ATRIAL PACING CAPTURE CONFIRMATION STRATEGY IN AN INTRA-CARDIAC LEADLESS PACEMAKER

Abstract

A leadless pacing device for implanting into an atrium of a heart. The leadless device comprises an implant anchor for connecting the device to an inner wall of the atrium; a stimulator for a direct stimulation of the atrium; a sensor for sensing a ventricular activity of the heart corresponding to the direct stimulation of the atrium. Further aspects relate to a system comprising such leadless pacing device, a method and a computer program that may be executed by such leadless pacing device.

Claims

1. Leadless pacing device for implanting into an atrium of a heart, comprising: an implant anchor for connecting the device to an inner wall of the atrium; a stimulator for a direct stimulation of the atrium; a sensor for sensing a ventricular activity of the heart corresponding to the direct stimulation of the atrium.

2. Leadless pacing device according to claim 1, wherein the device is further configured to determine an occurrence or an absence of a ventricular event corresponding to the direct stimulation of the atrium, based at least in part on the sensed ventricular activity.

3. Leadless pacing device according to claim 1, wherein the device is configured to determine whether a direct stimulation at a predetermined stimulation power and/or a predetermined stimulation energy leads to a corresponding ventricular event.

4. Leadless pacing device according to claim 1, wherein the device is further configured to change a stimulation power and/or a stimulation energy of the direct stimulation.

5. Leadless pacing device according to claim 3, wherein the device is further configured to perform multiple direct stimulations with different stimulation powers and/or different stimulation energies to determine a threshold of the stimulation power and/or of the stimulation energy for which a ventricular event occurs.

6. Leadless pacing device according to claim 1, wherein the device is further configured to sense the ventricular activity and/or to determine the ventricular event in a predetermined time window after the direct stimulation.

7. Leadless pacing device according to claim 6, wherein the device is further configured to determine at least one parameter of the time window at least in part based on data, stored by the device, concerning at least one previously measured time interval of the heart.

8. Leadless pacing device according to claim 6, wherein the device is further configured to determine at least one parameter of the time window at least in part based on performing a test stimulation with a test stimulation power and/or with a test stimulation energy and sensing the corresponding ventricular activity.

9. Leadless pacing device according to claim 1, wherein the sensor is configured for far-field sensing.

10. Leadless pacing device according to claim 1, wherein the sensor is configured for receiving information on ventricular activity from at least one first additional sensor for implanting in a ventricle of the heart.

11. System comprising the leadless pacing device and the at least one first additional sensor according to claim 10.

12. Leadless pacing device according to claim 1, comprising a second additional sensor for directly sensing an atrial activity of the heart corresponding to the direct stimulation of the atrium.

13. Method for determining a stimulation response carried out by a leadless pacing device implanted into an atrium of a heart, comprising: performing a direct stimulation of the atrium of the heart by the device at a predetermined stimulation power and/or a predetermined stimulation energy; sensing a ventricular activity of the heart corresponding to the direct stimulation by the device; determining an occurrence or an absence of a ventricular event corresponding to the direct stimulation.

14. Method according to claim 13, further comprising: performing multiple direct stimulations with different stimulation powers and/or different stimulation energies to determine a threshold of the stimulation power and/or of the stimulation energy for which a ventricular event occurs.

15. Computer program comprising instructions to perform a method of one of claim 13, when the instructions are executed by a computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] FIG. 1 Schematic representation of an exemplary embodiment of a leadless pacing device and an optional system according to the present invention.

[0055] FIG. 2 Schematic representation of an exemplary embodiment of a method according to the present invention.

[0056] FIG. 3 Schematic representation of a time window that may be used by a method or a device according to the present invention.

DETAILED DESCRIPTION

[0057] FIG. 1 shows a schematic of an exemplary leadless pacing device 100 according to the present invention.

[0058] The leadless pacing device 100 may optionally be part of a system S that may comprise a first additional sensor 200, wherein the first additional sensor 200 may be implantable in a ventricle V.

[0059] The leadless device 100 may be implanted into an atrium A of a heart (e.g., an atrium A of a human heart). The leadless device 100 may be particularly configured for implanting into a right atrium of a patient, for example.

[0060] 25 The leadless pacing device 100 may comprise an implant anchor 110 for connecting the leadless device 100 mechanically to an inner wall of the atrium A. The implant anchor 110 may be constructed as the base mount of the leadless device 100, which may serve as a surgical fixation point during an implantation procedure. The implant anchor 110 may comprise one or more fixation tines and/or an anchor structure and/or a screw-in fixation 30 mechanism to enable a stable and reliable connection to the atrium A.

[0061] The leadless pacing device 100 may further comprise a stimulator 120. The stimulator 120 may be configured to apply electrical stimulation onto the inner wall of the atrium A. It may be configured to deliver a specific amount of electrical energy into the atrium A. The stimulator 120 may be connected to a power electronic circuitry which may provide defined energy for the stimulation (e.g., in the form of one or more stimulation bursts). The stimulation may be for testing, calibration, core brady and/or anti-tachycardia pacing purposes. The stimulator may comprise an electrically conductive material which may be formed by means of an electrode (e.g., a cathode or an anode), which may provide a direct electrical connection to the wall of the atrium A for transferring the electrical energy of the stimulator onto the surrounding tissue.

[0062] The amount of electrical energy applied by the stimulator 120 may be adaptable. For example, the electrical energy may be applied in the form of pulses with an adaptable energy and/or an adaptable pulse timing or frequency. Further adaptable parameters may be (average) power, cycle length, current, voltage, pulse width, FWHM, etc. of the applied electrical stimulus. The electrical energy and/or pulse parameters may be determined by the leadless device 100 or the system S (e.g., depending on sensed ventricular activity and/or atrial activity).

[0063] The leadless device 100 may further comprise a sensor 130 (stationed in the atrium A, being part of the leadless device 100). In an example, the sensor 130 may be configured to indirectly measure ventricular activity by sensing the signal from a ventricle V (e.g., right ventricle) of the heart (e.g., far-field sensing and/or accelerometer-based sensing). For far-field sensing, the sensor 130 may be configured to be in direct contact with the inner wall of the atrium A such that an electrical connection is established. Notably, the sensor 130 may be further configured to sense electrical signals present in the atrium A indicative of ventricular activity (e.g., the R-wave signal). The sensor 130 may comprise an electrically conductive material which may be formed by means of an electrode (e.g., a cathode or an anode) to directly pick up the respective electrical signal from the inner wall of the Atrium A. The sensor 130 or its electrode may comprise a coating (e.g., by galvanization), a texture (e.g., with a dimensioned porosity) and/or a specific geometry (e.g., screw shape, flat circular shape, etc.) which may be optimized with regards to the properties of the inner wall of the atrium A to ensure a well-functioning sensing contact. As an example, the ventricular activity may be determined to correspond to an atrial stimulus.

[0064] In an example, the sensor 130 and/or the stimulator 120 may share an element with the implant anchor 110, thus enabling the mechanical fixation and sensing/stimulating functions of the leadless device 100 by a single structural element, e.g., an electrode that at least in part also serves for mechanically connecting the leadless device 100 to the wall of the atrium A.

[0065] The leadless device 100 may further comprise a second additional sensor 150. The second additional sensor 150 may be in direct contact with the inner wall of the atrium A such that an electrical connection is established. The second additional sensor 150 may thus enable near-field sensing and may be configured to sense the atrial activity (e.g., P-wave signal). In an example, the sensor 150 may be configured to also sense and/or determine the atrially-evoked response signal (i.e., the direct response of the atrial myocardium to an atrial stimulus). The sensor 150 may comprise an electrically conductive material which may be formed by means of an electrode (e.g., a cathode or an anode) to directly pick up the respective electrical signal from the inner wall of the Atrium A. The second additional sensor 150 (e.g., in particular its electrode) may have a fractal coating on the surface which serves as the contact to the surrounding (atrial) tissue. The fractal coating may be of a conductive material (e.g., iridium, titanium nitride) which may be deposited to form an irregular shape at a microscopic scale. The coating may thus significantly increase the electrochemically active surface area, which is beneficial to determine the atrially-evoked response. Hence, this may enable the second additional sensor to pick up the atrially-evoked response signal without significant interference at the device-to-tissue interface and correctly determine the atrially-evoked response. For example, the fractal coating may ensure that polarization artifacts remain consistent, which can then be accurately considered in the further signal processing. This may reduce or completely inhibit the detection of false positives and/or false negative. The atrially-evoked response may be determined to correspond to an atrial stimulus, for example.

[0066] The stimulator 120, the sensor 130 and/or the second additional sensor 150 may share one or more electrodes and/or have separate electrodes. The stimulator 120 and/or the sensor 130 may also have a fractal coating as described with reference to the second additional sensor 150 when their electrodes are shared with the second additional sensor or when their respective electrodes are separate.

[0067] As outlined above, in some examples, the functionalities of the sensor 130 and the second additional sensor 150 may be provided by a (single) sensor unit of the leadless device 100. In some examples, leadless device 100 may be provided with a sensor unit implementing the function of second sensor 150 and/or sensor 130, instead of second additional sensor 150 and sensor 130.

[0068] The leadless device 100 may further comprise a battery 140, which may serve as power supply of the leadless device 100. The battery 140 may have a slightly smaller form factor compared to batteries used for devices that are implanted into a ventricle, due to the smaller size of the atrium A.

[0069] Further, the leadless device may comprise a control unit 160. The control unit 160 may be at least one computing unit (e.g., a microprocessor, a microcontroller, an embedded system, an electronic circuitry, etc.) which may implement computing instructions. It may control various device elements based on a configuration, which may be defined by the computing instructions (e.g., by a computer program running on the control unit 160). The control unit 160 may be connected to the various device elements outlined above (e.g., over one or more input/output ports for respective electrical signaling) to control and/or receiving/send information. The control unit 160 may, for example, receive sensory input from the sensors outlined herein, and apply further signal processing (e.g., scaling, filtering, rectification). The control unit 160 may have its own memory and/or may be coupled to a separate memory which may be comprised in the leadless device 100.

[0070] The control 160 unit as described herein may also be implemented in hardware, software, firmware, and/or combinations thereof, for example, by means of one or more general-purpose or special-purpose processors and/or microcontrollers.

[0071] The control unit 160 may be coupled to the stimulator 120 and/or a power electronic circuitry of the stimulator 120, wherein a specific signaling of the control unit 160 may result in a desired stimulation output with a set of stimulation parameters over the stimulator 120 onto the atrium A of the heart. The control unit 160 may thus control the stimulation output in the atrium A, which may be based on several input factors, which may be processed and analyzed by the control unit 160. As an example, the paced output may be a response to a ventricular activity and/or atrial activity corresponding to a prior atrial stimulation. The control unit 160 may thus enable various implementations of cardiac therapies by the device.

[0072] As an example, the leadless pacing device 100 may be configured to support AAI mode cardiac therapies for patients with sick sinus.

[0073] It is noted that the way in which the interaction between control unit 160 and stimulator 120, and sensors 130 and 150 was described is merely optional. At least in part, functions of control unit 160 may be implemented by the sensors themselves. For example, the second additional sensor 150 may, in some examples, share an electrode with the sensor 130, such that their signals may physically be picked up by the same elements. However, they may comprise different signal processing/filtering etc. to derive atrial and ventricular activity, respectively, implemented by one or more control units.

[0074] The system S may optionally comprise a first additional sensor 200 according to the present invention which is indicated by dashed lines in FIG. 1. The first additional sensor 200 may be implanted into a ventricle V of a heart (e.g., a ventricle V of a human heart). The first additional sensor 200 may particularly be configured for implanting into a right ventricle of a patient. In an example, the first additional sensor 200 may be a passive sensor that detects the ventricular activity. The first additional sensor 200 may comprise a capacitor 210 as a passive sensor which may be implanted into the ventricle V in such a way that it is coupled to the ventricular activity. The capacitor 210 may be aligned in the tissue, so that the ventricular activity of the nearby muscle cells may influence the electrical properties of the capacitor 210. For example, the capacitor 210 may comprise a dielectric medium interposed between to conductors. The first additional sensor 200 may be arranged such that electrical fields of the ventricular tissue depolarizations influence the dielectric medium leading to a change of the dielectric medium, resulting in a change in the capacitance of the capacitor 210. In another example, the mechanical contractions of the ventricular cells may influence the mechanical properties of the capacitor 210 (e.g., the distance between capacitor plates and/or the area of the capacitor plates), which may lead to a change in capacitance of the capacitor 210. The capacitor 210 may be coupled to an inductor (not shown) to form a resonant circuit whose resonant frequency would then depend on the capacitance of the capacitor 210 and the inductance of the inductor. The inductance of the inductor may be designed to have a fixed value, wherein the inductor may be configured to not significantly change its inductance under the direct influence of the ventricular contractions and/or excitations. The resonant frequency of the resonant circuit may therefore be significantly dependent on the value of the capacitance of the capacitor 210 (and not the inductance) under the ventricular activity. A readout of the resonant frequency corresponding to a change in capacitance of the capacitor 210 may thus enable a readout of the ventricular activity. In an example, the resonant circuit in the ventricle V may comprise an antenna 220 which is connected to the inductor. The antenna 220 may relay the information of the resonant circuit (e.g., resonant frequency, the change in resonant frequency, the change in capacitance and/or the capacitance itself) to the leadless device 100 stationed in the atrium A. The leadless device 100 may comprise a receiver unit to receive the information. The receiver unit may be coupled to the control unit 160, which may further process the signal. In another example. an antenna 220 may be comprised in the leadless device 100 stationed in the atrium whereas the antenna 220 is configured to be coupled to the resonant circuit and to read out the resonant circuit parameters as outlined above. The first additional sensor 200 may comprise a power source to ensure application. In another example the first additional sensor 200 may be configured to not require an internal power source for detecting the ventricular activity.

[0075] In an example, the first additional sensor 200 may be comprised by a ventricularly-stationed leadless pacing device, which may be configured to directly sense the ventricular activity. The ventricularly-stationed leadless pacing device may comprise device elements that may be similar to those described herein for the leadless device 100 in the atrium. Its device elements may have features configured for the ventricle V. The optional ventricular leadless pacing device and the leadless pacing device 100 may be configured for device-to-device communication, such that the sensed activity may be requested, as well as exchanged between the devices in a manner similar to the relay of pacing commands.

[0076] FIG. 2 shows a schematic of an exemplary method 300 according to the present invention for determining a stimulation response carried out by a leadless pacing device implanted into an atrium of a heart. The method may be performed by the leadless device 100 implanted into an atrium A of a heart (e.g., by the control unit 160 of the leadless device 100). The method may be also performed by the leadless device 100 in the system S configuration as outlined herein.

[0077] The method 300 may comprise performing 310 a direct stimulation of the atrium of the heart by the leadless device 100 at a predetermined stimulation power and/or a predetermined stimulation energy. The direct stimulation may be based on a stimulation parameter or a set of stimulation parameters (e.g., cycle length, current, voltage, pulse width, total power, average power, total energy, etc.) corresponding to an electrical power and/or electrical energy of the stimulation. For example, the direct stimulation may comprise a fixed pulse duration, wherein the pulse amplitude may be adjusted to adapt the stimulation power. Notably, the stimulation power and/or stimulation energy (and/or the stimulation parameters) may be set by the control unit 160. The control unit 160 may activate the stimulation, which may be performed by the stimulator 120.

[0078] Subsequently, the method 300 may comprise sensing 320 a ventricular activity of the heart corresponding to the direct stimulation of the device. The ventricular activity as a heart response may be medically associated with the corresponding atrial stimulation. For example, the atrial stimulation may evoke an atrial signal which may be conducted along the heart to the ventricle to cause a corresponding ventricular activity as a heart response (e.g., a ventricular contraction). Additionally or alternatively, the method may comprise sensing an atrial activity (e.g., an atrial event and/or an atrially-evoked response signal) of the heart corresponding to the direct stimulation of the device. For example, as stated above, the atrial stimulation may evoke an atrial signal as a direct heart response which may be sensed, as well.

[0079] The ventricular activity may be sensed by the sensor 130 and/or the first additional sensor 200, whereas the atrial activity may be sensed by the second additional sensor 150. The sensory data may be transferred to the control unit 160, which may apply initial signal processing (e.g., high-gain signal amplification). The control unit 160 may be further configured to control the resolution of the sensory data, which may be implemented by adapting sensor settings, and/or by postprocessing of the raw sensor data. This may enable the leadless device 100 to collect high-resolution data, which may also comprise a high-gain signal of an intracardiac electrogram (IEGM). This processing may ensure a reliable signal quality for further processing steps.

[0080] As outlined herein, sensor 130 and/or second additional sensor 150 may be implemented as a (single) sensor unit (e.g., with a different channel for the far-field channel and/or for the near-field signal, respectively), such as to implement the two different sensor functionalities.

[0081] Subsequently, the method 300 may comprise determining 330 an occurrence or an absence of a ventricular event corresponding to the direct stimulation. The corresponding ventricular event may be a ventricular contraction taking place in response to the applied atrial stimulation. Additionally, or alternatively, the method 300 may comprise determining an occurrence or an absence of an atrial event and/or an atrially-evoked response corresponding to the direct stimulation. The atrial event may be an atrial contraction, whereas the atrially-evoked response may be a particular signature of the atrially-evoked response signal. The determination of a ventricular event, atrial event and/or atrially-evoked response may be implemented by a respective detection algorithm which may be implemented by the control unit 160. The respective detection algorithm may require signal processing (e.g., scaling, filtering, rectification, signal amplification, etc.).

[0082] The method 300 may further comprise performing 340 multiple direct stimulations (of the atrium A) with different stimulation powers and/or stimulation energies to determine a threshold of the stimulation power and/or stimulation energy for which a ventricular event (and/or atrial event and/or atrially-evoked response) occurs. This may enable the determination of a minimum stimulation power and/or a minimum stimulation energy which may still result in the occurrence of a ventricular event (and/or atrial event and/or atrially-evoked response). The method step of performing 340 may be implemented by sequentially repeating the steps of performing 310, sensing 320, determining 330, wherein each sequence may be based on a stimulation with a different stimulation power and/or stimulation energy, which may be adjusted after each sequence as outlined herein. The sequential stimulation may also be referred to as search stimulations.

[0083] Hence, the method 300 may enable various types of atrial capture threshold searches for various heart responses (e.g., ventricular event, atrial event, atrially-evoked response) to an atrial stimulus. A successful atrial capture may be understood as an occurrence of a specific heart response to the atrial stimulation (i.e., capture confirmation). An unsuccessful atrial capture may be understood as the absence of a specific heart response to the atrial stimulation (i.e., capture loss).

[0084] The atrial capture threshold search may search for a value of an atrial stimulation power and/or stimulation energy (and/or any other stimulation parameter) which marks a minimum threshold for effecting the specific heart response. The specific heart response may not be significantly dependent on the amount of a stimulation parameter of the stimulation, but merely dependent on the stimulation parameter being above or below its specific threshold. For example, the applicable stimulation power of the leadless device may vary in a certain range. The minimum threshold of a heart response (which may be patient specific) may, for example, be at 30% of that range. Stimulations with power levels above or equal to 30% may result in the specific heart response, stimulations with power levels below 30% may not cause the specific heart response.

[0085] For brevity purposes, the atrial capture threshold search will be explained in further detail in an example for a ventricular contraction as the specific heart response to an atrial stimulus. However, this is just for exemplary purposes and, in other examples, the method 300 may be based on a different heart response (i.e., a different ventricular signal, an atrial event and/or an atrially-evoked response).

[0086] To determine the threshold, the leadless pacing device 100 may evaluate a sequence of search stimulations (i.e., atrial search paces) and determine the respectively conducted ventricular activity, as outlined for the method 300. The steps of sensing 320 and determining 330 of the ventricular activity may be narrowed to a time window after the search stimulation.

[0087] An exemplary time window 420 is shown in the exemplary time diagram 400 of FIG. 3. Notably, when (e.g., in method 300), a time window 420 is used, ventricular activity outside of the time window 420 may not be sensed and/or taken into account for the step of determining 340. Only the signal in the time window 420 may be deemed relevant. This may significantly reduce computing complexity for the control unit 160 and may save power consumption leading to an increased device longevity. The time window 420 may be associated with an expected Vs (ventricle sensed) window assumed for a typical AV delay of the heart. The AV delay may be related to the signal conduction from the atrium to the ventricle. It may be seen as a time when the ventricular contraction will normally occur after an atrial stimulation. During the atrial capture threshold search, a steady AV delay and/or a stable ApVs (atrial paced, ventricle sensed) rhythm may be achieved by altering the atrial stimulation rate, which may, for example, be increased to overdrive the intrinsic heart activity. This may achieve a stable one-to-one AV conduction. Furthermore, an AV pacing delay may be lengthened to encourage sensing. Overall, atrial stimulation parameters may be adapted during the capture threshold search to reliably achieve that the response of ventricular activity is reliably taking place in the time window 420 after the atrial stimulus. This may enable to narrow the confirmation of a capture or capture loss to the time window 420 after a search stimulation 410 was applied.

[0088] The time window 420 is shown in FIG. 3 on a time scale relative to the search stimulation 410. The atrial search stimulation 410 may occur at a time to. The time window may be set to be in a period when the ventricular response is expected if a successful capture occurs, as outlined herein. The time window 420 may have a time window length defined by two time values which mark the beginning time t.sub.1 and the end time t.sub.2 of the time window 420. The time t.sub.1 and t.sub.2 may be referred back to the time to, which may be defined as the initial reference time to =0, when the atrial stimulation occurs. For example, a time measurement may be started after applying the atrial stimulation (e.g., by means of a time counter). The time may be measured by the control unit 160, and/or it may be measured by an additional time unit comprised in the leadless device 100. An important parameter of the time window 420 may be the center time t.sub.C which can be defined as the time window center, which may be calculated as t.sub.C=(t.sub.2+t.sub.1)/2. The center time t.sub.C may be set to be in the amplitude peak (or center of the distribution) of the expected ventricular contraction signal. The time window length (t.sub.2t.sub.1) may be set to take into account cycle-to-cycle variations of the ventricular contractions. This may ensure that the signal associated with the occurrence of a ventricular contraction may still be determined inside the time window 420, even when the signal of a ventricular contraction is slightly shifted.

[0089] The parameters of the time window 420 may be based on the patient's ApVs interval history. The center time t.sub.C may be set to match the last saved ApVs interval, or an average of a short buffer history of ApVs intervals.

[0090] The capture search may comprise an initialization phase to determine parameters of the time window (e.g., t.sub.C, t.sub.1, t.sub.2, window length etc.) by a continuous measurement of ventricular activity after a test stimulation. The test stimulation may comprise a parameter (e.g., a high-power pulse) or a set of parameters which are expected to successfully capture a ventricular contraction. Subsequently, the control unit 160 may analyze the signal of the continuous measurement of the ventricular activity and determine at least one time window parameter, as outlined herein. In an example, the test stimulation may be done to determine only the center time t.sub.C, wherein the time window length may be based on a predetermined time window length, which may be defined by the clinician and/or technician (i.e., by an external configuration of the leadless device 100). During the initialization phase, the atrial stimulation parameters (e.g., atrial stimulation rate) may be adapted for the same conditions as during the threshold search to achieve stable conduction conditions, to ensure that the determined time window parameters are the same as during the capture threshold search. This would imply that several test stimulations would be performed. The continuous measurement could then be performed after one of the test stimulations or a subset thereof, or possibly after each one of the test stimulations.

[0091] Coming back to FIG. 2, particularly in the step 340 the substep(s) of sensing and/or determining may thus be narrowed to the time window 420 without the loss of information if a successful capture occurred or not. The threshold search may be based on progressively sweeping a parameter (or a set of parameters) of the stimulation and determining if the respective stimulation results in a capture confirmation or capture loss inside the time window 420. As outlined herein, the threshold search may start with a high-power stimulation expected to capture, with a subsequent incremental decrease of the power of the stimulations to reach the vicinity of the threshold to eventually determine the latter. Various other threshold search algorithms may be applied.

[0092] As an example, the threshold search may be optimized to require as few steps as possible, which may be achieved by starting the threshold search based on a stored threshold. The stored threshold may be the last saved threshold, or an average of a short buffer history of prior thresholds. In a further example, the time window parameters may be determined after each threshold search step or may be determined at certain points (e.g., after certain steps) in the threshold search. For example, after a successful capture threshold determination, the time window parameters may be determined again as confirmation, to ensure they have not drifted during the search.

[0093] It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range, including the end points.