Patent Publication Number: US-2022226040-A1

Title: High voltage steerable catheter

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The subject application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 63/137,855 filed Jan. 15, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The subject invention is directed to a catheter for cardiac procedures, and more particularly, to a high voltage wiring layout for a steerable catheter used in cardiac ablation or cardioversion procedures. 
     2. Description of Related Art 
     Cardiac arrhythmia or an abnormal heart rhythm can cause problems such as fainting, stroke, heart attack, and even sudden cardiac death. Treatments for the condition include electrical cardioversion and cardiac ablation. In a cardioversion procedure, a high-energy shock is sent to the heart to reset a normal rhythm. In a cardiac ablation procedure, an electrophysiology (EP) catheter is deployed intravenously to map out and ablate the tissue in the heart that is allowing the incorrect electrical signals to cause an abnormal heart rhythm. 
     The catheter devices utilized in these procedures have conductors that y high voltage energy connected electrodes that deliver high energy shocks to heart tissue for either cardioversion or pulsed ablation therapy. It is necessary to insulate these high voltage wires to prevent shorts from occurring during a procedure. In the past, manufacturers have placed polyimide tubing over each wire in the catheter shaft to prevent arcing. However, wiring layouts are often complex and polyimide tubing cannot effectively cover all of the wires inside the catheter, making them susceptible to shorts. Therefore, there is a need in the art for a solution to this problem, so as to provide a safer product. 
     SUMMARY OF THE DISCLOSURE 
     The subject invention is directed to a new and useful high voltage catheter for use in cardiac ablation or cardioversion procedures, which includes a handle assembly, an elongated tubular shaft extending distally from the handle assembly and an electrode assembly operatively associated with a distal end portion of the tubular shaft for delivering high voltage energy to cardiac tissue. A plurality of conductive wires extend from the handle assembly through the tubular shaft to the electrode assembly to carry high voltage energy thereto. 
     Preferably, each conductive wire has a wire gauge of AWG 40, is formed from a nickel based alloy and is coated with insulation having a thickness that is greater than a conventional wire insulation thickness to provide enhanced dielectric performance. More particularly, each conductive wire is coated with insulation having a thickness that is at least 2 to 3 times greater than a conventional wire insulation thickness. Consequently, the insulation on each conductive wire is rated for dielectric performance to 10 kV. 
     The electrode assembly includes a plurality of longitudinally spaced apart electrode rings formed from a platinum iridium material for electrophysiological mapping, electrical cardioversion and/or pulsed ablation. A respective conductive wire from the plurality of conductive wires is laser welded to an inner diameter of each electrode ring. The handle assembly is operatively associated with a set of high voltage connectors that are rated to 7 kV, and conductive wires extend between the handle assembly and the high voltage connectors. 
     The handle assembly includes a rotatable bi-directional steering mechanism that is adapted and configured to deflect the distal end portion of the tubular shaft. A pair of non-conductive steering cables extend from the rotatable bi-directional steering mechanism in the handle assembly to the distal end portion of the shaft to facilitate deflection by pulling in either direction. Preferably, the non-conductive steering cables are formed from Kevlar® thread. The rotatable bi-directional steering mechanism has a circular body, and the steering cables are anchored to the circular body on diametrically opposed bobbins by respective set screws. 
     The subject invention is also directed to a steerable catheter, which includes a handle assembly, an elongated tubular shaft extending distally from the handle assembly, and a rotatable bi-directional steering mechanism in the handle assembly that is adapted and configured to deflect the distal end portion of the tubular shaft, wherein a pair of non-conductive steering cables extend from the steering mechanism to the distal end portion of the shaft. 
     The subject invention is also directed to a steerable high voltage catheter, which includes a handle assembly, a tubular shaft extending distally from the handle assembly, an electrode assembly associated with a distal end portion of the tubular shaft for delivering high voltage energy to cardiac tissue, wherein the electrode assembly includes a plurality of longitudinally spaced apart electrode rings formed from a platinum iridium material. 
     The steerable high voltage catheter further includes a plurality of conductive wires extending from the handle assembly through the tubular shaft to the electrode assembly to carry high voltage energy thereto, wherein each conductive wire has a wire gauge of AWG 40, is formed from a nickel based alloy is coated with insulation having a thickness that is at least 2 to 3 times greater than greater than a conventional wire insulation thickness. 
     The steerable high voltage catheter also includes a rotatable bi-directional steering mechanism within the handle assembly that is adapted and configured to deflect the distal end portion of the tubular shaft, wherein a pair of non-conductive steering cables extend from the steering mechanism to the distal end portion of the shaft, and wherein each steering cables is formed from Kevlar® thread. 
     These and other features of the steerable high voltage catheter of the subject invention will become more readily apparent to those having ordinary skill in the art to which the subject invention appertains from the detailed description of the preferred embodiments taken in conjunction with the following brief description of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those skilled in the art will readily understand how to make and use the steerable high voltage catheter of the subject invention without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to the figures wherein: 
         FIG. 1  is a perspective view of the steerable high voltage catheter of the subject invention, with the steering mechanism in the handle assembly and the electrode assembly at the distal end portion of the shaft removed for ease of illustration; 
         FIG. 2  is a perspective view of the electrode assembly at the distal end portion of the shaft; 
         FIG. 3  is partial perspective view of the electrode assembly shown in  FIG. 2 , wherein the material of the shaft is removed for ease of illustration; 
         FIG. 4  is an enlarged perspective view of a portion of an insulated conductive wire; electrical conductor; 
         FIG. 5  is an enlarged perspective view of the handle assembly shown in  FIG. 1 , illustrating the plurality of conductive wires leading into the shaft; and 
         FIG. 6  is partial top plan view of the handle assembly illustrating to the rotatable steering mechanism, with the steering cables anchored thereto. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings wherein like reference numerals identify similar structural features of the subject invention, there is illustrated in  FIG. 1  a steerable high voltage catheter for use in cardiac ablation or cardioversion procedures, which is designated generally by reference numeral  10 . 
     The catheter  10  includes a proximal handle assembly  12  and an elongated tubular shaft  14  extending distally from a nose piece  16  associated with a distal end portion of the handle assembly  12 . As best seen in  FIG. 2 , an electrode assembly  20  is operatively associated with a distal end portion of the tubular shaft  14  for delivering high voltage energy to cardiac tissue. The electrode assembly  20 , which will be described in greater detail below with respect to  FIG. 3 , includes a plurality of electrode rings  70 ,  80  for electrophysiological mapping, electrical cardioversion and/or pulsed ablation. 
     With continuing reference to  FIG. 1 , a high voltage connector assembly  40  is operatively associated with a proximal end portion of the handle assembly  12  for connection with power supply cables (not shown). The connector assembly  40  includes three (3) separate connectors  42   a - 42   c  that are each rated to 7 kV. The high voltage connectors  42   a - 42   c  extend to a junction coupling  44  by way of respective flexible wire conduits  46   a - 46   c . The junction coupling  44  is connected to a fitting  48  that extends from the proximal end of the housing assembly  12  by way of a flexible conduit  50 . 
     The fitting  48  leads to a tubular conduit  52  located within the interior cavity  18  of handle assembly  12  for accommodating the plurality of high voltage insulated conductive wires  60  that emanate from the connector assembly  40 , as best seen in  FIG. 5 . The insulated conductive wires  60  extend into an elongated guide tube  62  that leads from the interior cavity  18  of handle assembly  12 , through the elongated tubular shaft  14  of catheter  10 . 
     A luer fitting  54  also extends from the proximal end portion of the handle assembly  12  for connecting the handle assembly  12  to a source of suction or irrigation, for example. An irrigation/suction conduit  56  extends from the fitting  54 , through the interior cavity  18  of handle assembly  12  to the elongated guide tube  62 . The conduit  56  preferably communicates with one or more ports (not shown) associated with a distal end portion of the elongated shaft  14  of catheter  10 . 
     Referring now to  FIG. 3 , the plurality of insulated conductive wires  60  extend from the handle assembly  12  through the tubular shaft  14  to the electrode assembly  20 , in order to carry high voltage energy thereto. Preferably, the insulated conductive wires  60  are Nickel based wires, such as, for example, Nichrome wires comprised primarily of nickel and chromium, which exhibit low resistivity characteristics. These conductive wires  60  are preferably 40 gauge wire (AWG 40), although other wire gauges could be employed. Also, in accordance with the subject invention, each insulated conductive wire  60  is coated with insulation having a thickness or build that is greater than a conventional wire insulation thickness to provide enhanced dielectric performance. More particularly, with reference to  FIG. 4 , each insulated conductive wire  60  includes a conductor  64  coated with insulation  66  having a thickness or build that is at least 2 to 3 times greater than a conventional wire insulation thickness. Consequently, the insulation  64  of each conductive wire  60  is rated for dielectric performance to 10 kV. 
     Those skilled in the art will appreciate that insulation thickness, or build, is the measurement of coating that has been added to the circumference of a wire. It can be determined by taking the total diameter of the conductive wire and the insulation together, and then subtracting the diameter of just the wire from the total diameter. For 40 gauge wire (AWG 40), which has a nominal diameter of 0.00314 inches, the insulation build typically ranges from 0.0002 to 0.0006 inches, where larger insulation builds are used to make the wire stronger or to offer more protection. By way of comparison, in accordance with the subject invention, the conductive wires  60  have an insulation thickness of about approximately 0.0015 inches, providing enhanced dielectric performance rated to 10 kV. 
     Referring back to  FIG. 3 , the electrode assembly  20  includes a plurality of longitudinally spaced apart proximal electrode rings  70  formed from a platinum iridium material and a plurality of smaller distal electrode rings  80 . These electrodes are adapted and configured for electrophysiological mapping, electrical cardioversion and/or pulsed ablation to facilitate the treatment of cardiac arrhythmia conditions. A respective conductive wire  60  is laser welded to an inner diameter of each electrode ring  70 ,  80 . An adhesive may be used additionally. Because these insulated conductive wires have such a substantial insulation build, there is no need to include a secondary covering or wrap over the wires, as is typical in prior art devices. 
     Referring now to  FIG. 6 , the handle assembly  12  includes a rotatable bi-directional steering mechanism  90  that is adapted and configured to deflect or otherwise steer the distal end portion of the tubular shaft  14  for improved intravascular placement. A pair of non-conductive steering cables  92   a  and  92   b  extend from the rotatable bi-directional steering mechanism  90  in the handle assembly  12  to the distal end portion of the shaft  14  to facilitate deflection of the distal end portion of the shaft by pulling in either direction. 
     Preferably, the non-conductive steering cables  92   a  and  92   b  are formed from Kevlar® thread, which is a heat resistant para-aramid synthetic fiber with molecular structure of many inter-chain bonds that provide strength. Because the steering cables  92   a  and  92   b  are formed from Kevlar thread, as opposed to a metal wire, there is no risk that they might puncture through the catheter wall if they break loose from their anchor points in the distal end portion of the shaft  14 . 
     The rotatable bi-directional steering mechanism  90  has a circular body  94  supported on a central pivot  95 , and the steering cables  92   a  and  92   b  are anchored to the circular body  94  on diametrically opposed bobbins  96   a  and  96   b  by respective set screws  98   a  and  98   b . The circular body  94  includes diametrically opposed steering flanges  95   a  and  95   b  for manually rotating the steering mechanism  90 . 
     While the subject disclosure has been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.