Patent Publication Number: US-2020282187-A1

Title: Obturator, Sheath and Method for Using Same

Description:
The present application claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 62/566,352 filed on Sep. 30, 2017, and under 35 U.S.C. § 365 to International Application No. PCT/SG2018/050494 filed on Sep. 28, 2018. The entire contents of these applications are incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to an obturator, a cannula assembly, and methods for positioning or repositioning a guidewire and cannula. 
     BACKGROUND 
     Modern medical techniques generally need to balance the comfort of the patient with the time taken to perform procedures, the expense of those procedures and the associated risks. If an error is made during a procedure, it is desirable to rectify the error with as little deviation from the correct procedure as possible, and without increasing risk—e.g. without having to perform multiple penetrations of the subject&#39;s skin. 
     Antegrade peripheral revascularization, for example, can require guidewire access to the superficial femoral artery via needle-puncture into the common femoral artery (CFA). The CFA is often the site of choice as the femoral head is beneath and it facilitates effective post-procedure compression for haemostasis and prevention of external bleeding, retroperitoneal haemorrhage and pseudo-aneurysm formation. 
     The initial needle puncture is usually done blind by palpation alone, under fluoroscopy or else with the aid of ultrasound visualization. This is followed by insertion of the guidewire which is also typically blind, followed by insertion of an access sheath over the guidewire by the Seldinger technique. 
     The deep formal artery—profunda femoris artery (PFA)—can be accidentally cannulated instead of the superficial femoral artery (SFA). This may be due to procedural or anatomical factors. 
     Procedurally, guidewire-insertion is done blind as it requires a bimanual approach and many operators do not ultrasound or perform fluoroscopy during this step. This means the guidewire will take whichever initial trajectory it has upon exiting the needle. Moreover, interaction with pre-existing stenotic disease may skew the direction of the guidewire. 
     Anatomically, the real-estate for puncture of the CFA can be very short (about 1-1.5 cm) and the PFA (deep femoral artery) ostium tends to be situated on the lower surface of the artery resulting in preferential passage of the needle-directed guidewire into it (see  FIG. 1 ). This can be problematic since SFA access must be achieved before revascularization can take place. Salvage of the guidewire and correction of its trajectory into the SFA extends the time taken for the operative duration, and increases the volume of radiation exposure and contrast used. Moreover, repeated rewiring may also injure or dissect the PFA. 
     Not infrequently, access is lost and a second puncture needs to be made. Repuncture carries the additional risks of bleeding, hematoma and pseudo-aneurysm formation. 
     Techniques to prevent PFA cannulation centre around puncturing more proximally on the CFA with the intention to “bounce” the wire off the back-wall into the SFA. Such techniques can often be ineffective. Moreover, the vasculature includes high bifurcations, making such high puncture techniques dangerous. For example, puncturing above the inguinal ligament can result in occult retroperitoneal haemorrhage which is potentially life-threatening. Calcific plaques on the front wall may also deflect the expected path of the guidewire into the PFA. Not infrequently the guidewire snakes along the back wall instead of bouncing off it. 
     Salvaging a PFA cannulation involves tentative withdrawal of the sheath, and guidewire, out of the PFA into the CFA and attempting to re-advance the guidewire down the SFA under angiographic guidance. The sheath then follows over the guidewire once access has been secured. During this time the access is most at risk as the sheath can come back out of the puncture site on the vessel. Salvage may also be impossible if the puncture is immediately adjacent to the PFA ostium or if anterior plaque prevents SFA cannulation. 
     It is desirable therefore to provide a device or method that facilitates introduction of a cannula or guidewire into the correct bodily lumen, that avoids or ameliorates at least one of the aforementioned disadvantages or at least provides a useful alternative. 
     SUMMARY 
     In accordance with the present disclosure, there is provided an obturator comprising a hollow distal end portion, the distal end portion comprising a distal end and a side hole located proximally of the distal end, the side hole being for receipt of a guidewire and to direct the guidewire laterally from the obturator. 
     In accordance with the present disclosure there is also provided an obturator comprising a hollow distal end portion, the distal end portion comprising: 
     a single lumen; 
     a distal end; 
     an end hole at the distal end, for receipt of a guidewire extending through the single lumen; and 
     a side hole located proximally of the distal end, the side hole being for receipt of a guidewire extending through the single lumen and to direct the guidewire laterally from the obturator, the side hole further being located so that when the obturator is located in a first bodily lumen, in use, a second bodily lumen can be located by flowing contrast medium through the obturator to exit the side hole. 
     Disclosed herein is a sheath comprising: 
     a substantially hollow body having a proximal end, a distal end and a single lumen in the distal end—the single lumen may be for receiving an obturator; 
     an end hole at the distal end, for receipt of a guidewire extending through the single lumen; and 
     a side hole disposed proximally of the distal end, so that when the sheath is located in a first bodily lumen, in use, a second bodily lumen can be located by flowing contrast medium through the sheath to exit the side hole, the side hole further being for receipt of a guidewire and to direct the guidewire laterally from the sheath. 
     The end hole and side hole may be accessible from the single lumen. 
     The distal end portion may comprise an end hole for receipt of the guidewire and being located at the distal end. The end hole may be positioned so that a guidewire extending therethrough extends substantially parallel to a longitudinal axis of the obturator. The end hole may be offset from the longitudinal axis of the obturator. 
     The side hole may be located on one side of the obturator so that a guidewire extending through the side hole extends at an angle to the obturator. 
     The distal end portion may taper towards the distal end. The side hole may be located proximally of the taper. The taper may extend from the side hole to this distal end. The taper may instead extend from a location proximal of the side hole, to the distal end. 
     The side hole may have one of a square, rectangular, triangular shape, circular or elliptical. The side hole may alternatively have a teardrop shape. The teardrop shape may comprise a distally directed apex. 
     The obturator may further comprise a slit extending between the end hole and side hole. 
     The obturator may further comprise one or more orientation indicia positioned on a proximal portion of the obturator to indicate a location of the side hole around on a periphery of the obturator. 
     In accordance with the present disclosure there is further provided a sheath comprising: 
     a substantially hollow body having a proximal end and a distal end; and 
     a side hole disposed proximally of the distal end, so that when the sheath is located in a first bodily lumen, in use, a second bodily lumen can be located by flowing contrast medium through the sheath to exit the side hole. 
     In accordance with the present disclosure there is further provided a sheath assembly comprising: 
     a sheath; and 
     an obturator as described above. 
     In accordance with the present disclosure there is further provided a sheath assembly comprising: 
     a sheath as described above; and 
     an obturator. 
     In accordance with the present disclosure there is further provided a sheath assembly as described above, wherein the obturator is an obturator as also described above. 
     The sheath may be a cannula and the obturator is within the sheath or cannula. 
     In accordance with the present disclosure there is further provided a method for inserting a sheath, comprising threading a sheath assembly as described above onto a guidewire and into a bodily lumen of a subject, the guidewire extending into the side hole of the obturator. 
     The sheath may be a cannula. 
     In accordance with the present disclosure there is further provided a method for repositioning a guidewire, comprising:
         threading, onto a guidewire located in a first (e.g. undesired) bodily lumen, a sheath assembly comprising a sheath and an obturator as described above, the guidewire extending through the side hole of the obturator, the side hole being positioned to redirect the guidewire into the second (e.g. desired) bodily lumen.       

     ‘General alignment’ may be achieved intracorporeally or by withdrawing the assembly, with the wire through its side hole, off a proximal end of the wire (i.e. the end of the wire located extracorporeally), and reinserting the wire through the end hole of the, or a, sheath assembly to thereby generally align the sheath assembly with the desired bodily lumen. 
     In accordance with the present disclosure there is further provided a method for repositioning a guidewire, comprising:
         threading, onto a guidewire, a sheath assembly comprising a sheath and an obturator as described above, the guidewire extending through the end hole of the obturator and into a subject;   determining the guidewire and sheath extend into the first bodily lumen of the subject;   retracting the guidewire into the sheath assembly; and   advancing the guidewire through the side hole of the sheath assembly and into the second bodily lumen of the subject.       

     In accordance with the present disclosure there is further provided a method for repositioning a sheath, comprising:
         performing the method described above, for repositioning a guidewire;   retracting the sheath assembly along the guidewire until the obturator becomes generally aligned with the second bodily lumen; and   advancing the sheath assembly into the second bodily lumen.       

     The obturator comprises an end hole, a side hole and a slit extending between the end hole and side hole, and retracting the sheath assembly along the guidewire until the obturator becomes generally aligned with the second bodily lumen may then comprise retracting at least the obturator until the guidewire is captured in the obturator through the slit. 
     Again, the sheath may be a cannula. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some embodiments will now be described by way of non-limiting example only with reference to the accompanying drawings in which: 
         FIG. 1  comprises  FIG. 1 a   , illustrating cannulation of the PFA, and  FIG. 1 b    illustrating cannulation of the SFA; 
         FIG. 2  illustrates an obturator—also known as a dilator or introducer—in accordance with present teachings, with guidewires (shown in broken lines) extending from forward (first) and side (second) holes in a distal end portion of the obturator; 
         FIG. 3  illustrates a cannula assembly with guidewire extending therethrough and a valve attached to an extension tube into a side port of the cannula hub; 
         FIG. 4  illustrates a distal region of a cannula assembly in which the distal end portion of the obturator comprises a slit; 
         FIG. 5 , comprising  FIGS. 5 a  and 5 b   , illustrates two different shapes of side hole; 
         FIG. 6 , comprising  FIGS. 6 a  to 6 j   , illustrates various configurations of the distal end portion of the obturator; 
         FIG. 7  is a flowchart showing a method for cannulation; 
         FIG. 8 , comprising  FIGS. 8 a  to 8 j   , illustrates steps in the method of  FIG. 7 ; 
         FIG. 9  illustrates longitudinal cross section through the distal end portion of an obturator in accordance with present teachings; a lateral cross section through an alternative obturator in accordance with present teachings; a longitudinal cross section of a vascular sheath or cannula; 
         FIGS. 10 to 12  illustrate longitudinal cross sections through a distal end portion of an obturator, comprising a variety of quartering mechanisms; 
         FIG. 13  illustrates a longitudinal cross section through a distal end portion of an obturator; 
         FIGS. 14 a  and 14 b    illustrate end and longitudinal cross sectional views of a distal end portion of an alternative obturator; 
         FIGS. 15 a , 15 b    and  16  illustrate longitudinal cross sections through a distal end portion of an obturator comprising multiple lumina; 
         FIG. 17  illustrates a sheath assembly in accordance with present teachings, introduced into an undesired bodily lumen, with a guidewire extending through the side hole into the desired bodily lumen; and 
         FIG. 18  illustrates a sheath or cannula in accordance with present teachings. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosures relates to an obturator, a sheath assembly including such an obturator, and methods for use of the sheath assembly. The sheath assembly will hereinafter be described as a cannula assembly for illustration purposes only. It will be appreciated the present obturator may be useable in other assemblies without departing from the teachings herein. 
     The obturator comprises at least a side hole, and generally two holes—a side hole and an end hole—through which a guidewire can extend. A first of the holes—the end hole—is positioned generally axially with respect to the cannula assembly. For a correctly positioned guidewire, this first hole will be the only hole used since the cannula, tracking or advancing along the guidewire, will follow the guidewire into the correct (i.e. desired) bodily lumen. For an incorrectly placed guidewire, a second of the holes—the side hole—will be used. Advancing the guidewire through the second hole causes it to extend into the desired bodily lumen. The cannula assembly can then be advanced along the guidewire into the desired bodily lumen. 
     The obturator is intended to improve the ease and speed of salvaging an incorrectly placed guidewire with minimal change or disruption to existing clinical procedural workflows. The obturator may also assist in securing arterial access while minimising inadvertent loss of access during salvage. An advantage of use of the present obturator when salvaging an incorrectly placed guidewire and sheath assembly is that patients and staff are exposed to reduced unnecessary radiation and iodinated contrast. 
     In general, the present disclosure will be made with reference to the vasculature of a subject (i.e. patient) and vascular lumina of that vasculature. However, it will be appreciated that the present teachings may be similarly applied to other lumina of the body: for example, it may be similarly applied to other bifurcating vessels in the body, beyond the CFA, including both arteries and veins. For example, it could also be used for selective cannulation in the heart, visceral arteries, upper limbs, carotids, brain etc. 
       FIG. 1  illustrates incorrect placement of a guidewire  108  ( FIG. 1 a   ) through a needle  110 , followed by correct placement of the guidewire  108  ( FIG. 1 b   ) resulting from bouncing the guidewire  108  off the wall  112  of a vascular lumen  108  near an ostium  114 . In the arrangement shown in  FIG. 1 , the various portions of the vasculature  100  are the CFA  102 , SFA  104  and PFA  106 . 
     Using the obturator disclosed herein, an interventionist or physician may be able to avoid the uncertainty of correct placement resulting from bouncing the guidewire off the vascular luminal wall and other known techniques. An embodiment  200  of an obturator in accordance with present teachings is shown in  FIG. 2 . The obturator  200  broadly comprises a hollow distal end portion  202 , the distal end portion  202  comprising a first hole  204  and second hole  206  both of which are for receiving a guidewire. 
     The term “receiving” as used in relation to the guidewire can mean that the hole is threaded over a guidewire that has already been located in the subject, or that the guidewire is advanced through the hole, or another meaning as determined by the context in which the term is used. 
     The obturator  200  further comprises a hub  208  and grip  210 . The hub  208  is for connection to a cannula or other medical device, in a known manner. Similarly, the grip  210  may take any known shape and is for gripping during removal of the obturator  200 . 
     The distal end portion  202  extends from the distal end  212 , proximally of the obturator  200 . The distal end portion  202  tapers towards the distal end  212 . The taper  214  extends from the distal end  212 , proximally of the obturator  200 . The taper  214  facilitates introduction of the obturator into the subject (not shown). 
     The distal end  212  is sized to have the same, or slightly larger, diameter as the guidewire during use. The subject&#39;s skin may resile to circumferentially contact the guidewire after removal of the needle used to place the guidewire. Close conformance of the distal end  212  of the obturator  200  with the diameter of the guidewire facilitates insertion of the obturator  200  into the pre-existing penetration of the patient&#39;s skin. 
     The second hole  206 , which may be interchangeably referred to as a side hole or lateral hole, may be located in the taper  214 , or proximally of the taper as shown in  FIG. 2 . Locating the second hole  206  proximally of the taper  214  means the leading edge of the second hole  206  can direct the guidewire along a lateral trajectory at a greater angle to the longitudinal axis  216  of the obturator  200 . In addition, the leading and trailing edges of the second hole  206  are at the same diameter, resulting in a lower likelihood of the second hole  206  catching on the subject&#39;s skin during insertion of the obturator  200 . 
     The first hole  204  is located at the distal end  212 . The second hole  206  is located proximally of the first hole  204 . As used herein, the term “proximally” and similar will refer to being located closer to the end of the obturator, cannula or other medical device, at which the physician or interventionist applies manual control of the medical device. Conversely, “distally” and similar refer to being located further from that end. Thus, the distal end of a medical device is the end of that device that is further from the end to which direct manipulation is applied by the physician or interventionist. 
     The first hole  204  is positioned so that a guidewire extending therethrough extends substantially parallel to the longitudinal axis  216  of the obturator  200 . In some embodiments, the first hole  204  is coaxial, or axially aligned, with the longitudinal axis  216 . The first hole is offset from the longitudinal axis  216  of the obturator  200 . Since the obturator  200  may be flexible, parallelism and axial alignment may be determined tangentially relative to the distal end  212 . 
     In the present embodiment, the second hole  206  is located on one side of the obturator  200 . A guidewire extending through the second hole  206  therefore extends at an angle to the obturator  200 . For illustration purposes,  FIG. 2  shows guidewires  218 ,  220  extending from the first hole  204  and second hole  206  respectively, in broken lines as they do not form part of the obturator  200 . 
     The second hole  206  may take any desired shape. For example, the second hole  206  may have a square, rectangular or triangular shape. In the embodiment shown in FIG.  2 , the second hole  206  has a rectangular shape (though exact rectangularity is not required to have a “rectangular” shape). 
     The second hole  206  is located around the periphery of the obturator  200 . The second hole  206  therefore extends from a hollow internal lumen of the obturator—such as lumen being known in the art—through the wall of the obturator  200  so that a guidewire can enter a bodily lumen through the second hole. 
     The obturator  200  of  FIG. 2  further comprises one or more, and presently one, orientation indicia  222 . The indicium  222  is positioned on a proximal portion of the obturator to assist the physician or interventionist to locate the distal end region in the subject—e.g. in relation to the profunda or SFA. In some embodiments, the indicium may be located towards the distal end of the obturator and be locatable either on fluoroscopy, ultrasound, or by estimation, to provide similar assistance. The indicium  222  indicates a location of the second hole around on the periphery of the obturator. This enables the physician or interventionist to know where the second hole  206  is located relative to the desired bodily lumen. Where more than one side hole is provided, as discussed below, there may be an indicium per side hole. 
       FIG. 9 a    schematically illustrates a longitudinal cross section of an alternative distal end portion  900  of an obturator  908  in accordance with present teachings. In one exemplary embodiment the side hole  910  may have a configuration of an oval shape. The oval shape has a major axis between 2 mm and 15 mm long—e.g. in a longitudinal direction of the hole  910  along the distal end portion  900 . The oval shape has a minor axis between 0.33 mm to 3.66 mm long—e.g. in the transverse or lateral direction of the hole  910  along the distal end portion  900 . In other embodiments the side hole may be circular, or elliptical either symmetrically or asymmetrically, triangular, square, rectangular or have a teardrop shape. 
     The obturator may comprise a single side hole as described with reference to  FIG. 2 . In the present embodiment, the obturator may instead comprise two, three, four or any other number of side holes as required. Presently, the obturator  908  comprises four side holes. The side holes are positioned at different distances from the distal tip  913  so as not to materially weaken the distal end portion  900 . The holes are positioned at 12 o&#39;clock ( 912 ), 3 o&#39;clock ( 914 ), 6 o&#39;clock ( 910 ) and 9 o&#39;clock ( 916 ) positions respectively, as best shown in  FIG. 9 b   . The holes  910  to  916  are thus spaced equidistantly about the periphery of the distal end portion  900 . 
       FIG. 9 b    is a view along the longitudinal axis of a transverse cross section of the distal end portion  900  of the obturator  908 . The side hole or side holes may be lined with, or have applied strips or shapes of materials of different densities or characteristics that are radiopaque on fluoroscopy, or strengthen various portions of the respective hole to enable proper independent manipulation of the guidewire and obturator during repositioning of each. 
     To facilitate selective control of the guidewire through each hole  140  to  146 , the obturator may comprise a single lumen with quartering mechanism, a dual or triple lumen as desired. Guidewire control and plural lumina are discussed with reference to  FIGS. 10 to 17 . 
       FIG. 9 c    schematically depicts a longitudinal cross section of the proximal and distal ends of a vascular sheath or cannula  902 . The cannula  902  comprises, proximally, a haemostasis valve—not shown but well understood in the art—within a hub  904 . The hub  904  is located outside of the skin during use and is the portion of a cannula assembly (discussed in more detail with reference to  FIG. 3 ) through which all cannulations commence. 
     The cannula  902  comprises a lumen  906 , and a flushing port (see port  320  of  FIG. 3 ) which enables fluid or contrast to be aspirated or injected down the lumen  906 . The obturator  908  is positioned within the lumen  906  during use and the fluid or contrast is often injected through the cannula  902  and obturator  908  into the subject. The fluid or contrast exits either by the longitudinal or first hole  922  and through hole  918  of the obturator  908 , through the side hole  910  of the obturator  908 , or both. 
     To facilitate delivery of contrast or fluid, the obturator or obturator insert  908  is hollow in its proximal extremity. The obturator may have either a blind end in its distal extremity or else incorporate a diverting or quartering mechanism (described with reference to  FIGS. 10 to 12 ) to divert the guidewire out the desired side hole upon activation of the diverting or quartering mechanism. The diverting or quartering mechanism facilitates replicable diversion of the path of a guidewire into the desired side hole. In the instance of a blind-ending obturator, initial access will be done using a known obturator with a single end-hole as per normal. Upon discovery of a profunda cannulation the obturator and wire will be removed and the blind-ending obturator with side a side-hole will be inserted into the cannula. The entire cannula-obturator assembly will be retracted until the side-hole aligns with the femoral artery bifurcation. The wire will be advanced down the side-hole into the SFA and passed for a substantial distance. The entire assembly will then be withdrawn over the wire out of the patient, and reintroduced along the guidewire using the, or a, know obturator having an end-hole so that in-line cannulation of the SFA is achieved. 
     The distance between elements  918  and  910  is between 0.5 to 10 cm. The distance between distal end  924  of sheath  902  is between 3 cm and 20 cm, and preferably 11 cm. 
     In one embodiment, the sheath  902  may be tapered towards the distal tip or end  924 , leading to the exit or longitudinal hole  922 , resulting in the hole  922  being considerably narrower than the lumen  906  of the sheath  902 . The gauge of the sheath  902  may be suitable for common peripheral vascular interventions, for example between but not limited to 4 Fr and 10 Fr. 
       FIG. 3  illustrates a cannula assembly  300  comprising a cannula  302  and an obturator  304  as described with reference to  FIG. 2 .  FIG. 3  shows how the hub  306  of the obturator  304  engages with a hub  308  of the cannula  302 . 
     The distal end portion  310  of the obturator  304  protrudes distally of the cannula  302 . The distal end portion  310  thereby enters the subject first, widening the penetration formed in the subject and facilitating easier entry of the cannula  302  into the subject. 
     In this embodiment, the distal end portion  310  protrudes sufficiently that the second hole  312  is located distally of the cannula  308 . 
     The cannula assembly  300  also includes an infusion assembly  314 . The infusion assembly  314  comprises a valve  316  and extension tube  318 , extending into a side port or infusion port  320  of the cannula hub  302 . 
     The entire complex—i.e. obturator, cannula and other of the cannula assembly—can be made from hypoallergenic, inert, flexible and stretchable materials such as silicone or polymers such as polyurethane. 
     The obturator  200 ,  304  of  FIGS. 2 and 3  each comprise a distinct and separate first hole and second hole. In contrast, the obturator  400  of  FIG. 4 , which is received within a cannula  402 , comprises a slit  404  extending between the first hole  406  and second hole  408 . The relevance of the slit  404  will be explained with reference to  FIG. 8 . 
     The cannula  402  of  FIG. 4  tapers towards the obturator  400  such that the diameter of the cannula  402  at its distal end is the same as the outer diameter of the obturator  400  when the two are assembled together. In other cases, the cannula  402  may be a sufficiently tight fit around the obturator  400  to substantially avoid catching on tissue of the subject during insertion and use. 
     The obturators  200 ,  304  of  FIGS. 2 and 3  both included a substantially rectangular side or second hole  206 ,  312  as shown in  FIG. 5 a   . In other embodiments, the side or second hole  500  may have a teardrop shape as shown in  FIG. 5 b   . The teardrop shape of the side or second hole  500  comprises a distally directed apex  502 . Thus, the apex  502  points towards the distal end  504  of the obturator  506 . In other alternatives, the apex may be oriented proximally, or is some other desired orientation. 
     The teardrop shape self-centres the guidewire (not shown) in the second hole  500  when the guidewire extends therethrough. Where a slit is used in conjunction with the teardrop shape, the teardrop shape also facilitates reintroduction of the guidewire into the obturator after repositioning of the guidewire from the undesired lumen of the subject, into the desired lumen. The teardrop shape can permit more gradual bending of the guidewire as it exist the side hole, but may be more difficult to manufacture than a rectangular or other shape side hole. 
       FIG. 6  shows various embodiments on distal end portions of obturators in accordance with present teachings, each of which is shown extending from a cannula. Each distal end portion tapers towards its respective distal end—e.g. towards the diameter of a guidewire received through the obturator. In some embodiments, however, the distal end portion may be blunt—for example, sized to have the same or similar internal diameter as the outer diameter of a guidewire extending therethrough. 
     The distal end portions shown in  FIGS. 6 a  to 6 c , 6 g  and 6 h    each comprise a second tapered region  600 . The second hole  602  may be located in the taper described with reference to  FIG. 2 , in the second tapered region  600  or between the tapered regions as shown. 
       FIGS. 6 a  to 6 e , 6 i  and 6 j    each show rectangular second holes, such a shape being shown in exploded view in  FIG. 5 a   . Similarly,  FIGS. 6 f  to 6 h    shown teardrop second holes, such a shape being shown in exploded view in  FIG. 5   b.    
       FIGS. 6 a  and 6 d  to 6 f    shown the second hole located closer to the distal end of the distal end portion than in  FIGS. 6 b , 6 c  and 6 g    to  6   j.    
       FIGS. 6 b , 6 d , 6 g  and 6 i    each show embodiments where the first and second holes are connected by a slit  604  for return of the guidewire into the obturator lumen (i.e. that which leads to the end hole). As described with reference to  FIG. 8 , during repositioning of the obturator onto an already repositioned guidewire the slit flexes around the guidewire. The closer the second hole is to the distal end of the obturator, the greater the force that may be applied to the internal wall of the vasculature during repositioning of the obturator. It can therefore be desirable to locate the second hole further proximally in the distal end portion. This would also make it easier to anchor the obturator in the undesired lumen in vivo, while relocating the guidewire. 
       FIG. 7  shows a flowchart  700  of workflows performed during cannulation. To commence cannulation a puncture is formed in the subject&#39;s or patient&#39;s skin, and into the vasculature—step  702 . In general, the puncture will be a micro-puncture formed by a needle (not shown). A guidewire is then advanced through the needle and into the vasculature—step  704 . After step  704 , the needle will generally be removed from the guidewire and a sheath (i.e. cannula assembly) threaded onto, or introduced over, the guidewire and into the vasculature—step  706 . 
     The physician then checks whether the cannula assembly is in the correct or desired vascular lumen—step  708 . With reference to  FIG. 1 , this would place the cannula assembly in the SFA. This check can be performed using contrast medium injected into the cannula assembly—e.g. through extension tube  318  of  FIG. 3 . The contrast medium can be detected using known methods. The check may also be performed manually, by palpation. 
     If the cannula assembly has entered the desired lumen, then the procedure (e.g. angioplasty) continues—step  710 . This will involve removal of the guidewire and obturator from the cannula, and insertion of another device—e.g. a catheter—through the cannula and into the desired vascular lumen. 
     If it is determined that the cannula assembly has been advanced into the undesired lumen, the guidewire is retracted into the cannula assembly—step  712 . The guidewire is retracted until the tip of the guidewire is aligned with, or is proximal of to, the second hole of the obturator. 
     The guidewire is then advanced through the second hole of the cannula assembly and into a second or desired bodily lumen of the subject—step  714 . The guidewire is thus repositioned into the desired bodily lumen. 
     Relevantly, the cannula assembly used up to, and including, the determination step  708  may be a standard cannula assembly known in the art—i.e. a cannula assembly comprising only a single hole in the obturator, that hole being coaxial with a longitudinal axis of the obturator. Upon determining that the guidewire is in the undesired lumen, that cannula assembly may be removed and unthreaded from the guidewire and a cannula assembly as taught herein then threaded onto the guidewire. Alternatively, a cannula as taught herein may be used from the outset. 
     In accordance with step  718 , the cannula may then be repositioned—e.g. into the desired lumen. This is achieved by retracting the cannula assembly (i.e. sheath) over or along the guidewire. Retraction occurs until the obturator becomes generally aligned with the desired bodily lumen. The term “aligned” in this circumstance means that upon advancing the cannula assembly back along the guidewire, the obturator, and thus the cannula, will be guided into the second, or desired, bodily lumen. The procedure may then continue as usual—step  710 . 
       FIG. 7  thus illustrates the normal or common workflow and a workflow involving repositioning the cannula assembly with minimal disruption to the common workflow. With reference to  FIG. 1 , the puncture site may be secured by the method  700 —i.e. not require a further puncture to be made for repositioning—by having obturator and guidewire operated in a manner that changes the direction of the guidewire while maintaining the sheath inside the PFA. The sheath is only removed from the PFA once the guidewire is safely secured in the SFA. With the guidewire in the SFA, secured by the sheath, the physician or interventionist can now proceed with lower limb angioplasty or some other procedure. 
     The steps of the workflow  700  involving the cannula assembly described herein, comprising two holes in the obturator (though the obturator may also comprise more than two holes) are mainly involved in steps  712  to  718 . It will be appreciated that a procedure may instead comprise two obturators, one in which the distal end portion comprises only a side hole located proximally of the distal end, for directing the guidewire laterally from the obturator, and a separate obturator comprising and end hole. 
       FIG. 8 , comprising  FIGS. 8 a  to 8 k   , illustrates various steps of the workflows of  FIG. 7 , or states of the sheath assembly during performance of those workflows.  FIG. 8 a    shows a sheath assembly located in the undesired lumen  800  as determined at step  708 .  FIG. 8 b    shows the guidewire  802 , after retraction and reinsertion or re-advancement along the sheath assembly, extending through the side hole  804 .  FIG. 8 c    shows how the guidewire  802  will rest on the desired lumen  806  after advancing through the side hole.  FIG. 8 d    shows the obturator  808  retracted so that its distal end  810  is proximal the ostium  812  between the desired lumen  806  and undesired lumen  800 . This retraction step occurs between introduction of the guidewire  802  into the desired lumen  806 —steep  716 —and retraction of the sheath  814 —step  718 . In this condition, the obturator  808  and guidewire  802  will be side-by-side in the sheath  814  as shown in  FIG. 8 e   . The obturator  808  and sheath  814  are then advanced back along the guidewire  802  into the desired lumen  806 — FIG. 8   f.    
     In an alternative embodiment, the obturator  816  includes a slit  818  between the end hole  820  and side hole  822  as shown in  FIG. 8 g   . After repositioning the guidewire  824  through the side hole  822 , the guidewire  824  is located immediately distally of the side hole  822  in the position generally indicated by  FIG. 8 h   . As the obturator  816  is retracted, as shown progressively in  FIGS. 8 h  to 8 j   , the guidewire  824  flexes the edges of the slit  818  inwardly until the guidewire  824  pushes back into the lumen  826  of the obturator  816 . The final position of the obturator  816  during retraction, with the guidewire  824  in the lumen  826 , is shown in  FIG. 8 k   . Thus, advancing the obturator  816  will result in it following the trajectory of the guidewire  824  into the desired lumen  828 . 
     With further reference to  FIGS. 8 c , 8 d  and 8 e   , after the guidewire  824  exits the side hole  822  into the second or desired bodily lumen  806 , the sheath assembly is retracted along the guidewire  824  until the guidewire  824  and extended distal taper of the obturator  816 —i.e. the taper between the side hole  822  and distal end—are wedged within the sheath. In some cases, if the distal taper is long enough, the guidewire  824  will not be recaptured in the obturator  816  at this stage. Instead, the two wedge into the sheath due to the reduce cross section of at the distal taper. This wedging facilitates removal of the obturator  816  out of the sheath assembly while leaving the guidewire  824  in the second or desired bodily lumen  806 . 
       FIGS. 10 to 12  illustrate a variety of quartering systems each comprising a quartering mechanisms and in some cases one or more elements for enabling, aiding and/or facilitating control of the quartering mechanism and thus of the guidewire selectively between end (or first) and side (or second) holes. The quartering system in each case is part of the obturator  1000 ,  1100 .  FIG. 10  itself illustrates more than one quartering system. It will be appreciated that, in practice, only a single such quartering system will typically be provided. 
     In one embodiment, the quartering mechanism is a contoured protrusion  1002 . The contoured protrusion is diametrically opposite the side hole  1004  (e.g. if the side hole  1004  is at 6 o&#39;clock then the protrusion  1002  is at 12 o&#39;clock). The protrusion  1002  is relatively proximal to the side hole  1004 . The protrusion  1002  preferably slightly overlaps the side hole  1004  such that it deflects the guidewire (not shown) into the side hole  1004 . 
     The shape of the protrusion  1002  may be a symmetrical or asymmetrical hump, or ledge, or wedge. The surface of the protrusion  1002  may be smooth, rough or grooved. The protrusion may be inflatable, e.g. using air or a liquid, through a conduit (not shown) so as to have a collapsed state permitting preferential access of the guidewire through one of the side and end holes—presently the end hole  918  described with reference to  FIG. 9 a   —and an inflated or expanded state directing the guidewire through the other of the side and end holes—presently the side hole  910  as described with reference to  FIG. 9 a   . Expansion and collapse of the protrusion  1002  may be performed in the same manner as expansion and collapse of a balloon catheter in a known manner. 
     In an alternative embodiment, a flap/leaflet  1006  may be used. The flap  1006  is located distally of the side hole  1004 . The flap  1006  can be either oriented to occlude the main lumen  1008 , for instance by flipping up (on a hinge, living hinge or otherwise) to force passage of the guidewire through the side hole  1004 , or oriented to permit passage of the guidewire down to the distal end of the main lumen  1008 . The flap  1006  may take a substantially planar form, may be a ball-valve mechanism rotated between a position in which the hole through the ball of the valve aligns with the main lumen  1008 —permitting passage of the guidewire through the ball-valve—and a position in which the hole is out of alignment (e.g. perpendicular to) with the lumen  1008  to prevent access to the distal end. Rotation of the mechanism  1006  may be achieved by control wires and similar, presently used to control implant and removal of medical devices in the vasculature in a known manner. The flap  1006  may instead change elasticity or stiffness to afford greater resistance to passage via an activating mechanism (not shown). The change in elasticity or stiffness may be affected either electrically (e.g. using an elastomer that change properties upon electrical stimulation, such as carbon black filled ethylene-propylene based elastomer (cPBE) embedded in a electrically insulating sheet of polydimethyl siloxane), or mechanically (e.g. by coiling up a very fine helical wire within the flap or inflating the flap body), as will be understood by the skilled person in light of the present teachings. 
     In yet a further alternative embodiment, an expanding circumferential ring or doughnut  1010  is provided. The expanding ring  1010  can be expanded to occlude the distal lumen upon activation, and thereby force the guidewire through the side hole  1004 . Upon activation—e.g. inflation in the same manner as a balloon catheter—the ring  1010  significantly narrows the lumen  1008  to occlude it and preferentially preclude a guidewire from advancing down the lumen  1008 —e.g. force the guidewire out the side hole  1004 . Similarly, feature  1014  is a ring  1010  is inside the wall  1016  of the sheath. The ring  1014  is constricted upon activation—e.g. by pulling a wire that shortens the circumference of the ring  1014 —to occlude the main lumen  1008  and direct the guidewire out the side hole  1004 . 
       FIGS. 11 and 12  show a dirigible device  1102  immediately distal to the side hole  1104 . A small channel  1106  is embedded inside the wall  1108  of the sheath (e.g. vascular sheath). The channel connects the dirigible device  1102  to the proximal portion (see hub  308  of  FIG. 3 ) of the sheath. This channel  1106  enables the transport of medium such as fluid or air to the dirigible device to manipulate and adjust its size as seen in  FIG. 11  in which it is inflated, and  FIG. 12  in which it is deflated. Similar mechanisms can be used for inflation/deflation and control of other mechanisms described with reference to  FIG. 10 . 
     In an alternative embodiment, the quartering mechanism for guiding the guidewire to the side hole utilizes an intraluminal inflatable or bag that is meant to act as a dirigible device as discussed with reference to  FIGS. 11 and 12 . This dirigible apparatus is connected to the outside via a channel embedded inside the wall of the vascular sheath and can be activated via the injection of medium such as saline, contrast or gas such as carbon dioxide. 
     Upon activation, this dirigible device will expand and occlude the lumen of the vascular sheath completely. Additionally, the expansion may also stretch the sheath in the immediate vicinity and secondarily expand the width of the side hole to facilitate the guidewire tip cannulating this newly enlarged opening. In addition, if the main lumen is completely occluded, contrast can be flushed via the side hole to visualize the ostium of the profunda or undesired lumen. 
     It will be appreciated that the location of the quartering mechanisms and other elements of the quartering systems shown in  FIGS. 1 to 12  may not be exactly as shown in relation to the side hole  1004 ,  1104 ,  1204 . However, placement of those quartering mechanisms to achieve the purpose of directing the guidewire through the side hole  1004 ,  1104 ,  1204  will be clear to the skilled person in light of the present teachings. 
     One or more obturators may instead be used as part of the quartering system. With reference to  FIG. 13 , the distal end  1300  of an obturator  1302  is designed to fit snugly inside the lumen of the vascular sheath—see, e.g.  FIG. 9 . The tip of the obturator  1302  maybe tapered or bullet shaped to facilitate puncturing of the arterial wall, during entry into the vasculature, or the wall of another bodily lumen as required. In some embodiments the obturators may have a slightly larger gauge than the sheath and upon entering the lumen of the sheath may dilate and stretch the wall of the sheath. 
     The obturator  1302  comprises a lumen  1306  having a side hole  1304 , with the distal end  1300  being blind. In some cases, an obturator having only and end hole—e.g. a traditional obturator—may be used until it is determined that the obturator has entered an incorrect bodily lumen. That obturator may then be removed and obturator  1302  threaded onto the guidewire. The intention of using obturator  1302  is to shift the end of the guidewire into the desired bodily lumen. The cannula assembly can then be advanced along the correctly placed guidewire. 
     The side hole  1304  may be oval, elliptical, quadrilateral or otherwise. 
     In an alternative embodiment shown in  FIG. 14 a   , the side hole  1400  may be in alignment with the end hole  1404  of the obturator  1402 , off the main internal lumen  1406  as shown in  FIG. 14 b   . While the end hole is not strictly at the very distal end of the obturator, it is forward facing with respect to the longitudinal axis of the obturator and will be referred to herein as an end hole. Also, alignment of the end hole and side hole refers to both being located in generally the same plane defined by the longitudinal axis of the obturator and a radial line normal to the longitudinal axis. Moreover, both the side and end hole are to one side of the longitudinal axis. The main internal lumen  1406  may come out at or near the edge of the distal end  1408 , offset from the midline as shown in  FIGS. 14 a  and 14 b   . A quartering mechanism described with reference to  FIGS. 10 and 11  may be used to direct the guidewire between hole  1404  and hole  1400 . 
     In  FIG. 14 b   , the proximal lumen is at 12 o&#39;clock and the distal lumen is central. 
       FIG. 15 a    illustrates an embodiment of on obturator  1500 , particularly the distal end portion  1506 , comprising two separate lumina  1502 ,  1504 . The lumina  1502 ,  1504  can be cannulated individually. For example, initially (e.g. at step  706 ) the sheath will be threaded over the guidewire with the guidewire extending into end hole  1508 . Once it is determined that the guidewire has been incorrectly positioned in the undesired bodily lumen, then the obturator  1500  is retracted while leaving the cannula or sheath in position. The obturator  1500  is removed from the guidewire and re-threaded back onto the guidewire with the guidewire extending through the side hole  1510 . When the obturator  1500  emerges through the distal end of the sheath, with the side hole  1510  oriented towards the desired bodily lumen, the guidewire will be flexed back out of the undesired bodily lumen into the desired bodily lumen. The sheath assembly can then be advanced into the desired bodily lumen. 
     For this to be achieved, there will generally be some flex or spare space within the sheath to permit that portion of the obturator between the side hole  1510  and tip  1512  to progress through the sheath next to the guidewire. Alternatively, a groove  1514  (see  FIG. 15 b   ) may be incorporated into the portion of the obturator, in which the guidewire is received during advancement of the obturator  1500  along the sheath. 
     One lumen  1504  is shorter than the other  1502 , and exits side hole  1510  whereas the other lumen  1502  is longer and exits centrally at hole  1512  at the distal end  1512  of the obturator  1500 . 
       FIG. 16  describes an obturator  1600  with a diverting lumen  1602  to attain side hole  1604  cannulation of the bodily lumen as before, with the difference that the distal lumen continues with an abrupt taper to end hole  1606 . This results in straight cannulation only being possible with a fine wire (eg 0.018″ or 0.014″). End hole  1606  has a smaller diameter than side hole  1604 . Thus, standard wires (ie 0.035″) will be diverted out the side hole  164 . This would allow preservation of wire access in the PFA while simultaneously enabling preferential cannulation into the SFA. It will be appreciated that a similar arrangement could allow preferential straight cannulation, by providing an end hole with a larger diameter than the side hole. A correspondingly larger diameter lumen will need to extend to the end hole, than the diameter of the lumen extending to the side hole, from the main lumen. Moreover, the internal lumen of the obturator may permit simultaneous positioning of a fine guidewire into the smaller diameter hole, and of a larger guidewire through the larger diameter hole. In addition, even where the holes are the same size or otherwise, the positioning of a guidewire in one hole may force a second guidewire to exit the other hole. 
     The present disclosure, particularly  FIG. 18 , also discloses a sheath  1800 . The sheath  1800  comprises a side hole  1802  and a distal end  1804 . In use, if an obturator (whether as taught herein or known), with the guidewire threaded through its end hole, is used with sheath  1800  and it is determined the sheath is in the undesired lumen, the obturator can be removed. Contrast medium is then flowed (e.g. injected) through the sheath  1800 . The contrast medium will exit the distal end  1804  if that end  1804  is open. The contrast medium will not exit the distal end  1804  if the distal end is blind (i.e. closed). In both cases, contrast medium will exit the side hole  1804 . The sheath  1800  can then be moved, if necessary, until the side hole  1804  is aligned with the desired lumen as indicated by contrast medium flowing out the side hole into the desired lumen, the contrast medium being visualised in a known manner. The guidewire can then be removed, an obturator as taught herein inserted, and the guidewire threaded so that its side hole aligns with the side hole  1804  of the sheath—e.g. as determined when the hub of the obturator meets the hub of the sheath, or by providing indicia on one or both of the obturator and sheath to indicate the relative alignment of the side holes. The guidewire is then threaded through the side hole of the obturator to project from the side hole of the sheath  1800  into the desired lumen. The sheath assembly may then be withdrawn and to relocate the sheath and/or sheath assembly on the guidewire such that the guidewire projects distally of the sheath  1800 , which can then be advanced into the desired lumen. The sheath  1800  may be a cannula or cannulation catheter, or other medical device. 
       FIG. 17  illustrates how the obturator will be positioned in situ with the distal end  1700  within the profunda or PFA  1706 , and the guidewire  1702  within the SFA  1708  after cannulating the side hole  1704 . For illustration purposes, the hub  1710 , CFA  1712  and cannula  1714  are also shown. 
     The obturators, sheath/cannula assemblies described herein enable easy cannulation of the “side hole” on the obturator by engaging the guidewire and diverting its direction from within the vascular sheath to exit more proximally the body of the obturator at an angle to the obturator. The guidewire is thereby intended to pass distally down the SFA. 
     In some embodiments, a combination of a vascular sheath and a hollow shafted but blind-ending obturator can be used, the obturator having a side exit a distance away from the blind end. Of note, the side hole on the obturator is equal or larger than the dimension of the side holes on the sheath. The blind-ending obturator shaft may be made of materials that are stiffer and may be of a diameter slightly larger than that of the vascular sheath to allow the obturator to dilate and stretch the outer sheath when the obturator is inserted inside the sheath. 
     This is depicted in  FIG. 17  in which the side hole of the obturator and the side hole of the sheath are orientated and aligned by, for example, using one or more indicia such as external markings, or radiopaque markings visible on x-ray. In some other embodiments, haptic feedback can be used—e.g. a “click” and partial lock/grip when the obturator is aligned with the cannula. In this preferred embodiment, the side hole on the sheath may be about 3 to 6 cm from the distal tip. The obturator with the blind ending tip is slightly longer than the length of the vascular sheath between the proximal hub and the furthest side hole. In a variation of this embodiment, the obturator may have a smaller distal channel or lumen to enable introduction of the obturator through the sheath over an existing fine wire located within the PFA, such that the SFA can be preferentially cannulated through the side hole using a larger wire—e.g. two wires may be within the obturator, one fine wire extending distally from the end hole and the other, larger wire extending laterally from the side hole—see  FIGS. 14 and 16 . 
     The perceived workflow for use of said obturator would be, in the case of the blind-ending obturator for the wire to be removed leaving the sheath in the PFA:
         insertion of the obturator—e.g. so that its tip extends to within the PFA;   localisation of the bifurcation between the desired and undesired lumina—e.g. PFA/SFA—using contrast injection, with slow withdrawal of the entire assembly until the correct level is reached as indicated by contrast flowing into the desired lumen (this step can be incorporate into the method of  FIG. 7 ); and   rotation of the sheath assembly until the side hole(s) align with the desired lumen—e.g. align with the PFA ostium—with or without final confirmatory angiographic runs to prove alignment before cannulation.       

     In the case of a fine-hollow obturator the existing wire would be changed to a 0.018″ or smaller wire to maintain access in the undesired lumen—e.g. the PFA—and the obturator advanced or railed over the wire to end in the desired lumen—e.g. the SFA—as before. The remainder of the workflow would remain the same. Insertion of a second wire would now cause diversion down the side hole. 
     In an alternative embodiment, the side hole may incorporate a mechanism for detection of the edge of the puncture, for instance by flashback, or cessation thereof, of blood up a suction channel, or else by injection of contrast down an injectable channel, which may allow for activation of a separate mechanism for suture or otherwise closure of the puncture site, not described here. 
     It is envisioned that contrast will be flushed through either both the distal end and side holes, or else preferentially through one or the other, to demonstrate that the side hole is sitting proximal to the bifurcation of CFA into SFA and PFA—i.e. the bifurcation between the desired and undesired lumina—and in position for wiring. It is also envisioned that radiopaque markers on the side of the sheath will enable the operator to easily align the side hole with the opening of the undesired lumen by rotating the sheath until the marker is in the appropriate position. 
     It is further envisioned that, in some embodiments, the sheath will be withdrawn over the guidewire, now extending into the desired lumen, in its side hole and reintroduced via the wire in its main, working or longitudinal central lumen so that work may continue down the desired lumen and more distally. 
     It is conceived that this concept may be utilized for retrograde punctures and may facilitate the easy cannulation of the internal iliac artery, the crossing of the aortic bifurcation, the cannulation of visceral branches during procedures that require retrograde access, or other bodily lumina. The principles will remain the same although the sizes will likely range up to 24 F or larger, and the lengths of the sheath and obturator may increase to 15 cm or even longer as needed for a particular application, without departing from the teachings herein. 
     In this specification and the claims that follow, unless stated otherwise, the word “comprise” and its variations, such as “comprises” and “comprising”, imply the inclusion of a stated integer, step, or group of integers or steps, but not the exclusion of any other integer or step or group of integers or steps. 
     The various embodiments and variations thereof illustrated in the accompanying Figures and/or described herein are merely exemplary and are not intended to limit the scope of the invention. It is to be appreciated that numerous variations of the invention have been contemplated as would be obvious to one of ordinary skill in the art with the benefits of this disclosure. Rather, the scope and breadth afforded this document should only be limited by the claims provided herein while applying either the plain meaning to each of the terms and phrases in the claims or the meaning clearly and unambiguously provided in this application. 
     References in this specification to any prior publication, information derived from any said prior publication, or any known matter are not and should not be taken as an acknowledgement, admission or suggestion that said prior publication, or any information derived from this prior publication or known matter forms part of the common general knowledge in the field of endeavour to which the specification relates.