The present disclosure relates to intravascular blood pumps having one or more sensors for measuring, such as for measuring pressures within a patient's vascular system.
Intravascular blood pumps can be introduced into a patient either surgically or percutaneously and used to deliver blood from one location in the bean or circulatory system to another location in the heart or circulatory system. For example, when deployed in the left heart, an intravascular blood pump can pump blood from the left ventricle of the heart into the aorta. Likewise, when deployed in the right heart, an intravascular blood pump can pump blood from the inferior vena cava into the pulmonary artery. Examples of such blood pumps include the Impella® family of devices (Abiomed, Inc., Danvers, Mass.).
Blood pump may have one or more sensors for measuring the patient's vascular system. For example, intravascular blood pumps may include one or more optical sensors for measuring pressures within a patient's vascular system, and particular a patient's ventricular cavity, which may be used for operating the blood pump and/or for assessing the state of health of the patient's heart.
A first aspect of the present disclosure is drawn to a system including a cannula and a flexible hypotube with specific geometric relationships. The cannula (which may be a flexible flow cannula) has an inner surface and an outer surface, which define a cannula wall having a thickness, the inner surface of the cannula defining a first lumen therethrough. The flexible hypotube is attached to the cannula, and has an outer surface and an inner surface, where the inner surface defines a second lumen therethrough. The system is configured to provide a ratio R1 of a diameter of the outer surface of the hypotube to a diameter of the inner surface of the cannula is 1:5>R1>1:25. The second lumen is arranged to slidably receive an optical fiber therethrough.
Advantageously, the optical fiber is arranged to freely move within the second lumen. In some embodiments, a ratio R2 of a diameter of an outer surface of the optical fiber to a diameter of the inner surface of the flexible hypotube is 1:3>R2>1:1.1
In some embodiments, the system further includes an inflow cage connected at or near a distal portion of the cannula. In some embodiments, a distal portion of the optical fiber is attached to the inflow cage. In some embodiments, the optical fiber includes an optical fiber sensor head at a distal end of the optical fiber, where the sensor may be configured to, e.g., measure ventricular pressure.
In some embodiments, the system further includes a pump operably connected to a proximal portion of the first lumen.
In some embodiments, the flexible hypotube may be positioned within the first lumen. In some embodiments, the flexible hypotube may be positioned outside the first lumen. In some embodiments, at least one portion of the flexible hypotube is positioned within the first lumen and at least one portion of the flexible hypotube is positioned outside the first lumen.
In some embodiments, the flexible hypotube has a distal end, a proximal end, and a tubular portion between the distal end and the proximal end, the tubular portion containing at least one laser cut that extends at least partially through a wall of the flexible hypotube, such as from the outer surface towards the inner surface. In some embodiments, the cuts (or a subset of the cuts) may extend all the way through the wall of the hypotube. In some embodiments, each cut my have a width of between 0.01 mm and 0.1 mm. In some embodiments, the tubular portion may extend all the way between the distal and proximal ends. In such embodiments, the entire hypotube may include cuts other than the distal and proximal ends. In other embodiments, the tubular portion includes a portion of the length of the hypotube between the distal and proximal ends. For example, the tubular portion may be between 20% and 80% of the length of the hypotube. In some embodiments, the tubular portion is centered between the distal and proximal ends. In that regard, the tubular portion may be a central portion of the hypotube.
As will be appreciated, the hypotube and tubular portion may have any suitable cross-sectional shape, although shown as being circular in cross section. For example, in other embodiments, the hypotube and tubular portion may be ovular, triangular, square, other polygonal or other suitable shape.
As described herein, the at least one cut (e.g., laser cut) can exist in a variety of configurations. In some embodiments, the at least one cut defines a helical cut extending axially along the tubular portion of the flexible hypotube.
In some embodiments, the at least one cut comprises a plurality of identical laser cuts. In some embodiments, each of the plurality of identical laser cuts may be offset only axially from all other laser cuts of the plurality of identical laser cuts. In some of these embodiments, each of the plurality of identical laser cuts may be offset axially from all other laser cuts of the plurality of identical laser cuts, and at least one laser cut is offset circumferentially from a neighboring laser cut, such as being offset circumferentially by 45°, 90°, or 180° from a neighboring laser cut. In some of these embodiments, the plurality of identical laser cuts may define at least two helical patterns, such as two helical patterns that are offset circumferentially.
A second aspect of the present disclosure is drawn to a system having a cannula and a flexible hypotube, where the flexible hypotube contains laser cuts in the hypotube. The cannula (which may be a flexible flow cannula) has an inner surface and an outer surface, which define a cannula wall having a thickness, the inner surface of the cannula defining a first lumen therethrough. The flexible hypotube may be attached to the cannula, and has an outer surface and an inner surface, where the inner surface defines a second lumen therethrough. The flexible hypotube includes a tubular portion containing at least one cut extending from the outer surface at least partially through the sidewall of the flexible hypotube, each cut having a maximum width of between 0.01 mm and 0.1 mm. The second lumen is arranged to slidably receive an optical fiber therethrough.
As described herein, the optical fiber may be arranged to freely move within the second lumen of the hypotube. In some embodiments, the system is configured to provide a ratio R2 of a diameter of an outer surface of the optical fiber to a diameter of the inner surface of the flexible hypotube is 1:3>R2>1:1.1. In some embodiments, the system is configured to provide a ratio R1 of a diameter of the outer surface of the hypotube to a diameter of the inner surface of the cannula is 1:5>R1>1:25.
In some embodiments, the flexible hypotube may include a coating or jacket.
In some embodiments, the system also includes an inflow cage connected at or near a distal portion of the cannula. In some embodiments, a distal portion of the optical fiber may be attached to the inflow cage. In some embodiments, the optical fiber includes an optical fiber sensor head at a distal end of the optical fiber, where the sensor may be configured to, e.g., measure ventricular pressure.
In some embodiments, the system further includes a pump operably connected to a proximal portion of the first lumen.
In some embodiments, the flexible hypotube may be positioned within the first lumen. In some embodiments, the flexible hypotube may be positioned outside the first lumen. In some embodiments, at least one portion of the flexible hypotube is positioned within the first lumen and at least one portion of the flexible hypotube is positioned outside the first lumen.
In some embodiments, the flexible hypotube includes a distal portion, a proximal portion, and a tubular portion between the distal portion and the proximal portion, the tubular portion containing at least one cut extending at least partially through the wall of the flexible hypotube, from the outer surface towards the inner surface, each cut having a maximum width of between 0.01 and 0.1 mm. In some embodiments, the cuts may extend all the way through the hypotube.
As with the above, the at least one cut may include a variety of configurations. In some embodiments, the at least one cut defines a helical cut extending axially along the tubular portion of the flexible hypotube. In some embodiments, the at least one cut includes a plurality of identical laser cuts. In some of these embodiments, each of the plurality of identical laser cuts are offset only axially from all other laser cuts of the plurality of identical laser cuts. In some of these embodiments, each of the plurality of identical laser cuts are offset axially from all other laser cuts of the plurality of identical laser cuts, and at least one laser cut is offset circumferentially from a neighboring laser cut, such as being offset circumferentially by 45°, 90°, or 180° from a neighboring laser cut. In some of these embodiments, the plurality of identical laser cuts may define at least two helical patterns, such as two helical patterns that are offset circumferentially.
A third aspect of the present disclosure is drawn to an intravascular blood pump. The pump will generally include a catheter, a pumping device, and at least one sensor. The pumping device may be disposed distally of the catheter and has at its distal end a cannula (which may be a flexible flow cannula) through which blood is either sucked or discharged by the pumping device during operation of the intravascular blood pump. The at least one sensor has at least one optical fiber slidably disposed in a flexible hypotube, the flexible hypotube being at least partially attached to the cannula, the flexible hypotube having a tubular portion containing at least one cut extending from an outer surface of the flexible hypotube towards an inner surface of the flexible hypotube, at least partially through a wall of the flexible hypotube. In some embodiments, the cut(s) may extend all the way through the flexible hypotube wall. In some embodiment, each cut includes a width of between 0.01 mm and 0.1 mm. In some embodiments, the flexible hypotube is configured to minimize and/or prevent breakage of the at least one optical fiber during bending of the flexible hypotube and cannula while the blood pump is guided through a vascular system of a patient.
Advantageously, the optical fiber is arranged to freely move within the second lumen. In some embodiments, the system is configured to provide a ratio R2 of a diameter of an outer surface of the optical fiber to a diameter of the inner surface of the flexible hypotube is 1:3>R2>1:1.1. In some embodiments, the system is configured to provide a ratio R1 of a diameter of the outer surface of the hypotube to a diameter of the inner surface of the cannula is 1:5>R1>1:25.
In some embodiments, the system also includes an inflow cage connected at or near a distal portion of the cannula. In some embodiments, a distal portion of the optical fiber is attached to the inflow cage. In some embodiments, the optical fiber has an optical fiber sensor head at a distal end of the optical fiber, where the sensor may be configured to, e.g., measure ventricular pressure.
In some embodiments, the system further includes a pump operably connected to a proximal portion of the first lumen.
In some embodiments, the flexible hypotube may be positioned within the first lumen. In some embodiments, the flexible hypotube may be positioned outside the first lumen. In some embodiments, at least one portion of the flexible hypotube may be positioned within the first lumen and at least one portion of the flexible hypotube is positioned outside the first lumen.
In some embodiments, the flexible hypotube includes a distal portion, a proximal portion, and a tubular portion having at least one cut extending at least partially through the flexible hypotube (e.g., from the outer surface towards the inner surface). For example, the cut may extend all the way through the hypotube wall. In some embodiments, each cut includes a maximum width of between 0.01 mm and 0.1 mm. The at least one cut may include a variety of configurations. In some embodiments, the at least one cut defines a helical cut extending axially along the tubular portion of the flexible hypotube. In some embodiments, the at least one cut includes a plurality of identical laser cuts. In some of these embodiments, each of the plurality of identical laser cuts are offset only axially from all other laser cuts of the plurality of identical laser cuts. In some of these embodiments, each of the plurality of identical laser cuts are offset axially from all other laser cuts of the plurality of identical laser cuts, and at least one laser cut is offset circumferentially from a neighboring laser cut, such as being offset circumferentially by 45°, 90°, or 180° from a neighboring laser cut. In some of these embodiments, the plurality of identical laser cuts define at least two helical patterns, such as two helical patterns that are offset circumferentially.
A fourth aspect of the present disclosure is a method of reducing strain on an optical fiber during insertion and use of a blood pump. The method includes providing a blood pump having (i) a cannula (which may be a flexible flow cannula) having an inner surface and an outer surface, the inner surface defining a first lumen therethrough, (ii) a flexible hypotube attached to the cannula, the flexible hypotube having an outer surface and an inner surface, the inner surface defining a second lumen therethrough, the flexible hypotube having a tubular portion containing at least one cut extending from the outer surface of the flexible hypotube towards an inner surface of the flexible hypotube at least partially through the flexible hypotube, each opening having a width of between 0.01 and 0.1 mm, and (iii) an optical fiber having an outer surface, the optical fiber laid slidably in the flexible hypotube. The method then includes moving the blood pump through a patient's vascular system, while allowing the optical fiber to move axially within the flexible hypotube while the blood pump is moving.
In some embodiments, the method further includes receiving as an input at an evaluation device a transmitted optical signal from the optical fiber sensor head, and then determining a pressure using the transmitted optical signal.
In some embodiments, the optical fiber is arranged to freely move within the second lumen. In some embodiments, the blood pump of the method is configured to provide a ratio R2 of a diameter of an outer surface of the optical fiber to a diameter of the inner surface of the flexible hypotube is 1:3>R2>1:1.1. In some embodiments, the blood pump of the method is configured to provide a ratio R1 of a diameter of the outer surface of the hypotube to a diameter of the inner surface of the cannula is 1:5>R1>1:25.
In some embodiments, the blood pump of the method further includes an inflow cage connected at or near a distal portion of the cannula. In some embodiments, a distal portion of the optical fiber is attached to the inflow cage. In some embodiments, the optical fiber has an optical fiber sensor head at a distal end of the optical fiber, where the sensor may be configured to, e.g., measure ventricular pressure.
In some embodiments, the blood pump of the method further includes a pump operably connected to a proximal portion of the first lumen.
In some embodiments, the flexible hypotube may be positioned within the first lumen. In some embodiments, the flexible hypotube may be positioned outside the first lumen. In some embodiments, at least one portion of the flexible hypotube is positioned within the first lumen and at least one portion of the flexible hypotube is positioned outside the first lumen.
In some embodiments, the flexible hypotube has a distal portion, a proximal portion, and a tubular portion between the distal portion and the proximal portion, the tubular portion containing at least one cut at least partially through the flexible hypotube extending from the outer surface towards the inner surface, each cut having a width of between 0.01 and 0.1 mm.
As with the above, the at least one cut may include a variety of configurations. In some embodiments, the at least one cut defines a helical cut extending axially along the tubular portion of the flexible hypotube. In some embodiments, the at least one cut includes a plurality of identical laser cuts. In some of these embodiments, each of the plurality of identical laser cuts are offset only axially from all other laser cuts of the plurality of identical laser cuts. In some of these embodiments, each of the plurality of identical laser cuts are offset axially from all other laser cuts of the plurality of identical laser cuts, and at least one laser cut is offset circumferentially from a neighboring laser cut, such as being offset circumferentially by 45°, 90°, or 180° from a neighboring laser cut opening. In some of these embodiments, the plurality of identical laser cuts define at least two helical patterns, such as two helical patterns that are offset circumferentially.
As is known, blood pumps may have sensors for monitoring a patient. For example, intravascular blood pumps may include optical sensors, such as for measuring pressures within a patient's vascular system, and particular a patient's ventricular cavity, which may be used for operating the blood pump and/or for assessing the state of health of the patient's heart.
As appreciated by the inventors, the cannula, on its way to placement in the heart, may be subjected to great bends or flexions which can exert non-negligible tensile and compressive stresses on an optical fiber laid along the cannula, which may cause damage to the optical fiber. For example, in an illustrative example, the optical fiber may become detached from the pump housing during insertion due to tensile and compressive stresses. This also may apply to optical fibers made of glass. Although such optical fibers are normally covered with a thin plastic coating, such as polyimide (Kapton), which offers some protection from breakage, the danger of breakage during insertion due to tensile and compressive stresses could still be problematic. For example, such damage may result in the entire blood pump having to be replaced (e.g., if the optical fiber breaks).
Accordingly, the inventors have recognized the advantages of a system and method for relieving the strain of an optical fiber associated with a cannula, such as a flexible flow cannula. As described herein, in some embodiments the system may include a flexible hypotube within which an optical fiber is slidably disposed. In this regard, the hypotube may form a protective sleeve within which the optical fiber may be seated. In some embodiments, the hypotube is associated with a cannula. For example, the hypotube may be disposed inside or outside the cannula. The hypotube may include one or more cuts (e.g., laser cuts).
Turning now to the figures,
As shown in
In some embodiments, the pump may include two optical fibers 28A, 28B that may be attached at their proximal end to an evaluation device 100. These optical fibers 28A, 28B may be respectively part of an optical sensor (such as a pressure sensor) whose sensor heads 30 and 60 may be located in the vicinity of the suction inlet 54, on the one hand, and on the outside on the housing of the pump section 52, on the other hand.
According to an aspect of the present disclosure, and as shown in
In some embodiments, the flexible hypotube may have a distal end, a proximal end, and a tubular portion including one or more cuts as described herein. As described herein, the tubular portion may extend along a length of the flexible hypotube, between the proximal and distal ends. In some embodiments, the tubular portion may extend along an entire length of the hypotube. In other embodiments, the tubular portion may extend along only a portion of the length of the hypotube. For example, in some embodiments, the tubular portion may include a middle portion of the hypotube. In such embodiments, the hypotube may include a distal portion, a middle portion, and the proximal portion. See, e.g.,
As shown in
The flexible hypotube 27 in which the optical fibers 28A, 28B are laid can, in some embodiments, extend shortly (e.g., less than 6 inches) into the catheter hose 20, but can also extend completely through the catheter hose 20 (see
In some embodiments (see, e.g.,
The flexible hypotube may include a single walled, hollow tube. In some embodiments, the hypotube may include one or more coatings around a single walled, hollow tube. For example, as seen in
The flexible hypotube will have a length 113. In some embodiments, the hypotube may be between 4 and 8 cm in length, such as between 5 and 7 cm in length.
As shown in
Referring briefly to
As represented in these views, an outer diameter 114 of the flexible hypotube 27 may be smaller than the inner diameter 117 which defines a lumen through the cannula 53. In some embodiments, these components may be configured such that a ratio R1 of a diameter 114 of the outer surface of the hypotube 27 to a diameter 117 of the inner surface of the cannula 53 is 1:5>R1>1:25. That is, that the inner diameter of the cannula may be between 5 and 25 times larger than the outer diameter of the hypotube, such as between 15 and 25 times larger than the outer diameter of the hypotube (that is, 1:15>R1>1:25).
Further, the inner diameter 115 of the flexible hypotube 27 may be larger than the outer diameter 116 of the optical fiber 28A. In some embodiments, these components are configured such that a ratio R2 of a diameter 116 of an outer surface of the optical fiber 28A to a diameter 115 of the inner surface of the flexible hypotube 27 may be 1:3>R2>1:1.1, such as 1:2>R2>1:1.1.
In some embodiments, the optical fiber may be arranged to freely move within the second lumen, such that the optical fiber can move, axially, independent of movement of the flexible hypotube. In some embodiments, this freedom may be a result of the optical fiber not being connected to the flexible hypotube. In some embodiments, this freedom may be a result of there being slack, or excess, optical fiber within the flexible hypotube. For example, in some embodiments, the optical fiber may be attached to the hypotube (i.e., adhered to the hypotube, or otherwise restricted from moving axially independently of the hypotube) at or near the proximal end of the hypotube, while a linear length of optical fiber within the flexible hypotube may be longer (e.g., up to 1.1-1.2 times longer) that the linear length of the flexible hypotube, such that when the cannula and flexible hypotube bend, there may be sufficient excess optical fiber within the hypotube that the optical fiber does not experience substantial tension. As will be appreciated, the optical fiber also may be attached to other suitable portions of the hypotube and/or to the pump (e.g., at an inflow cage).
As shown in
As seen in
While the length of each cut may vary, each cut may have a width w 155 of between 0.01 and 0.1 mm. For purposes herein, a cut made between point A and point B along the surface of the hypotube may follow a pathline that is a straight, a curved, or a freeform path. The pathline may have a distance (i.e., the length of the pathline), and the means of forming the cut (such as a laser cut) may define the width w of the cut. In some embodiments, the width w of a cut may be constant along the entire pathline. In other embodiments, the width w of a cut may vary. For example, in some embodiments, the width of a cut may be constant except for the very ends 180 of each cut (which may be rounded, etc.). In other embodiments, the width of the cut may vary in other suitable portions
As shown in
As seen in
As will be appreciated, the length of the cut (e.g., the length of the tubular portion) may extend along an entire length of the hypotube (e.g., in
While some embodiments utilize only a single cut, in some embodiments, the at least one cut may comprise a plurality of identical cuts, such as a plurality of identical laser cut openings.
For example, as shown in
As seen in
As shown in
While
Combinations of these cuts are also envisioned in other embodiments. For example, in some embodiments, one first long spiral cut may extend substantially the entire length of the tubular portion. In another embodiment, the hypotube may include a plurality of additional interrupted spiral cuts that are each offset circumferentially and/or axially from the first long spiral cut.
As seen in
In some embodiments, the at least one laser cut opening may be offset circumferentially by ±45°, ±90°, or 180° from a neighboring laser cut opening.
In some embodiments, at least one laser cut opening may be only offset circumferentially from a neighboring laser cut, and at least one laser cut opening may be offset circumferentially and axially from a neighboring laser cut.
As seen in
As seen in
Referring to
In some embodiments, a distal portion of the optical fiber is attached to the inflow cage 70, and in some embodiments, attached to an internal surface of the inflow cage.
Referring to
The pumping device 50 may be disposed distally of the catheter 10 and may have at its distal end, a cannula 53 (which may be a flexible flow cannula) through which blood either sucked or discharged by the pumping device 50 during operation of the intravascular blood pump. The at least one sensor having at least one optical fiber 28A may be laid slidably in a flexible hypotube 27, the flexible hypotube being at least partially attached to the cannula (e.g., on an inner or outer surface of the cannula. As described herein, the flexible hypotube may include a tubular portion containing at least one cut extending from an outer surface of the flexible hypotube towards an inner surface of the flexible hypotube at least partially through the flexible hypotube, each cut having a width of between 0.01 and 0.1 mm. In some embodiments, the flexible hypotube may be configured to minimize or prevent breakage of the at least one optical fiber during bending of the flexible hypotube and/or cannula, and/or to minimize or prevent detachment of an optical sensor from the pump (e.g., an optical sensor attached to an inlet housing) while the blood pump is guided through a vascular system (e.g., 11, 12, 14, 15, 16) of a patient.
The components of the blood pump, including the cannula, flexible hypotube, and sensor (optical fiber, sensor head, etc.) may be configured as described in any of the previous embodiments.
Also disclosed is a method of reducing strain on an optical fiber during insertion and use of a blood pump. Referring to
After the blood pump has been provided, the blood pump can then be moved through a patient's vascular system. Rather than keeping the optical fiber from moving, the optical fiber may be allowed 220 to move axially within the flexible hypotube while the blood pump is moving.
After the blood pump is moved, an evaluation device (c.f.
In some embodiments, the process of moving the blood pump and measuring pressures is repeated at least once. In some embodiments, it is repeated until the determined pressure indicates the blood pump is positioned correctly.
Referring again to
As seen in
In some embodiments, the evaluation device 100 may alternatively, or additionally, calculate a signal-to-noise ratio (SNR) based on the transmitted optical signal. For example, the optical signal that is transmitted from the distal sensor head 60 to the evaluation device 100 using optical fiber 28A can be used by the evaluation device 100 to calculate the SNR of the optical signal. The SNR can be linked to the mechanical vibrations of a pumping device 50. When the pumping device 50 is stopped, the motor current is zero and the mechanical vibrations of the pumping device 50 are at a minimum. During this state, the SNR may be relatively large because the noise level of the optical signal is low. When the pumping device 50 is running, the motor current is greater than zero and the mechanical vibration of the pumping device 50 increases. During this state, the SNR may be relatively low because the noise level of the optical signal is large.
The pumping device 50 from
Instead of the optical pressure sensor described with reference to
The components of the blood pump, including the cannula, flexible hypotube, and sensor (optical fiber, sensor head, etc.) may be configured as described in any of the previous embodiments.
Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.
The present application claims priority to U.S. Provisional Patent App. No. 63/282,407, filed Nov. 23, 2021, the contents of which are incorporated by reference herein in their entirety.
Number | Date | Country | |
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63282407 | Nov 2021 | US |