IMPLANTABLE DEVICE FOR DETERMINING A FLUID VOLUME FLOW THROUGH A BLOOD VESSEL

Abstract

The invention relates to an implantable device (1) for determining a fluid volume flow (2) through a blood vessel (3), comprising: —at least one sensor (4) for recording at least one flow parameter, —a retaining means (5) for retaining a vessel wall port (6) in the region of a vessel wall (7) of the blood vessel (3), wherein the retaining means (5) is formed to retain the at least one sensor (4) in the region of the vessel wall (7).

Claims

1.-15. (canceled)

16. A device for determining a blood volume flow through a blood vessel, comprising: at least one sensor configured to detect at least one flow parameter of blood in the blood vessel, the blood vessel being in fluid communication with a pump of a cardiac assist system, a retaining means configured to retain a vessel wall port in or on a vessel wall of the blood vessel and configured to retain the at least one sensor in or on the vessel wall.

17. The device according to claim 16, wherein the at least one sensor comprises an ultrasonic element.

18. The device according to claim 16, wherein the at least one sensor is configured to perform a pulsed Doppler measurement.

19. The device according to claim 16, wherein the at least one sensor is configured to record a blood vessel cross-section of the blood vessel.

20. The device according to claim 16, wherein the at least one sensor comprises two ultrasonic elements.

21. The device according to claim 20, wherein the two ultrasonic elements are offset relative to one another in a flow direction of the blood in the blood vessel.

22. The device according to claim 20, wherein the two ultrasonic elements are arranged opposite each other and aligned facing each other.

23. The device according to claim 16, wherein the sensor is configured to change a main beam direction of the sensor.

24. The device according to claim 16, wherein the retaining means comprises a cuff that at least partially circumferentially enwraps the blood vessel.

25. The device according to claim 16, wherein the vessel wall port is configured to receive a portion of the cardiac assist system.

26. The device according to claim 25, wherein the retaining means is configured to position the vessel wall port to receive the portion of the cardiac assist system.

27. The device according to claim 16, wherein the vessel wall port comprises a lead-through for a cable of the cardiac assist system.

28. The device according to claim 16, wherein the vessel wall port comprises an opening for a bypass line of the cardiac assist system.

29. A system comprising: a cardiac assist system configured to be implanted within a blood vessel; and a device configured to determine blood volume flow of blood within the blood vessel, the device comprising: at least one sensor configured to detect at least one flow parameter of the blood in the blood vessel; and a retaining means configured to retain a vessel wall port in or on a vessel wall of the blood vessel and configured to retain the at least one sensor in or on vessel wall.

30. The system according to claim 29, wherein the vessel wall port is configured to receive a portion of the cardiac assist system, and wherein the retaining means is configured to position the vessel wall port to receive the portion of the cardiac assist system.

31. The system according to claim 29, wherein the vessel wall port comprises a lead-through for a cable of the cardiac assist system.

32. The system according to claim 29, wherein the vessel wall port comprises an opening for a bypass line of the cardiac assist system.

33. A method for determining a blood volume flow through a blood vessel having a cardiac assist system implanted therein, the method comprising: performing a measurement with at least one sensor of a device, the device comprising a retaining means configured to retain a vessel wall port in or on a vessel wall of the blood vessel and configured to retain the at least one sensor in or on the vessel wall; and determining the blood volume flow based at least in part on the measurement.

34. The method according to claim 33, wherein the vessel wall port comprises a lead-through for a cable of the cardiac assist system.

35. The method according to claim 33, wherein the vessel wall port comprises an opening for a bypass line of the cardiac assist system.

Description

[0045] The solution presented here as well as its technical environment are explained in more detail below with reference to the figures. It is important to note that the invention is not limited by the shown exemplary embodiments. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and/or insights from other figures and/or the present description. The following are shown schematically:

[0046] FIG. 1 an arrangement proposed herein,

[0047] FIG. 2 a further arrangement proposed herein,

[0048] FIG. 3 a device proposed herein,

[0049] FIG. 4 a further device proposed herein in a cross-sectional view,

[0050] FIG. 5 the device according to FIG. 3 in a further cross-sectional view, and

[0051] FIG. 6 a sequence of a method presented herein in a standard operating procedure,

[0052] FIG. 1 shows schematically an arrangement 14 proposed herein. The arrangement 14 comprises a device 1 proposed herein and an implantable vascular (here: ventricular) assist system 15. The arrangement is shown herein in an exemplary implanted state, wherein the assist system 15 passes through an aortic valve 17 and protrudes into a left ventricle 16. This illustrates an exemplary embodiment of an implanted left ventricular heart assist system 15 in the aortic valve position. In addition, the device 1 is arranged in the region of an ascending aorta 3.

[0053] The device 1 shown herein in an exemplary implanted state is formed to determine a fluid volume flow 2 through a blood vessel 3 (here the aorta). For this purpose, the device 1 comprises a sensor 4 for recording at least one flow parameter (here: the fluid volume flow 2) and a retaining means 5 for retaining a vessel wall port 6 in the region of a vessel wall 7 of the blood vessel 3. Here, the retaining means 5 is formed to retain the at least one sensor 4 in the region of the vessel wall 7.

[0054] The vessel wall port 6 of the device 1 in this case comprises a feed through 10 for a cable 11 of the assist system 15. The vessel wall port 6 or the feed through 10 in this case serves as an example for feeding out an electrical supply cable 11 for a (fully) implanted assist system 15 in the aortic valve position. In other words, the vessel wall port 6 forms in particular a port component of the device 1.

[0055] FIG. 2 shows schematically another arrangement 14 proposed herein. The arrangement 14 comprises a device 1 proposed herein, an implantable vascular (here: ventricular) assist system 15, and a control unit 20. The reference symbols are used uniformly so that reference can be made to the above explanations.

[0056] FIG. 2 illustrates an exemplary embodiment of an apically implanted left ventricular heart assist system 15. According to the illustration according to FIG. 2, the vessel wall port 6 of the device 1 has an opening 12 for a bypass line 13 of the assist system 15. The vessel wall port 6 or the opening 12 in this case serve as an example for recirculating a pump volume conveyed into the cardiovascular system by means of the assist system 1.

[0057] The control unit 20 can also be implanted (for fully implanted systems). However, this is not mandatory. In transcutaneous systems, for example, a first supply line 18 and a second supply line 19 can be guided through the skin to an extracorporeal control unit 20.

[0058] FIG. 3 shows schematically a device 1 proposed herein. The reference symbols are used uniformly so that reference can be made to the above explanations.

[0059] The retaining means 5 is in this case formed by way of example to retain the sensor 4 on the vessel wall 7. Furthermore, the retaining means 5 is formed by way of example in the shape of a cuff that at least partially circumferentially enwraps the blood vessel 3. The design as a cuff allows in an advantageous manner for a higher mechanical stability to be achieved and for the presence of installation space for sensors, for example ultrasonic transducers.

[0060] In FIG. 3, the sensor 4 comprises an ultrasonic element 8. In addition, the sensor 4 is formed for carrying out a pulsed Doppler method.

[0061] The flow calculation can be carried out using a single ultrasonic transducer 8 according to the Pulsed Wave Doppler method (PWD method). The ultrasonic transducer 8 sends an ultrasonic pulse and analyzes the phase progression of the sound energy back scattered on the cellular components of the blood in the time measurement window. In addition, large acoustic impedance differences, such as those occurring between blood and the aortic wall, can be detected in the transient reception signal.

[0062] Furthermore, the sensor 4 is shown here by way of example for recording a flow-carrying blood vessel cross-section 9 (not shown here, cf. FIG. 4).

[0063] The spatial dimensions can be inferred from an analysis of the time of flight between the emitted pulse and the received aortic wall echo at a known speed of sound in the propagation medium. By combining both methods, it is possible to calculate the flow velocity with the Doppler method and to calculate the cross-sectional area of the aorta with the echo time of flight, so that the volume flow can be recorded or calculated with the best possible precision.

[0064] FIG. 4 shows schematically a further device 1 proposed herein in a cross-sectional view. The reference symbols are used uniformly so that reference can be made to the above explanations.

[0065] In FIG. 4, the one sensor 4 comprises two ultrasonic elements 8. The two ultrasonic elements 8 are positioned at an offset to one another in flow direction. Furthermore, the two ultrasonic elements 8 are arranged opposite each other and aligned facing each other. The illustration according to FIG. 4 illustrates by way of example the position of the ultrasonic transducers or ultrasonic elements 8 to each other.

[0066] FIG. 4 shows an exemplary embodiment wherein two ultrasonic transducers 8 are placed opposite the cuff 5. A pulsed ultrasonic method can also be used here. If the transducers 8 are not positioned orthogonally to the flow direction of the blood, the flow rate can be inferred based on the time of flight differences of the pulses from one ultrasonic element 8 to the other ultrasonic element 8 independently of the speed of sound in the medium. By means of the mean value of the signal time of flight, the geometry and thus the aortic cross-section 9 can also be inferred. It is advantageous for the method when low-focus ultrasonic transducers (ultrasonic elements) are used so that the method can remain operational even for poor positions of the sensors or the ultrasonic elements to each other (e.g. due to poor positioning or due to movement in the region of the aorta).

[0067] FIG. 5 schematically shows the device according to FIG. 4 in a further cross-sectional view.

[0068] Here, it is shown by way of example that the two ultrasonic elements 8 are arranged opposite each other and aligned facing each other such that the connecting line between both elements 8 extends centrally through the cross-section of the blood vessel to be examined. In addition, the transducers 8 are positioned at an offset to each other along the flow direction, so that one pulse direction points downstream and the other pulse direction points upstream. For example, the angle of the main beam direction and the main flow direction is in the range of 0° to 85°, advantageously for example in the range of 45° (compromise between placement on the outer wall with a still high parallel portion of the main beam direction to the flow direction).

[0069] However, for inter-individual differences of the aortic cross-section 9 and a uniform cuff size, the transducers 8 can—if the cuff 5 is too small and the aortic cross-sectional area 9 is too large—migrate toward 12 o'clock, for example the ultrasonic element 8 shown on the left in FIG. 5 to 10 o'clock and the ultrasonic element 8 shown on the right in FIG. 5 to 2 o'clock. In particular, the ultrasonic measurement discussed above can also be carried out in this case by means of low-focused elements 8 with approximately spherical characteristics. In this case, however, a time of flight based cross-sectional area calculation could possibly have a corresponding error. Because the aortic cross-section 9 is generally on average not subject to major changes versus time, a (known) aortic cross-section, for example predetermined sonographically, can be stored in a calibration data memory (e.g. formed in the control unit 20 of the arrangement 14) as an alternative to the measurement using mean pulse time of flight.

[0070] As an alternative to a uniform cuff size, a plurality of devices that differ in the diameter of their retaining means can be specified, for example. During an implantation of the device, the device can then be selected with the appropriate retaining means diameter for the blood vessel.

[0071] Furthermore, it can be specified that the sensor 4 can change a main beam direction of the sensor 4. In this context, the measuring accuracy of the system can be further increased in the presence of a swirl or vortex in the blood flow by integrating one or more ultrasonic array transducers instead of single ultrasonic transducers. The measurement plane of the transducers can be pivoted by so-called beam steering, thus advantageously permitting a reconstruction of the complete three-dimensional flow vector field. The method can be generalized to a wave-based interaction means, i.e.—apart from the longitudinal waves present in ultrasound—the effect also occurs in the electromagnetic spectrum in transversal waves, for example of a radar sensor or a laser Doppler velocimeter. In addition to ultrasonic transducers, the integration of radar or laser Doppler sensors is therefore also advantageous, as these can (each) change their main beam direction.

[0072] FIG. 6 schematically shows a sequence of a method presented herein in a standard operating procedure.

[0073] The method serves to determine a fluid volume flow through a blood vessel in the region of an implanted device. The illustrated sequence of the method steps a), b), and c) with the blocks 110, 120, and 130 results in a standard operating procedure. In block 110, a measurement is carried out with at least one sensor of the device, which is retained with a retaining means for retaining a vessel wall port in the region of a vessel wall of the blood vessel. A measurement result from step a) is provided in block 120. In block 130, the fluid volume flow is determined using the measurement result provided in step b).

[0074] The solution presented herein advantageously specifies a device, an arrangement, a method, and a use for determining the total cardiac output (HTV) of a patient with implanted left ventricular cardiac assist system (LVAD). The heart-time volume is an important parameter for assisting the human cardiovascular system with an assist system and can be (continuously) provided in a particularly advantageous manner with the solution proposed herein even outside of cardiac surgery and the subsequent intensive care medical treatment or during routine daily or continuous operation of the implanted assist system. In particular, this parameter (HTV) can be provided continuously as a control parameter for operating the assist system.

[0075] The solution proposed herein is based in particular on an integration of, for example, ultrasonic flow metrology into a retaining means for a vessel wall port, for example an aortic wall port as a feed-through for the connecting cable of a ventricular assist system. In particular when the device is located in the region of the aorta, both the blood flow generated by the assist system and the residual output capacity of the heart through the aortic valve past the assist system can thus be advantageously determined.

[0076] The solution presented herein in particular has one or more of the following advantages: [0077] For fully implanted assist systems, the thorax is opened to position an electronic control component. Access for attaching, for example, a silicone cuff around the aorta is therefore already provided. [0078] For (fully) implanted assist systems in the aortic valve position, the supply cable must be guided out of the aorta. The port required for this purpose is suitable as a cuff component for integrating flow metrology, so that no further components need to be integrated. [0079] Compared to devices without sensors, only the connection of the additional sensor cable is required during the implantation procedure. [0080] The solution allows continuous recording of the cardiac output in patients with a cardiac assist system.