Devices using radiofrequency (RF) energy and electrical energy to deliver a controlled thermal injury to heat skin have proliferated within the nonablative skin treatment market since the introduction of Thermage in 2002. By delivering continuous monopolar RF energy, rather than pulsed heating, and repeatedly bringing the skin to therapeutic temperatures until maximal contraction is obtained, the Pelleve Procedure can give obvious cosmetic results confluently over all treated areas painlessly and with no downtime. In this article, the technique, mechanism of continuous RF heating, and apparent treatment requirements to produce these results are presented. Some controversies are also addressed.
The use of thermal injury to rejuvenate and repair aging facial skin has been part of the nonsurgical skin treatment for decades. Ablative light-based energies, the gold standard being full carbon dioxide laser resurfacing, offered the potential for remarkable smoothing and moderate tightening at a superficial level but came with significant pain, downtime, healing complications, and unwanted pigment-related changes. To reduce the downtime and complications, lesser-ablative and nonablative wavelengths were devised, but consistent results were still dependent on having the proper skin type, dosing, and healing response. The advent of the use of radiofrequency (RF) energy represented a change away from light-based energy, dependant on generating heat by absorption of energy by a target chromophore.
High-frequency electron flow, RF, generates heat because of the differences in impedance between tissue types ( Fig. 1 ).
Streaming electrons flow through the low resistance of the epidermis and dermis and meet the highly resistant fat at the dermal-subdermal junction. The sudden change in impedance turns kinetic energy into thermal energy, and the surrounding tissues are heated. This method not only eliminates the problem of heating unwanted target chromophores in the skin, such as melanin, as seen with light-based lasers, but also allows the heat to be generated in the deep dermis where existing residual collagen bundles are most plentiful. Also present at the dermal-subdermal junction are the connections of subdermal connective tissue bands that run through the subdermal fat to the underlying fascia. A controlled thermal injury reaching the threshold temperature for denaturing collagen of 60°C to 65°C can cause contraction of the thinned collagen in the deep dermis immediately and trigger an inflammatory response that generates new collagen bundle reorganization and thickening evident at 12 weeks as seen on electron microscopy. Controlled thermal contraction down the deep connective tissue bands causes a vertical and 3-dimensional tissue contraction, compacting the fatty globules without injuring the fat itself ( Fig. 2 ).
This mechanism is in contrast to that of uncontrolled thermal injury in which temperatures obtained in deep tissue can reach or exceed 70°C, causing a necrotic injury, irregular wound contraction, fat loss, and atrophy, which has been reported with pulsed devices. Despite the potential benefits of deep RF dermal heating, the pain associated with the treatments and the inability to generate consistently predictable results continue to plague this technology.
The shortcomings of pulsed RF-based devices include the need to deliver a safe dose without crossing the heat threshold that results in tissue necrosis. To assure this safety, the treatment protocols are typically the same for all patients, not allowing customization of the dosing to improve treatment outcomes. However, it is obvious that not all skins respond equally to the same amount of energy, thus, the reputation for unpredictable results. Pulsed devices also raise the temperatures rapidly, which can cause pain and necessitates surface cooling to prevent superficial burns. However, without the control of the actual depth of cooling, favorable thermal effects on the dermis, such as wrinkle reduction, horizontal contraction, and shrinkage of pores, can be limited in thinned-skin individuals because of the excessive cooling of the middle to upper dermis. The need to optimize these treatment parameters of the myriad of devices available has been emphasized by many investigators who have evaluated the devices that have come into the market.
Mechanism of controlled thermal injury
The Pelleve procedure, performed using the 4.0 S5 Surgitron (Ellman International, Oceanside, NY, USA), differs from other methods of delivering RF energy because it delivers a progressive but controlled thermal injury to the dermis and subdermis and overcomes many of the shortcomings associated with pulsed and fixed dosed methods.
A 4.0-MHz high-frequency energy is used, so the difference in resistance between the dermal skin and underlying fat is maximal and results in heat generation and diffusion only from the dermal-subdermal junction. The energy delivery is continuous, but because of the constant movement of the electrode over the treatment area, heating is gradual, rather than sudden, allowing the procedure to be painless but thorough when performed properly. A dispersion gel is used on the skin to allow smooth movement of the electrode and immediate dispersion of the energy of the otherwise-focused flow of electrons. Because all the heat generated emanates from deep at the dermal-subdermal junction as seen on infrared images ( Fig. 3 ), no direct surface cooling is required and potentially beneficial effects to the middle and upper dermis are not compromised. In addition, because the heat conducted down connective tissue bands is also gradual and progressive, it has been demonstrated that the fat compartments are contracted, giving 3-dimensional deep tissue contraction without the fat cells reaching temperatures that could cause atrophy or necrosis.
