Powering Electrosurgery: Precise Control and Delivery of RF Energy
Posted October 23, 2023 by Todd Huston
Radio Frequency Ablation (RFA)
RFA is a medical procedure in which part of a tumor, the electrical conduction system of the heart, or other dysfunctional tissue is ablated using the heat generated from medium frequency alternating current (typically in the range of 350 – 500 kHz). RFA may be performed to treat tumors in the lung, liver, kidney and bone and, less commonly, other organs. Once the diagnosis of tumor is confirmed, a needle-like RFA probe is placed inside the tumor through which RF waves are passed. This increases the temperature within the tumor tissue, resulting in its destruction.
RF energy is also commonly used in heart tissue to destroy abnormal electrical pathways that are contributing to a cardiac arrhythmia, as a minimally invasive treatment for varicose veins, and as a safe and effective treatment for Barrett's esophagus, a condition which causes changes to the cells lining the esophagus.
Another RFA medical application is rhizotomy, a technique that has been developed to treat chronic pain arising from the facet joints in the lower (lumbar) region of the back. Here, RF energy is applied to produce heat on targeted nerves – specifically those that surround the facet joints (the lumbar medial branches of the dorsal ramus of the spinal nerves). By generating heat around the nerve, the nerve is ablated, thus destroying its ability to transmit signals to the brain. The nerves to be ablated are identified through injections of local anesthesia (such as lidocaine) around the medial branches prior to the RFA procedure to first confirm the diagnosis.
Medical Equipment Demands
Currently, devices that apply energy to tissues are utilized in a majority of surgical procedures1. These systems require precise control and delivery of RF energy. Looking across the range of RF electrosurgery units, the majority of systems operate in a span from 50 W – 400 W, with 300 W being the most typical for cutting, coagulation and vessel sealing. Typical output frequencies range from 200 kHz ± 1% (square wave) to 480 kHz (quasi-sinusoidal voltage waveform), although some devices use frequencies as high as 4 MHz.
With an omnipresent focus on surgical efficiency, hospitals and surgeons are looking for systems that reduce procedure times, improve patient outcomes with robust operator safety. There is also demand for multifunctional platforms that reduce the number of different surgical instruments that must be trained and used. For example, a growing interest in pulsed field ablation (PFA) - a technique that uses ultra-short pulses to improve therapeutic effects while minimizing thermal issues – drives the desire for hybrid systems with the ability to toggle between RF and pulsed field energy. These hybrid systems bring together the best of both worlds and are likely to rise in popularity. In addition, with the rise of surgical robotics, it is expected that RF energy platforms will seamlessly integrate with robotic assisted systems. Finally, and unsurprisingly, rapid innovation in medical technologies has made short product design cycles a business imperative for medical equipment manufacturers.
Power Delivery and Control for RF Electrosurgery
Advanced Energy has a long history of developing and supporting RF generator solutions for medical applications with standard, configurable and customizable technologies that can reduce time-to-market and increase system reliability and functionality. AE’s broad standard medical portfolio, for example, provides multiple options for the next generation of RF devices. Addressing AC-DC configurable power, AC-DC low-/mid-power, high-voltage AC-DC, low- and high-voltage DC-DC and RF and pulsed electric field power, these products offer a wide selection of IEC60601-1 medically certified advanced medical power solutions.
Advanced Energy Excelsys CS1000
Among the AE power platforms targeted at medical applications are Excelsys CS1000 fanless, high-efficiency single-output power supplies, Artesyn LPS open frame single-output, low-power AC-DC power supplies, uMP configurable, low-power AC-DC power supplies, and the ATA Series of 3 W isolated DC-DC converters.
Where AE’s broad portfolio of standard products do not meet a particular application’s technical specifications, AE’s experienced field application engineers and engineering development teams can quickly provide modifications and full custom solutions, from a single component to a full system. For a full custom solution, AE’s Versatile Power® team has extensive experience designing and building RF medical generators. Several medical device customers have chosen Versatile Power® products to create full custom solutions that meet exacting technical specifications for RF energy delivery.
Typical options for such custom solutions are as below:
- Output voltage: Up to 700 Vpp
- Power: Up to 600 W; typical range is 50-400W
- Frequency: Up to 8 MHz, typical range is 200 - 500 KHz
- Polarity: Bipolar
- Signal shape: square wave, sinusoidal, modulated sinusoidal, with different programmable carrier frequency, programmable rise and fall times of the modulated bursts of waveforms and random delays in between the modulated bursts of waveforms
The efficacy of RF electrosurgery stems as much from groundbreaking technological innovations as from the uniformity and dependability of its power source. The degree of precision and safety inherent in RF electrosurgery is contingent on the delivery of consistent energy. As medical procedures evolve in sophistication, there is a proportionate increase in the demands placed on the power infrastructure. Particularly in procedures such as RF electrosurgery, precision is imperative, and there is no room for compromise.
A stable and superior-quality power supply is crucial for accurate delivery of RF energy, which in turn enhances surgical precision and mitigates the risk of tissue damage. The components of RF electrosurgery devices are highly sensitive and can experience degradation over time, especially when subjected to irregular power. A consistent power supply is instrumental in extending the longevity of the equipment.
Advanced Energy stands at the forefront of precision power technology, providing meticulously engineered, reliable power conversion solutions for RF medical devices. AE power supplies are designed to ensure that the RF energy delivered is stable and devoid of unwanted fluctuations, enabling consistent and high-precision medical applications. Cutting-edge technologies for highly reliable, precision power conversion in medical systems and extensive application knowledge and compliance expertise, ensure that medical equipment manufacturers can deliver RF systems that achieve optimal performance with the minimum possible design time and at the lowest total cost of ownership.
- Meeusen FC, Guédon ACP, Arkenbout EA, van der Elst M, Dankelman J, van den Dobbelsteen JJ. The Art of Electrosurgery: Trainees and Experts. Surg Innov. 2017;24(4):373-378. doi:10.1177/1553350617705207