Patent Description:
Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity.

In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart which is of concern. Within the heart, the ability to control the exact position and orientation of the catheter tip is critical and largely determines how useful the catheter is.

Steerable (or deflectable) catheters are generally well-known. For example, <CIT> describes a catheter having a control handle comprising a housing having a piston chamber at its distal end. A piston is mounted in the piston chamber and is afforded lengthwise movement. The proximal end of the catheter body is attached to the piston. A puller wire is attached to the housing and extends through the piston and through the catheter body. The distal end of the puller wire is anchored in the tip section of the catheter. In this arrangement, lengthwise movement of the piston relative to the housing results in deflection of the catheter tip section.

Often it is desirable to have a bidirectional steerable catheter, i.e., a catheter that can be deflected in two directions, typically opposing directions. For example, <CIT> discloses a bidirectional steerable catheter having two puller wires extending through the catheter. The distal ends of the puller wires are anchored to opposite sides of the tip section of the catheter. A suitable bidirectional control handle is provided that permits longitudinal movement of each puller wire to thereby allow deflection of the catheter in two opposing directions.

Also known is a steerable catheter having a tip section deflection mechanism is disclosed in <CIT>, entitled STEERABLE CATHETER WITH IN-PLANE DEFLECTION.

However, the deflection mechanism can be improved upon for reinforced tubing, including braided tubing made by the Maypole or sinuous method <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT> disclose steerable catheters which comprise a biasing member to define a preferred plane of bending.

Catheter shafts typically comprise an elongated tubular construction having a single, axial or central lumen. They are flexible, i.e., bendable, but substantially non-compressible along their length. Catheter shafts often have an outer wall made of polyurethane or PEBAX that has an imbedded braided mesh of stainless steel or the like to increase torsional stiffness of the catheter shaft so that rotation at one end (for example, by rotation of a control handle), the shaft will rotate in a corresponding manner through to the other end.

The braided mesh is typically constructed from at least two strands which are wound in oppositely directed helical paths that pass over and under one another in a prescribed sequential interval such as by a maypole or sinuous braiding machine. Maypole-type braiders for the reinforcing of hose and other tubular products and for the production of ropes, cables and the like are known and patented. Patents include <CIT>, <CIT>and <CIT>. More modern braiding machines have a mechanism for directing strand supply carrier spindles in intersecting serpentine paths around a braiding point. The mechanism includes a circle of carrier spindle drivers, where each carrier spindle has independent rotation from the driver it is driven thereby so that there is no abrupt change of direction of rotation as it is transferred from a rotor rotating in one direction to a rotor rotating in the opposite direction. Moreover, the braider is also configured so that a strand pay-off point of each carrier is maintained substantially on a line drawn through the center of the spindle and the braiding point during the travel of the carrier spindles in their serpentine paths around the braiding point. Suitable braiding machines for manufacturing reinforced tubing are available from Steeger USA, Inman, South Carolina, USA.

Although braided and reinforced tubing, and catheter shafts constructed therefrom have better torsional characteristics which minimize kinking and twisting of the shafts, there is need for a tubing construction that integrates the various layers and reinforcement components with a biasing mechanism to promote in-plane deflection, that is, where deflection of at least a portion of the shaft is in the same plane in which the pair of puller wires span. Such a catheter would have greater resistance to out-of-plane deflections to provide more predicable and precise steering of the catheter tip. Accordingly, a need exists for a catheter having an integrated tubing construction that is biased for in-plane bi-directional deflection.

The present invention is directed to an improved steerable catheter as defined in the independent claim <NUM>.

These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:.

In accordance with a feature of the present invention, there is provided a steerable electrode catheter with mapping and/or ablation capabilities, wherein at least a section of the catheter is biased for in-plane bi-directional deflection. As shown in the embodiment of <FIG>, the catheter <NUM> comprises an elongated catheter body <NUM>, a deflectable intermediate section <NUM> extending from a distal end of the catheter body <NUM>, and a tip section <NUM> extending from a distal end of the intermediate section <NUM>. A control handle <NUM> is provided at a proximal end of the catheter body <NUM>. Examples of suitable control handles for use in the present invention are described in <CIT>, <CIT>, and <CIT>. In the illustrated embodiment, the control handle <NUM> has a deflection knob <NUM> by which an operator can steer the tip section <NUM> via bi-directional, in-plane deflection of the intermediate section <NUM>.

With reference to <FIG> and <FIG>, the catheter body <NUM> comprises an elongated tubular construction having a single, central or axial lumen <NUM>. The catheter body <NUM> is flexible, i.e., bendable, but substantially non-compressible along its length. The catheter body <NUM> can be of any suitable construction and made of any suitable material. A presently preferred construction comprises an outer wall <NUM> made of a polyurethane or nylon. The outer wall <NUM> comprises an imbedded braided mesh of stainless steel or the like (not shown) to increase torsional stiffness of the catheter body <NUM> so that, when the control handle <NUM> is rotated, the tip sectional of the catheter <NUM> will rotate in a corresponding manner.

The outer diameter of the catheter body <NUM> is not critical, but is preferably no more than about <NUM> french. Likewise the thickness of the outer wall <NUM> is not critical. The inner surface of the outer wall <NUM> is lined with a stiffening tube <NUM>, which can be made of any suitable material, preferably polyimide. The stiffening tube, along with the braided outer wall <NUM>, provides improved torsional stability while at the same time minimizing the wall thickness of the catheter, thus maximizing the diameter of the single lumen. The outer diameter of the stiffening tube <NUM> is about the same as or slightly smaller than the inner diameter of the outer wall <NUM>. Polyimide tubing is one preferred material because it may be very thin walled while still providing very good stiffness. This maximizes the diameter of the central lumen <NUM> without sacrificing strength and stiffness. Polyimide material is typically not used for stiffening tubes because of its tendency to kink when bent. However, it has been found that, in combination with an outer wall <NUM> of polyurethane, nylon or other similar material, particularly having a stainless steel braided mesh, the tendency for the polyimide stiffening tube <NUM> to kink when bent is essentially eliminated with respect to the applications for which the catheter is used.

In one example, the catheter has an outer wall <NUM> with an outer diameter of about <NUM>,<NUM> (<NUM>,<NUM> inch) and an inner diameter of about <NUM>,<NUM> (<NUM>,<NUM> inch) and a polyimide stiffening tube having an outer diameter of about <NUM>,<NUM> (<NUM>,<NUM> inch) and an inner diameter of about <NUM>,<NUM> (<NUM>,<NUM> inch).

In one example, a first glue joint <NUM> is made between the stiffening tube <NUM> and the outer wall <NUM> by a fast drying glue, e.g. cyanoacrylate. Thereafter a second glue joint <NUM> is formed between the proximal ends of the stiffening tube <NUM> and outer wall <NUM> using a slower drying but stronger glue, e.g., polyurethane.

As illustrated in <FIG> and <FIG>, the deflectable intermediate section <NUM> extends from a distal end of the catheter body <NUM>. The intermediate section <NUM> is configured with multiple off axis lumens <NUM>, <NUM>, <NUM> and <NUM>, as described further below, for carrying various components, including two puller wires <NUM> to enable deflection. Other components include lead wires <NUM>, thermocouple wires <NUM> and <NUM>, a sensor cable <NUM> and irrigation tubing <NUM>.

With further reference to <FIG>, one embodiment of the intermediate section <NUM> has an integrated tubing construction <NUM> having an inner layer <NUM>, a reinforcing or braided mesh <NUM>, a pair of bias members <NUM>, and an outer wall <NUM>. In one detailed example, the inner layer <NUM> includes a melt extrudable polymeric material, e.g., nylon or polyimide, and the outer wall <NUM> includes a melt extrudable polymeric material, e.g., nylon, polyurethane or PEBAX. Both materials are preferably extruded using known melt or paste extrusion techniques. The inner layer <NUM> has a wall thickness between about <NUM>,<NUM> (<NUM>,<NUM> inch) and <NUM>,<NUM> (<NUM>,<NUM> inch), preferably between about <NUM>,<NUM> (<NUM>,<NUM> inch) and <NUM>,<NUM> (<NUM>,<NUM> inch), and more preferably between about <NUM>,<NUM> (<NUM>,<NUM> inch) and <NUM>,<NUM> (<NUM>,<NUM> inch). The outer wall <NUM> has a wall thickness between about <NUM>,<NUM> (<NUM>,<NUM> inch) and <NUM>,<NUM> (<NUM>,<NUM> inch), preferably between about <NUM>,<NUM> (<NUM>,<NUM> inch) and <NUM>,<NUM> (<NUM>,<NUM> inch), and more preferably between about <NUM>,<NUM> (<NUM>,<NUM> inch) and <NUM>,<NUM> (<NUM>,<NUM> inch).

The braided mesh <NUM> can be applied over the inner layer <NUM> through the use of a braiding machine well known in the art. The machine includes a plurality of spools of which carry the strands or fibers which are woven or braided. The fibers are fed through the machine to a braiding area in which the fibers are braided or wound about the inner layer <NUM>. Alternatively, the braided mesh <NUM> also can be constructed in a pre-made, sock-like fashion which is then mounted on the inner layer <NUM>. The strands or fibers of the braided mesh can be flat wire or sheet wire made of metal, plastic, ceramic or glass that is flexible at least a high modulus of elasticity, if not shape memory and/or superelastic properties. In one detailed example, the material should have a high percentage of strain before the material yields. Some suitable materials include stainless steel, Nitinol, and metastable titanium-molybdenum base alloy, and combinations thereof. Other suitable materials include boron ceramic fibers, carbon fiber, and fiberglass. Suitable plastics include aramid fibers, polyester fibers, liquid crystal polymer fibers, such as KEVLAR, NOMEX, DACRON, SPECTRA and VECTRAN.

In one example, the braided mesh <NUM> comprises interwoven helical members, typically twelve, sixteen or twenty-four interwoven helical members, half extending in one direction and the other half extending in the in the counter direction. The tightness or braid angle of the helical members to a line parallel with the axis of the catheter and intersecting the helical members is not critical, but is preferably about <NUM> degrees.

In the illustrated example of <FIG> and <FIG>, there are two elongated bias members or wires <NUM>, each of which is positioned at an opposite side of the intermediate section <NUM> and extends along the length of the section <NUM> between the inner layer <NUM> and the braided mesh <NUM>. Opposing each other across a diameter of the tubing construction, the bias members <NUM> define a transverse axis or plane <NUM> that runs along the longitudinal axis of the intermediate section <NUM>, the significance of which is discussed further below. The bias members <NUM> can be wires made of stainless steel with or without shape memory (e.g., nitinol) and any other suitable material such as those used for the braided mesh <NUM>. Additional suitable materials include ceramic, carbon fiber, metallic elements, alloys, plastics, or combinations thereof.

The extrusion of the outer wall <NUM> on the inner layer <NUM>, the bias members <NUM> and the braided mesh <NUM> integrates or otherwise bonds the bias members <NUM> and the braided mesh <NUM> to the inner layer <NUM>. That is, when extruded, the material extruded to form the outer wall <NUM> melts and flows into the gaps or interstitual spaces of the braided mesh <NUM> and the bias members <NUM> which integrally forms them to the inner layer <NUM> for a layered but integrated construction. Accordingly, relative movement between the braided mesh <NUM>, the bias members <NUM> and the inner layer <NUM> is minimal, if any, to provide improved flexural and torsional stability along the intermediate section <NUM>. In particular, the generally diametrically opposing arrangement of the integrated bias members <NUM> resists flexing of the tubing construction in the plane <NUM> which in tum biases the tubing construction to flex in a plane that is perpendicular to the plane <NUM>.

In the disclosed example, the cross-section of each of the pair of bias members <NUM> is generally identical in shape and size for symmetrical bias. The illustrated cross- sectional shape is circular but it is understood that the shape can be any suitable shape, including triangular, rectangular or any other polygonal shape. It is also understood that the cross-section shape of each pair need not be identical in size or shape to each other. Moreover, more than two bias members can be used and the arrangement can be asymmetrical, for example, with two weaker bias members on one side and a single stronger bias member on the other, so the overall or combined effect is balanced or purposefully unbalanced. In the present invention, the bias member(s) do not extend linearly along the length of the affected catheter, that is, the bias members can sinuate or have obtuse or acute angles to impart nonlinear deflection characteristics to the catheter. It is understood that depending on the application of the catheter shaft, the plurality, shape and/or size of the bias members can differ for different deflection characteristics, including a spiral or corkscrew deflection configuration.

In the illustrated embodiment of <FIG> and <FIG>, the inner layer <NUM> provides multiple off-axis lumens, including the lumens <NUM>, <NUM>, <NUM> and <NUM>. As illustrated in <FIG>. , the second lumen <NUM> carries the lead wires 40T and 40R, respectively, for a tip electrode <NUM> and ring electrode(s) <NUM>, the thermocouple wires <NUM> and <NUM> and the cable <NUM> for an electromagnetic location sensor <NUM> housed in the tip section <NUM>. The fourth lumen <NUM> carries an irrigation tubing <NUM> to transport fluid along the catheter, including fluid to the tip section <NUM>.

In accordance with an example the first and third lumens <NUM> and <NUM> are dedicated to carrying the puller member or wires <NUM>, because a plane <NUM> in which these lumens lie purposefully perpendicular to the transverse plane <NUM> defined by the bias members <NUM>. With the bias members <NUM> resisting flexure of the intermediate section <NUM> in the plane <NUM>, the intermediate section <NUM> is biased to exhibit a more planar movement within the plane <NUM> when deflected by the puller wires <NUM>, thus promoting "in-plane" deflection, that is, deflection within the plane defined by the lumens <NUM> and <NUM> and the puller wires <NUM>.

With the intermediate section <NUM> so configured, movement of the puller wires <NUM> by an operator's manipulation of the control handle <NUM> allows for more predictable bi-directional deflection of the intermediate section <NUM> and hence more precise control and steering of the tip section <NUM> during ablation and/or mapping. It is understood that the precise size of the lumens is not critical and will depend on the sizes of the components being carried by the lumens.

Means for attaching the catheter body <NUM> to the intermediate section <NUM> is illustrated in <FIG> and <FIG>. The proximal end of the intermediate section <NUM> comprises an outer circumferential notch <NUM> between the inner layer <NUM> and the outer layer <NUM> that receives the inner surface of the outer wall <NUM> of the catheter body <NUM>. This junction may be secured by glue or the like <NUM>.

If desired, a spacer (not shown) can be located within the catheter body between the distal end of the stiffening tube <NUM> (if provided) and the proximal end of the intermediate section <NUM>. The spacer provides a transition in flexibility at the junction of the catheter body <NUM> and intermediate section <NUM>, which allows this junction to bend smoothly without folding or kinking. A catheter having such a spacer is described in <CIT>.

At the distal end of the intermediate section <NUM> is the tip section <NUM> that is connected to intermediate section by a connective tubing <NUM>. In the illustrated embodiment of <FIG> and <FIG>, the connective tubing <NUM> has a single lumen 47which allows passage of the lead wires 40T and 40R, the thermocouple wires <NUM> and <NUM>, the electromagnetic sensor cable <NUM> and the irrigation tubing <NUM> from the intermediate section <NUM> to the tip section <NUM>. The single lumen <NUM> allows these components to reorient themselves from their respective lumens in the intermediate section <NUM> toward their location in the tip section <NUM>. As shown, various components can criss-cross each other to align themselves properly within the tip section <NUM>.

Means for attaching the intermediate section <NUM> to the connective tubing <NUM> is illustrated in <FIG> and <FIG>. The proximal end of the connective tubing <NUM> comprises an outer circumferential notch <NUM> that receives the inner surface of the tubing construction <NUM> between the outer layer <NUM> and the inner layer <NUM>. This junction may be secured by glue or the like <NUM>.

The tip electrode <NUM> as shown in <FIG> has a distal end <NUM> configured with an atraumatic design for contact with tissue and tissue ablation as appropriate. Received in a distal end of the connective tubing <NUM>, a trepanned proximal end <NUM> of the tip electrode has a proximal surface in which blind holes <NUM>, <NUM> and <NUM> are configured for receiving, respectively, a distal end of a lead wire 40T for the energizing the tip electrode, distal ends of the thermocouple wires <NUM> and <NUM> for sensing temperature at the tip electrode, and a distal end of the electromagnetic sensor <NUM>. These distal ends are anchored in the blind holes as known in the art. A fluid passage <NUM> is formed in the tip electrode extending along its longitudinal axis. A proximal end of the fluid passage receives a distal end of the irrigation tubing <NUM> which is adapted to transport fluid into the fluid passage <NUM>. Transverse branches <NUM> are provided to allow fluid to travel outside the tip electrode via ports <NUM> to, for example, irrigate and cool the tip electrode <NUM> and/or the ablation tissue site. Proximal the tip electrode <NUM>, one or more ring electrodes <NUM> (uni-polar or bi-polar for mapping) can be mounted on the connective tubing <NUM>, each with a respective lead wire 40R.

The ring electrode(s) <NUM> are connected to lead wires 40R and the tip electrode <NUM> is connected to lead wire 40T. The lead wires <NUM> extend proximally from the tip section <NUM> through the lumen <NUM> of the connective tubing <NUM>, the lumen <NUM> of the intermediate section <NUM>, the central lumen <NUM> of the catheter body <NUM>, and the control handle <NUM>, and terminate at their proximal end in a connector <NUM> so that signals can be sent to an appropriate signal processing unit (not shown) and the electrodes can be connected to a source of ablation energy (not shown), including RF. The portion of the lead wires extending through the central lumen <NUM> of the catheter body <NUM>, and proximal end of the second lumen <NUM> can be enclosed within a protective sheath (not shown), which can be made of any suitable material, preferably polyimide. The protective sheath is anchored at its distal end to the proximal end of the intermediate section <NUM> by gluing it in the lumen <NUM> with polyurethane glue or the like.

Each lead wire 40R is attached to its corresponding ring electrode by any suitable method. A preferred method for attaching a lead wire to a ring electrode <NUM> involves first making a small hole through the wall of the connective tubing <NUM>. Such a hole can be created, for example, by inserting a needle through the non-conductive covering sufficiently to form a permanent hole. The lead wire is then drawn through the hole by using a microhook or the like. The end of the lead wire is then stripped of any coating and welded to the underside of the ring electrode, which is then slid into position over the hole and fixed in place with polyurethane glue or the like. Alternatively, each ring electrode is formed by wrapping a lead wire around the non-conductive covering a number of times and stripping the lead wire of its own insulated coating on its outwardly facing surfaces. More alternatively, the ring electrodes can be formed by coating the tubing with an electrically conducting material, like platinum, gold and/or iridium. The coating can be applied using sputtering, ion beam deposition or an equivalent technique.

The thermocouple wires <NUM> and <NUM> extend from their distal ends anchored in the tip electrode <NUM>, through the single lumen <NUM> of the connective tubing <NUM>, through the second lumen <NUM> of the intermediate section <NUM>, through the central lumen <NUM> of the catheter body <NUM>, and into the control handle <NUM> where its proximal end terminates in the connector <NUM> at the proximal end of the control handle <NUM>.

The cable <NUM> of the electromagnetic position sensor <NUM> extends proximally through the lumen 47of the connective tubing <NUM>, through the second lumen <NUM> of the intermediate section <NUM>, through the central lumen <NUM> of the catheter body <NUM>, and into the control handle <NUM>. The electromagnetic sensor cable <NUM> comprises multiple wires encased within a plastic covered sheath. In the control handle <NUM>, the sensor cable <NUM> is connected to a circuit board (not shown). The circuit board amplifies the signal received from the electromagnetic sensor and transmits it to a computer in a form understandable by the computer. Suitable electromagnetic sensors for use with the present invention are described, for example, in <CIT> (entitled "Miniaturized Position Sensor") and <CIT>, <CIT>,<CIT>, <CIT>, <CIT>, and <CIT>.

The irrigation tubing <NUM> extends proximally from the tip electrode <NUM> through the central lumen <NUM> of the connective tubing <NUM>, through the fourth lumen <NUM> of the intermediate section <NUM>, through the central lumen <NUM> of the catheter body <NUM> and through the control handle <NUM>. Saline or other suitable fluid is introduced into the irrigation tubing <NUM> through a luer hub <NUM> or the like at the proximal end of the control handle <NUM>. The luer hub <NUM> is connected to a flexible plastic tubing <NUM>, e.g., made of polyimide. The plastic tubing <NUM> is attached to the proximal end of the irrigation tubing, preferably within the handle <NUM>, as shown in <FIG>. Alternatively, the tubing <NUM> can be connected to a suction source (not shown) to permit aspiration of fluid from the region being ablated.

Each puller wire <NUM> extends from the control handle <NUM>, through the central lumen <NUM> in the catheter body <NUM> and into a different one of the first and third lumens <NUM> and <NUM> of the inner layer <NUM> of the intermediate section <NUM>, as shown in <FIG> and <FIG>. The puller wires <NUM> is made of any suitable material, such as stainless steel or Nitinol. Preferably each puller wire has a coating, such as a coating of Teflon. or the like. Each puller wire has a diameter preferably ranging from about <NUM>,<NUM> (<NUM>,<NUM> inch) to about <NUM>,<NUM> (<NUM>,<NUM> inch). Both of the puller wires have the same diameter.

Each puller wire <NUM> is anchored at its proximal end in the control handle <NUM> such that manipulation of controls, for example, the deflection knob <NUM>, moves the puller wires to cause deflection of the intermediate section <NUM>. In that regard, each puller wire is anchored at its distal end in a side wall at or near a distal end of the intermediate section <NUM> by means of a T-bar anchor constructed of a metal tube <NUM>, e.g., a short segment of hypodermic stock, which is fixedly attached, e.g., by crimping, to the distal end of the puller wire, and a crosspiece <NUM> soldered or welded in a transverse arrangement to a flattened distal end of the tube <NUM>. T-bar anchors are described in <CIT> and <CIT>. Other means for anchoring the puller wires <NUM> in the intermediate section <NUM> would be recognized by those skilled in the art and are included within the scope of the invention, including anchoring the distal end in blind holes provided at the proximal end of the tip electrode <NUM>.

The disclosed embodiment of the catheter <NUM> further comprises two compression coils <NUM>, each in surrounding relation to a corresponding puller wire <NUM> in the catheter body <NUM>, as shown in <FIG> and <FIG>. In the illustrated embodiment, each compression coil is made of any suitable metal, such as stainless steel, and is tightly wound on itself to provide flexibility, i.e., bending, but to resist compression. The inner diameter of each compression coil is slightly larger than the diameter of its associated puller wire <NUM>. For example, when a puller wire <NUM> has a diameter of about <NUM>,<NUM> (<NUM>,<NUM> inch), the corresponding compression coil <NUM> preferably has an inner diameter of about <NUM>,<NUM> (<NUM>,<NUM> inch). A coating on the puller wires <NUM> allows them to slide freely within the compression coil <NUM>. The outer surface of each compression coil <NUM> is covered along most of its length by a flexible, non-conductive sheath <NUM> to prevent contact between the compression coil <NUM> and the lead wire(s) <NUM> within the central lumen <NUM>. In one embodiment, the non-conductive sheath <NUM> is made of thin-walled polyimide tubing.

The compression coils <NUM> are secured within the catheter body <NUM> with polyurethane glue or the like. Each compression coil <NUM> is anchored at its proximal end to the proximal end of the stiffening tube <NUM> in the catheter body <NUM> by a glue joint (not shown). In the depicted embodiment of <FIG>, the distal ends of the compression coils <NUM> extend into the lumens <NUM> and <NUM> of the intermediate section <NUM> and are anchored at their distal ends to the proximal end of the intermediate section by a glue joint <NUM>. Alternatively, where a stiffening tube <NUM> is not used, each compression coil at its proximal and distal ends can be anchored directly to the outer wall <NUM> of the catheter body <NUM>.

In the embodiment of <FIG> and <FIG>, within the off-axis lumens <NUM> and <NUM>, each puller wire <NUM> is surrounded by a plastic sheath <NUM>, preferably made of Teflon. The plastic sheaths <NUM> prevent the puller wires from cutting into the inner layer <NUM> of the intermediate section <NUM> when deflected. Each sheath <NUM> spans generally the length of the intermediate section <NUM>. Alternatively, each puller wire <NUM> can be surrounded by a compression coil where the turns are expanded longitudinally, relative to the compression coils extending through the catheter body, such that the surrounding compression coil is both bendable and compressible.

In a detailed embodiment, longitudinal movement of a puller wire <NUM> relative to the catheter body <NUM>, which results in deflection of the tip section <NUM> in the direction of the side of the intermediate section to which that puller wire extends, is accomplished by suitable manipulation of the control handle <NUM>. Additional suitable bidirectional control handles for use in the present invention is described in application Serial. No.<CIT> and entitled "Steerable Catheter with a Control Handle Having a Pulley Structure", and in <CIT>, <CIT>, <CIT>, and <CIT>.

As shown in the embodiment of <FIG>, the lumens <NUM> and <NUM> carrying the puller wires <NUM> lie on the plane <NUM> that is generally perpendicular to a transverse plane <NUM> in which the two bias members <NUM> lie. As such, deflection of the intermediate section <NUM> as accomplished by longitudinal movement of the puller wires <NUM> is generally planar in that the intermediate section <NUM> (along with the tip <NUM>) remains generally within the plane <NUM>.

With reference to <FIG>, in an alternate embodiment of the integrated tubing construction <NUM>, the bias members <NUM> can be situated outside of the braided mesh <NUM> so that the bias members are integrated between the outer wall <NUM> and the braided mesh <NUM>. Because the outer wall <NUM> is extruded, the material forming the outer wall melts and flows into the gaps or interstitual spaces of the braided mesh <NUM> and the bias members <NUM> which integrally forms them to the inner layer <NUM>.

As another alternate embodiment, the inner layer <NUM> need not provide multiple lumens, but can be formed with only a central lumen, as shown in <FIG>, as desirable or appropriate, such as for a catheter body or any section of the catheter <NUM>, including the deflectable intermediate section where components extending therethrough including the puller wires <NUM> float in the central lumen or can be routed through separate tubings <NUM> that are fixedly secured in place within the central lumen by glue or the like.

Relative movement between the braided mesh <NUM>, the bias members <NUM> and the inner layer <NUM> is minimal, if any, so as to enable the tubing construction to have a more planar deflection characteristic, yet with all the benefits of flexural and torsional stability. It is further understood that most catheter tubing can be retrofitted with bias members of the present invention. Extrusion of an outer layer over the bias members sufficiently integrates the bias members into the preexisting catheter tubing to provide biased in-plane bi-directional deflection.

Claim 1:
A catheter (<NUM>) comprising:
an elongated catheter body (<NUM>),
a deflectable section (<NUM>) distal the catheter body, the section including an inner layer (<NUM>) and an outer layer (<NUM>), and a braided mesh (<NUM>) between the inner and the outer layers, the section also having at least two elongated bias members (<NUM>) integrated between the inner and the outer layers, the bias members extending non-linearly along opposing locations of the section and lying on a plane, wherein the bias members sinuate or have acute or obtuse angles to impart nonlinear deflection characteristics to the catheter;
at least one puller wire (<NUM>) extending through the catheter body and the section;
a tip section (<NUM>) distal the catheter body, the tip section adapted for tissue ablation;
and
a control handle (<NUM>) at a proximal end of the catheter body, adapted for an operator to manipulate deflection of the section via the puller wire,
wherein the bias member resists flexure within the plane with the section is deflected.