Ring seal and intravascular blood pump

Abstract

To provide an intravascular blood pump which provides protection against a high-pressure difference along the blood vessel.SOLUTION: An intravascular blood pump 1 comprises a ring seal 10 that is configured to assume a collapsed configuration and an expanded configuration and configured to contact and seal against an inner wall of the patient's blood vessel when inserted therein in the expanded configuration. A support member 12, 13 is disposed inside the ring seal 10 in order to support the ring seal 10 from the inside, where the support member 12, 13 is configured to collapse at least partially when a predetermined pressure difference between a proximal area and a distal area of the blood vessel acting on the ring seal 10 is exceeded.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an intravascular blood pump for percutaneous insertion into a patient's blood vessel, which may be a right ventricular assist device, i.e., a blood pump for assisting the function of the right ventricle of the patient's heart. [Background technology]

[0002] Intravascular blood pumps are used to assist the function of a patient's heart as a left ventricular assist device (LVAD) or a right ventricular assist device (RVAD). Intravascular blood pumps typically include a catheter and a pumping device attached to the catheter, which is inserted into the patient's heart, for example, through the aorta into the left ventricle or through the vena cava into the right ventricle. The catheter may have an elongated body with a proximal portion and a distal portion extending along a longitudinal axis, with the pumping device attached to the distal portion of the catheter, typically farther from an operator, such as a surgeon.

[0003] Ventricular assist devices can be used to treat a patient's cardiac dysfunction or malformation, such as a congenital heart defect. For example, during the Fontan procedure, an RVAD is inserted into a patient's heart to divert venous blood from the right atrium to the pulmonary artery, bypassing the failing right ventricle. Another use for RVADs is for patients with right ventricular dysfunction that may occur due to treatments incorporating an LVAD. An RVAD may be used in addition to an LVAD to relieve abnormally high pressure in the right ventricle, such as up to 25 mmHg, and to avoid right ventricular failure during left ventricular therapy. Normal, healthy venous blood pressure can range from approximately 3 to 5 mmHg.

[0004] When used as an RVAD, the pumping device is advanced through the pulmonary artery using a catheter toward one lung lobe. Because blood exiting the blood pump is directed toward the lungs, the pressure differential created by the blood pump is crucial, especially compared to an LVAD, which pumps blood from the left ventricle to the aorta. High pressure can damage the lung's blood vessels. Normal healthy pressure in the pulmonary artery ranges from about 10 mmHg to 25 mmHg, usually about 15 mmHg. Patients with heart disease may experience higher pulmonary artery pressures, such as 30 mmHg to 40 mmHg or even 70 mmHg to 100 mmHg. Summary of the Invention [Problem to be solved by the invention]

[0005] SUMMARY OF THE INVENTION It is an object of the present invention to provide an intravascular blood pump for percutaneous insertion into a patient's blood vessel that provides protection against high pressure differentials along the vessel. [Means for solving the problem]

[0006] This object is achieved according to the invention by a blood pump having the features of independent claim 1. Preferred embodiments of the invention and further developments are set out in the claims dependent on claim 1.

[0007] In accordance with the present invention, there is provided an intravascular blood pump for percutaneous insertion into a patient's blood vessel, the intravascular blood pump including a catheter, a pumping device, and a ring seal having a support member disposed within the ring seal. The pumping device includes a blood inlet, a blood outlet, and a rotor for allowing blood to flow from the blood inlet to the blood outlet. The ring seal is disposed between the blood inlet and the blood outlet of the pumping device.

[0008] The ring seal can be in a collapsed or expanded configuration and is configured to contact and seal against the inner wall of the patient's blood vessel in the expanded configuration when inserted into the blood vessel. In this manner, the ring seal separates the proximal region of the blood vessel from the distal region of the blood vessel. A support member is disposed inside the ring seal to support the ring seal from the inside, and the support member is configured to at least partially collapse when a predetermined pressure difference acts on the ring seal between the proximal and distal regions of the blood vessel. At the same time, the support member is configured to withstand a pressure difference of up to 100 mmHg, preferably a smaller pressure difference such as up to 50 mmHg, preferably up to 20 mmHg. Throughout this disclosure, the term "distal" refers to a direction away from the user toward the heart, and the term "proximal" refers to a direction toward the user. In other words, the ring seal collapses when the pressure difference between the inlet side and the outlet side generated by the blood pump is greater than a predetermined value. Preferably, the blood pump is configured to be inserted into the pulmonary artery.

[0009] The support member is specifically a mechanical support member, as described in more detail below. The support member is configured to maintain the ring seal in an expanded configuration up to a predetermined pressure differential, while at the same time being flexible enough to ensure that a predetermined pressure differential between the proximal and distal regions within the blood vessel is not exceeded. This is important, for example, to limit the pressure increase caused by a blood pump in the pulmonary artery. The ring seal, as described in more detail below, does not occlude the blood vessel at pressure differentials of 100 mmHg or more, preferably 20 mmHg or more. In other words, the ring seal acts like an overpressure valve, i.e., when a predetermined threshold pressure differential is exceeded, blood is allowed to flow through the ring seal toward the lower pressure side. Thus, the provision of the ring seal provides a self-regulating pressure within the blood vessel. The internal pressure of the ring seal is preferably atmospheric pressure, i.e., the interior of the ring seal can be in fluid communication with the environment, for example, using an open line.

[0010] The ring seal, particularly its overall outer shape independent of the catheter body extending therethrough, can have any size and shape suitable for the desired application. For example, the ring seal can be spherical, elliptical, cylindrical, or a combination thereof. The ring seal can be symmetric, particularly axisymmetric, about the central longitudinal axis of the catheter, or asymmetric. The outer diameter of the ring seal, particularly the outer diameter in the inflated configuration, can be selected depending on the application. In one embodiment suitable for application in the pulmonary artery, the outer diameter of the ring seal in the inflated configuration can be about 1 cm to about 2.5 cm. The pump device can have a length of about 3 cm to 6 cm.

[0011] Preferably, the support member is configured to withstand a predetermined pressure differential between the proximal and distal regions of up to about 20 mmHg, which is an appropriate pressure differential for applications in which the catheter is advanced into the pulmonary artery. In other words, the support member is configured to maintain the ring seal in an expanded configuration at a pressure differential between the proximal and distal regions within the blood vessel of up to 20 mmHg, and to collapse when the pressure differential exceeds 20 mmHg. Depending on the desired application, the predetermined pressure differential can range from about 5 mmHg to about 35 mmHg, more preferably from about 7 mmHg to about 30 mmHg.

[0012] In one embodiment, the ring seal includes a flexible membrane. Specifically, the membrane is flexible and resilient. In this way, the membrane can conform to the expanded and collapsed configurations of the ring seal. The membrane can form a shell surrounding the support structure. Specifically, the membrane can form a balloon having an inflation port that allows fluid to be supplied to and removed from the balloon. The inflation port can be connected to a fluid line extending along the elongate body of the catheter so that the balloon can be inflated by supplying fluid to the balloon and deflated by removing fluid from the balloon. Specifically, the fluid line can be a vacuum line that allows a vacuum or negative pressure to be created within the balloon to collapse the ring seal. The balloon and fluid line can be suitable for any fluid, such as a liquid or gas, specifically saline or air. As mentioned above, the pressure within the ring seal can be atmospheric pressure. Therefore, the fluid line connected to the balloon can be open to the environment or otherwise configured to equalize the pressure within the balloon with atmospheric pressure.

[0013] The support member may be at least partially compressible, which allows the support member to remain within the ring seal even in the collapsed configuration. Alternatively, or additionally, the support member may be withdrawn from the ring seal to bring the ring seal from the expanded configuration to the collapsed configuration.

[0014] Preferably, the support member may have a tendency toward the inflated configuration. This provides the ring seal with self-expanding (or self-inflating) and self-retaining properties. In other words, the ring seal tends to assume the inflated configuration when no load is applied, so that no external action is required to change the ring seal from the collapsed configuration to the inflated configuration. Specifically, the ring seal may be maintained in the collapsed configuration by applying a vacuum, and the ring seal may expand when the vacuum is released. However, the expansion of the ring seal may also be facilitated by external action, for example, using pressurized fluid supplied to the ring seal.

[0015] In one embodiment, the support member can include a foam or sponge. The foam can be a closed-cell foam or an open-cell foam. The foam can be inflated, for example, at atmospheric pressure, and can be compressed by applying a vacuum or other external force to the ring seal. In particular, when the foam is surrounded by a flexible membrane, the ring seal including the foam and membrane is particularly well-suited for adapting to the size and shape of the inner wall of a blood vessel. The properties of the foam can be selected to allow the ring seal to collapse at a predetermined minimum pressure. The foam can include any suitable material, particularly a polymeric material such as polyurethane. The structure of the foam or sponge is selected to establish a predetermined minimum pressure at which the ring seal will collapse, or in other words, a predetermined maximum pressure difference at which the support member will maintain its inflated configuration.

[0016] In another embodiment, the support member can include at least one elastic wire, preferably made of a shape memory material such as Nitinol. Other materials with shape memory or superelastic properties, such as nylon, can also be used. Generally, shape memory is a temperature-dependent property that allows a shape memory material to deform at one temperature and then return to its original, undeformed shape when heated above the material's "transformation temperature." This temperature change causes the material to transform between its martensite and austenite phases. Superelasticity is a temperature-independent property that allows a shape memory material to undergo mechanical deformation due to an external force applied to the shape memory material and then return to its original, undeformed shape when the external force is released. Superelasticity, also known as pseudoelasticity, is caused by a transformation between the martensite and austenite phases induced by an external load.

[0017] The wire, which may be made of Nitinol as described above, can be withdrawn from the ring seal to collapse it. Withdrawing the wire can straighten it by retracting it into the lumen of the catheter. Conversely, advancing the wire into the ring can cause the wire to assume a curved shape, thereby inflating the ring seal. The curved shape can be a predetermined shape of the shape-memory material, such as a spiral or other shape, to produce a desired inflated configuration of the ring seal. Specifically, the wire can apply a force to the flexible membrane from inside the ring seal to inflate it. Additionally, the ring seal can be filled with a fluid, such as a liquid or gas, upon inflation, although this is not required. Thus, withdrawing the elastic wire from the ring seal can remove the fluid from the ring seal.

[0018] In one embodiment, the ring seal may include a flexible shield extending from the outer periphery of the ring seal, i.e., from the outer periphery of the ring seal body. The flexible shield may be configured to contact the inner vessel wall when the catheter is inserted into the vessel and the ring seal is in an expanded configuration. The shield may be relatively soft and thin compared to the ring seal body, thereby reducing the risk of injury to the vessel and further improving the ring seal's adaptability to the vessel size and shape. The shield may be formed as a skirt or sleeve surrounding the ring seal and supported by the ring seal. The shield preferably collapses and expands when the ring seal collapses. The shield may have a proximal end attached to the ring seal and a free distal end configured to contact the inner vessel wall. Thus, the shield may be open in the direction of blood flow to prevent backflow and improve sealing properties. However, because the shield collapses when the ring seal collapses, the pressure difference within the vessel is limited as described above.

[0019] The shield may include a reinforcing structure. The reinforcing structure may have at least one fluid-receiving groove configured to expand when fluid is received to stiffen the shield and to collapse when the fluid is removed to soften the shield. For example, the shield may have longitudinally extending grooves to form an umbrella-shaped shield. It will be appreciated that any other size, shape, number, and configuration of grooves, such as a spiral curve, suitable for stiffening the shield are also possible. The groove or grooves may be completely filled or emptied, or only partially filled or emptied, allowing for tailoring of the shield's stiffness.

[0020] The foregoing summary, as well as the following detailed description of the preferred embodiments, will be better understood when read in conjunction with the accompanying drawings. For purposes of illustrating the present disclosure, reference is made to the drawings. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the drawings. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 illustrates an intravascular blood pump inserted into a patient's heart. [Figure 2] FIG. 1 shows a schematic cross-sectional view of a catheter ring seal according to one embodiment in an expanded configuration. [Figure 3] FIG. 3 shows the ring seal of FIG. 2 in a collapsed configuration. [Figure 4] FIG. 10 shows a schematic cross-sectional view of a ring seal of a catheter according to another embodiment in an expanded configuration. [Figure 5] FIG. 5 shows the ring seal of FIG. 4 in a collapsed configuration. [Figure 6a] 5A-5C show schematic cross-sectional views of different implementations of ring seals for the embodiment of FIG. 4. [Figure 6b] 5A-5C show schematic cross-sectional views of different implementations of ring seals for the embodiment of FIG. 4. [Figure 7] FIG. 10 shows a schematic cross-sectional view of a ring seal of a catheter according to yet another embodiment in an expanded configuration. [Figure 8] FIG. 8 shows the ring seal of FIG. 7 in a collapsed configuration. DETAILED DESCRIPTION OF THE INVENTION

[0022] FIG. 1 shows an intravascular blood pump inserted into a patient's heart (H). More specifically, in this exemplary embodiment, the blood pump 1 includes a catheter 100, through which the blood pump 1 is inserted via the inferior vena cava (IVC) through the right ventricle (RV) of the patient's heart (H) into the pulmonary artery (PA). In a different approach, the catheter may be inserted through the superior vena cava (SVC). In operation, the blood pump 1, specifically the catheter 100, extends through the tricuspid valve (TRV) and the pulmonary valve (PV). The blood pump 1 includes a pumping device 2 having a blood inlet (3) and a blood outlet (4). An impeller or rotor (not shown) is provided to direct blood into the blood inlet (3), toward the blood outlet (4), and out of the blood outlet (4). The blood pump 1 according to this embodiment is designed as a right ventricular assist device (RVAD) and can be used, for example, in a Fontan procedure or in addition to a left ventricular assist device (LVAD). The pumping device 2 is positioned in the pulmonary artery (PA).

[0023] The blood pump 1, and more specifically, the pumping device 2, includes a ring seal 10. The ring seal 10, which will be described in more detail below with reference to FIGS. 2-6, can be inflated or collapsed, and is shown in the inflated configuration in FIG. 1. The ring seal 10 contacts the inner wall of the pulmonary artery PA, thereby sealing the proximal portion of the pulmonary artery PA against the distal portion of the pulmonary artery PA. Operation of the blood pump 1 creates a pressure differential between the proximal and distal portions of the pulmonary artery PA, and more specifically, pressure increases from the proximal portion to the distal portion. To limit the pressure increase, the ring seal 10 is configured to collapse when a predetermined minimum pressure difference between the proximal and distal portions of the pulmonary artery PA is reached, i.e., the ring seal 10 withstands a pressure difference up to the predetermined pressure difference. In the collapsed configuration, the ring seal 10 allows blood to flow from the distal portion of the pulmonary artery PA through the pumping device 2 toward the proximal portion of the pulmonary artery PA. When the pressure differential drops below a predetermined minimum pressure, the ring seal 10 is allowed to re-inflate, which is facilitated by the self-expanding properties of the support members within the ring seal 10, as will be explained in more detail below. The predetermined minimum pressure differential may be approximately 20 mmHg for pulmonary artery PA applications.

[0024] Referring now to FIG. 2, a schematic longitudinal cross-sectional view of the ring seal 10 of the pumping device 2 is shown inserted into a blood vessel V. It will be appreciated that details of the blood pump 1 have been omitted for clarity. FIG. 2 shows the ring seal 10 in an inflated configuration disposed around the pumping device 2. The ring seal 10 includes a flexible membrane 11 forming a balloon-like element. The membrane 11 surrounds a support member 12, which in this embodiment comprises foam, specifically polyurethane foam. The foam is biased toward the inflated configuration to provide the ring seal 10 with self-expanding and self-retaining properties. Preferably, atmospheric pressure is applied to the interior of the ring seal 10 when in the inflated configuration. A vacuum line 14 can be provided for removing fluid, such as a liquid or gas, from the ring seal 10, e.g., to actively collapse the ring seal 10 during insertion of the pumping device 2 or to remove the pumping device 2 from the patient's heart H.

[0025] The ring seal 10 is shown in a collapsed configuration in FIG. 3. In the collapsed configuration, the foam is at least partially compressed. This can be achieved by removing fluid from the ring seal 10. However, specifically, the ring seal 10 will automatically collapse when a predetermined pressure differential between the opposing sides acting on the ring seal 10 is exceeded. The minimum pressure differential can be between 7 mmHg and 30 mmHg, and preferably 20 mmHg. The direction of the pressure differential between the higher and lower pressures is indicated by arrow P in FIG. 2.

[0026] FIG. 4 illustrates another embodiment similar to the embodiment of FIGS. 2 and 3 except for the support member within the ring seal 10. The vacuum line 14 is not shown in FIG. 4. However, it will be appreciated that a vacuum line may also be provided in this embodiment. The support member 13 comprises a resilient wire, specifically made of a shape-memory material such as Nitinol. The wire is shown schematically in FIG. 4. FIGS. 6a and 6b illustrate different examples of resilient wires in cross-sectional views perpendicular to the longitudinal axis of the pump device 2. To inflate the ring seal 10, the wire is advanced into the ring seal 10, for example, from a lumen extending through the pump device 2 along the catheter 100 and straightening the wire. After advancing into the ring seal 10, the wire assumes its predetermined curved shape. The curved shape may be, for example, a spiral as shown in FIG. 6a or another curved shape as illustrated in FIG. 6b. The wire acts against the flexible membrane 11 from within the ring seal 10, thereby inflating the ring seal 10. To collapse the ring seal 10, the wire can be pulled from the ring seal 10 as shown in Figure 5. The wire is configured to collapse the ring seal 10 when a predetermined minimum pressure is applied to the ring seal 10, or in other words, to support the ring seal 10 so that it can withstand pressure differences only up to a predetermined pressure difference.

[0027] In another embodiment, shown in FIG. 7 , the ring seal 10 includes a flexible shield 16 extending from a main body of the ring seal 10. The shield 16 is disposed on the outer periphery of the ring seal 10 and configured to contact the inner wall of the blood vessel V when the ring seal 10 is in the expanded configuration, as shown in FIG. 7 . The shield 16 may include a membrane and is relatively thin to protect the vessel wall and improve sealing against the vessel wall. Grooves 17 may be provided as reinforcing structures that can be filled with fluid to stiffen the shield 16. Fluid can be removed from the grooves 17 to soften the shield 16. As shown in FIG. 8 , the shield 16 collapses along with the ring seal 10 in the collapsed configuration. Similar to the previous embodiment, the ring seal 10, including the shield 16, is configured to collapse when a predetermined minimum pressure differential acts on the ring seal 10 between a proximal portion of the pulmonary artery PA and a distal portion of the pulmonary artery PA to avoid excessive pressure buildup within the pulmonary artery PA.

Claims

1. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising a catheter (100) and a pumping device (2) attached to said catheter (100), said pumping device (2) having a blood inlet (3), a blood outlet (4), and a rotor (8) for causing blood to flow from said blood inlet (3) to said blood outlet (4), said blood pump comprising: a ring seal (10) disposed between the blood inlet (3) and the blood outlet (4) of the pump device (2), the ring seal being configured to assume a collapsed configuration and an expanded configuration, the ring seal being configured to contact and seal against an inner wall of the patient's blood vessel in the expanded configuration upon insertion into the vessel to separate a proximal region of the vessel from a distal region of the vessel; and support members (12, 13) disposed inside the ring seal (10) to support the ring seal from the inside, configured to at least partially collapse when a predetermined pressure difference between the proximal region and the distal region of the blood vessel acts on the ring seal (10), and capable of withstanding a pressure difference of up to 100 mmHg before collapsing.

2. 2. The blood pump of claim 1, wherein the support members (12, 13) are configured to withstand a pressure difference between the proximal and distal regions of up to 20 mmHg before the support members (12, 13) collapse.

3. 3. A blood pump according to claim 1 or 2, characterized in that the support members (12, 13) are configured to withstand a pressure difference between the proximal and distal regions of from about 5 mmHg to about 35 mmHg, preferably from about 7 mmHg to about 30 mmHg.

4. 4. A blood pump according to any one of claims 1 to 3, characterized in that the ring seal (10) comprises a flexible membrane (11).

5. 5. The blood pump of claim 4, wherein the ring seal (10) defines the balloon with an inflation port that allows fluid to be supplied to and removed from the balloon.

6. 6. The blood pump of claim 5, wherein the inflation port is connected to a fluid line (14) so ​​that the balloon can be inflated by supplying fluid to the balloon and deflated by removing fluid from the balloon.

7. 7. A blood pump according to any one of claims 1 to 6, characterized in that the support members (12, 13) are at least partially compressible.

8. 8. A blood pump according to any one of claims 1 to 7, characterized in that the support members (12, 13) tend towards the expanded configuration.

9. 9. A blood pump according to any one of the preceding claims, characterized in that the support member (12) comprises a foam or a sponge.

10. 10. A blood pump according to any one of the preceding claims, characterized in that the support member (13) comprises at least one elastic wire, preferably made of a shape memory material such as Nitinol.

11. 11. A blood pump according to any one of claims 1 to 10, characterized in that the outer diameter of the ring seal (10) in the expanded configuration is from about 1 cm to about 2.5 cm.

12. 12. The blood pump according to claim 1, wherein the ring seal includes a flexible shield extending from an outer periphery of the ring seal, the flexible shield configured to contact an inner wall of the blood vessel when the catheter is inserted into the blood vessel and the ring seal is in the expanded configuration.

13. 13. The blood pump of claim 12, wherein the shield (16) has a proximal end attached to the ring seal and a free distal end configured to contact the inner wall of the blood vessel.

14. 14. The blood pump according to claim 12 or 13, wherein the shield (16) includes a reinforcing structure (17) having at least one fluid-receiving groove configured to be expanded by receiving a fluid to harden the shield (16) and to be collapsed by removing the fluid to soften the shield (16).

15. 15. An intravascular blood pump according to any one of claims 1 to 14, adapted to be inserted into a pulmonary artery.

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