Systems, apparatuses and methods for delivery of ablative energy to tissue
A system includes a pulse waveform generator and an ablation device coupled to the pulse waveform generator. The ablation device includes at least one electrode configured for ablation pulse delivery to tissue during use. The pulse waveform generator is configured to deliver voltage pulses to the ablation device in the form of a pulsed waveform. A first level of a hierarchy of the pulsed waveform includes a first set of pulses, each pulse having a pulse time duration, with a first time interval separating successive pulses. A second level of the hierarchy of the pulsed waveform includes a plurality of first sets of pulses as a second set of pulses, a second time interval separating successive first sets of pulses, the second time interval being at least three times the duration of the first time interval.
1. A method, comprising:
generating a pulsed waveform, the pulsed waveform including:
(a) a first level of a hierarchy of the pulsed waveform that includes a first set of pulses, each pulse of the first set of pulses having a pulse time duration and being a rectangular pulse, a first time delay separating successive pulses of the first set of pulses;
(b) a second level of the hierarchy of the pulsed waveform that includes a plurality of first sets of pulses as a second set of pulses, a second time delay separating successive first sets of pulses, the second time delay being at least three times the duration of the first time delay; and
(c) a third level of the hierarchy of the pulsed waveform includes a plurality of second sets of pulses as a third set of pulses, a third time delay separating successive second sets of pulses, the third time delay being at least thirty times the duration of the second level time delay; and
delivering the pulsed waveform to an ablation device.
2. The method of claim 1 , wherein each pulse of the first set of pulses is a monophasic pulse with a voltage amplitude of at least 500 Volts, the pulse time duration of each monophasic pulse being in the range from about 1 microsecond to about 300 microseconds.
3. The method of claim 1 , wherein each second set of pulses includes at least 2 first sets of pulses and less than 40 first sets of pulses.
4. The method of claim 1 , wherein each third set of pulses includes at least 2 second sets of pulses and less than 30 second sets of pulses.
5. The method of claim 1 , wherein each pulse of the first set of pulses is a biphasic pulse with a voltage amplitude of at least 500 Volts, the pulse time duration of each biphasic pulse being in the range from about 0.5 nanosecond to about 20 microseconds.
6. The method of claim 1 , wherein the second time delay is at least ten times the pulse time duration of each pulse of the first set of pulses.
7. The method of claim 1 , wherein the ablation device includes an ablation catheter configured for epicardial placement.
8. The method of claim 1 , wherein the ablation device includes an ablation catheter configured for endocardial placement.
9. The method of claim 1 , wherein the ablation device includes at least four electrodes.
10. The method of claim 1 , wherein each pulse of the first set of pulses is a biphasic pulse, the first set of pulses having a frequency from about 100 kHz to about 300 kHz.
11. The method of claim 1 , wherein the first time delay is greater than the pulse time duration of each pulse of the first set of pulses.
12. The method of claim 1 , wherein the first level of the hierarchy of the pulsed waveform includes the first set of pulses implemented as a set of biphasic pulses with successive biphasic pulses separated by the first time delay, the first time delay being greater than the pulse time duration of each biphasic pulse of the set of biphasic pulses.
13. A method, comprising:
generating one or more pulsed waveforms, each pulsed waveform including:
(a) a first level of a hierarchy of the pulsed waveform that includes a first set of pulses, each pulse of the first set of pulses having a pulse time duration and being a rectangular pulse, a first time delay separating successive pulses of the first set of pulses;
(b) a second level of the hierarchy of the pulsed waveform that includes a plurality of first sets of pulses as a second set of pulses, a second time delay separating successive first sets of pulses, the second time delay being at least three times the duration of the first time delay; and
(c) a third level of the hierarchy of the pulsed waveform includes a plurality of second sets of pulses as a third sets of pulses, a third time delay separating successive second sets of pulses, the third time interval being at least thirty times the duration of the second level time delay; and
generating a set of pacing signals with a cardiac stimulator;
delivering, in synchrony with the set of pacing signals, the one or more pulsed waveforms to an ablation device such that each of the one or more pulsed waveforms is delivered during a refractory period following a pacing signal of the set of pacing signals.
14. The method of claim 13 , wherein each pulse of the first set of pulses is a monophasic pulse with a voltage amplitude of at least 500 Volts, the pulse time duration of each monophasic pulse being in the range from about 1 microsecond to about 300 microseconds.
15. The method of claim 13 , wherein each second set of pulses includes at least 2 first sets of pulses and less than 40 first sets of pulses.
16. The method of claim 13 , wherein each third set of pulses includes at least 2 second sets of pulses and less than 30 second sets of pulses.
17. The method of claim 13 , wherein each pulse of the first set of pulses is a biphasic pulse with a voltage amplitude of at least 500 Volts, the pulse time duration of each biphasic pulse being in the range from about 0.5 nanosecond to about 20 microseconds.
18. The method of claim 13 , wherein the second time delay is at least ten times the pulse time duration of each pulse of the first set of pulses.
19. The method of claim 13 , wherein the ablation device includes an ablation catheter configured for epicardial placement.
20. The method of claim 13 , wherein the ablation device includes an ablation catheter configured for endocardial placement.
21. The method of claim 13 , wherein the ablation device includes at least four electrodes.
22. The method of claim 13 , wherein each of the one or more pulsed waveforms is spaced from a pacing signal of the set of pacing signals by a time offset, the time offset being smaller than about 25 milliseconds.
23. The method of claim 13 , wherein the third time delay corresponds to a pacing period associated with the set of pacing signals.
24. The method of claim 13 , wherein each pulse of the first set of pulses is a biphasic pulse, the first set of pulses having a frequency from about 100 kHz to about 300 kHz.
25. The method of claim 13 , wherein the first time delay is greater than the pulse time duration of each pulse of the first set of pulses.
26. The method of claim 13 , wherein the first level of the hierarchy of each of the one or more pulsed waveforms includes the first set of pulses implemented as a set of biphasic pulses with successive biphasic pulses separated by the first time delay, the first time delay being greater than the pulse time duration of each biphasic pulse of the set of biphasic pulses.
27. The method of claim 13 , wherein:
the set of pacing signals include atrial pacing signals and ventricular pacing signals, each atrial pacing signal associated with an atrial refractory period and each ventricular pacing signal associated with a ventricular refractory period; and
each of the one or more pulse waveforms being delivered during an overlapping time window of the atrial refractory period and the ventricular refractory period.