Patent Publication Number: US-2023149675-A1

Title: Hybrid transseptal dilator and methods of using the same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of International Application No. PCT/IB2021/056514, filed Jul. 19, 2021, titled “HYBRID TRANSSEPTAL DILATOR AND METHODS OF USING THE SAME,” which claims priority to U.S. Provisional Application No. 63/053,930, filed Jul. 20, 2020, titled “HYBRID TRANSSEPTAL DILATOR AND METHODS OF USING THE SAME,” and U.S. Provisional Application No. 63/085,517, filed Sep. 30, 2020, titled “HYBRID TRANSSEPTAL DILATOR AND METHODS OF USING THE SAME,” the entire disclosures of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a medical device for use in accessing the cardiovascular system. More particularly the present disclosure relates to a hybrid transseptal dilator for facilitating a transseptal procedure for providing left heart access. 
     BACKGROUND 
     When performing a transseptal procedure to gain access to the left atrium of a heart, a physician typically uses a sheath and dilator to support a crossing or puncturing device. In some cases, a physician may not be able to cross through to the left atrium as the transition between sheath and dilator may get stuck or snag at the tissue boundary, and as a result the sheath may not be able to cross through the perforation (or it crosses with difficulty). In other words, the tissue may get hung up at the sheath/dilator interface. Thus, the use of multiple devices in a transseptal procedure may make it difficult for the operator to complete the procedure due to the material transitions between various devices which may get caught at the septal tissue interface. 
     Some conventional transseptal procedures, for example some that use the inferior approach to gain access to the heart, use a needle in order to carry out a transseptal puncture. Certain limitations may be associated with the use of needles or other rigid devices for carrying out a transseptal puncture procedure. 
     These limitations may include one or more of: (1) need for a separate exchange wire to gain access to the SVC resulting in multiple device exchanges on the right side; (2) the use of a needle may require multiple device exchanges in order to complete the procedure; (3) difficulty in correcting placement of the puncture device after insertion within the right atrium if the target site on the septum is missed; (4) there may be a lack of repeatability for certain aspects of the procedure for completing the puncture in an effective and timely manner; (5) the puncture device may not provide sufficient atraumacity and may result in excessive force being applied to puncture tissue resulting in damage to tissue; (6) possible risk of trauma to the structures within the left atrium following puncture due to the force of advancement; (7) there may be a lack of adequate anchoring after puncture to maintain access; (8) need for an additional exchange on the left side requiring removal of the puncture device and advancement of another wire (such as a pigtail wire) to facilitate anchoring; and/or (9) trackability to allow additional devices to be tracked over the wire once in the left side. 
    
    
     
       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, in which: 
         FIG.  1 A  is an illustration of a hybrid dilator, in accordance with an embodiment of the present invention; 
         FIG.  1 B  is an illustration of a proximal portion of the hybrid dilator of  FIG.  1 A ; 
         FIG.  1 C  is a front end view of a distal tip of the hybrid dilator of  FIG.  1 A ; 
         FIG.  1 D  is an illustration of a proximal portion of the hybrid dilator of  FIG.  1 A ; 
         FIG.  2 A . is a cross-sectional view of the distal tip of a hybrid dilator taken along the lines  2 A- 2 A of  FIG.  1 C ; 
         FIG.  2 B . is a cross-sectional view of the distal most end of a hybrid dilator taken along the lines  2 B- 2 B of  FIG.  1 C ; 
         FIG.  2 C  is an illustration of a distal tip, in accordance with an alternative embodiment of the present invention; 
         FIGS.  3 A- 3 D  illustrate alternate embodiments of a distal tip, in accordance with alternate embodiments of the present invention; 
         FIG.  4 A  illustrates a hybrid dilator in accordance with an embodiment of the present invention, and a standard sheath/dilator assembly usable in a standard transseptal procedure; 
         FIGS.  4 B- 4 G  illustrate a proximal portion of the hybrid dilator in accordance with an embodiment of the present invention; 
         FIGS.  5 A- 5 C  illustrates a proximal portion of a hybrid dilator, in accordance with an alternate embodiment of the present invention; 
         FIG.  5 D  illustrates a hybrid dilator, in accordance with an alternate embodiment of the present invention; 
         FIG.  5 E  illustrates an alternative embodiment of a proximal hub, in accordance with an embodiment of the present invention; 
         FIG.  6 A  is an illustration of a method of using a sheath and dilator, in accordance with a standard transseptal procedure; 
         FIG.  6 B  is a flowchart illustrating steps in a standard transseptal procedure; 
         FIG.  7 A  is an illustration of a method for performing a transseptal puncture procedure using a hybrid dilator, in accordance with an embodiment of the present invention; 
         FIG.  7 B  is a flowchart illustrating steps of a method for performing a transseptal puncture procedure using a hybrid dilator, in accordance with an embodiment of the present invention 
         FIG.  8    is a cross sectional view of the shaft and distal tip of a hybrid dilator of an alternative embodiment of the present invention; 
         FIG.  9    is an enlarged view of the distal tip of  FIG.  8   ; 
         FIG.  10 A- 10 D  illustrates a cross sectional view of the shaft of a hybrid dilator in accordance with an embodiment of the present invention; 
         FIG.  11 A- 11 C  illustrates a cross sectional view of the shaft of a hybrid dilator in accordance with an alternate embodiment of the present invention; 
         FIG.  12    is a flowchart illustrating steps of a method for performing a transseptal puncture procedure using a hybrid dilator in accordance with an embodiment of the present invention; 
         FIG.  13 A  is an illustration of a steerable hybrid dilator, in accordance with an embodiment of the present invention; 
         FIG.  13 B  is an illustration of the handle of the embodiment of  FIG.  13 A ; 
         FIG.  14 A  illustrates a hybrid dilator in accordance with an embodiment of the present invention; 
         FIG.  14 B  illustrates the hybrid dilator of  14 A in use; 
         FIG.  15 A  illustrates a hybrid dilator in accordance with an alternate embodiment of the present invention; 
         FIG.  15 B  illustrates the hybrid dilator of  15 A in use; 
         FIG.  16 A  illustrates a hybrid dilator in accordance with an alternate embodiment of the present invention; 
         FIG.  16 B  illustrates the hybrid dilator of  16 B in use; 
         FIG.  17    is a flowchart illustrating steps of a method for performing a transseptal puncture procedure using a hybrid dilator in accordance with an alternate embodiment of the present invention; 
         FIG.  18    illustrates a flexible puncture device in accordance with an embodiment of the present invention; 
         FIG.  19    illustrates the distal tip of a hybrid dilator with a radiopaque marker in accordance with an alternate embodiment of the present invention; 
         FIG.  20    illustrates the distal tip of a hybrid dilator with a radiopaque marker under fluoroscopy; and 
         FIG.  21    illustrates the mechanical properties of Nitinol compared to steel; 
         FIG.  22 A- 22 B  illustrate a hybrid dilator in accordance with an alternate embodiment of the present invention; 
         FIG.  22 C- 22 D  illustrate a cross sectional view of the hybrid dilator of  FIG.  22 A ; 
         FIG.  23 A- 23 C  illustrate the distal portion of a hybrid dilator in accordance with an embodiment of the present invention; 
         FIG.  24 A- 24 C  illustrate the distal portion of a hybrid dilator with a radiopaque marker in accordance with an alternate embodiment of the present invention; and 
         FIG.  25    illustrates the hub of a hybrid dilator in accordance with an embodiment of the present invention. 
         FIG.  26    is an illustration of a method of using a sheath and dilator, in accordance with a standard transseptal procedure; 
         FIGS.  27 A- 29 B  are illustrations of a method of using a hybrid dilator in accordance with an embodiment of the present invention 
         FIG.  30    is a flowchart illustrating steps of a method for performing a transseptal puncture procedure using a hybrid dilator in accordance with an embodiment of the present invention; 
         FIG.  31    is a flowchart illustrating steps of a method for performing a transseptal puncture procedure using a hybrid dilator in accordance with an alternate embodiment of the present invention; 
     
    
    
     DETAILED DESCRIPTION 
     The problem of a transseptal puncture being performed using a crossing device which is supported by a sheath and dilator set having a transition which may snag on tissue when crossing the septum, can be addressed by using a hybrid dilator (described herein) instead of the sheath and dilator set to thereby eliminate the transition, wherein the hybrid dilator has the appropriate functionality (flexibility, pushability, torqueability, distal taper, steerability, etc.) to facilitate a smooth crossing. 
     The inventors of the present invention have discovered systems and methods that attempt to overcome the limitations associated with prior art systems. 
     In one broad aspect, embodiments of the present invention include a hybrid dilator for use with a crossing device in tissue puncturing procedures, the hybrid dilator comprising: a dilator shaft defining a lumen for receiving a crossing device therethrough, the dilator shaft being structured to allow navigation to the target site and provide support for the crossing device when the crossing device is used to create a puncture in a tissue; 
     and a distal tip having an outer diameter which tapers down to an outer diameter of the crossing device for providing a smooth transition between the crossing device and the distal tip when the crossing device is inserted through the lumen and protrudes beyond the distal tip. In some such embodiments, the dilator shaft comprises an inner layer, an outer layer, and a torque layer therebetween. 
     In some such embodiments of the present invention, the hybrid dilator comprises a stiffening member that is reshapeable. 
     In some embodiments of the present invention, the hybrid dilator comprises a deflectable distal end. 
     In some embodiments of the present invention, the hybrid dilator is steerable. 
     Additionally, the present inventors have discovered a method to perform a transseptal medical procedure that streamlines the procedural workflow by providing a hybrid dilator that replaces a conventional transseptal sheath and dilator assembly. With the hybrid dilator of the present invention a reduced number of devices may be required in order to complete a transseptal procedure. This reduces the number of parts that a physician is required to prepare and assemble for the transseptal procedure and introduce into the patient. The present method provides a dilator that is usable with a guidewire for access that replaces a sheath, dilator, and guidewire assembly. 
     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 certain embodiments of the present invention only. 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. 
     In some embodiments, a single piece/unitary device in the form of a hybrid dilator is provided that provides smooth tapers functions to facilitate both the crossing and the exchange of devices in a trans-septal procedure while still providing the physician with tactile feedback and distal curve indication that are substantially equivalent to those provided by a sheath/dilator assembly. 
     In accordance with an embodiment of the present invention, a hybrid dilator  100  is provided, as shown in  FIG.  1 A . The hybrid dilator  100  comprises a combination of features that provide a dual functionality of a sheath and a dilator for facilitating a transseptal puncture procedure while avoiding disadvantages of conventional sheath and dilator assemblies. The hybrid dilator  100  provides the smoothness of a standard transseptal dilator with the control of a standard transseptal sheath. More specifically, the hybrid dilator  100  functions as a single device that removes the need for using a conventional sheath/dilator assembly and eliminates the need for assembly, resulting in less waste, fewer exchanges, and reduced procedure time. The hybrid dilator  100  comprises a sheath-like handle with familiar torque and tactile control. In the specific example shown, the hybrid dilator  100  defines a proximal portion  110  comprising a molded combination proximal hub  112 , as shown in  FIGS.  1 B and  1 D . A distal portion  120  is coupled to the proximal portion  110  comprising a dilator shaft. The dilator shaft extends from the proximal end and defines a curved distal end  130  that terminates in a distal tip  140 , as additionally shown in  FIG.  1 C . 
     Dilator Shaft/Support and Columnar Strength/Positioning 
     The dilator shaft is formed from a smooth distal tubing  121  that is coupled to the molded proximal hub  112 . The distal tubing  121  defines a lumen  122  there-through that narrows at the distal tip  140  and which may be used to flush the device prior to use. In some embodiments, since the hybrid dilator  100  provided a single unitary device, this means that one product is to be flushed unlike the prior art sheath/dilator assembly where each product requires flushing. The dilator shaft provides mechanical properties to best facilitate procedural activities. At the distal tip  140 , as illustrated further in  FIG.  2 A , the distal tubing  121  transitions through a smooth external taper T 3  that widens in the proximal direction to a greater outer diameter (OD) than a conventional transseptal kit dilator so as to dilate the septum to an appropriate size for the subsequent delivery device or equipment that may be used. The OD of the distal tubing  121  is substantially constant from the proximal edge of distal tip  140  till the proximal hub  112  where the distal tubing is coupled or attached thereto. In some such embodiments, the OD of the hybrid dilator  100  may vary based on the application and clinical use. In some embodiments, the size of hybrid dilator  100  is from about 12 French to about 20 French. In a specific example, the hybrid dilator has a size of about 12.5 French (outer diameter of about 0.163 inches (0.414 cm) to about 0.166 inches (0.421 cm)). In another example, the hybrid dilator has a size of about 15 French (outer diameter of about 0.193 inches (0.490 cm) to about 0.205 inches (0.521 cm)). 
     Distal End Curvature 
     In some embodiments of the present invention, the distal end  130  of the hybrid dilator  100  may be curved as shown in  FIG.  1 A . Alternatively, the distal end  130  of the hybrid dilator may be straight. In some embodiments where the distal end  130  of the hybrid dilator  100  is curved, the hybrid dilator  100 , in combination with a puncturing device such as a needle, forms a trajectory that is substantially equivalent to the trajectory achieved by the combination of a sheath/dilator/needle assembly of a conventional transseptal kit to provide physicians with a predictable and repeatable path for completing a transseptal puncture. The curved distal end  130  facilitates advancement of the hybrid dilator  100  in conjunction with the puncturing device to initiate a transseptal puncture. 
     In some such embodiments, the hybrid dilator  100  comprises a shaft formed from distal tubing  121  that is sufficiently rigid to enable positioning of a crossing device such as a puncturing needle or a guidewire to be advanced through it while maintaining the position of the assembly at a desired site, such as a fossa of a septum. As such, the hybrid dilator  100  functions to provide support and columnar strength to facilitate placement of the crossing device at the desired location. As disclosed above and as shown in  FIGS.  1 A , distal tubing  121  tapers proximally from the distal tip  140  to a greater OD defining a dilating interface to allow dilation of the puncture site  510  ( FIG.  6 A ) to facilitate additional devices to be advanced there-through. 
     Distal Tip 
     More specifically, in some embodiments as shown in  FIG.  2 A , the distal tip  140  provides a lumen  142  that is appropriate for a crossing device such as a puncturing device to be inserted there-through and defines a relatively thin wall to facilitate controlled puncture. In some such examples, the puncturing device is a mechanical needle or an RF puncturing device that is usable with the hybrid dilator  100 . The hybrid dilator  100  provides a restricted distal internal diameter (as shown by ID 2  and ID 3 ) at the distal tip  140  to control the distance by which the puncture device such a transseptal needle (with a narrow distal portion) protrudes from the hybrid dilator  100 . The narrowest distal portion of a compatible puncturing device has an outer diameter less than ID 3  whereby it extends into and through length S 2  of lumen  142 , and beyond distal edge  148 , while, typically, a part of the puncturing device having an outer diameter greater than ID 3  and less than ID 2  will be seated in internal taper T 2 . Consequently, the dimension of length S 2  is significant in determining the distance the puncturing device protrudes from the hybrid dilator  1 . In some such embodiments, this allows the hybrid dilator  100  to meet the same standard as existing transseptal dilators in that it controls the distance by which a transseptal needle can protrude when fully inserted therein. Additionally, as described previously, the distal tip  140  provides an external taper T 3  that allows the dilator OD to transition from a narrow OD 2  at a distal most end or distal edge  148  of the distal tip  140 , to a wider OD 1  at its proximal edge  146 . In some such examples, the hybrid dilator  100  has smooth lines and a smooth external taper T 3  to facilitate a seamless transition across tissue. In some such examples, the hybrid dilator  100  functions to reduce the number of physical or geometric transitions or material transitions which can cause difficulties and/or create tactile obstructions hindering a physician&#39;s ability to complete a transseptal or other tissue crossing. 
     In typical examples, as shown in  FIGS.  1 A and  2 A , the dilator shaft includes a distal tubing  121  which, in some examples, comprises a high density polyethylene (HDPE) tubing. In some such embodiments, the HDPE has a hardness from about 55 shore D to about 70 shore D, and in a specific example, the HDPE hardness is about 67 shore D. In typical embodiments, the distal tubing  121  comprises material that meets the functional requirements of a transseptal sheath/dilator kit. In some such examples, the distal tubing  121  comprises a straight shaft that transitions into curved distal end  130 . The distal tip  140  comprises a tapered tip with a smooth external taper T 3 , having a taper angle TA of about 5.5°+/−1° degrees, and internal geometry which provides a controlled internal diameter (ID) to provide a predicable needle extension length. In some embodiments, the length of the external taper T 3  ranges from about 0.4 inches (1 cm) to about 1 inch (2.5 cm). In some such examples, the taper length for external taper T 3  is equal to about 0.646″ or about 1.6 cm. The distal tubing  121  has an inner diameter ID 1  that is equal to about 0.109″ (0.277 cm) and an outer diameter OD 1  that is equal to about 0.166″ (0.422 cm) along its proximal portion (or proximal length  123 ), which extends from the proximal hub  112  to adjacent the distal tip  140 , as shown in  FIG.  1 A . In the example shown in  FIG.  2 A , the inner diameter at the distal tip  140  tapers down along internal taper T 1  from ID 1  to a relatively smaller inner diameter ID 2 . In one such embodiment, the taper length for internal taper T 1  is equal to about 0.22″ (cm 0.56) and ID 2  extends for a distance S 1  for about 0.100″ (0.254 cm) and ID 2  has a value equal to about 0.056″ (0.142 cm). In some examples, the inner diameter then further transitions from ID 2  along an internal taper T 2  to an even smaller inner diameter ID 3 . In some embodiments, the distal portion of the distal tip (length S 2 ) has a length from about 0.71 cm to about 0.74 cm, and in some more specific embodiments, a length from about 0.721 cm to about 0.726 cm. In a specific instance, taper T 2  extends for a distance equal to about 0.044″ (0.112 cm), where the ID 3  is equal to about 0.034″ (0.086 cm) and extends for a length S 2  of about 0.285″ (0.724 cm). In some alternative embodiments, S 1  is equal to zero, whereby internal taper T 1  and internal taper T 2  are adjacent to each other to thereby provide a smooth transition of internal diameter. Some alternative embodiments include the dilator shaft substantially comprising a low density polyethylene or a polyether ether ketone, with some such embodiments of the dilator shaft having a hardness from about 40 shore D to about 85 shore D. 
     Some embodiments of the dilator shaft comprised of a relatively harder material (e.g. HDPE) have an inner diameter ID 1  of about 0.072 inches (0.18 cm) to about 0.11 inches (0.28 cm). Other embodiments of the dilator shaft comprised of a relatively softer material (e.g. polyurethanes, polyether block amide) have an inner diameter ID 1  of about 0.050 inches (0.13 cm) to about 0.11 inches (0.28 cm). Polyether block amide (PEBA) is a thermoplastic elastomer (TPE) and is known under the tradenames of VESTAMID® E (Evonik Industries) and Pebax® (Arkema). 
     In the example shown in  FIG.  2 A , having several internal transitions, such as internal taper T 1  and internal taper T 2 , ensures that the hybrid dilator has an OD along its proximal length (OD 1 ) that enables the hybrid dilator  100  to dilate a tissue puncture site to a desired extent, while at the same time allowing the wall thickness W p  of the distal tubing  121  to be maintained to provide shaft rigidity and stiffness that is comparable to a conventional sheath/dilator assembly. The internal geometry of distal tip  140 , including dual tapers T 1  and T 2  and the inner diameter along the distal tip  140 , provides for insertion of a puncturing device such as needle there-through and for the desired extension of a needle tip. The internal geometry also helps ensure that the wall thickness WTi p  ( FIG.  2 B ) at the distal edge  148  of the distal tip  140  is sufficiently thin to ensure crossing and trackability through the transseptal puncture site. Still furthermore, the dual tapers T 1  and T 2  ensure that a smooth transition is provided between the relatively wider inner diameter ID 1  along the proximal portion of distal tubing  121 , and the relatively narrower inner diameter ID 3  at the distal edge  148 . In some embodiments, the inner diameter ID 3  at distal edge  148  is about 0.033 inches (0.084 cm) to about 0.037 inches (0.094 cm) and the outer diameter at distal edge  148  is about 0.040 inches (0.10 cm) to about 0.055 inches (0.14 cm). In one specific example, the inner diameter ID 3  at the distal edge  148  is equal to about 0.034″ (0.086 cm) ( FIG.  2 B ) and the outer diameter OD 2  at the distal edge is equal to about 0.042″ (0.107 cm). 
     In some embodiments, the taper angle TA may range from about 5° to about 15°. In some examples, the taper length of external taper T 3  may range from about 1.0 cm to about 1.6 cm. In some embodiments, length of the external taper T 3  ranges from about 0.4 inches (1 cm) to about 1 inch (2.5 cm). In one example, the taper length of external taper T 3  may be about 1.0 cm with a taper angle TA of about 15°. In some embodiments, the wall thickness W Tip  at the distal edge  148  of the distal tip  140  is between about  4  thousandths of an inch (0.010 cm) to about 5 thousandths of an inch (0.013 cm). The wall thickness WTip is sufficient for maintaining mechanical integrity of the distal tip  140  while ensuring that it is not too thick to make it difficult for the distal tip  140  to cross a puncture site within the tissue. 
     In an alternative embodiment of the present invention, as shown in  FIG.  2 C , a distal tip  140  may be provided with a single internal taper T 1  as shown. As shown, the distal tubing  121  is shown with inner lumen visible. 
     Wall Thickness, Bending Stiffness and Torque 
     As discussed earlier with respect to  FIG.  2 A , the hybrid dilator  100  is an HDPE Dilator with a 12.5 French OD with an 8.5 French ID. The ID and OD are representative of the dimensions along the proximal length  123  of the distal tubing  121 . Additionally, the wall thickness W p  along the proximal length  123  is about 25.5 thousandths of an inch (0.065 cm) to about 27.5 thousandths of an inch (0.070 cm). Bending stiffness for the illustrated example is about 3 N/mm and the torque is about 4.5 N cm. 
     In an alternative embodiment the hybrid dilator is a 12.5 French OD dilator with an 8.5 French ID. The wall thickness Wp along the proximal length  123  of the distal tubing  121  is about 32 thousandths of an inch (0.081 cm). Bending stiffness for the particular example is about 4 N/mm and the torque is about 5 N cm. 
     In still a further alternative, the hybrid dilator  100  is a 12.5 French OD dilator with a 4.5 French ID. The wall thickness Wp along the proximal length  123  of the distal tubing  121  is about 55 thousandths of an inch (0.140 cm). Bending stiffness for the particular example is about 5.5 N/mm and the torque is about 7 N cm. In another example, the hybrid dilator is a 15 French dilator where the wall thickness is less than about 26.5 thousandths of an inch (0.067 cm) to provide adequate stiffness. 
     In some embodiments, a HDPE hybrid dilator  100  has: a 12.5 French OD which is about 0.162-0.166″ (0.411-0.422 cm); a 4.5-8.5 French ID (about 0.056-0.115 inches or about 0.142-0.292 cm); a wall thickness from about 0.025″ to about 0.055″ (about 0.064-0.140 cm), a stiffness of about 3.5 to 5.5 N/mm, and a torque transmission from about 4 to about 7 N cm. 
     In an alternative embodiment, the dilator shaft is comprised substantially of HDPE and includes: a 12.5 French OD (about 0.162″-0.166″ or about 0.411-0.422 cm); an 8.5 French ID (about 0.108″-0.115″ or about 0.274-0.2921 cm); a wall thickness from about 23.5 thousandths of an inch (0.06 cm) to about 29 thousandths of an inch (0.074 cm). Such embodiments may have a bending stiffness from about 2.5 to 3.5 N/mm and a torque transmission from about 4 to 4.5 N cm. 
     In another alternative embodiment, the dilator shaft is HDPE and has: a 12.5 French OD (about 0.162″-0.166″ or about 0.411-0.422 cm); a 7.5 French ID (about 0.095″-0.102″ or about 0.241-0.259 cm); and a wall thickness which is about 0.03-0.036″ (about 0.076-0.091 cm). Bending stiffness for such examples is about 3.5 to 4.5 N/mm and the torque transmission is about 4.5 to 5.5 N cm. In some specific embodiments, the wall thickness is about 32 thousandths of an inch (0.081 cm). 
     Another alternative embodiment includes the dilator shaft being comprised of HDPE and the shaft having: a 12.5 French OD (about 0.162″-0.166″ or about 0.411-0.422 cm); a 4.5 French ID (about 0.056″-0.063″ or about 0.142-0.160 cm); and a wall thickness of about 0.05-0.055″ (0.127-0.140 cm). Typically, bending stiffness for such embodiments is from about 5 to 6 N/mm and the torque is about 6 N cm to 7 N cm. In some specific embodiments, the wall thickness is about 55 thousandths of an inch (0.140 cm). 
     In an alternate embodiment, the dilator shaft has an outer diameter between 12 French (about 0.162″-0.166″ or about 0.411-0.422 cm) and 18 French (about 0.236″ or about 0.599cm). In some embodiments, the inner diameter is configured to accommodate a needle such a mechanical needle or an RF needle. In some alternate embodiments, the inner diameter is configured to accommodate a wire such as an RF wire. Additionally, the inner diameter of the dilator shaft may be modified to adjust the mechanical properties of the dilator shaft. For example, a dilator shaft with an outer diameter of 18 French may have an enlarged inner diameter to reduce the wall thickness of the dilator shaft and thereby reduce the stiffness. In another embodiment, the material of the dilator shaft is adjusted to achieve the desired mechanical properties. 
     In some embodiments of the present invention Torque may range from about 1.0 N cm to about 7 N cm over a length of about 50 cm. In some examples the bending stiffness ranges from about 1.0 N/mm. to about 5.5 N/mm over a span of 50 mm. 
     Surface Finish 
     In some embodiments of the present invention, the distal tubing  121  may comprise different surface finishes to provide various amounts of friction along the exterior surface. In some embodiments, as above the distal tubing  121  may be formed substantially of HDPE. Alternatively, the dilator may be formed from multiple material layers or a composite material. In some such examples, the multiple layers may extend concentrically and longitudinally along the length of the distal tubing  121  in the form of multiple tubular layers. In one such example the inner layer or tubing comprises an HDPE or a low density polyethylene (LDPE) core with an outer layer of Pebax (polyether block amide) extrusion. This may provide a relatively smoother exterior finish compared to HDPE. Furthermore, the Pebax tubing allows for silicone coating to be disposed thereon to additionally provide a smooth coating on the exterior. 
     Alternate Embodiments of the Distal Tip 
     In an alternate embodiment of the present invention, as shown in  FIGS.  3 A to  3 D , the distal tip  140  comprises a modified taper. In one specific example as shown in  FIGS.  3 A and  3 B , the tapered distal tip  140  may comprise a secondary feature such as a secondary surface modification  147  that creates a surface variation, such as a secondary bump  147   a  or a divot  147   b  to more closely create the tactile queues of a standard sheath/dilator transseptal kit. The first tactile cue comes from a first/primary feature such as a first surface modification  145 , which may be a first bump  145   a  that is represented by the transition between the tapered tip  140  and the proximal length  123  of the distal tubing  121 . As above, the second tactile cue comes from the secondary surface modification  147 , for example the secondary bump  147   a  or divot  147 b. 
     Alternatively, as shown in  FIG.  3 C , the tapered distal tip  140  may comprise a smooth single external taper T 3  with a single surface modification such as a first surface modification  145  in the form of a first bump  145   a  at the transition, as described previously. In a further alternative, there may be two or more external tapers along the exterior. In a specific example, the distal tip  140  may have two external tapers: external taper T 4  and external taper T 5  as shown in  FIG.  3 D , where the first surface modification  145  and secondary surface modification  147  are formed by transitions that form first bump  145   a  and second bump  145   b . These provide tactile cues during use as the hybrid dilator  100  is being advanced through, for example, the septum. The tactile cues mimic the cues that are generally obtained from transitions in a standard transseptal kit that includes a standard dilator and sheath assembly while still providing a smooth transition such that the device does not get stuck at the tissue boundary. In some such examples, the internal taper may be as shown in  FIG.  2 A  comprising internal tapers T 1  and T 2 . 
     Alternatives 
     In alternative embodiments of the present invention, the distal tip  140  may have a modified external taper T 3 . In some such examples, the geometry of the external taper T 3  may be varied. As outlined previously, the distal tip  140  may have surface modifications along the external taper T 3 . The external taper T 3  may be provided with a secondary bump  147   a , the external taper T 3  may be provided with divot  147   b . Alternatively, the external taper T 3  may be provided with a modified roughness. 
     In alternative embodiments, the ID of the distal tip  140 , including internal taper(s), is modified in order to accommodate a crossing/puncturing device such as a needle (for example an RF needle). Alternatively, internal geometry may be modified in order to accommodate a crossing/puncturing device such as a guide wire (for example an RF guidewire). In some embodiments, the shaft distal tubing  121  comprises a single material. Alternatively, the shaft distal tubing  121  may comprise a composite material via co-extrusion or post extrusion processing/layering. In some examples, the shaft distal tubing  121  comprises a lubricious coating material along the exterior. In some such examples, the chemistry and/or processing of the lubricious coating material is varied to provide a suitable coating. In some embodiments, material may be used within the distal tubing  121 , and for coating, in accordance with what is known in the art. In a further alternative of the present invention, the hybrid dilator  100  may be provided with forward facing ports along, the distal tip  140 , to allow for fluid injection when a needle or a guidewire is positioned inside the hybrid dilator  100 . 
     In some embodiments of the present invention the hybrid dilator  100  has been created to optimize the tubing stiffness/torque response. Also, the handle/hub  112  provides enhanced handing features (discussed further herein below). In some embodiments, as shown previously, the distal tip  140  is provided with two external distal tapers. In some embodiments, the internal controlled geometry may be provided in varying configurations. 
       FIG.  8    is a cross sectional view of the shaft and distal tip of a hybrid dilator of an alternative embodiment of the present invention and  FIG.  9    is an enlarged view of the distal tip of  FIG.  8   , wherein the dilator shaft has more than one layer and the tip is typically comprised of the same material as one of the shaft layers. 
     Hybrid dilator  700  of  FIG.  8    has a shaft  702  which includes three layers, inner layer  706 , outer layer  708 , and a middle layer, torque layer  704 , to improve the torqueability of the device. There is a smooth joint between device tip  720  and a shaft  702 . Inner layer  706  is typically comprised of HDPE and outer layer  708  typically of Pebax or LDPE. Typical embodiments of shaft  702  provide a mechanical response that is similar to transseptal sheath and dilator sets that physicians commonly currently use. The durometer of the Pebax may be selected to adjust the flexibility and pushability of the shaft. The torque layer is typically a braided material, while in alternative embodiments the torque layer may be a stiff polymer and/or a metallic hypotube. Some further embodiments of shaft  702  do not include torque layer  704 . While outer layer  708  is typically comprised of Pebax or LDPE, in some alternative embodiments it is made of HDPE or other density blends of polyethylene that achieve the desired properties of flexibility and torque, all of which are compatible with lubricious coatings. Typical embodiments of shaft  702  have an outer diameter at least the size of current transseptal sheaths (approximately 0.144″ (0.366 cm)) to dilate the septum to at least the same size as current sheaths, and have a mechanical response (including flexibility, pushability, and torqueability) comparable to current transseptal sheath and dilator pairings. Some embodiments of shaft  702  have a 12.5 F outer diameter of about 0.163″ (0.414 cm) to about 0.166″ (0.421 cm). Other embodiments of shaft  702  have a 15 F outer diameter of about 0.193″ (0.490 cm) to about 0.205″ (0.521 cm). Some embodiments of shaft  702  which have the torque layer  704  have a torque transmission from about 4 N cm to about 8 N cm, with one specific embodiment having a torque transmission of about 8.1 N cm. 
     In embodiments which include a torque layer  704  between the inner and outer materials (For example HDPE and Pebax), the braid normally functions as an anchor between the inner and outer layers. Such embodiments may be manufactured using a reflow process which melts both the inner and outer layers into the braided layer whereby the braided layer mechanically joins the two materials together. Some such embodiments have a stainless steel braid and provide 8 N cm of torque transmission. 
       FIG.  9    illustrates an embodiment of tip  720  typically comprised of HDPE with from about 20 percent to 50 percent of the distal tip being comprised of BaSO 4  to facilitate imaging, but alternatively may be comprised of Pebax or any thermoplastic. In some embodiments, tip  720  is comprised of about 40% BaSO4. In testing, HDPE has displayed the advantageous characteristic of being stiff enough to be skive resistant. Tip  720  of  FIG.  9    includes internal lumen  724 , distal edge  722 , and a single external taper T 3  for smooth dilation. Internal taper T 1  and internal taper T 2  guide devices (e.g. guidewires, needles) from the shaft into the tip area, and limits needle protrusion (of compatible needles) out of the end of the dilator. The illustrated example includes two distal side holes  726  for limiting vacuum and pressure formation when withdrawing devices, while alternative examples include different size, location, number of holes, and configuration of holes. In other embodiments an alternate radiopacifier is embedded in the polymer material such as BiOCL. In some embodiments, the BiOCL is &lt;25%. In another embodiment, a change in radiopaque materials is used to visualize the distal tip  1004 . Other embodiments of tip  720  include radiopaque features such as bands and coils made from radiopaque materials (e.g. platinum, gold, tungsten, and/or barium sulfate-filled polymer). 
     Making further reference to  FIG.  9   , the inner diameter of tip  720  varies from the shaft ID to a smaller diameter compatible with commonly used 0.032″ (0.081 cm) or 0.035″ (0.089 cm) devices (e.g. guidewires and needles). The length of the external taper T 3  is typically more than 1.0 cm long since a shorter length increases the crossing force or may make crossing tissue more abrupt, with some examples of tip  720  having a taper length T 3  up to  3  cm in length. In some embodiments, the external taper length of the external taper T 3  ranges from about 0.4″ (1 cm) to about 1″ (2.5 cm). The outer diameter of tip  720  is typically no greater than 0.055″ (0.140 cm) or else the force in advancing through tissue would be larger than typical transseptal dilators. As an example, if the device is 0.032″ (0.081 cm) compatible and has an ID of approximately 0.034″ (0.086 cm), restraining the tip OD to a maximum of 0.054″ (0.137 cm) facilitates smooth advancement through tissue. 
     In a specific embodiment of the hybrid dilator  700  shown in  FIGS.  8  and  9   , shaft  702  has an outer diameter of 0.164 inches (0.417 cm) and an inner diameter of 0.072 inches (0.183 cm), the inner diameter of tip  720  at distal edge  722  is compatible with device having outer diameters of 0.032 inches (0.081 cm) or 0.035 inches (0.089 cm), the maximum tip OD is less than 0.055 inches (0.140 cm), the two side holes  726  have diameters of about 0.012 inches (0.030 cm) to about 0.024 inches (0.061 cm), and external taper T 3  has a length of 1.6 cm. Typical dilators have a taper length of approximately 1 cm and a smaller diameter than the illustrated embodiment. To prevent hybrid dilator  700  from having a higher taper angle than typical dilators (which results in a higher crossing force), hybrid dilator has an external taper T 3  with a length of 1.6 cm which corresponds with its relatively larger outer diameter. In some embodiments, the inner diameter of tip  720  at distal edge  722  is about 0.033 inches (0.084 cm) to about 0.037 inches (0.094 cm) and the outer diameter of tip  720  at distal edge  722  is about 0.040 inches (0.10 cm) to about 0.055 inches (0.14 cm). 
     Further alternative embodiments of hybrid dilator  700  include outer layer  708  of shaft  702  being made of thermoplastic to facilitate manufacturing. Some examples have only one internal lumen taper or more than two. Some further embodiments include an electrode configured for puncturing at the tip so that the one device can puncture, cross, and dilate. 
     Some embodiments include the shaft having an inner layer  706  made of HDPE and an outer layer  708  made of Pebax, wherein, during manufacture of the device, tip  720  and inner layer  706  are formed in the same extrusion of HDPE whereby tip  720  and inner layer  706  are continuous without any internal joint, which eliminates the risk of a sharp needle being advanced through the dilator catching at a joint between the dilator shaft  702  and tip  720 . 
     Proximal Hub 
     The hybrid dilator  100  comprises a handle defined by a hybrid or combination proximal hub  112  at a proximal end thereof, as additionally shown in  FIG.  4 A . The proximal hub  112  comprises dilator hub  114  that is formed integrally with a sheath hub or a sheath-like hub  116 .  FIG.  4 A  also includes a prior art dilator  650  inserted into sheath  660  such as to show a dilator hub  652  and a sheath hub  662  proximally, and dilator  650  extending out of sheath  660  distally. Sheath  660  and dilator  650  are being advanced across a septum  505  but the heart tissue is catching on sheath  660 . In contrast, hybrid dilator  100  which is being advanced across septum  505  without snagging. In some embodiments as shown in  FIGS.  4 B- 4 C and  4 F , the dilator hub  114  comprises a Luer hub or Luer connector  115  and the sheath hub  116  comprises an arm  117  that functions as pseudo side-port that provides the functional feel of a side-port to provide an indication/direction of the distal end curvature. The arm  117  mimics the side-port of a standard sheath without providing the fluid capability of a standard sheath side-port. The proximal hub  112  forms a hub/handle that is larger than a standard transseptal dilator hub so as to provide the physician with similar handling and expected tactile feedback, by featuring additional material to hold onto and additionally provides the arm  117  to indicate the direction of the distal end curvature. In some examples, the arm  117  may be replaced by functional side-port if the fluid capability is desired. In one specific example, the proximal hub  112  comprises a custom insert molded HDPE Hub at the proximal end with a luer connector  115  and tactile features (defined by a side-port arm  117 ) to indicate the plane of distal curvature and provide similar handling characteristics. In some such examples, the proximal end  110  has a luer taper to allow for connection of medical syringes or fluid drips.  FIG.  4 D  illustrates an end view taken from a distal end of the proximal hub  112  showing a coupling  119  of the proximal hub  112  for connecting the proximal hub  112  to the distal tubing  121 . In some such examples the coupling  119  may comprise a strain relief.  FIGS.  4 E and  4 G  show cross-sectional views of the proximal hub  112  illustrating the internal configuration of the proximal hub  112 , which may include features for facilitating entry of other devices therein during use. In some such examples, the proximal hub  112  comprises HDPE. 
     Proximal hub  112 , as illustrated in  FIG.  4 E , includes an outer diameter OD 3  of 5.25 mm at its distal end, an internal angle IA of 40.0 degrees, and a proximal angle PA of 6.0 degrees. Proximal hub  112 , as illustrated in  FIG.  4 F , the proximal column has an outer diameter OD 5  of 6 mm and an outer diameter of OD 4  of 7.37 mm at the Luer connector at its proximal end. The distance D 1  between arm endpoint  117   a  and opposing point  117   b  is 28.39 mm, and the distance D 2  between opposing point  117   b  and the central longitudinal axis of proximal hub  112  is 6.49 mm. Proximal hub  112 , as illustrated in  FIG.  4   g   , has an inner diameter ID 5  of 4.25 mm internal to the hub proximal end  113   a , an inner diameter ID 6  of 3 mm at the innermost portion of the lumen, an inner diameter ID 7  at the narrowest portion of the lumen, and an inner diameter ID 8  of 4.12 mm at the hub distal end  113   b  of the hub. Other hub dimensions shown in  FIG.  4 G  include: hub location H 1  (at the distal end of the proximal internal taper) is 12.40 mm from hub proximal end  113   a , hub location H 2  (at the proximal end of the distal internal taper) is 31.83 mm from hub proximal end  113   a , hub location H 3  (at the distal end of the distal internal taper) is 33.75 mm from hub proximal end  113   a , and hub location H 4  (at the distal end of narrowest portion of the lumen) is 35 mm from hub proximal end  113   a.    
     Alternate Embodiments of the Proximal Hub 
     In some embodiments as shown in  FIGS.  5 A- 5 D , an alternate embodiment of a hybrid dilator  200  is provided with a modified proximal portion  210 . The hybrid dilator  200  comprises a valved proximal hub  212 , as shown in  FIGS.  5 A- 5 B , where the hub comprises a valve  213  at its proximal end with a cap  220  for retaining the valve in position. The valve  213  is provided as a hemostasis valve. In some examples, as shown in  FIG.  5 B , the valved proximal hub  212  may additionally comprise an extra feature to direct devices into the valve  213 . In some embodiments the proximal hub  212  has an insertion guide  218  as a molded or an external feature that function co-operatively with the valve to direct and align product being inserted into the valve  213 . In the particular example shown, the insertion guide  218  is provided proximal of the valve  213 . 
     In accordance with another embodiment of the present invention, a feature is provided within the valved proximal hub  212  to funnel device into the shaft tubing. In a particular case, a funnel guide  222  is provided to direct and align product inserted into valve  213  into the shaft tubing. The funnel guide is positioned distal of the valve  213 . In some such examples, the funnel guide  222  is provided as a molded feature. In some embodiments, funnel guide  222  is configured such that it also centers the proximal end of the guidewire with respect to the valve. This centering directs the proximal end of the guidewire when it is inserted through the device&#39;s distal tip for the purpose of device exchange. 
     In a further alternative, as shown in  FIG.  5 D , a hybrid dilator  200 , is provided with a proximal hub  212  that houses a valve  213 , for example a hemostasis valve, and additionally comprises a side-port port  217  that has a side-port tubing  219  attached thereto, with a stopcock  228  to provide for flushing and aspiration. 
     In alternate embodiments of the present invention, the proximal hub  212  may comprise material that is taken from the group consisting of Pebax, HDPE, LDPE, and Nylon or a combination thereof to achieve desired lubricity and handling characteristics. 
     In still a further alternative, a proximal hub  112  is shown in  FIG.  5 E , that comprises a Luer connector  115  according to ISO  594 - 1 ,- 2 . Additionally, an arm  117  is provided in the form of a mock side-port to provide expected handling and align with the distal curve. Additionally, the proximal hub  112  is provided with a strain relief  119   b  at its distal end and the distal tubing  121  extends in a distal direction out of strain relief  119   b.    
     Alternatives 
     In some embodiments of the present invention, the proximal hub  112  or valved proximal hub  212  may comprise a molded hub. In some embodiments, the proximal hub  112  or valved proximal hub  212  may comprise HDPE. Alternatively, other materials may be used. In some embodiments, the geometry of the hub may be varied as may be suitable. In alternative embodiments of the valved proximal hub  212 , the valve material and/or geometry may be varied as may be known in the art. In some such examples, the slit configuration and/or size may be varied to provide a suitable valve to meet the requirements of the procedure, such as a transseptal procedure. In still further alternatives, the material of the side-port tubing, and the ID and OD of side-port tubing may be selected and/or varied as may be known to a person skilled in the art. Similarly, in some examples, as shown in  FIG.  5 D  where a stopcock is provided, the stopcock material may be varied as may be known in the art. 
     In still a further alternative of the present invention, some embodiments of a hybrid dilator of the present invention may provide the simplicity of transseptal crossing, and yet may still allow an ablation catheter to be used with it in case the need arises. 
     Another aspect of the invention is a kit for puncturing a tissue comprising: a crossing device having a puncturing feature; and a hybrid dilator  100 , wherein the dilator has a dilator shaft defining a lumen  122  for receiving the crossing device therethrough, the dilator shaft being structured to provide support for the crossing device when the crossing device is used to create a puncture in a tissue. The hybrid dilator also includes a distal tip  140  having an outer diameter which substantially tapers down to an outer diameter of the crossing device for cooperatively providing a smooth profile when the hybrid dilator  100  is advanced through a tissue over the crossing device. In some embodiments of the kit, the crossing device is a mechanical needle with a sharp tip, while in some other embodiments, the crossing device is configured for delivering energy to a tissue. 
     Another aspect of the invention is a system for puncturing a tissue comprising: a crossing device having a puncturing feature which is operable to deliver energy to a tissue; an electrosurgical generator which is operable to provide energy to the puncturing feature; and a hybrid dilator  100 , wherein the hybrid dilator has a dilator shaft defining a lumen  122  for receiving the crossing device therethrough, the dilator shaft being structured to provide support for the crossing device when the crossing device is used to create a puncture in a tissue. The hybrid dilator also includes a distal tip  140  having an outer diameter which substantially tapers down to an outer diameter of the crossing device for cooperatively providing a smooth profile when the hybrid dilator is advanced through a tissue over the crossing device. 
     Methods of Performing a Transseptal Procedure Using a Hybrid Dilator, Guidewire And Crossing Device 
     In accordance with the present invention, a method of the present invention provides for streamlining the procedural workflow by providing a hybrid dilator that combines the functionalities of a conventional transseptal sheath and dilator assembly. With the hybrid dilator of the present invention a reduced number of devices may be required in order to complete the transseptal procedure, which enhances procedural efficiency while reducing procedural time and complexity. 
     In such example, a method of the present invention avoids the disadvantages associated with a conventional transseptal procedure.  FIGS.  6 A and  6 B  illustrate an example of method of performing such a conventional transseptal medical procedure  300 . The method comprises the steps of: at step  310 , gaining access into the right atrium  501  via vasculature using a guidewire; at step  320 , advancing a sheath  20  and dilator  40  over the guidewire into the right atrium  501 , the sheath  20  and dilator  40  forming a sheath and dilator assembly  50 ; at step  330 , exchanging the guidewire for a crossing device  60  which comprises a puncturing device  62 ; at step  340 , advancing the crossing device  60  along with the dilator across a septum  505  to create a transseptal puncture site  510  and dilate the transseptal puncture site. At step  340 , the sheath  20  may get hung up at the sheath/dilator interface and the transition between the sheath/dilator can affect a physician&#39;s ability to cross tissue in a predictable, repeatable fashion. Sometimes the physician may not able to cross through to the sheath (get the sheath across the septal puncture site because the tissue will get hung up at the sheath/dilator interface). If at step  350 , the physician is successful, the physician may be able to advance the sheath and dilator assembly  50  and the crossing device  60  through the transseptal puncture site  510  to enable the sheath and dilator transition to cross the puncture site  510 . In some such procedures, the physician may wish to use a relatively large delivery sheath (for example which is larger than the transseptal sheath  20 ) for complex procedures for example for cryoablation procedures or a left atrial appendage closure/occlusion procedure and knows they cannot cross with the large delivery sheath, so the physician will introduce a standard transseptal kit with the sheath and dilator as discussed at step  350  above to purely to cross and pre-dilate the septum. Once this three piece kit is removed for exchange, it must be disposed, thereby underutilizing the three items (sheath, dilator, guidewire) for only a short procedural presence. The removal of the sheath/dilator assembly and exchange with the larger delivery sheath is described further below. At step  360  of the method, the crossing device  60  is exchanged with a guidewire  80 , which comprises the steps of removing the crossing device  60  and advancing the guidewire  80  into the left atrium  502 ; at step  370 , removing the sheath and dilator assembly  50 ; and at step  380 , advancing one or more secondary devices  70  such as a relatively large delivery sheath over the guidewire  80  into the left atrium  502  to complete the desired procedure. 
     As outlined herein above, embodiments of the present invention provide an optimized transseptal procedure In accordance with a method of the present invention, as shown in  FIGS.  7 A and  7 B , an optimized method  400  is provided for carrying out a transseptal procedure. The method comprises the steps of: at step  410 , gaining access into the right atrium via vasculature using a guidewire; and at step  420 , advancing a hybrid dilator  100  having a supporting shaft/column over the guidewire into the right atrium  501 ; By using the hybrid dilator  100  it reduces number of parts that the physician is required to prep/assemble and introduce into the patient from three to two. Instead of a sheath, dilator and guidewire, a hybrid dilator  100  and guidewire may be used. The method additionally provides: at step  430 , exchanging the guidewire for a crossing device  60  which comprises a puncturing device  62  [In some embodiments of the present invention, the puncturing device  62  may comprise a needle. In some such examples, the needle is a radiofrequency (RF) needle. Alternatively the needle may comprise a mechanical needle. In other embodiments of the present invention, the puncturing device  62  may comprise a radiofrequency (RF) guidewire]; and at step  440  advancing the crossing device and the hybrid dilator across the septum  505  to create a transseptal puncture site  510  and dilate the puncture site  510  to facilitate advancement of one or more secondary devices  70  through the transseptal puncture site. The hybrid dilator  100 , which may also be referred to as the step-up dilator, is provided as a simplified tool. It simplifies the procedural workflow by providing a one piece transseptal tool compared to a sheath and dilator (it is additionally usable with a guidewire and needle as shown). The hybrid dilator  100  is provided as a one/single oversized dilator and in use it reduces the number of physical/geometric transitions as well as the number of material transitions or tactile obstructions which may allow the physicians to complete a transseptal or other tissue crossings with greater ease. The hybrid dilator  100  reduces the changes of the hybrid dilator  100  from getting caught at the transseptal puncture site, by provided smooth lines and tapers to facilitate a seamless transition across tissue. This allows the hybrid dilator  100  to be advanced across the septum with greater ease. The method additionally provides for; at step  450 , exchanging the crossing device  60  with a guidewire  80  and advancing the guidewire  80  into the left atrium; at step  360 , removing the hybrid dilator  100 ; and at step  470 , advancing the one or more secondary devices over the guidewire  80  into the left atrium  502  to complete the desired procedure. 
     In procedures where the physician wishes to use a relatively large delivery sheath for complex procedures (for example for cryoablation or LAA occlusion) and knows they cannot cross with that product, the physician can now introduce just the hybrid dilator  100  over a guidewire as discussed in step  420  (as depicted in  FIG.  7 B ) using a single device to cross and pre-dilate the septum. The hybrid dilator  100  and the initial guidewire may then be removed for exchange, thus using only two products (hybrid dilator  100  and guidewire, instead of a standard sheath, dilator and guidewire kit). As such the improved method additionally provides at steps  460  and  470  removing just the hybrid dilator  100  to allow exchange with the secondary device such as a relatively large delivery sheath for complex procedures, wasting fewer products in the process. 
     Another embodiment of the method uses a hybrid dilator  100  and a crossing device for puncturing a septum  505  of a heart. This embodiment of the method comprises the steps of: a) positioning a distal tip  140  of the hybrid dilator at a desired site of the septum; b) using the hybrid dilator  100  for supporting a crossing device, located within a lumen of the hybrid dilator, as the crossing device is advanced beyond the distal tip of the hybrid dilator to puncture the septum; and c) advancing the hybrid dilator over the crossing device thereby dilating the desired site. In some such embodiments, the crossing device is a mechanical needle and step (b) further includes applying force with the mechanical needle to the septum to thereby puncture the septum. In other embodiments, the crossing device is configured for delivering energy, and step (b) further includes supplying electrical energy to the crossing device to thereby puncture the septum. Some embodiments further comprise a step (d) of exchanging the crossing device with a guidewire and advancing the guidewire into a left atrium, a step (e) of removing the hybrid dilator, and a step (f) of advancing one or more secondary devices over the guidewire into the left atrium. 
     In some embodiments of using a hybrid dilator and a crossing device for puncturing a septum of a heart wherein the crossing device is configured for delivering energy, the crossing device is further configured for use as a guide-wire, and the method further comprises a step (d) of removing the hybrid dilator, and typically, a step (e) of advancing one or more secondary devices over the crossing device into a left atrium. Further details of crossing devices suitable for delivering energy and using as a guide-wire are given in International Publication No. WO2015019132, entitled “METHODS AND DEVICES FOR PUNCTURING TISSUE”, which is hereby incorporated-by-reference in its entirety. 
     Hybrid Dilator and Method of Use 
     In accordance with an embodiment of the present invention, a hybrid dilator  2000  is shown in  FIGS.  22 A- 22 D . The hybrid dilator  2000  comprises a combination of features that provide a dual functionality of a sheath and a dilator for facilitating a transseptal puncture procedure while avoiding disadvantages of conventional sheath and dilator assemblies. The hybrid dilator  2000  functions as a single device that removes the need for using a conventional sheath/dilator assembly resulting in less waste and a simplified workflow. The hybrid dilator  2000  comprises a sheath-like handle with familiar torque and tactile control. In the specific example shown, the hybrid dilator  2000  defines a proximal portion  2110  comprising a molded combination proximal hub  2112  as shown in  FIG.  22 A . A distal portion  2120  is coupled to the proximal portion  2110  comprising a dilator shaft. The dilator shaft extends from the proximal end and defines a curved distal end  2130  that terminates in a distal tip  2140 . The hybrid dilator  2000  comprises a lumen  2122  there-through that narrows at the distal tip  2140 . 
     The dilator shaft is shown in  FIGS.  22 C and  22 D . The hybrid dilator  2000  is a single unitary device and the dilator shaft provides mechanical properties to best facilitate procedural activities. The hybrid dilator  2000  is sufficiently rigid to enable positioning and advancement of a crossing device, such as a puncturing needle or wire, within the hybrid dilator  2000  while maintaining the position of the assembly at a desired site. As such, the hybrid dilator  2000  functions to provide support and columnar strength to facilitate placement of the crossing device at the desired location. 
     As shown in  FIG.  22 A , in some embodiments of the present invention, the distal end  2130  of the hybrid dilator  2000  may be curved. Alternatively, the distal end  2130  of the hybrid dilator  2000  may be straight. The curved distal end  2130  facilitates advancement of the hybrid dilator  2000  in conjunction with the puncturing device to initiate a transseptal puncture. 
       FIG.  22 D  shows a cut-away view of the hybrid dilator&#39;s  2000  shaft  2002 . The hybrid dilator  2000  has a shaft  2002  which includes three layers, an inner layer  2006 , an outer layer  2008 , and a middle torque layer  2004 . The torque layer  2004  improves the torquability of the device. The inner layer  2006  is comprised of HDPE and the outer layer  2008  is comprised of LDPE. The torque layer  2004  is a braided material comprised of stainless steel. The braid functions as an anchor between the inner and outer layers. Such embodiments may be manufactured using a reflow process which melts both the inner and outer layers into the braided layer whereby the braided layer mechanically joins the two materials together. Some embodiments of shaft  2002  having torque layer  2006  have a torque transmission from about 2 N cm to about 8 N cm. In some specific embodiments, the torque transmission is from about 2 N cm to about 6 N cm. In one specific embodiment, the shaft  2002  has a torque transmission of about 4 N cm. In an alternate embodiment, the shaft  2002  has a torque transmission of about 8 N cm. In some embodiments, an outer coating  2010  is disposed on the outer surface  2008  to provide a smooth coating on the exterior. In one embodiment, the outer coating  2010  is a silicone coating. 
     Hybrid dilator  2000  comprises a smooth joint between the shaft  2002  and the device tip  2140 . The distal tip  2140  of the hybrid dilator  2000 , as illustrated in  FIG.  23 B , transitions through a smooth external taper. The taper allows dilation of the septum to an appropriate size for the subsequent delivery device or equipment that may be used. The outer diameter of the hybrid dilator  2000  is substantially constant from the proximal edge of distal tip  2140  to the proximal hub  2112 . In some such embodiments, the outer diameter of the hybrid dilator  100  may vary based on the application and clinical use. In some embodiments, the size of hybrid dilator  2000  is from about 12 French to about 20 French. In a specific example, the hybrid dilator has the size about 12.5 French (outer diameter of about 0.163″ (0.414 cm) to about 0.166″ (0.421 cm)). In the embodiment of  FIG.  23 B , the taper of the distal tip  2140  has an external taper length of 0.63″ (1.6 cm). The outer diameter of the distal end of the tapered distal tip  2140  is a dimeter of 0.055″ (0.14 cm). 
       FIGS.  24 A- 24 C  show an alternate embodiment of the distal tip  2140  of the hybrid dilator  2000 . In this embodiment, the distal tip  2140  comprises a radiopaque marker  2050 . In the embodiment of  FIG.  24    B, the radiopaque marker  2050  is a marker coil. In addition to being radiopaque, the marker coil  2050  is an echogenic marker and is visible under ultrasound. In one embodiment, the marker coil is from about 0.04″ (1 mm) to about 0.08″ (2 mm) in length. In a specific embodiment, the marker coil is about 0.063″ (1.6 mm) in length, has a 0.053″ (1.35 mm) outer diameter and a 0.004″ (0.1 mm) coil diameter. In some embodiments, the marker coil is placed from about 0.04″ (1 mm) to about 0.1″ (2.5 mm) from the distal edge of the distal tip  2140 . The distance between the distal edge and the radiopaque marker  2050  provide optimal visibility under ultrasound or fluoroscopy and maintain visibility of the crossing device&#39;s distal tip while inside the hybrid dilator  2000 . In some embodiments, the distal tip  2140  comprises an additional radiopacifier embedded in the polymer material such as BiOCL. In one embodiment, the distal tip  2140  is comprised of 15% BiOCL. 
     The hub  2112  of the hybrid dilator  2000  is shown in  FIG.  25   . The hub  2112  comprises a Luer hub or Luer connector  2115  and an arm  2117  to provide an indication/direction of the distal end curvature. The proximal hub  112  forms a hub/handle that is larger than a standard transseptal dilator hub so as to provide the physician with similar handling and expected tactile feedback of the combination of a dilator hub and a sheath hub, by featuring additional material to hold onto and additionally provides the arm  117  to indicate the direction of the distal end curvature. In a specific example, the proximal hub  2112  comprises a custom insert molded HDPE Hub at the proximal end with a Luer connector  2115  and arm  2117  to indicate the place of distal curvature. In some such examples, the proximal end has a Luer taper to allow for connection of medical syringes, pressure measurements, or fluid drips. The hub  2112  as illustrated in  FIG.  25    comprises and outer diameter of 6.123 mm at the Luer connector at its proximal end. The proximal hub  2112  has an internal angle IA of 40.0 degrees. 
     An example of an optimized transseptal workflow with the use of the hybrid dilator  2000  is illustrated in  FIG.  30   . The method comprises the steps of: at step  2210 , gaining access into the right atrium via vasculature using a guidewire; and at step  2220 , advancing a hybrid dilator  2000  over the guidewire into the right atrium. By using the hybrid dilator  2000 , it reduces the number of parts that the physician is required to prep/assemble and introduce into the patient. Instead of a sheath, dilator and guidewire, a hybrid dilator  2000  and guidewire may be used. This eliminates the need to separately exchange the sheath and dilator. The method additionally provides: at step  2230 , exchanging the guidewire for a crossing device such as a mechanical needle or an RF needle and step  2240  determining if the distal tip of the hybrid dilator is positioned on the target site. The position of the distal tip  2140  of the hybrid dilator  2000  may be determined using various visualization methods such as fluoroscopy, electro-anatomical mapping (EAM), or echogenic markers. The hybrid dilator  2000  may be repositioned until it is in the correct position. Once in the correct position, the step  2250  comprises advancing the crossing device and the hybrid dilator across the septum to create a transseptal puncture site and dilate the puncture site to facilitate advancement of one or more secondary devices through the transseptal puncture site. Due to the crossing device and the hybrid dilator respectively having at least one echogenic, EAM, or radiopaque marker, the relative positioning of the distal tip of the dilator and the distal tip of the crossing device may be seen at all times. By observing when the distal tip of the crossing device advances past the distal tip of the hybrid dilator through one of the visualization methods, the physician will be able to determine when the crossing device has crossed into the left atrium. The hybrid dilator  2000  simplifies the procedural workflow by providing a one-piece transseptal tool compared to a sheath and dilator. The hybrid dilator  2000  reduces the number of physical/geometric transitions as well as the number of material transitions or tactile obstructions which may allow the physicians to complete a transseptal crossing with greater ease. The method may additionally comprise step  2260 , exchanging the crossing device with a guidewire and advancing the guidewire into the left atrium; at step  2270 , removing the hybrid dilator  2000 , and at step  2280 , advancing the one or more secondary devices over the guidewire into the left atrium to complete the desire procedure. 
     The radiopaque marker  2050  allows visualization of the distal tip  2140  of the hybrid dilator  2000  (See  FIG.  20   ). The visualization allows the user to determine the position of the hybrid dilator&#39;s tip  2140  relative to the target position. This allows the user to adjust the hybrid dilator&#39;s position prior to using the crossing device. Once the distal tip  2140  of the hybrid dilator  2000  is correctly positioned, the crossing device may be used to cross the target tissue. In some embodiments, the crossing device that is provided comprises one or more radiopaque markers at a distal end thereof. In some such embodiments, the one or more crossing device radiopaque markers  12  are configured to co-operate with the hybrid dilator radiopaque marker  2050  to indicate the position of the crossing device relative to the hybrid dilator. A successful puncture and crossing by the crossing device may be determined by the radiopaque markers of the crossing device moving relative to the radiopaque marker  2050  of the hybrid dilator  2000 . Once the crossing device has crossed the target tissue, the hybrid dilator  2000  is advanced. The position of the distal tip  2140  of the hybrid dilator  2000  may be tracked during dilation and after crossing the target tissue. 
     In some embodiments, the distal tip of the hybrid dilator  2000  comprises a material with radiopacifier properties (such as Bismuth oxychloride (BiOCL)) embedded in the polymer material, the distal tip  2140  is visible under fluoroscopy (See  FIG.  20   ). Both the radiopaque marker of the crossing device at the distal tip of the hybrid dilator are visible, even when the crossing device is positioned within the hybrid dilator  2000 . In other words, the radiopaque marker  2050  and the radiopacifier embedded polymer distal tip  2140  are visible on fluoroscopy and ultrasound. When the crossing device is positioned within the hybrid dilator, the marker band of the crossing deice is more opaque than the distal tip  2140  of the hybrid dilator allowing both devices to be visible. In this embodiment, when the distal tip  2140  of the hybrid dilator  2000  is positioned against the target tissue, a successful puncture may be determined either by the visualization of the crossing device exiting the distal tip or the visualization of the crossing device under ultrasound. 
     An alternate example of an optimized transseptal workflow with the use of the hybrid dilator  2000  is illustrated in  FIG.  31   . The method comprises the steps of: at step  2310 , gaining access into the right atrium via vasculature using a radiofrequency (RF) wire; and at step  2220 , advancing a hybrid dilator  2000  over the RF wire into the right atrium. By using an RF wire and a hybrid dilator  2000 , it reduces the number or parts that the physician uses. Instead of a sheath, dilator, guidewire, and needle, a hybrid dilator and RF wire may be used. The method may additionally comprise: step  2320 , determining if the distal tip of the hybrid dilator is positioned on the target site. The position of the distal tip  2140  of the hybrid dilator  2000  may be determined using various visualization methods such as fluoroscopy, electro-anatomical mapping, or echogenic markers. The hybrid dilator  2000  may be repositioned until it is in the correct position. Once in the correct position, step  2340  comprises advancing the RF wire and the hybrid dilator across the septum to create a transseptal puncture site and dilate the puncture site to facilitate advancement of one or more secondary devices through the transseptal puncture site. The hybrid dilator  2000  simplifies the procedural workflow by providing a one-piece transseptal tool compared to a sheath and dilator. The hybrid dilator  2000  reduces the number of physical/geometric transitions as well as the number of material transitions or tactile obstructions which may allow the physicians to complete a transseptal crossing with greater ease. The method may additionally comprise step  23 , removing the hybrid dilator  2000  while the RF wire remains in the left atrium, and at step  2360 , advancing the one or more secondary devices over the RF wire into the left atrium to complete the desire procedure. 
     Reshapeable Hybrid Dilator 
     During a transseptal puncture procedure, the hybrid dilator is positioned against the septum  505 . Proper position may be verified using visualizing systems such as fluoroscopy and intracardiac echocardiography (ICE). In some embodiments, the hybrid dilator is visualized on an electroanatomical mapping (EAM) system. Once in proper position at the target site, the crossing device punctures the septum  505 . 
     In some instances, the hybrid dilator is unable to reach the target site due to anatomical variations. In standard workflows, the crossing device is a rigid mechanical needle or rigid RF needle that may be manipulated or curved to shape to the patient&#39;s anatomy. Accordingly, the shape of the crossing device is typically designed to define the curve of the combined system (i.e., hybrid dilator and crossing device) so that the tip of the crossing device may be appropriately directed. 
     In some instances, the rigid needle is unable to be shaped or curved to the desired shape or the desired shape is not maintained after shaping or curving. In other embodiments, the crossing device is a flexible puncturing device and does not impart any rigid shape or curve to the overall system at all. 
     In an embodiment, the hybrid dilator can be manipulated or curved to the shape of the patient&#39;s anatomy. In a specific embodiment, the hybrid dilator  1000  is reshapeable. A reshapeable hybrid dilator  1000  allows for enough plasticity to deform to the desirable shape, and enough rigidity to resist relaxation of the curve during device manipulation in the body.  FIGS.  10 A- 10 D  show a cross sections of various embodiments of a reshapeable hybrid dilator  1000 . Hybrid dilator  1000  comprises a stiffening member  1020  which provides the physician the ability to re-shape the dilator during the procedure, optimizing the positioning of the distal tip on the septum. 
     The shapeability of the hybrid dilator  1000  allows physicians to shape the hybrid dilator  1000  to improve positioning on the septum while also providing increased reach of the distal tip (i.e. increased distal tip distance from an uncurved axis). If the physician is not satisfied with the positioning of the tip of the hybrid dilator, the physician may shape the hybrid dilator  1000  to a desired curvature. This allows the physician to shape or curve the hybrid dilator  1000  so the tip of the hybrid dilator has the desired lateral distance from the axis of the uncurved portion. The stiffening member  1020  enables the hybrid dilator to be shaped either prior to or during the procedure. The stiffening member  1020  may be plastically deformed by manual manipulation by a physician. Once hybrid dilator  1000  has been manipulated to a desired curvature, the stiffening member  1020  has sufficient rigidity to resist relaxation of the curve. In other words, the stiffening member  1020  enables the hybrid dilator  1000  to hold its shape throughout the procedure, or until the hybrid dilator  1000  is again manipulated to a difference shape. When navigated through the vasculature to the target site, the stiffening member  1020  holds the desired curve of the hybrid dilator  1000 . 
     The hybrid dilator  1000 A of  FIG.  10 A  has a shaft  1010  comprising an outer layer  1012  and a stiffening member  1020 . In this embodiment, the stiffening member  1020  is a hypotube  1022 . The outer layer  1012  is typically comprised of Pebax or LDPE. In some alternative embodiments, the outer layer is made of HDPE or medium density polyethylene (MDPE), all of which are compatible with lubricious coatings. In some embodiments, the stiffening member  1020  is a stiff homogenous core such as a hypotube  1022  made of metal or plastic. In some embodiments, the metal hypotube may undergo heat treatments or other conditioning to achieve the desired properties. In alternate embodiments, the stiffening member  1020  is a stiff heterogenous core formed of multiple layers and segments of metal and/or plastic. 
     The hybrid dilator  1000 B of  FIG.  10 B  has a shaft  1010  comprising an outer layer  1012  and an inner layer  1014 . The outer layer  1012  is typically comprised of Pebax or LDPE. The inner layer  1014  is typically comprised of HDPE. The hybrid dilator  1000 B comprises a stiffening member  1020  between the inner layer  1014  and the outer layer  1012 . In the embodiment of  FIG.  10 B , the stiffening member  1020  is a wire stiffener  1024 . The wire stiffener  1024  comprises at least one wire. In the embodiment shown, two wires are present. In some embodiments, the wire stiffener is made of metal and in alternate embodiments, the wire stiffener is made of a polymer. In some embodiments, the wire stiffeners undergo conditioning or treatments to achieve desired properties. In the embodiment of  FIG.  10 B , the hybrid dilator  1000 B additionally comprises a torque layer  1030 . The torque layer  1030  improves the torqueability of the device. Torqueability refers to the ability of a device to respond to manual manipulations at one end of the device (e.g., a proximal end) to translate to movement at a second end of the device (e.g., a distal end). The torque layer is typically a braided material. The torque layer  1030  is positioned between the inner and outer layers  1012 ,  1014  with the wire stiffeners  1024 . In some embodiments, the outer layer  1012  and the inner layer  1014  are fixed to one another. Such embodiments may be manufactured using a reflow process which melts both the inner and outer layers into the braided layer whereby the braided layer mechanically joins the two materials together. In other embodiments, the outer layer  1012  and the inner layer  1014  are bonded to one another (e.g. adhesives, friction fit, etc.). In some embodiments, the outer layer  1012  and inner layer  1014  are fixed to one another along the length of the shaft. In some alternate embodiments, the outer layer  1012  and inner layer  1014  are fixed to one another at intervals along the shaft. The layers may be fixed at intervals to alter the mechanical properties along the shaft  1010  to improve steering or shapeability considerations. 
     The hybrid dilator  1000 C of  FIG.  10 C  has a shaft  1010  comprising an outer layer  1012  and multiple stiffening members  1020 . The hybrid dilator  1000 C comprises a first stiffening member, wire stiffeners  1024 , and a second stiffening member, hypotube  1022 . The combination of stiffening members results in a combination of reshapeable properties. The hypotube may be a homogenous core or a heterogenous core. The hybrid dilator  1000 C comprises at least one wire stiffener  1024 . In this specific embodiment, hybrid dilator  1000 C has 6 wire stiffeners  1024 . 
     The hybrid dilator  1000 D of  FIG.  10 D  has a shaft  1010  comprising an outer layer  1012 , an inner layer  1014 , and a stiffening member  1020 . In this embodiment, the stiffening member  1020  is a hypotube  1022 . In this specific embodiment, the stiffening member  1020  is the innermost layer and defines the lumen. The hybrid dilator  1000 D additionally comprises a torque layer  1030 . The torque layer  1030  is typically a braided material. The torque layer  1030  is positioned between the inner and outer layers  1012 ,  1014 . Such embodiments may be manufactured using a reflow process which melts both the inner and outer layers into the braided layer whereby the braided layer mechanically joins the two materials together. Some such embodiments have a stainless steel braid and provide 8 N cm of torque transmission. 
     In some embodiments, the size of hybrid dilator  1000  is from about 12 French to about 20 French. In a specific example, the hybrid dilator has a size of about 12.5 French (outer diameter of about 0.163″ (0.414 cm) to about 0.166″ (0.421 cm)). In another example, the hybrid dilator has a size of about 15 French (outer diameter of about 0.193″ (0.490 cm) to about 0.205″ (0.521 cm)). 
     Hybrid Dilator Superelastic Curve Retention 
     During a transseptal puncture procedure, the hybrid dilator is tracked through the vasculature to reach the heart. In cases of difficult percutaneous access or tracking through complex vasculature, the hybrid dilator may be deformed and lose the desired curve. A greater amount of curve retention will allow increased predictability and greater control. The ability to retain a set curve is dependent on the material properties, namely the strain at yield. Deformation up to the yield point is elastically recoverable. 
     In some embodiments, the shaft of the distal end curvature comprises a shape memory material. In a specific example, the shape memory material is nickel titanium alloy Nitinol which exhibits a very high strain at yield.  FIG.  21    illustrates the mechanical properties of Nitinol  52  compared to steel  51 . The graph of  FIG.  21    shows the stress (Y) vs. strain (X) curves of Nitinol  52  and steel  51 . A material with a very high strain at yield is known as superelastic as it can resist elongation of up to 30% without permanent deformation. The distal end curvature comprising a superelastic material will exhibit very high curve retention. The hybrid dilator is able to be tracked through the vasculature without deforming the curve. In alternate embodiments, other superelastic or shape memory materials are used for example polymers such as polyether ether ketone (PEEK). 
     In the embodiments shown in  FIGS.  11 A- 11 C , the hybrid dilator  1100  comprises a superelastic stiffening member  1120 . The superelastic stiffening member  1120  is capable of elastically deforming while passing through vasculature and is capable of reverting to its original shape. In embodiments where the distal end comprises a superelastic stiffening member  1120 , the hybrid dilator  1100  is capable of elastically deforming while passing through the vascular and capable of returning to its original curvature (i.e. it&#39;s curvature at time of manufacturing) at the target site more predictably. 
       FIG.  11 A  shows a cross section of the distal end curvature of a hybrid dilator  1110 A. The hybrid dilator  1100 A comprises a superelastic stiffening member  1120 . In this embodiment, the superelastic stiffening member  1120  is a superelastic hypotube  1122 . In a specific example, the hypotube  1122  is made of nitinol. The hypotube  1122  may be a continuous structure or have cut patterns. 
       FIG.  11 B  shows a cross section of the distal end curvature of a hybrid dilator  1110 B. The hybrid dilator  1110 B comprises a superelastic stiffening member  1120 . In this embodiment, the superelastic stiffening member  1120  is braided wire  1126 . In a specific example, the braided wire  1126  is made of nitinol. 
       FIG.  11 C  shows a cross section of the distal end curvature of a hybrid dilator  1110 C. The hybrid dilator  1100 C comprises a superelastic stiffening member  1120 . In this embodiment, the superelastic stiffening member  1120  is a superelastic wire stiffener  1124 . In a specific example, the wire stiffener  1124  is made of nitinol. 
     The hybrid dilator  1100  comprising a superelastic stiffening member  1120  will improve the curve retention of the device during the procedure. This will result in an improved ability to navigate anatomy without permanently deforming the device, and more predictable curve geometry when approaching the target site. This is beneficial during difficult access cases and where precise positioning is required. 
     In hybrid dilator  1100 , a superelastic material such as Nitinol is used within the curved region. In one embodiment, this is constructed using standard catheter layup and thermal reflow techniques to embed the superelastic material into the shaft of the device. In alternate embodiments, the superelastic materials are incorporated through gluing, welding, or laminating within the shaft materials. 
     The superelastic material is positioned in the hybrid dilator  1100  where the curve is desired. After the superelastic material is positioned within this region, the curve geometry must be shape set. In one embodiment using the superelastic material Nitinol, the curve geometry is set by heating the Nitinol curve geometry a 400-550 degrees Celsius for 1-20 minutes. This is followed by quenching the part to room temperature. In some embodiments, there may be a sequence of heating and quenching steps to reach the final curve shape and shape memory needed. 
     Methods of Performing a Transseptal Procedure Using a Hybrid Dilator and Flexible Puncture Device 
     The hybrid dilator with a flexible puncturing device such as an RF guidewire provides an improved workflow. This improves the efficacy of a procedure by eliminating steps from the workflow in procedures which may require specialty ancillary devices, such as specialty sheaths, to be used to deliver the end therapy devices once gaining access to the left atrium. Some examples of procedures requiring specialty ancillary devices are cryoablations, left atrial appendage occlusions (LAAO), transcatheter aortic valve replacement (TAVR), Mitral valve repairs, pulse field ablations, and RF ablations. These procedures commonly require the use of end-therapy devices which can only be delivered with sheaths having inner diameters greater than the sheaths used during transseptal puncture. This is because such end-therapy devices are larger in size than transseptal puncture devices, such as mechanical needles, RF needles, and RF guidewires. Specifically, transseptal puncture sheaths are 8 Fr to 8.5 Fr in diameter while some specialty sheaths, such as those used for cryoablation and LAAO, are sized 12 Fr or larger. Due to the difference in the size of the sheaths for end-therapy devices and transseptal puncture devices, multiple exchanges are typically required in order to both perform the transseptal procedure (i.e., the procedure for puncturing the septum) and deliver the end-therapy device to the left atrium. 
     In some embodiments, the hybrid dilator is used in combination with a flexible puncturing device. Details of a flexible puncturing device and method of use are disclosed in International Publication No. WO2018/083599, entitled “METHODS AND DEVICES FOR PUNCTURING TISSUE”, and U.S. application Ser. No. 17/316,229 which are incorporated herein by reference in their entirety. The flexible puncturing device may comprise an energy delivery device, such as an electrode, that is operable to deliver energy, for example radiofrequency energy, in order to puncture the tissue. In some such embodiments, the distal tip of the flexible puncturing device may be substantially atraumatic in order to reduce pressure exerted on the tissue and prevent inadvertent damage during the procedure. The atraumatic tip may be cylindrical, hemispherical, or a rounded dome. In some embodiments, the flexible puncturing device may comprise an electrically insulative coating with the energy delivery device being exposed at the distal tip. In an alternative embodiment, the flexible puncturing device may comprise a relatively sharp distal tip in order to mechanically puncture the tissue (not shown). 
     In some embodiments, a flexible puncturing device may be used to puncture tissue. The flexible puncturing device may be in the form of a puncturing guidewire, for example a flexible 0.035″ guidewire. In some embodiments, the flexible puncturing device may have a distal portion wherein the stiffness is defined by a flexural rigidity of at least about 3.57×10−6 Nm2 to about to about 5.95×10−6 Nm2, for example about 4.76×10-6 Nm2. The proximal portion may have a flexural rigidity between 0.00107 Nm2 to about 0.00179 Nm2, for example 0.00143 Nm2. 
     The hybrid dilator 1000 is dimensioned to accommodate the RF guidewire. Specifically, the inner diameter of the hybrid dilator 1000 corresponds to the outer dimeter of the RF guidewire. In some embodiments, the inner diameter of the hybrid dilator  1000  may range from 0.0035″ to 0.050″, with a preferred inner diameter in the range of 0.038″ to 0.44″. 
     The stiffening member  1020  enables the hybrid dilator  1000  to be shaped either prior or during the procedure. The shapeability of hybrid dilator  1000  provides physicians with improved positioning on the septum while also providing increased reach of the distal tip. 
     When the hybrid dilator  1000  is used with a flexible puncturing device, the stiffening member  1020  provides stiffness to support the flexible puncturing device. Physicians may insert the hybrid dilator  1000  prior to manipulating the curved portion. During the procedure, physicians may then visualize the hybrid dilator  1000  and flexible puncturing device using various imaging techniques to determine where the distal end of the hybrid dilator  1000  is positioned. If the distal end of the hybrid dilator  1000  is not positioned appropriately, the hybrid dilator  1000  may be withdrawn and shaped to a desired curvature before being reinserted. Alternatively, physicians may introduce the curvature prior to the procedure. Thus, the example of the workflow, described above, may include an additional step of shaping the hybrid dilator  1000  prior to the start of the procedure. 
     An example of the improved workflow with use of the present invention is illustrated in  FIG.  12   . This method comprises the steps of: (i) Advancing the flexible puncturing device such as an RF guidewire to the superior vena cava (SVC)  902 . (ii) Advancing the hybrid dilator into the SVC overtop the RF guidewire  904 . (iii) Dropping the hybrid dilator and RF guidewire onto the septum to a target site such as the fossa ovalis  906 . (iv) Determining if the distal tip of the hybrid dilator is positioned on the target site  908 . Where the distal tip of the hybrid dilator is positioned at the target site may be determined using various visualization methods such as fluoroscopy, electro-anatomical mapping, or echogenic markers. If the distal tip of the hybrid dilator is not in the correct position, (v) Removing the hybrid dilator and reshaping the curve of the hybrid dilator  910 . The dilator is then reinserted and steps (ii)-(iv) are repeated until the distal tip of the hybrid dilator is positioned at the target site. Once the hybrid dilator is positioned correctly, (vi)Tenting the septum with distal tip of the hybrid dilator.  912 . (vii) Advancing the RF guidewire such that the distal tip of the RF guidewire is contacting the FO  914 . (viii) Puncturing the septum by energizing the RF guidewire and advancing the guidewire through the septum such that the distal tip is in the left atrium  916 . Upon completing the puncture, the physician may confirm access into the left atrium through various methods such as fluoroscopy, electro-anatomical mapping, pressure differentials, contrast injection, or echogenic markers. (ix) Advancing the hybrid dilator across the septum  918  thereby enlarging the puncture. (x) Removing the hybrid dilator and advancing one or more secondary devices over the RF guidewire into the left atrium  920  to complete the desired procedure. 
     In procedures where the physician wishes to use a relatively large delivery sheath for complex procedures (for example for cryoablation or LAA occlusion) and knows they cannot cross with that product, the physician can now cross the septum using two devices, a flexible puncture device and hybrid dilator such as the reshapeable hybrid dilator  1000 . A number of exchanges are removed by reducing a sheath and dilator into one device, the hybrid dilator  1000 , and reducing the guidewire and puncturing device into one device, the flexible puncture device. Thus, only two products are used to cross the septum and gain access to the left side of the heart. The flexible puncture device can also allow the exchange with a secondary device wasting fewer products and streamlining the procedure. 
     Steerable Hybrid Dilator 
     In some procedures, a fixed curve hybrid dilator may not provide the control or precision required to locate the target site. The reshapeable hybrid dilator  1000  has stiffening member  1020  which allows the physician to manipulate the curve to a desire angle, also known as reach. This control, however, can only be achieved while the device is outside of the body. In other words, once the device is inserted into the body, the curvature angle cannot be changed unless the device is removed from the body and manually reshaped by the physician. In cases with abnormal anatomy such as tortuous vasculature, large right atrium etc., the physician may remove the device multiple times to achieve the required curvature angle to perform the transseptal workflow. Each removal and insertion of a device into the body bears risk of introducing air embolisms into the vasculature. 
     The distal curvature of a steerable hybrid dilator can be controlled by the user at the handle. In one embodiment of the present invention, a steerable control system or handle  1370  is provided for manipulating a hybrid dilator  1300 . The steerable handle is disclosed in application PCT/IB2013/055013 which is incorporated herein by reference in its entirety. In a specific example, as shown in  FIGS.  13 A and  13 B , the handle  1370  is coupled to a shaft  1302  to enable a user to manipulate or steer the hybrid dilator  1300  in a desired direction during use. The handle  1370  comprises a handle control  1372  that is rotatably coupled to a handle housing  1374 . The handle control  1372  is rotatable about the longitudinal axis of the handle  1370  and rotates with respect to housing  1374 . In operation, the rotation of the handle control  1374  in a first rotational direction allows the user to steer or deflect the shaft  1302  in a first direction, whereas the rotation of the handle control  1374  in a second rotational direction allows the user to steer or deflect the shaft  1302  in a second direction. In alternate embodiments, the hybrid dilator has unidirectional control ( FIGS.  14 A and  15 A ). In some embodiments as described herein, the bi-directional steerable catheter described is operable to be deflected in two different deflection directions, a first and a second deflection direction. In other embodiments, the bi-directional steerable catheter is configured to (or has the internal workings that enable it to) deflect in two different deflection directions; however, the deflection of the catheter in one of its deflection directions is limited or restricted such that the observed deflection of the catheter is limited to a single deflection direction (relative to the starting, or neutral, position). Thus, in some embodiments a unidirectional control system is provided for a bi-directional steerable catheter to provide a unidirectional steerable catheter including at least two pull wires. 
     The rotation of the handle control  1372  is converted into a deflection of the shaft  1302  via a slide assembly  1376 , shown in  FIG.  13 B . Generally, handle control  1372  is co-operatively engaged with the slide assembly  1376  which is housed within a lumen defined by the handle housing  1374 . In a specific example, the handle control  1372  is threadably engaged with slide assembly  1376 . The rotation of handle control  1472  causes a corresponding linear translation of the slide assembly  1376  within the housing  1370 . This translation of the slide assembly  1376  is converted into a tensioning of the pull wires  1380  coupled to the slide assembly  1376  and thereby resulting in a deflection of the shaft  1302 . 
     The steerable hybrid dilator  1300  has increased precision and improved ability to locate the target tissue. 
     Steerable and Reshapeable Hybrid Dilator 
     Current steerable catheters only offer the control of distal tip of the catheter also known as precision. In cases of abnormal anatomy, the deflection afforded by the steerable catheter may be insufficient to provide the necessary reach. Conversely, reshapeable, fixed curved catheters only offer control of the broad curve also known as reach. In cases with abnormal anatomy, the physician may remove the device multiple times to achieve the required curvature angle to perform the transseptal workflow. 
     The inventors of the present invention have identified the limitations of each device and discovered systems to overcome these limitations. 
       FIG.  14 A  shows a catheter  2000  that has a reshapeable proximal portion  1450 , and a deflectable distal portion  1460 . In the specific embodiment of  FIG.  14 A , the catheter is a hybrid dilator  1400 . Alternate embodiments of the catheter  2000  are a sheath, dilator, needle, etc. (not shown). The physician is able to manipulate the reshapeable proximal portion  1450  when the device is outside the body and is able to manipulate the curve of the deflectable distal portion  1460  while the catheter  2000  is within the body. 
     The combination of a proximal portion configured to be reshapeable, and a distal portion configured to be deflectable allows the physician to reshape the proximal portion to achieve a desired reach and steer the distal portion for precision while inside the anatomy. 
     The catheter  200  of  FIG.  14 A  is a reshapeable and steerable hybrid dilator  1400 . The reshapeable proximal portion  1450  of the hybrid dilator  1400  comprises a stiffening member  1420 . The stiffening member  1420  enables the proximal portion of hybrid dilator to be shaped either prior or during the procedure. The stiffening member  1420  plastically deforms while being manipulated by the physician. Once the physician has curved the proximal portion  1450  of hybrid dilator  1400 , the stiffening member  1420  has sufficient rigidity to resist relaxation of the curve. The reshapeable proximal portion  1450  extends between the handle  1470  and the deflectable distal portion  1460 . In the embodiment of  FIG.  14 A , the reshapeable proximal portion  1450  extends from the handle  1470  and ends proximal to the deflectable distal portion  1460 . 
     In some embodiments, the stiffening member  1420  is hypotube  1422  made of metal such as stainless steel. In alternate embodiments, the stiffening member  1420  is heterogenous formed of multiple layers and segments of metal and/or plastic (not shown). An additional layer of plastic may be included for increased rigidity. The inner layer  1414  may consist of one or multiple segments of plastic with different properties. In the proximal portion  1450 , the inner layer may consist of a harder plastic for example a plastic having a Shore D&gt;60 such as HDPE and Pebax 60D-80D. 
     The deflectable distal portion  1460  of the hybrid dilator  1400  can be controlled by the user at the handle  1470 . The deflectable distal portion  1460  is compliant and flexible allowing the distal portion  1460  to curve. The hybrid dilator  1400  has a steering mechanism comprising a steering handle  1470  which is operatively connected to at least one control wire  1480  for steering the deflectable distal end portion  1460 . 
     The deflectable distal portion  1460  comprises an attachment point for a pull wire  1480 . In a specific embodiment, the pull wire  1480  is attached to the distal portion  1460  via a pull ring  1482 . The pull wire  1480  extends substantially along the length of the hybrid dilator  1400 . The distal end of the pull wire is attached to the pull ring  1482 . The proximal end of the pull wire  1480  is fixed relative to a translating component housed within the steering handle  1470 . A control device such as handle control  1472  controls the translating component and thus controls the pull wire  1480 . In a specific embodiment, the rotation of the handle control  1472  translates into linear movement of the translating component. The linear movement along the handle&#39;s longitudinal axis applies tension at the proximal end of the pull wire  1480 , thereby causing the distal portion of the shaft to deflect. In a specific embodiment, the handle control  1472  automatically locks the curvature angle of the distal portion  1460  when released by the user. In other words, the physician does not require to apply constant force to maintain a curvature in the distal portion  1460 . 
     The pull wire  1480  of the deflection mechanism is installed into the handle. This may consist of the sole or combined construction of pulleys, rack and pinions, rotating gears, motors, etc. In a specific embodiment, a single pull wire  1480  and pull ring  1482  provides deflection in one plane. In other words, the deflection is unidirectional. The proximal end of the pull wire  1480  may be mechanically bonded to a travelling member within the handle such as a block. A rotating or linear control may be used to move the travelling member axially along the length of the handle where this motion applies a tensile force on the pull wire  1480  which causes the distal portion  1460  to deflect. Handle control  1472  is an example of a rotating control. The second handle control  1674  ( FIG.  16 A ) is an example of a linear control. 
     In the embodiment of  FIG.  14 A , the distal portion  1460  is between approximately 5-10 cm. In other words, the steerable curve is achieved across this portion. The physician may manipulate the proximal portion  1450  while the catheter is out of the body to achieve the desired reach of the hybrid dilator  1400 . In this embodiment, the hybrid dilator  1400  can be deflected within the body to further improve the reach of the hybrid dilator and provide precision to the distal end of the hybrid dilator  1400 . The reach of the hybrid dilator  1400  of  FIG.  14 A  is shown in  FIG.  14 B  (arrow A). 
     In the embodiment of  15 A, the distal portion  1560  of the hybrid dilator  1500  is between approximately 2-4 cm. In this embodiment, the steerable curve is achieved across a smaller length than the embodiment of  FIG.  14 A . In other words, the stiffening member  1520  extends further distally on hybrid dilator  1500  creating a longer shapeable proximal segment  1580 . Therefore, the deflection point (i.e. the point where the curvature occurs) is further distal on the hybrid dilator  1500  thereby the deflection imparted via the deflection mechanism in the handle  1470  will change the distal most tip. A smaller distal portion  1560  offers increased precision of the distal end. The physician may manipulate the proximal portion  1550  while the catheter is out of the body to achieve the desired reach of the hybrid dilator  1500  then control the precision of the distal end while the hybrid dilator  1500  is inside the body. The precision control of the hybrid dilator  1500  can be seen in  FIG.  15 B  (arrow B). 
     The hybrid dilator  1400  of  FIG.  14 A  additionally comprises a torque layer  1430 . The torque layer  1430  improves the torqueability of the device. The torque layer is typically a braided material. The braided material may have a pitch or picks per inch (PPI) in a range from 20-70 PPI. The PPI influences the torquability of the shaft. The PPI may be constant along the shaft or may vary. The torque layer  1430  is positioned between the inner layer  1412  and the and outer layer  1014 . The pull wire  1480  is encompassed within the layer of braiding. 
     In the specific embodiments of  FIG.  14 A , the inner layer  1414  of the hybrid dilator  1400  is comprised of different materials. In a specific embodiment, the inner layer  1414  of the proximal portion  1450  is a harder plastic than the inner layer  1414  of the distal portion  1460 . The proximal portion  1450  inner layer may be made of HDPE, higher durometer Pebax (&gt;60D) and/or Nylon. The distal portion  1460 , inner layer  1414  may be a softer plastic for example a plastic with a Shore D&lt;50 such as LDPE or a lower durometer Pebax (&lt;50D). These segments of plastic may be thermally bonded together. In alternate embodiments, Blends of HDPE and LDPE of varying ratios (e.g. 80/20, 50/50) may also be used as a segment along the lengths of the shaft. In alternate embodiments, the inner layer  1414  is comprised of a single material (not shown). 
     In some embodiments, the outer layer  1412  has a lower durometer than the stiffening member  1420 . In other words, the outer layer  1412  is softer than the stiffening member  1420 . In such embodiments, the stiffening member  1420  provides the required shapeability while the outer layer provides a softer surface that would not cause damage to vessels. The softer outer layer is smoother and therefore easier to navigate vasculature. In some embodiments the outer layer  1412  is formed of a single material. In other embodiments, the outer layer  1412  is formed of multiple layers of materials. In some embodiments, the outer layer  1412  is a material with a lower durometer than the inner layer  1414 . For example, the outer layer  1412  has a hardness of Shore D&lt;50. The ratio of the thickness ratio of the outer layer  1412  and the inner layer  1414  dictates the stiffness and torque transmission of the hybrid dilator shaft. In some embodiments, the outer layer is LDPE, an HDPE/LDPE blend or a Pebax D 50  or less. A bonding step may be performed to bond the outermost shaft layer to the remainder of the assembly. 
     The catheter  2000  in  FIG.  16 A  is hybrid dilator  1600  comprising two deflection points. In this specific embodiment, hybrid dilator  1600  comprises two pull rings  1682 ,  1684 . The first pull ring  1682  is located approximately 5-10 cm from the distal tip  1640 . The second pull ring  1684  is located approximately 2-4 cm from the distal tip  1640 . The first pull ring  1682  is operatively connected to a first control such as handle control  1674  via pull wire  1680 . The second pull ring  1684  is operatively connected to a second control such as handle control  1672  via pull wire  1682 . The handle controls  1672  and  1674  are controlled independently from one another. In this specific embodiment, the handle control  1674  is a linear control which controls the proximal pull ring  1682 . This control improves the reach of the hybrid dilator  1600 . The reach (arrow C) can be seen in  FIG.  16 B . The handle control  1672  is a rotational control which controls the distal pull ring  1684 . This control improves the control of the distal tip  1640  or in other words, the precision of the hybrid dilator  1600 . The precision (arrow D) can be seen in  FIG.  16 B . In other embodiments, the handle control  1674  controls the distal pull ring  1684  and the handle control  1672  controls the proximal pull ring  1682  (not shown). 
     Methods of Performing a Transseptal Procedure Using a Steerable Hybrid Dilator and Flexible Puncture Device 
     An example of the workflow of the steerable hybrid dilator with a flexible puncture device is illustrated in  FIG.  17   . This method comprises the steps of: (i) Advancing the flexible puncture device such as an RF guidewire to the SVC  1702 . Alternatively, the flexible puncturing device may be a sharp-tipped guidewire. (ii) Advancing the hybrid dilator into the SVC overtop the RF guidewire  1704 . (iii) Dropping the hybrid dilator and RF guidewire onto the septum to a target site such as the fossa ovalis  1706 . (iv)Steering the distal tip of the hybrid dilator to the target site  1708 . This step may be assisted using various visualization methods such as fluoroscopy, electro-anatomical mapping, or echogenic markers. Once the hybrid dilator is positioned correctly, (v)Tenting the septum with distal tip of the hybrid dilator  1710 . (vi) Advancing the RF guidewire such that the distal tip of the RF guidewire is contacting the target site  1712 . (vii) Puncturing the septum by energizing the RF guidewire and advancing the guidewire through the septum such that the distal tip is in the left atrium  1714 . Upon completing the puncture, the physician may confirm access into the left atrium through various methods such as fluoroscopy, electro-anatomical mapping, pressure differentials, contrast injection, or echogenic markers. (viii)Advancing the hybrid dilator across the septum  1716  enlarging the puncture. (ix) Removing the hybrid dilator and advancing one or more secondary devices over the RF guidewire into the left atrium  1718  to complete the desired procedure. 
     In embodiments where the steerable hybrid dilator comprises a stiffening member such as hybrid dilator  1400 , the hybrid dilator  1400  may be shaped either prior or during the procedure. This additional step allows the physician to match the reach of the hybrid dilator  1400  to the specific anatomy. In an embodiment of the method, prior to tenting the septum, the physician may remove the hybrid dilator and reshape the hybrid dilator to better access the target tissue. After reshaping, the physician would insert the hybrid dilator and continue from step  1704 . 
     In some instances of a conventional transeptal puncture ( FIG.  6 A and  6 B ), the fixed curve transseptal system (needle, dilator and sheath) may not align with the fossa ovalis on the septum. For example, during the drop-down procedure, the dilator and sheath assembly  50  has dropped too low (i.e. inferiorly) on the septum  505  as seen in  FIG.  26   . In such an event, a safe and effective transseptal puncture cannot be performed. To return to the fossa, the drop-down procedure would have to be performed again. This often involves removing the dilator and sheath assembly  50 , advancing the guidewire into the SVC, advancing the sheath  20  and dilator  40  over the guidewire into the SVC, exchanging the guidewire with a needle, and performing the drop-down procedure to attempt to land on the fossa ovalis. 
     A steerable hybrid dilator  1300  and flexible puncture device increases the precision of the transseptal puncture and can eliminate the exchanges required in circumstances where the dilator is not positioned on the desire location of the septum  505 . In the scenario where the steerable hybrid dilator falls too low (i.e. inferiorly) on the septum  505  during the drop-down step ( FIG.  27 A ), the steerable hybrid dilator  1300  may be maneuvered and steered to change the distal curvature such that it moves superiorly onto the fossa ovalis of the septum  505 . This is advantageous over the conventional transseptal puncture procedure as the steerable hybrid dilator  1300  does not have to be withdrawn from the septum  505  or the body to correct for a low position on the septum  505 . In some procedures, the target puncture site is a superior position on the fossa ovalis.  FIG.  27 B  shows an embodiment where the steerable hybrid dilator  1300  is on the fossa but is at a lower (inferior) position than desired. The physician is able to steer the steerable hybrid dilator  1300  to a superior position on the fossa without removing the steerable hybrid dilator  1300  from the fossa ovalis. This increases the precision of the transseptal puncture which may improve the efficacy of the therapy. 
     When positioned on the fossa ovalis, the steerable hybrid dilator  1300  may be steered such that it changed the amount of the fossa that is tented ( FIG.  28 A  and  FIG.  28 B ). This in-situ control may improve the safety and efficacy of the transseptal puncture as it can adjust the tent to accommodate for variabilities in the anatomy. For example, if the physician feels they have excessive or insufficient tenting to perform an effective transseptal puncture, they may change the distal curve ( FIG.  28 C ) to decrease or increase the tenting. In the embodiment of  FIG.  28 C , the right atrium  501  may be larger and the distance between the septum  505  and right atrium wall  503  is greater than the normal anatomy. As such, even if the steerable hybrid dilator  1300  is on the fossa ovalis, the physician may need to increase the force applied to the fossa to achieve a desirable tent for puncture. This may be achieved by steering the steerable hybrid dilator  1300 . 
       FIG.  29 A  shows an alternate embodiment where the hybrid dilator  1000  does not have sufficient reach to contact the septum  505  (i.e. the curve of the dilator  1300  does not provide sufficient lateral distance between the distal tip of the dilator and the axis of the straight portion). In a reshapeable hybrid dilator  1000 , the dilator may be withdrawn from the body to be manually re-shaped (i.e. physical manipulation of the distal curvature by hand to increase the reach) then reintroduced into the SVC to perform the drop-down. In a steerable hybrid dilator  1300 , the distal curve may be controlled through the steering mechanism to increase the reach. In a reshapeable steerable hybrid dilator  1400 , a combination of manually re-shaping the dilator outside the body and steering the dilator in-situ can maximize the reach and control of the dilator. By re-shaping and/or steering, the hybrid dilator&#39;s  1000  reach can be extended and the accuracy of puncturing location can be improved.  FIG.  29 A  show the hybrid dilator  1000  with a reach of di unable to reach the septum  505 . After re-shaping, steering or a combination of the two, the hybrid dilator is able to reach the septum  505  with a reach of d 2  as shown in  FIG.  29 B . 
     Additionally, during some procedures, the physician may desire a specific puncture site based on the end therapy procedure. For a mitral valve repair, the physician may want to puncture the septum at a superior position on the fossa. Meanwhile, for a pulmonary vein ablation, the physician may want to puncture the septum at an anterior position on the fossa. By re-shaping and/or steering the hybrid dilator  100 , the physician is able to direct and/or steer the distal tip of the hybrid dilator  100  to the desired position on the septum  505 . Furthermore, after the puncture has been performed, the physician may direct the hybrid dilator  100  towards the particular anatomical feature. A steerable hybrid dilator provides additional control for the physician to accurately position the device after the puncture. 
     RO Marker 
     In some embodiments, the hybrid dilator comprises a marker at the tapered distal end. The marker may be fluoroscopic and/or echogenic. The marker indicates the distal tip location as well as the apex of the taper. In some embodiments, the marker is a radiopaque marker band. In other embodiments, the marker is a changing material with varying radiopaque properties at distal tip as well as the apex of the taper. 
     With reference now to  FIG.  19   , the reinforced dilator  1000  may include a radiopaque marker  1002  located at the distal tip  1004 . This radiopaque marker  1002  may be in the form of a radiopaque band or coil embedded within one of the polymer layers. The radiopaque marker  1002  enables physicians to visualize the distal tip  1004  of the enhanced dilator  1000  throughout the procedure. (e.g. platinum, gold, tungsten, and/or barium sulfate-filled polymer). In other embodiments an alternate radiopacifier is embedded in the polymer material such as BiOCL. In some embodiments, the BiOCL is &lt;25%. In another embodiment, a change in radiopaque materials is used to visualize the distal tip  1004 .  FIG.  20    illustrates an embodiment of the distal tip of a hybrid dilator  1000  with a radiopaque marker  1002  under fluoroscopy.  FIG.  20    additionally shows an embodiment of the distal tip of a hybrid dilator  1000  with a radiopacifier material (such as BiOCL) embedded in the polymer material  1003 . 
     As such, in accordance with embodiments of the present invention, a method is provided for streamlining the procedural workflow by providing a hybrid dilator that combines the functionalities of a conventional transseptal sheath and dilator assembly. With the hybrid dilator of the present invention a reduced number of devices may be required in order to complete the transseptal procedure, which enhances procedural efficiency while reducing procedural time and complexity. 
     FURTHER EXAMPLES 
     
         
         
           
               1 . A hybrid dilator for use with a crossing device in tissue puncturing procedures the hybrid dilator comprising: 
             a dilator body comprising
           a dilator shaft defining a lumen for receiving a crossing device therethrough, the dilator shaft being structured to provide support for the crossing device when the crossing device is used to create a puncture in a tissue, the dilator shaft comprising a proximal portion and a distal portion;   the proximal portion comprising at least one stiffening member, wherein the at least one stiffening members is reshapeable;   the distal portion comprising a distal tip having an outer diameter which tapers down to an outer diameter of the crossing device for providing a smooth transition between the crossing device and the distal tip when the crossing device is inserted through the lumen and protrudes beyond the distal tip;   a deflectable distal end portion; and   at least one pull wire; and   
         
             a steering handle connected to a proximal end portion of a catheter body, the steering handle operatively connected to the at least one pull wire for steering the deflectable distal portion of the catheter in at least one direction. 
             2. The hybrid dilator of example 1 wherein the stiffening member is a hypotube. 
             3. The hybrid dilator of example 1 where the stiffening members is at least one stiffening wire. 
             4. The hybrid dilator of example 1 wherein the hybrid dilator comprises two stiffening members. 
             5. The hybrid dilator of example 4, wherein a first stiffening member is a hypotube and a second stiffening member is at least one stiffening wire. 
             6. The hybrid dilator of any one of examples 1 to 5, wherein the hybrid dilator further comprises a torque layer. 
             7. The hybrid dilator of example 6 wherein the torque layer is a braided material. 
             8. The hybrid dilator of any one of example 1 to 7 wherein the deflectable distal end portion comprises at least one pull ring attached to the at least one pull wire. 
             9. The hybrid dilator of example 8 wherein the hybrid dilator comprises two pull wires and the deflectable distal end portion comprises two pull rings, a first pull ring attached to a first pull wire and a second pull ring distal to the first pull ring attached to a second pull wire. 
             10. The hybrid dilator of example 9 wherein the handle comprises a first handle control operatively connected to the first pull wire for steering the deflectable distal potion and a second handle control operatively connected to the second pull wire for steering the deflectable distal portion. 
             11. The hybrid dilator of any one of examples 1 to 10 wherein the stiffening member terminates at a distal end of the proximal portion. 
             12. The hybrid dilator of any one of example 1 to 11 wherein the dilator shaft has an outer diameter from about 12 French to about 20 French. 
             13. The hybrid dilator of any one of example 1 to 12 wherein the dilator shaft comprises an outer layer and an inner layer. 
             14. The dilator of example 13 wherein the outer layer is fixed to the inner layer. 
             15. The dilator of claim 14 wherein the outer layer is fixed to the inner layer by a reflow process. 
             16. The hybrid dilator of any one of examples 13 to15 wherein the stiffening member is positioned between the inner layer and outer layer. 
             17. A catheter comprising; 
             a shaft comprising:
           a lumen for receiving a device therethrough;   a proximal portion configured to be reshapeable;   a distal portion configured to be deflectable; and   at least one pull wire; and   
         
             a steering handle connected to the proximal portion of the catheter body, the steering handle operatively connected to the at least one control pull wire for steering the deflectable distal portion of the dilator catheter in at least one direction. 
             18. The catheter of example 17 wherein the catheter is a hybrid dilator. 
             19. A hybrid dilator for use with a crossing device in tissue puncturing procedures, the hybrid dilator comprising: 
             a dilator shaft defining a lumen for receiving a crossing device therethrough, the dilator shaft being structured to provide support for the crossing device when the crossing device is used to create a puncture in a tissue, the dilator shaft comprising at least one stiffening member, wherein the at least one stiffening members is reshapeable; and 
             a distal tip having an outer diameter which tapers down to an outer diameter of the crossing device for providing a smooth transition between the crossing device and the distal tip when the crossing device is inserted through the lumen and protrudes beyond the distal tip. 
             20. A kit for puncturing a tissue comprising: 
             a crossing device having a puncturing feature; and 
             a hybrid dilator of any one of examples 1 to 19. 
             21. The kit of example 20 wherein the crossing device is a flexible puncture device. 
             22. The kit of example 21 wherein the flexible puncture device is an RF guidewire. 
             23. A method of using a hybrid dilator and a crossing device for puncturing a septum of the heart, the method comprising the steps of: 
             inserting the hybrid dilator in vasculature of a patient; 
             positioning a distal tip of the hybrid dilator at the desired site of the septum; 
             using the hybrid dilator for supporting a crossing device, located within a lumen of the hybrid dilator, as the crossing device is advanced beyond the distal tip of the hybrid dilator to puncture the septum; and 
             advancing the hybrid dilator over the crossing device thereby dilating the desired site. 
             24. The method of example 23 further comprising the step of reshaping the hybrid dilator to reach a desired site of the septum. 
             25. The method of example 24 wherein the step of reshaping the hybrid dilator occurs prior to inserting the hybrid dilator into the vasculature. 
             26. The method of example 24 further comprising the steps of removing the hybrid dilator from the vasculature of the patient after unsuccessful positioning of the distal tip of the hybrid dilator at the desired site, reshaping the hybrid dilator to reach a desired site and reinserting the hybrid dilator in the vasculature of the patient. 
             27. The method of any one of examples 23 to 25 further comprising the step of steering the distal tip of the hybrid dilator to target the desired site. 
             28. The hybrid dilator of any one of examples 1 to 27 wherein, the distal tip comprises a radiopaque marker. 
             29. The hybrid dilator of example 28, wherein the radiopaque marker is echogenic. 
             30. The hybrid dilator of any one of examples 28 to 29, wherein the radiopaque marker is a coil. 
             31. The hybrid dilator of example 30, wherein the coil comprises tungsten. 
             32. The hybrid dilator of example 30, wherein the marker coil is from about 1 mm to about 2 mm in length. 
             33. The hybrid dilator of any one of claims 1 to 32, wherein the distal tip comprises a radiopacifier. 
             34. The hybrid dilator of claim 33, wherein the radiopacifier is BiOCL. 
             35. A hybrid dilator for use with a crossing device in tissue puncturing procedures, the hybrid dilator comprising: 
             a dilator shaft defining a lumen for receiving a crossing device therethrough, the dilator shaft being structured to provide support for the crossing device when the crossing device is used to create a puncture in a tissue; and 
             a distal tip comprising a radiopaque marker and the distal tip having an outer diameter which tapers down to an outer diameter of the crossing device for providing a smooth transition between the crossing device and the distal tip when the crossing device is inserted through the lumen and protrudes beyond the distal tip. 
             36. The hybrid dilator of example 35, wherein the dilator shaft has an outer diameter from about 12 French to about 20 French. 
             37. The hybrid dilator of any one of examples 3 to 36, wherein the dilator comprises an inner layer, an outer layer, and a torque layer therebetween. 
             38. The hybrid dilator of example 37 wherein the torque layer is comprised of a braided material. 
             39. The hybrid dilator of example 38, wherein the braided material comprises stainless steel. 
             40. The hybrid dilator of any one of examples 35 to 39, wherein the radiopaque marker is echogenic. 
             41. The hybrid dilator of any one of examples 35 to 40, wherein the radiopaque marker is a coil. 
             42. The hybrid dilator of example 40, wherein the coil comprises tungsten. 
             43. The hybrid dilator of example 40, wherein the marker coil is from about 1 mm to about 2 mm in length. 
             44. The hybrid dilator of any one of examples 35 to 43, wherein the distal tip comprises a radiopacifier. 
             45. The hybrid dilator of example 43, wherein the radiopacifier is BiOCL. 
             46. A method of using a hybrid dilator and a crossing device for puncturing a target tissue, the method comprising the steps of: 
             inserting the hybrid dilator in vasculature of a patient; 
             determining the position of the distal tip of the hybrid dilator; 
             positioning a distal tip of the hybrid dilator at the target site; 
             using the hybrid dilator for supporting a crossing device, located within a lumen of the hybrid dilator, as the crossing device is advanced beyond the distal tip of the hybrid dilator to puncture the septum; and 
             advancing the hybrid dilator over the crossing device thereby dilating the desired site. 
             47. The method of example 46, wherein the step of determining the position of the distal tip comprises a visualization method. 
             48. The method of example 47 wherein the visualization method comprises one of the methods from the group consisting of fluoroscopy, electro anatomical mapping, or ultrasound. 
             49. The method of any one of examples 46 to 48, wherein the distal tip of the hybrid dilator comprises a radiopaque marker. 
             50. The method of any one of examples 46 to 49 wherein the wherein the distal tip of the hybrid dilator comprises a radiopacifier. 
             51. The method of any one of examples 46 to 50 wherein the crossing device is a needle. 
             52. The method of example 51, wherein the needle is a radiofrequency needle. 
             53. The method of any one of examples 46 to 50 wherein the crossing device is a wire. 
             54. The method of example 53, wherein the wire is a radiofrequency wire. 
             55. The method of any one of examples 46 to 54, further comprising the step of removing the hybrid dilator; 
             56. The method of example 55, further comprising the step of advancing one or more secondary devices over the crossing device. 
             57. The method of any one of examples 46 to 56, further comprising the step of determining the crossing of the crossing device. 
             58. The method of example 57, wherein the step of determining the crossing of the crossing device comprises monitoring the relative movement of a radiopaque marker of the crossing device with respect to a radiopaque marker of the hybrid dilator. 
             59. The method of any one of examples 46 to 58, further comprising the step of determining the position of the hybrid dilator after advancing the hybrid dilator over the crossing device. 
           
         
       
    
     The embodiment(s) 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 subcombination. 
     Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.