Integrated catheter system and method for cardiac mapping and piezoelectric micromachined ultrasound transducer (pMUT) ultrasound imaging

Abstract

An integrated cardiac mapping and piezoelectric micromachined ultrasound transducer (pMUT) ultrasound imaging system is disclosed. The system includes a pMUT imaging and mapping catheter having a longitudinal axis, a proximal end, and a distal end. A microelectromechanical (MEMS)-based pMUT or other transducer is disposed within the distal end of the pMUT imaging and mapping catheter. A pMUT mapping array is disposed within the distal end of the pMUT imaging and mapping catheter, the mapping array comprising an expandable basket, grid, hoop, or other configuration having an electronic sensor array disposed on an electronic flex circuit.

Description

[Technical Field]

[0001] The present disclosure relates generally to the field of cardiac mapping and ultrasound imaging and mapping catheters. More specifically, embodiments relate to a mapping catheter having a distal piezoelectric micromachined transducer for transmitting and receiving acoustic pulse information. [Background technology]

[0002] The use of catheter-based structural and electrophysiological procedures has recently expanded to more complex cases, and accurate definition of individual cardiac anatomy with variations is key to achieving optimal outcomes. In electrophysiological procedures, piezoelectric micromachined ultrasonic transducer (pMUT) imaging enables the integration of real-time imaging and mapping to guide transcatheter cardiac procedures. Cardiac mapping utilizes electrodes that measure cardiac tissue electrical activity. This electrical activity is transmitted to mapping system software, which creates a 3D model of the heart, displaying color-coded overlays indicating the radio waves generated during each heartbeat, the tissue touch points where the tissue was mapped, and the catheter's position within the heart. Tissues identified as having abnormal electrical activity responsible for arrhythmias can be directly ablated using an ablation catheter or isolated by creating small burned or scarred tissue that blocks electrical signals. The integration of pMUT imaging allows for real-time assessment of cardiac anatomy during interventional procedures and guides catheter manipulation in relation to different anatomical structures. Therefore, there is a need for improved mapping catheters that integrate ultrasound pMUT imaging.

[0003] Atrial fibrillation (AF) is one of the most widespread and persistent cardiac arrhythmias, affecting more than 30 million people worldwide. Its prevalence in developed countries tends to be small, approximately 1% to 4%. AF incidence is steadily increasing, and it is widely known that AF is associated with an increased risk of all-cause mortality, heart failure, thromboembolism, and dementia. Catheter mapping is an alternative treatment option that is more effective than antiarrhythmic drugs. Pulmonary vein isolation (PVI), which involves electrically isolating the pulmonary veins (PV) from the left atrium, remains the cornerstone of atrial fibrillation (AF) mapping. Catheter mapping is necessary to identify trigger and substrate locations for optimizing ablation strategies. The most commonly used cardiac mapping technique is isochronal mapping or activation mapping, which aims to create a spatial model of electrical wavefront propagation. Catheter mapping improves the ability to perform rapid and simultaneous contact mapping of cardiac chambers. Generally, modern mapping techniques can improve the efficacy, safety, and efficiency of mapping for persistent AF. Furthermore, current technology requires the separate use of mapping and ablation catheters and pMUT imaging catheters for intracardiac echocardiography (ICE). ICE has applications for structural cardiac pMUT imaging of the left atrial appendage (LAA), aids in septal defect closure and visualization of the fossa ovalis, and plays a role in transcatheter valve replacement. ICE is also used in EP procedures for ablation catheter guidance. ICE confirms the precise location of the catheter tip to aid in more precise ablation. ICE can also aid in safety monitoring of the pericardial cavity for cardiac tamponade or pericardial effusion, which are rarely caused by either transseptal puncture or ablation. ICE is expected to become increasingly important for better guiding the growing number of transcatheter ablation procedures. As transcatheter aortic and mitral heart valve replacement and LAA occlusion devices receive U.S. Food and Drug Administration (FDA) approval, the use of ICE is expected to increase for the precise deployment of these devices.

[0004] Furthermore, AF is a type of cardiac arrhythmia in which chaotic electrical conduction in the atria causes rapid, uncoordinated contractions, resulting in inefficient pumping of blood into the ventricles and a lack of synchronization. During AF, the atrioventricular node receives electrical impulses not only from the sinoatrial node, but also from multiple sites throughout the atria. This overloads the atrioventricular node, causing irregular and frequent heartbeats. As a result, blood pools in the atria, increasing the risk of blood clot formation. Major risk factors for atrial fibrillation include aging, coronary artery disease, rheumatic heart disease, hypertension, diabetes, and hyperthyroidism. AF affects 7% of the population aged 65 or older.

[0005] Furthermore, AF treatment options are limited. Lifestyle modifications are only effective for patients with lifestyle-related AF. Pharmacological therapy, while helpful in managing AF symptoms, can have more dangerous side effects than atrial fibrillation and does not cure AF. Cardioversion is often successful in restoring sinus rhythm but has a high recurrence rate. Furthermore, if a blood clot is present in the atrium, cardioversion can cause the clot to leave the heart and travel to the brain or other parts of the body, which can lead to a stroke. Therefore, improved cardiac mapping and pMUT ultrasound imaging catheter systems are needed. Summary of the Invention

[0006] By way of introduction, the preferred embodiments described below disclose an easy-to-use integrated cardiac mapping and piezoelectric micromachined ultrasound transducer (pMUT) ultrasound imaging catheter system. The integrated cardiac mapping and pMUT ultrasound imaging catheter system includes a pMUT imaging and mapping catheter having a longitudinal axis, a proximal end, and a distal end. Furthermore, an ultrasonic pMUT transducer array is disposed within the distal end of the pMUT imaging and mapping catheter. The ultrasonic pMUT transducer array comprises a plurality of pMUT transducer array elements disposed on a substrate. Note that the plurality of pMUT transducer array elements correspond to microelectromechanical (MEMS)-based pMUTs. Furthermore, the integrated cardiac mapping and pMUT ultrasound imaging catheter system includes a catheter shaft connected at one end to a handle assembly and at the other end to the ultrasonic pMUT transducer array. The catheter shaft contains an electronic flex cable that is in communication with at least one signal trace and is configured to direct each of the plurality of pMUT transducer array elements via the at least one signal trace to transmit and receive, to the heart, an ultrasound beam having a bandwidth that includes a predetermined fundamental mode vibration of each of the plurality of pMUT transducer array elements, such that a single array element simultaneously transmits and receives multiple fundamental mode vibrations; receive at least one signal from the plurality of pMUT transducer array elements based on transmitting and receiving at least one ultrasound beam of the plurality of ultrasound beams; and construct at least one image of at least a portion of the heart based on the at least one signal.

[0007] In one embodiment, an integrated cardiac mapping and pMUT ultrasound imaging catheter system includes a mapping catheter consisting of an open lumen catheter shaft with a collapsible basket-shaped distal end, the mapping catheter consisting of multiple electrodes mounted on a plurality of flexible, self-expanding, equally spaced metallic spline electrodes, the mapping catheter being constructed of a flexible material to enable passive deployment of the array catheter and optimize contact with the endocardium.

[0008] According to another aspect of the present invention, an integrated ultrasound imaging and mapping system is disclosed. The integrated ultrasound imaging and mapping system includes a mapping catheter having a longitudinal axis, a proximal end, and a distal end. The integrated ultrasound imaging and mapping system further includes a MEMS-based piezoelectric micromachined ultrasound transducer (pMUT) array disposed within the distal end of the mapping catheter. The MEMS-based pMUT array includes a substrate and a plurality of MEMS-based pMUT array elements disposed on the substrate. The integrated ultrasound imaging and mapping system further includes a mapping array disposed within the distal end of the mapping catheter, the mapping array comprising an expandable basket, grid, hoop, or other configuration having an electronic sensor array disposed on an electronic flex circuit.

[0009] According to another aspect of the present invention, a medical device is disclosed. The medical device includes a catheter shaft, a first carrier assembly, and a second carrier assembly. The first carrier assembly is coupled to the catheter shaft and has a first radially expandable electrode array coupled to a plurality of first carrier arms. The second carrier assembly is rotatably coupled to the catheter shaft and has a second radially expandable electrode array coupled to a plurality of second carrier arms, the second carrier assembly being rotatable about the first carrier assembly. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates a prior art imaging system for acquiring two-dimensional image information. [Figure 2] FIG. 1 illustrates a prior art imaging system for acquiring two-dimensional image information. [Figure 3] FIG. 1 is a schematic diagram of an integrated cardiac mapping and piezoelectric micromachined ultrasound transducer (pMUT) ultrasound imaging catheter system according to an embodiment of the present disclosure. [Figure 4] FIG. 1 illustrates multi-channel electronic communication between a pMUT imaging and mapping device and a pMUT imaging and mapping catheter, according to an embodiment of the present disclosure. [Figure 5] 1 is a cross-sectional view of a distal end of a pMUT imaging and mapping catheter having multiple pMUT transducer array elements, according to an embodiment of the present disclosure. [Figure 6] FIG. 1 is a perspective view of a distal portion of a pMUT imaging and mapping catheter according to an embodiment of the present disclosure. [Figure 7] FIG. 10 illustrates multiple circular mapping pMUT arrays arranged in a cylindrical configuration, according to an embodiment of the present disclosure. [Figure 8] FIG. 1 illustrates multiple linear pMUT imaging arrays arranged in a line, according to an embodiment of the present disclosure. [Figure 9] 1 is a perspective view of a distal portion of a pMUT imaging and mapping catheter in a partially deployed state having multiple circular pMUT imaging arrays arranged in a linear fashion, according to an embodiment of the present disclosure. FIG. [Figure 10] 1 is a perspective view of a distal portion of a pMUT imaging and mapping catheter in a partially deployed state having multiple linear pMUT imaging arrays arranged in a line, according to an embodiment of the present disclosure. FIG. [Figure 11]FIG. 10 illustrates a grid mapping view of a pMUT imaging and mapping catheter having multiple circular pMUT imaging arrays arranged in a linear fashion, according to an embodiment of the present disclosure. [Figure 12] FIG. 10 illustrates a grid mapping view of a pMUT imaging and mapping catheter having multiple linear pMUT imaging arrays arranged in a line, according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] The accompanying drawings illustrate various embodiments of systems, methods, and various aspects of the present disclosure. Those skilled in the art will understand that the boundaries of illustrated elements in the figures (e.g., boxes, groups of boxes, or other shapes) represent one example of various boundaries that represent the disclosed invention. In some examples, one element may be designed as multiple elements, or multiple elements may be designed as one element. In other examples, an element shown as an internal component of one element may be implemented as an external component of another element, and vice versa. Additionally, elements may not be drawn to scale. A non-limiting and non-exhaustive description of the present disclosure is described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed on the principles illustrated.

[0012] Various embodiments are described below in accordance with the accompanying drawings, which are provided to illustrate, but not in any way limit, the scope of the present disclosure, and in which like symbols indicate like elements.

[0013] The components of the embodiments, as generally described and illustrated in the Figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of various embodiments, as represented in the Figures, is not intended to limit the scope of the disclosure, but is merely representative of various embodiments. While various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0014] Next, several embodiments of the present disclosure that exhibit all the features of the present disclosure will be described in detail. The words "comprising," "having," "containing," and "including," as well as their derivatives, are equivalent in meaning and are intended to be open-ended in that the item or items following any one of these words are not meant to be an exhaustive listing of such item or items, or to be limited only to the listed item or items.

[0015] It should also be noted that as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context requires otherwise. 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, preferred systems and methods are described herein. The terms "proximal" and "distal" are opposite terms. For example, the distal end of a device or component is the end of the component that is farthest from the practitioner during normal use. The proximal end refers to the opposite end, or the end that is closest to the practitioner during normal use.

[0016] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which like numerals represent like elements throughout the several views and in which exemplary embodiments are shown. However, embodiments of the present disclosure may be embodied in alternative forms and should not be construed as limited to the embodiments set forth herein. The examples set forth herein are non-limiting examples and are merely examples among other possible examples.

[0017] 1 and 2 illustrate a prior art imaging system 100. The imaging system 100 provides an ultrasound transmit pulse 102 and an ultrasound receive path 104 for connection to an ultrasound transducer (not shown). The ultrasound transmit pulse 102 may transmit an ultrasound signal from the imaging system 100 toward an object, such as a patient's heart. Additionally, the ultrasound receive path 104 may generate a waveform based at least on the ultrasound signal. The imaging system 100 may then convert the received ultrasound signal or information into a two-dimensional (2D) image of the object or portion of the object.

[0018] FIG. 3 shows a schematic diagram of an integrated cardiac mapping and piezoelectric micromachined ultrasound transducer (pMUT) ultrasound imaging catheter system 300, according to one embodiment of the present disclosure.

[0019] In one embodiment, the integrated cardiac mapping and pMUT ultrasound imaging catheter system 300 may utilize a microelectromechanical (MEMS) pMUT transducer array, defined as a pMUT, or other types of MEMS transducers, interconnected using a suitable flexible circuit. Note that the use of a high-density flexible circuit may enable highly repeatable and stable transmitted and returned signals. Furthermore, the transmission lines of the high-density flexible circuit may transmit electrical energy from one end of the integrated cardiac mapping and pMUT ultrasound imaging catheter system 300 to the other distal end.

[0020] The integrated cardiac mapping and pMUT ultrasound imaging catheter system 300 may include a pMUT imaging and mapping device 302 connected to a pMUT imaging and mapping catheter 304 via a communication channel 306. The pMUT imaging and mapping device 302 may include a display 308, an image processor 310, a receive beamformer 312, a transmit beamformer 314, and a dongle 316. The pMUT imaging and mapping catheter 304 may be positioned within a chamber of the patient's heart, and the pMUT imaging and mapping device 302 may receive at least one signal from the pMUT imaging and mapping catheter 304. The at least one signal may be communicated from the pMUT imaging and mapping catheter 304 to the pMUT imaging and mapping device 302 via an electronic flex cable (not shown) connected to the dongle 316.

[0021] The image processor 310 may be configured to generate two-dimensional (2D) images according to data received from the pMUT imaging and mapping catheter 304. In one embodiment, the image processor 310 may be configured to receive focused signals from the receive beamformer 312. The image processor 310 may render the data to construct an image or a series of images. In one embodiment, the image may be a three-dimensional (3D) representation, such as a two-dimensional image rendered from a viewpoint selected by a user or a processor. In one embodiment, the image processor 310 may be a detector, filter, processor, application specific integrated circuit, field programmable gate array, digital signal processor, control processor, scan converter, three-dimensional image processor, graphics processing unit, analog circuit, digital circuit, or combination thereof. The image processor 310 may receive the beamformed data and generate an image for display on the display 308. It is noted that the generated image is associated with a two-dimensional (2D) scan. Alternatively, the generated image may be a three-dimensional (3D) representation.

[0022] The image processor 310 may be programmed to support hardware-accelerated two-dimensional reconstruction. The image processor 310 may store processed data of at least one signal and a sequence of images in memory. In one embodiment, the memory may be a non-transitory computer-readable storage medium. Instructions for implementing the processes, methods, and / or techniques described herein may be provided on a computer-readable storage medium or memory, such as a cache, buffer, RAM, removable media, 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. The 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, etc., operating alone or in combination.

[0023] The pMUT imaging and mapping catheter 304 may be in electronic communication with the pMUT imaging and mapping device 302 for transmitting and receiving ultrasound signals to and from the arterial walls of the vasculature. In one embodiment, the pMUT imaging and mapping catheter 304 may be configured to visualize standard echocardiographic images of the heart, for example, in a standard version, the right atrium may be visualized. The pMUT imaging and mapping catheter 304 may be employed in transseptal catheterization for several percutaneous interventions, including left heart catheter mapping and atrial septal defect closure, as an effective alternative to surgical intervention. In one embodiment, the pMUT imaging and mapping catheter 304 may comprise a body having a longitudinal axis, a proximal end, a distal end, a handle assembly, a catheter shaft, an electronic flex cable, and a distal tip, as shown in FIG. 6 .

[0024] Referring to FIG. 4, multi-channel electronic communication between a pMUT imaging and mapping device 302 and a pMUT imaging and mapping catheter 304 is disclosed, according to one embodiment of the present disclosure.

[0025] The pMUT imaging and mapping catheter 304 may comprise a catheter shaft (not shown) and a MEMS-based pMUT array 402 coupled to the pMUT imaging and mapping device 302 via a dongle 316. The dongle 316 may be referred to as a communication channel connected to the catheter shaft.

[0026] The MEMS-based pMUT array 402 may include a plurality of pMUT array elements 404 disposed on a substrate 406. Furthermore, each of the plurality of pMUT array elements 404 may provide a wide bandwidth for an individual focused beam. The MEMS-based pMUT array 402 may be connected to the pMUT imaging and mapping device 302 using a dongle 316, as described above. The MEMS-based pMUT array 402 disposed within the distal end of the pMUT imaging and mapping catheter 304 may transmit at least one signal to the pMUT imaging and mapping device 302 via an electronic flex cable within the catheter shaft. The at least one signal may be an acoustic echo transmitted from the MEMS-based pMUT array 402. Note that the acoustic echo of the acoustic energy may be received from the front surface of the MEMS-based pMUT array 402 and received at the image processor 310.

[0027] The ultrasound beam may have a bandwidth that includes a predetermined fundamental mode vibration of each of the multiple pMUT array elements 404, such that a single array element may simultaneously transmit and receive multiple fundamental mode vibrations. It should be noted that the multiple pMUT array elements 404 may transmit and receive ultrasound beams relative to the heart or at least a portion of the heart. Furthermore, an electronic flex cable within the catheter shaft may be configured to receive at least one signal from the multiple pMUT array elements 404 based on transmitting and receiving at least one ultrasound beam of the multiple ultrasound beams. The pMUT imaging and mapping device 302 may further be configured to construct at least one image of at least a portion of the heart based on the at least one signal. It should be noted that the electronic flex cable may be configured for the transmit beamformer 314 and the receive beamformer 312 to display two-dimensional (2D) image information of the heart or at least a portion of the heart.

[0028] In one embodiment, the plurality of pMUT array elements 404 may correspond to MEMS-based pMUTs. A catheter shaft may be connected at one end to the handle assembly 324 and at the other end to the MEMS-based pMUT array 402. An electronic flex cable within the catheter shaft may be in communication with at least one signal trace. Note that the electronic flex cable may further be in communication with the transmit beamformer 314 and the receive beamformer 312 via the dongle 316 to display two-dimensional (2D) image information of the heart being scanned.

[0029] Referring to FIG. 5, a cross-sectional view of the distal end of a pMUT imaging and mapping catheter 304 having a plurality of pMUT transducer array elements 402 is disclosed, according to one embodiment of the present disclosure.

[0030] The MEMS-based pMUT array 402 may include multiple pMUT array elements 404 disposed at the distal end of the pMUT imaging and mapping catheter 304. The distal end of the pMUT imaging and mapping catheter 304 may be provided with the MEMS-based pMUT array 402 having multiple pMUT array elements 404. Furthermore, each of the multiple pMUT array elements 404 may have multiple individual transducer cells 502 arranged to provide a wide bandwidth of the individual focused beam. In one embodiment, the MEMS-based pMUT array 402 may be constructed from a pMUT array including individual elements of different diameters. In one embodiment, to achieve wider bandwidths with the pMUT array, multiple pMUT cells with multiple diameters may be integrated into one element. Note that by arranging preformed pMUTs with different diameters, wider bandwidths may be achieved through complex interactions between the individual pMUT elements. In one embodiment, pMUT cells of multiple diameters may achieve a bandwidth greater than 55%. For example, with three elements, there are five different dome diameters, and each array has a different size, such as 300 μm.

[0031] Furthermore, the MEMS-based pMUT array 402 may correspond to a pMUT, and the plurality of pMUT array elements 404 may correspond to a plurality of pMUT elements. In one embodiment, the plurality of pMUT elements may be oriented to transmit and receive multiple ultrasound beams having bandwidths that include predetermined fundamental mode vibrations of each of the plurality of pMUT elements, allowing a single pMUT element to simultaneously transmit and receive multiple fundamental mode vibrations. Furthermore, an electronic flex cable within the catheter shaft receives at least one signal from the plurality of pMUT elements. Note that the at least one signal may correspond to at least one ultrasound beam. The at least one signal may be transmitted to the pMUT imaging and mapping device 302 for further processing in the image processor 310. The image processor 310 may construct at least one image of the heart. Note that multiple pMUT elements may be used to generate individual focused beams. In one embodiment, the plurality of pMUT elements are arranged in a linear configuration. In a second embodiment, the pMUTs are arranged in a cylindrical configuration, as shown in FIGS. 7-8.

[0032] Referring to FIG. 6, there is disclosed a perspective view of a distal portion of a pMUT imaging and mapping catheter 304, the device including an electronic connection assembly and a distal mapping carrier assembly, according to one embodiment of the present disclosure.

[0033] The pMUT imaging and mapping catheter 304 may include multiple expandable baskets 602 having multiple flexible splines 604 arranged alternately along the length of each of the multiple expandable baskets 602. The multiple expandable baskets 602 may be arranged serially along a single axis in an umbrella-shaped tip configuration. Furthermore, the pMUT imaging and mapping catheter 304 preferably includes an elongated tube as the catheter shaft 606 constructed from Pebax® material and approximately 6-8 French diameter. Alternatively, instead of an expandable basket, the mapping catheter may include a grid, hoop, or other configuration. The catheter shaft 606 slidably receives a first control shaft 608. The first control shaft 608 is attached at its distal portion to the multiple expandable baskets 602, grid, hoop, or other configuration.

[0034] Additionally, the plurality of flexible splines 604 are configured with an electronic sensor 610. The plurality of flexible splines 604 may have a first end 612 and a second end 614. The first end 612 of the plurality of flexible splines 604 is attached to a control on the proximal end of the pMUT imaging and mapping catheter 304 that is configured to allow an operator to precisely advance and retract the plurality of expandable baskets 602, grid, hoop, or another configuration.

[0035] Additionally, the pMUT imaging and mapping catheter 304 may include a first carrier assembly and a second carrier assembly (not shown) coupled to the catheter shaft 606. The first carrier assembly and the second carrier assembly may have a first radially expandable electrode array and a second radially expandable electrode array coupled to a plurality of first carrier arms and a plurality of second carrier arms (not shown). Note that the first and second radially expandable electrode arrays may correspond to electronic sensors 610. Note also that the plurality of first carrier arms and the plurality of second carrier arms may correspond to a plurality of flexible splines 604. The second carrier assembly is rotatable about the first carrier assembly. In one embodiment, the first and second radially expandable electrode arrays may include a series of longitudinally spaced electrodes or electronic sensors 610 longitudinally spaced along the plurality of expandable baskets 602. Alternatively, instead of an expandable basket, the mapping catheter may include a grid, hoop, or other configuration.

[0036] Additionally, the pMUT imaging and mapping catheter 304 may include a first ring 616 on the first end 612. The first ring 616 fixedly attaches one end of the plurality of flexible splines 604. The plurality of flexible splines 604 may be made from nitinol. Note that the nitinol is resiliently biased into a straight tip configuration or an umbrella tip configuration. Furthermore, advancement and retraction of the first control shaft 608 changes the diameter of the plurality of expandable baskets 602, including a fully compressed (smallest diameter) radial state when the first control shaft 608 is fully advanced and a maximum diameter state when the first control shaft 608 is fully retracted.

[0037] Additionally, the pMUT imaging and mapping catheter 304 may include a plurality of mapping elements 618 fixedly attached to each of the plurality of flexible splines 604. The mapping elements 618 are configured to map conductive pathways within the tissue. Additionally, the mapping elements 618 may include electronic sensors 610 configured for mapping. In another embodiment, the mapping elements 618 are connected to wires (not shown) that extend proximally to the proximal end of the pMUT imaging and mapping catheter 304 for connection to an energy delivery unit, a mapping unit, and / or another electronic device for transmitting or receiving signals and / or power.

[0038] Additionally, the mapping element 618 is configured to map electrical activity present in the tissue to identify target regions for creating ablation lesions and / or otherwise assess the patient's condition. In one embodiment, the mapping element 618 is constructed from an electronic sensor, a conductive material such as platinum or a platinum-iridium alloy, etc. Additionally, the mapping element 618 may include an integrated temperature sensor, such as a thermocouple, welded to an interior portion of the mapping element 618. In another embodiment, the mapping element 618 and the integrated temperature sensor or other sensor are connected to wires (not shown) that extend proximally to a proximal portion of the pMUT imaging and mapping catheter 304 for connection to the pMUT imaging engine, mapping unit, energy delivery unit, and / or another electronic device for transmitting or receiving signals and / or power.

[0039] The first control shaft 608 further includes a distal tip 620 at its distal end. In one embodiment, the distal tip 620 may be constructed from a soft or flexible material, such as a soft plastic or elastomer, that is preferably atraumatic to tissue and is preferably radiopaque, such as a Pebax® material doped with barium sulfate. Note that the distal tip 620 is constructed to aid in navigation into and stabilization within the pulmonary vein. The first control shaft 608 may further include a cylindrical portion 622 between the first ring 616 and the distal tip 620. The cylindrical portion 622 is configured to move on the first control shaft 608. The cylindrical portion 622 is configured to move the first ring 616 in a forward or backward direction to expand or contract the plurality of expandable baskets 602, grids, hoops, or other structures to map the heart wall. Additionally, the first ring 616 may carry a MEMS-based pMUT transducer configured to image the heart wall, as shown in FIGS.

[0040] Additionally, the pMUT imaging and mapping catheter 304 may include a second ring 624 proximal to the cylindrical portion 622 between the first end 612 and the second end 614. In one embodiment, the cylindrical portion 622 may correspond to a cylinder in radial motion between the first end 612 and the second end 614. The second ring 624 may be disposed on the first control shaft 608. Additionally, the first ring 616 and the second ring 624 may have the MEMS-based pMUT array 402 mounted thereon in a circular or cylindrical configuration, as shown in FIGS.

[0041] FIG. 7 illustrates multiple circular mapping pMUT arrays 702 arranged in a cylindrical configuration, according to one embodiment of the present disclosure. In one embodiment, a plurality of circular mapping pMUT arrays 702 may be cylindrically mounted on the first ring 616, the distal tip 620, and the second ring 624. In one embodiment, the plurality of circular mapping pMUT arrays 702 correspond to pMUT circular arrays or pMUT elements.

[0042] FIG. 8 illustrates multiple linear pMUT imaging arrays 802 arranged in a line, according to an embodiment of the present disclosure. In one embodiment, the first ring 616, the distal tip 620, and the second ring 624 may have multiple linear pMUT imaging arrays 802 mounted in a linear arrangement.

[0043] In one embodiment, the multiple circular mapping pMUT arrays 702 and multiple linear pMUT imaging arrays 802 may be arrays of mapping elements, preferably geometrically adjustable electrode arrays, and may be configured in a wide variety of configurations and patterns. In another embodiment, the multiple circular mapping pMUT arrays 702 and multiple linear pMUT imaging arrays 802 deliver electrical energy, such as radiofrequency (RF) energy, in a unipolar, bipolar, or combined unipolar-bipolar manner, and also provide a method for treating conditions (e.g., atrial fibrillation, supraventricular tachycardia, atrial tachycardia, ventricular tachycardia, ventricular fibrillation, etc.). Furthermore, multiple types of mapping catheters may be used for various minimally invasive procedures. Minimally invasive procedures include atrioventricular (AV) node ablation, which treats the irregular, fast, and chaotic heartbeat called atrial fibrillation; cryoablation, which uses cryogenic liquids or an instrument called a cryoprobe to freeze and remove abnormal tissue; and epicardial ablation, which creates a small scar on the outside of the heart to block faulty electrical signals that cause the heart to beat too fast, restoring a regular heart rhythm.

[0044] Referring to FIG. 9, a perspective view of a distal portion of an alternative pMUT imaging and mapping catheter 304 in a partially deployed state having multiple circular pMUT imaging arrays 702 arranged in a linear fashion is disclosed, in accordance with one embodiment.

[0045] The first control shaft 608 of the pMUT imaging and mapping catheter 304 is in a straight configuration for advancing the pMUT imaging and mapping catheter 304 over the guidewire 902. Once inserted into the femoral vein, the guidewire 902 is advanced for intraluminal advancement, traveling to the heart and through the septum separating the right and left atria (e.g., through a transseptal sheath) into a pulmonary vein, such as the left superior pulmonary vein. The first control shaft 608 is deployed into this straight, maximally compact configuration by advancing the first control shaft 608, such as by manipulating a control on a handle. The multiple expandable baskets 602, grid, hoop, or other configuration comprises multiple mapping elements 618. The multiple expandable baskets 602 or alternative configuration have a proximal end fixedly attached to the catheter shaft 606 via a first ring 616. Note that the first ring 616 may also be referred to as a crimp ring. The plurality of circular pMUT imaging arrays 702 are linearly arranged on the first ring. The first ends 612 of the plurality of flexible splines 604 are fixedly attached to the first control shaft 608 at a radial position offset by 90° from the attachment position at the proximal end such that the plurality of flexible splines 604 expand radially as the first control shaft 608 is retracted. The distal end of the first control shaft 608 is capped by a distal tip 620. A cylindrical portion 622 is slidably positioned to abut the distal tip 620. In one embodiment, the distal tip 620 can be an atraumatic tip with an exit hole (not shown) that communicates with an internal guidewire lumen through which a guidewire passes.

[0046] In one embodiment, the distal portion of the pMUT imaging and mapping catheter 304 is in a partially deployed state, and the multiple linear pMUT imaging arrays 802 are arranged in a linear fashion, as shown in Figure 10. The multiple linear pMUT imaging arrays 802 may be arranged in a linear fashion on the first ring 616.

[0047] The present invention provides a pMUT imaging and mapping catheter 304 for mapping target tissues of interest, such as atrial fibrillation, supraventricular tachycardia, atrial tachycardia, ventricular tachycardia, and ventricular fibrillation. In an alternative embodiment, the pMUT imaging and mapping catheter 304 may comprise a tubular body member (not shown) having proximal and distal ends and, preferably, a lumen extending therebetween. The pMUT imaging and mapping catheter 304 is preferably of a type used to perform intracardiac procedures and is typically introduced subcutaneously and advanced from the femoral vein in the patient's leg. Alternative methods include percutaneous introduction into the jugular vein in the patient's neck or other anatomical introduction point that can be used to access a target site within the patient. The pMUT imaging and mapping catheter 304 is preferably introduceable through a sheath and, preferably, advanceable over a guidewire. The pMUT imaging and mapping catheter 304 preferably has a steerable tip that allows for precise positioning of the distal portion.

[0048] The pMUT imaging and mapping catheter 304 enables the creation of ablation lesions of appropriate size and shape to treat conditions associated with disorganized electrical conduction (e.g., atrial fibrillation). The created lesions are segmented and localized. The lesions can be linear or curved, circular or partial circular, and / or continuous or discontinuous. The pMUT imaging and mapping catheter 304 is also practical in that it is highly maneuverable, reduces patient risk, and significantly shortens procedure time. The lesions created by the pMUT imaging and mapping catheter 304 are suitable for suppressing the propagation of inappropriate electrical impulses in the heart to prevent reentrant arrhythmias.

[0049] In one embodiment, energy to the pMUT imaging and mapping catheter 304 may be delivered using a pulse-width modulated drive signal, as is known to those skilled in the art. Additionally, energy may also be delivered in a closed-loop manner, such as a system with temperature feedback, where the type, frequency, and / or intensity of delivered energy is adjusted in response to temperature.

[0050] Referring to FIG. 11, a grid mapping view of a pMUT imaging and mapping catheter 304 having multiple circular pMUT imaging arrays 702 arranged in a linear fashion is disclosed, according to one embodiment of the present disclosure.

[0051] Additionally, the pMUT imaging and mapping catheter 304 may include a mapping element 1002 fixedly attached to each of the plurality of flexible splines 1004. The mapping element 1002 is configured to map conductive pathways within the tissue. Furthermore, the mapping element 1002 is configured to map electrical activity present within the tissue to identify target regions for creating ablation lesions and / or otherwise assess the patient's condition. In one embodiment, the mapping element 1002 is constructed from an electronic sensor, a conductive material such as platinum or a platinum-iridium alloy, etc. Furthermore, the mapping element 1002 may include an integrated temperature sensor, such as a thermocouple, welded to an interior portion of the mapping element 1002. In another embodiment, the mapping element 1002 and the integrated temperature sensor or other sensor are connected to wires (not shown) that extend proximally to a proximal portion of the mapping catheter 304 for connection to the pMUT imaging engine, mapping unit, energy delivery unit, and / or another electronic device for transmitting or receiving signals and / or power.

[0052] Additionally, the pMUT imaging and mapping catheter 304 may include a first ring 1006 having a plurality of circular mapping pMUT arrays 702 arranged in a cylindrical configuration. In one embodiment, the first ring 1006 has a plurality of linear pMUT imaging arrays 802 arranged in a linear configuration, as shown in FIG.

[0053] In one embodiment, the multiple circular mapping pMUT arrays 702 and multiple linear pMUT imaging arrays 802 may be arrays of mapping elements, preferably geometrically adjustable electrode arrays, and may be configured in a wide variety of shapes and patterns. In another embodiment, the multiple circular mapping pMUT arrays 702 and multiple linear pMUT imaging arrays 802 deliver electrical energy, such as radiofrequency (RF) energy, in a unipolar, bipolar, or combined unipolar-bipolar manner, and also provide a method for treating conditions (e.g., atrial fibrillation, supraventricular tachycardia, atrial tachycardia, ventricular tachycardia, ventricular fibrillation, etc.). Furthermore, multiple types of mapping catheters may be used for various minimally invasive procedures. Minimally invasive procedures include atrioventricular (AV) node ablation, which treats the irregular, fast, and chaotic heartbeat called atrial fibrillation; cryoablation, which uses cryogenic liquids or an instrument called a cryoprobe to freeze and remove abnormal tissue; and epicardial ablation, which creates a small scar on the outside of the heart to block faulty electrical signals that cause the heart to beat too fast, restoring a regular heart rhythm.

[0054] In one embodiment, the electrodes or mapping elements may have one or more different shapes. As used herein, the terms "proximal energy delivery carrier assembly and distal energy delivery carrier assembly" refer to flexible carriers on which one or more mapping elements are disposed. The carrier assemblies include one or more carrier arms, as described above as arm segments. The carrier assemblies are not limited in size or shape and can be configured in an extended state, a non-extended state, or a compact state. As used herein, the terms "proximal carrier arm and distal carrier arm" refer to wire-like shafts capable of interfacing with electrodes and a control shaft. Furthermore, the distal and proximal carrier arms are not limited to any size or measurement.

[0055] Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims. In addition, where this application recites method or procedure steps in a particular order, it is intended that the order in which some steps are performed be changed or may be advantageous in particular circumstances, and that particular steps in the method or procedure claims set forth herein below are not to be construed as order-specific unless such order-specificity is expressly recited in the claims.

Claims

1. 1. An integrated cardiac mapping and piezoelectric micromachined ultrasound transducer (hereinafter pMUT) ultrasound imaging system, comprising: a pMUT imaging and mapping catheter having a longitudinal axis, a proximal end, and a distal end; a microelectromechanical (hereinafter MEMS)-based pMUT or other transducer disposed within the distal end of the mapping catheter, the MEMS-based pMUT array comprising a substrate and a plurality of pMUT array elements disposed on the substrate; and a mapping array disposed within the distal end of the pMUT imaging and mapping catheter, the mapping array comprising an expandable basket, grid, hoop, or other configuration having an electronic sensor array disposed on an electronic flex circuit or micro-coaxial cable.

2. The integrated cardiac mapping and pMUT ultrasound imaging system of claim 1 , further comprising a catheter shaft having one end connected to a handle assembly and another end connected to the MEMS-based pMUT array and further to the mapping array.

3. 3. The integrated cardiac mapping and pMUT ultrasound imaging system of claim 2, wherein the mapping catheter comprises a steering control unit disposed within the handle assembly for articulating the distal tip of the pMUT imaging and mapping catheter and adjusting the face of the MEMS-based pMUT array toward an internal field of view including anterior or posterior positions and right or left positions of the tissue.

4. 4. The integrated cardiac mapping and pMUT ultrasound imaging system of claim 3, wherein the distal tip of the mapping catheter is coated with a material that provides electrical insulation and transparency to ultrasound signals.

5. 2. The integrated cardiac mapping and pMUT ultrasonic imaging system of claim 1, wherein the pMUT imaging and mapping catheter is connected to a dongle, and the dongle is configured to transmit ultrasonic transmit pulses and ultrasonic receive waveforms between the pMUT array and an integrated ultrasound and mapping computer system.

6. 2. The integrated cardiac mapping and pMUT ultrasound imaging system of claim 1, wherein the pMUT imaging and mapping catheter is connected to a dongle, and the dongle is configured to communicate electronic mapping data between a mapping basket, grid, hoop, or other configuration and an integrated ultrasound and mapping computer system.

7. 10. The integrated cardiac mapping and pMUT ultrasound imaging system of claim 1, wherein each of the plurality of pMUT array elements has transducer cell diameters of multiple diameters to achieve wide bandwidth.

8. The integrated cardiac mapping and pMUT ultrasound imaging system of claim 1 , wherein each of the plurality of pMUT array elements is a linear phased array.

9. The integrated cardiac mapping and pMUT ultrasound imaging system of claim 1 , wherein each of the plurality of pMUT array elements is a pMUT circular array.

10. The integrated cardiac mapping and pMUT ultrasound imaging system of claim 1 , wherein the electronic sensor array corresponds to a plurality of mapping elements.

11. The integrated cardiac mapping and pMUT ultrasound imaging system of claim 1 , wherein the expandable basket, grid, hoop, or other structure is positioned to abut an interior wall of the heart.

Images