Low profile electrodes for an angioplasty shock wave catheter
Described herein are low-profile electrodes for use with an angioplasty shockwave catheter. A low-profile electrode assembly may have an inner electrode, an insulating layer disposed over the inner electrode such that an opening in the insulating layer is aligned with the inner electrode, and an outer electrode sheath disposed over the insulating layer such that an opening in the outer electrode sheath is coaxially aligned with the opening in the insulating layer. This layered configuration allows for the generation of shockwaves that propagate outward from the side of the catheter. In some variations, the electrode assembly has a second inner electrode, and the insulating layer and outer electrode may each have a second opening that are coaxially aligned with the second inner electrode. An angioplasty shockwave catheter may have a plurality of such low-profile electrode assemblies along its length to break up calcified plaques along a length of a vessel.
1. A method for cracking calcified lesions at a target region in a blood vessel of a patient comprising the steps of:
advancing a guide wire from an entry site on a patient to the target region of the vessel;
advancing a catheter over the guide wire, said catheter including an electrode assembly surrounded by a semi-rigid enclosure and wherein a first wire extends along the length of the catheter, said first wire being insulated and having a non-insulated portion defining a first inner electrode and wherein a second wire extends along a length of the catheter, said second wire being insulated and having a non-insulated portion defining a second inner electrode, said second inner electrode being located at a position circumferentially offset from the first inner electrode, said electrode assembly further including a conductive sheath having first and second apertures arcuate cut-outs formed therein, said conductive sheath being mounted on the catheter so that the first arcuate cut-out thereof is aligned with the first inner electrode and the second arcuate cut-out thereof is aligned with the second inner electrode;
filling the enclosure with a conductive fluid; and
supplying at least one high voltage pulse to the first and second wires so that shockwaves will be generated near both the first and second inner electrodes, with a series connection being defined as the current travels along a path extending from the first inner electrode to the conductive sheath and from the conductive sheath to the second inner electrode, with the shock waves cracking the calcified lesion.
2. A method as recited in claim 1 wherein after the one or more high voltage pulses are supplied to the first and second wires, the catheter is repositioned within the vessel and additional high voltage pulses are supplied to the first and second wires.
3. A method as recited in claim 1 wherein the first and second inner electrodes are further defined by an additional conductive element attached to each of the non-insulated portions of the first and second wires.
4. A method as recited in claim 3 wherein the additional conductive element is a hypotube crimped to each of the non-insulated portions of the first and second wires.
5. A method as recited in claim 1 wherein the first and second wires each include an insulated sheath.
6. A method as recited in claim 5 wherein the catheter includes elongated grooves formed along the outer surface thereof and wherein the first and second wires are carried in the grooves.
7. A method as recited in claim 1 wherein the second inner electrode is offset from the first inner electrode by 180 degrees.
8. A method as recited in claim 1 further including a second conductive sheath having first and second arcuate cut-outs therein and wherein the second inner electrode is connected to a third inner electrode, said third inner electrode being aligned with the first arcuate cut-out in the second conductive sheath and a fourth inner electrode is aligned with the second arcuate cut-out in the second conductive sheath.
9. A method as recited in claim 1 further including an insulating sheath mounted between the conductive sheath and the first and second inner electrodes, the insulating sheath including first and second arcuate cut-outs respectively aligned with the first and second arcuate cut-outs of the conductive sheath.
10. A method as recited in claim 1 wherein the enclosure is an inflatable balloon.
11. A method for cracking calcified lesions at a target region in a blood vessel of a patient comprising the steps of:
advancing a guide wire from an entry site on a patient to the target region of the vessel;
advancing a catheter over the guide wire, said catheter including an electrode assembly surrounded by a semi-rigid enclosure and wherein a first wire extends along the length of the catheter, said first wire being insulated and having a non-insulated portion defining a first inner electrode and wherein a second wire extends along a length of the catheter, said second wire being insulated and having a non-insulated portion defining a second inner electrode, said second inner electrode being located at a position circumferentially offset from the first inner electrode, said second wire having a second non-insulated portion defining a third inner electrode axially spaced from the first inner electrode along the length of the catheter, said electrode assembly further including a first conductive sheath having first and second arcuate cut-outs formed therein, said first conductive sheath being mounted on the catheter so that the first arcuate cut-out is aligned with the first inner electrode and the second arcuate cut-out thereof is aligned with the second inner electrode, a third wire extending along a length of the catheter, said wire being insulated and having a non-insulating portion defining a fourth inner electrode, said fourth inner electrode being located at a position circumferentially offset from the third inner electrode and substantially at the same axial location as the third inner electrode, said electrode assembly including a second conductive sheath having first and second arcuate cut-outs formed therein, said second conductive sheath being mounted on the catheter so that the first arcuate cut-out thereof is aligned with the third inner electrode and the second arcuate cut-out thereof is aligned with the fourth inner electrode;
filling the enclosure with a conductive fluid; and
supplying at least one high voltage pulse to the first and third wires so that shockwaves will be generated near each of the first, second, third and fourth inner electrodes, with a series connection being defined as the current travels along a path extending from the first inner electrode to the first conductive sheath and from the first conductive sheath to the second inner electrode and from the second inner electrode to the third inner electrode, and from the third inner electrode to the second conductive sheath and from the second conductive sheath to the fourth inner electrode with the shock waves cracking the calcified lesion.
12. A method as recited in claim 11 wherein after the one or more high voltage pulses are supplied to the first and third wires, the catheter is repositioned within the vessel and additional high voltage pulses are supplied to the first and third wires.
13. A method as recited in claim 11 wherein the first, second and third wires each include an insulated sheath.
14. A method as recited in claim 13 wherein the catheter includes elongated grooves formed along the outer surface thereof and wherein the first, second and third wires are carried in the grooves.
15. A method as recited in claim 11 wherein the second inner electrode is offset from the first inner electrode by 180 degrees and the fourth inner electrodes is offset form the third inner electrode by 180 degrees.
16. A method as recited in claim 11 further including a first insulating sheath mounted between the first conductive sheath and the first and second inner electrodes, the first insulating sheath including first and second arcuate cut-outs respectively aligned with the first and second arcuate cut-outs of the conductive sheath, said device further including a second insulating sheath mounted between the second conductive sheath and the third and fourth inner electrodes, the second insulating sheath including first and second arcuate cut-outs respectively aligned with the first and second arcuate cut-outs of the second conductive sheath.
17. A method as recited in claim 11 wherein the enclosure is an inflatable balloon.