Systems, devices, and methods for focal ablation
Systems, devices, and methods for electroporation ablation therapy are disclosed. An apparatus may include a linear shaft including a distal portion positionable near a tissue wall. The linear shaft can be configured to deflect to position the distal portion near the tissue wall. The apparatus can include a plurality of electrodes disposed on the distal portion of the linear shaft, where the plurality of electrodes are configured to generate a pulsed electric field that produces an ablation zone in the tissue wall having a depth that is independent of an orientation of the distal portion relative to the tissue wall.
1 . A system, comprising:
an electroporation ablation device including:
a single linear shaft including a linear distal portion positionable near a tissue wall, the linear shaft configured to be deflectable along one or more portions proximal to the linear distal portion to position the linear distal portion near the tissue wall, the linear shaft comprising a flexible shaft portion;
a plurality of collinear electrodes disposed on the linear distal portion, the plurality of electrodes including:
a distal-most set of distal electrodes including a distal tip electrode disposed at a tip of the linear shaft and having a tip electrode length and an adjacent distal electrode having a first length and separated from the distal tip electrode by a distal spacing, wherein the tip electrode length is different from the first length; and
a proximal-most set of proximal electrodes disposed proximal to the distal-most set, the proximal-most set of proximal electrodes including a first spacing separating an adjacent pair of proximal electrodes, the first spacing being substantially equal to the distal spacing;
the flexible shaft portion having a portion length of a second spacing separating the most distal proximal electrode of the proximal-most set of proximal electrodes from the most proximal distal electrode of the distal-most set of distal electrodes, at least one of the proximal electrodes from the adjacent pair having a second length, the first length being less than the second length, and the second spacing being greater than the first spacing and greater than the distal spacing;
an electromagnetic sensor disposed along the portion length of the flexible shaft portion, such that the electromagnetic sensor is positioned between the set of distal electrodes and the set of proximal electrodes; and
a plurality of leads coupled to the plurality of electrodes, each lead having insulation configured to withstand a potential difference of at least about 700 V without dielectric breakdown; and
a signal generator operatively coupled to the electroporation ablation device and configured to activate the distal electrodes with a first polarity and the proximal electrodes with a second polarity opposite the first polarity as an anode-cathode pair such that the plurality of electrodes generates a pulsed electric field that is capable of producing an ablation zone via irreversible electroporation in the tissue wall having a depth that is independent of an orientation of the linear distal portion relative to the tissue wall.
2 . The system of claim 1 , wherein the set of proximal electrodes are jointly wired using a first lead from the plurality of leads, and the set of distal electrodes is independently wired using a second lead from the plurality of leads.
3 . The system of claim 1 , wherein the ablation device further includes a pull wire configured to be actuated to deflect the linear shaft, the pull wire coupled to a location along the distal portion of the linear shaft.
4 . The system of claim 1 , wherein each of the first spacing and the second spacing is about 0.5 mm to about 12 mm.
5 . The system of claim 4 , wherein the ratio of the second spacing to the first spacing is between about 1 and about 20.
6 . The system of claim 1 , further comprising:
a tracking device configured to track a location of the distal portion of the linear shaft during positioning, the tracking device including a field generator configured to generate at least one of electric fields or magnetic fields,
wherein the electromagnetic sensor is configured to receive a set of signals in response to the generated fields for determining the location of the distal portion of the linear shaft.
7 . The system of claim 1 , wherein the first length of the adjacent distal electrode is between about 1 mm and about 8 mm, and the second length of the at least one proximal electrode is between about 1 mm and about 6 mm.
8 . The system of claim 1 , wherein the set of proximal electrodes further includes a proximal electrode having a third length different from the second length.
9 . The system of claim 1 , wherein the signal generator is configured to activate the set of distal electrodes and the set of proximal electrodes to generate the pulsed electric field having a shape that is wider near the distal tip electrode than near the set of proximal electrodes.
10 . An apparatus, comprising:
a single linear shaft including a linear distal portion positionable near a tissue wall, the linear shaft configured to be deflectable along one or more portions proximal to the linear distal portion to position the linear distal portion near the tissue wall, the linear shaft comprising a flexible shaft portion;
a plurality of electrodes disposed on the linear distal portion, the plurality of electrodes configured to generate a pulsed electric field with the plurality of electrodes being capable of producing an ablation zone in the tissue wall having a depth that is independent of an orientation of the linear distal portion relative to the tissue wall, the plurality of electrodes including:
a distal-most set of distal electrodes including a distal tip electrode, having a tip electrode length, disposed at a tip of the linear shaft and an adjacent distal electrode having a distal electrode length different from the tip electrode length and separated from the distal tip electrode by a distal spacing; and
a proximal-most set of proximal electrodes disposed proximal to the distal-most set of distal electrodes, the proximal-most set of proximal electrodes including a proximal spacing separating an adjacent pair of proximal electrodes, the proximal spacing being greater than the distal spacing;
the flexible shaft portion having a portion length defining an electrode set spacing separating the most distal proximal electrode from the adjacent distal electrode, the most distal proximal electrode of the proximal-most set of proximal electrodes adjacent to the most proximal distal electrode of the distal-most set of distal electrodes,
wherein the distal spacing and the proximal spacing are less than the electrode set spacing;
an electromagnetic sensor disposed along the portion length of the flexible shaft portion, such that the electromagnetic sensor is positioned between the set of distal electrodes and the set of proximal electrodes; and
a plurality of leads coupled to the plurality of electrodes, each lead from the plurality of leads configured to deliver a voltage output having an amplitude of at least 700V to the plurality of electrodes (1) without dielectric breakdown of its corresponding insulation and (2) such that the set of distal electrodes are activated with a first polarity and the set of proximal electrodes are activated with a second polarity opposite the first polarity as an anode-cathode pair to collectively generate the pulsed electric field.
11 . The apparatus of claim 10 , wherein the set of proximal electrodes are jointly wired using a first lead from the plurality of leads, and the distal tip electrode and the adjacent distal electrode are jointly wired using a second lead from the plurality of leads.
12 . The apparatus of claim 10 , wherein the two proximal electrodes are jointly wired using a first lead from the plurality of leads, the distal tip electrode is independently wired using a second lead from the plurality of leads, and one or more distal electrodes disposed proximal to the distal tip electrode are independently or jointly wired using one or more third leads from the plurality of leads.
13 . The apparatus of claim 10 , wherein the linear shaft has a diameter of between about 1 mm and about 5 mm.
14 . The apparatus of claim 10 , wherein:
each proximal electrode from the set of proximal electrodes has a length of about 1 mm to about 6 mm, and
each distal electrode from the set of distal electrodes has a length of about 1 mm to about 8 mm.
15 . The apparatus of claim 10 , wherein the ratio of the electrode set spacing to the proximal spacing is between about 1 and about 20.
16 . The apparatus of claim 10 , further comprising a pull wire including proximal and distal ends,
the distal end of the pull wire coupled to the linear shaft at a location distal to the set of proximal electrodes and near the distal end of a portion of the linear shaft separating the most distal proximal electrode of the set of proximal electrodes from the most proximal distal electrode of the set of distal electrodes,
the proximal end of the pull wire coupled to an actuation mechanism,
the pull wire configured to be actuated via the actuation mechanism to deflect the linear shaft such that the portion of the linear shaft deflects with the deflection of the linear shaft.
17 . The apparatus of claim 10 , further comprising a pull wire including proximal and distal ends,
the distal end of the pull wire coupled to the distal portion of the linear shaft,
the proximal end of the pull wire coupled to an actuation mechanism,
the pull wire configured to be actuated via the actuation mechanism so as to deflect the linear shaft.
18 . The apparatus of claim 10 ,
wherein the electromagnetic sensor, in response to at least one of electric fields or magnetic fields being generated by a field generator associated with a tracking device, is configured to receive a set of signals for determining a location of the distal portion.
19 . The apparatus of claim 18 , wherein a subset of the set of distal electrodes is configured to measure electrocardiogram (ECG) data.
20 . The apparatus of claim 10 , wherein each of the proximal, electrode set, and distal spacings are between about 0.5 mm and about 12 mm.
21 . The apparatus of claim 10 , wherein the proximal spacing is greater than the distal spacing.
22 . A method, comprising:
positioning an ablation device including a single linear shaft in a cardiac chamber of a heart of a subject such that a linear distal portion of the linear shaft is near a first portion of a tissue wall with the linear shaft set at a first orientation to the first portion of the tissue wall, the linear shaft comprising a flexible shaft portion, the ablation device including a plurality of electrodes disposed on the linear distal portion and an electromagnetic sensor disposed at the flexible shaft portion, the plurality of electrodes including a distal-most set of distal electrodes, including a distal tip electrode having a distal tip length and an adjacent distal electrode having a distal electrode length different from the distal tip electrode length, and a proximal-most set of proximal electrodes, at least one adjacent pair of proximal electrodes of the set of proximal electrodes separated by a first spacing, the most distal proximal electrode of the set of proximal electrodes and the most proximal distal electrode of the set of distal electrodes separated by the flexible shaft portion having a portion length of a second spacing greater than the first spacing and devoid of electrodes of the plurality of electrodes, the most distal proximal electrode of the proximal-most set of proximal electrodes adjacent to the most proximal distal electrode of the distal-most set of distal electrodes, and the set of distal electrodes separated from each other by a distal spacing, the distal spacing less than each of the first spacing and the second spacing; and
generating, using a signal generator, a first pulse waveform having a voltage amplitude of at least about 700 V;
delivering, while the linear distal portion is set at the first orientation, the first pulse waveform to the plurality of electrodes such that the set of distal electrodes are activated with a first polarity and the set of proximal electrodes are activated with a second polarity opposite the first polarity to collectively generate a pulsed electric field that produces an ablation zone in the first portion of the tissue wall;
positioning the ablation device in the cardiac chamber such that the linear distal portion is near a second portion of the tissue wall with the linear shaft set at a second orientation different from the first orientation;
generating, using the signal generator, a second pulse waveform having a voltage amplitude of at least about 700 V; and
delivering, while the linear distal portion is set at the second orientation, the second pulse waveform to the plurality of electrodes such that the set of distal electrodes are activated with the first polarity and the set of proximal electrodes are activated with the second polarity as an anode-cathode pair to collectively generate a pulsed electric field that produces an ablation zone via irreversible electroporation in the second portion of the tissue wall having a depth that is approximately equal to a depth of the ablation zone produced in the first portion of the tissue wall.
23 . The method of claim 22 , wherein the cardiac chamber is an endocardial space of an atrium.
24 . The method of claim 22 , wherein each electrode from the plurality of electrodes has an insulated lead associated therewith, each insulated lead configured withstand a potential difference of at least about 700 V without dielectric breakdown of its corresponding insulation.
25 . The method of claim 22 , wherein the positioning of the linear shaft includes actuating a pull wire coupled to the distal portion to deflect the distal portion to steer the ablation device.
26 . The method of claim 22 , further comprising:
generating, using a field generator associated with a tracking device, at least one of electric fields or magnetic fields;
receiving, from a subset of the set of distal electrodes, a set of signals in response to the generated fields;
determining, based on the set of signals, a location of the distal portion of the linear shaft, the positioning of the linear shaft being guided by the location.
27 . The method of claim 22 , wherein each of the first, second, and distal spacings are between about 0.5 mm and about 12 mm.
28 . The method of claim 22 , wherein the ratio of the second spacing to the first spacing is between about 1 and about 20.
29 . The method of claim 22 , wherein:
each proximal electrode from the set of proximal electrodes has a length of about 1 mm to about 6 mm, and
each distal electrode from the set of distal electrodes has a length of about 1 mm to about 8 mm.
30 . The method of claim 22 , wherein the linear shaft set at the first orientation is approximately normal to the first portion of the tissue wall, and the linear shaft set at the second orientation is obliquely opposed to the tissue wall.