Applications of electrical energy in medicine: RF ablation, pulsed field ablation and electroporation

Learn about new and promising applications of energy-based medical systems and the challenges of their development.

Daniel Friedrichs, Minnetronix Medical

While modern medicine is awash with high-tech electronics, from large surgical robots to tiny implanted sensors, there are several applications where electrical energy is applied directly to a patient to remove tissue, transport drugs, or obtain other clinical effects.

Given the obvious concerns of applying electricity to humans, developing these tools in a safe and efficient way is crucial.

This article briefly reviews these applications of electrical energy in medicine and new opportunities to refine existing technology such as radiofrequency (RF) ablation or achieve radical improvements using new energy modalities such as ablation. in pulsed field (PFA).

Ablation

The use of energy to remove diseased or disordered tissue can be affected by thermal means including RF, microwave and ultrasonic heat sources.

RF is the most mature and widespread technology, due to its low cost, procedural simplicity, compatibility with minimally invasive techniques, and well-understood performance. In RF ablation, a high-frequency electrical current is conducted through an ablation target such as a tumor or nerve, causing heating and eventually cell death. The high frequency allows it to pass through tissue with minimal muscle stimulation.

Modern RF ablation systems use high-precision control systems that optimize ablation volume with minimal procedure time and can be tailored to specific clinical needs.

Pulsed field ablation

PFA is the use of high intensity electric fields to eliminate cells by a non-thermal mechanism. Specifically, PFA degrades cell membranes in an irreversible process leading to cell death.

RELATED: Pulsed-Field Ablation Enables New Precision Cancer Treatments

PFA differs from RF in that it is tissue-selective, non-thermal, and conducive to pre-planning:

• Tissue-selective: Different tissue types have markedly different sensitivity to the electric fields used in PFA, which may allow for tissue type-selective ablation. Cardiac electrophysiology applications benefit from this selectivity by using PFA to eliminate cardiomyocytes (which are highly sensitive to PFA) while avoiding unwanted collateral damage to the smooth muscle adjacent to the esophagus (which is poorly sensitive to PFA). This selectivity can potentially provide a significant reduction in morbidity for prostate and pancreatic cancer compared to RF or other treatments.
• Non-thermal: While thermal ablation causes tissue necrosis and subsequent inflammatory response, PFA causes cell death by apoptosis, which is the natural mechanism of cell clearance and is non-inflammatory. Patients benefit from a faster post-operative recovery.
• Conducive to pre-planning: Thermal ablation is difficult to plan ahead because the thermal properties of tissues – “heat sinks” from nearby blood vessels, “insulators” from nearby structures, and inhomogeneity of the ablation target – vary so considerably that they make pre-planning difficult or intractable. However, the electric field-mediated PFA mechanism is affected by a smaller and less variable set of parameters, allowing for significant pre-planning and control of energy input. Future applications of PFA are likely to include patient-specific energy prescription derived from pre-procedural imaging and therapy simulation.

Although the PFA is an ablation tool, it also has a second act. By reducing the intensity of the electric field, these same electric pulses can trigger transient permeability in cell walls allowing the injection of drugs, genes or other “cargo”, a technique called electroporation, electropermeabilization or electrochemotherapy. Whatever its name, it is a large-scale physical technique for modifying a biological process on a cellular scale. Current clinical applications include delivery of large molecule drugs, DNA vaccines, and delivery of personalized gene therapies.

Using electroporation to deliver such a drug transforms the device into a combination product, triggering higher levels of regulatory concerns and scrutiny. In the development of such a system, most important is a clear understanding of the interaction between the tissue and the electric field and the boundary between reversible electroporation, irreversible electroporation (pulsed field ablation) and ablation thermal.

RELATED: In vivo electroporation is an engineered solution for drug and gene delivery

For companies developing energy-based therapies, there are many considerations to take into account in the early planning stages:

Translate experience with RF systems into PFA systems

Despite a similar fundamental architecture between RF and PFA, achieving the desired clinical results is not trivial and may require many iterations.

That said, RF design experience provides a solid foundation for developing PFA systems. There are architectural similarities, as well as similarities in the measurement of clinical outcomes that can be adapted. When considering developing a PFA system, having resources or partners who have extensive RF experience can help limit pitfalls.

Design customization, avoiding platform entanglements

It is tempting to use a platform architecture for investment hardware and focus development on disposable products or instruments. An out-of-the-box platform can get you to market faster on the first device, but will hinder expansion and generational improvements.

Being tied to a third-party platform can also involve a developer in licensing agreements and hamper lifecycle planning. In a market that is likely to become as dynamic as any tech space in its early years, it behooves companies to develop their own capital systems for maximum flexibility in expanding their portfolio.

Full product lifecycle integration

It is surprising how many companies continue to plan the development of complex systems such as PFA programs in a piecemeal fashion. A typical system consists of several major subsystems, and each of them consists of complex components and subassemblies.

A program of this magnitude must consider not only the immediate concerns from proof of concept to prototype, but also how that prototype will translate through the commercialization process.

Daniel Friedrichs, Ph.D., leads development engineering efforts at Minnetronix Medical for the commercialization of surgical energy devices, including in vivo electroporation systems and other energy-based medical, surgical and drug delivery therapies. He is named on over 35 patents and has worked with an extensive network of clients seeking to commercialize a wide range of technologies.