Patent Application
20220346709
The present invention relates generally to medical devices. More particularly, the present invention relates to an embedded sensor system for wireless monitoring of the functional status of implanted heart valves.
Advances in sensor miniaturization, functional materials, telemetry and signal processing are opening up new opportunities for implantable wireless sensors to monitor organ function/health. A target of opportunity in this regard is the embedding of such sensors into prostheses or organ implants to provide longitudinal/persistent monitoring of prosthesis function and early detection of onset of potential adverse outcomes. Sensors embedded into or integrated within prosthetic valves have the advantage that this avoids the additional complication and risk of a separate medical procedure for implanting the sensor.
While a wide range of prosthetic devices/implants (orthopedic implants, breast implants, cerebrospinal shunts, etc.) could benefit from such monitoring, cardiac/cardiovascular implants/prostheses are one class of implants where such monitoring has high potential for decreasing adverse outcomes.
Due to increasing life expectancy combined with the advent of trans-catheter delivery of cardiovascular devices, the number of cardiovascular implants such as heart valves, rings, clips, and embolization protection devices is growing exponentially. Transcatheter heart valves in particularly are being deployed at extremely high rates projected to reach 850,000 heart valves/year by 2050.
The vast majority of these are transcatheter aortic valves (TAVs). These devices are expensive (approximately USD $32,000) and have a relatively complex design comprising of an expandable metal stent frame and bioprosthetic leaflets. Some new transcatheter valves are also employing polymeric or other synthetic materials (see
The global Transcatheter Aortic Valve Replacement (TAVR) devices market size was valued at USD 2.4 billion in 2017 and global Transcatheter Aortic Valve Implantation (TAVI) procedures market size was valued at USD 6.2 billion in 2017. It is anticipated to rise at a CAGR of 22.6% over the forecast period. Rising number of patients across the globe suffering from cardiovascular diseases such as heart failures, coronary artery diseases, and hypertension is one of the key trends stoking market growth. Cardiovascular diseases lead to improper functioning of aortic valves, which in turn escalates the demand for efficient valve replacement procedure. In addition, increasing funding for research & development activities, new product launches, and presence of favorable reimbursement policies are some of the factors likely to provide a fillip to the market. Growing adoption of minimally invasive surgery (MIS), along with technological advancements in transcatheter aortic valve replacement procedure, is projected to reduce the overall hospital stay. This, in turn, is poised to reduce healthcare expenditure. Furthermore, geographic expansion, funding, and adoption of advanced devices & procedural methods are estimated to boost the growth of the market during the forecast period. According to Annals of Cardiothoracic Surgery, Transcatheter Aortic Valve Implantation (TAVI) devices are considered to be cost-effective in treating high risk patients. In European and American countries, TAVI devices are government funded.
Transcatheter aortic valves have a biomimetic design with three leaflets and optimal function of these valves usually corresponds to unimpeded and coordinated (in-phase) opening and closing of the three leaflets, see
During implantation, the implanting surgeon/cardiologist must maneuver the implant to an optimal location in the aortic annulus and orient it appropriately in order to ensure that the prosthesis anchors into the aortic root and then functions with acceptable forward flow performance and little to no regurgitation. Peri-procedural imaging options for guiding implant placement are limited to echocardiography (transthoracic or transesophageal) and fluoroscopy. These modalities provide two-dimensional images and cannot accurately image the dynamic motion of each of the leaflets. Thus, the implanting surgeon cannot assess in real-time if the leaflets are opening fully or the degree of symmetry in the leaflet opening. Furthermore, the implanting surgeon cannot currently determine with accuracy, the azimuthal (angular) position of the TAV leaflets relative to the native leaflet and sinuses which is important for commissural alignment. Finally, the implanting surgeon cannot currently determine the position of the TAV leaflets relative to the coronary ostia nor the functional status of the TAV leaflets that are over the coronary ostia.
Accordingly, there is a need in the art for an embedded sensor system for wireless monitoring of the functional status of implanted heart valves.
The foregoing needs are met, to a great extent, by the present invention which provides a system for monitoring the functional status of an implantable heart valve including an implantable heart valve. The system includes sensors positioned on the implantable heart valve. The sensors are configured for monitoring the functional status of the implantable heart valve. The sensors are also configured for outputting a signal, wirelessly, wherein the signal contains data related to the functional status of the implantable heart valve.
In accordance with an aspect of the present invention, the sensors are positioned along an inflow lumen of the implantable heart valve. The sensors are centered with respect to prosthetic leaflets of the implantable heart valve. The sensors are positioned on a frame of the implantable heart valve behind prosthetic leaflets of the implantable heart valve. Sensors can also be positioned on a distal edge of a frame of the implantable heart valve. The sensors can take the form of pressure sensors, accelerometers, and strain sensors. The sensors are configured to estimate individual motion of each of prosthetic leaflets of the implantable heart valve. The system includes an external device to receive the signal transmitted from the sensors. The system further includes a non-transitory computer readable medium programmed for analyzing the signal transmitted from the sensors and output information to a healthcare provider.
In accordance with an aspect of the present invention, the system includes a non-transitory computer readable medium programmed to process the assimilates of each of the sensor data such that the functional status of the heart valve, the heart, and the vasculature is determined. The system includes an external module to facilitate transmission of data to and from the sensors. The external module is further configured to transmit data to external locations, devices, or storage. The external locations, devices, or storage take the form of one selected from the group of a caregiver, server, a computing device, and medical devices or equipment.
In accordance with yet another aspect of the present invention, the sensors take the form of tandem pairs, wherein each tandem pair transmits data as a unit. The sensors are positioned circumferentially about the valve in two separate circumferential planes. In other embodiments the sensors are positioned circumferentially about the valve. The valve can include a stent. The sensors can also be positioned circumferentially about the stent. Alternately. the sensors are positioned on the frame of the implantable heart valve, in the sinuses of Valsalva.
The accompanying drawings provide visual representations, which will be used to more fully describe the representative embodiments disclosed herein and can be used by those skilled in the art to better understand them and their inherent advantages. In these drawings, like reference numerals identify corresponding elements and:
The presently disclosed subject matter now will be described more fully hereinafter with reference to the accompanying Drawings, in which some, but not all embodiments of the inventions are shown. Like numbers refer to like elements throughout. The presently disclosed subject matter may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the presently disclosed subject matter set forth herein will come to mind to one skilled in the art to which the presently disclosed subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated Drawings. Therefore, it is to be understood that the presently disclosed subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. It should be noted that any dimensions are included simply by way of example and are not meant to be considered limiting. Any suitable dimensions known to or conceivable to one of skill in the art could also be used.
The present invention is directed to a system for monitoring the functional status of an implanted heart valve. The system includes wireless pressure sensors that are embedded in the heart valve. An external device receives signal transmitted from the wireless pressure sensors. The external device reads and analyzes these signals and then transmits the data to a healthcare provider.
In contrast to the current state of the art, the current system incorporates optimal sensor placements that are not obvious. The sensors are positioned along the inflow lumen centered with respect to the prosthetic leaflets. Sensors are positioned behind the leaflets on the stent frame as well as along a distal edge of the stent frame. This placement plan for the sensors is novel and derived from computational and experimental studies to optimize the position. The dynamic nature of sensor activation with respect to set conditions is also novel. Furthermore, the use of the sensors to estimate individual leaflet motion to aid in delivery of the device is also novel. Lastly, the sensor configuration also enables the estimation of ventricular and vascular health status and is clearly distinct from current state of the art.
The wireless sensor system of the present invention includes sensors that are embedded in the TAV. The signal transmitted by the sensors, can be analyzed to identify anomalous TAV function and leaflet motion and would be extremely useful during the implantation procedure. Such a system would reduce reliance on imaging, which is either invasive (such as Transesophageal echocardiography) or exposes the patient to radiation (such as fluoroscopy), or does not provide three-dimensional information about the location and orientation of the implant and its leaflets.
Prior art in this arena (see US20070173861A1) employs pressure sensors mounted on the tip of catheters. Such sensors cannot communicate wirelessly with an external device. Simultaneous measurements from different locations cannot be made with this device and precise positioning of the pressure sensor with respect to the valve is not possible.
The direct exposure of heart valve prostheses to the dynamic flow of blood as well as the fact that they are in direct contact within the surrounding vascular or cardiac tissue (e.g. the aortic root or the mitral annulus) that undergoes movement and deformation during each cardiac cycle makes them prone to a variety of “malfunctions” such as leaflet/valve thrombosis, infections, paravalvular leaks, regurgitation, calcification and mechanical deformation. These malfunctions can remain clinically and symptomatically silently or occur catastrophically within minutes, both compromising the long-term health of the heart as well as patient's quality of life. Currently, there are no at-home monitoring systems for evaluating the functional status of implanted heart valves (transcatheter or surgical; aortic, mitral, tricuspid or pulmonic position).
Among these various conditions, early leaflet thrombosis is one that has emerged as the most concerning. Recent studies have indicated that nearly all the TAVs on the market are susceptible to early leaflet thrombosis. Furthermore, this condition represents a major health-risk for the patient because while it is clinically “silent” (hemodynamic gradients are subclinical), it significantly increases the risk for thromboembolic events such as embolic stroke. Moreover, there is evidence that the risk of TAV thrombosis may persist beyond one year after valve implantation. This underscores the importance of serial follow-up and evaluation of the risks and benefits of long-term anticoagulation at regular intervals. Four-dimensional multi-detector computed tomography (4D-MDCT) is currently the most specific and sensitive imaging technique for detecting reduced leaflet motion (RLM) and leaflet thickening associated with leaflet thrombosis, see
A wireless sensor system where the sensors are embedded in the TAV and the signal transmitted by the sensors can be analyzed to (a) monitor TAV performance; (b) identify anomalous TAV function and leaflet motion, and (c) monitor overall parameters related to cardiac function, and would be extremely useful for long-term, at-home monitoring of TAV functional status and the overall cardiovascular status of the patient.
A variety of implantable microsensors have been developed for in-situ monitoring of the hemodynamic status of the cardiovascular system (CardioMEMS sensor from Abbot (Brugts 2017), Cordella System from Endotronix, etc.). Many of these sensors are designed to sense pressure, and similar pressure sensors could be used in the current system. Other sensors such as accelerometers, strain sensors etc. could also be used in the sensor system. These sensor systems generally include an off-body external module that receives the signal from the sensor. This external module may also send a signal to the embedded sensors. This external module may be capable of transmitting data to other devices (computers, phones, tablets) or networks (Wi-Fi, cellular) via wired or wireless connections. This external module is also capable of analyzing and processing the signal with appropriate hardware (CPU etc.) and software.
Given the inherent temporal and spatial complexity of the pressure field within the aorta and the multivariate nature of the implantation procedure as well as conditions such as leaflet thrombosis, the use of more than one sensor will enhance detection and classification of these anomalies. However, sensors placed in “insensitive” or “nondiscriminatory” locations would increase the system complexity and cost, without enhancing its diagnostic capability. The number of sensors and their placement configuration on the TAV is therefore a key element of the system design which would be a function of the valve position (aortic, mitral, etc.), and stent design.
Advances in sensor miniaturization, functional materials, telemetry and signal processing are opening up new opportunities for implantable wireless sensors to monitor organ function/health. A target of opportunity in this regard is the embedding of such sensors into prostheses or organ implants to provide longitudinal/persistent monitoring of prosthesis function and early detection of onset of potential adverse outcomes. Sensors embedded into or integrated within prosthetic valves have the advantage that this avoids the additional complication and risk of a separate medical procedure for implanting the sensor.
While a wide range of prosthetic devices/implants (orthopedic implants, breast implants, cerebrospinal shunts, etc.) could benefit from such monitoring, cardiac/cardiovascular implants/prostheses are one class of implants where such monitoring has high potential for decreasing adverse outcomes.
Due to increasing life expectancy combined with the advent of trans-catheter delivery of cardiovascular devices, the number of cardiovascular implants such as heart valves, rings, clips, and embolization protection devices is growing exponentially. Transcatheter heart valves in particularly are being deployed at extremely high rates projected to reach 850,000 heart valves/year by 2050.
As described above, sensors can be embedded (a) in the sub-annular (or skirt) region; (b) supra-annular portion of the implant, in the sinus region or near the sino-tubular junction (STJ); and (c) in or on either side of the leaflet, as illustrated in
The other location where valve anomalies generate large changes in pressure is downstream of the valve where the vortices are formed in the transvalvular jet and also where the transvalvular jet impacts the aortic wall, as illustrated in
Locations on the stent in the aortic sinus behind the mobile prosthetic leaflets are also regions where valve anomalies cause large pressure changes. This region is largely exposed to recirculating flow behind the mobile leaflet. In each cusp of the aortic sinus, the flow is relatively agnostic to that in the other two. Thus, measurements form this region are highly sensitive to changes in valve function.
Another location where valve anomalies generate large changes in pressure is on the valve leaflets, as illustrated in
ΔP(t)=P1(t)−P2(t)
where ‘t’ refers to time.
Likewise, the instantaneous pressure drop across the valve (referred to as the transvalvular gradient) may be computed as the difference between measurements upstream (at the skirt location) and downstream (at the STJ) from the valve. A large value of pressure drop, averaged over systole,(greater than about 10 mm of mercury) usually indicates non-negligible flow blockage most commonly due to reduced geometric opening of the leaflets. This is an important measure of overall valve function and performance. However, the sinus pressure difference is found to be more sensitive to changes in individual leaflet mobility and can capture changes in corresponding leaflet function.
Tandem sensors can be embedded for each leaflet and the signals from these tandem sensor arrangements can be analyzed to identify leaflets that are opening and moving normally from leaflets that are experiencing anomalous movement.
These sensor arrangements can indicate the position of paravalvular leaks when comparing ΔP(t) during the period the valve is closed. The sensor data can also estimate the patient's real time ventricular as well as arterial properties. For example, the time-rate-of-change of pressure at the inflow region of the valve can be correlated to the stroke volume and contractility of the ventricle. The changes in pressure (such as the decay constant) during the period the valve is closed can estimate the structural compliance of the aorta (for the case of the aortic valve). These parameters can be derived over resting and moderate activity of the patient to gauge changes in exercise physiology of the patient such as the responses to natural vasodilation as well as surrogate pressure volume characteristics of the ventricle. Complete characterization of the ventricular function will help manage heart failure therapy for the patient if the patient developed heart failure prior to or after valve replacement. The pressure rise over the iso-volumetric contraction phase can be calculated based on comparing the pressure changes between the inflow and outflow regions of the valve. This parameter gives a direct measure of myocardial contractility.
Sensors imbedded in or attached to the valve leaflets provide a strong signal of anomalous movement of the leaflet. The signal from the sensors in this case combines the effects of pressure as well as leaflet acceleration. The acquisition of the signal by the external module and the processing of the sensed signal is tightly coupled with the number and placement of sensors and is therefore an integral part of the system design. A sophisticated sensor system that is coupled with an inappropriate signal acquisition or signal analysis framework (and vice-versa) would diminish the effectiveness of the system.
The signal acquisition protocol could be controlled by the external module; a controller inside the external module, or a connected device, could modify the data acquisition protocol “on-the-fly” based on the real-time analysis of the signal. The analysis of the signal could involve comparison with previously obtained signals as well as other patient data acquired previously. Changes in sensor data acquisition include but are not limited to changing the temporal rate of signal acquisition from one or more sensors, changing signal intensity to one or more sensors, not acquiring signals from one or more sensors, increasing the duration of the signal acquisition from one or more sensors, and increasing the rate at which the patient is prompted to make these measurements during a given period.
The following are some example scenarios where such “on-the-fly” changes would be employed by the sensor system in the setting of post-operative monitoring of the implant (see
The following are some example scenarios where such “on-the-fly” changes would be employed by the sensor system in the setting of peri-procedural guidance, as illustrated in
The present invention could be carried out using a computer, non-transitory computer readable medium, or alternately a computing device or non-transitory computer readable medium incorporated into a console for TAV implantation. Indeed, any suitable method of calculation known to or conceivable by one of skill in the art could be used. It should also be noted that to the extent specific equations are detailed herein, variations on these equations can also be derived, and this application includes any such equation known to or conceivable by one of skill in the art.
A non-transitory computer readable medium is understood to mean any article of manufacture that can be read by a computer. Such non-transitory computer readable media includes, but is not limited to, magnetic media, such as a floppy disk, flexible disk, hard disk, reel-to-reel tape, cartridge tape, cassette tape or cards, optical media such as CD-ROM, writable compact disc, magneto-optical media in disc, tape or card form, and paper media, such as punched cards and paper tape. The computing device can be a special computer designed specifically for this purpose. The computing device can be unique to the present invention and designed specifically to carry out the method of the present invention. It is not a standard business or personal computer that can be purchased at a local store. Additionally, this computer carries out communications with the TAV devices through the execution of proprietary custom built software that is designed and written by the manufacturer for the computer hardware to specifically operate the scanner hardware.
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
This application claims the benefit of U.S. Provisional Patent Application No. 62/864,871 filed on Jun. 21, 2019, which is incorporated by reference, herein, in its entirety.
This invention was made with government support under CBET-1511200 awarded by the National Science Foundation. The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2020/038922 | 6/22/2020 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62864871 | Jun 2019 | US |
