placed on the other back arm. As one or both of the rows are advanced, front edges <NUM> slide across each other, until the rows of teeth interlock at the next position by virtue of the contact between back edges <NUM>, which inhibits the rows from sliding backward.

In other embodiments, each tooth <NUM> is angled forward, toward the tip of the appendage. In such embodiments, the tube may be constricted by moving at least one row of teeth backward relative to the other row of teeth, e.g., by pulling at least one front arm <NUM> away from the back arm <NUM> of the other appendage.

In some embodiments, the first and second appendages are configured to revert to a default relative position, in which the tube is not constricted, upon a release of first row 94a and second row 94b from one another, as indicated in <FIG> by release indicators <NUM>. In other words, at least one of the appendages is elastic, such that any movement from the default relative position causes the appendage to store elastic energy that, upon release of the rows from one another, causes the appendage to revert to the default position. Alternatively or additionally, upon release, the first and second appendages may revert to their default relative position due to elastic energy stored in the wall of the tube while the tube is constricted.

(It is emphasized that the appendages may be shaped to define fewer teeth than are shown in the figures. For example, one appendage may be shaped to define a single tooth, and the other appendage may be shaped to define N ≥ <NUM> teeth, such that N degrees of constriction are provided.

Typically, the tube is not completely constricted in any of the positions in which the rows of teeth interlock with one another. In other words, as shown in <FIG>, even at the most constricted interlocked position, the tube may remain partly (e.g., <NUM>%-<NUM>%) unconstricted. Thus, advantageously, full constriction of the tube requires that the physician continuously apply a force to one or both of the appendages, such that the physician is unlikely to forget that the flow has been stopped. For example, in the scenario shown in <FIG>, full constriction of the tube may require a continuous pinching of the appendages. In the absence of a pinching force, the elastic energy stored in the appendages and/or the wall of the tube causes the appendages to revert to the most constricted interlocked position.

(For embodiments in which the teeth are angled backward, the most constricted interlocked position is that in which the frontmost tooth of one appendage locks against the backmost tooth of the other appendage. For embodiments in which the teeth are angled forward, the most constricted interlocked position is that in which the frontmost tooth of one appendage locks against the frontmost tooth of the other appendage.

Claim 1:
Apparatus (<NUM>) for use with a tube (<NUM>, <NUM>, <NUM>) for carrying blood, the apparatus comprising:
a chamber (<NUM>, <NUM>) shaped to define a fluid port (<NUM>, <NUM>, <NUM>, <NUM>);
a first appendage (90a) protruding, from the chamber (<NUM>, <NUM>), beyond the fluid port (<NUM>, <NUM>, <NUM>, <NUM>) and shaped to define a first aperture (92a) and a first row (94a) of one or more teeth (<NUM>); and
a second appendage (90b) protruding, from the chamber (<NUM>, <NUM>), beyond the fluid port (<NUM>, <NUM>, <NUM>, <NUM>) and shaped to define a second aperture (92b) and a second row (94b) of one or more teeth (<NUM>) parallel to the first row (94a) of teeth (<NUM>),
the fluid port (<NUM>, <NUM>, <NUM>, <NUM>) being configured to couple to the tube (<NUM>, <NUM>, <NUM>) while the tube (<NUM>, <NUM>, <NUM>) passes through the first aperture (92a) and second aperture (92b), such that the tube (<NUM>, <NUM>, <NUM>) carries the blood to or from the fluid port (<NUM>, <NUM>, <NUM>, <NUM>) through the first aperture (92a) and second aperture (92b), and
the second row (94b) being configured to interlock with the first row (94a) at multiple different relative positions of the first appendage (90a) and second appendage (90b) in which the second aperture (92b) is aligned with the first aperture (92a) with different respective degrees of alignment, such that the tube (<NUM>, <NUM>, <NUM>) is constricted with different respective degrees of constriction.