DETECTION OF CATHETER LOCATION, ORIENTATION, AND MOVEMENT DIRECTION

Methods, apparatus, and systems for medical procedures are disclosed herein and include a catheter having a first electrode and a second electrode, the first electrode configured to transmit first electromagnetic signals and the second electrode configured to transmit second electromagnetic signals. A first patch, a second patch, and a third patch each configured to receive the first and second electromagnetic signals are included and arranged in a triangular formation on a first surface of a patient's body. A first catheter position relative to the first patch, the second patch, and the third patch, is determined at a first time and a second time. The first catheter position and the second catheter position relative to the first catheter position may be displayed such that the first catheter position is visually connected to the second catheter position.

FIELD OF INVENTION

The present disclosure relates to systems, apparatuses, and methods for improving medical procedures and mapping.

BACKGROUND

Medical conditions such as cardiac arrhythmia (e.g., atrial fibrillation (AF)) are often diagnosed and treated via intra-body procedures. For example, electrical pulmonary vein isolation (PVI) from the left atrial (LA) body is performed using ablation for treating AF. PVI, and many other minimally invasive catheterizations, cause damage to targeted organ tissue to prevent electrical activity through the organ tissue. Such procedures often require catheters and/or other inserted components to traverse a portion of a patient's body to reach an intended location.

Intra-body navigation of catheters and/or other inserted components can be visually assisted by techniques such as fluoroscopy or location pads that emit signals for location tracking via magnetic probes. Such techniques are often problematic due to potential radiation exposure, the number or complexity of components involved, or time consuming calibrations.

SUMMARY

Methods, apparatus, and systems for medical procedures are disclosed herein and include a catheter including a first electrode and a second electrode, the first electrode configured to transmit first electromagnetic signals and the second electrode configured to transmit second electromagnetic signals. A first patch, a second patch, and a third patch each configured to receive the first and second electromagnetic signals are included and arranged in a triangular formation on a first surface of a patient's body.

A processor is configured to determine, at a first time, a first catheter position relative to the first patch, the second patch, and the third patch, based on the first electromagnetic signals and the second electromagnetic signals received at the first patch, the second patch, and the third patch.

The processor may determine, at a second time, a second catheter position relative to the first patch, the second patch, the third patch, based on the signal strength of the first electromagnetic signals and the second electromagnetic signals received at the first patch, the second patch, and the third patch.

The processor may provide the first catheter position and the second catheter position relative to the first catheter position, to a display such that the first catheter position is visually connected to the second catheter position, wherein the first catheter position and the second catheter position each comprise a location and an orientation.

DETAILED DESCRIPTION

According to implementations of the disclosed subject matter, a catheter position relative to a plurality of sensing components (e.g., body surface patches, external electrodes, transceivers, etc.), commonly referred to as “patches” herein, may be determined. The catheter position may include both a location and an orientation of the catheter relative to the patches and guide a medical professional as the catheter is traversing a patient's body. For example, the location and orientation information conveyed by the catheter position may enable a medical professional to determine if the catheter is oriented in the right direction, if the catheter is traversing towards a target, if the catheter has encountered a blockage, or the like.

The catheter position may be provided relative to a plurality of patches such that the catheter position is not an absolute position in accordance with pre-determined coordinates but rather a relative position, relative to the patches. By determining the relative position, the initial insertion point of the catheter need not be necessary, allowing for a calibration free set-up. Further, detecting a relative position instead of an absolute position enables components on the catheter (e.g., electrodes) to transmit electromagnetic signals that are received by the patches, instead of calibrated patches and/or location pad(s) transmitting electromagnetic signals to be received by the catheter. This may reduce the electromagnetic activity within a patient's body and may also provide a single source of transmission. Additionally, obtaining the relative position of a catheter may prevent the need for time and resource intensive calibration of coordinates, such as with the use of a location pad placed near a patient's body.

The patches, as disclosed herein, may be applied to one or more surfaces of a patient's body (e.g., a front surface and/or a back surface). A plurality of patches may be used to determine a two dimensional and/or three-dimensional catheter location. A catheter may include a plurality of components (e.g., electrodes) that transmit electromagnetic signals that are received by the patches. For example, a first catheter electrode may transmit first electromagnetic signals and a second catheter electrode may transmit second electrode configured to transmit second electromagnetic signals. A given patch may receive both the first electromagnetic signals and the second electromagnetic signals. A processor, such as processor41ofFIG. 1, as further disclosed herein, may be configured to compare the first and second electromagnetic signals to determine the orientation of the catheter. For example, if the first electrode is at the top of the catheter, the second electrode is at the bottom of the catheter, and a given patch receives first electromagnetic signals from the first electrode with an amplitude of 0.5 mV and second electromagnetic signals from the second electrode with an amplitude of 0.7 mV, then the processor may determine that the bottom of the catheter is closer to the given patch that then top of the catheter.

According to implementations of the disclosed subject matter, a set of at least three patches may be arranged in a triangular configuration on a first surface (e.g., top surface) of a patient's body. These patches may be configured to receive electromagnetic signals transmitted by the components (e.g., electrodes) of a catheter that is inserted into the patient's body. Based on the properties of the electromagnetic signals received by the set of at least three patches, a position (i.e., location and orientation) of the catheter relative to the at least three patches may be determined. Notably, as the set of at least three patches is approximately on a single surface (i.e., plane) of the patient's body, the position at this stage would be a two-dimensional position. Here, being approximately on a single/same surface or plane means that the set of patches have a significant majority weight (e.g., 90%) of their coordinates within the same dimensions (e.g., a Z dimensions relative to the patient's body). For example, slight fluctuation of the patch coordinates based on muscle, bone, tissue heights, depths, or curves still result in a set of patches being approximately on the single/same surface or plane.

A set of at least three patches may receive electromagnetic signals from a plurality of electrodes on a catheter. A processor may determine a relative catheter position based on the electromagnetic signals received at the set of at least three patches. Notably, the set of at least three patches may be arranged in a triangular configuration such that they define a two-dimensional plane. The processor may determine the relative catheter position within this two-dimensional plane.

According to an implementation, one or more additional fourth patches may be arranged on the same first surface as the set of at least three patches. A first patch and the first patch may create a virtual directional line. The electromagnetic signals received at a first patch and the fourth patch may be combined (e.g., averaged, normalized, etc.) such that the combined reading is applied to determine portion of the catheter's position in the direction perpendicular to the virtual directional line. Combining the electromagnetic signals at two or more patches, in this manner, may reduce error when determining the catheter position.

According to another implementation, one or more additional fourth patches may be arranged on the opposite surface (e.g., second surface) as the first body surface. The second surface may be parallel to the first surface (e.g., a back facing second surface and a chest facing first surface). Such one or more additional fourth patches may provide an additional dimension such that the catheter position may be a three-dimensional relative position.

FIG. 1is a diagram of an exemplary system20in which one or more exemplary features of the present invention can be implemented. System20may include components, such as a catheter40, that are configured to traverse portions of a patient body and reach a target location (e.g., a heart or a cardiac chamber). The components, such as catheter40, may be further configured to map internal portions of a patient's body or may be used to perform a treatment such as by damaging tissue areas of an intra-body organ. The catheter40may also be further configured to obtain biometric data. Although catheter40is shown to be a single point catheter with multiple electrodes47A-N, it will be understood that a catheter of any shape that includes one or more elements (e.g., electrodes) may be used to implement the embodiments disclosed herein. System20includes a probe21, having shafts that may be navigated by a physician30into a body part, such as heart26, of a patient28lying on a bed29. According to implementations, multiple probes may be provided. However, for purposes of conciseness, a single probe21is described herein but it will be understood that probe21may represent multiple probes. As shown inFIG. 1, physician30may insert shaft22through a sheath23, while manipulating the distal end of the shaft22using a manipulator32near the proximal end of the catheter40and/or deflection from the sheath23. As shown in an inset25, catheter40may be fitted at the distal end of shaft22. Catheter40may be inserted through sheath23in a collapsed state and may be then expanded within heart26. Catheter40, as set forth above, may include at least one electrode or a plurality of electrodes47A-N, as further disclosed herein.

According to exemplary embodiments, catheter40may be configured to map and/or ablate tissue areas of a cardiac chamber of heart26. Inset45shows catheter40in an enlarged view, inside a cardiac chamber of heart26. As shown, catheter40may include at least one electrode (or a plurality of electrodes47A-N) coupled onto the body of the catheter40. According to other exemplary embodiments, multiple elements may be connected via splines that form the shape of the catheter40. One or more other elements (not shown) may be provided and may be any elements configured to ablate or to obtain biometric data and may be electrodes, transducers, or one or more other elements.

According to implementations disclosed herein, the electrodes, such as electrodes47A-N, may be configured to transmit electromagnetic signals such a single catheter may have multiple electrodes47A-N that each transmit a unique electromagnetic signal. The electromagnetic signals from a first electrode may be distinguishable from the electromagnetic signal from a second electrode based on any distinguishable attribute such as, but not limited to, frequency, phase, waveform, wavelength, etc.

The catheter40may also be configured to sense biometric data. For example, one or more electrodes47A-N may be configured to sense biometric data while the catheter is inserted into a patient's body. Biometric data may include one or more of LATs, electrical activity, topology, bipolar mapping, dominant frequency, impedance, or the like. The local activation time may be a point in time of a threshold activity corresponding to a local activation, calculated based on a normalized initial starting point. Electrical activity may be any applicable electrical signals that may be measured based on one or more thresholds and may be sensed and/or augmented based on signal to noise ratios and/or other filters. A topology may correspond to the physical structure of a body part or a portion of a body part and may correspond to changes in the physical structure relative to different parts of the body part or relative to different body parts. A dominant frequency may be a frequency or a range of frequency that is prevalent at a portion of a body part and may be different in different portions of the same body part. For example, the dominant frequency of a pulmonary vein of a heart may be different than the dominant frequency of the right atrium of the same heart. Impedance may be the resistance measurement at a given area of a body part.

As shown inFIG. 1, the probe21, and catheter40may be connected to a console24. Console24may include a processor41, such as a general-purpose computer, with suitable front end and interface circuits38for transmitting and receiving signals to and from catheter, as well as for controlling the other components of system20. In some exemplary embodiments, processor41may be further configured to receive biometric data, such as electrical activity, and determine if a given tissue area conducts electricity. According to an exemplary embodiment, the processor may be external to the console24and may be located, for example, in the catheter, in an external device, in a mobile device, in a cloud-based device, or may be a standalone processor.

As noted above, processor41may include a general-purpose computer, which may be programmed in software to carry out the functions described herein. The software may be downloaded to the general-purpose computer in electronic form, over a network, for example, or it may, alternatively or additionally, be provided and/or stored on non-transitory tangible media, such as magnetic, optical, or electronic memory. The example configuration shown inFIG. 1may be modified to implement the exemplary embodiments disclosed herein. The disclosed exemplary embodiments may similarly be applied using other system components and settings. Additionally, system20may include additional components, such as elements for sensing electrical activity, wired or wireless connectors, processing and display devices, or the like.

According to an embodiment, a display connected to a processor (e.g., processor41) may be located at a remote location such as a separate hospital or in separate healthcare provider networks. Additionally, the system20may be part of a surgical system that is configured to obtain anatomical and electrical measurements of a patient's organ, such as a heart, and performing a cardiac ablation procedure. An example of such a surgical system is the Carte system sold by Biosense Webster.

The system20may also, and optionally, obtain biometric data such as anatomical measurements of the patient's heart using ultrasound, computed tomography (CT), magnetic resonance imaging (MRI) or other medical imaging techniques known in the art. The system20may obtain electrical measurements using catheters, electrocardiograms (EKGs) or other sensors that measure electrical properties of the heart. The biometric data including anatomical and electrical measurements may then be stored in a memory42of the mapping system20, as shown inFIG. 1. The biometric data may be transmitted to the processor41from the memory42. Alternatively, or in addition, the biometric data may be transmitted to a server60, which may be local or remote, using a network62.

In some instances, the server62may be implemented as a physical server. In other instances, server62may be implemented as a virtual server a public cloud computing provider (e.g., Amazon Web Services (AWS)®).

Control console24may be connected, by a cable39, to body surface electrodes43, which may include adhesive skin patches that are affixed to the patient28. The processor, in conjunction with a current tracking module, may determine position coordinates of the catheter40inside the body part (e.g., heart26) of a patient. The position coordinates may be based on impedances or electromagnetic fields measured between the body surface electrodes43and the electrode48or other electromagnetic components of the catheter40. Additionally or alternatively, location pads may be located on the surface of bed29and may be separate from the bed29.

Processor41may comprise real-time noise reduction circuitry typically configured as a field programmable gate array (FPGA), followed by an analog-to-digital (A/D) ECG (electrocardiograph) or EMG (electromyogram) signal conversion integrated circuit. The processor41may pass the signal from an A/D ECG or EMG circuit to another processor and/or can be programmed to perform one or more functions disclosed herein.

Control console24may also include an input/output (I/O) communications interface that enables the control console to transfer signals from, and/or transfer signals to electrodes47A-N.

During a procedure, processor41may facilitate the presentation of a body part rendering35to physician30on a display27, and store data representing the body part rendering35in a memory42. Alternatively or in addition, the processor41may facilitate the presentation of all or a portion of a patient's body, such as from a catheter insertion point to above a heart.

Memory42may comprise any suitable volatile and/or non-volatile memory, such as random-access memory or a hard disk drive. In some implementations, medical professional30may be able to manipulate a body part rendering35using one or more input devices such as a touch pad, a mouse, a keyboard, a gesture recognition apparatus, or the like. For example, an input device may be used to change the position of catheter40such that rendering35is updated. In alternative exemplary embodiments, display27may include a touchscreen that can be configured to accept inputs from medical professional30, in addition to presenting a body part rendering35.

FIG. 2shows an example catheter32which may be the same as or similar to catheter40ofFIG. 1. During a medical procedure, a catheter, such as catheter32may initially be inserted into a patient through a natural orifice or via an incision in the patient's body. The catheter32may be guided through the patient's body until it reaches a desired location (e.g., a heart chamber). As shown, catheter32may include a number of electrodes50A through50C. It will be understood that the electrodes50A through50C may be arranged in any applicable manner and that the arrangement shown inFIG. 2is an example only.

FIG. 3shows a process300for determining a catheter position, according to implementations of the disclosed subject matter. As shown inFIG. 3, at step310of process300, a determination that a catheter (e.g., catheter40ofFIG. 1or catheter32ofFIG. 2) has entered the bloodstream of a patient may be made. At step320, a plurality of electrodes on the catheter may transmit first electromagnetic signals at a first time. At step330, the first electromagnetic signals transmitted at the first time may be received by a plurality of patches located on the patient's body. At step340, a first catheter position, including a location and an orientation, may be determined based on the first electromagnetic signals received by the plurality of patches on the patient's body. At step350, the plurality of electrodes on the catheter may transmit electromagnetic signals at a second time, subsequent to the first time. At step360, the electromagnetic signals transmitted at the second time may be received by the plurality of patches located on the patient's body. At step370, a second catheter position, including a location and an orientation, may be determined based on the second electromagnetic signals received by the plurality of patches on the patient's body at the second time. At step380, a visual indication may be provided that includes the relative path between the first catheter position and the second catheter position.

As shown in the process300ofFIG. 3, at step310, a determination that a catheter (e.g., catheter40ofFIG. 1or catheter32ofFIG. 2) has entered the bloodstream of a patient, may be made. The determination that a catheter has entered a patient's bloodstream may be made, for example, based on impedance values detected by a component (e.g., electrode) of the catheter. Notably, the patches may sense electromagnetic signals transmitted by catheter electrodes and an electrode impedance is also determined. If a given electrode is not in a bloodstream, then the current sensed by the one or more patches is low and the detected impedance is high. Accordingly, the catheter is determined not to be in the bloodstream. For example, a catheter component may be calibrated such that an impedance threshold value of X Ohms may correspond to a 99% likelihood that the component is not contact with blood. Accordingly, a determination that a catheter not has entered a patient's bloodstream may made based on if a sensed impedance reading by the catheter component is higher than or equal to X Ohms. Further, the electromagnetic signal amplitude received at the one or more patches may also be factored when determining if a catheter has entered a bloodstream.

Notably, the catheter may enter the patient's bloodstream via any applicable manner such as via a natural orifice or via an incision (e.g., laparoscopic incision) surgically created to insert the catheter. Prior to the catheter entering the patient's bloodstream, one or more of the catheter components may detect a prior impedance that does not meet the threshold impedance value. This prior impedance may be detected while the catheter is in a protective casing, while the catheter is exposed to air, or the like.

According to an implementation, the techniques disclosed herein, including steps320-370of the process300described inFIG. 3, may be implemented upon the determination that a catheter is in a patient's bloodstream. For example, determining that a catheter is in a patient's bloodstream may trigger step320of the process300described inFIG. 3, as further disclosed herein. According to this implementation, a determination that a catheter is in a patient's bloodstream may correspond to a “first time”, as disclosed herein in relation to step320.

At step320of the process300described inFIG. 3, electromagnetic signals may be transmitted form a plurality of electrodes of a catheter, at a first time. According to implementations disclosed herein, each of a plurality of electrodes of a catheter may transmit the electromagnetic signals at the first time. For example, a first electrode of a catheter may transmit first electromagnetic signals at the first time and a second electrode of the catheter may transmit second electromagnetic signals at the first times. Electromagnetic signals (e.g., first and second electromagnetic signals) may include properties that may distinguish the electromagnetic signals transmitted by a first electrode from the electromagnetic signals transmitted by a second electrode. The properties may be one or more of a frequency, phase, waveform, wavelength, or the like.

FIG. 4Ashows a diagram of the front surface of a patient's body andFIG. 4Bshows a diagram of a back surface of the patient's body. The front surface of the patient's body includes patches404,405,406,407and408and the back surface of the patient's body includes patches401,402,403, and409. The patches401-409may be attached to the patient's body in any applicable manner including via an adhesive, via a mechanical connection, via an insertion into the surface of the patient's skin, via a frictional component, or a combination thereof. It will be understood that the number and configuration of patches may vary and that the number and configuration shown inFIGS. 4A, 4Band throughout this disclosure are for example purposes only.

As shown inFIGS. 4A and 4B, a catheter420may be inserted into the patient's body. The catheter420may include at least two electrodes421and422that are each configured to transmit electromagnetic signals that may be received by one or more of the patches401-409. Accordingly, at step320of the process300described inFIG. 3, the electrode421of catheter420may transmit first electromagnetic signals and electrode422of catheter420may transmit second electromagnetic signals.

At step330of the process300described inFIG. 3, a plurality of patches may receive the electromagnetic signals transmitted, at a first time, by a plurality of electrodes of a catheter. Notably, based on the distance of a given electrode from a given patch, one or more attributes of an electromagnetic signal emitted by a given electrode and received by a given patch may differ from a different electromagnetic signal emitted by another electrode and received by the given patch. For example, a first electrode may be closer to a first patch than a second electrode. Accordingly, electromagnetic signals transmitted by the first electrode, as received at the first patch, may have a higher power amplitude than the electromagnetic signals transmitted by the second electrode, as received by the first patch, based on the amplitude attenuation that may occur over the larger distance that the electromagnetic signals transmitted by the second electrode traverse. Alternatively, electromagnetic signals transmitted by the first electrode, as received at the first patch, may be received by the first patch sooner than the electromagnetic signals transmitted by the second electrode, as received by the first patch, based on the time it takes to traverse the larger distance that the electromagnetic signals transmitted by the second electrode traverse.

In the example provided inFIGS. 4A and 4B, the electrode421is closer to patch404than electrode422. Accordingly, the patch404would receive electromagnetic signals transmitted by electrode421at a first time such that the received signals have a higher amplitude than the electromagnetic signals received by the patch404as transmitted, at the first time, by electrode422.

According to an implementation of the disclosed subject matter, signals provided for two or more patches may be combined prior to being analyzed by a processor to determine a catheter position. For example, as shown inFIGS. 4A and 4B, signals from patches that are not darkened (i.e.,402,405,406,407,408, and409) may be combined when being analyzed by a processor. The signals to be combined may be from patches such that two or more patches may create a virtual line in a given direction, and a component of the catheter location, perpendicular to the virtual line, may be determined based on the combined signals provided by the two or more patches.FIG. 6A, as further disclosed herein, shows an implementation combining signals from patches407and405as well as patches408and406.

According to an example, the signals from patches405and407may be combined and the signals from patches406and408may be combined when determining the position of a catheter in a left to right direction relative to the patient's body. Specifically, signals from patches405and407may be combined (e.g., sum or normalized sum) and may represent the left side of the patient's body, as further disclosed at step340of process300, and signals from patches406and408may be combined (e.g., sum or normalized sum) and may represent the right side of the patient's body. Notably, the pair of patches406and408may be positioned such that they have approximately at the same directional coordinate in the direction that is perpendicular to the direction being measured using the combined signal from the patches406and408. Similarly, the pair of patches405and407may be positioned such that they have approximately at the same directional coordinate in the direction that is perpendicular to the direction being measured using the combined signal from the patches406and408. To clarify, patches406and408may have the same coordinate in a left to right direction of the patient's body and patches405and407may have the same coordinate in the left to right direction of the patient's body, and the signals from the pairs of patches may be used to determine the position of a catheter in the left to right direction. Notably, in this example, when determining the position of the catheter in the left to right direction, the difference in signal between, for example, patch405and patch407may be less relevant because they each have approximately at the same

At step340of the process300described inFIG. 3, a first catheter position of the catheter inserted into a patient's body may be determined. The first catheter position may include a location and an orientation of the catheter. The first catheter position may be determined based on the electromagnetic signals transmitted by a plurality of electrodes of the catheter, at a first time, and based on those electromagnetic signals being received by a plurality of patches.

As disclosed herein, a catheter position, such as the first catheter position determined at step340of process300, may include a location and an orientation. The location of a catheter may be determined based on the electromagnetic signals transmitted by any one of a plurality of electrodes of the catheter, by a plurality of electromagnetic signals transmitted by the plurality of electrodes, or by a combination thereof. For example, the location of a catheter may be determined based on the amplitude of electromagnetic signals transmitted by a single electrode and received at a plurality of patches, when a single. Alternatively, multiple electrodes may transmit electromagnetic signals and a determination may be made that the signals transmitted by a single electrode are of the greatest quality (e.g., least signal to noise ratio, highest QRS factor, or the like). Accordingly, the electromagnetic signals from that electrode may be used to determine location of a catheter. Alternatively, multiple electrodes may transmit electromagnetic signals and a plurality of patches may receive each of the signals. A mathematical calculation, such as an average, may be applied to determine a representative electromagnetic signal that factors in each of the plurality of electromagnetic signals and that representative electromagnetic signal may be used to determine the location of the catheter. A processor, such as processor41may be used for at least one of determining the time duration between a first time of transmission of an electromagnetic signal and may also be used to apply a mathematical calculation, as disclosed above. Techniques used to determine the location of a catheter are further disclosed herein in further detail.

FIG. 4Cshows a technique that may be used to determine the location of a catheter based on electromagnetic signals transmitted by at least one electrode and received by a plurality of patches. Additional techniques for determining the location of a catheter are further disclosed herein.

As shown inFIG. 4C, a plurality of patches432,433, and434may receive electromagnetic signals transmitted by at least one electrode of catheter440. Based on a property of the electromagnetic signals, such as the amplitude of the electromagnetic signals or duration of time between the transmission of the electromagnetic signals by at least one electrode and receipt of the electromagnetic signals by each of a plurality of patches, potential locations of the catheter, as determined by each of the plurality of patches may be determined. For example, as shown inFIG. 4C, at least one electrode of the catheter440may transmit electromagnetic signals at a first time. The electromagnetic signals may be received by each of the patches432,433, and434.

According to an implementation, as shown inFIG. 4C, the amplitude of the respective received electromagnetic signals at each of the patches432,433, and434may be determined by, for example, a processor such as processor41ofFIG. 1. Based on the amplitude of the respective received electromagnetic signals at each of the patches432,433, and434, a potential distance of the catheter440from each of the patches432,433, and434may be determined. The potential distance may be a radius that corresponds to the given amplitude such that a higher amplitude detected at a given patch may correspond to a smaller radius such that the catheter may be closer to the given patch than a lower amplitude detected at the given patch which may indicate that the catheter is further from the given patch. As shown in the example provided inFIG. 4C, the potential distance of catheter440corresponding to patch432is represented by circle432A, corresponding to patch433is represented by circle433A, and corresponding to patch434is represented by circle434A. Accordingly, the location of the catheter may be determined to be at the intersection of the potential distances432A,433A, and434A, as shown inFIG. 4C. The intersection of the potential distances may be determined by a processor, such as processor41ofFIG. 1.

According to another implementation, as shown inFIG. 4D, the time duration between transmission by an electrode and receipt of the respective received electromagnetic signals at each of the patches452,453, and454may be determined by, for example, a processor such as processor41ofFIG. 1. Based on the time duration of receipt, from transmission, of the respective received electromagnetic signals at each of the patches452,453, and454, a potential distance of the catheter460from each of the patches452,453, and454may be determined. The potential distance may be a radius that corresponds to the given time duration such that a shorter time duration between transmission by an electrode and receipt by a given patch may correspond to a smaller radius such that the catheter may be closer to the given patch than a higher time duration between transmission by the electrode and receipt by the given patch which may indicate that the catheter is further from the given patch. As shown in the example provided inFIG. 4D, the potential distance of catheter460corresponding to patch452is represented by circle452A, corresponding to patch453is represented by circle453A, and corresponding to patch454is represented by circle454A. Accordingly, the location of the catheter may be determined to be at the intersection of the potential distances452A,453A, and454A, as shown inFIG. 4C. The intersection of the potential distances may be determined by a processor, such as processor41ofFIG. 1.

The orientation of a catheter may be determined by comparing the electromagnetic signals transmitted by each of a plurality of electrodes of a catheter, as disclosed herein. The first electromagnetic signals of a first electrode transmitted at a first time may be compared to the second electromagnetic signals of a second electrode transmitted at the first time. A difference in amplitude or time, as disclosed herein, may be used to determine the orientation of the catheter.

The location of the electrode471and electrode472on the catheter470may be a known location or may be determined based on the example implementations described inFIGS. 4E and 4F(e.g., may be ascertained when determining the orientation of a given catheter).

According to an implementation, as shown inFIG. 4E, the catheter470may include two electrodes471and472. Electrode471may transmit first electromagnetic signals and electrode472may transmit second electromagnetic signals. The amplitude of the respective received first and second electromagnetic signals at each of the patches462,463, and464may be determined by, for example, a processor such as processor41ofFIG. 1. Based on the amplitude of the respective received electromagnetic signals at each of the patches462,463, and464, a potential distance of the electrode471and472from each of the patches462,463, and464may be determined. The potential distance may be a radius that corresponds to the given amplitude such that a higher amplitude detected at a given patch may correspond to a smaller radius such that the catheter may be closer to the given patch than a lower amplitude detected at the given patch which may indicate that the catheter is further from the given patch. As shown in the example provided inFIG. 4E, the potential distance of electrode471corresponding to patch462is represented by circle462A and of electrode472corresponding to patch462is represented by dotted circle462B. The potential distance of electrode471corresponding to patch463is represented by circle463A and of electrode472corresponding to patch463is represented by dotted circle463B. The potential distance of electrode471corresponding to patch464is represented by circle464A and of electrode472corresponding to patch464is represented by dotted circle464B.

Accordingly, the location of the electrode471may be determined to be at the intersection of the potential distances462A,463A, and464A, as shown inFIG. 4Eand the location of the electrode472may be determined to be at the intersection of the potential distances462B,463B, and464B. The intersection of the potential distances may be determined by a processor, such as processor41ofFIG. 1. By determining the location of individual electrodes471and472of catheter470, the orientation of the catheter may be determined by the processor.

Similarly,FIG. 4Fshows the catheter470ofFIG. 4Eincluding two electrodes471and472. The catheter470ofFIG. 4Fmay be oriented different from the orientation of the catheter470inFIG. 4E. Electrode471may transmit first electromagnetic signals and electrode472may transmit second electromagnetic signals. The amplitude of the respective received first and second electromagnetic signals at each of the patches462,463, and464may be determined by, for example, a processor such as processor41ofFIG. 1. Based on the amplitude of the respective received electromagnetic signals at each of the patches462,463, and464, a potential distance of the electrode471and472from each of the patches462,463, and464may be determined, as described in relation toFIG. 4E. As shown in the example provided inFIG. 4F, the potential distance of electrode471corresponding to patch462is represented by circle462C and of electrode472corresponding to patch462is represented by dotted circle462D. The potential distance of electrode471corresponding to patch463is represented by circle463C and of electrode472corresponding to patch463is represented by dotted circle463D. The potential distance of electrode471corresponding to patch464is represented by circle464C and of electrode472corresponding to patch464is represented by dotted circle464D.

Accordingly, the location of the electrode471may be determined to be at the intersection of the potential distances462C,463C, and464C, as shown inFIG. 4Fand the location of the electrode472may be determined to be at the intersection of the potential distances462D,463D, and464D. The intersection of the potential distances may be determined by a processor, such as processor41ofFIG. 1. By determining the location of individual electrodes471and472of catheter470, the orientation of the catheter may be determined by the processor.

Although the examples provided inFIGS. 4C-4Fshow the position of a catheter being determined in two dimensions, the same process may be applied in three dimensions using, for example, the radius of a sphere instead of the radius of a circle, and determining intersection points of the sphere to determine the location and orientation of a catheter.

According to another implementation, as shown inFIGS. 5A through 5C, the location of a catheter and/or at least one electrode may be determined relative to the patches applied to a patient's body.FIGS. 5A and 5Breference the patches shown inFIGS. 4A and 4B. As shown inFIG. 5A, a first dimension may be defined relative to the plurality of patches. The first dimension may be defined by a line between the normalized sum of the current received at patches401,403, and404(“top patches”) which are located towards the face of the patient, as shown inFIGS. 4A and 4Band the normalized sum of patches402,405,406,407,408, and409(“bottom patches”) which are located towards the feet of the patient, as shown inFIGS. 4A and 4B. Notably, the first dimensions is relative to the position of the patches, and is not a pre-determined dimension. A plurality of electrodes on a catheter510may emit electromagnetic signals that are received by the top patches and the bottom patches such that when the catheter510is located proximate to the bottom patches, as shown inFIG. 5A, the normalized sum of the bottom patches is greater than the normalized sum of the top patches. Based on the difference between the normalized sums, a processor (e.g., processor41ofFIG. 1) may determine the position of the catheter510in the first dimension, based on the difference in the normalized sums.

According to an implementation, as shown in chart501ofFIG. 5B, the normalized sum of only a single set of patches (e.g., the top patches) may be received and a determination of the position of the catheter510may be determined based on the normalized sum of the single set of patches. As shown in the graph501ofFIG. 5B, the normalized sum of current received at the top patches may be low when the catheter510is proximate to the bottom patches (e.g., as shown inFIG. 5A). As the normalized sum of the current received at the top patches increases, a processor may determine that the catheter510is more proximate to the top patches.FIGS. 5A and 5Bindicate proximity to the bottom patches using the marker A and proximity to the top patches using the marker B.

FIG. 5Cshows an chart502including an experimental reading520of the normalized sum of the current received at a number of patches (e.g., top patches). As shown, for the first ˜1500 samples collected, the normalized sum of the current is approximately constant at 0.35. The first ˜1500 may indicate that a catheter (e.g., catheter510) may be stationary at a position that is approximately 35% of the distance between a first set of patches and a second set of patches in a given dimension. Between 1500 and 1700 samples, the normalized sum of the current shifts from approximately 0.35 to approximately 0.65. This change of current may indicate that a catheter (e.g., catheter510) may move from a position that is approximately 35% of the distance between the first set of patches and the second set of patches in the given dimension to a position that is approximately 65% of the distance between the first set of patches and the second set of patches in the given dimension. The percentage of distance may be calculated from a set point, such as from the bottom set of patches, the top set of patches, or a location (e.g., center) relative to either set of patches.

FIGS. 6A and 6Breference the patches shown inFIGS. 4A and 4B. As shown inFIG. 6A, a second dimension may be defined relative to the plurality of patches. The second dimension may be defined by a line between the sum or normalized sum of the current received at patches407, and405(“left patches”) which are located towards the left side of the patient's body, as shown inFIGS. 4A and 4Band the sum or normalized sum of patches408and406(“right patches”) which are located towards the right side of the patient's body, as shown inFIGS. 4A and 4B. Notably, the second dimensions is relative to the position of the patches, and is not a pre-determined dimension. A plurality of electrodes on a catheter510may emit electromagnetic signals that are received by the left patches and the right patches such that when the catheter610is located between the right patches and the left patches, as shown inFIG. 6A, the sum or normalized sum of the current at the left patches is about the same as the sum or normalized sum of the right patches. Based on the difference between the normalized sums, a processor (e.g., processor41ofFIG. 1) may determine the position of the catheter610in the second dimension, based on the difference between the sums or the normalized sums.

According to an implementation, as shown in the graph601ofFIG. 6B, the sum or normalized sum of only a single set of patches (e.g., the left patches) may be received and a determination of the position of the catheter610may be determined based on the sum or normalized sum of the single set of patches. As shown in the graph601ofFIG. 6B, the sum or normalized sum of current received at the right patches may be low when the catheter610is proximate to the left patches. As the sum or normalized sum of the current received at the right patches increases, a processor may determine that the catheter610is more proximate to the right patches.FIGS. 6A and 6Bindicate proximity to the left patches using the marker A and proximity to the right patches using the marker B.

FIG. 6Cshows a graph602including an experimental reading620of the sum or normalized sum of the current received at a number of patches (e.g., left patches). As shown, for the first ˜1200 samples collected, the sum or normalized sum of the current is approximately constant at 0.52. The first ˜1200 may indicate that a catheter (e.g., catheter610) may be stationary at a position that is approximately between distance between a first set of patches and a second set of patches in a given dimension. Between 1200 and 1700 samples, the normalized sum of the current shifts from approximately 0.52 to approximately 0.45. This change of current may indicate that a catheter (e.g., catheter610) moved from a position that is between the first set of patches and the second set of patches in the given dimension to a position that is approximately 45% of the distance between the first set of patches and the second set of patches in the given dimension. The percentage of distance may be calculated from a set point, such as from the bottom set of patches, the top set of patches, or a location (e.g., center) relative to either set of patches.

FIGS. 7A and 7Breference the patches shown inFIGS. 4A and 4B. As shown inFIG. 7A, a third dimension may be defined relative to the plurality of patches. The third dimension may be defined by a line between the sum or normalized sum of the current received at patches407,408,405, and406(“upper patches”) which are located on the upper surface of the patient's body, as shown inFIGS. 4A and 4Band the sum or normalized sum of patches409,402, and403(“lower patches”) which are located on the bottom surface of the patient's body, as shown inFIGS. 4A and 4B. Notably, the third dimensions is relative to the position of the patches, and is not a pre-determined dimension. A plurality of electrodes on a catheter710may emit electromagnetic signals that are received by the upper patches and the lower patches such that when the catheter710is located between the upper patches and the lower patches, as shown inFIG. 7A, the sum or normalized sum of the current at the upper patches is about the same sum or normalized sum of the current at the lower patches. Based on the difference between the normalized sums, a processor (e.g., processor41ofFIG. 1) may determine the position of the catheter710in the third dimension, based on the difference between the sums or the normalized sums.

According to an implementation, as shown in the graph701ofFIG. 7B, the sum or normalized sum of only a single set of patches (e.g., the upper patches) may be received and a determination of the position of the catheter710may be determined based on the sum or normalized sum of the single set of patches. As shown in the graph701ofFIG. 7B, the sum or normalized sum of current received at the upper patches may be low when the catheter710is proximate to the upper patches. As the sum or normalized sum of the current received at the lower patches increases, a processor may determine that the catheter710is more proximate to the lower patches.FIGS. 7A and 7Bindicate proximity to the lower patches using the marker A and proximity to the upper patches using the marker B.

According to implementations of the disclosed subject matter, a catheter location may be determined based on a combination of the first, second, and third dimensions relative to the patches. The first dimension may provide a first three-dimensional coordinate relative to the patches, the second dimension may provide a second three-dimensional coordinate relative to the patches, and the third dimension may provide a third three-dimensional coordinate relative to the patches. Similarly, the coordinates of individual electrodes in the catheter may be provided to determine the orientation of the catheter, as disclosed herein.

FIG. 8shows an experimental result of the distance from an entry point of a catheter as actually measured using a magnetic probe in combination with a location pad as well as estimated based on the techniques disclosed herein. For example,FIG. 8shows the data collected based on an actual measurement and an estimated measurement for a single dimension (e.g., a first dimension ofFIGS. 5A-5C), to test the accuracy of the techniques disclosed herein. It will be understood that the test would provide similar results if expanded to two or three dimensions. The actual measurement is indicated by line810and the estimated measurement is indicated by line820. As shown inFIG. 8, the estimated measurement820obtained based on receiving electromagnetic signals emitted by electrodes of a catheter, at a plurality of patches, mirrors the actual measurements calculated using the magnetic probe in combination with the location pad.

As shown inFIG. 8at822and824, the estimated measurements may include patterns (e.g., cyclical patterns) that may be caused by bodily movement due to, for example, respiration, a heartbeat, or the like. According to an implementation, the pattern may be filtered from the estimated measurement by using an applicable filter such as a high pass filter, a low pass filter, or the like. As also shown inFIG. 8, during times832, the catheter may be relatively stationary, may move further from the entry point during times834, may move closer to the entry point during times836, may be relatively stationary during times838, and may move towards the entry point during times840.

A second catheter position may be determined based on steps350-370of process300ofFIG. 3. Steps350-370are similar to steps320-340of the process300and, accordingly, the details for each step are not reiterated herein for simplicity. At step350of the process300described inFIG. 3, the plurality of electrodes on the catheter may transmit electromagnetic signals at a second time, subsequent to the first time. At step360, the electromagnetic signals transmitted at the second time may be received by the plurality of patches located on the patient's body. At step370, a second catheter position, including a location and an orientation, may be determined based on the electromagnetic signals received by the plurality of patches on the patient's body at the second time.

At step380, a visual indication may be provided that includes the relative path between the first catheter position and the second catheter position.FIG. 9shows an example visual indication910that indicates the path taken by catheter between a number of positions including a first position912, a second position914, and a third position916. The visual indication may be provided on a display, such as display27ofFIG. 1.

According to an implementation of the disclosed subject matter, a direction of movement of a catheter may be determined based on a first position and a second position of the catheter. The direction of movement may be determined based on the change in the first catheter position and the second catheter position. As an example, the direction of movement may be an arrow that may dynamically change as the direction of movement updates based on electromagnetic signals are transmitted by electrodes of a catheter.FIG. 9shows an example direction of movement920, in a direction box922, based on recent positions of the catheter having the visual indication910.