Catheter with integrated controller for imaging and pressure sensing

Abstract

An intravascular ultrasound (IVUS) device includes a flexible, slender member having a proximal portion and a distal portion; a controller connected to the distal portion of the flexible, slender member; an ultrasound transducer disposed at the distal portion of the flexible, slender member and communicating with the controller; a pressure transducer disposed at the distal portion of the flexible, slender member and communicating with the controller; and a plurality of conductors extending from the controller to the proximal portion of the catheter, at least one of the plurality of conductors being configured to carry a signal representing information captured by the ultrasound transducer and information captured by the pressure transducer.

Description

[0001] This application is a divisional application of Chinese invention patent application No. 201580020949.0, filed on April 21, 2015, entitled “CATHEA WITH INTEGRATED CONTROLLER FOR IMAGING AND PRESSURE SENSING”. Technical Field

[0002] The present disclosure generally relates to systems, devices and methods for using controllers for imaging sensors and pressure sensors for diagnostic evaluation of a target area of ​​a patient. More specifically, the present disclosure relates to systems, devices and methods for performing intravascular ultrasound (IVUS) imaging and pressure sensing for diagnostic evaluation of a target area of ​​a patient (e.g., a patient's vasculature) using a common controller. Background Art

[0003] Intravascular ultrasound (IVUS) imaging is widely used as a diagnostic tool in interventional cardiology for evaluating diseased vessels (e.g., arteries) in the human body, for determining the need for treatment, for guiding the intervention and / or for evaluating its effectiveness. IVUS imaging uses ultrasonic echoes to form a cross-sectional image of the vessel of interest. Typically, an ultrasonic transducer on an IVUS catheter emits ultrasonic pulses and receives reflected ultrasonic echoes. Ultrasonic waves easily pass through most tissues and blood, but they are partially reflected by discontinuities caused by tissue structures (e.g., multilayer vessel walls), red blood cells, and other features of interest. An IVUS imaging system connected to the IVUS catheter via a patient interface module processes the received ultrasonic echoes to produce a cross-sectional image of the vessel in which the catheter is positioned.

[0004] There are two types of IVUS catheters in routine use today: solid-state and rotatable, each with advantages and disadvantages. Solid-state IVUS catheters use an array of ultrasonic transducers (typically 64) distributed around the circumference of the catheter and connected to an electronic multiplexer circuit. The multiplexer circuit selects the array element for transmitting ultrasonic pulses and receiving echo signals. By stepping through a series of transmit-receive pairs, solid-state IVUS systems are able to synthesize the effects of mechanically scanned transducer elements, but without moving parts. Since there are no rotating mechanical elements, the transducer array can be placed in direct contact with blood and vascular tissue, and this has minimal risk of vascular damage, and the solid-state scanner can be directly wired to the imaging system using a simple cable and a standard detachable electrical connector.

[0005] In a conventional rotatable IVUS catheter, a single ultrasonic transducer element made of piezoelectric ceramic material is located at the end of a flexible drive rod that rotates in a plastic sheath inserted into the vessel of interest. The transducer element is oriented so that the ultrasound beam propagates approximately perpendicular to the axis of the catheter. The fluid-filled sheath protects the vascular tissue from the rotating transducer and drive rod while allowing the ultrasonic signal to propagate freely from the transducer into the tissue and back. As the drive rod rotates (usually at 30 revolutions per second), the transducer is periodically excited with high-voltage pulses to emit short bursts of ultrasound. The same transducer then listens for return echoes reflected from different tissue structures, and the IVUS imaging system uses a sequence / echo acquisition sequence consisting of hundreds of these ultrasonic pulses that occurs during a single rotation of the transducer to combine into a two-dimensional display of a cross-section of the vessel.

[0006] Although the solid-state IVUS catheter is simple to use, it cannot match the image quality that can be obtained from a rotatable IVUS catheter due to its lack of moving parts. It is difficult to operate a solid-state IVUS catheter at the same high frequency as a rotatable IVUS device, and the lower operating frequency of the solid-state IVUS catheter translates into poorer resolution compared to the operating frequency of a higher-frequency rotatable IVUS catheter. There are also artifacts (artifacts) that are greatly reduced or completely absent using a rotatable IVUS device due to array-based imaging, such as side lobes, grating lobes, and poor elevation focus (perpendicular to the imaging plane). Despite the advantages of the image quality of rotatable IVUS catheters, each of these devices has found a niche in the interventional cardiology market, with solid-state IVUS being preferred where ease of use is critical and reduced image quality is acceptable for specific diagnostic needs, while rotatable IVUS is preferred where image quality is critical and more time-consuming catheter preparation is justified.

[0007] In a rotatable IVUS catheter, the ultrasound transducer is typically a piezoelectric ceramic element with low electrical impedance that is capable of directly driving the cable that connects the transducer to the imaging system hardware. In this case, a single pair of electrical wires (or coaxial cable) is used to carry the transmit pulses from the system to the transducer, and the received echo signals from the transducer back to the imaging system through the patient interface module, where they are combined into an image.

[0008] Some catheters utilize pressure sensors configured to assess the severity of stenosis in a blood vessel, including lesions caused by ischemia. One method for assessing the severity of a stenosis includes taking two blood pressure measurements using a pressure sensor: one measurement distal to or downstream of the stenosis and one measurement proximal to or upstream of the stenosis. The pressure difference can be used to calculate a value representing the severity of the stenosis. Common treatment options include angioplasty, atherectomy, and stenting.

[0009] While existing IVUS catheters and existing pressure sensing catheters provide useful diagnostic information, there is a need for a combined pressure sensing and IVUS catheter that enables a healthcare provider to effectively perform diagnostic assessments for multiple modalities (e.g., imaging and pressure sensing) while only requiring the introduction of a single catheter into a patient. There is also a need for a combined pressure sensing and IVUS catheter that is integrated together in a manner that effectively and efficiently conserves required space or volume, such that the catheter is still sized small enough to access a small target area.

[0010] Therefore, there is a need for improved devices, systems and methods for providing a compact and efficient catheter having an ultrasound transducer for imaging or determining physical dimensions and a pressure sensor for measuring fluid pressure within a blood vessel.

[0011] The present disclosure addresses one or more of the shortcomings of the prior art. Summary of the invention

[0012] Embodiments of the present disclosure provide a compact and efficient circuit architecture and electrical interface for polymer piezoelectric micromachined ultrasound transducers used in intravascular ultrasound systems.

[0013] In one exemplary aspect, the present disclosure relates to an intravascular ultrasound (IVUS) device comprising: a flexible, elongated member having a proximal portion and a distal portion; a controller coupled to the distal portion of the flexible, elongated member; an ultrasonic transducer disposed at the distal portion of the flexible, elongated member and in communication with the controller; a pressure transducer disposed at the distal portion of the flexible, elongated member and in communication with the controller; and a plurality of conductors extending from the controller to the proximal portion of the catheter, at least one of the plurality of conductors being configured to carry a signal representing information captured by the ultrasonic transducer and information captured by the pressure transducer.

[0014] In one aspect, the ultrasonic transducer includes an ultrasonic transducer imaging element configured to rotate around the axis of the elongated member. In one aspect, the ultrasonic transducer includes a transducer array formed by a plurality of ultrasonic transducers. In one aspect, the plurality of conductors include a four-wire cable and the controller is configured to transmit signals based on information from an ultrasonic transducer and a pressure transducer located on the same conductor. In one aspect, the pressure transducer is connected to the controller via three wires. In one aspect, the distal portion of the four-wire cable is electrically connected to the controller. In one aspect, the proximal portion of the four-wire cable is connected to a connector, which is configured to connect the four-wire cable to a patient interface module (PIM). In one aspect, the controller is disposed adjacent to the ultrasonic transducer. In one aspect, the pressure transducer is disposed distal to the ultrasonic transducer. In one aspect, the flexible elongated member includes a guidewire lumen for receiving a guidewire.

[0015] In an exemplary aspect, the present disclosure relates to an intravascular ultrasound (IVUS) imaging and pressure sensing system including a catheter and a user interface. The catheter includes: a controller disposed at a distal portion of the catheter; an ultrasound transducer disposed at the distal portion of the catheter and in communication with the controller; a pressure transducer disposed at the distal portion of the catheter and in communication with the controller; and a plurality of conductors extending from the controller toward a proximal portion of the catheter, at least one of the plurality of conductors being configured to carry a signal representing information captured by the ultrasound transducer and information captured by the pressure transducer. The user interface communicates with the catheter and is configured to present information based on the signals carried by the plurality of conductors.

[0016] In one aspect, the ultrasonic transducer includes an ultrasonic transducer imaging element configured to rotate around the axis of the elongated member. In one aspect, the ultrasonic transducer includes a transducer array formed by a plurality of ultrasonic transducers. In one aspect, the cable is a four-wire cable and the controller is configured to transmit signals based on information from an ultrasonic transducer and a pressure transducer located on the same wire. In one aspect, the pressure transducer is connected to the controller via three wires. In one aspect, the distal portion of the four-wire cable is electrically connected to the controller. In one aspect, the proximal portion of the four-wire cable is connected to a connector configured to connect the four-wire cable to a patient interface module (PIM).

[0017] In an exemplary aspect, the present disclosure relates to a method for evaluating a patient, comprising: receiving information captured by an ultrasonic transducer disposed at a distal portion of a catheter; receiving information captured by a pressure transducer disposed at a distal portion of the catheter; generating a communication signal representing information from the ultrasonic transducer and from the pressure transducer at a controller carried on the catheter; and transmitting the communication signal representing information captured by the ultrasonic transducer and information captured by the pressure transducer from the controller carried on the catheter to a user interface.

[0018] In one aspect, receiving information captured by the ultrasonic transducer and receiving information captured by the pressure transducer are performed simultaneously. In one aspect, transmitting communication signals representing information captured by the ultrasonic transducer and information captured by the pressure transducer includes transmitting these signals in real time as they are received from the ultrasonic transducer and the pressure transducer. In one aspect, the generating includes converting an analog signal received from one of the pressure transducer and the ultrasonic transducer into a digital signal prior to transmitting.

[0019] Some embodiments of the present disclosure establish a circuit architecture that provides an electrical interface that requires a small number of electrical conductors for the desired signal amplification and efficient pulse generator circuits. In this regard, the small number of conductors enables the use of large diameter conductors within the limited space of the flexible, slender member, resulting in reduced cable attenuation and low electrical losses in the interconnecting cable extending along the length of the flexible, slender member. In addition, embodiments of the present disclosure provide good cable impedance matching. In this regard, the four-wire interface promotes a cable design that includes a pair of balanced transmission lines, each of which is properly terminated to minimize reflections and distortions of frequency responses that can cause artifacts or decay in the image. Alternatively, the four-wire interface promotes an alternative cable design (shielded twisted triplet) that includes a balanced transmission line that is properly terminated to minimize reflections and distortions of frequency responses that can cause artifacts or decay in the image, while the high voltage DC and ground signals are carried by unbalanced conductor pairs, where impedance matching and balance are not important.

[0020] In addition, embodiments of the present disclosure also provide low signal coupling. For example, the four-wire cable can be operated in a "starquad" configuration with diagonal conductor pairs forming independent transmission lines. In this configuration, the coupling between the diagonal signal pairs, each operating in differential mode, is minimized by the symmetry of the coupling to provide low crosstalk between multiple signals carried by the cable. In addition, a shielded twisted triplex cable can be operated in a configuration in which two of the three twisted conductors form a balanced transmission line, while the third twisted conductor and the shield carry high voltage direct current and ground signals. In this configuration, the coupling between the balanced signal pairs operating in differential mode and the other conductors is minimized by symmetry.

[0021] In addition, embodiments of the present disclosure provide low electromagnetic interference (EMI). In this regard, the four-wire interface promotes a cable design that includes a pair of balanced transmission lines. The balanced design suppresses the radiation of EMI and reduces the sensitivity of the system to external interference from other devices. The four-wire interface cable is in some cases sheathed with an electrically shielded conductor to further suppress EMI and sensitivity to external interference. In addition, the four-wire interface promotes a cable design that includes a shielded twisted triplet, and the shielded calibration triplet includes a balanced signal pair and an unbalanced pair. The balanced design suppresses the radiation of EMI and reduces the sensitivity to external interference from other devices, while the unbalanced pair only carries low-frequency signals that are not prone to EMI. The shielded twisted triplet cable includes an electrically shielded conductor to further suppress EMI and sensitivity to external interference.

[0022] Embodiments of the present disclosure also provide design flexibility, small integrated circuit die sizes suitable for use in intravascular catheters and / or guidewires, low power consumption, high transmission voltages, and efficient protection circuits. For example, the use of a serial communication scheme makes it feasible to add flexibility and improved features to the circuit design without complicating the four-wire physical interface between the PIM and the transducer. The circuit described herein is implemented in a compact application-specific integrated circuit (ASIC or controller as used herein) and the four-wire electrical interface consumes only a small portion of the device area, so that in some embodiments, the system can be implemented in catheters and guidewires with an outer diameter as small as 0.020 inches (0.5 mm). The embodiments of the circuits described herein are designed to minimize power dissipation to avoid excessive temperature rise at the distal end of the catheter. In addition, the embodiments of the circuits described herein include a high-voltage pulse generator at the distal end of the catheter, which avoids significant cable losses associated with the PIM-based pulse generator circuit. The method also reduces EMI that can be generated by otherwise sending high-voltage transmit pulses through a cable that extends along the length of the device to connect the PIM to the transducer. In addition, embodiments of the circuits described herein implement a highly efficient protection circuit that uses actively controlled analog switches to isolate sensitive amplifier inputs from high voltage transmit pulses applied to the transducer. The analog switch-based protection circuit design is facilitated by the proximity between the transmitter, amplifier, protection, and timing circuits all integrated into a single controller.

[0023] Additional aspects, features, and advantages of the present disclosure will become apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Illustrative embodiments of the present invention will be described with reference to the accompanying drawings, in which:

[0025] Figure 1 is a schematic diagram of an imaging system according to an embodiment of the present disclosure.

[0026] Figure 2 is a schematic perspective view, partially cut away, of an imaging device according to an embodiment of the present disclosure.

[0027] Figure 3 yes Figure 2 A schematic cross-sectional side view of a distal portion of an imaging device.

[0028] Figure 4 According to an embodiment of the present invention Figure 3 0 is a simplified side view of the components of the distal portion of the imaging device shown in , including micro-electromechanical system (MEMS) components and controller components.

[0029] Figure 5 yes Figure 4A simplified bottom view of the controller components of the components shown in FIG.

[0030] Figure 6 yes Figure 4 A simplified top view of the MEMS components of the components shown in FIG.

[0031] Figure 7 is a simplified cross-sectional side view of a distal portion of an imaging device according to another embodiment of the present disclosure.

[0032] Figure 8 is a schematic diagram of a distal portion of an imaging device arranged in a flat configuration according to another embodiment of the present disclosure.

[0033] Fig. 9 is a schematic diagram of a distal portion of an imaging device arranged in a flat configuration according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0034] In order to promote the understanding of the principles of the present disclosure, it will now be described with reference to the embodiments shown in the accompanying drawings, and specific language will be used to describe these embodiments. However, it will be understood that it is not intended to limit the scope of the present disclosure. Any changes and further modifications made to the described devices, systems and methods and any other applications of the principles of the present disclosure are fully contemplated and included in the present disclosure, as would normally be expected by a person skilled in the art to which the present disclosure belongs. In particular, it is fully contemplated that the features, components and / or steps described in conjunction with one embodiment may be combined with the features, components and / or steps described in conjunction with other embodiments of the present disclosure. However, for the sake of simplicity, multiple iterations of these combinations will not be described separately.

[0035] The systems, devices and methods disclosed herein relate to a system capable of performing imaging using an ultrasound transducer and pressure sensing using a pressure transducer. As described herein, the ultrasound transducer and the pressure transducer share a common conventional cable and other electronic components. With fewer components extending the length of the catheter, the overall diameter of the catheter can be smaller than would otherwise be achieved. In addition, some manufacturing steps can be eliminated when compared to manufacturing using distinct IVUS imaging and pressure transducers.

[0036] refer to Figure 1, which shows an IVUS imaging and pressure sensing system 100 according to an embodiment of the present disclosure. In some embodiments of the present disclosure, the IVUS imaging and pressure sensing system 100 is a piezoelectric micromachined ultrasonic transducer (PMUT) rotatable IVUS imaging and pressure sensing system. In this regard, the main components of the IVUS imaging and pressure sensing system 100 are an IVUS and pressure sensing catheter 102, a PMUT catheter-compatible patient interface module (PIM) 104, an IVUS and pressure console or processing system 106, and a monitor 108 for displaying the IVUS image and any pressure information or data generated by the IVUS and pressure console 106.

[0037] At a high level, the IVUS and pressure sensing catheter 102 emits ultrasonic energy from an IVUS transducer located at the end of the catheter. The ultrasonic energy is reflected by the tissue structure surrounding the IVUS transducer and the echo signal from the tissue is received and amplified by the IVUS transducer. The IVUS and pressure sensing catheter 102 also detects data representing the pressure in the target area of ​​the patient using a pressure transducer located at the end of the device. While emitting ultrasonic energy and receiving echoes, or at intervals, the IVUS and pressure sensing catheter 102 obtains pressure readings within the target body area of ​​the patient, typically within the vascular system. As described herein, the IVUS transducer and pressure transducer share an ASIC controller and the same communication and power cables extending toward the proximal end of the IVUS and pressure sensing catheter.

[0038] The PIM 104 facilitates the communication of signals between the IVUS and pressure console 106 and the IVUS and pressure sensing catheter 102 to control the operation of the IVUS transducer and pressure transducer. Controlling the operation of the IVUS transducer includes generating control signals to configure the IVUS transducer and triggering the transmitter circuit and transmitting the echo signal captured by the IVUS transducer to the IVUS and pressure console 106. With respect to the echo signal, the PIM 104 transmits the received signal, and in some embodiments, performs preliminary signal processing before transmitting the signal to the console 106. In an example of such an embodiment, the PIM 104 performs amplification, filtering and / or aggregation of the data. In one embodiment, the PIM 104 also supplies high voltage direct current and low voltage direct current to support the operation of the circuits and pressure sensors within the IVUS transducer. At the same time, the PIM 104 transmits the pressure data received from the pressure transducer, and in some embodiments, performs preliminary signal processing before transmitting the pressure data to the console 106. In an example of such an embodiment, the PIM 104 performs amplification, filtering, and / or aggregation of the pressure data.

[0039] The IVUS and pressure console 106 receives echo data from the IVUS transducer and pressure data from the pressure transducer through the PIM 104, and processes the data to form an image of the tissue surrounding the IVUS transducer and assess the pressure in the target area. In some cases, the IVUS and pressure console 106 is configured to calculate a blood flow reserve fraction (FFR) based on the pressure measurements obtained. The console 106 can also display images and / or pressure information including FFR on a monitor 108.

[0040] FFR is a currently commonly used technique for assessing the severity of stenosis in a blood vessel, including lesions caused by ischemia. It is defined as the ratio of the maximum blood flow in the stenotic artery obtained distal to the lesion to the normal maximum flow. Therefore, in order to calculate FFR for a given stenosis, two blood pressure measurements are obtained: one measurement located distally or downstream of the stenosis and one measurement located proximally or upstream of the stenosis. FFR is a calculation of the ratio of the distal pressure measurement to the proximal pressure measurement. FFR provides an index of the severity of stenosis, which allows determination of whether the blockage limits blood flow in the vessel to the extent that treatment is required. The more restricted the stenosis is, the greater the pressure drop across the stenosis, and the lower the resulting FFR. FFR measurements can be used as a decision point for guiding treatment decisions. The normal value of FFR in a healthy vessel is 1.00, while values ​​below about 0.80 are generally considered to be significant and require treatment. Common treatment options include angioplasty, percutaneous atherectomy, and stenting.

[0041] As discussed in more detail below, the IVUS and pressure sensing catheter 102 includes a PMUT ultrasound transducer and its associated circuitry mounted near the distal end of the catheter, a four-conductor cable, and appropriate electrical connectors to support the rotatable interface. The IVUS and pressure sensing catheter 102 also detects data representing the pressure within the patient's target area using a pressure transducer located near the distal end of the catheter.

[0042] The PIM 104 generates the required sequence of transmission trigger signals and control waveforms to regulate the operation of the circuit and process the amplified echo signals received on the same conductor pair. The PIM 104 also supplies high voltage DC and low voltage DC to support the operation of the IVUS and pressure sensing catheter 102. An important feature of the PIM 104 is that it must deliver DC voltage to the PMUT circuit of the catheter 102 across the rotatable interface. This requirement largely excludes the option of a rotary transformer commonly used in traditional rotatable IVUS systems, because the transformer can only transmit AC signals from the primary side to the secondary side. Actual options for delivering DC across the rotating interface include the use of slip rings and / or the implementation of active spinner technology described in U.S. Patent Application Publication No. 2010 / 0234736, which is hereby incorporated by reference in its entirety.

[0043] Reference now Figure 2 , which is a perspective, simplified view of a partially cutaway view of a rotatable IVUS and pressure sensing catheter 102 according to one embodiment of the present disclosure. In this regard, Figure 2 Additional details regarding the structure of the IVUS and pressure sensing catheter 102 are shown. In some aspects, the catheter is similar to a conventional rotatable IVUS catheter, such as that available from Volcano Corporation and described in U.S. Pat. No. 8,104,479. catheter, or those disclosed in U.S. Pat. Nos. 5,243,988 and 5,546,948, each of which is hereby incorporated by reference in its entirety. In this regard, the IVUS and pressure sensing catheter 102 includes an imaging core 110 and an outer catheter / sheath assembly 112. The imaging core 110 includes an imaging core 110 that is coupled to the outer catheter / sheath assembly 112. Figure 1The rotatable interface 114 of the electromechanical connection of the PIM 104 is terminated at the flexible drive rod at the proximal end. The distal end of the flexible drive rod of the imaging core 110 is connected to the transducer housing 116 containing the PMUT and related circuits, which is described in more detail below. The catheter / sheath component 112 includes a hub 118 that supports the rotatable interface and provides a bearing surface and a fluid seal between the rotating element and the non-rotating element of the catheter assembly. The hub 118 includes a luer lock flush port 120, through which saline is sprayed to flush out air and fill the inner cavity of the sheath with an ultrasound-compatible fluid when the catheter is used. Saline or other similar flushing fluids are usually required because air does not easily conduct ultrasound. Saline also provides a biocompatible lubricant for the rotating drive rod. The socket 118 is coupled to a telescope 122 that includes embedded tubular elements and sliding fluid seals that allow the catheter / sheath assembly 112 to be lengthened or shortened to facilitate axial movement of the transducer housing within an acoustically transparent window 124 of the distal portion of the catheter 102. In some embodiments, the window 124 includes thin-walled plastic tubing made of a material that easily conducts ultrasound waves between the transducer and vascular tissue with minimal attenuation, reflection, or refraction. The proximal shaft 126 of the catheter / sheath assembly 112 bridges the section between the sleeve 122 and the window 124 and includes a material or composite material that provides a smooth lumen and optimal stiffness but does not need to conduct ultrasound waves.

[0044] Reference now Figure 3 , which shows a cross-sectional side view of the distal portion of the catheter 102 according to one embodiment of the present disclosure. In particular, Figure 3 Exploded views of various aspects of the distal portion of the imaging core 110 are shown. In the exemplary embodiment, the imaging core 110 is terminated at its distal tip by a housing 116 made of stainless steel and provided with a rounded nose 126 and an imaging notch 128 for an ultrasound beam 130 to emerge from the housing 116 and a pressure sensing notch 129 for a pressure transducer 131 to detect pressure within the target anatomy.

[0045] In some embodiments, the flexible drive rod 132 of the imaging core 110 comprises two or more layers of counter-wound stainless steel wire that are welded or otherwise secured to the housing 116 so that rotation of the flexible drive rod also imparts rotation on the housing 116. In the illustrated embodiment, the PMUT MEMS 138 comprises a spherically focused transducer 142 and carries an application specific integrated circuit (ASIC) 144, also referred to herein as a controller.

[0046] The controller 144 is electrically coupled to the PMUT MEMS 138 via two or more connectors. In this regard, in some embodiments of the present disclosure, the controller 144 includes an amplifier, a transmitter, and a protection circuit associated with the PMUT MEMS. In some embodiments, the controller 144 is a flip-chip mounted to the substrate of the PMUT MEMS 138 using an anisotropic conductive adhesive or a suitable alternative chip-to-chip bonding method. When assembled together, the PMUT MEMS 138 and the controller 144 form a controller / MEMS hybrid assembly 146 mounted within the housing 116.

[0047] The cable 134 with optional shielding 136 is attached to the controller / MEMS hybrid assembly 146 using solder 140. The cable 134 extends through the lumen of the flexible drive rod 132 to the proximal end of the imaging core 110 where it is terminated at Figure 2 The electrical connector portion of the rotatable interface 114 is shown in FIG.

[0048] Embodiments of the present disclosure identify a four-wire electrical interface that provides a number of benefits with a four-wire electrical cross section that has minimal detriment to the performance of the circuitry and transducer while maintaining a small cable size that can be easily accommodated by a rotatable IVUS catheter. One implementation of this arrangement for the cable uses four electrical conductors that are twisted together into a symmetrical four-core cable and processed into two diagonal conductor pairs. In fact, the twisted four-core cable occupies only a slightly larger cylindrical space (20% larger diameter) than a twisted pair consisting of conductors of the same size.

[0049] In this twisted quad cable embodiment, one diagonal conductor pair provides a balanced transmission line that serves multiple purposes: (1) conducts balanced signals (e.g., data or information signals from the IVUS transducer and pressure transducer) from the controller amplifier to the PIM amplifier input, (2) carries a transmit trigger pulse as a balanced differential signal from the PIM transmit trigger circuit included on the controller to the transmitter and timing circuits included on the controller, (3) supplies low voltage DC power as a common mode voltage on the conductor pair (referred to as the ground conductor of the second pair), (4) provides receiver timing signals to turn amplifier circuits on and off as needed to minimize power consumption in the controller, and (5) forms a serial communication channel to support enhanced features (e.g., programmability). The second diagonal conductor pair carries the high voltage supply and ground. In addition to simply providing those DC voltages, the high voltage / ground pair also contributes to significant distributed capacitance that stores energy to be used by the pulse generator circuit when it delivers high power transmit pulses to the transducers. In effect, when the transmitter is triggered to generate a high power pulse to the transducer, it also transmits a traveling wave as a balanced signal onto the high voltage / ground conductor pair. When the traveling wave reaches the PIM, the PIM supplies the charge required to replenish what has been taken from the conductor pair by the transmit pulse. The cable construction provides all the required functions using a four-wire interface, all signals of which are transmitted on balanced lines, each of which is terminated with a suitable characteristic impedance. The balanced, terminated transmission lines provide reduced EMI generation and sensitivity to EMI, low distortion of the transmission waveform, high-speed communication, minimal distortion of the amplifier frequency response, and other electrical advantages. In some embodiments, the cable includes an optional shielding around the twisted four-core wire to further protect the signal line from EMI, to reduce electromagnetic interference emanating from the signal line, and to provide additional mechanical integrity.

[0050] An alternative cable design according to the present disclosure that provides many of the same advantages previously described in conjunction with the twisted quad construction is a shielded twisted triple. In this case, the two conductors of the twisted triple provide multiple functions previously described for the first pair of conductors of the twisted quad. The ground conductor serves as a shield, while the high voltage is carried by the third conductor of the twisted triple. Since the shield is symmetrical about the conductors of the twisted triple, there is a minimum differential interference signal coupled from the shield to the balanced signal line carrying the amplifier output. Likewise, due to symmetry, there is a minimum coupling on the high voltage conductor that interferes with the balanced signal line. In addition, there is usually very little high frequency noise on the high voltage signal line, except for the short transient sound during and immediately after the transmit pulse. Most of the high frequency transient sound will have dissipated when the earliest echo signal of interest returns from the vascular tissue. The shielded twisted triple is a highly manufacturable construction that forms an inherently stable and symmetrical bundle, and the shield provides mechanical integrity and protection from external interference to the cable.

[0051] In the illustrated embodiment, the controller / MEMS hybrid assembly 146 is fixed in position relative to the housing 116 by epoxy 148 or other adhesive. The epoxy 148 also serves as an acoustic substrate material to absorb acoustic reverberation propagating within the housing 116 and, in the case where it is welded to the controller / MEMS hybrid assembly 146, serves as a strain relief for the cable 134. The pressure transducer 131 is in electrical communication with the controller 144 via a wire 133 extending therebetween. The controller 144 provides power to the pressure transducer via the wire. Thus, the controller 144 disposed at the distal end of the catheter communicates with the PMUT MEMS 138 and the pressure transducer 131.

[0052] The pressure transducer 131 is mounted to measure the pressure outside the imaging core 110, and in a preferred embodiment, is a pressure sensor configured to sense the pressure within the vasculature of the patient being treated. The pressure transducer 131 is electrically connected to a controller 144 that can process, amplify, or condition the analog signal from the sensor and transmit a corresponding data signal to the proximal end of the catheter.

[0053] For this and other embodiments disclosed herein, the pressure transducer 131 may include a rigid housing 135 that at least partially surrounds and supports any type of pressure sensitive transducer. The housing 135 allows the sensor to be sufficiently pressure resistant to maintain functionality while embedded in or on the imaging core 110. For example, the pressure transducer 131 may include a capacitive sensor, a piezoresistive pressure transducer, a fiber optic pressure sensor such as those disclosed in U.S. Patent Nos. 8,298,156 and 8,485,985 and U.S. Patent Application Publication Nos. 2013 / 0303914 and 2013 / 0131523 (each of which is hereby incorporated by reference in its entirety), a sensor with a silicon backbone, or any other type of pressure sensor with the necessary durability and pressure resistance. In some cases, the pressure transducer 131 includes an array of sensor elements or a plurality of sensor elements (e.g., a capacitive pressure sensor array). In some embodiments, the pressure transducer 131 includes a sensor diaphragm assembly. In some embodiments, the sensor diaphragm assembly includes a body having a groove covered by a flexible diaphragm, which is configured to measure fluid pressure. The diaphragm can bend in response to changes in pressure around the diaphragm, thereby reflecting changes in blood pressure, for example. The pressure transducer 131 can then measure and transmit changes in pressure applied to the diaphragm assembly.

[0054] The sheath 112 includes an open end or hole that enables the pressure inside the sheath to be substantially equal to the pressure outside the sheath. Thus, the pressure measured in the sheath by the pressure transducer 131 is representative of the pressure outside the sheath.

[0055] Reference now Figure 4-6 , which shows additional aspects of the PMUT MEMS component 138 and the controller 144 that form the controller / MEMS hybrid assembly 146. In addition, Figure 6 A pressure transducer 131 is shown attached to the controller 144 via three wires 133 connected to bond pads 182 , 184 , and 186 . Figure 4-6The MEMS component 138 in the embodiment of the embodiment is a paddle-shaped silicon component, wherein the piezoelectric polymer transducer 142 is located in a widened portion 149 of a substrate located at the distal end of the MEMS component 138. The narrow portion of the substrate located proximal to the widened portion 149 is where the controller 144 is mounted to the MEMS component 138. In this regard, the MEMS component 138 includes ten bonding pads, and the bonding pads 150, 151, 152, 154, 156 and 158 of the MEMS 138 are configured to mate with the six bonding pads 172, 170, 180, 178, 176 and 174 on the controller 144, respectively, when the controller is flip-chip mounted on the MEMS 138 (e.g., Figure 6 ). The flip-chip mounting is accomplished using an anisotropic conductive adhesive, gold-gold thermosonic welding, and / or other suitable methods. Since the copolymer transducer elements are susceptible to debonding at temperatures as low as 100°C, which is well below conventional soldering temperatures, solder reflow is in some cases inconvenient for this application. Anisotropic conductive adhesives can be cured at temperatures below 100°C, as long as the curing time is extended to account for the low curing temperature. In this embodiment, bonding pads 152, 154, 156, and 158 are coupled to bonding pads 162, 164, 166, and 168 via conductive traces included on the MEMS substrate, and bonding pads 162, 164, 166, and 168 serve as terminals for the four conductors of cable 134, as shown. Figure 3 . In this regard, the four conductors of the cable 134 are welded or otherwise fixedly attached to the bonding pads 162, 164, 166 and 168, and the bonding pads 162, 164, 166 and 168 are electrically connected to the bonding pads 152, 154, 156 and 158. In other embodiments, the four conductors of the cable 134 are directly welded or otherwise fixedly attached to the controller bonding pads 174, 176, 178 and 180. The controller also includes three bonding pads 182, 184 and 186 that can be connected to the pressure transducer 131. The conductive wires extend from the bonding pads 182, 184 and 186 to the associated bonding pads provided on the pressure transducer 131.

[0056] Reference now Figure 7, which shows a cross-sectional side view of a distal portion of a portion of an imaging core 200 according to another embodiment of the present disclosure. The imaging core 200 may be similar to the imaging core 110 of the catheter 102 described above. In this regard, the imaging core 200 includes features and functions similar to those discussed above in conjunction with the imaging core 110. Therefore, the same reference numerals have been used to refer to similar features. For example, the imaging core 200 includes a MEMS 138 having a transducer 142 (e.g., an IVUS transducer) formed thereon and a controller 144 electrically coupled to the MEMS 138. However, in Figure 7 In an exemplary configuration of FIG. 1 , the controller 144 and MEMS 138 components are wire bonded together, mounted to the transducer housing 116, and secured in place using epoxy 148 or other adhesive to form a controller / MEMS hybrid assembly 146. In this embodiment, the wires of the cable 134 are directly welded or otherwise electrically coupled to the controller 144. The controller 144 includes wires 133 extending to the pressure transducer 131. In some embodiments of this configuration, the MEMS component 138 is Figure 4 and Figure 5 , with the narrow "handle" portion of the paddle removed. One advantage of the wire bonding approach is that the MEMS component carrying the transducer 142 can be mounted at an oblique angle relative to the longitudinal axis of the housing 116 and the imaging core 200 so that the ultrasound beam 130 propagates at an oblique angle relative to a line perpendicular to the central longitudinal axis of the imaging core. This tilt angle helps to reduce sheath echoes that may reverberate in the space between the transducer and the catheter sheath 112, and it also facilitates Doppler color flow imaging, as disclosed in U.S. Provisional Patent Application No. 61 / 646,080, entitled "DEVICE AND SYSTEM FOR IMAGING AND BLOOD FLOW VELOCITY MEASUREMENT," and U.S. Patent Application No. 61 / 646,074, entitled "ULTRASOUND CATHETER FOR IMAGING AND BLOOD FLOW MESUREMENT IN A VESSEL," each of which is hereby incorporated by reference in its entirety.

[0057] Figure 8 Another exemplary embodiment of a portion of an IVUS array and pressure sensing catheter 600 is shown. The portion shown may be used at the distal end of an imaging and pressure sensing catheter as described herein. Figure 8An ultrasound scanner assembly 601 in flat form is depicted. When placed on a catheter, the assembly 601 is rolled into a cylindrical shape. The assembly 601 includes a transducer array 602, a transducer control circuit 604 (including controllers 604a and 604b), and a pressure sensor 605 attached to a flexible circuit 606. The control circuit corresponds to the controller described above.

[0058] The transducer array 602 includes a plurality of ultrasound transducers 603 and replaces the single IVUS transducer described in other embodiments. The transducer array 602 may include any number and type of ultrasound transducers 603, although for clarity, only one is shown in FIG. Figure 8 A limited number of ultrasonic transducers are shown in FIG. 6 . In one embodiment, the transducer array 602 includes 64 individual ultrasonic transducers 603. In another embodiment, the transducer array 602 includes 32 ultrasonic transducers. Other numbers are contemplated and prepared. In one embodiment, the ultrasonic transducers 603 of the transducer array 602 are piezoelectric micromachined ultrasonic transducers (PMUTs) fabricated on a microelectromechanical system (MEMS) substrate using polymer piezoelectric materials, such as the transducers disclosed in U.S. Patent No. 6,641,540, which is hereby incorporated by reference in its entirety. In alternative embodiments, the transducer array includes piezoelectric zirconate transducers (PZT) transducers, such as bulk PZT transducers, capacitive micromachined ultrasonic transducers (cMUTs), single crystal piezoelectric materials, other suitable ultrasonic transmitters and receivers, and / or combinations thereof.

[0059] In some embodiments, the transducer array 602 forms part of a piezoelectric zirconate transducer (PZT) solid-state IVUS imaging device. In some embodiments, the catheter 600 incorporates a capacitive micromachined ultrasound transducer (CMUT) and / or a piezoelectric micromachined ultrasound transducer (PMUT). The IVUS imaging and pressure detection catheter 600 can be connected to a patient interface module (PIM) 104, an IVUS and pressure console or processing system 106, and / or a monitor 108 ( Figure 1 ) is associated with.

[0060] In the illustrated embodiment, the assembly 601 having 64 ultrasonic transducers 603 and at least one pressure sensor 605 includes nine sensor control circuits 604, five of which are shown. Designs incorporating other numbers of transducer control circuits 604, including 8, 9, 16, 17 and more, are utilized in other embodiments. In some embodiments, a single controller is designated as a master controller and is configured to receive signals directly from the cable 134. The remaining controllers are slave controllers. In the depicted embodiment, the master controller 604a does not directly control any IVUS transducer 603, but drives the pressure transducer 605. In other embodiments, the master controller 604a drives the same number of IVUS transducers 603 as the slave controller 604b while driving the pressure transducer 605, or drives a reduced set of transducers 603 compared to the slave controller 604b. In the illustrated embodiment, a single master controller 604a and 8 slave controllers 604b are provided. Each slave controller 604b is assigned 8 transducers. Based on the number of transducers that can be driven, such a controller may be referred to as an 8-channel controller.

[0061] The master controller 604a generates control signals for the slave controller 604b based on the configuration data and the transmit trigger received via the cable 134, and generates control signals for the pressure transducer 601. The master controller 604a also receives echo data from the slave controller 604b and from the pressure transducer 601 and retransmits it on the cable 134. To this end, in some embodiments, the master controller 604a includes an echo amplifier (not shown). In this configuration, the master controller 604a receives unamplified or partially amplified echo data and applies the required amplification for driving the echo data along the conductor of the cable 134. This can provide additional space for a larger high-fidelity amplifier.

[0062] In one embodiment, the flexible circuit 606 provides structural support and physically connects the transducer control circuit 604 to the transducers 603 and 605. In one embodiment, the flexible circuit 606 also includes a conductive trace 610 formed on the film layer. The conductive trace 610 carries signals between the transducer control circuit 604 and the transducer 603 or 605 and provides a set of pads for connecting the conductors of the cable 134. Suitable materials for the conductive trace 610 include copper, gold, aluminum, silver, tantalum, nickel and tin and can be deposited on the flexible circuit 606 by processes such as sputtering, plating and etching. In one embodiment, the flexible circuit 606 includes a chrome bonding layer. The width and thickness of the conductive trace are selected to provide suitable conductivity and elasticity when the flexible circuit 606 is rolled up. In this regard, an exemplary range of the thickness of the conductive trace 610 is between 10-50 μm. For example, in one embodiment, 20 μm conductive traces 610 are spaced apart by 20 μm. The width of conductive trace 610 may be further determined by the size of the pad of the device or the width of the wire to be connected to the trace.Additional details of flexible circuits may be found in U.S. Patent Application No. 61 / 746,804 filed on December 28, 2012, which is incorporated herein by reference.

[0063] The pressure sensor 601 is disposed in the distal portion on the catheter 600 and is disposed at or beyond the top edge of the flexible circuit 606 so as not to interfere with the operation of the IVUS transducer 603. In this example, the pressure transducer 601 is under the control of the main control circuit 604a. Conductive traces similar to the other conductive traces described herein extend from the main control circuit 604a to the pressure transducer 601. Data or information obtained by the pressure transducer 601 can be transmitted to the control circuit 604a, can receive some degree of processing, amplification or other processing at the control circuit 604a, and can then be transmitted as a signal related to the information from the IVUS transducer 603 on the same electrical conductor of the communication cable 134. In one aspect, the control circuit 604a can digitize one or more of the IVUS or pressure sensor signals before transmission.

[0064] Fig. 9 An exemplary catheter as used herein is shown on a monorail pressure sensing catheter 700, wherein the catheter 700 includes a controller 144, an ultrasound transducer array 142, and a pressure sensor 131, the pressure sensor 131 being disposed on or around the catheter, and the catheter 700 being advanced over a guidewire 702 toward a target area of ​​a patient.

[0065] An exemplary method of using the device disclosed herein is inferred from all of the teachings herein as will be apparent to one skilled in the art and explicitly disclosed in the following paragraphs. The catheter is advanced through a vasculature within a patient's body toward a target area or region of interest. This may be a target area that forms part of the patient's vascular system, but may also be other parts of the patient's body. In some embodiments, the catheter is advanced over a guide wire (e.g., Fig. 9 The guide wire 702 in the apparatus is advanced.

[0066] When the catheter is in the target area, the IVUS transducer and pressure transducer sensor can be actuated to obtain information related to the target area. In some embodiments, this can be used to obtain information related to stenosis in the vessel. The IVUS transducer can be used to image the target area of ​​the patient, and the pressure sensor can be used to measure the pressure in the vessel. This can occur simultaneously or at separate moments depending on the arrangement of the system. Signals representing ultrasound imaging and pressure are transmitted from the transducer to a controller or ASIC. Pressure or flow information can be transmitted via the same cable, and can be transmitted from the controller to the PIM via the same conductor, and finally transmitted to the console 106, and the pressure or flow information can be presented to the clinician on the display 108. In some embodiments, information representing ultrasound imaging and pressure is transmitted from the controller to the PIM in real time. In other cases, the information is stored on the controller and then sent.

[0067] In the case of having an ultrasonic transducer and a pressure transducer on the same catheter, the systems, devices and methods herein can perform imaging and pressure sensing. In one example, the combined catheter can be used to perform IVUS withdrawal to image the vessel, and can be used to sense the pressure in the vessel during withdrawal or at a separated time interval. Therefore, using a single catheter, medical personnel may be able to receive more information related to the patient's condition than the information that can be obtained in other ways. In addition, since the signals from the ultrasonic transducer and the pressure transducer are transmitted along the catheter using shared conductors and other electrical components (such as the same conductor in the communication cable 134), the catheter can be maintained in a small and effective size for evaluating even small vessels of the vascular system. Due to the additional information that can be obtained from a single catheter, medical personnel can more effectively evaluate patients. In some cases, this shortening of the evaluation time can also lead to a shortening of the actual treatment time, reducing the cost of the patient. In addition, due to the shared components, the overall diameter of the catheter can be less than the overall diameter that can be obtained in other ways. In addition, when compared with the use of distinct IVUS imaging and pressure transducer manufacturing, some manufacturing steps can be removed.

[0068] It will be appreciated by those skilled in the art that the above-described apparatus, systems, and methods may be modified in a variety of ways. Therefore, it will be appreciated by those skilled in the art that the embodiments encompassed by the present disclosure are not limited to the specific exemplary embodiments described above. In this regard, although illustrative embodiments have been shown and described, various modifications, changes, and substitutions are contemplated in the foregoing disclosure. It is understood that such changes may be made to the foregoing without departing from the scope of the present disclosure. Therefore, it is understood that the appended claims should be interpreted broadly and in a manner consistent with the present disclosure.

Claims

1. An intravascular ultrasound device, comprising: a flexible, elongated member having a proximal portion and a distal portion configured to be disposed in a vasculature of a patient; as well as an ultrasound scanner assembly rolled into a cylindrical shape and disposed on the distal portion of the flexible elongated member, the ultrasound scanner assembly comprising: a substrate coupled to the distal portion of the flexible elongated member and comprising a plurality of conductive traces; a controller mounted on the substrate; an ultrasonic transducer array mounted on the substrate and in communication with the controller, the ultrasonic transducer array comprising a plurality of ultrasonic transducers; a pressure sensor mounted on the substrate distal to the ultrasonic transducer array, the pressure sensor communicating with the controller via the plurality of conductive traces, a portion of each of the plurality of conductive traces being disposed between two ultrasonic transducers of the plurality of ultrasonic transducers; and A plurality of conductors extend from the distal portion of the flexible, slender member to the proximal portion of the flexible, slender member, the distal ends of the plurality of conductors being connected to electrical contacts located on the proximal region of the substrate, the ultrasound transducer array and the pressure sensor both being in electrical communication with the plurality of conductors, such that the plurality of conductors are configured to carry signals representing information captured by the ultrasound transducer array and information captured by the pressure sensor.

2. The device according to claim 1, wherein: The controller is configured to transmit signals based on information from the ultrasound transducer array and the pressure sensors located on the plurality of conductors.

3. The device according to claim 2, wherein: The plurality of conductive traces includes three wires, such that the pressure sensor is connected to the controller via the three wires.

4. The device according to claim 1, wherein: Proximal portions of the plurality of conductors are coupled to a connector configured to connect the plurality of conductors to a patient interface module.

5. The device according to claim 1, wherein: The controller is positioned adjacent to the ultrasound transducer array.

6. The device according to claim 1, wherein: The flexible elongate member includes a guidewire lumen for receiving a guidewire.

7. The device according to claim 1, wherein: Also included are a plurality of slave controllers coupled to the distal portion of the flexible elongated member and in communication with the controller, the ultrasonic transducer array communicating with the controller through the plurality of slave controllers, and the pressure sensor communicating directly with the controller.

8. The device according to claim 7, wherein: The controller is configured to directly control the operation of the pressure sensor and only indirectly control the operation of the ultrasound transducer array through the plurality of slave controllers.

9. The device according to claim 1, wherein: The substrate includes a flexible circuit, the pressure sensor is mounted to a distal end of the flexible circuit, and the plurality of conductive traces are formed in the flexible circuit.

10. The device according to claim 9, wherein: The flex circuit is disposed about the distal portion of the flexible, elongated member such that the ultrasound transducer array surrounds the distal portion of the flexible, elongated member.

11. The device according to claim 1, wherein: The pressure sensor includes a pressure transducer.

12. The device according to claim 1, wherein: The plurality of conductors includes only three conductors or only four conductors, all of the plurality of conductors are in a twisted configuration, the ultrasonic transducer array and the pressure sensor are in electrical communication with conductor pairs among the plurality of conductors, such that the conductor pairs are configured to carry signals representing information captured by the ultrasonic transducer array and information captured by the pressure sensor.

13. An intravascular ultrasound imaging and pressure sensing system, comprising: The intravascular ultrasound device according to any one of claims 1 to 12; as well as A user interface is in communication with the intravascular ultrasound device and is configured to present information based on the signals carried by the plurality of conductors.

14. The system according to claim 13, wherein: The system also includes a patient interface module, wherein proximal portions of the plurality of conductors are coupled to a connector configured to connect the plurality of conductors to the patient interface module.

15. A method for evaluating a patient using the intravascular ultrasound device of claim 1, comprising: receiving information captured by an ultrasound transducer array mounted on a substrate, the ultrasound transducer array comprising a plurality of ultrasound transducers, the substrate being coupled to a distal portion of a catheter positioned in a patient's vasculature and comprising a plurality of conductive traces; receiving information captured by a pressure sensor mounted on the substrate distal to the ultrasound transducer array; generating, at a controller mounted on the substrate, signals representing information from the array of ultrasonic transducers and from the pressure sensor, the pressure sensor communicating with the controller via the plurality of conductive traces, a portion of each of the plurality of conductive traces being disposed between two ultrasonic transducers of the plurality of ultrasonic transducers; Communication signals representing information captured by the ultrasound transducer array and information captured by the pressure sensor are transmitted from the controller carried on the catheter to a user interface via a plurality of conductors extending from the controller to a proximal portion of the catheter, the distal ends of the plurality of conductors being connected to electrical contacts located on a proximal region of the substrate.

16. The method according to claim 15, wherein: Receiving information captured by the ultrasound transducer array and receiving information captured by the pressure sensor are performed simultaneously.

17. The method according to claim 15, wherein: Transmitting communication signals representing information captured by the ultrasound transducer array and information captured by the pressure sensor includes transmitting signals in real time as the information captured by the ultrasound transducer array and information captured by the pressure sensor are received from the ultrasound transducer array and the pressure sensor.

18. The method according to claim 15, wherein: Generating a signal representing information from the ultrasound transducer array and from the pressure sensor includes converting an analog signal received from one of the pressure sensor and the ultrasound transducer array into a digital signal prior to transmission.

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