Steerable sheath including elastomeric member

An MR compatible steerable sheath with elastomeric member is provided. The elastomeric member is configured to serve as a reservoir and receive contrast media therewithin. The elastomeric member is positioned on the distal end of the steerable sheath and may circumferentially surround the sheath shaft or be offset from a longitudinal axis thereof. In operation, the contrast media allows a user to view the distal tip of the steerable sheath by virtue of the contrast media contained within the elastomeric member.

FIELD OF THE INVENTION

This invention relates to deflectable medical catheters, namely steerable sheaths used in interventional vascular procedures to deliver tools into the human body. More particularly, the present invention is related to a steerable sheath having an elastomeric member bonded to an outer portion thereof and configured to receive contrast media therewithin.

BACKGROUND OF THE INVENTION

Deflectable medical catheters, namely steerable sheaths, are used in interventional vascular procedures to deliver tools (e.g. electrophysiology catheters, guidewires, elastomeric members catheters, stents, instruments, etc.) into the human body. More particularly, the present invention is related to a family of sheaths that incorporate one or more elastomeric members that serve as a reservoir for a contrast agent. The deflectable elastomeric member sheath is safe for use in the magnetic resonance environment and the elastomeric member and deflectable sheath tip is rendered visible by the contrast agent.

MRI has achieved prominence as a diagnostic imaging modality, and increasingly as an interventional imaging modality. The primary benefits of MRI over other imaging modalities, such as X-ray, include superior soft tissue imaging and avoiding patient exposure to ionizing radiation produced by X-rays. MRI's superior soft tissue imaging capabilities have offered great clinical benefit with respect to diagnostic imaging. Similarly, interventional procedures, which have traditionally used X-ray imaging for guidance, stand to benefit greatly from MRI's soft tissue imaging capabilities. In addition, the significant patient exposure to ionizing radiation associated with traditional X-ray guided interventional procedures is eliminated with MRI guidance.

A variety of MRI techniques are being developed as alternatives to X-ray imaging for guiding interventional procedures. For example, as a medical device is advanced through the patient's body during an interventional procedure, its progress may be tracked so that the device can be delivered properly to a target site. Once delivered to the target site, the device and patient tissue may be monitored to improve therapy delivery. Thus, tracking the position of medical devices is useful in interventional procedures. Exemplary interventional procedures include, for example, cardiac electrophysiology procedures including diagnostic procedures for diagnosing arrhythmias and ablation procedures such as atrial fibrillation ablation, ventricular tachycardia ablation, atrial flutter ablation, Wolfe Parkinson White Syndrome ablation, AV node ablation, SVT ablations and the like. Tracking the position of medical devices using MRI is also useful in oncological procedures such as breast, liver and prostate tumor ablations; and urological procedures such as uterine fibroid and enlarged prostate ablations.

MRI uses three fields to image patient anatomy: a large static magnetic field, a time-varying magnetic gradient field, and a radiofrequency (RF) electromagnetic field. The static magnetic field and time-varying magnetic gradient field work in concert to establish both proton alignment with the static magnetic field and also spatially dependent proton spin frequencies (resonant frequencies) within the patient. The RF field, applied at the resonance frequencies, disturbs the initial alignment, such that when the protons relax back to their initial alignment, the RF emitted from the relaxation event may be detected and processed to create an image.

Each of the three fields associated with MRI presents safety risks to patients when a medical device is in close proximity to or in contact either externally or internally with patient tissue. One important safety risk is the heating that may result from an interaction between the RF field of the MRI scanner and the medical device (RF-induced heating), especially medical devices that have elongated conductive structures, such as braiding and pull-wires in catheters and sheaths.

The RF-induced heating safety risk associated with elongated metallic structures in the MRI environment results from a coupling between the RF field and the metallic structure. In this case several heating related conditions exist. One condition exists because the metallic structure electrically contacts tissue. RF currents induced in the metallic structure may be delivered into the tissue, resulting in a high current density in the tissue and associated Joule or Ohmic tissue heating. Also, RF induced currents in the metallic structure may result in increased local specific absorption of RF energy in nearby tissue, thus increasing the tissue's temperature. The foregoing phenomenon is referred to as dielectric heating. Dielectric heating may occur even if the metallic structure does not electrically contact tissue, such metallic braiding used in a steerable sheath. In addition, RF induced currents in the metallic structure may cause Ohmic heating in the structure, itself, and the resultant heat may transfer to the patient. In such cases, it is important to attempt to both reduce the RF induced current present in the metallic structure and/or eliminate it all together by eliminating the use of metal braid and long metallic pull-wires.

The static field of the MRI will cause magnetically induced displacement torque on any device containing ferromagnetic materials and has the potential to cause unwanted device movement. It is important to construct the sheath and control handle from non-magnetic materials, to eliminate the risk of unwanted device movement.

When performing interventional procedures under MRI guidance, clinical grade image quality must be maintained. Conventional steerable sheaths are not designed for the MRI and may cause image artifacts and/or distortion that significantly reduce image quality. Constructing the sheath from non-magnetic materials and eliminating all potentially resonant conductive structures allows the sheath to be used during active MR imaging without impacting image quality. Similarly, it is as important to ensure that the control handle is also constructed from non-magnetic materials thereby eliminating potentially resonant conductive structures that may prevent the control handle being used during active MR imaging.

Importantly, there is a need for an improved steerable sheath that incorporates one or more elastomeric members to create a reservoir for the injection of an MRI contrast agent. When the contrast agent is injected into the elastomeric member, the elastomeric member expands and becomes visible on the image generated during the MRI scan. During this process, the sheath, otherwise invisible on the MRI scan, is rendered visible at the location of the contrast filled elastomeric member resulting in better visualization and tracking of the sheath tip.

BRIEF SUMMARY OF THE INVENTION

The foregoing need is addressed by the steerable elastomeric member sheath with the invention. Those of skill in the art will appreciate that the steerable elastomeric member sheath in accordance with the invention is disclosed as being utilized with the steerable sheath and control handle as described herein but may also be utilized with other steerable sheaths and control handles, all of which fall within the scope of the invention.

In one aspect of the invention a steerable sheath is provided that may be used in an MRI environment to deliver a variety of tools (catheters, guidewires, implantable devices, etc.) into the lumens of the body.

In a further aspect of the invention, the steerable sheath shaft comprises a reinforced polymer tube in which the reinforcing material is non-metallic based (Kevlar, PEEK, Nylon, fabric, polyimide, etc.) or a hybrid of metallic and non-metallic materials and the reinforcing geometry may comprise a braid, a coil, or a slit tube that mimics a coil and combinations of the foregoing. In yet another aspect of the invention, the reinforced polymer tube may also be segmented with varying flexibility along its length to provide the user with the ability to deflect the catheter in a region in which the segment is more flexible than other segments.

In yet another aspect of the invention the polymer tube may also include one or more passive visualization markers along the length of the tube and/or one or more active visualization markers along the length of the tube.

The steerable sheath in accordance with the invention also includes one or more pull-wires which are coupled with the reinforced tube and that allow the user to manipulate and deflect the polymer tube. In one aspect of the invention, the pull-wires are preferably made of a non-metallic material (Kevlar, PEEK, Nylon, fabric, etc.). One or more internal pull-wire lumens are positioned within the polymer tube construct and allow the user to manipulate the pull-wires to move smoothly during actuation. One or more anchor points connect the pull-wire in the distal portion of the polymer tube.

In another aspect of the invention a control handle on the proximal end of the reinforced tube operates longitudinal movement of the pull-wire(s). In one aspect of the invention, the handle includes paramagnetic or diamagnetic materials or combinations of paramagnetic and diamagnetic materials.

In another aspect of the invention, an elastomeric member may circumferentially encompass the outer diameter of the sheath shaft or may be bonded to an outer portion thereof.

In another aspect of the invention, a deflectable sheath may integrally or non-integrally incorporate the elastomeric member.

In another aspect of the invention, the elastomeric member may be designed to be of a variety of shapes such as circular, conical, square, spherical, elliptical, tapered, dog bone, paddle, offset and/or toridal.

In another aspect of the invention, the sheath may include a single tube lumen or a multiple tube lumen that is fluidly coupled with the elastomeric member.

In another aspect of the invention, the deflectable sheath may incorporate one, two, three four offset-shaped elastomeric members.

In another aspect of the invention, the lumen(s) used to fill the elastomeric member(s) have a diameter sufficient to allow for the injection of viscous fluids into the elastomeric member and allow for quick inflation and deflation of the elastomeric member.

In another aspect of the invention, the lumen(s) used to fill the elastomeric member are coated to minimize resistance between the lumen wall and liquid within the lumen and allow for quick inflation and deflation of the elastomeric member.

In another aspect of the invention, the elastomeric member is made sufficiently pliable to allow it to inflate with viscous fluid without requiring excessive pressure at the injection site or within the lumen used to fill the elastomeric member.

In another aspect of the invention the elastomeric member comprises an inflatable balloon.

In another aspect of the invention, an MR compatible steerable sheath is provided. The MR compatible steerable sheath includes a steerable shaft including a proximal end and a deflectable distal tip, the steerable shaft configured to receive first and second longitudinal movement wires operably coupled to the deflectable distal tip; an elastomeric member operably coupled to the proximal end of the steerable shaft and configured to receive contrast media; a control handle having a main body configured to receive first and second rack screws, the second rack screw including a threaded portion on an outer surface thereof, the steerable shaft extending axially through the control handle; the first longitudinal movement wire operably coupled to the first rack screw and the second longitudinal movement operably coupled to the second rack screw; and a rotatable adjustment knob operably engageable with the control handle, the rotatable adjustment knob having an internal threaded portion matingly engageable with the threaded portion of the second rack screw, the rotatable adjustment knob moveable between a first position in which the internal thread is configured to engage the thread on the outer surface of the second rack screw and cause the second rack screw to move proximally to cause proximal longitudinal movement of the second longitudinal movement wire and a second position in which the internal thread is configured to move the second rack screw in a distal direction to release tension on the second longitudinal movement wire, wherein the elastomeric member is configured to receive contrast media therewithin causing the elastomeric member to expand and becomes visible on an image generated during an MRI scan.

While multiple embodiments, objects, features and advantages are disclosed, still other embodiments of the invention will become apparent to those of ordinary skill in the art from the following detailed description taken together with the accompanying figures, the foregoing being illustrative and not restrictive.

DETAILED DESCRIPTION OF THE INVENTION

Numerous structural variations of an MR compatible steerable elastomeric member sheath in accordance with the invention are contemplated and within the intended scope of the invention. Those of skill in the art will appreciate that the exemplary steerable elastomeric member sheath may be coupled to other types of steerable sheath shafts having control handles. Therefore, for purposes of discussion and not limitation, an exemplary embodiment of the MR compatible steerable elastomeric member sheath will be described in detail below.

Referring to the FIGS. like elements have been numbered with like reference numerals.

Referring now toFIG. 1, the control handle10in accordance with the invention includes a cover2as illustrated inFIG. 1. Cover2includes distal portion12, hand-graspable middle region14, and proximal end16. Distal portion12includes aperture18through which steerable sheath shaft100exits. Proximal end16includes rotatable adjustment knob20and port22. Rotatable adjustment knob20is operably coupled to a proximal end (not shown) of steerable sheath shaft100such that rotation of the knob causes movement of steerable sheath shaft100as hereinafter described. Port22includes an aperture therethrough for receiving a medical device such as by way of example an MR-compatible electrode circuit such as that disclosed in U.S. Publn. No. 2011/0046707, the entirety of which is hereby incorporated by reference.

Referring now toFIG. 2Aan exploded view of the control handle10and steerable sheath shaft100in accordance with the invention is shown. Cover2of control handle10includes a first mating portion24and a second mating portion26. Those of skill in the art will appreciate, however, that cover2may include any number of mating portions and still be within the scope of the invention. Each of the first and second mating portions24,26include an inner face30having a plurality of inserts32fixedly coupled to inner face30. As depicted, inserts32include a receiving groove therewithin. When first mating portion and second mating portion are operably coupled, receiving groove34forms a lumen into which steerable sheath shaft100is received. First mating portion24and second mating portion26when mated form an internal recess40at a distal end thereof, which accommodates first and second rack screws201,202. It should be noted that the distal threads236of the first rack screw201, although shown, have no function. First and second rack screws201,202are simply mirror images of each other and the distal threads236of the first rack screw201are present to reduce the cost of manufacturing so that first and second rack screws201,202can be made from the same mold. Control handle10further includes first and second pinion gears204,206, t-valve axle208, first and second pegs210,212, t-valve214, tube retainer216, tube218, and rotatable adjustment knob20. Rotatable adjustment knob20receives seals230, seal cap232and fitting234. First and second pegs210,212are operably coupled to t-valve axle208. Groove41receives pegs210,212. First and second pegs210,212receive pinion gears204and206. Tube218attaches to a stopcock in t-valve which connects to a syringe for flushing or aspirating the steerable catheter.

As may be seen inFIG. 2A, second rack screw202includes proximal threads238on an outer surface thereof. Those of skill in the art will appreciate that “first” and “second” rack screws are relative terms. Those of skill in the art will also appreciate that the control knob20may be positioned distally to first and second rack screws and the orientation of first and second rack screws flipped as will be described below with reference toFIG. 2B. An internal central channel of each of first and second rack screws201,202includes a threaded portion211that threadably receives pinion gears204,206in operation. First and second rack screws201,202include notched portion203,205. First and second pull wires320,340are routed and are operably coupled to ends230,252of each rack screw201,202, respectively. Pinion gears204,206are received by pegs210,212operably coupled to t-valve axle208. T-valve axle208is bonded to sheath shaft100. In operation, posts210,212are received by and move longitudinally on notched portion203,205respectively. This allows threaded pinion gears204,206to be received by and move longitudinally along the threaded central channel of each of first and second rack screws201,202.

As seen inFIG. 2A, rotatable adjustment knob20includes internal threads254circumferentially disposed about an inner wall thereof. Internal threads254will engage the proximal threads238of the second rack screw202. As the rotatable adjustment knob is rotated clock-wise the internal adjustment knob threads254engage the proximal threads238of the second rack screw202causing longitudinal, proximal movement of rack screw202. As the rotatable adjustment knob is rotated counter-clockwise the internal threads (still engaged with the proximal threads238of the second rack screw202) causes longitudinal, distal movement of rack screw202.

Those of skill in the art will appreciate that the orientation of the first and second rack screws may be changed without departing from the scope of the invention. As may be seen inFIG. 2B, second rack screw202′ includes distal threads238′ on an outer surface thereof. An internal central channel of each of first and second rack screws201′,202′ includes a threaded portion211′ that threadably receives pinion gears204′,206′ in operation. First and second rack screws201′,202′ include notched portion203′,205′. First and second pull wires (not shown) are routed and are operably coupled to ends230′,252′ of each rack screw201′,202′, respectively. Pinion gears204′,206′ are received by pegs210′,212′ operably coupled to t-valve axle208′. T-valve axle includes a lumen therewithin that slidably receives sheath shaft100′ at a distal end thereof. In operation, posts210′,212′ are received by and move longitudinally on notched portion203′,205′ respectively. This allows threaded pinion gears204′,206′ to be received by and move longitudinally along the threaded central channel of each of first and second rack screws201′,202′.

As seen inFIG. 2C, rotatable adjustment knob20′ includes internal threads254′ circumferentially disposed about an inner wall thereof. Internal threads254′ will engage the distal threads238′ of the second rack screw202′. As the rotatable adjustment knob20′ is rotated clock-wise the internal adjustment knob threads254′ engage the distal threads238′ of the second rack screw202′ causing longitudinal, proximal movement of rack screw202′. As the rotatable adjustment know is rotated counter-clockwise the internal threads (still engaged with the distal threads238′ of the second rack screw202′) causes longitudinal, distal movement of rack screw202′. Thus, those of skill in the art will appreciate that although the rotatable adjustment knob20′ is positioned distal to the first and second rack screws201′,202′ the operation of the control handle has not changed.

Rotatable adjustment knob20′ ofFIGS. 2B and 2Cincludes grooves500on an outer surface thereof which, in operation, accommodate a plurality of O-rings510(as best seen inFIG. 10) that create a friction fit between the knob20′ and the first mating portion24′ and second mating portion26′ of cover2of control handle10, which has corresponding grooves.

Referring now toFIG. 3, the steerable sheath shaft100in accordance with the invention will now be explained. Steerable sheath shaft100may be used in an MRI environment to deliver a variety of tools such as catheters, guide wires, implantable devices, etc. into cavities and passageways of a patient body. The steerable sheath shaft100includes a deflectable tip portion200that is able to bend at least 180 degrees offset from the longitudinal axis of the catheter sheath shaft100. This flexibility allows the medical professional to make very tight turns to deliver the aforementioned tools to the cavities and passageways of the patient body.

Referring again toFIG. 3a perspective view of an MR compatible steerable sheath that is suitable for use in an MRI environment is depicted. The MR compatible steerable sheath shaft100in accordance with the invention broadly includes tubular shaft120with distal140and proximal ends160. Tubular shaft120includes an outer diameter130, an inner diameter150and defines a central lumen300therewithin. Tubular shaft may be constructed of a variety of polymers such as pebax, polyurethane, nylon, derivatives thereof and combinations of the foregoing.

Distal end14includes transition section180, deflectable tip portion200, and magnetic marker220. Pressure relief holes240,260may be formed in the tubular shaft120at the distal end140. Those of skill in the art will appreciate that while only two pressure relief holes240,260are shown there may any number of pressure relief holes formed and still be within the scope of the invention. When retracting an item housed by the sheath shaft100, such as a catheter or MR active tracking system, pressure may form at the end of the sheath thereby drawing or sucking in tissue. Pressure relief holes240,260are designed to reduce this pressure thereby ameliorating the risk of tissue damage.

Transition section180is optionally included for purposes of manufacturability. The deflectable tip section20has a significantly lower durometer making it more malleable and flexible than the main body portion170of tubular shaft120which has a higher durometer or, in other words, quite stiff. As a consequence, these two sections do not bond to one another well. Transitional section180has a mid-range durometer allowing it to bond well to both the deflectable tip section200and the main body170of the tubular shaft120. Those of skill in the art will appreciate that the transition section180may be of any length desired so as to provide an adequate transition between the distal tip portion200and the main body portion170. In one exemplary embodiment transition section may range from about 0.25 to about 0.75 inches. In addition, those of skill in the art will appreciate that transition section may be eliminated and the deflectable tip section200may be coupled to the main body170of tubular shaft120by means known to those of skill in the art without departing from the spirit of the invention.

Steerable sheath shaft100includes central lumen300therewithin. In one aspect of the invention, the inner diameter150of the tubular shaft120is approximately 6 French or greater but those of skill in the art will appreciate that varying internal diameters may be used depending on the particular application without departing from the scope of the present invention. Central lumen300may include one or more liners (not shown) disposed therewithin to allow for easier movement of instruments therethrough. Liners may comprise materials made from polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), nylons and combinations of the foregoing. Alternatively, the lumen300may be coated with any such polymers. The polymer tubular shaft120may also include one or more passive visualization markers, such as a ferrous or magnetic marker220, disposed circumferentially about the tubular shaft120at one or more locations along the length thereof and/or one or more active visualization markers such as an active tracking coil along the length of the tube. An active tracking coil may comprise one or more small antennas integrated into the device and include traces on a circuit board, coiled wire, and/or a dipole. If an active visualization marker is used, one or more devices may be included in the conductors to mitigate RF field heating may be included. Such devices include chokes, transformers, impedances, and other such devices known to those of skill in the art. One or more fluoroscopy markers (not shown) may also be included along the length of the polymer tubular shaft12.

One or more optional fluid ports (not shown) may be located on the proximal end16of the tubular shaft12to allow for homeostasis of the sheath with the patient body. The fluid port(s) allows access for the user or physician to aspirate blood from the steerable sheath lumen30and flush with saline. Aspirating and flushing of the sheath prevents air from entering the body before and during insertion of a tool and/or catheter.

Referring now toFIG. 4a cut away view of the steerable sheath shaft100in accordance with the invention depicts a reinforcement construct320of the tubular shaft120. As shown, the geometry of the reinforcement construct320is braided but those of skill in the art will appreciate that the reinforcement construct320may comprise other configurations so long as it imparts the necessary deflectability to the tubular shaft120at the distal end. For example the reinforcement geometry may be a coil or a slit tube that mimics a coil or combinations of the foregoing. The reinforcement of the tubular shaft120may extend from the distal end140to the proximal end160or may extend from the deflectable tip section200to approximately the transition section180of the tubular shaft12.

The material used in the reinforcement construct320may be non-metallic such as Kevlar, PEEK, Nylon, fabric, polyimide, fiber optic, silica glass and the like or may also be hybrid of metallic, such as stainless steel, and non-metallic materials. Those of skill in the art will appreciate that, the reinforced polymer tubular shaft140may be segmented and each segment may be constructed with varying flexibility along the segment to provide the user with the ability to deflect the sheath in a region in which the segment is more flexible than in other segments. Varying flexibility and thus deflectability may be accomplished by having braids or coils that have greater braiding or coils per sq. cm than in other segments where the braiding or coiling would be less per sq. cm. Flexibility and deflectability may also be accomplished by the varying durometers as herein described.

Referring now toFIG. 5A, an enlarged view of the proximal end160of the steerable sheath shaft100in accordance with the invention is depicted. Proximal end160of the steerable sheath is operably coupled to control handle10depicted in dashed lines and as hereinafter described. The steerable sheath shaft100in accordance with the invention includes one or more pull-wires320,340which are operably coupled at a pull-wire proximal end342to the control handle10as hereinafter will be described. The portion of the pull-wires320,340that are operably coupled to the control handle exit the tubular body120at opening122. The portion of the pull-wires320,340that are operably coupled to pull ring440(as best seen inFIG. 5B) extend through a lumen constructed from a sheet of polymeric material fastened to an inner portion of tubular shaft120for a length thereof and enter tubular shaft120through entrance holes330,350on opposing sides of tubular shaft120. Pull-wires320,340allow the user to manipulate and deflect the one or more flexible segments along the length of the polymer tubular shaft120and in particular the deflectable tip portion200. In one aspect of the invention, the pull-wires320,340are preferably made of a non-metallic material (Kevlar, PEEK, Nylon, fabric, etc.).

One or more internal pull-wire lumens360are constructed of a flexible, non-metallic material such as PTFE. Internal pull-wire lumens360facilitate smooth manipulation of the pull-wires320,340during actuation. Internal pull-wire lumens360have an outer diameter of approximately 0.12 inches and an inner diameter of approximately 0.010 inches. However, those of skill in the art will appreciate that the dimensions of the internal pull-wire lumens360may vary with the dimensions of both the pull-wires320,340and the tubular shaft120so long as they are dimensioned to house the pull-wires and allow pull-wires to move smoothly during actuation.

Referring toFIG. 5B, a side view of the distal end of the steerable sheath in accordance with the invention is shown. Pull wires320,340are operably coupled at their distal end to an opening440in pull ring442positioned within lumen300at the deflectable tip200end of the steerable sheath shaft100.

Referring now toFIGS. 6-9an exemplary control handle31for operating the steerable sheath is disclosed. As discussed in reference toFIG. 2, control handle310allows the user to control the longitudinal movement of pull-wires320,340which in turn “pull” or deflect the distal end140of the steerable sheath shaft100in opposite directions. Control handle310is positioned on the proximal end of the steerable sheath shaft100and operates longitudinal movement of the pull-wire(s) and correspondingly, directional movement of the steerable sheath shaft100. In one aspect of the invention, control handle310includes paramagnetic or diamagnetic materials or combinations of paramagnetic and diamagnetic materials.

Referring now toFIGS. 6A-7B,FIGS. 7A and 7Bare enlarged views of the control handle ofFIGS. 6A and 6Bdenoted at numeral600,600′. Adjustment knob20,20′ is rotated in the clockwise direction, which causes internal threads254,254′ to engage threads238,238′ of second rack screw202,202′ and cause longitudinal, proximal movement of the second rack screw202,202′. At the same time, the pinion gears are engaged by the longitudinal movement of the second rack screw202,202′. This causes the first rack screw201,201′ to move in the opposite direction, i.e. distally. Distal movement of the first rack screw201,201′ releases tension in the first pull wire320,320′.

As rotatable adjustment knob20,20′ is rotated in the clockwise direction and engages rack screws which in turn engage pinion gears, second pull wire340,340′ is pulled toward the proximal direction as best seen inFIGS. 6A and 6B. In turn, the tension on first pull wire320,320′ is released. As second pull wire340,340′ is pulled in the proximal direction deflectable tip moves in one direction, shown as a downward direction inFIG. 6Aand an upward direction inFIG. 6B; however those of skill in the art will appreciate that the direction of deflectable tip is relative to how or the direction in which the user is holding the handle10. When the t-valve pegs210,210′,212,212′ abut stops205,205′ in second rack screw202,202′ the rack screw202,202′ stops moving and further movement of rotatable adjustment knob20,20′ is halted.

Referring now toFIGS. 8A, 8B and 9A, 9Bthe opposite function is illustrated. Adjustment knob20,20′ is rotated in the counter-clockwise direction, internal threads254,254′ engage threads238,238′ of second rack screw202,202′ causing longitudinal, distal movement. As the rotatable adjustment knob20,20′ continues to be rotated in a counter-clockwise direction, pinion gears204,204′,206,206′ once again operably engage threaded portion211,211′ of first and second rack screws.

As rotatable adjustment knob20,20′ is rotated in the counter-clockwise direction first pull wire320,320′ is pulled toward the proximal direction as best seen inFIGS. 9A and 9B. In turn, the tension on second pull wire340,340′ is released. As first pull wire320,320′ is pulled in the proximal direction deflectable tip moves in the opposite direction, shown as an upward direction inFIG. 9Aand a downward direction inFIG. 9B; however those of skill in the art will appreciate that the direction of deflectable tip is relative to how, or the direction in which, the user is holding the handle10. When the t-valve pegs210,210′,212,212′ abut stops205,205′ in second rack screw202,202′ the rack screw202,202′ stops moving and further movement of rotatable adjustment knob20,20′ is halted.

Referring now toFIGS. 10-23, the control handle and steerable sheath shaft ofFIGS. 1-9has been modified to include a distally located elastomeric member500in accordance with the invention. An exemplary embodiment will use control handle10′ ofFIG. 2Bto describe the invention. The integration of an elastomeric member onto the steerable sheath in accordance with the invention creates a reservoir for the injection of an MRI contrast agent. When the contrast agent is injected into the elastomeric member, the elastomeric member expands and becomes visible on the image generated during the MRI scan. During this process, the sheath, otherwise invisible on the MRI scan, is rendered visible at the location of the contrast filled elastomeric member. Those of skill in the art will appreciate that this technique may also be utilized with a therapy catheter and the like. Like elements in the Figures are labeled with like reference numerals.

Referring now toFIG. 10, a first aspect of the deflectable sheath with elastomeric member500in accordance with the invention is shown. Elastomeric member512circumferentially encompasses the outer diameter of the sheath shaft518. The elastomeric member512includes an axially extending sheath portion514which surrounds the sheath shaft518and creates a lumen coupled to a source of contrast media at one end and is in fluid communication with lumen520at a second opposing end. The shape of the elastomeric member512may be one of many including, but not limited to, circular, conical, square, spherical, elliptical, tapered, dog bone, paddle, offset as best seen inFIGS. 10 through 23. In one aspect as best seen inFIG. 11the elastomeric member512may circumferentially surround the outer diameter of the sheath shaft518. In another aspect, as best seen inFIGS. 14 and 17, the elastomeric member lumen520may comprise one or more tubes523,525that extend along the longitudinal axis of the sheath shaft518and are bonded or otherwise operably coupled thereto. The tubes523,525form a lumen that in is fluid communication at one end with a source of contrast media and with lumen520of elastomeric member512at an opposing end. The elastomeric member512and sheath portion514may be integrally or non-integrally formed. With respect to non-integrally formed embodiments fastening or anchoring the elastomeric member512to the sheath portion514, numerous techniques may be utilized including heat shrinking the elastomeric member512onto the sheath portion514, joining the elastomeric member512to the sheath portion514with adhesive, mechanical means, thermal molding of the elastomeric member512onto the sheath portion514and other methods known to those of skill in the art. In the foregoing embodiments the elastomeric member512and sheath portion514may comprise the same material or may comprise different materials. Alternatively, the sheath514and elastomeric member514may be integrally formed and be of the same material.

A conical shaped elastomeric member512is seen inFIG. 12. The conical shaped has a tapered-end522at the most distal portion of the sheath portion514. Alternatively, the conical shaped elastomeric member512may be coupled to the sheath shaft518and tubes523,525(a single tube or multiple tubes) may fluidly couple lumen512to a source of contrast media. When the elastomeric member512receives contrast media within lumen520, the tapered-end522may indicate the direction of steerable sheath500when in use.FIG. 13depicts a spherical-shaped elastomeric member circumferentially surround the steerable sheath at a distal end thereof. FIG.14depicts the spherical-shaped elastomeric member ofFIG. 13with a single tube lumen523fluidly coupled to elastomeric member lumen520at a first end525and fluidly coupled to a source of contrast media at a second end.FIG. 15is a cross-section of the device ofFIG. 14showing the single tube lumen523.FIG. 16depicts the spherical-shaped elastomer member512ofFIG. 13showing two tube lumen access523,525to the lumen520of elastomeric member512.FIG. 17is a cross-sectional view depicting multiple tube lumen access523,525,527,529to the lumen520of elastomeric member512.

As best seen in the FIGS. the elastomeric member512or multiple elastomeric members may be located at the most distal tip of the sheath512proximate the deflection region of the sheath shaft518. Referring now toFIG. 18Aa single elastomeric member512offset from the longitudinal axis of the sheath shaft518is shown. Multiple elastomeric members may be offset from the longitudinal axis of the sheath514as best seen inFIGS. 18B and 18C. Locating the elastomeric members512in a non-circumferential location on sheath shaft518may impart additional geometrical information to the clinician. For example, the two elastomeric members512that are 180 degrees opposed, as best seen inFIG. 18B, may be positioned such that their shapes are in plane with the deflection plane of the steerable sheath100′, and therefore the clinician may discern more information about the steerable sheath100′ than just the location of the deflectable tip200′. The same could be said of locating just a single offset balloon to one side of the sheath shaft518and in plane with the deflection plane of the steerable sheath100′.

FIGS. 19A and 19Bdepict the deflection region531of the sheath shaft518. Referring now toFIGS. 20 and 21multiple elastomeric members512may be utilized to indicate the direction of the steerable sheath shaft518. As seen inFIGS. 20-21, curve shape and direction may be indicated on the MR image by different elastomeric member shapes. This would be accomplished by locating the elastomeric members512at different positions on the distal section of the sheath shaft514. For example, using three elastomeric members512placed in a spaced apart relationship along the longitudinal axis of the steerable sheath shaft518curve would indication direction of the sheath shaft518to a user. For example, elastomeric members512may be placed at the commencement of the sheath shaft curve534, in the middle of the sheath shaft curve532, and at the distal tip530of the sheath shaft518as best seen inFIGS. 20-21. Alternatively, as seen inFIG. 20, the most proximal elastomeric member512may be conical-shaped. This would indicate to a user which one of the elastomeric members is most proximal on the MR image. Otherwise, the user is viewing the image of three circles and would not be able to discern which direction the steerable sheath100′ is moving, i.e. distally or proximally. Alternatively, the elastomeric members512may increase in size in the proximal direction or in the distal direction. Elastomeric members of different sizes or shapes may indicate, as mentioned above, sheath and curve direction on the MR image. In the various multiple elastomeric member designs in accordance with the invention, a single lumen may be utilized for all three elastomeric members, or, alternatively, each elastomeric member may have its own separate lumen.

Referring now toFIG. 22, an MR image of the heart is shown with a steerable sheath having multiple elastomeric members512,512,512. The curve of the deflectable sheath may be seen as the most distal elastomeric member is deflected slightly toward the left. In this aspect of the invention, the most proximal elastomeric member512may be coned-shaped to indicate to a user the proximal portion of the steerable sheath.

FIG. 23is an illustration of the heart showing a most proximal dog bone-shaped elastomeric member that is utilized to anchor the shaft of the sheath in the atrial or ventricular septum.

Although the present invention has been described with reference to various aspects of the invention, those of ordinary skill in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.