Abstract:
An ablation system for treating atrial fibrillation in a patient comprises an inner shaft having proximal and distal ends as well as a lumen therebetween. A distal tip assembly is adjacent the inner shaft distal end, and the distal tip assembly comprises an energy source and a sensor. The energy source is adapted to deliver energy to a target tissue so as to create a zone of ablation in the target tissue. This blocks abnormal electrical activity and thus reduces or eliminates atrial fibrillation in the patient. The system also has an outer shaft with proximal and distal ends, and a lumen therebetween. The inner shaft is slidably disposed in the outer shaft lumen, and the inner shaft is rotatable, bendable and linearly slidable relative to the outer shaft. The outer shaft is rotatable, bendable and linearly slidable relative to the target tissue.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application is a non-provisional of and claims the benefit of priority of U.S. Provisional Patent Application No. 61/082,059 (Attorney Docket No. 027680-000600US) filed Jul. 18, 2008, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to medical devices, systems and methods, and more specifically to improved devices, systems and methods for creating an ablation zone in tissue. The device may be used to treat atrial fibrillation. 
         [0004]    The condition of atrial fibrillation (AF) is characterized by the abnormal (usually very rapid) beating of left atrium of the heart which is out of synch with the normal synchronous movement (“normal sinus rhythm”) of the heart muscle. In normal sinus rhythm, the electrical impulses originate in the sino-atrial node (“SA node”) which resides in the right atrium. The abnormal beating of the atrial heart muscle is known as fibrillation and is caused by electrical impulses originating instead in the pulmonary veins (“PV”) [Haissaguerre, M. et al., Spontaneous Initiation of Atrial Fibrillation by Ectopic Beats Originating in the Pulmonary Veins, New England J Med., Vol. 339:659-666]. 
         [0005]    There are pharmacological treatments for this condition with varying degrees of success. In addition, there are surgical interventions aimed at removing the aberrant electrical pathways from the PV to the left atrium (“LA”) such as the Cox-Maze III Procedure [J. L. Cox et al., The development of the Maze procedure for the treatment of atrial fibrillation, Seminars in Thoracic &amp; Cardiovascular Surgery, 2000; 12: 2-14; J. L. Cox et al., Electrophysiologic basis, surgical development, and clinical results of the maze procedure for atrial flutter and atrial fibrillation, Advances in Cardiac Surgery, 1995; 6: 1-67; and J. L. Cox et al., Modification of the maze procedure for atrial flutter and atrial fibrillation. II, Surgical technique of the maze III procedure, Journal of Thoracic &amp; Cardiovascular Surgery, 1995; 2110:485-95]. This procedure is shown to be 99% effective [J. L. Cox, N. Ad, T. Palazzo, et al. Current status of the Maze procedure for the treatment of atrial fibrillation, Seminars in Thoracic &amp; Cardiovascular Surgery, 2000; 12: 15-19] but requires special surgical skills and is time consuming. 
         [0006]    There has been considerable effort to copy the Cox-Maze procedure for a less invasive percutaneous catheter-based approach. Less invasive treatments have been developed which involve use of some form of energy to ablate (or kill) the tissue surrounding the aberrant focal point where the abnormal signals originate in the PV. The most common methodology is the use of radio-frequency (“RF”) electrical energy to heat the muscle tissue and thereby ablate it. The aberrant electrical impulses are then prevented from traveling from the PV to the atrium (achieving conduction block within the heart tissue) and thus avoiding the fibrillation of the atrial muscle. Other energy sources, such as microwave, laser, and ultrasound have been utilized to achieve the conduction block. In addition, techniques such as cryoablation, administration of ethanol, and the like have also been used. 
         [0007]    There has been considerable effort in developing catheter based systems for the treatment of AF using radiofrequency (RF) energy. One such method is described in U.S. Pat. No. 6,064,902 to Haissaguerre et al. In this approach, a catheter is made of distal and proximal electrodes at the tip. The catheter can be bent in a J shape and positioned inside a pulmonary vein. The tissue of the inner wall of the PV is ablated in an attempt to kill the source of the aberrant heart activity. Other RF based catheters are described in U.S. Pat. No. 6,814,733 to Schwartz et al., U.S. Pat. No. 6,996,908 to Maguire et al., U.S. Pat. No. 6,955,173 to Lesh, and U.S. Pat. No. 6,949,097 to Stewart et al. 
         [0008]    Another source used in ablation is microwave energy. One such device is described by Dr. Mark Levinson [(Endocardial Microwave Ablation: A New Surgical Approach for Atrial Fibrillation; The Heart Surgery Forum, 2006] and Maessen et al. [Beating heart surgical treatment of atrial fibrillation with microwave ablation. Ann Thorac Surg 74: 1160-8, 2002]. This intraoperative device consists of a probe with a malleable antenna which has the ability to ablate the atrial tissue. Other microwave based catheters are described in U.S. Pat. No. 4,641,649 to Walinsky; U.S. Pat. No. 5,246,438 to Langberg; U.S. Pat. No. 5,405,346 to Grundy et al.; and U.S. Pat. No. 5,314,466 to Stem et al. 
         [0009]    Another catheter based method utilizes the cryogenic technique where the tissue of the atrium is frozen below a temperature of −60 degrees C. This results in killing of the tissue in the vicinity of the PV thereby eliminating the pathway for the aberrant signals causing the AF [A. M. Gillinov, E. H. Blackstone and P. M. McCarthy, Atrial fibrillation: current surgical options and their assessment, Annals of Thoracic Surgery 2002; 74:2210-7]. Cryo-based techniques have been a part of the partial Maze procedures [Sueda T., Nagata H., Orihashi K. et al., Efficacy of a simple left atrial procedure for chronic atrial fibrillation in mitral valve operations, Ann Thorac Surg 1997; 63:1070-1075; and Sueda T., Nagata H., Shikata H. et al.; Simple left atrial procedure for chronic atrial fibrillation associated with mitral valve disease, Ann Thorac Surg 1996; 62: 1796-1800]. More recently, Dr. Cox and his group [Nathan H., Eliakim M., The junction between the left atrium and the pulmonary veins, An anatomic study of human hearts, Circulation 1966; 34:412-422, and Cox J. L., Schuessler R. B., Boineau J. P., The development of the Maze procedure for the treatment of atrial fibrillation, Semin Thorac Cardiovasc Surg 2000; 12:2-14] have used cryoprobes (cryo-Maze) to duplicate the essentials of the Cox-Maze III procedure. Other cryo-based devices are described in U.S. Pat. Nos. 6,929,639 and 6,666,858 to Lafintaine and U.S. Pat. No. 6,161,543 to Cox et al. 
         [0010]    More recent approaches for the AF treatment involve the use of ultrasound energy. The target tissue of the region surrounding the pulmonary vein is heated with ultrasound energy emitted by one or more ultrasound transducers. One such approach is described by Lesh et al. in U.S. Pat. No. 6,502,576. Here the catheter distal tip portion is equipped with a balloon which contains an ultrasound element. The balloon serves as an anchoring means to secure the tip of the catheter in the pulmonary vein. The balloon portion of the catheter is positioned in the selected pulmonary vein and the balloon is inflated with a fluid which is transparent to ultrasound energy. The transducer emits the ultrasound energy which travels to the target tissue in or near the pulmonary vein and ablates it. The intended therapy is to destroy the electrical conduction path around a pulmonary vein and thereby restore the normal sinus rhythm. The therapy involves the creation of a multiplicity of lesions around individual pulmonary veins as required. The inventors describe various configurations for the energy emitter and the anchoring mechanisms. 
         [0011]    Yet another catheter device using ultrasound energy is described by Gentry et al. [Integrated Catheter for 3-D Intracardiac Echocardiography and Ultrasound Ablation, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 51, No. 7, pp 799-807]. Here the catheter tip is made of an array of ultrasound elements in a grid pattern for the purpose of creating a three dimensional image of the target tissue. An ablating ultrasound transducer is provided which is in the shape of a ring which encircles the imaging grid. The ablating transducer emits a ring of ultrasound energy at 10 MHz frequency. In a separate publication [Medical Device Link, Medical Device and Diagnostic Industry, February 2006], in the description of the device, the authors assert that the pulmonary veins can be imaged. 
         [0012]    While these devices and methods are promising, improved devices and methods for creating a heated zone of tissue, such as an ablation zone are needed. Furthermore, it would also be desirable if such devices could create single or multiple ablation zones to block abnormal electrical activity in the heart in order to lessen or prevent atrial fibrillation. It would also be desirable if such devices could be used in the presence of blood or other body tissues without coagulating or clogging up the ultrasound transducer. Such devices and methods should be easy to use, minimally invasive, cost effective and simple to manufacture. 
         [0013]    2. Description of Background Art 
         [0014]    Other devices based on ultrasound energy to create circumferential lesions are described in U.S. Pat. Nos. 6,997,925; 6,966,908; 6,964,660; 6,954,977; 6,953,460; 6,652,515; 6,547,788; and 6,514,249 to Maguire et al.; U.S. Pat. Nos. 6,955,173; 6,052,576; 6,305,378; 6,164,283; and 6,012,457 to Lesh; U.S. Pat. Nos. 6,872,205; 6,416,511; 6,254,599; 6,245,064; and 6,024,740; to Lesh et al.; U.S. Pat. Nos. 6,383,151; 6,117,101; and WO 99/02096 to Diederich et al.; U.S. Pat. No. 6,635,054 to Fjield et al.; U.S. Pat. No. 6,780,183 to Jimenez et al.; U.S. Pat. No. 6,605,084 to Acker et al.; U.S. Pat. No. 5,295,484 to Marcus et al.; and WO 2005/117734 to Wong et al. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    The present invention relates generally to medical devices and methods, and more specifically to medical devices and methods used to deliver energy to tissue as a treatment for atrial fibrillation and other medical conditions. 
         [0016]    In a first aspect of the present invention an ablation system for treating atrial fibrillation in a patient comprises an elongate inner shaft having a proximal end, a distal end and lumens therebetween. The system also has a distal tip assembly adjacent the distal end of the inner shaft. The distal tip assembly comprises an energy source and a sensor. The energy source is adapted to deliver energy to a target tissue so as to create a zone of ablation in the target tissue that blocks abnormal electrical activity thereby reducing or eliminating the atrial fibrillation in the patient. The system also has an elongate outer shaft having a proximal end, a distal end and a lumen therebetween. The inner shaft is slidably disposed in the outer shaft lumen. The inner shaft is rotatable, bendable and linearly slidable relative to the outer shaft, and the outer shaft is rotatable, bendable and linearly slidable relative to the target tissue. 
         [0017]    The distal tip assembly may comprise an outer housing with the energy source and the sensor disposed therein. The outer housing may have an open end and may have a plurality of slots on one end forming a castellated region. 
         [0018]    The energy source may be recessed from a distal end of the housing such that the energy source does not contact the target tissue or surrounding fluids such as blood when the energy source delivers energy. The energy source may comprise an ultrasound transducer. The energy source may deliver one of radiofrequency energy, microwaves, photonic energy, thermal energy, and cryogenic energy. The energy source may deliver the energy in a beam that is 65 to 115 degrees relative to a surface of the target tissue. The zone of ablation may follow an arcuate or a linear path. 
         [0019]    The sensor may detect gap distance between a surface of the target tissue and the energy source. The sensor also may be able to detect an angle between the energy source and a surface of the target tissue. The sensor may be able to determine characteristics of the target tissue such as its thickness. In some embodiments, the sensor comprises an ultrasound transducer. The energy source may also be an ultrasound transducer, and in some embodiments the ultrasound transducer serves as both the energy source and the sensor. The sensor may also comprise an infrared sensor or a radiofrequency sensor. 
         [0020]    The sensor may comprise a positioning mechanism adjacent the distal end of the outer shaft. The positioning mechanism may be adapted to facilitate location of an anatomic structure and also adapted to anchor the ablation system to the anatomic structure. The positioning mechanism may also provide a visual, audible or tactile indication of ablation system position relative to the anatomic structure. The ablation system inner shaft may be rotatable around the positioning mechanism. 
         [0021]    The positioning mechanism may be positionable in the outer shaft lumen and may be in a substantially linear configuration while disposed therein. The positioning mechanism may comprise a coil or a plurality of wires that are biased to flare radially outward when unconstrained. The positioning mechanism may be adapted to exert an outward biasing force against the anatomic structure, thereby anchoring the ablation system thereto. The target tissue may comprise a pulmonary vein and the positioning mechanism may be adapted to indicate the angle of entry of the inner shaft into the pulmonary vein. 
         [0022]    The system may further comprise a guide catheter and the outer shaft may be slidably positioned therein. The target issue may comprise heart tissue, a pulmonary vein or tissue adjacent thereto. The inner or the outer shaft may comprise a braided portion or a spring coil. The system may also comprise an anchoring mechanism that is coupled with the ablation system and that is configured to stabilize the distal tip assembly. The anchoring mechanism may comprise an expandable member such as a balloon. The anchoring mechanism may also comprise a shapeable wire that may be coupled with the target tissue. The anchor may also have one or more tissue engaging barbs or hooks. 
         [0023]    The system may further comprise a bending mechanism that is operably coupled with the inner shaft. In some embodiments, the bending mechanism may comprise a pull wire operably coupled adjacent the distal end of the inner shaft and wherein a portion of the pull wire is disposed along an outer surface of the inner shaft such that when the pull wire is actuated, the inner shaft deflects radially inward or outward relative to the portion of the pull wire outside of the inner shaft, and wherein the portion of the pull wire remains in a substantially linear configuration. The bending mechanism may comprise a first and a second pull wire. The first pull wire may be coupled with a distal region of the inner shaft and the second pull wire may be coupled with a proximal region of the inner shaft. The pull wires may be adapted to bend the inner shaft in two locations, a first bend and a second bend. The system may include an actuator that is disposed near a proximal end of the inner shaft and that is adapted to actuate the pull wires thereby bending the inner shaft and forming the first bend and the second bend along the inner shaft. The first and second bends may be in different planes. 
         [0024]    The system may comprise a bending mechanism that is operably coupled with the outer shaft. The bending mechanism may comprise a first and a second pull wire. The first pull wire may be coupled with a distal region of the outer shaft and the second pull wire may be coupled with a proximal region of the outer shaft. The pull wires may be adapted to bend the outer shaft in two locations, a first bend and a second bend. The system may also have an actuator that may be disposed near a proximal end of the outer shaft and that may be adapted to actuate the pull wires thereby bending the inner shaft and forming the first bend and the second bend along the inner shaft. The first and the second bends may be in different planes. 
         [0025]    In a second aspect of the present invention, a method for treating atrial fibrillation in a patient by ablating tissue comprises providing an ablation system comprising an outer shaft and an inner shaft. The inner shaft has a distal tip assembly that comprises an energy source and a sensor. The outer shaft is slidably disposed over at least a portion of the inner shaft. The distal tip assembly is positioned adjacent the tissue and the inner shaft or the outer shaft is manipulated so as to place the energy source in a desired position relative to the tissue. Energy is delivered from the energy source to the tissue and a partial or complete zone of ablation is created in the tissue, thereby blocking abnormal electrical activity and reducing or eliminating the atrial fibrillation. 
         [0026]    The ablation system may further comprise a guide sheath and the method may include positioning a distal portion of the guide sheath across an atrial septum of the patient&#39;s heart. Positioning the system may comprise advancing the distal tip assembly intravascularly into the patient&#39;s heart. 
         [0027]    The step of manipulating may comprise slidably moving the inner shaft relative to the outer shaft. Manipulating may also include rotating the inner shaft relative to the outer shaft or bending the inner shaft. Bending may also comprise bending the inner shaft in two or more locations that may lie in the same plane or in different planes. Bending may be accomplished by actuating one or more pull wires coupled to the inner shaft. The step of manipulating may also include slidably moving, rotating or bending the outer shaft. The outer shaft may be bent in two or more locations. The two or more bends may lie in the same or different planes. Bending of the outer shaft may be accomplished by actuating one or more pull wires that are coupled to the outer shaft. The step of manipulating may comprise rotating either the inner or the outer shaft in a first direction and rotating the inner or the outer shaft in a second direction opposite the first direction so as to reduce binding or torque buildup in the inner or the outer shaft. The step of manipulating may comprise moving the energy source so as to direct the energy from the energy source to the tissue in a raster pattern. The manipulating step may comprise synchronizing movement of the energy source with the patient&#39;s heart rate. 
         [0028]    The energy source may comprise an ultrasound transducer and the step of delivering the energy may comprise delivering an ultrasound beam from the transducer to the tissue. The step of delivering the energy may comprise delivering one of radiofrequency energy, microwave energy, photonic energy, thermal energy, and cryogenic energy. 
         [0029]    Creating the zone of ablation may comprise forming a linear ablation path or a circular ablation path which may encircle at least one pulmonary vein. The ablation system may further comprise a sensor and the method may comprise sensing characteristics of the tissue with the sensor. The sensor may comprise an ultrasound transducer and in some embodiments the energy source may comprise the same ultrasound transducer as the sensor. The method may further comprise switching modes between delivering energy from the ultrasound transducer and sensing with the ultrasound transducer. The sensed tissue characteristics may comprise position of the tissue relative to the energy source, such as gap distance between the tissue and a surface of the energy source. The position may comprise a relative angle between the energy source and the tissue. The tissue characteristics may comprise the tissue thickness and/or the depth of the ablated region. 
         [0030]    The sensor may comprise a positioning mechanism and the method may include advancing the positioning mechanism from either the inner or the outer shaft into the tissue or tissue adjacent thereto. The positioning mechanism may facilitate locating the anatomical structure. The positioning mechanism may comprise a plurality of wires and the method may further comprise positioning the wires into a pulmonary vein while observing the shape and orientation of the wires. 
         [0031]    The method may further comprise guiding the energy based on the tissue characteristics that are sensed. The method may also include maintaining the gap between the energy source and the tissue surface at a desired value. The tissue may comprise left atrial tissue, a pulmonary vein or tissue adjacent thereto. In some embodiments the method further comprises cooling the energy source or anchoring the distal tip assembly relative to the tissue. Anchoring may comprise coupling a wire with the tissue or expanding an expandable member coupled with the outer shaft, such as a balloon. 
         [0032]    These and other embodiments are described in further detail in the following description related to the appended drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0033]      FIG. 1  is a drawing of bending movement, rotating movement, and linear movement of the system of the preferred embodiments of the invention; 
           [0034]      FIG. 2  is a drawing of the distal tip assembly of the system of the preferred embodiments of the invention; 
           [0035]      FIG. 3  is a drawing of the first variation of the anchoring mechanism of the system of the preferred embodiments of the invention; 
           [0036]      FIGS. 4A-4C  are drawings of bending movement of the system of the preferred embodiments of the invention; 
           [0037]      FIG. 5  is a drawing of a “Sheppard&#39;s hook” bending movement of the system of the preferred embodiments of the invention; 
           [0038]      FIGS. 6A and 6B  are drawings of a second variation of bending movement of the system of the preferred embodiments of the invention; 
           [0039]      FIG. 7  is a drawing of a movement pattern; 
           [0040]      FIG. 8  is a drawing of a Electrocardiogram (ECG) tracing of a cardiac cycle; 
           [0041]      FIG. 9  is a drawing of the connector console of the preferred embodiments; and 
           [0042]      FIGS. 10A-13  are drawings of a positioning mechanism of the system of the preferred embodiments of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0043]    The following description of the preferred embodiments of the invention is not intended to limit the invention to these embodiments, but rather to enable any person skilled in the art to make and use this invention. 
         [0044]    As shown in  FIG. 1 , the system  10  of the preferred embodiments includes an elongate member  18  and a distal tip assembly  48 , which is coupled to the distal portion of the elongate member  18  and includes at least one of an energy source  12  and a sensor. The elongate member  18  functions to move and position the distal tip assembly  48 , along with the energy source  12  and/or sensor. The elongate member  18  and the distal tip assembly  48  cooperatively function to direct the energy source  12  and/or the sensor towards a target tissue. The system  10  is preferably designed for positioning an energy source within a patient and delivering energy to tissue, more specifically, for delivering ablation energy to tissue, such as heart tissue, to create a conduction block—isolation and/or block of conduction pathways of abnormal electrical activity, which typically originate from the pulmonary veins in the left atrium for treatment of atrial fibrillation in a patient. The system  10 , however, may be alternatively used with any suitable tissue in any suitable environment and for any suitable reason. 
         [0045]    The Elongate Member. As shown in  FIG. 1 , the elongate member  18  of the preferred embodiments functions to move and position the distal tip assembly  48 , and the energy source  12  and/or sensor within it. The elongate member  18  is preferably a catheter made of a flexible multi-lumen tube, but may alternatively be a cannula, tube or any other suitable elongate structure having one or more lumens. The elongate member  18  may also function to accommodate pull wires, fluids, gases, energy sources, electrical connections, therapy catheters, navigation catheters, pacing catheters, and/or any other suitable device or element. 
         [0046]    The elongate member is preferably one of several variations. In a first variation, as shown in  FIG. 1 , the elongate member  18  preferably includes a therapy catheter  2110 , an outer catheter  2112 , and a guide sheath  2118 . The elongate member  18  may alternatively include a single catheter or any other suitable number of catheters and/or sheaths. The catheters are preferably arranged concentrically to one another, but may alternatively be arranged in any other suitable fashion. The therapy catheter  2110  is preferably slideably contained in the outer catheter  2112 , and the therapy catheter  2110  and the outer catheter  2112  preferably form a conjoined set that can be freely moved axially in the guide sheath  2118 . The outer catheter  2112  is preferably provided with at least three independent movements: axial movement  2120 , rotational movement  2124 , and bending movement  2122 . The end portion  186  of the guide sheath  2118  preferably has a snug fit over the outer catheter  2112  so as to provide a grip on the outer catheter  2112  while it is performing rotation  2124 . The anchoring mechanism, as shown in  FIG. 3  and described below, is preferably used to fix the outer catheter  2112  with respect to the guide sheath  2118  while it rotates, bends, moves axially, or moves in any other suitable fashion. The outer catheter  2112  may be moved axially inside the guide sheath  2118  in a manner  2120 . In addition, a portion of the outer catheter  2112  may be bent about a pivot point  182  in a manner  2122 . Additionally, the outer catheter  2112  may bend in any suitable number of locations in addition to point  182 . 
         [0047]    Similarly to the outer catheter  2112 , as shown in  FIG. 1 , the therapy catheter  2110  also is provided with at least three independent movements: axial movement  2152 , rotational movement  2156 , and bending movement  2154 . The end portion  188  of the outer catheter  2112  preferably has a snug fit over the therapy catheter  2110  so as to provide a grip on the therapy catheter  2110  while it is performing rotation  2156 . The therapy catheter  2110  may also be moved axially inside the outer catheter  2112  in a manner  2152 . In addition, a portion of the therapy catheter  2110  may be bent about a pivot point  184  in a manner  2154 . The therapy catheter  2110  may bend in any suitable number of locations in addition to point  184 . 
         [0048]    The Distal Tip Assembly. As shown in  FIGS. 1 and 2 , the distal tip assembly  48  of the preferred embodiments is coupled to the distal portion of the elongate member  18  and includes at least one of an energy source  12  and a sensor. As shown in  FIG. 1 , the distal tip assembly  48  preferably includes a housing  16  coupled to the energy source  12 . The housing  16  preferably has an open, tubular shape, but may alternatively be a closed end housing that encloses the energy source  12 . At least a portion of the closed end housing is preferably made of a material that is transparent to the energy beam  20 , such as a material transparent to ultrasound energy, such as a poly 4-methyl, 1-pentene (PMP) material or any other suitable material. As shown in  FIG. 2 , the open tubular housing preferably has a “castle head” configuration such that the housing defines a plurality of slots  52 . The slots  52  function to provide exit ports for the flowing fluid  28 . When the front tip of the distal tip assembly  48  is in contact with or adjacent to the tissue or other structures during the use of the system  10 , the slots  52  function to maintain the flow of the cooling fluid  28  past the energy source  12  and along the surface of the tissue. The fluid flow lines  30  flow along the grooves in the backing  22 , bathe the energy source  12 , form a fluid column and exit through the slots  52  at the castle head housing  16 . In the closed end housing, the housing preferably defines apertures such as small holes towards the distal end of the housing  16 . These holes provide for the exit path for the flowing fluid. The apertures may be a grating, screen, holes, drip holes, weeping structure or any of a number of suitable apertures. Alternatively, the closed end housing may not define apertures to allow the exit of the fluid but rather, the housing contains the fluid within the housing and recycles the fluid past the energy source  12 . 
         [0049]    The housing  16  of the distal tip assembly  48 , further functions to provide a barrier between the face of the energy source  12  and the blood residing in the patient, such as in the atrium of the heart. If fluid flow is not incorporated, and the transducer face is directly in contact with blood, the blood will coagulate on the surface of the energy source  12 . Additionally, there is a possibility of forming a blood clot at the interface of the energy source  12  and the surrounding blood. Because the energy source is recessed from the distal end of the housing and because the flow of the cooling fluid  28  keeps the blood from contacting the energy source  12 , blood clot formation on the energy source is avoided. The fluid flow rate is preferably 1 ml per minute or higher (e.g. 10 ml per minute), but may alternatively be any other suitable flow rate to maintain the fluid column, keep the separation between the blood and the face of the energy source  12 , cool the energy source  12 , and/or cool the tissue  276 . Additional details about housing  16  and the components therein are disclosed in greater detail in U.S. patent application Ser. No. 12/480,256 (Attorney Docket No. 027680-000310US), Ser. No. 12/483,174 (Attorney Docket No. 027680-000410US), and Ser. No. 12/482,640 (Attorney Docket No.027680-000510US), the entire contents of each incorporated herein by reference. 
         [0050]    The Energy Source. As shown in  FIG. 2 , the energy source  12  of the preferred embodiments functions to provide a source of ablation energy and emits an energy beam  20 . The energy source  12  is preferably an ultrasound transducer that emits an ultrasound beam, but may alternatively be any suitable energy source that functions to provide any suitable source of ablation energy. Some examples of suitable sources of ablation energy include radio frequency (RF) energy, microwaves, photonic energy, and thermal energy. The therapy could alternatively be achieved using cooled fluids (e.g., cryogenic fluid). The distal tip assembly  48  preferably includes a single energy source  12 , but may alternatively include any suitable number of energy sources  12 . The ultrasound transducer is preferably made of a piezoelectric material such as PZT (lead zirconate titanate) or PVDF (polyvinylidine difluoride), or any other suitable ultrasound beam emitting material. The transducer may further include coating layers such as a thin layer of a metal. Some suitable transducer coating metals may include gold, stainless steel, nickel-cadmium, silver, and a metal alloy. 
         [0051]    The Sensor. The distal tip assembly  48  of the preferred embodiments also includes a sensor that functions to detect the gap (namely, the distance of the tissue surface from the energy source  12 ); the angle of the distal tip assembly  48 , energy source  12 , and/or sensor itself with respect to the tissue; the thickness of the tissue targeted for ablation; the characteristics of the ablated tissue; and any other suitable parameter or characteristic. By detecting this information, the information from the sensor preferably guides the therapy provided by the ablation of the tissue and provides information as to where to position the system, at what position to have the energy source with respect to the distal tip assembly in order to maintain a proper gap distance, and at what settings at which to use the energy source  12  and any other suitable elements. In response to the information detected by the sensor, the elongate member  18  and any suitable combination of outer catheters  2112  and therapy catheters  2110  can be moved axially, rotationally, in a bending movement, or in any suitable combination of movements thereof in order to move and position the distal tip assembly  48 , the energy source  12 , and/or the sensor within the patient, to maintain a sufficient gap distance and provide the proper characteristics and qualities desired of the ablated tissue. The sensor may be operated to detect the qualities of the targeted tissue, the gap distance, etc. before therapy, throughout therapy (simultaneously or alternating with therapy), after therapy, and/or any combination thereof. 
         [0052]    The sensor is preferably one of several variations. In a first variation, the sensor is an ultrasound transducer, but may alternatively be any suitable sensor, such as an IR sensor or RF sensor, to detect the gap, the angle of the distal tip assembly  48 , energy source  12 , and/or sensor itself with respect to the tissue, the thickness of the tissue targeted for ablation, the characteristics of the ablated tissue, and any other suitable parameter or characteristic. The ultrasound transducer preferably utilizes a pulse of ultrasound of short duration, which is generally not sufficient for heating of the tissue. This is an ultrasound imaging technique, referred to in the art as A-Mode, or Amplitude Mode imaging. The sensor is preferably the same transducer as the transducer of the energy source, operating in a different mode (such as A-mode, described above), or may alternatively be a separate ultrasound transducer. The separate ultrasound transducer may be coupled to the transducer of the energy source  12  or may be in a separate location. 
         [0053]    In a second variation, as shown in  FIGS. 10A and 10B , the sensor is a positioning mechanism  54 . The positioning mechanism is preferably coupled to a distal portion of the elongate member  18 . In some variations, the positioning mechanism  54  is retractable into the elongate member  18 . The positioning mechanism  54  functions to facilitate locating an anatomical structure by providing an indication of where the positioning mechanism  54  is with respect to the anatomical structure. The indication is preferably a visual indication (via a medical imaging system such as a fluoroscope), but is alternatively or additionally a tactile or audible indication. Additionally, the elongate member  18  and or the positioning mechanism  54  may include indicia, such as markings indicating distance, that indicate the location of the anatomical structure and/or to indicate the depth of insertion of the system  10  where the anatomical structure was located. 
         [0054]    As shown in  FIGS. 11 ,  12 A, and  12 B, a first version of the positioning mechanism  54 ′ includes a plurality of wires each having a first end  24  and a second end  26 . The first end  24  is preferably coupled to the distal tip of the elongate member  18 , but may alternatively be attached in any other suitable location. The second end  26  preferably extends from the distal tip of the elongate member and is positioned in a fully extended position, as shown in  FIG. 11 . The second end  26  preferably deflects due to contact with a surface, as shown in  FIGS. 12A and 12B . The second end  26  is preferably biased towards the fully extended position, but may alternatively be biased towards any other suitable position. 
         [0055]    As shown in  FIGS. 12A and 12B , the plurality of wires function to facilitate locating an anatomical structure by flexing as they come in contact with the anatomical structure. For example, the wires will remain fully extended from the elongate member  18  when they are unobstructed in the left atrium of the heart  3002 . As the system  10  is moved within the left atrium of the heart  3002  and begins to contact the ostium (opening) of a pulmonary vein  3000 , the plurality of wires will begin to deflect partially, as shown in  FIG. 12A . As the system  10  is moved into the pulmonary vein  3000 , the wires will deflect more dramatically as shown in  FIG. 12B . As the system is moved deeper into the pulmonary vein, the wires will not deflect as much, if at all, and the sensor and/or an operator of the system  10  will be able to determine when the positioning mechanism  54  of the system  10  is correctly located within the pulmonary vein. Furthermore, as shown in  FIG. 13 , the angle  3004  at which the system  10  enters the pulmonary vein  3000  with respect to the longitudinal axis of the pulmonary vein  3000  can be determined. Upon the detection of the angle  3004 , the distal tip assembly  48  is preferably moved such that the angle between the energy source  12  and the tissue is an appropriate angle. The emitted energy beam  20  preferably contacts the target tissue at an angle between 20 and 160 degrees to the tissue, more preferably contacts the target tissue at an angle between 45 and 135 degrees to the tissue, and most preferably contacts the target tissue at an angle of 65 and 115 degrees to the tissue. 
         [0056]    Positioning the System.  FIGS. 10A-10B ,  11 ,  12 A- 12 B and  13  illustrate several embodiments of a positioning mechanism. The elongate member  18  and the distal tip assembly  48  cooperatively function to direct the energy source  12  and/or the sensor towards a target tissue. The elongate member  18  preferably moves and positions the distal tip assembly  48 , and the energy source  12  and/or sensor within it. The distal tip assembly is preferably moved and positioned within a patient, preferably moved to within the left atrium of the heart (or into any other suitable location) and, once positioned there, is preferably moved to direct the sensor and/or the energy source  12  and the emitted energy beam  20  towards the target tissue at an appropriate angle. The emitted energy beam  20  preferably contacts the target tissue at an angle between 20 and 160 degrees to the tissue, more preferably contacts the target tissue at an angle between 45 and 135 degrees to the tissue, and most preferably contacts the target tissue at an angle of 65 and 115 degrees to the tissue. 
         [0057]    The distal tip assembly  48 , and the energy source  12  (and/or sensor) within it, are preferably moved along an ablation path (and/or imaging path) such that the energy source  12  provides a partial or complete zone of ablation along the ablation path (and/or diagnosis of the tissue along the path). For example, as shown in  FIG. 5 , ablation path  308  encircles two pulmonary veins PV. The ablation path may alternatively have any suitable geometry and be positioned in any suitable location. The zone of ablation along the ablation path preferably has any suitable geometry to provide therapy, such as providing a conduction block for treatment of atrial fibrillation in a patient. The zone of ablation along the ablation path may alternatively provide any other suitable therapy for a patient. The imaging path preferably has any suitable geometry to assess the characteristics of the target tissue such as the gap (namely, the distance of the tissue surface from the energy source  12 ), the angle of the distal tip assembly  48 , energy source  12 , and/or sensor itself with respect to the tissue, the thickness of the tissue targeted for ablation, the characteristics of the ablated tissue, and any other suitable parameter or characteristic. 
         [0058]    The elongate member  18  preferably moves and positions the distal tip assembly  48 , and the energy source  12  and/or sensor within it, by moving in several variations of movements such as axial (forwards and backwards along the axis of the elongate member), rotational, and bending movements with several variations of mechanisms such as a bending mechanism and an anchoring mechanism in order to obtain the desired ablation and/or imaging paths. For example, a linear ablation path is preferably created by moving the distal tip assembly, and the energy source  12  within it, in bending movements. Additionally, a generally circular ablation path is preferably created by rotating the distal tip assembly, and the energy source  12  within it, about an axis and an elliptical path is created by a combination of bending and rotation movements. 
         [0059]    Rotational Movement. As described above, and as shown in  FIG. 1 , the elongate member  18  and any of the catheters of the elongate member  18  are preferably rotated about the central axis of the elongate member as shown by arrows  2124  and  2156 . Conventionally, as a catheter is rotated within a second catheter, the two catheters may bind and stick with one another, generally due to static friction, preventing a smooth rotational movement. To prevent and/or release this binding and/or torque buildup, the tubing of the catheters are preferably encased in a braid that is covered in a jacket of low friction material. The catheters may alternatively be encased in a spring, spring wrapping, or wrapping of foil. The material of the braid is preferably round or flat metal wires, plastic filaments, or Kevlar. 
         [0060]    Alternatively to or in addition to the braid, the rotational movement of system  10  preferably includes a local oscillation movement (a second rotational movement in the opposite direction from the first rotational movement that is smaller than the first rotational movement). The local oscillation movement functions to prevent and/or release this binding and/or torque buildup. For example, as shown in  FIG. 1 , if rotational movement  2156  of the therapy catheter  2110  is clockwise a few degrees (or any other suitable distance), then the local oscillation movement (not shown) of the therapy catheter  2110  will be fewer degrees in the counter-clockwise direction. By taking a smaller rotational movement backward for every rotational movement forward, the binding and torque build up are minimized (and/or prevented), and the rotational movement of the catheter will preferably be substantially uniform and free of skipping and jumping. 
         [0061]    The energy source  12  of the system  10  is uniquely suited for this local oscillation movement. For example, as the energy source  12  is energized and delivering the energy beam  20  (preferably ultrasound energy beam) to the target tissue and is rotated along an ablation path, the local oscillation movement (the back and forth movement) will bring the energy source  12  and the energy beam  20  over certain portions of the ablation path more than once. Due to the characteristics of the ultrasound energy beam and the lesion formation characteristics, the tissue will not be damaged or otherwise negatively affected by being contacted by the energy beam  20  more than once. This was verified in animal experiments. 
         [0062]    The Bending Mechanism and Bending Movement. As shown in  FIGS. 4A-4C , the system  10  of the preferred embodiments further includes a bending mechanism that functions to bend a distal portion of the elongate member  18  in at least one of several locations. The bending mechanism preferably includes lengths of wires, ribbons, cables, lines, fibers, filament or any other tensional member. The bending mechanism is preferably one of several variations. In a first variation, as shown in  FIGS. 4A-4C  the bending mechanism preferably includes one or more pull wires, for example, a distal pull wire and a proximal pull wire that induce bending at a distal position and a proximal position. The distal pull wire and the proximal pull wire are preferably attached to the elongate member  18  with an adhesive band. Alternatively, the pull wires may be coupled to the elongate member  18  using any suitable attachment mechanism such as adhesive, welding, pins and/or screws. The pull wires are preferably disposed within one or separate lumens of the elongate member  18 , but may alternatively be held in any suitable location. The pull wires preferably each terminate at a slider in a proximal housing that preferably includes various actuating mechanisms to affect various features of the bending mechanism  18 . As shown in  FIGS. 4A-4C , the distal pull wire  116  is secured at a distal portion of the elongate member  18  by means of the distal adhesive band  118 . In use, as the distal pull wire  116  is pulled by moving a first slider (not shown), and the elongate member is bent at location  126  in the direction  172 , thereby moving from position X to position Y, as shown in  FIG. 4B . A proximal pull wire  128 , which is secured in an elongate member lumen at a position by proximal adhesive band  130 , is pulled by moving a second slider (not shown) and the elongate member bends at location  136  and moves in the direction  174  to position Z, away from the longitudinal axis of the catheter, as shown  FIG. 4C . Alternatively, both pull wires may be pulled by a single slider mechanism and the shape illustrated in  FIG. 4C  can be achieved in this manner. 
         [0063]    The pull wire attachment points, and correspondingly the bend locations in the device are preferably configurable, in any of a number of ways. For example, a single pull wire or other bend inducing mechanism may be used. Alternatively, the use of three or more such mechanisms may be used. With respect to attachment points for bend inducing mechanisms, any suitable location along the distal tip assembly as well as the catheter distal portion are suitable optional attachment points. With respect to the number and location of bend locations in the device, a spectrum of suitable bend locations may be provided. For example, while one and two bends are illustrated herein, three or more bends can be used to achieve a desired catheter configuration and/or application of energy using the device. The bending mechanism preferably includes any suitable number of bending locations (pivot points) such that elongate member is bendable into several variations of shapes and configurations. While the two bends of the bending mechanism may be in the same plane, as exemplified in  FIG. 4A-4C , the bending mechanism preferably bends in any suitable plane and the two bends may occur in two different planes. The several variations of shapes and configurations preferably include shapes that allow the elongate member to position the distal tip assembly throughout an area of a patient (preferably throughout the left atrial chamber of the heart of a patient) and access target tissue within any section or portion of the chamber. For example, if the guide sheath were to enter through the septal wall of the left atrium, adjacent to (or close to) the ceiling wall of the left atrium, it would be beneficial to bend the elongate member down, away from the atrial ceiling and then back up towards the pulmonary veins. In a further example, in order to access the right pulmonary veins, which are typically closer to the entry point in the septal wall, a “shepherd&#39;s hook” configuration of the elongate member is beneficial wherein the elongate member enters the atrial chamber and then bends back towards the right pulmonary veins. As shown in  FIG. 5 , the outer catheter  412  has a preset shape of a “shepherd&#39;s hook” so as to point towards the right pulmonary veins when placed in the atrial chamber. 
         [0064]    In a second variation, as shown in  FIGS. 6A and 6B , the bending mechanism preferably includes at least one pull wire  56  that preferably induces “worm-like” bending in the elongate member. The pull wire is preferably attached to the elongate member  18  with an adhesive band  58 . Alternatively, the pull wire may be coupled to the elongate member  18  using any suitable attachment mechanism such as adhesive, welding, pins and/or screws. The pull wire is preferably disposed within a lumen of the elongate member  18  and exits through notches  60  and  62 , but may alternatively be held in any suitable location. The pull wire preferably terminates at a slider in a proximal housing (not shown) that preferably includes various actuating mechanisms to affect various features of the bending mechanism  18 . In use, as the pull wire  56  is pulled by moving the first slider (not shown), and the elongate member is bent at location  64  while the distal tip portion  66  and the proximal portion of the elongate member remain unbent such that the center portion buckles and bends out about point  64 , thereby moving the energy source  12  such that it moves away from the distal tip portion  66  (distance H) and to an angle A from the central axis of the elongate member  18 . As the elongate member  18  is bent at point  64 , the generally straight distal tip portion  66  and the proximal portion move to a distance L from one another. As shown in  FIG. 6B , when the first slider (not shown) is moved further, the elongate member  18  will further buckle at location  64 , thereby moving the energy source  12  such that it moves further away from the distal tip (distance H′, wherein distance H′ is greater than distance H) and to an angle A′ from the central axis of the elongate member. As the elongate member  18  is bent further at point  64 , the generally straight distal tip portion  66  and the proximal portion move to a distance L′ from one another. Distance L′ is preferably shorter than distance L. 
         [0065]    The bending mechanism functions to bend a distal portion of the elongate member  18  in at least one of several locations. Referring now to  FIG. 7 , the bending mechanism further functions to move the elongate member  18  through a series of bending movements such that the distal tip assembly  48 , and the energy source and/or sensor, moves over a pattern  68  (such as an ablation path or a imaging path). The pattern is preferably one of several variations. In a first variation, as shown in  FIG. 7 , the pattern  68  is a raster pattern. The lines of  FIG. 7  represent the path that the distal tip assembly, and the energy source and/or sensor within it, pass over as they are moved through the pattern  68  by the elongate member  18 . The raster pattern is preferably formed by combining a series of left and right bends with a series of up and/or down bends. For example, as shown in  FIG. 7 , if the distal tip assembly  48  were to begin oriented towards the upper left hand corner of the pattern  68 , the elongate member would first bend such that the distal tip assembly  48  moves towards the right, in a manner  71 , and creates the first leg  70  of the pattern  68 . The elongate member would then bend, preferably in the same location as before, such that the distal tip assembly moves down to begin the second leg  72  of the pattern  68  and from there the elongate member will bend such that the distal tip assembly  48  moves back towards the left, in a manner  73 , and creates the second leg  72  of the pattern  68 , and so on. The elongate member  18  can bend in any suitable location(s) and the distal tip assembly  48  can move in any suitable directions to move the energy source and/or the sensor back and forth such that it sweeps across the majority of an area, such as a wall or portion of a chamber of a heart. 
         [0066]    The bending mechanism may further function to move the elongate member  18  through a series of bending movements such that the bending movements are synchronized to a movement of the patient, such as breathing, heart rate, or any other suitable movement. In this variation, the bending mechanism is preferably coupled to a heart rate monitor such as an electrocardiograph, which records the electrical activity of the heart over time. The electrical waves of the heart cause the heart muscle to pump, and therefore move in a generally predictable manner over time. By coupling the bending mechanism to the electrocardiograph, the bending mechanism can bend in such a way to accommodate for the movement of the heart, or the data received from the sensor during the movements through the pattern  68  can be altered to account for the movement of the heart. Furthermore, the data collected by the sensor during the movements through the pattern  68  can be gathered and/or displayed with respect to an Electrocardiogram (ECG or EKG)—a graphic that displays the overall rhythm of the heart produced by an electrocardiograph, as shown in  FIG. 8 . An ECG displays a series of tracings of the heartbeat (or cardiac cycle). Generally a single tracing, as shown in  FIG. 8 , will include a P wave, a QRS complex and a T wave. In a first version, the data collected by the sensor is preferably collected continuously and displayed with respect to an ECG. For example, the portion of the data displayed is preferably the portion of the data that was taken at the same point of each of the ECG tracings of the heartbeat (or the cardiac cycle). In a second version, the data collected by the sensor is preferably only collected once per cardiac cycle and preferably collected at the same point along the cardiac cycle. Although the sensor data is preferably collected and displayed in one of these two versions, the data may alternatively be collected and displayed in any other suitable fashion. 
         [0067]    The Anchoring Mechanism. As shown in  FIG. 3 , the system  10  of the preferred embodiments further includes an anchoring mechanism that functions to hold the distal portion of the elongate member  18  in a relatively predictable position relative to a tissue, for example, inside a chamber such as the left atrium of the heart. The anchoring mechanism functions to provide a firm contact and/or stabilization between the anchor mechanism and the tissue, and provides an axis around which all or a portion of the catheter shaft can be rotated. 
         [0068]    The anchoring mechanism is preferably one of several variations. As shown in  FIG. 3 , the anchor mechanism  570  of the ablation device includes a double wall tubing  580  having an annulus  582  between an inner wall  584  and an outer wall  586 . Anchor mechanism  570  is an elongate structure spanning from a distal portion of the therapy catheter  510  to substantially the proximal portion of the device (not shown). The distal portion of the anchor mechanism  570  includes an expandable member  588 , for example, an inflatable balloon, which can communicate with a connector, for example, a luer fitting (not shown) at the proximal end of the anchor mechanism  570 . Although a balloon is described as an exemplary expandable member, it is envisioned that other expandable members such as a cage or stent may be used. The inner lumen  590  of the anchor mechanism  570  provides a passageway for the therapy catheter  510  such that the catheter is free to move axially  554  and rotationally  552  within. As shown in  FIG. 3 , during use, the anchor mechanism  570  can be positioned inside the guide sheath  522  and advanced distally until a distal portion of the anchor mechanism  570  extends beyond the guide sheath  522  while the expandable member  588  remains inside the guide sheath  522  substantially proximal to the guide sheath  522  end. In another implementation at least a part of the expandable member of the anchor mechanism remains inside the guide catheter, while another part of the expandable member extends distally beyond the guide catheter end (not shown). In yet another implementation the distal portion of the anchor mechanism remains substantially proximal to the distal end of the guide catheter (not shown). 
         [0069]    To effect anchoring, the balloon can be inflated with a suitable fluid (e.g., saline or CO 2 ) sufficiently such that a distal portion of the anchor mechanism is held firmly in the guide catheter. The therapy catheter  510  can then be advanced distally (as shown by arrow  554  in  FIG. 3 ) through the inner lumen  590  of the anchor  570 . As shown in  FIG. 3 , when the expandable member  588  is inflated, the distal portion of the catheter  510  exiting from the anchor mechanism  570  is free to rotate in a manner  552  about a longitudinal axis, yet is held firmly in the guide sheath  522 . As required, the catheter distal portion can be shaped by bending as described above to a desired position (as shown in  FIGS. 4A-4C ). When anchored at the end of the guide sheath  522 , the distal portion of the therapy catheter  510  can be caused to follow a fixed rotational path without being susceptible to wavering or wandering as the catheter is rotated or otherwise guided in the heart chamber to create a zone of ablation. 
         [0070]    In a second variation, the anchor mechanism includes a pre-shaped wire loop. The wire loop is preferably made of a shapeable wire, for example, made from a shape-memory material such as Nitinol (nickel-titanium alloy) and although a loop is described, it is envisioned that any of a number of shapes, curved and/or angular, two-dimensional and/or three-dimensional can provide the anchoring required. The anchor can reside in a lumen (not shown) of the elongate member  18 , and can exit from the elongate member  18  through a notch near the distal end of the elongate member to couple with a tissue such that it anchors the system  10  with respect to the tissue. In a third variation, the expandable member is an inflatable balloon. The anchoring member may be in the shape of a disc that is inflatable, for example, an inflatable balloon. In a fourth variation, the distal portion of the anchor mechanism includes one or more barb members or similar tissue engaging hooks. 
         [0071]    The Connector Console. As shown in  FIG. 9 , the system  10  of the preferred embodiments further includes a connector console  2132  that functions to move the elongate member  18  (guide sheath, outer catheter, therapy catheter, etc.) in any suitable combination of movements and to drive the various mechanisms of the system  10  (anchoring, bending, etc.). All of the movements described below may alternatively be achieved by hand or by using any other suitable motors, linkages, and actuators in the console  2132  or in a separate or additional driving device, and/or any combination thereof. As shown in  FIG. 9 , at the proximal end of the guide sheath  2118 , the various catheter elements are connected to a variety of controls in a connector console  2132 . After placement of the distal tip assembly  48  within the patient (in one example, preferably through the septum of the heart into the left atrium), the guide sheath  2118  is preferably locked in position by means of a lever  2134 . As shown in  FIG. 1  in conjunction with  FIG. 9 , the outer catheter  2112  is preferably provided with at least three independent movements: axial movement  2120 , rotational movement  2124 , and bending movement  2122 . The axial movement  2120  of the outer catheter  2112  within the guide sheath  2118  is preferably achieved by moving slider  2140  that preferably moves linearly in slot  2142 , but may alternatively be achieved in any other suitable fashion. Once the desired position of the catheter  2112  is achieved, the slider  2140  is preferably locked in position. The rotational movement  2124  of the outer catheter  2112  is preferably achieved by the gear mechanism  2144  and  2146 , but may alternatively be achieved in any other suitable fashion. Gear  2144  is preferably attached to the proximal end of the outer catheter  2112 . Gear  2144  is driven by the pinion  2146 ; which is attached to a motor (not shown). The bending movement  2122  around a pivot point  182  of the distal tip of the catheter  2112  is preferably achieved by means of the pull wire  2148 , which terminates in a slider mechanism  2150 , but may alternatively be achieved in any other suitable fashion. The slider  2150  is preferably lockable once the desired position of the bending of the catheter  2112  is achieved. Additionally, the outer catheter  2112  may bend in any suitable number of locations in addition to point  182 . 
         [0072]    Similarly to the outer catheter  2112 , the therapy catheter  2110  also is provided with at least three independent movements: axial movement  2152 , rotational movement  2156 , and bending movement  2154 . The catheter  2110  can be moved axially in the catheter  2112  as shown by movement  2152 . This movement  2152  is preferably controlled at the proximal end by means of slider  2158 , but may alternatively be achieved in any other suitable fashion. The slider  2158  is preferably lockable once the desired position of the therapy catheter  2110  is achieved in the outer catheter  2112 . The distal portion of the catheter  2110  can be bent in the manner  2154  around a pivot point  184  preferably by a pull wire (not shown) connected to the slider mechanism  2160  at the proximal end console  2132 , but may alternatively achieve the bending movement in any other suitable fashion. Again, the slider  2160  is preferably lockable in position once the desired position of the bend of the tip of the catheter  2110  is achieved. Additionally, the therapy catheter  2110  may bend in any suitable number of locations in addition to point  184 . The catheter  2110  can be rotated in the outer catheter  2112  in a manner shown as  2156 . The end portion  188  of the outer catheter  2112  preferably grips the catheter  2110  to provide support during the rotation  2156  of the catheter  2110  and the catheter  2110  is preferably freely movable inside the outer catheter  2112  in a manner  2152 . This motion is preferably affected by the gear mechanism  2162  and  2164  in the console  2132 , but may alternatively be effected by any other suitable mechanism. Gear  2162  is preferably attached to the proximal end of the catheter  2110 , and it is preferably driven by the pinion  2164 , which is connected to a motor (not shown). The catheters  2110  and  2112  preferably contain the corresponding orientation marks provided on the shafts thereof. The console also preferably includes a connector  2170 , which electrically connects to a power generator and controller (not shown). The connector  2170  also provides electrical connections to the energy source  12  and/or the sensor of the distal tip assembly  48 . 
         [0073]    Method of Positioning the System. A method for positioning the energy source  12  within a patient and delivering energy to tissue, more specifically, for delivering ablation energy to tissue, such as heart tissue, to create a conduction for treatment of atrial fibrillation in a patient preferably includes the following steps. The method may alternatively include any other suitable steps or combinations thereof for any other suitable purpose and/or therapy. 
         [0074]    A guide sheath is positioned across the atrial septum S of a heart in a conventional way (as shown in  FIG. 1  and  FIG. 5 ). The opening of the guide sheath is preferably directed towards the pulmonary veins of the heart chamber. In  FIG. 5 , the guide sheath  2118  is advanced across the atrial septum into the left atrium. The outer catheter  412  extends from the guide catheter  2118  and is bent into a curve  498  so that its distal tip faces toward a pulmonary vein. The therapeutic catheter  2410  having distal housing  414  extends from the outer catheter and may be slidably moved away from or into the outer catheter in the direction indicated by arrow  2452 . The therapeutic catheter may also be rotated in the direction  456  (or in the opposite direction) relative to the outer catheter. The therapeutic catheter may also be bend along its length to further adjust the position of the distal assembly which directs energy into the tissue to be treated. In this embodiment, a plurality of coiled wires  428  extending from aperture  427  in the therapeutic catheter are positioned into the pulmonary veins in order to help anchor the device  400  relative to the treatment region. The distal assembly is thus rotated about the positioning wires  428 ,  430  to create a substantially circular zone of ablation around both pulmonary veins. 
         [0075]    As shown in  FIG. 3  (wherein the elongate member is positioned within the heart chamber as shown in  FIG. 1 ), anchor mechanism  570  is advanced through the guide sheath  522  and beyond the guide sheath  522  open end towards the tissue area in the middle of the pulmonary veins (PV) (not shown) such that the anchor mechanism  522  points generally towards a part of the tissue surrounded by the PV. 
         [0076]    Referring still to  FIG. 3 , the expandable member  588  of the anchor mechanism  570  is inflated with a fluid such that a distal portion of the anchor mechanism  570  is held firmly in the guide sheath  522 . 
         [0077]    The therapy catheter  510  is advanced through the inner lumen  590  of the anchor mechanism  570  and into the heart chamber. 
         [0078]    As shown in  FIGS. 4A-4C , the distal tip assembly  48  of the elongate member  18  is bent into a shape using the bending mechanism. In this step, the elongate member may be bent in any suitable configuration as described above, for any suitable purpose (e.g. for therapy and/or diagnosis). 
         [0079]    Once within the heart chamber, the distal tip assembly  48  and the sensor within it are preferably moved around the chamber such that the sensor can detect the relevant characteristics of the tissue and location of the energy source  12  with respect to the tissue. The sensor is preferably moved along an imaging path that is the same as the intended ablation path and/or the sensor is preferably moved along an imaging sweep, as shown by pattern  68  in  FIG. 7 . 
         [0080]    Once the system is positioned in the desired configuration and within the desired location with respect to the target tissue, and any desired imaging sweeps (one example of an imaging sweep is shown by pattern  68  in  FIG. 7 ) have been performed, the energy source  12  is preferably energized by a generator (not shown) to provide an energy beam  20  of emitted ultrasound energy, which impinges on the target tissue. This energy beam  20  creates an ablation zone in the tissue along the desired (and verified) ablation path. 
         [0081]    Referring again to  FIG. 3 , catheter  510  is progressively rotated about an axis in a manner  552  such that the tip assembly and the sound beam traverses in a substantially circular ablation path in the heart chamber. Alternatively, the catheter may be rotated and bent in a suitably combination to create a linear, or noncircular ablation path. The treatment of tissue along an ablation path is continued until a partial or a complete ablation of transmural thickness is achieved along the entire ablation path. As the therapy catheter  510  is rotated, the rotation movement preferably includes local oscillation movement, as described above, in order to reduce torque buildup and/or static friction such that the catheter does not jerk and will rotate smoothly. 
         [0082]    As an added feature, the system can regularly, on a timeshared basis, convert from ablation mode briefly to imaging mode (e.g. convert from the activation of the energy source  12  to the sensor, or run both simultaneously). In this way, the correct gap or other parameters can be monitored during the ablation. A complete ablation ring is made around all the targeted pulmonary veins, thereby achieving a conduction block. As described, the ablation path is generally circular, but may alternatively be elliptical, linear, curved, and/or any suitable combination of geometries to preferably achieve a conduction block. 
         [0083]    The elongate member is returned to a relaxed position by releasing the pull tension on the respective pull wires (not shown) and the therapy catheter  510  is retracted through the anchor mechanism. 
         [0084]    The expandable member  588  of the anchor mechanism  570  is deflated and the anchor mechanism  570  is retracted through the guide sheath  522  and the guide sheath  522  is removed from the body. 
         [0085]    Although omitted for conciseness, the preferred embodiments include every combination and permutation of the various elongate members  18 , distal tip assemblies  48 , energy sources  12 , sensors, bending mechanisms, and anchoring mechanisms. 
         [0086]    As a person skilled in the art will recognize from the previous detailed description and from the figures and claim, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of this invention defined in the following claims.