Abstract:
A device and method for treating a variety of tissue locations within a patient&#39;s body using a single device that includes an elongate body having a distal portion, a shaft rotatably and slidably disposed within the elongate body, and a first arm and a second arm each coupled to the elongate body distal portion. Retraction and rotation of the shaft transitions the each arm from a linear configuration to a radially expanded configuration in which each arm has an arcuate shape and lies in a plane that is substantially orthogonal to the elongate body longitudinal axis. Electrodes coupled to the arms are equidistant from the longitudinal axis of the elongate body in different radial directions when the device is in the radially expanded configuration. The electrodes are radially symmetrical about the shaft when the radially expanded configuration has a first diameter or a second diameter.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     n/a 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     n/a 
     FIELD OF THE INVENTION 
     The present invention relates to a device and method for treating a variety of tissue locations within a patient&#39;s body using a single device. In particular, the present invention relates to a device and method for thermally treating any or all of cardiac wall tissue, pulmonary vein ostia, pulmonary vein antra, and cardiac septal wall tissue with a medical device having an adjustable electrode array. 
     BACKGROUND OF THE INVENTION 
     Cardiac arrhythmia is term used to broadly describe a group of cardiac conditions involving abnormal electrical activity in the heart. In atrial fibrillation (AF), the most common type of cardiac arrhythmia, disorganized electrical impulses (usually generated by the roots of the pulmonary veins) interrupt the normal electrical impulses generated by the sinoatrial node, which in turn causes an irregular conduction of electrical impulses to the heartbeat-generating ventricles. AF may result from a number of conditions, such as hypertension, coronary artery disease, pericarditis, lung disease, hyperthyroidism, carbon monoxide poisoning, or rheumatoid arthritis. 
     Catheter ablation frequently used to treat AF, which involves a minimally invasive procedure by which areas of cardiac tissue that facilitate the irregular electrical conduction are ablated using any of a number of energy modalities. During catheter ablation, one or more pulmonary veins (PVs) may be targeted. AF is commonly initiated by foci located in the PVs. PVs are large blood vessels that carry oxygenated blood from the lungs to the left atrium (LA) of the heart. In order to disrupt the propagation of abnormal electrical currents, the ablation catheter is placed around the opening of the PV to the heart and/or within the PV where the foci are located. However, the PVs are usually not regularly shaped, and often have an asymmetrical interior that can be difficult to navigate. Further, the openings of two closely positioned PVs may form a single irregular opening, which can make ablation with many currently used ablation elements ineffective (for example, single loop-style ablation elements or the treatment elements of focal catheters). Additionally, the treatment of other types of cardiac arrhythmia may require ablation of tissue in or around the PV and tissue in other areas of the heart. However, it is often necessary to use more than one device in order to effectively destroy aberrant electrical currents. Having to replace a device during surgery can be time consuming, difficult to accomplish, and potentially dangerous for the patient. 
     Currently available devices may be used to treat conditions such as complex fractionated arterial electrograms (CFAEs), used for septal ablation, used to ablate pulmonary vein ostia, and used to create linear ablation lesions. Each of these devices is effective in ablating tissue, and each may be particularly suited to a certain area of anatomy. For example, some catheters may includes an electrode array that is well-suited for creating circumferential lesions about pulmonary vein ostia, whereas others do not include an expandable treatment element and are effective in creating linear lesions. As such, it may be necessary to use multiple ablation devices for treating a single atrial fibrillation patient, depending on the location(s) and number of aberrant electrical pathways that must be addressed. 
     Accordingly, an ablation device having one or more ablation elements suitable for treating aberrant electrical currents in a variety of cardiac locations is desired. In particular, the desired device is suitable for treating AF and other arrhythmias by ablating a variety of cardiac tissues, including the pulmonary veins, septum, and heart wall. 
     SUMMARY OF THE INVENTION 
     The present invention advantageously provides a device and method for treating a variety of tissue locations within a patient&#39;s body using a single device. In one embodiment, the device may generally include an elongate body including a longitudinal axis, a shaft rotatably and slidably disposed within the elongate body, a first arm including a distal end coupled to the shaft and a proximal end coupled to the elongate body, and a second arm including a distal end coupled to the shaft and a proximal end coupled to the elongate body. Retraction and rotation of the shaft may transition the first and second arms from a linear configuration to a radially expanded configuration in which each arm has an arcuate shape and lies in a plane that is substantially orthogonal to the elongate body longitudinal axis. The device may further include a first plurality of electrodes coupled to the first arm and a second plurality of electrodes coupled to the second arm. Each electrode may be equidistant from the longitudinal axis of the elongate body in different radial directions when the device is in the radially expanded configuration. Further, the electrodes may have a radial symmetry about the shaft. The elongate body may define a distal portion and a proximal portion and the shaft defines a distal portion and a proximal portion, the distal portion of the shaft extending distal of the distal portion of the elongate body. The device may further include a distal cap coupled to the distal portion of the shaft and the distal end of each of the first arm and second arm, each of the first arm and second arm having a midpoint that is equidistant from the distal cap and the distal portion of the elongate body. For example, the midpoint of the first arm and the midpoint of the second arm may be approximately 180° from each other in the plane that is substantially orthogonal to the elongate body longitudinal axis when the medical device is in the radially expanded configuration. The radially expanded configuration may include a diameter that is adjustable from a first diameter to at least a second diameter, the second diameter being greater than the first diameter. When the radially expanded configuration has a first diameter, the shaft may be rotated between approximately 45° and approximately 90° (for example, approximately 60°), such as by a rotational knob in a handle that is in communication with the proximal portion of the shaft. Further, when the radially expanded configuration has a second diameter, the shaft may be rotated less than approximately 45°. 
     In another embodiment, the device may generally include a first arm and a second arm each coupled to a distal portion of the medical device, the first arm and second arm each having a distal end and a proximal end, retraction of the distal ends of the first and second arm toward the proximal ends of the first and second arm transitioning the first and second arms from a linear configuration to a radially expanded configuration in which each arm has an arcuate shape and lies in a plane that is substantially orthogonal to the elongate body longitudinal axis. The medical device may define a longitudinal axis, the first arm includes a first plurality of electrodes and the second arm includes a second plurality of electrodes, each of the first and second plurality of electrodes being equidistant from the longitudinal axis of the medical device in different radial directions when the device is in the radially expanded configuration. The radially expanded configuration may have a diameter that is adjustable from a first diameter to at least a second diameter, each of the first and second plurality of electrodes being equidistant from the longitudinal axis of the medical device in different radial directions when the radially expanded configuration has a first diameter and when the radially expanded configuration has as second diameter. 
     The method may generally include transitioning a distal end of a medical device having a longitudinal axis from a linear configuration to a radially expanded configuration, the distal end of the medical device including a first arm having a plurality of electrodes and a second arm having a plurality of electrodes, the first arm and second arm lying along an axis that is parallel to the medical device longitudinal axis when the medical device is in the linear configuration, and the first arm and second arm lying in a plane that is substantially orthogonal to the medical device longitudinal axis when the medical device is in the radially expanded configuration. The radially expanded configuration may be adjustable between having a first diameter and having a second diameter. The method may further include activating the electrodes and creating an ablation lesion at any of a variety of locations within a patient&#39;s heart. For example, the method may include at least one of creating a linear ablation lesion on cardiac wall tissue, creating a circumferential ablation lesion on cardiac wall tissue, creating a circumferential ablation lesion about a pulmonary vein ostium, creating a circumferential ablation lesion about a pulmonary vein antrum, creating a circumferential ablation lesion within a pulmonary vein, and creating a lesion on cardiac septal wall tissue. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
         FIG. 1A  shows a medical system including an ablation device with an adjustable electrode array; 
         FIG. 1B  shows a device distal portion with adjustable electrode array in a first (linear) configuration; 
         FIG. 1C  shows a device distal portion with adjustable electrode array in a first (linear) configuration with arms slightly spaced apart, so as to clearly illustrate device components; 
         FIG. 1D  shows a close-up view of the point of connection between the first and second electrode arms and the shaft; 
         FIG. 1E  shows a device having an adjustable electrode array in a linear configuration being used to ablate cardiac tissue; 
         FIG. 2  shows a steering mechanism configuration that results in the distal portion having a first (linear) configuration; 
         FIG. 3A  shows a first view of a device distal portion with an adjustable electrode array in a second (radially expanded) configuration; 
         FIG. 3B  shows a second view of a device distal portion with an adjustable electrode array in a second (radially expanded) configuration; 
         FIG. 3C  shows a third view of a device distal portion with an adjustable electrode array in a second (radially expanded) configuration; 
         FIG. 3D  shows a device having an adjustable electrode array in a radially expanded configuration being used to ablate a pulmonary vein ostium; 
         FIG. 3E  shows a device having an adjustable electrode array in a radially expanded configuration being used to ablate a septal wall; 
         FIG. 4  shows a steering mechanism configuration that results in the distal portion having a second (radially expanded) configuration; 
         FIG. 5A  shows an anterior view of an adjustable electrode array in a second (radially expanded) configuration; and 
         FIG. 5B  shows an anterior view of an adjustable electrode array in a third (increased-diameter radially expanded) configuration. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIGS. 1A-1C , a medical system including an ablation device with an adjustable electrode array coupled to the distal end of the device is shown. The system  10  may generally include a medical device  12  for thermally treating or ablating an area of tissue, and a console  14  that houses various system controls. The system  10  may be adapted for use with a variety of energy modalities, including but not limited to, cryoablation, radiofrequency (RF) ablation, ultrasound ablation, microwave ablation, and laser ablation. For example, the system  10  shown in  FIG. 1A  may be suitable for use during RF ablation procedures. 
     The device  12  may generally include a handle  16 , elongate body  18  having a distal portion  20  and a proximal portion  22 , and one or more treatment elements  24  (for example, RF electrodes). The device  12  may have a longitudinal axis  26 . The elongate body  18  may also have a longitudinal axis, which may be substantially coaxial with the device longitudinal axis  26 . As shown in  FIGS. 1A-1C , the distal portion  20  may include an electrode array  28  that is adjustable from a first (linear) configuration, as shown in  FIGS. 1A-1C , to a variety of other configurations. For example, the adjustable electrode array may be transitionable from the first configuration to at least a second (radially expanded) configuration (as shown in  FIGS. 3A-3C and 5A ) and a third (increased-diameter radially expanded) configuration (as shown in  FIG. 5B ). The electrode array  28  may include a first electrode arm  30  (also referred to as “arm  30 ”) and a second electrode arm  32  (also referred to as “arm  32 ”), each of which bearing a plurality of electrodes  24 . For example, four electrodes  24  may be coupled to each arm  30 ,  32 . The configuration shown in  FIG. 1C  is a linear configuration shown with the arms  30 ,  32  slightly spaced apart so as to better illustrate individual components of the device. 
     Each electrode  24  may be composed of a conductive or selectively conductive material and each electrode  24  may include a thermocouple (not shown). For example, the electrodes  24  may be composed of gold, which is nearly 4.5 times as thermally conductive as platinum. As a result, a gold electrode may maintain a more uniform temperature across the entirety of its surface area than a platinum electrode of the same dimensions. This allows for enhanced accuracy in temperature measurement, regardless of the thermocouple position. Each electrode  24  may be, for example, a band electrode that is affixed or otherwise coupled to an exterior surface of the arms  30 ,  32 . Alternatively, each electrode may be an exposed portion of the arm  30 ,  32 . That is, the arms  30 ,  32  may be coated with a layer of insulative material, which layer may be removed in certain areas to expose a conductive or selectively conductive material layered beneath the insulative material. These exposed areas are conductive (or selectively conductive) and function in the same manner as band electrodes. In addition or as an alternative to ablation, the electrodes  24  may be used for pacing and/or mapping cardiac tissue. 
     The elongate body  18  of the device  12  may include one or more lumens. As shown in  FIGS. 1A-1C , elongate body  18  of the device  12  may include a main lumen  34  in which a shaft  36  is rotatably and slidably disposed. The longitudinal axis of the shaft  36  may be substantially coaxial with the device longitudinal axis  26 . Further, the shaft  36  may include a guidewire lumen  40  in which a guidewire  42  is rotatably and slidably disposed. Thus, the device  12  may be referred to as an “over-the-wire” device. The distal end  44  of the shaft  36  and the distal end  46 ,  48  of each arm  30 ,  32  may be coupled together by a distal cap  50  that is atraumatic to the patient. The proximal end  52 ,  54  of each arm  30 ,  32  may be secured within the distal portion  20  of the elongate body  18 . For example, the proximal end  52 ,  54  of each arm  30 ,  32  may be coupled to a cuff  56  having an aperture through which the shaft  36  may be extended, retracted, and rotated. Each arm  30 ,  32  may include a midpoint  57 A,  57 B that is substantially equidistant between the distal cap  50  and the point  58  at which the arms  30 ,  32  exit the elongate body  18 . In other words, the midpoint  57 A,  57 B (shown in the figures as an imaginary dot) represents the middle point of the exposed portion of each arm  30 ,  32  not captured beneath the distal cap  50  or disposed within the elongate body  18 . 
     If the device  12  is a cryoablation catheter, for example, the elongate body  18  may include a fluid injection lumen in fluid communication with a coolant reservoir  59 , and a fluid return lumen in fluid communication with a coolant return reservoir  60 . Depending on the energy modality being used, the lumens of the elongate body  18  may be in fluid communication with any of a number of fluids, such as saline. In some embodiments, one or more other lumens may be disposed within the main lumen, and/or the main lumen may function as the fluid injection lumen or the fluid return lumen. If the ablation catheter includes thermoelectric cooling elements or electrodes capable of transmitting radiofrequency (RF) (as shown in  FIGS. 1A-5B ), ultrasound, microwave, electroporation energy, or the like, the elongate body  18  may include a lumen in electrical communication with an energy generator  62 . 
     The console  14  may be in electrical and fluid communication with the medical device  12  and include one or more fluid (such as coolant or saline) reservoirs  59 , fluid return reservoirs  60 , energy generators  62  (for example, an RF or electroporation energy generator), and computers  64  with displays  66 , and may further include various other displays, screens, user input controls, keyboards, buttons, valves, conduits, connectors, power sources, processors, and computers for adjusting and monitoring system  10  parameters. The computer  64  may include one or more processors that are in electrical communication with the one or more system components for controlling energy application and/or duration, performing mapping functions, and/or comparing patient or system measurements to threshold measurements to ensure patient safety and/or the delivery of efficient treatment. 
     Referring now to  FIG. 1D , a close-up view of the point of connection between the first and second arms and the shaft is shown. As described regarding  FIGS. 1A-1C , The proximal end  52 ,  54  of each arm  30 ,  32  may be secured within the distal portion  20  of the elongate body  18 . As a non-limiting example, the proximal end  52 ,  54  of each arm  30 ,  32  may be coupled to a cuff  56  having an aperture through which the shaft  36  may be extended, retracted, and rotated. Extending the shaft  36  from the distal portion  20  of the elongate body  18  will likewise extend the arms  30 ,  32 , causing them to lie flat against the shaft  36  (not shown), or will at least cause the electrodes  24  to lie along an axis that is substantially parallel to the device longitudinal axis  26  (as shown in  FIG. 1B ). Rotation of the shaft  36  does not move the proximal end  52 ,  54  of each arm  30 ,  32 , but may rotate the distal end  46 ,  48  of each arm  30 ,  32 , thereby putting a helical or semi-helical twist in each arm  30 ,  32  about the shaft  36 . The degree of twisting may depend on the degree of rotation of the shaft  36  (as shown and described in  FIGS. 2-4 ). 
     Referring now to  FIG. 2 , a steering mechanism configuration that results in the distal portion having a first (linear) configuration is shown. The proximal portion  22  of the elongate body  18  may be coupled to the handle  16 . Additionally, a proximal portion  68  of the shaft  36  may be in mechanical communication with one or more actuation elements within the handle  16 . For example, as shown in  FIG. 2 , the shaft  36  may be extended and retracted by a slide knob  70  and may be rotated by a rotational knob  72 . When the electrode array  28  is in the linear configuration (as shown in  FIGS. 1A-1C ), the slide knob may be fully advanced toward the distal end  74  of the handle  16  and the rotational knob  72  may be in the neutral position (0° rotation). 
     When the electrode array  28  is in the linear configuration, the device  12  may be suitable for creating linear lesions (as shown in  FIG. 1E ). Linear lesions may be desirable when the aberrant electrical activity occurs in the heart wall, such as the wall of the right or left atrium, or if a roof-line ablation is performed (that is, a linear ablation between the left and right superior pulmonary veins). Additionally, the over-the-wire design of the device  12  may allow the device  12  to be anchored within the left superior pulmonary vein during a roof-line ablation procedure. Further, when the electrode array  28  is transitioned to other configurations, the same device  12  may also be used to treat other areas of the heart, such as the pulmonary vein ostia and septum (as shown in  FIGS. 3D and 3E ). 
     Referring now to  FIGS. 3A-3C , a device distal portion with an adjustable electrode array in a second (radially expanded) configuration is shown. When the shaft  36  is rotated and retracted, the distal cap  50  and distal end  46 ,  48  of each arm  30 ,  32  are brought toward the distal portion  20  of the elongate body  18  and the arm proximal ends  52 ,  54 , and the arms  30 ,  32  are slightly twisted about the shaft  36 . As a result, the electrode array  28  transitions from a linear configuration to a radially expanded configuration, in which each arm  30 ,  32  has an arcuate shape (that is, bowing out in a direction that is approximately 180° from the other arm). This configuration is clearly seen in the anterior view of  FIG. 3B . Further, when the electrode array  28  is in the radially expanded configuration, the two arms  30 ,  32  may be coplanar and lie in a plane that is substantially orthogonal to the device longitudinal axis  26  (as shown in  FIG. 3C ). In the radially expanded configuration, the midpoints  57 A,  57 B may be approximately 180° from each other along a line (referred to in  FIGS. 3A, 3B, 5A, and 5B  as line “D”) that is in the plane in which the arms  30 ,  32  lie, substantially orthogonal to the device longitudinal axis  26 . Additionally, the midpoints  57 A,  57 B are each located a radial distance (referred to in  FIG. 3B  as “r”) from the longitudinal axis  26 . 
     Referring now to  FIG. 4 , a steering mechanism configuration that results in the distal portion having a second (radially expanded) configuration is shown. In the radially expanded configuration, the device  12  may be suitable for creating circumferential lesions, such as when ablating pulmonary vein ostia or an inner diameter of a hollow anatomical structure (for example, a pulmonary vein). Additionally, in this configuration the device  12  may be used to ablate the septum (as shown in  FIG. 3E ). As shown and described in  FIG. 3C , when in the radially expanded configuration the arms  30 ,  32  may lie in a plane that is substantially orthogonal to the device longitudinal axis  26 , and this lends strength to the electrode array  28  when the array  28  is pulled back against the septum. That is, the arms  30 ,  32  will not be inadvertently bent toward the distal cap  50 , as could occur in ablation devices that have an electrode array that is canted toward the distal tip of the device. 
     When the electrode array  28  is in the radially expanded configuration (as shown in  FIGS. 3A-3C ), the slide knob may be fully retracted toward the proximal end  76  of the handle  16  and the rotational knob  72  may be rotated by an angle between approximately 45° and approximately 90° (for example, 60°) in a clockwise or counterclockwise direction. However, any degree of rotation may be used, depending on the desired diameter 
     Referring now to  FIGS. 5A and 5B , anterior views of an adjustable electrode array in a second (radially expanded) configuration and at least a third (increased-diameter radially expanded) configuration are shown for comparison. The diameter D 2  of the electrode array  28  between the midpoint  57 A,  57 B of each arm  30 ,  32  in the increased-diameter radially expanded configuration (as shown in  FIG. 5B ) may be greater than the diameter D 1  of the electrode array  28  between the midpoint  57 A,  57 B of each arm  30 ,  32  in the radially expanded configuration ( FIG. 5A ). It will be understood that the electrode array  28  may be adjustable to have any of a range of diameters other than those shown in  FIGS. 5A and 5B , depending on the degree of shaft  36  rotation. Depending on the size of the radius, the electrode array  28  may optionally be used to perform a first ablation, rotated approximately 90°, and used to perform a second ablation in order to create a fully circular lesion. Additionally, not only is the diameter of the electrode array  28  adjustable, but electrode  24  symmetry about the shaft  36  is preserved regardless of the diameter of the electrode array  28 . That is, the arms  30 ,  32  are symmetrically positioned about the longitudinal axis  26 , the distance between the longitudinal axis  26  and the midpoint  57 A,  57 B of each arm being equidistant. In both configurations shown in  FIGS. 5A and 5B , the electrode array  28  may appear to have a lobed shape, with each lobe comprising an arm  30 ,  32 . The lobes are separated by an angle α. As the radial distance between the midpoint  57 A,  57 B of each the arms  30 ,  32  and the longitudinal axis  26  increases, the angle α between the lobes also increases. The first angle α (in  FIG. 5A ) is referred to as α 1  and the second angle α (in  FIG. 5B ) is referred to as α 2 . An adjustable radius may be particularly useful for accommodating a variety of pulmonary vein diameters. The first radius r (in  FIG. 5A ) is referred to as r 1  and the second, increased radius (in  FIG. 5B ) is referred to as r 2 . Thus, the device  12  may not only perform the function of linear and septal ablation catheters, but may also perform the function of, and improve upon, multiple types of pulmonary vein ostia ablation catheters. 
     To achieve the increased-diameter configuration, the shaft  36  may be retracted and rotated so that the distal cap  50  is brought toward the elongate body distal portion  20 , similar to the method for transitioning the electrode array  28  to the radially expanded configuration. However, the shaft  36  may be rotated less than approximately 45°, thus causing the arms  30 ,  32  to bow out at a greater degree of curvature (that is, causing each arm  30 ,  32  to form a lobe with a midpoint  57 A,  57 B that is a greater radial distance from the longitudinal axis  26 ) than when the shaft is rotated approximately 45° or more. This greater degree of curvature translates to a greater electrode array  28  radius. 
     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope and spirit of the invention, which is limited only by the following claims.