Implantable passive mean pressure sensor

Abstract

An implantable pressure sensor includes a housing and a sensing component housed by the housing and exposed to an external pressure outside the housing. In response to the external pressure, the sensing component is configured to undergo a physical transformation that is representative of an average pressure of the external pressure over a period of at least one minute. The pressure sensor includes a circuit operable to be coupled to the sensing component and responsive to the physical transformation of the sensing component to produce an average pressure signal representative of the average pressure of the external pressure over a period of time.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 119,337, filed November 30, 2020, the disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to pressure sensors. More specifically, this disclosure relates to implantable pressure sensors capable of providing an average pressure indication. Background Technology

[0004] Various pressure sensors have been developed to measure a wide range of pressures, including blood pressure. Some pressure sensors can be implanted to provide blood pressure values. Because they are implanted, there is a problem of maintaining power to the pressure sensor over a period of time. Furthermore, while pressure sensors can provide instantaneous pressure indications, they are not typically configured to provide an indication of average pressure over a period of time. There is a need for a pressure sensor that can provide an indication of average pressure over a period of time, particularly one that does not require continuous electrical power to maintain the average pressure measurement over a period of time. Summary of the Invention

[0005] This disclosure relates to a pressure sensor capable of providing an indication of average pressure over a period of time, even without continuous electrical power to maintain the indication of average pressure over that period. As an example, an implantable pressure sensor includes a housing and a sensing element, the sensing element being housed by the housing and exposed to external pressure outside the housing. In response to external pressure, the sensing element is configured to undergo a physical transformation representing the average pressure of the external pressure over a period of at least one minute. The pressure sensor includes circuitry operable to be coupled to the sensing element and, in response to the physical transformation of the sensing element, to generate an average pressure signal representing the average pressure of the external pressure over a period of time.

[0006] Alternatively or additionally, the circuit can be configured to repeatedly receive energy transfers from a remote source and, in response, transmit an average pressure signal back to the remote source.

[0007] Alternatively or additionally, the sensing element can experience and maintain a physical change representing the average pressure over a period of time, without the application of power.

[0008] Alternatively or additionally, the physical transformation of the sensing element may have a time constant of at least one hour.

[0009] Alternatively or additionally, the physical transformation of the sensing element may have a time constant of at least twelve hours.

[0010] Alternatively or additionally, the physical transformation of the sensing element may have a time constant of at least one day.

[0011] Alternatively or additionally, the housing may be adapted for placement within a patient’s heart, bladder, brain, spine, eyes, joints, or vascular system.

[0012] Alternatively or additionally, the sensing element may include a first plate exposed to external pressure outside the housing and configured to move in response to pressure changes within the external pressure, a second plate spaced apart from the first plate and disposed within the housing, and a viscoelastic material disposed between the first and second plates.

[0013] Alternatively or additionally, the viscoelastic material may include a non-conductive material, and the average pressure signal may represent the capacitance between the first and second plates.

[0014] Alternatively or additionally, the viscoelastic material may include a conductive material, and the average pressure signal may be an indication of the resistance between the first and second plates.

[0015] Alternatively or additionally, the first plate may be conductive, and the second plate may be conductive.

[0016] Alternatively or additionally, the sensing element may include a hydraulic sensing element.

[0017] Alternatively or additionally, the hydraulic sensing component may include a hydraulic chamber exposed to external pressure, a first fluid disposed within the hydraulic chamber, a pressure chamber, a second fluid disposed within the pressure chamber, and a barrier disposed between the first and second fluids. Pressure changes in the hydraulic chamber relative to the pressure chamber can cause movement of the barrier.

[0018] Alternatively or additionally, the barrier may include a low-flow valve with a highly permeable material.

[0019] As another example, an implantable pressure sensor is configured to provide a signal indicating an average pressure value over a period of time. The implantable pressure sensor includes a housing configured for implantation within a patient's body and a sensing element disposed within the housing but exposed to the external environment. The sensing element is configured to maintain the average pressure measurement in the absence of electrical power, thereby providing an indication of the average pressure within the external environment of the housing over a period of time.

[0020] Alternatively or additionally, the sensing element may include a viscoelastic material having a time constant of at least one hour.

[0021] As another example, a left atrial appendage closure device is adapted to be fitted into a patient's left atrial appendage to substantially close the patient's left atrial appendage. The left atrial appendage closure device includes an expandable frame. Once the device is implanted, a sensing element is exposed to the left atrial pressure within the left atrium of the patient's heart, wherein, in response to the left atrial pressure, the sensing element is configured to undergo a physical transformation representing the average pressure of the left atrial pressure over a period of at least one minute. Circuitry is operable to be coupled to the sensing element and, in response to the physical transformation of the sensing element, generates an average pressure signal representing the average pressure of the left atrial pressure over a period of time.

[0022] Alternatively or additionally, the sensing element may include a viscoelastic material having a time constant of at least 10 minutes, which viscoelastic material undergoes viscoelastic deformation in response to left atrial pressure in a manner representing the average pressure of the left atrial pressure over a period of time.

[0023] Alternatively or additionally, the sensing element may include a hydraulic system comprising a low-flow valve, wherein in response to a positive change in left atrial pressure, the sensing element causes fluid to move through the low-flow valve in a first direction under hydraulic resistance, the first direction being constrained by a time constant of the sensing element defined at least in part by the low-flow valve.

[0024] Alternatively or additionally, in response to a negative change in left atrial pressure, the sensing element can cause fluid to move through a low-flow valve in a second direction opposite to the first direction, subject to the time constant of the sensing element.

[0025] The above overview of some embodiments is not intended to describe every disclosed embodiment or every implementation of this disclosure. The following drawings and detailed description illustrate these embodiments in more detail. Attached Figure Description

[0026] This disclosure will be more fully understood in light of the following detailed description taken in conjunction with the accompanying drawings, in which:

[0027] Figure 1 This is a schematic block diagram illustrating a pressure sensing system;

[0028] Figure 2 This is an illustrative schematic diagram of a pressure sensor;

[0029] Figure 3 It is a graphical representation of the average pressure data;

[0030] Figure 4 This is a schematic diagram illustrating a pressure sensor;

[0031] Figure 4A This is a schematic diagram of a portion of an illustrative pressure sensor;

[0032] Figure 4B This is a schematic diagram of a portion of an illustrative pressure sensor;

[0033] Figure 5 It is a perspective view of an illustrative left atrial appendage closure device; and

[0034] Figure 6 yes Figure 5 A side view of an illustrative left atrial appendage closure device.

[0035] While this disclosure is applicable to various modifications and alternatives, its details have been shown by way of example in the accompanying drawings and will be described in detail. However, it should be understood that it is not intended to limit the invention to the specific embodiments described. Rather, it is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure. Detailed Implementation

[0036] The terms defined below shall apply unless otherwise defined in the claims or elsewhere in this specification.

[0037] All numerical values ​​in this document are assumed to be modified by the term "approximately," whether explicitly stated or not. The term "approximately" generally refers to a range of numbers that a person skilled in the art would consider equivalent to the stated value (e.g., having the same function or result). In many cases, the term "approximately" may include numbers rounded to the nearest significant figure.

[0038] The range of numbers listed by the endpoints includes all numbers in that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0039] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly specifies otherwise. As used in this specification and the appended claims, the term “or” is used in its usual sense to include “and / or” unless the context clearly specifies otherwise.

[0040] It should be noted that references to "embodiments," "some embodiments," and "other embodiments" in the specification indicate that the described embodiments may include one or more specific features, structures, and / or characteristics. However, such descriptions do not necessarily imply that all embodiments include the specific features, structures, and / or characteristics. Furthermore, when a specific feature, structure, and / or characteristic is described in connection with an embodiment, it should be understood that, unless explicitly stated otherwise, such features, structures, and / or characteristics may also be used in conjunction with other embodiments, whether or not explicitly described.

[0041] The following detailed description should be read with reference to the accompanying drawings, in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily drawn to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.

[0042] Figure 1 This is a schematic block diagram of an illustrative pressure sensing system 10. The pressure sensing system 10 includes a pressure sensor 12 and a remote power source 20. The pressure sensor 12 can be configured to be implanted in a patient's body. In some cases, the pressure sensor 12 can be configured to be implanted in a location where the pressure sensor 12 can be exposed to the patient's bloodstream, such as within the patient's vascular system. For example, the pressure sensor 12 can be configured to be implanted within a chamber of the patient's heart. In other cases, for example, the pressure sensor 12 can be configured to be implanted in the patient's bladder, arteries, veins, brain, spine, eyes, joints, or other locations.

[0043] The illustrative pressure sensor 12 includes a housing 16 configured for implantation at a desired location within a patient's body. Although the pressure sensor 12 is described herein as being deployed as an implantable device intended for use in the human body, it should be understood that the pressure sensor 12 can also be used in other applications. When intended for use in the human body, the housing 16 can be formed of any suitable biocompatible material, such as a biocompatible polymer material or a biocompatible metallic material. In some cases, the housing 16 may be formed of a non-biocompatible material, but may have a biocompatible film or coating covering the exterior of the housing 16.

[0044] The pressure sensor 12 can be viewed as being configured to provide an indication of average pressure or an average pressure value over a period of time. The average pressure can be a rolling average pressure obtained over a predetermined time range. That is, instead of being an instantaneous pressure sensor that immediately reports the currently detected pressure, the pressure sensor 12 creates and maintains an average pressure measurement that is not excessively affected by instantaneous spikes in pressure. For example, blood pressure may spike when a person climbs stairs or otherwise exerts force. Instantaneous blood pressure measurements, especially those taken only at specific time intervals, may not provide an accurate picture of a person's overall cardiovascular health. In contrast, average blood pressure measurements are better able to ignore short-term pressure spikes, thus more accurately representing overall blood pressure trends.

[0045] The illustrative pressure sensor 12 includes a sensing element 18. The sensing element 18 can be configured to create and maintain an indication of average pressure representing the average pressure of the environment outside the housing 16 over a period of time. For this purpose, the housing 16 can be configured to allow the sensing element 18, or at least a portion thereof, to be exposed to the environment outside the housing 16. In some cases, the sensing element 18 may comprise a viscoelastic material. A viscoelastic material is a material whose stress-strain relationship depends on time and includes properties of both viscous and elastic materials. Viscosity is a measure of resistance to fluid flow, while elasticity is a measure of a material's return to its original state after a force is applied. A highly damped viscoelastic polymer solid that flows like a liquid under load... It is an example of a viscoelastic material. It is a thermosetting, polyether-based polyurethane material. Memory foam is another example of a viscoelastic material. Other examples of viscoelastic materials include some polymers, semi-crystalline polymers, biopolymers, neoprene rubber, and bitumen materials. These materials can be customized to have a desired time constant to match the desired application.

[0046] The sensing element 18 can be implemented as a hydraulic system, rather than using a viscoelastic material, capable of tracking an average or rolling average pressure over a period of time. Other systems may also be used. In any case, the sensing element 18 can be considered as being configured to maintain an indication of the average pressure over a period of time without requiring any power source to create and maintain the average pressure indication. Therefore, the pressure sensor 12 does not require any onboard power source, such as a battery. Instead, the pressure sensor 12 can be configured to periodically receive power transmitted from a remote power source 20. To enable the pressure sensor 12 to receive and utilize power transmitted from the remote power source 20, the pressure sensor 12 includes circuitry 22 operable to be coupled to the sensing element 18.

[0047] The illustrative circuitry 22 includes an antenna 24 configured to receive electrical energy from a remote power source 20. Circuitry 22 is configured to convert the electrical energy into an appropriate form where appropriate and to use that energy to request a signal from a sensing element 18. Circuitry 22 then transmits a signal providing an indication of the average pressure over a period of time measured by the sensing element 18 to a remote monitoring device 26. In some cases, a single antenna 24 may be capable of both receiving electrical energy transmitted from the remote power source 20 and communicating with the remote monitoring device 26. In some cases, antenna 24 may alternatively represent a first antenna configured to receive electrical energy transmitted from the remote power source 20 and a second antenna configured to transmit a signal to the remote monitoring device 26. Although the remote power source 20 and the remote monitoring device 26 are shown as separate devices, it should be understood that in some cases, the remote power source 20 and the remote monitoring device 26 may be incorporated into a single handheld device.

[0048] It should be noted that the electrical energy supplied to the pressure sensor 12 from the remote power source 20 is not used to create or maintain an indication of the average pressure measurement over a period of time. Instead, the indication of the average pressure measurement over a period of time is created and maintained by the sensing element 18 when continuous electrical energy is not required. In this example, the electrical energy supplied by the remote power source 20 is only used to query the sensing element 18 for an indication of the average pressure measurement over a period of time and to transmit a signal representing the indication of the average pressure measurement over a period of time to the remote monitoring device 26.

[0049] In some cases, sensing element 18 can be considered as having been configured to undergo a physical transformation in response to external pressure exposed to the exterior of housing 16. A physical transformation can be considered as the average pressure over a period of at least one minute. Brief spikes in pressure may be largely ignored. The physical transformation of sensing element 18 can be considered as having a time constant of at least one hour. The physical transformation of sensing element 18 can be considered as having a time constant of at least 12 hours. The physical transformation of sensing element 18 can be considered as having a time constant of at least one day. Here, the time constant represents the rate at which sensing element 18 can respond to changes in input pressure, defined here as the time it takes for the average pressure reported by sensing element 18 to change by a factor of 1 - 1 / e (approximately 0.6321) in response to a step change in input pressure. That is, for a time constant of one day, when the input pressure P is halved to P / 2 at time “t” and maintained at P / 2 for one day, sensing element 18 will report an average pressure of P – (P / 2 * (1 - 1 / e)) ≈ 0.68P after one day. This is just one example.

[0050] In some cases, the time constant used to increase pressure (e.g., the compression time constant) can be configured to be approximately equal to the time constant used to decrease pressure (e.g., the expansion time constant) to facilitate the measurement of average pressure values. In other cases, the time constants for increasing and decreasing pressure may not be equal. For example, it may be desirable to bias measurements towards higher or lower pressures, or when both time constants are adjusted to account for biological effects (e.g., tissue encapsulation).

[0051] In some cases, the signal provided by circuit 22, representing the average pressure measurement provided by sensing element 18, can be corrected for sensor hysteresis. This correction can occur within the remote monitoring device 26 to reduce computational requirements on circuit 22, although in some cases circuit 22 itself can correct for sensor hysteresis. In some cases, in addition to the average pressure measurement provided by pressure sensor 12, a second pressure sensor or one or more additional pressure sensors (not shown) can be implanted in the patient to provide instantaneous measurements when needed. The second pressure sensor or one or more additional pressure sensors can be part of pressure sensor 12 and operable to be coupled to circuit 22. Alternatively, one or more additional pressure sensors can be housed separately. The one or more additional pressure sensors can be used to calibrate pressure sensor 12. Alternatively, pressure sensor 12 can be used to calibrate an instantaneous pressure sensor. It should be understood that pressure sensor 12 (and any additional pressure sensors) can be configured to operate within pressure ranges encountered in blood vessels or chambers within the human body. For example, the expected absolute pressure range within the left atrium is 450 to 950 mmHg. The expected gauge pressure in the left atrium is 2 to 90 mm Hg.

[0052] Figure 2 This is a schematic diagram of an illustrative pressure sensor 28 exposed to an environment 30 with variable pressure. Pressure sensor 28 can be considered as an example of pressure sensor 12. Environment 30 can represent part of a patient's vascular system, including their heart, or a patient's bladder or other cavity. Illustrative pressure sensor 28 includes a chamber 32 formed between a first plate 34 and a second plate 36. It can be considered as... Figure 1 The illustrative housing 38 of the housing 16 shown provides sides and a bottom for the chamber 32. The first plate 34 is positioned such that when the external pressure within the environment 30 increases, the pressure change within the environment 30 causes the first plate 34 to bend downwards (in the shown orientation), and when the external pressure within the environment 30 decreases, the first plate 34 causes the first plate 34 to bend upwards (in the shown direction). In this example, the chamber 32 is filled with a viscoelastic material 40.

[0053] The first plate 34 and the second plate 36 can be considered to be conductive. In some cases, when the viscoelastic material 40 is non-conductive, the physical transformation of the viscoelastic material 40 that has occurred over a period of time can be indicated by detecting the capacitance between the first plate 34 and the second plate 36. In other cases, when the viscoelastic material 40 is conductive, the physical transformation of the viscoelastic material 40 that has occurred over a period of time can be indicated by detecting the resistance between the first plate 34 and the second plate 36. These are just examples.

[0054] Figure 3This is a graphical representation 50 of how a viscoelastic material is used to track average pressure measurements over a period of time. This particular example tracks left atrial pressure over a five-week period, with left atrial pressure indicated on the vertical axis and time indicated on the horizontal axis. This pressure data is not actual pressure data obtained from the patient, but is generated to illustrate how average pressure measurements over a period of time can ignore transient spikes and missed measurements. While this example is specific to the use of a viscoelastic material as part of sensing element 18, it should be understood that the lessons learned from this example are equally applicable to other types of sensing elements 18, such as hydraulic or other systems.

[0055] Curve 52 illustrates the mean left atrial pressure determined by periodic instantaneous measurements 56. In some cases, curve 52 indicates that the mean left atrial pressure determined by periodic instantaneous measurements 56 can be skewed if the instantaneous measurement is taken at an inopportune time (e.g., at a short-term peak). For example, several periodic instantaneous measurements 58 show elevated left atrial pressure values ​​due to conditions interfering with the expected mean pressure measurement, such as instantaneous measurements taken while the person is exercising. Curve 52 also shows that the mean left atrial pressure determined by periodic instantaneous measurements can be biased if instantaneous measurements are missing, such as a missed sample 60. Curve 62 provides a representation of the patient's actual left atrial pressure. It can be seen that curve 62 passes through each of the periodic instantaneous measurements 56, the inopportune instantaneous measurements 58, and the missed instantaneous measurements 60. It can be seen that the actual pressure can periodically spike.

[0056] Curve 64 provides a representation of the mean left atrial pressure determined using a viscoelastic material. As can be seen, as indicated by curve 62, curve 64 generally tracks the actual left atrial pressure, and curve 64 is unaffected by untimely transient measurements 58 or missed transient measurements 60. This illustrates how mean pressure measurements can be used as a reliable indicator of blood pressure performance when frequent transient measurements are not required. It also illustrates how viscoelastic materials can be used to provide an indication of mean pressure over a period of time in a manner that does not require electrical energy to create or maintain an indication of mean pressure over a period of time.

[0057] Figure 4This is a schematic diagram of an illustrative pressure sensor 70 exposed to an environment 30 with variable pressure. The pressure sensor 70 can be considered as an example of pressure sensor 12 and can be hydraulically operated. The pressure sensor 70 includes a hydraulic chamber 72 exposed to external pressure within the environment 30. The hydraulic chamber 72 includes a chamber wall 74 configured to bend and flex in response to a relative pressure difference between the environment 30 and the hydraulic chamber 72. The hydraulic chamber 72 includes a first fluid. The pressure sensor 70 includes a pressure chamber 76 containing a second fluid. The second fluid may be the same as the first fluid. In some cases, the first fluid may be a liquid. In some cases, the second fluid may be a liquid. A barrier 78 is fluidly coupled between the hydraulic chamber 72 and the pressure chamber 76. The hydraulic chamber 72 can be considered as acting as a motion multiplier, such that a relatively small pressure difference between the environment 30 and the hydraulic chamber 72 results in detectable movement of the barrier 78.

[0058] In the example shown, barrier 78 includes a low-flow valve made of a highly permeable material. When the external pressure within environment 30 changes, barrier 78, fluidly arranged between hydraulic chamber 72 and pressure chamber 76, moves in response. Furthermore, the maintained external pressure causes some fluid to flow slowly through the low-flow valve, moving between hydraulic chamber 72 and pressure chamber 76. The flow rate through the low-flow valve of barrier 78 can be selected to set the time constant of pressure sensor 70. This physical transformation of barrier 78 and the movement of fluid between hydraulic chamber 72 and pressure chamber 76 represent the average external pressure. To read the average pressure value, coil 80 can be coupled to barrier 78. When barrier 78 moves in response to pressure changes, the inductance of coil 80 changes. Therefore, when hydraulic chamber 72, pressure chamber 76, and the fluid therein are not conductive, measuring the inductance of coil 80 can provide an indication of the average pressure measurement.

[0059] Figure 4A One version of the pressure sensor 70 is shown, in which capacitance is used to provide an indication of average pressure. Figure 4A In the middle, the first plate 90 and the second plate 92 are conductive and serve as a barrier 78 with a low-flow valve. Figure 4 In some cases, the first plate 90 moves in response to changes in average pressure, while the second plate 92 does not. Since the distance between the first plate 90 and the second plate 92 changes according to pressure variations, the capacitance between the first plate 90 and the second plate 92 can be used as an indication of the average pressure measurement. Figure 4A In this case, the first and second fluids are non-conductive or substantially non-conductive. In this context, substantially non-conductive means that the fluid's conductivity is insufficient to interfere with the capacitance measurement. Figure 4B In this process, a conductive liquid is used, and the resistance change between the first plate 90 and the second plate 92 can be used as an indication of the average pressure measurement.

[0060] Figure 5 This is a perspective view of an exemplary left atrial appendage closure device 100, and Figure 6 This is a side view showing a left atrial appendage closure device 100 including an occlusion element 104. The left atrial appendage closure device 100 includes an expandable frame 102 configured to switch between a folded configuration (for delivery) and an expanded configuration, as shown. In some cases, the expandable frame can be compliant and can substantially conform to the shape and / or geometry of the sidewalls and / or ventral opening of the left atrial appendage in the expanded configuration, and / or seal against them. The left atrial appendage closure device 100 can expand to a size, degree, or shape smaller than or different from the maximum degree of unconstraint determined by the surrounding tissue and / or sidewalls of the left atrial appendage. Reducing the thickness of the various elements of the expandable frame 102 can increase the flexibility and compliance of the expandable frame 102 and / or the left atrial appendage closure device 100, thereby allowing the expandable frame 102 and / or the left atrial appendage closure device 100 to conform to the surrounding tissue, rather than forcing the tissue to conform to the expandable frame 102 and / or the left atrial appendage closure device 100.

[0061] In some cases, such as Figure 6 As shown, the left atrial appendage closure device 100 may optionally include an occlusion element 104 (e.g., a mesh, fabric, membrane, and / or other surface treatments) disposed on, above, around, or covering at least a portion of the expandable frame 102. In some embodiments, the occlusion element 104 may be disposed on, above, around, or covering at least a portion of the outer (or outward-facing) surface of the expandable frame 102.

[0062] In some embodiments, the expandable frame 102 may include a plurality of anchoring members 106 disposed around the periphery of the expandable frame in an expandable configuration. The plurality of anchoring members 106 may extend radially outward from the expandable frame 102. In some embodiments, at least some of the plurality of anchoring members 106 may each have and / or include a body portion, a tip portion, and barbs projecting circumferentially therefrom. In some embodiments, some and / or each of the plurality of anchoring members 106 has at least one barb projecting circumferentially therefrom. The plurality of anchoring members 106 may provide an anchoring mechanism to help retain the left atrial appendage closure device 100 in an expandable configuration at a target site (e.g., the left atrial appendage) within the patient's anatomy. However, one or more barbs may be configured, positioned, and / or arranged such that engagement of one or more barbs with surrounding tissue at the target site is minimized. For example, in an expandable configuration, one or more barbs may not puncture, penetrate, and / or extend into the surrounding tissue. Furthermore, in some embodiments, the plurality of anchoring members 106 may provide an attachment mechanism for securing the occlusion element 104 to the expandable frame 102.

[0063] The left atrial appendage closure device 100 may include a central post 108, from which at least some components of an expandable frame 102 may extend. In some cases, such as Figure 6 As shown, the central column 108 may include a pressure sensor 110 disposed within the central column 108. In this case, the central column 108 may at least partially serve as the housing of the pressure sensor 110. Although schematically shown, the pressure sensor 110 may represent... Figure 1 The pressure sensor 12 is shown. The pressure sensor 110 can represent... Figure 2 The pressure sensor 28 is shown. The pressure sensor 110 can represent... Figure 4 The pressure sensor 70 is shown. It should be understood that by placing the pressure sensor 110 within the central post 108, or by attaching the pressure sensor 100 to any other part of the left atrial appendage closure device 100, an average measurement of the left atrial pressure over a period of time can be obtained. In some cases, the pressure sensor 110 may extend a large portion of the length of the central post 108, but this is not necessary.

[0064] Because endothelialization makes removal of the left atrial appendage closure device 100 difficult, for example, a pressure sensor such as pressure sensor 110 is available that can provide an indication of average left atrial blood pressure over a period of time without requiring any onboard power, meaning there are no concerns about battery life. Physicians or other medical professionals can simply use a remote power source 20 ( Figure 1 This provides sufficient power periodically to the circuitry within the power sensor 110 to determine the average left atrial blood pressure measurement indicated by any sensing components present within the pressure sensor 110. This average left atrial blood pressure measurement can be transmitted to a remote monitoring device 26 and used by physicians or others for monitoring, diagnosis, and / or treatment of patients.

[0065] It should be understood that this disclosure is merely illustrative in many respects. Changes in detail may be made, particularly in terms of shape, size, and arrangement of steps, without departing from the scope of this disclosure. To the extent appropriate, this may include the use of any feature of one exemplary embodiment in other embodiments. Of course, the scope of the invention is defined by the language used in the appended claims.

Claims

1. An implantable pressure sensor, comprising: case; A sensing element, housed within the housing and exposed to external pressure outside the housing, wherein, in response to the external pressure, the sensing element is configured to undergo a physical transformation representing the average pressure of the external pressure over a time period of at least one minute; and The sensing component includes: A first plate, exposed to external pressure outside the housing, is configured to move in response to pressure changes within the external pressure. A second plate, spaced apart from the first plate and disposed within the housing; and A viscoelastic material disposed between the first plate and the second plate, wherein the viscoelastic material has a time constant of at least one hour, the time constant representing the rate at which the sensing element can respond to changes in input pressure; and The circuit is operable to be coupled to the sensing element and to generate an average pressure signal in response to physical changes in the sensing element, the average pressure signal representing the average pressure of the external pressure over the time period.

2. The implantable pressure sensor according to claim 1, wherein, The circuit is configured to repeatedly receive energy transfers from a remote source and, in response, transmit the average pressure signal back to the remote source.

3. The implantable pressure sensor according to claim 1 or 2, wherein, The sensing element undergoes and maintains a physical transformation without the application of power, the physical transformation representing the average pressure of the external pressure over the time period.

4. The implantable pressure sensor according to claim 1, wherein, The viscoelastic material includes a non-conductive material, and the average pressure signal represents the capacitance between the first plate and the second plate.

5. The implantable pressure sensor according to claim 1, wherein, The viscoelastic material includes a conductive material, and the average pressure signal includes an indication of the resistance between the first plate and the second plate.

6. The implantable pressure sensor according to claim 1 or 2, wherein, The sensing component includes a hydraulic sensing component.

7. The implantable pressure sensor according to claim 6, wherein, The hydraulic sensing component includes: The hydraulic chamber is exposed to the external pressure; The first fluid is disposed in the hydraulic chamber; Pressure chamber; A second fluid is disposed within the pressure chamber; A barrier is disposed between the first fluid and the second fluid; The movement of the barrier is caused by the change in pressure in the hydraulic chamber relative to the pressure chamber.

8. The implantable pressure sensor according to claim 7, wherein, The barrier includes a low-flow valve made of a highly permeable material.

9. The implantable pressure sensor according to claim 1, in, The sensing element maintains the average pressure measurement even without electrical power.

10. A left atrial appendage closure device adapted to be fitted into the left atrial appendage of a patient to substantially close the left atrial appendage of the patient, the left atrial appendage closure device comprising: Expandable frame; According to claim 1, once the sensing component is implanted in the left atrial appendage closure device, it exposes the patient's left atrial pressure within the left atrium of the heart. The sensing component includes a viscoelastic material with a time constant of at least 10 minutes, the viscoelastic material undergoing viscoelastic deformation in response to the left atrial pressure in a manner representing the average pressure of the left atrial pressure over the time period, wherein the time constant represents the rate at which the sensing component can respond to changes in input pressure; and The circuit is operable to be coupled to the sensing element and to generate an average pressure signal in response to physical changes in the sensing element, the average pressure signal representing the average pressure of the left atrial pressure over the time period.

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