WO2016/131020 and WO2017024051 are filed by the present Assignee and are incorporated by reference herein in their entirety.
The present disclosure generally relates to the field of medical devices and methods for monitoring patient blood vessels (or “vascular lumen”), such as the inferior vena cava (“IVC”).
Conditions which May be Monitored by IVC or Other Blood Vessel Monitoring
Heart failure is one of the most significant chronic conditions afflicting adult populations. In the United States, 5.7 million Americans have heart failure, with 870,000 new cases annually. As the population ages, this number is growing, as approximately 10% of the population over 80 suffers from heart failure.
In patients with chronic heart failure, significant costs are due to hospitalization to manage acutely decompensated heart failure (ADHF). Each re-hospitalization can last up to a week. ADHF is very often a result of some combination of a downturn in the heart's performance, a downturn in the kidney's removal of fluid from the bloodstream, and/or excessive intake of fluids and/or salt. This leads to a buildup of fluid in the vascular system, resulting in increased blood volume in the left atrium at higher pressure. This eventually leads to fluid filling the lungs and an inability to breathe. Managing these patients to prevent the need for re-hospitalization is extremely challenging. Non-invasive approaches to monitoring patients have been tried, such as weighing patients daily to detect fluid weight gain, or having a nurse call them daily to assess their health status, but these approaches have only modest effectiveness.
Although measurement of left atrial pressure, typically by measuring pulmonary artery wedge pressure, is commonly considered the most direct way to measure congestion in heart failure, there are other areas where congestion can be detected. When additional blood volume is added to the circulatory system, the IVC is one of the first places for that added volume to have an effect. The diameter of the IVC has demonstrated correlation with central venous pressure and right atrial pressure (as a proxy for left atrial pressure) as it flows directly into the right atrium (and by extension left atrial pressure through the connection through the pulmonary circulation), and it may correlate with renal function and renal sodium retention, which are also very important prognostic factors of heart failure. Therefore, increasing IVC volume and/or pressure may be a very effective early indicator of worsening heart condition.
In addition to heart failure patients, hemodialysis patients have a chronic need for careful volume management. Since their kidneys aren't excreting fluid, they are constantly becoming overloaded with fluid. Furthermore, large volumes of fluid are involved in the hemodialysis process, and managing patients so that they don't end up hypovolemic or overloaded with fluid requires careful management.
There are other groups of patients who might benefit from such a monitor. For example, patients in septic shock or acute shock due to trauma are subject to hypoperfusion.
Current Approaches to Monitoring the IVC or Other Blood Vessels
Prior studies of IVC dimensions have been conducted using external ultrasound imaging. This typically requires a highly trained physician or ultrasound technician to manage the ultrasound machine, ensure an appropriate connection of the transducer to the skin, position the ultrasound transducer in the appropriate location, identify the IVC, and take accurate measurements. This is not something that heart failure patients or their caregivers could typically be trained to do predictably and accurately with existing equipment. Moreover, these systems typically include large, complex, and expensive pieces of equipment which are not suitable for use outside of a specialized medical facility and are therefore not designed for serial measurements for chronic monitoring purposes.
Recent studies have indicated that the variation in IVC diameter over the respiratory cycle may be a more sensitive measurement of fluid overload and/or heart failure than simple measurement of average IVC diameter, volume, or pressure. During inspiration, intrathoracic pressure decreases, thereby increasing venous return and causing collapse of the IVC. During expiration, intrathoracic pressure increases, decreasing venous return and causing an increase in the diameter of the IVC.
While vessel dimensions may be measurable using external ultrasound, magnetic resonance imaging, computerized axial tomography, or other technologies, these imaging procedures must be administered in a hospital or other specialized facility. Furthermore, such procedures do not permit continuous monitoring, and do not allow for monitoring of the patient at their home or other remote location. As a result, the condition of a heart failure patient can worsen into a critical state before care providers become aware of it, dramatically increasing the mortality risk and cost of treatment for the patient.
PCT publication numbers WO2016/131020 and WO2017/024051, assigned to the assignee of the present disclosure, describe approaches involving implanted and catheter-based devices for real time monitoring of IVC dimensions for the diagnosis and treatment of heart failure and other conditions.
The present disclosure is directed towards providing improved apparatus for blood vessel dimension monitoring.
According to the present invention there is provided an implantable ultrasonic vascular sensor for implantation at a fixed location within a vessel, comprising:
The at least one ultrasound transducer may comprise a first transducer for transmitting an ultrasound wave and a second transducer for receiving an ultrasound echo.
The implantable ultrasonic vascular sensor may be configured for untethered retention in a vessel. In other words, there is no catheter attached to the implant after implantation. By “implantation at a fixed location” it is meant that the sensor is an implant, not a catheter.
The implantable ultrasonic vascular sensor is intended for retention in a vessel following withdrawal of a deployment catheter.
The at least one ultrasound transducer may comprise means for supporting the first transducer and the second transducer opposite one another.
The at least one ultrasound transducer may comprise means for supporting the first transducer and the second transducer adjacent each other.
The implantable ultrasonic vascular sensor may comprise means for supporting the first transducer and the second transducer back to back.
The implantable ultrasonic vascular sensor may further comprise a passive reflector attachable to a vessel wall.
The implantable ultrasonic vascular sensor may comprise a plurality of pairs of first and second transducers.
The implantable ultrasonic vascular sensor may further comprise means for supporting the plurality of pairs of first and second transducers for measuring across different chords of a vessel.
The or each transducer may be configured to transmit an ultrasound wave and receive an ultrasound echo.
The at least one transducer may be configured to provide an ultrasound wave having a beam width of between 5° and 14°.
The implantable ultrasonic vascular sensor may be configured to operate in real time for real time vessel monitoring.
The transducer drive circuit and at least one transducer may be configured to operate at a frequency in the range of 4 MHz to 20 MHz.
The transducer drive circuit and at least one transducer may be configured to operate at a frequency in the range of 7 MHz to 15 MHz.
The implantable ultrasonic vascular sensor may comprise a plurality of transducers. The drive circuit may configured to time multiplex operation of the transducers.
The implantable ultrasonic vascular sensor may further comprise a support structure for supporting the or each transducer within a vessel.
The support structure may have a stent-like configuration for engaging a vessel wall around its periphery.
At least one transducer may be longitudinally separated from a main portion of the support structure.
At least one transducer may be mounted on a strut extending longitudinally from the support structure main portion.
The strut may be mechanically biased to lie against a vessel wall.
Preferably the support structure has little impact on physiological expansion or contraction of the vessel at a sensing site. In other words, in use, the support structure and the transducer(s) move with the vessel wall. A movement of the vessel wall in a radial direction would impart a corresponding movement of the transducer(s) in a radial direction.
The strut may comprise an anchor for direct anchoring to a vessel wall.
The anchor may extend from a tip of the strut.
The strut may comprise a coating to promote adhesion to a vessel wall.
The at least one transducer may include a piezoelectric element and associated electrodes.
The at least one transducer may comprise a matching layer on an ultrasonic signal path side of the piezoelectric element and having a thickness of approximately a quarter of the wavelength of operation of the piezoelectric element.
The at least one transducer may comprise an active piezoelectric layer with a thickness of approximately a half wavelength.
The at least one transducer may have a backing material for attenuation of emitted ultrasonic waves in a direction opposed to a preferred signal direction.
The backing material may comprise a carrier material with embedded particles.
The at least one ultrasound transducer may comprise:
The implantable ultrasonic vascular sensor may further comprise means for measuring an acoustic wave time of flight between an ultrasound transmitter and an ultrasound receiver.
The implantable ultrasonic vascular sensor may further comprise means for calculating the distance between the ultrasound transmitter and the ultrasound receiver based on the measured time of flight.
In accordance with the present invention there is further provided a blood vessel monitoring system comprising at least one implantable ultrasonic vascular sensor as described above, and a remote processor configured to receive the transmitted ultrasound data and calculate distance between the ultrasound transmitter and the ultrasound receiver based on the measured time of flight.
The blood vessel monitoring system may further comprise means for determining at least one blood vessel dimension from the received data.
The blood vessel monitoring system may further comprise means for recognizing a plurality of diffuse ultrasound echo wave responses and means for determining a value representing vessel diameter or diameter changes from said responses.
The blood vessel monitoring system may further comprise means for determining at least one parameter value derived from a blood vessel dimension.
The implantable ultrasonic vascular sensor may comprise a plurality of transducers arranged to transmit and receive across different chords, and the signal processing circuit may be configured to use data from said transducers to determine blood volume and/or vessel shape.
The signal processing circuit may be configured to operate according to a desired user pattern such as intermittent or continuous or a hybrid of intermittent and continuous.
The blood vessel monitoring system may comprise a component configured to be mounted internally in the patient and an external component outside the patient's body, and said components are configured to wirelessly communicate.
The blood vessel monitoring system may comprise a subcutaneous component arranged to communicate with the implantable ultrasonic vascular sensor provide the communication link to an external component.
The blood vessel monitoring system may further comprise a discrete power source arranged to be implanted subcutaneously at a remote location separated from the vascular implant.
The blood vessel monitoring system may further comprise a discrete power source arranged to be implanted subcutaneously at a location separated from the implantable ultrasonic vascular sensor.
In accordance with the present invention there is further provided a vascular monitoring method comprising:
Implanting at least one ultrasound transducer within a vessel may comprise implanting at least one ultrasound transducer within an inferior vena cava, IVC.
The ultrasound wave may have a beam width of between 5° and 14°.
The at least one transducer may be operating at a frequency in the range of 4 MHz to 20 MHz.
The at least one transducer may be operating at a frequency in the range of 7 MHz to 15 MHz.
The method may further comprise calculating the distance between an ultrasound transmitter and an ultrasound receiver based on the time delay and wirelessly transmitting the distance.
The method may further comprise receiving the transmitted ultrasound data at a remote processor and calculating the distance between the ultrasound transmitter and the ultrasound receiver based on the time delay.
The method may further comprise determining at least one blood vessel dimension from the received data.
The method may further comprise recognizing a plurality of diffuse ultrasound echo wave responses and determining a value representing vessel diameter or diameter changes from said responses.
The method may further comprise determining at least one parameter value derived from a blood vessel dimension.
The method may further comprise using data from multiple transducers to determine blood volume and/or vessel shape.
The method may further comprise operating according to a desired user pattern such as intermittent or continuous or a hybrid of intermittent and continuous.
We describe a system for monitoring a blood vessel, the system comprising:
Preferably, the support structure has a stent-like configuration for engaging a vessel wall around its periphery. Preferably, at least one transducer is longitudinally separated from a main portion of the support structure, so that the structure main portion is substantially not in the path of ultrasonic waves and has little impact on physiologic expansion or contraction of the vessel at a sensing site.
Preferably, at least one transducer is mounted on a strut extending longitudinally from the support structure main portion.
In one example, the strut comprises an anchor for direct anchoring to a vessel wall in addition to being supported by the support structure. In one embodiment, the anchor extends from a tip of the strut.
In one example, the strut comprises a coating to promote adhesion to a vessel wall.
In some embodiments, the system comprises a passive reflector having an ultrasonic mismatch from blood, and being attachable to a vessel wall.
Preferably, the system comprises separate transducers for transmitting and receiving, in which at least one pair of transmit and receive transducers are arranged on the implant to be on opposite sides of the vessel. The system may comprise transmit and receive transducers which are separate or integrated, in which at least one transducer or transducer pair is arranged at approximately the same radial position in order to transmit an ultrasonic wave and receive a corresponding echo. In one embodiment, the sensor comprises a plurality of physically separate transducers mounted on a longitudinal strut extending from the support structure.
Preferably, the sensor comprises a plurality of pairs of transmit and receive transducers, arranged for measuring across different chords such as relatively orthogonal diameters of a vessel.
Preferably, at least one transducer includes a piezoelectric element and associated electrodes.
In one example, at least one transducer comprises a matching layer on an ultrasonic signal path side of the piezoelectric element and having a thickness of approximately a quarter of the wavelength of operation of the piezoelectric element.
Preferably, at least one transducer has an active piezoelectric layer with a thickness of approximately a half wavelength.
In one embodiment, at least one transducer has a backing material for attenuation of emitted ultrasonic waves in a direction opposed to a preferred signal direction.
Preferably, the backing material comprises a carrier material with embedded particles so that a wave emanating from the vibrating piezoelectric layer back surface in an unintended direction, such as away from a target and into the backing material, is absorbed and does not reflect back into a blood vessel in use.
In one example, at least one transducer comprises:
Preferably, the transducer provides an ultrasound wave having a beam width of between 5° and 14°.
Preferably, the sensor and the circuit are configured to operate in real time for real time vessel monitoring.
In one example, the circuits comprise a component configured to be mounted internally in the patient and an external component outside the patient's body, and said components are configured to wirelessly communicate.
Preferably, the system comprises a subcutaneous component arranged to communicate with the sensor and provide the communication link to an external component.
Preferably, the system comprises a discrete power source arranged to be implanted subcutaneously at a location separated from the vascular implant.
Preferably, the drive circuit and at least one transducer are configured to operate at a frequency in the range of 4 MHz to 20 MHz, and preferably at least 7 MHz.
In one example, the drive circuit and at least one transducer are configured to operate at a frequency in the range of 7 MHz to 15 MHz.
Preferably, the sensor comprises a plurality of transducers and the drive circuit is configured to time multiplex operation of the transducers.
Preferably, the signal processing circuit is configured to recognize a plurality of diffuse ultrasound echo wave responses and to determine a value representing vessel diameter or diameter changes from said responses.
Preferably, the signal processing circuit is configured such that received waveform undergoes a Hilbert transform, whereby the timers stop when an echo waveform envelope exceeds a certain level.
In one example, the signal processing circuit is configured to determine at least one parameter value derived from a blood vessel dimension, such as blood volume.
Preferably, the sensor comprises a plurality of transducers arranged to transmit and receive across different chords, and the signal processing circuit is configured to use data from said transducers to determine blood volume and/or vessel shape.
Preferably, the signal processing circuit is configured to operate according to a desired user pattern such as intermittent or continuous or a hybrid of intermittent and continuous.
The disclosure also provides a non-transitory computer readable medium comprising software code for performing by a digital processor operations of a drive circuit and/or a signal processing circuit of a system of any embodiment.
The disclosure will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings in which:
In various embodiments, blood vessel monitoring systems are described which include an implant with a sensor having at least one ultrasonic transducer, a data processing subsystem, a communications subsystem, and a battery power source. The transducers are supported by a stent-like support structure for both anchoring and positioning the device within a vessel such as the IVC. The support structure is flexible, elastic and highly compliant, having little influence on the normal movement and shape of the IVC.
In this specification the term “transducer” is intended to mean an ultrasound device including actively vibrating material such as a piezoelectric material and also including associated parts such as a matching layer and a backing layer. A “sensor” is an assembly of one or more transducers and all components involved for ultrasound transmitting and receiving including in some embodiments a passive reflector, as described in more detail below. The specific transducing part in which an applied voltage is transformed into mechanical vibrations is referred to as the piezoelectric material or layer.
Referring to
The system 1 also comprises a bedside console 7 wirelessly linked with the electronics housing 4 of the implant via a wireless transmitter in electronics housing and also linked with cloud servers 8, or any other data collection and processing equipment.
Support Structure 2 and Transducer Strut 5
The support structure 2 is sufficiently flexible and elastic to have little influence on the normal movement and shape of a blood vessel such as the IVC while still remaining in a fixed location in the vessel. Additionally, the longitudinal separation of the transducer 6 from support structure 2 helps to isolate it from any distortion of the vessel caused by support structure 2.
The strut 5 has a Nitinol spine alongside which are insulated electrical leads for the transducer 6.
In some embodiments, the transducer 6 and/or longitudinal strut 5 may be configured to be fixed to the vessel wall to ensure that the transducer moves with it. For example, the transducer 6 and/or the longitudinal strut, and/or the support structure 2 may have barbs, hooks, or other features on its outer side that penetrate or engage the wall tissue. The transducer 6 and/or longitudinal strut 5 may alternatively or additionally be coated with a material that adheres to tissue or encourages tissue growth around or into these components. In other embodiments the longitudinal strut 5 may have a tip extending beyond the transducer 6 and configured to penetrate into the vessel wall.
The structure 2 diameter is preferably in the range of 5 mm to 40 mm, and the length is preferably in the range of 10 mm to 40 mm. In one example the transducer 6 has a width of 4 mm, a thickness of 3 mm, and a length of 3 mm, and the tubular electronics housing 4 with domed ends, has a diameter of 5 mm and a length of 10 mm.
The ultrasound transducer 6 is positioned such that it lies on the endothelium of the IVC wall, directing ultrasound pressure waves towards the diametrically opposing side of the IVC interior wall. Due to the acoustic impedance difference between the vessel wall and blood, the IVC wall is a significant reflector of ultrasound waves. Hence, the ultrasound waves are reflected from the opposing IVC wall, returning back to the ultrasound transducer where they are detected. The time delay between the transmitted ultrasound pulse and the received echo signal is recorded, allowing for the IVC diameter to be calculated.
In various embodiments, the support structure 2 may have one, two, or more rings or hoops and interconnecting longitudinal members or struts between the hoops, the hoops being resiliently biased radially outwardly in a stent-like manner to engage the vessel wall and securely anchor the device 2-6 in the vessel. The rings or hoops may have a sinusoidal, zig-zag, or other radially collapsible configuration to facilitate delivery through the vessel to the desired location of placement and to impart a relatively consistent radial fixation force against the vessel wall over a wide range of diameters.
Ultrasound Transducer
Referring to
The piezoelectric material might be a piezoelectric ceramic, a piezoelectric single crystal or a piezoelectric composite material. The piezoelectric material may be diced in one direction or in orthogonal directions for reduction of lateral mode oscillations, due to lateral dimensions which approach a full wavelength.
In one embodiment, the piezoelectric layer is suitable to be driven at 4 MHz and has a thickness of 1.0 mm, and the other layers of the transducer raise this to a total thickness value in the range of 4 to 6 mm. In various embodiments the piezoelectric material might need to be in excess of 3 mm in width, and might preferably be made in a composite to break up lateral modes.
Up to limits, higher drive frequencies are preferred because a sharper beam is created, increasing signal strength and decreasing the possibility of echoes from parts of the vessel other than the diametrically opposed side. Higher frequencies have their limit, however. Blood attenuation is approximately 0.15 dB/MHz/cm. So, for a 2 cm diameter vessel, at 5 MHz, the attenuation is 3 dB, while at 20 MHz it is 12 dB. In the 30 MHz range, echoes from blood begin to compete in amplitude from those of tissue, and wall determination becomes yet more difficult. Therefore the preferred range of drive frequency is 4 MHz to 20 MHz, and more preferably 7 MHz to 15 MHz.
In general, the piezoelectric material thickness scales inversely proportionately to the frequency of operation.
The transducer may have a single piezoelectric crystal, or a composite “pillar” structure. The pillar transducer construction may provide a lower noise signal with better signal to noise ratio, and a relatively small aperture. A single crystal piezoelectric layer would have better amplitude conversion (voltage to displacement, and reverse) but would draw a higher current.
The matching layer 16 preferably has a thickness of a quarter wavelength.
The overall transducer may be mounted with an air gap or backing material 15 on the back side. This feature is to ensure that the waves emanating from the vibrating piezoelectric material in the unintended direction (i.e. away from the target and into the backing material), is absorbed and does not reflect back into the piezoelectric material. As shown in
The ultrasound transducer beam profile is mainly dependent on excitation pulse frequency. For example, 4 MHz with a 3 mm aperture gives a 6 dB beam width of 24°, 8 MHz gives 12°, and 10 MHz gives 9°. When targeting non planar surfaces, this can significantly affect sensor operation. There is a trade-off between beam width and angle-to-target and signal-to-noise ratio, with narrower beams providing higher signal-to-noise ratio.
Alternatively, as described in more detail below it may be preferred to rely on the echo structure from within the vessel wall to make measurements, as the strong specular reflection of the blood/wall interface may not always be achievable as compared to the diffuse echoes from within the vessel wall.
The following are exemplary aspects of the ultrasonic transducer for advantageous use in the application of monitoring width dimension of a blood vessel such as the IVC.
By way of example, for operation at 7.5 MHz, a CTS 3202HD piezoelectric ceramic with a thickness of approximately 0.3 mm (half wavelength) a surface dimension of 2.5 mm square, facing into the vessel was used. The ceramic was plated on both sides with approximately 0.2 microns of gold. The front surface matching layer material was a Henkel Loctite Stycast 3103 filled epoxy with an acoustic impedance of 4.6 MRayls, which was cast, adhesively bonded to the ceramic using EpoTek 301 epoxy, and lapped to one quarter wavelength thickness, as determined by impedance measurements. The backing material was alternatively air or a silicone rubber loaded with cork powder (acoustic impedance approximately 1.7 MRayls). 0.05 mm diameter copper leads were soldered to the opposing electrodes on the ceramic with 97:3::In:Ag solder. At approximately 30 mm from the ceramic, the leads were attached to either twisted pair wires or 50 Ohm coaxial cable for connection to the electronics.
Alternative Transducer Mounting Arrangements
A major advantage of using separate transducers for transmit and receive functions is to isolate transmit ring-down noise from the received signal. This noise would make it extremely difficult to set a meaningful threshold. Note in particular the noise on the waveforms of
A system with two transducers deployed at a longitudinal distance from each other, either supported by the same or different support structures, may also be implemented to measure a Doppler shift in the received signal. This would allow an estimate of volume flow.
It is envisaged that there may be more than two transmitter/receiver transducer pairs, e.g. up to four or more pairs of transducers, and the above benefits therefore also apply, providing even further data concerning the full volume and shape of the vessel.
It is also possible to position two transducers back-to-back near the middle of the vessel lumen. Then one transducer could be used to measure the distance to one wall, and the other could be used to measure the distance to the opposite wall. The sum of those distances is the diameter of the vessel.
A passive reflector may be provided to provide a strong reflection. This may be embedded within or individually anchored to the vessel wall opposite the transmit/receive transducer. Alternatively, a passive reflector may be mounted on a longitudinal strut attached to the support structure to which the transducer is coupled. Any such passive reflector provides increased reflectivity as compared to a blood/tissue interface.
In other embodiments there may be a co-implanted passive reflector or a second receive transducer on or within the opposing wall of the vessel. This reflector would serve to ensure a strong, perpendicular reflected signal back to the transducer. This reflector would need to be mounted so as not to impact the motion of the wall but remain in contact with it. The reflector may be on a longitudinal strut extending from the opposite side of the support structure 2, 180° apart from and parallel to the strut supporting the transmitter and receiver components. Alternatively a passive reflector may be mounted to or implanted within the wall of the vessel opposite the location of transducer. The passive reflector will be composed of a material having an impedance mismatch with vessel wall tissue and/or blood, causing a strong reflection of the transmitted ultrasound signal back to the transducer. The passive reflector may comprise a staple, button, barb, or rivet configured to penetrate or fasten to the inner wall of the vessel. Alternatively the passive reflector may comprise an injectable substance such as a flowable material, pellets, or beads which can be injected into the wall tissue.
Transducer Drive and Signal Processing
These components are within the implant electronics housing 4. The signal processor provides the wireless signals to the console 7 using Bluetooth, or an alternative local area wireless protocol. There may alternatively be a separate wireless communication interface or other wireless transceiver.
Power is provided by an implantable battery source, of a type known in the art, which is encapsulated within the housing 4. Alternatively an extra vascular power source could be used, this could be located within a subcutaneous pocket, as per implanted pacemakers, and connected to the electronics unit via a lead.
The received ultrasound signals provide data which can be processed to give a complete and accurate measurement of the IVC dimensions and further, measurements of the blood flow, blood volume, blood pressure, and possibly blood chemistry including hematocrit and oxygenation. The ultrasound echo provides data representing a diameter of the blood vessel, and from this basic data a range of derived values may be calculated as noted above.
Signal processing may involve a full waveform analysis, preferably with averaging. It may include a comparator, implemented by a System on Chip (“SOC”) or a microprocessor. The wiring may be twisted pairs or shielded coax. Alternatively, the signal processor may simply have a threshold signal intensity detector, which might require less electrical processing power.
Operation of the System and Data Analysis
The IVC contracts and expands with each respiration as well as with each cardiac cycle. Periodic IVC diameter measurements may thus be taken over multiple respiratory cycles, allowing for the recording of maximum and minimum diameters, from which a measure of collapsibility can be determined. The system may measure at any other desired intervals.
The recorded data is transmitted via radio frequency (RF) communication to the external console 6. In an alternative embodiment, some or all of the data may be locally stored on the implant. In general, the data processing, memory, and storage resources may be distributed in any suitable manner between the implant and the external equipment, provided the implant electronics unit is not excessively large, physically.
In another embodiment a subcutaneous monitor device may be provided to communicate with the implant, store the data, and to then transmit it to outside the body.
In one embodiment, the drive circuit sets a threshold, starts a timer on the transmit burst, and stops the timer on the first waveform crossing of the threshold. This number is then transmitted to the external processor. Alternatively, the received waveform undergoes a Hilbert transform, whereby the timers stop when the echo waveform envelope exceeds a certain level. This type of processing has significant advantages in signal-to-noise improvements.
Monitoring may be performed continuously or for intermittent periods, depending upon the desired trade-off between data intensity and battery life. It might be most efficient and physiologically relevant to take measurements only at night, when the patient is lying down and at rest. It might be desirable to intermittently measure IVC dimensions at random, or at specific time intervals. Although measurements may start and stop at random or preconfigured points along the respiratory cycle, it is intended that the measurement period cover multiple breathing cycles to enable IVC maxima and minima be identified.
Alternatively, the device may intermittently take continuous measurements over one or more entire cardiac and/or respiratory cycles, to get an effective measurement of the maximum and minimum IVC volumes. The difference between those minimum and maximum volumes may be an important prognostic indicator. If the overall IVC diameter is large and or there is only a small variation between minimum and maximum IVC diameters, that may be an indicator of congestion.
Referring to
A strong, well-defined received echo as in
The signal processing of either the electronics on the implant, the bedside console, or the cloud server recognise such weaker sub-responses and may use for example edge detection (especially for diameter measurement) and/or averaging (especially for diameter variation tracking) to more accurately determine vessel diameter and/or collapsibility.
By way of background regarding diffuse reflection and specular reflection, IVUS images, and even echo cardiograms, rely on diffuse echoes, and where a normal reflection occurs (in cardiology, typically at the apex of the heart), a bright ring appears on the display. It would be preferable to have more specular reflections as shown in
Alternatives
There are embodiments where multiple, separate transducers are used as dedicated transmit and receive transducers in order to reduce noise in the system. These could also be used to measure the vessel in multiple planes, thus generating a more complex and accurate shape of the vessel rather than a simple single diameter. These transducers could also be longitudinally disposed along the length of the device to provide more predictable send receive response by limiting the curvature and angulation of the vessel at the target location.
The disclosure is not limited to the embodiments described but may be varied in construction and detail.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2018/064383 | 5/31/2018 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2018/220143 | 12/6/2018 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3568661 | Franklin | Mar 1971 | A |
3838683 | Kolin | Oct 1974 | A |
4142412 | McLeod | Mar 1979 | A |
4638252 | Bradshaw | Jan 1987 | A |
RE32361 | Duggan | Feb 1987 | E |
4733669 | Segal | Mar 1988 | A |
4926875 | Rabinovitz et al. | May 1990 | A |
4947852 | Nassi et al. | Aug 1990 | A |
5127404 | Wyborny et al. | Jul 1992 | A |
5205292 | Czar et al. | Apr 1993 | A |
5316001 | Ferek-Petric et al. | May 1994 | A |
5339816 | Akamatsu et al. | Aug 1994 | A |
5363848 | Spani et al. | Nov 1994 | A |
5476484 | Hedberg | Dec 1995 | A |
5495852 | Stadler et al. | Mar 1996 | A |
5630836 | Prem et al. | May 1997 | A |
5752522 | Murphy | May 1998 | A |
5872520 | Siefert et al. | Feb 1999 | A |
5902308 | Murphy | May 1999 | A |
5967986 | Cimochowski | Oct 1999 | A |
5971933 | Gopakumaran | Oct 1999 | A |
6010511 | Murphy | Jan 2000 | A |
6012457 | Lesh | Jan 2000 | A |
6015386 | Kensey et al. | Jan 2000 | A |
6025725 | Gershenfeld et al. | Feb 2000 | A |
6039701 | Sliwa et al. | Mar 2000 | A |
6053873 | Govari et al. | Apr 2000 | A |
6111520 | Allen et al. | Aug 2000 | A |
6115633 | Lang et al. | Sep 2000 | A |
6115636 | Ryan | Sep 2000 | A |
6164283 | Lesh | Dec 2000 | A |
6206835 | Spillman, Jr. et al. | Mar 2001 | B1 |
6231516 | Keilman | May 2001 | B1 |
6261233 | Kantorovich | Jul 2001 | B1 |
6278379 | Allen et al. | Aug 2001 | B1 |
6287253 | Ortega et al. | Sep 2001 | B1 |
6325762 | Tjin | Dec 2001 | B1 |
6339816 | Bausch | Jan 2002 | B1 |
6354999 | Dgany et al. | Mar 2002 | B1 |
6398734 | Cimochowski et al. | Jun 2002 | B1 |
6434411 | Duret | Aug 2002 | B1 |
6503202 | Hossack et al. | Jan 2003 | B1 |
6574510 | Von Arx et al. | Jun 2003 | B2 |
6673020 | Okada et al. | Jan 2004 | B2 |
6699186 | Wolinsky et al. | Mar 2004 | B1 |
6738671 | Christophersom et al. | May 2004 | B2 |
6776763 | Nix | Aug 2004 | B2 |
6802811 | Slepian | Oct 2004 | B1 |
6855115 | Fonseca | Feb 2005 | B2 |
6895265 | Silver | May 2005 | B2 |
6926670 | Rich et al. | Aug 2005 | B2 |
6972553 | Petrovich et al. | Dec 2005 | B2 |
7065409 | Mazar | Jun 2006 | B2 |
7077812 | Naghavi | Jul 2006 | B2 |
7082330 | Stadler et al. | Jul 2006 | B2 |
7147604 | Allen | Dec 2006 | B1 |
7149587 | Wardle et al. | Dec 2006 | B2 |
7191013 | Miranda et al. | Mar 2007 | B1 |
7225032 | Schmeling et al. | May 2007 | B2 |
7233821 | Hettrick et al. | Jun 2007 | B2 |
7236821 | Cates et al. | Jun 2007 | B2 |
7245117 | Joy | Jul 2007 | B1 |
7284442 | Fleischman et al. | Oct 2007 | B2 |
7367984 | Kulcinski et al. | May 2008 | B2 |
7423496 | Scheuermann | Sep 2008 | B2 |
7432723 | Ellis | Oct 2008 | B2 |
7439723 | Allen | Oct 2008 | B2 |
7444878 | Pepples | Nov 2008 | B1 |
7452334 | Gianchandani et al. | Nov 2008 | B2 |
7454244 | Kassab et al. | Nov 2008 | B2 |
7466120 | Miller | Dec 2008 | B2 |
7479112 | Sweeney et al. | Jan 2009 | B2 |
7481771 | Fonseca | Jan 2009 | B2 |
7492144 | Powers | Feb 2009 | B2 |
7498799 | Allen | Mar 2009 | B2 |
7550978 | Joy | Jun 2009 | B2 |
7574792 | O'Brien | Aug 2009 | B2 |
7595647 | Kroh | Sep 2009 | B2 |
7618363 | Yadav | Nov 2009 | B2 |
7621036 | Cros | Nov 2009 | B2 |
7621876 | Hoctor et al. | Nov 2009 | B2 |
7647831 | Corcoran | Jan 2010 | B2 |
7647836 | O'Brien | Jan 2010 | B2 |
7662653 | O'Brien | Feb 2010 | B2 |
7667547 | Ellis | Feb 2010 | B2 |
7677107 | Nunez | Mar 2010 | B2 |
7678135 | Maahs et al. | Mar 2010 | B2 |
7679355 | Allen | Mar 2010 | B2 |
7699059 | Fonseca | Apr 2010 | B2 |
7710103 | Powers | May 2010 | B2 |
7725160 | Weber | May 2010 | B2 |
7748277 | O'Brien | Jul 2010 | B2 |
7778684 | Weber et al. | Aug 2010 | B2 |
7786867 | Hamel et al. | Aug 2010 | B2 |
7812416 | Courcimault | Oct 2010 | B2 |
7829363 | You | Nov 2010 | B2 |
7839153 | Joy | Nov 2010 | B2 |
7848813 | Bergelson et al. | Dec 2010 | B2 |
7854172 | O'Brien | Dec 2010 | B2 |
7908002 | Hoijer | Mar 2011 | B2 |
7908018 | O'Brien | Mar 2011 | B2 |
7909770 | Stern | Mar 2011 | B2 |
7932732 | Ellis | Apr 2011 | B2 |
7936174 | Ellis | May 2011 | B2 |
7955269 | Stahmann | Jun 2011 | B2 |
7966886 | Corcoran | Jun 2011 | B2 |
7988719 | Alt et al. | Aug 2011 | B2 |
8016766 | Goedje et al. | Sep 2011 | B2 |
8021307 | White | Sep 2011 | B2 |
8025625 | Allen | Sep 2011 | B2 |
8026729 | Kroh | Sep 2011 | B2 |
8060214 | Larson et al. | Nov 2011 | B2 |
8078274 | Kassab | Dec 2011 | B2 |
8082032 | Kassab et al. | Dec 2011 | B2 |
8099161 | Kassab | Jan 2012 | B2 |
8107248 | Shin et al. | Jan 2012 | B2 |
8111150 | Miller | Feb 2012 | B2 |
8114143 | Kassab et al. | Feb 2012 | B2 |
8118749 | White | Feb 2012 | B2 |
8154389 | Rowland | Apr 2012 | B2 |
8159348 | Ellis | Apr 2012 | B2 |
8185194 | Kassab | May 2012 | B2 |
8209033 | Zhang et al. | Jun 2012 | B2 |
8221405 | Whisenant et al. | Jul 2012 | B2 |
8237451 | Joy | Aug 2012 | B2 |
8264240 | Park | Sep 2012 | B2 |
8267954 | Decant, Jr. et al. | Sep 2012 | B2 |
8278941 | Kroh | Oct 2012 | B2 |
8298147 | Huennekens et al. | Oct 2012 | B2 |
8298148 | Furman | Oct 2012 | B2 |
8353841 | White | Jan 2013 | B2 |
8355777 | White | Jan 2013 | B2 |
8356399 | Kaplan | Jan 2013 | B2 |
8360984 | Yadar | Jan 2013 | B2 |
8374689 | Gopinathan et al. | Feb 2013 | B2 |
8432265 | Rowland | Apr 2013 | B2 |
8442606 | Furman | May 2013 | B2 |
8442639 | Walker et al. | May 2013 | B2 |
8465436 | Griswold | Jun 2013 | B2 |
8465452 | Kassab | Jun 2013 | B2 |
8467854 | Lewis et al. | Jun 2013 | B2 |
8493187 | Rowland | Jul 2013 | B2 |
8500660 | Buchwald et al. | Aug 2013 | B2 |
8521282 | Czygan et al. | Aug 2013 | B2 |
8527046 | Connelly et al. | Sep 2013 | B2 |
8556929 | Harper et al. | Oct 2013 | B2 |
8570186 | Nagy | Oct 2013 | B2 |
8600517 | Forsell | Dec 2013 | B2 |
8613705 | Scheurer | Dec 2013 | B2 |
8632469 | Kassab | Jan 2014 | B2 |
8644941 | Rooney et al. | Feb 2014 | B2 |
8665086 | Miner | Mar 2014 | B2 |
8669770 | Cros | Mar 2014 | B2 |
8696584 | Kassab | Apr 2014 | B2 |
8702613 | Kassab | Apr 2014 | B2 |
8706208 | Chiao et al. | Apr 2014 | B2 |
8706209 | Kassab | Apr 2014 | B2 |
8706219 | Feldman | Apr 2014 | B2 |
8728012 | Braido | May 2014 | B2 |
8784338 | Wallace | Jul 2014 | B2 |
8798712 | Gopinathan et al. | Aug 2014 | B2 |
8814798 | Corbucci et al. | Aug 2014 | B2 |
8818507 | Liu et al. | Aug 2014 | B2 |
8825151 | Gopinathan et al. | Sep 2014 | B2 |
8827929 | O'Dea | Sep 2014 | B2 |
8855783 | Dagan et al. | Oct 2014 | B2 |
8864666 | Kassem | Oct 2014 | B2 |
8870787 | Yadav | Oct 2014 | B2 |
8874203 | Kassab et al. | Oct 2014 | B2 |
8886301 | Kassab | Nov 2014 | B2 |
8894582 | Nunez | Nov 2014 | B2 |
8896324 | Kroh | Nov 2014 | B2 |
8909351 | Dinsmoor et al. | Dec 2014 | B2 |
8918169 | Kassab et al. | Dec 2014 | B2 |
8938292 | Hettrick et al. | Jan 2015 | B2 |
8951219 | Gerber et al. | Feb 2015 | B2 |
9049995 | Blomqvist et al. | Jun 2015 | B2 |
9060798 | Harper et al. | Jun 2015 | B2 |
9061099 | Gerber et al. | Jun 2015 | B2 |
9066672 | Kassab et al. | Jun 2015 | B2 |
9162065 | Karst et al. | Oct 2015 | B2 |
9198706 | Kassab et al. | Dec 2015 | B2 |
9265428 | O'Brien et al. | Feb 2016 | B2 |
9289132 | Ghaffari et al. | Mar 2016 | B2 |
9289229 | Kassab | Mar 2016 | B2 |
9305456 | Rowland | Apr 2016 | B2 |
9314169 | Kassab | Apr 2016 | B2 |
9326728 | Demir et al. | May 2016 | B2 |
9332914 | Langston | May 2016 | B2 |
9332916 | Kassab | May 2016 | B2 |
9333365 | Zhao | May 2016 | B2 |
9351661 | Kassab | May 2016 | B2 |
9393416 | Rooney et al. | Jul 2016 | B2 |
9445743 | Kassab | Sep 2016 | B2 |
9489831 | Nagy et al. | Nov 2016 | B2 |
9526637 | Dagan et al. | Dec 2016 | B2 |
9545263 | Lenihan | Jan 2017 | B2 |
9603533 | Lading et al. | Mar 2017 | B2 |
9662066 | Ledet et al. | May 2017 | B2 |
9675257 | Kassab | Jun 2017 | B2 |
9675315 | Song et al. | Jun 2017 | B2 |
9721463 | Rowland | Aug 2017 | B2 |
9814395 | Stahmann et al. | Nov 2017 | B2 |
9820673 | Feldman | Nov 2017 | B2 |
9872948 | Siess | Jan 2018 | B2 |
9878080 | Kaiser et al. | Jan 2018 | B2 |
9901722 | Nitzan et al. | Feb 2018 | B2 |
9996712 | Sundaram et al. | Jun 2018 | B2 |
10080528 | BeBusschere et al. | Sep 2018 | B2 |
10092247 | Taylor | Oct 2018 | B2 |
10105103 | Goldshtein et al. | Oct 2018 | B2 |
10194808 | Thompson | Feb 2019 | B1 |
10195441 | Kaiser | Feb 2019 | B2 |
10201285 | Sawanoi | Feb 2019 | B2 |
10210956 | Lavi | Feb 2019 | B2 |
10213129 | Kassab | Feb 2019 | B2 |
10219704 | Avi | Mar 2019 | B2 |
10219720 | Kassab | Mar 2019 | B2 |
10219724 | Stern | Mar 2019 | B2 |
10226203 | Stigall | Mar 2019 | B2 |
10226218 | Rowland | Mar 2019 | B2 |
10231659 | Vanslyke | Mar 2019 | B2 |
10231701 | Ryan | Mar 2019 | B2 |
10236084 | Grady | Mar 2019 | B2 |
10238311 | Kassab | Mar 2019 | B2 |
10238322 | Vanslyke | Mar 2019 | B2 |
10238323 | Vanslyke | Mar 2019 | B2 |
10238324 | Vanslyke | Mar 2019 | B2 |
10240994 | Xu | Mar 2019 | B1 |
10265024 | Lee | Apr 2019 | B2 |
10271797 | Zhang | Apr 2019 | B2 |
10335042 | Schoenie et al. | Jul 2019 | B2 |
10390714 | Wolinsky | Aug 2019 | B2 |
10433736 | Karlovsky et al. | Oct 2019 | B2 |
10537281 | Thompson et al. | Jan 2020 | B2 |
10542887 | Sarkar et al. | Jan 2020 | B2 |
10660577 | Thakur et al. | Jan 2020 | B2 |
10548535 | Zhang et al. | Feb 2020 | B2 |
10555704 | Averina et al. | Feb 2020 | B2 |
10582866 | Badie et al. | Mar 2020 | B2 |
10588528 | Banet et al. | Mar 2020 | B2 |
10595734 | Thakur et al. | Mar 2020 | B2 |
10596381 | Averina et al. | Mar 2020 | B2 |
10638980 | Gyllensten et al. | May 2020 | B2 |
10687715 | Jansen et al. | Jun 2020 | B2 |
10702213 | Sharma et al. | Jul 2020 | B2 |
10806352 | Sweeney et al. | Oct 2020 | B2 |
10905393 | Gifford, III et al. | Feb 2021 | B2 |
11006845 | Kuraguntla et al. | May 2021 | B2 |
11039813 | Gifford, III et al. | Jun 2021 | B2 |
11272840 | Rothfuss | Mar 2022 | B2 |
11445924 | Joseph | Sep 2022 | B2 |
11452497 | Garza | Sep 2022 | B2 |
20020120205 | Ferek-Petric | Aug 2002 | A1 |
20020188207 | Richter | Dec 2002 | A1 |
20030037591 | Ashton et al. | Feb 2003 | A1 |
20030100940 | Yodfat | May 2003 | A1 |
20030158584 | Cates et al. | Aug 2003 | A1 |
20030199938 | Smits et al. | Oct 2003 | A1 |
20040054287 | Stephens | Mar 2004 | A1 |
20040106871 | Hunyor et al. | Jun 2004 | A1 |
20040116992 | Wardle | Jun 2004 | A1 |
20040133092 | Kain | Jul 2004 | A1 |
20040140939 | Haller et al. | Jul 2004 | A1 |
20040167596 | Richter | Aug 2004 | A1 |
20040176672 | Silver et al. | Sep 2004 | A1 |
20040215235 | Jackson et al. | Oct 2004 | A1 |
20040225326 | Weiner | Nov 2004 | A1 |
20050137481 | Sheard et al. | Jun 2005 | A1 |
20050148903 | Diamantopoulos | Jul 2005 | A1 |
20050154321 | Wolinsky | Jul 2005 | A1 |
20060047327 | Colvin et al. | Mar 2006 | A1 |
20060056161 | Shin | Mar 2006 | A1 |
20060079793 | Mann et al. | Apr 2006 | A1 |
20060100522 | Yuan | May 2006 | A1 |
20060106321 | Lewinsky et al. | May 2006 | A1 |
20060122522 | Chavan et al. | Jun 2006 | A1 |
20060149166 | Zvuloni | Jul 2006 | A1 |
20060174712 | O'Brien | Aug 2006 | A1 |
20060177956 | O'Brien | Aug 2006 | A1 |
20060178695 | Decant | Aug 2006 | A1 |
20060253160 | Benditt et al. | Nov 2006 | A1 |
20060271119 | Ni et al. | Nov 2006 | A1 |
20060280351 | Luping et al. | Dec 2006 | A1 |
20060287602 | Obrien et al. | Dec 2006 | A1 |
20060287700 | White | Dec 2006 | A1 |
20070088214 | Shuros | Apr 2007 | A1 |
20070129637 | Wolinsky et al. | Jun 2007 | A1 |
20070158769 | You | Jul 2007 | A1 |
20070199385 | O'Brien | Aug 2007 | A1 |
20070249950 | Piaget et al. | Oct 2007 | A1 |
20070274565 | Penner | Nov 2007 | A1 |
20070282210 | Stern | Dec 2007 | A1 |
20070292090 | Alphonse et al. | Dec 2007 | A1 |
20080015569 | Saadat | Jan 2008 | A1 |
20080033527 | Nunez et al. | Feb 2008 | A1 |
20080077016 | Sparks | Mar 2008 | A1 |
20080097227 | Zdeblick et al. | Apr 2008 | A1 |
20080177186 | Slater et al. | Jul 2008 | A1 |
20080275350 | Liao | Nov 2008 | A1 |
20080294041 | Kassab | Nov 2008 | A1 |
20090007679 | Nunez | Jan 2009 | A1 |
20090009332 | Nunez | Jan 2009 | A1 |
20090011117 | Nunez | Jan 2009 | A1 |
20090024042 | Nunez | Jan 2009 | A1 |
20090024177 | Shuros et al. | Jan 2009 | A1 |
20090030291 | O'Brien | Jan 2009 | A1 |
20090036776 | Masuda et al. | Feb 2009 | A1 |
20090062684 | Gregersen et al. | Mar 2009 | A1 |
20090105799 | Hekmat et al. | Apr 2009 | A1 |
20090149766 | Shuros et al. | Jun 2009 | A1 |
20090177225 | Nunez et al. | Jul 2009 | A1 |
20090189741 | Rowland | Jul 2009 | A1 |
20090198293 | Cauller | Aug 2009 | A1 |
20090270729 | Corbucci | Oct 2009 | A1 |
20090299427 | Liu et al. | Dec 2009 | A1 |
20100056922 | Florent | Mar 2010 | A1 |
20100063375 | Kassab et al. | Mar 2010 | A1 |
20100076398 | Scheurer | Mar 2010 | A1 |
20100094328 | O'dea et al. | Apr 2010 | A1 |
20100113939 | Mashimo et al. | May 2010 | A1 |
20100121398 | Bjorling et al. | May 2010 | A1 |
20100222786 | Kassab | Sep 2010 | A1 |
20100262206 | Zdeblick et al. | Oct 2010 | A1 |
20100274217 | Da Silva et al. | Oct 2010 | A1 |
20100324432 | Bjorling et al. | Dec 2010 | A1 |
20110054333 | Hoffer | Mar 2011 | A1 |
20110105863 | Kroh | May 2011 | A1 |
20110144967 | Adirovich | Jun 2011 | A1 |
20110160844 | Haselby | Jun 2011 | A1 |
20110178383 | Kassab | Jul 2011 | A1 |
20110184301 | Holmstrom et al. | Jul 2011 | A1 |
20110201990 | Franano | Aug 2011 | A1 |
20110224582 | Spence | Sep 2011 | A1 |
20110265908 | Clerc et al. | Nov 2011 | A1 |
20110306867 | Gopinathan et al. | Dec 2011 | A1 |
20120016207 | Allen | Jan 2012 | A1 |
20120029598 | Zhao | Feb 2012 | A1 |
20120136385 | Cully | May 2012 | A1 |
20120203090 | Min | Aug 2012 | A1 |
20120203113 | Skerl et al. | Aug 2012 | A1 |
20120291788 | Griswold et al. | Nov 2012 | A1 |
20120296222 | Griswold et al. | Nov 2012 | A1 |
20130030295 | Huennekens et al. | Jan 2013 | A1 |
20130041244 | Woias et al. | Feb 2013 | A1 |
20130041251 | Bailey et al. | Feb 2013 | A1 |
20130041269 | Stahmann et al. | Feb 2013 | A1 |
20130060139 | Richter | Mar 2013 | A1 |
20130073025 | Kassab | Mar 2013 | A1 |
20130085350 | Schugt | Apr 2013 | A1 |
20130096409 | Hiltner et al. | Apr 2013 | A1 |
20130178750 | Sheehan et al. | Jul 2013 | A1 |
20130178751 | Min | Jul 2013 | A1 |
20130184545 | Blomqvist et al. | Jul 2013 | A1 |
20130218054 | Sverdlik et al. | Aug 2013 | A1 |
20130222153 | Rowland et al. | Aug 2013 | A1 |
20130245469 | Yadav | Sep 2013 | A1 |
20130245745 | Vong et al. | Sep 2013 | A1 |
20130261655 | Drasler et al. | Oct 2013 | A1 |
20130274705 | Burnes et al. | Oct 2013 | A1 |
20130281800 | Saroka et al. | Oct 2013 | A1 |
20130296721 | Yadav et al. | Nov 2013 | A1 |
20130303914 | Hiltner et al. | Nov 2013 | A1 |
20130303915 | Barnard et al. | Nov 2013 | A1 |
20130310820 | Fernandez et al. | Nov 2013 | A1 |
20130317359 | Wilson et al. | Nov 2013 | A1 |
20130324866 | Gladshtein | Dec 2013 | A1 |
20130331678 | Lading et al. | Dec 2013 | A1 |
20130338468 | Kassab | Dec 2013 | A1 |
20140028467 | Nagy | Jan 2014 | A1 |
20140051965 | Zdeblick et al. | Feb 2014 | A1 |
20140066738 | Kassab | Mar 2014 | A1 |
20140073935 | Rodriguez-Llorente | Mar 2014 | A1 |
20140084943 | Kroh | Mar 2014 | A1 |
20140088994 | Kroh | Mar 2014 | A1 |
20140094697 | Petroff et al. | Apr 2014 | A1 |
20140107768 | Venkatasubramanian | Apr 2014 | A1 |
20140155710 | Rowland | Jun 2014 | A1 |
20140155768 | Orion et al. | Jun 2014 | A1 |
20140155769 | White | Jun 2014 | A1 |
20140180118 | Stigall | Jun 2014 | A1 |
20140200428 | Kassab | Jul 2014 | A1 |
20140236011 | Fan et al. | Aug 2014 | A1 |
20140243640 | O'Dea | Aug 2014 | A1 |
20140266935 | Tankiewicz | Sep 2014 | A1 |
20140275861 | Kroh | Sep 2014 | A1 |
20140276011 | Schmitt et al. | Sep 2014 | A1 |
20140276067 | Neasham | Sep 2014 | A1 |
20140276110 | Hoseit | Sep 2014 | A1 |
20140276121 | Kassab | Sep 2014 | A1 |
20140276191 | Kassab | Sep 2014 | A1 |
20140288085 | Yadav | Sep 2014 | A1 |
20140288459 | Yadav | Sep 2014 | A1 |
20140306807 | Rowland | Oct 2014 | A1 |
20140330143 | Kroh et al. | Nov 2014 | A1 |
20140350348 | Tee et al. | Nov 2014 | A1 |
20150031966 | Ward et al. | Jan 2015 | A1 |
20150045649 | O'Dea et al. | Feb 2015 | A1 |
20150051467 | Corbucci et al. | Feb 2015 | A1 |
20150065835 | Kassab | Mar 2015 | A1 |
20150065897 | Bomzin et al. | Mar 2015 | A1 |
20150088100 | Oborn | Mar 2015 | A1 |
20150133796 | Yadav | May 2015 | A1 |
20150141863 | Kassab et al. | May 2015 | A1 |
20150157268 | Winshtein et al. | Jun 2015 | A1 |
20150208929 | Rowland | Jul 2015 | A1 |
20150216425 | Gladshtein et al. | Aug 2015 | A1 |
20150223702 | Vanney et al. | Aug 2015 | A1 |
20150238121 | Tu et al. | Aug 2015 | A1 |
20150257732 | Ryan | Sep 2015 | A1 |
20150282720 | Goldshtein et al. | Oct 2015 | A1 |
20150282875 | Harper et al. | Oct 2015 | A1 |
20150290373 | Rudser et al. | Oct 2015 | A1 |
20150297110 | Kassab | Oct 2015 | A1 |
20150297111 | Kassab | Oct 2015 | A1 |
20150297112 | Kassab et al. | Oct 2015 | A1 |
20150297113 | Kassab | Oct 2015 | A1 |
20150297818 | Matsubara et al. | Oct 2015 | A1 |
20150305808 | Ku et al. | Oct 2015 | A1 |
20150313479 | Stigall et al. | Nov 2015 | A1 |
20150327786 | Lading et al. | Nov 2015 | A1 |
20160000403 | Vilkomerson | Jan 2016 | A1 |
20160015507 | Johnson et al. | Jan 2016 | A1 |
20160022216 | Goldshtein et al. | Jan 2016 | A1 |
20160022447 | Kim et al. | Jan 2016 | A1 |
20160029956 | Rowland | Feb 2016 | A1 |
20160029995 | Navratil et al. | Feb 2016 | A1 |
20160038087 | Hunter | Feb 2016 | A1 |
20160045184 | Courtney | Feb 2016 | A1 |
20160081657 | Rice | Mar 2016 | A1 |
20160095535 | Hettrick et al. | Apr 2016 | A1 |
20160135787 | Anderson et al. | May 2016 | A1 |
20160135941 | Binmoeller et al. | May 2016 | A1 |
20160166232 | Merritt | Jun 2016 | A1 |
20160198981 | Demir et al. | Jul 2016 | A1 |
20160210846 | Rowland et al. | Jul 2016 | A1 |
20160324443 | Rowland et al. | Nov 2016 | A1 |
20160345930 | Mizukami | Dec 2016 | A1 |
20170055048 | Nagy et al. | Feb 2017 | A1 |
20170055909 | Schibli et al. | Mar 2017 | A1 |
20170065186 | Joseph | Mar 2017 | A1 |
20170071501 | Kassab | Mar 2017 | A1 |
20170127975 | Bozkurt | May 2017 | A1 |
20170164840 | Matsumoto | Jun 2017 | A1 |
20170181677 | Varsavsky et al. | Jun 2017 | A1 |
20170065824 | Dagan et al. | Aug 2017 | A1 |
20170216508 | Zilbershlag et al. | Aug 2017 | A1 |
20170224279 | Cahan | Aug 2017 | A1 |
20170238817 | Lading | Aug 2017 | A1 |
20170290686 | Sirhan et al. | Oct 2017 | A1 |
20170319096 | Kaiser | Nov 2017 | A1 |
20170332945 | Gopinathan et al. | Nov 2017 | A1 |
20170340440 | Ratz | Nov 2017 | A1 |
20170360312 | Joseph | Dec 2017 | A1 |
20180014829 | Tal et al. | Jan 2018 | A1 |
20180064931 | Clements | Mar 2018 | A1 |
20180092631 | Liou | Apr 2018 | A1 |
20180172785 | Leussler et al. | Jun 2018 | A1 |
20180177486 | Gifford et al. | Jun 2018 | A1 |
20180220992 | Gifford et al. | Aug 2018 | A1 |
20180228951 | Schwammenthal et al. | Aug 2018 | A1 |
20180247095 | Sundaram et al. | Aug 2018 | A1 |
20180268941 | Lavi et al. | Sep 2018 | A1 |
20180269931 | Hershko et al. | Sep 2018 | A1 |
20180271371 | Ziaie et al. | Sep 2018 | A1 |
20180289488 | Orth et al. | Oct 2018 | A1 |
20180289536 | Burnett | Oct 2018 | A1 |
20180293409 | Sundaram et al. | Oct 2018 | A1 |
20180326151 | Halpert et al. | Nov 2018 | A1 |
20180344917 | Inhaber et al. | Dec 2018 | A1 |
20190029639 | Gifford et al. | Jan 2019 | A1 |
20190046047 | Haase | Feb 2019 | A1 |
20190053720 | Sawado | Feb 2019 | A1 |
20190053767 | Yamada | Feb 2019 | A1 |
20190069784 | Mukkamala | Mar 2019 | A1 |
20190069842 | Rothberg | Mar 2019 | A1 |
20190069851 | Sharma | Mar 2019 | A1 |
20190070348 | Frost | Mar 2019 | A1 |
20190076033 | Sweeney et al. | Mar 2019 | A1 |
20190082978 | Van der Horst | Mar 2019 | A1 |
20190083030 | Thakur | Mar 2019 | A1 |
20190090760 | Kinast | Mar 2019 | A1 |
20190090763 | Woerlee | Mar 2019 | A1 |
20190090856 | Van der Horst | Mar 2019 | A1 |
20190099087 | Cros | Apr 2019 | A1 |
20190099088 | Whinnett | Apr 2019 | A1 |
20190110696 | Benkowski | Apr 2019 | A1 |
20190126014 | Kapur et al. | May 2019 | A1 |
20190150884 | Maharbiz et al. | May 2019 | A1 |
20190167188 | Gifford et al. | Jun 2019 | A1 |
20200000364 | Doodeman et al. | Jan 2020 | A1 |
20200013510 | Despenic et al. | Jan 2020 | A1 |
20200022588 | Wariar et al. | Jan 2020 | A1 |
20200022589 | Banet et al. | Jan 2020 | A1 |
20200029829 | Banet et al. | Jan 2020 | A1 |
20200029857 | Rowland et al. | Jan 2020 | A1 |
20200030612 | Song et al. | Jan 2020 | A1 |
20200037888 | Thakur et al. | Feb 2020 | A1 |
20200037892 | Banet et al. | Feb 2020 | A1 |
20200046299 | An et al. | Feb 2020 | A1 |
20200069857 | Schwammenthal et al. | Mar 2020 | A1 |
20200121187 | Sarkar et al. | Apr 2020 | A1 |
20200129087 | Sweeney et al. | Apr 2020 | A1 |
20200146577 | Badie et al. | May 2020 | A1 |
20200170515 | Wen et al. | Jun 2020 | A1 |
20200170711 | Hendriks et al. | Jun 2020 | A1 |
20200187864 | Sharma | Jun 2020 | A1 |
20200187865 | Sharma et al. | Jun 2020 | A1 |
20200196876 | Minor et al. | Jun 2020 | A1 |
20200196899 | Higgins et al. | Jun 2020 | A1 |
20200196943 | Minor et al. | Jun 2020 | A1 |
20200196944 | Minor et al. | Jun 2020 | A1 |
20200196948 | Cho et al. | Jun 2020 | A1 |
20200197178 | Vecchio | Jun 2020 | A1 |
20200254161 | Schwammenthal et al. | Aug 2020 | A1 |
20200289257 | Marquez | Sep 2020 | A1 |
20210038094 | Sweeney et al. | Feb 2021 | A1 |
20210060298 | Arndt et al. | Mar 2021 | A1 |
20210177277 | Cros et al. | Jun 2021 | A1 |
20210216733 | Chronos et al. | Jul 2021 | A1 |
20210244381 | Sweeney et al. | Aug 2021 | A1 |
20220071488 | Andersen et al. | Mar 2022 | A1 |
20220125312 | Nazari et al. | Apr 2022 | A1 |
20220233084 | Valdez | Jul 2022 | A1 |
20220240792 | Wetterling | Aug 2022 | A1 |
20220265157 | Charthad | Aug 2022 | A1 |
Number | Date | Country |
---|---|---|
110613449 | May 2020 | CN |
102005035022 | Nov 2006 | DE |
0399059 | May 1989 | EP |
0538885 | Apr 1993 | EP |
0897285 | Feb 1999 | EP |
1162914 | Dec 2001 | EP |
1311210 | May 2003 | EP |
0904009 | Sep 2003 | EP |
1545303 | Jun 2005 | EP |
1677852 | Jul 2006 | EP |
1847217 | Oct 2007 | EP |
1851524 | Nov 2007 | EP |
1851791 | Nov 2007 | EP |
1868496 | Dec 2007 | EP |
1871224 | Jan 2008 | EP |
1893080 | Mar 2008 | EP |
1893081 | Mar 2008 | EP |
1893085 | Mar 2008 | EP |
2091426 | Jun 2008 | EP |
1948007 | Jul 2008 | EP |
1993438 | Nov 2008 | EP |
2012658 | Jan 2009 | EP |
2046242 | Apr 2009 | EP |
2117423 | Nov 2009 | EP |
2197344 | Jun 2010 | EP |
2265164 | Dec 2010 | EP |
2021757 | Apr 2011 | EP |
2391263 | Dec 2011 | EP |
1921983 | Jan 2012 | EP |
2060014 | Jan 2012 | EP |
1902529 | Jun 2012 | EP |
1876945 | Dec 2012 | EP |
2330968 | Apr 2013 | EP |
2601633 | Jun 2013 | EP |
2449960 | Oct 2013 | EP |
2725969 | May 2014 | EP |
1993436 | Jun 2014 | EP |
3027109 | Feb 2015 | EP |
2076170 | Apr 2015 | EP |
2895059 | Jul 2015 | EP |
2898470 | Jul 2015 | EP |
2922465 | Sep 2015 | EP |
2317912 | Nov 2015 | EP |
1817593 | Dec 2015 | EP |
2967432 | Jan 2016 | EP |
2268218 | Feb 2016 | EP |
2456502 | Apr 2016 | EP |
2702578 | Aug 2016 | EP |
3057075 | Aug 2016 | EP |
2417590 | May 2017 | EP |
2986252 | Jul 2018 | EP |
3359021 | Aug 2018 | EP |
3435847 | Feb 2019 | EP |
3435862 | Feb 2019 | EP |
3437000 | Feb 2019 | EP |
3448330 | Mar 2019 | EP |
3448487 | Mar 2019 | EP |
3457911 | Mar 2019 | EP |
3457924 | Mar 2019 | EP |
3457928 | Mar 2019 | EP |
3463082 | Apr 2019 | EP |
3468462 | Apr 2019 | EP |
3591663 | Jan 2020 | EP |
3609392 | Feb 2020 | EP |
3256043 | Mar 2020 | EP |
3629921 | Apr 2020 | EP |
3629937 | Apr 2020 | EP |
3630275 | Apr 2020 | EP |
3634206 | Apr 2020 | EP |
3654835 | May 2020 | EP |
3496808 | Jun 2020 | EP |
2654560 | Jul 2020 | EP |
3326524 | Jul 2020 | EP |
3367884 | Jul 2020 | EP |
3678539 | Jul 2020 | EP |
3681389 | Jul 2020 | EP |
3684260 | Jul 2020 | EP |
3684464 | Jul 2020 | EP |
2155307 | Mar 2021 | EP |
4039173 | Aug 2022 | EP |
2473529 | Mar 2011 | GB |
2011234884 | Nov 2011 | JP |
1997042871 | Nov 1997 | WO |
1998029030 | Dec 1997 | WO |
1998035611 | Aug 1998 | WO |
2000055579 | Sep 2000 | WO |
2000056210 | Sep 2000 | WO |
2001012092 | Feb 2001 | WO |
2001013792 | Mar 2001 | WO |
2002015823 | Feb 2002 | WO |
2002076289 | Oct 2002 | WO |
2003061467 | Jul 2003 | WO |
2003061504 | Jul 2003 | WO |
2003092495 | Nov 2003 | WO |
2004014456 | Feb 2004 | WO |
2004073796 | Sep 2004 | WO |
2006049796 | May 2006 | WO |
2006086113 | Aug 2006 | WO |
2006086114 | Aug 2006 | WO |
2005027998 | Sep 2006 | WO |
2006094273 | Sep 2006 | WO |
2006096582 | Sep 2006 | WO |
2006102905 | Oct 2006 | WO |
2006110798 | Oct 2006 | WO |
2006025215 | Nov 2006 | WO |
2007002185 | Jan 2007 | WO |
2007002224 | Jan 2007 | WO |
2007002225 | Jan 2007 | WO |
2007008493 | Jan 2007 | WO |
2007028035 | Mar 2007 | WO |
2007035332 | Mar 2007 | WO |
2007047571 | Apr 2007 | WO |
2007047794 | Apr 2007 | WO |
2007061841 | May 2007 | WO |
2007106490 | Sep 2007 | WO |
2007106533 | Sep 2007 | WO |
2007130628 | Nov 2007 | WO |
2008031011 | Mar 2008 | WO |
2008031095 | Mar 2008 | WO |
2008051907 | May 2008 | WO |
2008066569 | Jun 2008 | WO |
2009006602 | Jan 2009 | WO |
2009006608 | Jan 2009 | WO |
2009006610 | Jan 2009 | WO |
2009006615 | Jan 2009 | WO |
2009025648 | Feb 2009 | WO |
2009039174 | Mar 2009 | WO |
2009111255 | Sep 2009 | WO |
2009131879 | Oct 2009 | WO |
2011060359 | Nov 2009 | WO |
2009146089 | Dec 2009 | WO |
2009146090 | Dec 2009 | WO |
2009149462 | Dec 2009 | WO |
2010011612 | Jan 2010 | WO |
2010088279 | Aug 2010 | WO |
2010117597 | Oct 2010 | WO |
20100117356 | Oct 2010 | WO |
2011011104 | Jan 2011 | WO |
2012015954 | Feb 2012 | WO |
2012015955 | Feb 2012 | WO |
2012019191 | Feb 2012 | WO |
2012090206 | Jul 2012 | WO |
2012140147 | Oct 2012 | WO |
2012145187 | Oct 2012 | WO |
2012149008 | Nov 2012 | WO |
2013003754 | Jan 2013 | WO |
2013142387 | Sep 2013 | WO |
2013163605 | Oct 2013 | WO |
2014006471 | Jan 2014 | WO |
2014012670 | Jan 2014 | WO |
2004014456 | Feb 2014 | WO |
2014047528 | Mar 2014 | WO |
2014054045 | Apr 2014 | WO |
2014070316 | May 2014 | WO |
2014076620 | May 2014 | WO |
2014081958 | May 2014 | WO |
2014145531 | Sep 2014 | WO |
2014145712 | Sep 2014 | WO |
2014162181 | Oct 2014 | WO |
2014170771 | Oct 2014 | WO |
2014179739 | Nov 2014 | WO |
WO-2014188430 | Nov 2014 | WO |
2014197101 | Dec 2014 | WO |
2015074018 | May 2015 | WO |
2015109028 | Jul 2015 | WO |
20150157712 | Oct 2015 | WO |
2016011309 | Jan 2016 | WO |
2016025430 | Feb 2016 | WO |
2016131020 | Aug 2016 | WO |
2016156446 | Oct 2016 | WO |
2016178196 | Nov 2016 | WO |
2016178197 | Nov 2016 | WO |
2017024051 | Feb 2017 | WO |
2017143198 | Aug 2017 | WO |
2017198867 | Nov 2017 | WO |
2017222964 | Dec 2017 | WO |
2018013725 | Jan 2018 | WO |
2018031714 | Feb 2018 | WO |
2018081314 | May 2018 | WO |
2018102435 | Jun 2018 | WO |
2018146690 | Aug 2018 | WO |
2018150314 | Aug 2018 | WO |
2018156930 | Aug 2018 | WO |
2018187582 | Oct 2018 | WO |
2018220143 | Dec 2018 | WO |
2018220146 | Dec 2018 | WO |
2019050831 | Mar 2019 | WO |
2019051007 | Mar 2019 | WO |
2019051108 | Mar 2019 | WO |
2019051007 | Apr 2019 | WO |
2019063521 | Apr 2019 | WO |
2019079364 | Apr 2019 | WO |
2019232213 | Dec 2019 | WO |
2020023839 | Jan 2020 | WO |
2020121221 | Jun 2020 | WO |
2020131247 | Jun 2020 | WO |
2020132460 | Jun 2020 | WO |
2020132668 | Jun 2020 | WO |
2020132669 | Jun 2020 | WO |
2020132670 | Jun 2020 | WO |
2020132671 | Jun 2020 | WO |
2020132678 | Jun 2020 | WO |
2020144075 | Jul 2020 | WO |
2020153765 | Jul 2020 | WO |
2021217055 | Oct 2021 | WO |
2021236756 | Nov 2021 | WO |
2022055920 | Mar 2022 | WO |
2022167382 | Aug 2022 | WO |
Entry |
---|
E. Y. Chow et al., “Fully Wireless Implantable Cardiovascular Pressure Monitor Integrated with a Medical Stent,” IEEE Transactions on Biomedical Engineering, vol. 57, No. 6, pp. 1487-1496, Jun. 2010 (Year: 2010). |
International Search Report and Written Opinion dated Feb. 27, 2020, in connection with PCT/IB2019/060669 filed Dec. 11, 2019. |
Voroneanu et. al., “The relationship between chronic volume overload 3 and elevated blood pressure in hemodialysis patients: 4 use of bioimpedance provides a different perspective 5 from echocardiography and biomarker methodologies,” Int Urol Nephrol, Sep. 2010; 42(3):789-97. |
Cannesson et al., “Respiratory Variations in Pulse Oximetry Plethysmographic Waveform Amplitude to Predict Fluid Responsiveness in the Operating Room,” Anesthesiology 2007; 106:1105-11. |
Abraham et al., “The Role of Implantable Hemodynamic Monitors to Manage Heart Failure,” Heart Failure Clin 11 (2015) 183-189. |
Tallaj et al., “Implantable Hemodynamic Monitors,” Cardiol Clin 29 (2011) 289-299. |
Tang et al., “Measuring impedance in congestive heart failure: Current options and clinical applications,” American Heart Journal 157 (3) 402-411. |
Merchant et al., “Implantable Sensors for Heart Failure,” Circulation: Arrhythmia and Electrophysiology. 2010; 3:657-667. |
Unadkat, Jignesh V., et al. “The Development of a Wireless Implantable Blood Flow Monitor,” Ideas and Innovations, American Society of Plastic Surgeons, 136:199 (2015). |
Steinhouse, David et al., “Implant Experience with an Implantable Hemodynamic Monitor for the Management of Symptomatic Heart Failure,” PACE (Aug. 2005) vol. 28, pp. 747-753. |
Braunschweig, Frieder et al. “Dynamic changes in right ventricular pressures during haemodialysis recorded with an implantable haemodynamic monitor,” Nephrol Dial Transplant (2006) 21:176-183. |
Karamanoglu, Mustafa et al., “Estimation of cardiac output in patients with congestive heart failure by analysis of right ventricular pressure waveforms,” BioMedical Engineering OnLine 2011, 10:36. |
Spiliopoulos, Sotirios et la., “Beneficial aspects of real time flow measurements for the management of acute right ventricular heart failure following continuous flow ventricular assist device implantation,” Journal of Cardiothoracic Surgery (2012) 7:119. |
Sharma, Arjun D. et al., “Right Ventricular Pressure During Ventricular Arrhythmias in Humans: Potential Implications for Implantable Antitachycardia Devices,” JACC vol. 15, No. 3, Mar. 1, 1990, pp. 648-655. |
Kjellstrom, Barbo et al., “Changes in Right Ventricular Pressures Between Hemodialysis Sessions Recorded by an Implantable Hemodynamic Monitor,” The American Journal of Cardiology, 2009, 103:119-123. |
Zile, Michael R. et al., “Transition From Chronic Compensated to Acute Decompensated Heart Failure,” Circulation, American Heart Association (2008) 118:1433-1441. |
Plicchi, G. et al., “Pea I and Pea II Based Implantable Haemodynamic Monitor: Pre Clinical Studies in Sheep,” Europace (2002) 4, 49-54. |
Vanderheyden, Marc et al., “Continuous Monitoring of Intrathoracic Impedance and Right Ventricular Pressures in Patients With Heart Failure,” Circulation Heart Failure (2010) 3:370-377. |
Jacobs, Donald L. et al., “Bedside vena cava filter placement with intravascular ultrasound: A simple, accurate, single venous access method,” Technical Note, Journal of Vascular Surgery, vol. 46, No. 6, pp. 1284-1286, Dec. 2007. |
Muller, Laurent et al., “Respiratory variations of inferior vena cava diameter to predict fluid responsiveness in spontaneously breathing patients with acute circulatory failure: need for a cautious use,” Critical Care 2012, 16:R188. |
Blehar, David J. et al., “Identification of congestive heart failure via respiratory variation of inferior vena cava diameter.” American Journal of Emergency Medicine (2009) 27, 71-75. |
Miller, Joseph B., et al., “Inferior vena cava assessment in the bedside diagnosis of acute heart failure,” American Journal of Emergency Medicine (2012) 30, 778-783. |
Corl, Keith et al., “Bedside sonographic measurement of the inferior vena cava caval index is a poor predictor of fluid responsiveness in emergency department patients,” Emergency Medicine Australasia (2012) 24, 534-539. |
Feissel, et al. “The respiratory variation in inferior vena cava diameter as a guide to fluid therapy,” Intensive Care Med (2004) 30: 1834-1837. |
Nakao, Shoichiro et al., “Effects of Positional Changes on Inferior Vena Caval Size and Dynamics and Correlations with Right-Sided Cardiac Pressure,” American Journal of Cardiology (1987; 59:125-132). |
Saha, Narayan M., et al., “Outpatient Use of Focused Cardiac Ultrasound to Assess the Inferior Vena Cava in Patients With Heart Failure,” American Journal of Cardiology (2015). |
Ishizaki, et al. “Measurement of inferior vena cava diameter for evaluation of venous return in subjects on day 10 of a bed-rest experiment,” J Appl Physical 96: 2179-2186, 2004. |
Carbone et al. “Inferior Vena Cava Parameters Predict Re-admission in Ischaemic Heart Failure”, European Journal of Clinical Investigations, 2014, 44(4): 341-349. |
Bertram, C.D. et al., “Cross-sectional area measurement in collapsed tubes using the transformer principle”, Med. & Biol, Eng. & Comput, 1989, 27, 357-364. |
Moreno, Augusto et al., “Mechanics of Distension of Dog Veins and Other Very Thin-Walled Tubular Structures”, Circulation Research, vol. XXVII, Dec. 1970, pp. 1069-1080. |
Tafur, Emilio et al., “Simultaneous Pressure, Flow and Diameter of the Vena Cava with Fright and Exercise”, Circulation Research, vol. XIX, Jul. 1966., pp. 42-50. |
Guntheroth, Warren G., et al., “Effect of Respiration on Venous Return and Stroke Volume in Cardiac Tamponade”, Circulation Research, vol. XX, Apr. 1967, pp. 381-390. |
Bartels, Lambertus et al., “Improved Lumen Visualization in Metallic Vascular Implants by Reducing RF Artifacts”, Magnetic Resonance in Medicine 47:171-180 (2002). |
Guntheroth, Warren G., “in Vivo Measurement of Dimensions of Veins with Implications Regarding Control of Venous Return”, IEEE Transactions on Bio-Medical Engineering, Oct. 1969; pp. 247-253. |
Kivelitz, Dietmar et al., “A Vascular Stent as an Active Component for Locally Enhanced Magnetic Resonance Imaging”, Investigative Radiology, vol. 38, No. 3, 147-152 (2003). |
Reddy, Reddy R.V., et al., “A Catheter-Tip Probe for Dynamic Cross-Section Area Measurement”, pp. 149-158. (1973). |
Stegall, H. Fred, “Survey of Dimension Transducers”, Chronically Implanted Cardiovascular Instrumentation, pp. 107-115 (1973). |
D. H. Bergel, “The Measurement of Lengths and Dimensions”, Cardiovascular Fluid Dynamics, vol. 1. pp. 91-114 (1972). |
Baan, Jan et al., “Dynamic Local Distensibility of Living Arteries and its relation to Wave Transmission”, Biophysical Journal, vol. 14, (1974); pp. 343-362. |
International Search Report and Written Opinion in connection with PCT/US2016/017902, dated Jul. 27, 2016. |
Reems, Miryam et al., Central Venous Pressure: Principles, Measurement, and Interpretation, Vetlearn.com, Jan. 2012, Compendium: Continuing Education for Veterinarians, pp. E1-E10. |
Yamauchi, Hideko et al., “Correlation Between Blood Volume and Pulmonary Artery Catheter Measurements”, Department of Surgery and Surgical Critical Care, University of Hawaii, 2005. |
Abraham, William T. et al., “Wireless pulmonary artery haemodynamic monitoring in chronic heart failure: a randomised controlled trial”; www.thelancet.com, vol. 377, Feb. 19, 2011, pp. 658-666. |
Guiotto, Giovanna et al., “Inferior vena cava collapsibility to guide fluid removal in slow continuous ultrafiltration: a pilot study”, Intensive Care Med (2010) 36:696-696. |
Martens, Pieter et al., “Current Approach to Decongestive Therapy in Acute Heart Failure”, Curr Heart Fail Rep (2015) 12:367-378. |
Dupont, Matthias et a., “Impact of Systemic Venous Congestion in Heart Failure”, Curr Heart Fail Rep (2011) 8:233-241. |
Marik, Paul E. et al., “Hemodynamic parameters to guide fluid therapy”, Annals of Intensive Care 2011, 1:1; http://www.annalsofintensivecare.com/content/1/1/1. |
Silverberg, Donald et al., “The association between congestive heart failure and chronic renal disease”, Curr Opin Nephrol Hypertens 13: 163-170, 2004. |
Extended European Search Report dated Jul. 3, 2020, in connection with EP20163433.4. |
International Search Report and Written Opinion dated Mar. 3, 2020, in connection with PCT/US2019/066589 filed Dec. 16, 2019. |
International Search Report and Written Opinion dated Mar. 27, 2018, in connection with PCT/US2017/063749. |
International Search Report and Written Opinion dated Aug. 29, 2018, in connection with PCT/EP2018/064386. |
International Search Report and Written Opinion dated Aug. 21, 2018, in connection with PCT/EP2018/064383. |
International Search Report and Written Opinion dated Nov. 4, 2019, in connection with PCT/US2019/034657, filed May 30, 2019. |
International Search Report and Written Opinion dated Oct. 19, 2017, in connection with PCT/US2017/046204. |
Brennan, J.M., “Handcarried Ultrasound Measurement of the Inferior Vena Cava for Assessment of Intravascular Volume Status in the Outpatient Hemodialysis Clinic”; Clinical Journal of the American Society of Nephrology; pp. 749-753; Jan. 23, 2006. |
International Search Report and Written Opinion dated Oct. 20, 2016, in connection with PCT/US2016/045385 filed Aug. 3, 2016. |
Horizon Scanning Research & Intelligence Centre; Furosemide sc2Wear micro-pump patch for oedema in heart failure; National Institute for Health Research; NIHR HSRIC ID: 11808; Mar. 2016; pp. 1-10; www.hsric.nihr.ac.uk. |
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20200253583 A1 | Aug 2020 | US |
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62513013 | May 2017 | US |