this invention , in one aspect , is a guidewire for intravascular measurement of at least four variables comprising : an elongate guidewire body having a distal segment and a proximal segment and having a diameter and defining a guidewire body surface and guidewire body bulk ; the guidewire body surface defining at least one helical groove extending along the length of the guidewire body between its distal segment and its proximal segment , the helical groove extending into the guidewire body bulk ; a sensor region on the distal segment of the guidewire body , the sensor region having at least four sensor elements ; at least four connectors on the proximal segment of the guidewire body ; at least four cables coupling the connectors to the sensor elements , the cables being located within the helical groove ( s ) defined by the guidewire body and not projecting outside the diameter of the guidewire body . in one aspect of the present guidewire there are between four and ten sensors and connectors coupled to each other with between four and 10 cables . in a further aspect of the present guidewire the guidewire body surface defines at least two helical grooves , the at least two helical grooves each having the cables disposed therein . in yet a further aspect , the present guidewire has a polymeric guidewire body . in yet a further aspect , the guidewire body of the present guidewire is a core wire , the core wire defining the at least one helical groove and the core wire diameter . in a preferred embodiment , this invention is a guidewire for intravascular measurement of at least four variables comprising or consisting essentially of : an elongate guidewire core wire , the core wire having a distal segment and a proximal segment , a diameter and defining a core wire surface and core wire bulk ; the core wire surface defining at least one helical groove extending along the length of the core wire between its distal segment and its proximal segment , the helical groove extending to the core wire bulk ; a sensor region on the distal segment of the core wire , the sensor region having at least four sensor elements ; at least four connectors located on the proximal segment of the core wire ; at least four cables coupling the connectors to the sensor elements , the cables being located within the helical groove and not projecting outside the diameter of the core wire . fig1 shows schematically an illustrative embodiment of the present invention . fig1 shows a guidewire body 10 , e . g ., a solid core wire segment 12 with a helical groove 14 ground into the guidewire body 10 . the helical groove 14 is ground to a depth dependent upon the number of insulated wires to be placed or wound therein substantially without increasing the core wire diameter or device profile . the core wire segment 12 shown in fig1 has an optional taper 16 leading to a second substantially constant diameter region 18 . groove 14 is cut into the surface 16 , 20 of core wire 12 and continues into the bulk or body 22 of core wire 12 . with this arrangement the very desirable guidewire handling characteristics of a guidewire ( of which the core wire 12 could be a structural component ) discussed above are retained . it should be noted that reference is made herein to “ distal ” and “ proximal ” segments or portions of a guidewire body such as a guidewire core wire . those references are made from the frame of reference of a medical professional using the guidewire . thus , in fig1 “ distal ” guidewire segment and structure tends toward the end of the device having designations and lead line numbers 12 , 16 and 18 . “ proximal ” guidewire segment and structure tends toward the portions of the core wire structure at 14 and 22 . this designation and frame of reference are as applicable to further guidewire structures , e . g ., coils , coatings , and particularly electrodes and connectors discussed below , deployed on or adjacent to the core wire distal or proximal segments . fig2 shows schematically a partial cross section of the invention shown in fig1 . taken along a line 2 - 2 in fig1 . in this embodiment , five insulated wires or cables 24 are deployed within groove 14 . as is shown in this embodiment , groove 14 is rectangular in section . other groove depths , and cross - sectional profile or section configuration are within the teaching of this invention . also as is shown in fig2 , by utilization of grooves 14 cut in the corewire body the vast bulk of the corewire remains intact , its outer diameter or profile being the same or substantilly the same as the corewire body before the conductive wires are placed therein . thus , the desired low profile and substantial maintainance of guidewire handling characteristics are provided by this invention . as is shown in fig1 and 2 the guidewire has a total of 5 insulated filars , cable or wires placed within the groove . this potentially provides 5 independent electrical pathways by means of the filars and a 6 th provided by the core wire itself . each and every insulated filar would have a sensing / stimulation electrode , pad or structure in its distal end and be coupled to a connecter ( usually male ) on its proximal end . the present invention contemplates the deployment of about 4 to as many as 10 or more conductive pathways ( i . e . wires or cables ) with essential maintenance of both core wire diameter and guidewire handling characteristics . one skilled in this art will appreciate that the core wire material and the conductive pathway material need not be and often would not be the same . in fact , advantageous characteristics could be imparted to the guidewire by intentionally selecting materials which provide a desired characteristic or characteristics . for example , nitinol wires could be used with a stainless steel core to provide additional resilience to the composite structure . one skilled in this art will also appreciate that the corewire material could be non - metallic , e . g ., a suitable polymer such as peek . were a non - metallic corewire material to be used , there would be a reduction ( by 1 ) of the number of conductive pathways available since , for example , a polymer core wire would not normally be sufficiently conductive ( without some additional modification , e . g ., doping ) to provide an electrically conductive pathway of a conductivity approaching that of common ferrous metals . one skilled in this art will also appreciate that the selection of insulative material to be coated onto the helically - deployed filars , wires , or cables is of critical importance . for example , u . s . pat . no . 7 , 627 , 382 to minar et al ., the teaching of which is incorporated by reference herein , is exemplary of both chemistry and method usable herein . numerous other chemistries will occur to one skilled in this art . fig3 shows in longitudinal section an embodiment of the invention with 4 conductive wires 50 , 52 , 54 , 56 deployed in a helical groove 58 having a depth corresponding approximately to the diameter of the wire providing the possibility of 5 separate pathways ( presuming a conductive core wire is used ) from the distal and to the proximal end of the guidewire structure . fig4 , 5 , and 6 show in perspective an embodiment of this invention illustrated in fig1 and 2 above with increasing amplification . the terms “ sensor ” and “ sensor elements ” are used in the attached claims and in this disclosure . that term is intended to mean , essentially any structure intended to monitor or treat electrical phenomena within the body from outside of the body . as such “ sensing ” as used here is not limited to monitoring electro - physical activity , e . g ., that of sensing coronary pulses and other parameters relating to e . g ., rate - responsive pacing , but includes delivering pacing or defibrillation pulses . the present invention permits the electrical coupling of a plurality connectors such as male connectors located on the proximal segment of a guidewire to electrodes / sensors / conductive pads located on the distal segment of the guidewire . those structures are conventional and are discussed in patent application publication us 2010 / 00228112 to malmborg at paragraphs [ 0024 ] through [ 0030 ] including fig1 - 6 , that disclosure and figs being incorporated by reference herein . the present invention , in contrast with the malmborg reference in the previous paragraph , employs at least four and as many as 4 to 10 or more electrically conductive pathways helically running the length of guidewire body . the large number of conductive pathways permits the simultaneous monitoring and / or therapeutic adjustment of ( e . g ., by stimulation ) of a comparable number of endovascular physiologic parameters . for example , blood temperature , flow rate , muscle activity , ph , oxygen saturation , and numerous other parameters such as those used in rate - responsive pacing can be monitored . in a further advantage of the large number of conductive pathways provided by this invention , differentials between sensing pads or electrodes on the guidewire body can be determined . electrical conductivity , fluid temperature , flow rate , ph and other physiologic parameters may be measured as between two or more sensor structures strategically placed on the guidewire body distal segment to diagnose / treat endovascular medical conditions exemplified by vessel blockage , temperature drop , pressure , flow rate , oxygen saturation . one skilled in this art will appreciate the many potential applications for this versatile guidewire structure in the measurement , diagnosis and treatment of endovascular medical issues .
this invention relates to medical guidewire having multiple electrically conductive pathways extending from substantially their distal ends to substantially their proximal ends .