Patent Publication Number: US-2021177509-A1

Title: Tissue mapping and treatment

Description:
INCORPORATION BY REFERENCE 
     The present application is a continuation-in-part of U.S. application Ser. No. 15/396,309, filed Dec. 30, 2016, entitled TISSUE MAPPING AND TREATMENT, which claims priority benefit to U.S. Prov. App. No. 62/273,268, filed Dec. 30, 2015, entitled PHRENIC NERVE LOCATION AND INJURY PREVENTION. The present application also claims priority benefit to U.S. Prov. App. No. 62/947,471, filed Dec. 12, 2019, entitled TISSUE MAPPING AND TREATMENT, all of which are incorporated herein in their entireties. 
    
    
     BACKGROUND 
     In many medical procedures, catheters are used to treat tissue. In some procedures, it may be valuable to map the location of certain extravascular structures, to potentially influence the execution of the index procedure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating an embodiment of a treatment system. 
         FIG. 2  is a diagram illustrating an embodiment of a mapping system. 
         FIG. 3  is a diagram illustrating an embodiment of a cryoablation treatment system. 
         FIG. 4A  is a diagram illustrating an embodiment of a mapping device of an intravenous catheter is positioned within the right superior pulmonary vein. 
         FIG. 4B  is a diagram illustrating an embodiment of a treatment device positioned within the right superior pulmonary vein. 
         FIGS. 5A, 5B, 5C, 5D  are diagrams illustrating embodiments of a complementary mapping device and treatment device in different configurations and positions 
         FIG. 6  is a diagram illustrative of an embodiment of a complementary mapping device and treatment device positioned within the right superior pulmonary vein. 
         FIG. 7  is a flow diagram illustrating an embodiment of a routine for treating cardiac arrhythmia. 
         FIG. 8  is a flow diagrams illustrating an embodiment of a routine for treating a tissue site 
         FIGS. 9, 10A and 10B  are diagrams illustrating embodiments of treatment elements that include multiple segments. 
         FIGS. 11 and 12  are diagrams illustrating embodiments of a treatment device that includes one or more sensor/electrodes. 
         FIG. 13  is a diagram illustrative of an embodiment of a treatment device positioned within the right superior pulmonary vein. 
         FIG. 14  is a flow diagram illustrating an embodiment of a routine for treating a tissue site. 
         FIGS. 15A-15D  are diagrams illustrative of a mapping overlay. 
         FIGS. 16A-16C  are diagrams illustrating embodiments of a mapping overlay and a treatment device in different configurations and positions. 
         FIGS. 17A-17B  show coaxial introduction of a treatment catheter into the basket of a mapping catheter. 
         FIGS. 18A-18C  show coaxial introduction as in  FIGS. 17B-17B , into a basket having a circumferential wire spacing stabilizing feature. 
         FIGS. 19A-19B  show parallel introduction of the mapping catheter and the treatment catheter, with the treatment element entering the mapping catheter cavity through the wire mesh side wall. 
         FIGS. 20A-20B  illustrate filament braid patterns. 
         FIG. 21  shows a cryo balloon inside of a mapping array, with an ice ball. 
         FIGS. 22-26  show electrograms from mapping devices in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     During medical procedures using catheters, it can be difficult to identify tissue proximate to the catheter. Furthermore, in some cases, when the tissue is being treated it can be difficult to monitor the effects of the treatment on tissue proximate the tissue that is to be treated. A method and device described herein can be used as part of or in conjunction with a treatment device to map tissue at or near a target site and monitor the tissue at or near the target site during treatment. In same embodiments, the device can be used in conjunction with a treatment device used to treat cardiac arrhythmia. However, it will be understood that the methods and device described herein can be used with many types of treatment devices. 
     Cardiac Arrhythmia 
     Cardiac arrhythmia, a condition in which the heart&#39;s normal rhythm is disrupted, includes many different forms. For example, cardiac arrhythmia includes premature atrial contractions (PACs), atrial flutter, accessory pathway tachycardias, atrial fibrillation, atrioventricular (AV) nodal reentrant tachycardia (AVNRT), premature ventricular contractions (PVCs), ventricular tachycardia (VT), ventricular fibrillation, long QT syndrome, and bradyarrhythmias. 
     Certain types of cardiac arrhythmias, including atrial fibrillation (AF), may be treated by ablation (for example, radiofrequency (RF) ablation, cryoablation, ultrasound ablation, laser ablation, and the like), either endocardially or epicardially. 
     As mentioned above, one method of ablating tissue of the heart and pulmonary veins to control atrial fibrillation includes delivering radiofrequency (RF) energy to the tissue to be ablated. In particular, high frequency energy can be employed, for example, to cause ionic agitation and frictional heat in targeted tissue, causing permanent damage to the tissue. Once damaged, the tissue may no longer propagate or source electrical signals, and the fibrillation may be treated or reduced. The RF energy can be delivered by an RF catheter having an RF source at a distal treatment end that is positioned at a target site inside a patient during a treatment procedure. 
     Another method of ablating tissue of the heart and pulmonary veins to control atrial fibrillation is through cryotherapy, or the extreme cooling of body tissue. Cryotherapy may also cause permanent alteration to treated tissue, preventing the treated tissue from propagating or sourcing electrical signals, thereby reducing or eliminating atrial fibrillation. Cryotherapy may be delivered to appropriate target sites inside a patient&#39;s heart and circulatory system by a cryotherapy catheter. A cryotherapy catheter can include a treatment member at its distal end, such as an expandable balloon having a cooling chamber inside. A cryotherapy agent can be provided by a source external to the patient at the proximal end of the cryotherapy catheter and delivered distally through a lumen in an elongate member to the cooling chamber where it is released. Release of the cryotherapy agent into the chamber cools the chamber, the balloon&#39;s outer surface, and tissue that is in contact with the outer surface, to perform ablation. The cryotherapy agent may be exhausted proximally through an exhaust lumen in the elongate member to a reservoir external to the patient. 
     Furthermore, in the case of cryoballoon ablation, the distal hemisphere of the balloon contacts the pulmonary vein antrum in an occlusive manner. Tissue in contact with distal hemisphere of the cryoballoon will be ablated as liquid N2O evaporates in the distal balloon. As the tissues freezes, a shell of ice forms around the balloon and penetrates full thickness through the wall of the pulmonary vein antrum reaching extracardiac tissues. This can include non-targeted tissues such as the phrenic nerve, esophagus and vagus nerve. The same non-targeted tissues can also be damaged by other balloon directed therapies including but not limited to radiofrequency hot balloon, high frequency ultrasound balloon and laser balloon. 
     Phrenic Nerve Injury 
     One possible complication of an ablation procedure is damage to the phrenic nerves, which are involved in breathing and both receive and transmit nerve signals to the diaphragm. Phrenic nerve injury (PNI) can cause dyspnea, cough, hiccup, and/or sudden diaphragmatic elevation. The majority of patients with PNI recover over time, such as within days or months, but PNI may be persistent in a minority of patients. 
     The main function of the phrenic nerves is to control breathing by acting on the diaphragm. As such, it is possible to monitor phrenic nerve viability by stimulating the phrenic nerves electrically and detecting the corresponding physiologic response. Means for detecting physiologic response may include electromyography (the detection of electromyograms such as compound motor action potentials, or electrical potential generated by muscle cells when the cells are electrically or neurologically activated), mechanomyography (the detection of mechanomyograms, or mechanical signals observable from the surface of a muscle when the muscle is contracted), and kinemyography (the detection of electrical currents generated after deformation of a mechanosensor), auditory cardiotocography (detection of sound waves created by the diaphragmatic contraction). One can also directly observe the diaphragmatic movement fluoroscopically in a spontaneously breathing patient. Pacing of the nerve and palpation of the intensity of the diaphragmatic contraction can also be used to monitor the function of the nerve if the pacing source is positioned distal to the ablation source in the case of balloon cryoablation. 
     In some embodiments, to avoid phrenic nerve injury (PNI), the electrical activity of a pulmonary vein (or other target site) can be mapped prior to permanent ablation by either RF, high-frequency ultrasound (HIFU), laser, hot balloon, and/or cryotherapy, in order to pinpoint appropriate ablation target sites. Some apparent target sites may have non-targeted tissues such as the phrenic nerve or esophagus in close proximity and ablation at those sites may cause collateral damage such as injury to the phrenic nerve as the ablation penetrates deeper into the tissues. Treating other target sites may affect healthy tissue in undesirable ways (e.g., creating conduction blocks). Precisely mapping the electrical activity in a target treatment region can help focus the treatment and confirm its efficacy and safety. 
     Mapping Catheter 
     Various specialized mapping catheters may be employed to electrically map tissue, such as a circular catheter or a multi-electrode basket catheter. As a non-limiting example, in some embodiments, the Constellation catheter, available from Boston Scientific, can be used to electrically map tissue. 
     Such mapping catheters can be positioned at possible target sites inside a patient, and electrodes at those sites can provide signals to a processing system external to the patient that can process the signals and provide physicians with information to subsequently position a separate RF, HIFU, laser, hot balloon, or cryotherapy catheter and deliver with that separate catheter appropriately targeted ablation energy. In some cases, the mapping catheters can be used to pace and map the phrenic nerve as well. 
     With reference to  FIG. 1  below, system  10  can include a mapping catheter  14  and an ablation catheter  16 . Each probe  14 / 16  can be separately introduced into target region  12  through a vein or artery (e.g., the femoral vein or artery) using a suitable percutaneous access technique. Alternatively, mapping catheter  14  and ablation catheter  16  can be assembled in an integrated structure for simultaneous introduction and deployment in target region  12 . However, it will be understood that in some embodiments, the system  10  can omit the ablation catheter  16 . 
     Mapping catheter  14  can include a catheter shaft  18 . The distal end of the catheter shaft  18  can include mapping device  20 , which can include a three-dimensional multiple electrode structure  20 . Mapping device  20  can take the form of a basket having a plurality of struts  22  (see  FIG. 2 ), although other multiple electrode structures could be used. A plurality of mapping electrodes  24  (not explicitly shown on  FIG. 1 , but shown on  FIG. 2 ) can be disposed along struts  22 . Each electrode  24  can be configured to sense intrinsic physiological activity in the anatomical region. In some embodiments, electrodes  24  can be configured to detect activation signals of the intrinsic physiological activity within the anatomical structure (e.g., the activation times of cardiac activity). 
     Electrodes  24  can be electrically coupled to a processing system  32 . A signal wire (not shown) can be electrically coupled to each electrode  24  on mapping device  20 . The wires can extend through shaft  18  and electrically couple each electrode  24  to an input of processing system  32 . Electrodes  24  can sense electrical activity in the anatomical region (e.g., myocardial tissue). The sensed activity (e.g., activation signals) can be processed by processing system  32 , which can assist the physician by generating an electrical activity map (e.g., a vector field map, an activation time map, etc.) to identify the site or sites within the heart appropriate for a diagnostic and/or treatment procedure. For example, processing system  32  can identify a near-field signal component (e.g., activation signals originating from cellular tissue adjacent to the mapping electrode  24 ) or from an obstructive far-field signal component (e.g., activation signals originating from non-adjacent tissue). The near-field signal component can include activation signals originating from atrial myocardial tissue whereas the far-field signal component can include activation signals originating from ventricular myocardial tissue. The near-field activation signal component can be further analyzed to find the presence of a pathology and to determine a location suitable for ablation for treatment of the pathology (e.g., ablation therapy). 
     Processing system  32  can include dedicated circuitry (e.g., discrete logic elements and one or more microcontrollers; a memory or one or more memory units, application-specific integrated circuits (ASICs); and/or specially configured programmable devices, such as, for example, programmable logic devices (PLDs) or field programmable gate arrays (FPGAs) for receiving and/or processing the acquired activation signals. In at least some embodiments, processing system  32  includes a general-purpose microprocessor and/or a specialized microprocessor (e.g., a digital signal processor, or DSP, which can be optimized for processing activation signals) that executes instructions to receive, analyze and display information associated with the received activation signals. In such implementations, processing system  32  can include program instructions, which when executed, perform part of the signal processing. Program instructions can include, for example, firmware, microcode or application code that is executed by microprocessors or microcontrollers. The above-mentioned implementations are merely exemplary. A variety of processing systems  32  are contemplated. 
     In some embodiments, processing system  32  can be configured to measure the electrical activity in the myocardial tissue adjacent to electrodes  24 . For example, in some embodiments, processing system  32  can be configured to detect electrical activity associated with a dominant rotor or divergent activation pattern in the anatomical feature being mapped. Dominant rotors and/or divergent activation patterns can have a role in the initiation and maintenance of atrial fibrillation, and ablation of the rotor path, rotor core, and/or divergent foci can be effective in terminating the atrial fibrillation. In either situation, processing system  32  processes the sensed activation signals to generate a display of relevant characteristics, such as an isochronal map, activation time map, action potential duration (APD) map, a vector field map, a contour map, a reliability map, an electrogram, a cardiac action potential, and/or the like. The relevant characteristics can be used by the physician to identify a site suitable for ablation therapy. 
     Additionally, the electrodes  24  of the mapping catheter  14  can be used to pace and map the phrenic nerve. For example, one or more of the electrodes  24  can be activated. If the activated electrode  24  is within a threshold distance of the phrenic nerve it can activate it. In some cases, when paced, the phrenic nerve can cause the diaphragm to contract. Furthermore, as the proximity between the activated electrode and phrenic nerve increases, the strength of the contraction of the diaphragm can increase. Based on which electrodes  24  pace the phrenic nerve, all or portions of the phrenic nerve can be located. In some cases, to locate the phrenic nerve, the electrodes  24  can be activated (sequentially or otherwise) along a tine and/or in a circumference on the different tines. In certain embodiments when mapping in a circumference, once one circumference of electrodes is activated  24  a next circumference of electrodes can be activated (e.g., sequentially or otherwise). The next circumference can either be distal or proximal to the atrium with respect to the previous circumference (e.g., the activated circumference can move proximal-to-distal or vice versa). 
     In some embodiments, the portion of the phrenic nerve that is proximal (in some embodiments, the most proximal) to the atrium can be identified. In some cases, the determined location of the phrenic nerve (or portions thereof) can be displayed on a corresponding display. As will be described in greater detail below, in some embodiments, the placement of the mapping catheter  14  and mapping of the phrenic nerve can be based at least in part on an anatomical cycle, such as a respiration or cardiac cycle. 
     Treatment Catheter 
     Once the phrenic nerve has been mapped, a treatment device, can be used to treat the patient. In some cases, the treatment device can form part of the mapping catheter, can be placed in the patient while the mapping catheter is still present (e.g., can fit within the lumen of the mapping catheter or vice versa), and/or can be a device that requires removal of the mapping catheter before insertion. One embodiment of a treatment device is the Artic Front Advance Cardiac Cryoablation Catheter, which is commercially available from Medtronic, and can be used to ablate the tissue. 
     With reference to  FIG. 3  below, the treatment device  312  can be a catheter with ablation, mapping, and/or audio sensing capabilities, and can have a longitudinal axis  329 . The treatment device  312  can additionally include pacing capabilities. As a non-limiting example, the treatment device  312  can generally include a handle  316 , an elongate body  318  having a distal portion  320  and a proximal portion  322 , one or more recording electrodes  324  for detecting electrophysiological signals, one or more treatment elements  326  for ablating or thermally treating tissue, and/or one or more audio sensors  327  for recording sounds generated from the thoracic region of the patient&#39;s body (for example, audio signals from the heart and/or diaphragm). 
     In some embodiments, the one or more recoding electrodes  324  and pacing electrodes  328  can be included on an electrophysiology catheter  330 . The electrophysiology catheter  330  can be can be used as a component of the treatment device  312  (as shown in  FIG. 3 ) or as an independent device. Likewise, the one or more audio sensors  327  can be included on a separate device. 
     The one or more treatment elements  326  can be coupled to or disposed on at least a portion of the distal portion  320  of the elongate body  318 . For example, the one or more treatment elements  326  can include an expandable element (such as a cryoballoon as shown in  FIG. 3 , an expandable array of electrodes as shown in  FIG. 2 , an expandable conductive mesh, and the like). Alternatively, the one or more treatment elements  326  can be borne directly on the distal portion  320  of the elongate body  318  (for example, the treatment device  312  can be a fixed-diameter catheter such as a focal catheter). 
     The elongate body  318  of the treatment device  312  can include one or more lumens  333 . If the treatment device  312  is a cryoablation catheter, for example, the elongate body  318  can include a main lumen, a fluid injection lumen in fluid communication with a coolant reservoir  334 , and a fluid return lumen in fluid communication with a coolant return reservoir  336 . In some embodiments, one or more other lumens can be disposed within the main lumen, can be disposed within the elongate body  318  along the longitudinal axis  329  parallel to the main lumen, and/or the main lumen can function as the fluid injection lumen or the fluid return lumen. If the treatment device  312  includes thermoelectric cooling elements or electrodes capable of transmitting RF (for example, the device shown in  FIG. 2 ), ultrasound, microwave, HIFU, laser, hot balloon, electroporation energy, or the like, the elongate body  318  can include a lumen within which one or more wires are disposed, the wires being in electrical communication with one or more energy generators  338 . 
     The console  314  can be in electrical and/or fluid communication with the treatment device  312  and can include one or more fluid (such as coolant or saline) reservoirs  334 , fluid return reservoirs  336 , energy generators  338  (for example, an RF or electroporation energy generator), and one or more computers  340  with displays  342 , and can further include various other displays, screens, user input controls, keyboards, buttons, valves, conduits, connectors, power sources, and computers for adjusting and monitoring system  310  parameters. The computer  340  can be in electrical communication with the one or more treatment elements  326 , the one or more recording electrodes  324 , and/or the one or more audio sensors  327 . Further, the computer  340  can include a processor  344  that includes one or more algorithms  346  executable to evaluate signals received from the one or more recording electrodes  324  and audio sensors  327  and to control, monitor, and/or suggest repositioning of the one or more treatment elements  326 . 
     The treatment device  312  can be used in association with an electrophysiology catheter  330 , with the treatment device  312  being used to ablate tissue and the electrophysiology catheter  330  being used to stimulate the phrenic nerve and, optionally, to record one or more electrophysiological signals from the heart. The electrophysiology catheter  330  can, for example, be slidably disposed within a lumen  333  of the device  312  such that the electrophysiology catheter  330  can be positioned within the patient&#39;s anatomy independently before advancing the treatment device  312  over the electrophysiology catheter  330  to a treatment location (as shown in  FIG. 3 ). Alternatively, the electrophysiology catheter  330  can be usable independent of the device  312  (as shown in  FIG. 3 ). The electrophysiology catheter  330  can be flexible (for example, capable of being deflectable into a hooped shape (as shown in  FIG. 3 ) and/or into a shape that includes one or more curves or bends. Further, the electrophysiology catheter  330  can include one or more pacing electrodes  328  that can be used to stimulate the phrenic nerve by transmitting energy in frequencies around approximately 100 Hz or more, for example, in a series of pacing pulses. 
     Device Placement 
       FIG. 4A  is a diagram illustrative of an embodiment in which a mapping device  402  of an intravenous catheter is positioned within the right superior pulmonary vein (RSPV).  FIGS. 4A, 4B, 6, and 9  further illustrate the relative locations of various anatomical features, including the right atrium (RA), left atrium (LA), phrenic nerve, right hemidiaphragm, right inferior pulmonary vein (RIPV), left superior pulmonary vein (LSPV), left inferior pulmonary vein (LIPV), inferior vena cava (IVC), and mitral valve (MV), with respect to various medical devices. 
     In the illustrated embodiments of  FIGS. 4A, 4B, 6, and 9 , the catheter has been moved intravenously to the heart and entered the left atrium via a transeptal puncture. In addition, in the illustrated embodiment of  FIG. 4A , the mapping device  402  has been expanded to the circumference of the RSPV near the PV-LA junction. 
     The location of the mapping device  402  (and/or catheter) can be determined in a variety of ways, such as by performing fluoroscopy or a venogram, tracking the location of the mapping device  402 , using a 3D mapping system, occlusive venography, ultrasound (intracardiac echo or transesophageal echo), contact force sensors (e.g., the difference in impedance when in contact with tissue vs. not in contact can be compared), fiber optics, etc. In some embodiments, the determined location of the mapping device  402  can be traced onto a live fluoroscopy image. 
     Once the mapping device  402  is positioned in the desired location, the mapping device  402  can be expanded until contact is made on all sides of the PV (e.g., a circumference or perimeter of the mapping device  402  is in contact with the PV). A variety of techniques can be used to determine whether there is adequate juxtaposition to the wall of the pulmonary vein/antrum, such as, but not limited to, venography, an occlusive balloon venogram, a self-expanding nitinol array, contact force sensors, direct visualization in the case of an array mounted to or in direct contact with a balloon (fiber optics), or with intracardiac echo, etc. 
     Furthermore, as described above, once the mapping device  402  is placed within the RSPV, one or more of the electrodes of the mapping device  402  can be activated to pace and map (or determine the location of) the phrenic nerve. In some embodiments, multiple electrodes are activated to identify the location of (and map) the phrenic nerve. In certain embodiments, the electrodes are activated to identify the location of as much of the phrenic nerve as possible (e.g., the portions of the phrenic nerve that can be paced by the electrodes of the mapping device  402 ). As discussed previously, activation of the electrodes closer to the phrenic nerve can result in a stronger, or more pronounced, diaphragmatic contraction (or other observable reaction). For example, in the illustrated embodiment, electrodes  410   a ,  410   b ,  410   c  can result in a stronger diaphragmatic contraction than the activation of electrodes  410   d ,  410   e ,  410   f . One may detect very proximal phrenic nerve stimulation and mapping of the phrenic nerve may extend into the PV antrum/atrium. The mapping array can be positioned in the PV antrum/atrium to complete the evaluation of the full extent of the phrenic nerve stimulation including the most proximal region of the phrenic nerve. 
     Using the results of the activation of the electrodes, the portions of the phrenic nerve near the mapping device  402  (and targeted tissue region) can be located and the phrenic nerve can be mapped. For example, a display can display the determined location of the phrenic nerve, the location of the electrodes that paced the phrenic nerve, and/or the (relative) strength of the contraction (or other observed reaction) when the particular electrode is activated compared to other electrodes. In this way, a map of the phrenic nerve can be achieved. The determined location and/or mapping of the phrenic nerve can be used to treat the targeted tissue region. 
       FIG. 4B  is a diagram illustrative of an embodiment in which the mapping device  402  (and corresponding catheter) is replaced with a treatment device  404  having a treatment element  405 , such as an inflatable balloon. For example, following the mapping of the phrenic nerve, the mapping device  402  (and corresponding catheter) can be removed and replaced with the treatment device  404 . 
     In the illustrated embodiment, the treatment element  405  of the treatment device  404  is positioned and expanded within the RSPV at a similar location to the mapping device  402 . Similar to the mapping device  402 , in some embodiments, the treatment element  405  is expanded until contact is made on all sides of the PV (e.g., a circumference or perimeter of the treatment element  405  is in contact with the PV). Contact with the PV can be determined similar to the methods described above with respect to the mapping device  402 . 
     In some embodiments, the treatment element  405  can be positioned based at least in part on the determined location of the phrenic nerve (or its mapping), or portions thereof. For example, a display can display the phrenic nerve mapping while also displaying the location of the treatment element  405 . 
     In certain embodiments, the treatment element  405  can be positioned based at least in part on the determined location of an identified proximal portion of the phrenic nerve. In some embodiments, the identified proximal portion of the phrenic nerve is the portion of the phrenic nerve nearest to the PV-LA junction and/or the atrium. 
     Based at least in part on the proximity of the treatment element  405  to the determined location of the phrenic nerve (and/or the phrenic nerve mapping), a user can determine whether to proceed with treatment. For example, if the location of the treatment element  405  (and/or the portions thereof that are in contact with the PV) is distal to, or approximately equal to, the identified proximal portion of the phrenic nerve, the user can determine not to ablate because there can be a relatively high risk of PNI. If the treatment element  405  (and/or the portions thereof that are in contact with the PV) is proximal with respect to the identified proximal portion of the phrenic nerve, the user can determine whether there is a relatively intermediate or low risk of PNI (as a non-limiting example, ≤4 mm between the treatment element  405  and the phrenic nerve can indicate a relatively intermediate risk and &gt;4 mm between the treatment element  405  and the phrenic nerve can indicate a relatively low risk, however, it will be understood that the level of risk can vary, for example, based on the treatment element  405  used, other factors, etc.). 
     In some embodiments, such as when there is a relatively intermediate risk, the treatment element  405  can be moved into the atrium, activated, and then pushed back into the PV. When activated, the circumference of the treatment element  405  can expand, which can reduce the distance in the vein to which the treatment element  405  can advance. For example, depending on the treatment device  404  used, the circumference of the treatment element  405 can expand from 26 mm to 28 mm. In this way, the physician can decrease the relative risk of PNI by increasing the distance between the phrenic nerve and the treatment element  405  during ablation as a larger diameter balloon will “wedge” at a more proximal location. 
     In the event the user determines to proceed with the treatment, the phrenic nerve can be monitored for potential injury during the treatment procedure. For example, the phrenic nerve can be paced (for example, by activating one or more electrodes of a catheter positioned in the superior vena cava (SVC) adjacent to the phrenic nerve and superior to the site of ablation in the pulmonary vein). If a reduction of the force of diaphragmatic contraction is detected (or other observable reaction changes) during ablation, the ablation procedure can be stopped. For example, the balloon can be forcibly deflated and a corresponding ice shell fractured with saline. 
     In the illustrated embodiment of  FIG. 4B , a second catheter is shown that includes a pacing electrode  412  positioned near a portion of the phrenic nerve superior to the treatment element  405  in or near the SVC. The second catheter can be used to pace the phrenic nerve during operation of the treatment device  404  in order to detect phrenic nerve injury. For example, during treatment, the pacing electrode  412  can be activated to pace the phrenic nerve. If the diaphragmatic contractions weaken (or other observable reactions change) while the placement of the pacing electrode and its electrical output remain the same (or approximately the same), a potential phrenic nerve injury can be determined and the procedure stopped. 
     Complementary Devices 
       FIGS. 5A-5D  are diagrams illustrating embodiments of a complementary mapping device  502  and treatment device  504  in different configurations and positions. In some embodiments, the complementary mapping device  502  and treatment device  504  can be implemented as part of a single catheter. In certain embodiments, the mapping device  502  and treatment device  504  can be implemented as separate, complementary catheters. For example, a mapping catheter can be sized to fit within the lumen of the treatment catheter or vice versa. In the illustrated embodiment, a mapping catheter is placed within a lumen  503  of a treatment catheter. In addition, in the illustrated embodiment, a lumen  507  of the mapping device  502  and a guidewire  516  are shown. 
     The mapping device  502  and treatment device  504  can be placed within an outer sheath  506  and can be independently operated. For example, the mapping device  502  can be independently, moved, collapsed, and/or expanded as desired. Similarly, the treatment device  504  can be independently moved, and its corresponding treatment element  505  can be independently collapsed, and/or expanded as desired. In the illustrated embodiments, a lever  508  is used to control the position and configuration of at least the mapping device  502 . 
     The mapping device  502  can be similar to the mapping device  20  described above with reference to  FIG. 2 . For example, the mapping device  502  can include multiple independently activatable electrodes  510  that can be used to pace and/or map the phrenic nerve. 
     Portions of the mapping device  502 , such as portions of the tines  512  that are more proximate to the treatment element  505  and/or outer sheath, can be coupled to a runner  514 . In the illustrated embodiment, the runner  514  can move telescopically within the treatment catheter. However, it will be understood that the runner  514  can be implemented in a variety of ways. For example, the runner  514  can form an extension of the treatment device  504 , etc. 
     In the illustrated embodiment, the lever  508  controls the runner  514 , causing the runner  514  to advance or retract. As the runner  514  moves, the configuration of the mapping device  502  can change. For example, as the runner  514  advances away from the outer sheath  506 , the mapping device  502  can move from a collapsed configuration to an expanded configuration and from an expanded configuration to a treatment configuration. However, it will be understood that fewer or more configurations can be used as desired. For example, in some embodiments, the mapping device  502  can have two configurations: collapsed and expanded, or can have more than three configurations. 
     In some embodiments, the collapsed configuration can be used to advance the mapping device  502  through the patient and outer sheath  506 . In the expanded configuration, the mapping device  502  can be used to pace and/or map the phrenic nerve, and in the treatment configuration, the mapping device  502  can be used to provide space for the treatment element  505 , pace the phrenic nerve during tissue ablation and/or provide a buffer between the treatment element  505  and the phrenic nerve. One can also determine if the underlying tissues have been frozen by the loss of local electrograms upon freezing of the tissues. 
     The treatment element  505  can be similar to the treatment element  326 , described in greater detail above with reference to  FIG. 3 . However, although illustrated as a cryoballoon catheter in  FIGS. 5A-5D , it will be understood that the treatment device  504  and treatment element  505  can be implemented using a variety of devices and technologies, including, but not limited to, RF, high-frequency ultrasound (HIFU), laser, and/or hot balloon. 
       FIG. 5A  is a diagram illustrating an embodiment of the complementary mapping device  502  and the treatment device  504  when the mapping device  502  is collapsed and the treatment element  505  is expanded. Although not illustrated, when the mapping device  502  and treatment device  504  are inserted into the patient, both can be in a collapsed position to enable movement through the patient and the outer sheath. Once the devices  502 ,  504  are positioned, each one can be independently expanded/collapsed as desired. 
       FIG. 5B  is a diagram illustrating an embodiment of the complementary mapping device  502  and treatment device  504  when the mapping device  502  and the treatment element  505  are expanded. In the illustrated embodiments, the control lever  506  is moved to alter the configuration of the mapping device  502 . As illustrated, when the control lever  506  is moved from a first position to a second position, the runner  514  advances and the mapping device  502  changes from a collapsed configuration to an expanded configuration. As described in greater detail above, in some embodiments, when in the expanded configuration, the mapping device  502  can be used to pace and/or map the phrenic nerve. 
       FIG. 5C  is a diagram illustrating an embodiment of the complementary mapping device  502  and treatment device  504  when the mapping device  502  is moved to a third, or treatment, configuration. In the illustrated embodiments, when the control lever  506  is moved to a third position, the runner  514  advances further and the mapping device  502  changes to the third configuration. In the illustrated embodiment, in the third configuration, the mapping device  502  is in an umbrella shape, however, it will be understood that in the third configuration, the mapping device  502  can be put in any shape and/or can be collapsed and withdrawn from the tissue site as desired. 
       FIG. 5D  is a diagram illustrating an embodiment of the complementary mapping device  502  and treatment device  504  when the mapping device  502  is in the treatment configuration and the treatment element  505  is moved in closer proximity to the mapping device  502 . The treatment element  505  can be moved more proximate to the mapping device  502  by using the control lever  506 , a separate control lever and/or by advancing the treatment catheter as desired. In some embodiments, by positioning the mapping device  502  in the treatment configuration and advancing the treatment element  505 , the mapping device  502  can be used to pace the phrenic nerve while the treatment element  505  ablates the target tissue. Furthermore, the mapping device  502  can be used as a buffer between the treatment element  505  and the phrenic nerve in order to reduce the likelihood of PNI. Flexible heaters can regionally warm the non-targeted tissues by resistive heating during balloon cryoablation to reduce the likelihood of PNI. 
     In the illustrated embodiments of  FIGS. 5A-5D , the runner  514  and lever  506  are used to adjust the configuration of the mapping device  502 . However, it will be understood that the configuration of the mapping device can be adjusted in a variety of ways as desired. For example, a button or cord can be used to adjust the configuration and/or move the mapping device  502  and/or treatment device  504 . 
       FIG. 6  is a diagram illustrative of an embodiment in which the complementary mapping device  502  and treatment device  504  are positioned within the right superior pulmonary vein (RSPV). In the illustrated embodiment, the configuration of the complementary mapping device  502  and treatment device  504  are similar to the configuration shown in  FIG. 5D . For example,  FIG. 6  can represent an embodiment in which the phrenic nerve has been mapped using the mapping device  502  and a healthcare provider is ready to treat the targeted tissue with the treatment device  504 . As described above, in such a configuration, the treatment element  505  can be used to treat the targeted tissue. In addition, the mapping device  502  can be used to pace the phrenic nerve during treatment (e.g., at a location superior to the location of treatment) and/or provide a buffer between the treatment element  505  and the phrenic nerve during treatment. Furthermore, the location and placement of the devices  502 ,  504  can be determined similar to the manner in which the location of the mapping device  402  and treatment device  404  are determined. 
     Anatomical Cycle 
     In some embodiments, the determined placement and/or use of a medical device, such as the mapping device  20 / 402 / 502  and/or the treatment device  312 / 404 / 504 , can be based at least in part on an anatomical cycle, such as a respiration or cardiac cycle. 
     In some cases, during a procedure, anatomical cycles can cause portions of relevant tissue to move in a cyclical pattern with respect to the location of a medical device. For example, during the respiration cycle, the heart can move several centimeters depending on the tidal volume. 
     By taking into account movement due to the anatomical cycle in determining the location/use of a medical device, a user can increase the likelihood that two medical devices have been placed in the same location at different times, and reduce the likelihood of treating undesired tissue. For example, a user can increase the likelihood that the treatment element  326 / 405 / 505  has been placed in the same location that the mapping device  20 / 402 / 502  was when mapping the surrounding tissue (e.g., when mapping the phrenic nerve). In some cases, the amount of tissue movement due to an anatomical cycle can be reduced, such as by using jet ventilation in a non-paralyzed patient. 
     As a non-limiting example, at a particular portion of an exhalation cycle, such as at end exhalation, the location of the mapping device  20 / 402 / 502  can be determined. The location can be determined in a variety of ways, such as by performing fluoroscopy or a venogram, tracking the location of the mapping device  20 / 402 / 502  using a 3D mapping system, occlusive venography, ultrasound (intracardiac echo or transesophageal echo), contact force sensors (e.g., the difference in impedance when in contact with tissue vs. not in contact can be compared), fiber optics, etc. In some embodiments, the determined location of the mapping device  20 / 402 / 502  can be traced onto a live fluoroscopy image. The electrodes of the mapping device  20 / 402 / 502  can be paced and the location of the phrenic nerve determined. In addition, the location of some or all of the phrenic nerve, timed to end exhalation can be displayed on the live fluoroscopy image. 
     In some embodiments, once the mapping device  20 / 402 / 502  is moved or replaced with the treatment device  312 / 404 / 504 , the location of the treatment device  312 / 404 / 504  can be determined. In certain embodiments, the location of the treatment device  312 / 404 / 504  and/or treatment element  326 / 405 / 505  can be determined, timed to end exhalation. The determined location can then be compared to the determined location of the phrenic nerve and/or the mapping device  20 / 402 / 502 , and the user can determine whether to proceed with the procedure as described above. 
     Phrenic Nerve Injury Risk Determination Examples 
       FIG. 7  is a flow diagram illustrating an embodiment of a routine  700  for treating cardiac arrhythmia. 
     At block  702 , a venography is performed of one or more pulmonary veins of a patient. In some embodiments, the venography can be performed for the right-sided pulmonary veins and/or can be displayed in at least two orthogonal views. In certain embodiments, the venography can be timed to end exhalation. In some cases, the patient is spontaneously breathing (e.g., not paralyzed, not being assisted by the ventilator). 
     At block  702 , the veins are displayed on a screen, such as a live fluoroscopy screen. In certain embodiments, the veins can be displayed timed to end exhalation and/or in at least two orthogonal views. 
     At block  704 , a mapping device is placed in the pulmonary vein and/or pulmonary vein antrum and a fluoroscopy is performed to determine its location. In some embodiments, the fluoroscopy can be performed in the same view as those used in block  702  and/or can be timed to end exhalation. 
     At block  706 , the mapping device is displayed and/or traced onto the displayed veins. In certain embodiments, the mapping device can be displayed timed to end exhalation. 
     At block  708 , one or more electrodes of the mapping device are activated to determine the location of the phrenic nerve. As described in greater detail above, the activation of the electrodes can be used to determine the location of the phrenic nerve in the pulmonary vein and/or pulmonary vein antrum with respect to the mapping device. In some embodiments, the activation of the electrodes can be done at high output (e.g., 20 mA at 9 ms asynchronously). 
     At block  710 , a proximal portion of the phrenic nerve captured by the mapping device is identified and displayed. In some embodiments, the proximal portion of the phrenic nerve can be displayed in at least two orthogonal views and/or timed to end exhalation. 
     At block  712 , it is determined whether a proximal portion of the mapping device (proximal with respect to a central axis that is orthogonal to a longitudinal axis of the mapping device) is free of phrenic nerve stimulation. If not, the mapping device can be retracted until the proximal portion of the mapping device is free of phrenic nerve capture. In certain embodiments, the phrenic nerve is paced with high output. In some embodiments, if the mapping device is moved, blocks  708  and  710  can be repeated. 
     At block  714 , the position of the mapping device and the sites of phrenic nerve stimulation are displayed on a display. In some embodiments, the position of the mapping device and the sites of phrenic nerve stimulation can be displayed on a 3D mapping system. 
     At block  716 , the mapping device is replaced with a treatment device, such as a treatment device  312 / 404 / 504 , and at block  718  a treatment element of the treatment device is inflated to achieve occlusion. In some embodiments, the treatment element can be inflated after positioning the treatment element at one of the right-sided veins. 
     At block  718 , the vein is occluded, and at block  720  a venography is performed to confirm the occlusion. In certain embodiments, the venography can be performed through a distal port of the treatment device and/or can be timed to end exhalation. 
     At block  722 , the position of the treatment element of the treatment device is determined relative to the most proximal site of phrenic nerve stimulation. In some embodiments, the position can be determined timed to end exhalation. 
     At block  724 , the location of the treatment element is compared with an indication, such as a line or other graphic, of a most proximal portion of the phrenic nerve. If the treatment element overlaps the indication, the location is identified as high risk. If the treatment element is located within four millimeters of the indication, the location is identified as intermediate risk. If the treatment element is located greater than four millimeters of the indication, the location is identified as low risk. If the location is identified as high risk, the treatment element can be repositioned to an intermediate risk position or low risk position. 
     At block  726 , the phrenic nerve is paced while ablating. During the ablation, if a reduction of the force of diaphragmatic contraction is detected by palpation, the position of the catheter in the SVC can be verified. If the location was identified as low risk and the catheter pacing the phrenic nerve has moved, excursion of the right hemidiaphragm can be verified using fluoroscopy. 
     If a weakening of the diaphragm is detected fluoroscopically, the treatment element can be forcibly deflated and the ice shell fractured with saline administered through the distal port. If the diaphragm is moving normally on fluoroscopy, the treatment element can be repositioned in the SVC to regain phrenic nerve capture and the ablation continued. 
     If the case was identified as intermediate risk and the diaphragmatic contraction weakens by palpation, the treatment element can be deflated and the ice shell fractured. Fluoroscopy can be performed to assess the motion of the right hemidiaphragm. 
     At block  728 , the presence of pulmonary vein isolation (PVI) is assessed, and in certain cases, additional treatment provided. In some embodiments, PVI can be assessed by placing the mapping and/or treatment device at the pulmonary vein antrum and in the pulmonary vein, evaluating for the presence of local PV electrograms to determine the presence of entrance block, and pacing the pulmonary vein to determine the presence of exit block. 
     In response, if persistent PV conduction is detected, additional treatment can be provided. For example, in some cases, the earliest site of entrance conduction into the PV/PV antrum can be targeted with the treatment device. Additional sites can be treated based on additional assessments for PVI. 
     In addition, as part of the assessment, adenosine can be administered after PVI to determine the presence of dormant conduction. Following the administration of the adenosine, if PV conduction is detected, additional treatment can be provided. For example, the earliest site of entrance conduction into the PV can be targeted with the treatment device. In some cases, the presence of PVI can be repeatedly assessed until there is no evidence of dormant conduction. 
     It will be understood that the various steps described above can be performed in a variety of orders. Furthermore, some steps can be omitted. For example, in some embodiments, a 3D mapping system may not be used, etc. In certain embodiments, the anatomical cycle (e.g., end exhalation) can be ignored, such as, but not limited to, when a treatment device that includes mapping functionality is used. Furthermore, although described with respect to locating the phrenic nerve and the treatment of cardiac arrhythmia, it will be understood that routine  700  can be used to identify the location of non-targeted tissue near a tissue site in other locations of the body. For example, the mapping device can be placed at a tissue site other than the pulmonary vein, such as near the prostate, and electrodes activated to locate non-targeted tissue near the tissue site, such as nerves near the prostate or a proximal portion of non-targeted tissue near a tissue site. Once located, the mapping device can be replaced with a treatment device, and a treatment element of the treatment device inflated. The location of the treatment element can be compared with the determined location of the non-targeted tissue. Based on the comparison, it can be determined whether the location of the treatment element represents a relatively low risk, relatively intermediate risk, or relatively high risk. The treatment element can be moved or treatment can begin based on the determined risk level. During treatment, the non-targeted tissue can continue to be assessed, such as by stimulation. If an adverse reaction occurs, the treatment can be stopped. 
       FIG. 8  is a flow diagram illustrating an embodiment of a routine  800  for treating a tissue site. For example, routine  800  can be used to treat cardiac arrhythmia. Furthermore, it will be understood that any one or more of the blocks of routine  700  can be included with routine  800 . 
     At block  802 , a mapping device is placed at a tissue site and determine the location of the mapping device. In certain embodiments, the tissue site can be the pulmonary vein and/or pulmonary vein antrum. As described above, in some embodiments, a fluoroscopy is performed to determine the location. In some embodiments, its location can be determined timed to an anatomical cycle, such as end exhalation. 
     At block  804 , one or more electrodes of the mapping device are activated to determine the location of non-targeted tissue with respect to the mapping device. In some cases, the non-targeted tissue can be the phrenic nerve. However, it will be understood that when used in other areas of the body, the one or more electrodes can be used to determine the location of other non-targeted tissue near a tissue site. 
     At block  806 , a proximal portion of the non-targeted tissue captured by the mapping device is identified and displayed. In some embodiments, such as when treating cardiac arrhythmia, the proximal portion of the phrenic nerve can be identified. In certain cases, the determined location can be displayed in at least two orthogonal views and/or timed to a portion of the anatomical cycle, such as end exhalation. 
     At block  808 , the mapping device is replaced with (or moved for) a treatment device. 
     At block  810 , a treatment element of the treatment device is inflated for treatment. In certain embodiments, the treatment element is inflated to achieve occlusion of a vein. 
     Once it is determined that the treatment element is inflated to a satisfactory level, such as occlusion of the vein, at block  812  the position of the treatment element is determined relative to the identified proximal portion of the non-targeted tissue, such as the phrenic nerve. In some embodiments, the position of the treatment element is determined timed to a portion of the anatomical cycle, such as end exhalation. 
     At block  814 , a risk level is determined based at least in part on determined position of the treatment element relative to the identified proximal portion of the non-targeted tissue. 
     At block  816 , the treatment is performed based at least in part on the determined risk level. As described in greater detail above with reference to  FIG. 7 , in some embodiments, if the risk level is determined to be high, the treatment element can be moved. 
     At block  818 , the non-targeted tissue is monitored during treatment. For example, the non-targeted tissue can be monitored by electrical stimulation or other methods. If an adverse reaction is detected, the treatment element can be moved or the treatment stopped. 
     In embodiments in which the phrenic nerve is paced, during the ablation, if a reduction of the force of diaphragmatic contraction is detected by palpation, the position of the catheter in the SVC can be verified. If the location was identified as low risk and the catheter pacing the phrenic nerve has moved, the fluoroscopy can be repositioned. If a weakening of the diaphragm is detected fluoroscopically, the treatment element can be forcibly deflated and the ice shell fractured with saline administered through the distal port. If the diaphragm is moving normally on fluoroscopy, the treatment element can be repositioned in the SVC to regain phrenic nerve capture and the ablation continued. If the case was identified as intermediate risk and the diaphragmatic contraction weakens by palpation, the treatment element can be deflated and the ice shell fractured. Fluoroscopy can be performed to assess the motion of the right hemidiaphragm. 
     At block  820 , the targeted tissue site is assessed, and in certain cases, additional treatment provided. In some embodiment, once an initial treatment is completed, the tissue at the targeted tissue site can be examined to determine whether additional treatment is to be provided. For example, electrical signals near the targeted tissue site can be monitored. 
     With respect to embodiments in which cardiac arrhythmia is being treated, the presence of PVI can be assessed. In some embodiments, PVI can be assessed by placing the mapping and/or treatment device at the pulmonary vein antrum and in the pulmonary vein, evaluating for the presence of local PV electrograms to determine the presence of entrance block, and pacing the pulmonary vein to determine the presence of exit block. In response, if persistent PV conduction is detected, additional treatment can be provided. For example, in some cases, the earliest site of entrance conduction into the PV/PV antrum can be targeted with the treatment device. Additional sites can be treated based on additional assessments for PVI. In addition, as part of the assessment of PVI, adenosine can be administered after PVI to determine the presence of dormant conduction. Following the administration of the adenosine, if PV conduction is detected, additional treatment can be provided. For example, the earliest site of entrance conduction into the PV can be targeted with the treatment device. In some cases, the presence of PVI can be repeatedly assessed until there is no evidence of dormant conduction. 
     Fewer or more steps can be included as desired. For example, if the risk level is high, the treatment device can be moved. If the risk level is intermediate, the treatment device can be withdrawn from the tissue site, activated, and re-inserted into tissue site as described above. Furthermore, with respect to treating cardiac arrhythmia, during ablation, the phrenic nerve can be monitored and action taken, as described in greater detail above with reference to  FIG. 7 . For example, in some cases, if weakening diaphragmatic contractions are detected, the treatment element can be deflated and an ice shell broken. 
     In addition, although specific embodiments are described with respect to identifying the location of the phrenic nerve during treatment of cardiac arrhythmia, it will be understood that routine  800  can be used to identify non-targeted tissue near targeted tissue sites during treatment of other areas of the body. For example, the greater and lesser cavernous nerves (non-targeted tissues) pass nearby the prostate gland and can be injured during prostate surgery causing erectile dysfunction. By identifying the location of the nerves prior to treatment, the likelihood of injury can be reduced. 
     Segmented Treatment Element 
       FIGS. 9, 10A and 10B  are diagrams illustrating embodiments of treatment elements  902 ,  1002  of treatment devices that include multiple segments, which can also be referred to as cells or compartments. Each segment can be formed by a separate inflatable device, such as a balloon, and/or encompass a distinct location and volume with respect to the other segments. Furthermore, each segment can include walls that separate it from the other segments. 
     In the illustrated embodiment of  FIG. 9 , the treatment element  902  includes two segments: a distal segment  904  and a proximal segment  906 . Further, in the illustrated embodiment of  FIG. 9 , the distal segment  904  is smaller than the proximal segment  906 . However, it will be understood that the segments can be the same size or the proximal segment  906  can be smaller than the distal segment  904 . 
     In the illustrated embodiment of  FIGS. 10A and 10B , the treatment element  1002  includes eight segments  1004 A,  1004 B,  1004 C,  1004 D,  1004 E,  1004 F,  1004 G,  1004 H that extend from a distal portion central lumen to a more proximal portion of the central lumen forming approximately equal partitions of the distal end of the treatment device corresponding to the treatment element, and which can also be referred to as wedge segments. It will be understood that the embodiments shown in  FIGS. 9, 10A , and  10 B can be combined as desired and/or fewer or more segments can be used as desired. For example, the distal segment  904  and/or the proximal segment  906  can include multiple wedge segments and/or the treatment element  902  can include fewer or more segments, such as a central segment, etc. Similarly, the treatment element  1002  can include proximal and distal segments as desired and can include fewer or more wedge segments. 
     In certain embodiments, the cells can be independently controlled. For example, in some embodiments, each segment (or a subset of the total number of segments) can be independently and variably expanded and/or contracted. Furthermore, each segment (or a subset of the segments) can be independently heated or cooled. 
     In some cases, segments determined to be in close proximity to the phrenic nerve and/or esophagus can be converted to warming segments. For example, the distal segment  904  can be used for cryoablation during ablation of left sided PVs, and the proximal segment  906  can be a warming segment if the esophagus satisfies a distance threshold or temperature threshold, or is too close or became too cold during ablation of the left sided pulmonary veins. 
     Similarly, in cases where the distal segment  904  is determined to be too close to the phrenic nerve (for example, by pacing the phrenic nerve) or other tissue that is not to be treated, the proximal segment  906  can be used to cryo-ablate tissue and the distal segment  904  can be deflated and not used to cryoablate, inflated but not used to cryoablate, or inflated and used as a warming segment. 
     The segments can be made of a compliant material, such as polyurethane, polyester, composite material, laminate, or other material that allows for variable sizing to enable contact with the surrounding tissue, such as a pulmonary vein antrum, and to seal leaks between the surrounding tissue and the treatment element  902 ,  1002 . The size of the segments can be adjusted by variably pressurizing during use, such as during cryoablation or warm high pressure mapping. As discussed in greater detail below, in certain cases, contact force sensors and flow sensors can be used to guide the appropriate size. If phrenic nerve location (or other tissue near a target site, but that is not to be treated) is a concern, high pressure warm mapping can be performed with to seal the tissue without risking injury to the nerve. In this way, the operator can test the occlusion of a vein, or other tissue, without risking injury to the surrounding tissue. 
     With respect to the treatment elements in  FIGS. 10A and 10B , in some cases, if one or more of the segments  1004 A,  1004 B,  1004 C,  1004 D,  1004 E,  1004 F,  1004 G,  1004 H are determined to be too close to tissue that is not to be treated, the one or more segments  1004 A,  1004 B,  1004 C,  1004 D,  1004 E,  1004 F,  1004 G,  1004 H can be deflated, inflated without injecting high pressure refrigerant such as N2O to cryoablate, or used as warming segments either by applying a warming agent or leaving the segment empty of a solution. 
     Treatment Device with Sensors/Electrodes 
       FIGS. 11 and 12  are diagrams illustrating embodiments of treatment devices  1102 ,  1202  that include one or more sensor/electrodes and can be used to pace and/or map the phrenic nerve and/or treat the targeted tissue region. Devices that can be used for mapping and treating a target location, such as treatment devices  1102 ,  1202 ,  1302  can also be referred to as an integrated device and/or an integrated treatment device. In some embodiments, when using the treatment devices  1102 ,  1202 , the anatomical cycle can be ignored because the mapping and treatment devices described above are combined; provided however that the combined treatment devices are in direct contact with the targeted tissue during an anatomic cycle (non-limiting example: a combined treatment device positioned in PV antrum during an occlusive venogram. Furthermore, once the treatment device is inflated within the PV, the device can move with the tissue during the anatomical cycle. In some embodiments, the lumen of the treatment device  1102 ,  1202  can be flush with the distal end of the treatment device  1102 ,  1202 , thereby allowing the treatment device to be used without a guide wire. 
     As described in greater detail above with reference to  FIGS. 10A, 10B , and  10 C, and as further illustrated in  FIGS. 11 and 12 , in some embodiments, the treatment device can include two or more segments, such as a distal and proximal segment. In certain embodiments, mapping electrodes can be included on the surface of the treatment device, thereby allowing accurate real time assessment of the location of the phrenic nerve. 
     In the illustrated embodiment of  FIG. 11 , a distal portion of treatment device  1102  is shown including central lumen  1112  and a treatment element  1103  that includes a distal segment  1104 , a proximal segment  1106 , a plurality of electrodes/ sensors  1108 . In the illustrated embodiment of  FIG. 12 , a distal portion of treatment device  1202  is shown including a central lumen  1212  and a treatment element  1203  that includes a distal segment  1204 , four proximal segments configured as wedge segments  1206 A,  1206 B,  1206 C,  1206 D (not shown), and a plurality of electrode/sensors  1208 . It will be understood that fewer or more compartments can be used as desired and that each of the segments can be independently controlled. Furthermore, each segment can be capable of cryoablation, cold mapping (low pressure), warm mapping (low pressure), warm fully inflated (high pressure), etc. It will be understood that warm mapping can include a solution at ambient temperature or a solution that is not cooled. 
     In some embodiments, the various segments of the treatment elements  1103 ,  1203  can be enclosed by an outer casing  1110 ,  1210 , which can be formed of a compliant material, such as polyurethane with a vacuum between it and each of the interior segments to ensure safety in the event of a rupture of any of the segments  1104 ,  1204 ,  1106 ,  1206 A- 1306 D. In some cases, the electrodes/sensors  1108 ,  1208  can be on the exterior of the outer casing  1110 ,  1210 . In some embodiments, the sensors/electrodes  1108 ,  1208  can be integrated into the outer casing  1110 ,  1210 . 
     As further illustrated in  FIGS. 11 and 12 , the treatment device  1102 ,  1202  can include a series of sensing, pacing, mapping, ablation electrodes, contact force sensors, and/or flow sensors (collectively electrodes/sensor  1108 ,  1208 ) designed to characterize tissue, such as the pulmonary vein and surrounding tissues in the vein, including the phrenic nerve. For example, the electrodes/sensors  1108 ,  1208  can be used to detect contact of the treatment element  1103 ,  1203  to the antrum of the pulmonary vein or the pulmonary vein itself, locate, any flow of blood around the treatment device, obtain pulmonary venous electrograms, locate/map/pace the phrenic nerve, and/or determine the temperature of the tissue adjacent to the phrenic nerve, esophagus, and/or the remainder of the antrum/pulmonary vein itself. As such, in certain embodiments, the treatment device  1102 ,  1202  can be utilized as a 3D mapping catheter able to collect 3D volume and activation times. 
     In some embodiments, the pacing electrodes can be used to stimulate surrounding tissue, such as a phrenic nerve. Based on the stimulation, the treatment device  1102 ,  1202  can generate a map of the surrounding tissue, collecting 3D geometry and/or identify the location of the phrenic nerve and/or esophagus. 
     The sensing electrodes can be used to detect electrical or other activity. For example, the sensing electrodes can identify electrical activity before and/or after the procedure. Before the procedure, the data from the sensing electrodes can be used to identify a location of tissue that is to be ablated. Following the procedure, the data from the sensing electrodes can be used to determine whether the procedure was successful. 
     The contact force sensors can be used to detect contact of the treatment element  1103 ,  1203  to surrounding tissue and/or whether the tissue is properly occluded. The flow sensors can be used to detect any flow of blood or other substance around the treatment device and/or to determine whether the tissue is properly occluded. 
     Ablation electrodes can be used to isolate the pulmonary vein, in the event that the proximal segment of the treatment element  1103 ,  1203  satisfies a distance threshold with respect to the phrenic nerve (for example, is too close to the phrenic nerve and/or cryoablation risks phrenic nerve injury). Additionally, the ablation electrode can be used for radiofrequency touchup to improve the ablation of certain tissue and/or increase likelihood of a successful procedure. In certain cases, the ablation electrodes can be configured in a ring. In some embodiments, the inclusion of ablation electrodes with the treatment device  1102 ,  1202  can replace the use of a separate radiofrequency catheter. 
     The temperature sensors can be used to monitor the temperature of tissue, before, after, or during ablation. Based on the temperature sensor data, the treatment element  1103 ,  1203  can be moved and/or the procedure halted. In some embodiments, the temperature sensors can be positioned on the treatment element  1103 ,  1203  adjacent to mapping electrodes and can demonstrate the temperature of the various regions of the treatment element  1103 ,  1203 . The temperature of electrodes/sensors  1108 ,  1208  near sites of phrenic nerve (or other tissue) stimulation can be used to assess the risk of injury and can help in the prevention of injury in intermediate risk cases. If the local temperature of electrodes/sensors  1108 ,  1208  near the phrenic nerve (or other relevant tissue) satisfy a temperature threshold and/or are too cold, cryoablation can be stopped prior to injury of the nerve. 
     The treatment device  1102 ,  1202  can include additional sensors/electrodes as desired. For example, the treatment device  1102 ,  1202  can include optical elements to visualize the effects of ablation on the tissue, e.g., looking for gaps in the ablation lines or rings. 
     In certain cases, the treatment device  1102 ,  1202  can include an ultrasound transducer that can be used to obtain geometry, determine if a leak is occurring (with color flow), determine the optimal size to inflate the treatment device  1102 ,  1202  to obtain contact with the antrum of the pulmonary veins, etc. In some cases, the ultrasound transducer to construct 3D geometry for accurate navigation of the treatment device  1102 ,  1202  without the use of fluoroscopy. Color flow can help determine the sizing of the treatment device  1102 ,  1202  to ensure occlusion even in cases of left common ostium. 
     In addition, in some cases, an esophageal temperature probe can be positioned close to the treatment device  1102 ,  1202 , and in some cases, as close as possible. The pairing of the esophageal probe, with the treatment device  1102 ,  1202  can improve the ability to identify the location of the segments nearest the esophagus. The signals can be sent over to any physiologic recording system or 3D mapping system for viewing. In some cases, if the treatment device  1102 ,  1202  is moved, rotated, or otherwise manipulated, the tissue can be remapped. 
     The electrodes/sensors  1108 ,  1208  for each segment of the treatment elements  1103 ,  1203  can be paired with a return electrode/sensor specific to the segment, such that pacing or sensing on that wedge segment can result in the completion of the circuit and enable the treatment device  1102 ,  1202  to determine which segment is being evaluated on the console. For example, a return electrode can be paired with the distal segment  1204 , such that pacing any electrode on the distal segment  1204  causes the completion of a circuit that enables the treatment device  1102 ,  1202  to recognize the distal segment  1204 . If the electrode being paced captures the phrenic nerve, a press of a touch screen can identify the segment or sub-segment. In some cases, the screen can turn the corresponding segment red, or otherwise highlight the segment that is being paced. Once selected, the corresponding segment can be configured for a warm mode, either low or high pressure, or a cryoablation mode. 
     In some embodiments, when in a mapping mode, all segments of the treatment element  1103 ,  1203  can be inflated to map the tissue. The tissue can be characterized using the electrodes/sensors  1108 ,  1208 . In some cases, the distal segment  1104 ,  1204  can be used to keep a firm position in the vein while the phrenic nerve is being pacing using the electrodes/sensors  1108 ,  1208 . 
     In some embodiments, the segments of the treatment element  1103 ,  1203  that risk damaging tissue surrounding a target site, such as the phrenic nerve or esophagus, can be can be deflated and/or used as warming segments, whether at high pressure or low pressure. In addition, the temperature of the tissue adjacent to the target site can be monitored using the electrodes/sensors  1108 ,  1208  during the procedure. 
     Based on the data collected during the mapping mode, the treatment device  1102 ,  1202  can provide treatment (e.g., cryoablation, etc.) from any of the proximal  1106 ,  1206 A- 1306 D, and/or distal segments  1104 ,  1204 . If the phrenic nerve (or other tissue near a target site) is in jeopardy of being damaged and/or paralyzed by the distal segment  1104 ,  1204 , the distal segment  1104 ,  1204  can be converted to a warming balloon, inflated without cryoablating, and/or deflated. As such, the treatment device  1102 ,  1202  can protect the phrenic nerve from cryoablation and also assess the function of the phrenic nerve by pacing the nerve using the electrodes/sensors  1108 ,  1208  that are positioned on the treatment element  1103 ,  1203 . 
     In some embodiments, as described in greater detail above, the distal segment  1104 ,  1204  can remain cold mapping for cryoablation during ablation of left sided PVs, and the proximal segments  1106 ,  1206 A- 1306 D can be used as warming segments if the esophagus satisfies a distance threshold or temperature threshold or becomes too cold during ablation of the left sided pulmonary veins. 
     As yet another example, the proximal segment(s)  1106 ,  1206 A- 1306 D can be used to isolate the pulmonary vein. Pulmonary vein electrograms can be assessed during the freeze to determine time to effect thereby reducing unnecessary additional cryoablation. In some embodiments, if it is determined that the mapped tissue is clear of any phrenic nerve activation and satisfies a threshold distance from the esophagus, all segments of the treatment element  1103 ,  1203  can be used to ablate. 
     Furthermore, in some cases, the treatment device  1102 ,  1202  can be used for a roof line or posterior wall isolation. The treatment device  1102 ,  1202  can assess for bidirectional block across the pulmonary vein antrum (pulmonary vein isolation), block across the roof of the left atrium and posterior wall isolation, etc. 
     The treatment device  1102 ,  1202  can be constructed such that the treatment element  1103 ,  1203  can variably expanded to determine contact with the antrum, including cases of a left sided common ostium. Furthermore, as mentioned above, the segments of the treatment element  1103 ,  1203  in close proximity to the phrenic nerve and/or esophagus can be converted to warming segments. In some embodiments in place of or in addition to the segments, the electrodes/sensors  1108 ,  1208  of the treatment device  1102 ,  1202  can be used to create warmth regions. 
     In some embodiments, the treatment device  1102 ,  1202  can be controlled manually or robotically from a console without fluoroscopy. The treatment device  1102 ,  1202  can reconstruct the course of the phrenic nerve as a continuous variable. The various cells can be closed off (or not supplied with a solution), deflated, and/or converted to warming cells automatically to create a buffer to protect the nerve. The temperature of the tissue in contact with the phrenic nerve can be assessed and the catheter can convert more cells to warming cells if the temperature of the tissue near the esophagus gets too low or satisfies a temperature threshold. The temperature threshold can be based on a temperature at which tissue will be, or is likely to be, damaged. After the veins are isolated, the treatment device  1102 ,  1202  can be used to achieve a roof line, if a roof dependent tachycardia is induced. 
     In some embodiments, the treatment device  1102 ,  1202  can be used to assess for block across the roof by positioning the treatment element  1103 ,  1203  across the line and pacing from each side (anterior and posterior to the line). The treatment device  1102 ,  1202  can isolate the posterior wall of the left atrium and assess for electrical isolation. 
     The energy modality used to achieve isolation can include, but is not limited to, cryoablation, laser, HIFU, radiofrequency, etc. An ultrasound catheter mounted to the treatment device  1102 ,  1202  can recreate 3D geometry, assess for leaks and coupled with the array of sensors allow for non-fluoroscopic navigation of the treatment device 1202 ,  1202 . 3D mapping and temperature assessment of the esophagus can enhance the safety of the procedure. Segments of the treatment device  1102 ,  1202  adjacent to the esophagus can be turned to a warming mode to protect the esophagus. 
     A console can display the treatment device  1102 ,  1202 , any portion thereof, such as treatment element  1103 ,  1203 , or a virtual representation of thereof, and each segment of the treatment element  1103 ,  1203  can be independently controlled for warm mapping (low pressure), warm mapping (high pressure), cold mapping (low pressure using N 2 O), and/or cryoablation. 
     By using the treatment device  1102 ,  1202 , a healthcare provider can avoid changing catheters during surgery, i.e. from replacing the mapping device  20  with the treatment device  312 . The treatment device  1102 ,  1202  can map in real time and also be used for ablation, thereby reducing, if not eliminating, error in accurate translation of phrenic nerve location to treatment device  1102 ,  1202  location. Furthermore, the treatment device  1102 ,  1202  can reduce the risk of inadvertent damage, reduce stress on the operator, and potentially enable the operator to be more aggressive with the ablation, due to the mapping. In cases where the distal segment  1104 ,  1204  is made a warm high pressure balloon, the phrenic nerve can be paced from a stable, reliable position above the treatment level. Local tissue temperature next to the nerve can be assessed. As such, the phrenic nerve can be shielded, the temperature of its local environment assessed and its function tested with the treatment device  1102 ,  1202 . 
       FIG. 13  is a diagram illustrative of an embodiment of a treatment device  1302  positioned within the right superior pulmonary vein (RSPV). The treatment device  1302  can be similar to the treatment devices  1102 ,  1202  described previously with reference to  FIGS. 11 and 12 , and can include one or more treatment elements  1304  and one or more sensors  1306 . The one or more sensors can also be referred to as a mapping portion  1306 . The mapping portion  1306  can be similar to the mapping devices  20 / 402 / 502  and/or the sensors  1108 ,  1208  described previously, and the treatment element  1304  can be similar to any one or any combination of the treatment elements  326 / 405 / 505 / 902 / 1002 / 1103 / 1203 , described previously. 
     In the illustrated embodiment, the treatment device  1302  can be placed in a mapping mode and/or a treatment mode. In the mapping mode, various electrodes of the mapping portion  1302  can be activated to determine the location of the phrenic nerve. In the treatment mode, the treatment element  1304  (or segments thereof) can be activated in order to ablate the tissue. For example, the treatment element  1304  (or segments thereof) can be filled with a coolant for cryoablation. However, as described previously, the tissue can be ablated in a variety of ways. As described in greater detail above, with reference to  FIGS. 12 and 13 , the segments of the treatment element  1304  can be individually and independently used as warming regions or as ablation regions. 
       FIG. 13  further illustrates a second catheter with a pacing electrode  1308  positioned near the phrenic nerve superior to the treatment device  1302 . In some embodiments, once the treatment element  1304  is activated, the electrodes of the mapping portion  1302  may not be usable. (If this is cryoablation, one can definitely use the high impedance artifact to dose once the PN is properly located and the tissue depth assessed with thresholds). In such embodiments, the electrode  1308  can be used to detect phrenic nerve injury, similar to the electrode  412  described previously. If a potential phrenic nerve injury is determined, the procedure can be stopped and/or different portions of the treatment device can be activated as warming regions, as described previously. 
     Pulmonary Vein Assessment 
     After each pulmonary vein has been ablated, sensing and pacing electrodes on an independent mapping array such as the Constellation Basket, complementary mapping device  502 , a treatment device  1102 ,  1202 ,  1302  and a mapping overlay  1501  can be used to assess for the presence of entrance and exit block. Specifically, the presence of local electrograms (near-field signal) associated with the underlying atrial rhythm would indicate that the pulmonary vein antrum is not isolated if the integrated device is positioned opposed to the pulmonary vein antrum. The absence of signals or the presence of independent signals can indicate entrance block. Pacing of the vein from electrodes positioned distal to the ablation region can be used to assess for exit block. 
     Local capture of the vein can be evidenced by the generation of local PV potentials without capturing the atrium in a patient in normal rhythm can be used to determine exit block. In the case that a vein has persistent PV connection during sinus rhythm, atrial fibrillation, flutter, atrial tachycardia or other atrial rhythm, the location of the earliest local PV electrogram (near-field signal) can be mapped in both a circumferential and/or a longitudinal axis to determine the specific location of electrical entrance into the pulmonary vein antrum. Targeting this location with ablation can result in isolation of the vein and/or can reveal the presence of another site of earliest PV connection that must also be ablated to achieve isolation. 
     Adenosine 
     Adenosine, or other A1 (adenosine 1; AKA purine 1) receptor agonist, can be used post ablation in isolated veins to adjust the treatment device  1102 ,  1202  upon an additional treatment, such as a freeze. For example, a given pulmonary vein is isolated as determined upon remapping post ablation with the treatment device  1102 ,  1202 . IV adenosine can be given to the point of causing transient heart block, hypotension or sinus node suppression. 
     A transient acute PV reconnection (as evidenced by PV electrograms associated with sinus rhythm or other atrial rhythm) can be readily and specifically targeted prior to moving to the next pulmonary vein. These acute reconnections can involve an area that leaked during ablation. Directing the treatment device to target the site(s) of acute PV reconnection can result in elimination of dormant conduction, which has been demonstrated to improve the efficacy of the atrial fibrillation ablation. 
     Sensors Co-Located with Treatment Element 
       FIG. 14  is a flow diagram illustrating an embodiment of a routine  1400  for locating non-targeted tissue near a targeted tissue site and providing treatment to the tissue site based on the location of the non-targeted tissue. In some embodiments, routine  1400  can be used in conjunction with an integrated treatment device that includes sensors co-located with a treatment element. In certain embodiments, routine  1400  can be used in conjunction with a mapping overlay or mapping device, such as the mapping overlay described below with reference to  FIGS. 15A-15C and 16A-16C , that is distinct from a treatment device but provides sensors or electrodes that are co-located with at least a portion of the treatment element of a treatment device. 
     At block  1402 , a treatment element of a treatment device is inflated at a targeted tissue site, which can also be referred to as a target site or treatment site. In some embodiments, the tissue site can be the pulmonary vein. In some embodiments, prior to inflation, the treatment element is placed in the pulmonary vein antrum and an occlusive balloon venogram is performed to determine its location. 
     At block  1404 , one or more electrodes of a mapping portion of the integrated treatment device or a mapping overlay (as described in greater detail in  FIGS. 15A-15C and 16A-16C ) coupled to a treatment device are activated to determine the location of a proximal portion of tissue near the target site, such as the phrenic nerve in the pulmonary vein. 
     At block  1406 , the proximal portion of the non-targeted tissue near the target site captured by the mapping portion or mapping overlay is identified and displayed. In some embodiments, it is determined whether a proximal portion of the mapping portion or mapping overlay is free of non-targeted tissue stimulation, such as phrenic nerve stimulation. If not, the device can be retracted until the mapping portion corresponding to the location of the treatment element is free of non-targeted tissue capture. In certain cases, such as when used to treat cardiac arrhythmia, this can reduce the likelihood that phrenic nerve function will be affected by the treatment element. 
     At block  1408 , a risk level is determined based at least in part on the position of the treatment element relative to the identified proximal portion of the tissue near the target site. In some embodiments, zones to be treated and zone of non-targeted tissue to be protected can be established. 
     At block  1410 , treatment is performed at the target site based at least in part on the determined risk level. As described in greater detail above with reference to  FIG. 7 , in some embodiments, if the risk level is determined to be high, the treatment element can be moved and/or one or more segments or electrodes can be used to protect the non-targeted tissue. For example, one or more segments can be deflated or used as a warming balloon, etc. 
     At block  1412 , the non-targeted tissue is monitored during treatment. For example, the non-targeted tissue can be monitored by electrical stimulation or other methods. If an adverse reaction is detected, the treatment element can be moved or the treatment stopped. 
     In embodiments in which the phrenic nerve is paced, during the ablation, if a reduction of the force of diaphragmatic contraction is detected by palpation, the position of the catheter in the SVC can be verified. If the location was identified as low risk and the catheter pacing the phrenic nerve has moved on fluoroscopy, the catheter can be repositioned. If a weakening of the diaphragm is detected fluoroscopically, the treatment element can be forcibly deflated and the ice shell fractured with saline administered through the distal port. If the diaphragm is moving normally on fluoroscopy, the treatment element can be repositioned in the SVC to regain phrenic nerve capture and the ablation continued. If the case was identified as intermediate risk and the diaphragmatic contraction weakens by palpation, the treatment element can be deflated and the ice shell fractured. Fluoroscopy can be performed to assess the motion of the right hemidiaphragm. 
     At block  1414 , the targeted tissue site is assessed, and in certain cases, additional treatment provided. In some embodiment, once an initial treatment is completed, the tissue at the targeted tissue site can be examined to determine whether additional treatment is to be provided. For example, electrical signals near the targeted tissue site can be monitored. 
     With respect to embodiments in which cardiac arrhythmia is being treated, the presence of PVI can be assessed. In some embodiments, PVI can be assessed using the mapping portion of the integrated treatment device, evaluating for the presence of local PV electrograms to determine the presence of entrance block, and pacing the pulmonary vein to determine the presence of exit block. In response, if persistent PV conduction is detected, additional treatment can be provided. For example, in some cases, the earliest site of entrance conduction into the PV/PV antrum can be targeted with the treatment device. Additional sites can be treated based on additional assessments for PVI. In addition, as part of the assessment, adenosine can be administered after PVI to determine the presence of dormant conduction. Following the administration of the adenosine, if PV conduction is detected, additional treatment can be provided. For example, the earliest site of entrance conduction into the PV can be targeted with the treatment device. In some cases, the presence of PVI can be repeatedly assessed until there is no evidence of dormant conduction. 
     Fewer or more steps can be included as desired. For example, if the risk level is high or intermediate, the treatment element can be moved, distal portions of the treatment element can be deflated and/or used as warming portions, and/or electrodes can be activated to create a warming region, etc. In addition, during treatment for cardiac arrhythmia, the phrenic nerve can be monitored, etc. Furthermore, it will be understood that any one or any combination of the steps described above with respect to  FIGS. 7 and 8  can be used. For example, multiple images can be taken at different times and at different orthogonal views, etc. 
     In addition, although specific embodiments are described with respect to identifying the location of the phrenic nerve during treatment of cardiac arrhythmia, it will be understood that routine  1400  can be used to identify non-targeted tissue near targeted tissue sites during treatment of other areas of the body. For example, the greater and lesser cavernous nerves (non-targeted tissues) pass nearby the prostate gland and can be injured during prostate surgery causing erectile dysfunction. By identifying the location of the nerves prior to treatment, the likelihood of injury can be reduced. 
     Mapping Overlay 
       FIGS. 15A-15C  are diagrams illustrative of a mapping overlay  1501 , which can form part of a mapping device or mapping catheter. The mapping overlay  1501  can be used in association with a treatment device, such as the treatment devices  312 ,  404 ,  504 , form part (e.g., the mapping portion) of the integrated treatment devices  1102 ,  1202 ,  1302 , and/or be used in any one or any combination of the routines  700 ,  800 , and/or  1400 . 
     In the illustrated embodiment, the mapping overlay  1501  includes a wire mesh  1502  extending beyond a catheter body  1508 , which can also be referred to as a lining or tube, and multiple sensors/electrodes  1504  (individually referred to as sensor/electrode  1504 ). A distal end of the mesh  1502  can be coupled to a cap  1506  and a proximal portion of the mesh  1502  can be coupled to, or encircled by the body  1508 . In some embodiments, an interior diameter of the mesh  1502  can be sized to enable a treatment device, such as treatment devices  312 ,  404 ,  504  to pass therethrough. In certain embodiments, an exterior diameter of the mesh  1502  and body  1508  can be sized to pass within an inner diameter of a sheath  1510 . 
     The cap  1506  or corresponding cap in other embodiments may be occlusive, or may be provided with a central lumen or aperture to accommodate advance of the catheter over a guidewire as is understood in the art. In an over the wire implementation, the catheter may also be provided with a guidewire lumen extending between a proximal guidewire port and the aperture in the distal cap. The guidewire lumen may extend, for example, through the catheter shaft  1603  (See, e.g.,  FIG. 17A ). 
     The mesh  1502  can include a plurality of interwoven or braided wires  1503  (individually referred to as a wire  1503 ). In certain embodiments, the mesh can form a tubular structure. In some embodiments, the wires  1503  can be wound helically and form a perimeter of a lumen. In certain cases, the mesh can include longitudinal wires running lengthwise with the lumen and woven wires that weave between the longitudinal wires. In some cases, the wires can be interlaced with each other like a braid. Any number of wires  1503  can be used for the mesh  1502 . In some cases, the mesh  1502  can be cylindrical with an interior lumen. However, it will be understood that the mesh  1502  can be formed in any shape. In some embodiments, the minimum number of wires  1503  is equal to at least the number of electrodes  1504  used with the mesh  1502  or twice the number of electrodes  1504  used with the mesh  1502 . For example, if 32 electrodes  1504  are attached to the mesh  1502 , the mesh can be made up of 32 wires  1503  or 64 wires  1503 . However, it will be understood that the mesh  1502  can include fewer or more wires  1503  as desired. 
     In some embodiments, the wires  1503  of the mesh  1502  can be made of steel, coated copper polyester, nitinol, composite material, platinum, platinum coating over nitinol core, tungsten (strength), or other biocompatible metal or conductor. In some embodiments, the wires can be multi-conductor wires or cables (non-limiting examples: coaxial cable with one more cores, multi-ribbon wire, etc.). Further, the wires  1503  can be coated in Teflon, polyester polyimide kapton, or other biocompatible electrical insulator, such as plastic, etc. 
     In some cases, the mesh  1502  can include a combination of different types of wires  1503 . For example, the mesh  1502  can include a one or more conductor wires, one or more structural wires, and/or one or more radiopaque wires. The different wires can be made of different material and can be braided together to provide the mesh  1502  with different characteristics. For example, the conductor wires (non-limiting examples: copper) can be used to provide an electrical signal to and/or from the sensors  1505 , the structural wires (non-limiting examples: steel, nitinol, tungsten) can be used to provide the mesh  1502  with rigidity and structure, and the radiopaque wires (non-limiting examples: tungsten, platinum, gold-plated) can be used to increase the visibility of the mesh  1502  when inserted into a patient. In certain cases, the sensors  1504  are coupled only to the conductor wires and are not coupled to the structural wires or the radiopaque wires. In certain cases, a conductor wire can also be used as a structural and/or radiopaque wire. In some cases, the majority of the wires of the mesh  1502  can be conductor wires. In certain embodiments, approximately one fourth of the wires can be structural wires. However, it will be understood that the mesh can include any combination of conductor wires, structural wires, and/or radiopaque wires. 
     The mesh  1502  can be constructed to expand/collapse passively or actively. To expand passively, the mesh  1502  can rely on a force applied to it from another object proximate thereto, such as a treatment element of a treatment device. For example, in some embodiments, as the treatment element enlarges, it can exert a deformation force on the wires  1503 . In response to the deformation force, the wires  1503  can deform and the mesh  1502  expand, as illustrated in  FIG. 15B . 
     Similarly, to collapse passively, the mesh  1502  can rely on a force applied to it from another object proximate thereto, such as the sheath  1510 . In some embodiments, once the deformation force from the treatment element is withdrawn due to a deflation and/or removal of the treatment element, the mesh  1502  can retain the shape created by the deformation force of the treatment element, or otherwise not return to its pre-deformed shape absent an additional force. In such embodiments, if the mesh is in an expanded state (as shown in  FIG. 15B ) due to a previous deformation force applied thereto by a treatment element, the mesh  1502  can be passively collapsed using a force applied thereto by the sheath  1510 . For example, as the mapping overlay  1501  is withdrawn from the target site and pulled through the sheath  1510 , a deformation force on the mesh  1502  from the sheath  1510  can cause the mesh  1502  to deform back to a predetermined shape or a shape similar to the predetermined shape. 
     In some embodiments, the mesh  1502  can collapse passively based on the pliability characteristics of the wires  1503 . For example, the wires  1503  can be constructed to have sufficient spring such that once a deformation force, such as from a treatment element, is removed from the wires  1503 , the wires  1503  return to a predetermined shape or similar thereto. In some cases, the wires  1503  can return to a predetermined shape unless a deformation force that satisfies a wire pliability threshold is applied. If the deformation force satisfies the wire pliability threshold, the wires  1503  can maintain their new shape or not return to the predetermined shape. 
     To expand or collapse actively, the wires  1503  can be controlled by a user. For example, the user can manipulate a lever or knob to actively adjust the expansion and/or collapse of the wires. The lever or knob can enable the user to expand or collapse the mesh  1502  as desired. For example, moving a lever or slider button in one direction, such as a longitudinal axis of the mapping overlay can cause the mesh  1502  to expand and moving the lever or slier button in a different direction, such as an opposite direction, can cause the mesh  1502  to collapse. 
     In some embodiments, to form the mapping overlay or mapping catheter, an inner layer, such as a polymer or other flexible material, can be heat shrunk, or otherwise coupled or bonded, around a tube, such as a mandrel. One or more wires  1503  with or without electrodes can be pre-braided in a tubular structure and slid over the first layer on the mandrel to form a second layer. The mesh of wires  1502  can extend past a distal end and proximal end of the inner layer and the mandrel. A third layer can be laminated over the portion of the wires that that are on top of the mandrel. To provide structural or mechanical properties such as flexibility, pushability, and torqueability, other layers can be added to control said properties. After the layers are placed over the wires  1503 , the mandrel can be removed. Accordingly, a distal portion of the mapping catheter can include the mesh of wires without an inner layer or outer layer, the middle portion (or body  1508 ) of the mapping catheter can include the mesh of wires sandwiched between the inner layer and outer layers of material, and a proximal portion of the mapping catheter can include the mesh  1502 . In some embodiments, 6-12″ of mesh can extend beyond the body  1508  of the mapping catheter at both the distal end and proximal end. However, it will be understood that the mapping overlay can be configured to have more or less mesh extend beyond the body  1508 . Furthermore, it will be understood that the mapping overlay can be constructed in a variety of ways. As another example, the body  1508  can extend along the entire length of the mesh  1502 . A distal end of the body  1508  and mesh  1502  can be dipped in acid to remove the inner and outer layers of the body  1508  from the mesh  1502 , etc. 
     In some embodiments, the mesh  1502  can provide a known spatial relationship between the electrodes  1504 . Preferably the electrodes are maintained with substantially constant spacing in between, in at least the circumferential direction and preferably also in the axial direction. In addition, the mesh  1502  can provide the mapping overlay with flexibility, conformability and radial expansion control, which enables conformability to the surrounding tissue, which can increase the likelihood of an accurate mapping of surrounding tissue. 
     With continued reference to  FIGS. 15A-15C , one or more sensors and/or electrodes  1504 , described in greater detail above, can be coupled to the mesh  1502 . A sensor/electrode  1504  can be coupled to a wire  1503  by using a biocompatible adhesive, bonding agent, welding, soldering, plated over exposed copper, or other coupling that is biocompatible and electrically conductive, etc. In some cases, to apply a sensor and/or electrode to a wire  1502 , a portion of the insulation of the wire can be removed. The exposed portion of the wire can be gold plated or have a stainless metal applied as the electrode  1504 . In certain cases, a portion of the wire  1502  can be cut and a resistive material can be applied to provide a heating electrode. 
     In some cases, a single sensor/electrode  1504  can be coupled to (only) one of the wires  1503  of the mesh  1502 . For example, a wire  1503  with a sensor/electrode  1504  can terminate at the cap  1506 . In such embodiments, the wire  1503  and electrode  1504  can act as a passive sensor or voltmeter.In certain cases, a sensor/electrode  1504  can be coupled to more than one wire  1503 . For example, the sensor/electrode  1504  can be affixed to a first wire carrying an electrical signal to or from a controller. The first wire can be electrically coupled to a second wire to carry the signal in the opposite direction as the first wire (non-limiting example: first wire carries electrical signal distally from controller and second wire carries electrical signal back to the controller, or vice versa). In some embodiments, more than one sensor/electrode  1504  can be coupled to a single wire  1503 . In embodiments, where more than one electrode  1504  is coupled to a wire, the wire can be a multi-conductor wire and/or the electrodes  1504  can be read using multiplexing. The wire(s)  1503  coupled to the relative sensor/electrode  1504  can provide the sensor/electrode  1504  with an electrical connection thereby enabling the control of the sensor/electrode  1504  and the ability to receive data from the sensor/electrode  1004 . 
     Additionally, in some embodiments, the wire(s)  1503  can keep the sensor/electrode  1504  in place. For example, the mesh  1502  can provide a 3D fixation for the sensor/electrode  1504 . As such, the location of the sensor/electrode  1504  relative to the treatment device can be known with greater accuracy and/or dependability. 
     When more than one sensor/electrode  1504  is used, the sensors/electrodes can be located in a variety of configurations. In some embodiments, the sensors/electrodes  1504  can be evenly (or unevenly) spaced from each other. In certain embodiments, the sensor/electrodes  1504  can be located on the mesh  1502  such that they are distal to or (approximately, such as ±5 cm) coaxial with the portion of a treatment element of a treatment device with the largest circumference or perimeter when the treatment element is expanded (e.g., the meridian of the treatment element). However, it will be understood that the sensor/electrodes  1504  can located anywhere on the mesh  1502 . For example, one or more sensor/electrodes  1504  can be located proximal to the meridian of the treatment element. Similarly, the sensor/electrodes  1504  can be located along an entire portion of a treatment element of a treatment device and/or distal or proximal to the treatment element of a treatment device. Typically, at least about 20 or 30 or more electrodes are provided. In some implementations, at least about 48 or at least about 64 electrodes are provided depending upon physical construction constraints and intended clinical performance. 
     A mono conductor filament may only support one unique electrode. But a filament having more than one distinct electrically conductive trace, each unique trace can support another unique electrode. Multiple conductor filaments may be provided, for example, by layering alternating concentric conductor and insulator layers, and electrically connecting each conductive layer with a unique electrode spaced apart along the filament. Insulation material may be applied at each electrode site, in a manner to retain electrical separation between the electrode and all but one of the conductive layers. 
     In some embodiments, the sensors/electrodes  1504  can be arranged into one or more groups  1505 A,  1505 B,  1505 C of sensors/electrodes  1504 . For example, multiple sensors/electrodes  1504  can be located at approximately the same distance from the cap  1506  such that a group (e.g., groups  1505 A,  1505 B,  1505 C) of sensors/electrodes  1504  form a ring. In such an embodiment, when the treatment element of a treatment device is enlarged (as shown in  FIGS. 15B, 15C ), the group  1505 A,  1505 B,  1505 C of sensors/electrodes  1504  can form a ring around a particular portion of the treatment element, such as a particular circumference or perimeter around the treatment element. In the illustrated embodiment of  FIG. 15 , the sensor/electrodes  1504  are arranged into three groups  1505 A,  1505 B,  1505 C. The sensor/electrodes  1504  within a group  1505 A,  1505 B,  1505 C can be the same type of sensor/electrode  1504  and/or a combination of different sensor/electrodes  1504 . At least one group of sensors is preferably located within the distal most 30% or 20% or 15% of the axial length of the distal end of the expandable mesh. In some implementations, no sensors are provided on at least the proximal most 30% or 45% of the axial length of the expandable portion of the mesh. 
     Furthermore, in some embodiments, one group of sensor/electrodes  1504  can be offset with respect to a proximate group of sensor/electrodes  1504 . For example, in the illustrated embodiment of  FIG. 15 , the group  1505 A of sensor/electrodes  1504  is offset with respect to the group  1505 B of sensor/electrodes  1504  such that if all of the sensor/electrodes  1504  of groups  1505 A,  1505 B were on the same axis, the sensor/electrodes  1504  from group  1505 B would be in between the sensor/electrodes  1504  of group  1505 A. In certain embodiments, the groups of sensor/electrodes  1504  are not offset, such that if all of the sensor/electrodes  1504  were on the same axis, a sensor/electrode  1504  from group  1505 B would be co-located with a sensor/electrode  1504  of group  1505 A. 
     One implementation of the electrode array is illustrated in  FIG. 15D . A plurality of electrodes are arranged in transverse planes on the expandable basket. The planes may be distinct groupings around the periphery and spaced axially apart, or may be portions of a spiral electrode pattern that extends continuously around the basket. The dimension A of the distal advance segment of the catheter may be varied depending upon the desired functionality, so the B, C, D and E electrode planes may be located relative to the A plane by subtracting out the A variable as will be understood by one of skill in the art. Preferably the B, C and D planes will be populated with electrodes. The D plane and even more proximal electrodes may not be necessary in a pulmonary vein mapping catheter since they may not be in contact with tissue. Electrodes proximal of the central transverse meridian of the basket may be desirable in a mapping environment wherethe basket is advanced through a small opening into a larger hollow organ such as the bladder where it will be expanded and retracted proximally up against the wall surrounding the opening. 
     The distal advance segment A may be provided with one or more reference electrodes or sensor such as a pressure, temperature or other sensor to provide feedback relating to the progress of the mapping or ablation. For example, at least one or two or more thermocouples may be provided on the advance segment A or mesh, for monitoring temperature. See, e.g., US patent publication No. 2015/0119868 to Lalonde, et al., entitled Feedback System for Cryoablation of Cardiac Tissue, the disclosure of which is hereby incorporated in its entirety herein by reference. See also U.S. Pat. No. 7,070,594 to Sherman, entitled System and Method for Assessing Ice Ball Formation During a Cryoablation Procedure, the disclosure of which is hereby incorporated in its entirety herein by reference. Impedance may be determined from electrodes placed on the distal advance segment shaft just past the balloon and the proximal shaft, just proximal to the balloon. A distal reference electrode and the electrodes positioned on the balloon may be used to determine regional changes in impedance and thus regional dosing, or electrodes on the distal advance segment and catheter shaft just proximal to the mesh may allow determination of global impedance changes that will determine PVI. 
     The cap  1506  can be coupled with a distal portion of the mesh  1502 . In some embodiments, a distal portion of the wires  1503  can be coupled to the cap  1506 . For example, an end of each wire  1503  can be may be adhered or bonded to the cap  1506  using a biocompatible adhesive, bonding agent, welding, soldering, crimping, etc. As yet another example, a portion of the wire  1503 , such as an end or middle portion, can be wound around the cap  1506  or inserted through a hole in the cap  1506 . In some embodiments, the cap  1506  can provide electrical connections between wires  1503  to enable a completed circuit to be formed for each sensor/electrode  1504 . In some cases, the cap can include an inner lumen large enough to fit a guidewire. For example, the inner lumen can be between 0.032″-0.035″ in diameter. It will be understood that lumen&#39;s diameter can be other widths as well. 
     In certain embodiments, the cap  1506  can include an inner portion and an outer portion. The inner portion can be used to couple the cap  1506  to the mesh  1502  and to the treatment device. The outer portion can cover the inner portion to protect the interconnections from the environment and can have an atraumatic shape to avoid damaging the tissue when inserted into a patient. In some embodiments, the cap  1506  can include a central lumen  1512 . The central lumen  1512  can be sized for a guidewire or portion of a treatment device. In some embodiments, the central lumen  1512  can include a sphincter that can be broken when the treatment device is inserted. 
     In addition, the cap  1506  can be coupled with a distal end of the treatment device. For example, the cap  1506  can include a protrusion or indentation that can be used to engage with the treatment device to prevent unwanted relative movement between the mapping overlay and the treatment device when the treatment device is in use. In some cases, an interior portion of the cap  1506  can include threads that can engage with a distal end of the treatment device. The cap  1506  and the treatment device can be disengaged by twisting and/or pulling the two apart. 
     The body  1508  can be made of one or more layers of polymer or other flexible material. In some embodiments, the body  1508  can be coupled with a proximal portion or middle portion of the mesh  1502 . For example, as described above, the body  1508  can include one or more inner layers of polymer and one or more outer layers of polymer and a portion of the mesh  1502  can be located between the inner/outer layer(s). 
     In certain embodiments, a proximal portion or middle portion of the mesh  1502  can be located within the body  1508  and/or sandwiched between layers of the body  1508 . In some cases, the mesh  1502  can extend at least along the length of the body  1508  within the sheath  1510 . In some embodiments, the mesh  1502  can extend beyond a distal end of the body  1508 , as illustrated in  FIG. 15A . Furthermore, the mesh  1502  can extend beyond a proximal end of the body  1508  (not shown). 
     The outer portion of the body  1508  can be coated in Teflon, hydrogel, or other lubricious material, to reduce the amount of friction between the body  1508  and an outer sheath  1510 . In certain embodiments, the body  1508  can also include a junction box for receiving the electrical signals from the sensors. The junction box can be located at a proximal end of the body  1508  that is not inserted into a patient during a procedure. 
     When the mesh  1502  expands either passively or actively, its length can decrease. In some embodiments, as the length decreases, the body  1508  can be pulled towards the cap  1506 . 
       FIGS. 15B and 15C  are diagrams illustrating the mesh  1502  of the mapping overlay  1501  in an expanded state, which can be caused by the enlargement of a treatment element of a treatment device. As described above, in the expanded state, the sensor groups  1505 A,  1505 B,  1505 C can form a ring around different portions of the treatment element of the treatment device.  FIGS. 15B and 15C  further illustrate the helical nature of the windings of the wires  1503  and the coupling between a sensor  1504  and a wire  1503 . 
       FIGS. 16A-16C  are diagrams illustrating embodiments of the mapping overlay  1501  and a treatment device  1602  in different configurations and positions. The treatment device  1602  can be similar to the treatment devices  312 ,  404 ,  504  described previously and can include a treatment element  1604  to treat a target site. 
     In some embodiments, the mapping overlay  1501  and treatment device  1602  can be implemented as part of a single catheter. In certain embodiments, the mapping overlay  1501  and the treatment device  1602  can be implemented as separate devices, such as two distinct catheters and/or a sheath and a catheter. For example, the mapping overlay  1501  can be sized such that the treatment device  1602  fits within an inner lumen of the mapping overlay  1501 . 
     In the illustrated embodiment of  FIG. 16A , the sheath  1510  is shown with the cap  1506  of the mapping overlay  1501  protruding from a distal portion thereof. The illustrated configuration of  FIG. 16A  can represent a scenario in which the sheath  1510  has been placed at a target site or proximate to a target site and the mapping overlay  1501  and/or the treatment device  1602  have been guided to the target site by the guidewire  1606  through the sheath  1510 . For example, in a cardiac ablation procedure, the sheath  1510  can be inserted near the groin and follow the femoral vein and inferior vena cava to the heart and the mapping overlay  1501  and treatment device  1602  can be inserted inside the sheath  1501  and follow the sheath  1501  to the heart. A non-limiting example of a sheath is the FlexCath® Steerable Sheath available from Medtronic. Destino Twist® deflectable steerable guiding sheath from Oscor; Agilis NXT steerable introducer sheath from St. Jude; etc. 
     In the illustrated embodiment of  FIG. 16B , the mapping overlay  1501  and the treatment device  1602  are visible protruding from the sheath  1510 . The configuration illustrated in  FIG. 16B  can represent a scenario in which a user is preparing to treat the target site. In the illustrated embodiment, the treatment device  1602  including the treatment element  1604  is visible within the mesh  1502  of the mapping overlay  1501 . As described in greater detail above, the treatment element  1604  can be used to treat the target site using RF, HIFU, laser, hot balloon, and/or cryotherapy. (electroporation) In some embodiments, the mapping overlay  1501  can be sized such that it generally extends across the entire length of the treatment element  1604 . 
     In the illustrated embodiment of  FIG. 16C , the treatment element  1604  of the treatment device  1602  is shown in an expanded state. The configuration illustrated in  FIG. 16C  can represent a scenario in which a user has filled the treatment element with a gas in preparation for treating the target site. In such a configuration, the mapping overlay  1501  can be used to map the target site and/or to monitor the effect of treatment on the target side, as described in greater detail above. As a non-limiting example, the sensor/electrodes  1504  can be used to pace tissue at the target site, such as a phrenic nerve, monitor a temperature at the target site, etc. 
     As illustrated in the  FIG. 16C , when the treatment element  1604  is enlarged, the mesh  1502  in the area of the treatment element can expand as well. The expansion of the mesh  1502  where the treatment element  1604  portion can induce a force on the remaining portion of the mesh  1502  which can pull the body  1508  further out from the sheath  1510 . Accordingly, in some embodiments, the interior of the sheath  1510  and the exterior of the body  1508  can be constructed to have a low friction coefficient such that the body  1508  can slide with relative ease when treatment element  1604  is expanded. 
     Furthermore, as described in greater detail above, the wires  1503  of the mesh  1502  can be constructed to achieve a particular level of pliability such that when the treatment element  1604  is deflated, the mesh  1502  can retain its expanded shape. In such an embodiment, the mesh  1502  can retain the expanded shape until pulled inside the sheath  1510 . The force exerted on the mesh  1502  by the sheath  1510  can flatten the mesh  1502  back to a predetermined shape or similar to a predetermined shape. It will be understood, however, that the mesh  1502  can be constructed so that when the treatment element is reduced in size and/or removed, the mesh  1502  can return to its predetermined shape or similar thereto 
     In some embodiments, the mapping overlay  1501  and treatment device  1602  can be placed within an outer sheath and can be independently operated. For example, the mapping overlay  1501  can be independently moved. Similarly, the treatment device  1602  and treatment element  1604  can be independently moved, collapsed, and/or expanded as desired. 
     A simplified, coaxial system is illustrated in  FIGS. 17A and 17  B. Referring to  FIG. 17  A, there is illustrated a mapping overlay catheter  1501  comprising an elongate tubular catheter body  1508  extending between a proximal end (not illustrated) and a distal end which carries a wire mesh basket  1502 . The wire mesh basket  1502  comprises a plurality of wires  1503  as has been discussed. Wires  1503  may comprise a mix of electrically conductive wires and structural support wires as discussed elsewhere herein. 
     The wire mesh basket  1502  is convertible between a first, reduced crossing profile configuration for transluminal navigation and a second, enlarged configuration as illustrated in  FIG. 17A . Each of the wires  1503  in the basket portion of the device has a proximal end carried by the catheter body  1508  and a distal end at cap  1506 . The wire basket may be carried within the tubular sheath  1510  for transluminal navigation. 
     The catheter body  1508  includes a lumen  1509 , for axially movably receiving a treatment device  1602 . Treatment device  1602  includes a treatment catheter  1603 . Treatment catheter  1603  extends between a proximal end (not illustrated) and a distal end which includes a treatment element  1604 . In the illustrated environment, treatment element  1604  comprises a radially expandable structure such as a balloon, for delivering an ablation initiator such as heat, cold or in a microporous implementation, an ablative agent such as any of a variety of drugs or chemical agents known in the art. In one implementation, treatment element comprises a cryogenic delivery element which may be carried within a cryo-balloon. 
     In the example of  FIGS. 17A and 17B , the mapping overlay  1501  is trans vascularly advanced to a treatment site. The sheath  1510  is proximally retracted to expose the wire mesh basket  1502 . The wire basket may self expand, as shown in  FIG. 17A . The treatment device  1602  may there after be advanced via the lumen  1509  into the interior of the basket  1502  and inflated as shown in  FIG. 17B . The system thus permits electrically conducting functions such as mapping to be accomplished via wires  1503 , while the delivery of therapy originates with the treatment element  1604 , and is propagated from a position inside of the basket  1502  through openings defined between adjacent wires  1503  and to the target tissue. 
     In any of the embodiments disclosed here in, the basket  1502  may self expand, followed by placement of the treatment device. Alternatively, the basket  1502  maybe forcibly expanded by inflation of the treatment device. 
     For simplicity, the embodiment of  FIGS. 17A and 17B  illustrate a plurality of wires  1503  extending in an axial direction. However, circumferential spacing between adjacent wires  1503  may not be maintained upon radial expansion unless circumferential support is provided. Thus, referring to  FIGS. 18A-C , at least one and generally at least about five or 10 or 20 or more circumferential struts or filaments  1520  (also referred to herein as tethers) are provided. Circumferential filaments are connected to each of the axially extending wires  1503  (also referred to herein as splines) to assist in maintaining spacing between adjacent wires  1503 . 
     Circumferential filaments  1520  may comprise a warp or a weft portion of a weave as has been previously discussed. The circumferential spacing filaments  1520  may extend at an angle within the range of from about 10 or 15 degrees to about 90 degrees from the longitudinal axis, measured in the expanded configuration. Generally the angle will be at least about 45 degrees or 60 degrees or more from the longitudinal axis. Filaments  1520  may each reside in a transverse plane (90 degrees from the longitudinal axis in the fully expanded configuration) as illustrated in  FIGS. 18A-18C , and circling the full circumference of the basket  1502 . 
       FIG. 18B  illustrates a self expanding basket  1502 , following retraction of the sheath  1510 . A treatment catheter  1603  has been distally advanced to position a treatment element  1604  within the basket  1502 . As illustrated in  FIG. 18C  the treatment element  1604  may be inflated within the basket  1502  at the treatment site, to deliver ablative therapy through the basket. 
     Depending upon various considerations including the nature of the treatment catheter  1603  and the desired crossing profile of the catheter body  1508  or delivery sheath  1510 , it may be desirable to introduce the treatment element  1604  into the cavity defined by the basket  1502  through an opening in the mesh rather than coaxially through the catheter body  1508 . See  FIGS. 19A and 19B . In this configuration the treatment catheter may approach the basket from the proximal side, outside of and parallel to the catheter body  308  throughout the length of the two catheters in the case of a single vascular access point. Alternatively, the overlay catheter  1508  may be introduced at a first vascular access point and the treatment catheter  1603  introduced at a second, different access point, with both converging in a common vessel at (e.g., proximal to) the basket  1502 . 
     In general, methods and devices in accordance with the present invention may be described in accordance with the following lexicón.
         Ablation Fixture
           Device that guides the ablation energy (e.g. laser) to specific points on a target (e.g. Conductive Filament).   One embodiment is expected to be a generally spherical device that fits inside the mesh much as the Mandrel does, but contains guide pins and concave areas with reflective surfaces to concentrate the energy for ablation to small, specific locations.   
           Cap
           A distal Terminal Construct that is cup-like, shaped to receive the distal free ends of the Mesh.   In the present embodiment, the Cap is a plastic device that is shaped like a cylinder with one (proximal) end open.   
           Conductive Filament
           A component of the Mapping Device.   Woven into the Mesh to lend sensing capability to the Mapping Device.   Each contains one or more mapping electrodes.   The present embodiment the Mapping Device includes 12 Conductive Filaments.   In one embodiment, the Conductive Filaments are made of 0.006″ Au-DFT®-92% NiTi (Fort Wayne Metals)   Conductive filaments extend proximally throughout the length of the catheter.   
           Delivery Catheter
           The catheter through which the Treatment Balloon and Mesh are delivered to the Target Tissue.   In one embodiment, the Delivery Catheter may be a Medtronic FlexCath.   
           Filament
           A thin wire, suture, or fabric ribbon that can be used to create a Mesh   Two types of Filament are described in this disclosure: Support Filament and Conductive Filament. The two may be the same or different.   Filaments may be made of a variety of materials and may be selected to be radio-opaque and or structurally supportive.   
           Insulation
           An electrical insulation applied to all Filaments of the Mapping Device.   In one embodiment, the insulation may be Pyre M.L. natural polyimide (Fort Wayne Metals/RC 5019: 0.0005-0.0015″ total build thickness applied with Cure Profile #10)   Conductive Filaments may be made of a variety of materials including but not limited to Parylene, polyimide, polytetrafluoroethylene, and diamond.   
           Mandrel
           Device that is placed inside the braided Mesh prior to shape setting, which serves as the form for the shape set.   In one embodiment, it may be a solid, spherical device.   
           Mapping Device
           A catheter-based endocardial mapping device that captures electrographic data.   In one embodiment, it features a 48-wire mesh arranged in a generally spherical pattern.   
           Mapping Electrode
           A site of conductive metal capable of capturing an electrophysiologic signal.   In one embodiment, electrodes are formed by removing (e.g. ablating) the insulation from the Conductive Wires in select locations.   In one embodiment, there are 12 mapping electrodes, one on each   
               

     Conductive Wire of the Mapping Device.
         Mesh
           A woven network of Filaments that wraps around the Treatment Balloon and conforms it its shape.   In one embodiment, the tether is made of 12 Conductive Filaments and 36 Support Filaments.   In one embodiment the Filaments are woven in a “2-over-1-under” basket weave configuration.   
           Ring
           A Terminal Construct that is a structurally stable, closed loop shaped to attach to the free ends of the Mesh.   The Ring may be made of Filament material, plastic, metal, or ceramic.   
           Support Filament
           A component of the Mapping Device.   Woven into the Mesh to lend structural integrity to the Mapping Device.   In one embodiment the Mapping Device includes 36 Support Filaments.   In one embodiment, the Support Filaments may be made of #1 NiTi (Fort Wayne Metals).   
           Terminal Construct
           A feature at the distal end of the Mesh, which captures the free ends of the Filaments.   In one embodiment, the Terminal Construct is a convex distally-facing plastic Cap.   
           Treatment Balloon
           An expandable balloon catheter device that is capable of entering vessels and/or organs and delivering energy and/or drugs to a specific site.   In one embodiment, the Treatment Balloon may be a cryoballoon for ablation of the heart&#39;s atrial tissue.   
               

     As recited above, the Mesh exhibits both conformity and structural integrity in a low crossing profile collapsed configuration (profile when passing it through vasculature or tissue) and compatible with the requirements of endocardial surgery (biocompatible, non-thrombogenic, non-particulate). 
     To achieve structural integrity, any of a variety of alloys such as stainless steel and shape-memory nickel titanium that might serve as the Support Filaments. These are preferably fine but somewhat stiff and capable of shape setting. #1 NiTi (Fort Wayne Metals) is suitable for this purpose. Support Filaments may be made of a variety of materials including but not limited to shape memory nitinol and other superelastic, shape memory alloys. 
     The Conductive Filaments preferably comprise a fine memory alloy wire capable of withstanding shape setting. In addition, it is preferably highly conductive so that electrographic signals can be detected. One suitable specialized magnet wire is a 0.006″ Au-DFT®-92% NiTi. Conductive Filaments may be made of a variety of materials including but not limited to Au-DFT®-92% NiTi, other types of nitinol, gold-plated stainless steel, platinum, silver, and similar materials. These materials may be layered coaxially in a single Filament to create conductive channels surrounded by insulative material. 
     Braid geometry of a first set of axially oriented filaments and a second set of circumferential filaments is configured to optimize adequate tissue contact. The pattern of braiding can alter the braid geometry. A 2:1 design ( FIG. 20A ) may ensure optimal tissue contact by buttressing the electrode against the tissue, when the electrode is properly placed. This is less optimal with a 1:1 braid pattern ( FIG. 20B ). Additional braid patterns may also be used. 
     In a 2:1 braid pattern, two filaments of a first set of filaments cross over (radially outside) and under (radially inside) a filament of a second set of filaments. The electrode may be located on the radially outside facing surface at a filament crossing point, such as on a double filament cross over, to optimize contact with adjacent tissue. The 2:1 weave is also useful for maintaining the preset (preferably approximately equidistant) circumferential spacing between adjacent electrodes. 
     While one embodiment includes 36 Support Filaments and 12 Conductive Filaments, this can be varied. The proportion of Support Filaments to Conductive Filaments may vary. The total number of Filaments in the braid may also vary, being greater or less than 48 Filaments. 
     The Mapping Electrodes may be formed in a variety of ways, beginning with ablation of the Insulation at small select locations. The exposed wires may then be used as-is for electrodes. Alternatively, another material may be applied to each ablated area to serve as a signal-capture surface. For example, a ring of conductive material such as a platinum alloy could be attached to a laser ablated window on the wire. Materials may include but are not limited to platinum alloy, iridium oxide and other similarly conductive alloys. 
     In one embodiment, there is one electrode (insulation window) per wire. In another embodiment, the conductive wire may be constructed of coaxially layered materials that allow for multiple channels to run along a single wire (from center: core, conductor, insulator, conductor, insulator). Thus could there be more than one electrode per wire. 
     In one implementation of the invention, the filaments are coated with an insulating material such as a polyimide prior to braiding, as it had the potential to survive the heat set. Various different formulations of polyimide and a variety of “cure profiles” (mainly time, temperature, and cycling of polyimide application) may be used. These polyimide treated Meshes would withstand heat set in the target range of 480° C.-500° C. if under a reductive gas such as argon or helium. When heat set under air, the Mesh is prone to oxidative damage appearing as cracks, peeling and pits. 
     There are several ways in which the distal tip of the device can be minimized. One may:
         Invert   This approach involves attaching the cap such that its top is oriented to face the Delivery Catheter, toward the proximal end of the device. Ends of the Mesh Filaments are inverted into the distal end of the Cap.   Retract   This approach involves attaching the cap such that its top is oriented to face distally, away from the Delivery Catheter. Ends of the Mesh Filaments are embedded into the Cap, which is then retracted to effective invert and then revert the mesh at the distal tip.   Tether to a Ring   This approach involves replacing the cap with a Ring, to which the ends of the Mesh Filaments may be tethered.       

     The Cap and Ring constructs presented in this disclosure were developed to be compatible with Treatment Balloon designs in development, which also aim to minimize size/profile of the distal tip. Examples of these designs can be found in the patent literature (e.g. U.S. Ser. No. 14/255,625 the entire contents of which are hereby expressly incorporated by reference herein). 
     Another aspect of the present invention relates to an algorithm that can be used to assess location of critical anatomical features relative to a medical diagnostic and/or treatment device. The primary value of such technology would be to improve patient outcomes by informing physician decision-making. Specifically, it is designed to help the physician to understand what amount (“dose”) of treatment is appropriate to sufficiently treat target tissue without causing collateral damage. 
     The invention arises from research on phrenic nerve protection during atrial ablation, but could be applied to other surgical interventions, as well. The inventor envisions the technology taking the form of software programs specific to particular clinical indications and the diagnostic as well as treatment modalities used to address them. These software programs could be integrated into console systems that are currently used for surgical planning and assessment during surgery. 
     This set of algorithms would be tailored to meet each indication by utilizing coefficients specific to the:
         Type of tissue being mapped;   Signal type and range utilized by the diagnostic mapping device; and   Treatment kinetics and dynamics.       

     This aspect of the present invention may be described with reference to the following lexicon.
         Artifact
           A signal occurring at a particular location on the Diagnostic Mapping Tool, resulting from the interaction of that tool with the tissue and the Treatment Device.   In one embodiment, the signal is related to a physical change such as formation of ice.   
           Diagnostic Mapping Tool
           A device or other tool used to determine the relative location of the Protected Tissue.   In one embodiment, the Diagnostic Mapping Tool is designed to capture electrograms.   
           Dose at Safe Distance
           The amount of treatment that would be administered when the Protected Tissue is so far from the treatment location that there is no risk of the treatment causing collateral damage to the Protected Tissue.   In one embodiment, the Dose at Safe Distance is an amount of treatment time.   
           Fractional Treatment Factor
           A coefficient applied to the Dose at Safe Distance.   Involves comparison between the safe distance of the Protected Tissue from the Treatment Device and that of the Protected Tissue from the Treatment Device/Diagnostic Mapping Tool.   In one embodiment the Fractional Treatment Factor is ratio of the current required to capture the Protected Tissue to the current to capture known to represent a safe distance.   
           Protected Tissue
           The tissue that the operator desires to locate and protect.   In one embodiment, the Protected Tissue is nerve tissue.   
           Treatment Device
           A device that delivers treatment, which may be include tissue manipulation, energy, and/or drug.   In one embodiment the Treatment Device may be co-located with the Diagnostic Mapping Tool.   
           Angle of Displacement
           Angle between bipolar midplane of an Interelectrode Space and Protected Tissue   
           Current Density
           Minimum amount of current per surface area required to excite the Protected Tissue.   
           Interelectrode Spacing
           Distance between two consecutive electrodes on a Diagnostic Mapping Device   
           Radius
           Distance between the Diagnostic Mapping Device and the excitable/Protected Tissue.   In one embodiment this is the distance between the Diagnostic Mapping Device and the Protected Tissue.   
               

     An algorithm is provided to determine information regarding the location of critical nerves that the surgeon would wish to avoid. 
     This information would assist the surgeon in determining placement and dosage of treatment so as to maximize impact while preventing collateral damage. In this way, it has the potential to accelerate treatment and improve outcomes. 
     In one embodiment the algorithm has been tailored for protection of the phrenic nerve during cardiovascular cryoablation procedures, such as ablation of atrial tissue for the treatment of atrial fibrillation. 
     Use of this algorithm requires a Diagnostic Mapping Device to be co-located with a Treatment Device. For example, the Diagnostic Mapping Tool may be a Constellation Basket (Boston Scientific) and the Treatment Device may be an Arctic Front Advance (Medtronic) cryoballoon. The Treatment Device may be inserted inside of the Diagnostic Mapping Tool as shown in  FIG. 21 , which depicts a Constellation mapping basket with Arctic Front Advance cryoballoon inserted. Merged devices are shown after application of the cryojets, which created ice around the devices. 
     As the two devices operate simultaneously, the algorithm dictates that, in cases where the phrenic nerve is considered to be at risk of injury because of proximity to the cryoballoon, the optimal dosage of cryotherapy will be driven by the moment at which the Diagnostic Mapping Tool (Constellation Basket) shows an Artifact indicative of localized ice formation. Specifically, the optimal treatment time will be the time to the formation of the Artifact plus the Fractional Treatment Factor multiplied by the full treatment time that would be applied, were the phrenic nerve not at risk. 
     This relationship may be expressed by the following equation:
         T o : Optimal Treatment Time       

         T   o   =T   a +[( I   t   /I   s )* T   s ]         T a : Time to Artifact   T s : Treatment Time at Safe Distance   I t : Current to Capture Protected Tissue (Rheobase)   I s : Minimum Current to Capture at Safe Distance       
     In this type of case, a phrenic nerve is typically considered to be at a safe distance from the cryoballoon if it captures at 20 mA or more. Therefore, the constant of 20 mA would be used as a constant value for I s . The full treatment time at this safe distance, (T s ) is generally believed to be 180 seconds. Therefore, the equation appears as: 
         T   o   =T   a +[( I   t /20 mA)*180 s] 
     Given this, it can then be concluded that, if the current required to capture the phrenic nerve (I t ) is 5 mA at a particular bipole on the Diagnostic Mapping Tool and an Artifact appears at that bipole 30 seconds (T a ) into the freeze cycle, then the optimal treatment time is: 
     
       
         
           
             
               
                 
                   
                     T 
                     o 
                   
                   = 
                     
                    
                   
                     
                       30 
                        
                       
                           
                       
                        
                       s 
                     
                     + 
                     
                       [ 
                       
                         
                           ( 
                           
                             5 
                              
                             
                                 
                             
                              
                             
                               mA 
                               / 
                               20 
                             
                              
                             
                                 
                             
                              
                             mA 
                           
                           ) 
                         
                         * 
                         180 
                          
                         
                             
                         
                          
                         s 
                       
                       ] 
                     
                   
                 
               
             
             
               
                 
                   = 
                     
                    
                   
                     
                       30 
                        
                       
                           
                       
                        
                       s 
                     
                     + 
                     
                       45 
                        
                       
                           
                       
                        
                       s 
                     
                   
                 
               
             
             
               
                 
                   = 
                     
                    
                   
                     75 
                      
                     
                         
                     
                      
                     s 
                   
                 
               
             
           
         
       
     
     In summary, a freeze time of 75 s at that location would maximize treatment time (opportunity for efficacy) while still preventing freezing to the point of phrenic nerve injury. 
     This calculation may be termed “segmental dosing” as it provides the time to therapeutic effect independently for each bipole on the Diagnostic Mapping Tool. If the artifact does not appear, then it can be predicted that the tissue at that location will not be effectively ablated and isolated. It should thus be possible to use the pattern and duration of artifacts on the Diagnostic Treatment Tool to predict isolation pattern. For example, if a completely circumferential ring of artifacts does not simultaneously or sequentially appear at the entrance to a vein, then the electrophysiologist can predict that the vein is not permanently isolated. The electrophysiologist may then remedy the situation by repeating the freeze or touching up the area with an alternative ablation modality, such as radiofrequency. 
     Referring to  FIG. 22 , the intensity of the Artifact appears to be related to the depth and size of the lesion. It appears to reliably follow the temperature curve reproducibly intensifying during freezing and diminishing during the thaw. 
     Referring to  FIG. 23 , this is the right superior pulmonary vein with balloon surface mapping. Arrow indicates pacing stimulus artifact and demonstrate pacing of the phrenic nerve from a remote structure—the superior vena cava (pacing does not capture the atrium). Visible from top to bottom are surface leads I, III, aVF, V1, 32 bipolar electrode pairs organized and color coded by spline. For example Spline A is aqua-colored with 4 bipoles: A1-2, A3-4, A5-6, A7-8). Electrograms (in the oval) are taken from the pulmonary vein and the antrum of the pulmonary vein, with the more distal electrodes (A1-2, B1-2 . . . H1-2) bipoles sampling the pulmonary vein. ABL 3-4 and ABL 1-2 are displayed but are not in use. 
     The electrogram of  FIG. 23  illustrates a single freeze in which maximum high impedance artifact is seen on B1-2, C1-2, C3-4, E1-2, E3-4, F1-2, G1-2, and G3-4. Notice the amplitude of the artifact differs from bipole to bipole. For example, B1-2 is lower amplitude than F1-2. Notice A and H splines have not developed the high impedance artifact. 
     The amplitude of the artifact is inversely related to the temperatures. See  FIG. 24A . As temperature decreases the amplitude of the artifact increases and vice versa. Thus, the amplitude and duration of the artifact are directly related to the depth and size of the lesion under the sampling bipolar electrodes. The high impedance artifact does not appear if the underlying tissue is not frozen. The artifact appears to reliably follow the temperature curve reproducibly appearing once the underlying tissues have frozen, intensifying during freezing and diminishing during the thaw until the artifact disappears completely. 
     This is the same ablation as shown previously, just after cryoablation has ceased. In this example, the amplitude of artifact diminishes from peak values viewed in  FIG. 22  once cryoablation ceases and the underlying tissues warm. The artifact will completely disappear once the tissues have completely thawed (not demonstrated here). 
     Capture threshold of PN at long pulse width (&gt;1 msec) give a value on the strength duration curve known as the rheobase. It is given as a current or voltage, in the case of constant current, the unit is mA. 

 
     REFERENCES 
     Jenkins, J M et. al. Use of the pill electrode for transesophageal atrial pacing.  PACE.  8:512. 1985. 
     The primary value of such technology would be to improve patient outcomes and quality of life by elevating the probability of complete isolation of unwanted electrophysiological connections during the first procedure in which they are treated. It is also believed to mitigate the risk of iatrogenic injury to non-target tissue such as the phrenic nerve. 
     The system generally comprises a mesh or set of splines that effectively wrap around the balloon and conform to its surface geometry. This would enable the surgeon to essentially map the surface of the balloon while treating the patient. 
     This sort of system would incorporate structural features that meet the following requirements:
         Provide point-to-point mapping of electrographic signal; and   Map tissue independently of balloon presence.   These requirements are met with the following technical strategies:   Producing a novel, stand-alone mesh that:
           Is packed around the balloon within a single catheter;   Can be reversibly advanced and released to expand;   With or without the balloon in the center.   
           Modifying an existing mapping device that is:
           A non-occlusive mapper consisting of splines;   Co-located with the treatment balloon, which is eased into the center of the mapper; and   In a separate delivery catheter from the treatment balloon.   
               

     This disclosure focuses on the latter, modification of an existing mapping device. 
     The mapping device and treatment balloon may be co-located in a variety of ways including:
         Placing the two separate catheter devices side by side; or   Coaxially aligning the two devices in a single catheter with the treatment balloon at the center and the mapping device surrounding it.       

     Continuity of Signal Before and After Merge 
       FIG. 26  shows an electrogram from Mapping Device prior to being merged with Treatment Balloon. Note aberrant signal at electrodes  7  and  8  on neighboring splines A and H. 
       FIG. 27  shows an electrogram from Mapping Device that is merged with operating Treatment Balloon. Artifacts of freezing at Splines B, C, E, F, G (dense waves) dissipate as the ice thaws. Artifacts on A and H have already dissipated revealing absence of aberrant signal that appeared on H  7 - 8  in  FIG. 1 . 
     Lexicon 
     Filament
         A thin wire, suture, or fabric ribbon that can be used to create a Tether of Mesh.   Must be biocompatible, non-thrombogenic, and not produce any particulate.   In the current embodiment, the Filament is made of non-resorbable suture.       

     Mapping Device
         A catheter based endocardial mapping device that captures electrographic data.   In the present embodiment, it features 8 splines arranged an generally spherical pattern.       

     Mapping Electrode
         A site of conductive metal capable of capturing an electrophysiologic signal.   In the present embodiment, there are 8 copper mapping electrodes on each spline.       

     Ring
         A Terminal Construct that is a structurally stable, closed loop shaped to attach to the free ends of the Mesh.   The Ring may be made of Filament material, plastic, metal, or ceramic.   The embodiment of the Ring has yet to be specified.       

     Spline
         A long, thin arm of a device.   May be a component of a mapping device.   Contains one or more mapping electrodes.   In the present embodiment, each spline contains 8 electrodes spaced evenly along its length       

     Support Mesh
         A network of Filaments or textile in a mesh configuration that connects Splines to one another   Support Mesh filaments may be made of a variety of materials including but not limited to suture, fine wire, textile threads, or non-woven textile.       

     Tether
         A Filament or Ring that connects one Spline to another   Tether Filaments may be made of a variety of materials including but not limited to suture, fine wire, or fabric.   In the current embodiment, the Tether is a Filament of non-resorbable suture.       

     Treatment Balloon
         An expandable balloon catheter device that is capable of entering vessels and/or organs and delivering energy and/or drugs to a specific site.   In the present embodiment, the Treatment Balloon is a cryoballoon for ablation of the heart&#39;s atrial tissue.       

     Structural Support: Tethered Splines 
     The circumferential tethers lend structural integrity to the Mapping Device while still allowing it to collapse into a very small diameter when needed. This occurs in two ways. First, the Tethers retain the Splines in relative positions, evenly spaced in a spherical configuration that can guide the Treatment Balloon to a central location within it. The Tethers are also expected to add structural strength. This provides the surgeon with a flexible, multi-directional mapping tool that achieves a high degree of contact with the tissue to maintain continuity of signal both when operating alone and when the Treatment Balloon is present. 
     Exemplary Embodiment(s) 
     The present embodiment is schematically shown in  FIGS. 18A-19B . The tethered Splines will:
         Maintain their relative positions when deployed independently; and   Maintain their relative positions when a treatment balloon is inserted and deployed in the center of the spherical space that they delineate.       

     A Mapping Device comprising Splines that are attached to one another by a system of Tethers, which hold them in their relative positions in a somewhat spherical configuration. 
     Key components include:
         Mapping Device   Splines   Tethers   Treatment Balloon       

     Tethers may be attached to Splines in a variety of ways, including but not limited to welding the Splines to a Ring or Filament and wrapping of the Filament around the Splines. 
     The need for the Tethers to hold the Splines is evident in the data from the procedures in which the devices are merged. When splines stay in place, the mapping is helpful to ablation. However, the image data from the mapping device show that the Splines can move out of place in which case, they are of minimal value during placement of the Treatment Device. 
     Preferably the Support Mesh retains its Splines in relative circumferentially spaced positions, evenly spaced in a spherical configuration that can guide the Treatment Balloon to a central location within it. This provides the surgeon with a flexible, multi-directional means of mapping tissue that can maintain continuity of signal both when operating alone and when the treatment balloon is present. The Splines are tethered in such a way that there remains an opening on the proximal end through which the Treatment Device can be threaded. Tethering the splines will maintain their relative positions when deployed independently; and maintain their relative positions when a treatment balloon is inserted and deployed in the center of the spherical space that they delineate. 
     A Mapping Device comprising Splines that are attached to one another by a Support Mesh, which holds them in their relative positions in a somewhat spherical configuration. 
     Key components include:
         Mapping Device   Splines   Support Mesh   Treatment Balloon       

     The Support Mesh may be designed so as to be occlusive or not. Open networks of filaments will keep the device non-occlusive, while wrapping it in a polymer film of fabric will make it more occlusive. 
     Although described above as being distinct from the treatment device  1602 , it will be understood that in some embodiments, the mapping overlay  1502  can be permanently affixed to or form part of the treatment device  1602 . For example, the mapping overlay  1502  can form part of an integrated treatment device, similar to integrated treatment devices  1102 ,  1202 ,  1302 , described in greater detail above. In such embodiments, the treatment device can include the treatment element  1604 , the mesh  1502  and/or the sensors  1504 . In addition, the mapping overlay can be used in any one or any combination of the routines  700 ,  800 , and/or  1400  described above. 
     Furthermore, it will be understood that the various embodiments described herein can be combined in any fashion. For example, a mapping overlay can be used in conjunction with any one or any combination of the treatment device embodiments. 
     Additional Embodiments 
     While the examples above have been described with respect to the treatment of atrial fibrillation, it will be understood that the devices, systems, and methods described herein can be used in a variety of applications where it is desirable to place two medical devices in the same location at different times and the location moves based on an anatomical cycle. For example, a first medical device can be placed at a particular location and its location can be determined with reference to a particular portion of an anatomical cycle, such as end exhalation. The first medical device can be removed and/or moved and a second medical device can be placed in approximately the same location as the first medical device. The location of the second medical device can be determined with respect to the same portion of the anatomical cycle. In this way, a provider can better determine whether the two medical devices are placed at the same location at different times. 
     Furthermore, reference is made throughout to various catheters that can be used to map and/or treat tissue. It will be understood that the catheters and sheaths described herein can be made of any one or a combination of polymers, including, but not limited to, silicone rubber, nitinol, nylon, polyurethane, polyethylene terephthalate (PET), latex, and thermoplastic elastomers as desired. In addition, the treatment elements and/or balloons described here can be made of polyurethane or other flexible and biocompatible material. 
     Any of the devices described above is preferably provided with an anti-thrombogenic feature. Thrombosis is a common concern in procedures involving endocardial devices. Two known approaches may significantly mitigate risk of thrombosis with the devices described in this disclosure: (1) coatings; and (2) side port irrigation. 
     Anti-thrombotic coatings may be applied to the filaments and splines of the mapping device. When applied, care must be taken to prevent interference with the integrated electrodes. This may be achieved by masking the electrodes during application of the coating or by applying the coating prior to ablative formation of the electrode zones on the wires. Coatings may include but are not limited to polymers with anti-thrombotic agents added, such as heparin or hirudin. An example of a suitable coating technology is HemoLAST anti-thrombogenic coating, available from AST Products, Inc., Billerica Mass. (https://www.astp.com/hemolast). 
     Side port irrigation can be arranged by integrating a fluid delivery channel into the device, which carries irrigation fluid from a proximal infusion port to at least one or a plurality of effluent irrigation ports in the vicinity of the mapping device. The channel may be a lumen within or a separate catheter alongside the mapping/treatment device. For example, the channel might be a lumen between the outside wall of the treatment balloon and the inside wall of the tubular mapping mesh. Controlled, periodic release of this fluid can prevent and disrupt aggregation of fibrin and formation of thromboses around the filaments and splines. Irrigation fluid may include but is not limited to heparinized saline or contrast medium.