Pulsed-field ablation (PFA) has dominated the medical device news in recent years, yet it is only one modality among many in the world of ablation therapies, and while groundbreaking, it is limited to a few diseases. It’s time to broaden the conversation and highlight the myriad innovations in ablation technology transforming medical practice.
What Is Ablation?
Ablation refers to the selective destruction of tissue to treat a disease or disorder. Common applications include killing tumors, correcting heart arrhythmias, and deadening pain from over-active sensory nerves. Other applications include conditions spanning from literally head-to-toe on the human body and include everything from the most cutting-edge life-saving treatments (brain surgery) to the most superficial (killing sweat glands to reduce underarm perspiration).
Ablation is a cornerstone of minimally invasive medicine, offering targeted tissue destruction with precision unattainable by traditional surgical methods. Ablation technologies encompass a wide variety of modalities, including:
Extreme cold (cryoablation).
Heat (microwave and radiofrequency ablation).
Mechanical forces (focused ultrasound).
Electric fields (electroporation and PFA).
What all these modalities have in common is that they require interdisciplinary expertise spanning device engineering, tissue biology, and computational modeling to ensure they are safe, effective, and market ready.
Mechanisms of Action
Cryoablation is the simplest ablation modality, using extreme cold to induce frostbite in a controlled manner. This process kills cells by freezing their intracellular fluid, leading to ice crystal formation and cell rupture. While commonly used for superficial applications, advancements in needle and catheter design have enabled deep-tissue treatments, such as for prostate or liver tumors.
Despite its effectiveness, cryoablation has limitations. The process can be unwieldy, and controlling the spread of freezing can be challenging, making it less precise than some other ablation modalities.
Microwave and radiofrequency (RF) ablation both rely on heat to destroy tissue, but their mechanisms differ:
Microwave ablation excites water molecules in tissue, generating heat through molecular vibrations (similar to a microwave oven heating food).
RF ablation conducts electrical current through tissue, producing heat via resistance.
Each technique has distinct strengths and applications as shown in Table 1. The choice between these technologies depends on the target tissue and clinical requirements. For example, RF ablation excels in smaller, electrically conductive tissues, while microwave ablation is preferred for larger, less conductive structures such as the lung (see Figure 1).
Ultrasound ablation uses high-intensity sound waves, and again, has a different mechanism of action depending on the specific implementation.
Thermal ultrasound devices generate sound waves with enough intensity that they produce significant heating when absorbed by tissue; this has applications in catheter-based intraluminal therapies and directional needle-based ablation therapies.
Cavitational ultrasound devices use high-frequency sound waves to induce cavitation (a mechanical shearing of tissue), which produces tiny, localized bubbles that disrupt tissue at the cellular level. Particularly exciting about this approach is the ability to generate ultrasound waves outside of the body then focus them at a target deep within the body — to say this therapy is minimally invasive is insufficient; this approach is completely noninvasive.
Electric field ablation encompasses PFA and irreversible electroporation (IRE), which use high-intensity electric fields to open pores in the walls of cells (and/ or their nuclei), causing a loss of cellular homeostasis and eventual cell death (see Figure 2). Key benefits of this approach include:
Tissue selectivity: Different types of tissues are dramatically more (or less) susceptible to electroporation. In cardiac electrophysiology, this allows electric fields to ablate errant conduction pathways in myocardial tissue without damaging sensitive nearby nerves or muscles.
Nonthermal mechanism: Electroporation uses essentially the same type of thin needles and catheters that physicians are familiar with using in RF ablation yet ablates tissue in a non-thermal manner. This apoptotic mechanism of cellular death (versus the necrotic mechanism of thermal ablation) minimizes inflammation, resulting in faster healing and less pain.
Predictability: Thermal ablation therapies are less predictable and controllable in tissues with different heat capacities, different thermal conductivities, or heat sink effects (such as blood flow) present. Preprocedure planning and prediction of thermal ablation therapies is difficult, as the heat transfer equations and computational models are complex. Electric field ablation, however, is unaffected by any of these confounders, and the equations and models are simple, allowing meaningful and reliable preplanning of treatments, improving efficacy and outcomes.
Emerging Innovations in Ablation
Two major themes are emerging in ablation innovation today: 1) even less-invasive procedures, and 2) even more selective and effective approaches.
Less-invasive Procedures. Across all medical disciplines, there is a push toward less-invasive techniques, and ablation therapies are no exception. Innovations focus on enhancing existing technologies to reduce patient recovery time and improve outcomes. Examples include:
Intraluminal ablation catheters: These catheters circulate coolant to protect surrounding tissues while creating precise, uniquely shaped ablation zones.
Expandable RF needles: By mechanically expanding around the target tissue, these instruments shorten procedure times and improve durability of the therapy.
Integrated sensors: Advanced sensor systems can identify target tissues, assess therapy success in real-time, and reduce the risk of complications.
Enhanced Selectivity and Efficacy. While many ablation techniques rely on basic mechanisms like heating or freezing, new advancements aim to improve tissue selectivity, efficacy, and controllability. Notable examples include:
Expanding PFA applications: Beyond its established use in cardiac therapies, PFA is being adapted for non-cardiac applications. Researchers are exploring tissue-specific electric susceptibilities to develop treatments with reduced collateral damage and fewer side effects.
Steerable probes: These allow clinicians to precisely direct energy to diseased tissues while avoiding healthy structures. Additionally, their ability to adjust in real-time eliminates the need for repositioning electrodes during procedures (see Figure 3).
Challenges and Opportunities
Despite their transformative potential, ablation technologies face several challenges:
Thermal modalities require complex modeling to predict heat transfer accurately, especially in tissues with varying thermal properties or blood flow.
Cryoablation’s limitations in controllability can restrict its use for certain applications.
Electric field ablation, while highly promising, is still in the early stages of clinical adoption for noncardiac uses.
Opportunities lie in addressing these challenges through interdisciplinary innovation. Combining modalities, such as pairing thermal ablation with sensors for real-time feedback, could significantly enhance outcomes. Similarly, advancements in computational modeling and AI-driven planning systems promise to improve precision and predictability across all modalities.
Future Directions and Conclusions
Ablation therapies have become indispensable in modern medicine, and their influence will only grow as innovation drives less-invasive, more-effective solutions. The next wave of advancements is likely to emerge from the convergence of technologies, leveraging engineering, biology, and clinical insights to overcome current limitations. Those innovators with multi-disciplinary technology breadth, the ability to work with users to understand their needs and pains, and the ability to straddle the biological, electrical, and mechanical domains, will be the leaders in the ablation technologies of the future.
This article was written by Dan Friedrichs, PhD. He leads development engineering efforts at Minnetronix Medical, St. Paul, MN. For more information, visit here .
