Patent Publication Number: US-11660137-B2

Title: Connector system for electrosurgical device

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/532,980, filed on Aug. 6, 2019, which is on is a continuation-in-part of U.S. application Ser. No. 14/222,909, filed on Mar. 24, 2014, now U.S. Pat. No. 10,493,259, which is a continuation-in-part of U.S. application Ser. No. 13/468,939, filed on May 10, 2012, now U.S. Pat. No. 8,679,107, which is a divisional application of, and claims priority from, U.S. application Ser. No. 11/905,447, filed on Oct. 1, 2007, now U.S. Pat. No. 8,192,425, which claims the benefit of: U.S. provisional application No. 60/827,452, filed on Sep. 29, 2006, and U.S. provisional application No. 60/884,285, filed on Jan. 10, 2007, all of which are incorporated by reference herein in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to methods and devices usable within the body of a patient to deliver energy to tissue. More specifically, the present invention is concerned with medical devices which use electricity for puncturing tissue. 
     SUMMARY OF THE DISCLOSURE 
     Mechanical force is typically used with a conventional transseptal needles to create a puncture. Under certain circumstances, however, mechanical force is not always effective at puncturing tissue. In such cases a physician may use electrical energy to create a puncture while having sufficient stiffness in the puncture device to provide tactile feedback, i.e. to use an electrosurgical device which is stiff. These requirements could be met by an electrosurgical device comprising an electrically conductive elongate member which is capable of force transmission from a distal portion of the electrosurgical device to a proximal portion of the electrosurgical device to thereby provide tactile feedback to a user, wherein the proximal portion comprises a handle with the handle including an electrical connector which is configured to receive, in a releasable manner, an electrically conductive component operable to be electrically coupled to an energy source. 
     In a first broad aspect, embodiments of the present invention comprise an electrosurgical device configured for use with an energy source, the electrosurgical device comprising: a handle; an electrically conductive elongate member configured for force transmission and having a proximal region and a distal region, a lumen formed therein providing fluid communication between the proximal region and the distal region; the electrically conductive elongate member coupled to and extending inside the handle, wherein the handle is configured to electrically couple the proximal region to the energy source; and an electrically insulating material disposed around the electrically conductive elongate member and extending along a length of the electrically conductive elongate member, wherein a portion of the distal region extends distally from the electrically insulating material and is electrically exposed. In typical embodiments, the handle includes a fluid connector for connecting the lumen to a source of fluid. 
     As a feature of the first broad aspect, the portion of the distal region which extends distally from the electrically insulating material and is electrically exposed includes a distal end of the electrically conductive elongate member which defines an aperture which is in fluid communication with the lumen. In some such embodiments, the distal end of the electrically conductive elongate member is open to thereby define the aperture is forward facing. In some embodiments, the portion of the distal region which extends distally from the electrically insulating material and is electrically exposed defines an electrode for delivering energy to a tissue. In other embodiments, the distal end of the electrically conductive elongate member is shaped in a manner to mechanically puncture tissue. In some embodiments wherein the distal end of the electrically conductive elongate member is shaped in a manner to mechanically puncture tissue, the distal end of the electrically conductive elongate member is bullet-shaped. 
     As a feature of the first broad aspect, in some embodiments the handle comprises an electrical connector to electrically connect the energy source to the electrically conductive elongate member. Some examples of the electrical connector comprise a jack. Some embodiments further comprise an electrical wire within the handle connecting the electrical connector to the electrically conductive elongate member. Typical embodiments include the electrical connector being configured for receiving an electrically conductive component. Some such embodiments include the electrically conductive component electrically coupling a source of energy to the electrical connector. 
     In a second broad aspect, embodiments of the present invention include an electrosurgical device configured for use with an energy source, the electrosurgical device comprising: a handle, a distal portion defining a first lumen that extends longitudinally in the distal portion, the distal portion having a distal end that defines a distal aperture which is in fluid communication with the first lumen, a force transmitting portion extending between the handle and the distal portion, the force transmitting portion defining a second lumen that extends longitudinally in the force transmitting portion and is in fluid communication with the first lumen of the distal portion, wherein the distal portion and force transmitting are electrically conductive and form a continuous electrical conduction path, and wherein the handle is configured to electrically couple the force transmitting portion to the energy source and the distal end of the distal portion which is electrically exposed. 
     In some embodiments of the second broad aspect, the handle includes a fluid connector for connecting to a source of fluid. In some embodiments, the electrosurgical device includes an electrical insulation extending proximally from a distal tip of the distal portion such that the distal tip is electrically exposed. Some embodiments comprise a distal tip of the electrosurgical device being substantially bullet-shaped. In some embodiments of the second broad aspect, the handle includes an electrical connector for receiving an electrically conductive component. In some such embodiments, the electrical connector comprises a jack for receiving the electrically conductive component. 
     In a third broad aspect, embodiments of the present invention are for a method of using an electrosurgical device configured for use with an energy source, the electrosurgical device comprising: a handle having an electrical connector; an electrically conductive elongate member configured for force transmission and having a proximal region and a distal region, a lumen formed therein providing fluid communication between the proximal region and the distal region; the electrically conductive elongate member coupled to and extending inside the handle, wherein the handle is configured to electrically couple the proximal region to the energy source; an electrically insulating material disposed around the electrically conductive elongate member and extending along a length of the electrically conductive elongate member, wherein a portion of the distal region extends distally from the electrically insulating material and is electrically exposed to define an electrode; and the method comprising the steps of (1) connecting an electrically conductive component, which is in electrical communication with a source of energy, to the electrical connector of the handle, and (2) delivering electrical energy through the electrode to a tissue. Typical embodiments of the method further comprise a step (3) of disconnecting the electrically conductive component from the electrical connector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the invention may be readily understood, embodiments of the invention are illustrated by way of examples in the accompanying drawings. 
         FIG.  1    illustrates a perspective view of a medical device in accordance with an embodiment of the present invention; 
         FIGS.  2 A to  2 D  illustrate partial perspective views of distal regions of embodiments of medical devices; 
         FIG.  2 E  illustrates a cross-sectional view of a distal region of an embodiment of a medical device; 
         FIGS.  3 A to  3 D  illustrate perspective views of various electrode configurations; 
         FIGS.  4 A and  4 B  illustrate a partially cut-away side view and an end view, respectively, of a medical device and a tubular member in accordance with an embodiment of the present invention; 
         FIGS.  5 A and  5 B  illustrate a partially cut-away side view and an end view, respectively, of a medical device and a tubular member in accordance with another embodiment of the present invention; 
         FIGS.  5 C and  5 D  illustrate end views of a medical device and a tubular member in accordance with alternative embodiments of the present invention; 
         FIGS.  6 A and  6 B  illustrate a partially cut-away side view and an end view, respectively, of a tubular member in accordance with another embodiment of the present invention; 
         FIGS.  7 A and  7 B  illustrate a partially cut-away side view and an end view, respectively, of a medical device and a tubular member in accordance with another embodiment of the present invention; 
         FIG.  8    illustrates a perspective view of a system including a medical device in accordance with the present invention; 
         FIGS.  9 A and  9 B  illustrate partially cut-away views of a method using an apparatus in accordance with an embodiment of the present invention; 
         FIG.  10 A  illustrates a perspective view of an elongate member portion of the medical device shown in  FIG.  1   ; 
         FIG.  10 B  illustrates a partial perspective view of an alternative elongate member usable in the medical device shown in  FIG.  1   ; 
         FIG.  10 C  illustrates a partial perspective view of another alternative elongate member usable in the medical device shown in  FIG.  1   ; 
         FIG.  10 D  illustrates a partial perspective view of yet another alternative elongate member usable in the medical device shown in  FIG.  1   ; 
         FIG.  11 A  illustrates a perspective view of a medical device in accordance with an yet another alternative embodiment of the present invention, the medical device including a curved section; 
         FIG.  11 B  illustrates a partial perspective view of a medical device in accordance with yet another alternative embodiment of the present invention, the medical device including an alternative curved section; 
         FIG.  11 C  illustrates a partial perspective view of a medical device in accordance with yet another alternative embodiment of the present invention, the medical device including another alternative curved section; 
         FIG.  12 A  illustrates a top elevation view of an embodiment of a hub; and 
         FIG.  12 B  illustrates a side cross-sectional view taken along the line  5 B- 5 B of  FIG.  12 A . 
     
    
    
     DETAILED DESCRIPTION 
     Devices used for puncturing tissue, such as the septal tissue of a patient&#39;s heart, are typically either mechanical or electrosurgical in nature. Usually, such devices are inserted into a patient&#39;s body through tubular devices such as dilators or sheaths. Mechanical force is normally used with a conventional Brockenbrough transseptal needle to create a puncture. A Brockenbrough needle has a sharp beveled tip and a forward-facing aperture that may be used for injecting fluid or monitoring pressure. Under certain circumstances, however, mechanical force is not always effective at puncturing tissue. In such cases, physicians have proposed using an electrocautery generator or the like to electrify the mechanical needle and thereby produce an ad hoc electrosurgical device with a forward facing aperture. One drawback to electrifying a non-insulated Brockenbrough needle is a risk of burns to the patient and physician. While a dilator or sheath provides some insulation for the part of the non-insulated Brockenbrough needle contained therein, there is still potential for burns to the patient and physician by sections of the needle outside of the dilator or sheath. Also, any fluids (e.g. blood, cooling water) inside of the dilator or sheath will be exposed to electricity such that the fluid may conduct electricity to outside of the dilator or sheath. Furthermore, there is a risk of tissue coring. A core (or plug) of tissue is typically cut from the tissue inside the ring-shaped distal tip of the needle upon delivery of energy. This tissue core is subsequently captured in the lumen of the electrosurgical device upon advancement of the needle through tissue. The tissue core may be released from the lumen, potentially leading to emboli and increasing the risk of a stroke or other ischemic event. 
     The present inventors have conceived of, and reduced to practice embodiments of an electrosurgical device configured for force transmission from a distal portion of the electrosurgical device to a proximal portion of the electrosurgical device to thereby provide tactile feedback to a user. The proximal portion of the device comprises a handle and/or a hub, with the handle (or hub) including an electrical connector which is configured to receive, in a releasable manner, an electrically conductive component which is operable to be in electrical communication with an energy source to allow the physician or other user to puncture a tissue layer, such as a septum. In some cases, a radiofrequency (RF) energy source is used to selectively apply RF energy to tissue. Typical embodiments of the device include insulation to protect the user and the patient, and are configured to avoid creating emboli. Some embodiments comprise a transseptal puncturing device having an electrically conductive elongate member and an electrode at a distal end of the electrically conductive elongate member for delivering energy to tissue, with the transseptal puncturing device further including an electrical connector configured to releasably receive, the electrically conductive component which is electrically coupled to an energy source. 
     With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the present invention only. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention. The description taken with the drawings will make apparent to those skilled in the art how the several aspects of the invention may be embodied in practice. 
     Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
     As used herein, the terms ‘proximal’ and ‘distal’ are defined with respect to the user. That is, the term ‘proximal’ refers to a part or portion closer to the user, and the term ‘distal’ refers to a part or portion further away from the user when the device is in use. Also, it should be noted that while, for clarity of explanation, the term tubular or tubular member is used to describe the members that enclose the disclosed medical devices, the term tubular member is intended to describe both circular and non-circular embodiments of the enclosing member. The term tubular member is used in this disclosure to describe dilators, sheaths, and other members that define a lumen for containing a medical device. 
     Referring to  FIG.  1   , there is shown a medical device  100  in accordance with an embodiment of the present invention. The medical device  100  is usable for creating a channel at a target location in a body of a patient. The medical device  100  includes a handle  110 , a distal portion  112  and a force transmitting portion  114  extending between the distal portion  112  and the handle  110 . The distal portion  112  defines a distal portion length, and includes an electrode  106  and an electrical insulation  104  extending proximally from the electrode  106 . 
     The force transmitting portion  114  defines a force transmitting portion length, the force transmitting portion length being larger than the distal portion length. In some embodiments of the invention, the force transmitting portion  114  has a force transmitting portion flexural rigidity of at least about 0.016 Nm2, for example about 0.017 Nm2. The force transmitting portion  114  has a force transmitting portion flexural rigidity allowing the transmission to the handle  110  of contact forces exerted on the distal portion  112  when the distal portion  112  contacts the target location to provide tactile feedback to the intended user. In addition, the force transmitting portion flexural rigidity allows for the transmission of force from the handle  110  to the distal portion  112  in order to, for example, advance the distal portion  112  within the body of the patient or to orient the distal portion  112  by applying torque to the handle  110 . 
     Therefore, the proposed medical device  100  is structured such that it provides the intended user with a similar, or better, ‘feel’ as some prior art devices. That is, although the structure and function of the medical device  100  differs significantly from prior art devices. 
     In some embodiments of the invention, the distal portion  112  has a distal portion flexural rigidity of at least about 0.0019 Nm2, for example 0.0021 Nm2. Such values of flexural rigidity enhance the cognitive ergonomics of the proposed medical device  100  by providing tactile feedback to the intended user and allowing for the transmission of radial (torque) and longitudinal forces from the handle to the distal portion. 
     In typical embodiments of the invention, the medical device  100  includes an electrically conductive elongate member  102  having an electrical insulation  104  disposed thereon. The electrical insulation  104  substantially covers the entire outer surface of the elongate member  102  such that elongate member  102  is able to deliver energy from its proximal region to the electrode  106  at its distal region, without substantial leakage of energy along the length of the elongate member  102 . The elongate member  102  defines a lumen  208  and at least one side-port  600  (shown, for example, in  FIGS.  2 A to  2 D ), which is in fluid communication with the lumen  208 . 
     The one or more side-ports  600  are particularly useful in typical embodiments of medical device  100  wherein a lumen  208  of the elongate member  102  is not open to the surrounding environment via the distal end of the medical device  100  (i.e. wherein medical device  100  is a close-ended device), for example, in the embodiments of  FIGS.  2 A to  2 E . In such embodiments, the lumen extends substantially longitudinally through the force transmitting portion  114  ( FIG.  1   ), and through a section of the distal portion  112 , and terminates in the distal portion  112  at a location substantially spaced apart from the distal tip  403 , such that the distal tip  403  remains closed. 
     In embodiments comprising side-port(s)  600 , the side-port(s)  600  allow for fluids to be injected into the surrounding environment from the lumen  208 , and/or allow for pressure to be measured by providing a pressure transmitting lumen through medical device  100 . In some examples, the side-port(s)  600  are formed radially through elongate member  102  and electrical insulation  104 , thereby allowing for fluid communication between the surrounding environment and the lumen  208 . In alternative embodiments, a side-port  600  is formed radially through a portion of the electrode  106 . 
     The size and shape of the side-port(s)  600  may vary depending on the intended application of the medical device  100 , and the invention is not limited in this regard. For example, in one embodiment, the side-port(s)  600  is between about 0.25 mm and about 0.45 mm in diameter. Some embodiments include side-ports of more than one size. In addition, the number of side-ports  600  may vary, and they may be located anywhere along the medical device  100  that does not interfere with the functioning of the device. For example, as shown in  FIG.  2 A , the medical device  100  includes two side-ports  600  located about 1 cm from the distal end of the elongate member  102 , at substantially the same longitudinal position along the elongate member  102 . In another embodiment, as shown in  FIG.  2 B , the medical device  100  includes about 3 side-ports located at the same circumferential position and spaced longitudinally at about 1.0 cm, 1.5 cm, and 2.0 cm from the distal end of the elongate member  102 . In another embodiment, as shown in  FIG.  2 C , the side-ports  600  are staggered, such that they are spaced apart both circumferentially as well as longitudinally. In a further embodiment, as shown in  FIG.  2 D , the side-ports  600  are located on the electrode  106 . In some embodiments, the side-port(s)  600  have a smooth or rounded wall, which serves to minimize or reduce trauma to bodily tissue. For example, some such embodiments comprise one or more side-port(s)  600  with a smooth outer circumferential edge created by sanding the circumferential edges to a smooth finish or, for example, by coating the edges with a lubricious material. 
     When a medical device that relies on side-ports to provide fluid communication between its lumen and the surrounding environment is inside a lumen of a close fitting member, the side-ports may be partially or completely occluded or blocked. The embodiments of  FIGS.  4  to  9    relate to an apparatus that provides an effective conduit from the lumen of medical device to the environment outside of the device, and methods of using such apparatus. 
       FIGS.  4 A and  4 B  illustrate a partially cut-away side view and an end view, respectively, of a distal portion  112  of medical device  100  positioned within tubular member  800 . As described in more detail herein below, some embodiments of medical device  100  are comprised of a single piece elongate member  102  (as shown in  FIG.  1    and  FIG.  10 A ) and some other embodiments of medical device  100  are comprised of two elongate members, main member  210  and end member  212 , which are joined together (as shown in  FIGS.  10 D and  2 E ). Depending on the embodiment of medical device  100  being considered, distal portion  112  may be the distal portion of a single piece elongate member  102 , the distal portion of an end member  212 , or the distal portion of some other embodiment of medical device  100 . In  FIGS.  4  to  9   , the lumen defined by distal portion  112  may be either lumen  208  of elongate member  102  or end member lumen  216 . For descriptive purposes, the lumen defined by distal portion  112  in  FIGS.  4  to  9    is referred to as device lumen  809 . 
     Tubular member  800  may comprise a dilator, a sheath, or some other member defining a lumen configured to receive a medical device  100 . 
     Referring to  FIGS.  4 A and  4 B , illustrated features of an embodiment of distal portion  112  of medical device  100  include a change in diameter  831 , a distal portion  830 , device lumen  809  defined by a body of the medical device  100 , a side-port  600  in fluid communication with the lumen, and a closed distal end. Distal portion  830  has an outer diameter less than the outer diameter of distal portion  112  proximal of the change in diameter  831 , i.e., distal portion  830  has a reduced diameter. In the embodiment of  FIG.  4 A , distal tip  403  of the medical device comprises a distal electrode  106 . Some alternative embodiments of medical device  100  do not include an electrode. Tubular member  800  defines tubular member lumen  802 . Tubular member  800  and distal portion  830  of medical device  100 , in combination, define conduit  808  whereby medical device  100  is able to provide sufficient fluid flow for delivering contrast fluid to stain tissue. Fluid (e.g. blood) may also be withdrawn through the path defined by conduit  808 , side-port  600 , and device lumen  809 . In the example of  FIG.  4 A , conduit  808  includes the space between tubular member  800  and reduced diameter distal portion  830 , and the portion of tubular member lumen  802  distal of medical device  100 . 
     In the embodiment of  FIG.  4 A , distal portion  830  is distal of change in diameter  831  and includes insulated part  834  and electrode  106 . Constant diameter part  836  is distal of change in diameter  831  and includes insulated part  834  and the straight longitudinal part of electrode  106  that has a constant diameter (i.e. the portion of electrode proximal of the dome shaped electrode tip). Constant diameter part  836  of distal portion  830  does not taper and may be described as having a substantially constant diameter longitudinally. There is a minor change in outer diameter at the distal end of electrical insulation  104 , but with regards to fluid flow, it can be considered negligible. 
     In the embodiment of  FIG.  4 A , a small space or gap  832  exists between the tubular member  800  and the part of distal portion  112  proximal of the change in diameter  831 . It is common for embodiments of medical device  100  and tubular member  800  to have a small gap  832  between the outer diameter of medical device and the inner diameter of tubular member. Completely eliminating the gap would result in increased friction between the medical device and tubular member and could result in difficulty advancing medical device  100  through tubular member  800 . In typical embodiments, the gap is small enough that it prevents a substantial flow of fluids such as contrast fluids, which are typically 3 to 5 times more viscous than water. 
     In the embodiment of  FIG.  4 A , side-port  600  is close to the change in diameter  831  whereby the larger diameter part of distal portion  112  functions as a brace to keep tubular member  800  from blocking side-port  600 .  FIG.  4 A  illustrates an abrupt change in diameter. Alternative embodiments have a less abrupt change in diameter. Typical embodiments of medical device  100  include a second side-port, with the two side-ports being opposite to each other. Some alternative embodiments include more than two side-ports. Other alternative embodiments have one side-port. In some alternative embodiments of medical device  100 , side-port  600  is longitudinally elongated, i.e., capsule-shaped. 
     The side-port(s)  600  and the device lumen  809  together provide a pressure transmitting lumen. The pressure transmitting lumen is operable to be coupled to a pressure transducer, for example, external pressure transducer  708  (to be described with respect to  FIG.  8   ). 
     Distal tip  403  of medical device  100  is shown in the example of  FIG.  4 A  as being slightly proximal of the distal end of tubular member  800 . In this position, fluid communication between the medical device lumen and the surrounding environment may be established. Fluid communication may also be established when distal tip  403  is positioned further proximal of the distal end of tubular member  800 , when distal tip  403  is aligned with the distal end of tubular member  800 , and when distal tip  403  is positioned distal of the distal end of tubular member  800 . If distal tip  403  is positioned such that side-port  600  is distal of the distal end of tubular member  800 , it is still possible to deliver fluid in a radial direction. 
     Typical embodiments of medical device  100  comprise a conductive member (elongate member  102 , or main member  210  joined to end member  212 ), which is typically comprised of a metallic material. The conductive member is in electrical communication with distal electrode  106 , and a layer of insulation (electrical insulation  104 ) covers the metallic material. In other words, the elongate member  102  comprises an electrically conductive material, and a layer of insulation covers the electrically conductive material, the electrically conductive material being electrically coupled to the electrode  106 . For some single piece embodiments, elongate member  102  has an on outer diameter proximal of change in diameter  831  of about 0.7 mm to about 0.8 mm at distal end  206 , and an outer diameter for reduced diameter distal portion  830  of about 0.4 mm to about 0.62 mm. For some two piece embodiments, end member  212  has an outer diameter proximal of change in diameter  831  of about 0.40 mm to about 0.80 mm, and an outer diameter for distal portion  830  of about 0.22 mm to about 0.62 mm. The above described embodiments are typically used with a tubular member defining a corresponding lumen about 0.01 mm (0.0005 inches) to about 0.04 mm (0.0015 inches) larger than the outer diameter of medical device  100  proximal of change in diameter  831 . 
       FIG.  4 B  illustrates an end view of the apparatus of  FIG.  4 A . The figure includes, from inside to outside (in solid line), electrode  106 , electrical insulation  104 , the part of distal portion  112  proximal of change in diameter  831 , gap  832 , tubular member distal end  801 , and tubular member  800 . Hidden features shown in broken line include side-port  600  and device lumen  809 . 
     In the embodiment of  FIGS.  4 A and  4 B , distal tip  403  of the medical device is comprised of electrode  106  which defines a substantially circular cross-section and a circular end-profile. Similar to the embodiments of  FIGS.  3 A and  3 B , electrode  106  of  FIG.  4 B  is at the end of elongate member  102  (or end member  212 ) and has the same outer diameter as the distal end of the conductive member. Since constant diameter part  836  of reduced diameter distal portion  830  does not substantially taper (the small change in diameter at the distal end of electrical insulation  104  is not taken to be substantial), electrode  106  has a diameter which is substantially equal to the diameter of the part of distal portion  830  which is proximal of electrode  106  (i.e. substantially equal to the diameter of insulated part  834 ). 
     Making reference again to  FIGS.  1  to  4   , some embodiments of medical device  100  comprise an elongate member  102  having a closed distal end, with the elongate member defining a device lumen  809  and at least one side-port  600  in fluid communication with the device lumen. The elongate member also defines a proximal portion and a distal portion  830 , the distal portion extending from the at least one side-port  600  to the distal end of the elongate member. The proximal portion defines a first outer diameter and the distal portion defines a second outer diameter, with the first outer diameter being larger than the second outer diameter, and the second outer diameter being substantially constant. The distal tip of medical device  100  comprises an electrode  106 . The diameter of the electrode is substantially equal to the second outer diameter. 
     Some embodiments of electrode  106  typically create a puncture in tissue with a diameter 10 to 20 percent larger than the electrode. Such a puncture diameter is typically large enough to facilitate passage of the part of medical device proximal of change of diameter  831  (i.e. the larger diameter portion of medical device) through the tissue puncture, and to start advancing a dilator over medical device  100  and through the tissue. 
       FIGS.  5 A to  5 D  illustrate embodiments of medical device  100  wherein distal portion  830  has a non-circular cross section. In  FIGS.  5 A and  5 B , distal portion  830  (including electrode  106  and insulated part  834  ( FIG.  4   a   )) defines a substantially flat outer surface portion. The body of medical device  100  defines device lumen  809  (shown in broken line in  FIG.  5 B ), and side-port  600  in fluid communication with the lumen. Reduced outer diameter distal portion  830  of the body extends between side-port  600  and distal tip  403  of the medical device whereby the outer surface of medical device  100 , in combination with tubular member  800  can provide a conduit  808 . While  FIG.  5 A  illustrates a portion of reduced outer diameter distal portion  830  extending proximally from side-port  600  to change in diameter  831 , some alternative embodiments do not include this portion, i.e., change in diameter  831  is adjacent side-port  600 . 
     The embodiment of conduit  808  in  FIG.  5 B  is shown as having an end-view shape of a portion of circle. The reduced outer diameter is substantially constant longitudinally along distal portion  830 , with the exceptions of the distal end of electrical insulation  104  and the hemispherical-shaped distal tip of electrode  106 . A cross-section of the electrode  106  is substantially identical to a cross-section of the part of the distal portion  830  which is proximal of the electrode. 
       FIG.  5 C  illustrates an alternative embodiment with two flat outer surfaces and two corresponding side-ports.  FIG.  5 D  illustrates another alternative embodiment with three flat outer surfaces and three corresponding side-ports. Further alternative embodiments are similar to the embodiments of  FIGS.  5 B,  5 C and  5 D , except instead of the flat outer surfaces, the devices have corresponding outer surfaces that are convexly curved to provide a larger device lumen  809 . 
       FIGS.  6 A and  6 B  illustrate an embodiment of a tubular member  800  for use with a medical device  100  having a side-port  600 . The body of tubular member  800  defines a lumen such that tubular member proximal region  803   a  has a first inner diameter d 1 , and tubular member distal region  803   b  has at least a portion of it defining a second inner diameter d 2 , wherein the second inner diameter d 2  is greater than the first inner diameter d 1 , and wherein the tubular member distal region  803   b  extends to the tubular member distal end  801 . 
     The embodiment of  FIG.  6 B  includes the tubular member distal region  803   b  (i.e. the increased diameter portion with the second inner diameter d 2 ) extending circumferentially over less than 360 degrees of the circumference of the tubular member. Tubular member inner surface  804  defines a tubular member channel  805  which, in the example of  FIG.  6 B , extends circumferentially approximately 90 degrees. In some alternative embodiments, tubular member distal region  803   b  extends 360 degrees of the circumference of the tubular body. 
     The embodiment of  FIGS.  6 A and  6 B  includes tubular member proximal marker  816  at the proximal end of the distal region, and tubular member distal marker  818  at the distal end of tubular member distal region  803   b . Alternative embodiments have only one of the distal region markers or neither distal region marker. The embodiment of  FIGS.  6 A and  6 B  also includes a side marker  819 , which is operable to be used as an orientation marker for aligning the tubular member distal region  803   b  (i.e. the increased diameter portion) with the side-port  600  of a medical device  100  positioned inside the tubular member. 
     One embodiment is a dilator comprising a tubular member defining a lumen in fluid communication with a distal end aperture, a proximal region having a first inner diameter, and a distal region having an increased diameter portion. The increased diameter portion extends proximally from a distal end of the dilator and defines a substantially longitudinally constant second inner diameter that is greater than the first inner diameter. 
     The embodiment of  FIGS.  7 A and  7 B  is a kit comprising a tubular member  800  and a medical device  100 , operable to be combined to form an apparatus. Tubular member  800  defines a tubular member lumen  802  for receiving medical device  100 . Medical device  100  defines a device lumen  809  in fluid communication with a side-port  600 , and comprises a medical device proximal region  838  proximal of the side-port, and a medical device distal region  839  distal of the side-port. Medical device  100  and tubular member  800  are configured for cooperatively forming a conduit  808  between an outer surface of medical device distal region  839  and an inner surface of tubular member  800 . In the example of  FIG.  7 A , conduit  808  is formed both proximal and distal of side-port  600 , while in alternative embodiments it is only formed distal of the side-port. In typical use, conduit  808  is formed at least between the side-port and a distal end of the tubular member when medical device  100  is inserted and positioned within tubular member lumen  802 . 
     The apparatus of  FIG.  7 A  includes both a tubular member channel  805  and a medical device channel  807 . Conduit  808  is comprised of both tubular member channel  805  and a medical device channel  807 . In typical embodiments, at least some of the length of conduit  808  has a constant cross-sectional configuration, which reduces turbulence and facilitates laminar flow, which in turn facilitates forwards injection of a fluid. Some alternative embodiments include a tubular member channel  805  but not a medical device channel  807 , and some other alternative embodiments include a medical device channel  807  but not a tubular member channel  805 . 
     Some embodiments of the medical device and the tubular member further comprise corresponding markers for aligning the side-port of the medical device within the tubular member lumen to form said conduit. In the example of  FIG.  7   , medical device  100  includes medical device proximal marker  810  and medical device distal marker  812 , while tubular member  800  includes side marker  819 . In some embodiments of the kit, the corresponding markers are configured for longitudinally aligning the side-port within the tubular member lumen. In the example of  FIG.  7   , side-port  600 , which is equidistant between medical device proximal marker  810  and medical device distal marker  812 , can be longitudinally aligned with side marker  819  by positioning side marker  819  between medical device proximal marker  810  and medical device distal marker  812 . 
     In some embodiments of the kit, the corresponding markers are configured for rotationally aligning the side-port within the tubular member lumen. In the example of  FIG.  7   , side-port  600  can be rotationally aligned with side marker  819  of tubular member  800  by comparing the relatively larger diameter medical device proximal marker  810  with the smaller diameter medical device distal marker  812 , which thereby aligns side-port  600  with tubular member channel  805 . Alternative embodiments of medical device  100  include a side-marker on the same side as side-port  600 , or on the side opposite to the side-port, to facilitate rotational positioning. Further details regarding markers are found in U.S. Pat. No. 4,774,949, issued Oct. 4, 1988 to Fogarty, incorporated by reference herein in its entirety. 
     An embodiment of a kit comprises a tubular member defining a tubular member lumen in fluid communication with a distal end aperture, and a medical device having a closed distal end. The medical device comprises a device lumen in fluid communication with at least one side-port, and a distal portion extending from the at least one side-port to a distal end of the medical device. Medical device and tubular member are configured to cooperatively form a conduit between an outer surface of the distal portion and an inner surface of the tubular member when the medical device is inserted within the tubular member lumen. The conduit extends at least between the side-port and the distal end aperture for enabling fluid communication between the side-port and an environment external to the distal end aperture. 
     In a specific embodiment of a kit, end member  212  has an on outer diameter proximal of change in diameter  831  of about 0.032 inches (about 0.81 mm), and an outer diameter at reduced diameter distal portion  830  of about 0.020 inches (about 0.51 mm) to about 0.025 inches (about 0.64 mm). End member  212  is used with a tubular member defining a lumen about 0.0325 inches (0.82 mm) to about 0.0335 inches (0.85 mm). 
     Referring to  FIG.  8   , systems for use with the medical device  100  typically comprise a generator  700  and, in some embodiments, a grounding pad  702 , external tubing  706 , a pressure transducer  708 , and/or a source of fluid  712 . 
     Referring to  FIG.  8   , as mentioned herein above, in order to measure pressure at the distal region  202  ( FIG.  10   ) of the medical device  100 , an external pressure transducer may be coupled to the medical device  100 . In the example of  FIG.  8   , an adapter  705  is operatively coupled to the external tubing  706 , which is operatively coupled to an external pressure transducer  708 . The adapter  705  is structured to couple to adapter  704  when in use. In some examples, adapters  704  and  705  comprise male and female Luer locks or other fluid connectors, adapted to readily couple and decouple to/from each other. In use, tubing  706  and  508  may be flushed with saline or another suitable fluid to remove air bubbles prior to measuring pressure. When medical device  100  is positioned in a vessel, conduit, or cavity of a body, fluid adjacent the distal region  202  ( FIG.  10   ) exerts pressure through the side-port(s)  600  on fluid within the lumen  208 , which in turn exerts pressure on fluid in tubing  508  and  706 , which further exerts pressure on external pressure transducer  708 . The side-port(s)  600  and the lumen  208  thus provide a pressure sensor in the form of a pressure transmitting lumen for coupling to a pressure transducer. 
     The external pressure transducer  708  produces a signal that varies as a function of the pressure it senses. The external pressure transducer  708  is electrically coupled to a pressure monitoring system  710  that is operative to convert the signal provided by the transducer  708  and display, for example, a pressure contour as a function of time. Thus, pressure is optionally measured and/or recorded and, in accordance with one embodiment of a method aspect as described further herein below, used to determine a position of the distal region  202 . In those embodiments of the medical device  100  that do not comprise a lumen in fluid communication with the outside environment, a pressure transducer may be mounted at or proximate to the distal portion  112  of the medical device  100  and coupled to a pressure monitoring system, for example, via an electrical connection. 
     As previously mentioned, for some embodiments the medical device  100  is operatively coupled to a source of fluid  712  for delivering various fluids to the medical device  100  and thereby to a surrounding environment. The source of fluid  712  may be, for example, an IV bag or a syringe. The source of fluid  712  may be operatively coupled to the lumen  208  via the tubing  508  and the adapter  704 , as mentioned herein above. Alternatively, or in addition, some embodiments include the medical device  100  being operatively coupled to an aspiration device for removing material from the patient&#39;s body through one or more of the side-ports  600 . 
     In one broad aspect, the medical apparatus is used in a method of establishing a conduit for fluid communication for a medical device  100 , the medical device defining a device lumen  809  in fluid communication with a side-port  600 . Making reference to  FIGS.  4  to  9   , the method comprises the steps of (a) inserting a medical device  100  having at least one side-port  600  into a tubular member  800 , and (b) cooperatively defining a conduit  808  for fluid communication by positioning the side-port  600  of the medical device  100  at a location of the tubular member  800  where a space exists between the side-port  600  and a tubular member inner surface  804 , the space extending at least between the side-port  600  and a distal end of the tubular member. 
     In some embodiments of the broad aspect, the medical device comprises a medical device proximal marker  810  proximal of the side-port, and a medical device distal marker  812  distal of the side-port, and step (b) includes visualizing at least one of the proximal marker and the distal marker to position the medical device. In some such embodiments, step (b) comprises positioning side-port  600  within tubular member lumen  802 , for example, by using a medical device proximal marker  810  and a medical device distal marker  812 . In such embodiments of the method, it is not necessary for distal tip  403  to be inside of tubular member lumen  802 . In some embodiments of the method, the medical device further comprises a side-port marker wherein the side-port marker and the side-port are equidistant from a tip of the medical device, and wherein step (b) includes visualizing the side-port marker to position the medical device. In some other embodiments, step (b) comprises positioning distal portion  830  of distal portion  112  within tubular member lumen  802 , which inherently positions the side-port in the tubular member lumen. In some embodiments of the method, step (b) includes aligning a distal tip  403  of the medical device with the tubular member distal end  801 . 
     Some embodiments of the broad aspect further comprise a step (c) of delivering fluid through the side-port  600 , wherein the fluid is a contrast fluid  814  and wherein step (c) includes delivering the contrast fluid distally through the distal end of the tubular member. Some such embodiments further comprise a step of delivering electrical energy to puncture tissue before the contrast fluid is delivered. Some embodiments comprise a step (d) of delivering electrical energy through the medical device to create a puncture through a tissue after the contrast fluid is delivered. 
     In some embodiments, the tissue comprises a septum of a heart, and step (c) comprises staining the septum by delivering contrast fluid through the side-port. 
     In some embodiments of the broad aspect, the side-port  600  and the device lumen  809  together comprise a pressure transmitting lumen, and the method further comprises a step (c) of measuring a pressure of an environment external to the distal end using the side-port and the conduit. Some such embodiments further comprise a step (d) of delivering fluid through the side-port. 
     Some embodiments of the broad aspect further comprise a step (c) of withdrawing fluid through the side-port  600 . In some such embodiments, the fluid is blood. 
     In one example of a method of use, illustrated in  FIGS.  9 A and  9 B , a target site comprises the atrial septum  822 , a tissue within the heart of a patient. In this example, the target site is accessed via the inferior vena cava (IVC), for example, through the femoral vein. The medical device  100  of  FIGS.  9 A and  9 B  is similar to medical device of  FIG.  4 A , except the embodiment of  FIG.  9    has a medical device proximal marker  810  and a medical device distal marker  812 . 
     The example of the method includes a user advancing sheath  820  and a dilator (i.e. tubular member  800 ) through inferior vena cava  824 , and introducing the sheath and tubular member  800  into the right atrium  826  of the heart. An electrosurgical device, for example medical device  100  described herein above, is then introduced into tubular member lumen  802 , and advanced toward the heart. In typical embodiments of the method, these steps are performed with the aid of fluoroscopic imaging. 
     After inserting medical device  100  into tubular member  800 , the user positions the distal end of tubular member  800  against the atrial septum  822  ( FIG.  9 A ). Some embodiments of tubular member  800  include markers ( FIG.  6 A ). The medical device is then positioned such that electrode  106  is aligned with or slightly proximal of the distal end of tubular member  800  ( FIG.  9 A  insert). Medical device proximal marker  810  and medical device distal marker  812  facilitate positioning medical device  100 . Tubular member  800  is typically positioned against the fossa ovalis of the atrial septum  822 . Referring to the  FIG.  9 A  insert, the inner surface of tubular member  800  and the outer surface of medical device  100  define conduit  808  from side-port  600  to the distal end of tubular member lumen  802 , which is sealed by atrial septum  822 . 
     Once medical device  100  and tubular member  800  have been positioned, additional steps can be performed, including taking a pressure measurement and/or delivering material to the target site, for example, a contrast agent, through side-port(s)  600 . The  FIG.  9 A  insert illustrates contrast fluid  814  flowing from side-port  600 , through conduit  808 , and ending at atrial septum  822 , whereby the tissue is stained by the contrast fluid. In alternative examples, electrode  106  is positioned against atrial septum  822  when contrast fluid  814  is delivered. Such steps facilitate the localization of the electrode  106  at the desired target site. 
     Starting from the position illustrated by the  FIG.  9 A  insert, medical device  100  is advanced until electrode  106  contacts atrial septum  822 . (Alternative embodiments wherein electrode  106  is positioned against atrial septum  822  when contrast fluid  814  is delivered do not require this repositioning.) With the medical device  100  and the dilator (i.e. tubular member  800 ) positioned at the target site, energy is delivered from an energy source, through medical device  100 , to the target site. The path of energy delivery is through elongate member  102  (or main member  210  and end member  212 ), to the electrode  106 , and into the tissue at the target site. The example of  FIG.  9 A  includes delivering energy to vaporize cells in the vicinity of the electrode, thereby creating a void or puncture through the tissue at the target site, and advancing distal portion  112  of the medical device  100  at least partially through the puncture. When the distal portion  112  has passed through the target tissue and reached the left atrium ( FIG.  9 B ), energy delivery is stopped. The side-ports of medical device  100  are uncovered ( FIG.  9 B  insert), whereby contrast may be delivered to confirm the position of distal portion  112  in the left atrium of the heart. The diameter of the puncture created by the delivery of energy is typically large enough to facilitate advancing distal portion  112  of the medical device  100  therethrough and to start advancing a dilator (i.e. tubular member  800 ). 
     Referring now to  FIG.  10 A , the elongate member  102  includes a proximal region  200 , a distal region  202 , a proximal end  204 , and a distal end  206 . In some embodiments of the invention, the elongate member  102  defines a lumen  208 , which typically extends substantially between the proximal region  200  and the distal region  202 . 
     The elongate member  102  is typically sized such that the handle  110  remains outside of the patient when the distal end  206  is within the body, for example, adjacent the target site. That is, the proximal end  204  is at a location outside of the body, while the distal end  206  is located within the heart of the patient. Thus, in some embodiments of the invention, the length of the elongate member  102 , i.e., the sum of the force transmitting length and the distal portion length, is between about 30 cm and about 100 cm, depending, for example, on the specific application and/or target site. 
     The transverse cross-sectional shape of the elongate member  102  may take any suitable configuration, and the invention is not limited in this regard. For example, the transverse cross-sectional shape of the elongate member  102  is substantially circular, ovoid, oblong, or polygonal, among other possibilities. Furthermore, in some embodiments, the cross-sectional shape varies along the length of the elongate member  102 . For example, in one embodiment, the cross-sectional shape of the proximal region  200  is substantially circular, while the cross-sectional shape of the distal region  202  is substantially ovoid. 
     In typical embodiments, the outer diameter of the elongate member  102  is sized such that it fits within vessels of the patient&#39;s body. For example, in some embodiments, the outer diameter of the elongate member  102  is between about 0.40 mm and about 1.5 mm (i.e. between about 27 Gauge and about 17 Gauge). In some embodiments, the outer diameter of the elongate member  102  varies along the length of the elongate member  102 . For example, in some embodiments, the outer diameter of the elongate member  102  tapers from the proximal end  204  towards the distal end  206 . In one specific embodiment, the outer diameter of the proximal region  200  of the elongate member  102  is about 1.5 mm. In this embodiment, at a point about 4 cm from the distal end  206 , the outer diameter begins to decrease such that the distal end  206  of the elongate member  102  is about 0.7 mm in outer diameter. In a further embodiment, the outer diameter of the elongate member  102  tapers from about 1.3 mm to about 0.8 mm at a distance of about 1.5 mm from the distal end  206 .  FIG.  10 B  is an example of a taper in elongate member  102  occurring smoothly, for example, over a length of about 4 cm.  FIG.  10 C  is an example of a taper occurring more abruptly, for example, over a length of about 1 mm or less. The taper may be applied to the elongate member  102  by a variety of methods. In some embodiments, the elongate member  102  is manufactured with the taper already incorporated therein. In other embodiments, the elongate member  102  is manufactured without a taper, and the taper is created by swaging the elongate member down to the required outside diameter, or by machining the distal region  202  such that the outside diameter tapers while the inside diameter remains constant. 
     In a further embodiment, the elongate member  102  is manufactured from two pieces of material, each having a different diameter, which are joined together. For example, as shown in  FIG.  10 D , the elongate member  102  includes a main member  210  mechanically coupled to the handle (not shown in  FIG.  10 D ), the main member  210  having a length of about 50 cm to about 100 cm and an outer diameter of about 1.15 mm to about 1.35 mm. The main member  210  defines a main member lumen  214 , as shown in  FIG.  2 E , extending substantially longitudinally therethrough. The main member is co-axially joined to an end member  212 , having a length of about 2.5 cm to about 10 cm and an outer diameter of about 0.40 mm to about 0.80 mm. In some examples, the end member  212  is inserted partially into the main member lumen  214 , substantially longitudinally opposed to the handle  110 . In some embodiments, the electrode  106  is located about the end member, for example, by being mechanically coupled to the end member  212 , while in other embodiments the electrode  106  is integral with the end member  212 . If the end member  212  defines an end member lumen  216 , as seen in  FIGS.  10 D and  2 E , the end member lumen  216  is in fluid communication with the main member lumen  214 , as shown in  FIG.  2 E . The main member  210  and the end member  212  are joined in any suitable manner, for example welding, soldering, friction fitting, or the use of adhesives, among other possibilities. Also, in some embodiments, the main member lumen  214  and the end member lumen  216  have substantially similar diameters, which reduces turbulence in fluids flowing through the main member lumen  214  and the end member lumen  216 . 
     In embodiments of the invention wherein the elongate member  102  defines a lumen  208 , the wall thickness of the elongate member  102  may vary depending on the application, and the invention is not limited in this regard. For example, if a stiffer device is desirable, the wall thickness is typically greater than if more flexibility is desired. In some embodiments, the wall thickness in the force transmitting region is from about 0.05 mm to about 0.40 mm, and remains constant along the length of the elongate member  102 . In other embodiments, wherein the elongate member  102  is tapered, the wall thickness of the elongate member  102  varies along the elongate member  102 . For example, in some embodiments, the wall thickness in the proximal region  200  is from about 0.1 mm to about 0.4 mm, tapering to a thickness of from about 0.05 mm to about 0.20 mm in the distal region  202 . In some embodiments, the wall tapers from inside to outside, thereby maintaining a consistent outer diameter and having a changing inner diameter. Alternative embodiments include the wall tapering from outside to inside, thereby maintaining a consistent inner diameter and having a changing outer diameter. Further alternative embodiments include the wall of the elongate member  102  tapering from both the inside and the outside, for example, by having both diameters decrease such that the wall thickness remains constant. For example, in some embodiments the lumen  208  has a diameter of from about 0.4 mm to about 0.8 mm at the proximal region  200 , and tapers to a diameter of from about 0.3 mm to about 0.5 mm at the distal region  202 . In other alternative embodiments, the outer diameter decreases while the inner diameter increases, such that the wall tapers from both the inside and the outside. 
     In some embodiments, the elongate member  102 , and therefore the medical device  100 , are curved or bent, as shown in  FIGS.  11 A- 11 C . As used herein, the terms ‘curved’ or ‘bent’ refer to any region of non-linearity, or any deviation from a longitudinal axis of the device, regardless of the angle or length of the curve or bend. The medical device  100  includes a substantially rectilinear section  302  and a curved section  300  extending from the substantially rectilinear section  302 . Typically, the curved section  300  is located in the distal region  202  of the elongate member  102 , and may occur over various lengths and at various angles. In some examples, curved section  300  has a relatively large radius, for example, between about 10 cm and about 25 cm, and traverses a small portion of a circumference of a circle, for example between about 20 and about 40 degrees, as shown in  FIG.  11 B . In alternative examples, the curved section  300  has a relatively small radius, for example, between about 4 cm and about 7 cm, and traverses a substantially large portion of a circumference of a circle, for example, between about 50 and about 110 degrees, as shown in  FIG.  11 C . In one specific embodiment, the curved section  300  begins about 8.5 cm from the distal end  206  of the elongate member  102 , has a radius of about 6 cm, and traverses about 80 degrees of a circumference of a circle. In an alternative embodiment, the curved section has a radius of about 5.4 cm and traverses about 50 degrees of a circumference of a circle. In a further embodiment, the curved section has a radius of about 5.7 cm and traverses about 86 degrees of a circumference of a circle. This configuration helps in positioning the elongate member  102  such that the distal end  206  is substantially perpendicular to the tissue through which the channel is to be created. This perpendicular positioning transmits the most energy when a user exerts a force through the elongate member  102 , which provides enhanced feedback to the user. 
     The curved section  300  may be applied to the elongate member  102  by a variety of methods. For example, in one embodiment, the elongate member  102  is manufactured in a curved mold. In another embodiment, the elongate member  102  is manufactured in a substantially straight shape then placed in a heated mold to force the elongate member  102  to adopt a curved shape. Alternatively, the elongate member  102  is manufactured in a substantially straight shape and is forcibly bent by gripping the elongate member  102  just proximal to the region to be curved and applying force to curve the distal region  202 . In an alternative embodiment, the elongate member  102  includes a main member  210  and an end member  212 , as described with respect to  FIG.  10 D , which are joined together at an angle (not shown in the drawings). That is, rather than being coaxial, the main member  210  and an end member  212  are joined such that, for example, they are at an angle of 45° with respect to each other. 
     As mentioned herein above, in some embodiments the proximal region  200  of the elongate member  102  is structured to be coupled to an energy source. To facilitate this coupling, the proximal region  200  may comprise a hub  108  that allows for the energy source to be electrically connected to the elongate member  102 . Further details regarding the hub  108  are described herein below. In other embodiments, the proximal region  200  is coupled to an energy source by other methods known to those of skill in the art, and the invention is not limited in this regard. 
     In typical embodiments, the elongate member  102  is made from an electrically conductive material that is biocompatible. As used herein, ‘biocompatible’ refers to a material that is suitable for use within the body during the course of a surgical procedure. Such materials include stainless steels, copper, titanium and nickel-titanium alloys (for example, NITINOL®), amongst others. Furthermore, in some embodiments, different regions of the elongate member  102  are made from different materials. In an example of the embodiment of  FIG.  10 D , the main member  210  is made from stainless steel such that it provides column strength to a portion of the elongate member  102  (for example, the force transmitting portion), and the end member  212  is made out of a nickel-titanium alloy such as NITINOL®, such that it provides flexibility to a portion of the elongate member  102  (for example, the distal portion). Embodiments wherein the force transmitting portion of the elongate member  102  is manufactured from stainless steel often result in medical device  100  having a similar amount of column strength to a device of the prior art, for example, a mechanical perforator such as a Brockenbrough™ needle. This is beneficial in that it provides a familiar ‘feel’ to users familiar with such devices. In some embodiments comprising a curved or bent elongate member  102 , the rectilinear section  302  is made from stainless steel such that it provides column strength to the elongate member  102 , and the curved section  300  is made out of a nickel-titanium alloy such as NITINOL®, such that it provides flexibility to the elongate member  102 . In addition, the use of NITINOL® for curved section  300  is advantageous as the superelastic properties of this material helps in restoring the shape of the curved section  300  after the curved section  300  is straightened out, for example, when placed within a dilator. 
     As mentioned herein above, an electrical insulation  104  is disposed on at least a portion of the outer surface of the elongate member  102 . In some embodiments, for example as shown in  FIG.  1   , electrical insulation  104  covers the circumference of the elongate member  102  from the proximal region  200  of the elongate member  102  to the distal region  202  of the elongate member  102 . In other words, the force transmitting portion  114  and distal portion  112  are electrically conductive, and the electrical insulation substantially covers the force transmitting portion  114  and distal portion  112 , while the electrode  106  remains substantially uninsulated. When a source of energy is coupled to the proximal region  200  of the elongate member  102 , the electrical insulation  104  substantially prevents leakage of energy along the length of the elongate member  102 , thus allowing energy to be delivered from the proximal region  200  of the elongate member  102  to the electrode  106 . 
     In embodiments as illustrated in  FIG.  1   , the electrical insulation  104  may extend to different locations on the distal region  202  ( FIG.  10   ), depending on the configuration of the electrode  106 . Typically, electrical insulation  104  extends to a proximal end  404  of the electrode  106 , which may or may not coincide with the distal end of the elongate member  102 . For example, as shown in  FIG.  3 A , the distal-most 1.5 mm of the elongate member  102  serves as at least a portion of the electrode  106 . In these embodiments, electrical insulation  104  extends to a point about 1.5 mm proximal to the distal end  206  of the elongate member  102 . In the embodiments of  FIGS.  3 B- 3 C , an external component  400  coupled to the distal end of the elongate member  102  serves as the electrode  106 . In such embodiments, the proximal end  404  of the electrode  106  substantially coincides with the distal end  206  of the elongate member  102 , and thus the electrical insulation  104  extends to the distal end  206  of the elongate member  102 . In some embodiments, the electrical insulation  104  extends beyond the distal end  206  of the elongate member  102 , and covers a portion of the external component  400 . This typically aids in securing the external component  400  to the elongate member  102 . The uncovered portion of the external component  400  can then serve as the electrode  106 . In other embodiments, for example as shown in  FIG.  3 A , the distal-most portion of the elongate member  102 , as well as a rounded external component  402 , serve as the electrode  106 . In this embodiment, the electrical insulation  104  extends to a point substantially adjacent to the distal end  206  of the elongate member  102 . In one example, the electrical insulation  104  extends to a point about 1.0 mm away from the distal end  206  of the elongate member  102 . 
     The electrical insulation  104  may be one of many biocompatible dielectric materials, including but not limited to, polytetrafluoroethylene (PTFE, Teflon®), parylene, polyimides, polyethylene terephtalate (PET), polyether block amide (PEBAX®), and polyetheretherketone (PEEK™), as well as combinations thereof. The thickness of the electrical insulation  104  may vary depending on the material used. Typically, the thickness of the electrical insulation  104  is from about 0.02 mm to about 0.12 mm. 
     In some embodiments, the electrical insulation  104  comprises a plurality of dielectric materials. This is useful, for example, in cases where different properties are required for different portions of the electrical insulation  104 . In certain applications, for example, substantial heat is generated at the electrode  106 . In such applications, a material with a sufficiently high melting point is required for the distal-most portion of the electrical insulation  104 , so that this portion of the electrical insulation  104 , located adjacent to electrode  106 , doesn&#39;t melt. Furthermore, in some embodiments, a material with a high dielectric strength is desired for all of, or a portion of, the electrical insulation  104 . In some particular embodiments, electrical insulation  104  has a combination of both of the aforementioned features. 
     With reference now to  FIG.  2 E , the electrical insulation  104  includes a first electrically insulating layer  218  made out of a first electrically insulating material, and a second electrically insulating layer  220  made out of a second electrically insulating material, and being substantially thinner than the first electrically insulating layer  218 . The first electrically insulating layer  218  substantially covers the main member  210  substantially adjacent the end member  212 , and the second electrically insulating layer  220  substantially covers the end member  212 , with the electrode  106  substantially deprived from the second electrically insulating layer  220 . In the illustrated embodiment, the first electrically insulating layer  218  overlaps the second electrically insulating layer  220  about the region of the taper of the elongate member  102 . This configuration provides desirable mechanical properties for the medical device  100 , as thinner materials are typically less rigid than thicker materials. Also, in some embodiments of the invention, the first electrically insulating layer  218  overlaps a portion of the second electrically insulating layer  220 . However, in alternative embodiments of the invention, the electrical insulation  104  has any other suitable configuration, for example, the first electrically insulating layer  218  and the second electrically insulating layer  220  being made of the same material. 
     In further embodiments as shown in  FIG.  3 D , a heat shield  109  may be applied to the medical device  100  substantially adjacent to the electrode  106 , for example, in order to prevent a distal portion of the electrical insulation  104  from melting due to heat generated by the electrode  106 . For example, in some such embodiments, a thermally insulating material, for example Zirconium Oxide or polytetrafluoroethylene (PTFE), is applied over approximately the distal-most 2 cm of the electrical insulation  104 . Typically, the heat shield  109  protrudes substantially radially outwardly from the remainder of the distal portion  112  and substantially longitudinally from the electrode  106  in a direction leading towards the handle  110 . 
     The electrical insulation  104  may be applied to the elongate member  102  by a variety of methods. For example, if the electrical insulation  104  includes PTFE, it may be provided in the form of heat-shrink tubing, which is placed over the elongate member  102  and subjected to heat to substantially tighten around the elongate member  102 . If the electrically insulating material is parylene, for example, it may be applied to the elongate member  102  by vapor deposition. In other embodiments, depending on the specific material used, the electrical insulation  104  may be applied to the elongate member  102  using alternate methods such as dip-coating, co-extrusion, or spraying. 
     As mentioned herein above, in embodiments of the present invention the elongate member  102  comprises an electrode  106  at the distal region, the electrode  106  configured to create a channel via radiofrequency perforation. As used herein, ‘radiofrequency perforation’ refers to a procedure in which radiofrequency (RF) electrical energy is applied from a device to a tissue to create a perforation or fenestration through the tissue. Without being limited to a particular theory of operation, it is believed that the RF energy serves to rapidly increase tissue temperature to the extent that water in the intracellular fluid converts to steam, inducing cell lysis as a result of elevated pressure within the cell. Furthermore, electrical breakdown may occur within the cell, wherein the electric field induced by the alternating current exceeds the dielectric strength of the medium located between the radiofrequency perforator and the cell, causing a dielectric breakdown. In addition, mechanical breakdown may occur, wherein alternating current induces stresses on polar molecules in the cell. Upon the occurrence of cell lysis and rupture, a void is created, allowing the device to advance into the tissue with little resistance. In order to increase the current density delivered to the tissue and achieve this effect, the device from which energy is applied, i.e. the electrode, is relatively small, having an electrically exposed surface area of no greater than about 15 mm 2 . In addition, the energy source is capable of applying a high voltage through a high impedance load, as will be discussed further herein below. This is in contrast to RF ablation, whereby a larger-tipped device is utilized to deliver RF energy to a larger region in order to slowly desiccate the tissue. As opposed to RF perforation, which creates a void in the tissue through which the device is advanced, the objective of RF ablation is to create a large, non-penetrating lesion in the tissue, in order to disrupt electrical conduction. Thus, for the purposes of the present invention, the electrode refers to a device which is electrically conductive and exposed, having an exposed surface area of no greater than about 15 mm 2 , and which is operable to delivery energy to create a perforation or fenestration through tissue when coupled to a suitable energy source and positioned at a target site. The perforation is created, for example, by vaporizing intracellular fluid of cells with which it is in contact, such that a void, hole, or channel is created in the tissue located at the target site. 
     In further embodiments, as shown in  FIG.  3 A , it is desirable for the distal end  206  of the elongate member  102  to be closed. For example, in some embodiments, it is desirable for fluids to be injected radially from the elongate member  102 , for example, through side-ports in elongate member  102  substantially without being injected distally from the elongate member  102 , as discussed herein below. In these embodiments, a closed distal end  206  facilitates radial injection of fluid while preventing distal injection. 
     It is a common belief that it is necessary to have a distal opening in order to properly deliver a contrast agent to a target site. However, it was unpredictably found that it is possible to properly operate the medical device  100  in the absence of distal openings. Advantageously, these embodiments reduce the risk that a core of tissue becomes stuck in such a distal opening when creating the channel through the tissue. Avoiding such tissue cores is desirable as they may enter the blood circulation, which creates risks of blocking blood vessels, leading to potentially lethal infarctions. 
     Thus, as shown in  FIG.  3 A , a rounded external component  402 , for example an electrode tip, is operatively coupled to the distal end  206 . In this embodiment, the exposed portion of the distal region  202  ( FIG.  10 A to  10 D ), as well as the rounded external component  402 , serves as the electrode  106 . In such an embodiment, if the outer diameter of the elongate member  102  is 0.7 mm, the rounded external component  402  is a hemisphere having a radius of about 0.35 mm, and the length of the distal-most exposed portion of the elongate member  102  is about 2.0 mm, and then the surface area of the electrode  106  is about 5.2 mm 2 . Alternatively, as shown for example in  FIG.  2 E , the distal end of end member  212  is closed and used as the electrode  106 , rather than a separate external component. 
     In other embodiments as shown, for example, in  FIGS.  3 B and  3 C , an electrically conductive and exposed external component  400  is electrically coupled to the distal end of the elongate member  102 , such that the external component  400  serves as the electrode  106 . In such embodiments, external component  400  is a cylinder having a diameter of between about 0.4 mm and about 1 mm, and a length of about 2 mm. Electrode  106  thus has an exposed surface area of between about 2.6 mm 2  and about 7.1 mm 2 . 
     The external component  400  may take a variety of shapes, for example, cylindrical, main, conical, or truncated conical. The distal end of the external component  400  may also have different configuration, for example, rounded, or flat. Furthermore, some embodiments of the external component  400  are made from biocompatible electrically conductive materials, for example, stainless steel. The external component  400  may be coupled to the elongate member  102  by a variety of methods. In one embodiment, external component  400  is welded to the elongate member  102 . In another embodiment, external component  400  is soldered to the elongate member  102 . In one such embodiment, the solder material itself comprises the external component  400 , e.g., an amount of solder is electrically coupled to the elongate member  102  in order to function as at least a portion of the electrode  106 . In further embodiments, other methods of coupling the external component  400  to the elongate member  102  are used, and the invention is not limited in this regard. 
     In these embodiments, as described herein above, the electrically exposed and conductive surface area of the electrode  106  is no greater than about 15 mm 2 . In embodiments wherein the electrical insulation  104  covers a portion of the external component  400 , the portion of the external component  400  that is covered by the electrical insulation  104  is not included when determining the surface area of the electrode  106 . 
     Referring again to  FIG.  3 A , in some embodiments, the distal portion  112  defines a distal tip  403 , the distal tip  403  being substantially atraumatic. In other words, the distal end of the medical device  100  is structured such that it is substantially atraumatic, or blunt. As used herein, the terms ‘atraumatic’ and ‘blunt’ refer to a structure that is not sharp, and includes structures that are rounded, obtuse, or flat, amongst others, as shown, for example, in  FIG.  3 A . In embodiments wherein the distal end of the medical device  100  is substantially blunt, the blunt distal end is beneficial for avoiding unwanted damage to non-target areas within the body. That is, if mechanical force is unintentionally applied to the medical device  100  when the distal end of the medical device  100  is located at a non-target tissue, the medical device  100  is less likely to perforate the non-target tissue. 
     In some embodiments, the distal tip  403  is substantially bullet-shaped, as shown in  FIG.  2 E , which allows the intended user to drag the distal tip  403  across the surface of tissues in the patient&#39;s body and to catch on to tissues at the target site. For example, if the target site includes a fossa ovalis, as described further herein below, the bullet-shaped tip may catch on to the fossa ovalis so that longitudinal force applied at a proximal portion of medical device  100  causes the electrode  106  to advance into and through the fossa ovalis rather than slipping out of the fossa ovalis. Because of the tactile feedback provided by the medical device  100 , this operation facilitates positioning of the medical device  100  prior to energy delivery to create a channel. 
     As mentioned herein above, in some embodiments, the medical device  100  comprises a hub  108  coupled to the proximal region. In some embodiments, the hub  108  is part of the handle  110  of the medical device  100 , and facilitates the connection of the elongate member  102  to an energy source and a fluid source, for example, a contrast fluid source. 
     In the embodiment illustrated in  FIGS.  12 A and  12 B , the proximal region  200  the of the elongate member  102  is electrically coupled to the hub  108 , which is structured to electrically couple the elongate member  102  to a source of energy, for example, a radiofrequency generator. In one embodiment, the hub  108  comprises a conductive wire  500  that is connected at one end to the elongate member  102 , for example, by welding or brazing. The other end of the wire  500  is coupled to a connector (i.e. a connector means for receiving), for example a banana jack  502 , that can be electrically coupled to a banana plug  504 , which is electrically coupled to a source of energy. Thus, electrical energy may be delivered from the energy source, through plug  504 , jack  502 , and wire  500  to the elongate member  102  and electrode  106 . In other embodiments, other hubs or connectors that allow elongate member  102  to be connected to a source of fluid and a source of energy are used, and the invention is not limited in this regard. 
     In some embodiments, medical device  100  is a transseptal puncturing device comprising an elongate member which is electrically conductive, an electrical connector in electrical communication with the elongate member, and an electrode at a distal end of the electrically conductive elongate member for delivering energy to tissue. A method of using the transseptal puncturing device comprises the steps of (1) connecting an electrically conductive component, which is in electrical communication with a source of energy, to the electrical connector, and (2) delivering electrical energy through the electrode to a tissue. The electrically conductive component may comprise a plug, such as plug  504 , and a wire connected thereto. Some embodiments of the method further comprise a step (3) of disconnecting the electrically conductive component from the electrical connector. In such embodiments, the electrically conductive component is connected in a releasable manner. 
     In some embodiments, the hub  108  is structured to be operatively coupled to a fluid connector  506 , for example a Luer lock, which is connected to tubing  508 . Tubing  508  is structured to be operatively coupled at one end to an aspirating device, a source of fluid  712  (for example a syringe), or a pressure sensing device (for example a pressure transducer  708 ). The other end of tubing  508  may be operatively coupled to the fluid connector  506 , such that tubing  508  and lumen  208  are in fluid communication with each other, thus allowing for a flow of fluid between an external device and the lumen  208 . In embodiments in which a hub  108  is part of handle  110 , fluid and/or electrical connections do not have to be made only with the hub  108  i.e. connections may be made with other parts of the handle  110 , or with parts of medical device  100  other than the handle. 
     In some embodiments, the hub  108  further comprises one or more curve-direction or orientation indicators  510  that are located on one side of the hub  108  to indicate the direction of the curved section  300 . The orientation indicator(s)  510  may comprise inks, etching, or other materials that enhance visualization or tactile sensation. 
     In some embodiments of the invention, the handle  110  includes a relatively large, graspable surface so that tactile feedback can be transmitted relatively efficiently, for example by transmitting vibrations. In some embodiments of the invention, the handle  110  includes ridges  512 , for example, in the hub  108 , which enhance this tactile feedback. The ridges  512  allow the intended user to fully grasp the handle  110  without holding the handle  110  tightly, which facilitates the transmission of this feedback. 
     In some embodiments of the invention, the medical device  100 , as shown in  FIG.  2 E , defines a lumen peripheral surface  602  extending substantially peripherally relative to the end member lumen  216 , the lumen peripheral surface  602  being substantially covered with a lumen electrically insulating material  604 . This configuration prevents or reduces electrical losses from the lumen peripheral surface  602  to any electrically conductive fluid located within the lumen  208 . However, in other embodiments of the invention, the lumen peripheral surface  602  is not substantially covered with the lumen electrically insulating material  604 . 
     Also, in some embodiments of the invention that include the curved section  300 , the curved section  300  defines a center of curvature (not shown in the drawings), and the side-port(s)  600  extend from the lumen  208  substantially towards the center of curvature. This configuration substantially prevents the edges of the side-port(s)  600  from catching onto tissues as the tissues are perforated. However, in alternative embodiments of the invention, the side-port(s)  600  extend in any other suitable orientation. 
     In some embodiments, one or more radiopaque markers  714  (as shown in  FIG.  8   ) are associated with the medical device  100  to highlight the location of important landmarks on medical device  100 . Such landmarks include the location where the elongate member  102  begins to taper, the location of the electrode  106 , or the location of any side-port(s)  600 . In some embodiments, the entire distal region  202  of the medical device  100  is radiopaque. This can be achieved by filling the electrical insulation  104 , for example Pebax®, with a radiopaque filler, for example Bismuth. 
     In some embodiments, the shape of the medical device  100  may be modifiable. For example, in some applications, it is desired that medical device  100  be capable of changing between a straight configuration, for example as shown in  FIG.  1   , and a curved configuration, for example as shown in  FIGS.  11 A- 11 C . This may be accomplished by coupling a pull-wire to the medical device  100 , such that the distal end of the pull-wire is operatively coupled to the distal region of the medical device  100 . When a user applies force to the proximal end of the pull wire, either directly or through an actuating mechanism, the distal region  202  of the medical device  100  is forced to deflect in a particular direction. In other embodiments, other means for modifying the shape of the medical device  100  are used, and the invention is not limited in this regard. 
     In some embodiments, the medical device  100  includes at least one further electrically conductive component, located proximal to the electrode  106 . For example, the electrically conductive component may be a metal ring positioned on or around the electrical insulation  104  which has a sufficiently large surface area to be operable as a return electrode. In such an embodiment, the medical device  100  may function in a bipolar manner, whereby electrical energy flows from the electrode  106 , through tissue at the target site, to the at least one further electrically conductive component. Furthermore, in such embodiments, the medical device  100  includes at least one electrical conductor, for example a wire, for conducting electrical energy from the at least one further conductive component to a current sink, for example, circuit ground. 
     In some embodiments, medical device  100  is used in conjunction with a source of radiofrequency energy suitable for perforating material within a patient&#39;s body. The source of energy may be a radiofrequency (RF) electrical generator  700 , operable in the range of about 100 kHz to about 1000 kHz, and designed to generate a high voltage over a short period of time. More specifically, in some embodiments, the voltage generated by the generator increases from about 0 V (peak-to-peak) to greater than about 75 V (peak-to-peak) in less than about 0.6 seconds. The maximum voltage generated by generator  700  may be between about 180V peak-to-peak and about 3000V peak-to-peak. The waveform generated may vary, and may include, for example, a sine-wave, a rectangular-wave, or a pulsed rectangular wave, amongst others. During delivery of radiofrequency energy, the impedance load may increase due to occurrences such as tissue lesioning near the target-site, or the formation of a vapor layer following cell rupture. In some embodiments, the generator  700  is operable to continue to increase the voltage, even as the impedance load increases. For example, energy may be delivered to a tissue within a body at a voltage that rapidly increases from about 0 V (RMS) to about 220 V (RMS) for a period of between about 0.5 seconds and about 5 seconds. 
     Without being limited to a particular theory of operation, it is believed that under particular circumstances, as mentioned herein above, dielectric breakdown and arcing occur upon the delivery of radiofrequency energy, whereby polar molecules are pulled apart. The combination of these factors may result in the creation of an insulative vapor layer around the electrode, therein resulting in an increase in impedance, for example, the impedance may increase to greater than 4000Ω. In some embodiments, despite this high impedance, the voltage continues to increase. Further increasing the voltage increases the intensity of fulguration, which may be desirable as it allows for an increased perforation rate. An example of an appropriate generator for this application is the BMC RF Perforation Generator (model number RFP-100, Baylis Medical Company, Montreal, Canada). This generator delivers continuous RF energy at about 460 kHz. 
     In some embodiments, a dispersive electrode or grounding pad  702  is electrically coupled to the generator  700  for contacting or attaching to a patient&#39;s body to provide a return path for the RF energy when the generator  700  is operated in a monopolar mode. Alternatively, in embodiments utilizing a bipolar device, as described hereinabove, a grounding pad is not necessary as a return path for the RF energy is provided by the further conductive component. 
     In the embodiment illustrated in  FIGS.  12 A and  12 B , the medical device  100  is operatively coupled to the tubing  508  using fluid connector  506  located at the proximal end of the medical device  100 . In some embodiments, the tubing  508  is made of a polymeric material such as polyvinylchloride (PVC), or another flexible polymer. Some embodiments include the tubing  508  being operatively coupled to an adapter  704 . The adapter is structured to provide a flexible region for the user to handle when releasably coupling an external pressure transducer, a fluid source, or other devices to the adapter. In some embodiments, couplings between elongate member  102 , fluid connector  506 , and tubing  508 , and between tubing  508  and adapter  704 , are temporary couplings such as Luer locks or other releasable components. In alternative embodiments, the couplings are substantially permanent, for example a bonding agent such as a UV curable adhesive, an epoxy, or another type of bonding agent. Some embodiments of the medical device  100  include a distal aperture in fluid communication with the lumen  208  wherein the distal aperture is a side-port  600 , while some alternative embodiments have a distal aperture defined by an open distal end. 
     In one broad aspect, the electrosurgical medical device  100  is usable to deliver energy to a target site within a patient&#39;s body to perforate or create a void or channel in a material at the target site. Further details regarding delivery of energy to a target site within the body may be found in U.S. patent application Ser. No. 13/113,326 (filed on May 23, 2011), Ser. No. 10/347,366 (filed on Jan. 21, 2003, now U.S. Pat. No. 7,112,197), Ser. No. 10/760,749 (filed on Jan. 21, 2004), Ser. No. 10/666,288 (filed on Sep. 19, 2003), and Ser. No. 11/265,304 (filed on Nov. 3, 2005), and U.S. Pat. No. 7,048,733 (application Ser. No. 10/666,301, filed on Sep. 19, 2003) and U.S. Pat. No. 6,565,562 (issued on May 20, 2003), all of which are incorporated herein by reference. 
     In one specific embodiment, the target site comprises a tissue within the heart of a patient, for example, the atrial septum of the heart. In such an embodiment, the target site may be accessed via the inferior vena cava (IVC), for example, through the femoral vein. 
     In one such embodiment, an intended user introduces a guidewire into a femoral vein, typically the right femoral vein, and advances it towards the heart. A guiding sheath, for example, a sheath as described in U.S. patent application Ser. No. 10/666,288 (filed on Sep. 19, 2003), previously incorporated herein by reference, is then introduced into the femoral vein over the guidewire, and advanced towards the heart. The distal ends of the guidewire and sheath are then positioned in the superior vena cava. These steps may be performed with the aid of fluoroscopic imaging. When the sheath is in position, a dilator, for example the TorFlex™ Transseptal Dilator of Baylis Medical Company Inc. (Montreal, Canada), or the dilator as described in U.S. patent application Ser. No. 11/727,382 (filed on Mar. 26, 2007), incorporated herein by reference, is introduced into the sheath and over the guidewire, and advanced through the sheath into the superior vena cava. The sheath aids in preventing the dilator from damaging or puncturing vessel walls, for example, in embodiments comprising a substantially stiff dilator. Alternatively, the dilator may be fully inserted into the sheath prior to entering the body, and both may be advanced simultaneously towards the heart. When the guidewire, sheath, and dilator have been positioned in the superior vena cava, the guidewire is removed from the body, and the sheath and dilator are retracted slightly such that they enter the right atrium of the heart. An electrosurgical device, for example medical device  100  described herein above, is then introduced into the lumen of the dilator, and advanced toward the heart. 
     In this embodiment, after inserting the electrosurgical device into the dilator, the user positions the distal end of the dilator against the atrial septum. The electrosurgical device is then positioned such that electrode  106  is aligned with or protruding slightly from the distal end of the dilator. When the electrosurgical device and the dilator have been properly positioned, for example, against the fossa ovalis of the atrial septum, a variety of additional steps may be performed. These steps may include measuring one or more properties of the target site, for example, an electrogram or ECG (electrocardiogram) tracing and/or a pressure measurement, or delivering material to the target site, for example, delivering a contrast agent through side-port(s)  600  and/or open distal end  206 . Such steps may facilitate the localization of the electrode  106  at the desired target site. In addition, as mentioned herein above, the tactile feedback provided by the proposed medical device  100  is usable to facilitate positioning of the electrode  106  at the desired target site. 
     With the electrosurgical device and the dilator positioned at the target site, energy is delivered from the energy source, through medical device  100 , to the target site. For example, energy is delivered through the elongate member  102 , to the electrode  106 , and into the tissue at the target site. In some embodiments, the energy is delivered at a power of at least about 5 W at a voltage of at least about 75 V (peak-to-peak), and, as described herein above, functions to vaporize cells in the vicinity of the electrode, thereby creating a void or perforation through the tissue at the target site. If the heart was approached via the inferior vena cava, as described herein above, the user applies force in the substantially cranial direction to the handle  110  of the electrosurgical device as energy is being delivered. The force is then transmitted from the handle to the distal portion  112  of the medical device  100 , such that the distal portion  112  advances at least partially through the perforation. In these embodiments, when the distal portion  112  has passed through the target tissue, that is, when it has reached the left atrium, energy delivery is stopped. In some embodiments, the step of delivering energy occurs over a period of between about 1 s and about 5 s. 
     At this point in the procedure, the diameter of the perforation is typically substantially similar to the outer diameter of the distal portion  112 . In some examples, the user may wish to enlarge the perforation, such that other devices such as ablation catheters or other surgical devices are able to pass through the perforation. Typically, to do this, the user applies force to the proximal region of the dilator, for example, in the cranial direction if the heart was approached via the inferior vena cava. The force typically causes the distal end of the dilator to enter the perforation and pass through the atrial septum. The electrosurgical device is operable to aid in guiding the dilator through the perforation, by acting as a substantially stiff rail for the dilator. In such embodiments, a curve, for example, curved section  300  of the medical device  100 , typically assists in anchoring the electrosurgical device in the left atrium. In typical embodiments, as force is applied, portions of the dilator of larger diameter pass through the perforation, thereby dilating, expanding, or enlarging the perforation. In some embodiments, the user also applies torque to aid in maneuvering the dilator. Alternatively, in embodiments wherein the device is tapered, the device may be advanced further into the left atrium, such that larger portions of the device enter and dilate the perforation. 
     In some embodiments, when the perforation has been dilated to a suitable size, the user stops advancing the dilator. A guiding sheath is then advanced over the dilator through the perforation. In alternative embodiments, the sheath is advanced simultaneously with the dilator. At this point in the procedure, the user may retract the dilator and the electrosurgical device proximally through the sheath, leaving only the sheath in place in the heart. The user is then able to perform a surgical procedure on the left side of the heart via the sheath, for example, introducing a surgical device into the femoral vein through the sheath for performing a surgical procedure to treat electrical or morphological abnormalities within the left side of the heart. 
     If an apparatus of the present invention, as described herein above, is used to carry out a procedure as described herein, then the user is able to maintain the ‘feel’ of a mechanical perforator, for example a Brockenbrough™ needle, without requiring a sharp tip and large amounts of mechanical force to perforate the atrial septum. Rather, a radiofrequency perforator, for example, the electrode  106 , is used to create a void or channel through the atrial septum, as described herein above, while reducing the risk of accidental puncture of non-target tissues. 
     In other embodiments, methods of the present invention may be used for treatment procedures involving other regions within the body, and the invention is not limited in this regard. For example, rather than the atrial septum, embodiments of devices, systems, and methods of the present invention can be used to treat pulmonary atresia. In some such embodiments, a sheath is introduced into the vascular system of a patient and guided to the heart, as described herein above. A dilator is then introduced into the sheath, and advanced towards the heart, where it is positioned against the pulmonary valve. An electrosurgical device comprising an electrode is then introduced into the proximal region of the dilator, and advanced such that it is also positioned against the pulmonary valve. Energy is then delivered from the energy source, through the electrode of the electrosurgical device, to the pulmonary valve, such that a puncture or void is created as described herein above. When the electrosurgical device has passed through the valve, the user is able to apply a force to the proximal region of the dilator, for example, in a substantially cranial direction. The force can be transmitted to the distal region of the dilator such that the distal region of the dilator enters the puncture and advances through the pulmonary valve. As regions of the dilator of larger diameter pass through the puncture, the puncture or channel becomes dilated. 
     In other applications, embodiments of a device of the present invention can be used to create voids or channels within or through other tissues of the body, for example within or through the myocardium of the heart. In other embodiments, the device is used to create a channel through a fully or partially occluded lumen within the body. Examples of such lumens include, but are not limited to, blood vessels, the bile duct, airways of the respiratory tract, and vessels and/or tubes of the digestive system, the urinary tract and/or the reproductive system. In such embodiments, the device is typically positioned such that an electrode of the device is substantially adjacent the material to be perforated. Energy is then delivered from an energy source, through the electrode  106 , to the target site such that a void, puncture, or channel is created in or through the tissue. 
     This disclosure describes embodiments of a kit and its constituent components which together form an apparatus in which fluid communication between a medical device&#39;s lumen and the surrounding environment is provided by a conduit cooperatively defined by the medical device and a tubular member into which the device is inserted. The medical device and tubular member are configured to fit together such that an outer surface of the distal region of the medical device cooperates with an inner surface of the tubular member to define the conduit between the side-port of the medical device and a distal end of the tubular member. The conduit is operable for a variety of applications including injecting fluid, withdrawing fluid, and measuring pressure. Methods of assembling and using the apparatus are described as well. 
     This disclosure further describes an electrosurgical device configured for force transmission from a distal portion of the electrosurgical device to a proximal portion of the electrosurgical device to thereby provide tactile feedback to a user. The proximal portion of the device comprises a handle and/or a hub, with the handle (or hub) including an electrical connector (i.e. a connector means) which is configured to receive, in a releasable manner, an electrically conductive component which is operable to be in electrical communication with an energy source to allow the user to puncture a tissue layer. In some cases, a radiofrequency (RF) energy source is used to selectively apply RF energy to the tissue. Typical embodiments of the device include insulation to protect the user and the patient. 
     The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims. 
     It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. 
     Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations are apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the appended claims.