Lesion Width Research Articles

Epicardial Ablation With Irrigated Electrodes

Ablation of ventricular tachycardia originating from the left ventricular (LV) epicardium is often limited by the radiofrequency power delivery. We compared the effect of bipolar vs. unipolar epicardial ablation on lesion size. Eleven excised pig hearts were superfused with saline (2 L/min). Unipolar ablation (25 or 30 W for 120 s) was performed between the LV epicardial saline-irrigated electrode and an indifferent electrode (n = 33 lesions). Bipolar ablation (25 or 30 W for 120 s) was performed between a 4-mm saline-irrigated-tip (20 ml/min) electrode on the LV epicardium and an opposing 10-mm non-irrigated-tip electrode on the LV endocardium (n = 38 lesions). Wall thickness did not differ between experiments (15.4 ± 2.4 vs. 15.3 ± 2.1 mm). Impedance was lower at the beginning and end of unipolar ablation than at the beginning and end of bipolar ablation (163.2 ± 20.3Ω and 109.9 ± 16.0Ω vs. 194.6 ± 23.3Ω and 127.1 ± 16.4Ω, respectively) (P<0.001). Epicardial lesion width did not differ between unipolar and bipolar ablation (10.1 ± 2.7 vs. 10.2 ± 2.4 mm), but lesion depth was greater with bipolar ablation (10.6 ± 2.7 vs. 7.5 ± 1.0 mm) (P<0.001). Unipolar ablation produced no transmural lesion, but bipolar ablation produced 15 (46%) (P<0.001). Steam pop occurred in 11 (29%) and 3 (9%) cases, respectively (P = 0.036). Bipolar ablation of the LV free wall is highly effective at creating an appropriately deep epicardial lesion.

Short‐term cast immobilisation is effective in reducing lesion propagation in a surgical model of equine superficial digital flexor tendon injury

Larger superficial digital flexor tendon (SDFT) injuries have a poorer prognosis than smaller lesions. During the inflammatory phase enlargement of the initial lesion is frequently noted, with biomechanical loading being recently proposed to play an important role. To evaluate the effect of lower limb cast immobilisation on tendon lesion propagation in an equine model of surgically induced SDFT injury. Core lesions were surgically induced in both front SDFTs of 6 young mature horses. At the end of surgery, one leg was randomly placed in a lower limb cast and the other leg (control) was bandaged for 10 days. Computerised ultrasonographic tissue characterisation performed at Days 10, 15, 21, 28, 35 and 42 allowed measurement of lesion length (cm) and width (expressed as a percentage of whole tendon cross-section). On Day 42 horses were subjected to euthanasia and both SDFTs were sectioned every centimetre to assess the lesion length macroscopically. Statistics were performed to compare cast vs. control legs with significance set at P<0.05. When all time points were combined, lesion length was 19% shorter (P<0.0001) and lesion width 57% smaller (P = 0.0002) in the cast legs (6.13 ± 0.12 cm; 6.90 ± 0.64%) than in the control legs (7.30 ± 0.21 cm; 10.85 ± 1.22%). On Day 42 the lesion length on macroscopic evaluation was 19% shorter (P = 0.04) in the cast (7.00 ± 0.36 cm) than in the control legs (8.33 ± 0.33 cm). Cast immobilisation for 10 days effectively reduced lesion propagation (length and width) compared to bandaging in an in vivo model of artificially-induced tendon lesions. A short period of cast immobilisation during the early phase of tendon healing may be an easy and cost-effective way to reduce the initial enlargement of lesion size and hence to improve prognosis.

Measurement of Histological and Radiographic Depth and Width of Occlusal Caries Lesions: A Methodological Study

Aim: To develop a measurement method to quantify the depth and width of occlusal caries lesions. Material and Methods: One hundred and ten extracted permanent molars with occlusal caries lesions were selected, then visually scored by ICDAS scoring system and then sectioned mesiodistally, resulting in a facial and a lingual fraction. Digital photos and radiographs were taken from each section. By randomization, one of the sections was chosen for further examinations. First digital photos were taken. Depth and width of the lesions were marked with arrows on the images both before (H_un-col) and after coloring (H_col) the sections. The same types of measurements were done on the radiographs (R). The relative dentinal depth and width of the lesions were measured in the same order. Results: Weighted intra- and interexaminer kappa value for ICDAS scorings varied between 0.85 and 0.90. Intraexaminer kappa for dentinal depth in 36 randomized selected teeth was calculated to 0.75 (H_un-col), 0.91 (H_col), 0.79 (R) and for dentinal width to 0.84 (H_un-col), 0.96 (H_col), 0.84 (R). Significant correlations were found between ICDAS scorings and the measurements of depth and width of lesions in H_un-col, H_col, and R (p < 0.000). The lowest difference was measured between H_un-col and H_col in both relative depth and width of the lesion with maximum differences up to 45% (H_un-col–H_col) and 73% (H_col–R). Conclusion: It is possible to measure depth and width of occlusal caries lesions by means of histological and radiographic technique with acceptably high reproducibility using this method.

Percutaneous Radiofrequency Ablation of Renal Parenchyma: Experimental Study on the Optimal Temperature and the Impact of Vasoactive Drugs

Radiofrequency (RF) is an efficient, inexpensive, safe, and friendly option for the management of small renal tumors. The objective was to evaluate the ideal temperature for renal cell destruction in dogs by RF and to verify whether the injection of vasoactive drugs, such as prostaglandin E1 and adrenaline, can help to improve the results, compared with "dry" RF ablation. The study was divided into three phases: Initially, 16 dogs of comparable weight underwent RF ablation of the renal parenchyma at temperatures of 80°C, 90°C, and 100°C. After that, seven other dogs received adrenaline (vasoconstrictor) and seven received prostaglandin E1 (vasodilator). Finally, the results from 14 animals were compared with those of the 16 (dry RF) dogs at the optimum temperature found. After 14 days, the animals underwent nephrectomy to evaluate the size of the lesions (width and depth), histology examination, and were then sacrificed. There were no clinical or surgical complications in any of the dogs, and none died before the 14th day after the procedure. The optimum temperature was found to be 90°C. Prostaglandin E1 resulted in significantly larger lesions (in depth and width) than adrenaline, with lower impedance. Prostaglandin did not increase the lesions compared with dry RF. All the kidneys presented total coagulation necrosis, with no viable cells in the histologic analysis of the treated tissue. In the ablation of renal cells by RF, prostaglandin produced larger lesions (in depth and width) than the same procedure using adrenaline, and its performance was similar to that of RF without injection of drugs.

Could it be advantageous to tune the temperature controller during radiofrequency ablation? A feasibility study using theoretical models

Purpose: To assess whether tailoring the Kp and Ki values of a proportional-integral (PI) controller during radiofrequency (RF) cardiac ablation could be advantageous from the point of view of the dynamic behaviour of the controller, in particular, whether control action could be speeded up and larger lesions obtained.Methods: Theoretical models were built and solved by the finite element method. RF cardiac ablations were simulated with temperature controlled at 55°C. Specific PI controllers were implemented with Kp and Ki parameters adapted to cases with different tissue values (specific heat, thermal conductivity and electrical conductivity) electrode–tissue contact characteristics (insertion depth, cooling effect of circulating blood) and electrode characteristics (size, location and arrangement of the temperature sensor in the electrode).Results: The lesion dimensions and Tmax remained almost unchanged when the specific PI controller was used instead of one tuned for the standard case: Tmax varied less than 1.9°C, lesion width less than 0.2 mm, and lesion depth less than 0.3 mm. As expected, we did observe a direct logical relationship between the response time of each controller and the transient value of electrode temperature.Conclusion: The results suggest that a PI controller designed for a standard case (such as that described in this study), could offer benefits under different tissue conditions, electrode–tissue contact, and electrode characteristics.

Piezosurgery prevents brain tissue damage: an experimental study on a new rat model

Piezosurgery is a promising meticulous system for bone cutting, based on ultrasound microvibrations. It is thought that the impact of piezosurgery on the integrity of soft tissue is generally low, but it has not been examined critically. The authors undertook an experimental study to evaluate the brain tissue response to skull bone removal using piezosurgery compared with a conventional drilling method. In Wistar male rats, a circular bone window was drilled to the parietal bone using piezosurgery on one side and a conventional bone drill on the other side. The behavioural performance of animals was evaluated using the motor BBB test and sensory plantar test. The brains of animals were evaluated by magnetic resonance imaging (MRI) and histology. The results of MRI showed significantly increased depth and width of the brain lesion in the region of conventional drilling compared with the region where piezosurgery was used. Cresylviolet and NF 160 staining confirmed these findings. There was no significant difference in any of the behavioural tests between the two groups. In conclusion, piezosurgery is a safe method for the performance of osteotomy in close relation to soft tissue, including an extremely injury-sensitive tissue such as brain.

Repair of bone erosions in rheumatoid arthritis treated with tumour necrosis factor inhibitors is based on bone apposition at the base of the erosion

ObjectivesTo investigate whether bone erosions in patients with rheumatoid arthritis (RA) show evidence of repair.Methods127 erosions were identified in metacarpophalangeal joints 2–4 of the right hands of 30 RA patients...

Optical Coherence Tomography and Autofluorescence Findings in Areas with Geographic Atrophy Due to Age-Related Macular Degeneration

To analyze outer retinal changes within the atrophic lesion in patients with geographic atrophy (GA) secondary to age-related macular degeneration. Twenty-one simultaneously obtained fundus autofluorescence (FAF, excitation, 488 nm; emission, 500-700 nm) and spectral-domain optical coherence tomography (SD-OCT) scans (Spectralis HRA+OCT; Heidelberg Engineering, Heidelberg, Germany) of 21 GA patients (mean age, 75.1 ± 7.4 years) were included and separately exported. Two readers independently graded the following parameters: width of the atrophic lesion on the FAF image at the site where the SD-OCT scan had been placed; and on the SD-OCT image, widths of the linear disruption of the outer nuclear layer, the external limiting membrane, and the inner and outer segments of the photoreceptor layer (IPRL) and width of the disruption of choroidal signal enhancement. Results. The mean width of the atrophic lesion by FAF imaging was 2.83 mm (95% confidence interval, 2.37-3.29). The linear disruption of choroidal hyperreflectivity showed the closest agreement with 2.83 mm (2.37-3.28), whereas the linear width of disrupted IPRL was larger (3.10 mm; 2.65-3.55). Overall, the width of the atrophic lesion correlated significantly with all five SD-OCT parameters (P < 0.0001, r = 0.96-0.99). These findings demonstrate that the atrophic lesions identified with FAF represent irreversible underlying outer retinal damage. The observation that the width of the atrophic lesion identified with FAF, although significantly correlated but not identical with the width of disruption within the cellular layers of the retina, is consistent with the dynamic nature of the disease. (ClinicalTrials.gov numbers, NCT00393692, NCT00599846.).

Performance of a Novel Dual-Electrode Bipolar Radiofrequency Ablation Device a Chronic Porcine Study

: Over recent years, a variety of energy sources, including bipolar radiofrequency, have been used to replace the traditional incisions of the Cox-Maze procedure for the surgical treatment of atrial fibrillation (AF). The purpose of this study was to evaluate the safety and efficacy of a novel dual-electrode bipolar radiofrequency ablation device Synergy (Atricure, Inc., Cincinnati, OH USA) for AF in a chronic porcine model. : Six domestic pigs underwent a modified Cox-Maze IV procedure without cardiopulmonary bypass using the Synergy device. Animals survived for 30 days. Each pig then underwent induction of AF and was killed to remove the heart en bloc for histologic assessment. Each ablation line was dissected perpendicularly at 5-mm intervals to assess the lesion width, depth, and transmurality. : All animals survived the operation. Electrical isolation of the left atrial appendage and the pulmonary veins were documented by pacing acutely and at 30 days after the operation in all six animals. All animals failed to be induced in AF at 30 days. There was no gross evidence of intra-atrial thrombus formation or stricture of the pulmonary veins. All ablations (n = 209) examined were discrete, linear, and transmural, with a mean lesion width of 3.0 ± 0.7 mm and a mean lesion depth of 5.4 ± 3.3 mm. The mean ablation time was 16.3 ± 4.4 seconds, with a mean total energy delivery of 238 ± 170 J. : The Atricure Synergy was able to create reliable chronic transmural lesions of the modified Cox-Maze IV procedure on a porcine beating heart without cardiopulmonary bypass. The ablation lines were significantly wider when compared with its predecessor, the Isolator II.

Bipolar Radiofrequency Lesion Geometry: Implications for Palisade Treatment of Sacroiliac Joint Pain

Ex vivo photographic temperature mapping of bipolar radiofrequency (RF) lesions in animal tissue is performed over a wide range of electrode tip spacings, tip lengths, tip diameters, tip temperatures, and lesion times. In vivo temperature measurements collected during clinical treatment of sacroiliac joint (SIJ) pain corroborate those collected ex vivo. Generation of a "strip lesion" connecting two separated bipolar electrode tips is demonstrated ex vivo for tip spacings as large as 20 mm. A rounded rectangular bipolar lesion with midline dimensions 12 mm × 15 mm × 8 mm (L × W × D) is demonstrated using 10 mm parallel tip spacing, 10 mm tip lengths, 20 gauge cannulae, 90°C tip temperature, and 3-minute lesion time. Lesion length can be increased to 18 mm by using 15 mm tip lengths. Lesion width can be increased to 17 mm by using 12 mm tip spacing. The size of conventional bipolar lesions can exceed the size of lesions produced both by conventional monopolar RF (12 mm × 7 mm × 7 mm ellipsoidal) and by cooled monopolar RF as used in spinal pain management (10 mm × 10 mm × 10 mm spherical). SIJ pain is treated by placing 5 to 7 straight RF cannulae perpendicular to the dorsal sacrum and producing 4 to 6 overlapping bipolar RF lesions between the dorsal sacral foramina and the ipsilateral SIJ. This bipolar "palisade" (a defensive fence) creates a continuous lesion spanning the region through which multiple sacral lateral branch nerves travel along irregular, branching paths to reach the SIJ.

Comparison of the Carbon Dioxide Laser and the Radiofrequency Unit for Feline Onychectomies

This study compared the collateral tissue damage and incisional bridging with granulation tissue via histopathological examination following feline onychectomy performed by radiofrequency (RF) and carbon dioxide (CO(2)) laser. Two cats were euthanized, and their digits were harvested for histopathological evaluation on days 1, 3, and 7 post-onychectomy. Each digit was evaluated for total lesion width, total necrosis width, and degree of edema, hemorrhage, and inflammation. This study found few significant differences in collateral tissue damage between RF and CO(2) laser, but more incisional bridging by granulation tissue was noted with RF for feline onychectomies. These results indicate that RF for feline onychectomy is a reasonable alternative to CO(2) laser in regard to collateral tissue damage and bridging of the incision by granulation tissue. In addition, RF is not accompanied by the strict safety considerations and initial expense of acquisition of a CO(2) laser.

The Influence of Local Anatomy on the Outcome of Treatment of Gingival Recession Associated With Non‐Carious Cervical Lesions

The present study evaluates the influence of local anatomy on the reduction in relative gingival recession (Delta RGR) and gain of clinical attachment level (Delta CAL) achieved by coronally advanced flap alone (CAF), CAF plus restoration (CAF + R), subepithelial connective tissue graft alone (CTG), and CTG plus restoration (CTG + R), to treat Miller Class I gingival recessions associated with non-carious cervical lesions. A total of 78 defects in maxillary canines or premolars were included, and received one of the following treatments: CAF, CAF + R, CTG, or CTG + R. Delta RGR and Delta CAL after 6 months were associated with cervical lesion height (CLH), cervical lesion width, cervical lesion depth (CLD), keratinized tissue width, keratinized tissue thickness, papillae width, papillae height, bone level (BL), and post-surgical position of the gingival margin using stepwise multivariate linear regression. CLH was statistically associated with Delta RGR when CAF (P = 0.02) and CTG + R (P = 0.0002) were analyzed and statistically associated with Delta RGR when overall data (P = 0.005) from both CTG groups were analyzed. CLD was significantly associated with Delta RGR in the CAF group (P = 0.0045). BL was statistically associated with Delta RGR when evaluating the CTG group (P = 0.02). It was also significantly associated with Delta CAL when considering the CTG (P = 0.01) and the overall data (P = 0.04) from CAF (CAF and CAF + R). It can be concluded that CLD may influence Delta RGR when CAF is performed to treat combined defects. Additionally, BL may not negatively influence Delta RGR when the CTG technique is used.

Your Index Finger Is Your Measure!

An objective assessment of open wounds, scars, or various forms of skin and soft tissue lesions begins with the description of its size. In clinical practice we frequently hesitate to perform a thorough measurement and roughly estimate its length and width (and height or depth if necessary) with our naked eye, but these estimations are usually prone to significant variations among different observers. Paper rulers and measuring tapes are very handy and inexpensive tools yet many physicians do not carry them in their pockets on a regular basis. We describe a new and inexpensive method that can be readily applied for measurement purposes. A practical and readily available method to measure various small-to-moderate-sized defects and lesions as well as some intraoperative details necessitates nothing more than our bare hands. Each individual’s hand has specific landmarks such as fingertips and interphalangeal joint creases. Determining and memorizing the distances between these landmarks (Fig. 1) can be helpful in measuring length and width as well as height or depth of defects and lesions throughout the body. Measurement is a key point in the evaluation of a patient with visible defects and lesions. As far as surgical intervention is concerned, an accurate measurement facilitates preoperative planning and improves postoperative results. Thus, the value of this simple task is unquestionable in plastic and reconstructive surgery, which deals mainly with defect closure, functional restoration, and aesthetic improvement. Paper rulers and measuring tapes are inexpensive and simple tools used frequently for measurement purposes, yet they are forgotten in other places such as one’s desk during patient visits. They also frequently go missing. Since our bare hands do not have these drawbacks, they are a good candidate for measurement tasks. With this method many measurements such as the three-dimensional size of a decubitus ulcer, length and width of a skin lesion (Fig. 2), and the length of the areolar diameter before and after breast surgery (Fig. 3) can be readily performed without the need for a ruler. Also, the rough and occasionally misleading estimation done with the naked eye can be improved. This method is practical and easy to perform, necessitates no specific instrument or tool other than the bare hand, and it provides a better estimation of the size of the defect than the naked eye alone; nevertheless, the measurement with a ruler or measuring tape obviously remains the gold standard.

Use of High-Frequency, High-Resolution Ultrasound Before Mohs Surgery

Although ultrasound imaging is employed ubiquitously today, its use to examine and assess the skin is a relatively new technology. We explored the clinical application and use of high-frequency, high-resolution ultrasound in Mohs micrographic surgery. To evaluate the ability of ultrasound to accurately determine lesion length and width of tumor borders in order to reduce the number of surgical stages. This was an institutional review board-approved single-center study of 26 Mohs surgery patients. Ultrasound images were taken to record lesion dimensions, and then the investigator documented clinical estimation of the first stage. Extirpation of the tumor and histological analysis were performed thereafter. The results of 20 patients were included in the analysis. A paired-samples t-test revealed no significant difference between clinical and ultrasound widths (t=-1.324, p=.20). Similarly, there was no significant difference between the lengths found from clinical assessment and ultrasound (t=-1.093, p=.29). For different tumor types, there was no significant difference between clinical and ultrasound widths or lengths for basal cell carcinoma (t=-1.307, p=.23; t=-1.389, p=.20) or squamous cell cancer (t=-0.342, p=.73; t=0.427, p=.68). CONCLUSION There is a diagnostic role for high-resolution ultrasound in Mohs surgery regarding the delineation of surgical margins, but its limitations preclude its practical adoption at this time.

Surgical versus pathological excision margins—an excision too far?

A common observation by clinicians who surgically excise skin pathology is the discrepancy between the measured size of the surgical specimen and that of the measurements reported by the examining pathologist. This discrepancy can often be the difference between whether, in the case of skin malignancies, the patient requires further wider excision, follow-up and, in cases where relevant, discharge. Could it therefore mean that patients are needlessly undergoing further excisions that could be avoided with more careful attention to specimen measurements and specimen ‘shrinkage,’ both surgically and pathologically? We measured the length and width of skin lesions excised pre- and post-operatively and compared these measurements with the reported histopathological measurements. A significant difference in length (p = 0.000) and width (p = 0.001) exists between pre- and post-operative measurements. No significant difference exists between post-operative and pathological measurements of length (p = 0.072) or width (p = 0.157). Length of time preserved in 10% formalin did not make a significant difference to specimen size (p = 0.47). The aim of clinicians is to excise fully all skin pathology relevant for excision, ensuring sufficient clear margins to prevent potential recurrence whilst trying to sacrifice as little ‘normal’ tissue as possible in the process. What this study helps to highlight is the fact that clinicians cannot take for granted the reported measurements on the histopathology reports, upon which subsequent clinical management on reported excision margins are often based, without taking into consideration documented excision margins and subsequent allowance for significant specimen shrinkage, often resulting, for malignancies, in further wider excisions that are potentially disfiguring, and in the authors opinion, in more cases than currently thought, unnecessary. If one also factors in the fact that malignant cells shrink less than both benign tumours and, most importantly, normal skin, then subsequent reported pathological margins may be increasingly inaccurate as the excision margins may indeed be greater.

Considerations for Thermal Injury Analysis for RF Ablation Devices~!2009-09-09~!2009-12-19~!2010-02-04~!

Background:The estimation of lesion size is an integral part of treatment planning for the clinical applications of radiofrequency ablation. However, to date, studies have not directly evaluated the impact of different computational estimation techniques for predicting lesion size. In this study, we focus on three common methods used for predicting tissue injury: (1) iso-temperature contours, (2) Cumulative equivalent minutes, (3) Arrhenius based thermal injury.Methods:We created a geometric model of a multi-tyne ablation electrode and simulated thermal and tissue injury profiles that result from three calculation methods after 15 minutes exposure to a constant RF voltage source. A hybrid finite element technique was used to calculate temperature and tissue injury. Time-temperature curves were used in the assessment of iso-temperature thresholds and the method of cumulative equivalent minutes. An Arrhenius-based formulation was used to calculate sequential and recursive thermal injury to tissues.Results:The data demonstrate that while iso-temperature and cumulative equivalent minute contours are similar in shape, these two methodologies grossly over-estimate the amount of tissue injury when compared to recursive thermal injury calculations, which have previously been shown to correlate closely with in vitro pathologic lesion volume measurement. In addition, Arrhenius calculations that do not use a recursive algorithm result in a significant underestimation of lesion volume. The data also demonstrate that lesion width and depth are inadequate means of characterizing treatment volume for multi-tine ablation devices.Conclusions:Recursive thermal injury remains the most physiologically relevant means of computationally estimating lesion size for hepatic tumor applications. Iso-thermal and cumulative equivalent minute approaches may produce significant errors in the estimation of lesion size.

Considerations for Thermal Injury Analysis for RF Ablation Devices

Background: The estimation of lesion size is an integral part of treatment planning for the clinical applications of radiofrequency ablation. However, to date, studies have not directly evaluated the impact of different computational estimation techniques for predicting lesion size. In this study, we focus on three common methods used for predicting tissue injury: (1) iso-temperature contours, (2) Cumulative equivalent minutes, (3) Arrhenius based thermal injury. Methods: We created a geometric model of a multi-tyne ablation electrode and simulated thermal and tissue injury profiles that result from three calculation methods after 15 minutes exposure to a constant RF voltage source. A hybrid finite element technique was used to calculate temperature and tissue injury. Time-temperature curves were used in the assessment of iso-temperature thresholds and the method of cumulative equivalent minutes. An Arrhenius-based formulation was used to calculate sequential and recursive thermal injury to tissues. Results: The data demonstrate that while iso-temperature and cumulative equivalent minute contours are similar in shape, these two methodologies grossly over-estimate the amount of tissue injury when compared to recursive thermal injury calculations, which have previously been shown to correlate closely with in vitro pathologic lesion volume measurement. In addition, Arrhenius calculations that do not use a recursive algorithm result in a significant underestimation of lesion volume. The data also demonstrate that lesion width and depth are inadequate means of characterizing treatment volume for multi-tine ablation devices. Conclusions: Recursive thermal injury remains the most physiologically relevant means of computationally estimating lesion size for hepatic tumor applications. Iso-thermal and cumulative equivalent minute approaches may produce significant errors in the estimation of lesion size.

The Effectiveness of Chemoprevention Agents Is Underestimated When Lesion Sizes Are Rounded

Change in the area of premalignant lesions is an end point in estimating the efficacy of chemopreventive agents. When examiners round measurements of lesion length and width, they introduce variability, which perturbs the relative percent change in lesion area and, consequently, the percent of subjects showing a clinical response. We use simulations to illustrate the resulting bias when the agent under test is effective in reducing lesion area. We simulated 500 oral leukoplakia lesions per run, with 2,500 runs at each of five levels of agent effectiveness, namely, true relative percent reduction in area of 25%, 45%, 50%, 55%, and 75%. Realistic values of lesion lengths and widths were generated randomly and then rounded to the nearest multiple of five. The product is the distribution of mean relative percent change in lesion area and the corresponding percent of subjects showing a clinical response. Even the fifth percentile of the distribution of mean relative percent change in lesion area consistently underestimated the true value, by about 6 percentage points. The percent showing a clinical response was underestimated by 50%, 37%, and 11% for true values of reduction in lesion area of 50%, 55%, and 75%, respectively. This could easily double the required sample size for a modest phase II study. We suggest that it is cost-effective to train observers of lesion length and width to eschew rounding of measurements in the chemoprevention setting.

Efficacy of a novel bipolar radiofrequency ablation device on the beating heart for atrial fibrillation ablation: A long-term porcine study

Over recent years, a variety of energy sources have been used to replace the traditional incisions of the Cox maze procedure for the surgical treatment of atrial fibrillation. This study evaluated the safety and efficacy of a new bipolar radiofrequency ablation device for atrial ablation in a long-term porcine model. Six pigs underwent a Cox maze IV procedure on a beating heart off cardiopulmonary bypass using the AtriCure Isolator II bipolar ablation device (AtriCure, Inc, Cincinnati, Ohio). In addition, 6 pigs underwent median sternotomy and pericardiotomy alone to serve as a control group. All animals were allowed to survive for 30 days. Each pig underwent induction of atrial fibrillation and was then humanely killed to remove the heart en bloc for histologic assessment. Magnetic resonance imaging scans were also obtained preoperatively and postoperatively to assess atrial and ventricular function, pulmonary vein anatomy, valve function, and coronary artery patency. All animals survived the operation. Electrical isolation of the left atrial appendage and the pulmonary veins was documented by pacing acutely and at 30 days in all animals. No animal that underwent the Cox maze IV procedure was able to be induced into atrial fibrillation at 30 days postoperatively, compared with all the sham animals. All 257 ablations examined were discrete, linear, and transmural, with a mean lesion width of 2.2 +/- 1.1 mm and a mean lesion depth of 5.3 +/- 3.0 mm. The AtriCure Isolator II device was able to create reliable long-term transmural lesions of the modified Cox maze procedure on a beating heart without cardiopulmonary bypass 100% of the time. There were no discernible effects on ventricular or valvular function.

Histological comparison of two different fractional photothermolysis devices operating at 1,550 nm

There are a wide variety of fractional resurfacing devices that are available and it is important to understand the tissue effect of different devices at different parameters to ensure a well-controlled treatment. Thus, we have chosen to characterize and compare two different fractional laser devices, the Fraxel SR750 and SR1500 (re:store) (Solta Medical, Hayward, CA). While the SR750 has a fixed focus spot diameter, the SR1500 features an internally controlled zoom optic allowing for an adjustable spot size. Exposures were performed in vitro on human skin samples at 37 degrees C. The exposures were performed for the SR750 at pulse energies between 6 and 40 mJ at 125 MTZ/cm(2) with up to 20 passes, and for the SR1500 between 6 and 100 mJ, at Treatment Level 7 and 8 passes. The skin samples then were processed for serial frozen sectioning, stained with Nitro-Blue-Tetrazolium-Chloride (NBTC) and lesion depth and width was determined. Mean lesion depth was significantly greater for lesions treated with the SR1500 laser compared to the SR750 at pulse energies of 6, 10, 30, and 40 mJ (P<0.001) with a borderline difference at 20 mJ. Mean lesion width was comparable for energies up to 20 mJ and relatively increased for the SR1500 for higher energies. The depth-to-width ratio (DWR) was in general higher for the SR1500, reaching significance at 6, 10, and 40 mJ. We have characterized the lesion depth and width for the for two different Fractional Photothermolysis devices (SR750 vs. SR1500). The device with the adjustable spot size (SR1500 or Fraxel re:store) provides generally deeper lesions at the same energy level. It remains to be shown whether increased lesion depth improves efficacy for certain clinical applications.