Introduction
Atrial fibrillation (AF), also known as AFib, is a type of cardiac arrhythmia (irregular heartbeat) that occurs when the upper chambers of the heart (atria) beat either very fast, slow, or irregularly. It can happen for short episodes or maybe a permanent condition. This results in impaired blood movement from the atria to the ventricles (lower chambers). Sometimes, the blood can get pooled in an area and lead to clot formation. AF can be symptomatic in some people, while others do not experience any symptoms. Irregular heartbeats, extreme fatigue, chest pain, shortness of breath, lightheadedness, and palpitations characterize AFib.
Obesity, advancing age, smoking, alcohol consumption, and conditions such as hypertension, diabetes, ischemic heart disease, hyperthyroidism, etc, are some of the risk factors for atrial fibrillation. Atrial fibrillation can be managed by medications, and certain procedures such as cardiac ablation, cardioversion (quick, low energy is used to restore normal cardiac rhythm), Maze procedure (a technique which creates scar tissue by application of cold energy), insertion of a pacemaker, or other surgeries).
What Is Pulsed Field Ablation?
Cardiac ablation is a procedure in which cold or heat energy is used to create small scars in the tissues which is responsible for abnormal rhythm. It is performed using wires called electrodes that stimulate the heart and locate the area causing abnormal rhythm. Pulsed-field ablation (PFA) is a nonthermal tissue ablation technique that uses high-amplitude pulsed electrical fields to generate irreversible electroporation (an increase in cell membrane permeability) in tissues. This method also avoids damage to adjacent structures and is a better alternative to traditional ablation techniques.
The PulseSelect PFA system was approved by the United States Food and Drug Administration (FDA) on December 13, 2023, as the first PFA method for treating patients with atrial fibrillation. It also treats solid tumors near the major nerves or blood vessels. Pulsed-field ablation has been investigated since 2011 for generating myocardial lesions. Studies have shown that this technique can create deep lesions in the myocardium (cardiac muscles) without causing clinically significant damage to the extracardiac tissues. It has been reported as safe and effective for patients with atrial fibrillation since 2018.
What Is the Mechanism of Pulsed Field Ablation?
The pulsed-field ablation technique creates nanopores (tiny holes) in the cell membranes because transient and high-voltage exposure disrupts the cell wall integrity, thus leading to cell death. Ultra-rapid electric fields are used to create nanoscale pores that destabilize the tissues, resulting in transmural lesions (scars) in the target tissues (atrial muscles). PFA is particularly well suited for cardiac ablation techniques as the cardiac cells have lower threshold values than other tissues. This system includes a PFA catheter, a custom generator, and a 13-F steerable sheath. The custom generator delivers a high-voltage pulsed field through multiple channels. The PFA catheter with gold electrodes can map the cardiac anatomy and electrical activity and deliver pulsed-field ablation energy for the cardiac tissues to treat atrial fibrillation. It uses contact-sensing in the respective electrodes in contact with the heart tissues to deliver the treatment effectively. Recent research illustrates that magnetic resonance imaging (MRI) and computed tomography (CT) guided ablation techniques also successfully treat AFib.
What Are the Challenges of Pulsed Field Ablation?
For decades, thermal energy was accepted as the standard therapy for catheter ablation in atrial fibrillation in cardiac electrophysiology. Pulsed-field ablation is a promising technique for treating arrhythmias, but it involves several challenges that must be addressed before it is adopted into clinical practice. These include:
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One of the important limitations is the lack of standard protocols for PFA, as the determination of energy delivery parameters can vary depending on the target tissues and the patient’s condition. It is also needed to avoid dose-dependent complications.
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As PFA is a relatively new technique, it is difficult to compare the results of various studies of traditional techniques.
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The cost of the technique, equipment, and the need for specialized training can be difficult to adopt in all healthcare facilities, thus limiting accessibility to some patients.
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Improving the target tissues of interest can be challenging or difficult as the structures are hard to access and have complex anatomy. Improved imaging techniques and guidance systems can aid in overcoming these aspects.
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Pulsed-field ablation can be associated with complications like pulmonary artery hemorrhage and coronary artery spasms. Hence, further research is required to prevent these conditions.
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Some studies have shown that PFA also causes collateral damage to the surrounding structures.
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The cellular mechanisms involved in pulsed-field ablation are yet to be completely understood; hence, further research is required to optimize these parameters.
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Large-scale studies and long-term data to establish the safety and efficacy of PFA need to be more comprehensive to determine its role in clinical practice.
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Randomized clinical trials have not been performed to compare the clinical outcomes of PFA with conventional ablation methods such as cryoablation and radiofrequency ablation.
What Are the Advancements in Pulsed Field Ablation?
Pulsed-field ablation is an advanced technology for treating different medical conditions, including arrhythmias and cancer. It is a faster, safer, and more effective cardiac ablation technique compared to traditional thermal modes that risk damage to the surrounding tissues and also require lengthy treatment duration. PFA can also be effective in posterior wall isolation for deeper lesions and ventricular tachycardia ablation for targeting the tissues in ventricular walls. Miniaturization of PFA catheters has been developed to improve its use in smaller and more complex structures and perform the ablation more precisely and efficiently. Energy delivery parameters are also being optimized and investigated to reduce the need for multiple ablation methods and tissue damage. Machine learning algorithms and artificial intelligence (AI) can also improve the effectiveness and accuracy of the PFA procedures.
Conclusion
Pulsed-field ablation is an emerging treatment method for the management of atrial fibrillation. It involves the generation of rapid and high-voltage pulsed electrical fields to create permeability in the cell membrane. Compared to traditional ablation methods, it is not based on heating to damage or destroy the target tissues. Studies have shown that this non-thermal technique possesses good durability and is faster than other conventional ablation methods, along with reduced risk to adjacent structures. Healthcare specialists expect PFA to be widespread and commercially available so that many patients can benefit from this new technology.
