Patent Publication Number: US-2020297412-A1

Title: Directional balloon transseptal insertion device for medical procedures

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of U.S. Provisional Application Ser. No. 62/821,062, filed on Mar. 20, 2019, which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to cardiac catheters, and more particularly, to a transseptal insertion device which is suitable for facilitating quick and safe transseptal puncture and insertion of a catheter through a cardiac septum to provide access to the left atrium in implementation of a left atrial intervention. 
     BACKGROUND 
     Cardiac catheterization is a medical procedure in which a long thin tube or catheter is inserted through an artery or vein into specific areas of the heart for diagnostic or therapeutic purposes. More specifically, cardiac chambers, vessels and valves may be catheterized. 
     Cardiac catheterization may be used in procedures such as coronary angiography and left ventricular angiography. Coronary angiography facilitates visualization of the coronary vessels and finding of potential blockages by taking X-ray images of a patient who has received a dye (contrast material) injection into a catheter previously injected in an artery. Left ventricular angiography enables examination of the left-sided heart chambers and the function of the left sided valves of the heart, and may be combined with coronary angiography. Cardiac catheterization can also be used to measure pressures throughout the four chambers of the heart and evaluate pressure differences across the major heart valves. In further applications, cardiac catheterization can be used to estimate the cardiac output, or volume of blood pumped by the heart per minute. 
     Some medical procedures may require catheterization into the left atrium of the heart. For this purpose, to avoid having to place a catheter in the aorta, access to the left atrium is generally achieved by accessing the right atrium, puncturing the interatrial septum between the left and right atria of the heart, and threading the catheter through the septum and into the left atrium. Transseptal puncture must be carried out with extreme precision, as accidental puncturing of surrounding tissue may cause very serious damage to the heart. In addition, transseptal puncture may require complicated instruments which are not helpful in guaranteeing the precision of the puncture. 
     The use of devices available today present many challenges for doctors attempting to puncture the interatrial septum and perform cardiac catheterization. Locating the interatrial septum, properly placing the distal end of the puncturing device at the desired location of the septum, safely puncturing the interatrial septum, avoiding accidental punctures, and tracking and maneuvering the catheter post-puncture, are among the many challenges facing those performing cardiac catheterization today. 
     SUMMARY 
     Accordingly, there is an established need for a device that is suitable for facilitating quick and safe transseptal puncturing to provide access to the left atrium in implementation of a left atrial intervention. 
     These and other advantages may be provided by, for example, a transseptal insertion device which is suitable for facilitating precise and safe transseptal puncture of a cardiac interatrial septum. The transseptal insertion device includes a sheath that defines at least one lumen therein, one or more balloons, one or more ultrasound transceivers, and a dilator. The sheath has a distal end that is closest to the cardiac interatrial septum of a patient when the transseptal insertion device is in use and a proximal end that is external to the patient. The one or more balloons are connected to the distal end of the sheath and are contained in the sheath. The balloons, when inflated and the transseptal insertion device is in use, overhangs and extends past the distal end of the sheath, preventing accidental puncturing of the cardiac interatrial septum and stabilizing the transseptal insertion device against fossa ovalis of the cardiac interatrial septum. The one or more ultrasound transceivers emit and receive ultrasound waves, and convert the ultrasound waves to electrical signals. The dilator is positioned within the at least one lumen. The dilator has a distal end and is designed to and is capable of precisely puncturing the cardiac interatrial septum. 
     The transseptal insertion device may further include one or more hypotubes connected to the one or more balloons. The one or more balloons are inflated by gas or fluid flowing through the one or more hypotubes. The transseptal insertion device may further include at least one lumen shaft contained in the sheath. The at least one lumen shaft defines the at least one lumen and the dilator is positioned in said at least one lumen shaft. The one or more hypotubes may be contained in the sheath outside said at least one lumen shaft. The one or more ultrasound transceivers may be located on surfaces of the one or more balloons. The one or more ultrasound transceivers may be located between the balloons. The one or more ultrasound transceivers may be oriented towards the cardiac interatrial septum when the one or more balloons are inflated and the distal end of the sheath is oriented towards the cardiac interatrial septum. The one or more ultrasound transceivers may be oriented perpendicular to the sheath when the balloons are deflated. The one or more ultrasound transceivers may be configured in the shape of a disc. The one or more ultrasound transceivers may be connected to an external imaging device wirelessly or through a wire that runs via the sheath, and may transmit the electrical signals to the external imaging device to produce images of the cardiac interatrial septum from the received electrical signals. The dilator may include cap or crown with radio frequency (RF) energy capability or capable of delivering RF energy. 
     These and other advantages may be provided by, for example, a transseptal insertion device which is suitable for facilitating precise and safe transseptal puncture of a cardiac interatrial septum. The transseptal insertion device includes a sheath that defines at least one lumen therein, at least one balloon, one or more ultrasound transceivers, and a dilator. The sheath has a distal end that is closest to the cardiac interatrial septum of a patient when the transseptal insertion device is in use and a proximal end that is external to the patient. The at least one balloon is connected to the distal end of the sheath. The balloon, when inflated and the transseptal insertion device is in use, overhangs and extends past the distal end of the sheath, preventing accidental puncturing of the cardiac interatrial septum and stabilizing the transseptal insertion device against fossa ovalis of the cardiac interatrial septum. The one or more ultrasound transceivers emit and receive ultrasound waves, and convert the ultrasound waves to electrical signals. The dilator is positioned within the at least one lumen. The dilator has a distal end and is designed to and is capable of precisely puncturing the cardiac interatrial septum. 
     The transseptal insertion device may further include at least one hypotube connected to the at least one balloon. The at least one balloon is inflated by gas or fluid flowing through the at least one hypotube. The transseptal insertion device may further include at least one lumen shaft contained in the sheath. The lumen shaft may define the at least one lumen and the dilator may be positioned in said at least one lumen shaft. The hypotube may be contained in the sheath outside the at least one lumen shaft. The one or more ultrasound transceivers may be located on a surface of the at least one balloon. The one or more ultrasound transceivers may be oriented towards the distal end of the sheath when the at least one balloon is inflated and the distal end of the sheath is oriented towards the cardiac interatrial septum. The one or more ultrasound transceivers may be oriented perpendicular to the sheath when the at least one balloon is deflated. The one or more ultrasound transceivers may be connected to an external imaging device wirelessly or through a wire that runs via the sheath, and transmit the electrical signals to the external imaging device to produce images of the cardiac interatrial septum from the received electrical signals. The dilator may include cap or crown with radio frequency (RF) energy capability or capable of delivering RF energy. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of embodiments disclosed herein are described below in connection with the accompanying drawings. The preferred embodiments described herein and illustrated by the drawings hereinafter be to illustrate and not to limit the invention, where like designations denote like elements. 
         FIG. 1A  is a side perspective, cross-sectional view of an embodiment of a transseptal insertion device. 
         FIG. 1B  is a side perspective, cross-sectional view of an embodiment of a transseptal insertion device showing a dilator extending partially through and extending out from device. 
         FIG. 1C  is a side perspective, cross-sectional view of an embodiment of a transseptal insertion device showing a dilator extending partially through the device. 
         FIG. 2A  is a is a perspective view of an embodiment of a transseptal insertion device with hypotube connected to one or more balloons. 
         FIG. 2B  is a is a front view of an embodiment of a transseptal insertion device with hypotube connected to one or more balloons. 
         FIGS. 2C-2D  are side views of embodiments of transseptal insertion device with ultrasound imaging or visualizing capability. 
         FIG. 3A  is a is a perspective view of an embodiment of a transseptal insertion device with multiple balloons and hypotubes connected to the multiple balloons. 
         FIG. 3B  is a is a front view of an embodiment of a transseptal insertion device with multiple balloons and hypotubes connected to the multiple balloons. 
         FIG. 4  is a perspective, cross-sectional view of an embodiment of a transseptal insertion device with radiofrequency energy capability. 
         FIG. 5  is a is a perspective view of an embodiment of a transseptal insertion device with a drive assembly coupled to dilator, and knob coupled to the drive assembly. 
         FIG. 6  is a perspective, cross-sectional view of an embodiment of a transseptal insertion device showing inflated overhanging balloon and dilator positioned within device and subplanar to overhanging balloon. 
         FIG. 7  is a cross-sectional, end view of an embodiment of a transseptal insertion device and dilator shown prior to puncturing an interatrial cardiac septum with inflated overhanging balloon. 
         FIG. 8  is a perspective, cross-sectional view of an embodiment of a transseptal insertion device with dilator advanced forward in order to tent an interatrial septum. 
         FIG. 9  is a perspective, cross-sectional view of an embodiment of a transseptal insertion device with a transseptal wire advanced post-puncture through interatrial septum. 
         FIGS. 10A-10C  are perspective, cross-sectional views of an embodiment of a flexible transseptal insertion device with different angulations. 
         FIG. 11  is a side view of an embodiment of transseptal insertion device with an overhanging balloon with marking. 
         FIG. 12  is a side view of an embodiment of transseptal insertion device with an overhanging balloon with a marker band. 
         FIG. 13  is a cross-sectional side view of an embodiment of a transseptal insertion device that includes a dilator with an electrode tip. 
         FIG. 14  is a side view of an embodiment of a transseptal insertion device with mechanical deflection capability. 
         FIG. 15  is side views of embodiments of curved dilators that may be used in embodiments of a transseptal insertion device. 
         FIG. 16  is a perspective side view of a proximal end of an embodiment of a transseptal insertion device showing a handle and a stabilizer. 
         FIGS. 17A-17B  are side views of an embodiment of a transseptal insertion device with balloons capable of differential inflation. 
         FIG. 18  is a side view of a malleable or flexible transseptal needle that may be used in embodiments of a flexible transseptal insertion device with multiple angulations. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure, which is defined by the claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
     With reference to  FIGS. 1A-1C , shown is an embodiment of transseptal insertion device or catheter  10 . Shown is the distal end of transseptal insertion device  10 , i.e., the end of transseptal insertion device  10  with opening through which dilator, catheter, and needle may extend, e.g., to puncture interatrial cardiac septum. As shown in  FIG. 1A , transseptal insertion device  10  includes outer sheath or balloon shaft  12  and one or more balloons  14  located at distal tip  13  of transseptal insertion device  10 . Sheath  12  may contain and define a center lumen  15 . Sheath  12  may be fabricated from various materials, including, e.g., polymers, including thermoplastics elastomers (TPEs) such as PEBA (e.g., Pebax®), nylons, thermoplastic polyurethanes (TPUs) such as Pellathane®, similar materials and combinations thereof. Sheath  12  may be referred to as catheter shaft and used in cardiac catheterizations. After puncture, sheath  12  may be inserted through septum into left atrium. Alternatively, sheath  12  may contain a separate catheter that is inserted through septum post puncture. Transseptal insertion device  10  also includes dilator  16 , positioned in center lumen  15 , as shown in  FIG. 1B . The one or more balloons  14  are preferably sealed, air-tight and water-tight, on both its ends to sheath  12 . 
     With continuing reference to  FIG. 1A , in view shown, overhanging one or more balloons  14  are uninflated. Although cross-section of balloons  14  shown on top and bottom of distal tip  13 , balloons  14  preferably extend around circumference of distal tip or end  13  of transseptal insertion device  10 . Overhanging one or more balloons  14  are of form such that balloons  14  overhang or extend from distal tip  13  of sheath  12  when inflated. 
     In  FIG. 1B , dilator  16  is shown positioned within and partially extending out of sheath  12 , past distal tip  13  of device  10 . Overhanging one or more balloons  14  are uninflated and dilator  16  extends past balloons  14 . It is noted that the relative sizes of sheath  12  and dilator  16  shown are for illustrative purposes as the diameter of dilator  16  may be relatively larger or smaller than shown in relation to the diameter of sheath  12 , although dilator  16  necessarily has a smaller diameter than sheath  12 . Although dilator  16  is shown to have a pointed end, dilator  16  may have a rounded or relatively flat end. Embodiments, as described herein, are designed and intended to puncture septum without use of a needle or other sharp instrument. 
     With reference now to  FIG. 1C , dilator  16  is shown positioned within center lumen  15  of sheath  12 . Tip of dilator  16  is positioned within distal tip  13  of transseptal insertion device  10  sub-planar to end of transseptal insertion device  10 . The position shown is position dilator  16  may be in immediately prior to inflation of one or more balloons  14 . It is noted that the relative sizes of catheter/sheath  12  and dilator  16  shown are for illustrative purposes as the diameter of dilator  16  may be relatively larger or smaller than shown in relation to the diameter of sheath  12 . Ordinarily, dilator  16  has smaller diameter or gauge then catheter/sheath  12 , although fit of dilator  16  in catheter/sheath  12  is preferably snug enough so that dilator  16  does not move (laterally or axially) relative to position or “wobble” within transseptal insertion device  10 . Dilator  16  necessarily has a smaller diameter than sheath  12 . In embodiments, sheath  12  material may be sufficiently malleable to enable larger diameter dilators  16 , and other larger diameter devices, to be passed through sheath  12 . In such embodiments, sheath  12  will stretch to accommodate the larger diameter dilator  16  or other device. 
     With reference to  FIG. 2A , shown is a side perspective view of an embodiment of transseptal insertion device or catheter  200 . With reference to  FIG. 2B , shown is the distal end of transseptal insertion device  200 , i.e., the end of transseptal insertion device  200  with opening through which dilator, catheter, and needle may extend, e.g., to puncture interatrial cardiac septum. As shown in  FIG. 2A , transseptal insertion device  200  includes outer sheath or catheter shaft  212  and one or more balloons  214  located at distal tip  213  of transseptal insertion device  200 . Sheath  212  may contain lumen shaft  211  that defines center lumen  215 . Sheath  212  may be fabricated from various materials, including, e.g., polymers, including thermoplastics elastomers (TPEs) such as PEBA (e.g., Pebax®), nylons, thermoplastic polyurethanes (TPUs) such as Pellathane®, similar materials and combinations thereof. Sheath  212  may be referred to as catheter shaft and used in cardiac catheterizations. After puncture, sheath  212  may be inserted through septum into left atrium. Alternatively, sheath  212  may contain multiple lumen shafts that define multiple lumens separately. Transseptal insertion device  200  also includes dilator  216 , positioned in center lumen  215 . The one or more balloons  214  are preferably sealed, air-tight and water-tight, on both their ends to sheath  212 . Transseptal insertion device  200  includes hypotube  217  for inflation or deflation of one or more balloons  214 . Hypotube  217  may be contained in sheath or catheter shaft  212 . Transseptal insertion device  200  may further include a port (not shown) connected to hypotube  217  to supply gas or fluid to inflate one or more balloons  214 , or to remove gas or fluid from one or more balloons  214  to deflate balloons  214 . Balloons  214  may be fully inflated or deflated, or may be inflated or deflated as much as desired. With reference to  FIG. 2B , shown is a front, cross-sectional view of distal end  213  of the embodiment of transseptal insertion device  200  that shows cross-sectional views of sheath  212 , center lumen  215 , and hypotube  217 . 
     In the embodiment shown in  FIGS. 2A and 2B , transseptal insertion device  200  may include ultrasound chips or transducers  26  for ultrasound imaging or visualizing (see  FIGS. 2C and 2D ). The transseptal sheath  212  or balloon  214  may house (inside or on) an ultrasound chip or transducer which may be used to guide the insertion procedure. Ultrasound chip or transducer emits and receives ultrasound energy, that may be detected by known ultrasound visualization devices, to create an image of the cardiac chambers (e.g., the right atrium, fossa, interatrial septum, left atrium, atrial appendage, mitral valve, ventricle, etc.). Ultrasound chips and transducers are transducers that convert ultrasound waves to electrical signals and/or vice versa. Those that both transmit and receive may also be called ultrasound transceivers; many ultrasound sensors besides being sensors are indeed transceivers because they can both sense and transmit. Such imaging will allow the operator(s) of transseptal insertion device  200  to visualize the cardiac chambers and the determine the location of the distal end or tip  213  of transseptal insertion device  200 , enabling more precise operation of transseptal insertion device  200 . Such a ultrasound chips or transducers used may be similar to ultrasound chip or transducer described in US Patent Application Publication No. 2003/019546, which is herein incorporated by reference, or any other ultrasound transducer known to those of ordinary skill in the art that may be fabricated on scale small enough to be deployed on or in sheath  212  or balloon  214 . 
     With reference to  FIGS. 2C and 2D , shown are embodiments of transseptal insertion device  200  with ultrasound imaging or visualizing capability. Balloon  14  shown includes one or more ultrasound chips or transducers  26  deployed in or on balloon  14 . Ultrasounds chips or transducers  26  may be ultrasound transceivers that both emit and receive waves, convert the ultrasound waves to electrical signals, transmit the electrical signals, e.g., through a wire that runs via sheath  12 . Ultrasounds chips or transducers  26  may be connected via WiFi or other wireless connection, to an external imaging device that produces images from the received signals (both still and video images). 
     Ultrasound chips or transducers  26  may be affixed to interior or exterior surface of balloon  14 . Ultrasound chips or transducers  26  may be arranged in a line, disc, or cross-shape. Ultrasound chips or transducers  26  may be arranged to be forward facing (e.g., on distal end of balloon facing towards interatrial septum), as shown in  FIG. 2C , or in a different direction/orientation, such as sideways and forward facing (e.g., facing towards interatrial septum and facing perpendicular to the distal or front end), as shown in  FIG. 2D . Indeed, orientation of ultrasound chips or transducers  26  may depend on whether balloon  14  is inflated or not. When balloon  14  is fully inflated, as shown in  FIGS. 2C and 2D , ultrasound transducer  26  may be forward facing as shown in  FIG. 2C  or forward and perpendicularly facing as shown in  FIG. 2D . However, when balloon  14  is deflated, ultrasound transducer  26  may be folded flat and positioned on side of distal tip  13  of sheath  12 . Hence, when balloon  14  is deflated, ultrasound chip or transducer  26  may be side-facing (perpendicular to an axis of the sheath). During inflation ultrasound transducer  26  orientation will change as balloon  14  inflates (moving from side-facing orientation to forward facing orientation with the ultrasound transducer  26  shown in  FIG. 2C ). Accordingly, operator(s) of transseptal insertion device  200  may vary the inflation of balloon  14  to achieve different orientations of ultrasound transducer  26  for different imaging views. 
     Ultrasound chip or transducers  26  may emit and/or receive/detect ultrasound waves that may be reflect off of surfaces and structures, e.g., within atrium, and then read by imaging system (not shown), e.g., connected to ultrasound chips or transducers  26  via wire or cable extending through, e.g., lumen  15  in sheath  12 . In this manner, ultrasound chips or transducers  26  may enable visualization of the interatrial septum and the left atrial structures. 
     It is also noted that ultrasound chips or transducers  26  may be deployed on distal tip  13  of sheath  12  (or elsewhere on or in sheath  12 ). Ultrasound chips or transducers  26  may be installed or configured to be forward facing (facing towards distal end of sheath  12 ). Alternatively, ultrasound chips or transducers  26  may be flipped to be rear facing (facing towards proximal end of sheath  12 ). Varying orientations of ultrasound chips or transducers  26  may be implemented. 
     With reference to  FIGS. 3A and 3B , shown is transseptal insertion device  300  including multiple balloons  314 , which surround center lumen shaft  311  that defines center lumen  315 , and sheath or catheter shaft  312  that includes center lumen shaft  311  and hypotubes  317  connected to multiple balloons  314 .  FIG. 3A  is a side view of sheath or catheter shaft  312 , and  FIG. 3B  is a front cross-sectional view of sheath or catheter shaft  312 . Balloons  314  are in various shapes such as round, cylindrical, spherical, tear drop shaped or pear shaped, and are in various lengths. Balloons  314  may be with or without overhang over shaft. Balloons  314  are positioned around distal tip or end  313 , and may extend around circumference of distal tip or end  313 . Multiple balloons  314  are connected to one or more hypotubes  317 , and inflated or deflated via hypotubes  317  that are contained in sheath or catheter shaft  312 . Each of balloons  314  may be connected to corresponding hypotube  317  to independently control the inflation and deflation of balloons  314 . Alternatively, balloons  314  may share one or more hypotubes  317 . Inflation fluid or gas may flow through hypotubes  317  to inflate or deflate balloons  314 . Outer covering  319  may cover the multiple balloons  314 . 
     In between balloons  314 , there are one or more ultrasound chips or transducers  326  that provide ultrasound imaging or visualizing capability. For illustrative purposes,  FIG. 3B  shows ultrasound chips or transducers  326  disposed between balloons  314 , but ultrasound chips or transducers  326  may be deployed in or on balloons  314 . Ultrasound chips or transducers  326  may be affixed to interior or exterior surface of balloon  314 . Ultrasounds chips or transducers  326  may be ultrasound transceivers that both emit and receive waves, convert the ultrasound waves to electrical signals, transmit the electrical signals, e.g., through wire  320  that runs inside sheath or catheter shaft  312 . However, ultrasound chips or transducers  326  may be connected wirelessly via WiFi or other wireless connection, to an external imaging device that produces images from the received signals (both still and video images). 
     Ultrasound chips or transducers  326  may be designed based on the shape of the balloons  314 . The balloons  314  may be round, cylindrical, spherical, tear drop shaped or pear shaped with overhang or without overhang. Ultrasound chips or transducers  326  may have shapes corresponding to the shapes of balloons  314 . Alternatively, one or more ultrasound chips or transducers  326  may be deployed in a shape corresponding to the shapes of balloons  314 . Depending on the shapes of balloons  314 , ultrasound chips or transducers  326  may be side facing, front facing or back facing. Ultrasound chips or transducers  326  may be arranged in a line, disc, or cross-shape. Ultrasound chips or transducers  326  may be arranged to be forward facing (e.g., on distal end of balloon facing towards interatrial septum), or in a different direction/orientation, such as sideways and forward facing (e.g., facing towards interatrial septum and facing perpendicular to the distal or front end). 
     Orientations of ultrasound chips or transducers  326  may depend on whether balloons  314  are inflated or not. When balloons  314  are fully inflated, ultrasound chips or transducers  326  may be forward facing. However, when balloons  314  are deflated, ultrasound chips or transducer  326  may be folded flat and positioned on side of distal tip  313  of center lumen  315 . Hence, when balloons  314  are deflated, ultrasound chips or transducer  326  may be side-facing. During inflation, orientation of ultrasound chips or transducers  326  may change as balloons  314  inflate (moving from side-facing orientation to forward facing orientation). Accordingly, operator(s) of transseptal insertion device  300  may vary the inflation of balloons  314  to achieve different orientations of ultrasound chips or transducers  326  for different imaging views. 
     With reference now to  FIG. 4 , shown is an embodiment of transseptal insertion device  10  with radiofrequency (RF) energy capability. Transseptal insertion device  10  shown includes sheath  12 , overhanging one or more balloons  14 , and dilator  16 . Dilator  16  may include cap or crown  22 , on distal end as shown, with RF energy capability or capable of delivering RF energy. Alternatively, cap or crown may include or be an RF electrode. Dilator  16  may be connected, e.g., on proximate end (not shown) to a radiofrequency energy source (not shown) at, e.g., external hub, that provides RF energy to cap or crown  22 . The RF energy may be delivered through dilator  16 . So equipped with cap or crown  22 , dilator  16  may tent interaxial septum and create puncture of interaxial septum through delivery of RF energy. In this embodiment, the use of a sharp needle may be avoided. The dilator with cap or crown on distal end with RF energy capability or capable of delivering RF energy may be used for transseptal insertion devices  200  and  300  shown in  FIGS. 2A-2B and 3A-3B . 
     With reference to  FIG. 5 , shown is transseptal insertion device  400  including drive assembly  421 , which is coupled to dilator  416 , and knob  422  coupled to drive assembly  421  to cause dilator  416  to traverse along an axial direction of sheath or catheter shaft  412 . Dilator  416  may move backwards or forwards along the axial direction of sheath  412  while knob  422  is rotated. The drive assembly  421  may include nut assembly to drive the dilator  416 . Dilator  416  may be with or without RF energy capability. 
     With reference now to  FIG. 6 , shown is distal end of an embodiment of transseptal insertion device  10  in which overhanging balloons  14  is inflated by supplying gas or fluid into balloon  14  through hypotube (not shown). Dilator  16  is shown positioned within center lumen  15  of sheath  12  with tip of dilator  16  positioned at distal tip  13  of transseptal insertion device  10  and sub-planar to overhanging balloon  14 . The plane that is referred to here is the plane perpendicular to the axis of transseptal insertion device  10  and dilator  16 , formed by the end of overhanging balloon  14 . Hence, dilator  16  remains sub-planar to overhanging balloon  14  until operator intends balloon  14  to be deflated and dilator  16  to tent and puncture interatrial septum  100 . As noted above, balloon  14  preferably extends completely around circumference of tip  13  of transseptal insertion device  10 . Accordingly,  FIG. 7  only illustrates cross-section of inflated balloon  14 . 
     With reference now to  FIG. 7 , shown is a front, cross-sectional view of distal end an embodiment of transseptal insertion device  10  in which overhanging balloon  14  is inflated. As shown, inflated overhanging balloon  14  preferably extends around entire circumference of sheath  12  (and, therefore, device  10 ). Shown situated within lumen  15  of sheath  12  is tip of dilator  16 . Tip of dilator  16  is positioned within tip  13  of transseptal insertion device  10 , as it would be prior to being extended past tip  13  and puncturing an interatrial cardiac septum. 
     With reference now to  FIG. 8 , shown is distal end of an embodiment of transseptal insertion device  10  with dilator  16  advanced forward in order to tent the interatrial septum  100 . Dilator  16  is shown extending through center lumen  15  of sheath  12  and past overhanging balloon  14 . At this stage, balloon  14  may be deflated by removing gas or fluid in balloon  14  through hypotube. Extended as such, and pressed against interatrial septum  100 , dilator  16  tents the interatrial septum  100  away from transseptal insertion device  10 . 
     With reference now to  FIG. 9 , shown is shown is distal end of an embodiment of transseptal insertion device  10  with dilator  16  advanced forward through interatrial septum  100 , after puncturing septal wall (e.g., through application of energy through dilator  16  as described herein) and transseptal wire or wire rail  20  extending through dilator  16  and into left atrium chamber  110 . Wire rail  20  may sit in a lumen  19  of dilator  16 . Dilator  16  may be used as a conduit to advance the wire rail  20  into the left atrium. 
     Wire rail  20  may act as a guide for devices to enter the left atrium through the puncture in the septal wall made by transseptal insertion device  10 . For example, wire rail  20  may guide transseptal insertion device  10  or other catheters in the left atrium. In this manner, catheters may be advanced safely into the left atrium over or guided by wire rail  20 . In an embodiment, wire rail  20  may be energized (e.g., to ablate or puncture the septum with energy delivered from source at proximal end of transseptal insertion device  10 ). 
     With continued reference to  FIG. 9 , dilator  16  preferably defines and includes an opening or lumen  19  extending through its tip and through which transseptal wire  20  extends. With dilator  16  extended as shown and tenting interatrial septum, septum may be punctured by energy delivered through cap or electrode at tip of dilator  16  and transseptal wire rail  20  extended through opening in tip of dilator  16  and through puncture made in interatrial septum by dilator  16  cap. 
     With reference to  FIGS. 10A-10C , shown are different views of an embodiment of transseptal insertion device  10  with a flexible sheath  12  flexed or angulated at different angles. Transseptal insertion device  10  may be flexed or angulated depending on the anatomy of the atria using fixed angled dilators  16  that are inserted into lumen shaft of sheath  12 , causing sheath  12  to flex. Such fixed angled dilators  16  may be, e.g., any angle from 0-270°. Alternatively, sheath  12 , lumen shaft and dilator  16  may be all flexible (preferably, hypotubes, needle and catheter inserted through such flexible sheath  12  are flexible or malleable, at least in part) and transseptal insertion device  10  may be flexed or angulated, thereby flexing or angulating sheath  12  and dilator  16 , using, e.g., a handle or wire (not shown) connected to tip  13  of device  10 . Handle and/or wire may also be used to turn or flex or move tip  13  of transseptal insertion device  10 , e.g., moving tip  13  of sheath “up” or “down” or “left” or “right” or angulating tip  13  relative to axis of sheath  12  as shown. 
     With reference now to  FIG. 11 , shown is distal end of an embodiment of transseptal insertion device  10  with inflated overhanging balloon  14 . Balloon  14  shown is an embodiment with one or more markers  24 . Marker  24  may be, e.g., a radiopaque and/or echogenic marker  24 . As a radiopaque or echogenic marker, marker  24  will be visible on scanners used by those performing cardiac catheterizations. The markers  24  may be in the form of letters, such as an E or a C. Marker  24  enables the appropriate positioning of balloon  14  and sheath  12  in the 3-dimensional space (e.g., of the atrium) using imaging to view the marker  24  and, therefore, the position of balloon  14 . Specifically, in operation, the less posterior distal tip  13  is positioned, the more of the E (or C) will be shown. As operator of transseptal insertion device  10  turns or rotates distal tip  13  toward posterior of patient, less of the arms of the E will be seen. In a preferred embodiment, when only the vertical portion of the E is visible (i.e., appearing as an I) distal tip  13  will be rotated to its maximum posterior position. 
     With continuing reference to  FIG. 11 , balloon  14  is shown as inflated. However, distal end of dilator  16  is shown extruding or extending distally from balloon  14 , past plane formed by distal end of inflated balloon  14 . According, dilator  16  has been moved into the tenting and puncturing position, adjacent to interaxial septum. At this stage, balloon  14  may be deflated or will soon be deflated, and puncture of the interaxial septum is imminent. 
     With reference now to  FIG. 12 , shown is another embodiment of overhanging balloon  14  which may be deployed in embodiments of transseptal insertion device  10 . Overhanging balloon  14  may include ring or band  28  around a portion of balloon  14 . Ring or band  28  may serve as a marker, similar to markers  24  shown in  FIG. 11 . Hence, ring  28  may be radiopaque or echogenic and may be view by scanning devices used for visualization in cardiac catheterizations (e.g., fluoroscopic imaging devices). Similar to the letter E or C, the view of the ring  28  changes as the distal tip  13  of transseptal insertion device  10  moves more posterior. When in a least posterior position, ring  28  may appear as just a line or band positioned across axis of transseptal insertion device  10 . When device  10  is rotated so that distal tip  13  is significantly closer to the posterior, ring  28  may appear as a full “flat” circle or ring. In  FIG. 12 , distal tip  13  is partially rotated so that ring  28  is partially visible. 
     With reference to both  FIGS. 11 and 12 , the marker  24  and ring  28  are described and shown as located on balloon  14 . In embodiments, marker  24  and/or ring  28  may also be located on sheath  12  and/or dilator  16 . So located, marker  24  and/or ring  28  would operate in effectively the same manner as described above (i.e., the arms of the E would disappear as the distal end was moved more to the posterior and the ring would become more visible). Markers  24  and/or rings  28  may be placed on all of balloon  14 , sheath  12 , and dilator  16 , or a combination thereof. 
     With reference now to  FIG. 13 , shown is distal end of an embodiment of transseptal insertion device  10  that includes dilator  16  with electrode tip. Shaft of dilator  16  defines and contains a center lumen  50 . Lumen  50  may be defined in the range of, but not limited to, 0.020 to 0.040 inches. Dilator  16  may be made from a polymer material (e.g., HDPE, LDPE, PTFE, or combination thereof). Dilator shaft  16  shown includes a distal electrode tip  52 . Electrode tip  52  may be comprise a metallic alloy (e.g., PtIr, Au, or combination thereof). In preferred embodiments, the size and shape of electrode tip  52  is selected to be sufficient to generate a plasma for in vivo ablation of tissue in an applied power range of, but not limited to, 20-30 W. Electrical conductor  54  extends from electrode tip  52  to the proximal end (not shown) of the dilator  16 . Electrical conductor  54  may run axially through an additional lumen  56  defined by and contained in dilator shaft  16 . Electrical conductor  54  may contain a coil feature  58  to accommodate lengthening during bending or flexing of dilator  16 . 
     Attached to distal end of sheath  12  is contains overhanging balloon  14  that is connected to hypotube  17 . Overhanging balloon  14  may be made from a polymer material (e.g., PET, Nylon, Polyurethane, Polyamide, or combination thereof). Overhanging balloon  14  may be in the range of, but not limited to, 5-20 mm in diameter and 20-30 mm in length. Overhanging balloon  14  may be inflated via injection of gas or fluid through hypotube  17  connected to balloon  14 . Overhanging balloon  14  may be deflated by removing gas or fluid in balloon  14  through hypotube  17  connected to balloon  14 . During the proper functioning or operation of transseptal insertion device  10  for puncturing the interatrial septum, balloon  14  may be deflated when dilator  16  moves out of lumen  15  by removing gas or fluid from balloon  14 . Overhanging balloon  14  is of form such balloon  14  overhangs or extends from distal end  13  of sheath  12 . Overhang or extension  60  may be in the range of, but not limited to, 0.0 mm-5.0 mm. The end of the overhang or extension  60  is the plane to which dilator  16  remains sub-planar until moving to tent and puncture the interatrial septum. 
     With reference now to  FIG. 14 , shown is an embodiment of transseptal insertion device  10  that includes a mechanical deflection mechanism. Mechanical deflection mechanism may enable distal end of sheath  12  to be deflected or angulated to various angles with respect to axis of transseptal insertion device  10 . Mechanical deflection mechanism may include a pull wire anchor  40  affixed to distal end of sheath  12  and pull wire actuator  42  connected to pull wire anchor  40  with pull wire (not shown). Rotation of pull wire actuator  42 , as shown, may exert force on pull wire anchor  40  that deflects or angulates distal end of sheath  12 . Pull wire actuator  42  may be rotated by handle connected thereto (not shown). Deflection or angulation of distal end of sheath  12  may enable better intersection (e.g., more perpendicular, flush) with interaxial septum and, therefore, better puncture and insertion by transseptal insertion device  10 . 
     With reference now to  FIG. 15 , shown are three (3) embodiments of curved dilators  16 , each with a different curve profile (i.e., different angle of deflection or curve). Curved dilators  16  may be used in embodiments of transseptal insertion device  10  with flexible or malleable sheath  12 . Such a flexible or malleable sheath  12  may be referred to as a steerable sheath  12  as it is “steered” by curved dilator  16  inserted in sheath  12 . 
     With reference now to  FIG. 16 , shown is an embodiment of transseptal insertion device  10  with an external stabilizer  80 . Stabilizer  80  keeps proximal end of transseptal insertion device  10  stable while allowing movement of transseptal insertion device  10  towards the distal and proximal ends of device  10 , rotational/torqueing movement of proximal end of device  10 , and manipulation of dials or other controls of device  10 . In effect, stabilizer  80  substantially prevents unwanted movement of the transseptal insertion device  10  and, importantly, distal end of sheath  12 , balloon  14 , and dilator  16 . 
     Stabilizer  80  includes connecting rods or arms  82  that connect stabilizer  80  to handle  70  at proximal end of transseptal insertion device  10 . Connecting arms  82  are attached to stabilizer platform  84 . Connecting arms  82  preferably hold the handle  70  securely and tightly, while permitting desired rotational movements and control manipulation. Stabilizer platform  84  is moveably attached to stabilizer base  86  so that stabilizer platform  84 , and hence handle  70  and transseptal insertion device  10 , may be slid forwards and backwards along axis of transseptal insertion device  10  towards and away from insertion point in patient (typically femoral vein at the groin of patient). Stabilizer base  86  is typically secured to a flat, stable surface, such as a table, or the leg of the patient. Configured as such, stabilizer  80  prevents unwanted vertical, rotational, or other movement of transseptal insertion device  10  and its handle  70 , keeping transseptal insertion device  10  and its handle  70  stable while permitting precise manipulation of handle  70  and its controls. 
     With continuing reference to  FIG. 16 , as shown, proximal end of transseptal insertion device  10  may include a handle  70  for control and manipulation of transseptal insertion device  10  and, particularly, dilator  16  and distal end of dilator  16 . Handle  70  may include a first dial  72  that may be used to turn or deflect distal end of dilator  16 , effectively moving the distal end of dilator  16  up or down in relation to axis of transseptal insertion device  10  (as indicated by arrows in  FIG. 16 ). Handle  70  may also include a second dial  74  for extruding/extending distal end of dilator  16  out of sheath  12  and retracting dilator  16  back into sheath  12 , effectively moving dilator  16  along axis of transseptal insertion device  10  (as indicated by arrows in  FIG. 16 ). Handle  70  may also be rotated, as indicated by rotational arrow in  FIG. 16 , in order to deflect or turn distal end of transseptal insertion device to left or right in relation to axis of transseptal insertion device  10 , increasing or decreasing dilator  16  angle of deflection in that direction. If dial  72  moves distal end of dilator  16  along Y axis, and transseptal insertion device  10  axis is considered the Z axis, so that dial  74  moves dilator  16  along Z axis rotating handle  70  moves distal end of transseptal insertion device  10  (and hence distal end of dilator  16 ) along X axis. Handle  70  includes a port through which dilator  16  and other devices inserted into transseptal insertion device  10  may be inserted. Handle  70  may also include one or more tubes or other ports permitting connection to external hubs and external energy sources, inflation liquids or gas. 
     In embodiments shown herein, balloon  14  and dilator  16  may be used as energy sources in the left atrium and may be used to deliver energy to the pulmonary veins, left atrial appendage, mitral valve and the left ventricle present in the left atrium. Such embodiments may include external energy sources connected to balloon  14  and/or dilator  16  through wires or other conductors extending lumen in sheath  12 . Delivery of energy via balloon  14  or dilator  16  may be thermal/Cryo or radiofrequency, laser or electrical. The delivery of such energy could be through a metallic platform such as a Nitinol cage inside or outside balloon  14 . Transseptal insertion device  10  may also include an energy source external to the proximal end of the sheath and operatively connected to balloon  14  to deliver energy to balloon  14 . 
     With reference now to  FIGS. 17A and 17B  shown is an embodiment of transseptal insertion device  10  enabling differential expansion of balloon  14 . Differential expansion of balloon  14  enables balloon  14  inflation to be adjusted based on the needs of the device operator and the conditions present in the patient&#39;s heart. For example, the size of the fossa ovalis portion of the interatrial septum may dictate the desired size of the inflated balloon  14  needed at the puncture site (interatrial septum if often punctured through the fossa ovalis). Fossae can vary greatly in size. The larger the fossa, the harder it will be to tent the interatrial septum with balloon  14 . Large fossa tend to be saggy and more difficult to manipulate. Hence, with a large fossa, a larger distal end of balloon  14  will make proper tenting of the interatrial septum easier. Indeed, it may be ideal to have balloon  14  inflated uniformly until intersecting or passing through fossa and then differentially expanding distal end  142  of balloon  14  to move fossa out of the way. In  FIG. 17A , distal end or portion  142  of balloon  14  is smaller (less expanded) than proximal end  144  of balloon  14 . 
     Oppositely, the smaller the fossa, the easier it will be to tent the interatrial septum but, there will be less room to maneuver balloon  14  near interatrial septum. Consequently, a smaller distal end of balloon  14  is desired. It also may be beneficial to expand the proximal portion  144  more in order to help fix or secure balloon  14  in place. In  FIG. 17B , distal end or portion of balloon  14  is larger (more expanded) than proximal end or portion of balloon  14 . In both  FIGS. 17A and 17B , dilator  16  has extruded from sheath  12  and past distal end of balloon  14 , tenting interatrial septum  100 , and puncture is imminent. 
     This differential expansion of balloon  14  may be achieved, e.g., by using different materials for different portions of balloon  14  (e.g., a more expandable material for distal end  142  than proximal end or portion  144 , or vice versa). In general, balloon  14  may be made of either compliant or non-compliant material, or a combination thereof. Compliant material will continue expanding as more inflating liquid or gas is added to balloon  14  (at least until failure). Non-compliant material will only inflate up to a set expansion or designated inflation level. Combinations of compliant and non-compliant material may be used to provide a differentially expanding balloon  14 . For example, distal end  142  may be formed from compliant material and proximal end  144  from non-compliant material to enable a larger distal end  142 . Oppositely, proximal end  144  may be formed from compliant material and distal end  142  from non-compliant material to enable a larger proximal end  144 . Other means for providing differential expansion of balloon  14  may be used, such as applying energy to different portions of balloon  14  to increase or decrease the compliance, and expandability, of that portion. 
     Balloon  14  may also be used to direct other equipment into these anatomical locations or be used as an angiographic or hemodynamic monitoring balloon. Differential expansion of balloon  14  may be utilized for proper orientation or direction of such equipment. 
     With reference now to  FIG. 18 , shown is an embodiment of a malleable transseptal needle  90  that may be used with transseptal insertion device  10  with a flexible sheath or otherwise capable of multiple angulations. In embodiments, malleable transseptal needle  90  may be of a variety of diameters and lengths. For example, embodiments may include an eighteen (18) gauge transseptal needle and that is available in 71 cm, 89 cm, and 98 cm lengths. In embodiments, the malleable transseptal needle  90  has different stiffness in a proximal segment  92 , distal segment  94 , and in a middle segment  96  between. For example, malleable transseptal needle  90  may be stiffer in the proximal segment  92  and distal segment  94  and more flexible (less stiff) in a middle segment or mid-section  96 . The mid-section may be the section where transseptal insertion device  10  and dilator  16  angulate. In an embodiment, malleable transseptal needle  90  is used and a control handle provided that enables three-dimensional movements. Malleable transseptal needle  90  shown is, preferably, malleable or flexible at least in part. Proximal end  92  of malleable transseptal needle  90  may be stiff (e.g., made from a stiff material, such as a metal). Mid-section or middle  96  of malleable transseptal needle  90  may be malleable or flexible (e.g., made from a flexible, malleable material, such as rubber). Accordingly, mid-section may flex or bend, enabling malleable transseptal needle  90  to pass through angulated or flexed sheath  12 . 
     Distal end  94  of malleable transseptal needle  90  (i.e., end that punctures interatrial cardiac septum) may be stiff with a cap or electrode at its tip for delivering energy to interatrial septum to puncture interatrial septum. In embodiments, transseptal needle is able to transmit radiofrequency energy to create a controlled septal puncture. Such a transseptal needle may or may not be malleable, but is able deliver RF energy through a cap or crown (e.g., an electrode) at its distal end tip. The needle  90  may be connected, e.g., on proximate end (not shown) to a radiofrequency (RF) energy source (not shown) at, e.g., external hub, that provides RF energy through needle to its distal end tip. In such an embodiment, dilator  16  may tent interaxial septum and RF energy capable transseptal needle may create puncture of interaxial septum through delivery of RF energy. 
     Embodiments may include an additional dilator which would be able to dilate the distal end of sheath  12 , or the entire sheath length, thereby significantly increasing the French size of the sheath  12 . For example, balloons deployed within sheath  12  may be inflated to expand sheath  12 . In such embodiments, transseptal insertion device  10  may, therefore, be used to accommodate and deliver larger devices or be able to retrieve devices once they have been extruded from sheath  12  and have embolized. Such balloons may be inflated through one or more hypotubes. 
     In embodiments, energy, typically electrical energy, may directed through transseptal insertion device  10  may be used to increase or decrease the French size of sheath  12 . In such embodiments, sheath  12  is fabricated from materials that are known to increase in malleability and or expand when certain energies are applied. In this manner, the French size of sheath  12  may be adjusted to a size deemed necessary during a given procedure. Such energy may be applied through wires or conductive material, connected to energy source external to proximal end of transseptal insertion device  10 , attached to or fabricated within sheath  12  or other components of transseptal insertion device  10 . Likewise, parts or portions of transseptal insertion device  10  may be selectively made more rigid or more malleable/soft with the application of energy. Therefore, with the application of differential energy to different parts of transseptal insertion device  10  at different times, transseptal insertion device  10  size may be adjusted to enable various devices that are ordinarily larger and bulkier than the catheter to traverse through the catheter. In embodiments, transseptal insertion device  10  may accommodate devices up to 36 Fr (French size). 
     In an embodiment of transseptal insertion device  10 , visualization of an intrathoracic region of interest using MRI techniques may be provided. Embodiments may, for example, provide a needle system comprising a hollow needle having a distal portion and a proximal portion, said distal portion having a distal-most end sharpened for penetrating a myocardial wall. The needle may include a first conductor, an insulator/dielectric applied to cover the first conductor over the proximal portion of said needle and a second conductor applied to cover the insulator/dielectric. The method may further direct the needle system into proximity to a myocardial wall, track progress of the needle system using active MRI tracking, penetrate the myocardial wall to approach the intrathoracic region of interest, and, use the needle system as an MRI antenna to receive magnetic resonance signals from the intrathoracic region of interest. 
     In related embodiments, MRI antenna may be installed on distal tip  13  of sheath  12 , dilator  16  or on balloon  14 , similar to ultrasound chips or transducers  226  or  326  described above. Wires connecting such MRI antenna or other MRI components may pass through lumen in dilator  16  or sheath  12  and connect with appropriate magnetic resonance energy source on exterior of distal end of transseptal insertion device  10 . 
     Since many modifications, variations, and changes in detail can be made to the described preferred embodiments of the invention, it is intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. Consequently, the scope of the invention should be determined by the appended claims and their legal equivalents.