Pediheart Podcast #392: Pulsed Field Ablation For Complex Congenital Heart Atrial Arrhythmia Management

This week's work is a brief one and is really a so-called research letter in which the team at Boston Children's Hospital reports on their initial experience using pulsed field ablation, or PFA, for the treatment of atrial arrhythmias in congenital heart patients.

For those not familiar with this energy source, PFA is a newer technique for cardiac ablation that uses short, high-voltage electrical pulses that are thought to selectively target heart tissue responsible for arrhythmia, while also sparing surrounding structures.

When compared to radiofrequency catheter ablation, the standard approach, which uses heat to destroy tissue, PFA is generally more precise, faster, and less likely to damage adjacent structures, such as the esophagus or the phrenic nerve.

PFA causes tissue injury by creating electrical fields that disrupt the cell membrane of the target tissue.

These pulses cause something called electroporation, which essentially forms tiny holes in the cell membrane.

And when those holes don't close, it leads to cell death.

Importantly, the voltage parameters that are used are chosen so that only the targeted cardiac cells are affected, potentially sparing most other tissues, which is why it's thought to be promising in regards to safety.

Thus, on the advantage side, PFA tends to have shorter procedure times, and it may be safer for patients who have different kinds of comorbidity.

However, PFA is still relatively new, and so long-term data on its efficacy and durability are still evolving, and this stands in contradistinction to radiofrequency ablation, where we have decades of data behind it making it a

well-validated and reliable method, though perhaps with more risk of collateral damage.

The work begins by reviewing how PFA has been used in the recent past, mostly for pulmonary vein isolation for the treatment of atrial fibrillation, using an over-the-wire catheter, and how the initial catheters are really quite large in the range of 13 French, making them particularly challenging to manipulate in complex anatomy where one might need to perforate a baffle or maybe even access the site via the liver.

Not having to use a gigantic sheath when going transhepatic could have a number of theoretical safety advantages.

According to the authors, the new so-called varipulse catheter has been released that has a variable loop circular catheter design that's 8.5 French, and it's bidirectional in regards to steering of the catheter.

And it's also integrated into the 3D electroanatomical mapping system, CARTO.

This catheter allows the operator to adjust the size of the loop of ablation, which may help it be more useful in different anatomies, rather than using a fixed circle of ablation that needs to be positioned to work for variable anatomies.

The authors explain that its safety and efficacy for adult PVI has been established, but that there's essentially no description of its use for complex and general heart disease, and that's the purpose of this work.

namely to review retrospectively the six patients in which the team used this catheter between April and October of 2025 for the treatment of atrial arrhythmias and complex congenital heart disease.

There were six male patients who had a mean age of 36 with a range of 21 to 58 years and all had complex drug-resistant atrial arrhythmias.

All six had an ablation with this variable loop catheter, with three having ablation for atrial fibrillation and three for atrial tachycardia and flutter.

The authors have a table with the patients on page 410, and we see that they all had important forms of congenital heart disease with two heterotaxy patients, one one-and-a-half ventricle pulmonary atresia intact ventricular septal patient, a patient with DTGA status post and atrial level switch, an Epstein's patient, and finally an LTGA VSD patient with mechanical valve following a double switch.

So these are obviously not typical or easy cases.

Three of the patients needed a transbathel puncture through prosthetic material, one from a transhepatic approach, and one had a transeptal through prosthetic material, and one a transeptal below a previously placed ASD device.

So I think it's clear that these were not run-of-the-mill simple ablations.

The authors describe using the variable loop catheter for PVI in five patients and for regional ablation of atypical atrial tachycardia or flutter in two.

And so what happened to these patients? Well, first, there was acute success in all six with one recurrence of atrial fibrillation after an extensive ablation on postoperative day two.