Determination of the Most Efficient Temperature for Radiofrequency Ablation of Renal Cells: A Prospective Study in Dogs

Background and Purpose: Radiofrequency (RF) ablation of renal tumors is a major technique for tumor cell destruction while preserving healthy renal parenchyma. There is no consensus in the literature regarding the optimal temperature, impedance, and time for RF application for effective cell destruction. This study investigated two variables while keeping time unchanged: Temperature for RF cell destruction and tissue impedance in dog kidneys. Materials and Methods: Sixteen dogs had renal punctures through videolaparoscopy for RF interstitial tissue ablation. A RF generator was applied for 10 minutes to the dog's kidney at different target temperatures: 80 degrees C, 90 degrees C, and 100 degrees C. On postoperative day14, the animals were sacrificed and nephrectomized. All lesions were macroscopically and microscopically examined. The bioelectrical impedance was evaluated at three different temperatures. Results: Renal injuries were wider and deeper at 90 degrees C (P < 0.001), and they were similar at 80 degrees C and 100 degrees C. The bioelectrical impedance was lower at 90 degrees C than at the temperatures of 80 degrees C and 100 degrees C (P < 0.001). Viable cells in the RF ablation tissue area were not found in the microscopic examination. Conclusion: The most effective cell destruction in terms of width and depth was achieved at 90 degrees C, which was also the optimal temperature for tissue impedance. RF ablation of renal cells eliminated all viable cells.

Ablation Rate and Morphology of Superficial and Deep Dentin Irradiated with Different Er:YAG Laser Energy Levels

Objective: In this study we evaluated the ablation rate of superficial and deep dentin irradiated with different Er:YAG laser energy levels, and observed the micromorphological aspects of the lased substrates with a scanning electron microscope (SEM). Background Data: Little is known about the effect of Er: YAG laser irradiation on different dentin depths. Materials and Methods: Sixty molar crowns were bisected, providing 120 specimens, which were randomly assigned into two groups ( superficial or deep dentin), and later into five subgroups (160, 200, 260, 300, or 360 mJ). Initial masses of the specimens were obtained. After laser irradiation, the final masses were obtained and mass losses were calculated followed by the preparation of specimens for SEM examination. Mass-loss values were subjected to two-way ANOVA and Fisher's least significant difference multiple-comparison tests (p < 0.05). Results: There was no difference between superficial and deep dentin. A significant and gradual increase in the mass-loss values was reached when energies were raised, regardless of the dentin depth. The energy level of 360 mJ showed the highest values and was statistically significantly different from the other energy levels. The SEM images showed that deep dentin was more selectively ablated, especially intertubular dentin, promoting tubule protrusion. At 360 mJ the micromorphological features were similar for both dentin depths. Conclusion: The ablation rate did not depend on the depth of the dentin, and an energy level lower than 360 mJ is recommended to ablate both superficial and deep dentin effectively without causing tissue damage.

Effect of Er:YAG Laser Parameters on Ablation Capacity and Morphology of Primary Enamel

Objective: The purpose of this study was to evaluate the ablation capacity of different energies and pulse repetition rates of Er:YAG laser energy on primary molar enamel, by assessing mass loss and by analyzing the surface morphology with scanning electron microscopy. Background Data: Previous studies have demonstrated the capacity of the Er:YAG laser to ablate enamel substrate. Methods: Forty-two sound primary molars were bisected in a mesiodistal direction. The enamel surfaces were flattened and their initial mass (in milligrams) was obtained. An area of 4 mm(2) was delimited. The specimens were randomly assigned to 12 groups according to the combination of energy (160, 200, 250, and 300 mJ) and pulse repetition rate (2, 3, and 4 Hz). Er: YAG laser irradiation was performed on each specimen for 20 sec. After irradiation, the final mass was obtained and specimens were prepared for examination with scanning electron microscopy. The data obtained by subtracting the final mass from the initial mass were statistically analyzed using ANOVA and the Tukey test (p < 0.05). Results: The pulse repetition rate of 4 Hz provided greater mass loss, different from that seen with 2 Hz, and similar to that seen with 3 Hz. The energy level of 300 mJ resulted in greater mass loss, similar to that seen with 200 and 250 mJ. Scanning electron photomicrographs showed that there was non-selective enamel removal, with fused and cracked areas in all specimens. Conclusion: The parameters of 200 mJ and 2 Hz produced a good ablation rate with fewer surface alterations in primary molar enamel.

Early Brief Treatment with Losartan plus Mycophenolate Mofetil Provides Lasting Renoprotection in a Renal Ablation Model

Background: Inflammatory events antecede established renal injury in rats with 5/6 renal ablation (Nx), as indicated by the beneficial effects of early, uninterrupted treatment with mycophenolate mofetil (MMF). Angiotensin II also exerts a major pathogenic role at this initial phase. We investigated whether losartan (L) or L+MMF treatment, started early, and L+MMF treatment, started late, would exert lasting renoprotection in Nx even after being discontinued. Methods: Adult male Munich-Wistar rats underwent Nx and were divided into three groups: Nx (untreated), Nx(L) (given L), and Nx(LMMF) (given L and MMF). Protocol 1: treatments began on day 1, and ceased on day 30, after Nx. Protocol 2: L+MMF treatment began on day 30 and ceased on day 60. Results: Protocol 1: on day 30, hypertension, albuminuria and renal injury were strongly attenuated in Groups Nx(L) and Nx(LMMF). On day 120, these abnormalities were still attenuated in group Nx(LMMF). Protocol 2: on day 120, all parameters were similar between this late Nx(LMMF) group and untreated Nx. Conclusion: In Nx, temporary suppression of early, transitory hemodynamic/inflammatory phenomena affords relatively durable renoprotection even after treatment discontinuation. This effect is not obtained with similar temporary treatment initiated later in the course of renal disease. Copyright (C) 2010 S. Karger AG, Basel

Left Atrial Function After Ablation for Paroxysmal Atrial Fibrillation

Radiofirequency ablation of the pulmonary veins has been used to treat patients with paroxysmal atrial fibrillation (AF), and atrial damage after ablation is an issue of concern. To evaluate left atrial function shortly and midterm after ablation, 33 consecutive patients with paroxysmal AF were studied at baseline, 24 hours, and >= 6 months after ablation. Patients in sinus rhythm with normal ventricular function were included in the study. Echocardiographic measurements of left atrial volumes (Simpson`s rule) and transmitral and tissue Doppler myocardial (A`) velocities at the septal and lateral mitral annulus were undertaken at each time. Left atrial emptying fraction (EF; maximal - minimal left atrial volume/maximal left atrial volume) was used to express left atrial function. After 8 +/- 2 months, 30 of 33 patients returned (23 men, age 53 +/- 13 years), and all except 2 were in sinus rhythm. Shortly after ablation, left atrial minimal volumes increased (from 30 +/- 15 to 35 +/- 15 ml; p = 0.02), with maximal volumes unchanged, resulting in decreased left atrial EF (from 47 +/- 8 to 40 +/- 7 ml; p <0.05). Tissue Doppler septal A` velocities also decreased (from 8.2 +/- 1.8 to 6.9 +/- 2.0 cm/s; p <0.05). However, after midterm follow-up, both left atrial EF and septal A` velocities had slightly increased compared with shortly after ablation, although left atrial volumes remained similar to baseline. Septal A` velocity changes paralleled left atrial EF both shortly (r = 0.46, p = 0.02) and at midterm after ablation (r = 0.47, p = 0.01). In conclusion, after radiofrequency ablation, patients with paroxysmal AF experienced an initial impairment in atrial function, with improvement at longer term follow-up. (C) 2009 Elsevier Inc. All rights reserved. (Am J Cardiol 2009;103: 395-398)

Gastric hypomotility following epicardial vagal denervation ablation to treat atrial fibrillation

Gastric Palsy Following AF Vagal Ablation. We report a case of a 55-year-old man with vagal paroxysmal atrial fibrillation (AF) who was submitted to selective epicardial and endocardial atrial vagal denervation with the objective of treating AF. Radiofrequency pulses were applied on epicardial and endocardial surface of the left atrium close to right pulmonary veins (PVs) and also on epicardial surface close to left inferior PV. Following the procedure, patient presented with symptoms of gastroparesis, which was documented on CT scan and gastric emptying scintigraphy. Symptoms were transient and the patient recovered completely.

Atrial Coronary Arteries in Areas Involved in Atrial Fibrillation Catheter Ablation

Background-The proximity to vascular structures is a limiting factor during radiofrequency ablation. However, little or no attention has been given to the atrial arterial circulation during the development of atrial fibrillation (AF) catheter ablation techniques. Methods and Results-We examined the atrial arterial circulation in areas involved in AF ablation in 24 heart specimens by colored resin injection and careful dissection. The sinus node artery (SNA) arose from the circumflex artery in 42% of case; proximal to the LA appendage in 29%, crossing the left atrium (LA) anterior wall; and after the LA appendage in the remaining 13%, crossing the mitral isthmus and passing close to the left pulmonary veins (PVs), the LA roof, and the right superior PV. In 58%, the SNA arose from the right coronary artery. Major arteries (>= 1 mm in external diameter) were found in the mitral isthmus in 54%, at the LA roof in 54%, and at the LA anterior wall in 29%. Around the left PV ostia, there were areas with major arteries in up to 37% (at the roof and inferior segments) and around the right PV ostia in up to 29% (at the roof segment). Conclusions-Major atrial coronary arteries, including the SNA, were commonly found in the areas involved in AF ablation and could cause difficulties in obtaining transmural lesions and electric isolation or even lead to ischemic sinus node or atrial dysfunction. (Circ Arrhythm Electrophysiol. 2010;3:600-605.)

Prion protein ablation increases cellular aggregation and embolization contributing to mechanisms of metastasis

Cellular Prion Protein (PrP(C)) is a cell surface protein highly expressed in the nervous system, and to a lesser extent in other tissues. PrP(C) binds to the extracellular matrix laminin and vitronectin, to mediate cell adhesion and differentiation. Herein, we investigate how PrP(C) expression modulates the aggressiveness of transformed cells. Mesenchymal embryonic cells (MEC) from wildtype (Prnp(+/+)) and PrP(C)-null (Prnp(0/0)) mice were immortalized and transformed by co-expression of ras and myc. These cells presented similar growth rates and tumor formation in vivo. When injected in the tail vein, PrnP(0/0)raS/myc cells exhibited increased lung colonization compared with Prnp(+/+)ras/myc cells. Additionally, Prnp(0/0)ras/myc cells form more aggregates with blood components than Prnp(+/+)ras/myc cells, facilitating the arrest of Prnp(0/0)ras/myc cells in the lung vasculature. Integrin alpha(v)beta(3) is more expressed and activated in MEC and in transformed Prnp(0/0) cells than in the respective Prnp(+/+) cells. The blocking of integrin alpha(v)beta(3) by RGD peptide reduces lung colonization in transformed Prnp(0/0) cells to similar levels of those presented by transformed Prnp(+/+) cells. Our data indicate that PrP(C) negatively modulates the expression and activation of integrin alpha(v)beta(3) resulting in a more aggressive phenotype. These results indicate that PrP(C) may have main implications in modulating metastasis formation. (C) 2009 UICC

Long-Term Astroglial Reaction and Neuronal Plasticity in the Subcortical Visual Pathways After a Complete Ablation of Telencephalon in Pigeons (Columba livia)

This paper analyzes the astroglial and neuronal responses in subtelencephalic structures, following a bilateral ablation of the telencephalon in the Columba livia pigeons. Control birds received a sham operation. Four months later the birds were sacrificed and their brains processed for glial fribillary acid protein (GFAP) and neurofilament immunohistochemistry, markers for astrocytes and neurons, respectively. Computer-assisted image analysis was employed for quantification of the immunoreactive labeling in the nucleus rotundus (N.Rt) and the optic tectum (OT) of the birds. An increased number of GFAP immunoreactive astrocytes were found in several subregions of the N.Rt (p .001), as well as in layers 1, 2cd, 3, and 6 of the OT (p .001) of the lesioned animals. Neurofilament immunoreactivity decreased massively in the entire N.Rt of the lesioned birds; however, remaining neurons with healthy aspect showing large cytoplasm and ramified branches were detected mainly in the periphery of the nucleus. In view of the recently described paracrine neurotrophic properties of the activated astrocytes, the data of the present study may suggest a long-lasting neuroglial interaction in regions of the lesioned bird brain far from injury. Such events may trigger neuronal plasticity in remaining brain structures that may lead spontaneous behavior recovery as the one promoted here even after a massive injury.

Development of an animal model for endometrial ablation using trichloroacetic acid

Objective: To develop an animal model of endometrial ablation, and to evaluate the histologic effects of trichloroacetic acid (TCA) in the uterine cavity. Design: Experimental prospective. Setting: Department of gynecology. Patient(s): Thirty female adult rats. Intervention(s): Animals were submitted to injection of TCA in one uterine horn and saline solution in the other. Group 1 was sacrificed the day after the procedure. Group 2 was sacrificed in phase of diestrus. Superficial epithelia of the endometrium, stromal thickness, endometrial glands, and myometrium thickness were compared among the uterine horns of the same rats of group 1. The same evaluation was performed in group 2. Endometrial regeneration was evaluated. Main Outcome Measure(s): Histologic effects. Result(s): In group 1, histologic parameters showed endometrial destruction on TCA injected uterine horn. In group 2, four rats died after the procedure, and six rats had no viable material. In the rest of the group, TCA-injected uterine horns showed endometrial destruction. Superficial epithelia of the endometrium and stromal thickness were similar between TCA uterine horn from groups. However, the number of endometrial glands was higher in group 1. Conclusion(s): The study developed an experimental model for endometrial ablation. TCA acid is a potent agent for endometrial ablation in rat model. No endometrial regeneration was observed after recovery of cycle. (Fertil Steril (R) 2011; 95: 2418-21. (C) 2011 by American Society for Reproductive Medicine.)

Catheter ablation of severe neurally meditated reflex (neurocardiogenic or vasovagal) syncope: cardioneuroablation long-term results

Aims Neurally meditated reflex or neurocardiogenic or vasovagal syncope (NMS) is usually mediated by a massive vagal reflex. This study reports the long-term outcome of NMS therapy based on endocardial radiofrequency (RF) catheter ablation of the cardiac vagal nervous system aiming permanent attenuation or elimination of the cardioinhibitory reflex (cardioneuroablation). Methods and results A total of 43 patients (18F/25M, 32.9+/-15 years) without apparent cardiopathy (left ventricular ejection fraction=68.6+/-5%) were included. All had recurrent NMS (4.7+/-2 syncope/patient) with important cardioinhibition (pauses=13.5+/-13 s) at head-up tilt test (HUT), normal electrocardiogram (ECG), and normal atropine test (AT). The patients underwent atrial endocardial RF ablation using spectral mapping to track the neurocardiac interface (AF Nest Mapping). The follow-up (FU) consisted of clinical evaluation, ECG (1 month/every 6 months/or symptoms), Holter (every 6 months/or symptoms), HUT (>= 4 months/or symptoms), and AT (end of ablation and >= 6 months). A total of 44 ablations (48+/-9 points/patient) were performed. Merely three cases of spontaneous syncope occurred in 45.1+/-22 months (two vasodepressor, one undefined). Only four partial cardioinhibitory responses occurred in post-ablation HUT without pauses or asystole (sinus bradycardia). Long-term AT (21.7+/-11 months post) was negative in 33 (76.7%, P<0.01), partially positive in 7(16.3%), and normal in three patients only (6.9%) reflecting long-term vagal denervation (AT-Delta% HR pre 79.4% x 23.2% post). The post-ablation stress test and Holter showed no abnormalities. No major complications occurred. Conclusion Endocardial RF catheter ablation of severe neurally meditated reflex syncope prevented pacemaker implantation and showed excellent long-term results in well selected patients. Despite no action in vasodepression it seems to cause enough long-term vagal reflex attenuation, eliminating the cardioinhibition, and keeping most patients asymptomatic. Indication was based on clinical symptoms, reproduction of severe cardioinhibitory syncope, and normal atropine response.

Percutaneous Laser Ablation of Sacrococcygeal Teratoma in a Hydropic Fetus with Severe Heart Failure - Too Late for a Surgical Procedure?

Sacrococcygeal teratoma (SCT) is the commonest solid fetal tumor. Perinatal prognosis is usually favorable, but sometimes it can be complicated by fetal hydrops being responsible for high risk of mortality. Fetal therapy in such cases has so far not been established. We report a case with a giant solid SCT associated with fetal hydrops and severe heart failure. 2D- and 3D-Doppler ultrasonography revealed great vessels originated from the medial sacral artery. Percutaneous laser ablation of these vessels was performed at 24 weeks of gestation. During the procedure, severe anemia was also diagnosed (hemoglobin 4.3 g/dl). Two days later, the fetus died and pathological examination revealed local tumor necrosis and blood hemorrhage inside the mass. We suggest that in such cases, fetal surgery may not be enough, being too late, and perhaps fetal clinical therapy for anemia and heart failure could be the best option at a gestational age of less than 28 weeks. Copyright (C) 2009 S. Karger AG, Basel

Percutaneous Transatrial Access to the Pericardial Space for Epicardial Mapping and Ablation

Background-Puncture of the atrial appendage may provide access to the pericardial space. The aim of this study was to evaluate the feasibility of epicardial mapping and ablation through an endocardial transatrial access in a swine model. Methods and Results-An 8-F Mullins sheath was used to perforate the right (n=16) or left (n=1) atrial appendage in 17 pigs (median weight, 27.5 kg; first and third quartiles [Q1, Q3], 25.2, 30.0 kg). A 7-F ablation catheter was introduced into the pericardial space to perform epicardial mapping and deliver radiofrequency pulses on the atria. The pericardial space was entered in all 17 animals. In 15 (88%) animals, there was no hemodynamic instability (mean blood pressure monitoring, initial median, 80 mm Hg; Q1, Q3, 70, 86 mm Hg; final median, 88 mm Hg; Q1, Q3, 80, 96 mm Hg; P=0.426). In these 15, a mild hemorrhagic pericardial effusion was identified and aspirated (median, 20 mL; Q1, Q3, 15, 30 mL) during the procedure, and postmortem gross analysis revealed that the atrial perforation was closed in these animals. In 2 (12%) of the 17 animals, there was major pericardial bleeding with hemodynamic collapse. On gross examination, it was found that pericardial space was accessed through right ventricular perforation in 1 animal and the tricuspid annulus in the other. After the initial study, we used an occlusion device in 3 other animals to attempt to seal the puncture (2 at the right atrial appendage and 1 at the right ventricle). These 3 animals had no significant pericardial bleeding. Conclusions-Transatrial endovascular right atrial appendage puncture may provide a potential alternative route for pericardial access. Further studies are needed to evaluate its safety with longer and more-complex procedures before being applied in clinical settings. (Circ Arrhythm Electrophysiol. 2011;4:331-336.)

The influence of erbium:yttrium-aluminum-garnet laser ablation with variable pulse width on morphology and microleakage of composite restorations

The objective of this study was to evaluate the influence of various pulse widths with different energy parameters of erbium:yttrium-aluminum-garnet (Er:YAG) laser (2.94 mu m) on the morphology and microleakage of cavities restored with composite resin. Identically sized class V cavities were prepared on the buccal surfaces of 54 bovine teeth by high-speed drill (n = 6, control, group 1) and prepared by Er:YAG laser (Fidelis 320A, Fotona, Slovenia) with irradiation parameters of 350 mJ/ 4 Hz or 400 mJ/2 Hz and pulse width: group 2, very short pulse (VSP); group 3, short pulse (SP); group 4, long pulse (LP); group 5, very long pulse (VLP). All cavities were filled with composite resin (Z-250-3 M), stored at 37A degrees C in distilled water, polished after 24 h, and thermally stressed (700 cycles/5-55A degrees C). The teeth were impermeabilized, immersed in 50% silver nitrate solution for 8 h, sectioned longitudinally, and exposed to Photoflood light for 10 min to reveal the stain. The leakage was evaluated under stereomicroscope by three different examiners, in a double-blind fashion, and scored (0-3). The results were analyzed by Kruskal-Wallis test (P > 0.05) and showed that there was no significant differences between the groups tested. Under scanning electron microscopy (SEM) the morphology of the cavities prepared by laser showed irregular enamel margins and dentin internal walls, and a more conservative pattern than that of conventional cavities. The different power settings and pulse widths of Er:YAG laser in cavity preparation had no influence on microleakage of composite resin restorations.