Patent Description:
The invention is as defined by independent claims <NUM> and <NUM>. Dependent claims disclose exemplary embodiments. A catheter and method for catheter assembly are disclosed. A flexible substrate includes a number of layers, where each layer has a number of printed wires. The wires are printed on the flexible substrate using a conductive material. The printed substrate is environmentally protected. The printed substrate is rolled and inserted into the catheter. Connectors are attached to each end of the substrate. The connectors are in turn connected to sensors at a distal end of the catheter and with electrical cards or a cable connector at a proximate or handle end of the catheter. At least one layer of the substrate is connected to a coil in a magnetic sensor, for example. According to the invention, a reference layer is used to determine or measure magnetic radiation for interference purposes by connecting and/or shorting two traces in the reference layer at a distal end of the catheter. These measurements may be used by a processor or hardware to cancel out the magnetic interference effect on the other layers. Another printed substrate can be wrapped around the catheter shaft and used for non-magnetic type sensors.

Cardiac ablation is a medical procedure performed by electrophysiologists that may be used to correct heart rhythm defects, known as arrhythmias, by creating lesions to destroy tissue in the heart that contributes to the rhythm defects. An example arrhythmia that can be treated using cardiac ablation is atrial fibrillation (AF), which is an abnormal heart rhythm that originates in the atria of the heart. Goals of cardiac ablation are to remove the arrhythmia to return the patient's heart to a normal heart rhythm or reduce the frequency of arrhythmia and the severity of symptoms in the patient.

Cardiac ablation may employ long, flexible catheters (endoscope) that may be inserted through a small incision in the groin and through the blood vessels to the heart, and may be used to apply energy (e.g., radio frequency (RF) energy, or extreme cold) to produce small scars or lesions on the tissue to block faulty electrical impulses that may cause the heart rhythm disorders. These lesions, also called transmural lesions, are scar tissue that penetrates the heart tissue and keeps errant electrical signals from being transmitted.

Current methods for manufacturing the catheter shaft are extremely cumbersome. Catheter shafts contain a large (and increasing) number of wires with electrodes. Each wire is pulled through the catheter shaft and then soldered into place. This is labor intensive and time consuming as there can be dozens of wires that need to be soldered on both the proximal and distal ends of the catheter shaft. Moreover, this method is prone to human error in properly terminating both ends of each conductor to its proper respective termination point.

Described herein is a catheter and method for catheter assembly. In general, a flexible substrate or ribbon includes a number of layers, where each layer has a number of printed wires. The wires are printed on the flexible substrate using a conductive material. The printed substrate is environmentally protected by lamination or other similar techniques. The printed substrate is inserted into the catheter. In an implementation, the printed substrate is rolled prior to insertion. In an implementation, the printed substrate is maintained in a straight line format prior to insertion. Connectors are attached to each end of the substrate. The connectors are in turn connected to sensors at a distal end of the catheter and with electrical cards or a cable connector at a proximate or handle end of the catheter. In an implementation, a layer is connected to a coil in a magnetic sensor, for example. According to the invention, a reference layer is used to determine or measure magnetic radiation for interference purposes. The reference layer is shorted to measure magnetic radiation interference. These measurements may be used by a processor or hardware to cancel out the magnetic interference effect on the other layers. Another printed substrate can be wrapped around the catheter shaft and used for non-magnetic type sensors.

<FIG> is an illustration of an example medical system <NUM> that is used to generate and display information during a medical procedure and to control the deployment of various catheters within a subject. Example system <NUM> includes a catheter <NUM>, such as an intracardiac catheter, a console <NUM> and an associated catheter control unit <NUM>. As described herein, it will be understood that catheter <NUM> is used for diagnostic or therapeutic treatment, such as for example, mapping electrical potentials in a heart <NUM> of a patient <NUM> or performing an ablation procedure. Alternatively, catheter <NUM> can be used, mutatis mutandis, for other therapeutic and/or diagnostic purposes in heart <NUM>, lungs, or in other body organs and ear, nose, and throat (ENT) procedures.

An operator <NUM> can, for example, insert catheter <NUM> into the vascular system of patient <NUM> using catheter control unit <NUM> so that a distal end <NUM> of catheter <NUM> enters a chamber of the patient's heart <NUM>. Console <NUM> can use magnetic position sensing to determine position coordinates of distal end <NUM> inside heart <NUM>. To determine the position coordinates, a driver circuit <NUM> in console <NUM> may drive field generators <NUM> to generate magnetic fields within the body of patient <NUM>. Field generators <NUM> can include coils that may be placed below the torso of the patient <NUM> at known positions external to patient <NUM>. These coils may generate magnetic fields in a predefined working volume that contains heart <NUM>.

A location sensor <NUM> within distal end <NUM> of catheter <NUM> can generate electrical signals in response to these magnetic fields. A signal processor <NUM> can process these signals in order to determine the position coordinates of distal end <NUM>, including both location and orientation coordinates. Known methods of position sensing described hereinabove are implemented in the CARTO™ mapping system produced by Biosense Webster Inc. , of Diamond Bar, Calif. , and is described in detail in the patents and the patent applications cited herein.

Location sensor <NUM> is configured to transmit a signal to console <NUM> that is indicative of the location coordinates of distal end <NUM>. Location sensor <NUM> can include one or more miniature coils, and typically can include multiple coils oriented along different axes. Alternatively, location sensor <NUM> can comprise either another type of magnetic sensor, or position transducers of other types, such as impedance-based or ultrasonic location sensors.

Catheter <NUM> can also include a force sensor <NUM> contained within distal end <NUM>. Force sensor <NUM> can measure a force applied by distal end <NUM> to the endocardial tissue of heart <NUM> and generate a signal that is sent to console <NUM>. Force sensor <NUM> can include a magnetic field transmitter and a receiver connected by a spring in distal end <NUM>, and can generate an indication of the force based on measuring a deflection of the spring. Further functional details of the catheter and force sensor are described in <CIT> and <CIT>. Alternatively, distal end <NUM> can include another type of force sensor that can use, for example, fiber optics or impedance measurements.

Catheter <NUM> can include an electrode <NUM> coupled to distal end <NUM> and configured to function as an impedance-based position transducer. Additionally or alternatively, electrode <NUM> can be configured to measure a certain physiological property, for example the local surface electrical potential of the cardiac tissue at one or more of the multiple locations. Electrode <NUM> can be configured to apply radio frequency (RF) energy to ablate endocardial tissue in heart <NUM>.

Although example medical system <NUM> can be configured to measure the position of distal end <NUM> using magnetic-based sensors, other position tracking techniques can be used (e.g., impedance-based sensors). Magnetic position tracking techniques are described, for example, in <CIT>, <CIT>, <CIT>,<CIT>, <CIT>, <CIT>, and <CIT>. Impedance-based position tracking techniques are described, for example, in <CIT>, <CIT> and <CIT>.

Signal processor <NUM> can be included in a general-purpose computer, with a suitable front end and interface circuits for receiving signals from catheter <NUM> and controlling the other components of console <NUM>. Signal processor <NUM> can be programmed, using software, to carry out the functions that are described herein. The software can be downloaded to console <NUM> in electronic form, over a network, for example, or it can be provided on non-transitory tangible media, such as optical, magnetic or electronic memory media. Alternatively, some or all of the functions of signal processor <NUM> can be performed by dedicated or programmable digital hardware components.

In the example of <FIG>, console <NUM> can also be connected by a cable <NUM> to external sensors <NUM>. External sensors <NUM> can include body surface electrodes and/or position sensors that can be attached to the patient's skin using, for example, adhesive patches. The body surface electrodes can detect electrical impulses generated by the polarization and depolarization of cardiac tissue. The position sensors can use advanced catheter location and/or magnetic location sensors to locate catheter <NUM> during use. Although not shown in <FIG>, external sensors <NUM> can be embedded in a vest that is configured to be worn by patient <NUM>. External sensors <NUM> can aid in identifying and tracking the respiration cycle of patient <NUM>. External sensors <NUM> can transmit information to console <NUM> via cable <NUM>.

Additionally, or alternatively, catheter <NUM>, and external sensors <NUM> can communicate with console <NUM> and one another via a wireless interface. For example, <CIT> describes, inter alia, a wireless catheter, which is not physically connected to signal processing and/or computing apparatus. Rather, a transmitter/receiver is attached to the proximal end of the catheter. The transmitter/receiver communicates with a signal processing and/or computer apparatus using wireless communication methods, such as infrared (IR), radio frequency (RF), wireless, Bluetooth®, acoustic or other transmissions.

Catheter <NUM> can be equipped with a wireless digital interface that can communicate with a corresponding input/output (I/O) interface <NUM> in console <NUM>. Wireless digital interface and the I/O interface <NUM> can operate in accordance with any suitable wireless communication standard that is known in the art, such as IR, RF, Bluetooth, one of the IEEE <NUM> families of standards, or the HiperLAN standard. External sensors <NUM> can include one or more wireless sensor nodes integrated on a flexible substrate. The one or more wireless sensor nodes can include a wireless transmit/receive unit (WTRU) enabling local digital signal processing, a radio link, and a power supply such as miniaturized rechargeable battery.

Wireless digital interface and the I/O interface <NUM> can enable console <NUM> to interact with catheter <NUM> and external sensors <NUM>. Based on the electrical impulses received from external sensors <NUM> and signals received from catheter <NUM> via wireless digital interface and the I/O interface <NUM> and other components of medical system <NUM>, signal processor <NUM> can generate information <NUM> which can be shown on a display <NUM>.

During the diagnostic treatment, signal processor <NUM> can present information <NUM>, and/or can store data in a memory <NUM>. Memory <NUM> can include any suitable volatile and/or non-volatile memory, such as random access memory or a hard disk drive.

Catheter control unit <NUM> can be configured to be operated by an operator <NUM> to manipulate catheter <NUM> based on information <NUM>, which is selectable using one or more input devices <NUM>. Alternatively, medical system <NUM> can include a second operator that manipulates console <NUM> while operator <NUM> operates catheter control unit <NUM> to manipulate catheter <NUM> based on information <NUM>. The second operator can also be provided with information <NUM>. The mechanics of the construction and use of catheter control device <NUM> to move and position distal end <NUM> of catheter <NUM> is within the state of the art such as employed in the CARTO™ mapping system referenced above. For example, see also <CIT>.

An example catheter <NUM> is shown in greater detail in <FIG>, showing some, but not all, of the elements that may be included in catheter <NUM>. A catheter <NUM> may include, but is not limited to include, any one or more of the following components: electrode(s) <NUM>; temperature sensor(s) <NUM>; non-contact electrodes <NUM>; image sensor(s) <NUM>; positioning or location sensor(s) <NUM>; distal tip <NUM>; distal end <NUM>; handle <NUM>; and/or cable <NUM>. The schematic diagram of catheter <NUM> in <FIG> is a high-level representation of possible components of catheter <NUM>, such that the location and configuration of the components in catheter <NUM> may be different than shown.

Distal end <NUM> of catheter <NUM> may include an electrode(s) <NUM> at distal tip <NUM> that may be used to measure electrical properties of the cardiac tissue. Electrode(s) <NUM> may also be used to send electrical signals to the heart for diagnostic purposes. Electrode(s) <NUM> may also perform ablation on defective cardiac tissue by applying energy (e.g., RF energy) directly to the cardiac tissue at the desired location of ablation.

Distal end <NUM> of catheter <NUM> may include temperature sensor(s) <NUM> to measure the temperature of the cardiac tissue in contact with distal end <NUM> and/or measure the temperature of distal end <NUM> itself. For example, thermocouples or thermistors for measuring temperature may be placed anywhere along distal end <NUM> to serve as temperature sensor(s) <NUM>.

Distal end <NUM> may include non-contact electrodes <NUM> arranged in an array, which may be used to simultaneously receive and measure far-field electrical signals from the walls of the heart chamber of a patient. Electrode(s) <NUM> and non-contact electrodes <NUM> provide information regarding the electrical properties of the heart to processing device(s) for processing, such as for example, signal processor <NUM>.

Catheter(s) <NUM> may be equipped with one or more image sensor(s) <NUM>, such as a charge coupled device (CCD) image sensor, and/or a camera for capturing endoscopic images when inserted in a body cavity. Image sensor(s) <NUM> may be located at distal end <NUM>.

Distal end <NUM> may include location sensor(s) <NUM> in distal tip <NUM> of catheter <NUM> that may generate signals used to determine the position and orientation (and/or distance) of catheter <NUM> in the body. In an example, the relative position and orientation of location sensor(s) <NUM>, electrode(s) <NUM>, and distal tip <NUM> are fixed and known in order to facilitate accurate positioning information of distal tip <NUM>. For example, the position of location sensor(s) <NUM> may be determined in part based on the relative position to known positions outside the heart (e.g., based on extra-cardiac sensors). The use of location sensor(s) <NUM> may provide improved location accuracy within the magnetic fields in the surrounding space and provide location information that is adaptable to patient movement because the position information of catheter <NUM> is relative to the anatomy of the patient.

Handle <NUM> of catheter <NUM> may be operated by an operator such as a physician and may include controls <NUM> to enable the physician to effectively steer distal tip <NUM> in the desired direction.

Electrodes <NUM>, <NUM>, and sensors <NUM>, <NUM>, <NUM> may be connected to processing device(s), such as for example signal processor <NUM>, via wires that may pass through handle <NUM> and cable <NUM>, in order to provide information, such as location, electrical, imaging and/or temperature information, to a console system, which may be used to operate and display the function of catheter <NUM> within the heart in real-time.

<FIG> is a schematic diagram of an example catheter <NUM> with a printed flexible substrate <NUM> in accordance with certain implementations. Catheter <NUM> includes a catheter shaft <NUM>, a handle <NUM> and a cable <NUM>. Catheter shaft <NUM> includes a distal end <NUM> and a proximate end or handle end <NUM>. Distal end <NUM> includes a number of sensors (not shown) as described herein. Proximate end <NUM> ends at handle <NUM>. Handle <NUM> includes controls <NUM> and a cable <NUM> which connects to processing devices in a console, for example, console <NUM>. Printed flexible substrate <NUM> includes distal end connectors <NUM> and proximate end connectors <NUM>. Printed flexible substrate <NUM> extends from distal end <NUM> to proximate end <NUM>. In particular, distal end connectors <NUM> are connected to sensors and proximate end connectors <NUM> are connected to cable <NUM> via cards or connectors in handle <NUM>.

<FIG> is an example printed flexible substrate <NUM> in accordance with certain implementations. Printed flexible substrate <NUM> can be any type of flexible substrate including a flexible printed circuit board (PCB), a ribbon and other similar structures. Printed flexible substrate <NUM> can include a predetermined number of layers which may depend on the type of sensor in the catheter. The predetermined number of layers can include signal layers and reference layers. For example, the sensor can be a location sensor which includes three coils, one for each of an X, Y and Z axis. In an illustrative example, signal layers can include layers <NUM>, <NUM> and <NUM>, which are associated with coils representing each X, Y and Z axis. As noted herein, a reference layer, e.g., layer <NUM>, is used for magnetic interference cancellation that results from other devices in the catheter or the medical system.

In an implementation, each of layers <NUM>, <NUM>, <NUM>, and <NUM> can include any number of traces. The traces may include signal traces and ground traces. In an implementation, the traces can include ground traces <NUM> and <NUM>, a first signal trace <NUM> and a second signal trace <NUM>. Each of the traces, e.g., ground traces <NUM> and <NUM>, first signal trace <NUM> and second signal trace <NUM>, is made of a conductive material, such as copper, gold, gold cladded copper or other similar materials. The conductive material is deposited, printed or otherwise positioned on the flexible substrate. Measurements from each of layers <NUM>, <NUM>, <NUM>, and <NUM> are eventually routed to processing device(s) such as for example signal processor <NUM> and signal processing hardware such as amplifiers and filters.

As noted above, reference layer <NUM> is configured to measure magnetic radiation that may cause interference in the measurements carried by first signal trace <NUM> and second signal trace <NUM> and in the respective signal layers in layers <NUM>, <NUM> and <NUM>. Reference layer <NUM> is shorted and measures the magnetic fields that cause the magnetic interference. This information may then be used by processing device(s) such as for example signal processor <NUM> and signal processing hardware to cancel out the magnetic interference from the measurements carried by the signal layers, e.g., layers <NUM>, <NUM> and <NUM>.

<FIG> is an example printed flexible substrate <NUM> wrapped with respect to a catheter <NUM> in accordance with certain implementations. Catheter <NUM> can include a catheter shaft <NUM> and a handle <NUM>. Catheter shaft <NUM> includes a distal tip <NUM> which includes a sensor <NUM> as shown in <FIG>. Handle <NUM> includes an electronic card <NUM>, which may include filters, signal amplifiers, and analog-to-digital converters for signal processing. A printed flexible substrate <NUM> can be implemented as shown in <FIG> and then wrapped around a catheter shaft <NUM>. One end of printed flexible substrate <NUM> is connected to sensor <NUM> and another end of printed flexible substrate <NUM> is connected to electronic card <NUM>. In an implementation, in addition to and in conjunction with the configuration illustrated in <FIG>, a printed flexible substrate <NUM> can be wrapped around an irrigation tube, for example, inside of catheter shaft <NUM> for sensors that do not use magnetic based devices.

6A shows more detail for the configuration illustrated in <FIG> and FIG. 6B shows a cross-section of the configuration shown in FIG. 6A shows a catheter shaft <NUM> that has a printed flexible substrate <NUM> wrapped with respect to catheter shaft <NUM> in accordance with certain implementations. Printed flexible substrate <NUM> includes multiple layers <NUM><NUM> - <NUM>N, which carry signals from the sensors to the processing device(s). A shaft cross section <NUM> shows the layer structures where an inner layer <NUM> is built with isolation material. Conductor layers (i.e. printed flexible substrate) <NUM> is printed and isolated from a shielding layer <NUM> by an isolation layer <NUM>. The shielding layer <NUM> is isolated by a nonconductive layer <NUM>. The printed conductors/traces are applied in a spiral shape to enable flexibility of the shaft <NUM>.

<FIG> is a method <NUM> for assembling a catheter in accordance with certain implementations. A flexible substrate is printed with conductive traces (<NUM>). Each printed flexible substrate can include multiple layers or levels. The printed flexible substrate is then environmentally protected (<NUM>). For example, the printed flexible substrate can be laminated. The printed flexible substrate is then inserted into the catheter shaft (<NUM>). Connectors are attached to each end of the printed flexible substrate (<NUM>). One set of connectors are connected to sensors in the catheter and another set of connectors are attached to electronic cards or connectors in a handle of the catheter (<NUM>). In an implementation, another printed flexible substrate may be wrapped with respect to a shaft of the catheter (<NUM>). Connectors are attached to each end of the another printed flexible substrate (<NUM>). One set of connectors are connected to sensors in the catheter and another set of connectors are attached to electronic cards or connectors in a handle of the catheter (<NUM>).

In general, a method for catheter assembly includes printing conductive traces on at least one flexible substrate, encapsulating the at least one flexible substrate for environmental protection, inserting at least one encapsulated flexible substrate into a catheter shaft of a catheter, attaching connectors to each end of the at least one encapsulated flexible substrate, attaching a set of connectors to sensors located at a distal end of the catheter, and attaching another set of connectors to electronics in a handle of the catheter. In an implementation, the method includes wrapping an encapsulated flexible substrate around a component contained within the catheter shaft, attaching connectors to each end of the encapsulated flexible substrate, attaching a set of connectors to non-magnetic based sensors in the catheter, and attaching another set of connectors to electronics in a handle of the catheter. The at least one flexible substrate includes a plurality of layers, each layer having a plurality of conductive traces. The plurality of layers includes a reference layer, and the method further includes shorting two of the plurality of conductive traces in the reference layer to measure magnetic radiation for interference cancellation determination. In an implementation, the plurality of layers includes signal layers that are connected to the sensors. In an implementation, the encapsulating step includes at least laminating the at least one flexible substrate. In an implementation, the at least one encapsulated flexible substrate is rolled prior to insertion into the catheter shaft. In an implementation, the at least one encapsulated flexible substrate is inserted substantially linear into the catheter shaft. In an implementation, the conductive traces include signal traces and ground traces.

In general, a catheter includes a catheter shaft having a distal end and a handle. The catheter further includes sensors located at the distal end, electronics located at the handle and at least one flexible substrate which is inserted inside the catheter shaft, where the at least one flexible substrate has conductive traces. The catheter further includes first connectors which connect the sensors to one end of the at least one flexible substrate and second connectors which connect the electronics to another end of the at least one flexible substrate. The first connectors and the second connectors are connected after insertion into the catheter shaft. In an implementation, the at least one flexible substrate is encapsulated for environmental protection. In an implementation, the catheter further includes non-magnetic sensors, another flexible substrate that is wrapped around a component in the catheter shaft, third connectors which connect the non-magnetic sensors to one end of the another flexible substrate and fourth connectors which connect the electronics to another end of the flexible substrate. The at least one flexible substrate includes a plurality of layers, each layer having a plurality of conductive traces. The plurality of layers includes a reference layer, where two of the plurality of conductive traces are shorted in the reference layer to measure magnetic radiation for interference cancellation determination. In an implementation, the plurality of layers includes signal layers that are connected to the sensors. In an implementation, the at least one flexible substrate is laminated for environmental protection. In an implementation, the at least one flexible substrate is rolled prior to insertion into the catheter shaft. In an implementation, the at least one flexible substrate is positioned substantially linear into the catheter shaft. In an implementation, the conductive traces include signal traces and ground traces.

The description herein is with respect to cardiac mapping and ablation procedures for a cardiac system, although it is understood by one skilled in the art that the disclosures may be applied to systems and procedures that can be used in any cavity or system in the body, including, but not limited to, the respiratory/pulmonary system, the respiratory and pulmonary system, the digestive system, the neurovascular system, and/or the circulatory system.

Claim 1:
A method for catheter assembly, the method comprising:
printing conductive traces on at least one flexible substrate;
encapsulating the at least one flexible substrate (<NUM>) for environmental protection, wherein the at least one flexible substrate includes a plurality of layers, wherein each layer has a plurality of conductive traces and the plurality of layers includes a reference layer (<NUM>), the method further comprising:
shorting two of the plurality of conductive traces in the reference layer to allow for measurement of the magnetic radiation for interference cancellation determination;
inserting at least one encapsulated flexible substrate into a catheter shaft (<NUM>) of a catheter (<NUM>);
attaching connectors (<NUM>, <NUM>) to each end of the at least one encapsulated flexible substrate, wherein;
a set of the connectors (<NUM>) is also connected to sensors located at a distal end of the catheter; and
another set of the connectors (<NUM>) is also connected to electronics in a handle (<NUM>) located at a proximal end of the catheter.