CN116568366A - Adjustable shunt with resonant circuit and associated systems and methods - Google Patents

Abstract

The present technology generally relates to shunt systems having shape memory actuated elements capable of selectively changing the geometry of the shunt element to affect the flow of fluid therethrough. In some embodiments, these shape memory actuation elements are incorporated as part of an on-board resonant circuit. Activating the resonant circuit causes current to flow through the shape memory actuation element, thereby resistively heating the shape memory actuation element.

Description

Adjustable shunt with resonant circuit and associated systems and methods

Cross References to Related Applications

This application claims the benefit of U.S. Provisional Application No. 63/088,832, filed October 7, 2020, and U.S. Provisional Application No. 63/089,391, filed October 8, 2020, both of which are incorporated herein by reference in their entirety.

technical field

The present technology relates generally to implantable medical devices, and in particular to implantable shunt systems and associated methods for selectively controlling fluid flow between a first body region and a second body region.

Background technique

Implantable medical devices that can be selectively activated or otherwise actuated typically require some sort of power management system. Power management systems can be used for several types of operations. For example, a power management system may be used to operate electronic components on the device (eg, microcontrollers, sensors, etc.), and may also be used to drive activation or actuation of various aspects of the device. To this end, some medical devices include energy storage components (eg, batteries, capacitors, supercapacitors, etc.) integral with or operatively coupled to the device. Each energy storage component is associated with different properties (eg, capacity, energy density, power density, discharge rate, impedance, etc.), and thus different components may be best suited for different types of operations.

The implanted device may also include onboard electronics for wirelessly receiving energy and charging or recharging the energy storage device. For example, FIG. 1 is a schematic diagram of a conventional circuit 100 for recharging an energy storage device (capacitor C2 in the illustrated embodiment), which may be used to power an actively powered actuator 106 . Circuit 100 may include a rectifying resonant RLC circuit that generates energy in response to exposure to a magnetic and/or electric field. At least some of the energy generated in the resonant RLC circuit is directed to and stored in capacitor C2. The stored energy may then be released in a controlled manner to power the actuator 106 . For example, circuit 100 may include a switched-mode power supply circuit that may control parameters of energy released via capacitor C2 to maintain precise control of power delivered to actuator 106 . However, such conventional circuits suffer from several disadvantages. For example, the actuator 106 cannot be directly activated by an external energy source, necessitating the use of one or more energy storage devices and increasing the cost, size and complexity of the device. Furthermore, the amount of power available to drive the actuator 106 is limited by the storage capacity of the energy storage device, which is generally proportional to the size of the energy storage device. Additionally, the discharge rate and discharge time characteristics of the energy storage device may not allow practical utilization of the full energy storage capacity (e.g., when used in an environment, such as a fluid environment, where the The converted energy is quickly transferred to the surrounding medium), thereby further increasing the size of the energy storage device required to successfully drive the actuator 106.

While the foregoing shortcomings illustrate the desire to integrate larger energy storage devices, the size of the energy storage device may be limited by the target anatomical location of the implanted device and/or the procedure used to implant the implanted device. Consequently, the storage capacity and/or discharge characteristics of available energy storage devices are often sub-optimal. As a result, actuators in implantable medical devices typically cannot be driven using methods similar to the circuit in FIG. 1 , or such methods require the use of suboptimal (eg, low quality) actuators to be successful. Accordingly, there is a need for improved power management systems in actively powered medical devices.

Description of drawings

Figure 1 is a schematic diagram of a circuit for charging an implanted energy storage device.

2 is a schematic illustration of an interatrial device implanted within a heart and configured in accordance with a selected embodiment of the present technology.

3 is a schematic illustration of an adjustable interatrial shunt system configured in accordance with an alternative embodiment of the present technology.

4 is a schematic diagram of an electrical circuit incorporating an actuation element and configured in accordance with selected embodiments of the present technology.

5 is a flowchart of a method for deploying an adjustable shunt system in accordance with an embodiment of the present technology.

Detailed ways

The present technology generally relates to adjustable shunt systems having shape memory actuated elements capable of selectively changing the geometry of the shunt elements to affect the flow of fluid therethrough. In some embodiments, shape memory actuation elements are incorporated directly into the on-board resonant circuit. Activation of the resonant circuit (eg, by externally applied energy, such as an externally generated magnetic field) causes current to flow through the shape memory actuation element, thereby resistively heating the shape memory actuation element. Heating the shape-memory actuation element above its transition temperature can cause a change in the state of the material in the shape-memory actuation element, which can cause a change in geometry in the actuation element that can drive a corresponding geometry in the shunt element. Structural changes.

Terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is used in conjunction with a detailed description of certain specific embodiments of the technology. Certain terms may even be emphasized below; however, any terms that are intended to be interpreted in any limited manner will be disclosed and specifically defined in this detailed description. In addition, the technology may also include other embodiments within the scope of the examples but not described in detail with respect to FIGS. 2-4 .

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present technology. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features or characteristics may be combined in any suitable manner in one or more embodiments.

References throughout the specification to relative terms such as, for example, "generally", "approximately" and "about" are used herein to denote ±10% of the stated value.

As used herein, the terms "atrial device", "atrial shunt device", "IAD", "IASD", "atrial shunt" and "shunt" are used interchangeably to refer to a device in at least one configuration A device including a shunt element that provides blood flow between a first region (eg, the left atrium of the heart) and a second region (eg, the right atrium of the heart or the coronary sinus) of a patient. Although described in terms of a shunt between the atria (i.e., the left and right atria), it should be understood that the technology is equally applicable to devices positioned between other chambers and passages of the heart, or other components of the cardiovascular system. device between parts. For example, any of the shunts described herein (including those referred to as "atrial") can still be used and/or modified to connect between the left atrium ("LA") and the coronary sinus, or the right pulmonary vein and the superior vena cava Blood is shunted between veins. Furthermore, while the disclosure herein primarily describes shunting blood from the LA to the right atrium ("RA"), the present technique can be readily adapted to shunting blood from the RA to the LA to treat certain conditions, such as pulmonary hypertension. For example, a mirror image or in some cases the same embodiment of the embodiment used to shunt blood from LA to RA may be used to shunt blood from RA to LA in certain patients. Furthermore, while certain embodiments herein are described in the context of heart failure treatment, any of the embodiments herein, including those referred to as interatrial shunts, can still be used and/or modified to treat other conditions or conditions, including other diseases or conditions in other body areas. For example, the systems described herein can be used to treat diseases characterized by increased pressure and/or fluid accumulation, including but not limited to glaucoma, lung failure, kidney failure, cerebral edema, and the like.

The headings provided herein are for convenience only and do not interpret the scope or meaning of the claimed technology.

A. Atrial shunts used to treat heart failure

Heart failure ("HF") can be classified into one of at least two categories based on the ejection fraction that occurs in the patient: (1) heart failure with preserved ejection fraction ("HFpEF"), historically known as diastolic heart failure, Or (2) Heart Failure with Reduced Ejection Fraction ("HFrEF"), historically known as systolic heart failure. One definition of HFrEF is a left ventricular ejection fraction below 35%-40%. Although related, the underlying pathophysiology and treatment options for each heart failure classification can vary considerably. For example, while there are some established drug therapies that can help treat the symptoms of HFrEF, and sometimes slow or reverse the progression of the disease, available drug therapies with only questionable efficacy for HFpEF are limited.

In heart failure patients, abnormal function in the left ventricle ("LV") leads to pressure buildup in the LA. This directly leads to higher pressure in the pulmonary venous system supplying the LA. Elevated pulmonary venous pressure pushes fluid out of the capillaries and into the lungs. This fluid buildup leads to lung congestion and many of the symptoms of heart failure, including shortness of breath and signs of exertion during even light physical activity. Risk factors for HF include renal dysfunction, hypertension, hyperlipidemia, diabetes, smoking, obesity, old age, and obstructive sleep apnea. HF patients may have increased LV stiffness, which leads to a decrease in left ventricular relaxation during diastole, resulting in increased pressure and inadequate filling of the ventricle. Patients with HF may also have an increased risk of atrial fibrillation and pulmonary hypertension, and often have other comorbidities that can complicate treatment options.

Atrial shunts have recently been proposed as a way to reduce elevated left atrial pressure, and this emerging class of cardiovascular therapeutic intervention has proven to have significant clinical promise. Figure 2 shows the placement of the shunt in the bulkhead between LA and RA. Most interatrial shunts (eg, shunt 10 ) involve forming a hole or inserting a lumen structure into the interatrial septum to create a fluid communication pathway between the LA and RA. Thus, elevated left atrial pressure may be partially relieved by unloading the LA into the RA. In early clinical trials, the approach has been shown to improve symptoms of heart failure.

One challenge with many conventional interatrial shunts is determining the most appropriate size and shape for the shunt lumen. A too small lumen may not adequately unload the LA and relieve symptoms; a too large lumen may overload RA and the right heart more generally, creating new problems for the patient. Furthermore, the relationship between decompression and clinical outcome, and the degree of decompression required to optimize outcome, remains incompletely understood, in part because the pathophysiology of HFpEF (and, to a lesser extent, HFrEF) is not fully understood. As a result, clinicians are forced to make best guesses (based on limited clinical evidence) in selecting an appropriately sized shunt, and often cannot adjust the size over time. In addition, clinicians must base their decisions on general factors (e.g., size of the patient's anatomy, patient's hemodynamic measurements taken at one snapshot, etc.) and/or the design of available devices rather than the health and expected response of the individual patient. Select the size of the shunt. With many such conventional devices, once the device is implanted, the clinician does not have the ability to adjust or determine therapy, eg, in response to changing patient conditions, such as the progression of a disease. In contrast, an interatrial shunt system configured in accordance with embodiments of the present technology allows a clinician to select a size during surgery or after implantation based on the patient's condition.

B. Adjustable shunt system

3 is a schematic diagram of an adjustable shunt system 300 ("system 300") configured in accordance with embodiments of the present technology. System 300 includes a shunt element 302 that defines a lumen 304 therethrough. When implanted across the septum S, system 300 may fluidly connect LA and RA via lumen 304 . Therefore, when the shunt element 302 is implanted in the septum, blood can flow from LA to RA via the lumen 304 (as indicated by arrow F). Diverter element 302 may include additional features not shown in FIG. 2, such as frames, anchors, membranes, and the like. For example, the shunt element 302 may include features such as those described in International Patent Application No. PCT/US2020/049996, the disclosure of which is incorporated by reference in its entirety.

System 300 may also include an actuation element 306 configured to selectively alter the geometry (size, shape, etc.) and/or other characteristics of flow diverting element 302 to selectively adjust fluid passage through lumen 304 flow. For example, actuation element 306 may be configured to selectively increase the diameter of lumen 304 (e.g., orifice diameter, hydraulic diameter, etc.) and/or selectively decrease the diameter of lumen 304 (e.g., , orifice diameter, hydraulic diameter, etc.). In other embodiments, the actuation element 306 is configured to affect the shape and/or geometry of the lumen 304 in other ways. Accordingly, the actuation element 306 may be coupled to the diverter element 302 and/or may be included within the diverter element 302 . In some embodiments, for example, actuation element 306 is part of shunt element 302 and at least partially defines lumen 304 . In other embodiments, the actuation element 306 is spaced apart from but operatively coupled to the diverter element 302 .

In some embodiments, at least a portion of the actuation element 306 includes a shape memory material, such as a shape memory metal or alloy (e.g., Nitinol, including Nitinol-based alloys), a shape memory polymer, or a pH-based shape memory material. Material. In embodiments where the actuation element is comprised of a shape memory material (which may be referred to herein as a "shape memory actuation element"), the shape memory actuation element may be configured to move in response to a stimulus (e.g., a thermal or mechanical load). Changing geometry (eg, transitioning between a first configuration and a second configuration). For example, in some embodiments, when the shape-memory actuation element is in a first material state (e.g., a martensitic material state or an R-phase material state), the shape-memory actuation element is relative to its preferred geometry (e.g., fabricated geometry, raw geometry, heat set geometry, etc.) deformation. When the deformed shape memory element is heated above its transition temperature (in some embodiments, the transition temperature is a temperature greater than body temperature), the shape memory actuated element transitions to a second material state (e.g., an R-phase material state or austenitic material state), which can cause the shape memory actuation element to move towards its preferred geometry. Movement of the actuation element from the deformed position toward its preferred geometry can adjust the geometry of the lumen 304, as described above. Additional aspects of adjusting interatrial shunts using shape memory actuation elements, including various adjustable interatrial shunts incorporating shape memory actuation elements, are described in International Application No. PCT/US2020/049996, previously incorporated by reference and into this article.

System 300 may also include an energy delivery device 322 for delivering energy (e.g., power) to implanted components of system 300 (e.g., actuation element 306 and/or implanted electronics 324 described below). ). Energy transmission device 322 may include any device or system external to the patient's body capable of wirelessly transmitting energy to an implanted component. For example, energy delivery device 322 may be configured to deliver radio frequency (RF) energy, microwave frequency energy, other forms of electromagnetic energy, ultrasonic energy, thermal energy, or other types of energy according to techniques known to those skilled in the art. In some embodiments, the energy delivery device 322 may deliver energy at a frequency in the range between about 1 MHz and about 1 GHz (eg, 1 MHz, 2 MHz, 3 MHz, 10 MHz, 100 MHz, 500 MHz, etc.), although other frequencies are possible. In some embodiments, an energy delivery device may generate an electric field and/or a magnetic field toward the implanted aspect of system 300 .

In some embodiments, energy delivery device 322 may include one or more devices configured to be at least temporarily positioned within a patient's body (eg, an energy delivery catheter configured to navigate access to system 300 during surgery). For example, the energy delivery device 322 can be advanced percutaneously until the transmitter coil on the distal end of the energy delivery device 322 is in proximity (e.g., within 5 cm, within 4 cm, within 3 cm, within 2 cm, within 1 cm, etc.) One or more implanted portions of system 300 , such as actuation element 306 . Once positioned proximate to actuation element 306 or another target component, energy delivery device 322 may generate an electromagnetic field for activating actuation element 306 . Notably, and similar to the electrical coupling achieved when using energy delivery device 322 positioned external to the patient, the energy delivery catheter need not be positioned in direct contact with any implanted portion of system 300 such as actuation element 306 . However, the use of an energy delivery catheter instead of or in addition to a non-invasive energy delivery device positioned outside the patient's body is expected to be useful in embodiments requiring greater amounts of energy because The coupling efficiency is desirably much higher (eg, at least about 100% higher, at least about 1000% higher, etc.) when using a transmitter positioned close to the target than when using a transmitter that remains outside the patient's body. A representative embodiment in which an invasive method using an energy delivery catheter is particularly useful is described in more detail below with reference to FIG. 5 .

System 300 may also include electronic components 324 implanted with shunt element 302 and electrically coupled together to form an electrical circuit (eg, RLC circuit, resonant circuit, etc.). Electronic components 324 may include, for example, conventional electronic components found in electrical circuits, such as resistors, capacitors, and inductors. In some embodiments, an inductor may be a coil of wire or other filament that can be coupled to an externally generated electromagnetic field. For example, in some embodiments, the inductor is a first wire coil (not shown) having a self-inductance L. The energy delivery device 322 may have a second wire coil (not shown) configured to remain external to the patient (or at least to remain spaced from the electronic components 324, such as positioned on an energy delivery catheter), and to A mutual inductance M is coupled to the first wire coil. The self-inductance L of the first wire coil acts as an inductor in the circuit, and the mutual inductance M of the first and second wire coils serves to transfer energy and/or power from an externally generated magnetic field to the first wire coil. In some embodiments, the self-inductance L can be between about 0.1 μH and about 10 μH, the ratio of the mutual inductance M to the self-inductance L (e.g., M/L) can be less than about 0.10, and the diameter of the first wire coil is the same as that of the second wire. The ratio of the diameters of the coils may be between about 0.01 and 1.0. In some embodiments, the first coil of wire may be one or more turns of shaped wire, a conductive pattern printed on a non-conductive single or multi-layer substrate, or another coil formed to surround the magnetic flux generated by the energy transfer device 322. Conductive structure to achieve.

As described in detail with respect to FIG. 3 , electrical circuits formed by electronic components 324 may receive energy and/or power from energy transfer device 322 . For example, in some embodiments, energy transfer device 322 generates an electromagnetic field, and electronic component 324 generates an electrical current in response to exposure to the electromagnetic field. The electrical current generated by the electronics 324 may flow through the actuation element 306 and provide power directly to the actuation element (eg, resistive heating of the actuation element). For example, as described in more detail with respect to FIG. 4 , actuation element 306 may be incorporated into an electrical circuit formed by electronic component 324 such that energy transfer device 322 may pass through actuation element 306 by generating a flow in the circuit and actuate it. The actuating element 306 is directly powered by the current for resistive heating of the actuating element.

4 is a circuit diagram of an exemplary circuit formed via electronic components 324 ( FIG. 3 ) and used to power actuation element 306 in accordance with an embodiment of the present technology. In particular, FIG. 4 illustrates a resonant circuit 400 configured to be powered via an energy transfer device 322 . Notably, the actuation element 306 can be incorporated directly into the resonant circuit 400 because the actuation element 306 can be powered by resistive heating and does not require a specific electrical waveform like many conventional actuators, including electric motors. For example, in the illustrated embodiment, actuation element 306 is coupled in series with other electronic components of resonant circuit 400 . In other embodiments, the actuation element 306 may be coupled in parallel with other electronic components of the resonant circuit 400, or in other suitable configurations. When resonant circuit 400 is energized (eg, via external energy transfer device 322 of FIG. 3 ), current flows through actuation element 306 , thereby resistively heating actuation element 306 . In embodiments where the actuation element 306 is composed of a shape memory material, this resistive heating can heat the shape memory actuation element above its transition temperature and drive a phase shift that causes a change in geometry in the lumen 304, as described above with respect to Figure 3 is described in detail.

The resonant circuit 400 can be characterized by a quality factor, Q, which is the ratio of the energy stored in the circuit to the energy dissipated per radian of resonant oscillation and is defined by the following formula:

In the above formula, f is equal to the resonant frequency, L is the inductance of the inductor, R1 is equal to the resistance of the actuation element 306, _RL is the resistance of the inductor, and R _C is the resistance of the capacitor. In some embodiments, _RL has a value between about 0.1 ohms and about 2 ohms, _RC has a value between about 0.01 ohms and 0.05 ohms, and R1 has a value between about 0.5 ohms and about 10 ohms , but values outside the foregoing ranges are possible and within the scope of the present technology.

Resonant circuit 400 may be designed to optimize or otherwise enhance the functionality of system 300 . For example, resonant circuit 400 may be designed with intentional "power loss", as opposed to conventional resonant circuits which generally attempt to maximize the quality factor Q by minimizing the power dissipated in the circuit. In particular, the actuation element 306 is designed to increase the power dissipated in the circuit (thereby reducing the quality factor Q) when current flows through the circuit, since the power dissipation drive caused by the current flowing through the actuation element 306 causes The temperature change that changes the geometry of the moving element 306. In some implementations, resonant circuit 400 may have a quality factor Q of less than about 100, such as between about 10 and about 100, for example. In contrast, conventional wireless power transfer circuits typically have a quality factor Q greater than 100. Power dissipation in the actuation element 306 is generally maximized when the resistance of the actuation element 306 is equal, or at least approximately equal, to R _L +R _C . Thus, in some embodiments, the resistance of actuation element 306 is equal or substantially equal to the sum of _RL and R _C such that the ratio of the resistance of actuation element 306 to the sum of the resistances of _RL and R _C is between 2.0 and 0.5 Between, such as, 2.0, 1.8, 1.6, 1.4, 1.2, 1.1, 1.0, 0.9, 0.8, 0.7, 0.6 or 0.5.

Resonant circuit 400 may also be designed such that actuation element 306 has a greater power dissipation density than other electronic components (eg, inductors, capacitors, etc.) when current flows through circuit 400 . For example, the other electronic components may (each) have a surface area greater than the surface area of the actuation element 306 . In some embodiments, this can be achieved by designing the other electronic components to have a longer length than the actuation element 306, although other configurations are possible (e.g., other electronic components can have a greater perimeter than the actuation element 306 ). Due to the relatively small surface area of the actuation element 306, the power dissipation density in the actuation element 306 is greater than in other electronic components. This advantageously causes the actuation element 306 to be heated to a greater extent than other electronic components when current flows through the circuit 400 .

As noted above, incorporating the actuation element 306 into the resonant circuit 400 generally provides additional resistance (and thus greater power dissipation) within the resonant circuit 400 . However, this additional resistance is usually low enough not to disturb the circuit resonance.

Incorporating actuation element 306 into resonant circuit 400 is expected to provide several advantages. For example, incorporating actuation element 306 into resonant circuit 400 enables direct heating of actuation element 306 using an energy delivery device (e.g., energy delivery device 322 of FIG. 2 ) external to the permanently implanted portion of system 300, and thus The actuating element is activated directly. In contrast, if the actuation element 306 were not incorporated into the resonant circuit 400, the system 300 would require an energy storage component (e.g., a supercapacitor that could receive and store energy from the resonant circuit) to selectively release energy to heat actuating element. Such energy storage elements having a size and/or shape suitable for implantation and/or delivery (e.g., percutaneous delivery via catheterization) into a patient's heart typically have limited energy storage capacity and/or discharge characteristics, This limits the ability to actuate the actuation element.

In contrast, by not relying on implanted energy storage components, the present technology is not limited by the energy storage capacity or other characteristics of the energy storage components, but instead relies on external energy transfer devices (which can have a relatively unlimited supply of energy) The actuation element 306 is directly activated. Accordingly, in some embodiments, it is desirable for the present technology to provide an adjustable shunt system that does not require (permanently) implanted energy storage components to actuate the actuation element. However, in some embodiments, adjustable shunt systems may still include implanted energy storage components for powering other aspects of the system (eg, sensors) and/or for augmenting the power provided by external energy delivery devices.

Another desirable advantage of incorporating the actuation element 306 into the resonant circuit 400 rather than relying on a separate energy storage component is that the system 300 does not generate direct current (DC) when the actuation element 306 is energized, even when energy is delivered continuously. ) (if utilizing an energy storage component such as a supercapacitor, a direct current would be generated). Without being bound by theory, this is expected to reduce/eliminate the risk of electric shock from such energy transfer.

Alternatively or additionally, the implantable devices and systems described herein may include a resonant antenna or cavity integral with the shape memory actuation element. In such embodiments, the resonant antenna or resonant cavity may be configured to operate at frequencies above about 100 MHz. In response to the antenna or resonant circuit in the cavity being powered, current may flow through and heat the shape memory actuation element, as described above. In other embodiments, the implantable devices and systems described herein may include piezoelectric acoustic resonators configured to receive energy from an externally positioned ultrasound source. Piezoacoustic resonators convert received energy into electrical current. The piezoacoustic resonator may also be operably coupled (eg, coupled in series) with the shape memory actuation element such that current flows through and resistively heats the shape memory actuation element.

As explained above, the present technique can be used to power the actuation element non-invasively (e.g., using an energy delivery device that remains external to the patient) or invasively (eg, using an energy delivery device that is advanced percutaneously toward an implanted device) Power is supplied to the actuating element. In some embodiments, the system is configured to enable a user (e.g., physician) to choose to non-invasively or invasively power the device based on a variety of factors, including the environment/setting in which the therapy occurs (e.g., , catheterization laboratory availability), energy requirements, timing requirements, patient factors (eg, risk factors), etc. Without being bound by theory, invasive powering an actuation element is expected to Provides a more efficient energy coupling between energy transfer devices (eg, about 10% to 30% desired energy coupling between transmitter and receiver). Of course, in some cases where activation requires a lower amount of overall energy transfer, it may be advantageous to power the actuation element non-invasively, since it is less complex/less invasive.

5 is a flowchart of a method 500 for deploying an adjustable shunt system having a shape memory actuation element and a shunt element (e.g., system 300, shunt element 302, and actuation element 306 of FIG. 3) in accordance with an embodiment of the present technology. picture. Method 500 may begin at step 502 by deploying a shunt system with shape memory actuated elements at a target location, such as across the septum of the heart. For example, step 502 may include percutaneously advancing a shunt delivery catheter carrying a shunt delivery catheter to a target site, deploying the shunt delivery catheter from the shunt delivery catheter, and withdrawing the shunt delivery catheter. In such embodiments, the shunt system is typically disposed within the catheter in a collapsed configuration prior to deployment. When deployed from the catheter, the shunt system typically stretches toward its deployed configuration. However, certain components, such as shape memory actuation elements, may remain at least partially deformed (eg, crimped) even after deployment from the catheter. In some embodiments, the shape memory actuation element deforms to such an extent that its function is affected, thereby requiring additional restoration of the shape memory actuation element.

Method 500 may continue at step 504 by percutaneously advancing the energy delivery catheter toward the shunt system. The energy delivery catheter may be advanced until the transmit coil on the energy delivery catheter is positioned within 5 cm, within 4 cm, within 3 cm, within 2 cm, and/or within 1 cm of a target component of the shunt system (eg, the deformed actuation element). Once the coil on the energy delivery catheter is in place, method 500 may continue at step 506 by initiating power transfer between the energy delivery catheter and the shunt system to activate the resonant circuit including the shape memory actuation element. This may include emitting an electromagnetic field from the transmit coil and inducing a current in the resonant circuit in response to the electromagnetic field, as described with reference to FIGS. 3 and 4 . This causes a current to flow through the shape memory actuation element and resistive heating of the shape memory actuation element. The shape-memory actuation element can be heated above the transition temperature such that it transforms to a relatively harder material state (eg, austenite), which causes the shape-memory actuation element to move toward and restore its preferred geometry .

Although steps 504 and 506 describe the use of an invasive energy delivery device to restore the shape of the shape memory actuated element after deployment of the shunt system, in some embodiments step 504 may be omitted and energy held outside the patient's body may be used The transmission device executes step 506. However, in some embodiments, using the invasive methods described in steps 504 and 506 is preferred because the amount of energy required to at least initially restore the shape memory actuated element is large enough that using non-invasive methods is not an option. practical and/or inefficient. However, once the shape memory actuation element has recovered, non-invasive methods can be used to make additional adjustments to the shape memory actuation element.

As those skilled in the art will appreciate from the disclosure herein, various components of the interatrial shunt system described above may be omitted without departing from the scope of the present technology. Likewise, additional components not expressly described above may be added to the interatrial shunt system without departing from the scope of the present technology. Furthermore, the circuits described herein may be incorporated into other types of implantable medical devices besides cardiac shunts. Accordingly, the technology is not limited to the configurations expressly identified herein, but covers variations and adaptations of the systems described.

Example

Several aspects of the present technology are illustrated in the following examples:

1. An implantable medical device comprising:

an actuation element comprised of a shape memory material and having a preferred geometry, wherein when the actuation element is deformed relative to its preferred geometry and heated above its transition temperature, the actuation element is configured To move towards its preferred geometry; and

one or more electronic components configured to generate an electrical current when exposed to an electromagnetic field, wherein the one or more electronic components form a resonant circuit including the actuating element, and wherein the resonant circuit is configured Such that when the one or more electronic components generate the current, the current flows through the actuation element and resistively heats the actuation element.

2. The device of embodiment 1, wherein the one or more electronic components are configured to generate an electrical current upon exposure to an electromagnetic field generated by an energy source positioned external to the patient.

3. The device of embodiment 1, wherein the one or more electronic components are configured to generate an electromagnetic field upon exposure to an electromagnetic field generated by an energy source positioned within the patient and spaced from the one or more electronic components current.

4. The device of embodiment 1, wherein the one or more electronic components are configured to generate an electrical current in response to delivery of radio frequency (RF) and/or microwave energy.

5. The apparatus of any one of embodiments 1 to 4, wherein the resonant circuit is an RLC circuit.

6. The device of any one of embodiments 1 to 5, wherein the ratio between the first resistance provided by the actuation element and the second resistance provided by the one or more electronic components is between about 2:1 and Between 0.5:1.

7. The device of any one of embodiments 1 to 6, wherein the actuation element has a first surface area, and wherein the one or more electronic components have a second surface area that is greater than the first surface area.

8. The device of embodiment 7, wherein when the current flows through the one or more electronic components and the actuation element, the actuation element is The first power dissipation density in the one or more electronic components is greater than the second power dissipation density in the one or more electronic components.

9. The device of embodiment 7, wherein the actuation element has a first length, and wherein the one or more electronic components have a second length that is greater than the first length.

10. The device according to any one of embodiments 1 to 9, wherein the actuating element has a first resistance and the one or more electronic components collectively have a second resistance, and wherein the first resistance and the second The resistances are approximately the same.

11. The device of any one of embodiments 1 to 10, wherein the resonant circuit is configured to dissipate power when the current flows through the actuation element.

12. The apparatus of any one of embodiments 1 to 11, wherein the resonant circuit has a quality factor of less than 100.

13. The device of any one of embodiments 1 to 12, wherein the actuation element is in series with the one or more electronic components.

14. The device of any one of embodiments 1 to 13, wherein the shape memory material comprises an alloy comprising one or more of nickel, titanium and copper.

15. The device of any one of embodiments 1 to 14, wherein the device is configured to divert fluid between a first body region and a second body region when implanted in a human patient.

16. The device of embodiment 15, further comprising: a shunt element having a lumen extending therethrough and configured such that when the shunt element is implanted in the patient, the lumen The first body region and the second body region are fluidly connected, wherein the actuation element is configured to adjust the lumen geometry.

17. An electrical circuit for use with an implantable medical device, the electrical circuit comprising:

one or more electronic components configured to generate electrical current when exposed to an electromagnetic field; and

a shape memory actuation element integrated with an electrical circuit having the one or more electronic components,

Wherein the current generated by the one or more electronic components in response to exposure to the electromagnetic field flows through the shape memory actuation element and resistively heats the shape memory actuation element.

18. The circuit of embodiment 17, wherein the circuit is a resonant circuit.

19. The circuit of embodiment 17, wherein the circuit is an RLC circuit.

20. The circuit of any one of embodiments 17 to 19, wherein the ratio between the first resistance provided by the shape memory actuation element and the second resistance provided by the one or more electronic components is about 2.0: Between 1 and 0.5:1.

21. The circuit of any one of embodiments 17 to 20, wherein the shape memory actuation element has a first surface area, and wherein the one or more electronic components have a second surface that is greater than the first surface area area.

22. The circuit of embodiment 21, wherein, when the current flows through the one or more electronic components and the actuation element, the actuation element due to the second surface area being greater than the first surface area The first power dissipation density in the one or more electronic components is greater than the second power dissipation density in the one or more electronic components.

23. The circuit of embodiment 21, wherein the actuation element has a first length, and wherein the one or more electronic components have a second length that is greater than the first length.

24. The circuit of any one of embodiments 17 to 23, wherein the shape memory actuation element has a first resistance and the one or more electronic components collectively have a second resistance, and wherein the first resistance and the The second resistor is the same.

25. The circuit of any one of embodiments 17 to 24, wherein the circuit is configured to dissipate power when the current flows through the shape memory actuation element.

26. The circuit of any one of embodiments 17-25, wherein the circuit has a figure of merit of less than 100.

27. The circuit of any one of embodiments 17 to 26, wherein the shape memory actuation element is in series with the one or more electronic components.

28. The circuit of any one of embodiments 17 to 27, wherein the shape memory actuation element has a transition temperature, and wherein the circuit is configured such that when the one or more electronic components are exposed to the electromagnetic field, The generated electrical current heats at least a portion of the resistance of the shape memory actuation element above its transition temperature.

29. A method for controlling a medical device implanted in a patient, the method comprising:

directing energy toward one or more electronic components implanted in the patient, wherein the electronic components form a resonant circuit including an actuation element operatively coupled to the implanted medical device; and

In response to the energy, a current is automatically generated in the resonant circuit, wherein the current flows through the actuation element and resistively heats the actuation element.

30. The method of embodiment 29, wherein directing the energy toward the one or more electronic components comprises directing energy from an energy source positioned external to the patient.

31. The method of embodiment 29, wherein directing the energy toward the one or more electronic components comprises directing energy from an energy source temporarily positioned within the patient but spaced from the one or more electronic components.

32. The method of any one of embodiments 29-31, wherein directing the energy toward the one or more electronic components comprises generating an electromagnetic field around the one or more electronic components.

33. The method of any one of embodiments 29-32, wherein directing the energy toward the one or more electronic components comprises directing RF or microwave energy toward the one or more electronic components.

34. The method of any one of embodiments 29 to 33, wherein the actuation element is comprised of a shape memory material, and wherein resistively heating the actuation element heats the actuation element above a transition temperature, wherein The transition temperature is a temperature greater than body temperature.

35. The method of embodiment 34, wherein heating the actuating element above the transition temperature transforms the actuating element from a first configuration in which it deforms relative to its preferred geometry to a second configuration in which it assumes its preferred geometry. configuration and/or transition towards the second configuration.

36. The method of embodiment 35, wherein moving the actuation element from the first configuration toward the second configuration controls one or more operations of the implanted medical device.

37. The method of embodiment 36, wherein the implanted medical device is a shunt fluidly connecting a first body region and a second body region, and wherein the actuating element is directed from the first configuration toward the second body region Configuration moves adjust the geometry of the splitter.

38. A method for deploying an adjustable shunt system having a shape memory actuation element, the method comprising:

deploying the adjustable shunt system comprising the shape memory actuation element at a target location within the patient, wherein the shape memory actuation element deforms relative to a preferred geometry after deployment of the adjustable shunt system;

advancing an energy delivery catheter percutaneously toward the shunt system until the energy delivery catheter approaches the adjustable shunt system; and

initiating power transfer between the energy delivery catheter and the shunt system to induce a current in a resonant circuit including the shape memory actuation element,

Wherein the current resistively heats the shape memory actuation element.

39. The method of embodiment 38, wherein the energy delivery catheter is a first catheter, and wherein deploying the adjustable shunt system at the target location comprises: percutaneously advancing a different catheter than the first catheter toward the target location A second conduit carrying the adjustable shunt system.

40. The method of embodiment 38 or 39, wherein percutaneously advancing the energy delivery catheter until the energy delivery catheter is in proximity to the adjustable shunt system comprises: positioning a transmitter coil carried by the energy delivery catheter over the adjustable shunt within 5cm of the system.

41. The method of embodiment 40, wherein percutaneously advancing the energy delivery catheter until the energy delivery catheter approaches the adjustable shunt system comprises positioning the transmitter coil within 2 cm of the adjustable shunt system.

42. The method of embodiment 40, wherein the transmitter coil does not contact the adjustable shunt system.

43. The method of any one of embodiments 38 to 42, wherein the electrical current heats the shape memory actuation element resistively above the transition temperature and causes the shape memory actuation element to move from a deformed configuration towards its preferred geometry move.

in conclusion

Embodiments of the present disclosure may include some or all of the following components: batteries, supercapacitors, or other suitable power sources; microcontrollers, FPGAs, ASICs, or software and/or firmware capable of storing and executing operations that drive the implant Other programmable components or systems; memory such as RAM or ROM for storing data and/or software/firmware associated with the implant and/or its operation; wireless communication hardware such as configured to communicate via Bluetooth, WiFi or Antenna systems for transmission by other protocols known in the art; energy harvesting devices such as coils or antennas capable of receiving and/or reading externally provided signals that can be used to power the device, charge batteries, start Readings from sensors or for other purposes. Embodiments may also include one or more sensors such as pressure sensors, impedance sensors, accelerometers, force/strain sensors, temperature sensors, flow sensors, optical sensors, cameras, microphones or other acoustic sensors, ultrasound sensors, ECG or other cardiac rhythm sensors sensors, SpO2 and other sensors suitable for measuring tissue and/or blood gas levels, blood volume sensors, and other sensors known to those skilled in the art. Embodiments may include radiopaque and/or ultrasound reflective portions to facilitate image-guided implantation or image-guided surgery using techniques such as fluoroscopy, sonography, or other imaging methods. Embodiments of the system may include a dedicated delivery catheter/system adapted to deliver the implant and/or perform the procedure. The system may include components such as a guide wire, a sheath, a dilator, and multiple delivery catheters. Components may be interchanged via in-line, quick swap, combination, or other methods.

The above detailed descriptions of embodiments of the technology are not intended to be exhaustive or to limit the technology to the precise forms disclosed above. While specific embodiments of, and examples for, the technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the technology, as those skilled in the relevant art will recognize. For example, although steps are presented in a given order, alternative embodiments may perform steps in a different order. The various embodiments described herein can also be combined to provide other embodiments. For example, although this disclosure has been written to describe devices generally described as being used to create a fluid communication pathway between the LA and the RA, between the LV and the right ventricle (RV), or between the LA and the coronary sinus, It should be understood that similar embodiments may also be used for shunts between other chambers of the heart or for shunts in other regions of the body.

Unless the context clearly requires otherwise, throughout the specification and examples, the words "comprise", "comprising", etc. are to be interpreted in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is , in the sense of "including but not limited to". As used herein, the terms "connected", "coupled" or any variation thereof mean any direct or indirect connection or connection between two or more elements; the connection or connection between elements may be physical, logical or a combination of them. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words using singular or plural in the above specific embodiments may also include plural or singular, respectively. As used herein, the phrase "and/or" as in "A and/or B" refers to A alone, B alone, and A and B. Furthermore, the term "comprising" throughout means including at least the mentioned features, such that any greater number of the same features and/or other types of features are not excluded. It should also be understood that specific embodiments have been described herein for purposes of illustration, but that various modifications may be made without departing from the technology. Furthermore, while advantages associated with certain embodiments of the present technology have been described in the context of these embodiments, other embodiments may exhibit such advantages as well, and not all embodiments must exhibit such advantages to be considered scope of this technology. Accordingly, the present disclosure and related art may encompass other embodiments not expressly shown or described herein.

Claims (43)

1. An implantable medical device, said device comprising: an actuation element comprised of a shape memory material and having a preferred geometry, wherein when the actuation element is deformed relative to its preferred geometry and heated above its transition temperature, the actuation the element is configured to move towards its preferred geometry; and one or more electronic components configured to generate an electrical current when exposed to an electromagnetic field, wherein the one or more electronic components form a resonant circuit including the actuation element, and wherein the The resonant circuit is configured such that when the one or more electronic components generate the current, the current flows through the actuation element and resistively heats the actuation element. 2. The apparatus of claim 1, wherein the one or more electronic components are configured to generate an electrical current upon exposure to an electromagnetic field generated by an energy source positioned external to the patient. 3. The apparatus of claim 1 , wherein the one or more electronic components are configured to be exposed to energy generated by an energy source positioned within the patient and spaced apart from the one or more electronic components. An electric current is generated in an electromagnetic field. 4. The apparatus of claim 1, wherein the one or more electronic components are configured to generate an electrical current in response to delivery of radio frequency (RF) and/or microwave energy. 5. The apparatus of claim 1, wherein the resonant circuit is an RLC circuit. 6. The device of claim 1, wherein a ratio between the first resistance provided by the actuation element and the second resistance provided by the one or more electronic components is between about 2:1 and 0.5:1 between. 7. The device of claim 6, wherein the actuation element has a first surface area, and wherein the one or more electronic components have a second surface area greater than the first surface area. 8. The device of claim 7, wherein when the current flows through the one or more electronic components and the actuation element, since the second surface area is greater than the first surface area , a first power dissipation density in the actuation element is greater than a second power dissipation density in the one or more electronic components. 9. The device of claim 7, wherein the actuation element has a first length, and wherein the one or more electronic components have a second length greater than the first length. 10. The device of claim 1, wherein the actuating element has a first resistance and the one or more electronic components collectively have a second resistance, and wherein the first resistance is approximately the same as the second resistance same. 11. The device of claim 1, wherein the resonant circuit is configured to dissipate power when the current flows through the actuation element. 12. The device of claim 1, wherein the resonant circuit has a quality factor of less than 100. 13. The device of claim 1, wherein the actuation element is in series with the one or more electronic components. 14. The device of claim 1, wherein the shape memory material comprises an alloy comprising one or more of nickel, titanium, and copper. 15. The device of claim 1, wherein the device is configured to divert fluid between a first body region and a second body region when implanted in a human patient. 16. The device of claim 15, further comprising a shunt element having a lumen extending therethrough and configured such that when the shunt element is implanted in the patient , the lumen fluidly connects the first body region and the second body region, wherein the actuation element is configured to adjust a geometry of the lumen. 17. An electrical circuit for use with an implantable medical device, the electrical circuit comprising: one or more electronic components configured to generate electrical current when exposed to an electromagnetic field; and a shape memory actuation element integrated with an electrical circuit having said one or more electronic components, wherein the current generated by the one or more electronic components in response to exposure to the electromagnetic field flows through the shape memory actuation element and resistively heats the shape memory actuation element. 18. The circuit of claim 17, wherein the circuit is a resonant circuit. 19. The circuit of claim 17, wherein the circuit is an RLC circuit. 20. The circuit of claim 17, wherein a ratio between the first resistance provided by the shape memory actuation element and the second resistance provided by the one or more electronic components is between about 2.0:1 and 0.5: between 1. 21. The circuit of claim 20, wherein the shape memory actuation element has a first surface area, and wherein the one or more electronic components have a second surface area greater than the first surface area. 22. The circuit of claim 21 , wherein when the current flows through the one or more electronic components and the actuating element, since the second surface area is greater than the first surface area , a first power dissipation density in the actuation element is greater than a second power dissipation density in the one or more electronic components. 23. The circuit of claim 21, wherein the actuation element has a first length, and wherein the one or more electronic components have a second length greater than the first length. 24. The circuit of claim 17, wherein the shape memory actuation element has a first resistance and the one or more electronic components collectively have a second resistance, and wherein the first resistance is connected to the second resistance. The resistance is the same. 25. The circuit of claim 17, wherein the circuit is configured to dissipate power when the current flows through the shape memory actuation element. 26. The circuit of claim 17, wherein the circuit has a figure of merit of less than 100. 27. The circuit of claim 17, wherein the shape memory actuation element is in series with the one or more electronic components. 28. The circuit of claim 17, wherein the shape memory actuation element has a transition temperature, and wherein the circuit is configured such that when the one or more electronic components are exposed to the electromagnetic field, the generated The electrical current heats at least a portion of the resistance of the shape memory actuation element above its transition temperature. 29. A method for controlling a medical device implanted in a patient, the method comprising: directing energy toward one or more electronic components implanted in the patient, wherein the electronic components form a resonant circuit including an actuation element operatively coupled to an implanted medical device; and In response to the energy, a current is automatically generated in the resonant circuit, wherein the current flows through the actuation element and resistively heats the actuation element. 30. The method of claim 29, wherein directing the energy toward the one or more electronic components comprises directing energy from an energy source positioned external to the patient. 31. The method of claim 29, wherein directing the energy toward the one or more electronic components comprises directing energy from a device temporarily positioned within the patient but spaced from the one or more electronic components source of energy. 32. The method of claim 29, wherein directing the energy toward the one or more electronic components comprises generating an electromagnetic field around the one or more electronic components. 33. The method of claim 29, wherein directing the energy toward the one or more electronic components comprises directing RF or microwave energy toward the one or more electronic components. 34. The method of claim 29, wherein the actuating element is comprised of a shape memory material, and wherein resistively heating the actuating element heats the actuating element above a transition temperature, wherein the transition Temperature is a temperature greater than body temperature. 35. The method of claim 34, wherein heating the actuating element above the transition temperature transforms the actuating element from its first configuration deformed relative to a preferred geometry to assume its preferred geometry the second configuration and/or transition towards said second configuration. 36. The method of claim 35, wherein moving the actuation element from the first configuration toward the second configuration controls one or more operations of the implanted medical device. 37. The method of claim 36, wherein the implanted medical device is a shunt fluidly connecting a first body region and a second body region, and wherein directing the actuating element from the first configuration toward The second configuration movement adjusts the geometry of the splitter. 38. A method for deploying an adjustable shunt system having a shape memory actuation element, the method comprising: Deploying the adjustable shunt system including the shape memory actuation element at a target location within the patient, wherein the shape memory actuation element deforms relative to a preferred geometry after deployment of the adjustable shunt system ; advancing an energy delivery catheter percutaneously toward the shunt until the energy delivery catheter is in proximity to the adjustable shunt; and initiating power transfer between the energy delivery catheter and the shunt system to induce a current in a resonant circuit including the shape memory actuation element, Wherein the electric current performs resistive heating on the shape memory actuation element. 39. The method of claim 38, wherein the energy delivery catheter is a first catheter, and wherein deploying the adjustable shunt system at the target location comprises: advancing percutaneously toward the target location in conjunction with the A second conduit different from the first conduit, the second conduit carrying the adjustable shunt system. 40. The method of claim 38, wherein percutaneously advancing the energy delivery catheter until the energy delivery catheter is in proximity to the adjustable shunt system comprises positioning a transmitter coil carried by the energy delivery catheter on the Adjustable shunt system within 5cm. 41. The method of claim 40, wherein percutaneously advancing the energy delivery catheter until the energy delivery catheter is in proximity to the adjustable shunt system comprises: positioning the transmitter coil on the adjustable shunt system within 2cm. 42. The method of claim 40, wherein the transmitter coil does not contact the adjustable shunt system. 43. The method of claim 38, wherein the current resistively heats the shape memory actuation element above a transition temperature and causes the shape memory actuation element to move from a deformed configuration towards its preferred geometry.