Methods of recognizing and eliminating arcs and arc induced plasma during energy delivery in tissue
Methods and systems for monitoring and modifying pulsed field ablation (PFA) energy delivery to prevent patient safety risks and/or delivery device failure. In particular, some embodiments provide methods and systems for detecting and preventing arcs and arc-induced plasma, and their causal events, during delivery of pulsed field ablation energy, as well as methods and systems for identifying conditions leading to potential delivery device failure and correcting charge imbalance or asymmetry.
1. A method of modifying pulsed field ablation (PFA) energy delivery, the method comprising:
delivering a PFA pulse from a PFA generator;
determining, with an amplitude detector, a 10% amplitude and a 90% amplitude of a final amplitude of the PFA pulse in the time domain;
measuring, with a counter circuit, a rise time and a fall time of the PFA pulse based on the 10% amplitude and the 90% amplitude of the final amplitude;
calculating a voltage of at least one oscillatory pole in the PFA pulse based at least in part on the rise time and the fall time; and
modifying a pulse width of the PFA pulse and at least one of the rise time and the fall time to reduce the voltage of the at least one oscillatory pole in the PFA pulse, wherein modifying the pulse width and at least one of the rise time and the fall time includes
generating, with the counter circuit and the amplitude detector, a correction signal based on the rise time and the fall time, and
applying the correction signal to the PFA generator.
2. The method of claim 1 , wherein the PFA generator further includes processing circuitry having an H bridge circuit.
3. The method of claim 2 , wherein modifying the at least one of the rise time and the fall time includes applying the correction signal to adjust an input resistance in the H bridge circuit.
4. The method of claim 1 , wherein modifying at least one of the rise time and the fall time includes reducing the time in which the PFA pulse reaches 90% of a final amplitude of the PFA pulse when gradients between energy delivery electrodes are 1 KV/cm or more.
5. The method of claim 1 , wherein the at least one of the rise time and the fall time is modified to a time between 0.3 μs and 0.5 μs.
6. The method of claim 1 , further comprising:
measuring a pulse width of the PFA pulse;
calculating a voltage of an oscillatory pole in the PFA pulse based at least in part on the pulse width; and
modifying the pulse width to reduce the voltage of the at least one oscillatory pole in the PFA pulse.
7. The method of claim 1 , further comprising:
ceasing delivery of the PFA pulse from the PFA generator when the calculated voltage of the oscillatory pole is greater than a threshold voltage.
8. A method of modifying pulsed field ablation (PFA) energy delivery, the method comprising:
delivering at least one biphasic PFA pulse from a PFA generator, each of the at least one biphasic PFA pulse including a biphasic pair having a positive phase and a negative phase;
determining, with an amplitude detector, a 10% amplitude and a 90% amplitude of a final amplitude of the PFA pulse in the time domain;
measuring, with a counter circuit, a rise time and a fall time of the PFA pulse based on the 10% amplitude and the 90% amplitude of the final amplitude;
calculating a value of an integral of a current over the biphasic pair;
calculating a voltage of at least one oscillatory pole in the PFA pulse based at least in part on the rise time and the fall time; and
modifying a pulse width of the PFA pulse and at least one of the rise time and the fall time to reduce the voltage of the at least one oscillatory pole in the PFA pulse, wherein modifying the pulse width and at least one of the rise time and the fall time includes
generating, with the counter circuit and the amplitude detector, a correction signal based on the rise time and the fall time, and
applying the correction signal to the PFA generator.
9. The method of claim 8 , further comprising:
measuring a pulse width of the PFA pulse; and
modifying the pulse width of the biphasic PFA pulse when the integral of the current has a non-zero value.
10. The method of claim 9 , further comprising delivering a runt pulse in the biphasic PFA pulse and modifying the pulse width of the biphasic PFA pulse when the integral of the current has a non-zero value.
11. The method of claim 10 , wherein the runt pulse has an amplitude that is less than an amplitude of the positive phase of the biphasic pair.
12. The method of claim 10 , wherein the runt pulse has an amplitude that is less than an amplitude of the negative phase of the biphasic pair.
13. The method of claim 10 , wherein the runt pulse is delivered after the negative phase of the biphasic pair.
14. The method of claim 1 , wherein modifying at least one of the rise time and the fall time includes applying a spectral mask to a delivered waveform to ensure that the timing of the waveform and amplitude characteristics fit a prescribed dosing prescription of the waveform, wherein the mask includes an upper boundary, a lower boundary, and a compliance region between the upper boundary and the lower boundary.