CARDIAC ABLATION

What is Atrial Fibrillation?

There are processes in the body that happen naturally every day and go unnoticed—such as the beating of the heart. But what happens when that process begins to fail? Although it may not seem like it, having an irregular heartbeat is a common condition, clinically known as arrhythmia. Currently, one of the most frequent arrhythmias is atrial fibrillation (AF), characterized by disorganized activation of the atria.

An irregular rhythm, like the one seen in AF, increases the likelihood of a blood clot forming, entering the bloodstream, and causing a stroke. In fact, between 15% and 20% of people who suffer a stroke have previously experienced irregular heartbeats.

How is Atrial Fibrillation Treated?

There are several treatment options for atrial fibrillation. However, one of the most commonly used is cardiac ablation, a brief and painless procedure that uses energy to destroy the area of tissue responsible for the arrhythmia, aiming to block its conductivity and restore a normal heart rhythm. Today, the most common methods are radiofrequency ablation (RFA) and pulsed field ablation (PFA).

Are There Risks in Cardiac Ablation?

While cardiac ablation is an effective option for treating atrial fibrillation, like any medical procedure, it carries risks. For example, one of the most serious adverse effects of RFA is atrioesophageal fistula (AEF)—a condition that is fatal in 50% of cases and occurs when the esophagus is thermally damaged during ablation.

But how does an AEF happen? RFA is a treatment that uses radio waves to generate alternating current. This current stimulates ionic vibration in the tissue, producing localized heating that leads to cell death. Because the esophagus is anatomically close to the heart, this heat often transfers to it, causing thermal injury that may progress and eventually result in an AEF.

How is PFA Different from RFA?

Unlike thermal ablation therapies like RFA, PFA delivers high-voltage, short electric pulses to the tissue, inducing pore formation in the cell membrane and cell death. In theory, this should eliminate the risk of thermal injury. However, it has been shown that under certain application conditions, this type of ablation can also cause a rise in tissue temperature.

How Can the Esophagus Be Protected from Thermal Effects?

Several strategies have been proposed to mitigate the thermal effects of ablation, such as reducing the applied power, monitoring luminal esophageal temperature, and mechanically displacing the esophagus. However, none of these strategies have proven to be entirely effective.

On the other hand, the ensoETM® system, a proactive cooling device approved by the FDA in September 2023, has demonstrated high efficacy in protecting the esophagus during ablation—achieving a 100% reduction in esophageal injuries.

Why Not Use PFA Exclusively, If Thermal Risk Seems Minimal?

Although PFA appears safer in terms of thermal damage, as previously mentioned, under certain conditions or with indiscriminate use, this therapy can still cause a temperature increase. Additionally, other side effects have been identified, such as red blood cell hemolysis, which can lead to kidney damage, and bubble formation, which may result in microembolisms.

What Are Hybrid Ablation Devices?

In recent years, several companies have developed hybrid devices capable of alternately applying both RFA and PFA, aiming to combine the advantages of each and reduce the risk of esophageal thermal damage. Generally, PFA is considered more suitable for the posterior wall of the heart, while RFA is preferred for thicker tissue areas. However, more studies are still needed to evaluate the safety of these new devices, as thermal effects may still persist.

How Can In Silico Trials Improve the Efficacy and Safety of Ablation Therapies?

Traditionally, clinical and in vivo studies have been conducted to evaluate the safety and effectiveness of a therapy or device. However, these studies present several challenges—from high costs and long timelines to ethical and legal dilemmas.

In this context, computational modeling offers an alternative, allowing the representation of real-world systems and phenomena in a virtual environment where an almost unlimited number of clinical contexts or scenarios can be simulated.

At IN SILICO STEM, we have developed cardiac ablation models using COMSOL Multiphysics®. With these models, we have predicted temperature distribution, lesion depth, and thermal injury progression for different technologies and protocols. This has enabled us to gain a deeper understanding of the interaction between tissues and applied energy, address clinically relevant questions, and generate scientific evidence that supports the development of safer treatments.