Treatment of ischaemia

The apparatus of any preceding claim, wherein the catheter comprises an external distal centring arrangement that is extensible from at least two opposed sides of the catheter in radially-outward directions.

The apparatus of any preceding claim, wherein the catheter comprises an external steering arrangement that is extensible from the catheter in at least one radially-outward direction to deflect a distal end of the catheter and the element laterally from a longitudinal axis.

The apparatus of any preceding claim, wherein the catheter contains inner and outer bundles of filaments, the filaments of one bundle being twisted about a longitudinal axis of the catheter relative to the filaments of the other bundle and the bundles being co-operable to apply torsional forces to a wall of the catheter in response to a distal end portion of the catheter being compressed.

The apparatus of any preceding claim, wherein the catheter contains at least one radially self-expanding support that is deployable from the catheter around the element and that, when deployed, has a longitudinally-tapering shape.

The apparatus of any preceding claim, wherein a distal end portion of the catheter is tapered distally.

The apparatus of any preceding claim, wherein a proximal end of the catheter is coupled to the transducer to receive ultrasonic energy from the transducer.

The apparatus of any preceding claim, wherein the catheter comprises a longitudinal slit extending along at least a majority of the length of the catheter, the slit communicating with a lumen of the catheter for accommodating the element.

The apparatus of any preceding claim, wherein the catheter defines at least two parallel lumens, a first of those lumens being for housing the element.

The apparatus of any preceding claim, wherein the second lumen has a distal opening whose periphery is inclined at an acute angle to a longitudinal axis of the catheter.

The apparatus of any preceding claim, wherein the catheter comprises a damping element that is movable radially inwardly from a wall of the catheter into contact with the activated element.

The apparatus of any preceding claim, wherein the catheter and the element comprise detent formations that are co-operable by relative longitudinal movement to provide feedback on relative longitudinal positions of the catheter and the element.

A method of crossing through an obstruction in a blood vessel, the method comprising activating a distal tip section of the wire with ultrasonic energy, causing the distal tip 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.

A method of crossing through an obstruction in a blood vessel, the method comprising exciting a distal tip section of an elongate endovascular element such as a wire by conveying ultrasonic energy from a wider proximal section of the element to the distal tip section along a distally-tapering intermediate section of the element, said excitation generating lateral sub-harmonic vibrations in the distal tip section in addition to longitudinal vibrations driven by longitudinal resonances in the element.

A method of handling an elongate endovascular element, such as a wire, for crossing through an obstruction in a blood vessel of a patient, the method comprising:

• advancing an activation unit distally toward the patient's body, the activation unit being coupled to the element to activate the element ultrasonically;
• and
• by virtue of a tube that extends distally from the activation unit and surrounds a portion of the element, limiting distal advance of the activation unit toward the body to keep that portion of the element outside the body.

A method of handling an elongate endovascular element, such as a wire, for crossing through an obstruction in a blood vessel of a patient, the method comprising:

• supporting a portion of the element outside the patient's body within a tube extending distally from an activation unit that is coupled to the element to activate the element ultrasonically;
• and
• pressing part of the tube in a radially-inward direction into contact with the element.

A method of handling an elongate endovascular element, such as a wire, for crossing through an obstruction in a blood vessel of a patient, the method comprising:

• supporting a portion of the element outside the patient's body within a tube extending distally from an activation unit that is coupled to the element to activate the element ultrasonically;
• and
• varying the length of the tube by applying longitudinal force to a telescopic, concertina or braid structure of the tube.

A method of crossing through an obstruction in a blood vessel, the method comprising exciting a distal tip section of an elongate endovascular element such as a wire by conveying ultrasonic energy along the wire, wherein the element is supported in a surrounding first lumen of a catheter and fluid is driven from a second lumen of the catheter into the first lumen around the element.

A method of crossing through an obstruction in a blood vessel, the method comprising exciting a distal tip section of an elongate endovascular element such as a wire by conveying ultrasonic energy along the wire, wherein the element is supported in a surrounding first lumen of a catheter and fluid is driven along a second lumen of the catheter to aspirate debris removed from the obstruction by said excitation of the distal tip section of the element.