USRE50332E1 - Intravascular rotary blood pump - Google Patents

Abstract

An intravascular rotary blood pump possesses a catheter (10), a pumping device (50) disposed distally of the catheter and having at its distal end a flexible flow cannula (53) through which blood is either sucked or discharged by the pumping device (50) during operation of the blood pump, and at least one pressure sensor (27, 28A, 30) having at least one optical fiber (28A) which is laid along the flow cannula (53). The optical fiber (28A) and, where applicable, a sliding tube (27) in which the optical fiber (28A) is laid extend along a neutral fiber of the flow cannula (53).

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 9,474,840 (the '840 patent). This application is a reissue continuation application of U.S. application Ser. No. 16/169,720 filed Oct. 24, 2018, which issued on Jul. 20, 2021 as U.S. Pat. No. RE48,649, which is a reissue of U.S. application Ser. No. 14/396,700 filed on Oct. 23, 2014, now U.S. Pat. No. 9,474,840 which issued on Oct. 25, 2016, which is a U.S. national phase application claiming the benefit of International Application Serial No. PCT/EP2013/058715, filed on Apr. 26, 2013, which in turn claims the benefit ofDE 10 2012 207 053.2, filed on Apr. 27, 2012,; this application is also a reissue of U.S. Pat. No. 9,474,840; the entire disclosures of which are hereby incorporated by reference for all purposes in their entirety as if fully set forth herein.

This invention relates to an intravascular rotary blood pump having one or more pressure sensors for measuring pressures within the patient's vascular system which are significant for operating the blood pump and/or for assessing the state of health of the patient's heart.

WO 2011/039091 A1 describes in connection with a heart support system a pressure-measuring catheter which has a catheter hose and a pressure sensor for measuring the pressure distally of the catheter hose. Concretely, the pressure-measuring catheter has an optical pressure sensor and an elongate tube made of metal or a high-strength plastic, for example PEEK, through which a loosely laid optical fiber of the optical pressure sensor extends. At the anterior (distal) end of the pressure-measuring catheter there is located a sensor head which works on the Fabry-Pérot principle. The sensor head possesses a cavity which is terminated by a thin, pressure-sensitive glass membrane, on the one hand, and into which the end of the optical fiber protrudes, on the other hand. The pressure-sensitive glass membrane is deformed in dependence on the size of the pressure acting on the sensor head. Through the reflection on the glass membrane, the light exiting from the optical fiber is modulatingly reflected and fed into the optical fiber again. At the proximal end of the optical fiber there is located an evaluation unit having an integrated CCD camera, which evaluates the obtained light in the form of an interference pattern. In dependence thereon, a pressure-dependent electrical signal is generated. Altogether this is thus an optoelectronic pressure sensor.

The pressure-measuring catheter is employed in connection with intravascular heart support systems, such as for example an intra-arterial balloon pump (IABP) or an intravascular rotary blood pump, by first advancing the relevant heart support system to the desired place in the patient's vascular system, i.e. for example into the aorta or into a heart chamber, by means of a catheter hose. The pressure-measuring catheter including the tube surrounding the optical fiber is displaceable relative to this catheter hose in its longitudinal direction and is subsequently introduced into the lumen of the catheter hose, advanced through the catheter hose and exits from its end. When the sensor head has reached the intended measurement location, the tube of the pressure-measuring catheter is withdrawn, but can also remain in situ. In connection with a rotary blood pump, it is proposed to push the pressure-measuring catheter far beyond the distal end of the catheter hose and past the pump device of the rotary blood pump, so that it crosses the aortic valve and protrudes with its sensor head into the left ventricle to thereby measure the ventricular pressure.

It would be in principle desirable if the sensor head of the optical pressure sensor was already brought to the proper place with the placement of the rotary blood pump, as is known for example in connection with pressure sensors wherein the pressure is transferred to an extracorporeal pressure-measuring device via a hydrostatic pressure-transfer hose. Thus, there is known for example from US 2003/0187322 A1 a rotary blood pump whose pumping device possesses at the distal end a flow cannula having embedded therein a hydrostatic pressure-transfer hose which extends to the distal end of the flow cannula and is subjected to the blood pressure there.

However, an optical pressure sensor comprising an optical fiber cannot readily be laid along the flow cannula. For the flow cannula, on its way to placement in the heart, is subjected to great bends or flexions which would exert non-negligible tensile and compressive stresses on an optical fiber laid along the flow cannula. Even if the optical fiber was laid freely within a separate pressure-measuring lumen, the frictional forces occurring due to relative motions between the optical fiber and the pressure-measuring lumen could be so great that the optical fiber breaks or tears. This holds in particular for optical fibers made of glass. Such optical fibers are normally covered with a thin plastic coating, such as polyimide (Kapton), which offers some protection from breakage. Nevertheless, the danger of breakage is not ruled out, and it would be great trouble to have to replace the entire blood pump placed in the patient if the optical fiber actually breaks.

The object of the present invention is hence to configure a rotary blood pump having an optical pressure sensor's sensor head fixed to the flow cannula such that the danger of breakage of the optical fiber of the optical pressure sensor is reduced to a great extent.

This object is achieved by an intravascular rotary blood pump having the features of claim1. Claims dependent thereon state advantageous developments and embodiments of the invention.

Accordingly, an intravascular rotary blood pump, according to a preferred embodiment of the invention, comprises a catheter, a pumping device disposed distally of the catheter and having at its distal end a flexurally flexible flow cannula through which blood is either sucked or discharged by the pumping device during operation of the blood pump, and at least one pressure sensor having at least one optical fiber. According to the invention, the optical fiber is laid along a “neutral fiber” of the flow cannula.

The “neutral fiber” of the flow cannula extends in the longitudinal direction of the flow cannula and is characterized in that it is not, or at least less, preferably considerably less, flexurally flexible than the rest of the flow cannula, so that the flow cannula does not bend, or at least does not bend as easily, along the neutral fiber when the blood pump is guided with the flow cannula in front through the patient's vascular system. By definition, the neutral fiber, upon flexion of the cannula, lies exactly between the compressed and extended regions and ideally undergoes no change of length.

Because the optical fiber extends along the neutral fiber of the flow cannula, i.e. either coincides with a neutral fiber or lies in the same “neutral bending plane” as the neutral fiber, the optical fiber undergoes no compression or extension whatsoever when the rotary blood pump is guided with the flow cannula in front through the patient's vascular system and adapts itself to the different radii of curvature of the vessels.

In the simplest case, the optical fiber can for this purpose be bonded by means of an elastic bonding agent on the inside or outside of the flow cannula along a neutral fiber of the flow cannula. However, for safety's sake it is preferred to dispose the optical fiber in a freely movable manner within a sliding tube laid along the neutral fiber, in order to thereby additionally protect the optical fiber against the risk of breakage due to extensions or compressions.

The neutral fiber of the flow cannula can be realized in different ways. Thus, it is possible for example to impose a neutral fiber, so to speak, by locally strengthening the flow cannula, e.g. by incorporating or applying a flexurally stiff or tensilely and compressively stiff strip along the flow cannula. This is expedient in particular in rotary blood pumps whose flow cannula extends straight in the normal state. Such local strengthening can be obtained for example by a sufficiently rigid lumen or sliding tube in which the optical fiber is laid.

However, the flow cannula frequently has a preset precurvature. Upon navigation of the rotary blood pump through the patient's vascular system, the flow cannula then bends in such a way that this preset curvature becomes stronger and lesser depending on the bending direction. Between the inner radius of curvature and outer radius of curvature of the flow cannula as defined by the precurvature, there is accordingly a neutral fiber, that is, altogether two neutral fibers, namely on both sides of the flow cannula. The precurvature can in turn be preset or stabilized by means of a flexurally stiff strip along the neutral fiber or fibers.

In case the danger of an extension or compression of the optical fiber exists in spite of the optical fiber being laid along the neutral fiber of the flow cannula, it is preferred—as stated—to lay the optical fiber freely movably in a separate sliding tube. Nevertheless, fiber breaks can also occur in this case—as likewise already stated—e.g. because the fiber is subjected to excessive extension or compression within the sliding tube due to high friction. It is hence preferable to choose a sliding material pairing with a low coefficient of friction for the outer surface of the optical fiber and the inner surface of the sliding tube. This may be a metal-metal sliding material pairing, a metal-plastic sliding material pairing or a plastic-plastic material pairing, with the plastic preferably being or at least comprising polytetrafluoroethylene (PTFE).

For this purpose, the optical fiber is accordingly coated with polytetrafluoroethylene on the outer side. Conventional optical fibers, in contrast, are usually coated with polyimide (Kapton). However, the optical fiber can also have an outer metal coating, which can be vapor-deposited for example, in order to form a metal-metal sliding material pairing or metal-plastic sliding material pairing with the inner surface of the sliding tube. For metal regularly has a lower coefficient of friction than conventional plastics.

The sliding tube in which the optical fiber is laid freely movably can be a simple hose, in particular also a stretchable hose, which is possible due to the fact of its being laid along the neutral fiber of the flow cannula. However, a metallic material is preferred for the sliding tube, which might be plastic-coated on the inside, preferably again with polytetrafluoroethylene (PTFE). A metallic sliding tube is compressively and tensilely stable and hence suited for imposing a neutral fiber on the flow cannula. In such rotary blood pumps whose flow cannula already has a preset neutral fiber through precurvature, this neutral fiber is additionally stabilized by the metallic sliding tube.

It is particularly preferred when the sliding tube is formed from a material comprising a shape-memory alloy. The best-known example of such a shape-memory alloy is so-called “nitinol”. The special benefit of shape-memory alloys in the present connection is that shape-memory alloys show superelastic behavior. The flow cannula can thereby follow even extreme curvatures without the sliding tube being plastically deformed or the circular cross section being deformed so as to damage the optical waveguide. Instead, the sliding tube bends back into the original shape. Due to this special material property, the lumen can be designed very small with only little clearance for the light guide. Consequently, the cannula, too, can thus still remain thin-walled.

A further advantage of a sliding tube made of shape-memory metal lies in the drastically reduced break sensitivity upon multiple bending load or buckling load. While a “normal” metal tube breaks more easily in this case and thus constitutes a local weak point, thus even increasing the probability of a subsequent fiber break, the tube made of shape-memory metal remains bending-elastic longer and thus continues to reliably prevent fiber break.

It is further preferred when the sliding tube in which the optical fiber is laid freely movably is filled with liquid. This can further reduce the frictional forces between the surface of the optical fiber and the surface of the sliding tube.

The optical fiber employed is preferably a glass fiber, because it is easy to handle and inexpensive. In particular, there are particularly thin glass fibers which do not break even at very narrow bend radii due to their small diameter. This is of special importance in connection with the attachment of the optical fiber to the flow cannula, for it can happen that the flow cannula runs into an obstacle, e.g. the sinus of the aortic valve, and briefly folds 180° when advancing through the blood vessels.

Furthermore, a small diameter of the optical fiber is also advantageous for keeping the cross-sectional dimensions of the blood pump as small as possible. This holds in particular when the optical fiber or the sliding tube containing the optical fiber extends along the flow cannula on the outside. For the greater the diameter of the optical fiber or the diameter of the sliding tube is, the greater the cross-sectional dimensions of the blood pump are, and this can be disadvantageous upon placement of the blood pump and/or upon operation of the blood pump in the patient's vascular system. Hence, it is preferred to provide an optical fiber, in particular an optical fiber comprising a glass fiber, having a diameter of 130 μm or less.

When the sensor head of the pressure sensor or, in general terms, the distal end of the pressure sensor is fixed on the outside of the flow cannula, e.g. on an inflow cage lying at the distal end of the flow cannula, the sensor head is received at least partly in a depression which is provided in the outer surface of the flow cannula. This protects the sensitive sensor head from a collision with a sluice valve or hemostatic valve when the blood pump is being introduced into the patient's vascular system.

However, it may be that the wall thickness of the flow cannula is not sufficient for producing a depression with a depth in which the sensor head can be completely received, so that the distal end of the pressure sensor projects radially beyond the periphery of the flow cannula. In particular in such cases it is advantageous to provide distally before the sensor head a bulge likewise projecting beyond the periphery of the flow cannula, in order to prevent the hemostatic valve or sluice valve from getting caught at the distal end of the pressure sensor when the blood pump is introduced into the patient's vascular system. This bulge can alternatively also be configured such that it is present not only distally before the sensor but also laterally or also proximally. Advantageously, this U- or O-shaped bulge is so configured that the sensor-head contour fits completely into the protective contour, i.e. possesses no edges projecting beyond the protective contour (bulge). This bulge can be for example a bead of bonding agent, which might also only be applied after the sensor head has been fixed in the depression. The bulge can alternatively also be welded or soldered on the flow cannula.

Hereinafter the invention will be explained by way of example with reference to the accompanying drawings. Therein are shown:

FIG.1 a blood pump laid through the aorta, extending through the aortic valve into the left ventricle and having an integrated pressure sensor,

FIG.2 an optical pressure sensor having an optical fiber,

FIG.3 the pumping device of the blood pump fromFIG.1 in greater detail,

FIGS.4A,4B the detail A fromFIG.3 in plan view and in side view,

FIGS.5A,5B the detail B fromFIG.3 in plan view and in side view, and

FIG.6 a cross section through a pressure sensor having an optical fiber guided in a sliding tube.

FIG.1 shows an intravascular blood pump having acatheter10 which is introduced into the descending aorta11 retrograde. The descending aorta is part of theaorta12 which first ascends from the heart and then descends and has theaortic arch14. At the beginning of theaorta12 there is located theaortic valve15 which connects theleft ventricle16 to theaorta12 and through which the intravascular blood pump extends. The intravascular blood pump comprises in addition to the catheter10 arotary pumping device50 fastened at the distal end of thecatheter hose20 and having amotor section51 and apump section52 disposed at an axial distance therefrom, as well as aflow cannula53 protruding in the distal direction from the inflow end of thepump section52 and having asuction inlet54 located at its end. Distally of thesuction inlet54 there is provided a soft-flexible tip55, which can be configured for example as a “pigtail” or in a J shape. Through thecatheter hose20 there extend different lines and devices which are important for operating thepumping device50. Of these,FIG.1 only shows twooptical fibers28A,28B which are attached at their proximal end to anevaluation device100. Theseoptical fibers28A,28B are respectively part of an optical pressure sensor whose sensor heads30 and60 are located on the outside on the housing of thepump section52, on the one hand, and on the outside in the vicinity of thesuction inlet54, on the other hand. The pressure transmitted by the sensor heads30 and60 is converted into electrical signals in theevaluation device100 and displayed e.g. on adisplay screen101.

The measurement of both the aortic pressure by means of thesensor head60 and the ventricular pressure by means of thesensor head30 makes possible, in addition to the actual pressure signal, e.g. a contractility measurement by which the recovery of the heart is measured, as well as the establishment of the pressure difference which is used for computing the flow of thepumping device50.

The principle of electro-optical pressure measurement will be explained more closely hereinafter with reference toFIG.2.FIG.2 shows a pressure-measuringcatheter26 having a lumen or slidingtube27 in which anoptical fiber28A (which might also be a plurality of optical fibers or theoptical fiber28B) is freely movable. The slidingtube27 can consist of a polymer, in particular polyurethane, or preferably of nitinol or another shape-memory alloy, exit from thecatheter hose20 at an exit point57 (cf.FIG.1), and be laid along theflexible flow cannula53 e.g. on the outside. Within thecatheter hose20 the separate slidingtube27 can be omitted. At thedistal end34 of theoptical fiber28A the pressure-measuring catheter has asensor head30 having ahead housing31 which contains athin glass membrane32 which terminates acavity33. Theglass membrane32 is pressure-sensitive and is deformed in dependence on the size of a pressure acting on thesensor head30. Through the reflection on the membrane the light exiting from theoptical fiber28A is reflected modulatingly and coupled back into the optical fiber. The coupling in can be effected either directly into theform28A or indirectly via a bottom37 terminating thecavity33 in a vacuum-tight manner. Advantageously, the bottom37 is an integral part of thehead housing31. Thus, the specification of the pressure in thecavity33 can be effected independently of the mounting of theoptical fiber28A. At the proximal end of theoptical fiber28A, i.e. in theevaluation device100, there is located a digital camera, such as e.g. a CCD camera or a CMOS, which evaluates the incoming light in the form of an interference pattern. In dependence thereon, a pressure-dependent electrical signal is generated. The evaluation of the optical image or optical pattern delivered by the camera and the computation of the pressure are effected through theevaluation unit100. The latter passes the already linearized pressure values to the control means, which also controls the power supply to the motor-operatedpumping device50 in dependence on the effected evaluation of the pressure signal.

Instead of the optical pressure sensor described with reference toFIG.2, which works on the Fabry-Pérot principle, other optical pressure sensors with one or more optical fibers can also be employed.

Thepumping device50 fromFIG.1 is represented in further detail inFIG.3. One can see adrive shaft57 protruding from themotor section51 into thepump section52, which drives animpeller58 by means of which, during operation of the blood pump, blood is sucked through the blood pass-throughopenings54 at the distal end of theflexible flow cannula53 and discharged proximally of theimpeller58 through the blood-flow pass-throughopenings56. Thepumping device50 can also pump in the reverse direction when it is adapted accordingly. Leading through thecatheter hose20 of thecatheter10 to thepumping device50 are the above-mentionedoptical fibers28A,28B, on the one hand, and a power-supply line59A for themotor section51 and a purge-fluid line59B.

Thesensor head60 of the first pressure sensor is fixed on the outside of the pump housing of thepump section52. The appurtenantoptical fiber28B is guided in a thinplastic hose21 over a short distance of for example 5 cm within thecatheter hose20, in order to ensure that theoptical fiber28B does not break upon strong curvatures of thecatheter10 in this region of thecatheter hose20. Outside thepumping device50 theoptical fiber28B is laid freely and only bonded to the outer wall of thepumping device50 by means of bonding agent. This minimizes the outer cross-sectional dimensions of thepumping device50. The bonding of theoptical fiber28B is possible because thepumping device50 is rigid in this region and theoptical fiber28B hence does not have to be movable relative to thepumping device50.

In contrast, theoptical fiber28A leading to thesensor head30 of the second pressure sensor is laid freely in a hose or tubelet, preferably a nitinol tubelet, along the total periphery of thepumping device50, so that it can shift relative to thepumping device50 within this hose or tubelet upon changes of bend of theflow cannula53. The hose or tubelet thus forms the slidingtube27 for theoptical fiber28A and extends along a neutral fiber of theflow cannula53 on the outer surface of the flow cannula. It is likewise possible to lay the slidingtube27 inside theflow cannula53, in particular when a pressure inside theflow cannula53 is to be measured, or to integrate it into the walling of theflow cannula53.

The neutral fiber of theflow cannula53, in the exemplary embodiment represented inFIG.3, results from the flow cannula possessing a precurvature which facilitates the laying of the blood pump in the patient's vascular system. Due to this precurvature, theflow cannula53 has an inner radius of curvature and an outer radius of curvature between which, substantially in the middle, a neutral bending plane extends. Theflow cannula53 possesses neutral fibers where this central bending plane intersects the flow cannula. The neutral fiber or neutral plane of theflow cannula53 as preset by the precurvature is strengthened by the slidingtube27 laid there. However, a neutral fiber of the flow cannula as intended by the present invention is also understood to include all other lines extending within the neutral plane, since no line or “fiber” extending within this plane is subjected to pressure loads or tensile loads when the precurvature of theflow cannula53 is strengthened or lessened on its way through the patient's vascular system. The strengthening of the neutral fiber by the slidingtube27 can moreover be of special advantage, since it prevents or at least lessens a bend of the cannula perpendicular to the sheet plane. This anisotropy can make it easier for the user to advance the cannula through the curved vascular system.

As explained at the outset, theoptical fiber28A can also be laid and fixed along a neutral fiber of theflow cannula53 directly without an additional slidingtube27. Freely laying theoptical fiber28A within the slidingtube27 laid along the neutral fiber serves only to give theoptical fiber28A additional resistance to breakage.

The hose and/or tubelet of the slidingtube27 in which theoptical fibers28A,28B are laid can extend shortly into thecatheter hose20, but can also extend completely through thecatheter hose20 and end in a corresponding plug at the end of the line for insertion of the relevant pressure sensor into a connection of theevaluation device100.

Distally before and/or beside and/or behind the sensor heads30 and60 there is respectively provided abulge35,65 which protects the sensor heads30 and60 from damage upon introduction of the blood pump through a hemostatic valve or sluice valve. Furthermore, the sensor heads30 and60 are respectively set in adepression36,66 of thepumping device50. This is not represented inFIG.3 and will be explained hereinafter with reference toFIGS.4A,4B and5A,5B.

FIG.4A shows the detail A fromFIG.3 in greater detail and partly in cross section.FIG.4B basically shows the same detail A but in plan view from above. Accordingly, thesensor head60 is received in a countersunk manner in adepression66 provided on the outer surface of thepump section52, thedepression66 being surrounded by a horseshoe- orU-shaped bulge65. The bulge could also be closed to form an O shape. It is bonded on or welded on, but can also form an integral part of thepump section52. Theoptical fiber28B is bonded on the surface and extends along a bar between two blood-flow pass-throughopenings56.

In a similar manner (FIGS.5A and5B), thesensor head30 of the second pressure sensor is also received in a countersunk manner in adepression36 on the outer surface at the distal end of theflow cannula53. Here, too, thenitinol tubelet27 with theoptical fiber28A laid therein extends through over a bar between two blood-flow pass-throughopenings54. A point-shapedbulge35 distally directly before thedepression36 protects thesensor head30 from collision damage upon introduction of the blood pump. Thebulge35, too, can alternatively be configured in a U shape or O shape and in particular be bonded on, welded on or an integral part of theflow cannula53.

Thesensor head30 can alternatively extend together with the slidingtube27 up to an arbitrary place on the soft-flexible tip55 and be protected mechanically there e.g. by the walling of the soft-flexible tip55. Bending-induced pressure artifacts are low, since the sensor membrane is disposed orthogonally to the walling. Only the bonded connection between theoptical waveguide34 and the sensor head must be protected against bending. This can be effected through thetubelet27 or an additional stiffening in the region of the bonding.

Theoptical fiber28B as well as theoptical fiber28A are preferably glass fibers, which are usually polymer-coated. Optical fibers made of plastic are likewise employable. However, optical fibers made of glass can be manufactured especially thin, which is favorable—in particular in combination with the additional slidingtube27—for minimizing the total cross section of thepumping device50. It is thus advantageous to employ optical fibers with a glass core which do not exceed a total diameter of 130 μm. It is true that such thin optical fibers are especially in danger of breaking when they are subjected to tensile or compressive forces. However, this risk is reduced to a great extent by disposing the optical fiber along the neutral fiber of theflow cannula53. The slidingtube27 can then possess an inner diameter of only 150 μm. The outer diameter then lies slightly thereabove, for example at 220 μm, so that the total cross section of thepumping device50 is not significantly increased. For it is to be taken into consideration that the slidingtube27 must always be laid outside thepumping device50 at least in the region of thepump section52. Tubelets made of the shape-memory alloy, nitinol, are commercially available with the above-mentioned inner and outer diameters. However, it is also possible to employ sliding tubes, in particular nitinol tubelets, with greater diameters, for example an inner diameter of 230 μm and an outer diameter of 330 μm. Theoptical fiber28A can then also have an accordingly greater diameter.

FIG.6 shows a cross section through a slidingtube27 with anoptical fiber28 laid therein, which comprises a glass-fiber core28_core, a so-calledcladding28_cladlikewise made of glass and anouter polymer coating28_coat. The different refractive indices of the optical-fiber core28_coreand of the optical-fiber cladding28_cladensure that light coupled into the optical-fiber core is transmitted along theoptical fiber28 virtually losslessly. Theouter coating28_coatserves to protect theoptical fiber28 against breakage. While thecoating28_coatis usually a polyimide coating, it is advantageous within the scope of the present invention to provide acoating28_coatas low in friction as possible, in particular made of polytetrafluoroethylene (PTFE). Theouter coating28_coatcan also be a metallic coating. The glass-fiber core28_corecan possess a diameter of e.g. 62.5 μm. The reflective layer could then increase the diameter to 80 μm. Thecoating28_coatcan possess a thickness of 10 μm. The diameter of theoptical fiber28 preferably amounts altogether to approx. 100 μm or less.

There is a distinction between normal optical fibers and graded-index fibers. In graded-index fibers the glass-fiber cladding28_cladis formed by a plurality of superjacent glass layers with different refractive indices. The employment of graded-index fibers is preferred in connection with the present invention because they are more bendable and more lossless than simple glass fibers.

The slidingtube27 consists for its part of an outer casing27a, with an inner-side coating27i. The outer casing27a substantially defines the bending and extension properties of the slidingtube27, while the inside coating27i is essential for reducing the frictional forces acting between the slidingtube27 and theoptical fiber28. The inside coating27i is hence preferably a metallic coating or again a low-friction polymer coating, in particular made of polytetrafluoroethylene.

The slidingtube27 can additionally be filled with a liquid in order to minimize frictional forces that occur.

Claims (24)

The invention claimed is:

1. An intravascular rotary blood pump, comprising a catheter (10), a pumping device (50) disposed distally of the catheter (10) and having at its distal end a flexurally flexible flow cannula (53) through which blood is either sucked or discharged by the pumping device (50) during operation of the blood pump, and at least one pressure sensor (27,28A,30) having at least one optical fiber (28A), characterized in that the optical fiber (28A) is laid along a neutral fiber of the flow cannula (53).

2. The blood pump according toclaim 1, wherein the neutral fiber is preset by a precurvature of the flow cannula (53) and accordingly lies between an inner radius of curvature and outer radius of curvature of the flow cannula as defined by the precurvature.

3. The blood pump according toclaim 1, wherein the optical fiber (28A) is bonded along the neutral fiber.

4. The blood pump according toclaim 1, wherein the optical fiber (28A) is laid freely movably in a sliding tube (27) along the neutral fiber.

5. The blood pump according toclaim 4, wherein the sliding tube (27) extends along the flow cannula (53) on the outside.

6. The blood pump according toclaim 4, wherein an outer surface of the optical fiber (28A) and an inner surface of the sliding tube (27) form a sliding material pairing of metal-metal, metal-plastic or plastic-plastic.

7. The blood pump according toclaim 6, wherein the plastic comprises polytetrafluoroethylene (PTFE).

8. The blood pump according toclaim 4, wherein the sliding tube (27) is formed from a material comprising a shape-memory alloy.

9. The blood pump according toclaim 4, wherein the sliding tube (27) is plastic-coated on the inside.

10. The blood pump according toclaim 4, wherein the optical fiber (28A) has an outer metal coating (28_coat).

11. The blood pump according toclaim 4, wherein the optical fiber (28A) has an outer plastic coating (28_coat) made of polytetrafluoroethylene (PTFE).

12. The blood pump according toclaim 4, wherein the sliding tube (27) is filled with liquid.

13. The blood pump according toclaim 1, wherein the optical fiber (28A) comprises a glass fiber (28_core,28_clad,28_coat).

14. The blood pump according toclaim 1, wherein the optical fiber (28A) possesses a diameter of 130 μm or less.

15. The blood pump according toclaim 1, wherein the flow cannula (53) has an outer surface in which there is configured a depression (36) in which a distal end (30) of the pressure sensor is at least partly disposed.

16. The blood pump according toclaim 1, wherein the flexurally flexible flow cannula (53) has a soft-flexible tip (55) and wherein a distal end (30) of the pressure sensor is at least partly disposed in the soft-flexible tip (55).

17. The blood pump according toclaim 1, wherein a distal end (30) of the pressure sensor projects radially beyond the periphery of the flow cannula (53), and wherein there is provided on the flow cannula (53) distally before the distal end (30) of the pressure sensor a bulge (35) likewise projecting beyond the periphery of the flow cannula (53).

18. An intravascular rotary blood pump, comprising:

a catheter (10),

a pumping device (50) disposed distally of the catheter (10) and having at its distal end a flexurally flexible flow cannula (53) through which blood is either sucked or discharged by the pumping device (50) during operation of the blood pump, and

at least one pressure sensor (27, 28A, 30) having at least one optical fiber (28A) fixed along a neutral fiber of the flow cannula (53) selected to prevent breakage of the fiber (28A) during bending of the flow cannula (53) while the blood pump is guided through a vascular system of a patient, wherein the neutral fiber of the flow cannula (53) is formed by locally strengthening the flow cannula.

19. The blood pump according toclaim 18, wherein the cannula is strengthened by a tube (27) that extends through walling of the flow cannula (53).

20. The blood pump according toclaim 18, wherein the cannula is strengthened by a tube (27) that extends along an outer surface of the flow cannula (53).

21. The blood pump according toclaim 18, wherein the optical fiber (28A) is configured to undergo substantially no extension while the blood pump is guided through the vascular system of the patient.

22. The blood pump according toclaim 18, wherein the optical fiber (28A) is configured to undergo substantially no compression while the blood pump is guided through the vascular system of the patient.

23. The blood pump according toclaim 18, wherein the optical fiber (28A) is locally strengthened by applying a stiff strip along the flow cannula.

24. The blood pump according toclaim 23, wherein the stiff strip is one of flexurally stiff, tensilely stiff, or compressively stiff.

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