Dynamic ablation catheter

Abstract

An example method of ablating target tissue of a patient includes sensing, by an impedance sensor, a first impedance of the target tissue at a first time, causing, by processing circuitry and before a second time that is after the first time, an energy delivery element of an ablation catheter to deliver a first amount of ablation energy to the target tissue, and sensing, by the impedance sensor, a second impedance of the target tissue at the second time. The method also includes determining, by the processing circuity and based on a difference between the first impedance and the second impedance, a second amount of ablation energy, and causing, by the processing circuitry, the energy delivery element of the ablation catheter to deliver the second amount of ablation energy to the target tissue at a third time that is after the second time.

Description

DYNAMIC ABLATION CATHETER

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 712,226, filed October 25, 2024, the entire content of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present technology is related to ablation catheters. In particular, various examples of the present technology are related to ablation techniques using medical systems including ablation catheters.BACKGROUND

[0003] Tissue ablation is a medical procedure commonly used to treat conditions such as cardiac arrhythmias, which includes atrial fibrillation. For treating cardiac arrhythmias, ablation can be performed to modify tissue, such as to stop aberrant electrical propagation and / or disrupt aberrant electrical conduction through cardiac tissue. Ablation techniques include pulsed field ablation (PF A), cryoablation, laser ablation, radio ablation and radiofrequency (RF) ablation.

[0004] Cardiac arrhythmias are a group of conditions that cause an irregular heartbeat or conduction pattern. Ablation may be used to create a safe and effective lesion or set of lesions at the origin of the irregular heartbeat or in regions that aid in the termination of arrhythmias without causing damage to adjacent structures or surrounding tissue, ideally resulting in no need for a maintenance treatment regimen, such as medications or cardioversions.SUMMARY

[0005] The present disclosure is directed to devices, systems, and methods for ablation using dynamic energy delivery to create the desired lesion. An ablation delivery system may adjust an amount of ablation energy delivered by one or more energy delivery elements, or adjust the number and which energy delivery elements deliver energy, e.g., adjusting the vectoring of the delivery of ablation energy by adjusting the surface area and locations of where ablation energy is delivered and by which energy delivery elements, based on animpedance of the target tissue or a difference of the impedance of the target tissue before, during, and after delivery of ablation energy.

[0006] In one example, this disclosure describes a method of ablating target tissue of a patient, the method including: sensing, by an impedance sensor, a first impedance of the target tissue at a first time; causing, by processing circuitry and before a second time that is after the first time, an energy delivery element of an ablation catheter to deliver a first amount of ablation energy to the target tissue; sensing, by the impedance sensor, a second impedance of the target tissue at the second time; determining, by the processing circuity and based on a difference between the first impedance and the second impedance, a second amount of ablation energy; and causing, by the processing circuitry, the energy delivery element of the ablation catheter to deliver the second amount of ablation energy to the target tissue at a third time that is after the second time.

[0007] In another example, this disclosure describes a system including: an ablation catheter including an ablation energy delivery element; a processor, and a memory in communication with the processor and storing instructions that, when executed by the processor, cause the processor to: cause an impedance sensor to sense a first impedance of a target tissue of a patient at a first time; cause an energy delivery element of the ablation catheter to deliver a first amount of ablation energy to the target tissue; cause the impedance sensor to sense a second impedance of the target tissue at a second time; determine, based on a difference between the first impedance and the second impedance, a second amount of ablation energy; and cause the energy delivery element of the ablation catheter to deliver the second amount of ablation energy to the target tissue at a third time.

[0008] In another example, this disclosure describes a computer readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to: cause an impedance sensor to sense a first impedance of a target tissue at a first time; cause an energy delivery element of an ablation catheter to deliver a first amount of ablation energy to the target tissue; cause the impedance sensor to sense a second impedance of the target tissue at a second time; determine, based on a difference between the first impedance and the second impedance, a second amount of ablation energy; and cause the energy delivery element of the ablation catheter to deliver the second amount of ablation energy to the target tissue at a third time.

[0009] The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. l is a conceptual diagram illustrating an example system for delivering ablation.

[0011] FIG. 2A is a flow diagram illustrating an example method of ablating target tissue of a patient.

[0012] FIG. 2B is a flow diagram further illustrating the example method of ablating target tissue of a patient of FIG. 2A

[0013] FIG. 3 A is a conceptual diagram illustrating vectoring of multi-polar ablation energy delivery.

[0014] FIG. 3B is a conceptual diagram illustrating contact of one or more ablation energy delivery elements of an ablation catheter.

[0015] FIG. 4 is a block diagram illustrating an example controller of an ablation system.DETAILED DESCRIPTION

[0016] Tissue ablation may be used to treat conditions such as cardiac arrhythmias, which includes atrial fibrillation. For treating cardiac arrhythmias, ablation may be performed to modify tissue, such as to stop aberrant electrical propagation and / or disrupt aberrant electrical conduction through cardiac tissue. Ablation techniques may include pulsed field ablation (PF A) and radiofrequency (RF) ablation.

[0017] Cardiac arrhythmias are a group of conditions that cause an irregular heartbeat or conduction pattern. Ablation may be used to create a safe and effective lesion or set of lesions at the origin of the irregular heartbeat or in regions that aid in the termination of arrhythmias without causing damage to adjacent structures or surrounding tissue, ideally resulting in no need for a maintenance treatment regimen, such as medications or cardioversions.

[0018] Current systems may be limited to their current energy delivery configurations (e.g., bipolar or a single energy delivery element to ground for RF, and either unipolar or bipolar for PF). As such, system design may limit lesion depth and shape and multiple applications can be required to optimize lesion morphology, e.g., size, width, depth and / or shape.

[0019] In accordance with one or more aspects of this disclosure, a system may adjust the number and location of ablation energy delivery elements of an ablation catheter based on impedance of the tissue during or after the ablation delivery. For example, for each energy delivery element of the ablation catheter, processing circuitry may determine whether an energy delivery element is in an area for which a lesion is to be formed, e.g., positioned correctly via imaging or other suitable methods. If the processing circuitry determines that the energy delivery element is not positioned correctly, the processing circuitry may deactivate (e.g., turn off) the energy delivery element and / or initiate repositioning of the catheter. For example, the processing circuitry may initiate repositioning of the catheter by outputting a message indicating that the energy delivery element is not positioned correctly, and may indicate that the catheter should be repositioned and / or the energy delivery element be deactivated, e.g., by a user and / or physician. If the processing circuitry determines that the energy delivery element is positioned correctly, an impedance sensor of the system may sense and / or measure an impedance of the tissue, e.g., using the energy delivery element.

[0020] The measured impedance may be indicative of whether or not the energy delivery element is in contact with, or proximate to, the target tissue, and the processing circuitry may determine, based on the impedance, whether the energy delivery element is in contact with the tissue, proximate to the tissue, or neither. If the processing circuitry determines that the energy delivery element is not in contact with or proximate to the tissue, the catheter may be repositioned and the impedance measured again, e.g., the processing circuitry may output a message indicating that the energy delivery element catheter should be repositioned. If the processing circuitry determines that the energy delivery elements is in contact with, or is proximate to, the tissue, the processing circuitry may cause the energy delivery element to deliver ablation energy according to an ablation, or treatment, strategy, e.g., pulsed field ablation (PF A) or radio frequency (RF) ablation. In some examples, if the processing circuitry determines that the energy delivery elements is in contact with, or isproximate to, the tissue, the processing circuitry may output a message indicating that the energy delivery element should be activated, e.g., by a user and / or physician, to deliver ablation energy according to an ablation, or treatment, strategy. In some examples, the impedance sensor may sense and / or measure the impedance as a complex impedance, e.g., having an impedance magnitude and phase and / or having real and imaginary components.

[0021] Additionally, before moving on to the next energy delivery element, the processing circuitry may determine an appropriate ablation procedure and dose, e.g., amount of ablation energy, to be delivered by the energy delivery element based on whether the tissue is normal or abnormal, e.g., where abnormal tissue may be scarred, infarcted, and / or diseased. For example, the impedance of tissue that the energy delivery element is in contact with or proximate to may be indicative of whether the tissue is scarred, infarcted, and / or diseased, and the processing circuitry may adjust the amount of ablation energy to be delivered by the energy delivery element. In some examples, the processing may determine other energy delivery elements of the catheter, even adjacent energy delivery elements, to have a different dose based on the tissue being not scarred, infarcted, and / or diseased.

[0022] After determining, for each energy delivery element, whether to use the energy delivery element and the dose and ablation type (e.g., PFA or RF) for each energy delivery element, the processing circuitry may cause each energy delivery element to deliver ablation energy according to its dosing strategy and the impedances of the tissue. Example dosing strategies may include delivering RF ablation energy with a predetermined amount of power and / or current, or a power schedule (e.g., with a power and / or current that changes as a function of time), or with a power and / or current based on a target tissue temperature and / or impedance, change in irrigation rate, delivering PFA energy according to parameters including voltage and / or current pulse amplitude, frequency, duty cycle, number of pulses, and pulse width. After delivery of the ablation energy, the impedance sensor may sense and / or measure the impedance(s), using each energy delivery element, to determine whether to continue or repeat ablation, whether to adjust the dose and or ablation type of each energy delivery element, whether to adjust the ablation catheter, whether to include or remove energy delivery elements from the set of energy delivery elements delivering ablation, whether to include or remove energy delivery elements from a different catheter that may deliver ablation, or whether to end application of ablation. In some examples, the processing circuitry may cause some energy delivery elements to continue / repeat application ofablation and other energy delivery elements to turn off, e.g., end application of ablation energy by those other energy delivery elements, based on the impedance measured using each of the energy delivery elements. In some examples, the processing circuitry may verify the ablation / lesion formation based on other ablation markers, e.g., imaging, before ending the application session, or to aid in determining whether to initiate adjustment the catheter position in order to loop back and cause one or more of the energy delivery elements to repeat delivery of ablation energy.

[0023] The devices, systems, and methods described herein may provide for configuration changes to an ablation system that allows for dynamic energy delivery to create the desired lesion, e.g., size, width, depth and / or shape, without multiple applications. In some examples, the devices, systems, and methods may provide for improved energy efficiency and lesion formation via adjusting delivery of ablation energy to target tissue (e.g., adjusting vectoring of ablation energy) and changing the delivery method, or not delivering, ablation energy to non-target tissue, e.g., non-target tissue that is proximate to target tissue or is within target tissue but is abnormal, e.g., scarred, infarcted, and or diseased.

[0024] FIG. 1 is a conceptual diagram illustrating an example system 100 for delivering ablation. System 100 includes a catheter 102, a controller 104, and an anatomical information device 114. In general, to deliver ablation, a practitioner (e.g., electrophysiologist, interventional cardiologist, etc.) may insert one or more of catheter 102 into a patient and cause controller 104 to deliver, via catheter 102, energy (e.g., pulsed field ablation energy and / or radiofrequency ablation energy) to target tissue of a patient. Ablation may cause lesions in target cardiac tissue which may mitigate or stop cardiac arrhythmias. As ablation causes lesions in the target tissue, it may be desirable for system 100 to safely and accurately provide information to a clinician regarding ablation parameters, such as a suggested location where to position one or more energy delivery elements 110 of one or more catheters 102, an amount of energy to be delivered during ablation, or which tissue would be ablated after delivery of ablation energy via the at least one energy delivery element 110.

[0025] Catheter 102 may be an ablation catheter, and may include elongated structure 112 carrying a plurality of energy delivery elements 110A-110H (collectively “energy delivery elements 110”). An energy delivery element may include an electrode (e.g., in the case of a PFA catheter), a radiofrequency element (e.g., in the case of a radiofrequencyablation catheter), or both (e.g., in the case of a PFA and RF catheter), or another energy delivery element. While the techniques of this disclosure are applicable to any ablation catheter, the example of FIG. 1 is directed to a PFA and / or RF ablation catheter. Catheter 102 may generally include features that enable insertion of catheter 102 into a patient and navigation of catheter 102 to a target tissue site. Elongated structure 112 may include a distal portion 106 and a proximal portion 108. Energy delivery elements 110 may be generally positioned at distal portion 106, while proximal portion 108 may be connected to controller 104. Energy delivery elements 110 may be of any suitable geometry. Example geometries of energy delivery elements include, but are not necessarily limited to, circular (e.g., ring) electrodes surrounding the body of the lead, conformable electrodes, cuff electrodes, segmented electrodes (e.g., electrodes disposed at different circumferential positions around the lead instead of a continuous ring electrode), any combination thereof (e.g., ring electrodes and segmented electrodes). Energy delivery elements 110 may be axially distributed along longitudinal axis LA of elongated structure 112 or in several other configurations. In some examples, catheter 102 may include one or more energy delivery elements 110 and the geometry of the one or more energy delivery elements 110 may include a balloon, which may be inflated when performing ablation and deflated when navigating catheter 102 to the target tissue. The delivery elements 110 may also be in a circular form, in an array, along multiple splines, or in other configurations.

[0026] Elongated structure 112 may include conductors configured to carry electrical signals between energy delivery elements 110 and controller 104. In some examples, elongated structure 112 may include a separate conductor for each of energy delivery elements 110. For instance, in the example of FIG. 1 where energy delivery elements 110 includes eight electrodes, elongated structure 112 may include eight separate conductors. In this way, elongated structure may enable each electrode of energy delivery elements 110 to be driven with a different signal from controller 104. In other examples, multiple electrodes of energy delivery elements 110 may share a common conductor. For instance, energy delivery elements 110C and HOD may be connected to a same (e.g., a common) conductor. While such a common conductor arrangement may reduce energy delivery element flexibility (e.g., as electrodes connected to the common conductor may be driven with a same signal), such an arrangement may reduce manufacturing complexity and / or cost and may increase the structural flexibility of catheter 102.

[0027] As shown in FIG. 1, energy delivery elements 110 may include a tip electrode (e.g., energy delivery element 110A), which may be a ring electrode with a “cap” covering at least a portion of a tip of elongated structure 112. In some examples, the tip electrode may be chamfered or otherwise rounded (e.g., to enable easier passage of catheter 102 through anatomy of the patient). Energy delivery elements 110 may include a ring electrode (e.g., energy delivery element HOB) that is adjacent to the tip electrode. This ring electrode may be separated (axially along LA) from the tip electrode. Energy delivery elements 110 may include one or more pairs of ring electrodes. A pair of ring electrodes may include two adjacently closely spaced electrodes of energy delivery elements 110. For instance, in the example of FIG.1, energy delivery elements 110C and HOD may form a first pair of ring electrodes, energy delivery elements 110E and 110F may form a second pair of ring electrodes, and energy delivery elements 110G and 110H may form a third pair of ring electrodes. In general, the first pair of ring electrodes (i.e., energy delivery elements 110C and 110D) may be accompanied by one or more additional electrodes. The one or more additional electrodes may include any combination of pairs of ring electrodes and coil electrodes (e.g., electrodes that include conductors that spiral around elongated structure 112).

[0028] In the example of FIG. 1, energy delivery elements 110 are illustrated as has having a larger diameter than elongated structure 112. In some examples, one or more of energy delivery elements 110 may have a diameter that is approximately equal to or less than the diameter of elongated structure 112. For instance, energy delivery elements 110 may be recessed in elongated structure 112 such that the combination results in a relatively smooth outer surface.

[0029] Controller 104 may include an energy generator configured to provide electrical pulses to energy delivery elements 110 (or to control the delivery of radio frequency energy or cryogenic energy by energy delivery elements 110) to perform an ablation procedure to cardiac tissue or other tissues within the patient's body, such as renal tissue, airway tissue, and organs or tissue within the cardiac space or the pericardial space. For instance, the energy generator may be configured and programmed to deliver pulsed, high-voltage electric fields appropriate for achieving desired pulsed, high-voltage ablation, e.g., PF A, “pulsed electric field ablation,” and / or radiofrequency ablation. Controller 104 may include impedance sensor(s) 124 configured to sense an impedance of one or moreenergy delivery elements 110, impedance of tissue of the patient (e.g., a tissue impedance), and / or an impedance of system 100 or a component of system 100, e.g., catheter 102 and / or components of catheter 102. Impedance sensor(s) 124 may be configured to sense complex impedances, e.g., impedance magnitudes and phases.

[0030] Anatomical information device(s) 114 may include a computed tomography (CT) device, a magnetic resonance imaging (MRI) device, an ultrasound (U / S) device, a pacing device, an electrophysiology (EP) mapping device, a biophysical property sensing device, e.g., such as a nicotinamide adenine dinucleotide (NADH) sensing device, and / or a non-invasive mapping device. Information sensed by anatomical information device(s) 114 may be used by system 100 to inform controller 104 of the anatomy of a patient, physical or electrical characteristics of the anatomy, and / or a location of catheter 102 during delivery of catheter 102 into the anatomy of a patient. Anatomical information device(s) 114 may sense one or more ablation markers, e.g., electrical, optical, and / or physical properties of a lesion, and / or the morphology of a lesion, e.g., size, width, depth and / or shape of a lesion. Controller 104 may determine an ablation marker, and determine whether a lesion satisfies target lesion criteria (e.g., electrical, optical, physical properties and / or morphology) based at least in part on an ablation marker, or information indicative of an ablation marker, sensed by anatomical information device(s) 114. In some examples, controller 104 may include one or more of anatomical information device(s) 114.

[0031] In accordance with one or more aspects of this disclosure, a system 100 for use in ablating target tissue of a patient includes controller 104 including non-transitory computer readable medium (e.g., memory) communicatively coupled processing circuitry and / or one or more processors configured to sense impedances and control ablation parameters of catheter 102. For example, the memory 422 (FIG. 4) may include instructions that, when executed by processing circuitry 418 (FIG. 4), may cause processing circuitry 418 to: cause impedance sensor(s) 124 to sense a first impedance of the target tissue at a first time, cause an energy delivery element 110A-H of catheter 102 to deliver a first amount of ablation energy to the target tissue, cause impedance sensor(s) 124 to sense a second impedance of the target tissue at a second time, determine, based on the difference between the first impedance and the second impedance, a second amount ofablation energy, and cause the energy delivery element 110 of the catheter 102 to deliver the second amount of ablation energy to the target tissue at a third time.

[0032] The techniques of this disclosure may provide for configuration changes to system 100 that allows for dynamic energy delivery to create the desired lesion, e.g., size, width, depth and / or shape, without multiple applications. The techniques of this disclosure may also provide clinicians with improved control of ablation to improve the efficacy of lesions that they create during a cardiac ablation procedure. In some examples, the devices, systems, and methods may provide for improved energy efficiency and lesion formation via adjusting delivery of ablation energy to target tissue and changing the delivery method, or not delivering, ablation energy to non-target tissue, e.g., non-target tissue that is proximate to target tissue or is within target tissue but is abnormal, e.g., scarred, infarcted, and or diseased.

[0033] Although not shown, system 100 may include one or more sensors, in addition to impedance sensor 124, to monitor the operating parameters through system 100, such as temperature, delivered voltage, or the like, and for measuring and monitoring one or more tissue characteristics, such as EGM waveforms, monophasic action potentials, or the like, in addition to monitoring, recording, or otherwise conveying measurements or conditions within the catheter 102 or other component of system 100 or the ambient environment at the distal portion 106 of catheter 102. The sensor(s) may be in communication with controller 104 for initiating or triggering one or more notifications and / or alerts, or ablation energy delivery modifications such as repositioning catheter 102. In some examples, such sensors may be part of controller 104 and / or catheter 102.

[0034] FIGS. 2 A and 2B are flow diagrams illustrating an example method of ablating target tissue of a patient. FIGS. 2A and 2B are described with respect to system 100, catheter 102, and impedance sensors(s) 124 of FIG. 1, and processing circuitry 418 of controller 404 of FIG. 4. However, other devices may be used to perform techniques of FIGS. 2A and 2B. In the example shown, (202) through (224) may be performed in a loop iterating through one or more of the energy delivery elements 110 of catheter 102, e.g., to select and / or configure the ablation type, dose amount, and dosing strategy for each individual energy delivery element 110, and the ablation type, dose amount, and dosing strategy may be different or the same as one or more of the other energy delivery elements 110. In the examples shown, (226) and (302) through (332) may be performed subsequentto (202) through (224), e.g., after configuring the ablation type, dose amount, and dosing strategy for each individual energy delivery element 110.

[0035] A clinician may start an ablation procedure (202). For example, a clinician may navigate catheter 102 to a target position within a patient to ablate target tissue, and initiate controller 404 and processing circuitry 418 to begin an ablation procedure.

[0036] Processing circuitry 418 may determine whether an energy delivery element 110 is positioned correctly (204). For example, processing circuitry 418 may determine whether the energy delivery element 110 is positioned correctly based information from anatomical information devices 114, e.g., imaging such as CT, MRI, U / S, and / or mapping such as EP mapping. In some examples, processing circuitry 418 may determine if energy delivery element 110 is positioned correctly based on input from the clinician. For example, the clinician may view imaging and / or mapping and input, via user interface 420 whether energy delivery element 110 is positioned correctly. If the energy delivery element 110 is not positioned correctly (the NO branch at (204), the processing circuitry 418 may output a message, e.g., indicating energy delivery element 110 is not positioned correctly and / or requesting repositioning, and / or the clinician may reposition the catheter 102 (206), and processing circuitry 418 (and / or the clinician) may subsequently determine whether the energy delivery element 110 is positioned correctly after the repositioning at (204).

[0037] If the energy delivery element 110 is positioned correctly (the YES branch at (204)), impedance sensor 124 may sense and / or measure a first impedance of target tissue at a first time (208). For example, impedance sensor 124 may sense the first impedance via the energy delivery element 110, or one or more other of energy delivery elements 110, or via a separate sensing element (e.g., conductive pad, not shown in FIG. 1) along distal portion 106 of catheter 102, at a time prior to delivering ablation energy. For example, sensor 124 and / or energy generator 416 may send a relatively low power electrical signal between two energy delivery elements 110, e.g., including the energy delivery element 110 determined to be positioned correctly, and sensor 124 may sense an impedance based on a measured voltage and / or current resulting from the signal. In some examples, controller 404 may control two or more catheters 102, and one or more impedance sensor 124 and / or energy generator 416 may send a relatively low power electrical signal between the energy delivery element 110 determined to be positioned correctly, e.g., on the first catheter 102, and an energy delivery element 110 of the second, different catheter 102. For example, theclinician may navigate and position two catheters 102 within the patient to ablate target tissue between the two catheters 102, and / or to sense one or more system 100 and / or patient parameters (e.g., impedance and / or tissue impedance). Alternatively or additionally, the clinician may navigate and / or position one target catheter 102 within the patient and position a second, external catheter on the patient to ablate target tissue and / or sense one or more system 100 and / or patient parameters (e.g., impedance and / or tissue impedance). In some examples, the external catheter may be substantially similar to catheter 102 described above, except designed to be used external to the patient.

[0038] Processing circuitry 418 may determine whether the first impedance is indicative of contact between the energy delivery element 110 and the target tissue (210). For example, processing circuitry 418 of controller 404 may determine that the energy delivery element 110 is in direct contact with target tissued based on at least one of the magnitude or phase of the sensed impedance.

[0039] Processing circuitry 418 may determine, based on the first impedance, that the energy delivery element 110 is in contact with that target tissue (the YES branch at 210). Responsive to determining that energy delivery element 110 is in contact with the target tissue, processing circuitry 418 may then select and / or configure the energy delivery element 110 to deliver a first amount of ablation energy to the target tissue via PF A or RF ablation (212) (e.g., the delivery of the first amount ablation energy occurring at (226) as described below). Processing circuitry 418 may determine, based on the first impedance, that the energy delivery element 110 is not in contact with the target tissue (the NO branch at 210). Responsive to determining that energy delivery element 110 is not in contact with the target tissue, processing circuitry 418 may then determine whether the first impedance is indicative of proximity between an energy delivery element 110 and the target tissue (214). Responsive to determining that energy delivery element 110 is proximate to the target tissue, processing circuitry 418 may then select and / or configure the energy delivery element 110 to deliver the first amount of ablation energy to the target tissue via PF A (216). For example, processing circuitry 418 of controller 404 may determine whether the first impedance is indicative of at least one of contact between the energy delivery element 110 and the target tissue or proximity between the energy delivery element 110 and the target tissue, and cause energy delivery element to select and / or configure the ablation energy element 110 to deliver the ablation energy via only PFA if the impedance indicates proximity to, but notcontact with, the target tissue, or select and / or configure the ablation energy element 110 to deliver the ablation energy via PFA and / or RF ablation if the impedance indicates contact with the target tissue.

[0040] Processing circuitry 418 may determine, based on the first impedance, that the energy delivery element 110 is not in proximity to the target tissue (the NO branch at 214). Responsive to determining that energy delivery element 110 is not proximate to the target tissue, processing circuitry 418 may generate a notification that the energy delivery element 110 is not in contact with and / or not in proximity to the target tissue. For example, processing circuitry 418 may generate and output a notification and / or message via user interface 420. The clinician may then reposition the catheter 102 at (206), and subsequently determine whether one or more energy delivery elements 110 are positioned correctly after the repositioning at (204). For example, the method may loop back to positioning catheter 102, verifying catheter 102 is positioned correctly at (204), and sensing a first impedance (e.g., a subsequent “first” impedance which may be a first impedance with the energy delivery element 110 positioned correctly) of the target tissue at a first time (e.g., a subsequent “first” time which may be a first time with the energy delivery element 110 positioned correctly) at (208).

[0041] Additionally or alternatively, responsive to determining that energy delivery element 110 is not proximate to the target tissue, processing circuitry 418 may determine whether to turn the energy delivery element 110 off (215) (e.g., at the dashed line NO branch at (214)). For example, processing circuitry 418 may determine to select and / or configure the energy delivery element 110 to deliver a zero amount of ablation energy (e.g., to turn the electrode off at the YES branch at (215)), and determine whether to move on to configuring the next energy delivery element 110 at (224) as further described below. In some examples, alternatively or additionally, the clinician may determine to turn off the energy delivery element 110 at (215). For example, the clinician may cause (e.g., via user interface 420) processing circuitry 418 to configure the energy delivery element to be off, e.g., after receiving the notification generated by processing circuitry 418 at (214) that the energy delivery element 110 is not in contact with and / or not in proximity to the target tissue. Processing circuitry 418 may determine, or the clinician may cause processing circuitry 418, to not select and / or configure the energy delivery element 110 to deliver a zero amount ofablation energy (e.g., not to turn the electrode off at the NO branch at (215)), and the method may proceed to (206) as described above.

[0042] Processing circuitry 418 may determine, based on the first impedance, whether the target tissue is abnormal tissue or not abnormal (e.g., “normal”) tissue at (218). For example, processing circuitry 418 may determine, based on the first impedance, that the target tissue is abnormal tissue (the YES branch at (218)). Responsive to determining that target tissue is abnormal tissue, processing circuitry 418 may then determine the first amount of ablation energy delivered by the energy delivery element 110 to be a first abnormal tissue amount that is different from a first normal tissue amount based on the target tissue being abnormal (222). For example, if the target tissue is abnormal, e.g., scarred, infarcted, and / or diseased, the electrical and physical properties of the tissue may be different than normal tissue and processing circuitry 418 may determine a dosing amount and / or a dosing strategy appropriate for the abnormal tissue that is different than a dosing amount and / or a dosing strategy appropriate for normal tissue. In some examples, processing circuitry 418 may determine to use PFA rather than RF ablation for abnormal tissue. In some examples, processing circuitry 418 may determine the first abnormal tissue amount to be greater than a first normal tissue amount, e.g., so as to ablate more thoroughly initially and reduce and / or prevent edema and improve the ease of creating subsequent lesions.

[0043] Alternatively, processing circuitry 418 may determine, based on the first impedance, that the target tissue is not abnormal tissue (the NO branch at (218)). Responsive to determining that target tissue is not abnormal tissue, processing circuitry 418 may then determine the first amount of ablation energy delivered by the energy delivery element 110 to be the first normal tissue amount that is different from the first abnormal tissue amount based on the target tissue being not abnormal (e.g., being normal) (220). For example, if the target tissue is not abnormal, e.g., not scarred, infarcted, and / or diseased, processing circuitry 418 may determine the dosing amount and / or the dosing strategy appropriate for the normal tissue that is different than the dosing amount and / or the dosing strategy appropriate for abnormal tissue.

[0044] Processing circuitry 418 may determine whether to configure the next energy delivery element 110 (224). For example, after determining the ablation type and dosing amount and dosing strategy, e.g., the first amount of ablation energy, of the energy delivery element 110 (e.g., after configuring the ablation energy delivery parameters of the energydelivery element 110), processing circuitry 418 may determine that not all of the energy delivery elements 110 have been configured (the YES branch at 224) and the method may loop back to (204) for the next energy delivery element 110. Alternatively, processing circuitry 418 may determine that all of the energy delivery elements 110 of catheter 102 have been configured (the NO branch at 224). Processing circuitry 418 may then cause the energy delivery element 110 to deliver the first amount of ablation energy to the target tissue (226). In some examples, processing circuitry 418 may determine that at least one of the energy delivery elements 110 of catheter 102 have been configured and then cause the at least one energy delivery element 110 to deliver the first amount of ablation energy to the target tissue at (226) e.g., as long as one or more electrodes are configured and / or positioned correctly, the method may move on to (226) to deliver ablation energy via the one or more electrodes. In some examples, processing circuitry 418 may determine that all the energy delivery elements 110 of catheter 102 have been configured, but all of the electrodes are deactivated or turned off, e.g., at (215), and output a message indicating that no electrodes are configured to delivery energy and / or end the current application of ablation energy delivery or the ablation energy delivery session. In some examples, processing circuitry 418 may cause one or more of all of the energy delivery elements 110 to deliver the first amount of ablation energy determined for each individual energy delivery element 110 (which may the same or different than each of the other energy delivery elements 110) in parallel (e.g., at the same time), sequentially, or in any combination of parallel or sequentially. The method may then proceed to (302).

[0045] Referring the FIG. 2B, impedance sensor 124 may sense and / or measure a second impedance of target tissue at a second time (304). For example, impedance sensor 124 sense the second impedance via the energy delivery element 110, or one or more other of energy delivery elements 110, or via a separate sensing element, and the impedance may be a complex impedance including a magnitude and phase, as described above at (208), but at a second time subsequent to the first time and subsequent to delivering the first amount of ablation energy to the targe tissue.

[0046] Processing circuitry 418 may determine whether the impedance decreased with ablation (306). If processing circuitry 418 determines that the second impedance is less than the first impedance (the YES branch at (306)), processing circuitry 418 may determine whether the impedance decreased by a threshold amount (308). For example, processingcircuitry 418 may determine a difference between the first impedance and the second impedance, and may determine the magnitude of the difference, e.g., the absolute difference between the first and second impedances. In some examples, processing circuitry may determine an absolute difference between the magnitudes of the first and second impedances (e.g., as a positive value whether processing circuitry subtracts the first impedance magnitude from the second impedance magnitude or subtracts the second impedance magnitude from the second impedance magnitude), and in some examples, processing circuitry 418 may determine the absolute difference between the first and second impedances as the norm of the difference between the first and second impedances as complex numbers, e.g., an absolute value of the magnitude of the vector difference (e.g., distance) between the first and second impedances as complex values. In some examples, the threshold amount may be at least a 10% (10 percent), e.g., a difference between the sensed impedances by 10% or more, or the threshold amount may be at least 10 Ohms, e.g., the difference between the magnitudes of the sensed impedances of 10 Ohms or more.

[0047] If processing circuitry 418 determines that the second impedance is less than the first impedance by an absolute difference that is greater than or equal to a threshold amount (the YES branch at 308), processing circuitry 418 may determine whether one or more other ablation markers (e.g., other than impedance) are verified (310). For example, other ablation markers may include information from anatomical information devices 114 and may including imaging information, e.g., verifying the lesion morphology such as size, width, depth and / or shape of the lesion. In some examples, ablation markers may include one or more tissue characteristics, such as EGM waveforms, monophasic action potentials, or any suitable tissue characteristic indicative of a lesion satisfying target lesion criteria.

[0048] If processing circuitry 418 determines the one or more other ablation markers are verified (the YES branch at 310), processing circuitry 418 may select and / or configure at least one energy delivery element 110 to have a second amount of ablation energy to be a zero amount (312). For example, processing circuitry 418 may determine that at least a portion of the lesion satisfies target lesion criteria, e.g., based on the second impedance and / or a difference between the first and second impedances, and verify that the lesion satisfies the target lesion criteria via other ablation markers. Processing circuitry 418 may then turn off the energy delivery elements 110 of catheter 102 to end the procedure, or to turn off one or more of the energy delivery elements 110 of catheter 102 before subsequentlydelivering ablation energy via other (e.g., not turned off) energy delivery elements 110. If processing circuitry 418 determines and verifies the entire lesion satisfies that target lesion criteria, processing circuitry 418 may turn off all of the energy delivery elements 110 and end the procedure (312), and / or generate a notification and / or message (via user interface 420) that the procedure resulted in a lesion satisfying the target lesion criteria. If processing circuitry 418 determines and verifies that a portion, but less than the entirety, of the lesion satisfies that target lesion criteria, the method may follow the NO branch at 310 (as further described below) except that processing circuitry 418 may turn off some, but less than all, of the energy delivery elements 110, e.g., in preparation for subsequent delivery of ablation energy by other energy delivery elements 110 to further complete formation of a lesion that satisfies the target lesion criteria.

[0049] If processing circuitry 418 determines the one or more other ablation markers are not verified (the NO branch at 310), processing circuitry 418 may continue and / or repeat ablation (314). Additionally, if processing circuitry 418 determines that the second impedance is less than the first impedance by an absolute difference that is less than the threshold amount (the NO branch at 308), processing circuitry 418 may continue and / or repeat ablation (314). For example, processing circuitry 418 may determine, based on the difference between the first impedance and the second impedance, a second amount of ablation energy to be delivered by one or more energy delivery elements 110. In some examples, processing circuitry 418 may additionally or alternatively determine the second amount of ablation energy to be delivered by one or more energy delivery elements 110 based on a rate of change of impedance (e.g., the difference between the first and second impedances per amount of time) or a relative rate of change of impedance, e.g., a rate of change of impedance measured by different electrodes 110. , and processing circuitry 418 may cause one or more of the energy delivery elements 110 of the ablation catheter 102 to deliver the second amount of ablation energy to the target tissue at a third time, e.g., a third time that is subsequent to the second time. Impedance sensor 124 may sense and / or measure a third impedance of target tissue at a fourth time (315). For example, impedance sensor 124 sense the fourth impedance via the energy delivery element 110, or one or more other of energy delivery elements 110, or via a separate sensing element, and the impedance may be a complex impedance including a magnitude and phase, as described above at (208) and(304), but at a fourth time subsequent to delivering the second amount of ablation energy to the targe tissue.

[0050] Processing circuitry 418 may then determine whether the impedance decreased with ablation (316), e.g., similar to (306) described above, but subsequent to deliver of the second amount of ablation energy. If processing circuitry determines that the third impedance is less than the first impedance (the YES branch at (316)), processing circuitry 418 may determine whether the impedance decreased by the threshold amount at (308), e.g., the method may loop back to (308). For example, processing circuitry 418 may determine a difference between the first impedance and the third impedance at (308), and may determine the magnitude of the difference, e.g., the absolute difference between the first and third impedances as described above.

[0051] If processing circuitry determines that the third impedance is greater than or equal to than the first impedance (the NO branch at (316)), processing circuitry 418 may select and / or configure at least one energy delivery element 110 to have a second amount of ablation energy that is a zero amount at (312). For example, processing circuitry 418 may determine that, after two or more ablations, the lesion may not be progressing to satisfy the target lesion criteria. Processing circuitry 418 may then turn off all of the energy delivery elements 110 of catheter 102 and end the procedure at (312), or processing circuitry 418 may turn off the energy delivery elements 110 of catheter 102 before subsequently delivering ablation energy via other (e.g., not turned off) energy delivery elements 110, e.g., in preparation for subsequent delivery of ablation energy by other energy delivery elements 110 to further complete formation of portions of a lesion to satisfy the target lesion criteria. Processing circuitry 418 may then generate a notification and / or message (via user interface 420) that the procedure did not result in at least a portion of the lesion satisfying the target lesion criteria, or that one or more of energy delivery elements 110 are turned off and are not progressing formation of the lesion towards satisfying the target lesion criteria.

[0052] Referring back to (306), if processing circuitry 418 determines that the second impedance is equal to or greater than the first impedance (the NO branch at (306)), processing circuitry 418 may determine whether the impedance rose, or is rising, by a threshold amount (318). For example, a rising impedance may be indicative of a undesired effect, such as a steam pop. If processing circuitry 418 determines that the second impedance is equal to or greater than the first impedance (e.g., rising) by an amount (e.g.,an absolute difference) that is greater than or equal to the threshold amount (the YES branch at (318)), processing circuitry 418 may turn off the energy delivery elements 110 of catheter 102 and, in some examples, may end the procedure (320). Processing circuitry 418 may then generate a notification and / or message (via user interface 420) that the impedance corresponding to at least one of the energy delivery elements 110 (or sensed by at least one of the energy delivery elements 110) rose, or is rising, but at least the threshold amount.

[0053] Responsive to determining that the second impedance is equal to or greater than the first impedance (e.g., rising) by an amount (e.g., an absolute difference) that is less than the threshold amount (the NO branch at (318)), processing circuitry 418 may initiate an adjustment of the position of ablation catheter 102 (322). In some examples, processing 418 may initiate and adjustment of one or more of energy delivery elements 110, e.g., rather than the entire catheter 102. For example, processing circuitry 418 may generate a notification and / or message via user interface 420 requesting adjustment of catheter 102 and / or one or more of the energy delivery elements 110.

[0054] Processing circuitry 418 may then determine whether the adjustment at (322) worked, e.g., to cause a subsequent impedance to decrease (324). For example, after a clinician adjusts catheter 102 and / or one or more of the energy delivery elements 110, processing circuitry 418 may cause one or more of the energy delivery elements 110 to deliver the first amount, or a different amount (e.g., a test amount) of ablation energy to the target tissue. Impedance sensor 124 may then subsequently sense a fourth impedance of the target tissue. In some examples, impedance sensor 124 may measure the fourth impedance prior to processing circuitry 418 causing an energy delivery element 110 to deliver the second amount of ablation energy at the third time or the impedance sensor 124 measuring the third impedance at the fourth time, e.g., one or more of method steps (318) through (332) may occur before the method proceeds to the YES branch at (306), as shown in FIG. 2B. In other words, the steps of the NO branch at (306), in which fourth, fifth and sixth impedances are sensed (as described below), may occur prior to the third and fourth times described above. Processing circuitry 418 may then determine whether the impedance decreased, e.g., whether the fourth impedance is less than the first impedance. Processing circuitry 418 may determine that the adjustment worked based on the fourth impedance being less than the first impedance (the YES branch at (324)), or thatthe adjustment did not work based on the fourth impedance being greater than or equal to the first impedance (the NO branch at (324)).

[0055] If processing circuitry 418 determines that the adjustment at (322) worked (the YES branch at 324), processing circuitry 418 may determine whether the impedance decreased by the threshold amount, e.g., the method may proceed to (308) described above. For example, after determining that the adjustment worked at (324), processing circuitry 418 may determine whether the impedance decreased by a threshold amount at (308) by determining a difference and / or absolute difference between the first impedance and the fourth impedance. If processing circuitry 418 determines that the fourth impedance is less than the first impedance by an absolute difference that is greater than or equal to the threshold amount (the YES branch at 308 after adjustment at (322)), processing circuitry 418 may determine whether one or more other ablation markers (e.g., other than impedance) are verified at (310) as described above. If processing circuitry 418 determines the one or more other ablation markers are not verified (the NO branch at 310), or if processing circuitry 418 determines that the fourth impedance is less than the first impedance by an absolute difference that is less than the threshold amount (the NO branch at 308), processing circuitry 418 may continue and / or repeat ablation at the third time at (314), as described above, except that processing circuitry 418 may determine the second amount of ablation energy delivered by the energy delivery element 110 based on the difference between the first impedance and the fourth impedance. Impedance sensor 124 may then sense and / or measure the third impedance of target tissue at the fourth time (315) as described above.

[0056] If processing circuitry 418 determines that the adjustment at (322) did not work (the NO branch at 324), processing circuitry 418 may increase a number of active energy delivery elements 110 (326). For example, the energy delivery element 110 that delivered the first amount of ablation energy at (226) may be a first energy delivery element 110, and processing circuitry 418 may activate, or turn on, a second energy delivery element 110 of catheter 102.

[0057] Processing circuitry 418 may then determine whether increasing the number of active energy delivery elements 110 at (326) worked, e.g., to cause a subsequent impedance to decrease (328). For example, processing circuitry 418 may cause the first and second energy delivery elements 110 to deliver an amount of ablation energy to thetarget tissue, e.g., the first amount, a test amount, or another amount that may be based on the different positioning of the second energy delivery element 110 relative to the first energy delivery element 110. In some examples, processing circuitry 418 may activate a plurality of selected energy delivery elements 110 of catheter 102 to deliver an amount of ablation energy to the target tissue at (328). Impedance sensor 124 may then subsequently sense a fifth impedance of the target tissue. In some examples, impedance sensor 124 may measure the fifth impedance prior to processing circuitry 418 causing an energy delivery element 110 to deliver the second amount of ablation energy at the third time or the impedance sensor 124 measuring the third impedance at the fourth time, e.g., as described above at (324). Processing circuitry 418 may then determine whether the impedance decreased, e.g., whether the fifth impedance is less than the first impedance. Processing circuitry 418 may determine that the adjustment worked based on the fifth impedance being less than the first impedance (the YES branch at (328)), or that the adjustment did not work based on the fifth impedance being greater than or equal to the first impedance (the NO branch at (328)).

[0058] If processing circuitry 418 determines that the increase at (326) worked (the YES branch at 328), processing circuitry 418 may determine whether the impedance decreased by the threshold amount, e.g., the method may proceed to (308) described above. For example, after determining that the increase worked at (328), processing circuitry 418 may determine whether the impedance decreased by a threshold amount at (308) by determining a difference and / or absolute difference between the first impedance and the fifth impedance. If processing circuitry 418 determines that the fifth impedance is less than the first impedance by an absolute difference that is greater than or equal to the threshold amount (the YES branch at 308 after increase at (326)), processing circuitry 418 may determine whether one or more other ablation markers (e.g., other than impedance) are verified at (310) as described above. If processing circuitry 418 determines the one or more other ablation markers are not verified (the NO branch at 310), or if processing circuitry 418 determines that the fifth impedance is less than the first impedance by an absolute difference that is less than the threshold amount (the NO branch at 308), processing circuitry 418 may continue and / or repeat ablation at the third time at (314), as described above, except that processing circuitry 418 may determine the second amount of ablation energy delivered by the energy delivery element 110 based on the differencebetween the first impedance and the fifth impedance. Impedance sensor 124 may then sense and / or measure the third impedance of target tissue at the fourth time (315) as described above.

[0059] If processing circuitry 418 determines that the increase at (326) did not work (the NO branch at 328), processing circuitry 418 may increase a number of active energy delivery elements 110 of catheter 102 and increase the number of active energy delivery elements of another catheter, e.g., a second catheter positioned internal or external to the patient (330). For example, processing circuitry 418 may activate, or turn on, a second energy delivery element 110 of catheter 102 and a third energy delivery element of a different catheter (internal or external to the patient).

[0060] Processing circuitry 418 may then determine whether increasing the number of active energy delivery elements 110 on catheter 102 and an additional catheter at (330) worked, e.g., to cause a subsequent impedance to decrease (332). For example, processing circuitry 418 may cause the first, second, and third energy delivery elements 110 to deliver an amount of ablation energy to the target tissue, e.g., the first amount, a test amount, or another amount that may be based on the different positioning of the second and third energy delivery elements 110 relative to the first energy delivery element 110. In some examples, processing circuitry 418 may activate a plurality of selected energy delivery elements 110 of catheter 102 and a plurality of selected energy delivery elements 110 of the separate catheter to deliver an amount of ablation energy to the target tissue at (332). Impedance sensor 124 may then subsequently sense a sixth impedance of the target tissue. In some examples, impedance sensor 124 may measure the sixth impedance prior to processing circuitry 418 causing an energy delivery element 110 to deliver the second amount of ablation energy at the third time or the impedance sensor 124 measuring the third impedance at the fourth time, e.g., as described above at (324). Processing circuitry 418 may then determine whether the impedance decreased, e.g., whether the sixth impedance is less than the first impedance. Processing circuitry 418 may determine that the adjustment worked based on the sixth impedance being less than the first impedance (the YES branch at (332)), or that the adjustment did not work based on the sixth impedance being greater than or equal to the first impedance (the NO branch at (332)).

[0061] If processing circuitry 418 determines that the increase at (330) worked (the YES branch at 332), processing circuitry 418 may determine whether the impedancedecreased by the threshold amount, e.g., the method may proceed to (308) described above. For example, after determining that the increase worked at (332), processing circuitry 418 may determine whether the impedance decreased by a threshold amount at (308) by determining a difference and / or absolute difference between the first impedance and the sixth impedance. If processing circuitry 418 determines that the sixth impedance is less than the first impedance by an absolute difference that is greater than or equal to the threshold amount (the YES branch at 308 after increase at (330)), processing circuitry 418 may determine whether one or more other ablation markers (e.g., other than impedance) are verified at (310) as described above. If processing circuitry 418 determines the one or more other ablation markers are not verified (the NO branch at 310), or if processing circuitry 418 determines that the sixth impedance is less than the first impedance by an absolute difference that is less than the threshold amount (the NO branch at 308), processing circuitry 418 may continue and / or repeat ablation at the third time at (314), as described above, except that processing circuitry 418 may determine the second amount of ablation energy delivered by the energy delivery element 110 based on the difference between the first impedance and the sixth impedance. Impedance sensor 124 may then sense and / or measure the third impedance of target tissue at the fourth time (315) as described above.

[0062] If processing circuitry 418 determines that the increase at (330) did not work (the NO branch at 328), processing circuitry 418 may select and / or configure at least one energy delivery element 110 to have a second amount of ablation energy that is a zero amount at (312). For example, processing circuitry 418 may determine that, after the adjustments, increases, and two or more ablations of (322)-(332), the lesion may not be progressing to satisfy the target lesion criteria. Processing circuitry 418 may then turn off all of the energy delivery elements 110 of catheter 102 and end the delivery and / or procedure at (312), or processing circuitry 418 may turn off the energy delivery elements 110 of catheter 102 before subsequently delivering ablation energy via other (e.g., not turned off) energy delivery elements 110, e.g., in preparation for subsequent delivery of ablation energy by other energy delivery elements 110 to further complete formation of portions of a lesion to satisfy the target lesion criteria. Processing circuitry 418 may then generate a notification and / or message (via user interface 420) that the procedure did not result in at least a portion of the lesion satisfying the target lesion criteria, or that one ormore of energy delivery elements 110 are turned off and are not progressing formation of the lesion towards satisfying the target lesion criteria.

[0063] FIG. 3 A is a conceptual diagram illustrating vectoring of multi-polar ablation energy delivery, e.g., using catheter 102 and the method of FIGS. 2A and 2B described above. FIG. 3 A is described with respect to system 100 and catheter 102, and impedance sensors(s) 124 of FIG. 1, and processing circuitry 418 of controller 404 of FIG. 4.However, other devices may be used to perform vectoring of multi-polar ablation energy delivery.

[0064] In the example shown, catheter 102L is positioned at a first position relative to tissue 340 of a patient and catheter 102R is positioned at a second position relative to tissue 340. Catheters 102L and 102R may be substantially similar to catheter 102 described above, and are collectively referred to as “catheters 102” herein. Tissue 340 may be, or may include, target tissue of the patient. Tissue 340 may be cardiac tissue, renal tissue, airway tissue, organs or tissue within the cardiac space or the pericardial space, or any tissue suitable for delivering ablation energy.

[0065] System 100 including one or more ablation catheters, e.g., ablation catheters 102L, 102R and feedback sensors, e.g., impedance sensors 124 and / or sensors integrated into the ablation catheters, may reduce limitations to energy delivery configurations. System 100 may be configured to adjust, or allow a physician to adjust based on information from system 100, which electrodes are active and to change the vectoring of the ablation energy, e.g., how ablation energy is being applied, across and / or to tissue 340. In some examples, system 100 may be configured to enable changing of vectoring of ablation energy from a single catheter 102, multiple catheters 102, e.g., catheters 102L and 102R, from a catheter 102 and an indwelling electrode, e.g., an indwelling ground and / or reference electrode (not shown), or from a catheter 102 and an external electrode, e.g., an external ground and / or reference electrode (not shown). System 100 may provide improved or optimized lesion morphology ( size, width, depth and / or shape, or the like), and improved efficiency, e.g., by improving the vectoring of delivery of ablation energy to target tissue to cause an intended effect (formation of a lesion with a target size, width depth, and / or shape) with less ablation energy, such as by not wasting ablation energy on non-target tissue or on target tissue but with a vector that may be relatively less effective.

[0066] As described herein, vectoring of ablation energy includes the aggregate directions of ablation energy delivered to a target tissue at a particular position from one or more electrodes at particular positions, as well as the parameters of the energy delivered from each of those electrodes, e.g., the amount (amplitude), frequency, duty cycle, on-off time, pulsing, or any suitable parameter, and the coordination of delivery of energy between the one or more electrodes. For example, a first electrode may deliver ablation energy to a first area and / or volume of target tissue with a first amplitude and frequency for a portion of time and a second electrode may deliver ablation energy to a portion or all of the first area and / or volume as well as additional area and / or volume of target tissue with a second amplitude and pulse frequency (which may be the same or different from the first) for the same portion of time, or a shorter or longer period of time, simultaneously with the first electrode or with a delay. In some examples, the first and second electrode may deliver the ablation energy for a plurality overlapping or non-overlapping portions of time set a set total time during or until one or more lesion formation criteria are satisfied.

[0067] In the example shown, catheters 102L and 102R are proximate to tissue 340. In other examples, catheters 102L and 102R may be adjacent to tissue 340, e.g., such that one or more electrodes 110 are in contact with tissue 340. In the example shown, electrode HOG of catheter 102L and electrode 110H of catheter 102R deliver ablation energy to form portion 344 of lesion 342 at target tissue of tissue 340 via bipolar RF or PFA. That is, electrode 110G of catheter 102L and electrode 11 OH of catheter 102R may be vectored, by system 100, to form portion 344. If, for example, lesion 342 is intended to also include portion 346, system 100 may determine a new ablation delivery vector and cause electrode 11 OF of catheter 102L to also deliver ablation energy, e.g., to adjust vectoring of ablation energy to deliver multi-polar RF or PFA via both ablation catheters 102R and 102L. If, on the other hand, electrodes 110F and 110G of catheter 102L and electrode 11 OH of catheter 102R deliver ablation energy to form portions 344 and 346 of lesion 342 at target tissue of tissue 340 via bipolar RF or PFA, and lesion 342 is intended to include only portion 344, system 100 may determine a new ablation delivery vector and cause electrode 11 OF of catheter 102L to cease delivering ablation energy (to turn off and / or to deliver a zero amount of ablation energy), e.g., to adjust vectoring of ablation energy to deliver bipolar RF or PFA via both ablation catheters 102R and 102L. Although shown as vectoring using two or three electrodes of two catheters, system 100 may be configured to adjust vectoring of ablationenergy via more or fewer electrodes of more or fewer catheters. Although shown as vectoring using ablation catheters 102L, 102R, system 100 may be configured to vector ablation energy using an external electrode., e.g., an external patch electrode to create a unique and / or adjustable ablation energy vector.

[0068] In the example shown at lesion 352, system 100 may adjust vectoring of ablation energy delivered from a single catheter. For example, electrodes HOC and HOD may deliver ablation energy to tissue 340 to form lesion 352 having a first ablation energy delivery vector. System 100 may adjust the vectoring of the ablation energy by turning off one or both electrodes 110C and 110D, e.g., to reduce the area and / or depth of lesion 352, or to cause additional electrodes of catheter 102R to delivery ablation energy, e.g., to increase the area and / or depth of lesion 352.

[0069] FIG. 3B is a conceptual diagram illustrating contact of one or more ablation energy delivery elements 110 of an ablation catheter 102. FIG. 3B is described with respect to system 100 and catheter 102, and impedance sensors(s) 124 of FIG. 1, and processing circuitry 418 of controller 404 of FIG. 4. However, other devices may be used to determine contact of an ablation energy delivery element 110 and tissue.

[0070] In the example shown, catheter 102 is positioned at a first position relative to tissue 340 of a patient. Catheter 102 may be substantially similar to catheter 102 described above. Tissue 340 may be, or may include, target tissue of the patient. Tissue 340 may be cardiac tissue, renal tissue, airway tissue, organs or tissue within the cardiac space or the pericardial space, or any tissue suitable for delivering ablation energy.

[0071] System 100 including catheter 102 and impedance sensors 124 and / or sensors integrated into the ablation catheters, may be configured to adjust, or allow a physician to adjust based on information from system 100, which electrodes are active and to change the type of ablation energy delivery, e.g., RF ablation energy delivery or PFA energy delivery, based on proximity and / or contact of energy delivery elements 110 with tissue 340.

[0072] In the example shown, each of energy delivery elements 110A-110H are proximate to tissue 340, but only energy delivery elements 110A-110F are in contact with tissue 340. Processing circuitry 418 may cause energy delivery elements 110G and 110H to be deactivated, and cause energy delivery elements 110A-110F to delivery ablation energy via RF ablation energy delivery. Processing circuitry 418 may cause energy delivery elements 110G and 11 OH to be activated and to deliver ablation energy via PFA energydelivery, e.g., before or after causing energy delivery elements 110A-110F to delivery ablation energy. In some examples, processing circuitry 418 may cause all of the proximate energy delivery elements, e.g., energy delivery elements 110A-110H to delivery ablation energy via PFA energy delivery.

[0073] FIG. 4 is a block diagram illustrating an example controller 404 of an ablation system, e.g., system 100 of FIG. 1. Controller 404 of FIG. 4 may be an example of controller 104 of FIG. 1. As shown in FIG. 4, controller 404 includes energy generator 416, processing circuitry 418, user interface 420, storage devices 422, and sensing circuitry 424.

[0074] Energy generator 416 may be configured to provide electrical pulses to energy delivery elements and / or electrodes (e.g., energy delivery elements 110 of FIG. 1) to ablate target tissue of a patient via PFA and / or RF ablation, e.g., cardiac tissue, renal tissue, airway tissue, and organs or tissue within the cardiac space or the pericardial space. For instance, energy generator 416 may be configured and programmed to deliver pulsed, high-voltage electric fields appropriate for achieving desired pulsed, high-voltage ablation (referred to as “pulsed field ablation” or “pulsed electric field ablation”) and / or radiofrequency ablation. While shown in the example of FIG. 4 as a single energy generator, energy generator 416 is not so limited. For instance, controller 404 may include multiple energy generators 416 that are each capable of generating ablation signals in parallel.

[0075] Processing circuitry 418 may include one or more processors, such as any one or more of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), discrete logic circuitry, or any other processing circuitry configured to provide the functions attributed to processing circuitry 418 herein may be embodied as firmware, hardware, software or any combination thereof. Processing circuitry 418 controls energy generator(s) 416 to generate signals according to various settings. In some examples, processing circuitry 418 may execute other instructions stored in storage device 422 to perform PFA and / or RF ablation.

[0076] Sensing circuitry 424 may be configured to receive signals from energy delivery elements 110 and / or one or more sensors to monitor the operating parameters through system 100, such as impedance, temperature, delivered voltage, or the like, andfor measuring and monitoring one or more tissue characteristics, such as EGM waveforms, monophasic action potentials, tissue impedance, or the like.

[0077] Storage device 422 may be configured to store information within controller 404, respectively, during operation. Storage device 422 may include a non-transitory computer-readable storage medium or computer-readable storage device. In some examples, storage device 422 includes one or more of a short-term memory or a long-term memory. Storage device 422 may include, for example, random access memories (RAM), dynamic random access memories (DRAM), static random access memories (SRAM), magnetic discs, optical discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable memories (EEPROM). In some examples, storage device 422 is used to store data indicative of instructions, e.g., for execution by processing circuitry 418, respectively.

[0078] User interface 420 may include a button or keypad, lights, a speaker for voice commands, a display, such as a liquid crystal (LCD), light-emitting diode (LED), or organic light-emitting diode (OLED). In some examples, the display includes a touch screen. User interface 420 may be configured to display any information related to the performance of PF A. User interface 420 may also receive user input (e.g., selection of linear or focal PFA mode) via user interface 420. The user input may be, for example, in the form of pressing a button, such as a pushbutton, pressing a button on a keypad, turning and / or articulating a knob, or selecting an icon from a touch screen.

[0079] Accordingly, although example systems and techniques have been shown and described, it is to be understood that all the terms used herein are descriptive rather than limiting, and that many changes, modifications, and substitutions may be made by one having ordinary skill in the art without departing from the spirit and scope of the invention. The following examples are examples of systems, devices, and methods described herein.

[0080] Example 1 : A method of ablating target tissue of a patient the method including: sensing, by an impedance sensor, a first impedance of the target tissue at a first time; causing, by processing circuitry and before a second time that is after the first time, an energy delivery element of an ablation catheter to deliver a first amount of ablation energy to the target tissue; sensing, by the impedance sensor, a second impedance of the target tissue at the second time; determining, by the processing circuity and based on adifference between the first impedance and the second impedance, a second amount of ablation energy; and causing, by the processing circuitry, the energy delivery element of the ablation catheter to deliver the second amount of ablation energy to the target tissue at a third time that is after the second time.

[0081] Example 2: The method of example 1, wherein the first impedance is indicative of at least one of contact between the energy delivery element and the target tissue or proximity between the energy delivery element and the target tissue.

[0082] Example 3 : The method of example 2, further including: determining, by the processing circuitry and based on the first impedance, that the energy delivery element is proximate to the target tissue, wherein causing the energy delivery element to deliver the first amount of ablation energy to the target tissue comprises causing, based on determining that the energy delivery element is proximate to the target tissue, the energy delivery element to deliver the first amount of ablation energy via pulsed field ablation (PFA).

[0083] Example 4: The method of any of examples 2 and 3, further including: determining, by the processing circuitry and based on the first impedance, that the energy delivery element is in contact with the target tissue, wherein causing the energy delivery element to deliver the first amount of ablation energy to the target tissue comprises causing, based on determining that the energy delivery element is proximate to the target tissue, the energy delivery element to deliver the first amount of ablation energy via PFA or radiofrequency (RF) ablation.

[0084] Example 5: The method of any one of examples 1-4, further including: determining, by the processing circuitry and based on the first impedance, that the target tissue is abnormal tissue; and responsive to determining that the target tissue is abnormal tissue, determining, by the processing circuitry, the first amount of ablation energy delivered by the energy delivery element to be a first abnormal tissue amount different from a first normal tissue amount.

[0085] Example 6: The method of any one of examples 1-4, further including: determining, by the processing circuitry and based on the first impedance, that the target tissue is not abnormal tissue; and responsive to determining that the target tissue is not abnormal tissue, determining, by the processing circuitry, the amount of ablation energydelivered by the energy delivery element to be a first normal tissue amount different from a first abnormal tissue amount.

[0086] Example 7: The method of any one of examples 1-6, wherein the second impedance is less than the first impedance, wherein an absolute difference between the first impedance and the second impedance is equal to or greater than a threshold amount, the method further including: determining, by the processing circuitry and based on an ablation marker, that the target tissue includes a lesion satisfying target lesion criteria; and wherein the second amount of ablation energy is a zero amount.

[0087] Example 8: The method of example 7, wherein the threshold amount is at least one of 10 percent or 10 Ohms.

[0088] Example 9: The method of any one of examples 1-6, wherein the second impedance is less than the first impedance, wherein an absolute difference between the first impedance and the second impedance is less than a threshold amount, the method further including: sensing, by the impedance sensor, a third impedance of the target tissue at a fourth time; determining, by the processing circuitry, that the third impedance is less than the first impedance, wherein an absolute difference between the first impedance and the third impedance is greater than or equal to a threshold amount; determining, by the processing circuitry and based on an ablation marker, that the target tissue includes a lesion satisfying target lesion criteria; and generating, by the processing circuitry, a notification that the target tissue includes a lesion satisfying the target lesion criteria.

[0089] Example 10: The method of any one of examples 1-6, wherein the second impedance is equal to or greater than the first impedance, the method further including: initiating, by the processing circuitry and responsive to determining that the second impedance is equal to or greater than the first impedance, an adjustment of a position of the ablation catheter; causing, by the processing circuitry, the energy delivery element of the ablation catheter to deliver the first amount of ablation energy to the target tissue after the adjustment; and sensing, by the impedance sensor, a fourth impedance of the target tissue.

[0090] Example 11 : The method of example 10, wherein if the fourth impedance is less than the first impedance, the method further including: determining, by the processing circuitry and based on a difference between the first impedance and the fourth impedance, the second amount of ablation energy delivered by the energy delivery element.

[0091] Example 12: The method of any of examples 10 and 11, wherein the energy delivery element is a first energy delivery element, wherein if the fourth impedance is greater than or equal to the first impedance, the method further including: causing, by the processing circuitry, a second energy delivery element of the ablation catheter to deliver ablation energy to the target tissue; and sensing, by the impedance sensor, a fifth impedance of the target tissue.

[0092] Example 13: The method of example 12, wherein if the fifth impedance is less than the first impedance, the method further includes determining, by the processing circuitry and based on a difference between the first impedance and the fifth impedance, the second amount of ablation energy delivered by the energy delivery element.

[0093] Example 14: The method of any of examples 12 and 13, wherein the ablation catheter is a first ablation catheter, wherein if the fifth impedance is greater than or equal to the first impedance, the method further including: causing, by the processing circuitry, an energy delivery element of a second ablation catheter to deliver ablation energy to the target tissue; and sensing, by the impedance sensor, a sixth impedance of the target tissue.

[0094] Example 15: The method of example 14, wherein if the sixth impedance is less than the first impedance, the method further including: determining, by the processing circuitry and based on a difference between the first impedance and the sixth impedance, the second amount of ablation energy delivered by the energy delivery element.

[0095] Example 16: The method of any of examples 14 and 15, wherein if the sixth impedance is greater than or equal to the first impedance, the method further including: determining, by the processing circuitry, the second amount of ablation energy is a zero amount.

[0096] Example 17: A system including: an ablation catheter including an ablation energy delivery element; a processor; and a memory in communication with the processor and storing instructions that, when executed by the processor, cause the processor to: cause an impedance sensor to sense a first impedance of a target tissue of a patient at a first time; cause an energy delivery element of the ablation catheter to deliver a first amount of ablation energy to the target tissue; cause the impedance sensor to sense a second impedance of the target tissue at a second time; determine, based on a difference between the first impedance and the second impedance, a second amount of ablationenergy; and cause the energy delivery element of the ablation catheter to deliver the second amount of ablation energy to the target tissue at a third time.

[0097] Example 18: The system of example 17, wherein the first impedance is indicative of at least one of contact between the energy delivery element and the target tissue or proximity between the energy delivery element and the target tissue.

[0098] Example 19: The system of example 18, the memory storing instructions that, when executed by the processor, further cause the processor to: determine, based on the first impedance, that the energy delivery element is proximate to the target tissue; and cause, based on determining that the energy delivery element is proximate to the target tissue, the energy delivery element to deliver the first amount of ablation energy via pulsed field ablation (PF A).

[0099] Example 20: The system of any of examples 18 and 19, the memory storing instructions that, when executed by the processor, further cause the processor to: determine, based on the first impedance, that the energy delivery element is in contact with the target tissue, cause, based on determining that the energy delivery element is proximate to the target tissue, the energy delivery element to deliver the first amount of ablation energy via PFA or radiofrequency (RF) ablation.

[0100] Example 21 : The system of any one of examples 17-20, the memory storing instructions that, when executed by the processor, further cause the processor to determine, based on the first impedance, that the target tissue is abnormal tissue; and determine the amount of ablation energy delivered by the energy delivery element to be the first amount based on the target tissue being abnormal.

[0101] Example 22: The system of any one of examples 17-20, the memory storing instructions that, when executed by the processor, further cause the processor to: determine, based on the first impedance, that the target tissue is not abnormal tissue; and determine the amount of ablation energy delivered by the energy delivery element to be the second amount based on the target tissue not being abnormal.

[0102] Example 23: The system of any one of examples 17-22, wherein the second impedance is less than the first impedance, wherein an absolute difference between the first impedance and the second impedance is equal to or greater than a threshold amount, the memory storing instructions that, when executed by the processor, further cause the processor to: determine, based on an ablation marker, that the target tissue includes alesion satisfying target lesion criteria; and wherein the second amount of ablation energy is a zero amount.

[0103] Example 24: The system of example 23, wherein the threshold amount is at least one of 10 percent or 10 Ohms.

[0104] Example 25: The system of any one of examples 17-22, wherein the second impedance is less than the first impedance, wherein an absolute difference between the first impedance and the second impedance is less than a threshold amount, the memory storing instructions that, when executed by the processor, further cause the processor to cause the impedance sensor to sense a third impedance of the target tissue; determine that the third impedance is less than the first impedance, wherein an absolute difference between the first impedance and the third impedance is greater than or equal to a threshold amount; determine, based on an ablation marker, that the target tissue includes a lesion satisfying target lesion criteria; and generate a notification that the target tissue includes a lesion satisfying the target lesion criteria.

[0105] Example 26: The system of any one of examples 17-22, wherein the second impedance is equal to or greater than the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to: initiate, responsive to determining that the second impedance is equal to or greater than the first impedance, an adjustment of a position of the ablation catheter; cause the energy delivery element of the ablation catheter to deliver the first amount of ablation energy to the target tissue after the adjustment; and cause the impedance sensor to sense a fourth impedance of the target tissue.

[0106] Example 27: The system of example 26, wherein if the fourth impedance is less than the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to: determine, based on a difference between the first impedance and the fourth impedance, the second amount of ablation energy delivered by the energy delivery element.

[0107] Example 28: The system of any of examples 26 and 27, wherein the energy delivery element is a first energy delivery element, wherein if the fourth impedance is greater than or equal to the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to: cause a second energy deliveryelement of the ablation catheter to deliver ablation energy to the target tissue; and cause the impedance sensor to sense a fifth impedance of the target tissue.

[0108] Example 29: The system of example 28, wherein if the fifth impedance is less than the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to perform the steps of: determine, based on a difference between the first impedance and the fifth impedance, the second amount of ablation energy delivered by the energy delivery element.

[0109] Example 30: The system of any of examples 28 and 29, wherein the ablation catheter is a first ablation catheter, wherein if the fifth impedance is greater than or equal to the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to perform the steps of: cause an energy delivery element of a second ablation catheter to deliver ablation energy to the target tissue; and cause the impedance sensor to sense a sixth impedance of the target tissue.

[0110] Example 31 : The system of example 30, wherein if the sixth impedance is less than the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to perform the steps of: determine, based on a difference between the first impedance and the sixth impedance, the second amount of ablation energy delivered by the energy delivery element.

[0111] Example 32: The system of any of examples 30 and 31, wherein if the sixth impedance is greater than or equal to the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to perform the steps of: determine the second amount of ablation energy is a zero amount.

[0112] Example 33 : A computer readable medium including instructions that, when executed by one or more processors, cause the one or more processors to: cause an impedance sensor to sense a first impedance of a target tissue at a first time; cause an energy delivery element of an ablation catheter to deliver a first amount of ablation energy to the target tissue; cause the impedance sensor to sense a second impedance of the target tissue at a second time; determine, based on a difference between the first impedance and the second impedance, a second amount of ablation energy; and cause the energy delivery element of the ablation catheter to deliver the second amount of ablation energy to the target tissue at a third time.

[0113] Example 34: The computer readable medium of example 33, wherein the first impedance is indicative of at least one of contact between the energy delivery element and the target tissue or proximity between the energy delivery element and the target tissue.

[0114] Example 35: The computer readable medium of example 34, further including instructions that, when executed by one or more processors, cause one or more processors to: determine, based on the first impedance, that the energy delivery element is proximate to the target tissue; and cause, based on determining that the energy delivery element is proximate to the target tissue, the energy delivery element to deliver the first amount of ablation energy via pulsed field ablation (PF A).

[0115] Example 36: The computer readable medium of any of examples 34 and 35, further including instructions that, when executed by one or more processors, cause one or more processors to: determine, based on the first impedance, that the energy delivery element is in contact with the target tissue; and cause, based on determining that the energy delivery element is proximate to the target tissue, the energy delivery element to deliver the first amount of ablation energy via PFA or radiofrequency (RF) ablation.

[0116] Example 37: The computer readable medium of any one of examples 33-36, further including instructions that, when executed by one or more processors, cause one or more processors to: determine, based on the first impedance, that the target tissue is abnormal tissue; and determine the amount of ablation energy delivered by the energy delivery element to be the first amount based on the target tissue being abnormal.

[0117] Example 38: The computer readable medium of any one of examples 33-36, further including instructions that, when executed by one or more processors, cause one or more processors to: determine, based on the first impedance, that the target tissue is not abnormal tissue; and determine the amount of ablation energy delivered by the energy delivery element to be the second amount based on the target tissue not being abnormal.

[0118] Example 39: The computer readable medium of any one of examples 33-38, wherein the second impedance is less than the first impedance, wherein an absolute difference between the first impedance and the second impedance is equal to or greater than a threshold amount, the computer readable medium further including instructions that, when executed by one or more processors, cause one or more processors to: determine, based on an ablation marker, that the target tissue includes a lesion satisfying target lesion criteria; and wherein the second amount of ablation energy is a zero amount.

[0119] Example 40: The computer readable medium of example 39, wherein the threshold amount is at least one of 10 percent or 10 Ohms.

[0120] Example 41 : The computer readable medium of any one of examples 33-38, wherein the second impedance is less than the first impedance, wherein an absolute difference between the first impedance and the second impedance is less than a threshold amount, the computer readable medium further including instructions that, when executed by one or more processors, cause one or more processors to: cause the impedance sensor to sense a third impedance of the target tissue; determine that the third impedance is less than the first impedance, wherein an absolute difference between the first impedance and the third impedance is greater than or equal to a threshold amount; determine, based on an ablation marker, that the target tissue includes a lesion satisfying target lesion criteria; and generate a notification that the target tissue includes a lesion satisfying the target lesion criteria.

[0121] Example 42: The computer readable medium of any one of examples 33-38, wherein the second impedance is equal to or greater than the first impedance, the computer readable medium further including instructions that, when executed by one or more processors, cause one or more processors to: initiate, responsive to determining that the second impedance is equal to or greater than the first impedance, an adjustment of a position of the ablation catheter; cause the energy delivery element of the ablation catheter to deliver the first amount of ablation energy to the target tissue after the adjustment; and cause the impedance sensor to sense a fourth impedance of the target tissue.

[0122] Example 43 : The computer readable medium of example 42, wherein if the fourth impedance is less than the first impedance, the computer readable medium further including instructions that, when executed by one or more processors, cause one or more processors to: determine, based on a difference between the first impedance and the fourth impedance, the second amount of ablation energy delivered by the energy delivery element.

[0123] Example 44: The computer readable medium of any of examples 42 and 43, wherein the energy delivery element is a first energy delivery element, wherein if the fourth impedance is greater than or equal to the first impedance, the computer readable medium further including instructions that, when executed by one or more processors, cause one or more processors to: cause a second energy delivery element of the ablationcatheter to deliver ablation energy to the target tissue; and cause the impedance sensor to sense a fifth impedance of the target tissue.

[0124] Example 45: The computer readable medium of example 44, wherein if the fifth impedance is less than the first impedance, the computer readable medium further including instructions that, when executed by one or more processors, cause one or more processors to: determine, based on a difference between the first impedance and the fifth impedance, the second amount of ablation energy delivered by the energy delivery element.

[0125] Example 46: The computer readable medium of any of examples 44 and 45, wherein the ablation catheter is a first ablation catheter, wherein if the fifth impedance is greater than or equal to the first impedance, the computer readable medium further including instructions that, when executed by one or more processors, cause one or more processors to: cause an energy delivery element of a second ablation catheter to deliver ablation energy to the target tissue; and cause the impedance sensor to sense a sixth impedance of the target tissue.

[0126] Example 47: The computer readable medium of example 46, wherein if the sixth impedance is less than the first impedance, the computer readable medium further including instructions that, when executed by one or more processors, cause one or more processors to: determine, based on a difference between the first impedance and the sixth impedance, the second amount of ablation energy delivered by the energy delivery element.

[0127] Example 48: The computer readable medium of any of examples 46 and 47, wherein if the sixth impedance is greater than or equal to the first impedance, the computer readable medium further including instructions that, when executed by one or more processors, cause one or more processors to: determine the second amount of ablation energy is a zero amount.

[0128] Example 49: The computer readable medium of any one of examples 33-48, the computer readable medium further comprising instructions that, when executed by one or more processors, cause one or more processors to: determine, based on a rate of change from the first impedance to the second impedance, the second amount of ablation energy.

[0129] The techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware or any combination thereof. For example, variousaspects of the described techniques may be implemented within processing circuitry, which may include one or more processors, including one or more microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components. The term “processor” or “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry. A control unit including hardware may also form one or more processors or processing circuitry configured to perform one or more of the techniques of this disclosure.

[0130] Such hardware, software, and firmware may be implemented, and various operation may be performed within same device, within separate devices, and / or on a coordinated basis within, among or across several devices, to support the various operations and functions described in this disclosure. In addition, any of the described units, circuits or components may be implemented together or separately as discrete but interoperable logic devices. Depiction of different features as circuits or units is intended to highlight different functional aspects and does not necessarily imply that such circuits or units must be realized by separate hardware or software components. Rather, functionality associated with one or more circuits or units may be performed by separate hardware or software components or integrated within common or separate hardware or software components. Processing circuitry described in this disclosure, including a processor or multiple processors, may be implemented, in various examples, as fixed-function circuits, programmable circuits, or a combination thereof. Fixed-function circuits refer to circuits that provide particular functionality with preset operations. Programmable circuits refer to circuits that can be programmed to perform various tasks and provide flexible functionality in the operations that can be performed. For instance, programmable circuits may execute software or firmware that cause the programmable circuits to operate in the manner defined by instructions of the software or firmware. Fixed-function circuits may execute software instructions (e.g., to receive stimulation parameters or output stimulation parameters), but the types of operations that the fixed-function circuits perform are generally immutable. In some examples, one or more of the units may be distinct circuit blocks (fixed-function or programmable), and in some examples, one or more of the units may be integrated circuits.

[0131] The techniques described in this disclosure may also be embodied or encoded in a computer-readable medium, such as a computer-readable storage medium, containing instructions that may be described as non-transitory media. Instructions embedded or encoded in a computer-readable storage medium may cause a programmable processor, or other processor, to perform the method, e.g., when the instructions are executed. Computer readable storage media may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a CD-ROM, a floppy disk, a cassette, magnetic media, optical media, or other computer readable media.

Claims

WHAT IS CLAIMED IS:

1. A system comprising:an ablation catheter comprising an ablation energy delivery element;a processor; anda memory in communication with the processor and storing instructions that, when executed by the processor, cause the processor to:cause an impedance sensor to sense a first impedance of a target tissue of a patient at a first time;cause an energy delivery element of the ablation catheter to deliver a first amount of ablation energy to the target tissue;cause the impedance sensor to sense a second impedance of the target tissue at a second time;determine, based on a difference between the first impedance and the second impedance, a second amount of ablation energy; andcause the energy delivery element of the ablation catheter to deliver the second amount of ablation energy to the target tissue at a third time.

2. The system of claim 1, wherein the first impedance is indicative of at least one of contact between the energy delivery element and the target tissue or proximity between the energy delivery element and the target tissue.

3. The system of claim 2, the memory storing instructions that, when executed by the processor, further cause the processor to:determine, based on the first impedance, that the energy delivery element is proximate to the target tissue; andcause, based on determining that the energy delivery element is proximate to the target tissue, the energy delivery element to deliver the first amount of ablation energy via pulsed field ablation (PF A).

4. The system of claim 2, the memory storing instructions that, when executed by the processor, further cause the processor to:determine, based on the first impedance, that the energy delivery element is in contact with the target tissue,cause, based on determining that the energy delivery element is proximate to the target tissue, the energy delivery element to deliver the first amount of ablation energy via PFA or radiofrequency (RF) ablation.

5. The system of any one of claims 1-4, the memory storing instructions that, when executed by the processor, further cause the processor todetermine, based on the first impedance, that the target tissue is abnormal tissue; anddetermine the amount of ablation energy delivered by the energy delivery element to be the first amount based on the target tissue being abnormal.

6. The system of any one of claims 1-5, the memory storing instructions that, when executed by the processor, further cause the processor to:determine, based on the first impedance, that the target tissue is not abnormal tissue; anddetermine the amount of ablation energy delivered by the energy delivery element to be the second amount based on the target tissue not being abnormal.

7. The system of any one of claims 1-6, wherein the second impedance is less than the first impedance, wherein an absolute difference between the first impedance and the second impedance is equal to or greater than a threshold amount, the memory storing instructions that, when executed by the processor, further cause the processor to:determine, based on an ablation marker, that the target tissue includes a lesion satisfying target lesion criteria,wherein the second amount of ablation energy is a zero amount, and wherein the threshold amount is at least one of 10 percent or 10 Ohms.

8. The system of any one of claims 1-7, wherein the second impedance is less than the first impedance, wherein an absolute difference between the first impedance and thesecond impedance is less than a threshold amount, the memory storing instructions that, when executed by the processor, further cause the processor tocause the impedance sensor to sense a third impedance of the target tissue; determine that the third impedance is less than the first impedance, wherein an absolute difference between the first impedance and the third impedance is greater than or equal to a threshold amount;determine, based on an ablation marker, that the target tissue includes a lesion satisfying target lesion criteria; andgenerate a notification that the target tissue includes a lesion satisfying the target lesion criteria.

9. The system of any one of claims 1-8, wherein the second impedance is equal to or greater than the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to:initiate, responsive to determining that the second impedance is equal to or greater than the first impedance, an adjustment of a position of the ablation catheter;cause the energy delivery element of the ablation catheter to deliver the first amount of ablation energy to the target tissue after the adjustment; andcause the impedance sensor to sense a fourth impedance of the target tissue.

10. The system of claim 9, wherein if the fourth impedance is less than the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to:determine, based on a difference between the first impedance and the fourth impedance, the second amount of ablation energy delivered by the energy delivery element.

11. The system of claim 9, wherein the energy delivery element is a first energy delivery element, wherein if the fourth impedance is greater than or equal to the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to:cause a second energy delivery element of the ablation catheter to deliver ablation energy to the target tissue; andcause the impedance sensor to sense a fifth impedance of the target tissue.

12. The system of claim 11, wherein if the fifth impedance is less than the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to perform the steps of:determine, based on a difference between the first impedance and the fifth impedance, the second amount of ablation energy delivered by the energy delivery element.

13. The system of claim 11, wherein the ablation catheter is a first ablation catheter, wherein if the fifth impedance is greater than or equal to the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to perform the steps of:cause an energy delivery element of a second ablation catheter to deliver ablation energy to the target tissue; andcause the impedance sensor to sense a sixth impedance of the target tissue.

14. The system of claim 13, wherein if the sixth impedance is less than the first impedance, the memory storing instructions that, when executed by the processor, further cause the processor to perform the steps of:determine, based on a difference between the first impedance and the sixth impedance, the second amount of ablation energy delivered by the energy delivery element.

15. A computer readable medium comprising instructions that, when executed by one or more processors, cause the one or more processors to:cause an impedance sensor to sense a first impedance of a target tissue at a first time;cause an energy delivery element of an ablation catheter to deliver a first amount of ablation energy to the target tissue;cause the impedance sensor to sense a second impedance of the target tissue at a second time;determine, based on a difference between the first impedance and the second impedance, a second amount of ablation energy; andcause the energy delivery element of the ablation catheter to deliver the second amount of ablation energy to the target tissue at a third time.

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