SEPARATE-ELECTRODE ELECTRIC FIELD GUIDANCE
20220322960 · 2022-10-13
Assignee
Inventors
Cpc classification
A61B34/20
HUMAN NECESSITIES
A61B5/287
HUMAN NECESSITIES
A61F2/2442
HUMAN NECESSITIES
A61B5/065
HUMAN NECESSITIES
A61B2017/00606
HUMAN NECESSITIES
A61B2090/3966
HUMAN NECESSITIES
International classification
A61B5/06
HUMAN NECESSITIES
A61B5/00
HUMAN NECESSITIES
Abstract
Electrical field-guided positioning of a second device within a body cavity, using electrical field mapping information generated from electrical field measurements by electrodes of a first device. The first device, in some embodiments, is a catheter electrode probe, and the second device is an internally implantable and/or operated medical device. An exposed, electrically conductive portion of the second device is optionally configured to be used as an electrical field measuring electrode. A rule is applied to measurements made by this electrode to estimate its position within a body cavity. The rule is generated, in some embodiments, using measurements made by the first device.
Claims
1. A method of guiding an electrically conductive medical implement inside a body cavity, the method comprising: accessing a rule for transforming electrical field measurements to positions in the body cavity, wherein the rule is generated based on a first set of electrical field measurements of one or more electrical fields extending through the body cavity and which are measured using electrodes of a probe at various positions of the probe within the body cavity, the probe comprising a plurality of measuring electrodes; receiving a second set of electrical field measurements of the one or more electrical fields measured via an electrically conductive medical implement within the body cavity, wherein the electrically conductive medical implement is a separate device to the probe; and estimating a position of the electrically conductive medical implement when the second set of electrical field measurements was measured, using the second set of electrical field measurements and the rule.
2. The method of claim 1, wherein the electrically conductive medical implement comprises an electrically conductive portion having a surface of at least 10 mm in each of one or more dimensions, and is configured to expose the surface of the electrically conductive portion.
3. The method of claim 1, wherein the electrically conductive medical implement comprises an electrically conductive portion at least twice as big as each of the measuring electrodes of the probe in one or more dimensions, and is configured to expose a surface of the electrically conductive portion.
4. The method of claim 1, wherein the electrically conductive medical implement is configured to deploy, thereby exposing the electrically conductive portion to the electrical fields.
5. The method of claim 1, wherein the second set of electrical field measurements are received from the electrically conductive medical implement via a structural member of the medical implement, the structural member being electrically conductive and operable to move the electrically conducive medical implement within the body cavity.
6. The method of claim 4, wherein the second set of electrical field measurements is measured while the electrically conductive portion remains partially within a sheath from which it is configured to deploy.
7-9. (canceled)
10. The method of claim 1, wherein the rule for transforming electrical field measurements to positions transforms electrical field readings of the first set of electrical field measurements to positions of electrodes of the multi-electrode probe.
11. The method of claim 10, wherein estimating the position of the electrically conductive medical implement comprises applying the rule to measurements of the second set of electrical field measurements to produce a position result.
12. The method of claim 11, wherein the position result provides an estimated position for the electrically conductive medical implement.
13. (canceled)
14. The method of claim 11, comprising transforming the position result to an adjusted position result according to a model of the shape and size of the electrically conductive medical implement.
15-16. (canceled)
17. The method of claim 1, wherein the rule for transforming electrical field measurements to positions transforms electrical field measurements of the second set of electrical field measurements to positions corresponding to measurement positions of electrodes of the probe.
18-19. (canceled)
20. The method of claim 1, wherein the medical implement comprises a medical implant device configured to attach to and be left in the body.
21. The method of claim 1, wherein the medical implement is configured to expand in at least one of a longitudinal and a radial direction upon delivery to the body cavity, and the second set of electrical field measurements are made while the medical implement is expanded.
22. (canceled)
23. The method of claim 1, comprising receiving an indication that the probe has been moved from the body cavity before the second set of measurements was received.
24. The method of claim 1, wherein the rule for transforming electrical field measurements to positions is generated using inter-electrode distances of the multi-electrode probe.
25. The method of claim 1, wherein the estimating comprises use of a calibration of the second set of electrical field measurements to the rule using position information for the electrically conductive medical implement within the body cavity which is known separately from the second set of electrical field measurements.
26. The method of claim 25, wherein the position information known separately includes a known position of the electrically conductive medical implement at a septum of the heart.
27. The method of claim 25, wherein the position information known separately includes a position at which further advancing of the conductive medical implement is prevented by contact with a wall of the body cavity.
28. The method of claim 1, wherein the estimating comprises use of a calibration of the second set of electrical field measurements to the rule using one or more electrically measured characteristics of the environment of the electrically conductive medical implement.
29. The method of claim 28, wherein the one or more electrically measured characteristics of the environment comprise a change in measured impedance.
30. The method of claim 29, wherein the change in measured impedance is characteristic of proximity to a wall of the body cavity.
31. The method of claim 1, comprising moving the conductive medical implement, based on the estimating.
32. The method of claim 1, wherein the electrical field measurements are measurements of a parameter comprising at least one of the group consisting of current and voltage.
33-85. (canceled)
Description
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0094] Some embodiments of the present disclosure are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example, and for purposes of illustrative discussion of embodiments of the present disclosure. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the present disclosure may be practiced.
[0095] In the drawings:
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DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION
[0108] The present invention, in some embodiments thereof, relates to the field of navigation within body cavities by intrabody devices, and more particularly, to guidance of the placement of intrabody devices, optionally including implantable devices.
Overview
[0109] An aspect of some embodiments of the present disclosure relates to electrical field-guided positioning of a second device within a body cavity, using electrical field mapping information generated from electrical field measurements by electrodes of a first device. Herein, electrical field measurements may also be referred as “electrical measurements”. Reference to ‘electrical field measurements’ as used herein may refer to direct measurements of the electrical field at the position of the measurement, or may refer to measurements of parameters, such as voltage, that are indicative of the electrical field at the position of the measurement. Electrical field measurements optionally include, for example, measurements of voltage or current.
[0110] Herein, the term “first device” refers to an electrode-carrying probe (a “probe”)—for example, an electrode catheter—insertable to and navigable within a body cavity; and configured to make electrical field measurements within the body cavity. In some embodiments, the first device carries a plurality of electrodes.
[0111] Herein, the term “second device” refers to medical devices, such as medical implements insertable to and navigable within a body cavity (e.g., to move the implement to a site of implantation and/or endolumenal operation). The medical implement (i.e., second device) may be any device insertable through a catheter, and/or another instrument such as an endoscope. Examples of medical implements (i.e., second devices) include: implantable pacemaker, stent, implantable ring, implantable valve replacement (e.g., aortic valve replacement, mitral valve replacement and/or tricuspid valve replacement), left atrial appendage (LAA) occluder, and/or atrial septal defect (ASD) occluder. In some embodiments, the second device is an Amplatzer septal occluder used to treat an atrial septal defect as described in more detail below with reference to
[0112] In some embodiments, electrical field mapping information comprises a map which associates measurements made by the electrodes of the first device to positions of the electrodes when carrying out those measurements (that is, the measurement data are position-mapped). Using electrical field mapping to guide movements of devices within a body cavity provides potential advantages, for example by reducing or eliminating a need for use of imaging techniques which use ionizing radiation (e.g., isotope and/or X-ray imaging) and/or access-limited imaging resources (e.g., MRI).
[0113] In some embodiments, using the electrical field mapping comprises application of a rule based on the map. The rule, in some embodiments, comprises direct lookup within the map, as if the electrical field measurement made by the second device was a measurement made by the first device. In some embodiments, the rule comprises transformation of the lookup result and/or the map to match second-device measurements to the map.
[0114] A rule optionally comprises other aspects. For example, it may comprise steps of selection from among different maps and/or map transformations to suit particular conditions of the second device (e.g., different configurations, conformations, and/or degrees of unsheathing), particular conditions of electrical field generation (e.g., which fields are being generated at any given moment of a procedure), and/or particular regions of navigation (e.g., there may be different transformations of the field mapping information, each suitable for finding the position of the second device in some region of the body cavity, but not necessarily suitable for a complete and accurate transformation of all the field mapping information).
[0115] In some embodiments, the rule is defined so that the electrical fields measured using the second device are a subset of electrical fields used in measurements made by the first device (e.g., three or more electrical fields are measured during first-device mapping, but only two or three electrical fields are measured for positioning of the second device).
[0116] Herein an electrical field generated at two different times using substantially the same generating device parameters, e.g., of voltage, current, frequency, and generating electrode configuration, is considered to be practically the same electrical field. This is regardless of minor actual variations in the electrical field due to factors such as body movement and/or electrical component property drift, although these may be considered as contributing time-variability (or “noise”) to the electrical field. In some embodiments, the electrical field is continuously generated from electrodes which remain in place. However, these conditions are not strictly necessary to recreate the same electrical field parameters, and accordingly the same electrical field. For example, an electrical field generator can be briefly turned off and then on again, and the electrical field generated is still “the same” electrical field, as the concept of electrical field identity is used herein.
[0117] Furthermore, the definition herein of the identity of an electrical field over time discounts influences of measurement devices on the electrical field. To the extent that such influences occur (e.g., because the measuring device's impedance is not infinite), they are considered to modify an electrical field that still retains its “identity”.
[0118] In some embodiments, the first device comprises a sensing catheter or other device comprising 2, 3, 4, or more electrodes, and the electrical field mapping information is derived in part by using one or more known distances between the electrodes (inter-electrode distances) to set distance scaling of simultaneous electrical field measurements from each other. This scaling provides a constraint that allows estimation of relative position upon application of the constraint to a set having a suitably large number of measurements made as the first device moves about within the body cavity. The first device may itself be navigated and/or have its position determined using this estimation of relative position.
[0119] Construction and first-device use of maps of this type may be performed, for example, as described in International Patent Publication No. WO2018/130974 and/or in International Patent Publication No. WO2019/034944, the contents of which are included herein by reference in their entirety. Herein, measurement data that are position-mapped using the known inter-electrode distances are said to be “self-scaled”.
[0120] The inventors have realized that the self-scaled position-mapped measurement data (for example) provides a basis for navigation of a second device, even if the second device has only one electrode. Accordingly, in some embodiments, the method provides for navigation based on single-electrode measurements of a second device, based on self-scaled, position-mapped measurements made by a plurality of measuring electrodes of a first device—even though the second device is unsuitable for self-scaled position mapping.
[0121] This represents a potential advance, insofar as electrical field-based measurements by a single-electrode device as such are generally not susceptible to use with self-scaled position-mapped measurements (since there is only one electrode, there is no well-known inter-electrode distance).
[0122] While methods of electrical field-based guidance which do not use self-scaling are also known, their use is not always available and/or suitable. For example, these may rely on calculations of field geometry and/or careful configuration of how the electrical fields are generated, which are potentially unavailable, time-consuming, and/or prone to errors in setup and/or model assumptions.
[0123] Nevertheless, it should be understood that the electrical field mapping information used in some embodiments of the present disclosure to estimate second-device positioning is optionally obtained by a method that does not rely on self-scaling; for example, systems wherein electrical fields are generated to control their voltage gradient geometry (e.g., to be substantially linear within a certain region of interest), and/or systems wherein electrical field voltage gradients are calculable from other available information such as electrode positions and the dielectric properties and structure of body tissue through which electrical fields are generated.
[0124] Furthermore, the inventors have realized that when electrodes of both the first device and the second device are of sufficiently similar size and also of sufficiently similar impedance (e.g., pass minimal currents), any differences in how each “sees” the electrical field is potentially minimal enough that relative measurement differences made using what are essentially two different measurement systems can be ignored.
[0125] In some embodiments, an actual difference in one or more of these conditions (or another condition affecting measurement similarity) is compensated for by calibration, and/or accounted for as a limitation on the accuracy and/or precision of position estimation. For example, differences can optionally be reduced by the application of corrections which can be learned from the measurements themselves, and/or by calibration steps using equipment available at the time of the procedure, and/or pre-programmed for known devices.
[0126] For example, in some embodiments, systematic offsets and/or scale differences in the measurements can be corrected by checking for measurement differences at positions which are well-defined outside of the electrical field measurements themselves. As examples, measurements from two different devices are estimated, in some embodiments, to originate from comparable positions if they are both made by one or more of: [0127] At a same point of insertion (such as a heart atrial septum). [0128] While both the first and second device occupy adjacent positions, e.g., in contact with each other or at a known offset from each other. [0129] Along a same path (for example along a same arc of a catheter as it advances into the body cavity). [0130] At same extremes of available movement limited by lumenal walls of the body cavity. [0131] At same landmarks such as blood vessel branching points, blood vessel ostia, heart valves, tissue folds, and/or appendages (such as the left atrial appendage). [0132] At same electrically measured landmarks, such as local or global minima and/or maxima of measured voltage, or maximum- or minimum-amplitude slope (local or global) of voltage change; including features which include joint consideration of a plurality of voltage fields generated with different orientations, frequencies, and/or currents. [0133] At any other “same position”, however this may be identified.
[0134] In some embodiments, calibration involves corrections to compensate for entities that influence the measurements measured by the second device. For example, whilst a conductive portion of the second device is used to measure electrical field measurements in the body cavity, the same conductive portion, as well as other, optionally dielectric portions of the second device may interact with the electrical fields in the body cavity. As would be understood by the skilled person, such conductive or dielectric portions would interact with and modify the electrical field, thereby affecting the electrical field measurements made using the electrode conductive portion of the second device. This would lead to a mapping of the second device measurements to wrong positions in the body cavity, and so a correction may be required to account for the field modifying portions (referred to herein as field modifiers). As described in more detail below correcting errors can involve one or more of: correcting the rule for mapping measurements to positions, correcting the measurements before applying the measurements to the original rule, or correcting the resulting positions provided after applying the measurements to the original rule. The original rule (that does not account for field modifiers) is referred to below as a baseline rule.
[0135] Since the second device is typically a medical implement such as an implant, the second device may have one or more field modifiers that need to be accounted for when guiding the second device in the body cavity based on the measurements made using the second device itself. The following examples are therefore of particular interest in the event that the second device comprises field modifying portions. As mentioned above, the field modifying portions may be conductive or dielectric, or may otherwise be any portion of the second device that modifies the electric field.
[0136] In some embodiments, the errors generated as a result of applying the baseline rule to the second device measurements are corrected at least in a region of interest within the body cavity. For example, in some embodiments, the second device comprising the field modifier is an implement to be implanted in a certain position within the cavity, and so it is useful to have the highest accuracy of the navigation at that certain position or at least in the vicinity of that position. In the following, the vicinity of the certain position is referred to as a region of interest, but the term region of interest may be used for regions being of interest for other reasons. In some embodiments, the errors are corrected by modifying the baseline rule, so that the modified rule provides corrected positions. In some embodiments, the baseline rule is used, and the erroneous positions it provides are corrected.
[0137] In more detail, the correction to the measurements/baseline rule/positions is determined using one or more corrective electrodes. The specific examples below refer to a single corrective electrode, but it would be appreciated that a plurality of corrective electrodes may equally be used. The corrective electrode(s) are disposed on a device (referred to herein as the corrective device) separate to the second device that is configured to be disposed in the body cavity. The corrective device may be a catheter device similar to the first device used to obtain measurements for generating the baseline rule. In some embodiments, the corrective device may be a catheter of a different kind. For example, the first device may be configured for navigate in the entire body cavity, while the corrective device may be configured to be anchored to the region of interest. The position of the corrective electrode may be restricted to the region of interest in the body cavity.
[0138] The corrective electrode may be used to obtain electrical field measurements in the region of interest in the presence of the field modifier (e.g. when the second device is also in the vicinity of the region of interest). These measurements taken using the corrective electrode in the presence of the field modifier are then used as follows to compensate for the presence of the field modifier.
[0139] In a first example, the measurements taken using the corrective electrode in the presence of the field modifier are mapped to positions by applying the baseline rule (thereby giving inaccurate positions of the corrective electrode). These positions are compared to a known position of the corrective electrode. The comparison of the inaccurate positions obtained by measurements and the known positions can be used to determine a correction. The known position of the corrective electrode can be obtained by applying the baseline rule to measurements taken using the corrective electrode, when the measurements were taken before the field modifier (e.g. the second device) was introduced to the region of interest. In other words, the known position of the corrective electrode can be obtained using measurements obtained in the absence of the field modifier. This assumes that the corrective electrode does not change position in the region of interest between the measurements taken in the absence and the presence of the field modifier. In other embodiments, the known position may be obtained using various imaging techniques as would be known to the skilled person, or any other suitable technique that is independent of the measurements made using the electrode itself.
[0140] For example, the baseline rule may be modified so as to transform readings of the corrective electrode in the presence of the field modifier to the known position of the corrective electrode. In another example, results of applying the baseline rule to readings of the corrective electrode obtained in the presence of the field modifier are modified to fall on the known position of the corrective electrode. In another example, the readings of the corrective electrode are modified such that applying the baseline rule to the modified readings results in positions corresponding to the known positions of the corrective electrode.
[0141] In a second example, measurements are taken using the corrective electrode in the absence of the field modifier (when the second device is not in the region of interest or in the vicinity of the region), and further measurements are taken using the corrective electrode in the presence of the field modifier (when the second device is also in the region on interest). The measurements taken using the corrective electrode in the presence and absence of the field modifier may be taken in any order. A corrective registration function is then defined based on these two sets of measurements. In particular, the corrective registration function may be defined based on a group of positions obtained by applying the baseline rule to the measurements in the presence of the field modifier (denoted {a}), and a group of positions obtained by applying the baseline rule to the measurements in the absence of the field modifier (denoted {b}). The corrective registration function is defined as a registration transformation that transforms each member of {a} to the corresponding member of {b}, that is, the position of each corrective electrode as provided by the baseline rule in the presence of the field modifier is registered with the position of the same corrective electrode as provided by the baseline rule in the absence of the field modifier. This ensures that the readings of the corrective electrode in the presence of the field modifier are registered to the correct positions (i.e. the positions provided by measurements in the absence of the field modifier). This condition may be symbolized as:
f({a})={b}
[0142] In addition, the corrective function may be required to register positions obtained by the baseline rule in the absence of the field modifier to themselves (i.e. the positions in the cavity that are not in the vicinity the region of interest and for which the position provided by the baseline rule is the best available approximation of their current position. These positions are denoted {X}. To facilitate smoothness of the corrective function, the latter condition may be made by requiring that the positions in {X}∪{a} are registered to the positions in {X}∪{b}. That is:
f({X}∪{a}).fwdarw.{X}∪{b}
[0143] Thus, once measurements are obtained using the second device in the presence of the field modifier, they may be mapped to positions by first applying the baseline rule to the readings to obtain inaccurate positions, and then applying the corrective function f to the inaccurate positions to obtain corrected positions.
[0144] In some embodiments, similar logic is applied by correcting the electrical field measurements, rather than the positions obtained from the measurements. In such embodiments, a corrective function g is generated based on measurements taken using the corrective electrode(s) in absence of the field modifier, symbolized herein by the symbol {y}; and measurements taken using the corrective electrode(s) in presence of the field modifier, symbolized herein by the symbol {z}. The corrective function g is required to be smooth, and fulfill the following two conditions:
g({z})={y};
g:({V}∪{z}).fwdarw.{V}∪{y}
Where {V} are the measurements taken at positions that are not in the vicinity of the region of interest.
[0145] In such embodiments, readings received from the second device are first corrected by the corrective function, and the corrected readings are transformed to corrected positions by the baseline rule.
[0146] It is noted that the field modifier is not necessarily static. For example, it may move from one place to another (for example as the second device moves), causing at each place a different field modification. Additionally or alternatively, the field modifier may change orientation (for example as the second device changes orientation), and cause at each orientation a different field modification. Additionally or alternatively, the field modifier may be electrified, so that its dielectric properties change, and it may modify the field differently even without changing position and/or orientation. Additionally or alternatively, the field modifier may change shape or configuration. For example, the field modifier may a medical implement that is deployable from an insulating sheath, and the extent of modification of the electrical field may change depending on whether the field modifier is in a deployed configuration, or if the field modifier is retracted inside the sheath. In all such cases, the above procedures may be repeated so as to allow following the field modifier as the modifier changes position, orientation, dielectric properties, and/or configuration. The rate of repeating the correction procedure may depend on the rate at which the field modifier changes, and the accuracy demands put on the following process: if less accurate following is acceptable, a slower rate of repetitions may be used.
[0147] Potential advantages in using electrical measurements from a second device in order to guide its navigation and/or estimate its position include reducing or eliminating a need for imaging and/or position finding using exogenous measurement methods. For example, it may be possible to eliminate use of an esophagus-inserted (or other endoscopically positioned) ultrasound transducer and/or ionizing radiation imaging methods. This may in turn obviate a need for the use of general anesthesia and/or the need for an attending anaesthesiologist thereby reducing the overall cost of medical procedures. Patient recovery time may also be faster for procedures performed without the use of general anesthesia.
[0148] An aspect of some embodiments of the present disclosure relates to the electrical field-guided positioning of a second device within a body cavity, using electrical field mapping information generated from electrical field measurements by electrodes of a first device, wherein the second device is different in shape and/or electrical characteristics from electrodes of the first device.
[0149] For example, the electrodes of the first device may be relatively small—e.g., a millimeter or two in length and/or diameter.
[0150] The second device, in contrast, may be an implantable device or other medical implement comprising an electrically conductive portion of several millimeters, in each of one or more dimensions, having a surface which is exposed and/or configured to be exposed upon intralumenal deployment and/or operation of the second device. The electrically conductive portion of the second device is used as the electrode portion of the device. Exemplary sizes of the electrically conductive portion, in each of the one or more dimensions include sizes larger than the measurement electrodes of the first device by a factor of at least 2, 3, or 4, and/or at least 5 mm, at least 10 mm, 20 mm, or more. That conductive portion is wired by an insulated wire, in some embodiments, to form the electrode (electrode portion) used in making electrical field measurements.
[0151] The conductive portion may be used as an electrode, having a form provided primarily for a non-measurement function: for example, as a support, stent, plug, screw, anchor, needle, net, valve, frame, and/or other non-measurement function. In other words, whilst the conductive portion's primary function may be structural (i.e. not for measuring, but instead has a mechanical function), the conductive portion can have a secondary function as a measuring electrode. In some specific examples, the second device is a device (for example, Amplatzer Septal Occluder, Watchman LA appendage occluder, or a Cardioband anchor) which does not comprise electrodes, but comprises conductive structural portions that may be used as electrodes to measure parameters of electrical fields. In some embodiments, the deployment of the second device includes deployment of the conductive portion through a shape alteration, e.g., from a compact form (e.g., such as may be deliverable via a catheter) to an expanded form. In some embodiments, the exposed surface of the conductive portion is exposed by removal of to an insulating and/or partially insulating surface. For example, a metal stent coated with a fully or partially insulating coating may be exposed by having a portion of the coating removed in order to form an electrode (by exposing the conductive material that can function as an electrode).
[0152] In some embodiments, guidance of movement of the second device is performed using a rule which treats measurements made actually using the second device as if made by an electrode of the first device placed in some particular relationship to the second device. Herein, this is referred to as the equivalent first-device electrode position. For example, if the electrode portion of the second device is a linear conductor extending in a substantially linear (constant voltage gradient) electrical field, then the equivalent first-device electrode position is optionally at the geometrical center of the second device. For example, the equivalent first-device electrode position may be at the middle of the second device electrically conductive portion, and the rule may be “transform the measurements made by the second device to positions, using the rule generated for transforming readings of the first device to positions; and attribute the obtained position to the center of the electrode portion (the conductive portion) of the second device”.
[0153] Optionally, the equivalent first-device electrode position is fixed relative to the second device, as in the aforementioned example. In some embodiments, the equivalent first-device electrode position is dynamic relative to the second device. For example, insofar as the voltage gradients are known (from the map made using the first device), and the shape of the second device's conductive electrode portion is also known (e.g., based on its design and deployment stage), it can be determined using standard techniques what measurement would be made as the second device moves to different positions, and, accordingly, what the equivalent first-device electrode position is for each of those positions, even if not always the same relative to the position of the second device. For example, based on the gradients and the structure of the second device, an equivalent first-device electrode position may be determined as a position at which a point electrode should be standing in order to measure the same measurement as the electrode-portion of the second device measures; and the rule may be: “transform the measurements made by the second device to positions, using the rule generated for transforming readings of the first device to positions; and attribute the obtained position to the determined equivalent first-device electrode position”.
[0154] In some embodiments, calibrations (e.g., using any of the reference position types described herein above) take into account relative differences between first device and second device geometry. For example, an expanded second device potentially encounters a wall physically, even though its equivalent first-device position remains remote from the wall. The distance being known or estimated, a contact with the wall provides a potential calibration point for aligning, scaling, and/or confirming the alignment/scaling of the original first-device measurement map with measurements now made by the second device.
[0155] An aspect of some embodiments of the present disclosure relates to the electrical field-guided positioning of a second device within a body cavity, using electrical field mapping information generated from electrical field measurements by electrodes of a first device, wherein:
[0156] The second device is susceptible to assume a plurality of conditions which cause it to act as an electrode with different properties, and Among those conditions among which is a subset of conditions wherein it most closely approximates electrical field measurement characteristics of one or more electrodes of the first device.
[0157] For example, in some embodiments, the electrodes of the first device may be relatively small—e.g., a millimeter or two in length and/or diameter.
[0158] The second device, in contrast, may be an implantable device comprising an electrically conductive portion of several millimeters in one or more dimensions (e.g., in a range of 5-30 mm). That conductive portion is wired, in some embodiments, to form the electrode used in making electrical field measurements.
[0159] In some embodiments, the second device is delivered through and/or within an electrically insulating sheath. As the device leaves the sheath, in some embodiments, it gradually assumes different electrical properties affecting how it “sees” the electrical fields around it.
[0160] In some embodiments, navigation of the second device takes place while it is in a partially un-sheathed configuration which provides to it electrical field measurement characteristics similar to those of one or more of the electrodes of the first device. Herein, any such configuration is referred to as a “mimicking” configuration relative to one or more electrodes of the first device. For a second device in a mimicking configuration, the rule for applying electrical field mapping information obtained using electrodes of the first device is optionally as straightforward as a direct lookup. Optionally (for example if the mimicking configuration mimics imperfectly), scaling and/or offset corrections (if applied at all) are made relatively simple and direct by use of the mimicking configuration. The inventors have found that a useful degree of mimicry is optionally obtained, in some embodiments, by extruding a second device until electrical field measurements begin to be received at measurement value levels (e.g. voltage values) corresponding (e.g., within about ±20%) to levels of first device electrode measurements at about the same location—and then stopping. Optionally, magnitudes of measurement noise are used as an indicator. For example, upon reaching, during device extrusion, reaching an impedance low enough to make measurements with a root mean square noise amplitude similar (e.g., within ±20%) to the noise amplitude of first-device electrodes is used as a signal that a mimicking device configuration has been reached.
[0161] In some embodiments, the second device is reconfigurable during navigation between the mimicking configuration and another configuration. The other configuration may be, for example, a more-unsheathed, more-extended and/or more-deployed configuration, or any other configuration that causes more of the conductive portion of the second device to be exposed. Optionally, this is used to obtain a direct calibration of the non-mimicking configuration to a rule using the electrical field mapping information from the first-device measurements. For example, the second device, in a mimicking configuration, makes measurements at a first position in the body cavity, and a rule applied to determine its position. The second device is then converted to a non-mimicking configuration, resulting in a known change in position relative to the determined position. More measurements are made. This can be repeated at one or more additional positions. The non-mimicking configuration, in some embodiments, comprises exposure of more of the surface of the second device outside an insulating sheath such as a catheter sheath; for example, at least 2×, 3×, 4×, or more surface along a longitudinal axis of the sheath than is exposed by an electrode of the first device. In some embodiments, the non-mimicking configuration comprises a conformational change in a shape of the second device, for example, a radial expansion of part of the device (e.g., an expansion to either side of a longitudinal axis of the device). Optionally, the radial expansion increases a diameter of the device by at least 2×, 3×, 4×, or more. In some embodiments, the non-mimicking configuration comprises exposing a surface of the second device which is specially formed to perform a non-electrical function. For example, the second device optionally comprises a screw to thread, serrations, tool-receiving surface (e.g., a hexagonal recess), or another surface which is shaped to perform a mechanical function such as fastening, cutting, and/or engaging with a mating surface.
[0162] In some embodiments, mimicking/non-mimicking configuration pairs of measurements provide calibration indications which allow the first-device mapping data to be recalibrated to measurements by the second device in the non-mimicking configuration. In some embodiments, these measurements, optionally with suitable extrapolations and interpolations, are used stand-alone as a new set of position-mapped measurements, which indicate and/or guide further positioning of the second device.
[0163] In some embodiments, the second device is optionally itself used to make measurements of the types described in relation to the first device, e.g., a cloud of measurements which is used to generate a rule converts electrical field measurements into positions. In embodiments wherein the second device is not addressable as a plurality of (electrically mutually isolated) electrodes, this potentially limits methods by which the rule is generated, for example to a non-self-scaled method, optionally based on methods, principles, and/or systems for position estimation without self-scaling mentioned hereinabove.
[0164] Before explaining at least one embodiment of the present disclosure in detail, it is to be understood that the present disclosure is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings. Features described in the current disclosure, including features of the invention, are capable of other embodiments or of being practiced or carried out in various ways.
Methods of Second Device Navigation
[0165] Second Device Navigation with Selected Operations Illustrated
[0166] Reference is now made to
[0167] The flowchart of
[0168] In some embodiments, first device 12 comprises an electrode catheter having two or more electrodes arranged at known distances from each other. A typical parameter that can be determined is impedance, which may itself be determined, e.g., from measurements of voltage made within one or more time-varying electrical fields. First device 12 is illustrated in
[0169] In some embodiments, impedance is calculated from voltages/or and current measurements at electrodes of first device 12. In some embodiments, impedance is calculated from voltage measurements at electrodes of first device 12 and known current injected at electrodes of first device 12. In some embodiments, electrical measurement may include any dielectric parameter measured at one or more electrodes of first device 12. Electrical measurement may include voltage measurements, current measurements, impedance measurements and any combination thereof.
[0170] In some embodiments, measurements are accessed which were obtained from a first device 12 when the first device 12 was used for mapping and/or reconstructing the body cavity; e.g., to obtain measurements for a map and/or reconstruction used in an interventional procedure. Mapping and/or reconstructing the body cavity may be performed, for example, as described in International Patent Publication No. WO2018/130974 and/or in International Patent Publication No. WO2019/034944, the contents of which are included herein by reference in their entirety. In some embodiments, measurements are accessed which were obtained from a first device 12 when the first device 12 was used solely for obtaining such measurements, e.g., for calculating field mapping information to be used in navigation of the second device.
[0171]
[0172] At block 104, in some embodiments, a rule for transforming electrical field measurements to positions is generated, using the electrical field measurements made by the first device 12. Herein, such a rule is also referred to as a position estimation rule.
[0173] In some embodiments, blocks 102 and 104 may be omitted, and replaced by accessing a position estimation rule. The position estimation rule may, for example, have been previously generated from measurements which were obtained from a first device 12 comprising a plurality of electrodes configured to measure electrical fields generated to extend through the body cavity 49. In other words, the position estimation rule may have been generated at a separate, earlier point in time by carrying out steps 102 and 104, but the disclosed methods may not necessarily explicitly involve these steps and may instead involve accessing the previously generated position estimation rule.
[0174] Electrical fields 62A, 62B, 62C (represented as a crossing grid of dotted lines in
[0175] A plurality of electrical fields are generated (e.g., between different electrode sets, and optionally differentiated by being generated at different times and/or frequencies). Each electrical field may be treated as defining a different coordinate of a coordinate system defined by the fields taken together. Measurement sets, each set measuring a plurality of electrical fields extending through an individual position within the body cavity 49, provide a distinctive “tag” for that position. Each such a “tag” may be considered the position of the electrode that took the measurement, expressed in coordinates of the field-generated coordinate system.
[0176] Generating electrical fields having mutually orthogonal voltage gradient components helps ensure that each position is associated with a different combination of electrical field measurements. However, the electrical field gradients are not necessarily orthogonal. While three voltage fields are illustrated in
[0177] The marking dots 63 used to represent measurement cloud 60 (
[0178] Nearby positions, in some embodiments, tend to be associated with correspondingly relatively similar sets of voltage measurements. However, relative positions of measurements 61 of measurement cloud 60 may not be initially known. For example, the distribution of electrical field gradients may include significant non-linearities with respect to their corresponding magnitudes and orientations in space. This potentially interferes with the use of electrical field measurements as a direct indication of position; e.g., isopotential lines of electrical fields bend through space, and may be closer or further apart depending on the distribution of structures with different dielectric properties through which the electrical fields extend.
[0179] However, position is potentially recoverable by using the measurement values themselves, along with additional information, to produce a reconstruction of the spatial distribution of the positions from which the fields have been measured. Herein, such a reconstruction is also referred to as a map.
[0180] In some embodiments, the rule for transforming electrical field measurements to positions optionally includes a rule for transforming a voltage measurements cloud (e.g., a group of measurements defined in a space with dimensions corresponding to measurements of different electrical fields and/or by different electrodes) to a position cloud (e.g., positions in a model of three-dimensional physical space associated with the measurements). In some embodiments, the rule may include a rule for transforming voltage measurements to positions within the body cavity.
[0181] In some embodiments, the position estimation rule generated in block 104 comprises use of such a map.
[0182] The map is optionally created using one or more of several available methods. Methods of converting electrical field measurements made by an electrode catheter to a map of positions at which those measurements were made are described, for example, in International Patent Publication No. WO2018/130974 and/or in International Patent Publication No. WO2019/034944, the contents of which are incorporated herein by reference in their entirety. In some embodiments, known distances between electrodes on an electrode catheter or other electrode probe are used to constrain the relative positions at which simultaneous measurements are made. The mutual distance constraint (indicated by the connecting lines 61) provides a kind of “ruler” that allows local scaling to be determined, in some embodiments, even when the change in voltage and/or impedance measured as a function of position is variable in magnitude and/or direction. Additionally or alternatively (for example), the problem of non-linearity is managed by computational modeling of the electrical fields, and/or by the conditions of generating the electrical fields: e.g., electrodes are optionally placed at sufficient distances and relative angles relative to the body cavity 49, so that significant portions of the electrical field change about linearly as a function of position offset along some direction.
[0183] The position estimation rule generated in block 104, in some embodiments, may be considered equivalent to application of a mapping between values of electrical field measurements made using the first device 12, and corresponding positions in space. Optionally, the rule includes additional features, such as modification for calibration with measurements made by a second device 20 having different electrical measuring characteristics than the electrodes of the first device 12. In some embodiments, the rule is supplemented by additional information; for example: constraints on where and/or when it is valid, and/or how it may be interpolated and/or extrapolated to positions which were not measured.
[0184] Optionally, the measurements from which a rule is generated are “over-determining”—that is, more measurements (e.g., of different electrical fields) are made at each position than are actually needed to uniquely identify positions. This potentially helps in reducing ambiguity and/or error in generating the rule. For example, there may be four or more electrical fields measured, even though the measurement values of only three crossing electrical fields may be sufficient to construct a rule which uniquely determines a position in space. A rule specifying spatial correspondences with just two, or even just one electrical field may be sufficient to determine position in a case where there are other constraints on position. For example, where position varies substantially along a single axis (e.g., because movement is constrained by advance out of or retraction into a catheter tube), position can potentially be determined from knowing the location of the axis in space (e.g., an orientation and a point of intersection), and a single electrical field measurement.
[0185] At block 105, in some embodiments, a second device 20 comprising an electrically conductive portion 21 (cf.
[0186] To be so-configured, the second device 20 is at least configured to act as an electrode within an electrical field measurement system. In particular, at least a conductive portion 21 of the second device 20 is itself electrically conductive (e.g., comprised of a metal or other low-electrical resistance material), and is furthermore connected to an electrical measuring device via a conductive member. “Configuring” the second device may therefore involve exposing at least a portion of the conductive portion as described in more detail below such that the conductive portion can “see” electrical fields and interact with them.
[0187] The conductive member, in some embodiments, is also a structural member to which the second device 20 is mechanically attached. The structural member may comprise, for example, a cable, tube, and/or strut which is operated to mechanically manipulate the second device 20; e.g., to extrude it from an electrically insulating catheter sheath. Where reference is made to a ‘structural member’, this is intended to refer to portions of the second device that are not primarily used for measurements. In other words, as described above, a structural member has a primary function that is mechanical, rather than to measure mechanical fields. A structural member is therefore not be designed to function as an electrode, but it is capable of functioning as a electrode as a secondary function.
[0188] The second device 20, in some embodiments, moreover comprises a deploying device; that is, a device which is delivered to the body cavity 49 in a first shape (for example, a shape suitable for movement along the lumen of a catheter tube), and deploys to a second shape (for example, a shape suitable for one or more functions of anchoring, blocking, moving, interconnecting, cutting, restraining, and/or affixing). In some embodiments, the second device 20 itself retains a substantially constant shape (e.g., a linear shape), but is optionally extruded more or less into the body cavity 49 from within a relatively insulating sheath. These changes in shape and/or extrusion distance also affect, in some embodiments, how measurements are made and/or how position-estimation rules are applied.
[0189] Two broad approaches by means of which a second device 20 and/or the position estimating system overall can be further configured to be suited to application of the rule of block 104 are (1) using and/or modifying the second device 20 so that it behaves more like electrodes of the first device 12 (for example by adjusting the length of the conductive portion of the second device that is exposed to act as an electrode), and (2) using calculations of how different physical and/or electrical characteristics of the second device 20 affect application of the rule of block 104. This is implemented, optionally, as modification of the rule of block 104 itself, and/or as further adjustments made upon application of the rule at block 108.
[0190] A third approach is to take measurements under special conditions which can be used to calibrate second device 20 measurements to first device 12 measurements. Any one, two, or three of these broad approaches are optionally used in some embodiments of the present disclosure. It is noted that in some embodiments, no calibration or rule modification is required, and the rule generated by the first device may be used for positioning the second device straightforwardly.
[0191] Electrodes of the first device 12 may each comprise, for example, a relatively small ring, e.g., of 1-2 mm diameter and 1-2 mm length (these measurements refer to the portions of the electrode electrically exposed to the environment of the body cavity 49, and exclude, for example, insulated wire conductors used to conduct current to a measurement device). The electrically conductive portion 21 of the second device 20, in contrast, may be larger (e.g., having at least one dimension in a range of 5-30 mm or larger) and/or more complex in shape, potentially resulting in different electrical field measurement properties.
[0192] In some embodiments, the second device 20 is made suited to application of the rule by being placed in a configuration selected to (in other words, by being configured to) mimic the electrical field measurement properties of an electrode of the first device 12. In a relatively simple example, the second device 20 is extruded from an insulating sheath to a small extent, e.g., so that only a portion of about the size of the electrodes of the first device 12 is electrically exposed to the environment of the body cavity 49 within which it is moving.
[0193] This “mimicking configuration” potentially helps to reduce complexity and/or increase accuracy of the rule for determining positions of the second device 20, as next explained.
[0194] Examples of different devices and corresponding different configurations thereof are discussed, for example, in relation to
[0195] When positions of the second device 20 are to be estimated while the second device 20 is not in a mimicking configuration, measurements made by the second device 20 are optionally subjected to further processing.
[0196] At block 106, in some embodiments, second-device measurements are received. At block 108, in some embodiments, the rule of block 104 is applied (optionally with additional corrections, for example, as next described; depending on whether the rule of block 104 is modified on the fly according to conditions of calibration and/or second-device configuration). At block 110, in some embodiments, the second-device position estimate is provided. In some embodiments, the second-device position estimate may be used for navigating the second device 20 within the body cavity, for example: during a medical procedure.
[0197] The operations of block 108-110 are optionally implemented by a rule as simple as a lookup performed on the map of first-device measurements to first-device position, using instead the second-device measurements of block 106. This is particularly well-suited to embodiments of the method wherein the second device 20 is operated in a mimicking configuration.
[0198] Alternatively, the rule includes additional corrections to adjust for differences between the second device 20 and the first device 12. In particular, corrections may be applied to account for the presence of field modifiers in the body cavity, as described above.
[0199] The electrically conductive portion 21 of the second device 20 is effectively at a single voltage potential (disregarding minor internal resistances and reactivity). More particularly, it is measured as having a single potential at any given time by the electrical measuring device to which it is connected. Accordingly, the second device 20, even when fully expanded, can be understood as having an equivalent first-device electrode position, given by applying the rule generated from first-device measurements to second-device measurements.
[0200] Second-device measurements of different electrical fields may, however, associate to different corresponding equivalent first-device electrode positions (even if measured simultaneously). This potentially complicates position determination, insofar as a set of simultaneous measurements made using the second device 20 may not, in fact, fully correspond to a measurement set made at any particular position of the first device 12. In some embodiments, this is overcome by calibration (methods of calibration are discussed herein, for example, in relation to
[0201] The equivalent first-device electrode position of the second device 20 is likely to be within (or at least nearby) an envelope defined by the larger physical extent of the second device 20. Accordingly, in some embodiments, the position of the second device 20 is also defined as an envelope around the equivalent first-device electrode position (this can be implemented as a suitable modification to the rule of block 104). This allows estimation, e.g., of distances to contacts with walls of the tissue cavity, even though the equivalent first-device electrode position itself never reaches such a contact. For second devices 20 that undergo a conformational change during use (e.g., expansion during deployment): both the envelope, and its relationship to the equivalent first-device electrode position, are optionally varied as a function of shape. In some embodiments, these variations are made part of the rule of block 104. Different methods may be used to estimate a relationship between a second-device shape envelope and the equivalent first-device electrode position. In some simple implementations, a geometric center of the second device 20 (e.g., of its envelope, and/or of its center of mass) is assigned as the equivalent first-device electrode position. Optionally, interaction of the second device 20 with the electrical fields is electrically modeled, which can take into account, e.g., effects of electrical field gradient non-linearities, and/or influences of the second device 20 itself on the distribution of electrical field potentials. For example, such a model can take into account the presence of field modifiers in the cavity (such as conductive portions disposed on the tool) and the model can account for such field modifiers with a correction to the mapping rule or to the second device measurements. Conversely, the behavior of the equivalent first-device electrode position as a function of manipulation of the second device 20 is optionally used as an indication of second-device state, for example as described in relation to
[0202] From block 112, in some embodiments, further measurements, rule applications, and position estimates may be repeatedly performed as second device 20 navigates in body cavity 49 and/or as the second device is deployed. The iterative process may continue until no further estimate of the position of the second device 20 is required (for example when the position estimates converge within a predetermined error threshold). The second device 20 may be placed into different configurations in different loops, which can affect, for example, how the rule is applied at block 108.
[0203] Second Device Navigation in Two Configurations
[0204] Reference is now made to
[0205] At block 200, in some embodiments, first-device measurements are accessed, and at block 201, a position estimation rule is generated. These blocks correspond, in some embodiments, to blocks 102 and 104 of
[0206] At block 202, in some embodiments, second-device measurements are received, with the second device 20 in a mimicking configuration (for example, as described in relation to
[0207] At block 206, in some embodiments, second-device measurements are received, with the second device 20 in a changed-shape configuration (for example, as described in relation to
[0208] From block 212, in some embodiments, further measurements, rule applications, and position estimates may be performed until estimating of the position of the second device 20 ends or is no longer required.
[0209] In the first instance, operations of blocks 202 and 204 are distinguished from the operations of blocks 206 and 208 in that the second device 20 is in a differently-shaped configuration (mimicking configuration and changed-shape configuration).
[0210] In some embodiments, an additional distinguishing feature between blocks 202 and 204, and 206 and 208 is that the type of motion for which position estimations are generated is different. In some embodiments, movements during the position estimation in blocks 204 and 206 are free in three dimensions. This may be suitable, for example, for positioning to reach the deployment-ready position shown in
[0211] In some embodiments, position finding in blocks 206 and 208 is optionally performed while motion is constrained to operations which alter a deployment status of second device 20: for example, extrusion of second device 20 from catheter sheath 10 by advancing of connecting member 22, and/or actuation/deployment by other methods and/or control members. In some embodiments, second device 20 is elastically biased to self-expand or otherwise change shape as constraint from catheter sheath 10 is removed.
[0212] In cases where motion is limited to deployment movements, the position last estimated at block 204 is used, in some embodiments, as a base position. Subsequent position estimates are made as estimates of change from this position. For example, as second device 20 is extruded from catheter sheath 20, its equivalent first-device electrode position also advances, at least initially. With further expansion, there can also be a reversal of the direction of motion of the equivalent first-device electrode position, or another motion; for example, as described in relation to
[0213] Additionally or alternatively, in some embodiments, interconversion between a mimicking configuration and a changed-shape configuration is performed several times, at different positions. Optionally, the positions of interconversion are used as calibration anchoring locations, allowing a rule which generates first-device positions from first-device measurements to be transformed (e.g., by interpolation between calibration anchoring locations) to generate second-device positions from second-device measurements, even when the second device 20 is in a configuration which does not mimic first-device electrodes. The calibration, in some embodiments, is between second-device measurements and first-device measurements; determining, e.g., adjustments in offset and/or scale of second-device measurements so that they can be used like first-device measurements in determining device positions.
Second Device Measurement Calibration to First Device Measurement/Position Rules
[0214] Reference is now made to
[0215] The method of
[0216] The calibration, in some embodiments, is between second-device measurements and first-device measurements; determining, e.g., adjustments in offset and/or scale of second-device measurements so that they can be used like first-device measurements in determining device positions. Optionally, the calibration anchoring locations of the method of
[0217] At block 302, in some embodiments, first-device measurements are accessed, and at block 304, a position estimation rule is generated. These blocks correspond, in some embodiments, to blocks 102 and 104 of
[0218] At block 306, in some embodiments, a second device 20 is configured to a “rule-uncalibrated” configuration; that is, it is deployed into a shape which does not mimic an electrode of the first device. At block 308, the second device 20 is moved to a landmark position. This can be, for example, a position of catheter access into the body cavity 49 (e.g., a fossa ovalis or other point of transseptal penetration), and/or a position of farthest travel (e.g., a place at which advancement of the second device 20 is blocked by an encounter with a lumenal wall).
[0219] At block 310, in some embodiments, second-device measurements are received, which allows defining of a calibration anchoring position. From block 312, in some embodiments, the collection of calibration anchoring positions continues with repetition of block 308 and block 310 as necessary. Optionally, measurements at positions between well-defined landmarks (or offset from a single landmark in a known direction) are also collected for use as calibration anchoring positions, with their own positions being calculated according to the distance of advance along the path of travel. Once enough calibration anchoring positions have been collected, the method continues with block 314, wherein the position estimation rule of block 304 is modified, by use of the collected calibration information. At block 316, in some embodiments, the modified rule is provided. The modified rule becomes an optional basis for further position estimations, for example as described in relation to
Second Device Examples
[0220] Reference is now made to
[0221] In each of
[0222] In
[0223] For purposes of illustration, it may be presumed that the equivalent first-device electrode position is located along a central longitudinal axis 402 defined by the orientation of the distal tip of catheter sheath 10. However asymmetries of the second device 400 and/or the electrical field environment can potentially draw the equivalent first-device electrode position away from this central axis.
[0224] In
[0225] In
[0226] This forward-then-backward movement is potentially characteristic of deployment for devices of this type, and is optionally used as a marker to help a physician track the stage of deployment. For example: before the reversal, the physician can be reasonably confident that the device is collapsed enough to allow easy repositioning; while after the reversal, the physical can be reasonably confident that the device is expanded enough to anchor. Reference is now made to
[0227] The device of
[0228] Similarly to the situation in
[0229] Reference is now made to
[0230] The device of
[0231] Brackets 602A-602C show increasing offset during unsheathing from a central longitudinal axis defined by the orientation of a distal tip of catheter sheath 10. This is due to a predefined bend in second device 601 which it assumes upon unsheathing. Such a bend might allow, for example, sideways access to a surface, and/or be a feature of a guidewire allowing selection of an off-axis aperture to advance into.
[0232] A physician monitoring the increase in radial offset optionally uses this to learn the direction of radial offset, and/or to help gauge if the device is expanding unimpeded, or if it is being impeded, for example, by contact with a lumenal wall instead of a targeted aperture.
System for Second Device Position Estimation
[0233] Reference is now made to
[0234] In some embodiments, system 700 comprises one or more of: [0235] Catheter sheath 10, for example as described in relation to
Second Devices with a Plurality of Conductive Portions
[0243] Reference is now made to
[0244] Implantable device 800, in some embodiments, comprises a flexible member 801, which is configured to be secured to tissue around the perimeter a heart valve 55 using fasteners 803 (optionally screws). Upon being secured, the device can be cinched, shortening flexible member 801 and drawing the perimeter tissue together. This potentially treats leakage/regurgitation through heart valve 55 (a heart mitral valve, in the example shown) by bringing leaflets of the valve closer together.
[0245] Implantable device 800 is shown during a late stage of implantation, with the flexible member 801 still partially within catheter sheath 805 (from which it has been partially extruded). Several fasteners 803 have already been inserted to tissue, and fastener 803A (also electrically conductive) is in the midst of being inserted. Insertion is performed, in some embodiments, by rotation of cable 804 to which fastener 803A is removably attached. Cable 804 is itself also electrically conductive, and in electrical contact with fastener 803A.
[0246] In some embodiments, each fastener 803 is brought separately from a proximal end of the catheter sheath 805 to be secured into place by mechanical operation of cable 804. In some embodiments, cable 804 is attached to an electrical field measuring device, thereby converting fastener 803 (e.g., fastener 803A) into an electrical field measuring electrode. In some embodiments, this allows fastener 803 to act as a second device, for example as described in relation to
[0247] Radio-opaque markers 802 are optionally comprised of a conductive material (e.g., a radio-opaque metal). Optionally one or more of radio-opaque markers 802 are connected to a conductive wire 806 which extends to a proximal side of catheter sheath 805, where it is optionally connected to an electrical field measuring device. Radio-opaque markers 802 are optionally connected to a single wire 806, or to a plurality of separately conducting wires 806. When separately wired, positions of individual radio-opaque markers are optionally determined according to their equivalent first-device electrode position. When wired to a same conductor in common, the relationship of the equivalent first-device electrode position to the positioning of the radio-opaque marker 802 is potentially offset, e.g., to near a geometrical “center of gravity” of the electrically joined-together radio-opaque markers 802, or another location.
[0248] Movements of the equivalent first-device electrode position during implantation may provide additional information about device status (which is optionally used to track progress of implantation). For example, as each new electrically joined-together radio-opaque marker 802 is exposed upon extrusion from catheter sheath 805, there is potentially a relatively rapid (e.g., step-function) jump in estimated position. As the radio-opaque marker 802 approaches the wall of the left atrium 50, there may be an additional rapid change in estimated position, e.g., insofar as field density lines may be more concentrated near the body cavity wall, so that the contribution of the radio-opaque maker 802 to the overall measurement changes more rapidly as a function of its change in position.
[0249] It is noted that one or more radio-opaque markers 802 wired as one or more electrically isolated electrodes and/or a fastener 803 electrically isolated from the radio-opaque markers 802, optionally together form an electrode system comprising a plurality of electrodes. By controlling distances of extrusion of flexible member 801 and fastener 803, the distances of these elements (considered as electrodes) is optionally controlled so that it is known, and this system, in some embodiments, then used as a plurality of electrodes for self-scaled mapping of the body cavity, for example, as described for a first device in the overview, and/or in relation to
[0250] Also shown in
Example Second Device—Amplatzer Septal Occluder
[0251] As described above, the second device may be an implantable device and may have a conductive portion that has a primary function that is a non-measurement function (i.e. the conductive portion's primary function is structural). In some specific examples, the second device is an Amplatzer Septal Occluder as illustrated in
[0252]
[0253]
[0254] The septal device includes one or more electrically conductive portions connected to an electrical field measurer via a conductive member such as a wire. The conductive portion can therefore function as an electrode, meaning that voltages, or other measurements indicative of electrical fields can be measured using the conductive portion. The conductive portion may be either or both of the expanding portions 940 and 950 themselves, which have a primary, structural (mechanical) function as described above, but are also capable of functioning as electrodes when connected to an electric field measurer by another conductive member.
Example First Device—Circular Catheter
[0255] In some specific examples, the first device is a circular catheter, e.g., a Lasso® catheter, or a lasso-like catheter, for example as depicted in
General
[0256] It is expected that during the life of a patent maturing from this application many relevant implantable and/or endolumenally operated medical devices will be developed; the scope of the term implantable and/or endolumenally operated medical devices is intended to include all such new technologies a priori.
[0257] As used herein with reference to quantity or value, the term “about” means “within ±10% of”.
[0258] The terms “comprises”, “comprising”, “includes”, “including”, “having” and their conjugates mean: “including but not limited to”.
[0259] The term “consisting of” means: “including and limited to”.
[0260] The term “consisting essentially of” means that the composition, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.
[0261] As used herein, the singular form “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “a compound” or “at least one compound” may include a plurality of compounds, including mixtures thereof.
[0262] The words “example” and “exemplary” are used herein to mean “serving as an example, instance or illustration”. Any embodiment described as an “example” or “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments.
[0263] The word “optionally” is used herein to mean “is provided in some embodiments and not provided in other embodiments”. Any particular embodiment of the present disclosure may include a plurality of “optional” features except insofar as such features conflict.
[0264] As used herein the term “method” refers to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the chemical, pharmacological, biological, biochemical and medical arts.
[0265] As used herein, the term “treating” includes abrogating, substantially inhibiting, slowing or reversing the progression of a condition, substantially ameliorating clinical or aesthetical symptoms of a condition or substantially preventing the appearance of clinical or aesthetical symptoms of a condition.
[0266] Throughout this application, embodiments may be presented with reference to a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of descriptions of the present disclosure. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as “from 1 to 6” should be considered to have specifically disclosed subranges such as “from 1 to 3”, “from 1 to 4”, “from 1 to 5”, “from 2 to 4”, “from 2 to 6”, “from 3 to 6”, etc.; as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.
[0267] Whenever a numerical range is indicated herein (for example “10-15”, “10 to 15”, or any pair of numbers linked by these another such range indication), it is meant to include any number (fractional or integral) within the indicated range limits, including the range limits, unless the context clearly dictates otherwise. The phrases “range/ranging/ranges between” a first indicate number and a second indicate number and “range/ranging/ranges from” a first indicate number “to”, “up to”, “until” or “through” (or another such range-indicating term) a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numbers therebetween.
[0268] Although descriptions of the present disclosure are provided in conjunction with specific embodiments, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.
[0269] All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present disclosure. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is/are hereby incorporated herein by reference in its/their entirety.
[0270] It is appreciated that certain features which are, for clarity, described in the present disclosure in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the present disclosure. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.