Guidewire apparatus and method for multiple parameter analysis of coronary stenosis

Abstract

A Percutaneous Coronary Intervention (PCI) guidewire and method of use includes at least two pairs of small surface area, closely spaced electrodes spaced axially along the length of the guidewire to allow one electrode pair to be positioned on each side of a coronary stenosis. The electrodes can sense electrical signals from the myocardium immediately adjacent to the electrodes, enabling the guidewire to record and analyze an Intra-Coronary Electrogram (ICEG) and heart pacing, and, therefore, facilitate more accurately diagnosis of an individual patient's stenosis and provide a more patient specific diagnosis of clinical need.

What is claimed is: 
     
         1 . An intravascular device:
 an elongate tubular body having a distal end region, and   a plurality of electrode pairs disposed on an exterior surface of the elongate tubular body proximate the distal end region and actually spaced thereapart   wherein the plurality of electrode pairs are electrically couplable to one of a signal source and measurement circuit.   
     
     
         2 . The intravascular device of  claim 1  wherein the plurality of electrode pairs comprises a proximal pair of closely spaced electrodes and a distal pair of closely spaced electrodes wherein the ratio of the interelectrode distance between the proximal pair of electrodes in the distal pair of electrodes to the intra-electrode distance between electrodes within a pair is in the range between 5:1 to 40:1. 
     
     
         3 . The intravascular device of  claim 1  wherein the plurality of electrode pairs comprises a proximal pair of closely spaced electrodes and a distal pair of closely spaced electrodes wherein the ratio of the interelectrode distance between the proximal pair of electrodes in the distal pair of electrodes to the intra-electrode distance between electrodes within a pair is in the range between 7:1 to 25:1. 
     
     
         4 . The intravascular device of  claim 1  wherein the plurality of electrode pairs comprises a proximal pair of closely spaced electrodes and a distal pair of closely spaced electrodes wherein the ratio of the interelectrode distance between the proximal pair of electrodes in the distal pair of electrodes to the intra-electrode distance between electrodes within a pair is in the range between 12:1 to 18:1. 
     
     
         5 . The intravascular device of  claim 1  in combination with a signal source and measurement circuit and capable of measuring impedance between the proximal pair of electrodes and the distal pair of electrodes. 
     
     
         6 . The intravascular device of  claim 1  wherein the interelectrode distance enables the proximal pair of electrodes and the distal pair of electrodes to be positioned on a different sides of a stenosis through which the guidewire is disposed within a vessel. 
     
     
         7 . The intravascular device of  claim 1  further comprising a third pair of closely spaced electrodes spaced axially along the elongate tubular body from the proximal pair of electrodes and the distal pair of electrodes 
     
     
         8 . The intravascular device of  claim 1  the electrodes of the proximal pair of electrodes and the distal pair of electrodes can sense electrical signals from living tissue adjacent to the electrodes. 
     
     
         9 . The intravascular device of  claim 1  wherein the closely spaced electrodes of one of the proximal pair of electrodes and the distal pair of electrodes are electrically coupled together. 
     
     
         10 . The intravascular device of  claim 1  wherein the intravascular device is a guidewire. 
     
     
         11 . The intravascular device of  claim 12  wherein the intravascular device is a catheter. 
     
     
         12 . The intravascular device of  claim 1  wherein the catheter is a guide catheter. 
     
     
         13 . A method for determining the necessity of performing a PCI or stenting procedure comprising:
 A) positioning a pair of electrodes within a vessel on both sides of a stenosis;   B) measuring with a measurement circuit electrically coupled to the electrodes the impedance within the vessel across the stenosis, and   C) comparing the measured impedance with one of a predetermined impedance value or a prior impedance measurement.   
     
     
         14 . The method of  claim 13  further comprising:
 D) presenting one of data indicating the size of a stenosis or a recommendation for performing a stenting procedure. 
 
     
     
         15 . The method of  claim 13  wherein the measured impedance comprises an average impedance value computed from multiple impedance values and wherein B) further comprises:
 B1) measuring with the electrodes the impedance within the vessel across the stenosis multiple times within a given time period. 
 
     
     
         16 . The method of  claim 15  wherein the vessel comprises a coronary artery and the given time period comprises at least one cardiac cycle. 
     
     
         17 . The method of  claim 13  further comprising:
 D) performing a Fast Fourier Transform analyses of signal data collected by measurement circuit while a pair of electrodes is positioned within a vessel on each sides of a stenosis