Pulsed Field Ablation for Ventricular Arrhythmias: Early Evidence

Catheter ablation has become a cornerstone in the management of ventricular tachycardia and other ventricular rhythm disturbances, particularly in patients with structural heart disease. Conventional energy sources, including radiofrequency and cryothermal energy, carry inherent risks when targeting myocardium near coronary vessels, the phrenic nerve, or other vulnerable structures. Pulsed field ablation has emerged as a nonthermal alternative that uses high-voltage, microsecond electrical pulses to induce irreversible electroporation, producing durable myocardial lesions without relying on resistive tissue temperatures.

While pulsed field technology has matured rapidly for atrial fibrillation, its application in the ventricles remains in an earlier phase of investigation. Preclinical work in porcine and ovine models has established proof of concept, and recent case series from international centres have begun to translate those findings into humans. Ventricular myocardium is thicker, more vascular, and more heterogeneous than atrial tissue, raising questions about whether pulsed field energy can consistently create transmural lesions in scarred or hypertrophied ventricles without collateral injury to the conduction tissue.

Australian electrophysiologists have followed this space with interest, given the country's active clinical trial environment and its strong preclinical research community in Melbourne, Sydney, and Brisbane. Researchers at the Baker Heart and Diabetes Institute in Melbourne and the Victor Chang Cardiac Research Institute in Sydney have contributed to the broader mechanistic literature, while hospitals such as Royal Melbourne, Westmead, and The Prince Charles Hospital in Brisbane are positioned to be early adopters once Therapeutic Goods Administration approval pathways are clear. Preclinical pulsed field ablation research for ventricular arrhythmias has gained momentum globally, with major findings appearing in the Journal of Arrhythmia and related journals.

This review synthesises the current preclinical and early human data on pulsed field ablation in ventricular arrhythmias, with attention to lesion formation, safety considerations, and implications for Australian practice. The article examines the biophysics of irreversible electroporation, the relevance of pulsed electric fields for ventricular myocardium, what animal models have taught us about lesion durability and collateral effects, and what the initial human experience has revealed about efficacy and procedural safety. Where local context applies, Australian centres and regulatory frameworks are highlighted.

Mechanism of irreversible electroporation in the ventricles

Irreversible electroporation is a nonthermal process in which microsecond-to-millisecond bursts of high-voltage direct current destabilise the lipid bilayer of cardiac myocytes, forming permanent nanoscale pores that lead to cell death. Unlike thermal ablation, pulsed field energy is not dependent on resistive heating, so lesion depth scales with electric field intensity rather than thermal conductivity. In atrial tissue this mechanism produces sharply demarcated lesions with relative sparing of surrounding connective tissue, and ventricular applications aim to exploit similar characteristics, especially when ablating near the coronary arteries, the phrenic nerve, or the conduction system.

Electric field thresholds determine efficacy, and these thresholds vary between tissues. Myocardium has a relatively low threshold for electroporation compared with vascular endothelium and nerve tissue, which is the basis for the selectivity argument that has driven much of the enthusiasm around this technology. In porcine ventricular studies, pulsed field application at field strengths of around 1000 V per centimetre consistently produces contiguous lesions on voltage mapping, while sparing adjacent coronary arterial smooth muscle on histopathology. This contrasts with radiofrequency ablation, in which resistive temperatures can produce risk of coronary spasm or stenosis.

Ventricular myocardium presents different challenges than atrial tissue. The thicker wall and variable fibrosis mean that uniform field distribution is harder to achieve, and the presence of epicardial fat, intramyocardial scar from prior infarction, or lipomatous metaplasia can shield tissue from the field. Operators have explored both bipolar and monopolar configurations, and recent catheter platforms incorporate larger electrodes or lattice-tip configurations to homogenise exposure across the ventricular wall. Researchers at Australian centres such as the University of Sydney and Monash University have published on the biophysics of field distribution in anisotropic myocardium, building on the foundational work in atrial tissue.

Preclinical lesion characteristics in animal models

Preclinical studies have used both healthy swine and infarcted or hypertrophied ovine models to characterise pulsed field lesions in the ventricles. Healthy swine ventricles have generally shown durable, homogeneous ablation zones when irrigated catheters are used, with clear borders on histology and minimal inflammatory response at one week. Voltage mapping and cardiac magnetic resonance have demonstrated that pulsed field lesions in normal myocardium are usually noncontiguous on electroanatomic mapping, suggesting that lesion formation follows the field wavefront rather than tissue perfusion.

Chronic studies in infarcted models have raised some concerns. When pulsed field energy is delivered into dense scar, lesion formation can be incomplete because the field is shunted through low-impedance channels, and re-entrant circuits may persist. Conversely, in border zones where myocytes intermix with fibrosis, the field appears to create more complete lesions than radiofrequency, likely because electroporation does not require conductive heating to reach temperature thresholds in poorly perfused tissue. Ovine studies at preclinical research centres in Melbourne have shown that border-zone dense lesions can be created with pulsed field energy in clinically relevant scar settings, supporting the translational potential of the technique.

Coronary artery safety has been a major focus. Several preclinical studies, including work referenced in hoe werkt een multiplier and other recent reviews, have shown that pulsed field energy spares the arterial media and elastica, with preserved endothelial integrity even when the vessel is within the ablation zone. Phrenic nerve studies in canine and porcine models have likewise demonstrated preserved nerve function after pulsed field application, even when the nerve is adjacent to the ablation site. Esophageal injury, a major concern in atrial pulsed field ablation, has not been a focus in ventricular work because most ventricular ablation does not approach the oesophagus, although ablation in the posterior septum or coronary sinus can place the oesophagus at risk.

Tissue selectivity and procedural safety

Despite the favourable preclinical safety profile, several concerns deserve attention when applying pulsed field technology to ventricular arrhythmias. Muscle contractions during energy delivery are more pronounced in the ventricles than in the atria, because higher currents are typically required to achieve transmural lesions. This has led to a stronger reliance on deep sedation or general anaesthesia during ventricular pulsed field ablation, with some operators using neuromuscular blockade to limit patient movement.

Skeletal muscle recruitment can elevate serum biomarkers of muscle injury, including creatine kinase, often to levels much higher than seen with thermal ablation. Whether this translates into clinically meaningful myocardial injury remains uncertain, but cardiac troponin elevations follow a similar pattern to thermal ablation. Operators must also be aware of potential interactions with implantable devices; pacemakers and defibrillators can be affected by the high-voltage pulses, and most protocols recommend switching devices to a backup mode and interrogating them after the case. The Therapeutic Goods Administration has been responsive to safety communications for ventricular pulsed field platforms, and Australian operators have contributed to international registries tracking these events.

Ventricular arrhythmia induction during pulsed field delivery is a recognised phenomenon in preclinical models, and a small number of cases of induced ventricular arrhythmia during delivery have been reported. Strategies to mitigate this risk include synchronising pulses to the absolute refractory period and using lower-frequency pulse trains. Catheter design also matters, and contemporary platforms incorporate biphasic waveforms and shorter pulse durations that reduce muscle capture and arrhythmia induction. For a deeper dive into pulmonary vein isolation safety thresholds using high-power short-duration ablation, see pulmonary vein isolation safety thresholds.

Early human experience and procedural outcomes

The early human experience with pulsed field ablation for ventricular arrhythmias consists of case reports, small case series, and registry analyses. Pioneering work in Europe and North America has demonstrated feasibility of pulsed field ablation in atrial fibrillation, and ventricular applications have followed. Single-centre series from Heidelberg, Hamburg, and Bordeaux have reported successful ablation of idiopathic outflow tract ventricular tachycardia and selected scar-mediated ventricular tachycardia cases, with acute procedural success rates comparable to thermal ablation.

Procedural times have generally been shorter with pulsed field ablation than with thermal ablation, in part because of the rapid lesion formation and reduced reliance on waiting periods for temperature-related monitoring. However, ventricular cases often involve mapping with high-density catheters, which adds time. Fluoroscopy times vary across studies, and most series report low complication rates with no reports of atrio-oesophageal fistula, a feared complication of thermal ablation in atrial fibrillation that is less relevant for ventricular work.

Long-term follow-up data remain limited. Most published series have follow-up of less than 12 months, and recurrence rates are difficult to compare across studies because of heterogeneous patient populations, mapping techniques, and endpoints. Australian operators have begun to participate in international collaborations to capture more systematic data, and national cardiac procedure registries have begun to track outcomes in selected Australian sites.

Implications for clinical practice in Australia

Translating pulsed field ablation for ventricular arrhythmias into Australian practice will depend on several factors. Therapeutic Goods Administration approval of ventricular pulsed field ablation catheters has lagged behind atrial approval, and clinicians will need to work within approved indications. The Australian healthcare system, with its mix of public and private provision, will also shape access; pulsed field ablation systems are capital-intensive, and many public hospitals will require health technology assessments before adoption.

Training pathways are another consideration. Pulsed field ablation is technically distinct from thermal ablation, and proctoring is recommended by supervising interventional cardiologists with experience in ventricular ablation. The Cardiac Society of Australia and New Zealand has begun to issue position statements on pulsed field ablation for atrial fibrillation, and a parallel document for ventricular applications is anticipated. Industry-supported training programs in Sydney, Melbourne, and Brisbane are providing hands-on experience with phantom models and ex vivo tissue.

Research priorities for Australian centres include local registry participation, prospective comparative studies against standard-of-care thermal ablation, and translational studies of lesion durability in vivo. The Baker Heart and Diabetes Institute, the Victor Chang Cardiac Research Institute, and the University of Adelaide have expressed interest in preclinical pulsed field ablation research, and there is scope for Australian contributions to the international mechanistic literature. Researchers can also engage with the editorial team at the journal to discuss submission of preclinical data or case reports.

Pulsed field ablation represents an important technological evolution in catheter ablation for ventricular arrhythmias. The preclinical evidence is encouraging, particularly with respect to tissue selectivity and the sparing of coronary arteries and nerves, and early human data support procedural feasibility. Durable lesion duration and outcomes in lower-risk scar settings remain incompletely defined, and further research is needed. Australian centres are well placed to contribute to this evidence base through preclinical research, clinical trials, and registry participation. Clinicians interested in submitting original research, case reports, or reviews on this topic are invited to contact the editorial team for manuscript guidelines and submission instructions.