Wireless pullback distance sensor for IVUS system

Abstract

This invention relates to intravascular techniques where measuring the retraction distance is important, such as intravascular ultrasound (IVUS) imaging. The invention describes hardware, circuit architecture, and methods for wirelessly transmitting data related to the retraction distance of a catheter introduced into a blood vessel.

Description

Technical Field

[0001] Related Application Data: This application claims the benefit of U.S. Provisional Patent Application No. 63 / 464,338, filed May 5, 2023, entitled "Wireless Pullback Distance Sensor," which is hereby incorporated by reference in its entirety.

[0002] This disclosure relates to intravascular ultrasound (IVUS), and more particularly, to systems and methods for measuring the pullback distance of an IVUS catheter.

Background Art

[0003] Intravascular ultrasound (IVUS) is an imaging technique for evaluating vascular lesions and guiding vascular interventions. IVUS is particularly useful in percutaneous coronary intervention (PCI), where plaque assessment and procedural guidance can be difficult with coronary angiography alone. Coronary IVUS was first commercially available in the early 1990s. The technology has progressed steadily as expected, and sufficient clinical evidence has accumulated demonstrating the benefits of IVUS in PCI. Corl's U.S. Patent No. 8,864,674, "Circuit Architecture and Electrical Interface of Rotating Intravascular Ultrasound (IVUS) Devices," describes an example of a conventional IVUS system, which is incorporated herein by reference in its entirety. The additional imaging information provided by IVUS—such as the identification of plaque presence and extent, more accurate vessel sizing, external membrane elasticity (EEM) measurement, and evaluation of stent deployment—has the potential to improve the safety of stent placement, including optimizing vessel length and stent length, selecting stent landing sites, and identifying lesions at high risk of distal embolization during stent placement. Because IVUS has been demonstrated to have the ability to identify high-risk lesions, it can also facilitate the implementation of strategies to prevent future coronary events. Clinical research has shown that treatment decisions for individual patients are often complex and uncertain. Clinicians face on a daily basis difficult decisions regarding revascularization strategies (e.g., PCI or bypass surgery) and critical procedural issues regarding the likelihood of PCI success (e.g., identifying the lesion to treat, the length of the vessel to treat, optimal stent placement, and the risks of peripheral embolism and intraoperative myocardial infarction (MI)).

[0004] The vast majority of PCI cases in the United States are performed under angiography guidance only, but coronary angiography alone does not provide sufficient information to make such complex decisions. Importantly, in coronary angiography, images are formed by the contrast agent flowing through the arteries, inevitably imaging only the lumen of the vessel. Information about the vessel wall (e.g., plaque load) remains hidden. Dimensional accuracy is also limited due to low spatial resolution and numerous elements that cause image artifacts (e.g., vessels curving away from or towards the detector). Angiography is notorious for its high variability in the interpretation of parameters (e.g., degree of stenosis) used to quantitatively determine the feasibility of intervention. While angiography is an important tool for revealing the general presence of disease and roughly quantifying the degree of stenosis, it tends to underestimate the severity of atherosclerotic lesions, especially in the early stages of the disease, because vascular remodeling may maintain a normal lumen diameter even if a significant amount of plaque has formed on the vessel wall. Importantly, angiography has significant limitations in precisely measuring plaque structure and cannot provide data on plaque composition beyond a rough estimate of the degree of calcification. It is known that selecting and placing drug-eluting coronary stents (DES) based solely on angiographic information increases complications and leads to worse outcomes compared to IVUS-guided PCI.

[0005] IVUS-guided PCI has been shown to reduce stent complications (dissection, stent thrombosis, or end-restenosis), stent placement errors (stent ending at the lesion or being in an inappropriate location), and incomplete or improper stent deployment. As an example of comprehensive evidence, a meta-analysis covering 11 studies involving 19,619 patients demonstrated the superiority of direct coronary imaging over angiography guidance in facilitating PCI. Another major study showed that IVUS guidance changed clinician decisions in over 75% of cases, leading to the use of longer, more appropriately sized, and more effectively deployed stents. Repeated studies have shown that IVUS-guided PCI is associated with a relative risk reduction of over 50% in the composite endpoint of cardiac death, myocardial infarction, and stent thrombosis.

[0006] Atherosclerotic lesions characterized by a risk of rupture, so-called fragile plaques, are of particular importance to interventional cardiologists and are considered to be the cause of the majority of myocardial infarctions. The in vivo pathological analogue of fragile plaques is thin-capped fibrous atheroma (TCFA), which is mainly defined by the presence of a large necrotic nucleus and a thin (<65 μm) fibrous cap covering it. Therefore, to interpret whether fragile plaques are present, first, the IVUS system must have sufficient contrast and tissue boundary discrimination ability (e.g., blood, lumen boundary, external elastic membrane, thrombus, calcium, etc.) and be able to quantify the so-called plaque load (plaque size) so that it can be inferred that the plaque contains a necrotic nucleus, and second, sufficient resolution (e.g., <50 μm) is essential to visualize the thin-film region. Even the best IVUS systems currently on the market have only moderate image quality, which may limit their ability to identify fragile plaques. Similar image quality parameters related to plaque characterization for predicting a patient's future long-term risk are also urgently important for patient treatment guidance (accurate stent placement relative to plaque location, stent size, confirmation of successful stent deployment, or assessment of stent healing during follow-up catheter insertion).

[0007] As mentioned earlier, measuring the length of a lesion and related parameters, defined by its longitudinal position within a blood vessel, is crucial. Commercially available catheters fall into two basic types: those with a single transducer element and a rotatable / extendable core, and those with a multiplexed transducer array at the tip. Single-transducer rotatable core catheters rotate at high speed (typically 1800 RPM, or 30 frames / second) to acquire cross-sectional image frames, and generate volumetric images by retracting the core (so-called "pullback") while continuing to acquire frames. The pullback length is tracked within the motor drive by digitally converting the distance the core is pulled back relative to the sheath. Pullback information is transmitted to the console and image processing code via a wired connection between the motor drive and the console. Catheters with a multiplexed transducer array at the tip ("phased array" catheters) generate images by sequentially exciting and detecting transducers arranged in a circular pattern to create virtual rotations and corresponding frames. Volumetric images can be acquired by withdrawing the entire catheter from the blood vessel while continuing to acquire frames. Commercially available pullback devices are known to have significant accuracy and variability issues. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In one embodiment, the present disclosure relates to a pull-back distance sensor for an intravascular ultrasound system (IVUS). The sensor comprises a housing that defines a central opening configured to receive an IVUS catheter; a linear motion sensor positioned in the housing to detect the movement of the IVUS catheter as it moves through the central opening of the housing; and a wireless communication device positioned in the housing to communicate with the linear motion sensor to receive and wirelessly transmit a signal representing the movement of the IVUS catheter detected by the linear motion sensor.

[0009] In another embodiment, the disclosure relates to an intravascular ultrasound (IVUS) system comprising an IVUS patient interface module, an IVUS catheter extending from the patient interface module, an IVUS catheter introducer configured to receive the IVUS catheter, and a retraction distance detection unit positioned around the IVUS catheter and configured to generate a wireless signal indicating the retraction distance, the wireless signal being received by an IVUS system controller.

[0010] In yet another embodiment, the disclosure relates to a method for measuring the retraction distance in an intravascular ultrasound system (IVUS), the method comprising: arranging a retraction distance sensing unit housing around an IVUS catheter; retracting the IVUS catheter through the retraction distance sensing unit housing; detecting the distance the IVUS catheter travels through the retraction distance sensing unit housing using at least one linear motion sensor located in the retraction distance sensing unit housing; and wirelessly transmitting a signal indicating the distance traveled from the retraction distance sensing unit housing to an IVUS system controller. [Brief explanation of the drawing]

[0011] To illustrate the disclosures herein, the drawings illustrate aspects of one or more embodiments thereof. However, it should be understood that this disclosure is not limited to the exact arrangements and means shown in the drawings. [Figure 1] Figure 1 is a schematic diagram of the IVUS system according to this disclosure. [Figure 2] Figure 2 is a detailed view of a motion detection and transmission unit according to one embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram showing the operation of the motion detection and transmission unit according to the embodiment of this disclosure. [Figure 4] Figure 4 is a block diagram showing sensor communication according to an embodiment of the present disclosure. [Figure 5] Figure 5 is a schematic end view of an alternative embodiment of the detection unit according to this disclosure. [Modes for carrying out the invention]

[0012] This specification describes IVUS systems and methods including motion sensing and transmitting units configured to provide more accurate pullback measurements with greater precision and repeatability. Embodiments described herein and shown in accompanying figures include, but are not limited to, detecting the catheter pullback position with a small, disposable accessory that connects to a Luer lock connector on an introducer to continuously transmit information wirelessly to a motor drive unit. Here, the detection can be purely optical (reflecting light off the side of the catheter), a wheel with a slotted disc that contacts the catheter and has optical measuring capabilities, and / or scales printed on the side of the catheter to improve the accuracy of the sensor, and the sensor circuitry and digitization can be implemented using ASICs.

[0013] As shown in Figure 1, one embodiment of the system according to this disclosure includes a patient interface module (PIM) 10 which may include an IVUS motor drive unit and a communication device (not shown) such as a Wi-Fi, custom radio, or Bluetooth module. An IVUS catheter 12 extends from the patient interface module 10 through a sensing unit 14 and an vascular introducer 16, and in some embodiments, the sensing unit and the introducer may be connected by a conventional Luer lock fitting 18. The sensing unit 14 may have a fitting 19 at one end that can be connected to the Luer lock fitting 18. The catheter 12 extends from the distal end of an introduction needle 20. The vascular introducer 16 also includes a saline / wash line 22, as is well known in the art. The motion sensing unit 14 includes a motion sensing element 24 and a communication device 26, the motion sensing element 24 and the communication device 26 being located on or inside the housing of the sensing unit 14, respectively. The communication device 26 generates a wireless communication signal 28. The wireless communication signal 28 is transmitted to and received by the patient interface module 10, and may also be received by an IVUS console (not shown) equipped with system processing and image display functions for the operator, as is well known in the art.

[0014] The sensor element 24 detects the movement of the IVUS catheter as it passes through the sensor element by sliding motion, translational motion, etc., and can take various forms. In one embodiment, the sensor element 24 comprises a linear motion sensor combined with a 3-axis accelerometer, as shown in Figure 2. In another embodiment, the sensor element 24 may consist only of a linear motion sensor. Examples of linear motion sensors include mechanical sensors such as a wheel or an encoder-equipped wheel that rotates as the catheter moves longitudinally and contacts the catheter. The rotation of this wheel is detected by optical or other rotational position / detection means that can be configured by those skilled in the art. Other known linear motion / position detection devices, such as magnetic, inductive, capacitive, and eddy current sensors, may be used in combination with appropriate detection processing on the inside or outside surface of the catheter 12. Magnetic distance sensors convert magnetic energy into an electronic signal. Inductive linear sensors use electromagnetic induction to detect displacement. Capacitive sensors use dielectric materials to detect motion. Eddy currents can utilize any metal sheet and can detect the distance or change in the movement of the metal sheet. The linear motion sensor of the sensor element 24 is configured to detect the amount and direction of longitudinal movement of the catheter 12 via the detection unit 14, for example, during the retraction operation when creating an IVUS image. In an embodiment in which a 3-axis accelerometer is used for the sensor element 24, the longitudinal movement information is combined with 3-axis accelerometer information that detects the 3D movement of the detection unit 14, thereby detecting the longitudinal movement of the catheter during treatment and the potential displacement of the detection unit 14.

[0015] As an example, as shown in Figure 3, the linear sensor of the sensor element 24 may consist of an optical emitter / detector pair 30, such as an optical sensor in an optical computer pointing device (e.g., a mouse). In this embodiment, the sensor 30 can utilize the surface texture of the catheter as a guide for displacement calculation and provide micrometer-level displacement information. In some embodiments, as shown in Figure 3, a scale 32 may be provided on the catheter 12 to improve the sensitivity and accuracy of optical sensing and to be used for compensating for sudden slippage. A three-axis accelerometer incorporated into the sensor element 24, which is integrated with the optical sensor 30, further collects information indicating the three-dimensional movement of the sensing unit 14. To improve the accuracy of 3D motion sensing, this accelerometer may also include a three-axis gyroscope and a three-axis compass. Such a three-axis accelerometer may be configured as a MEMS device.

[0016] In some embodiments, it may be desirable to include an optional signal processor 34 within the motion detection unit 14, as shown in Figure 4. For example, the processor 34 may be configured to amplify the output of the sensor element 30 and digitize the signal when the sensor element 30 generates an analog output signal. For example, the processor 34 can be a Bluetooth® or Bluetooth® Low Energy (BLE) wireless microcontroller (MCU). In one embodiment, the processor 34 may be implemented as an ASIC by those skilled in the art based on the teachings herein. The processor 34 may integrate all sensor information within the motion detection unit 14, accurately extract the relative displacement of the catheter core and the introduction needle, and calculate the accurate displacement of the catheter core relative to the blood vessel. This information can be used to generate the retraction length, and in some embodiments, a separate IVUS motorized retraction device may not necessarily be provided. Alternatively, the processor 34 can be omitted, and the raw (unprocessed) linear displacement and 3D sensor information can be transmitted as is. In this configuration, the raw information is processed by a wireless system console (not shown) to generate the aforementioned catheter displacement information.

[0017] The detection unit 14 may be configured as an inexpensive, disposable add-on accessory that can be easily adapted to existing IVUS systems simply by attaching the Luer lock fitting 18 before insertion of the catheter 12. Using the detection unit 14 allows for much better control and more accurate understanding of the catheter position and retraction distance than is possible with current systems. The wireless communication signal 28 from the wireless communication device 26 is transmitted to and received by the interface unit / motor drive unit 10, and may also be received by a wireless system console (not shown). This console has system processing functions and an image display function for the operator. The detection unit 14 may be used in combination with an electric pullback unit (not shown), whether or not the wireless detection signal 28 is wirelessly transmitted to the electric pullback unit directly. In some embodiments, it may be desirable to operate the electric pullback unit under feedback control from the detection unit 14.

[0018] In yet another embodiment shown in Figure 5, the sensing unit 14 may have a longitudinal opening 36 that can be closed by a cover or door 38, thereby allowing the sensing unit to be attached to and detached from the catheter 12 without removing the catheter 12 from the introducer. Alternatively, the sensing unit 14 may be separated from the vascular introducer 16 and the Luer lock fitting 18 (or other relatively fixed structure), and instead may be held by the operator when withdrawing the catheter 12. In the case of a handheld sensing unit 14, the acceleration sensor of the sensor element 24 may be used to compensate for the influence of the operator's hand movements, thereby reducing the influence of the linear motion sensor on the withdrawal measurement.

[0019] The above is a detailed description of embodiments as specific examples of the present disclosure. In this specification and the appended claims, connecting expressions such as “at least one of X, Y, and Z” and “one or more of X, Y, and Z” shall be interpreted, unless otherwise stated or indicated, as meaning that each item in the connecting list may exist in any number, excluding all other items in the list. It also means that each item may exist in any number in any combination with any other item(s) in the connecting list. Each item may also exist in any number. Applying this general rule, the connecting phrases in the above examples (where the connecting list consists of X, Y, and Z) each include: one or more X; one or more Y; one or more Z; one or more X and one or more Z; and one or more X, one or more Y, and one or more Z.

[0020] Various modifications and additions can be made without departing from the spirit and scope of this disclosure. Each feature of the various embodiments described above may be combined, where appropriate, with features of other described embodiments to provide combinations of multiple features in new and relevant embodiments. Furthermore, although the foregoing describes several distinct embodiments, the content described herein is merely an example of the application of the principles of this disclosure. Moreover, even where certain methods are illustrated and / or described herein in a particular order, the order can be significantly altered to achieve the content of this disclosure within the scope of the art. Therefore, the descriptions herein should be understood as illustrative only and not to otherwise limit the scope of this disclosure.

[0021] Exemplary embodiments are disclosed above, along with the accompanying drawings. Those skilled in the art will understand that various modifications, omissions, and additions are possible with respect to the content specifically disclosed herein without departing from its spirit and scope.

Claims

1. A housing section defining a central opening configured to slidably receive an intravascular ultrasound system catheter, A linear motion sensor is disposed within the housing and configured to detect the movement of the intravascular ultrasound system catheter when moved through the central opening, A wireless communication device disposed in the housing and communicating with the linear motion sensor, the wireless communication device receiving and wirelessly transmitting a signal representing the movement of the intravascular ultrasound system catheter detected by the linear motion sensor, A pull-back distance sensor for intravascular ultrasound (IVUS) systems equipped with [specific feature].

2. The housing further comprises an acceleration sensor located in the housing that communicates with the wireless communication device, The acceleration sensor generates three-dimensional position information relative to the housing, which is wirelessly transmitted by the wireless communication device. The pull-back distance sensor according to claim 1.

3. The housing portion surrounding the central opening is further provided with a connector fitting that enables connection to a fitting or hub of the IVUS system introducer. The pull-back distance sensor according to claim 1 or 2.

4. The housing portion further defines a longitudinal opening configured to allow the housing portion to be placed on an intravascular ultrasound system catheter, and further comprises a closing portion for the longitudinal opening. The pull-back distance sensor according to claim 1 or 2.

5. The aforementioned storage unit is configured as a handheld storage unit. The pull-back distance sensor according to claim 4.

6. The linear motion sensor comprises a wheel configured to contact the intravascular ultrasound system catheter when retracted through the housing, The pull-back distance sensor according to any one of claims 1 to 5.

7. The linear motion sensor comprises an optical sensor configured to detect the movement of the surface of the intravascular ultrasound system catheter as it is retracted through the housing. The pull-back distance sensor according to any one of claims 1 to 5.

8. The aforementioned light sensor comprises a pair of light-emitting elements and light-receiving elements. A pull-back distance sensor according to claim 7,

9. Stepped markings are arranged on the surface of the intravascular ultrasound system catheter. The pull-back distance sensor according to claim 7 or 8.

10. The linear motion sensor comprises a magnetic linear position sensor, and the intravascular ultrasound system catheter includes one or more magnetic elements along its entire length. The pull-back distance sensor according to any one of claims 1 to 5.

11. The linear motion sensor comprises an inductive linear position sensor, and the intravascular ultrasound system catheter includes a magnetic core or magnetic element along its entire length. The pull-back distance sensor according to any one of claims 1 to 5.

12. The linear motion sensor comprises a capacitive linear position sensor, and the intravascular ultrasound system catheter contains a dielectric material such as ceramic or glass along its entire length. The pull-back distance sensor according to any one of claims 1 to 5.

13. The linear motion sensor comprises an eddy current linear position sensor, and the intravascular ultrasound system catheter includes a conductive metal strip or strip element along its entire length. The pull-back distance sensor according to any one of claims 1 to 5.

14. The housing is further equipped with a signal processor capable of communicating with at least the linear motion sensor and the wireless communication device, The signal processor is configured to determine the pull-back distance from the input of the intravascular ultrasound system catheter base from the sensor. A pull-back distance sensor according to any of the preceding claims.

15. The signal processor is configured to receive an acceleration detection signal from the acceleration sensor and to determine the three-dimensional movement of the housing unit. The pull-back distance sensor according to claim 14.

16. IVUS patient interface module, An IVUS catheter extending from the aforementioned IVUS patient interface module, An IVUS catheter introduction device configured to receive the aforementioned IVUS catheter, A retraction distance detection unit is positioned around the IVUS catheter and configured to generate a wireless signal indicating the retraction distance, wherein the wireless signal is received by the IVUS system controller. An intravascular ultrasound (IVUS) system equipped with [specific features / features].

17. The IVUS system controller that receives the wireless signal comprises the IVUS patient interface module. The intravascular ultrasound system (IVUS) according to claim 16.

18. The IVUS system controller further comprises an IVUS console, which additionally or alternatively receives the radio signal. The intravascular ultrasound system (IVUS) according to claim 17.

19. The aforementioned pull-back distance detection unit, A housing portion defining a central opening configured to slidably receive the IVUS catheter, A linear motion sensor is provided in the housing and configured to detect the movement of the IVUS catheter when it moves through the central opening, A wireless communication device is disposed in the housing and communicates with the linear motion sensor, receiving and wirelessly transmitting a signal representing the movement of the IVUS catheter detected by the linear motion sensor. Equipped with, An intravascular ultrasound system (IVUS) according to any one of claims 16 to 18.

20. The pull-back distance detection unit further comprises an acceleration sensor located in the housing unit that communicates with the wireless communication device, The acceleration sensor generates three-dimensional position information relative to the housing, which is wirelessly transmitted by the wireless communication device. The intravascular ultrasound system (IVUS) according to claim 19.

21. The device further comprises a connector fitting positioned at one end of the housing surrounding the central opening, which allows for direct or indirect connection to the IVUS catheter introduction device. The intravascular ultrasound system (IVUS) according to claim 19 or 20.

22. The housing portion further defines a longitudinal opening configured to allow the housing portion to be placed on the IVUS catheter, and further comprises a closing portion for the longitudinal opening. The intravascular ultrasound system (IVUS) according to claim 19 or 20.

23. The aforementioned pull-back distance detection unit is configured as a handheld unit. The intravascular ultrasound system (IVUS) according to claim 22.

24. The linear motion sensor comprises a wheel configured to contact the IVUS catheter when it is retracted through the housing. An intravascular ultrasound system (IVUS) according to any one of claims 19 to 23.

25. The linear motion sensor comprises an optical sensor configured to detect the movement of the surface of the IVUS catheter as it is retracted through the housing. An intravascular ultrasound system (IVUS) according to any one of claims 19 to 23.

26. The process involves arranging the retraction distance detection unit housing around the IVUS catheter, The process of pulling back the IVUS catheter and pulling it through the distance detection unit, A step of detecting the distance traveled by the IVUS catheter through the retraction distance detection unit housing using at least one linear motion sensor located in the distance detection unit housing, The process includes wirelessly transmitting a signal indicating the distance traveled from the pull-back distance detection unit housing to the IVUS system controller, A method for measuring the retraction distance in an intravascular ultrasound system (IVUS), including [specific component].

27. The IVUS system controller comprises either or both an IVUS console and an IVUS patient interface module. The method according to claim 26.

28. The method further includes attaching the withdrawal distance detection unit housing directly or indirectly to the IVUS catheter introduction device in order to position the IVUS catheter within the patient's blood vessels. The method according to claim 26 or 27.

29. This further includes, at least during the pulling and detecting steps, holding the pull-back distance detection unit housing in the hand of the system operator, The method according to claim 26 or 27.

30. The further includes processing signals from at least a linear motion sensor within the retraction distance detection unit housing to determine the retraction distance, and wirelessly transmitting the determined retraction distance. The method according to any one of claims 26 to 29.

31. The method further includes processing signals from a three-axis accelerometer included in the linear motion sensor to determine the three-dimensional movement of the pull-back distance detection unit housing, and arbitrarily correcting the determined pull-back distance based on the determined three-dimensional movement. The method according to claim 30.

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