Treatment of ischaemia

Abstract

An endovascular apparatus for crossing through an obstruction in a blood vessel comprises an elongate endovascular element such as a wire. The element has a proximal section, a distal tip section of smaller diameter than the proximal section; and a distally-tapering intermediate section extending between the proximal and distal tip sections . The apparatus comprises an ultrasonic transducer, mechanically coupled to the proximal section of the element for ultrasonically activating the element, hence exciting the distal tip section to facilitate crossing through the obstruction. A catheter surrounds the element, leaving at least part of the distal tip section of the element protruding distally beyond a distal end of the catheter.

1 - 52 . (canceled) 
     
     
         53 . A method of crossing through an obstruction in a blood vessel, the method comprising activating a distal section of a wire with ultrasonic energy, causing the distal section to move in a primary longitudinal mode with distal and proximal oscillation, and also in a radial direction with a lateral mode and secondary modes of differential harmonics. 
     
     
         54 . The method of  claim 53 , wherein the distal section undergoes orbital movement about a central longitudinal axis to excavate a tunnel in the obstruction that is wider than the distal section. 
     
     
         55 . The method of  claim 54 , comprising advancing the distal section of the element distally through the obstruction to create an aperture, inducing said orbital movement in the distal section on a distal side of the obstruction, and moving the orbitally-moving distal section proximally through the obstruction to widen the aperture. 
     
     
         56 . The method of  claim 53 , wherein the distal section undergoes multi-harmonic movement to excavate a tunnel in the obstruction that is wider than the distal section. 
     
     
         57 . The method of  claim 56 , comprising advancing the distal section of the element distally through the obstruction to create an aperture, inducing the multi-harmonic movement in the distal section on a distal side of the obstruction, and moving the multi-harmonically moving distal section proximally through the obstruction to widen the aperture. 
     
     
         58 . The method of  claim 53 , further comprising supporting the element in a catheter that surrounds the element, leaving at least part of the distal section protruding distally beyond a distal end of the catheter. 
     
     
         59 . The method of  claim 58 , comprising effecting relative longitudinal movement between the element and the catheter. 
     
     
         60 . The method of  claim 58 , comprising moving the catheter longitudinally to induce orbital and/or multi-harmonic movement in the distal section on a proximal side of the obstruction, and moving the orbitally and/or multi-harmonically-moving distal section distally through the obstruction to create or to widen an aperture through the obstruction. 
     
     
         61 . The method of  claim 58 , comprising adjusting a diameter of a lumen of the catheter to vary radial clearance between the catheter and the element. 
     
     
         62 . The method of  claim 58 , comprising steering the catheter within the vessel to deflect a distal end of the catheter and the element laterally from a longitudinal axis by applying radially-outward steering force from the catheter in at least one direction. 
     
     
         63 . The method of  claim 58 , further comprising conveying vibrations distally along the catheter from a proximal end of the catheter. 
     
     
         64 . A method of crossing through an obstruction in a blood vessel, the method comprising exciting a distal section of an endovascular element such as a wire by conveying ultrasonic energy from a wider proximal section of the element to the distal section along a distally-tapering intermediate section of the element, said excitation generating and/or amplifying lateral sub-harmonic vibrations in the distal section in addition to longitudinal vibrations driven by longitudinal resonances in the element. 
     
     
         65 . The method of  claim 64 , comprising amplifying the vibrations in the distal section by conveying the ultrasonic energy along the distally-tapering intermediate section. 
     
     
         66 . The method of  claim 64 , wherein the distal section undergoes orbital movement about a central longitudinal axis to excavate a tunnel in the obstruction that is wider than the distal section. 
     
     
         67 . The method of  claim 66 , comprising advancing the distal section of the element distally through the obstruction to create an aperture, inducing said orbital movement in the distal section on a distal side of the obstruction, and moving the orbitally-moving distal section proximally through the obstruction to widen the aperture. 
     
     
         68 . The method of  claim 64 , wherein the distal section undergoes multi-harmonic movement to excavate a tunnel in the obstruction that is wider than the distal section. 
     
     
         69 . The method of  claim 68 , comprising advancing the distal section of the element distally through the obstruction to create an aperture, inducing said multi-harmonic movement in the distal section on a distal side of the obstruction, and moving the multi-harmonically moving distal section proximally through the obstruction to widen the aperture. 
     
     
         70 . The method of  claim 64 , further comprising supporting the element in a catheter that surrounds the element, leaving at least part of the distal section protruding distally beyond a distal end of the catheter. 
     
     
         71 . The method of  claim 70 , comprising effecting relative longitudinal movement between the element and the catheter. 
     
     
         72 . The method of  claim 70 , comprising moving the catheter longitudinally to induce orbital and/or multi-harmonic movement in the distal section on a proximal side of the obstruction, and moving the orbitally- or multi-harmonically-moving distal section distally through the obstruction to create or to widen an aperture through the obstruction. 
     
     
         73 . The method of  claim 70 , comprising adjusting the diameter of a lumen of the catheter to vary radial clearance between the catheter and the element. 
     
     
         74 . The method of  claim 70 , comprising steering the catheter within the vessel to deflect a distal end of the catheter and the element laterally from a longitudinal axis by applying radially-outward steering force from the catheter in at least one direction. 
     
     
         75 . The method of  claim 70 , further comprising conveying vibrations distally along the catheter from a proximal end of the catheter. 
     
     
         76 . The method of  claim 64 , comprising subsequently delivering one or more therapeutic devices along the element to treat the blood vessel.