System and apparatus comprising a multisensor guidewire for use in interventional cardiology

Abstract

A system and apparatus comprising a multisensor guidewire for use in interventional cardiology, e.g. for Transcatheter Valve Therapies (TVT), comprises a plurality of optical sensors for direct measurement of cardiovascular parameters, e.g. transvalvular blood pressure gradients and flow. A conventional outer coil contains a shaped core wire having a cross-section defining helical grooves extending along its length, which accommodate optical fibers and optical sensors within a diameter D core of the core wire. Advantageously, the diameter and material of the core wire provides the guidewire with sufficient stiffness for use as a support guidewire for valve replacement, e.g. Transcatheter Aortic Valve Implantation (TAVI), while accommodating multiple sensors and optical fibers within a guidewire of outside diameter ≦0.89 mm. An optical connector couples the guidewire to a control system. Optionally, the guidewire includes a contact force sensor; a pre-formed tip; and/or a separable micro-connector for proximal mounting of over-the-guidewire components.

1 . A multisensor guidewire for measuring blood pressure concurrently at multiple locations during a minimally invasive intravascular or cardiac intervention, comprising:
 a tubular covering layer comprising a flexible coil (coil), the coil having a length extending between a proximal end and a distal end, an outside diameter of ≦1 mm, a core wire extending within the coil from the proximal end to the distal end, and the distal end comprising a flexible distal tip;   a plurality of optical sensors and a plurality of optical fibers; a sensor end of each optical fiber being attached and optically coupled to an individual one of the plurality of optical sensors;   the core wire having an external surface with a cross-sectional profile defining a plurality of grooves extending along a length of the core wire, each groove accommodating an individual optical fiber and a respective optical sensor within a diameter D core  of the core wire and providing a sensor arrangement with said plurality of optical sensors positioned at respective sensor locations within a distal end portion of the guidewire;   a proximal end of each of the plurality of optical fibers being coupled to an optical input/output connector at the proximal end of the guidewire for connection to an optical control system; and   the plurality of optical sensors of the sensor arrangement including at least two optical pressure sensors at respective sensor locations spaced apart lengthwise along a length of said distal end portion.   
     
     
         2 . The multisensor guidewire of  claim 1 , wherein the plurality of grooves are symmetrically spaced around the core wire. 
     
     
         3 . The multisensor guidewire of  claim 2 , wherein the grooves are helical grooves. 
     
     
         4 . The multisensor guidewire of  claim 3 , wherein the helical grooves have a pitch of at least 25 mm (1 inch). 
     
     
         5 . The multisensor guidewire  claim 1 , wherein the grooves have a depth that accommodates each optical fiber and optical sensor within a respective groove of the core wire without protruding beyond the diameter D core  of the core wire. 
     
     
         6 . The multisensor guidewire of  claim 5 , wherein, at sensor positions in the distal end portion, the grooves are enlarged to accommodate optical sensors having an external diameter greater than that of the optical fibers. 
     
     
         7 . The multisensor guidewire of  claim 1 , wherein surfaces of the core wire defining the grooves are radiused to no less than a minimum radius R min  for formation of the grooves by a wire-drawing process. 
     
     
         8 . The multisensor guidewire of  claim 1 , wherein each optical fiber is adhesively bonded to the core wire within its respective groove at a point adjacent the sensor location. 
     
     
         9 . The multisensor guidewire of  claim 1 , wherein the coil has an outside diameter of ≦0.89 mm (≦0.035 inch). 
     
     
         10 . The multisensor guidewire of  claim 1 , for use as a support guidewire for transcatheter valve replacement, wherein the core wire comprises a medical grade stainless steel alloy and the diameter D core  of the core wire provides the guidewire with predetermined stiffness characteristics defined by a standard guidewire descriptor, said guidewire descriptor being one of stiff, super-stiff and ultra-stiff. 
     
     
         11 . The multisensor guidewire of  claim 1 , for use as a support guidewire for transcatheter valve replacement, wherein the core wire comprises a medical grade stainless steel alloy and the diameter D core  of the core wire in at least the distal end portion provides a flexural modulus of 60 GPa or more. 
     
     
         12 . The multisensor guidewire of  claim 1 , configured for measuring a transvalvular blood pressure gradient within the heart during a minimally invasive cardiac intervention, wherein said plurality of optical sensors comprise Fabry-Pérot MOMS pressure sensors and said sensor locations are spaced apart lengthwise along said length of the distal end portion to provide for one or more of:
 a) placement of at least one pressure sensor in the aorta downstream of the aortic valve and placement of at least one pressure sensor in the left ventricle, upstream of the aortic valve for measurement of a transvalvular blood pressure gradient for the aortic valve; 
 b) placement of at least one pressure sensor in the left atrium upstream of the mitral valve and placement of at least one pressure sensor in the left ventricle, downstream of the mitral valve for measurement of a transvalvular blood pressure gradient for the mitral valve; 
 c) placement of at least one pressure sensor in the right atrium upstream of the tricuspid valve and placement of at least one pressure sensor in the right ventricle, downstream of the tricuspid valve, for measurement of a transvalvular blood pressure gradient for the tricuspid valve; and 
 d) placement of at least one pressure sensor in the right ventricle upstream of the pulmonary valve and placement of at least one pressure sensor in the pulmonary artery, downstream of the pulmonary valve for measurement of a transvalvular blood pressure gradient for the pulmonary valve. 
 
     
     
         13 . The multisensor guidewire  claim 1 , wherein the plurality of optical sensors further comprises an optical flow sensor. 
     
     
         14 . The multisensor guidewire of  claim 1 , for use as a support guidewire for transcatheter valve replacement, comprising at least three optical sensors and respective optical fibers, wherein the distal end portion of the coil has an external diameter ≦0.89 mm (≦0.035 inch), and the core wire provides a guidewire having a flexural modulus of 60 GPa or more. 
     
     
         15 . The multisensor guidewire of  claim 1 , wherein apertures are provided in the coil adjacent each optical pressure sensor for fluid contact therewith, and optionally, radiopaque markers are provided adjacent each optical pressure sensor. 
     
     
         16 . The multisensor guidewire of  claim 1 , wherein the guidewire comprises separable distal and proximal parts, and further comprising a separable micro-optical coupler comprising a female connector and a male connector coupling the proximal and distal parts, the distal part carrying the male connector, and the male connector having a diameter no greater than the outside diameter of the coil, to enable proximal mounting of components on/over-the-guidewire. 
     
     
         17 . The multisensor guidewire of  claim 1 , wherein the plurality of optical sensors further comprises an optical contact force sensor adjacent to, or within, the distal tip, the optical contact force sensor being configured for sensing a force applied by the distal end portion of the guidewire to surrounding tissue. 
     
     
         18 . The multisensor guidewire of  claim 1 , wherein the flexible distal tip comprises a pre-formed atraumatic tip comprising one of:
 a straight soft tip;   a pre-formed J-tip,   a pre-formed spiral tip or other two dimensionally curved tip;   a pre-formed tip having a three dimensional curved form;   a pre-formed tip having a helical structure; and   a pre-formed tip having a tapered helical structure, resembling the form of a snail shell.   
     
     
         19 . A core wire for a multisensor guidewire as defined in  claim 1 , wherein the multisensor guidewire has a flexible coil having an external diameter of ≦1 mm and comprises a plurality of optical sensors and a corresponding plurality of optical fibers,
 the core wire being formed from a medical grade metal alloy, having a diameter D core  and an external surface defining a plurality of grooves extending along the length of the guidewire, each groove having a depth that can accommodate an individual one of said plurality of optical fibers within the diameter D core  of the core wire, and wherein D core  is sized to fit slideably with the flexible coil of a guidewire. 
 
     
     
         20 . The core wire of  claim 19 , wherein the plurality of grooves extend helically along the length of the core wire. 
     
     
         21 . The core wire of  claim 19 , wherein the plurality of grooves are spaced symmetrically around the core wire. 
     
     
         22 . The core wire of  claim 19 , wherein surfaces of the grooves have at least a minimum radius for formation of the grooves by wire-drawing. 
     
     
         23 . The core wire of  claim 19 , fabricated from a stainless steel alloy. 
     
     
         24 . A method of assembly of a multisensor guidewire as defined in  claim 1 , the method comprising:
 providing a core wire having an external surface and cross-sectional profile defining a plurality of grooves defined along its length;   providing a plurality of optical fibers, each optical fiber having at its distal end an optical sensor;   attaching the optical fibers and their respective optical sensors and the core wire to form a sub-assembly with optical sensors spaced apart lengthwise along a distal end portion of the core wire, and with each optical fiber and its respective sensor sitting within a respective groove of the core wire; and   inserting the sub-assembly into the coil of the guidewire.