Prospective Multicenter Clinical Trial of a Temperature-Controlled Subcutaneous Microneedle Fractional Bipolar Radiofrequency System for the Treatment of Cellulite.

BACKGROUND: A bipolar fractional radiofrequency (RF) device was developed to generate cutaneous thermal injuries using a temperature-controlled microneedle electrode array. OBJECTIVE: Evaluate safety and efficacy of a novel subcutaneous microneedle RF for treatment of posterolateral thigh cellulite. METHODS: The study design was an institutional review board-approved multicenter clinical trial after a per-protocol analysis. Fifty subjects with Nurnberger-Muller Grade II or III cellulite were enrolled at 4 treatment centers and received 1 subcutaneous microneedle RF treatment (67°C/4-second duration). Efficacy was evaluated by blinded grading by 3 dermatologists using randomized, standardized photographs and investigator grading at baseline, 1-, 3-, and 6-month follow-up. As per the Food and Drug Administration, treatment success was defined by ≥1-point improvement on dimple number or severity of undulation irregularities scales by at least 2 of 3 blinded physicians. Study subjects' self-assessments and satisfaction questionnaires and procedural pain levels and adverse events were monitored. RESULTS: Blinded physician evaluations revealed a procedural success rate of 93% at 6-month follow-up. Procedural pain level was 3.74 ± 1.96 on a 10-point scale. There were no adverse events. Seventy-five percent of subjects were satisfied with the results at 6-month follow-up. CONCLUSION: The results indicate that subcutaneous microneedle RF treatment is safe and effective for long-term treatment of Type II and III cellulite in a single session.

Randomized, blinded, 3-arm clinical trial assessing optimal temperature and duration for treatment with minimally invasive fractional radiofrequency.

BACKGROUND: A previous multicenter clinical trial of a needle-based fractional radiofrequency (FRF) treatment for facial and neck rhytides and laxity counterintuitively demonstrated a mean target temperature and treatment duration of 69.5 °C and 4.9 seconds for subjects with lesser improvement and 67 °C and 4.2 seconds for greater improvement. OBJECTIVE: To determine optimal temperature and duration settings for maximal clinical results in rhytides and laxity from a single FRF treatment of the face and neck. METHODS: A randomized, blinded, 3-arm clinical evaluation of FRF at a series of temperatures from 52-57 °C to 67 °C. Three blinded plastic surgeons and dermatologists scored rhytides using the Fitzpatrick Wrinkle Assessment Scale and laxity using the Alexiades Laxity Assessment Scale at 1, 3, and 6 months. RESULTS: Blinded grading showed optimal improvement at 67 °C and 3 seconds and decreased efficacy below 67 °C, with mean rhytide reductions of 40, 29, and 25% and mean laxity reductions of 34, 36, and 25% in Arms 3 (67 °C), 2 (62 °C), and 1 (52 °C-57 °C), respectively. A 100% response rate was observed for all subjects treated at 62 °C to 67 °C target temperature. CONCLUSION: The optimal target dermal temperature for facial and neck rhytide and laxity treatment is 67 °C and duration of 3 to 4 seconds with a 100% response rate after a single FRF treatment.

Prospective multicenter clinical trial of a minimally invasive temperature-controlled bipolar fractional radiofrequency system for rhytid and laxity treatment.

BACKGROUND: A minimally invasive fractional bipolar radiofrequency (FRF) was developed. OBJECTIVE: To evaluate safety and efficacy of FRF in reducing face and neck rhytides and laxity. MATERIALS AND METHODS: This prospective, open-label, multicenter clinical trial enrolled 100 subjects with mild to severe facial and neck rhytides and laxity at seven centers in a per-protocol analysis. One single-pass FRF treatment was administered through five 32 g-needle electrode pairs at a preselected real-time fixed temperature of 62 to 78°C, energy duration for 3 to 5 seconds, and impedance restrictions of 200 to 3,000 Ohms, ensuring intradermal delivery. Five blinded dermatologists and plastic surgeons graded randomized standardized baseline and follow-up photographs of 53 and 42 subjects at 3- and 6-month follow-up intervals, respectively, using the Fitzpatrick wrinkle and Alexiades-Armenakas laxity scales. Subject assessments and adverse events were recorded in 100 subjects. RESULTS: Blinded evaluations revealed correct pre- and post-treatment identification in 100% of scored cases, mean improvement of 25.6% on the Fitzpatrick Wrinkle Scale and 24.1% on the Alexiades-Armenakas laxity scale at 6 months, and 100% response rate for rhytides and 95% for laxity. Subgroup analysis revealed maximal rhytid reduction in the mean target temperature of 66.7, energy duration of 4.2 seconds, and volume of denatured collagen of mm(3) denatured collagen group. Adverse events included transient erythema, edema, and ecchymoses, resolving within 1 to 5 days, and two incidents of temporary pinpoint depressions. More than 90% of subjects were satisfied or very satisfied. CONCLUSION: Real-time temperature-controlled FRF is a highly reproducible, safe, effective nonsurgical treatment of face and neck rhytides and laxity and provides important insights into neocollagenesis, neoelastogenesis, and clinical outcomes.

Elastometry and clinical results after bipolar radiofrequency treatment of skin.

BACKGROUND: The healing process of a novel radiofrequency bipolar system was recently shown to produce a profound increase in collagen and elastin content. OBJECTIVE: To determine the relationship between subjective clinical improvement scores and changes in objective measures of mechanical skin properties. METHODS AND MATERIALS: Elastometry measurements were made at baseline and 3 months after treatment. All patients received a treatment zone on the lower face. Patient assessments of results and physician ratings of wrinkle and skin laxity were collected at baseline and 3 and 6 months after treatment. Elastometry and clinical results were then compared. RESULTS: Three months after treatment, elastometry measurements showed statistically significant improvement (5-12% decrease in Young's Modulus and 10-16% decrease in retraction time). The average improvement correlated to a 2.6-year improvement in skin property. Physician scores at 3 months showed a statistically significant improvement of 1.42 grades on the Fitzpatrick scale for wrinkles and 0.66 grades on the Alexiades scale for skin laxity, increasing to 1.57 and 0.70 improvement, respectively, at 6 months. Eighty-nine percent and 91% of patients were satisfied or very satisfied with the procedure at 3- and 6-month follow-up, respectively. CONCLUSION: Elastometry data showed an average decrease in Young's Modulus and retraction time, both of which suggest that radiofrequency bipolar treatment resulted in more youthful skin. Better mechanical characteristics were consistent with improvements in wrinkles, laxity, and skin quality and appearance.

A predictive model of minimally invasive bipolar fractional radiofrequency skin treatment.

BACKGROUND: A novel bipolar fractional radiofrequency (FRF) system with temperature feedback was recently developed for facial laxity and rhytid treatment. The study objective was to develop a model based on published in vivo human skin data that could be extrapolated to aid physicians in making future dosimetry choices under clinically relevant conditions. METHODS: A standard electrode pair designed for use with the FRF system was modeled using finite element analysis (FEA). The model incorporated temperature feedback from sensors within the electrodes, selectable target dermal temperatures, and an epidermal cooling plate. The model was validated using data obtained during clinical treatments. Thermal injury as a function of target temperatures and electrical conductivity was simulated and then validated using in vivo histology results. RESULTS: Lesion size predicted by the model matched histology samples. Lesion width and height were 1.65 and 1.24 mm compared to 1.75 and 1.21 mm for the model versus in vivo, respectively. The thermal profile remained confined between the proximal and distal ends of the electrodes. Ninety-six percent of power was deposited in the dermis. Dose-response curves showed a nonlinear volume increase to 1.7 and 4.7 mm(3) at target temperatures of 65 and 75 degrees C, respectively, and a low sensitivity to electrical conductivity variation. CONCLUSION: FEA of the Bipolar FRF system revealed that isotherms were mainly within the dermis. Lesion volume was found to be less sensitive to changes in electrical conductivity than to target temperature and duration. Simulation results matched well the in vivo lesion dimensions. To our knowledge, this is the first model of bipolar FRF treatment capable of accurately predicting the thermal response of human skin in vivo. The findings of this study allow for the development of accurate dose-response curves to aid physicians in parameter selection and achieving efficacy and safety profiles.

Dose response curves for microwave ablation in the cardioplegia-arrested porcine heart.

INTRODUCTION: Microwave ablation has been used clinically for the surgical treatment of atrial fibrillation, particularly during valve procedures. However, dose- response curves have not been established for this surgical environment. The purpose of this study was to examine dosimetry curves for the Flex 4 and Flex 10 microwave devices in an acute cardioplegia-arrested porcine model. METHODS: Twelve domestic pigs (40-45 kg) were acutely subjected to Flex 4 (n = 6) and Flex 10 (n = 6) ablations. On a cardioplegically arrested heart maintained at 10-15(o)C, six endocardial atrial and seven epicardial ventricular lesions were created in each animal. Ablations were performed for 15 s, 30 s, 45 s, 60 s, 90 s, 120 s, and 150 s (65 W, 2.45 GHz). The tissue was stained with 2,3,5-triphenyl-tetrazolium chloride and lesions were sectioned at 5 mm intervals. Lesion depth and width were determined from digital photomicrographs of each lesion (resolution +/- .03 mm). RESULTS: Average atrial thickness was 2.88 +/- .4 mm (range 1.0 to 8.0 mm). 94% of ablated atrial sections created by the FLEX 4 (n = 16) and the FLEX 10 (n = 16) were transmural at 45 seconds. 100% of atrial sections were transmural at 90 seconds with the FLEX 10 (n = 14) and at 60 seconds with the Flex 4 device (n = 15). Lesion width and depth increased with duration of application. CONCLUSION: Both devices were capable of producing transmural lesions on the cardioplegically arrested heart at 65 W. These curves will allow surgeons to ensure transmural ablation by tailoring energy delivery to the specific atrial geometry.

In vitro and in vivo evaluation of the thermal patterns and lesions of catheter ablation with a microwave monopole antenna.

BACKGROUND: Radiofrequency (RF) catheter ablation is an effective treatment for supraventricular tachycardia. The effectiveness of the technique is at times limited by the small lesion size produced by RF energy delivery. Previous reports have indicated that microwave energy is capable of producing a larger volume of heated tissue than radiofrequency energy, raising the possibility that microwave energy may offer a potential alternative energy source to radiofrequency for the substrate ablation of certain arrhythmias such as ventricular tachycardia or atrial flutter. METHODS: The present study evaluated the thermal profiles of a monopole microwave antenna delivering energy at 2.45 GHz frequency in a phantom tissue-equivalent material with dielectric and thermal properties similar to myocardium. In addition, microwave catheter ablations were performed in vivo in the ventricles of goats prior to the examination of the lesions. RESULTS: The measured thermal profiles in the phantom revealed that the antenna is capable of producing heating to a temperature associated with myocardial necrosis to a controllable depth that can be more than 8 mm, while the endocardial temperature is maintained relatively low. The ablation volume is significantly reduced but is still effective when there is only a partial contact between the antenna and the tissue surface. In vivo studies on goat models confirmed that the monopole antenna can produce a deep transmural lesion in the left ventricle without causing coagulation or charring on the endocardial surface.

Application of microwave energy in cardiac tissue ablation: from in vitro analyses to clinical use.

BACKGROUND: Recently, there has been renewed interest in simplifying a surgical cure for atrial fibrillation. Microwave energy ablation provides an easier and faster surgical technique, in lieu of traditional "cut and sew," which can also be applied on the beating heart. METHODS: Specific absorption rate (SAR) and thermal profiles were determined after microwave energy ablation intended for clinical application. Lesion geometry measures obtained in vitro with tissue equivalent media were compared with values collected from animal myocardium. RESULTS: Thermal profile analysis demonstrated lesion penetration depths of 2.5, 3, and 5 mm after 8, 16, and 24 seconds, respectively, with microwave power application of 40 W. Dosimetric studies performed using animal myocardium corresponded to the thermal profile analysis and showed that lesion depth was controlled by the output power and the ablation time. CONCLUSIONS: Lesion geometry in tissue using microwave energy is similar to that predicted from in vitro analysis. The ablation depths and thermal profile of microwave ablation is favorable for performing atrial ablation, and this is corroborated by favorable early clinical results.