Elimination of Purkinje Fibers by Electroporation Reduces Ventricular Fibrillation Vulnerability

Abstract

BackgroundThe Purkinje network appears to play a pivotal role in the triggering as well as maintenance of ventricular fibrillation. Irreversible electroporation (IRE) using direct current has shown promise as a nonthermal ablation modality in the heart, but its ability to target and ablate the Purkinje tissue is undefined. Our aim was to investigate the potential for selective ablation of Purkinje/fascicular fibers using IRE.Methods and ResultsIn an ex vivo Langendorff model of canine heart (n=8), direct current was delivered in a unipolar manner at various dosages from 750 to 2500 V, in 10 pulses with a 90‐μs duration at a frequency of 1 Hz. The window of ventricular fibrillation vulnerability was assessed before and after delivery of electroporation energy using a shock on T‐wave method. IRE consistently eradicated all Purkinje potentials at voltages between 750 and 2500 V (minimum field strength of 250–833 V/cm). The ventricular electrogram amplitude was only minimally reduced by ablation: 0.6±2.3 mV (P=0.03). In 4 hearts after IRE delivery, ventricular fibrillation could not be reinduced. At baseline, the lower limit of vulnerability to ventricular fibrillation was 1.8±0.4 J, and the upper limit of vulnerability was 19.5±3.0 J. The window of vulnerability was 17.8±2.9 J. Delivery of electroporation energy significantly reduced the window of vulnerability to 5.7±2.9 J (P=0.0003), with a postablation lower limit of vulnerability=7.3±2.63 J, and the upper limit of vulnerability=18.8±5.2 J.ConclusionsOur study highlights that Purkinje tissue can be ablated with IRE without any evidence of underlying myocardial damage.

In vitro analysis of the origin and characteristics of gaseous microemboli during catheter electroporation ablation

“…Therefore, the in vitro results of this study cannot directly be translated to an in vivo situation. Furthermore, only one IRE waveform in combination with one catheter design was studied, while other groups use different pulse modalities and electrode geometry that may influence the amount and characteristics of the produced bubbles . Further research is needed to determine the differences between the different modalities.…”

Purkinje tissue modification and ventricular fibrillation

“…Early animal studies have shown promise of using pulsed electric fields as a means of electroporation to selectively modulate Purkinje signals and reduce vulnerability to VF . Cardiac electroporation holds major promise for the treatment of such a complex overlay of myocardium and conduction system tissue.…”

“…The ideal solution would be to selectively destroy the Purkinje tissue, while sparing the precious myocardium. Furthermore, leveraging selectivity for specific conduction tissue such as insulated versus noninsulated tissue, if possible, would offer an increase in both safety and efficacy …”

“…Early animal studies have shown promise of using pulsed electric fields as a means of electroporation to selectively modulate Purkinje signals and reduce vulnerability to VF. 9 Cardiac electroporation holds major promise for the treatment of such a complex overlay of myocardium and conduction system tissue. With the advantages of its selectivity, short duration, nonthermal nature, and the ability to modulate tissue reversibly as well as irreversibly, this energy modality may lend itself as ideal for selective and safe Purkinje tissue ablation.…”

Prevention of ventricular fibrillation through de‐networking of the Purkinje system

“…Recently, Livia et al published a study that targeted the PF in an experimental model of canine hearts with irreversible electroporation. Abolishing Purkinje signals was associated with a decreased window of vulnerability toward VF induction 35.…”