Integrated steerable sheath ultrasound imaging system and method - Patent Application 20070122997

Abstract

An ultrasound imaging system is disclosed. The ultrasound imaging system includes an intracardiac echocardiogram (ICE) catheter and a transducer ring. A steerable sheath is integrated with a built-in forward-looking transducer and a transducer ring disposed at the distal end of the sheath. The transducer ring includes a MEMS-based pMUT array disposed on a substrate. The catheter shaft has a lumen therein that allows passage of a puncture needle and an electronic flex cable, and is in communication with at least one signal trace. The electronic flex cable is configured to communicate with the pMUT array via the at least one signal trace, transmit and receive ultrasound beams, receive signals based on the transmission and reception, and construct an image of the heart or a portion thereof based on the signals.

Description

[Technical Field]

[0001] The present disclosure relates generally to the field of ultrasound imaging systems. More specifically, some embodiments relate to a forward-looking intracardiac echo (ICE) ultrasound catheter with an integrated steerable sheath or a forward-looking intracardiac echo (ICE) ultrasound catheter with a lumen that allows passage of a transseptal needle. The disclosed device improves the accuracy of transseptal puncture and also facilitates delivery of the device to the left atrium. [Background technology]

[0002] Atrial fibrillation is the most common type of cardiac arrhythmia, currently affecting approximately 2.2 million adults in the United States alone. Minimally invasive, catheter-based electrophysiological (EP) interventions provide useful information about the electrical behavior of the myocardium, information that can aid in better diagnosis and treatment of arrhythmias. Catheter-based radiofrequency (RF) ablation is the most common ablation therapy and is often used to ablate a small portion of the dysfunctional tissue responsible for the arrhythmia.

[0003] The use of catheter-based structural and electrophysiology procedures has expanded in recent years to more complex cases, making accurate understanding of the variable individual cardiac anatomy key to achieving optimal outcomes. Intracardiac echocardiography (ICE) is a unique imaging modality that allows high-resolution, real-time visualization of cardiac structures, continuous monitoring of catheter position within the heart, and early recognition of procedural complications such as pericardial effusion and clot formation. Furthermore, the ICE imaging technique offers additional advantages, including excellent patient tolerance, reduced fluoroscopy time, and no need for general anesthesia or a second operator.

[0004] Since its introduction, transseptal catheterization has been used to access the left atrium for the treatment of several conditions and is generally considered safe and effective. In recent years, the number of different transcatheter interventions requiring this approach has increased. The accuracy of the puncture site is important not only to reduce the risk of complications but also to facilitate device delivery to the desired left atrial site and, therefore, the overall procedure. To facilitate transseptal catheterization, intracardiac echocardiography (ICE) and transesophageal echocardiography (TEE) are widely used, contributing to procedural monitoring and improving the safety and accuracy of the puncture. ICE imaging has now largely replaced transesophageal echocardiography as the ideal imaging technique for guiding certain procedures, such as atrial septal defect closure and catheter ablation of cardiac arrhythmias, and is also playing an emerging role in other procedures, such as mitral valvuloplasty, transcatheter aortic valve replacement, and left atrial appendage closure.

[0005] In electrophysiology procedures, intracardiac echocardiography (ICE) imaging allows for the integration of real-time images with electroanatomical maps. ICE imaging plays an important role in the evaluation of arrhythmogenic substrates and is particularly useful for mapping structures not visualized by fluoroscopy, such as the interatrial or interventricular septum, papillary muscles, and intracardiac muscle ridges. For these reasons, ICE has largely replaced transesophageal echocardiography (TEE). Furthermore, the introduction of ICE represents a major advancement in cardiac imaging and has become an essential component in various types of percutaneous interventions and electrophysiology procedures, potentially resulting in improved outcomes and reduced risk. ICE allows for real-time assessment of cardiac anatomy during interventions and guides catheter manipulation relative to various anatomical structures.

[0006] In contrast to transesophageal echocardiography (TEE), intracardiac echocardiography (ICE) is performed by the actual operator of the interventional procedure under sedation without the need for endotracheal intubation, thereby eliminating the risk of esophageal injury and other postanesthetic complications. In addition, ICE reduces fluoroscopic exposure to both the patient and the surgeon, potentially improving outcomes, shortening procedure time, and facilitating early recognition of complications such as blood clot formation and pericardial effusion.

[0007] Therefore, there is a need for an improved ultrasound imaging system using a forward-looking ultrasound ICE catheter, which involves a new concept to improve the accuracy of transcardial septal puncture. Summary of the Invention

[0008] By way of introduction, the preferred embodiment described below includes an easy-to-use ultrasound imaging system. The ultrasound imaging system includes an intracardiac echocardiogram (ICE) catheter having a longitudinal axis, a proximal end, and a distal end. The ultrasound imaging system includes a transducer ring disposed at the distal end of the ICE catheter. The transducer ring includes a substrate and a microelectromechanical (MEMS)-based piezoelectric micromachined ultrasound transducer (pMUT) array disposed thereon, the MEMS-based pMUT array being a forward-facing assembly including a plurality of pMUT array elements mounted on the substrate in a circular or linear configuration. The ultrasound imaging system further includes a catheter shaft connected to one end of a handle assembly and coupled to the MEMS-based pMUT array at the other end. The catheter shaft defines an internal lumen that allows passage of an insertion needle and an electronic flex cable toward the proximal end of the ICE catheter. The electronics flex cable is in communication with the at least one signal trace and is in electrical communication with the MEMS-based pMUT array such that a single array element simultaneously transmits and receives multiple fundamental mode vibrations, and transmits and receives an ultrasound beam having a bandwidth that includes the predetermined fundamental mode vibration with each pMUT array element with respect to the heart via the at least one signal trace, the electronics flex cable being configured to receive at least one signal from the MEMS-based pMUT array based on the at least one transmission and reception of the ultrasound beam, and to construct an image of the heart or a portion thereof based on the signal. The ultrasound imaging system further comprises a steerable sheath, the steerable sheath being integrated with an integrated forward-looking transducer and integrated with a transducer ring disposed at a distal end of the steerable sheath or a distal end of the ICE catheter.

[0009] The ICE catheter further includes a steering control unit disposed within the handle assembly for bending the distal end of the ICE catheter and aligning the face of the MEMS-based pMUT array toward an internal field of view, including the fossa ovalis. The distal end of the ICE catheter is coated with a material that provides electrical insulation and transmission of ultrasound signals. The ICE catheter accommodates a mechanically flexible sheath that allows insertion into the heart and includes a marker band for identifying its location on X-ray images. The ICE catheter is further coupled to an imaging device using a custom dongle. The custom dongle is coupled to the handle assembly using an interposer and a flat circuit board. The custom dongle is configured to communicate ultrasound transmit pulses and ultrasound receive waveforms between the ICE catheter and the imaging device. The catheter shaft further houses multiple individual electronic flex cables connected between the handle assembly and the MEMS-based pMUT array. The ultrasound beam has a bandwidth that includes predetermined fundamental vibration modes of each of the multiple pMUT array elements, and a single array element simultaneously transmits and receives multiple fundamental vibration modes.

[0010] In one embodiment, an intracardiac echocardiogram (ICE) catheter is disclosed. The ICE catheter comprises a body having a longitudinal axis and a distal end. The ICE catheter further comprises a transducer ring disposed at the distal end of the ICE catheter. The transducer ring comprises a substrate and a microelectromechanical (MEMS)-based piezoelectric micromachined ultrasound transducer (pMUT) array disposed thereon. The MEMS-based pMUT array is a forward-facing assembly. The MEMS-based pMUT array comprises a plurality of transducer array elements disposed on the substrate. The ICE catheter further comprises a steerable sheath integrated with an integrated forward-looking transducer and the transducer ring disposed at the distal end of the ICE catheter. Each of the plurality of transducer array elements comprises individual elements of a plurality of diameters. The MEMS-based pMUT array is further connected in series between at least one signal trace and a common ground. Each of the plurality of transducer array elements includes a plurality of transducers, including a first group of two or more transducers in a first transducer array element and a second group of two or more transducers in the first transducer array element. Each of the plurality of transducer array elements is connected in parallel. At least one first electrode is connected between at least one piezoelectric layer and a signal conductor, and at least one second electrode is connected between at least one piezoelectric layer and a ground conductor.

[0011] In one embodiment, an intracardiac echocardiogram (ICE) imaging system is disclosed. The ICE imaging system includes an ICE catheter having a longitudinal axis, a proximal end, and a distal end. A microelectromechanical systems (MEMS)-based piezoelectric micromachined ultrasound transducer (pMUT) array is disposed within the distal end of the ICE catheter. The MEMS-based pMUT array is a forward-facing assembly including a plurality of MEMS-based pMUT array elements disposed on a substrate. The MEMS-based pMUT array also includes pMUT cells with multiple diameters to achieve a bandwidth greater than 55%. The ICE imaging system further includes a steerable sheath integrated with an integrated forward-looking transducer and a transducer ring disposed at the distal end of the ICE catheter. The ICE imaging system further includes a catheter shaft connected to one end of a handle assembly and coupled to the MEMS-based pMUT array at the other end. The catheter shaft has an internal lumen that allows a puncture needle and an electronic flex cable to pass through toward the proximal end of the ICE catheter. The electronic flex cable is in communication with at least one signal trace and is configured to conduct with each of the plurality of MEMS-based pMUT array elements via the at least one signal trace, transmit and receive ultrasound beams relative to the heart, receive at least one signal from the plurality of MEMS-based pMUT array elements based on the at least one transmission and reception of the ultrasound beam, and construct at least one image of the heart or a portion thereof based on the signal.

[0012] Other features and aspects of the present disclosure will become apparent from the following description and accompanying drawings. The accompanying drawings illustrate systems, methods, and embodiments according to various aspects of the present disclosure. Those skilled in the art will appreciate that the boundaries of elements shown in the drawings (e.g., frames, frames, other shapes, etc.) are illustrative of various boundaries representative of the present invention. In some instances, a single element may be designed as multiple elements. Also, multiple elements may be designed as a single element. In other instances, what is shown as an internal component of one element may be implemented as an external component in other instances, and vice versa. Additionally, elements are not necessarily drawn to scale. A non-limiting and non-exhaustive description of the present disclosure is described with reference to the following drawings. The components shown in the figures are not necessarily drawn to scale, rather emphasizing the principles illustrated.

[0013] Various embodiments will now be described with reference to the accompanying drawings, which are provided for illustrative purposes without limiting the scope of the present disclosure in any way, and in which like reference numerals indicate like or equivalent elements. [Brief explanation of the drawings]

[0014] [Figure 1A] FIG. 1 is a schematic diagram of a forward-looking piezoelectric micromachined ultrasonic transducer (pMUT) circular array assembly according to an embodiment of the present disclosure. [Figure 1B] FIG. 1 is a schematic diagram of a forward-looking pMUT linear array assembly according to an embodiment of the present disclosure. [Figure 2] 1 is a cross-sectional view of a distal end of an ICE catheter having multiple transducer array elements according to an embodiment of the present disclosure. [Figure 3] 1 is a schematic diagram of an ultrasound imaging system according to an embodiment of the present disclosure. [Figure 4A] FIG. 1 illustrates a conventional imaging system for acquiring two-dimensional image information. [Figure 4B] FIG. 1 illustrates a conventional imaging system for acquiring two-dimensional image information. [Figure 5] FIG. 2 is a perspective view of the distal end of an ICE catheter according to one embodiment of the present disclosure. [Figure 6] FIG. 1 is a cross-sectional view of a heart for placement of a forward-looking ICE catheter prior to transcardial septal puncture according to an exemplary embodiment of the present disclosure. [Figure 7] FIG. 10 is another cross-sectional view of the heart for placement of a forward-looking ICE catheter during transcardiac septal puncture, according to an exemplary embodiment of the present disclosure. [Figure 8] 1 is a schematic diagram of an ICE catheter according to one embodiment of the present disclosure. [Figure 9] FIG. 1 illustrates multi-channel electronic communication between an ultrasound imaging device and a MEMS-based pMUT array according to an embodiment of the present disclosure. MODE FOR CARRYING OUT THE INVENTION

[0015] The components of the embodiments of the present disclosure may be arranged or designed in a variety of configurations, as generally described and illustrated in the drawings set forth herein. Thus, the following more detailed description of various embodiments that are illustrated in the drawings is not intended to limit the scope of the disclosure, but is merely illustrative of various embodiments. While various aspects of the embodiments are illustrated in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0016] Some embodiments of the present disclosure are described in detail below, examples illustrating all of their features. The terms "comprising," "having," "containing," and "including," as well as other forms thereof, are intended to be synonymous and open-ended, i.e., an item or group of items following any of these terms does not imply an exhaustive list of those items, nor is it intended to be limited to only the listed items.

[0017] It should also be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include the plural forms unless the context otherwise dictates. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the preferred systems and methods are described below. The terms "proximal end" and "distal end" are opposite terms. For example, the distal end of a device or component refers to the end of the component that is farthest from the operator during normal use, and is opposite the proximal end, i.e., the end closest to the operator during normal use.

[0018] Embodiments of the present disclosure are described in more detail below with reference to the accompanying drawings, in which like reference numerals designate like or corresponding elements throughout the drawings and in which exemplary embodiments are shown. However, the embodiments of the present disclosure may be embodied in other forms and should not be construed as limited to the embodiments set forth herein. The example shown is not limiting and is merely one example among other possible examples.

[0019] Referring to FIG. 1A, a schematic diagram of a forward-looking piezoelectric micromachined ultrasonic transducer (pMUT) circular array assembly 100 is disclosed in accordance with one embodiment of the present disclosure.

[0020] The pMUT circular array assembly 100 may be coupled to an intracardiac echocardiogram (ICE) catheter (not shown). The ICE catheter has a longitudinal axis, a proximal end, and a distal end. The pMUT circular array assembly 100 may be positioned on the distal end of the ICE catheter. The pMUT circular array assembly 100 may include a circular transducer ring 102. The circular transducer ring 102 may further include a substrate 104 and a plurality of microelectromechanical (MEMS)-based pMUT array elements 106 mounted in a circular configuration on and overlying the substrate 104. The MEMS-based pMUT array elements 106 are forward-facing assemblies. The substrate 104 may further include a first plurality of connectors 108 arranged along the periphery of the circular transducer ring 102. The first plurality of connectors 108 may be configured to couple the MEMS-based pMUT array elements 106 in a plurality of connections. Here, the multiple connections may be series and / or parallel connections between the MEMS-based pMUT array elements 106 and the substrate 104. Furthermore, the first multiple connections 108 are disposed along the outer periphery of the circular transducer ring 102. Furthermore, the MEMS-based pMUT array element connections 108 are routed within a lumen 110 via an electronic flex cable 112. The circular transducer ring 102 may be disposed at the distal end of an ICE catheter. Furthermore, the circular transducer ring 102 may be configured to transmit an ultrasound beam forward of the distal end of the ICE catheter. The ICE catheter is described in connection with FIG. 8.

[0021] Referring to FIG. 1B, a schematic diagram of a forward-looking pMUT linear array assembly 114 is disclosed in accordance with one embodiment of the present disclosure. The pMUT linear array assembly 114 may include a linear transducer ring 116. The linear transducer ring 116 may include MEMS-based pMUT array elements 118 mounted in a linear configuration overlying the substrate 104. The MEMS-based pMUT array elements 118 may correspond to individual linear transducers. Additionally, the linear transducer ring 116 may include a second plurality of connections 120. Furthermore, the MEMS-based pMUT array elements 118 are routed within the lumen 110 via the electronic flex cable 112. Furthermore, the linear transducer ring 116 is positioned at the distal end of the ICE catheter and transmits an ultrasound beam forward of the distal end of the ICE catheter.

[0022] FIG. 2 shows a cross-sectional view of the distal end of an ICE catheter with a MEMS-based pMUT array 202 having multiple transducer array elements 204, according to one embodiment of the present disclosure.

[0023] The distal end of the ICE catheter may include a MEMS-based pMUT array 202 having multiple transducer array elements 204. Each of the multiple transducer array elements 204 may have multiple individual transducer cells 206 arranged to provide broadband coverage for each focused beam. In one embodiment, the MEMS-based pMUT array 202 may be comprised of a pMUT array including individual elements with different diameters. In another embodiment, to achieve a wider bandwidth in the pMUT array, multiple diameter pMUT cells may be integrated into a single element. Furthermore, by arranging preformed pMUTs with different diameters, a wider bandwidth may be achieved through complex interactions between the individual pMUT elements. In one embodiment, the multiple diameter pMUT cells may achieve a bandwidth of over 55%. For example, there may be five different dome diameters in a three-element array, each with a different size, such as 300 μm.

[0024] Furthermore, the MEMS-based pMUT array 202 may correspond to a pMUT, and the plurality of transducer array elements 204 may correspond to a plurality of pMUT elements. In one embodiment, the plurality of pMUT elements may be oriented to transmit and receive ultrasound beams having a bandwidth that includes a predetermined fundamental mode vibration of each pMUT element. This allows a single pMUT element to simultaneously transmit and receive multiple fundamental mode vibrations. In one embodiment, an electronic flex cable within the catheter shaft of the ICE catheter receives at least one signal from the plurality of pMUT elements. Here, the at least one signal may correspond to at least one ultrasound beam. The at least one signal may be transmitted to an ultrasound imaging device 302 for subsequent processing in an image processor, as shown in FIG. 3 . The image processor may construct at least one image of the heart. Note that the plurality of pMUT elements may be used to generate individual focused beams.

[0025] In an alternative embodiment, the MEMS-based pMUT array 202 may include a cladding portion that exhibits a flat cross-sectional shape. This feature of the MEMS-based pMUT array 202 is common in ultrasound imaging catheters. Due to the severe spatial constraints imposed by the small diameter of intracardiac catheters, the MEMS-based pMUT array 202 is typically limited to a circular phased array composed of multiple individual transducer elements, such as 64 transducers or elements. These transducers have flat surfaces from which sound waves are emitted and from which reflected sound is received. As is well known to those skilled in the art, the individual transducer elements are pulsed by an ultrasound control system, and the emitted sound waves are constructively combined to form a main beam. By varying the timing at which each transducer element is pulsed, the ultrasound imaging system 300 shown in FIG. 3 can reconstruct the individual beams as focused images to acquire a two-dimensional image. As a result, the MEMS-based pMUT array 202 emits ultrasound waves along a plane perpendicular to the surface of the transducer array. Thus, the MEMS-based pMUT array 202 radiates acoustic waves along a plane perpendicular to the assembly.

[0026] Referring to FIG. 3, a schematic diagram of an ultrasound imaging system 300 is disclosed in accordance with an embodiment of the present disclosure. The ultrasound imaging system 300 may be implemented for electrophysiology (EP) procedures. The ultrasound imaging system 300 may be used for diagnosis and / or treatment in combination with other imaging modalities, such as x-ray, fluoroscopy, magnetic resonance, computed tomography, or optical imaging. Both imaging modalities may scan a patient to generate images to assist a physician. Data from different imaging modalities may be aligned by identifying markers in the images of the other imaging modality that have a known spatial relationship to the ultrasound scan. In another embodiment, the ultrasound imaging system 300 may use a catheter without markers and / or a catheter that does not use the other imaging modality. In one embodiment, the ultrasound imaging system 300 may utilize a microelectromechanical (MEMS) transducer array, defined as a piezoelectric micromachined ultrasound transducer (pMUT), or other types of MEMS transducers interconnected using a matched flexible circuit. In one embodiment, the ultrasound imaging system 300 may correspond to an intracardiac echocardiogram (ICE) imaging system. In one embodiment, the ultrasound imaging system 300 can accommodate an intravascular MEMS ultrasound transducer that utilizes high-density flexible circuitry for all transmission and electrical interconnections. In one embodiment, the ultrasound imaging system 300 can be used to treat patients with cystic fibrosis (CF). It is noted that the use of high-density flexible circuitry allows for highly repeatable and stable transmitted and reflected signals. Furthermore, transmission lines in the high-density flexible circuitry can transmit electrical energy from one end of the ultrasound imaging system 300 to the other distal end.

[0027] The ultrasound imaging system 300 may include an imaging device 302 coupled to an ICE catheter 304 via a communication channel 306. In some embodiments, the communication channel 306 may be a cable and bus connection or a custom dongle with multiple connections. Hereinafter, the communication channel 306 will be referred to as the custom dongle 306. In some embodiments, the ICE catheter 304 may correspond to an ultrasound catheter.

[0028] The ICE catheter 304 may be positioned within a chamber of the patient's heart, and the imaging device 302 may receive at least one signal from the ICE catheter 304. The at least one signal may be communicated from the ICE catheter 304 to the imaging device 302 via a custom dongle 306. The imaging device 302 may further include an image processor 308, a transmit beamformer 310, a receive beamformer 312, and a display 314.

[0029] The image processor 308 may be configured to generate two-dimensional (2D) images based on data received from the ICE catheter 304. In some embodiments, the image processor 308 may be configured to receive focused signals from the receive beamformer 312. The image processor 308 may render the data to construct an image or a continuum of images. In some embodiments, the image may be a three-dimensional (3D) representation, such as a two-dimensional image rendered from a view direction selected by a user or a processor. In some embodiments, the image processor 308 may be a detector, filter, processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), digital signal processor (DSP), control processor, scan converter, three-dimensional image processor, graphics processing unit (GPU), analog circuitry, digital circuitry, or a combination thereof. The image processor 308 may receive the beamformed data and generate an image for display on the display 314. Note that the generated image is associated with a two-dimensional (2D) scan. Alternatively, the generated image may be a three-dimensional (3D) representation.

[0030] The image processor 308 may be programmed to perform hardware-accelerated two-dimensional reconstruction. The image processor 308 may store processed data of at least one signal and a continuum of images in memory. In some embodiments, the memory may be a non-transitory computer-readable storage medium. Instructions for implementing the processes, methods, and / or techniques disclosed herein may be provided on a computer-readable storage medium or memory, such as a cache, buffer, RAM, removable media, a hard drive, or other computer-readable storage medium. Non-transitory computer-readable storage media include various types of volatile and non-volatile storage media. The functions, operations, or tasks illustrated in the figures or described herein are performed in response to one or more instruction sets stored on a computer-readable storage medium. These functions, operations, or tasks are independent of the particular type of instruction set, storage medium, processor, or processing strategy and may be performed by software, hardware, integrated circuits, firmware, microcode, or any combination thereof, alone or in combination.

[0031] The transmit beamformer 310 may be configured to transmit electrical signals or impulses in the form of at least one signal toward the ICE catheter 304. The receive beamformer 312 may be configured to receive the electrical signals or impulses from the ICE catheter 304. In an embodiment, the transmit beamformer 310 and the receive beamformer 312 may use transmit beamforming techniques to focus energy at the receive side to improve the signal-to-noise ratio (SNR) of the at least one signal, which may then be facilitated for transmission to the image processor 308.

[0032] The display 314 may be configured to display an image or a series of images during or after the data is rendered by the image processor 308. The images may be three-dimensional (3D) representations, such as two-dimensional images rendered from a viewing direction selected by a user or a processor. Alternatively, the images may be one or more two-dimensional images representing a plane within a volume. In some embodiments, the display 314 may be part of the imaging device 302 or may be remote, such as a network-connected display. In some embodiments, the display 314 may be a cathode ray tube (CRT), liquid crystal display (LCD), projector, plasma display, or other display device now known or later developed.

[0033] 4A and 4B, a prior art imaging system 400 is disclosed. The imaging system 400 may be used for diagnosis and / or treatment in combination with other imaging techniques, such as X-ray, fluoroscopy, magnetic resonance, computed tomography, or optical systems. It is noted that the imaging technique scans a patient to generate an image to assist a physician. Furthermore, the imaging system 400 provides an ultrasound transmit pulse 402 and an ultrasound receive path 404, which may be connected to an ultrasound transducer (not shown). The ultrasound transmit pulse 402 may transmit an ultrasound signal from the imaging system 400 toward a target, such as a patient's heart. Furthermore, the ultrasound receive path 404 may generate a waveform based on at least one ultrasound signal. The imaging system 400 may then convert the received ultrasound signal or ultrasound information into a two-dimensional (2D) image of the target or a portion thereof.

[0034] Referring to FIG. 5, a perspective view of the distal end of an ICE catheter 304 is disclosed in accordance with one embodiment of the present disclosure. The ICE catheter 304 may include a catheter shaft 502 defining a lumen 110 therein. The lumen 110 may allow a needle (not shown) and a flex cable (not shown) to pass through. It is noted that the flex cable transmits ultrasound signals between the transducer array 504 and the dongle 306. The transducer array 504 may include MEMS-based pMUT array elements 106 arranged along the periphery of the circular transducer ring 102.

[0035] Referring to FIG. 6, there is shown a cross-sectional view of a heart 600 with a forward-looking ICE catheter 304 positioned prior to transseptal puncture, according to an exemplary embodiment of the present disclosure. The ICE catheter 304 may be positioned within the right atrium 602 of the heart 600. Further, the ICE catheter 304 may include a distal tip 604. The distal tip 604 of the ICE catheter 304 may be inserted into the right atrium 602 via the inferior vena cava (not shown). The movement of the distal tip 604 of the ICE catheter 304 within the right atrium 602 may be controlled by a steering control unit (not shown) of the ICE catheter 304 so as to be positioned to image the fossa ovalis 606.

[0036] Referring to FIG. 7, another cross-sectional view of a heart 600 is disclosed illustrating the placement of a forward-looking ICE catheter 304 during a transseptal puncture, in accordance with an exemplary embodiment of the present disclosure.

[0037] The distal tip 604 of the ICE catheter 304 may be positioned within the right atrium 602 of the heart 600. The steering control unit may be actuated to advance the distal tip 604 of the ICE catheter 304 to puncture the fossa ovalis 606.

[0038] Referring to FIG. 8, a schematic diagram of an ICE catheter 304 according to one embodiment of the present disclosure is disclosed. The ICE catheter 304 may include a flexible sheath 802 with marker bands 804 that allow for location on x-ray images (not shown). The flexible sheath 802 may have marker bands 804 at a distal end 806 of the ICE catheter 304 to allow for insertion into a chamber of the patient's heart 600, thereby allowing for location on x-ray images. It is noted that the distal end 806 of the ICE catheter 304 may be coated with a material that provides electrical insulation and transmission of the ultrasound signals generated by the ICE catheter 304. In one embodiment, the flexible sheath 802 is inserted into a chamber of the heart 600, and the marker bands 804 may allow for location on x-ray images. It is noted that the image processor 308 of the ultrasound imaging device 302 may generate real-time 2D images of the heart using the location on x-ray images. In one embodiment, the flexible sheath 802 may correspond to the catheter shaft 304, allowing for insertion into the heart, thereby achieving location on x-ray images. In one embodiment, ICE catheter 304 is provided with an electrically insulating coating to transmit ultrasound signals generated by ICE catheter 304, and patients with cystic fibrosis (CF) can be treated with ICE catheter 304. In one embodiment, flexible sheath 802 corresponds to a steerable sheath with an integrated forward-looking transducer, and transducer ring 102 can be disposed at the distal end 806 of steerable sheath or ICE catheter 304. It is noted that a forward-looking ICE catheter 304 integrated into a steerable sheath or a forward-looking ICE catheter with lumen 110 can facilitate the passage of a puncture needle or atrial septal puncture needle. A steerable sheath can facilitate maximum manipulation of ICE catheter 304 to allow deflection of the puncture needle. It is further noted that a steerable sheath can facilitate access to difficult-to-reach regions within the heart.

[0039] Additionally, the ICE catheter 304 may include an electrically insulated shaft 808 toward the distal end 806 of the ICE catheter 304. The electrically insulated shaft 808 may use a copolymer material up to the distal end 806 of the ICE catheter 304. In one embodiment, the electrically insulated shaft 808 may be coated with a PEBAX® material. The imaging window may allow the ultrasound beam to pass to and from the MEMS-based pMUT array 202. Additionally, the distal end 806 of the ICE catheter 304 may be coated with an electrically insulated material to provide isolation and transmission of the ultrasound signal.

[0040] Furthermore, the MEMS-based pMUT array 202 may be disposed within the distal end 806 of the ICE catheter 304. The MEMS-based pMUT array 202 may include a plurality of transducer array elements 204 disposed on the substrate 104. Furthermore, the MEMS-based pMUT array 202 may be connected in series between at least one signal trace and a common ground. Furthermore, each of the plurality of transducer array elements 204 may include a plurality of transducers. The plurality of transducers may include a first group of two or more transducers within the first transducer array element and a second group of two or more transducers within the first transducer array element. Furthermore, each of the plurality of transducer array elements 204 may be connected in parallel. Furthermore, it is noted that each transducer array element may include at least one piezoelectric layer disposed on the substrate 104. The at least one piezoelectric layer may constitute a pMUT array element. Further, each transducer array element may include at least one first electrode that may be connected between the at least one piezoelectric layer and a signal conductor. Further, at least one second electrode may be connected between the at least one piezoelectric layer and a ground conductor. In some embodiments, each pMUT array element may have a predetermined shape configured to accommodate a predetermined fundamental mode vibration.

[0041] In one embodiment, the MEMS-based pMUT array 202 may comprise a plurality of pMUTs coupled to the distal end 806 of the ICE catheter 304. It is noted that the pMUT array is a circular phased array. In one embodiment, a first group of two or more transducers and a second group of two or more transducers may be connected in parallel. Furthermore, multiple elements of the multiple transducer array elements may be grouped to operate as a single array element.

[0042] Referring to FIG. 9, multi-channel electronic communication between an ultrasound imaging device 302 and a MEMS-based pMUT array 202 according to one embodiment of the present disclosure is shown. The MEMS-based pMUT array 202 may include a plurality of transducer array elements 204 arranged on the substrate 104. Furthermore, each of the plurality of transducer array elements 204 may provide a broadband of an individual focused beam. The MEMS-based pMUT array 202 may be coupled to the ultrasound imaging device 302 using a dongle cable. The MEMS-based pMUT array 202 disposed within the distal end 806 of the ICE catheter 304 may transmit at least one signal to the ultrasound imaging device 302 via an electronic flex cable 902 within the catheter shaft 502. The at least one signal may be an acoustic echo transmitted from the MEMS-based pMUT array 202. It is noted that the acoustic echo of the acoustic energy is received from the surface of the MEMS-based pMUT array 202 and received by the image processor 308.

[0043] Furthermore, the ultrasound beam has a bandwidth that includes a predetermined fundamental mode vibration of each of the plurality of transducer array elements 204, such that a single array element can simultaneously transmit and receive multiple fundamental mode vibrations. It is noted that the plurality of transducer array elements 204 can transmit and receive ultrasound beams relative to the heart or at least a portion of the heart. Furthermore, the electronic flex cable 902 within the catheter shaft 502 can be configured to receive at least one signal from the plurality of transducer array elements 204 based on the transmission and reception of the at least one ultrasound beam. The ultrasound imaging device 302 can further be configured to construct at least one image of the heart or at least a portion thereof based on the at least one signal. It is noted that the electronic flex cable is configured into a transmit beamformer 310 and a receive beamformer 312 to display two-dimensional (2D) image information of the heart or at least a portion of the heart.

[0044] In one embodiment, the plurality of transducer array elements 204 may correspond to microelectromechanical (MEMS)-based piezoelectric micromachined ultrasound transducers (pMUTs). The catheter shaft 502 may be connected to a handle assembly (not shown) at one end and to the MEMS-based pMUT array 204 at the other end. An electronics flex cable 902 within the catheter shaft 502 may be in communication with at least one signal trace. It is noted that the electronics flex cable 902 further communicates with a transmit beamformer 310 and a receive beamformer 312 via a custom dongle 306 to display two-dimensional (2D) image information of the scanned heart.

[0045] While particular structures embodying various embodiments of the invention have been shown and described herein, it will be apparent to those skilled in the art that various changes and rearrangements of the parts can be made therein without departing from the spirit and scope of the underlying inventive concept, and the invention is not to be limited to the specific forms shown and described herein, except to the extent indicated by the appended claims.

Claims

1. 1. An ultrasound imaging system comprising: The ultrasound imaging system includes an intracardiac echo catheter (ICE catheter) having a longitudinal axis, a proximal end, and a distal end; The ultrasound imaging system comprises a transducer ring disposed at a distal end of the ICE catheter, the transducer ring comprising a substrate and a micro-electromechanical-based (MEMS-based) piezoelectric micromachined ultrasound transducer (pMUT) array disposed on the substrate, the MEMS-based pMUT array being a forward-facing assembly and comprising a plurality of pMUT array elements mounted on the substrate in a circular or linear configuration; the ultrasound imaging system includes a steerable sheath integrated with a built-in forward-looking transducer and positioned at a distal end of the ICE catheter and integrated with the transducer ring; The ultrasound imaging system includes a catheter shaft connected to a handle assembly at one end and coupled to the MEMS-based pMUT array at the other end, the catheter shaft defining a lumen therein to allow a puncture needle and an electronic flex cable to pass toward the proximal end of the ICE catheter, the electronic flex cable being in communication with at least one signal trace; and communicating with the MEMS-based pMUT array via the at least one signal trace to transmit and receive ultrasound beams relative to the heart; receiving at least one signal from the MEMS-based pMUT array based on at least one transmission and reception of an ultrasonic beam; constructing at least one image of the heart or at least a portion thereof based on the at least one signal; An ultrasound imaging system configured to:

2. The ultrasound imaging system of claim 1 , wherein the transducer ring corresponds to a circular transducer ring comprising a MEMS-based pMUT array mounted in a circular configuration on the substrate.

3. 2. The ultrasound imaging system of claim 1, wherein the ICE catheter comprises a steering control unit disposed in a handle assembly for bending a distal end of the ICE catheter and aligning a face of the MEMS-based pMUT array toward an internal field of view including the fossa ovalis.

4. An intracardiac echocardiogram catheter (ICE catheter), the ICE catheter comprising: a body having a longitudinal axis and a distal end; a transducer ring disposed at the distal end of the ICE catheter; Equipped with the transducer ring comprises a substrate and a micro-electromechanical-based (MEMS-based) piezoelectric micromachined ultrasonic transducer array (pMUT array) disposed on the substrate, the MEMS-based pMUT array being a forward-facing assembly and comprising a plurality of transducer array elements disposed on the substrate; the ICE catheter comprises a steerable sheath, the steerable sheath being integrated with an integrated forward-looking transducer and integrated with the transducer ring located at a distal end of the ICE catheter; each transducer array element is comprised of a plurality of transducers, including a first group of two or more transducers in a first transducer array element and a second group of two or more transducers in the first transducer array element, each transducer array element being connected in parallel; and at least one piezoelectric layer disposed on the substrate; at least one first electrode connected between the at least one piezoelectric layer and a signal conductor; at least one second electrode connected between the at least one piezoelectric layer and a ground conductor; An ICE catheter comprising:

5. The ICE catheter of claim 4 , wherein each transducer array element is a linear phased array.

6. The ICE catheter of claim 4 , wherein each transducer array element is a circular phased array.

7. The ICE catheter of claim 4 , wherein the plurality of transducer array elements individually generate focused beams.

8. The ICE catheter of claim 4 , further comprising an electrically insulated shaft covering the shaft up to the imaging window.

9. 10. The ICE catheter of claim 8, wherein the electrically insulated shaft uses PEBAX material to cover the shaft up to the imaging assembly at the distal end of the body.

10. The ICE catheter of claim 4 , wherein the ICE catheter comprises a steering control unit for bending a distal end of the ICE catheter to align a face of the MEMS-based pMUT array toward an internal field of view that includes the fossa ovalis.

11. 11. The ICE catheter of claim 10, wherein the distal end of the ICE catheter is coated with a material that provides electrical insulation and transmission of ultrasound signals.

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