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Sample records for af ablation procedure

  1. Cardiac ablation procedures

    MedlinePlus

    ... Accessory pathway, such as Wolff-Parkinson-White Syndrome Atrial fibrillation and atrial flutter Ventricular tachycardia ... consensus statement on catheter and surgical ablation of atrial fibrillation: ... for personnel, policy, procedures and follow-up. ...

  2. Korean Atrial Fibrillation (AF) Network: Genetic Variants for AF Do Not Predict Ablation Success

    PubMed Central

    Choi, Eue-Keun; Park, Jae Hyung; Lee, Ji-Young; Nam, Chung Mo; Hwang, Min Ki; Uhm, Jae-Sun; Joung, Boyoung; Ko, Young-Guk; Lee, Moon-Hyoung; Lubitz, Steven A; Ellinor, Patrick T; Pak, Hui-Nam

    2015-01-01

    Background Genomewide association studies have identified several loci associated with atrial fibrillation (AF) and have been reportedly associated with response to catheter ablation for AF in patients of European ancestry; however, associations between top susceptibility loci and AF recurrence after ablation have not been examined in Asian populations. We examined whether the top single nucleotide polymorphisms (SNPs) at chromosomes 4q25 (PITX2), 16q22 (ZFHX3), and 1q21 (KCNN3) were associated with AF in a Korean population and whether these SNPs were associated with clinical outcomes after catheter ablation for AF. Methods and Results We determined the association between 4 SNPs and AF in 1068 AF patients who underwent catheter ablation (74.6% male, aged 57.5±10.9 years, 67.9% paroxysmal AF) and 1068 age- and sex-matched controls. The SNPs at the PITX2 and ZFHX3 loci, but not the KCNN3 locus, were significantly associated with AF (PITX2/rs6843082_G: odds ratio 3.41, 95% CI 2.55 to 4.55, P=1.32×10−16; PITX2/rs2200733_T: odds ratio 2.05, 95% CI 1.66 to 2.53, P=2.20×10−11; ZFHX3/rs2106261_A: odds ratio 2.33, 95% CI 1.87 to 2.91, P=3.75×10−14; KCNN3/rs13376333_T: odds ratio 1.74, 95% CI 0.93 to 3.25, P=0.085). Among those patients who underwent catheter ablation for AF, none of the top AF-associated SNPs were associated with long-term clinical recurrence of AF after catheter ablation. Conclusions SNPs at the PITX2 and ZFHX3 loci were strongly associated with AF in Korean patients. In contrast to prior reports, none of the 4 top AF-susceptibility SNPs predicted clinical recurrence after catheter ablation. PMID:26272656

  3. Totally thorascopic surgical ablation of persistent AF and long-standing persistent atrial fibrillation using the "Dallas" lesion set.

    PubMed

    Edgerton, James R; Jackman, Warren M; Mahoney, Cecile; Mack, Michael J

    2009-12-01

    Minimally invasive surgery consisting of bipolar radiofrequency pulmonary vein (PV) isolation and limited ganglionated plexus ablation is effective in eliminating atrial fibrillation (AF) in patients with paroxysmal AF but is less effective in those with persistent AF or long-standing persistent AF. The purpose of this study was examine the results of minimally invasive surgery incorporating an additional set of radiofrequency ablation lines replicating a left-sided Cox maze III procedure. Thirty patients with persistent AF (n = 10) or long-standing persistent AF (n = 20) underwent minimally invasive surgery with an extended lesion set and PV isolation for a minimum follow-up of 6 months. Linear lesions were created at the roof line, at the anterior line, and between the roof line and the left atrial appendage. All patients underwent limited ganglionated plexus ablation and left atrial appendage excision as well as PV isolation verification. Block across the roof and anterior lines was confirmed in 29 (96.6%) of the 30 patients. Follow-up included 2-week event monitoring with auto-trigger in 21 patients, pacemaker interrogation in 8, and ECG in 1 who was in AF and refused longer-term monitoring. No operative mortality or major morbidity occurred. At 6 months, 24 (80%) of the 30 patients were free of AF: 15 (75%) with long-standing persistent AF and 9 (90%) with persistent AF. Among the six failures, burden of AF was low: one had 1 episode >15 seconds, two had 4 episodes, one had 6 episodes, one had >50 episodes, and one had AF on ECG and refused further monitoring. Early results of minimally invasive surgery with a new extended linear lesion set suggest increased efficacy over PV isolation and limited ganglionated plexus ablation in patients with persistent AF or long-standing persistent AF. PMID:19959146

  4. Atrial Electrogram Discordance During Baseline versus Re-Induced Atrial Fibrillation: Potential Ramifications For Ablation Procedures

    PubMed Central

    Biviano, Angelo B.; Ciaccio, Edward J.; Knotts, Robert; Lawrence, John; Iyer, Vivek; Whang, William; Garan, Hasan

    2015-01-01

    Background There are scant data comparing the electrogram (EGM) signal characteristics of AF in the baseline versus electrically induced states during ablation procedures. Objective The purpose of this study was to use novel intracardiac signal analysis techniques to gain insights into the effects of catheter ablation and AF re-induction on AF EGMs in patients with persistent AF. Methods We collected left atrial EGMs in patients undergoing first ablation for persistent AF at three time intervals: i) AF at baseline; ii) AF after pulmonary vein isolation (PVI) and; iii) AF after post-PVI cardioversion and subsequent re-induction. We analyzed the following two EGM spectral characteristics: 1a) dominant frequency (DF) and 1b) spectral complexity; and the following two EGM morphologic characteristics: 2a) morphology variation, and 2b) pattern repetitiveness. Results There were no differences in AF dominant frequency, dominant amplitude, spectral complexity, or metrics of EGM morphology or repetitiveness at baseline versus after PVI. However, dominant frequency, dominant amplitude, and spectral complexity differed significantly after DC cardioversion and re-induction of AF. Conclusions The frequency, spectral complexity and local EGM morphologies of AF do not significantly change over the course of a pulmonary vein isolation procedure in patients with persistent AF. However, re-induction of AF after DC cardioversion results in different DF and spectral complexity, consistent with a change in the characteristics of the perpetuating source(s) of the newly induced AF. These data suggest that AF properties can vary significantly between baseline versus re-induced AF, with potential clinical ramifications for outcomes of catheter ablation procedures. PMID:25818256

  5. Catheter ablation for atrial fibrillation: results from the first European Snapshot Survey on Procedural Routines for Atrial Fibrillation Ablation (ESS-PRAFA) Part II.

    PubMed

    Chen, Jian; Dagres, Nikolaos; Hocini, Melece; Fauchier, Laurent; Bongiorni, Maria Grazia; Defaye, Pascal; Hernandez-Madrid, Antonio; Estner, Heidi; Sciaraffia, Elena; Blomström-Lundqvist, Carina

    2015-11-01

    The European Snapshot Survey on Procedural Routines in Atrial Fibrillation Ablation (ESS-PRAFA) is a prospective, multicentre snapshot survey collecting patient-based data on current clinical practices during atrial fibrillation (AF) ablation. The participating centres were asked to prospectively enrol consecutive patients during a 6-week period (from September to October 2014). A web-based case report form was employed to collect information of patients and data of procedures. A total of 455 eligible consecutive patients from 13 countries were enrolled (mean age 59 ± 10.8 years, 28.8% women). Distinct strategies and endpoints were collected for AF ablation procedures. Pulmonary vein isolation (PVI) was performed in 96.7% and served as the endpoint in 91.3% of procedures. A total of 52 (11.5%) patients underwent ablation as first-line therapy. The cryoballoon technique was employed in 31.4% of procedures. Procedure, ablation, and fluoroscopy times differed among various types of AF ablation. Divergences in patient selection and complications were observed among low-, medium-, and high-volume centres. Adverse events were observed in 4.6% of AF ablation procedures. In conclusion, PVI was still the main strategy for AF ablation. Procedure-related complications seemed not to have declined. The centre volume played an important role in patient selection, strategy choice, and had impact on the rate of periprocedural complication. PMID:26462700

  6. Atrioesophageal fistula following ablation procedures for atrial fibrillation: systematic review of case reports

    PubMed Central

    Chavez, Patricia; Messerli, Franz H; Casso Dominguez, Abel; Aziz, Emad F; Sichrovsky, Tina; Garcia, Daniel; Barrett, Connor D; Danik, Stephan

    2015-01-01

    Background Atrioesophageal fistula (AEF) is a rare but serious adverse event of atrial fibrillation (AF) ablation. Objective To identify the clinical characteristics of AEF following ablation procedures for AF and determine the associated mortality. Methods A systematic review of observational cases of AEF following ablation procedures for AF was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement protocol. Results 53 cases were identified. Mean age was 54±13 years; 73% (39/53) of cases occurred in males. Mean interval between procedure and presentation was 20±12 days, ranging from 2 to 60 days. AEF was observed in 12 patients who underwent surgical radiofrequency ablation (RFA) and in 41 patients with percutaneous RFA. Fever was the most common presenting symptom (n=44) followed by neurological deficits (n=27) and haematemesis (n=19). CT of the chest (n=27) was the preferred diagnostic test. Patients who did not receive a primary esophageal repair were more likely to have a deadly outcome (34% vs 83%; p<0.05). No difference in mortality rate was found between patients who underwent surgical RFA when compared with percutaneous RFA (58% vs 56%; p=0.579). No association was found between onset of symptoms and mortality (19±10 vs 23±14 days; p=0.355). Conclusions AEF following ablation procedures for AF is a serious complication with high mortality rates. Presenting symptoms most often include a triad of fever, neurological deficit and/or haematemesis within 60 days of procedure. The preferred diagnostic test is CT of the chest. The treatments of choice is surgical repair. PMID:26380098

  7. Impact of Free Thyroxine on the Outcomes of Left Atrial Ablation Procedures.

    PubMed

    Sousa, Pedro A; Providência, Rui; Albenque, Jean-Paul; Khoueiry, Ziad; Combes, Nicolas; Combes, Stéphane; Boveda, Serge

    2015-12-15

    The prevalence of atrial fibrillation (AF) is increased in hyperthyroidism. The degree to which thyroid hormones affect the outcomes of left atrial (LA) ablation is still unclear. From September 2010 to September 2013, 1,095 patients who underwent LA ablation (59.7% paroxysmal AF, 32.3% persistent AF, and 8.0% LA tachycardia) had their serum thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels measured in the 48 hours before the procedure. Patients were followed until they presented the first AF relapse after a blanking period of 3 months. TSH and FT4 were assessed as predictors of arrhythmia relapse and were adjusted for possible confounders. During a mean follow-up of 12.5 ± 7.9 months, 28.9% of patients presented an atrial arrhythmia relapse. TSH was not a predictor of relapse. In contrast, after adjustment, FT4 (median = 11.8 ng/L and interquartile range 10.6 to 14.6 ng/L) remained a predictor of relapse with 15% increase per quartile (hazard ratio 1.15, 95% confidence interval 1.03 to 1.29, p = 0.014). In conclusion, FT4 levels influence the success rate of LA ablation procedures, even when in the normal range. PMID:26514301

  8. Multimodality Imaging for Guiding EP Ablation Procedures.

    PubMed

    Njeim, Mario; Desjardins, Benoit; Bogun, Frank

    2016-07-01

    Recent advances in 3-dimensional electroanatomical mapping have been met by continuous improvements in the field of cardiac imaging and image integration during ablation procedures. Echocardiography, computed tomography, cardiac magnetic resonance, and nuclear imaging provide information about cardiac anatomy and ultrastructure of the heart that may be crucial for a successful ablation procedure. Techniques and value of pre-procedural, intraprocedural, and post-procedural imaging and image integration are discussed in this review article. Pre-procedural imaging provides key anatomic information that can be complemented by intraprocedural imaging to minimize procedural complications. Furthermore, the presence and extent of structural heart disease can be assessed pre-procedurally and can be displayed intraprocedurally to limit and focus the mapping and ablation procedure to the area of interest. Pre-procedural imaging combined with imaging obtained during the ablation procedure further enhances procedural safety, reduces exposure to ionizing radiation from fluoroscopy, reduces procedure time, and may improve outcomes. PMID:27388666

  9. Comparison of procedure costs of various percutaneous tumor ablation modalities.

    PubMed

    Astani, Seyed A; Brown, Manuel L; Steusloff, Kay

    2014-01-01

    Microwave ablation, radiofrequency ablation, cryoablation, and irreversible electroporation are percutaneous ablation modalities commonly employed to treat tumors. The procedure cost of treating the same lesion with each of the four modalities is compared. A cost model was created for each ablation modality estimating the cost of treating a tumor based on the number of probes required, which is estimated by the tumor size.Total cost of treating a 3 cm kidney lesion with each modality was individually calculated. There was a strongly positive and statistically significant relationship between estimated cost based on the cost modules and actual cost for all procedures. The number of required probes is the dominant factor in determining the cost of an ablation procedure. The most expensive ablation modalities in decreasing order are irreversible electroporation, cryoablation, and microwave and radiofrequency ablations. PMID:25174139

  10. Remotely controlled steerable sheath improves result and procedural parameters of atrial fibrillation ablation with magnetic navigation

    PubMed Central

    Errahmouni, Abdelkarim; Latcu, Decebal Gabriel; Bun, Sok-Sithikun; Rijo, Nicolas; Dugourd, Céline; Saoudi, Nadir

    2015-01-01

    Aims The magnetic navigation (MN) system may be coupled with a new advancement system that fully controls both the catheter and a robotic deflectable sheath (RSh) or with a fixed-curve sheath and a catheter-only advancement system (CAS). We aimed to compare these approaches for atrial fibrillation (AF) ablation. Methods and results Atrial fibrillation ablation patients (45, 23 paroxysmal and 22 persistent) performed with MN–RSh (RSh group) were compared with a control group (37, 18 paroxysmal and19 persistent) performed with MN–CAS (CAS group). Setup duration was measured from the procedure's start to operator transfer to control room. Ablation step duration was defined as the time from the beginning of the first radiofrequency (RF) pulse to the end of the last one and was separately acquired for the left and the right pulmonary vein (PV) pairs. Clinical characteristics, left atrial size, and AF-type distribution were similar between the groups. Setup duration as well as mapping times was also similar. Ablation step duration for the left PVs was similar, but was shorter for the right PVs in RSh group (46 ± 9 vs. 63 ± 12 min, P < 0.0001). Radiofrequency delivery time (34 ± 9 vs. 40 ± 11 min, P = 0.007) and procedure duration (227 ± 36 vs. 254 ± 62 min, P = 0.01) were shorter in RSh group. No complication occurred in RSh group. During follow-up, there were five recurrences (11%) in RSh group and 11 (29%) in CAS group (P = 0.027). Conclusion The use of the RSh for AF ablation with MN is safe and improves outcome. Right PV isolation is faster, RF delivery time and procedure time are reduced. PMID:25662989

  11. Pericardioesophageal Fistula Following Left Atrial Ablation Procedure

    PubMed Central

    Bailey, Christopher W.; Tallaksen, Robert J.

    2014-01-01

    We present a case of pericardioesophageal fistula formation in a 40 year old male who 23 days after undergoing a repeat ablation procedure for atrial fibrillation developed chest pressure, chills and diaphoresis. After initial labs and tests that demonstrated no evidence for acute myocardial ischemia, the patient underwent CT angiography of the chest. The study revealed pneumopericardium and a pericardial effusion. Suspicion was raised of perforation of the posterior left atrial myocardial wall with injury to adjacent esophagus. Water soluble contrast with transition to barium sulfate esophagram subsequently performed identified a perforation further affirming the postulate of a fistulous communication between the esophagus and pericardium. Transthoracic echocardiogram confirmed pericardial effusion but did not demonstrate myocardial defect. Endoscopic management was preferred and an esophageal stent was placed. Follow up esophagram showed an intact esophageal stent without evidence of extravasation. PMID:25426222

  12. Pericardioesophageal fistula following left atrial ablation procedure.

    PubMed

    Bailey, Christopher W; Tallaksen, Robert J

    2014-10-01

    We present a case of pericardioesophageal fistula formation in a 40 year old male who 23 days after undergoing a repeat ablation procedure for atrial fibrillation developed chest pressure, chills and diaphoresis. After initial labs and tests that demonstrated no evidence for acute myocardial ischemia, the patient underwent CT angiography of the chest. The study revealed pneumopericardium and a pericardial effusion. Suspicion was raised of perforation of the posterior left atrial myocardial wall with injury to adjacent esophagus. Water soluble contrast with transition to barium sulfate esophagram subsequently performed identified a perforation further affirming the postulate of a fistulous communication between the esophagus and pericardium. Transthoracic echocardiogram confirmed pericardial effusion but did not demonstrate myocardial defect. Endoscopic management was preferred and an esophageal stent was placed. Follow up esophagram showed an intact esophageal stent without evidence of extravasation. PMID:25426222

  13. Robust tracking of a virtual electrode on a coronary sinus catheter for atrial fibrillation ablation procedures

    NASA Astrophysics Data System (ADS)

    Wu, Wen; Chen, Terrence; Strobel, Norbert; Comaniciu, Dorin

    2012-02-01

    Catheter tracking in X-ray fluoroscopic images has become more important in interventional applications for atrial fibrillation (AF) ablation procedures. It provides real-time guidance for the physicians and can be used as reference for motion compensation applications. In this paper, we propose a novel approach to track a virtual electrode (VE), which is a non-existing electrode on the coronary sinus (CS) catheter at a more proximal location than any real electrodes. Successful tracking of the VE can provide more accurate motion information than tracking of real electrodes. To achieve VE tracking, we first model the CS catheter as a set of electrodes which are detected by our previously published learning-based approach.1 The tracked electrodes are then used to generate the hypotheses for tracking the VE. Model-based hypotheses are fused and evaluated by a Bayesian framework. Evaluation has been conducted on a database of clinical AF ablation data including challenging scenarios such as low signal-to-noise ratio (SNR), occlusion and nonrigid deformation. Our approach obtains 0.54mm median error and 90% of evaluated data have errors less than 1.67mm. The speed of our tracking algorithm reaches 6 frames-per-second on most data. Our study on motion compensation shows that using the VE as reference provides a good point to detect non-physiological catheter motion during the AF ablation procedures.2

  14. Arrhythmia Termination Versus Elimination of Dormant Pulmonary Vein Conduction as a Procedural End Point of Catheter Ablation for Paroxysmal Atrial Fibrillation

    PubMed Central

    Theis, Cathrin; Konrad, Torsten; Mollnau, Hanke; Sonnenschein, Sebastian; Kämpfner, Denise; Potstawa, Maik; Ocete, Blanca Quesada; Bock, Karsten; Himmrich, Ewald; Münzel, Thomas

    2015-01-01

    Background— Pulmonary vein isolation (PVI) is still associated with a substantial number of arrhythmia recurrences in paroxysmal atrial fibrillation (AF). This prospective, randomized study aimed to compare 2 different procedural strategies. Methods and Results— A total of 152 patients undergoing de novo ablation for paroxysmal AF were randomized to 2 different treatment arms. The procedure in group A consisted of PVI exclusively. In this group, all isolated PVs were challenged with adenosine to reveal and ablate dormant conduction. In group B, PVI was performed with the patient either in spontaneous or in induced AF. If AF did not terminate with PVI, ablation was continued by targeting extra-PV AF sources with the desired procedural end point of termination to sinus rhythm. Primary study end point was freedom from arrhythmia during 1-year follow-up. In group A, adenosine provoked dormant conduction in 31 (41%) patients with a mean of 1.6±0.8 transiently recovered PVs per patient. Termination of AF during PVI was observed in 31 (65%) patients, whereas AF persisted afterward in 17 (35%) patients. AF termination occurred in 13 (76%) patients by AF source ablation. After 1-year follow-up, significantly more group B patients were free of arrhythmia recurrences (87 versus 68%; P=0.006). During redo ablation, the rate of PV reconduction did not differ between both groups (group A: 55% versus group B: 61%; P=0.25). Conclusions— Elimination of extra-PV AF sources after PVI is superior to sole PV isolation with the adjunct of abolishing potential dormant conduction. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT02238392. PMID:26297786

  15. Advances in Atrial Fibrillation Ablation

    PubMed Central

    Darge, Alicia; Reynolds, Matthew R.; Germano, Joseph J.

    2009-01-01

    Atrial Fibrillation (AF) is an increasingly common and costly medical problem.1–3 Given the disappointing efficacy and side effects associated with pharmacological therapy for AF, new treatment options are needed. Over the last decade, advances in our understanding of the mechanisms of AF, coupled with iterative improvements in catheter ablation techniques, have spurred the evolution of catheter ablation for AF from an experimental procedure to an increasingly important treatment option.4 This paper will review recent advances in the approaches and outcomes of AF ablation. PMID:19411729

  16. New Ablation Technologies and Techniques

    PubMed Central

    Berte, Benjamin; Yamashita, Seigo; Derval, Nicolas; Denis, Arnaud; Shah, Ashok; Amraoui, Sana; Hocini, Meleze; Haissaguerre, Michel; Jais, Pierre; Sacher, Frederic

    2014-01-01

    Catheter ablation is an established treatment strategy for a range of different cardiac arrhythmias. Over the past decade two major areas of expansion have been ablation of atrial fibrillation (AF) and ventricular tachycardia (VT) in the context of structurally abnormal hearts. In parallel with the expanding role of catheter ablation for AF and VT, multiple novel technologies have been developed which aim to increase safety and procedural success. Areas of development include novel catheter designs, novel navigation technologies and higher resolution imaging techniques. The aim of the present review is to provide an overview of novel developments in AF ablation and VT ablation in patients with of structural cardiac diseases. PMID:26835075

  17. New Ablation Technologies and Techniques.

    PubMed

    Mahida, Saagar; Berte, Benjamin; Yamashita, Seigo; Derval, Nicolas; Denis, Arnaud; Shah, Ashok; Amraoui, Sana; Hocini, Meleze; Haissaguerre, Michel; Jais, Pierre; Sacher, Frederic

    2014-08-01

    Catheter ablation is an established treatment strategy for a range of different cardiac arrhythmias. Over the past decade two major areas of expansion have been ablation of atrial fibrillation (AF) and ventricular tachycardia (VT) in the context of structurally abnormal hearts. In parallel with the expanding role of catheter ablation for AF and VT, multiple novel technologies have been developed which aim to increase safety and procedural success. Areas of development include novel catheter designs, novel navigation technologies and higher resolution imaging techniques. The aim of the present review is to provide an overview of novel developments in AF ablation and VT ablation in patients with of structural cardiac diseases. PMID:26835075

  18. Contact force mapping during catheter ablation for atrial fibrillation: procedural data and one-year follow-up

    PubMed Central

    Huemer, Martin; Parwani, Abdul Shokor; Blaschke, Florian; Haverkamp, Wilhelm; Boldt, Leif-Hendrik

    2014-01-01

    Introduction Pulmonary vein isolation (PVI) is the state-of-the-art treatment of atrial fibrillation (AF). Pulmonary vein reconnection is one of the main mechanisms of AF recurrence after ablation. Catheter-tissue contact is essential for effective ablation lesions. The aim of this study was to evaluate the impact of catheter contact monitoring during PVI on AF recurrence rate. Material and methods One hundred and forty-three patients who underwent PVI were analysed. In 31 patients, PVI was performed by monitoring the catheter-tissue contact with a contact force (CF) sensing catheter. One hundred and twelve patients in whom conventional PVI was performed without CF information served as the control group. Procedural data and recurrence rate within 12-month follow-up were compared. Results A significant reduction in procedure duration was seen in the CF mapping group (128.4 ±29 min vs. 157.7 ±30.8 min, p = 0.001). Complete pulmonary vein isolation was achieved in 100% of the patients. Rate of AF recurrence within 12 months after ablation was significantly lower in the contact force group (16.1%) when compared to the standard ablation group (36.6%) (p = 0.031). Conclusions Pulmonary vein isolation with the use of contact force information results in a shorter procedure duration and a lower rate of AF recurrence after 12 months compared to conventional PVI without this information. Catheter-tissue contact monitoring may have a beneficial effect on mid-term and long-term results of PVI procedures. PMID:24904659

  19. Oral anticoagulant therapy for stroke prevention in patients with atrial fibrillation undergoing ablation: results from the First European Snapshot Survey on Procedural Routines for Atrial Fibrillation Ablation (ESS-PRAFA).

    PubMed

    Potpara, Tatjana S; Larsen, Torben B; Deharo, Jean Claude; Rossvoll, Ole; Dagres, Nikolaos; Todd, Derick; Pison, Laurent; Proclemer, Alessandro; Purefellner, Helmut; Blomström-Lundqvist, Carina

    2015-06-01

    The European Snapshot Survey on Procedural Routines in Atrial Fibrillation Ablation (ESS-PRAFA) is a prospective, multicentre snapshot survey of patients undergoing atrial fibrillation (AF) ablation, conducted to collect patient-based data on current clinical practices in AF ablation in context of the latest AF Guidelines and contemporary oral anticoagulant therapies. The EP Research Network Centres were asked to prospectively enrol consecutive patients during a 6-week period (September/October 2014). Data were collected via the web-based case report form. We present the results pertinent to the use of antithrombotic therapies. Thirteen countries prospectively enrolled 455 eligible consecutive patients [mean age 59 ± 10.8 years, 131 (28.8%) females]. The mean CHA2DS2-VASc score was 1.12 ± 1.06 [137 patients (30.1%) had a score of ≥2]. Before ablation, 443 patients (97.4%) were on anticoagulant therapy [143 (31.4%) on non-vitamin K antagonist oral anticoagulants (NOACs) and 264 (58.0%) on vitamin K antagonists (VKAs)]. Of the latter, 79.7% underwent ablation without VKA interruption, whilst a variety of strategies were used in patients taking NOAC. After ablation, most patients (89.3%) continued the same anticoagulant as before, and 2 (0.4%) were not prescribed any anticoagulation. At discharge, 280 patients (62.2%) were advised oral anticoagulation for a limited period of mean 3.8 ± 2.2 months. On multivariate analysis, CHA2DS2-VASc, AF duration, prior VKA use, and estimated AF ablation success were significantly associated with the decision on short-term anticoagulation. Our results show the increasing use of NOAC in patients undergoing AF ablation and emphasize the need for more information to guide the periprocedural use of both NOACs and VKAs in real-world setting. PMID:26023177

  20. Catheter ablation of atrial fibrillation: Radiofrequency catheter ablation for redo procedures after cryoablation

    PubMed Central

    Kettering, Klaus; Gramley, Felix

    2013-01-01

    AIM: To evaluate the effectiveness of two different strategies using radiofrequency catheter ablation for redo procedures after cryoablation of atrial fibrillation. METHODS: Thirty patients (paroxysmal atrial fibrillation: 22 patients, persistent atrial fibrillation: 8 patients) had to undergo a redo procedure after initially successful circumferential pulmonary vein (PV) isolation with the cryoballoon technique (Arctic Front Balloon, CryoCath Technologies/Medtronic). The redo ablation procedures were performed using a segmental approach or a circumferential ablation strategy (CARTO; Biosense Webster) depending on the intra-procedural findings. After discharge, patients were scheduled for repeated visits at the arrhythmia clinic. A 7-day Holter monitoring was performed at 3, 12 and 24 mo after the ablation procedure. RESULTS: During the redo procedure, a mean number of 2.9 re-conducting pulmonary veins (SD ± 1.0 PVs) were detected (using a circular mapping catheter). In 20 patients, a segmental approach was sufficient to eliminate the residual pulmonary vein conduction because there were only a few recovered pulmonary vein fibres. In the remaining 10 patients, a circumferential ablation strategy was used because of a complete recovery of the PV-LA conduction. All recovered pulmonary veins could be isolated successfully again. At 2-year follow-up, 73.3% of all patients were free from an arrhythmia recurrence (22/30). There were no major complications. CONCLUSION: In patients with an initial circumferential pulmonary vein isolation using the cryoballoon technique, a repeat ablation procedure can be performed safely and effectively using radiofrequency catheter ablation. PMID:24009817

  1. [Catheter ablation of persistent atrial fibrillation : pulmonary vein isolation, ablation of fractionated electrograms, stepwise approach or rotor ablation?].

    PubMed

    Scherr, D

    2015-02-01

    Catheter ablation is an established treatment option for patients with atrial fibrillation (AF). In paroxysmal AF ablation, pulmonary vein isolation alone is a well-defined procedural endpoint, leading to success rates of up to 80% with multiple procedures over 5 years of follow-up. The success rate in persistent AF ablation is significantly more limited. This is partly due to the rudimentary understanding of the substrate maintaining persistent AF. Three main pathophysiological concepts for this arrhythmia exist: the multiple wavelet hypothesis, the concept of focal triggers, mainly located in the pulmonary veins and the rotor hypothesis. However, the targets and endpoints of persistent AF ablation are ill-defined and there is no consensus on the optimal ablation strategy in these patients. Based on these concepts, several ablation approaches for persistent AF have emerged: pulmonary vein isolation, the stepwise approach (i.e. pulmonary vein isolation, ablation of fractionated electrograms and linear ablation), magnetic resonance imaging (MRI) and rotor-based approaches. Currently, persistent AF ablation is a second-line therapy option to restore and maintain sinus rhythm. Several factors, such as the presence of structural heart disease, duration of persistent AF and dilatation and possibly also the degree of fibrosis of the left atrium should influence the decision to perform persistent AF ablation. PMID:25687615

  2. [Treatment of atrial fibrillation using maze procedure by radiofrequency ablation].

    PubMed

    Cai, Z; Sun, G; Du, R

    1997-12-01

    From May 1994 to May 1996, 20 cases of atrial fibrillation were treated by means of Maze procedure by radiofrequenncy ablation, at the same time 19 cases of these patients were complicated with rheumatic heart valve disease and valve replacement operations were perfomned, in the other case atrial septal defect was repaired. Yoshio Kosakai's operation route was adopted in radiofrequency ablation procedure. After operation 16 patients of atrial fibrillation resumed sinus rhythm (80%), in 4 casess of atrial fibrillation sinus rhythm was unsuccessfully restored, two patients remained atrial fibrillation, one patient was of atrial flutter, the other was of nodal rhythm. Short time was needed in radiofrequency ablation Maze procedure, average time increase of aortic clamping was 20.5 minutes, and there was no danger of hemorrhage related to this kinds of Maze procedure. During 7-10 days after operation, there appeared superventricular arrhythmia which might be related to ill-distribution of radiofrequency ablation, and interference of atrial electric activity. PMID:10677989

  3. Low rate of asymptomatic cerebral embolism and improved procedural efficiency with the novel pulmonary vein ablation catheter GOLD: results of the PRECISION GOLD trial

    PubMed Central

    De Greef, Yves; Dekker, Lukas; Boersma, Lucas; Murray, Stephen; Wieczorek, Marcus; Spitzer, Stefan G.; Davidson, Neil; Furniss, Steve; Hocini, Mélèze; Geller, J. Christoph; Csanádi, Zoltan

    2016-01-01

    Aims This prospective, multicentre study (PRECISION GOLD) evaluated the incidence of asymptomatic cerebral embolism (ACE) after pulmonary vein isolation (PVI) using a new gold multi-electrode radiofrequency (RF) ablation catheter, pulmonary vein ablation catheter (PVAC) GOLD. Also, procedural efficiency of PVAC GOLD was compared with ERACE. The ERACE study demonstrated that a low incidence of ACE can be achieved with a platinum multi-electrode RF catheter (PVAC) combined with procedural manoeuvres to reduce emboli. Methods and results A total of 51 patients with paroxysmal atrial fibrillation (AF) (age 57 ± 9 years, CHA2DS2-VASc score 1.4 ± 1.4) underwent AF ablation with PVAC GOLD. Continuous oral anticoagulation using vitamin K antagonists, submerged catheter introduction, and heparinization (ACT ≥ 350 s prior to ablation) were applied. Cerebral magnetic resonance imaging (MRI) scans were performed within 48 h before and 16–72 h post-ablation. Cognitive function assessed by the Mini-Mental State Exam at baseline and 30 days post-ablation. New post-procedural ACE occurred in only 1 of 48 patients (2.1%) and was not detectable on MRI after 30 days. The average number of RF applications per patient to achieve PVI was lower in PRECISION GOLD (20.3 ± 10.0) than in ERACE (28.8 ± 16.1; P = 0.001). Further, PVAC GOLD ablations resulted in significantly fewer low-power (<3 W) ablations (15 vs. 23%, 5 vs. 10% and 2 vs. 7% in 4:1, 2:1, and 1:1 bipolar:unipolar energy modes, respectively). Mini-Mental State Exam was unchanged in all patients. Conclusion Atrial fibrillation ablation with PVAC GOLD in combination with established embolic lowering manoeuvres results in a low incidence of ACE. Pulmonary vein ablation catheter GOLD demonstrates improved biophysical efficiency compared with platinum PVAC. Trial registration ClinicalTrials.gov NCT01767558. PMID:26826134

  4. Pulmonary vein triggers, focal sources, rotors and atrial cardiomyopathy: implications for the choice of the most effective ablation therapy.

    PubMed

    Pison, L; Tilz, R; Jalife, J; Haïssaguerre, M

    2016-05-01

    Understanding of the pathophysiological mechanism(s) underlying atrial fibrillation (AF) is the foundation on which current ablation strategies are built. In the vast majority of patients with paroxysmal AF, the ablation procedure should target the pulmonary veins. In patients with nonparoxysmal AF, however, pulmonary vein isolation alone seems to be insufficient to prevent the arrhythmia. Several recent clinical trials have investigated the concept that rotors (re-entry based on a meandering central core from which spiral waves emanate) might be the mechanism responsible for sustaining AF. Ablation of these localized AF sources is an important step towards substrate-driven procedures in persistent AF. Hybrid AF ablation procedures, based on the integration of endocardial transcatheter and epicardial off-pump surgical techniques, have been introduced to overcome their mutual shortcomings. The long-term results are encouraging, especially in currently challenging settings such as nonparoxysmal AF and failed endocardial catheter ablation procedures. PMID:26991806

  5. Combined catheter ablation for atrial fibrillation and Watchman® left atrial appendage occlusion procedures: Five-year experience

    PubMed Central

    Phillips, Karen P.; Walker, Daniel T.; Humphries, Julie A.

    2015-01-01

    Background Patients with atrial fibrillation (AF) may benefit from undergoing concomitant interventions of left atrial catheter ablation and device occlusion of the left atrial appendage (LAA) as a two-pronged strategy for rhythm control and stroke prevention. We report on the outcome of combined procedures in a single center case series over a 5-year timeframe. Methods Ninety-eight patients with non-valvular AF and a mean CHA2DS2-VASc score 2.6±1.0 underwent either first time, or redo pulmonary vein isolation (PVI) procedures, followed by successful implant of a Watchman® device. Results All procedures were generally uncomplicated with a mean case time of 213±40 min. Complete LAA occlusion was achieved at initial implant in 92 (94%) patients. Satisfactory LAA occlusion was achieved in 100% of patients at 12 months, with a complete LAA occlusion rate of 86%. All patients discontinued oral anticoagulation. Persistent late peri-device leaks were more frequently associated with device angulation or shoulder protrusion, and were associated with a significantly lower achieved device compression of 12±3% vs. 15±5% (p<0.01) than complete occlusion. One ischemic stroke was recorded over a mean follow-up time of 802±439 days. Twelve months׳ freedom from detectable AF was achieved in 77% of patients. Conclusions Combined procedures of catheter ablation for AF and Watchman® LAA implant appear to be feasible and safe, with excellent rates of LAA occlusion achieved and an observed stroke rate of 0.5% per year during mid-term follow-up. Incomplete occlusion was associated with lower achieved device compression and was more frequently associated with suboptimal device position. PMID:27092193

  6. High risk in atrial fibrillation following an ablation procedure: the wide usefulness of the CHADS(2) score.

    PubMed

    Fauchier, Laurent; Taillandier, Sophie; Clementy, Nicolas

    2012-09-01

    Evaluation of: Chao TF, Ambrose K, Tsao HM et al. Relationship between the CHADS(2) score and risk of very late recurrences after catheter ablation of paroxysmal atrial fibrillation. Heart Rhythm 9(8), 1185-1191 (2012). Limited data are available on the predictors of adverse events and recurrences in patients with atrial fibrillation (AF) after catheter ablation. In a retrospective analysis of 238 patients with paroxysmal AF treated with catheter ablation, it was found that the congestive heart failure, hypertension, age >75 years, diabetes and previous stroke/transient ischemic attack (CHADS(2)) score was an independent predictor of AF recurrences. Moreover, among patients without recurrences at 2 years post-ablation, future recurrence rate during the subsequent follow-up was 64% in those with a CHADS(2) score of less than three, while it was only 3% in patients with a CHADS(2) score of zero. Patients with a higher CHADS(2) score have a different substrate, a more marked disease in the atrium and this may explain the higher rate of recurrence observed after AF ablation. Several more complex scores are available to separately identify the risk of different events in AF: stroke and embolic events, bleeding events, AF recurrences and progression to more sustained forms of AF. Whether it is a better strategy to use the simple CHADS(2) score to rapidly identify a global risk of all future events in AF more widely remains to be determined. PMID:23013122

  7. Ablation of Atrial Fibrillation: Patient Selection, Periprocedural Anticoagulation, Techniques, and Preventive Measures After Ablation.

    PubMed

    Link, Mark S; Haïssaguerre, Michel; Natale, Andrea

    2016-07-26

    Atrial fibrillation (AF) is the most common arrhythmia encountered by cardiologists and is a major cause of morbidity and mortality. Risk factors for AF include age, male sex, genetic predisposition, hypertension, diabetes mellitus, sleep apnea, obesity, excessive alcohol, smoking, hyperthyroidism, pulmonary disease, air pollution, heart failure, and possibly excessive exercise. The management of AF involves decisions about rate versus rhythm control. Asymptomatic patients are generally managed with rate control and anticoagulation. Symptomatic patients will desire rhythm control. Rhythm control options are either antiarrhythmic agents or ablation, with each having its own risks and benefits. Ablation of AF has evolved from a rare and complex procedure to a common electrophysiological technique. Selection of patients to undergo ablation is an important aspect of AF care. Patients with the highest success rates of ablation are those with normal structural hearts and paroxysmal AF, although those with congestive heart failure have the greatest potential benefit of the procedure. Although pulmonary vein isolation of any means/energy source is the approach generally agreed on for those with paroxysmal AF, optimal techniques for the ablation of nonparoxysmal AF are not yet clear. Anticoagulation reduces thromboembolic complications; the newer anticoagulants have eased management for both the patient and the cardiologist. Aggressive management of modifiable risk factors (hypertension, diabetes mellitus, sleep apnea, obesity, excessive alcohol, smoking, hyperthyroidism, pulmonary disease, air pollution, and possibly excessive exercise) after ablation reduces the odds of recurrent AF and is an important element of care. PMID:27462054

  8. What have we learned of ablation procedures for atrial fibrillation?

    PubMed

    Maurer, T; Lundqvist, C B; Tilz, R; Mont, L; Chierchia, G-B; Malmborg, H; Metzner, A; Kuck, K-H

    2016-05-01

    Atrial fibrillation is a widespread disease of growing clinical, economic and social importance. Interventional therapy for atrial fibrillation offers encouraging results, with pulmonary vein isolation (PVI) as the established cornerstone. Yet, the challenge to create durable transmural lesions remains, leading to recurrence of atrial fibrillation in long-term follow-up even after multiple ablation procedures in 20% of patients with paroxysmal atrial fibrillation and approximately 50% with persistent atrial fibrillation. To overcome these limitations, innovative tools such as the cryoballoon and contact force catheters have been introduced and have demonstrated their potential for safe and effective PVI. Furthermore, advanced pharmacological and pacing manoeuvres enhance evaluation of conduction block in PVI. PMID:26940476

  9. A systematic review of minimally invasive surgical treatment for atrial fibrillation: a comparison of the Cox-Maze procedure, beating-heart epicardial ablation, and the hybrid procedure on safety and efficacy.

    PubMed

    Je, Hyung Gon; Shuman, Deborah J; Ad, Niv

    2015-10-01

    There is a growing trend to perform off-bypass surgical ablation for atrial fibrillation (AF) because it is perceived to be safer and more effective than the Cox-Maze procedure with cardiopulmonary bypass (CPB) support. In this systematic review, we compared three minimally invasive stand-alone surgical ablation procedures for AF: the endocardial Cox-Maze procedure, epicardial surgical ablation and a hybrid epicardial surgical and catheter-based endocardial ablation procedure (hybrid procedure). Relevant studies were identified in MEDLINE and the Cochrane Database of Systematic Reviews according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. From 565 initial studies, 37 were included in this review. The total number of patients across all studies was 1877 (range 10-139). Two studies reported on endocardial Cox-Maze procedures (n = 145), 26 reported on epicardial surgical ablation (n = 1382) and 9 reported on hybrid surgical ablation (n = 350). For minimally invasive Cox-Maze, epicardial and hybrid groups, operative mortality rates were 0, 0.5 and 0.9%, perioperative permanent pacemaker insertion rates were 3.5, 2.7 and 1.5%, incidence of conversion to median sternotomy was 0, 2.4 and 2.5%, and reoperation for bleeding was 1.0, 1.5 and 2.2%, with mean length of stay (days) of 5.4, 6.0 and 4.6, respectively. At 12 months, rates of sinus rhythm restoration were 93, 80 and 70%, and sinus restoration without anti-arrhythmic medications was 87, 72 and 71%, for Cox-Maze, epicardial and hybrid procedures, respectively. Of the three procedures, the minimally invasive Cox-Maze procedure with CPB support was most effective for the treatment of stand-alone AF and had important safety advantages in conversion to sternotomy and major bleeding. The minimally invasive Cox-Maze procedure with CPB support also demonstrated the potential for a higher success rate 12 months following the procedure. PMID:25567961

  10. DISPARATE EVOLUTION OF RIGHT AND LEFT ATRIAL RATE DURING ABLATION OF LONG-LASTING PERSISTENT ATRIAL FIBRILLATION

    PubMed Central

    Hocini, Mélèze; Nault, Isabelle; Wright, Matthew; Veenhuyzen, George; Narayan, Sanjiv M.; Jaïs, Pierre; Lim, Kang-Teng; Knecht, Sébastien; Matsuo, Seiichiro; Forclaz, Andrei; Miyazaki, Shinsuke; Jadidi, Amir; O’Neill, Mark D.; Sacher, Frédéric; Clémenty, Jacques; Haïssaguerre, Michel

    2010-01-01

    Objectives To assess whether additional ablation in the right atrium(RA) improves termination rate in long-lasting persistent atrial fibrillation(PsAF). Background Prolongation of atrial fibrillation(AF) cycle length(CL) measured from the left atrial appendage predicts favorable outcome during catheter ablation of PsAF. However, in some patients despite prolongation of AFCL in the left atrium(LA) with ablation, AF persists. We hypothesized that this is due to RA drivers and these patients may benefit from RA ablation. Methods 148 consecutive patients undergoing catheter ablation of PsAF(duration 25±32 months) were studied. AFCL was monitored in both atria during stepwise ablation commencing in the LA. Ablation was performed in the RA when all LA sources in AF had been ablated and a RA-LA gradient existed. The procedural endpoint was AF termination. Results Two distinct patterns of AFCL change emerged during LA ablation. In 104patients(70%), there was parallel increase of AFCL in LA and RA culminating in AF termination (baseline: LA 153ms[140,170], RA 155ms[143,171]; after ablation: LA 181ms[170,200], RA 186ms[175,202]). In 24 patients(19%), RA AFCL did not prolong, creating a right-to-left frequency gradient, (baseline: LA 142ms[143,153], RA 145 ms[139,162]; after ablation: LA 177 ms[165–185], RA 152ms[147,175]). These patients had a longer AF history (23versus12 months, p=0.001), and larger RA diameter (42versus39mm, p=0.005) and RA ablation terminated AF in 55%. In the remaining 20 patients, biatrial ablation failed to terminate AF. Conclusions A divergent pattern of AFCL prolongation after LA ablation resulting in a right-to-left gradient demonstrating that the right atrium is driving AF in about 20 % of PsAF. PMID:20202517

  11. Clinical Significance of Additional Ablation of Atrial Premature Beats after Catheter Ablation for Atrial Fibrillation

    PubMed Central

    Kim, In-Soo; Yang, Pil-Sung; Kim, Tae-Hoon; Park, Junbeum; Park, Jin-Kyu; Uhm, Jae Sun; Joung, Boyoung; Lee, Moon Hyoung

    2016-01-01

    Purpose The clinical significance of post-procedural atrial premature beats immediately after catheter ablation for atrial fibrillation (AF) has not been clearly determined. We hypothesized that the provocation of immediate recurrence of atrial premature beats (IRAPB) and additional ablation improves the clinical outcome of AF ablation. Materials and Methods We enrolled 200 patients with AF (76.5% males; 57.4±11.1 years old; 64.3% paroxysmal AF) who underwent catheter ablation. Post-procedure IRAPB was defined as frequent atrial premature beats (≥6/min) under isoproterenol infusion (5 µg/min), monitored for 10 min after internal cardioversion, and we ablated mappable IRAPBs. Post-procedural IRAPB provocations were conducted in 100 patients. We compared the patients who showed IRAPB with those who did not. We also compared the IRAPB provocation group with 100 age-, sex-, and AF-type-matched patients who completed ablation without provocation (No-Test group). Results 1) Among the post-procedural IRAPB provocation group, 33% showed IRAPB and required additional ablation with a longer procedure time (p=0.001) than those without IRAPB, without increasing the complication rate. 2) During 18.0±6.6 months of follow-up, the patients who showed IRAPB had a worse clinical recurrence rate than those who did not (27.3% vs. 9.0%; p=0.016), in spite of additional IRAPB ablation. 3) However, the clinical recurrence rate was significantly lower in the IRAPB provocation group (15.0%) than in the No-Test group (28.0%; p=0.025) without lengthening of the procedure time or raising complication rate. Conclusion The presence of post-procedural IRAPB was associated with a higher recurrence rate after AF ablation. However, IRAPB provocation and additional ablation might facilitate a better clinical outcome. A further prospective randomized study is warranted. PMID:26632385

  12. Microwave Ablation of Porcine Kidneys in vivo: Effect of two Different Ablation Modes ('Temperature Control' and 'Power Control') on Procedural Outcome

    SciTech Connect

    Sommer, C. M.; Arnegger, F.; Koch, V.; Pap, B.; Holzschuh, M.; Bellemann, N.; Gehrig, T.; Senft, J.; Nickel, F.; Mogler, C.; Zelzer, S.; Meinzer, H. P.; Stampfl, U.; Kauczor, H. U.; Radeleff, B. A.

    2012-06-15

    Purpose: This study was designed to analyze the effect of two different ablation modes ('temperature control' and 'power control') of a microwave system on procedural outcome in porcine kidneys in vivo. Methods: A commercially available microwave system (Avecure Microwave Generator; MedWaves, San Diego, CA) was used. The system offers the possibility to ablate with two different ablation modes: temperature control and power control. Thirty-two microwave ablations were performed in 16 kidneys of 8 pigs. In each animal, one kidney was ablated twice by applying temperature control (ablation duration set point at 60 s, ablation temperature set point at 96 Degree-Sign C, automatic power set point; group I). The other kidney was ablated twice by applying power control (ablation duration set point at 60 s, ablation temperature set point at 96 Degree-Sign C, ablation power set point at 24 W; group II). Procedural outcome was analyzed: (1) technical success (e.g., system failures, duration of the ablation cycle), and (2) ablation geometry (e.g., long axis diameter, short axis diameter, and circularity). Results: System failures occurred in 0% in group I and 13% in group II. Duration of the ablation cycle was 60 {+-} 0 s in group I and 102 {+-} 21 s in group II. Long axis diameter was 20.3 {+-} 4.6 mm in group I and 19.8 {+-} 3.5 mm in group II (not significant (NS)). Short axis diameter was 10.3 {+-} 2 mm in group I and 10.5 {+-} 2.4 mm in group II (NS). Circularity was 0.5 {+-} 0.1 in group I and 0.5 {+-} 0.1 in group II (NS). Conclusions: Microwave ablations performed with temperature control showed fewer system failures and were finished faster. Both ablation modes demonstrated no significant differences with respect to ablation geometry.

  13. Design and evaluation of a transesophageal HIFU probe for ultrasound-guided cardiac ablation: simulation of a HIFU mini-maze procedure and preliminary ex vivo trials.

    PubMed

    Constanciel, Elodie; N'Djin, W Apoutou; Bessière, Francis; Chavrier, Françoise; Grinberg, Daniel; Vignot, Alexandre; Chevalier, Philippe; Chapelon, Jean Yves; Lafon, Cyril

    2013-09-01

    Atrial fibrillation (AF) is the most frequent cardiac arrhythmia. Left atrial catheter ablation is currently performed to treat this disease. Several energy sources are used, such as radio-frequency or cryotherapy. The main target of this procedure is to isolate the pulmonary veins. However, significant complications caused by the invasive procedure are described, such as stroke, tamponade, and atrioesophageal fistula, and a second intervention is often needed to avoid atrial fibrillation recurrence. For these reasons, a minimally-invasive device allowing performance of more complex treatments is still needed. High-intensity focused ultrasound (HIFU) can cause deep tissue lesions without damaging intervening tissues. Left atrial ultrasound-guided transesophageal HIFU ablation could have the potential to become a new ablation technique. The goal of this study was to design and test a minimally-invasive ultrasound-guided transesophageal HIFU probe under realistic treatment conditions. First, numerical simulations were conducted to determine the probe geometry, and to validate the feasibility of performing an AF treatment using a HIFU mini-maze (HIFUMM) procedure. Then, a prototype was manufactured and characterized. The 18-mm-diameter probe head housing contained a 3-MHz spherical truncated HIFU transducer divided into 8 rings, with a 5-MHz commercial transesophageal echocardiography (TEE) transducer integrated in the center. Finally, ex vivo experiments were performed to test the impact of the esophagus layer between the probe and the tissue to treat, and also the influence of the lungs and the vascularization on lesion formation. First results show that this prototype successfully created ex vivo transmural myocardial lesions under ultrasound guidance, while preserving intervening tissues (such as the esophagus). Ultrasound-guided transesophageal HIFU can be a good candidate for treatment of AF in the future. PMID:24658718

  14. Contact force sensing during atrial fibrillation ablation: clinical experience and effects on outcomes.

    PubMed

    Liang, Jackson J; Santangeli, Pasquale

    2016-06-01

    Catheter ablation is an effective treatment option for atrial fibrillation (AF), and pulmonary vein isolation (PVI) is the cornerstone of AF ablation. When AF recurs after ablation, PV reconnection is frequently seen during repeat ablation. As such, achieving durable chronic PVI by delivering effective, transmural lesions during the index ablation is key to optimize long-term outcomes. The development of contact force (CF) sensing technologies integrated into ablation catheters now allow for real-time visualization of applied CF during PVI and have been shown to improve ablation efficacy and safety. The aim of this review is to describe the CF technology, summarize the literature on the outcomes of CF-guided ablation, and to discuss procedural aspects that are crucial when using CF. PMID:26998886

  15. Molecular thermometers for potential applications in thermal ablation procedures

    NASA Astrophysics Data System (ADS)

    Zhegalova, Natalia G.; Aydt, Alex; Wang, Steven T.; Berezin, Mikhail Y.

    2013-02-01

    Thermal ablation is a promising minimally invasive method for treating tumors without surgical intervention. Thermal ablation uses thermal sources such as lasers, radiowaves or focused ultrasound to increase the temperature of the tumor to levels lethal to cancer cells. This treatment based on heat therapy may be problematic as the temperature of the operation site is unknown. To address this problem, we developed optical molecular thermometers that can potentially measure the temperature on a molecular scale and be compatible with in vivo measurements. The thermometers are centered on a combination of two fluorophores emitting in two distinct spectral ranges and having different temperature-dependent emission properties. In this design, a fluorophore with relatively insensitive temperature-dependent fluorescence serves as a reference while another sensitive fluorophore serves as a sensor. We have demonstrated the feasibility of this approach using a coumarin-rhodamine conjugate. The sensitivity of the construct to the clinically relevant ablation temperatures (20-85 °C) was demonstrated in vitro.

  16. Outcomes of Cryoballoon Ablation in High- and Low-Volume Atrial Fibrillation Ablation Centres: A Russian Pilot Survey

    PubMed Central

    Mikhaylov, Evgeny N.; Lebedev, Dmitry S.; Pokushalov, Evgeny A.; Davtyan, Karapet V.; Ivanitskii, Eduard A.; Nechepurenko, Anatoly A.; Kosonogov, Alexey Ya.; Kolunin, Grigory V.; Morozov, Igor A.; Termosesov, Sergey A.; Maykov, Evgeny B.; Khomutinin, Dmitry N.; Eremin, Sergey A.; Mayorov, Igor M.; Romanov, Alexander B.; Shabanov, Vitaliy V.; Shatakhtsyan, Victoria; Tsivkovskii, Viktor; Revishvili, Amiran Sh.; Shlyakhto, Evgeny V.

    2015-01-01

    Purpose. The results of cryoballoon ablation (CBA) procedure have been mainly derived from studies conducted in experienced atrial fibrillation (AF) ablation centres. Here, we report on CBA efficacy and complications resulting from real practice of this procedure at both high- and low-volume centres. Methods. Among 62 Russian centres performing AF ablation, 15 (24%) used CBA technology for pulmonary vein isolation. The centres were asked to provide a detailed description of all CBA procedures performed and complications, if encountered. Results. Thirteen sites completed interviews on all CBAs in their centres (>95% of CBAs in Russia). Six sites were high-volume AF ablation (>100 AF cases/year) centres, and 7 were low-volume AF ablation. There was no statistical difference in arrhythmia-free rates between high- and low-volume centres (64.6 versus 60.8% at 6 months). Major complications developed in 1.5% of patients and were equally distributed between high- and low-volume centres. Minor procedure-related events were encountered in 8% of patients and were more prevalent in high-volume centres. Total event and vascular access site event rates were higher in women than in men. Conclusions. CBA has an acceptable efficacy profile in real practice. In less experienced AF ablation centres, the major complication rate is equal to that in high-volume centres. PMID:26640789

  17. Prevention of immediate recurrence of atrial fibrillation with low-dose landiolol after radiofrequency catheter ablation

    PubMed Central

    Ishigaki, Daisuke; Arimoto, Takanori; Iwayama, Tadateru; Hashimoto, Naoaki; Kutsuzawa, Daisuke; Kumagai, Yu; Nishiyama, Satoshi; Takahashi, Hiroki; Shishido, Tetsuro; Miyamoto, Takuya; Watanabe, Tetsu; Kubota, Isao

    2015-01-01

    Background Immediate recurrence of atrial fibrillation (AF) after radiofrequency (RF) catheter ablation is commonly observed within 3 d after the procedure. The mechanism and pharmacological management of immediate AF recurrence remain unclear. Methods A total of 50 consecutive patients with paroxysmal AF were randomized to receive either low-dose landiolol (landiolol group) or a placebo (placebo group). In the landiolol group, intravenous landiolol (0.5 μg kg−1 min−1) was administered for 3 d after AF ablation. Results No serious adverse event associated with RF catheter ablation or landiolol administration was observed. The prevalence of immediate AF recurrence (≤3 d after RF catheter ablation) was significantly lower in the landiolol group than in the placebo group (16% vs. 48%, p=0.015). Although the postprocedural change in heart rate was significantly lower in the landiolol group compared to that in the placebo group, the changes in blood pressure and body temperature were not different between the two groups. Multiple logistic regression analysis revealed that landiolol treatment was the only independent predictor of immediate AF recurrence after ablation (odds ratio: 0.180; 95% confidence interval: 0.044–0.729; p=0.016). Conclusions Prophylactic administration of low-dose landiolol after AF ablation may be effective and safe for preventing immediate AF recurrence within 3 d after AF ablation. PMID:26550083

  18. Lung radiofrequency and microwave ablation: a review of indications, techniques and post-procedural imaging appearances

    PubMed Central

    Jennings, P E

    2015-01-01

    Lung ablation can be used to treat both primary and secondary thoracic malignancies. Evidence to support its use, particularly for metastases from colonic primary tumours, is now strong, with survival data in selected cases approaching that seen after surgery. Because of this, the use of ablative techniques (particularly thermal ablation) is growing and the Royal College of Radiologists predict that the number of patients who could benefit from such treatment may reach in excess of 5000 per year in the UK. Treatment is often limited to larger regional centres, and general radiologists often have limited awareness of the current indications and the techniques involved. Furthermore, radiologists without any prior experience are frequently expected to interpret post-treatment imaging, often performed in the context of acute complications, which have occurred after discharge. This review aims to provide an overview of the current indications for pulmonary ablation, together with the techniques involved and the range of post-procedural appearances. PMID:25465192

  19. Estimating Effective Dose from Phantom Dose Measurements in Atrial Fibrillation Ablation Procedures and Comparison of MOSFET and TLD Detectors in a Small Animal Dosimetry Setting

    NASA Astrophysics Data System (ADS)

    Anderson-Evans, Colin David

    Two different studies will be presented in this work. The first involves the calculation of effective dose from a phantom study which simulates an atrial fibrillation (AF) ablation procedure. The second involves the validation of metal-oxide semiconducting field effect transistors (MOSFET) for small animal dosimetry applications as well as improved characterization of the animal irradiators on Duke University's campus. Atrial Fibrillation is an ever increasing health risk in the United States. The most common type of cardiac arrhythmia, AF is associated with increased mortality and ischemic cerebrovascular events. Managing AF can include, among other treatments, an interventional procedure called catheter ablation. The procedure involves the use of biplane fluoroscopy during which a patient can be exposed to radiation for as much as two hours or more. The deleterious effects of radiation become a concern when dealing with long fluoroscopy times, and because the AF ablation procedure is elective, it makes relating the risks of radiation ever more essential. This study hopes to quantify the risk through the derivation of dose conversion coefficients (DCCs) from the dose-area product (DAP) with the intent that DCCs can be used to provide estimates of effective dose (ED) for typical AF ablation procedures. A bi-plane fluoroscopic and angiographic system was used for the simulated AF ablation procedures. For acquisition of organ dose measurements, 20 diagnostic MOSFET detectors were placed at selected organs in a male anthropomorphic phantom, and these detectors were attached to 4 bias supplies to obtain organ dose readings. The DAP was recorded from the system console and independently validated with an ionization chamber and radiochromic film. Bi-plane fluoroscopy was performed on the phantom for 10 minutes to acquire the dose rate for each organ, and the average clinical procedure time was multiplied by each organ dose rate to obtain individual organ doses. The

  20. Estimating Effective Dose from Phantom Dose Measurements in Atrial Fibrillation Ablation Procedures and Comparison of MOSFET and TLD Detectors in a Small Animal Dosimetry Setting

    NASA Astrophysics Data System (ADS)

    Anderson-Evans, Colin David

    Two different studies will be presented in this work. The first involves the calculation of effective dose from a phantom study which simulates an atrial fibrillation (AF) ablation procedure. The second involves the validation of metal-oxide semiconducting field effect transistors (MOSFET) for small animal dosimetry applications as well as improved characterization of the animal irradiators on Duke University's campus. Atrial Fibrillation is an ever increasing health risk in the United States. The most common type of cardiac arrhythmia, AF is associated with increased mortality and ischemic cerebrovascular events. Managing AF can include, among other treatments, an interventional procedure called catheter ablation. The procedure involves the use of biplane fluoroscopy during which a patient can be exposed to radiation for as much as two hours or more. The deleterious effects of radiation become a concern when dealing with long fluoroscopy times, and because the AF ablation procedure is elective, it makes relating the risks of radiation ever more essential. This study hopes to quantify the risk through the derivation of dose conversion coefficients (DCCs) from the dose-area product (DAP) with the intent that DCCs can be used to provide estimates of effective dose (ED) for typical AF ablation procedures. A bi-plane fluoroscopic and angiographic system was used for the simulated AF ablation procedures. For acquisition of organ dose measurements, 20 diagnostic MOSFET detectors were placed at selected organs in a male anthropomorphic phantom, and these detectors were attached to 4 bias supplies to obtain organ dose readings. The DAP was recorded from the system console and independently validated with an ionization chamber and radiochromic film. Bi-plane fluoroscopy was performed on the phantom for 10 minutes to acquire the dose rate for each organ, and the average clinical procedure time was multiplied by each organ dose rate to obtain individual organ doses. The

  1. Applications of computed tomography and magnetic resonance imaging in percutaneous ablation therapy for atrial fibrillation.

    PubMed

    Chyou, Janice Y; Biviano, Angelo; Magno, Pedro; Garan, Hasan; Einstein, Andrew J

    2009-10-01

    Percutaneous catheter ablation is an established therapy for symptomatic drug-refractory atrial fibrillation (AF). Accurate delineation of relevant anatomy is critical but often challenging and limited in traditional technologies such as intra-procedural fluoroscopy. There has been an increased interest in non-invasive three-dimensional imaging technologies, especially computed tomography (CT) and magnetic resonance imaging (MRI), as useful tools for patients undergoing AF ablation. Here, we review applications of CT and MRI before, during, and after AF ablation and highlight areas for future research. PMID:19521756

  2. Respiratory motion influence on catheter contact force during radio frequency ablation procedures

    NASA Astrophysics Data System (ADS)

    Koch, Martin; Brost, Alexander; Hornegger, Joachim; Strobel, Norbert

    2013-03-01

    Minimally invasive catheter ablation is a common treatment option for atrial fibrillation. A common treatment strategy is pulmonary vein isolation. In this case, individual ablation points need to be placed around the ostia of the pulmonary veins attached to the left atrium to generate transmural lesions and thereby block electric signals. To achieve a durable transmural lesion, the tip of the catheter has to be stable with a sufficient tissue contact during radio-frequency ablation. Besides the steerable interface operated by the physician, the movement of the catheter is also influenced by the heart and breathing motion - particularly during ablation. In this paper we investigate the influence of breathing motion on different areas of the endocardium during radio frequency ablation. To this end, we analyze the frequency spectrum of the continuous catheter contact force to identify areas with increased breathing motion using a classification method. This approach has been applied to clinical patient data acquired during three pulmonary vein isolation procedures. Initial findings show that motion due to respiration is more pronounced at the roof and around the right pulmonary veins.

  3. Current ablation techniques for persistent atrial fibrillation: results of the European Heart Rhythm Association Survey.

    PubMed

    Dagres, Nikolaos; Bongiorni, Maria Grazia; Larsen, Torben Bjerregaard; Hernandez-Madrid, Antonio; Pison, Laurent; Blomström-Lundqvist, Carina

    2015-10-01

    The aim of this survey was to provide insight into current practice regarding ablation of persistent atrial fibrillation (AF) among members of the European Heart Rhythm Association electrophysiology research network. Thirty centres responded to the survey. The main ablation technique for first-time ablation was stand-alone pulmonary vein isolation (PVI): in 67% of the centres for persistent but not long-standing AF and in 37% of the centres for long-standing persistent AF as well. Other applied techniques were ablation of fractionated electrograms, placement of linear lesions, stepwise approach until AF termination, and substrate mapping and isolation of low-voltage areas. However, the percentage of centres applying these techniques during first ablation did not exceed 25% for any technique. When stand-alone PVI was performed in patients with persistent but not long-standing AF, the majority (80%) of the centres used an irrigated radiofrequency ablation catheter whereas 20% of the respondents used the cryoballoon. Similar results were reported for ablation of long-standing persistent AF (radiofrequency 90%, cryoballoon 10%). Neither rotor mapping nor one-shot ablation tools were used as the main first-time ablation methods. Systematic search for non-pulmonary vein triggers was performed only in 10% of the centres. Most common 1-year success rate off antiarrhythmic drugs was 50-60%. Only 27% of the centres knew their 5-year results. In conclusion, patients with persistent AF represent a significant proportion of AF patients undergoing ablation. There is a shift towards stand-alone PVI being the primary choice in many centres for first-time ablation in these patients. The wide variation in the use of additional techniques and in the choice of endpoints reflects the uncertainties and lack of guidance regarding the most optimal approach. Procedural success rates are modest and long-term outcomes are unknown in most centres. PMID:26498718

  4. Is dabigatran efficacy enough to prevent stroke in atrial fibrillation patient with high CHADS2 score during peri-procedural catheter radiofrequency ablation? A case report with literature review

    PubMed Central

    Shi, Xiang-Min; Chen, Fu-Kun; Liang, Zhuo; Li, Jian; Lin, Kun; Guo, Jian-Ping; Shan, Zhao-Liang

    2015-01-01

    Atrial fibrillation (AF) is a major cause of thromboembolic (TE) events including stroke and transient ischemic attacks, catheter radiofrequency ablation (CA) has been demonstrated to effectively eliminate AF in majority of patients. During the peri-procedural CA of AF, dabigatran, a reversible direct thrombin inhibitor, has been proved as safe and efficacy as warfarin in the prevention of thromboembolic complication. However, for patients with CHADS2 score ≥3, sometimes dabigatran may not be an ideal substitute of warfarin. The current study presents delayed stroke occurred in a middle-aged AF patient with high CHADS2 score who had undergone successful CA of AF being on dabigatran, trans esophageal echocardiogram (TEE) detected a clot in the left atrium appendage (LAA) and magnetic resonance image (MRI) indicated stroke of left basal ganglia, therefore anticoagulant was switched to warfarin with well controlled international normalization ratio (INR) ranging from 2.0-3.0 and the patient eventually recovered without any TE events during the subsequent follow-up. PMID:26131290

  5. Left Atrial Anatomy Relevant to Catheter Ablation

    PubMed Central

    Sánchez-Quintana, Damián; Cabrera, José Angel; Saremi, Farhood

    2014-01-01

    The rapid development of interventional procedures for the treatment of arrhythmias in humans, especially the use of catheter ablation techniques, has renewed interest in cardiac anatomy. Although the substrates of atrial fibrillation (AF), its initiation and maintenance, remain to be fully elucidated, catheter ablation in the left atrium (LA) has become a common therapeutic option for patients with this arrhythmia. Using ablation catheters, various isolation lines and focal targets are created, the majority of which are based on gross anatomical, electroanatomical, and myoarchitectual patterns of the left atrial wall. Our aim was therefore to review the gross morphological and architectural features of the LA and their relations to extracardiac structures. The latter have also become relevant because extracardiac complications of AF ablation can occur, due to injuries to the phrenic and vagal plexus nerves, adjacent coronary arteries, or the esophageal wall causing devastating consequences. PMID:25057427

  6. A Modified Epicardial Radiofrequency Ablation for Preoperative Atrial Fibrillation Combined With Isolated Aortic Valve Disease.

    PubMed

    Jiang, Zhaolei; Ma, Nan; Liu, Hao; Tang, Min; Ding, Fangbao; Bao, Chunrong; Mei, Ju

    2016-06-01

    Isolated aortic valve diseases can lead to atrial fibrillation (AF) by causing left atrium pressure overload and enlargement. At present, most patients with preoperative AF and isolated aortic valve disease have undergone a Cox-maze IV procedure through a left atriotomy under cardiopulmonary bypass with aortic cross-clamping. Here, we describe a novel modified epicardial radiofrequency ablation procedure performed on a beating heart without aortic cross-clamping or opening the left atrium. This technique has proved to be safe and feasible, with good clinical outcomes. It may be useful in selecting the best ablation approaches for patients with AF and aortic valve disease. PMID:27211963

  7. One-Dimensional Ablation with Pyrolysis Gas Flow Using a Full Newton's Method and Finite Control Volume Procedure

    NASA Technical Reports Server (NTRS)

    Amar, Adam J.; Blackwell, Ben F.; Edwards, Jack R.

    2007-01-01

    The development and verification of a one-dimensional material thermal response code with ablation is presented. The implicit time integrator, control volume finite element spatial discretization, and Newton's method for nonlinear iteration on the entire system of residual equations have been implemented and verified for the thermochemical ablation of internally decomposing materials. This study is a continuation of the work presented in "One-Dimensional Ablation with Pyrolysis Gas Flow Using a Full Newton's Method and Finite Control Volume Procedure" (AIAA-2006-2910), which described the derivation, implementation, and verification of the constant density solid energy equation terms and boundary conditions. The present study extends the model to decomposing materials including decomposition kinetics, pyrolysis gas flow through the porous char layer, and a mixture (solid and gas) energy equation. Verification results are presented for the thermochemical ablation of a carbon-phenolic ablator which involves the solution of the entire system of governing equations.

  8. Thermal protection during percutaneous thermal ablation procedures: interest of carbon dioxide dissection and temperature monitoring.

    PubMed

    Buy, Xavier; Tok, Chung-Hong; Szwarc, Daniel; Bierry, Guillaume; Gangi, Afshin

    2009-05-01

    Percutaneous image-guided thermal ablation of tumor is widely used, and thermal injury to collateral structures is a known complication of this technique. To avoid thermal damage to surrounding structures, several protection techniques have been reported. We report the use of a simple and effective protective technique combining carbon dioxide dissection and thermocouple: CO(2) displaces the nontarget structures, and its low thermal conductivity provides excellent insulation; insertion of a thermocouple in contact with vulnerable structures achieves continuous thermal monitoring. We performed percutaneous thermal ablation of 37 tumors in 35 patients (4 laser, 10 radiofrequency, and 23 cryoablations) with protection of adjacent vulnerable structures by using CO(2) dissection combined with continuous thermal monitoring with thermocouple. Tumor locations were various (19 intra-abdominal tumors including 4 livers and 9 kidneys, 18 musculoskeletal tumors including 11 spinal tumors). CO(2) volume ranged from 10 ml (epidural space) to 1500 ml (abdominal). Repeated insufflations were performed if necessary, depending on the information given by the thermocouple and imaging control. Dissection with optimal thermal protection was achieved in all cases except two patients where adherences (one postoperative, one arachnoiditis) blocked proper gaseous distribution. No complication referred to this technique was noted. This safe, cost-effective, and simple method increases the safety and the success rate of percutaneous thermal ablation procedures. It also offers the potential to increase the number of tumors that can be treated via a percutaneous approach. PMID:19219496

  9. Thermal Protection During Percutaneous Thermal Ablation Procedures: Interest of Carbon Dioxide Dissection and Temperature Monitoring

    SciTech Connect

    Buy, Xavier; Tok, Chung-Hong; Szwarc, Daniel; Bierry, Guillaume; Gangi, Afshin

    2009-05-15

    Percutaneous image-guided thermal ablation of tumor is widely used, and thermal injury to collateral structures is a known complication of this technique. To avoid thermal damage to surrounding structures, several protection techniques have been reported. We report the use of a simple and effective protective technique combining carbon dioxide dissection and thermocouple: CO{sub 2} displaces the nontarget structures, and its low thermal conductivity provides excellent insulation; insertion of a thermocouple in contact with vulnerable structures achieves continuous thermal monitoring. We performed percutaneous thermal ablation of 37 tumors in 35 patients (4 laser, 10 radiofrequency, and 23 cryoablations) with protection of adjacent vulnerable structures by using CO{sub 2} dissection combined with continuous thermal monitoring with thermocouple. Tumor locations were various (19 intra-abdominal tumors including 4 livers and 9 kidneys, 18 musculoskeletal tumors including 11 spinal tumors). CO{sub 2} volume ranged from 10 ml (epidural space) to 1500 ml (abdominal). Repeated insufflations were performed if necessary, depending on the information given by the thermocouple and imaging control. Dissection with optimal thermal protection was achieved in all cases except two patients where adherences (one postoperative, one arachnoiditis) blocked proper gaseous distribution. No complication referred to this technique was noted. This safe, cost-effective, and simple method increases the safety and the success rate of percutaneous thermal ablation procedures. It also offers the potential to increase the number of tumors that can be treated via a percutaneous approach.

  10. Patient reported outcome measures for cardiac ablation procedures: a multicentre pilot to develop a new questionnaire

    PubMed Central

    Withers, Kathleen L.; White, Judith; Carolan-Rees, Grace; Patrick, Hannah; O'Callaghan, Peter; Murray, Stephen; Cunningham, David; Wood, Kathryn A.; Lencioni, Mauro; Griffith, Michael

    2014-01-01

    Aim To assess the feasibility of administering Patient Reported Outcomes Measures (PROMs) in patients treated with ablation for cardiac arrhythmias, and to conduct the first stage of development and testing of a new PROM tool. Methods and results A new tool was developed by a multidisciplinary team and tested alongside an adaptation of the patient perception of arrhythmia questionnaire (PPAQ) and EQ-5D-5L in a multicentre retrospective audit involving 791 consecutive cardiac arrhythmia patients treated with catheter ablation at three UK centres over 13 months. Data were recorded in the National Cardiac Rhythm Management Database, part of the National Institute for Cardiovascular Outcomes Research. The response rate was 71.9% (n = 569). Patients reported significant improvements across all outcomes and impacts, with reductions in symptoms of 51.7% (heart racing), 33.9% (fatigue) 31.8% (heart flutters), 43.5% (dizziness), 38.6% (breathlessness), 44.2% (chest pressure), 33.1% (trouble concentrating), 15.9% (headache), 28.3% (neck pressure), and 23.4% (fainting) (P < 0.001). The mean number of social days affected reduced by 7.49 days/month (P < 0.001); mean work/school days affected/month reduced by 6.26 (P < 0.001); mean GP/hospital visits reduced by 1.36 days/month (P < 0.001). The procedure met patient expectations in 72% of responders. Conclusions The high response rate suggests that the use of PROMs in this patient group is feasible, with rates equalling those of the National PROMs Programme. The results showed that patients experienced significant improvements in their quality of life following ablation, while feedback allowed the tools to be improved. Further work is required to validate these tools; however, the findings suggest that PROMs could be useful in the audit of ablation techniques. PMID:24627541

  11. Pathogenesis of AF: Impact on intracardiac signals

    PubMed Central

    Shah, Ashok J; Dubois, Rémi; Miyazaki, Shinsuke; Jadidi, Amir S; Scherr, Daniel; Wilton, Stephen B; Roten, Laurent; Pascale, Patrizio; Pedersen, Michala; Derval, Nicolas; Knecht, Sebastien; Sacher, Frederic; Jais, Pierre; Narayan, Sanjiv; Hocini, Mélèze; Haïssaguerre, Michel

    2014-01-01

    Atrial fibrillation (AF) is the most common cardiac arrhythmia, and is responsible for the highest number of rhythm-related disorders and cardioembolic strokes worldwide. Intracardiac signal analysis during the onset of paroxysmal AF led to the discovery of pulmonary vein as a triggering source of AF, which has led to the development of pulmonary vein ablation—an established curative therapy for drug-resistant AF. Complex, multicomponent and rapid electrical activity widely involving the atrial substrate characterizes persistent/permanent AF. Widespread nature of the problem and complexity of signals in persistent AF reduce the success rate of ablation therapy. Although signal processing applied to extraction of relevant features from these complex electrograms has helped to improve the efficacy of ablation therapy in persistent/permanent AF, improved understanding of complex signals should help to identify sources of AF and further increase the success rate of ablation therapy. PMID:22255589

  12. Impact of esophageal temperature monitoring guided atrial fibrillation ablation on preventing asymptomatic excessive transmural injury

    PubMed Central

    Kiuchi, Kunihiko; Okajima, Katsunori; Shimane, Akira; Kanda, Gaku; Yokoi, Kiminobu; Teranishi, Jin; Aoki, Kousuke; Chimura, Misato; Toba, Takayoshi; Oishi, Shogo; Sawada, Takahiro; Tsukishiro, Yasue; Onishi, Tetsuari; Kobayashi, Seiichi; Taniguchi, Yasuyo; Yamada, Shinichiro; Yasaka, Yoshinori; Kawai, Hiroya; Yoshida, Akihiro; Fukuzawa, Koji; Itoh, Mitsuaki; Imamura, Kimitake; Fujiwara, Ryudo; Suzuki, Atsushi; Nakanishi, Tomoyuki; Yamashita, Soichiro; Hirata, Ken-ichi; Tada, Hiroshi; Yamasaki, Hiro; Naruse, Yoshihisa; Igarashi, Miyako; Aonuma, Kazutaka

    2015-01-01

    Background Even with the use of a reduced energy setting (20–25 W), excessive transmural injury (ETI) following catheter ablation of atrial fibrillation (AF) is reported to develop in 10% of patients. However, the incidence of ETI depends on the pulmonary vein isolation (PVI) method and its esophageal temperature monitor setting. Data comparing the incidence of ETI following AF ablation with and without esophageal temperature monitoring (ETM) are still lacking. Methods This study was comprised of 160 patients with AF (54% paroxysmal, mean: 24.0±2.9 kg/m2). Eighty patients underwent ablation accompanied by ETM. The primary endpoint was defined as the occurrence of ETI assessed by endoscopy within 5 d after the AF ablation. The secondary endpoint was defined as AF recurrence after a single procedure. If the esophageal temperature probe registered >39 °C, the radiofrequency (RF) application was stopped immediately. RF applications could be performed in a point-by-point manner for a maximum of 20 s and 20 W. ETI was defined as any injury that resulted from AF ablation, including esophageal injury or periesophageal nerve injury (peri-ENI). Results The incidence of esophageal injury was significantly lower in patients whose AF ablation included ETM compared with patients without ETM (0 [0%] vs. 6 [7.5%], p=0.028), but not the incidence of peri-ENI (2 [2.5%] vs. 3 [3.8%], p=1.0). AF recurrence 12 months after the procedure was similar between the groups (20 [25%] in the ETM group vs. 19 [24%] in the non-ETM group, p=1.00). Conclusions Catheter ablation using ETM may reduce the incidence of esophageal injury without increasing the incidence of AF recurrence but not the incidence of peri-ENI. PMID:26949429

  13. Cost analysis of periprocedural imaging in patients undergoing catheter ablation for atrial fibrillation.

    PubMed

    Pokorney, Sean D; Hammill, Bradley G; Qualls, Laura G; Steinberg, Benjamin A; Curtis, Lesley H; Piccini, Jonathan P

    2014-07-15

    Cardiovascular imaging is an important part of procedural planning and safety for catheter ablation of atrial fibrillation (AF). However, the costs of imaging surrounding catheter ablation of AF have not been described. Medicare fee-for-service data were used to evaluate Medicare expenditures before, during, and after catheter ablation for AF from July 2007 to December 2009. Among 11,525 patients who underwent catheter ablation for AF, the mean overall expenditure on the day of the procedure was $14,455 (SD $7,441). The mean imaging expenditure in the periprocedural period, which included the 30 days before the catheter ablation and the day of the ablation itself, was $884 (SD $455). Periprocedural imaging expenditures varied by the imaging strategy used, ranging from a mean of $557 (SD $269) for patients with electroanatomic mapping only to $1,234 (SD $461) for patients with electroanatomic mapping, transesophageal echocardiogram, and computed tomography or magnetic resonance imaging. Mean patient-level imaging expenditures varied by provider (mean $872, SD $249). Periprocedural imaging expenditures also varied by patient risk, with mean expenditures of $862 (SD $444) for patients with a CHADS2 score of ≥2 compared with $907 (SD $466) for CHADS2 score<2 (p<0.001). In conclusion, periprocedural imaging accounts for approximately 6% of mean Medicare expenditures for catheter ablation of AF. The expenditures for periprocedural imaging vary both at the patient and at the provider level and they are inversely related to stroke risk by CHADS2 score. PMID:24952929

  14. Atrial Fibrillation Ablation in Systolic Dysfunction: Clinical and Echocardiographic Outcomes

    PubMed Central

    Lobo, Tasso Julio; Pachon, Carlos Thiene; Pachon, Jose Carlos; Pachon, Enrique Indalecio; Pachon, Maria Zelia; Pachon, Juan Carlos; Santillana, Tomas Guillermo; Zerpa, Juan Carlos; Albornoz, Remy Nelson; Jatene, Adib Domingos

    2015-01-01

    Background Heart failure and atrial fibrillation (AF) often coexist in a deleterious cycle. Objective To evaluate the clinical and echocardiographic outcomes of patients with ventricular systolic dysfunction and AF treated with radiofrequency (RF) ablation. Methods Patients with ventricular systolic dysfunction [ejection fraction (EF) <50%] and AF refractory to drug therapy underwent stepwise RF ablation in the same session with pulmonary vein isolation, ablation of AF nests and of residual atrial tachycardia, named "background tachycardia". Clinical (NYHA functional class) and echocardiographic (EF, left atrial diameter) data were compared (McNemar test and t test) before and after ablation. Results 31 patients (6 women, 25 men), aged 37 to 77 years (mean, 59.8±10.6), underwent RF ablation. The etiology was mainly idiopathic (19 p, 61%). During a mean follow-up of 20.3±17 months, 24 patients (77%) were in sinus rhythm, 11 (35%) being on amiodarone. Eight patients (26%) underwent more than one procedure (6 underwent 2 procedures, and 2 underwent 3 procedures). Significant NYHA functional class improvement was observed (pre-ablation: 2.23±0.56; postablation: 1.13±0.35; p<0.0001). The echocardiographic outcome also showed significant ventricular function improvement (EF pre: 44.68%±6.02%, post: 59%±13.2%, p=0.0005) and a significant left atrial diameter reduction (pre: 46.61±7.3 mm; post: 43.59±6.6 mm; p=0.026). No major complications occurred. Conclusion Our findings suggest that AF ablation in patients with ventricular systolic dysfunction is a safe and highly effective procedure. Arrhythmia control has a great impact on ventricular function recovery and functional class improvement. PMID:25387404

  15. Current Hot Potatoes in Atrial Fibrillation Ablation

    PubMed Central

    Roten, Laurent; Derval, Nicolas; Pascale, Patrizio; Scherr, Daniel; Komatsu, Yuki; Shah, Ashok; Ramoul, Khaled; Denis, Arnaud; Sacher, Frédéric; Hocini, Mélèze; Haïssaguerre, Michel; Jaïs, Pierre

    2012-01-01

    Atrial fibrillation (AF) ablation has evolved to the treatment of choice for patients with drug-resistant and symptomatic AF. Pulmonary vein isolation at the ostial or antral level usually is sufficient for treatment of true paroxysmal AF. For persistent AF ablation, drivers and perpetuators outside of the pulmonary veins are responsible for AF maintenance and have to be targeted to achieve satisfying arrhythmia-free success rate. Both complex fractionated atrial electrogram (CFAE) ablation and linear ablation are added to pulmonary vein isolation for persistent AF ablation. Nevertheless, ablation failure and necessity of repeat ablations are still frequent, especially after persistent AF ablation. Pulmonary vein reconduction is the main reason for arrhythmia recurrence after paroxysmal and to a lesser extent after persistent AF ablation. Failure of persistent AF ablation mostly is a consequence of inadequate trigger ablation, substrate modification or incompletely ablated or reconducting linear lesions. In this review we will discuss these points responsible for AF recurrence after ablation and review current possibilities on how to overcome these limitations. PMID:22920482

  16. Endometrial ablation

    MedlinePlus

    Hysteroscopy-endometrial ablation; Laser thermal ablation; Endometrial ablation-radiofrequency; Endometrial ablation-thermal balloon ablation; Rollerball ablation; Hydrothermal ablation; Novasure ablation

  17. Initial Independent Outcomes from Focal Impulse and Rotor Modulation Ablation for Atrial Fibrillation: Multicenter FIRM Registry

    PubMed Central

    MILLER, JOHN M.; KOWAL, ROBERT C.; SWARUP, VIJAY; DAUBERT, JAMES P.; DAOUD, EMILE G.; DAY, JOHN D.; ELLENBOGEN, KENNETH A.; HUMMEL, JOHN D.; BAYKANER, TINA; KRUMMEN, DAVID E.; NARAYAN, SANJIV M.; REDDY, VIVEK Y.; SHIVKUMAR, KALYANAM; STEINBERG, JONATHAN S.; WHEELAN, KEVIN R.

    2014-01-01

    Introduction The success of pulmonary vein isolation (PVI) for atrial fibrillation (AF) may be improved if stable AF sources identified by Focal Impulse and Rotor Mapping (FIRM) are also eliminated. The long-term results of this approach are unclear outside the centers where FIRM was developed; thus, we assessed outcomes of FIRM-guided AF ablation in the first cases at 10 experienced centers. Methods We prospectively enrolled n = 78 consecutive patients (61 ± 10 years) undergoing FIRM guided ablation for persistent (n = 48), longstanding persistent (n = 7), or paroxysmal (n = 23) AF. AF recordings from both atria with a 64-pole basket catheter were analyzed using a novel mapping system (Rhythm View™; Topera Inc., CA, USA). Identified rotors/focal sources were ablated, followed by PVI. Results Each institution recruited a median of 6 patients, each of whom showed 2.3 ± 0.9 AF rotors/focal sources in diverse locations. 25.3% of all sources were right atrial (RA), and 50.0% of patients had ≥1 RA source. Ablation of all sources required a total of 16.6 ± 11.7 minutes, followed by PVI. On >1 year follow-up with a 3-month blanking period, 1 patient lost to follow-up (median time to 1st recurrence: 245 days, IQR 145–354), single-procedure freedom from AF was 87.5% (patients without prior ablation; 35/40) and 80.5% (all patients; 62/77) and similar for persistent and paroxysmal AF (P = 0.89). Conclusions Elimination of patient-specific AF rotors/focal sources produced freedom-from-AF of ≈80% at 1 year at centers new to FIRM. FIRM-guided ablation has a rapid learning curve, yielding similar results to original FIRM reports in each center’s first cases. PMID:24948520

  18. Gender, Race, and Health Insurance Status in Patients Undergoing Catheter Ablation for Atrial Fibrillation.

    PubMed

    Patel, Nileshkumar; Deshmukh, Abhishek; Thakkar, Badal; Coffey, James O; Agnihotri, Kanishk; Patel, Achint; Ainani, Nitesh; Nalluri, Nikhil; Patel, Nilay; Patel, Nish; Patel, Neil; Badheka, Apurva O; Kowalski, Marcin; Hendel, Robert; Viles-Gonzalez, Juan; Noseworthy, Peter A; Asirvatham, Samuel; Lo, Kaming; Myerburg, Robert J; Mitrani, Raul D

    2016-04-01

    Catheter ablation for atrial fibrillation (AF) has emerged as a popular procedure. The purpose of this study was to examine whether there exist differences or disparities in ablation utilization across gender, socioeconomic class, insurance, or race. Using the Nationwide Inpatient Sample (2000 to 2012), we identified adults hospitalized with a principal diagnosis of AF by ICD 9 code 427.31 who had catheter ablation (ICD 9 code-37.34). We stratified patients by race, insurance status, age, gender, and hospital characteristics. A hierarchical multivariate mixed-effect model was created to identify the independent predictors of AF ablation. Among an estimated total of 3,508,122 patients (extrapolated from 20% Nationwide Inpatient Sample) hospitalized with a diagnosis of AF in the United States from the year 2000 to 2012, 102,469 patients (2.9%) underwent catheter ablations. The number of ablations was increased by 940%, from 1,439 in 2000 to 15,090 in 2012. There were significant differences according to gender, race, and health insurance status, which persisted even after adjustment for other risk factors. Female gender (0.83 [95% CI 0.79 to 0.87; p <0.001]), black (0.49 [95% CI 0.44 to 0.55; p <0.001]), and Hispanic race (0.64 [95% CI 0.56 to 0.72; p <0.001]) were associated with lower likelihoods of undergoing an AF ablation. Medicare (0.93, 0.88 to 0.98, <0.001) or Medicaid (0.67, 0.59 to 0.76, <0.001) coverage and uninsured patients (0.55, 0.49 to 0.62, <0.001) also had lower rates of AF ablation compared to patients with private insurance. In conclusion we found differences in utilization of catheter ablation for AF based on gender, race, and insurance status that persisted over time. PMID:26899494

  19. Navigation for fluoroscopy-guided cryo-balloon ablation procedures of atrial fibrillation

    NASA Astrophysics Data System (ADS)

    Bourier, Felix; Brost, Alexander; Kleinoeder, Andreas; Kurzendorfer, Tanja; Koch, Martin; Kiraly, Attila; Schneider, Hans-Juergen; Hornegger, Joachim; Strobel, Norbert; Kurzidim, Klaus

    2012-02-01

    Atrial fibrillation (AFib), the most common arrhythmia, has been identified as a major cause of stroke. The current standard in interventional treatment of AFib is the pulmonary vein isolation (PVI). PVI is guided by fluoroscopy or non-fluoroscopic electro-anatomic mapping systems (EAMS). Either classic point-to-point radio-frequency (RF)- catheter ablation or so-called single-shot-devices like cryo-balloons are used to achieve electrically isolation of the pulmonary veins and the left atrium (LA). Fluoroscopy-based systems render overlay images from pre-operative 3-D data sets which are then merged with fluoroscopic imaging, thereby adding detailed 3-D information to conventional fluoroscopy. EAMS provide tracking and visualization of RF catheters by means of electro-magnetic tracking. Unfortunately, current navigation systems, fluoroscopy-based or EAMS, do not provide tools to localize and visualize single shot devices like cryo-balloon catheters in 3-D. We present a prototype software for fluoroscopy-guided ablation procedures that is capable of superimposing 3-D datasets as well as reconstructing cyro-balloon catheters in 3-D. The 3-D cyro-balloon reconstruction was evaluated on 9 clinical data sets, yielded a reprojected 2-D error of 1.72 mm +/- 1.02 mm.

  20. Advances in Imaging for Atrial Fibrillation Ablation

    PubMed Central

    D'Silva, Andrew; Wright, Matthew

    2011-01-01

    Over the last fifteen years, our understanding of the pathophysiology of atrial fibrillation (AF) has paved the way for ablation to be utilized as an effective treatment option. With the aim of gaining more detailed anatomical representation, advances have been made using various imaging modalities, both before and during the ablation procedure, in planning and execution. Options have flourished from procedural fluoroscopy, electroanatomic mapping systems, preprocedural computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and combinations of these technologies. Exciting work is underway in an effort to allow the electrophysiologist to assess scar formation in real time. One advantage would be to lessen the learning curve for what are very complex procedures. The hope of these developments is to improve the likelihood of a successful ablation procedure and to allow more patients access to this treatment. PMID:22091384

  1. Common Genetic Variants and Response to Atrial Fibrillation Ablation

    PubMed Central

    Shoemaker, M. Benjamin; Bollmann, Andreas; Lubitz, Steven A.; Ueberham, Laura; Saini, Harsimran; Montgomery, Jay; Edwards, Todd; Yoneda, Zachary; Sinner, Moritz F.; Arya, Arash; Sommer, Philipp; Delaney, Jessica; Goyal, Sandeep K.; Saavedra, Pablo; Kanagasundram, Arvindh; Whalen, S. Patrick; Roden, Dan M.; Hindricks, Gerhard; Ellis, Christopher R.; Ellinor, Patrick T.; Darbar, Dawood; Husser, Daniela

    2016-01-01

    Background Common single nucleotide polymorphisms (SNPs) at chromosomes 4q25 (rs2200733, rs10033464 near PITX2), 1q21 (rs13376333 in KCNN3), and 16q22 (rs7193343 in ZFHX3) have consistently been associated with the risk of atrial fibrillation (AF). Single-center studies have shown that 4q25 risk alleles predict recurrence of AF after catheter ablation of AF. Here, we performed a meta-analysis to test the hypothesis that these 4 AF susceptibility SNPs modulate response to AF ablation. Methods and Results Patients underwent de novo AF ablation between 2008 and 2012 at Vanderbilt University, the Heart Center Leipzig, and Massachusetts General Hospital. The primary outcome was 12-month recurrence, defined as an episode of AF, atrial flutter, or atrial tachycardia lasting >30 seconds after a 3-month blanking period. Multivariable analysis of the individual cohorts using a Cox proportional hazards model was performed. Summary statistics from the 3 centers were analyzed using fixed effects meta-analysis. A total of 991 patients were included (Vanderbilt University, 245; Heart Center Leipzig, 659; and Massachusetts General Hospital, 87). The overall single procedure 12-month recurrence rate was 42%. The overall risk allele frequency for these SNPs ranged from 12% to 35%. Using a dominant genetic model, the 4q25 SNP, rs2200733, predicted a 1.4-fold increased risk of recurrence (adjusted hazard ratio, 1.3 [95% confidence intervals, 1.1–1.6]; P=0.011). The remaining SNPs, rs10033464 (4q25), rs13376333 (1q21), and rs7193343 (16q22) were not significantly associated with recurrence. Conclusions Among the 3 genetic loci most strongly associated with AF, the chromosome 4q25 SNP rs2200733 is significantly associated with recurrence of atrial arrhythmias after catheter ablation for AF. PMID:25684755

  2. Long-term efficacy of surgical ablation of atrial fibrillation in a low-volume centre

    PubMed Central

    Zyśko, Dorota; Bielicki, Grzegorz; Obremska, Marta; Goździk, Anna; Kustrzycki, Wojciech

    2015-01-01

    Surgical ablation is a recommended procedure for patients with atrial fibrillation (AF) undergoing a cardiac surgery operation. However, the procedure is associated with significant risk of late recurrence of AF. The aim of the study was to assess the long-term efficacy of the procedure with respect to the comorbidities. The study group consisted of 22 patients: 9 women and 13 men, who underwent surgical AF ablation in the 2008-2013 period. The patients were interviewed by telephone and were asked to send their recently performed 12-lead electrocardiography (ECG). The semi-structured interview consisted of 25 items regarding the history of AF, concomitant comorbidities, lifelong syncopal history, smoking, family history of premature cardiovascular diseases, and current medical treatment. Furthermore, the Epworth test was performed to measure the daytime sleepiness, which in turn is related to the presence of obstructive sleep apnoea. On the basis of the obtained data, the CHADS2, and Epworth scale scores were calculated for each patient. As a result of the study six patients (27%) had sinus rhythm or paced dual chamber rhythm, and 16 patients had atrial fibrillation. The multivariate analysis revealed that Epworth scale scoring > 9, CHADS2 score > 0, and persistent type of AF were related to poor outcome of surgical ablation procedure. In conclusion, patients with AF treated with surgical ablation have similar prognosis of sinus rhythm maintenance to those treated with radiofrequency ablation. Moreover, the same predisposing factors play a significant role in AF recurrence both in surgical patients and in patients treated with radiofrequency ablation. PMID:26855645

  3. Radiation exposure to operator and patients during cardiac electrophysiology study, radiofrequency catheter ablation and cardiac device implantation procedures

    NASA Astrophysics Data System (ADS)

    Lee, C. H.; Cho, J. H.; Park, S. J.; Kim, J. S.; On, Y. K.; Huh, J.

    2015-10-01

    The purpose of this study was to measure the radiation exposure to operator and patient during cardiac electrophysiology study, radiofrequency catheter ablation and cardiac device implantation procedures and to calculate the allowable number of cases per year. We carried out 9 electrophysiology studies, 40 radiofrequency catheter ablation and 11 cardiac device implantation procedures. To measure occupational radiation dose and dose-area product (DAP), 13 photoluminescence glass dosimeters were placed at eyes (inside and outside lead glass), thyroids (inside and outside thyroid collar), chest (inside and outside lead apron), wrists, genital of the operator (inside lead apron), and 6 of photoluminescence glass dosimeters were placed at eyes, thyroids, chest and genital of the patient. Exposure time and DAP values were 11.7 ± 11.8 min and 23.2 ± 26.2 Gy cm2 for electrophysiology study; 36.5 ± 42.1 min and 822.4 ± 125.5 Gy cm2 for radiofrequency catheter ablation; 16.2 ± 9.3 min and 27.8 ± 16.5 Gy cm2 for cardiac device implantation procedure, prospectively. 4591 electrophysiology studies can be conducted within the occupational exposure limit for the eyes (150 mSv), and 658-electrophysiology studies with radiofrequency catheter ablation can be carried out within the occupational exposure limit for the hands (500 mSv). 1654 cardiac device implantation procedure can be conducted within the occupational exposure limit for the eyes (150 mSv). The amounts of the operator and patient's radiation exposure were comparatively small. So, electrophysiology study, radio frequency catheter ablation and cardiac device implantation procedures are safe when performed with modern equipment and optimized protective radiation protect equipment.

  4. Personnel, equipment, and facilities for electrophysiological and catheter ablation procedures in Europe: results of the European Heart Rhythm Association Survey.

    PubMed

    Estner, Heidi L; Chen, Jian; Potpara, Tatjana; Proclemer, Alessandro; Todd, Derick; Blomström-Lundqvist, Carina

    2014-07-01

    Clinical electrophysiology (EP) and catheter ablation of arrhythmias are rapidly evolving in recent years. More than 50 000 catheter ablations are performed every year in Europe. Emerging indications, an increasing number of procedures, and an expected high quality require national and international standards as well as trained specialists. The purpose of this European Heart Rhythm Association (EHRA) survey was to assess the practice of requirements for EP personnel, equipment, and facilities in Europe. Responses to the questionnaire were received from 52 members of the EHRA research network. The survey involved high-, medium-, and low-volume EP centres, performing >400, 100-399, and under 100 implants per year, respectively. The following topics were explored: (i) EP personnel issues including balance between female and male operators, responsibilities within the EP department, age profiles, role and training of fellows, and EP nurses, (ii) the equipments available in the EP laboratories, (iii) source of patient referrals, and (iv) techniques used for ablation for different procedures including sedation, and peri-procedural use of anticoagulation and antibiotics. The survey reflects the current EP personnel situation characterized by a high training requirement and specialization. Arrhythmia sections are still most often part of cardiology departments and the head of cardiology is seldom a heart rhythm specialist. Currently, the vast majority of EP physicians are men, although in the subgroup of physicians younger than 40 years, the proportion of women is increasing. Uncertainty exists regarding peri-procedural anticoagulation, antibiotic prophylaxis, and the need for sedation during specific procedures. PMID:24966009

  5. Adjusted Left Atrial Emptying Fraction as a Predictor of Procedural Outcome after Catheter Ablation for Atrial Fibrillation

    PubMed Central

    Im, Sung Il; Kim, Sun Won; Choi, Cheol Ung; Kim, Jin Won; Yong, Hwan Seok; Kim, Eung Ju; Rha, Seung-Woon; Park, Chang Gyu; Seo, Hong Seog; Oh, Dong Joo; Lim, Hong Euy

    2015-01-01

    Structural remodeling of the left atrium is a risk factor for recurrent arrhythmia after catheter ablation for atrial fibrillation; however, data are sparse regarding the role of functional left atrial remodeling in predicting procedural outcomes. We evaluated whether left atrial transport function could be used to predict recurrent atrial fibrillation. From July 2008 through August 2010, we enrolled 202 consecutive patients who underwent catheter ablation for atrial fibrillation (paroxysmal=120, persistent=82). Left atrial volumes (LAVs) were measured by means of multislice computed tomography at every 10% of the R-R interval, and measurements were adjusted for body surface area to yield the LAV index (LAVI) at baseline. The left atrial emptying fraction (LAEF) was calculated according to LAV differences. During the mean follow-up period of 10 ± 4 months after a single ablation procedure, atrial fibrillation recurred in 59 patients (paroxysmal=19, persistent=40). Multivariate analysis revealed that persistent atrial fibrillation, early mitral inflow velocity, LAVImax, LAVImin, LAEF, LAVImax/LAEF, and LAVImin/LAEF were all independent predictors of atrial fibrillation, but the best predictor was LAVImin/LAEF (β=1.329, P=0.001). The cutoff value was 1.61 (mL/m2)/%, and the sensitivity and specificity were 74.6% and 62.2%, respectively (area under the curve=0.761). Our study shows that adjusted left atrial emptying fraction with use of multislice computed tomography might be a useful, noninvasive method to select patients for ablation. PMID:26175632

  6. Real-time circumferential mapping catheter tracking for motion compensation in atrial fibrillation ablation procedures

    NASA Astrophysics Data System (ADS)

    Brost, Alexander; Bourier, Felix; Wimmer, Andreas; Koch, Martin; Kiraly, Atilla; Liao, Rui; Kurzidim, Klaus; Hornegger, Joachim; Strobel, Norbert

    2012-02-01

    Atrial fibrillation (AFib) has been identified as a major cause of stroke. Radiofrequency catheter ablation has become an increasingly important treatment option, especially when drug therapy fails. Navigation under X-ray can be enhanced by using augmented fluoroscopy. It renders overlay images from pre-operative 3-D data sets which are then fused with X-ray images to provide more details about the underlying soft-tissue anatomy. Unfortunately, these fluoroscopic overlay images are compromised by respiratory and cardiac motion. Various methods to deal with motion have been proposed. To meet clinical demands, they have to be fast. Methods providing a processing frame rate of 3 frames-per-second (fps) are considered suitable for interventional electrophysiology catheter procedures if an acquisition frame rate of 2 fps is used. Unfortunately, when working at a processing rate of 3 fps, the delay until the actual motion compensated image can be displayed is about 300 ms. More recent algorithms can achieve frame rates of up to 20 fps, which reduces the lag to 50 ms. By using a novel approach involving a 3-D catheter model, catheter segmentation and a distance transform, we can speed up motion compensation to 25 fps which results in a display delay of only 40 ms on a standard workstation for medical applications. Our method uses a constrained 2-D/3-D registration to perform catheter tracking, and it obtained a 2-D tracking error of 0.61 mm.

  7. Ablation of chronic total occlusions using kilohertz-frequency mechanical vibrations in minimally invasive angioplasty procedures.

    PubMed

    McGuinness, G B; Wylie, M P; Gavin, G P

    2010-01-01

    Certain minimally invasive cardiology procedures, such as balloon angioplasty and stent implantation, critically require that the site of an arterial blockage be crossed by an intraluminal guidewire. Plaques resulting in near or totally occluded arteries are known as chronic total occlusions, and crossing them with conventional guidewires is a significant challenge. Among the most promising proposed solutions is the delivery of high-power, low-frequency ultrasonic vibrations to the occlusion site via an intraluminal wire waveguide. The vibrating distal tip of the ultrasound wire waveguide is used to transmit energy to the surrounding plaques, tissues, and fluids to ablate or weaken atherosclerotic plaque. Potential mechanisms of interaction with the plaque and adjacent fluids identified in the literature include: (i) direct contact with the waveguide distal tip, (ii) subcavitational acoustic fluid pressure fluctuations, (iii) cavitation, and (iv) acoustic streaming. We summarize developments in this area over more than two decades, describing experimental methods for device performance characterization, preclinical tests, early clinical investigations, and, later, full clinical trials. The article also reviews theoretical foundations and numerical models suitable for device design and analysis. Finally, important issues for future research and for the development of this technology will be considered. PMID:21303322

  8. Anesthetic management in atrial fibrillation ablation procedure: Adding non-invasive ventilation to deep sedation.

    PubMed

    Sbrana, Francesco; Ripoli, Andrea; Formichi, Bruno

    2015-01-01

    Anesthetic management of patients undergoing pulmonary vein isolation for atrial fibrillation has specific requirements. The feasibility of non-invasive ventilation (NIV) added to deep sedation procedure was evaluated. Seventy-two patients who underwent ablation procedure were retrospectively revised, performed with (57%) or without (43%) application of NIV (Respironic(®) latex-free total face mask connected to Garbin ventilator-Linde Inc.) during deep sedation (Midazolam 0.01-0.02 mg/kg, fentanyl 2.5-5 μg/kg and propofol: bolus dose 1-1.5 mg/kg, maintenance 2-4 mg/kg/h). In the two groups (NIV vs deep sedation), differences were detected in intraprocedural (pH 7.37 ± 0.05 vs 7.32 ± 0.05, p = 0.001; PaO2 117.10 ± 27.25 vs 148.17 ± 45.29, p = 0.004; PaCO2 43.37 ± 6.91 vs 49.33 ± 7.34, p = 0.002) and in percentage variation with respect to basal values (pH -0.52 ± 0.83 vs -1.44 ± 0.87, p = 0.002; PaCO2 7.21 ± 15.55 vs 34.91 ± 25.76, p = 0.001) of arterial blood gas parameters. Two episodes of respiratory complications, treated with application of NIV, were reported in deep sedation procedure. Endotracheal intubation was not necessary in any case. Adverse events related to electrophysiological procedures and recurrence of atrial fibrillation were recorded, respectively, in 36% and 29% of cases. NIV proved to be feasible in this context and maintained better respiratory homeostasis and better arterial blood gas balance when added to deep sedation. PMID:26937093

  9. Three-dimensional quantitative assessment of ablation margins based on registration of pre- and post-procedural MRI and distance map

    PubMed Central

    Tani, Soichiro; Tatli, Servet; Hata, Nobuhiko; Garcia-Rojas, Xavier; Olubiyi, Olutayo I.; Silverman, Stuart G.; Tokuda, Junichi

    2016-01-01

    Purpose Contrast-enhanced MR images are widely used to confirm the adequacy of ablation margin after liver ablation for early prediction of local recurrence. However, quantitative assessment of the ablation margin by comparing pre- and post-procedural images remains challenging. We developed and tested a novel method for three-dimensional quantitative assessment of ablation margin based on non-rigid image registration and 3D distance map. Methods Our method was tested with pre- and post-procedural MR images acquired in 21 patients who underwent image-guided percutaneous liver ablation. The two images were co-registered using non-rigid intensity-based registration. After the tumor and ablation volumes were segmented, target volume coverage, percent of tumor coverage, and Dice Similarity Coefficient were calculated as metrics representing overall adequacy of ablation. In addition, 3D distance map around the tumor was computed and superimposed on the ablation volume to identify the area with insufficient margins. For patients with local recurrences, the follow-up images were registered to the post-procedural image. Three-D minimum distance between the recurrence and the areas with insufficient margins were quantified. Results The percent tumor coverage for all non-recurrent cases was 100%. Five cases had tumor recurrences, and the 3D distance map revealed insufficient tumor coverage or a 0-millimeter margin. It also showed that two recurrences were remote to the insufficient margin. Conclusions Non-rigid registration and 3D distance map allows us to quantitatively evaluate the adequacy of the ablation margin after percutaneous liver ablation. The method may be useful to predict local recurrences immediately following ablation procedure. PMID:27038962

  10. Demographic Differences in Catheter Ablation After Hospital Presentation With Symptomatic Atrial Fibrillation

    PubMed Central

    Kummer, Benjamin R; Bhave, Prashant D; Merkler, Alexander E; Gialdini, Gino; Okin, Peter M; Kamel, Hooman

    2015-01-01

    Background Catheter ablation is increasingly used for rhythm control in symptomatic atrial fibrillation (AF), but the demographic characteristics of patients undergoing this procedure are unclear. Methods and Results We used data on all admissions at nonfederal acute care hospitals in California, Florida, and New York to identify patients discharged with a primary diagnosis of AF between 2006 and 2011. Our primary outcome was readmission for catheter ablation of AF, identified using validated International Classification of Diseases, Ninth Revision, Clinical Modification procedure codes. Cox regression models were used to assess relationships between demographic characteristics and catheter ablation, adjusting for Elixhauser comorbidities. We identified 397 612 eligible patients. Of these, 16 717 (4.20%, 95% CI 0.41 to 0.43) underwent ablation. These patients were significantly younger, more often male, more often white, and more often privately insured, with higher household incomes and lower rates of medical comorbidity. In Cox regression models, the likelihood of ablation was lower in women than men (hazard ratio [HR] 0.83; 95% CI 0.80 to 0.86) despite higher rates of AF-related rehospitalization (HR 1.23; 95% CI 1.21 to 1.24). Compared to whites, the likelihood of ablation was lower in Hispanics (HR 0.60; 95% CI 0.56 to 0.64) and blacks (HR 0.68; 95% CI 0.64 to 0.73), even though blacks had only a slightly lower likelihood of AF-related rehospitalization (HR 0.97; 95% CI 0.94 to 0.99) and a higher likelihood of all-cause hospitalization (HR 1.38; 95% CI 1.37 to 1.39). Essentially the same pattern existed in Hispanics. Conclusions We found differences in use of catheter ablation for symptomatic AF according to sex and race despite adjustment for available data on demographic characteristics and medical comorbidities. PMID:26396201

  11. Predictive value of various Doppler-derived parameters of atrial conduction time for successful atrial fibrillation ablation

    PubMed Central

    Valtuille, Lucas; Choy, Jonathan B; Becher, Harald

    2015-01-01

    Various Doppler-derived parameters of left atrial electrical remodeling have been demonstrated to predict recurrence of atrial fibrillation (AF) after AF ablation. The aim of this study was to compare three Doppler-derived measures of atrial conduction time in patients undergoing AF ablation, and to investigate their predictive value for successful procedure. In 32 prospectively enrolled patients undergoing the first AF ablation, atrial conduction time was estimated by measuring the time delay between the onset of P-wave on the surface ECG to the peak of the a′-wave on the pulsed-wave Doppler and color-coded tissue Doppler imaging of the left atrial lateral wall, and to the peak of the A-wave on the pulsed-wave Doppler of the mitral inflow. There was a significant difference in the baseline atrial conduction time measured by different echocardiographic techniques. Most (88%) patients had normal or only mildly dilated left atrium. At 6 months, 12 patients (38%) had recurrent AF/atrial tachycardia. The duration of history of AF was the only predictor of AF/atrial tachycardia recurrence following the first AF ablation (P=0.024; OR 1.023, CI 1.003–1.044). A combination of normal left atrial volume and history of paroxysmal AF of ≤48 months was associated with the best outcome. Predictive value of the Doppler derived parameters of atrial conduction time may be reduced in the early stages of left atrial remodeling. Future studies may determine which echocardiographic parameter correlates best with the extent of left atrial remodeling and is most predictive of successful AF ablation. PMID:26795694

  12. Cost Analysis of Periprocedural Imaging in Patients Undergoing Catheter Ablation for Atrial Fibrillation

    PubMed Central

    Pokorney, Sean D.; Hammill, Bradley G.; Qualls, Laura G.; Steinberg, Benjamin A.; Curtis, Lesley H.; Piccini, Jonathan P.

    2014-01-01

    Cardiovascular imaging is an important part of procedural planning and safety for catheter ablation of atrial fibrillation (AF). However, the costs of imaging surrounding catheter ablation of AF have not been described. Medicare fee-for-service data were used to evaluate Medicare expenditures before, during, and after catheter ablation for AF from July 2007 to December 2009. Among 11,525 patients who underwent catheter ablation for AF, the mean overall expenditure on the day of the procedure was $14,455 (SD $7,441). The mean imaging expenditure in the periprocedural period, which included the 30 days before the catheter ablation and the day of the ablation itself, was $884 (SD $455). Periprocedural imaging expenditures varied by the imaging strategy used, ranging from a mean of $557 (SD $269) for patients with electroanatomic mapping only to $1,234 (SD $461) for patients with electroanatomic mapping, transesophageal echocardiogram, and computed tomography or magnetic resonance imaging. Mean patient-level imaging expenditures varied by provider (mean $872, SD $249). Periprocedural imaging expenditures also varied by patient risk, with mean expenditures of $862 (SD $444) for patients with a CHADS2 score of ≥2 compared with $907 (SD $466) for CHADS2 score <2 (p <0.001). In conclusion, peri-procedural imaging accounts for approximately 6% of mean Medicare expenditures for catheter ablation of AF. The expenditures for periprocedural imaging vary both at the patient and at the provider level and they are inversely related to stroke risk by CHADS2 score. PMID:24952929

  13. Surgical ablation devices for atrial fibrillation.

    PubMed

    Lall, Shelly C; Damiano, Ralph J

    2007-12-01

    The introduction of ablation technology has revolutionized the surgical treatment of atrial fibrillation (AF). It has greatly simplified surgical approaches and has significantly increased the number of procedures being performed. Various energy sources have been used clinically, including cryoablation, radiofrequency, microwave, laser, and high-frequency ultrasound. The goal of these devices is to create conduction block to either block activation wavefronts or to isolate the triggers of AF. All present devices have been shown to have clinical efficacy in some patients. The devices each have their unique advantages and disadvantages. It is important that surgeons develop accurate dose-response curves for new devices in clinically relevant models on both the arrested and beating heart. This will allow the appropriate use of technology to facilitate AF surgery. PMID:18175210

  14. 4:2:1 conduction of an AF initiating trigger

    PubMed Central

    Kojodjojo, Pipin; Chong, Eric; Lim, Toon Wei; Seow, Swee Chong

    2015-01-01

    A 44 year old male with idiopathic dilated cardiomyopathy was undergoing persistent atrial fibrillation (AF) ablation. Following antral ablation, AF terminated into a regular narrow complex rhythm. Earliest activation was mapped to a focus in the superior vena cava (SVC) which was conducted in a 2:1 ratio to the atria which in turn was conducted with 2:1 ratio to the ventricles, resulting in an unusual 4:2:1 conduction of the SVC tachycardia. 1:1 conduction of the SVC tachycardia to the atrium preceded initiation of AF. During AF, SVC tachycardia continued unperturbed. Sinus rhythm was restored following catheter ablation of the focus. PMID:27134438

  15. Silent cerebral events/lesions related to atrial fibrillation ablation: a clinical review.

    PubMed

    Deneke, Thomas; Jais, Pierre; Scaglione, Marco; Schmitt, Rainer; DI Biase, Luigi; Christopoulos, Georgios; Schade, Anja; Mügge, Andreas; Bansmann, Martin; Nentwich, Karin; Müller, Patrick; Krug, Joachim; Roos, Markus; Halbfass, Phillip; Natale, Andrea; Gaita, Fiorenzo; Haines, David

    2015-04-01

    Brain magnetic resonance imaging (MRI) has identified a high incidence of cerebral ischemia in asymptomatic patients after atrial fibrillation (AF) ablation (silent). Detection of cerebral ischemic events on MRI is based on acute hyperintense lesions on diffusion-weighted imaging. In the literature, the incidence is related to specifications of MRI and depends on the definition applied. In comparative studies, silent cerebral events (SCE, diffusion-weighted MRI [DWI] positive only) appear to be approximately 3 times more common compared to using a definition of silent cerebral lesions (SCL; without fluid attenuated inverse recovery sequence [FLAIR] positivity). Whereas the FLAIR sequence may turn positive within days after the ischemic event, SCE definition is highly sensitive for early phases of ischemic brain damage. SCE/SCL appear to represent cerebral ischemic infarcts and determine the "embolic fingerprint" of a specific ablation technology and strategy used. The optimum time point for detecting SCE is early after AF ablation (24-72 hours), whereas detection of SCL can only be performed within the first 2-7 days (due to delay of FLAIR positivity). Different technology-, procedure-, and patient-related parameters have been identified to play a role in the multifactorial genesis of SCE/SCL. In recent years, evidence has been gathered that there may be differences of SCE/SCL rates depending upon the ablation technology used, but small patient numbers and a large number of potential confounders hamper all studies. As major findings of recent studies, mode of periprocedural and intraprocedural anticoagulation has been identified as a major predictor for incidences of SCE/SCL. Whereas procedural characteristics related to higher SCE/SCL-rates may be modified, unchangeable patient-related factors should be taken into account for future individualized risk assessment. Novel ablation devices introduced into the market should be tested for their potential embolic

  16. Impact of Additional Transthoracic Electrical Cardioversion on Cardiac Function and Atrial Fibrillation Recurrence in Patients with Persistent Atrial Fibrillation Who Underwent Radiofrequency Catheter Ablation

    PubMed Central

    Wang, Deguo; Zhang, Fengxiang; Wang, Ancai

    2016-01-01

    Backgrounds and Objective. During the procession of radiofrequency catheter ablation (RFCA) in persistent atrial fibrillation (AF), transthoracic electrical cardioversion (ECV) is required to terminate AF. The purpose of this study was to determine the impact of additional ECV on cardiac function and recurrence of AF. Methods and Results. Persistent AF patients received extensive encircling pulmonary vein isolation (PVI) and additional line ablation. Patients were divided into two groups based on whether they need transthoracic electrical cardioversion to terminate AF: electrical cardioversion (ECV group) and nonelectrical cardioversion (NECV group). Among 111 subjects, 35 patients were returned to sinus rhythm after ablation by ECV (ECV group) and 76 patients had AF termination after the ablation processions (NECV group). During the 12-month follow-ups, the recurrence ratio of patients was comparable in ECV group (15/35) and NECV group (34/76) (44.14% versus 44.74%, P = 0.853). Although left atrial diameters (LAD) decreased significantly in both groups, there were no significant differences in LAD and left ventricular cardiac function between ECV group and NECV group. Conclusions. This study revealed that ECV has no significant impact on the maintenance of SR and the recovery of cardiac function. Therefore, ECV could be applied safely to recover SR during the procedure of catheter ablation of persistent atrial fibrillation. PMID:27022500

  17. Noninvasive mapping to guide atrial fibrillation ablation.

    PubMed

    Lim, Han S; Zellerhoff, Stephan; Derval, Nicolas; Denis, Arnaud; Yamashita, Seigo; Berte, Benjamin; Mahida, Saagar; Hooks, Darren; Aljefairi, Nora; Shah, Ashok J; Sacher, Frédéric; Hocini, Meleze; Jais, Pierre; Haissaguerre, Michel

    2015-03-01

    Atrial fibrillation (AF) is a dynamic rhythm. Noninvasive mapping overcomes many previous barriers to mapping such a dynamic rhythm, by providing a beat-to-beat, biatrial, panoramic view of the AF process. Catheter ablation of AF drivers guided by noninvasive mapping has yielded promising clinical results and has advanced understanding of the underlying pathophysiologic processes of this common heart rhythm disorder. PMID:25784025

  18. Accidental Entrapment of Electrical Mapping Catheter by Chiari's Network in Right Atrium during Catheter Ablation Procedure

    PubMed Central

    Sakamoto, Atsushi; Urushida, Tsuyoshi; Sakakibara, Tomoaki; Sano, Makoto; Suwa, Kenichiro; Saitoh, Takeji; Saotome, Masao; Katoh, Hideki; Satoh, Hiroshi; Hayashi, Hideharu

    2016-01-01

    A 78-year-old male was admitted to our hospital due to frequent palpitation. His electrocardiogram (ECG) presented regular narrow QRS tachycardia with 170 bpm, and catheter ablation was planned. During electroanatomical mapping of the right atrium (RA) with a multiloop mapping catheter, the catheter head was entrapped nearby the ostium of inferior vena cava. Rotation and traction of the catheter failed to detach the catheter head from the RA wall. Exfoliation of connective tissue twined around catheter tip by forceps, which were designed for endomyocardial biopsy, succeeded to retract and remove the catheter. Postprocedural echocardiography and pathologic examination proved the existence of Chiari's network. The handling of complex catheters in the RA has a potential risk of entrapment with Chiari's network. PMID:27366332

  19. Novel Balloon Catheter Device with Pacing, Ablating, Electroporation, and Drug Eluting Capabilities for Atrial Fibrillation Treatment – Preliminary Efficacy and Safety Studies in a Canine Model

    PubMed Central

    DeSimone, Christopher V.; Ebrille, Elisa; Syed, Faisal F.; Mikell, Susan B.; Suddendorf, Scott H.; Wahnschaffe, Douglas; Ladewig, Dorothy J.; Gilles, Emily J.; Danielsen, Andrew J.; Holmes, David R.; Asirvatham, Samuel J.

    2015-01-01

    Pulmonary vein isolation is an established therapeutic procedure for symptomatic atrial fibrillation (AF). This approach involves ablation of atrial tissue just outside of the pulmonary veins. However, patient outcomes are limited by a high rate of arrhythmia recurrence. Ablation of electrically active tissue inside the pulmonary vein may improve procedural success, but is currently avoided due to the complication of post-ablation stenosis. An innovative device that can ablate inside pulmonary veins and prevent stenosis is a viable strategy to increase long-term efficacy. We have developed a prototypical balloon catheter device and have demonstrated its functionality in four acute canine experiments. Further optimization of this device may provide an innovative means to simultaneously a blate and prevent pulmonary vein stenosis for improved AF treatment in humans. PMID:25092516

  20. Cone-Beam Computed Tomography (CBCT) Versus CT in Lung Ablation Procedure: Which is Faster?

    SciTech Connect

    Cazzato, Roberto Luigi Battistuzzi, Jean-Benoit Catena, Vittorio; Grasso, Rosario Francesco Zobel, Bruno Beomonte; Schena, Emiliano; Buy, Xavier Palussiere, Jean

    2015-10-15

    AimTo compare cone-beam CT (CBCT) versus computed tomography (CT) guidance in terms of time needed to target and place the radiofrequency ablation (RFA) electrode on lung tumours.Materials and MethodsPatients at our institution who received CBCT- or CT-guided RFA for primary or metastatic lung tumours were retrospectively included. Time required to target and place the RFA electrode within the lesion was registered and compared across the two groups. Lesions were stratified into three groups according to their size (<10, 10–20, >20 mm). Occurrences of electrode repositioning, repositioning time, RFA complications, and local recurrence after RFA were also reported.ResultsForty tumours (22 under CT, 18 under CBCT guidance) were treated in 27 patients (19 male, 8 female, median age 67.25 ± 9.13 years). Thirty RFA sessions (16 under CBCT and 14 under CT guidance) were performed. Multivariable linear regression analysis showed that CBCT was faster than CT to target and place the electrode within the tumour independently from its size (β = −9.45, t = −3.09, p = 0.004). Electrode repositioning was required in 10/22 (45.4 %) tumours under CT guidance and 5/18 (27.8 %) tumours under CBCT guidance. Pneumothoraces occurred in 6/14 (42.8 %) sessions under CT guidance and in 6/16 (37.5 %) sessions under CBCT guidance. Two recurrences were noted for tumours receiving CBCT-guided RFA (2/17, 11.7 %) and three after CT-guided RFA (3/19, 15.8 %).ConclusionCBCT with live 3D needle guidance is a useful technique for percutaneous lung ablation. Despite lesion size, CBCT allows faster lung RFA than CT.

  1. Ablation of Myocardial Tissue With Nanosecond Pulsed Electric Fields

    PubMed Central

    Xie, Fei; Varghese, Frency; Pakhomov, Andrei G.; Semenov, Iurii; Xiao, Shu; Philpott, Jonathan; Zemlin, Christian

    2015-01-01

    Background Ablation of cardiac tissue is an essential tool for the treatment of arrhythmias, particularly of atrial fibrillation, atrial flutter, and ventricular tachycardia. Current ablation technologies suffer from substantial recurrence rates, thermal side effects, and long procedure times. We demonstrate that ablation with nanosecond pulsed electric fields (nsPEFs) can potentially overcome these limitations. Methods We used optical mapping to monitor electrical activity in Langendorff-perfused New Zealand rabbit hearts (n = 12). We repeatedly inserted two shock electrodes, spaced 2–4 mm apart, into the ventricles (through the entire wall) and applied nanosecond pulsed electric fields (nsPEF) (5–20 kV/cm, 350 ns duration, at varying pulse numbers and frequencies) to create linear lesions of 12–18 mm length. Hearts were stained either with tetrazolium chloride (TTC) or propidium iodide (PI) to determine the extent of ablation. Some stained lesions were sectioned to obtain the three-dimensional geometry of the ablated volume. Results In all animals (12/12), we were able to create nonconducting lesions with less than 2 seconds of nsPEF application per site and minimal heating (< 0.2°C) of the tissue. The geometry of the ablated volume was smoother and more uniform throughout the wall than typical for RF ablation. The width of the lesions could be controlled up to 6 mm via the electrode spacing and the shock parameters. Conclusions Ablation with nsPEFs is a promising alternative to radiofrequency (RF) ablation of AF. It may dramatically reduce procedure times and produce more consistent lesion thickness than RF ablation. PMID:26658139

  2. Drug-Coated Balloon Venoplasty for In-Stent Restenosis in a Patient With Recurrent Pulmonary Vein Stenosis Post Ablation for Atrial Fibrillation: Initial Experience With a New Treatment Technique.

    PubMed

    Rosenberg, Jonathan; Fisher, Westby G; Guerrero, Mayra; Smart, Steve; Levisay, Justin; Feldman, Ted; Salinger, Michael

    2016-05-01

    Pulmonary vein stenosis (PVS) is an uncommon but serious complication following radiofrequency ablation for atrial fibrillation. Occurrence of this complication has risen with increased rates of ablation procedures, with >50,000 AF ablation procedures performed per year, and can occur within weeks to months post procedure. Currently, the main therapies for PVS include percutaneous interventions with balloon angioplasty and stenting, but these treatments are complicated by a high rate of restenosis. The optimal treatment for recurrent pulmonary vein in-stent restenosis has not been determined. We describe the novel use of a paclitaxel drug-coated balloon for the treatment of in-stent restenosis of the pulmonary veins. PMID:27145055

  3. Major complications of cryoballoon catheter ablation for atrial fibrillation and their management.

    PubMed

    Bhat, Tariq; Baydoun, Hassan; Asti, Deepak; Rijal, Jharendra; Teli, Sumaya; Tantray, Mohmad; Bhat, Hilal; Kowalski, Marcin

    2014-09-01

    Atrial fibrillation (AF) is the most common symptomatic and sustained cardiac arrhythmia. It affects approximately 2-3 million people in the USA alone with an increased incidence and prevalence worldwide. It is associated, in addition to worsening quality of life, with increased morbidity and mortality especially in poorly controlled AF, affecting mostly those older than 65 years of age. Radiofrequency ablation was found to be a good strategy for focal isolation of pulmonary veins triggering from the vulnerable atrial substrate but is a time-consuming procedure and carries the risk of multiple complications like tamponade which could be fatal, atrioesophageal fistula and local thrombus formation at the site of ablation. Cryoballoon ablation with pulmonary vein isolation has emerged in the past few years as a breakthrough novel technology for the treatment of drug-refractory AF. It is a relatively simple alternative for point-by-point radiofrequency ablation of paroxysmal AF and is associated with fewer incidences of fatal complications such as cardiac perforation. As experience with this new tool accumulates, the field faces new challenges in the form of rare compilations including gastroparesis, phrenic nerve palsy, atrioesophageal fistula, pulmonary vein stenosis, thromboembolism pericardial effusion, and tamponade. PMID:25115140

  4. Contact force-guided catheter ablation for the treatment of atrial fibrillation: a meta-analysis of randomized, controlled trials

    PubMed Central

    Qi, Z.; Luo, X.; Wu, B.; Shi, H.; Jin, B.; Wen, Z.

    2016-01-01

    Contact force (CF) sensing technology allows real-time monitoring during catheter ablation for atrial fibrillation (AF). However, the effect of CF sensing technology on procedural parameters and clinical outcomes still needs clarification. Because of the inconsistent results thus far in this area, we performed a meta-analysis to determine whether CF sensing technology can improve procedural parameters and clinical outcomes for the treatment of AF. Studies examining the benefits of CF sensing technology were identified in English-language articles by searching the MEDLINE, Web of Science, and Cochrane Library databases (inception to May 2015). Ten randomized, controlled trials involving 1834 patients (1263 males, 571 females) were included in the meta-analysis (681 in the CF group, 1153 in the control group). Overall, the ablation time was significantly decreased by 7.34 min (95%CI=-12.21 to -2.46; P=0.003, Z test) in the CF group compared with the control group. CF sensing technology was associated with significantly improved freedom from AF after 12 months (OR=1.55, 95%CI=1.20 to 1.99; P=0.0007) and complications were significantly lower in the CF group than in the control group (OR=0.50, 95%CI=0.29 to 0.87; P=0.01). However, fluoroscopy time analysis showed no significantly decreased trend associated with CF-guided catheter ablation (weighted mean difference: -2.59; 95%CI=-9.06 to 3.88; P=0.43). The present meta-analysis shows improvement in ablation time and freedom from AF after 12 months in AF patients treated with CF-guided catheter ablation. However, CF-guided catheter ablation does not decrease fluoroscopy time. PMID:26840711

  5. Analysis of Bipolar Radiofrequency Ablation in Treatment of Atrial Fibrillation Associated with Rheumatic Heart Disease

    PubMed Central

    Li, Yang; Wu, Zhong

    2016-01-01

    Background Among patients with rheumatic heart disease (RHD), 45% to 60% present with atrial fibrillation (AF), which is associated with increased rates of thromboembolism, heart failure, and even death. The bipolar radiofrequency ablation (BRFA) combining with mitral valve procedure has been adopted in patients of AF associated with RHD, but evaluations about its effectiveness are still limited. Methods A total of 87 patients with RHD and long persistent AF who had accepted mitral valve replacement concomitant with BRFA were studied. Clinical data were collected to analyze the midterm results of BRFA and evaluate its efficiency. Univariate and multivariate analyses were used to identify the independent factors associated with late AF recurrence. Results Sixty-six (75.9%) patients maintained sinus rhythm after a mean follow-up of 13.4 ± 5.2 months. Late AF recurrence had been detected in 21 (24.1%) patients, 11 (12.6%) patients were confirmed to be AF, 8 (9.2%) patients were atrial flutter and 2 (2.3%) patients were junctional rhythm. In Multivariate logistic regression analysis, body mass index (BMI) (OR = 1.756, 95% CI = 1.289–2.391, p = 0.000) and early AF recurrence (OR = 5.479, 95% CI = 1.189–25.254, p = 0.029) were independent predictors of late AF recurrence. In addition, left ventricular ejection fraction (LVEF) and New York Heart Association class showed a greater improvement in patients who maintained sinus rhythm than those who experienced late AF recurrence. Conclusion BRFA is an effective technique for the treatment of long persistent AF associated with RHD during mitral valve replacement. The BMI and early AF recurrence are independent predictors for late AF recurrence. Patients with long-term restoration of sinus rhythm experienced a greater improvement of left ventricular function after BRFA. PMID:26960188

  6. Persistent atrial fibrillation ablation: conventional versus driver-guided strategy.

    PubMed

    Lim, Han S; Sacher, Frédéric; Zellerhoff, Stephan; Jesel, Laurence; Shah, Ashok J; Komatsu, Yuki; Daly, Matthew; Denis, Arnaud; Derval, Nicolas; Hocini, Mélèze; Jaïs, Pierre; Haïssaguerre, Michel

    2015-01-01

    While pulmonary vein isolation for paroxysmal atrial fibrillation (AF) is highly effective, catheter ablation for persistent AF remains a challenge with varying clinical success reported. Several ablation techniques have been proposed to target persistent AF, with the additional ablation of complex fractionated electrograms and linear lesions shown to provide incremental success to pulmonary vein isolation alone. Recently, several studies have suggested the presence of localized drivers (re-entrant or focal) in AF. By targeting these drivers, clinical outcomes may be maintained while minimizing the extent of ablation. This article will focus on the conventional stepwise ablation approach for persistent AF versus driver-guided ablation with the use of newer mapping technologies. PMID:26610158

  7. Early Experience of Novel Oral Anticoagulants in Catheter Ablation for Atrial Fibrillation: Efficacy and Safety Comparison to Warfarin

    PubMed Central

    Shin, Dong Geum; Kim, Tae-Hoon; Uhm, Jae-Sun; Kim, Joung-Youn; Joung, Boyoung; Lee, Moon-Hyoung

    2016-01-01

    Purpose Compared with warfarin, novel oral anticoagulants (NOACs) are convenient to use, although they require a blanking period immediately before radiofrequency catheter ablation for atrial fibrillation (AF). We compared NOACs and uninterrupted warfarin in the peri-procedural period of AF ablation. Materials and Methods We compared 141 patients treated with peri-procedural NOACs (72% men; 58±11 years old; 71% with paroxysmal AF) and 281 age-, sex-, AF type-, and history of stroke-matched patients treated with uninterrupted warfarin. NOACs were stopped 24 hours before the procedure and restarted on the same procedure day after hemostasis was achieved. Results We found no difference in the CHA2DS2-VASc (p=0.376) and HAS-BLED scores (p=0.175) between the groups. The preprocedural anticoagulation duration was significantly shorter in the NOAC group (76.3±110.7 days) than in the warfarin group (274.7±582.7 days, p<0.001). The intra-procedural total heparin requirement was higher (p<0.001), although mean activated clotting time was shorter (350.0±25.0 s vs. 367.4±42.9 s, p<0.001), in the NOAC group than in the warfarin group. There was no significant difference in thromboembolic events (1.4% vs. 0%, p=0.111) or major bleeding (1.4% vs. 3.9%, p=0.235) between the NOAC and warfarin groups. Minor stroke occurred in two cases within 10 hours of the procedure (underlying CHA2DS2-VASc scores 0 and 1) in the NOAC group. Conclusion Pre-procedural anticoagulation duration was shorter and intra-procedural heparin requirement was higher with NOAC than with uninterrupted warfarin during AF ablation. Although the peri-procedural thromboembolism and bleeding incidences did not differ, minor stroke occurred in two cases in the NOAC group. PMID:26847285

  8. Optimization of catheter ablation of atrial fibrillation: insights gained from clinically-derived computer models.

    PubMed

    Zhao, Jichao; Kharche, Sanjay R; Hansen, Brian J; Csepe, Thomas A; Wang, Yufeng; Stiles, Martin K; Fedorov, Vadim V

    2015-01-01

    Atrial fibrillation (AF) is the most common heart rhythm disturbance, and its treatment is an increasing economic burden on the health care system. Despite recent intense clinical, experimental and basic research activity, the treatment of AF with current antiarrhythmic drugs and catheter/surgical therapies remains limited. Radiofrequency catheter ablation (RFCA) is widely used to treat patients with AF. Current clinical ablation strategies are largely based on atrial anatomy and/or substrate detected using different approaches, and they vary from one clinical center to another. The nature of clinical ablation leads to ambiguity regarding the optimal patient personalization of the therapy partly due to the fact that each empirical configuration of ablation lines made in a patient is irreversible during one ablation procedure. To investigate optimized ablation lesion line sets, in silico experimentation is an ideal solution. 3D computer models give us a unique advantage to plan and assess the effectiveness of different ablation strategies before and during RFCA. Reliability of in silico assessment is ensured by inclusion of accurate 3D atrial geometry, realistic fiber orientation, accurate fibrosis distribution and cellular kinetics; however, most of this detailed information in the current computer models is extrapolated from animal models and not from the human heart. The predictive power of computer models will increase as they are validated with human experimental and clinical data. To make the most from a computer model, one needs to develop 3D computer models based on the same functionally and structurally mapped intact human atria with high spatial resolution. The purpose of this review paper is to summarize recent developments in clinically-derived computer models and the clinical insights they provide for catheter ablation. PMID:25984605

  9. Optimization of Catheter Ablation of Atrial Fibrillation: Insights Gained from Clinically-Derived Computer Models

    PubMed Central

    Zhao, Jichao; Kharche, Sanjay R.; Hansen, Brian J.; Csepe, Thomas A.; Wang, Yufeng; Stiles, Martin K.; Fedorov, Vadim V.

    2015-01-01

    Atrial fibrillation (AF) is the most common heart rhythm disturbance, and its treatment is an increasing economic burden on the health care system. Despite recent intense clinical, experimental and basic research activity, the treatment of AF with current antiarrhythmic drugs and catheter/surgical therapies remains limited. Radiofrequency catheter ablation (RFCA) is widely used to treat patients with AF. Current clinical ablation strategies are largely based on atrial anatomy and/or substrate detected using different approaches, and they vary from one clinical center to another. The nature of clinical ablation leads to ambiguity regarding the optimal patient personalization of the therapy partly due to the fact that each empirical configuration of ablation lines made in a patient is irreversible during one ablation procedure. To investigate optimized ablation lesion line sets, in silico experimentation is an ideal solution. 3D computer models give us a unique advantage to plan and assess the effectiveness of different ablation strategies before and during RFCA. Reliability of in silico assessment is ensured by inclusion of accurate 3D atrial geometry, realistic fiber orientation, accurate fibrosis distribution and cellular kinetics; however, most of this detailed information in the current computer models is extrapolated from animal models and not from the human heart. The predictive power of computer models will increase as they are validated with human experimental and clinical data. To make the most from a computer model, one needs to develop 3D computer models based on the same functionally and structurally mapped intact human atria with high spatial resolution. The purpose of this review paper is to summarize recent developments in clinically-derived computer models and the clinical insights they provide for catheter ablation. PMID:25984605

  10. Localized reentry within the left atrial appendage: arrhythmogenic role in patients undergoing ablation of persistent atrial fibrillation

    PubMed Central

    Hocini, Mélèze; Shah, Ashok J.; Nault, Isabelle; Sanders, Prashanthan; Wright, Matthew; Narayan, Sanjiv M.; Takahashi, Yoshihide; Jaïs, Pierre; Matsuo, Seiichiro; Knecht, Sébastien; Sacher, Frédéric; Lim, Kang-Teng; Clémenty, Jacques; Haïssaguerre, Michel

    2012-01-01

    BACKGROUND Left atrial appendage (LAA) is implicated in maintenance of atrial fibrillation (AF) and atrial tachycardia (AT) associated with persistent AF (PsAF) ablation, although little is known about the incidence and mechanism of LAA AT. OBJECTIVE The purpose of this study was to characterize LAA ATs associated with PsAF ablation. METHODS In 74 consecutive patients undergoing stepwise PsAF ablation, 142 ATs were encountered during index and repeat procedures. Out of 78 focal-source ATs diagnosed by activation and entrainment mapping, 15 (19%) arose from the base of LAA. Using a 20-pole catheter, high-density maps were constructed (n = 10; age 57 ± 6 years) to characterize the mechanism of LAA-AT. The LAA orifice was divided into the posterior ridge and anterior-superior and inferior segments to characterize the location of AT. RESULTS Fifteen patients with LAA AT had symptomatic PsAF for 17 ± 15 months before ablation. LAA AT (cycle length [CL] 283 ± 30 ms) occurred during the index procedure in four and after 9 ± 7 months in 11 patients. We could map 89% ± 8% AT CLs locally with favorable entrainment from within the LAA, which is suggestive of localized reentry with centrifugal atrial activation. ATs were localized to inferior segment (n = 4), anterior-superior segment (n = 5), and posterior ridge (n = 6) with 1:1 conduction to the atria. Ablation targeting long fractionated or mid-diastolic electrogram within the LAA resulted in tachycardia termination. Postablation, selective contrast radiography demonstrated atrial synchronous LAA contraction in all but one patient. At 18 ± 7 months, 13/15 (87%) patients remained in sinus rhythm without antiarrhythmic drugs. CONCLUSION LAA is an important source of localized reentrant AT in patients with PsAF at index and repeat ablation procedures. Ablation targeting the site with long fractionated or mid-diastolic LAA electrogram is highly effective in acute and medium-term elimination of the arrhythmia. PMID

  11. Quantitative modeling of the accuracy in registering preoperative patient-specific anatomic models into left atrial cardiac ablation procedures

    SciTech Connect

    Rettmann, Maryam E. Holmes, David R.; Camp, Jon J.; Cameron, Bruce M.; Robb, Richard A.; Kwartowitz, David M.; Gunawan, Mia; Johnson, Susan B.; Packer, Douglas L.; Dalegrave, Charles; Kolasa, Mark W.

    2014-02-15

    Purpose: In cardiac ablation therapy, accurate anatomic guidance is necessary to create effective tissue lesions for elimination of left atrial fibrillation. While fluoroscopy, ultrasound, and electroanatomic maps are important guidance tools, they lack information regarding detailed patient anatomy which can be obtained from high resolution imaging techniques. For this reason, there has been significant effort in incorporating detailed, patient-specific models generated from preoperative imaging datasets into the procedure. Both clinical and animal studies have investigated registration and targeting accuracy when using preoperative models; however, the effect of various error sources on registration accuracy has not been quantitatively evaluated. Methods: Data from phantom, canine, and patient studies are used to model and evaluate registration accuracy. In the phantom studies, data are collected using a magnetically tracked catheter on a static phantom model. Monte Carlo simulation studies were run to evaluate both baseline errors as well as the effect of different sources of error that would be present in a dynamicin vivo setting. Error is simulated by varying the variance parameters on the landmark fiducial, physical target, and surface point locations in the phantom simulation studies. In vivo validation studies were undertaken in six canines in which metal clips were placed in the left atrium to serve as ground truth points. A small clinical evaluation was completed in three patients. Landmark-based and combined landmark and surface-based registration algorithms were evaluated in all studies. In the phantom and canine studies, both target registration error and point-to-surface error are used to assess accuracy. In the patient studies, no ground truth is available and registration accuracy is quantified using point-to-surface error only. Results: The phantom simulation studies demonstrated that combined landmark and surface-based registration improved

  12. Post-procedural evaluation of catheter contact force characteristics

    NASA Astrophysics Data System (ADS)

    Koch, Martin; Brost, Alexander; Kiraly, Atilla; Strobel, Norbert; Hornegger, Joachim

    2012-03-01

    Minimally invasive catheter ablation of electric foci, performed in electrophysiology labs, is an attractive treatment option for atrial fibrillation (AF) - in particular if drug therapy is no longer effective or tolerated. There are different strategies to eliminate the electric foci inducing the arrhythmia. Independent of the particular strategy, it is essential to place transmural lesions. The impact of catheter contact force on the generated lesion quality has been investigated recently, and first results are promising. There are different approaches to measure catheter-tissue contact. Besides traditional haptic feedback, there are new technologies either relying on catheter tip-to-tissue contact force or on local impedance measurements at the tip of the catheter. In this paper, we present a novel tool for post-procedural ablation point evaluation and visualization of contact force characteristics. Our method is based on localizing ablation points set during AF ablation procedures. The 3-D point positions are stored together with lesion specific catheter contact force (CF) values recorded during the ablation. The force records are mapped to the spatial 3-D positions, where the energy has been applied. The tracked positions of the ablation points can be further used to generate a 3-D mesh model of the left atrium (LA). Since our approach facilitates visualization of different force characteristics for post-procedural evaluation and verification, it has the potential to improve outcome by highlighting areas where lesion quality may be less than desired.

  13. Reduction of Fluoroscopy Time and Radiation Dosage During Catheter Ablation for Atrial Fibrillation

    PubMed Central

    Aldhoon, Bashar; Kautzner, Josef

    2016-01-01

    Radiofrequency catheter ablation has become the treatment of choice for atrial fibrillation (AF) that does not respond to antiarrhythmic drug therapy. During the procedure, fluoroscopy imaging is still considered essential to visualise catheters in real-time. However, radiation is often ignored by physicians since it is invisible and the long-term risks are underestimated. In this respect, it must be emphasised that radiation exposure has various potentially harmful effects, such as acute skin injury, malignancies and genetic disease, both to patients and physicians. For this reason, every electrophysiologist should be aware of the problem and should learn how to decrease radiation exposure by both changing the setting of the system and using complementary imaging technologies. In this review, we aim to discuss the basics of X-ray exposure and suggest practical instructions for how to reduce radiation dosage during AF ablation procedures. PMID:27617094

  14. Safety and efficacy of multipolar pulmonary vein ablation catheter vs. irrigated radiofrequency ablation for paroxysmal atrial fibrillation: a randomized multicentre trial

    PubMed Central

    McCready, J.; Chow, A. W.; Lowe, M. D.; Segal, O. R.; Ahsan, S.; de Bono, J.; Dhaliwal, M.; Mfuko, C.; Ng, A.; Rowland, E. R.; Bradley, R. J. W.; Paisey, J.; Roberts, P.; Morgan, J. M.; Sandilands, A.; Yue, A.; Lambiase, P. D.

    2014-01-01

    Aims The current challenge in atrial fibrillation (AF) treatment is to develop effective, efficient, and safe ablation strategies. This randomized controlled trial assesses the medium-term efficacy of duty-cycled radiofrequency ablation via the circular pulmonary vein ablation catheter (PVAC) vs. conventional electro-anatomically guided wide-area circumferential ablation (WACA). Methods and results One hundred and eighty-eight patients (mean age 62 ± 12 years, 116 M : 72 F) with paroxysmal AF were prospectively randomized to PVAC or WACA strategies and sequentially followed for 12 months. The primary endpoint was freedom from symptomatic or documented >30 s AF off medications for 7 days at 12 months post-procedure. One hundred and eighty-three patients completed 12 m follow-up. Ninety-four patients underwent PVAC PV isolation with 372 of 376 pulmonary veins (PVs) successfully isolated and all PVs isolated in 92 WACA patients. Three WACA and no PVAC patients developed tamponade. Fifty-six percent of WACA and 60% of PVAC patients were free of AF at 12 months post-procedure (P = ns) with a significant attrition rate from 77 to 78%, respectively, at 6 months. The mean procedure (140 ± 43 vs. 167 ± 42 min, P<0.0001), fluoroscopy (35 ± 16 vs. 42 ± 20 min, P<0.05) times were significantly shorter for PVAC than for WACA. Two patients developed strokes within 72 h of the procedure in the PVAC group, one possibly related directly to PVAC ablation in a high-risk patient and none in the WACA group (P = ns). Two of the 47 patients in the PVAC group who underwent repeat ablation had sub-clinical mild PV stenoses of 25–50% and 1 WACA patient developed delayed severe PV stenosis requiring venoplasty. Conclusion The pulmonary vein ablation catheter is equivalent in efficacy to WACA with reduced procedural and fluoroscopy times. However, there is a risk of thrombo-embolic and pulmonary stenosis complications which needs to be addressed and prospectively monitored. Clinical

  15. A systematic review of surgical ablation versus catheter ablation for atrial fibrillation

    PubMed Central

    Kearney, Katherine; Stephenson, Rowan; Phan, Kevin; Chan, Wei Yen; Huang, Min Yin

    2014-01-01

    Background Atrial fibrillation (AF) is an increasingly prevalent condition in the ageing population, with significantly associated morbidity and mortality. Surgical and catheter ablative strategies both aim to reduce mortality and morbidity through freedom from AF. This review consolidates all currently available comparative data to evaluate these two interventions. Methods A systematic search was conducted across MEDLINE, PubMed, Embase, Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews from January 2000 until August 2013. All studies were critically appraised and only those directly comparing surgical and catheter ablation were included. Results Seven studies were deemed suitable for analysis according to the inclusion criteria. Freedom from AF was significantly higher in the surgical ablation group versus the catheter ablation group at 6-month, 12-month and study endpoint follow-up periods. Subgroup analysis demonstrated similar trends, with higher freedom from AF in the surgical ablation group for paroxysmal AF patients. The incidence of pacemaker implantation was higher, while no difference in stroke or cardiac tamponade was demonstrated for the surgical versus catheter ablation groups. Conclusions Current evidence suggests that epicardial ablative strategies are associated with higher freedom from AF, higher pacemaker implantation rates and comparable neurological complications and cardiac tamponade incidence to catheter ablative treatment. Other complications and risks were poorly reported, which warrants further randomized controlled trials (RCTs) of adequate power and follow-up duration. PMID:24516794

  16. Catheter Ablation as First-Line Therapy for Atrial Fibrillation: Ready for Prime-Time?

    PubMed

    Carrizo, Aldo G; Morillo, Carlos A

    2016-07-01

    Current guidelines include atrial fibrillation (AF) catheter ablation as part of the management strategy in patients that have failed at least one oral antiarrhythmic drug treatment course. However, growing evidence derived from both randomized and non-randomized studies demonstrate lower rates of AF recurrence and AF burden in patients with paroxysmal AF that are naïve to antiarrhythmic drug treatment. Furthermore, progression from paroxysmal AF to persistent AF appears to be delayed by early catheter ablation of AF. The current review addresses the question of the best timing for ablation in patients with paroxysmal AF and provides the rationale for offering AF ablation as first-line therapy based on the most updated evidence available. PMID:27300744

  17. Impact of Tricuspid Regurgitation on the Success of Atrioventricular Node Ablation for Rate Control in Patients With Atrial Fibrillation: The Node Blast Study.

    PubMed

    Reddy, Yeruva Madhu; Gunda, Sampath; Vallakati, Ajay; Kanmanthareddy, Arun; Pillarisetti, Jayasree; Atkins, Donita; Bommana, Sudharani; Emert, Martin P; Pimentel, Rhea; Dendi, Raghuveer; Berenbom, Loren D; Lakkireddy, Dhanunjaya

    2015-09-15

    Atrioventricular node (AVN) ablation is an effective treatment for symptomatic patients with atrial arrhythmias who are refractory to rhythm and rate control strategies where optimal ventricular rate control is desired. There are limited data on the predictors of failure of AVN ablation. Our objective was to identify the predictors of failure of AVN ablation. This is an observational single-center study of consecutive patients who underwent AVN ablation in a large academic center. Baseline characteristics, procedural variables, and outcomes of AVN ablation were collected. AVN "ablation failure" was defined as resumption of AVN conduction resulting in recurrence of either rapid ventricular response or suboptimal biventricular pacing. A total of 247 patients drug refractory AF who underwent AVN ablation at our center with a mean age of 71 ± 12 years with 46% being males were included. Ablation failure was seen in 11 (4.5%) patients. There were no statistical differences between patients with "ablation failure" versus "ablation success" in any of the baseline clinical variables. Patients with moderate-to-severe tricuspid regurgitation (TR) were much more likely to have ablation failure than those with ablation success (8 [73%] vs 65 [27%]; p = 0.003). All 11 patients with ablation failure had a successful redo procedure, 9 with right and 2 with the left sided approach. On multivariate analysis, presence of moderate-to-severe TR was found to be the only predictor of failure of AVN ablation (odds ratio 9.1, confidence interval 1.99 to 42.22, p = 0.004). In conclusion, moderate-to-severe TR is a strong and independent predictor of failure of AVN ablation. PMID:26174606

  18. Catheter ablation of atrial fibrillation in chronic heart failure: state-of-the-art and future perspectives.

    PubMed

    Anselmino, Matteo; Matta, Mario; Castagno, Davide; Giustetto, Carla; Gaita, Fiorenzo

    2016-05-01

    Catheter ablation of atrial fibrillation (AFCA) is a widely recommended treatment for symptomatic atrial fibrillation (AF) patients refractory to pharmacological treatment. Catheter ablation of AF is becoming a therapeutic option also among patients with chronic heart failure (CHF), on top of optimal medical treatment, being this arrhythmia related to a higher risk of death and/or symptom's worsening. In fact, in this setting, clinical evidences are continuously increasing. The present systematic review pools all published experiences concerning AFCA among CHF patients, or patients with structural cardiomyopathies, in order to summarize procedural safety and efficacy in this specific population. Moreover, the effects of AFCA on functional class and quality of life and the different procedural protocols available are discussed. The present work, therefore, attempts to provide an evidence-based clinical perspective to optimize clinical indication and tailor procedural characteristics and endpoints to patients affected by CHF referred for AFCA. PMID:26857188

  19. Factors related to sinus rhythm at discharge after radiofrequency ablation of permanent atrial fibrillation in patients undergoing mitral valve surgery.

    PubMed

    Rostagno, Carlo; Gelsomino, Sandro; Capecchi, Irene; Rossi, Alessandra; Montesi, Gian Franco; Stefàno, Pier Luigi

    2016-04-01

    Late recovery of sinus rhythm is unusual in patients with permanent AF treated by (radiofrequency) RF maze procedure during mitral valve surgery. Identification of clinical and instrumental preoperative factors predictive of early success of RF ablation in patients with permanent AF undergoing mitral valve surgery may improve selection of subjects to obtain long-term results. Hundred and thirty consecutive patients with permanent AF and mitral valve disease underwent modified RF maze procedure during concomitant mitral valve surgery. Rheumatic valve disease (61 pts) and mitral valve prolapse (41 pts) were the more common aetiology of valve abnormalities. Mitral valve replacement was performed in 54 % of patients and mitral valve repair in the remaining 46 %. Four patients died after surgery. At discharge, 87 patients (69 %) were in sinus rhythm (group 1) and 43 patients in AF persisted (group 2). At an average 24-month follow-up, sinus rhythm was present in 67 % of patients, and 33 % were in atrial fibrillation. In this period, late recovery of sinus rhythm was observed only in five patients, while eight discharged in sinus rhythm developed again atrial fibrillation. Among preoperative parameters at univariate analysis female sex, atrial fibrillation >24 months, left atrial diameter >54 mm, left atrial area >24 cm(2), rheumatic valve disease and NYHA class were associated with persistence of AF. At Cox regression multivariate analysis, increased left atrial area (OR 1.07 per unit increase-95 % CI 1.01-1.131) and rheumatic aetiology of valve disease (OR 4.52, 95 % CI 1.65-12.4) were associated with persistence of AF at hospital discharge. Persistence of AF after RF ablation in patients undergoing mitral valve surgery is related to aetiology, e.g. rheumatic valve disease, and to increasing left atrial diameter. Due to low rate of late recovery of sinus rhythm, indication to RF ablation associated with MV surgery should be carefully considered in patients with large

  20. Body Surface Mapping to Guide Atrial Fibrillation Ablation

    PubMed Central

    Yamashita, Seigo; Shah, Ashok J; Mahida, Saagar; Sellal, Jean-Marc; Berte, Benjamin; Hooks, Darren; Frontera, Antonio; Jefairi, Nora Al; Wielandts, Jean-Yves; Lim, Han S; Amraoui, Sana; Denis, Arnaud; Derval, Nicolas; Sacher, Frédéric; Cochet, Hubert; Hocini, Mélèze; Jaïs, Pierre; Haïssaguerre, Michel

    2015-01-01

    Atrial fibrillation (AF) is the most common rhythm disorder, and is strongly associated with thromboembolic events and heart failure. Over the past decade, catheter ablation of AF has advanced considerably with progressive improvement in success rates. However, interventional treatment is still challenging, especially for persistent and long-standing persistent AF. Recently, AF analysis using a non-invasive body surface mapping technique has been shown to identify localised reentrant and focal sources, which play an important role in driving and perpetuating AF. Non-invasive mapping-guided ablation has also been reported to be effective for persistent AF. In this review, we describe new clinical insights obtained from non-invasive mapping of persistent AF to guide catheter ablation. PMID:26835121

  1. Body Surface Mapping to Guide Atrial Fibrillation Ablation.

    PubMed

    Yamashita, Seigo; Shah, Ashok J; Mahida, Saagar; Sellal, Jean-Marc; Berte, Benjamin; Hooks, Darren; Frontera, Antonio; Jefairi, Nora Al; Wielandts, Jean-Yves; Lim, Han S; Amraoui, Sana; Denis, Arnaud; Derval, Nicolas; Sacher, Frédéric; Cochet, Hubert; Hocini, Mélèze; Jaïs, Pierre; Haïssaguerre, Michel

    2015-12-01

    Atrial fibrillation (AF) is the most common rhythm disorder, and is strongly associated with thromboembolic events and heart failure. Over the past decade, catheter ablation of AF has advanced considerably with progressive improvement in success rates. However, interventional treatment is still challenging, especially for persistent and long-standing persistent AF. Recently, AF analysis using a non-invasive body surface mapping technique has been shown to identify localised reentrant and focal sources, which play an important role in driving and perpetuating AF. Non-invasive mapping-guided ablation has also been reported to be effective for persistent AF. In this review, we describe new clinical insights obtained from non-invasive mapping of persistent AF to guide catheter ablation. PMID:26835121

  2. Advances in catheter ablation: atrial fibrillation ablation in patients with mitral mechanical prosthetic valve.

    PubMed

    Santangeli, Pasquale; Di Biase, Luigi; Bai, Rong; Horton, Rodney; Burkhardt, J David; Sanchez, Javier; Price, Justin; Natale, Andrea

    2012-11-01

    Atrial fibrillation (AF) is common in patients with mitral valve replacement (MVR). Treatment of AF in these subjects is challenging, as the arrhythmia is often refractory to antiarrhythmic drug therapy. Radiofrequency catheter ablation (RFCA) is usually avoided or delayed in patients with MVR due to the higher perceived risks and difficulty of left atrial catheter manipulation in the presence of a mechanical valve. Over the last few years, several investigators have reported the feasibility and safety of RFCA of AF in patients with MVR. Five case-control studies have evaluated the feasibility and safety of RFCA of AF or perimitral flutter (PMFL) in patients with MVR. Overall, a total of 178 patients with MVR have been included (21 undergoing ablation of only PMFL), and have been compared with a matched control group of 285 patients. Total procedural duration (weighted mean difference [WMD] = +24.5 min, 95% confidence interval [CI] +10.2 min to +38.8 min, P = 0.001), and fluoroscopy time (WMD = +13.5 min, 95% CI +3.7 min to +23.4 min, P = 0.007) were longer in the MVR group. After a mean follow-up of 11.5 ± 8.6 months, 64 (36%) patients in the MVR group experienced recurrence of AF/PMFL, as compared to 73 (26%) patients in the control group, accounting for a trend toward an increased rate of recurrences in patients with MVR (odds ratio [OR] = 1.66, 95% CI 0.99 to 2.78, P = 0.053). Periprocedural complications occurred in 10 (5.6%) patients in the MVR group, and in 8 (2.8%) patients in the control group (OR = 2.01, 95% CI 0.56 to 7.15, P = 0.28). In conclusion, a quantitative analysis of the available evidence supports a trend toward a worse arrhythmia-free survival and a higher absolute rate of periprocedural complications in patients with MVR undergoing RFCA of AF or PMFL, as compared to a matched control group without mitral valve disease. These data would encourage the adoption of RFCA of AF in MVR patients mostly by more experienced Institutions. PMID:23003204

  3. Catheter Ablation Related Mitral Valve Injury: The Importance of Early Recognition and Rescue Mitral Valve Repair

    PubMed Central

    DeSimone, Christopher V.; Hu, Tiffany; Ebrille, Elisa; Syed, Faisal F.; Vaidya, Vaibhav R.; Cha, Yong-Mei; Valverde, Arturo M.; Friedman, Paul A.; Suri, Rakesh M.; Asirvatham, Samuel J.

    2015-01-01

    Introduction An increasing number of catheter ablations involve the mitral annular region and valve apparatus, increasing the risk of catheter interaction with the mitral valve (MV) complex. We review our experience with catheter ablation-related MV injury resulting in severe mitral regurgitation (MR) to delineate mechanisms of injury and outcomes. Methods We searched the Mayo Clinic mitral valve surgical database over a 19-year period (1993–2012) and the electrophysiologic procedures database over a 23-year period (1990–2013) and identified 9 patients with catheter ablation related MV injury requiring clinical intervention. Results Indications for ablation included atrial fibrillation (AF) [n=4], ventricular tachycardia (VT) [n =3], and left-sided accessory pathways [n=2]. In all 4 AF patients, a circular mapping catheter entrapped in the MV apparatus was responsible for severe mitral regurgitation. In all 3 VT patients, radiofrequency energy delivery led to direct injury to the MV apparatus. In the 2 patients with accessory pathways, both mechanisms were involved (1 per patient). Six patients required surgical intervention (5 MV repair, 1 catheter removal). One patient developed severe functional MR upon successful endovascular catheter disentanglement that improved spontaneously. Two VT patients with persistent severe post-ablation MR were managed non-surgically, one of whom died 3 months post-procedure. Conclusion Circular mapping catheter entrapment and ablation at the mitral annulus are the most common etiologies of MV injury during catheter ablation. Close surveillance of the MV is needed during such procedures and early surgical repair is important for successful salvage if significant injury occurs. PMID:24758402

  4. Cardiac ablation procedures

    MedlinePlus

    ... food tips Heart attack - discharge Heart disease - risk factors Heart failure ... Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed ...

  5. Linear Ablation Following Pulmonary Vein Isolation in Patients with Atrial Fibrillation: A Meta-Analysis.

    PubMed

    Zhang, Zhiwei; Letsas, Konstantinos P; Zhang, Nixiao; Efremidis, Michael; Xu, Gang; Li, Guangping; Liu, Tong

    2016-06-01

    Previous studies have given conflicting data regarding the long-term adjunctive efficacy of linear lesions (LLs) on top of pulmonary vein isolation (PVI) as an ablation strategy in patients with atrial fibrillation (AF). The aim of this meta-analysis was to provide a detailed analysis of the available randomized controlled trials (RCTs) regarding the efficacy of LL following PVI in AF patients. Current databases were searched until October 2015. The primary outcome end point of the meta-analysis was recurrence of any symptomatic or documented episode of AF or atrial tachycardia after a single ablation procedure with or without the use of antiarrhythmic drugs. Ten RCTs with a total of 1,446 patients were included in the meta-analysis. The pooled analysis of five trials concerning persistent AF (PeAF) patients (400 in PVI plus LL group and 182 in PVI alone group) suggested that the addition of LL following PVI does not lead to a significant reduction in recurrent atrial tachyarrhythmias compared with PVI alone (relative ratio [RR] = 0.73, 95% confidence interval [CI]: 0.44-1.21, P = 0.22). Similarly, there was no incremental benefit of additional LL in long-term outcomes in paroxysmal AF (PAF) patients (RR = 0.85, 95% CI: 0.68-1.05, P = 0.13). Pooling the results of all eligible trials suggested that PVI plus LL compared with PVI alone significantly increased radiofrequency time (P = 0.0002), fluoroscopy time (P < 0.00001), and procedure time (P < 0.0001). This meta-analysis suggests that LL following PVI does not provide additional benefit to sinus rhythm maintenance in patients with PeAF and PAF. PMID:26970360

  6. Long-term outcomes after ablation of persistent atrial fibrillation: an observational study over 6 years

    PubMed Central

    El-Kadri, Moutaz; Haq, Iram; Das, Moloy; Modi, Simon; Snowdon, Richard; Hall, Mark; Waktare, Johan EP; Todd, Derick M; Gupta, Dhiraj

    2016-01-01

    Objectives To address the limited long-term outcome data for catheter ablation (CA) of persistent atrial fibrillation (PeAF), we analysed consecutive ablations performed at our centre from 1 January 2008 to 31 December 2010 and followed patients prospectively until January 2014. Methods Both arrhythmia recurrence and symptom relief were assessed. Follow-up data were collected from hospital records, supplemented by data from general practitioners and referring hospitals. At the end of the follow-up period, all patients were contacted by phone to determine their up-to-date clinical condition. Results 188 consecutive patients with PeAF (157 male, mean age 57.3±9.7 years, 20% with long-standing PeAF) underwent a mean of 1.75 procedures (range 1–4). Telephone follow-up was achieved for 77% of surviving patients. Over a mean follow-up of 46±16 months (range 4–72), 139 (75%) patients experienced arrhythmia recurrence after a single procedure and 90 (48%) after their final procedure. Median time to first recurrence was 210 days (range 91–1850). 71% of recurrences were within the first year following ablation and 91% within 2 years. At final follow-up, 82% of patients reported symptomatic improvement. 7 (2.3%) major complications occurred, and there was no procedure-related death or stroke. Conclusions CA for PeAF is safe with a low rate of complications. Over a follow-up period of up to 6 years, a large majority of patients experience significant symptomatic improvement but recurrence after the initial procedure is the norm rather than the exception. 2 years' follow-up is sufficient to observe 90% of AF recurrences, but recurrence can occur even after 5 years' remission. PMID:27547426

  7. Ablative therapies for renal tumors

    PubMed Central

    Ramanathan, Rajan; Leveillee, Raymond J.

    2010-01-01

    Owing to an increased use of diagnostic imaging for evaluating patients with other abdominal conditions, incidentally discovered kidney masses now account for a majority of renal tumors. Renal ablative therapy is assuming a more important role in patients with borderline renal impairment. Renal ablation uses heat or cold to bring about cell death. Radiofrequency ablation and cryoablation are two such procedures, and 5-year results are now emerging from both modalities. Renal biopsy at the time of ablation is extremely important in order to establish tissue diagnosis. Real-time temperature monitoring at the time of radiofrequency ablation is very useful to ensure adequacy of ablation. PMID:21789083

  8. [A case of bile peritonitis caused by jejunal perforation after radiofrequency ablation for the multiple liver metastases from cholangiocarcinoma successfully treated with various interventional radiological procedures after pancreatoduodenectomy].

    PubMed

    Yasumoto, Taku; Shimizu, Junzo; Watanabe, Noriyuki; Inada, Masami; Nakata, Saki; Sato, Masayuki; Hayashi, Shoho; Dono, Keizo; Kitada, Masashi; Shimano, Takashi

    2009-11-01

    The case is a man in his 50s who had a curative surgical resection for cholangiocarcinoma in August 2006. The lesion was judged to be T3, N1, H0, P0, M0 and Stage III, and then he received various treatments including thermotherapy, CD3-activated T lymphocyte therapy. Then from June 2007, he was treated for multiple liver metastases by GEM, radiofrequency ablation (RFA), stereotactic radiotherapy, S-1, dendritic cell therapy. But there were multiple liver metastases whose maximum size was 17 mm in diameter and he was introduced to our hospital. In September 2008, ultrasonography and CT fluoroscopy guided RFA was operated on him for the liver tumors with a safety margin. But 2 hours after the ablation, he complained of epigastralgia. CT examination revealed a bile peritonitis caused by perforation of the jejunum which has been anastomosed to the pancreas, and was adjacent to the avascular area caused by RFA in segment 4 of the liver. We treated him by various interventional procedures including percutaneous drainage for bile leakage, pancreatic fistula, abscess in peritoneal cavity, and biloma in segment 3. Fifty days after the ablation, T-tube, with which pancreatic fluid and bile was induced from the cecal portion of the anastomosed jejunum to the anal side slipping through the perforated point, was successfully inserted through right flank, and resulted in complete recovery from a major technical complication of the bile peritonitis. PMID:20037334

  9. Navigation Systems for Ablation

    PubMed Central

    Wood, B. J.; Kruecker, J.; Abi-Jaoudeh, N; Locklin, J.; Levy, E.; Xu, S.; Solbiati, L.; Kapoor, A.; Amalou, H.; Venkatesan, A.

    2010-01-01

    Navigation systems, devices and intra-procedural software are changing the way we practice interventional oncology. Prior to the development of precision navigation tools integrated with imaging systems, thermal ablation of hard-to-image lesions was highly dependent upon operator experience, spatial skills, and estimation of positron emission tomography-avid or arterial-phase targets. Numerous navigation systems for ablation bring the opportunity for standardization and accuracy that extends our ability to use imaging feedback during procedures. Existing systems and techniques are reviewed, and specific clinical applications for ablation are discussed to better define how these novel technologies address specific clinical needs, and fit into clinical practice. PMID:20656236

  10. Magnetic Resonance Imaging-Guided High-Intensity Focused Ultrasound Ablation of Uterine Fibroids: Effect of Bowel Interposition on Procedure Feasibility and a Unique Bowel Displacement Technique

    PubMed Central

    Kim, Young-sun; Lim, Hyo Keun; Rhim, Hyunchul

    2016-01-01

    Purpose To evaluate the effect of bowel interposition on assessing procedure feasibility, and the usefulness and limiting conditions of bowel displacement techniques in magnetic resonance imaging-guided high-intensity focused ultrasound (MR-HIFU) ablation of uterine fibroids. Materials and Methods Institutional review board approved this study. A total of 375 screening MR exams and 206 MR-HIFU ablations for symptomatic uterine fibroids performed between August 2010 and March 2015 were retrospectively analyzed. The effect of bowel interposition on procedure feasibility was assessed by comparing pass rates in periods before and after adopting a unique bowel displacement technique (bladder filling, rectal filling and subsequent bladder emptying; BRB maneuver). Risk factors for BRB failure were evaluated using logistic regression analysis. Results Overall pass rates of pre- and post-BRB periods were 59.0% (98/166) and 71.7% (150/209), and in bowel-interposed cases they were 14.6% (7/48) and 76.4% (55/72), respectively. BRB maneuver was technically successful in 81.7% (49/60). Through-the-bladder sonication was effective in eight of eleven BRB failure cases, thus MR-HIFU could be initiated in 95.0% (57/60). A small uterus on treatment day was the only significant risk factor for BRB failure (B = 0.111, P = 0.017). Conclusion The BRB maneuver greatly reduces the fraction of patients deemed ineligible for MR-HIFU ablation of uterine fibroids due to interposed bowels, although care is needed when the uterus is small. PMID:27186881

  11. Ablating atrial fibrillation: A translational science perspective for clinicians.

    PubMed

    Weiss, James N; Qu, Zhilin; Shivkumar, Kalyanam

    2016-09-01

    Although considerable progress has been made in developing ablation approaches to cure atrial fibrillation (AF), outcomes are still suboptimal, especially for persistent and long-lasting persistent AF. In this topical review, we review the arrhythmia mechanisms, both reentrant and nonreentrant, that are potentially relevant to human AF at various stages/settings. We describe arrhythmia mapping techniques used to distinguish between the different mechanisms, with a particular focus on the detection of rotors. We discuss which arrhythmia mechanisms are likely to respond to ablation, and the challenges and prospects for improving upon current ablation strategies to achieve better outcomes. PMID:27241354

  12. Three-dimensional electroanatomic mapping systems in catheter ablation of atrial fibrillation.

    PubMed

    Lo, Li-Wei; Chen, Shih-Ann

    2010-01-01

    Atrial fibrillation (AF) is the most common tachyarrhythmia, with a prevalence of 5% in people over the age of 65. Catheter ablation of AF has emerged as an important management choice for drug-refractory symptomatic paroxysmal or persistent AF. Three-dimensional (3D) electroanatomic mapping systems were introduced into catheter ablation of AF more than a decade ago. The 3D tool has the benefit of reducing the radiation exposure time, as well as voltage and fractionation mapping in order to identify the critical substrate during the ablation, prevent the formation of gaps, guide the ablation of post-ablation atrial tachycardia or flutter, and integrate images to improve the safety and long-term success rate. The 3D systems successfully enable safe and tailored radiofrequency ablation of AF in individual patients. (Circ J 2010; 74: 18 - 23). PMID:19920357

  13. Benefit of Left Atrial Roof Linear Ablation in Paroxysmal Atrial Fibrillation: A Prospective, Randomized Study

    PubMed Central

    Arbelo, Elena; Guiu, Esther; Bisbal, Felipe; Ramos, Pablo; Borras, Roger; Andreu, David; Tolosana, José María; Berruezo, Antonio; Brugada, Josep; Mont, Lluís

    2014-01-01

    Background Isolation of the pulmonary veins (PVs) for the treatment of atrial fibrillation (AF) is often supplemented with linear lesions within the left atrium (LA). However, there are conflicting data on the effects of creating a roof line (RL) joining the superior PVs in paroxysmal atrial fibrillation (PAF). Methods and Results A cohort of 120 patients with drug‐refractory PAF referred for ablation were prospectively randomized into 2 strategies: (1) PV isolation in combination with RL ablation (LA roof ablation [LARA]‐1: 59 patients) or (2) PV isolation (LARA‐2: 61 patients). Follow‐up was performed at 1, 3, and 6 months after the procedure and every 6 months thereafter. After a 3‐month blanking period, recurrence was defined as the ocurrence of any atrial tachyarrhythmia lasting ≥30 seconds. PV isolation was achieved in 89% and complete RL block in 81%. RF duration, fluoroscopy, and procedural times were slightly, but not significantly, longer in the LARA‐1 group. After 15±10 months, there was no difference in the arrhythmia‐free survival after a single AF ablation procedure (LARA‐1: 59% vs. LARA‐2: 56% at 12 months; log rank P=0.77). The achievement of complete RL block did not influence the results. The incidence of LA macroreentrant tachycardias was 5.1% in the LARA‐1 group (n=3) versus 8.2% in the LARA‐2 (n=5) (P=ns). Univariate analysis only identified AF duration as a covariate associated with arrhythmia recurrence (hazard ratio, 1.01 [95% confidence interval, 1.002 to 1.012]; P<0.01). Conclusion The linear block at the LA roof is not associated with an improved clinical outcome compared with PV isolation alone. Clinical Trial Registration URL: ClinicalTrials.gov. Unique identifier: NCT01203241. PMID:25193295

  14. CTS Trials Network: Surgical ablation of atrial fibrillation during mitral valve surgery - many questions unanswered

    PubMed Central

    Afifi, Ahmed

    2015-01-01

    A disease that is associated with stroke and mortality, atrial fibrillation (AF) complicates 30 to 50% of mitral valve disease patients admitted for surgery.1 Since the introduction of the Cox maze III procedure in 1992 many efforts have been made to come up with modified lesion sets and/or energy sources to surgically treat AF. This lead to the recently published American Heart Association (AHA)– American College of Cardiology (ACC)–Heart Rhythm Society (HRS) guidelines2 stating that it is reasonable to perform atrial fibrillation ablation in selected patients undergoing other types of cardiac surgery. The effectiveness of different techniques in conversion to sinus rhythm and the clinical impact of freedom from AF remain a question. The CTS Trials Network have undertaken a trial to answer these questions. The first year results of their randomized trial comparing AF ablation at the time of mitral valve surgery with mitral valve surgery alone were published recently in The New England Journal of Medicine.3 PMID:26566527

  15. Catheter ablation in combination with left atrial appendage closure for atrial fibrillation.

    PubMed

    Swaans, Martin J; Alipour, Arash; Rensing, Benno J W M; Post, Martijn C; Boersma, Lucas V A

    2013-01-01

    Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting millions of individuals worldwide. The rapid, irregular, and disordered electrical activity in the atria gives rise to palpitations, fatigue, dyspnea, chest pain and dizziness with or without syncope. Patients with AF have a five-fold higher risk of stroke. Oral anticoagulation (OAC) with warfarin is commonly used for stroke prevention in patients with AF and has been shown to reduce the risk of stroke by 64%. Warfarin therapy has several major disadvantages, however, including bleeding, non-tolerance, interactions with other medications and foods, non-compliance and a narrow therapeutic range. These issues, together with poor appreciation of the risk-benefit ratio, unawareness of guidelines, or absence of an OAC monitoring outpatient clinic may explain why only 30-60% of patients with AF are prescribed this drug. The problems associated with warfarin, combined with the limited efficacy and/or serious side effects associated with other medications used for AF, highlight the need for effective non-pharmacological approaches to treatment. One such approach is catheter ablation (CA), a procedure in which a radiofrequency electrical current is applied to regions of the heart to create small ablation lesions that electrically isolate potential AF triggers. CA is a well-established treatment for AF symptoms, that may also decrease the risk of stroke. Recent data showed a significant decrease in the relative risk of stroke and transient ischemic attack events among patients who underwent ablation compared with those undergoing antiarrhythmic drug therapy. Since the left atrial appendage (LAA) is the source of thrombi in more than 90% of patients with non-valvular atrial fibrillation, another approach to stroke prevention is to physically block clots from exiting the LAA. One method for occluding the LAA is via percutaneous placement of the WATCHMAN LAA closure device. The WATCHMAN device

  16. Perioperative atrial fibrillation: A systematic review of evolving therapeutic options in pharmacologic and procedural management

    PubMed Central

    Schleifer, J. William; Ramakrishna, Harish

    2015-01-01

    Given the high incidence of atrial fibrillation (AF) in the surgical population and the associated morbidity, physicians managing these complicated patients in the perioperative period need to be aware of the new and emerging trends in its therapy. The cornerstones of AF management have always been rate/rhythm control as well as anticoagulation. Restoration of sinus rhythm remains the fundamental philosophy as it maintains the atrial contribution to cardiac output and improves ventricular function. The recent years have seen a dramatic increase in the number of randomized AF trials that have made significant advances to our understanding of both pharmacologic and procedural management, from the introduction of the new generation of oral anticoagulants (NOAC's) to catheter approaches for AF ablation. This paper will summarize the newest data that will affect the perioperative management of these patients. PMID:26440243

  17. Analytical procedure for characterization of medieval wall-paintings by X-ray fluorescence spectrometry, laser ablation inductively coupled plasma mass spectrometry and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Syta, Olga; Rozum, Karol; Choińska, Marta; Zielińska, Dobrochna; Żukowska, Grażyna Zofia; Kijowska, Agnieszka; Wagner, Barbara

    2014-11-01

    Analytical procedure for the comprehensive chemical characterization of samples from medieval Nubian wall-paintings by means of portable X-ray fluorescence (pXRF), laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and Raman spectroscopy (RS) was proposed in this work. The procedure was used for elemental and molecular investigations of samples from archeological excavations in Nubia (modern southern Egypt and northern Sudan). Numerous remains of churches with painted decorations dated back to the 7th-14th century were excavated in the region of medieval kingdoms of Nubia but many aspects of this art and its technology are still unknown. Samples from the selected archeological sites (Faras, Old Dongola and Banganarti) were analyzed in the form of transfers (n = 26), small fragments collected during the excavations (n = 35) and cross sections (n = 15). XRF was used to collect data about elemental composition, LA-ICPMS allowed mapping of selected elements, while RS was used to get the molecular information about the samples. The preliminary results indicated the usefulness of the proposed analytical procedure for distinguishing the substances, from both the surface and sub-surface domains of the wall-paintings. The possibility to identify raw materials from the wall-paintings will be used in the further systematic, archeometric studies devoted to the detailed comparison of various historic Nubian centers.

  18. [Catheter ablation in patients with atrial fibrillation: what will change in daily practice?].

    PubMed

    van der Voort, Pepijn H

    2013-01-01

    A recent publication compared catheter ablation and antiarrhythmic drugs as initial therapy for paroxysmal atrial fibrillation. No difference was seen in the primary endpoint of the cumulative AF burden over two years. The burden of AF was documented objectively by a series of 7-day continuous ECG recordings; a method that will evolve as a gold standard for measuring the AF burden. The major shortcoming of the study was an obsolete ablation endpoint, lacking verification of pulmonary vein isolation. Other drawbacks were the fact that ablations were not exclusively carried out in high-volume centres and a high cross-over rate in the drug group. Also, although the primary endpoint was not significantly different, several secondary outcomes obviously favoured ablation. Outcomes in both the ablation and drug groups were relatively good, and this study will not change the current practice for the majority of paroxysmal AF patients, although catheter ablation could be performed as the initial therapy. PMID:23548191

  19. The mechanism of lesion formation by focused ultrasound ablation catheter for treatment of atrial fibrillation

    NASA Astrophysics Data System (ADS)

    Sinelnikov, Y. D.; Fjield, T.; Sapozhnikov, O. A.

    2009-10-01

    The application of therapeutic ultrasound for the treatment of atrial fibrillation (AF) is investigated. The results of theoretical and experimental investigation of ultrasound ablation catheter are presented. The major components of the catheter are the high power cylindrical piezoelectric element and parabolic balloon reflector. Thermal elevation in the ostia of pulmonary veins is achieved by focusing the ultrasound beam in shape of a torus that transverses the myocardial tissue. High intensity ultrasound heating in the focal zone results in a lesion surrounding the pulmonary veins that creates an electrical conduction blocks and relief from AF symptoms. The success of the ablation procedure largely depends on the correct choice of reflector geometry and ultrasonic power. We present a theoretical model of the catheter’s acoustic field and bioheat transfer modeling of cardiac lesions. The application of an empirically derived relation between lesion formation and acoustic power is shown to correlate with the experimental data. Developed control methods combine the knowledge of theoretical acoustics and the thermal lesion formation simulations with experiment and thereby establish dosimetry that contributes to a safe and effective ultrasound ablation procedure.

  20. THE MECHANISM OF LESION FORMATION BY FOCUSED ULTRASOUND ABLATION CATHETER FOR TREATMENT OF ATRIAL FIBRILLATION

    PubMed Central

    Sinelnikov, Y.D.; Fjield, T.; Sapozhnikov, O.A.

    2009-01-01

    The application of therapeutic ultrasound for the treatment of atrial fibrillation (AF) is investigated. The results of theoretical and experimental investigation of ultrasound ablation catheter are presented. The major components of the catheter are the high power cylindrical piezoelectric element and parabolic balloon reflector. Thermal elevation in the ostia of pulmonary veins is achieved by focusing the ultrasound beam in shape of a torus that transverses the myocardial tissue. High intensity ultrasound heating in the focal zone results in a lesion surrounding the pulmonary veins that creates an electrical conduction blocks and relief from AF symptoms. The success of the ablation procedure largely depends on the correct choice of reflector geometry and ultrasonic power. We present a theoretical model of the catheter’s acoustic field and bioheat transfer modeling of cardiac lesions. The application of an empirically derived relation between lesion formation and acoustic power is shown to correlate with the experimental data. Developed control methods combine the knowledge of theoretical acoustics and the thermal lesion formation simulations with experiment and thereby establish rigorous dosimetry that contributes to a safe and effective ultrasound ablation procedure. PMID:20161431

  1. Is radiation-induced ovarian ablation in breast cancer an obsolete procedure? Results of a meta-analysis

    PubMed Central

    Asiri, Mushabbab Al; Tunio, Mutahir A; Abdulmoniem, Reham

    2016-01-01

    Background A meta-analysis was conducted to assess the impact of radiation-induced ovarian ablation (RT-OA) on amenorrhea cessation rates, progression-free survival, and overall survival in pre/perimenopausal women with breast cancer. Materials and methods The Medline, CANCERLIT, and Cochrane Library databases and search engines were searched to identify randomized controlled studies comparing RT-OA with control for early or metastatic breast cancer. Further, radiotherapy doses, techniques, and associated side effects were evaluated. Results Six controlled trials with a total patient population of 3,317 were identified. Pooled results from these trials showed significant amenorrhea rates (P<0.00001) and increase in progression-free survival in patients treated with RT-OA (P<0.00001). However, there was no difference in overall survival (P=0.37). The majority of patients were treated with larger field sizes with parallel-opposed anteroposterior and posteroanterior pelvic fields. RT-OA was generally well tolerated. Radiotherapy doses of 1,500 cGy in five fractions, 1,500 cGy in four fractions, 1,600 cGy in four fractions, and 2,000 cGy in ten fractions were associated with excellent amenorrhea rates. The resultant funnel plot showed no publication bias (Egger test P=0.16). Conclusion RT-OA is cost-effective and can safely be used in pre/perimenopausal women with metastatic breast cancer, or if luteinizing hormone-releasing hormone analogs are contraindicated, or in patients in whom fertility preservation is not an issue. Radiation dose of 1,500 cGy in five fractions, 1,500 cGy in four fractions, 1,600 cGy in four fractions, and 2,000 cGy in ten fractions showed more efficacies. However, further studies incorporating three-dimensional conformal radiotherapy and intensity-modulated radiotherapy are warranted. PMID:27307764

  2. Catheter Ablation for Long-Standing Persistent Atrial Fibrillation

    PubMed Central

    Romero, Jorge; Gianni, Carola; Di Biase, Luigi; Natale, Andrea

    2015-01-01

    Atrial fibrillation (AF) is the most common sustained arrhythmia worldwide and represents a major burden to health care systems. Atrial fibrillation is associated with a 4- to 5-fold increased risk of thromboembolic stroke. The pulmonary veins have been identified as major sources of atrial triggers for AF. This is particularly true in patients with paroxysmal AF but not always the case for those with long-standing persistent AF (LSPAF), in which other locations for ectopic beats have been well recognized. Structures with foci triggering AF include the coronary sinus, the left atrial appendage (LAA), the superior vena cava, the crista terminalis, and the ligament of Marshall. More than 30 studies reporting results on radiofrequency ablation of LSPAF have been published to date. Most of these are observational studies with very different methodologies using different strategies. As a result, there has been remarkable variation in short- and long-term success, which suggests that the optimal ablation technique for LSPAF is still to be elucidated. In this review we discuss the different approaches to LSPAF catheter ablation, starting with pulmonary vein isolation (PVI) through ablation lines in different left atrial locations, the role of complex fractionated atrial electrograms, focal impulses and rotor modulation, autonomic modulation (ganglionated plexi), alcohol ablation, and the future of epicardial mapping and ablation for this arrhythmia. A stepwise ablation approach requires several key ablation techniques, such as meticulous PVI, linear ablation at the roof and mitral isthmus, electrogram-targeted ablation with particular attention to triggers in the coronary sinus and LAA, and discretionary right atrial ablation (superior vena cava, intercaval, or cavotricuspid isthmus lines). PMID:26306125

  3. Initial outcome following invasive cardiac electrophysiologic studies and radiofrequency ablation of atrial fibrillation

    PubMed Central

    Uwanuruochi, Kelechukwu; Saravanan, Sabari; Ganasekar, Anita; Solomon, Benjamin S; Murugesan, Ravikumar; Shah, Ruchit A; Krishnamoorthy, Jaishankar; Pandurangi, Ulhas M

    2016-01-01

    Background: Cardiac electrophysiologic study and radiofrequency ablation (RFA) have become an established mode of treatment for patients with refractory arrhythmias. These procedures are carried out regularly at the cardiac catheterization laboratory of Madras Medical Mission India. Objective: The purpose of this study was to evaluate our experience with cardiac electrophysiologic studies (EPS) and RFA catheter of atrial fibrillation (AF). Materials and Methods: This was a retrospective study carried out in the Cardiac Electrophysiology Department of the Institute of Cardiovascular Diseases, Madras Medical Mission, India. All cases diagnosed to have AF following cardiac EPS between January 2010 and April 2014 was selected for the study. The records, which were obtained from the Cardiac Electrophysiology Clinical Research Office of Madras Medical Mission, were reviewed. Forty-nine cases were chosen for analysis, using SPSS statistical software version 15. Results: There were 49 patients, 23 males and 26 females. The mean age was 57.53 years. Commonly associated diseases were diabetes mellitus 8 (16.3%), hypertension 18 (36.7%), and coronary heart disease 14 (28.5%). The ventricular rate was rapid most cases (91.2%). AF was diagnosed as being paroxysmal in 40 (81.6%), persistent in 5 (10.2%), chronic in 3 (6.1%), and lone in 1 (2.0%). Ablation was carried out in 28 (57.1%), the success rate being 90% for pulmonary vein isolation, and 90.9% for atrioventricular node ablation. Complication rate was 2.04%. Conclusions: Treatment of AF by RFA is highly effective and safe. PMID:27127736

  4. Two-Year Follow-Up after Contact Force Sensing Radiofrequency Catheter and Second-Generation Cryoballoon Ablation for Paroxysmal Atrial Fibrillation: A Comparative Single Centre Study.

    PubMed

    Kardos, Attila; Kis, Zsuzsanna; Som, Zoltan; Nagy, Zsofia; Foldesi, Csaba

    2016-01-01

    Background. There are little comparative data on catheter ablation of paroxysmal atrial fibrillation (AF) using the contact force radiofrequency (CF-RF) catheter versus the second-generation cryoballoon (CB2). Methods and results. This is a single center, retrospective, nonrandomized study of 98 patients with symptomatic, drug-refractory paroxysmal AF who underwent their first PVI ablation using either the CB2 (n = 40) or CF-RF (n = 58). The mean age was 60 years with 63% men, a mean LA size of 42 mm. The procedure duration (74 ± 17 versus 120 ± 49 minutes p < 0.05) was shorter for CB2 group; the fluoroscopy time (14 ± 17 versus 16 ± 5 minutes, p = 0.45) was similar. Complete PVI was achieved in 96% of patients with RF-CF and 98% with CB2. Phrenic nerve palsies (2 transient and 1 persistent) occurred exclusively in the CB2 group and 1 severe, nonlethal complication (pericardial tamponade) occurred in the CF-RF group. At 24-month follow-up, the success rate, defined as freedom from AF/atrial tachycardia (AT) after a single procedure without antiarrhythmic drug, was comparable in CF-RF group and CB2 group (65.5% versus 67%, resp., log rank p = 0.54). Conclusion. Both the CB2 and the RF-CF ablation appeared safe; the success rate at 2 years was comparable between both technologies. PMID:27314032

  5. Two-Year Follow-Up after Contact Force Sensing Radiofrequency Catheter and Second-Generation Cryoballoon Ablation for Paroxysmal Atrial Fibrillation: A Comparative Single Centre Study

    PubMed Central

    Kardos, Attila; Kis, Zsuzsanna; Som, Zoltan; Nagy, Zsofia; Foldesi, Csaba

    2016-01-01

    Background. There are little comparative data on catheter ablation of paroxysmal atrial fibrillation (AF) using the contact force radiofrequency (CF-RF) catheter versus the second-generation cryoballoon (CB2). Methods and results. This is a single center, retrospective, nonrandomized study of 98 patients with symptomatic, drug-refractory paroxysmal AF who underwent their first PVI ablation using either the CB2 (n = 40) or CF-RF (n = 58). The mean age was 60 years with 63% men, a mean LA size of 42 mm. The procedure duration (74 ± 17 versus 120 ± 49 minutes p < 0.05) was shorter for CB2 group; the fluoroscopy time (14 ± 17 versus 16 ± 5 minutes, p = 0.45) was similar. Complete PVI was achieved in 96% of patients with RF-CF and 98% with CB2. Phrenic nerve palsies (2 transient and 1 persistent) occurred exclusively in the CB2 group and 1 severe, nonlethal complication (pericardial tamponade) occurred in the CF-RF group. At 24-month follow-up, the success rate, defined as freedom from AF/atrial tachycardia (AT) after a single procedure without antiarrhythmic drug, was comparable in CF-RF group and CB2 group (65.5% versus 67%, resp., log rank p = 0.54). Conclusion. Both the CB2 and the RF-CF ablation appeared safe; the success rate at 2 years was comparable between both technologies. PMID:27314032

  6. Early recurrence of atrial fibrillation after catheter ablation with left atrial fibrosis identified at cardiac magnetic resonance by late gadolinium enhancement.

    PubMed

    Totaro, Antonio; Casavecchia, Graziapia; Gravina, Matteo; Ieva, Riccardo; Santoro, Francesco; Grimaldi, Massimo; Pellegrino, Pier Luigi; Macarini, Luca; Di Biase, Matteo; Brunetti, Natale Daniele

    2016-08-01

    In patients with atrial fibrillation (AF), extensive atrial tissue fibrosis identified by delayed enhancement magnetic resonance imaging has been associated with early recurrence of AF after catheter ablation. We present a case of a patient with extensive atrial fibrosis and AF recurrence.The study of late gadolinium enhancement with cardiac magnetic resonance imaging in patients with AF could be a valuable noninvasive tool for the selection of patients suitable for successful catheter ablation. PMID:26826170

  7. Radiofrequency Ablation of Metastatic Pheochromocytoma

    PubMed Central

    Venkatesan, Aradhana M.; Locklin, Julia; Lai, Edwin W.; Adams, Karen T.; Fojo, Antonio Tito; Pacak, Karel; Wood, Bradford J.

    2013-01-01

    In the present report on the preliminary safety and effectiveness of radiofrequency (RF) ablation for pheochromocytoma metastases, seven metastases were treated in six patients (mean size, 3.4 cm; range, 2.2–6 cm). α- and β-adrenergic and catecholamine synthesis inhibition and intraprocedural anesthesia monitoring were used. Safety was assessed by recording ablation-related complications. Complete ablation was defined as a lack of enhancement within the ablation zone on follow-up computed tomography. No serious adverse sequelae were observed. Complete ablation was achieved in six of seven metastases (mean follow-up, 12.3 months; range, 2.5–28 months). In conclusion, RF ablation may be safely performed for metastatic pheochromocytoma given careful attention to peri-procedural management. PMID:19875067

  8. Ablative system

    NASA Technical Reports Server (NTRS)

    Gray, V. H. (Inventor)

    1973-01-01

    A carrier liquid containing ablative material bodies is connected to a plenum chamber wall with openings to a high temperature environment. The liquid and bodies pass through the openings of the wall to form a self replacing ablative surface. The wall is composed of honeycomb layers, spheres containing ablative whiskers or wads, and a hardening catalyst for the carrier liquid. The wall also has woven wicks of ablative material fibers that extend through the wall openings and into plenum chamber which contains the liquid.

  9. Effectiveness of Integrating Delayed Computed Tomography Angiography Imaging for Left Atrial Appendage Thrombus Exclusion into the Care of Patients Undergoing Ablation of Atrial Fibrillation

    PubMed Central

    Bilchick, Kenneth C.; Mealor, Augustus; Gonzalez, Jorge; Norton, Patrick; Zhuo, David; Mason, Pamela; Ferguson, John D.; Malhotra, Rohit; Mangrum, J. Michael; Darby, Andrew E.; DiMarco, John; Hagspiel, Klaus; Dent, John; Kramer, Christopher M.; Stukenborg, George J.; Salerno, Michael

    2015-01-01

    Background Computed tomography angiography (CTA) can identify and rule out left atrial appendage (LAA) thrombus when delayed imaging is also performed. Objective In patients referred for CTA for pulmonary vein anatomy prior to ablation of atrial fibrillation or atypical left atrial flutter (AF), we sought to determine the effectiveness of a novel clinical protocol for integrating results of CTA delayed imaging of the LAA into pre-procedure care. Methods After making delayed imaging of the LAA part of our routine pre-ablation CTA protocol, we integrated early reporting of pre-ablation CTA LAA imaging results into clinical practice as part of a formal protocol in June 2013. We then analyzed the effectiveness of this protocol by evaluating 320 AF ablation patients with CTA imaging during 2012–2014. Results Among CTA patients with delayed LAA imaging, the sensitivity and negative predictive values for LAA thrombus with intracardiac echocardiography (ICE) or transesophageal echocardiograms (TEEs) as the reference standard were both 100%. ICE during ablation confirmed absence of thrombus in patients with a negative CTA or negative TEE. No patients with either a negative CTA or an equivocal CTA combined with a negative TEE had strokes or transient ischemic attacks. Overall, the need for TEEs decreased from 57.5% to 24.0% during the 3-year period as a result of the CTA protocol. Conclusions Clinical integration of CTA with delayed LAA imaging into the care of patients having catheter ablation of AF is feasible, safe, and effective. Such a protocol could be applied broadly to improve patient care. PMID:26341605

  10. Therapeutic stimulation versus ablation.

    PubMed

    Hariz, Marwan I; Hariz, Gun-Marie

    2013-01-01

    The renaissance of functional stereotactic neurosurgery was pioneered in the mid 1980s by Laitinen's introduction of Leksell's posteroventral pallidotomy for Parkinson´s disease (PD). This ablative procedure experienced a worldwide spread in the 1990s, owing to its excellent effect on dyskinesias and other symptoms of post-l-dopa PD. Modern deep brain stimulation (DBS), pioneered by Benabid and Pollak in 1987 for the treatment of tremor, first became popular when it was applied to the subthalamic nucleus (STN) in the mid 1990s, where it demonstrated a striking effect on all cardinal symptoms of advanced PD, and permitted reduced dosages of medication. DBS, as a nondestructive, adaptable, and reversible procedure that is proving safe in bilateral surgery on basal ganglia, has great appeal to clinicians and patients alike, despite the fact that it is expensive, laborious, and relies on very strict patient selection criteria, especially for STN DBS. Psychiatric surgery has experienced the same phenomenon, with DBS supplanting completely stereotactic ablative procedures. This chapter discusses the pros and cons of ablation versus stimulation and investigates the reasons why DBS has overshadowed proven efficient ablative procedures such as pallidotomy for PD, and capsulotomy and cingulotomy for obsessive-compulsive disorder and depression. PMID:24112885

  11. Atrial fibrillation ablation.

    PubMed

    Pappone, Carlo; Santinelli, Vincenzo

    2012-06-01

    Atrial fibrillation is the commonest cardiac arrhythmia, with significant morbidity related to symptoms, heart failure, and thromboembolism, which is associated with excess mortality. Over the past 10 years, many centers worldwide have reported high success rates and few complications after a single ablation procedure in patients with paroxysmal atrial fibrillation. Recent studies indicate a short-term and long-term superiority of catheter ablation as compared with conventional antiarrhythmic drug therapy in terms of arrhythmia recurrence, quality of life, and arrhythmia progression. As a result, catheter ablation is evolving to a front-line therapy in many patients with atrial fibrillation. However, in patients with persistent long-standing atrial fibrillation catheter ablation strategy is more complex and time-consuming, frequently requiring repeat procedures to achieve success rates as high as in paroxysmal atrial fibrillation. In the near future, however, with growing experience and evolving technology, catheter ablation of atrial fibrillation may be extended also to patients with long-standing atrial fibrillation. PMID:22541284

  12. Ablative thermal protection systems

    NASA Technical Reports Server (NTRS)

    Vaniman, J.; Fisher, R.; Wojciechowski, C.; Dean, W.

    1983-01-01

    The procedures used to establish the TPS (thermal protection system) design of the SRB (solid rocket booster) element of the Space Shuttle vehicle are discussed. A final evaluation of the adequacy of this design will be made from data obtained from the first five Shuttle flights. Temperature sensors installed at selected locations on the SRB structure covered by the TPS give information as a function of time throughout the flight. Anomalies are to be investigated and computer design thermal models adjusted if required. In addition, the actual TPS ablator material loss is to be measured after each flight and compared with analytically determined losses. The analytical methods of predicting ablator performance are surveyed.

  13. AFS controlling algorithm

    NASA Astrophysics Data System (ADS)

    Liu, Hong; Jiang, Lanfang; Wang, Gengjie; Wang, Li

    2008-12-01

    Adaptive front lighting system (i.e., AFS) is the development trend of lighting system of motor vehicles. AFS means that headlamp can adjust beam direction to get best illumination according to road condition and its bodywork. The paper discusses the AFS key techniques: establishing calculation formulae of vehicle body state concerned road condition and steering state. Because of sensor technology limitations, it only can deal with inclination and turn of vehicle body state by means of sensor's signals. This paper studies the relationship between inclination and turn of the body and lamp lighting on the base of relative standards, and gives out the calculation formulae for the body and lamp lighting adjustment, also discusses its dynamical properties. The study is basic work for lighting adjustment automatically.

  14. Tumour ablation: technical aspects

    PubMed Central

    Bodner, Gerd; Bale, Reto

    2009-01-01

    Abstract Image-guided percutaneous radiofrequency ablation (RFA) is a minimally invasive, relatively low-risk procedure for tumour treatment. Local recurrence and survival rates depend on the rate of complete ablation of the entire tumour including a sufficient margin of surrounding healthy tissue. Currently a variety of different RFA devices are available. The interventionalist must be able to predict the configuration and extent of the resulting ablation necrosis. Accurate planning and execution of RFA according to the size and geometry of the tumour is essential. In order to minimize complications, individualized treatment strategies may be necessary for tumours close to vital structures. This review examines the state-of-the art of different device technologies, approaches, and treatment strategies for percutaneous RFA of liver tumours. PMID:19965296

  15. Rotors as Drivers of Atrial Fibrillation and Targets for Ablation

    PubMed Central

    Schricker, Amir A.; Lalani, Gautam G.; Krummen, David E.

    2014-01-01

    Atrial fibrillation (AF) is the most common arrhythmia targeted by catheter ablation. Despite significant advances in our understanding of AF, ablation outcomes remain suboptimal, and this is due in large part to an incomplete understanding of the underlying sustaining mechanisms of AF. Recent developments of patient-tailored and physiology-based computational mapping systems have identified localized electrical spiral waves, or rotors, and focal sources as mechanisms that may represent novel targets for therapy. This report provides an overview of Focal Impulse and Rotor Modulation (FIRM) mapping, which reveals that human AF is often not actually driven by disorganized activity but instead that disorganization is secondary to organized rotors or focal sources. Targeted ablation of such sources alone can eliminate AF and, when added to pulmonary vein isolation, improves long-term outcome compared with conventional ablation alone. Translating mechanistic insights from such patient-tailored mapping is likely to be crucial in achieving the next major advances in personalized medicine for AF. PMID:24950671

  16. Atrial Tachycardias Arising from Ablation of Atrial Fibrillation: A Proarrhythmic Bump or an Antiarrhythmic Turn?

    PubMed Central

    Shah, Ashok J.; Jadidi, Amir; Liu, Xingpeng; Miyazaki, Shinsuke; Forclaz, Andrei; Nault, Isabelle; Rivard, Lena; Linton, Nick; Xhaet, Olivier; Derval, Nicolas; Sacher, Frederic; Bordachar, Pierre; Ritter, Philippe; Hocini, Meleze; Jais, Pierre; Haissaguerre, Michel

    2010-01-01

    The occurrence of atrial tachycardias (AT) is a direct function of the volume of atrial tissue ablated in the patients with atrial fibrillation (AF). Thus, the incidence of AT is highest in persistent AF patients undergoing stepwise ablation using the strategic combination of pulmonary vein isolation, electrogram based ablation and left atrial linear ablation. Using deductive mapping strategy, AT can be divided into three clinical categories viz. the macroreentry, the focal and the newly described localized reentry all of which are amenable to catheter ablation with success rate of 95%. Perimitral, roof dependent and cavotricuspid isthmus dependent AT involve large reentrant circuits which can be successfully ablated at the left mitral isthmus, left atrial roof and tricuspid isthmus respectively. Complete bidirectional block across the sites of linear ablation is a necessary endpoint. Focal and localized reentrant AT commonly originate from but are not limited to the septum, posteroinferior left atrium, venous ostia, base of the left atrial appendage and left mitral isthmus and they respond quickly to focal ablation. AT not only represents ablation-induced proarrhythmia but also forms a bridge between AF and sinus rhythm in longstanding AF patients treated successfully with catheter ablation. PMID:20379387

  17. Endometrial ablation

    MedlinePlus

    ... can be seen on the video screen. Small tools can be used through the scope to remove abnormal growths or tissue for examination. Ablation uses heat, cold, or electricity to destroy the lining of the womb. The ...

  18. Ablation article and method

    NASA Technical Reports Server (NTRS)

    Erickson, W. D.; Sullivan, E. M. (Inventor)

    1973-01-01

    An ablation article, such as a conical heat shield, having an ablating surface is provided with at least one discrete area of at least one seed material, such as aluminum. When subjected to ablation conditions, the seed material is ablated. Radiation emanating from the ablated seed material is detected to analyze ablation effects without disturbing the ablation surface. By providing different seed materials having different radiation characteristics, the ablating effects on various areas of the ablating surface can be analyzed under any prevailing ablation conditions. The ablating article can be provided with means for detecting the radiation characteristics of the ablated seed material to provide a self-contained analysis unit.

  19. Epicardial Ablation For Ventricular Tachycardia

    PubMed Central

    Maccabelli, Giuseppe; Mizuno, Hiroya; Della Bella, Paolo

    2012-01-01

    Epicardial ablation has lately become a necessary tool to approach some ventricular tachycardias in different types of cardiomyopathy. Its diffusion is now limited to a few high volume centers not because of the difficulty of the pericardial puncture but since it requires high competence not only in the VT ablation field but also in knowing and recognizing the possible complications each of which require a careful treatment. This article will review the state of the art of epicardial ablation with special attention to the procedural aspects and to the possible selection criteria of the patients PMID:23233758

  20. Radiofrequency catheter ablation in pediatric patients with supraventricular arrhythmias.

    PubMed

    Rhodes, L A; Lobban, J H; Schmidt, S B

    1995-01-01

    Radiofrequency (RF) ablation of foci leading to abnormal cardiac rhythms is rapidly becoming the procedure of choice in the management of arrhythmias in adults. This report reviews our initial experience with RF ablation in the pediatric population. PMID:8533398

  1. Atrial Fibrillation Ablation and Stroke.

    PubMed

    Aagaard, Philip; Briceno, David; Csanadi, Zoltan; Mohanty, Sanghamitra; Gianni, Carola; Trivedi, Chintan; Nagy-Baló, Edina; Danik, Stephan; Barrett, Conor; Santoro, Francesco; Burkhardt, J David; Sanchez, Javier; Natale, Andrea; Di Biase, Luigi

    2016-05-01

    Catheter ablation has become a widely available and accepted treatment to restore sinus rhythm in atrial fibrillation patients who fail antiarrhythmic drug therapy. Although generally safe, the procedure carries a non-negligible risk of complications, including periprocedural cerebral insults. Uninterrupted anticoagulation, maintenance of an adequate ACT during the procedure, and measures to avoid and detect thrombus build-up on sheaths and atheters during the procedure, appears useful to reduce the risk of embolic events. This is a review of the incidence, mechanisms, impact, and methods to reduce catheter ablation related cerebral insults. PMID:27150179

  2. Bone and Soft Tissue Ablation

    PubMed Central

    Foster, Ryan C.B.; Stavas, Joseph M.

    2014-01-01

    Bone and soft tissue tumor ablation has reached widespread acceptance in the locoregional treatment of various benign and malignant musculoskeletal (MSK) lesions. Many principles of ablation learned elsewhere in the body are easily adapted to the MSK system, particularly the various technical aspects of probe/antenna design, tumoricidal effects, selection of image guidance, and methods to reduce complications. Despite the common use of thermal and chemical ablation procedures in bone and soft tissues, there are few large clinical series that show longitudinal benefit and cost-effectiveness compared with conventional methods, namely, surgery, external beam radiation, and chemotherapy. Percutaneous radiofrequency ablation of osteoid osteomas has been evaluated the most and is considered a first-line treatment choice for many lesions. Palliation of painful metastatic bone disease with thermal ablation is considered safe and has been shown to reduce pain and analgesic use while improving quality of life for cancer patients. Procedure-related complications are rare and are typically easily managed. Similar to all interventional procedures, bone and soft tissue lesions require an integrated approach to disease management to determine the optimum type of and timing for ablation techniques within the context of the patient care plan. PMID:25053865

  3. Bone and soft tissue ablation.

    PubMed

    Foster, Ryan C B; Stavas, Joseph M

    2014-06-01

    Bone and soft tissue tumor ablation has reached widespread acceptance in the locoregional treatment of various benign and malignant musculoskeletal (MSK) lesions. Many principles of ablation learned elsewhere in the body are easily adapted to the MSK system, particularly the various technical aspects of probe/antenna design, tumoricidal effects, selection of image guidance, and methods to reduce complications. Despite the common use of thermal and chemical ablation procedures in bone and soft tissues, there are few large clinical series that show longitudinal benefit and cost-effectiveness compared with conventional methods, namely, surgery, external beam radiation, and chemotherapy. Percutaneous radiofrequency ablation of osteoid osteomas has been evaluated the most and is considered a first-line treatment choice for many lesions. Palliation of painful metastatic bone disease with thermal ablation is considered safe and has been shown to reduce pain and analgesic use while improving quality of life for cancer patients. Procedure-related complications are rare and are typically easily managed. Similar to all interventional procedures, bone and soft tissue lesions require an integrated approach to disease management to determine the optimum type of and timing for ablation techniques within the context of the patient care plan. PMID:25053865

  4. Thermal Ablation for Benign Thyroid Nodules: Radiofrequency and Laser

    PubMed Central

    Lee, Jeong Hyun; Valcavi, Roberto; Pacella, Claudio M.; Rhim, Hyunchul; Na, Dong Gyu

    2011-01-01

    Although ethanol ablation has been successfully used to treat cystic thyroid nodules, this procedure is less effective when the thyroid nodules are solid. Radiofrequency (RF) ablation, a newer procedure used to treat malignant liver tumors, has been valuable in the treatment of benign thyroid nodules regardless of the extent of the solid component. This article reviews the basic physics, techniques, applications, results, and complications of thyroid RF ablation, in comparison to laser ablation. PMID:21927553

  5. Sharp Potential in Cavo-tricuspid Isthmus Targeted during Typical Atrial Flutter Radiofrequency Ablation.

    PubMed

    Rey, Florian; Sunthorn, Henri

    2016-03-01

    The aim of this study was to define atrial electrograms (EGM) morphology, which could predict a conduction gap in cavo-tricuspid isthmus (CTI) during typical atrial flutter (AF) radiofrequency ablation. One hundred atrial EGM were retrospectively analysed. We demonstrated that recognising a sharp potential (short duration and high amplitude) is useful for quickly achieving CTI bi-directional block during typical AF ablation. PMID:26700023

  6. Reversal of pulmonary vein remodeling after catheter ablation of atrial fibrillation

    PubMed Central

    Wu, Jia-Hui; Li, Hung-Kei; Couri, Daniel M; Araoz, Philip A; Lee, Ying-Hsiang; Ma, Chang-Sheng; Packer, Douglas L; Cha, Yong-Mei

    2016-01-01

    Background Pulmonary veins (PV) and the atria undergo electrical and structural remodeling in atrial fibrillation (AF). This study aimed to determine PV and left atrial (LA) reverse remodeling after catheter ablation for AF assessed by chest computed tomography (CT). Methods PV electrophysiologic studies and catheter ablation were performed in 63 patients (68% male; mean ± SD age: 56 ± 10 years) with symptomatic AF (49% paroxysmal, 51% persistent). Chest CT was performed before and 3 months after catheter ablation. Results At baseline, patients with persistent AF had a greater LA volume (91 ± 29 cm3 vs. 66 ± 27 cm3; P = 0.003) and mean PV ostial area (241 ± 43 mm2 vs. 212 ± 47 mm2; P = 0.03) than patients with paroxysmal AF. There was no significant correlation between the effective refractory period and the area of the left superior PV ostium. At 3 months of follow-up after ablation, 48 patients (76%) were AF free on or off antiarrhythmic drugs. There was a significant reduction in LA volume (77 ± 31 cm3 to 70 ± 28 cm3; P < 0.001) and mean PV ostial area (224 ± 48 mm2 to 182 ± 43 mm2; P < 0.001). Patients with persistent AF had more reduction in LA volume (11.8 ± 12.8 cm3 vs. 4.0 ± 11.2 cm3; P = 0.04) and PV ostial area (62 mm2 vs. 34 mm2; P = 0.04) than those who have paroxysmal AF. The reduction of the averaged PV ostial area was significantly correlated with the reduction of LA volume (r = 0.38, P = 0.03). Conclusions Catheter ablation of AF improves structural remodeling of PV ostia and left atrium. This finding is more apparent in patients with persistent AF treated by catheter ablation. PMID:27168743

  7. Reduction of Iatrogenic Atrial Septal Defects with an Anterior and Inferior Transseptal Puncture Site when Operating the Cryoballoon Ablation Catheter.

    PubMed

    Rich, Michael E; Tseng, Andrew; Lim, Hae W; Wang, Paul J; Su, Wilber W

    2015-01-01

    The cryoballoon catheter ablates atrial fibrillation (AF) triggers in the left atrium (LA) and pulmonary veins (PVs) via transseptal access. The typical transseptal puncture site is the fossa ovalis (FO) - the atrial septum's thinnest section. A potentially beneficial transseptal site, for the cryoballoon, is near the inferior limbus (IL). This study examines an alternative transseptal site near the IL, which may decrease the frequency of acute iatrogenic atrial septal defect (IASD). Also, the study evaluates the acute pulmonary vein isolation (PVI) success rate utilizing the IL location. 200 patients were evaluated by retrospective chart review for acute PVI success rate with an IL transseptal site. An additional 128 IL transseptal patients were compared to 45 FO transseptal patients by performing Doppler intracardiac echocardiography (ICE) post-ablation to assess transseptal flow after removal of the transseptal sheath. After sheath removal and by Doppler ICE imaging, 42 of 128 (33%) IL transseptal patients demonstrated acute transseptal flow, while 45 of 45 (100%) FO transseptal puncture patients had acute transseptal flow. The difference in acute transseptal flow detection between FO and IL sites was statistically significant (P <0.0001). Furthermore, 186 of 200 patients (with an IL transseptal puncture) did not need additional ablation(s) and had achieved an acute PVI by a "cryoballoon only" technique. An IL transseptal puncture site for cryoballoon AF ablations is an effective location to mediate PVI at all four PVs. Additionally, an IL transseptal location can lower the incidence of acute transseptal flow by Doppler ICE when compared to the FO. Potentially, the IL transseptal site may reduce later IASD complications post-cryoballoon procedures. PMID:26132435

  8. [Percutaneous ablation of renal tumors: radiofrequency ablation or cryoablation?].

    PubMed

    Buy, X; Lang, H; Garnon, J; Gangi, A

    2011-09-01

    Percutaneous ablation of renal tumors, including radiofrequency ablation and cryoablation, are increasingly being used for small tumors as an alternative to surgery for poor surgical candidates. Compared to radiofrequency ablation, cryoablation has several advantages: improved volume control and preservation of adjacent structures due to the excellent depiction of the ice ball on CT and MRI; better protection of the collecting system for central tumor with reduced risk of postprocedural urinary fistula. The main pitfall of cryoablation is the higher cost. Therefore, cryoablation should be reserved for the treatment of complex tumors. In this article, we will review the different steps of percutaneous renal tumor ablation procedures including patient selection, technical considerations, and follow-up imaging. PMID:21944236

  9. Phrenic Nerve Injury After Catheter Ablation of Atrial Fibrillation

    PubMed Central

    Sacher, Frederic; Jais, Pierre; Stephenson, Kent; O'Neill, Mark D; Hocini, Meleze; Clementy, Jacques; Stevenson, William G; Haissaguerre, Michel

    2007-01-01

    Phrenic Nerve Injury (PNI) has been well studied by cardiac surgeons. More recently it has been recognized as a potential complication of catheter ablation with a prevalence of 0.11 to 0.48 % after atrial fibrillation (AF) ablation. This review will focus on PNI after AF ablation Anatomical studies have shown a close relationship between the right phrenic nerve and it's proximity to the superior vena cava (SVC), and the antero-inferior part of the right superior pulmonary vein (RSPV). In addition, the proximity of the left phrenic nerve to the left atrial appendage has been well established. Independent of the type of ablation catheter (4mm, 8 mm, irrigated tip, balloon) or energy source used (radiofrequency (RF), ultrasound, cryothermia, and laser); the risk of PNI exists during ablation at the critical areas listed above. Although up to thirty-one percent of patients with PNI after AF ablation remain asymptomatic, dyspnea remain the cardinal symptom and is present in all symptomatic patients. Despite the theoretical risk for significant adverse effect on functional status and quality of life, short-term outcomes from published studies appear favorable with 81% of patients with PNI having a complete recovery after 7 ± 7 months. Conclusion Existing studies have described PNI as an uncommon but avoidable complication in patients undergoing pulmonary vein isolation for AF. Prior to ablation at the SVC, antero-inferior RSPV ostium or the left atrial appendage, pacing should be performed before energy delivery. If phrenic nerve capture is documented, energy delivery should be avoided at this site. Electrophysiologist's vigilance as well as pacing prior to ablation at high risk sites in close proximity to the phrenic nerve are the currently available tools to avoid the complication of PNI. PMID:17235367

  10. FBG Sensor for Contact Level Monitoring and Prediction of Perforation in Cardiac Ablation

    PubMed Central

    Ho, Siu Chun Michael; Razavi, Mehdi; Nazeri, Alireza; Song, Gangbing

    2012-01-01

    Atrial fibrillation (AF) is the most common type of arrhythmia, and is characterized by a disordered contractile activity of the atria (top chambers of the heart). A popular treatment for AF is radiofrequency (RF) ablation. In about 2.4% of cardiac RF ablation procedures, the catheter is accidently pushed through the heart wall due to the application of excessive force. Despite the various capabilities of currently available technology, there has yet to be any data establishing how cardiac perforation can be reliably predicted. Thus, two new FBG based sensor prototypes were developed to monitor contact levels and predict perforation. Two live sheep were utilized during the study. It was observed during operation that peaks appeared in rhythm with the heart rate whenever firm contact was made between the sensor and the endocardial wall. The magnitude of these peaks varied with pressure applied by the operator. Lastly, transmural perforation of the left atrial wall was characterized by a visible loading phase and a rapid signal drop-off correlating to perforation. A possible pre-perforation signal was observed for the epoxy-based sensor in the form of a slight signal reversal (12–26% of loading phase magnitude) prior to perforation (occurring over 8 s). PMID:22368507

  11. FBG sensor for contact level monitoring and prediction of perforation in cardiac ablation.

    PubMed

    Ho, Siu Chun Michael; Razavi, Mehdi; Nazeri, Alireza; Song, Gangbing

    2012-01-01

    Atrial fibrillation (AF) is the most common type of arrhythmia, and is characterized by a disordered contractile activity of the atria (top chambers of the heart). A popular treatment for AF is radiofrequency (RF) ablation. In about 2.4% of cardiac RF ablation procedures, the catheter is accidently pushed through the heart wall due to the application of excessive force. Despite the various capabilities of currently available technology, there has yet to be any data establishing how cardiac perforation can be reliably predicted. Thus, two new FBG based sensor prototypes were developed to monitor contact levels and predict perforation. Two live sheep were utilized during the study. It was observed during operation that peaks appeared in rhythm with the heart rate whenever firm contact was made between the sensor and the endocardial wall. The magnitude of these peaks varied with pressure applied by the operator. Lastly, transmural perforation of the left atrial wall was characterized by a visible loading phase and a rapid signal drop-off correlating to perforation. A possible pre-perforation signal was observed for the epoxy-based sensor in the form of a slight signal reversal (12-26% of loading phase magnitude) prior to perforation (occurring over 8 s). PMID:22368507

  12. Cryoballoon Ablation for Atrial Fibrillation

    PubMed Central

    Andrade, Jason G; Dubuc, Marc; Guerra, Peter G; Macle, Laurent; Rivard, Lena; Roy, Denis; Talajic, Mario; Thibault, Bernard; Khairy, Paul

    2012-01-01

    Focal point-by-point radiofrequency catheter ablation has shown considerable success in the treatment of paroxysmal atrial fibrillation. However, it is not without limitations. Recent clinical and preclinical studies have demonstrated that cryothermal ablation using a balloon catheter (Artic Front©, Medtronic CryoCath LP) provides an effective alternative strategy to treating atrial fibrillation. The objective of this article is to review efficacy and safety data surrounding cryoballoon ablation for paroxysmal and persistent atrial fibrillation. In addition, a practical step-by-step approach to cryoballoon ablation is presented, while highlighting relevant literature regarding: 1) the rationale for adjunctive imaging, 2) selection of an appropriate cryoballoon size, 3) predictors of efficacy, 4) advanced trouble-shooting techniques, and 5) strategies to reduce procedural complications, such as phrenic nerve palsy. PMID:22557842

  13. The Cox-maze IV procedure for lone atrial fibrillation: a single center experience in 100 consecutive patients

    PubMed Central

    Weimar, Timo; Bailey, Marci S.; Watanabe, Yoshiyuki; Marin, Donna; Maniar, Hersh S.; Schuessler, Richard B.

    2015-01-01

    Purpose The Cox-maze III procedure (CMP) has achieved high success rates for the surgical treatment of atrial fibrillation (AF). In 2002, our group introduced a simplified CMP, in which most incisions were replaced with linear lines of ablation using bipolar radiofrequency and cryoenergy. This operation, termed the CMP-IV, has significantly shortened operative times and allowed for a minimally invasive approach. This report evaluates our results in 100 consecutive patients undergoing a stand-alone CMP-IV. Methods Data were collected prospectively on 100 patients (mean age, 56±10 years) who underwent a CMP-IV from January 2002 through May 2010. All patients were available for follow-up with a mean follow-up of 17±10 months. Electrocardiograms or 24-h Holter monitorings were obtained at 6, 12, and 24 months. Data were analyzed using a longitudinal database containing over 380 variables. Results Thirty-one percent of patients had paroxysmal AF, with the remainder having persistent (6%) or longstanding persistent AF (63%). The mean preoperative duration of AF was 7.4±6.7 years. The mean left atrial diameter was 4.7±1.1 cm. In this group, 40 patients had failed with a mean of 2.6±1.3 catheter ablations. Mean aortic cross-clamp time was 41±13 min. There was one postoperative mortality. Postoperative freedom from AF was 93%, 90%, and 90% at 6, 12, and 24 months, respectively. Freedom from AF off antiarrhythmic medication was 82%, 82%, and 84% at 6, 12, and 24 months, respectively. Conclusion The less invasive CMP-IV has a high single procedure success rate, even with improved follow-up and stricter definitions of failure. PMID:21340516

  14. Left atrial reservoir function predicts atrial fibrillation recurrence after catheter ablation: a two-dimensional speckle strain study

    PubMed Central

    Mirza, Mahek; Caracciolo, Giuseppe; Khan, Uzma; Mori, Naoyo; Saha, Samir K.; Srivathsan, Komandoor; Altemose, Gregory; Scott, Luis; Sengupta, Partho

    2011-01-01

    Background Predictors of atrial fibrillation (AF) recurrence after catheter ablation (CA) are not fully defined. We hypothesized that 2D left atrial (LA) regional strain maps would help identify abnormal atrial substrate that increases susceptibility to AF recurrence post-CA. Methods and Results Sixty-three patients (63±10 years, 60% male) underwent CA for symptomatic paroxysmal (75%) or persistent (25%) AF. Baseline LA mechanical function determined using speckle tracking echocardiography was compared between those with AF recurrence (AFR) and no recurrence post-CA. Bi-dimensional global and regional maps of LA wall velocity, strain, and strain rate (SR) were obtained during end ejection and early diastole. After 18±12 months of follow-up, 34 patients were free of AFR post-CA. There were no differences in clinical characteristics, LA and LV volumes, and Doppler estimates of LV diastolic function and filling pressures at baseline between patients with recurrent AF and those that maintained sinus rhythm. However, the LA emptying fraction (55±17% vs. 64±14%, p=0.04), global and regional systolic and diastolic strains, SR, and velocities were reduced in patients with recurrent AF. There was marked attenuation of peak LA lateral wall longitudinal strain (LS; 11±7% vs. 20±14%, p=0.007) and SR (0.9±0.4 vs. 1.3±0.6 s−1, p=0.01). Multivariate analysis revealed lateral wall LS (odds ratio=1.15, 95% CI=1.02–1.28, p=0.01) as an independent predictor of AFR. Conclusions Regional LA lateral wall LS is a pre-procedural determinant of AFR in patients undergoing CA, independent of LA enlargement. Characterization of atrial myocardial tissue properties by speckle tracking echo may aid the appropriate selection of adjunctive strategies and prognostication of patients undergoing CA. PMID:21424845

  15. Design, development, and evaluation of focused ultrasound arrays for transesophageal cardiac ablations

    NASA Astrophysics Data System (ADS)

    Lee, Hotaik

    The ultimate purpose of this dissertation is the evaluation of the feasibility of transesophageal cardiac surgery in arrhythmia treatment, using therapeutic ultrasound energy without the requirement for surgical incisions or blood contact. Atrial fibrillation (AF) is the most common cardiac arrhythmia, affecting over 2.2 million Americans. One effective treatment is cardiac ablation, which shows a high rate of success in treating paroxysmal AF. As a prevailing modality for this treatment, catheter ablation using radiofrequency has been effective, but there is measurable morbidity and significant costs and time associated with this invasive procedure for permanent or persistent AF. To address these issues, a transesophageal ultrasound applicator for noninvasive cardiac ablations has been designed, developed and evaluated in this dissertation. Focused ultrasound for thermal ablation has gained interest for decades due to its noninvasive characteristics. Since the esophagus is close to the posterior of the left atrium, its position makes it attractive for the incision-less surgery of the selected area of the heart using ultrasound. The overall goal of this study is to bring an applicator as closely as possible to the heart in order to effectively deliver ultrasound energy, and create electrically isolating lesions in myocardial tissue, replicating the currently used Maze procedure. The Maze procedure is a surgical operation that treats AF by creating a grid of incisions resulting in non-conductive scar tissue in the atria. The initial design of an ultrasound applicator capable of creating atrial lesions from the esophagus, involved evaluating sound pressure fields within layers of the esophagus and myocardium. Based on the multiple factors of the simulation results of transducer arrays, current transesophageal medical devices, and the throat anatomy, a focused ultrasound transducer that can be inserted into the esophagus has been designed and tested. In this study, a

  16. Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?

    NASA Astrophysics Data System (ADS)

    Wu, Po-hung; Brace, Chris L.

    2016-08-01

    Intra-procedural contrast-enhanced CT (CECT) has been proposed to evaluate treatment efficacy of thermal ablation. We hypothesized that contrast material delivered concurrently with thermal ablation may become trapped in the ablation zone, and set out to determine whether such an effect would impact ablation visualization. CECT images were acquired during microwave ablation in normal porcine liver with: (A) normal blood perfusion and no iodinated contrast, (B) normal perfusion and iodinated contrast infusion or (C) no blood perfusion and residual iodinated contrast. Changes in CT attenuation were analyzed from before, during and after ablation to evaluate whether contrast was trapped inside of the ablation zone. Visualization was compared between groups using post-ablation contrast-to-noise ratio (CNR). Attenuation gradients were calculated at the ablation boundary and background to quantitate ablation conspicuity. In Group A, attenuation decreased during ablation due to thermal expansion of tissue water and water vaporization. The ablation zone was difficult to visualize (CNR  =  1.57  ±  0.73, boundary gradient  =  0.7  ±  0.4 HU mm‑1), leading to ablation diameter underestimation compared to gross pathology. Group B ablations saw attenuation increase, suggesting that iodine was trapped inside the ablation zone. However, because the normally perfused liver increased even more, Group B ablations were more visible than Group A (CNR  =  2.04  ±  0.84, boundary gradient  =  6.3  ±  1.1 HU mm‑1) and allowed accurate estimation of the ablation zone dimensions compared to gross pathology. Substantial water vaporization led to substantial attenuation changes in Group C, though the ablation zone boundary was not highly visible (boundary gradient  =  3.9  ±  1.1 HU mm‑1). Our results demonstrate that despite iodinated contrast being trapped in the ablation zone, ablation visibility

  17. Analysis of iodinated contrast delivered during thermal ablation: is material trapped in the ablation zone?

    PubMed

    Wu, Po-Hung; Brace, Chris L

    2016-08-21

    Intra-procedural contrast-enhanced CT (CECT) has been proposed to evaluate treatment efficacy of thermal ablation. We hypothesized that contrast material delivered concurrently with thermal ablation may become trapped in the ablation zone, and set out to determine whether such an effect would impact ablation visualization. CECT images were acquired during microwave ablation in normal porcine liver with: (A) normal blood perfusion and no iodinated contrast, (B) normal perfusion and iodinated contrast infusion or (C) no blood perfusion and residual iodinated contrast. Changes in CT attenuation were analyzed from before, during and after ablation to evaluate whether contrast was trapped inside of the ablation zone. Visualization was compared between groups using post-ablation contrast-to-noise ratio (CNR). Attenuation gradients were calculated at the ablation boundary and background to quantitate ablation conspicuity. In Group A, attenuation decreased during ablation due to thermal expansion of tissue water and water vaporization. The ablation zone was difficult to visualize (CNR  =  1.57  ±  0.73, boundary gradient  =  0.7  ±  0.4 HU mm(-1)), leading to ablation diameter underestimation compared to gross pathology. Group B ablations saw attenuation increase, suggesting that iodine was trapped inside the ablation zone. However, because the normally perfused liver increased even more, Group B ablations were more visible than Group A (CNR  =  2.04  ±  0.84, boundary gradient  =  6.3  ±  1.1 HU mm(-1)) and allowed accurate estimation of the ablation zone dimensions compared to gross pathology. Substantial water vaporization led to substantial attenuation changes in Group C, though the ablation zone boundary was not highly visible (boundary gradient  =  3.9  ±  1.1 HU mm(-1)). Our results demonstrate that despite iodinated contrast being trapped in the ablation zone, ablation visibility

  18. Atrial Fibrillation Ablation without Interruption of Anticoagulation.

    PubMed

    Santangeli, Pasquale; Di Biase, Luigi; Sanchez, Javier E; Horton, Rodney; Natale, Andrea

    2011-01-01

    Atrial fibrillation (AF) can be cured by pulmonary vein antrum isolation (PVAI) in a substantial proportion of patients. The high efficacy of PVAI is partially undermined by a small but concrete periprocedural risk of complications, such as thromboembolic events and bleeding. A correct management of anticoagulation is essential to prevent such complications. Performing PVAI without interruption of oral anticoagulation has been demonstrated feasible by our group in previous studies. Recently, we reported that continuation of therapeutic warfarin during radiofrequency catheter ablation consistently reduces the risk of periprocedural stroke/transient ischemic attack without increasing the risk of hemorrhagic events. Of note, interrupting warfarin anticoagulation may actually increase the risk of stroke even when bridged with heparin. The latter strategy is also associated with an increased risk of minor bleeding. With regard to major bleeding, we found no significant difference between patients with a therapeutic INR and those who were bridged with heparin. Therefore, continuation of therapeutic warfarin during ablation of AF appears to be the best anticoagulation strategy. In this paper we summarize our experience with AF ablation without interruption of anticoagulation. PMID:21577267

  19. First Case of Automatic His Potential Detection With a Novel Ultra High-density Electroanatomical Mapping System for AV Nodal Ablation

    PubMed Central

    Hilbert, Sebastian; Kosiuk, Jedrzej; John, Silke; Hindricks, Gerhard; Bollmann, Andreas

    2016-01-01

    A 74-year old was considered for atrioventricular (AV) nodal ablation in view of atrial fibrillation (AF) with poorly controlled ventricular rate despite being on amiodarone. Targeted AV nodal ablation was successfully performed after identifying the target site for ablation by reviewing an ultra high-density map of the His region produced by automatic electrogram annotation. PMID:25852249

  20. Radiofrequency Catheter Ablation for Atrial Fibrillation Elicited "Jackhammer Esophagus": A New Complication Due to Vagal Nerve Stimulation?

    PubMed

    Tolone, Salvatore; Savarino, Edoardo; Docimo, Ludovico

    2015-10-01

    Radiofrequency catheter ablation (RFCA) is a potentially curative method for treatment of highly symptomatic and drug-refractory atrial fibrillation (AF). However, this technique can provoke esophageal and nerve lesion, due to thermal injury. To our knowledge, there have been no reported cases of a newly described motor disorder, the Jackhammer esophagus (JE) after RFCA, independently of GERD. We report a case of JE diagnosed by high-resolution manometry (HRM), in whom esophageal symptoms developed 2 weeks after RFCA, in absence of objective evidence of GERD. A 65-year-old male with highly symptomatic, drug-refractory paroxysmal AF was candidate to complete electrical pulmonary vein isolation with RFCA. Prior the procedure, the patient underwent HRM and impedance-pH to rule out GERD or hiatal hernia presence. All HRM parameters, according to Chicago classification, were within normal limits. No significant gastroesophageal reflux was documented at impedance pH monitoring. Patient underwent RFCA with electrical disconnection of pulmonary vein. After two weeks, patient started to complain of dysphagia for solids, with acute chest-pain. The patient repeated HRM and impedance-pH monitoring 8 weeks after RFCA. HRM showed in all liquid swallows the typical spastic hypercontractile contractions consistent with the diagnosis of JE, whereas impedance-pH monitoring resulted again negative for GERD. Esophageal dysmotility can represent a possible complication of RFCA for AF, probably due to a vagal nerve injury, and dysphagia appearance after this procedure must be timely investigated by HRM. PMID:26351090

  1. Radiofrequency Catheter Ablation for Atrial Fibrillation Elicited “Jackhammer Esophagus”: A New Complication Due to Vagal Nerve Stimulation?

    PubMed Central

    Tolone, Salvatore; Savarino, Edoardo; Docimo, Ludovico

    2015-01-01

    Radiofrequency catheter ablation (RFCA) is a potentially curative method for treatment of highly symptomatic and drug-refractory atrial fibrillation (AF). However, this technique can provoke esophageal and nerve lesion, due to thermal injury. To our knowledge, there have been no reported cases of a newly described motor disorder, the Jackhammer esophagus (JE) after RFCA, independently of GERD. We report a case of JE diagnosed by high-resolution manometry (HRM), in whom esophageal symptoms developed 2 weeks after RFCA, in absence of objective evidence of GERD. A 65-year-old male with highly symptomatic, drug-refractory paroxysmal AF was candidate to complete electrical pulmonary vein isolation with RFCA. Prior the procedure, the patient underwent HRM and impedance-pH to rule out GERD or hiatal hernia presence. All HRM parameters, according to Chicago classification, were within normal limits. No significant gastroesophageal reflux was documented at impedance pH monitoring. Patient underwent RFCA with electrical disconnection of pulmonary vein. After two weeks, patient started to complain of dysphagia for solids, with acute chest-pain. The patient repeated HRM and impedance-pH monitoring 8 weeks after RFCA. HRM showed in all liquid swallows the typical spastic hypercontractile contractions consistent with the diagnosis of JE, whereas impedance-pH monitoring resulted again negative for GERD. Esophageal dysmotility can represent a possible complication of RFCA for AF, probably due to a vagal nerve injury, and dysphagia appearance after this procedure must be timely investigated by HRM. PMID:26351090

  2. Novel P Wave Indices to Predict Atrial Fibrillation Recurrence After Radiofrequency Ablation for Paroxysmal Atrial Fibrillation.

    PubMed

    Hu, Xiaoliang; Jiang, Jingzhou; Ma, Yuedong; Tang, Anli

    2016-01-01

    BACKGROUND Circumferential pulmonary vein isolation (CPVI) is a widely used treatment for paroxysmal atrial fibrillation (AF). Several P wave duration (PWD) parameters have been suggested to predict post-ablation recurrence, but their use remains controversial. This study aimed to identify novel P wave indices that predict post-ablation AF recurrence. MATERIAL AND METHODS We selected 171 consecutive patients undergoing CPVI for paroxysmal AF. Electrocardiography (ECG) recordings were obtained at the beginning and the end of ablation. PWD was measured in all 12 leads. The PWD variation was calculated by subtracting the pre-ablation PWD from the post-ablation PWD. RESULTS PWD was significantly shortened in leads II, III, aVF, and V1 after ablation. During a mean follow-up of 19.96±4.32 months, AF recurrence occurred in 32 (18.7%) patients. No significant differences in baseline characteristics or pre- or post-ablation PWD were observed between the AF recurrence and non-recurrence groups. Patients with AF recurrence exhibited a smaller PWD variation in leads II (1.21(-0.56, 2.40) vs. -5.77(-9.10, -4.06) ms, P<0.001), III (-5.92(-9.87, 3.27) vs. -9.44(-11.89, -5.57) ms, P=0.001) and V1 (-4.43(-6.64, -3.13) vs. -6.33(-8.19,-4.59) ms, P=0.003). Multivariable logistic regression analysis demonstrated that smaller PWD variations in lead II and III were independent risk factors for AF recurrence. PWD variation ≥-2.21 ms in lead II displayed the highest combined sensitivity and specificity (85.29% and 83.94%, respectively) for predicting post-ablation AF recurrence. A PWD variation ≥0 ms displayed the best practical value in predicting AF recurrence. CONCLUSIONS PWD variation in lead II is an effective predictor of post-ablation AF recurrence. PMID:27450644

  3. Novel P Wave Indices to Predict Atrial Fibrillation Recurrence After Radiofrequency Ablation for Paroxysmal Atrial Fibrillation

    PubMed Central

    Hu, Xiaoliang; Jiang, Jingzhou; Ma, Yuedong; Tang, Anli

    2016-01-01

    Background Circumferential pulmonary vein isolation (CPVI) is a widely used treatment for paroxysmal atrial fibrillation (AF). Several P wave duration (PWD) parameters have been suggested to predict post-ablation recurrence, but their use remains controversial. This study aimed to identify novel P wave indices that predict post-ablation AF recurrence. Material/Methods We selected 171 consecutive patients undergoing CPVI for paroxysmal AF. Electrocardiography (ECG) recordings were obtained at the beginning and the end of ablation. PWD was measured in all 12 leads. The PWD variation was calculated by subtracting the pre-ablation PWD from the post-ablation PWD. Results PWD was significantly shortened in leads II, III, aVF, and V1 after ablation. During a mean follow-up of 19.96±4.32 months, AF recurrence occurred in 32 (18.7%) patients. No significant differences in baseline characteristics or pre- or post-ablation PWD were observed between the AF recurrence and non-recurrence groups. Patients with AF recurrence exhibited a smaller PWD variation in leads II (1.21(−0.56, 2.40) vs. −5.77(−9.10, −4.06) ms, P<0.001), III (−5.92(−9.87, 3.27) vs. −9.44(−11.89, −5.57) ms, P=0.001) and V1 (−4.43(−6.64, −3.13) vs. −6.33(−8.19,−4.59) ms, P=0.003). Multivariable logistic regression analysis demonstrated that smaller PWD variations in lead II and III were independent risk factors for AF recurrence. PWD variation ≥−2.21 ms in lead II displayed the highest combined sensitivity and specificity (85.29% and 83.94%, respectively) for predicting post-ablation AF recurrence. A PWD variation ≥0 ms displayed the best practical value in predicting AF recurrence. Conclusions PWD variation in lead II is an effective predictor of post-ablation AF recurrence. PMID:27450644

  4. Surgical Ablation of Atrial Fibrillation.

    PubMed

    Ramlawi, Basel; Abu Saleh, Walid K

    2015-01-01

    The Cox-maze procedure for the restoration of normal sinus rhythm, initially developed by Dr. James Cox, underwent several iterations over the years. The main concept consists of creating a series of transmural lesions in the right and left atria that disrupt re-entrant circuits responsible for propagating the abnormal atrial fibrillation rhythm. The left atrial appendage is excluded as a component of the Maze procedure. For the first three iterations of the Cox- maze procedure, these lesions were performed using a surgical cut-and-sew approach that ensured transmurality. The Cox-Maze IV is the most currently accepted iteration. It achieves the same lesion set of the Cox- maze III but uses alternative energy sources to create the transmural lesions, potentially in a minimally invasive approach on the beating heart. High-frequency ultrasound, microwave, and laser energy have all been used with varying success in the past. Today, bipolar radiofrequency heat or cryotherapy cooling are the most accepted sources for creating linear lesions with consistent safety and transmurality. The robust and reliable nature of these energy delivery methods has yielded a success rate reaching 90% freedom from atrial fibrillation at 12 months. Such approaches offer a significant long-term advantage over catheter-based ablation, especially in patients having longstanding, persistent atrial fibrillation with characteristics such as dilated left atrial dimensions, poor ejection fraction, and failed catheter ablation. Based on these improved results, there currently is significant interest in developing a hybrid ablation strategy that incorporates the superior transmural robust lesions of surgical ablation, the reliable stroke prevention potential of epicardial left atrial appendage exclusion, and sophisticated mapping and confirmatory catheter-based ablation technology. Such a minimally invasive hybrid strategy for ablation may lead to the development of multidisciplinary "Afib teams" to

  5. High-intensity focused ultrasound ablation for the treatment of colorectal liver metastases during an open procedure: study on the pig

    PubMed Central

    Parmentier, Hubert; Melodelima, David; N'Djin, William Apoutou; Chesnais, Sabrina; Chapelon, Jean Yves; Rivoire, Michel

    2009-01-01

    Objective : To demonstrate in a porcine model that high intensity focused ultrasound (HIFU) with toroidshaped emitters may have a role in treating unresectable colorectal liver metastases. Summary Background Data : Surgical resection is the only curative option for colorectal hepatic metastases. Only 20% of patients are suitable for surgery. Many ablative techniques have been assessed but several limitations have been documented: traumatic puncture of the parenchyma, limited size of lesions and inability to monitor the treatment in real time. Methods : A HIFU device with 256 toroid-shaped emitters and integrated ultrasound imaging probe was used. Single lesions, induced in 40 seconds, and juxtaposition of 6 single lesions were created under ultrasound guidance on 13 pigs. The lesions were studied on sonograms, macroscopically and microscopically up to 30 days after the treatment. Results : Ninety percent of the HIFU lesions were immediately hypoechoic on ultrasound imaging. The average coagulated volume obtained from a 40 s total exposure in the liver was 7.0 ± 2.5 cm3 (1.5 – 20.0), average diameter: 19.5 ± 3.8 mm (10.0 – 29.0). Using the real-time visualisation of the treated region, single lesions were easily juxtaposed in order to produce larger lesions up to 6 cm in diameter without any major complication. Conclusions : This toroid HIFU device allows short treatment times, non-invasiveness regarding the liver and real time ultrasound guidance. It appears to be simpler and more reliable to use than current ablative methods. Additionally, lesions through large vessels (up to 5 mm) being feasible, treatment of some juxta-vascular metastases should be possible. PMID:19106688

  6. A rare complication of radiofrequency ablation: skin burn.

    PubMed

    Ertuğrul, İlker; Karagöz, Tevfik; Aykan, Hayrettin H

    2015-10-01

    Radiofrequency ablation is the first-line treatment for arrhythmias with high success and low complication rates. Skin burns have been reported rarely after electrophysiological procedures, especially procedures in which higher-power energy is used and multiple ablations are performed. Here, we report a case of skin burn that developed after radiofrequency ablation for ventricular tachycardia originating from the right ventricular outflow tract. PMID:25613639

  7. Catheter ablation of persistent atrial fibrillation: The importance of substrate modification

    PubMed Central

    Letsas, Konstantinos P; Efremidis, Michael; Sgouros, Nikolaos P; Vlachos, Konstantinos; Asvestas, Dimitrios; Sideris, Antonios

    2015-01-01

    Accumulating data have shown that elimination of atrial fibrillation (AF) sources should be the goal in persistent AF ablation. Pulmonary vein isolation, linear lesions and complex fractionated atrial electrograms (CFAEs) ablation have shown limited efficacy in patients with persistent AF. A combined approach using voltage, CFAEs and dominant frequency (DF) mapping may be helpful for the identification of AF sources and subsequent focal substrate modification. The fibrillatory activity is maintained by intramural reentry centered on fibrotic patches. Voltage mapping may assist in the identification of fibrotic areas. Stable rotors display the higher DF and possibly drive AF. Furthermore, the single rotor is usually consistent with organized AF electrograms without fractionation. It is therefore quite possible that rotors are located at relatively “healthy islands” within the patchy fibrosis. This is supported by the fact that high DF sites have been negatively correlated to the amount of fibrosis. CFAEs are located in areas adjacent to high DF. In conclusion, patchy fibrotic areas displaying the maximum DF along with high organization index and the lower fractionation index are potential targets of ablation. Prospective studies are required to validate the efficacy of substrate modification in left atrial ablation outcomes. PMID:25810810

  8. Lung Cancer Ablation: Technologies and Techniques

    PubMed Central

    Alexander, Erica S.; Dupuy, Damian E.

    2013-01-01

    The incidence of lung cancers in 2012 is estimated to reach 226,160 new cases, with only a third of patients suitable surgical candidates. Tumor ablation has emerged as an important and efficacious treatment option for nonsurgical lung cancer patients. This localized minimally invasive therapy is best suited for small oligonodular lesions or favorably located metastatic tumors. Radiofrequency ablation has been in use for over a decade, and newer modalities including microwave ablation, cryoablation, and irreversible electroporation have emerged as additional treatment options for patients. Ablation therapies can offer patients and clinicians a repeatable and effective therapy for palliation and, in some cases, cure of thoracic malignancies. This article discusses the available technologies and techniques available for tumor ablation of thoracic malignancies including patient selection, basic aspects of procedure technique, imaging follow-up, treatment outcomes, and comparisons between various therapies. PMID:24436530

  9. Epicardial Ventricular Tachycardia Ablation for Which Patients?

    PubMed Central

    Roten, Laurent; Sacher, Frédéric; Daly, Matthew; Pascale, Patrizio; Komatsu, Yuki; Ramoul, Khaled; Scherr, Daniel; Chaumeil, Arnaud; Shah, Ashok; Denis, Arnaud; Derval, Nicolas; Hocini, Mélèze; Haïssaguerre, Michel; Jaïs, Pierre

    2012-01-01

    With the widespread use of implantable cardioverter-defibrillators, an increasing number of patients present with ventricular tachycardia (VT). Large multicentre studies have shown that ablation of VT successfully reduces recurrent VT and this procedure is being performed by an increasing number of centres. However, for a number of reasons, many patients experience VT recurrence after ablation. One important reason for VT recurrence is the presence of an epicardial substrate involved in the VT circuit which is not affected by endocardial ablation. Epicardial access and ablation is now frequently performed either after failed endocardial VT ablation or as first-line treatment in selected patients. This review will focus on the available evidence for identifying VT of epicardial origin, and discuss in which patients an epicardial approach would be benefitial. PMID:26835028

  10. Pathophysiologic basis of autonomic ganglionated plexus ablation in patients with atrial fibrillation.

    PubMed

    Nakagawa, Hiroshi; Scherlag, Benjamin J; Patterson, Eugene; Ikeda, Atsuhsi; Lockwood, Deborah; Jackman, Warren M

    2009-12-01

    The intrinsic cardiac autonomic nervous system (ganglionated plexuses [GP]) plays a significant role in the initiation and maintenance of atrial fibrillation (AF) in both experimental models and AF patients. Left atrial GP, located in epicardial fat pads and the ligament of Marshall, contain afferent neurons from the atrial myocardium and the central autonomic nervous system, efferent neurons (cholinergic and adrenergic neurons), and interconnecting neurons, which allow communication between GP. Stimulation of the GP produces both parasympathetic stimulation (markedly shortens action potential duration) and sympathetic stimulation (increases calcium transient) in the pulmonary vein (PV) myocardium and atrial myocardium. In a canine model, GP stimulation resulted in early afterdepolarizations, and calcium transient triggered firing in the adjacent PV and initiated AF. Fractionated atrial potentials (FAP) were consistently located in the left atrium close to the stimulated GP. Ablation of the stimulated GP eliminated the FAP surrounding the GP. In patients with paroxysmal AF, epicardial and endocardial high-frequency stimulation produced a positive vagal response (transient AV block during AF and hypotension), allowing the identification and localization of five major left atrial GP (superior left GP, inferior left GP, Marshall tract GP, anterior right GP, inferior right GP). High-density electroanatomic maps of the left atrium and PVs obtained during AF showed the FAP are located in four main left atrial areas (left atrial appendage ridge FAP area, superior-left FAP area, inferoposterior FAP area, anterior-right FAP area). All five GP are located within one of the four FAP areas. In 63 patients with paroxysmal AF, GP ablation alone (before PV antrum isolation) significantly decreased the occurrence of PV firing (47/63 patients before ablation vs 9/63 patients after ablation, P <.01). GP ablation also decreased the inducibility of sustained AF (43/63 patients vs 23

  11. Plasma microRNAs are associated with atrial fibrillation and change after catheter-ablation (the miRhythm Study)

    PubMed Central

    McManus, David D.; Tanriverdi, Kahraman; Lin, Honghuang; Esa, Nada; Kinno, Menhel; Mandapati, Divakar; Tam, Stanley; Okike, Okike N.; Ellinor, Patrick T.; Keaney, John F.; Donahue, J, Kevin; Benjamin, Emelia J.; Freedman, Jane E.

    2014-01-01

    Background MicroRNAs (miRNAs) are associated with cardiovascular disease (CVD), control gene expression, and are detectable in the circulation. Objective To test the hypothesis that circulating miRNAs would be associated with atrial fibrillation (AF). Methods Using a prospective study design powered to detect subtle differences in miRNAs, we quantified plasma expression of 86 miRNAs by high-throughput quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) in 112 participants with AF and 99 without AF. To examine parallels between cardiac and plasma miRNA profiles, we quantified atrial tissue and plasma miRNA expression using qRT-PCR in 31 participants undergoing surgery. We also explored the hypothesis that lower AF burden after ablation would be reflected in the circulating blood pool by examining change in plasma miRNAs after AF ablation (n=47). Results The mean age of the cohort was 59 years. 58% of participants were men. Plasma miRs-21 and 150 were 2-fold lower in participants with AF than in those without AF after adjustment (p ≤ 0.0006). Plasma levels of miRs-21 and 150 were also lower in participants with paroxysmal AF than in those with persistent AF (p <0.05). Expression of miR-21, but not miR-150, was lower in atrial tissue from patients with AF compared to no AF (p<0.05). Plasma levels of miRs-21 and 150 increased 3-fold after AF ablation (p ≤ 0.0006). Conclusions Cardiac miRs-21 and 150 are known to regulate genes implicated in atrial remodeling. Our findings show associations between plasma miRs-21 and 150 and AF, suggesting that circulating miRNAs provide insights into cardiac gene regulation. PMID:25257092

  12. Catheter Ablation

    MedlinePlus

    ... Are the Risks Clinical Trials Links Related Topics Arrhythmia Heart Surgery How the Heart Works Sudden Cardiac ... medical procedure used to treat some types of arrhythmia (ah-RITH-me-ah). An arrhythmia is a ...

  13. Local Ablation for Hepatocellular Carcinoma in Taiwan

    PubMed Central

    Lin, Shi-Ming

    2013-01-01

    Hepatocellular carcinoma (HCC) is the second commonest cancer in Taiwan. The national surveillance program can detect HCC in its early stages, and various curative modalities (including surgical resection, orthotopic liver transplantation, and local ablation) are employed for the treatment of small HCC. Local ablation therapies are currently advocated for early-stage HCC that is unresectable because of co-morbidities, the need to preserve liver function, or refusal of resection. Among the various local ablation therapies, the most commonly used modalities include percutaneous ethanol injection and radiofrequency ablation (RFA); percutaneous acetic acid injection and microwave ablation are used less often. RFA is more commonly employed than other local ablative modalities in Taiwan because the technique is highly effective, minimally invasive, and requires fewer sessions. RFA is therefore advocated in Taiwan as the first-line curative therapy for unresectable HCC or even for resectable HCC. However, current RFA procedures are less effective against tumors that are in high-risk or difficult-to-ablate locations, are poorly visualized on ultrasonography (US), or are large. Recent advancements in RFA in Taiwan can resolve these issues by the creation of artificial ascites or pleural effusion, application of real-time virtual US assistance, use of combination therapy before RFA, or use of switching RF controllers with multiple electrodes. This review article provides updates on the clinical outcomes and advances in local ablative modalities (mostly RFA) for HCC in Taiwan. PMID:24159599

  14. Atrioventricular Junction Ablation for Atrial Fibrillation.

    PubMed

    Patel, Dilesh; Daoud, Emile G

    2016-04-01

    Atrioventricular junction (AVJ) ablation is an effective therapy in patients with symptomatic atrial fibrillation who are intolerant to or unsuccessfully managed with rhythm control or medical rate control strategies. A drawback is that the procedure mandates a pacing system. Overall, the safety and efficacy of AVJ ablation is high with a majority of the patients reporting significant improvement in symptoms and quality-of-life measures. Risk of sudden cardiac death after device implantation is low, especially with an appropriate postprocedure pacing rate. Mortality benefit with AVJ ablation has been shown in patients with heart failure and cardiac resynchronization therapy devices. PMID:26968669

  15. Atrioventricular junction ablation for atrial fibrillation.

    PubMed

    Patel, Dilesh; Daoud, Emile G

    2014-11-01

    Atrioventricular junction (AVJ) ablation is an effective therapy in patients with symptomatic atrial fibrillation who are intolerant to or unsuccessfully managed with rhythm control or medical rate control strategies. A drawback is that the procedure mandates a pacing system. Overall, the safety and efficacy of AVJ ablation is high with a majority of the patients reporting significant improvement in symptoms and quality-of-life measures. Risk of sudden cardiac death after device implantation is low, especially with an appropriate postprocedure pacing rate. Mortality benefit with AVJ ablation has been shown in patients with heart failure and cardiac resynchronization therapy devices. PMID:25443238

  16. Uninterrupted rivaroxaban vs. uninterrupted vitamin K antagonists for catheter ablation in non-valvular atrial fibrillation

    PubMed Central

    Cappato, Riccardo; Marchlinski, Francis E.; Hohnloser, Stefan H.; Naccarelli, Gerald V.; Xiang, Jim; Wilber, David J.; Ma, Chang-Sheng; Hess, Susanne; Wells, Darryl S.; Juang, George; Vijgen, Johan; Hügl, Burkhard J.; Balasubramaniam, Richard; De Chillou, Christian; Davies, D. Wyn; Fields, L. Eugene; Natale, Andrea

    2015-01-01

    Aims VENTURE-AF is the first prospective randomized trial of uninterrupted rivaroxaban and vitamin K antagonists (VKAs) in patients with non-valvular atrial fibrillation (NVAF) undergoing catheter ablation (CA). Methods and results Trial size was administratively set at 250, the protocol-specified target. Events were independently and blindly adjudicated. We randomly assigned 248 NVAF patients to uninterrupted rivaroxaban (20 mg once-daily) or to an uninterrupted VKA prior to CA and for 4 weeks afterwards. The primary endpoint was major bleeding events after CA. Secondary endpoints included thromboembolic events (composite of stroke, systemic embolism, myocardial infarction, and vascular death) and other bleeding or procedure-attributable events. Patients were 59.5 ± 10 years of age, 71% male, 74% paroxysmal AF, and had a CHA2DS2-VASc score of 1.6. The average total heparin dose used to manage activated clotting time (ACT) was slightly higher (13 871 vs. 10 964 units; P < 0.001) and the mean ACT level attained slightly lower (302 vs. 332 s; P < 0.001) in rivaroxaban and VKA arms, respectively. The incidence of major bleeding was low (0.4%; 1 major bleeding event). Similarly, thromboembolic events were low (0.8%; 1 ischemic stroke and 1 vascular death). All events occurred in the VKA arm and all after CA. The number of any adjudicated events (26 vs. 25), any bleeding events (21 vs. 18), and any other procedure-attributable events (5 vs. 5) were similar. Conclusion In patients undergoing CA for AF, the use of uninterrupted oral rivaroxaban was feasible and event rates were similar to those for uninterrupted VKA therapy. Name of the Trial Registry Clinicaltrials.gov trial registration number is NCT01729871. PMID:25975659

  17. Impact of Atrial Fibrillation Ablation on Left Ventricular Filling Pressure and Left Atrial Remodeling

    PubMed Central

    dos Santos, Simone Nascimento; Henz, Benhur Davi; Zanatta, André Rodrigues; Barreto, José Roberto; Loureiro, Kelly Bianca; Novakoski, Clarissa; dos Santos, Marcus Vinícius Nascimento; Giuseppin, Fabio F.; Oliveira, Edna Maria; Leite, Luiz Roberto

    2014-01-01

    Background Left ventricular (LV) diastolic dysfunction is associated with new-onset atrial fibrillation (AF), and the estimation of elevated LV filling pressures by E/e' ratio is related to worse outcomes in patients with AF. However, it is unknown if restoring sinus rhythm reverses this process. Objective To evaluate the impact of AF ablation on estimated LV filling pressure. Methods A total of 141 patients underwent radiofrequency (RF) ablation to treat drug-refractory AF. Transthoracic echocardiography was performed 30 days before and 12 months after ablation. LV functional parameters, left atrial volume index (LAVind), and transmitral pulsed and mitral annulus tissue Doppler (e' and E/e') were assessed. Paroxysmal AF was present in 18 patients, persistent AF was present in 102 patients, and long-standing persistent AF in 21 patients. Follow-up included electrocardiographic examination and 24-h Holter monitoring at 3, 6, and 12 months after ablation. Results One hundred seventeen patients (82.9%) were free of AF during the follow-up (average, 18 ± 5 months). LAVind reduced in the successful group (30.2 mL/m2 ± 10.6 mL/m2 to 22.6 mL/m2 ± 1.1 mL/m2, p < 0.001) compared to the non-successful group (37.7 mL/m2 ± 14.3 mL/m2 to 37.5 mL/m2 ± 14.5 mL/m2, p = ns). Improvement of LV filling pressure assessed by a reduction in the E/e' ratio was observed only after successful ablation (11.5 ± 4.5 vs. 7.1 ± 3.7, p < 0.001) but not in patients with recurrent AF (12.7 ± 4.4 vs. 12 ± 3.3, p = ns). The success rate was lower in the long-standing persistent AF patient group (57% vs. 87%, p = 0.001). Conclusion Successful AF ablation is associated with LA reverse remodeling and an improvement in LV filling pressure. PMID:25590928

  18. Double-gap-in-roof reentrant tachycardia following surgical thoracoscopic atrial fibrillation ablation

    PubMed Central

    Osmancik, Pavel; Zdarska, Jana; Budera, Petr; Straka, Zbynek

    2015-01-01

    A case of macro-reentrant tachycardia associated with a box lesion after thoracoscopis left atrial surgical atrial fibrillation (AF) ablation yet to be described. The goal was to clarify the mechanisms and electrophysiological characteristics of this type of tachycardia. A patient was admitted for an EP study following surgical thoracoscopic AF ablation (box lexion formation by right-sided Cobra thoracoscopic ablation). Thoracoscopic ablation was done as the first step of the hybrid ablation approach to the persistent AF; the second step was the EP study. At the EP study, he presented with incessant regular tachycardia (cycle length of 226 ms). An EP study with conventional, 3D activation and entrainment mapping was done to assess the tachycardia mechanism. Two conduction gaps in the superior line (roofline) between the superior pulmonary veins were discovered. The tachycardia was successfully treated with a radiofrequency application near the gap close to the left superior pulmonary vein; however, following tachycardia termination, pulmonary vein isolation was absent. A second radiofrequency application, close to the roof of the right superior pulmonary, vein closed the gap in the box and led to the isolation of all 4 pulmonary veins. No atrial tachycardia recurred during the 6-month follow-up. Conduction gaps in box lesion created by thoracospcopic ablation can present as a novel type of man-made tachycardia after surgical ablation of atrial fibrillation. Activation and entrainment mapping is necessary for an accurate diagnosis. PMID:26937113

  19. Double-gap-in-roof reentrant tachycardia following surgical thoracoscopic atrial fibrillation ablation.

    PubMed

    Osmancik, Pavel; Zdarska, Jana; Budera, Petr; Straka, Zbynek

    2015-01-01

    A case of macro-reentrant tachycardia associated with a box lesion after thoracoscopis left atrial surgical atrial fibrillation (AF) ablation yet to be described. The goal was to clarify the mechanisms and electrophysiological characteristics of this type of tachycardia. A patient was admitted for an EP study following surgical thoracoscopic AF ablation (box lexion formation by right-sided Cobra thoracoscopic ablation). Thoracoscopic ablation was done as the first step of the hybrid ablation approach to the persistent AF; the second step was the EP study. At the EP study, he presented with incessant regular tachycardia (cycle length of 226 ms). An EP study with conventional, 3D activation and entrainment mapping was done to assess the tachycardia mechanism. Two conduction gaps in the superior line (roofline) between the superior pulmonary veins were discovered. The tachycardia was successfully treated with a radiofrequency application near the gap close to the left superior pulmonary vein; however, following tachycardia termination, pulmonary vein isolation was absent. A second radiofrequency application, close to the roof of the right superior pulmonary, vein closed the gap in the box and led to the isolation of all 4 pulmonary veins. No atrial tachycardia recurred during the 6-month follow-up. Conduction gaps in box lesion created by thoracospcopic ablation can present as a novel type of man-made tachycardia after surgical ablation of atrial fibrillation. Activation and entrainment mapping is necessary for an accurate diagnosis. PMID:26937113

  20. New-onset ventricular arrhythmias post radiofrequency catheter ablation for atrial fibrillation.

    PubMed

    Wu, Lingmin; Lu, Yanlai; Yao, Yan; Zheng, Lihui; Chen, Gang; Ding, Ligang; Hou, Bingbo; Qiao, Yu; Sun, Wei; Zhang, Shu

    2016-09-01

    As a new complication, new-onset ventricular arrhythmias (VAs) post atrial fibrillation (AF) ablation have not been well defined. This prospective study aimed to describe the details of new-onset VAs post AF ablation in a large study cohort.One thousand fifty-three consecutive patients who underwent the first radiofrequency catheter ablation for AF were enrolled. All patients had no evidence of pre-ablation VAs. New-onset VAs were defined as new-onset ventricular tachycardia (VT) or premature ventricular contractions (PVC) ≥1000/24 h within 1 month post ablation.There were 46 patients (4.4%) who had 62 different new-onset VAs, among whom 42 were PVC alone, and 4 were PVC coexisting with nonsustained VT. Multivariate analysis showed that increased serum leukocyte counts ≥50% post ablation were independently associated with new-onset VAs (OR: 1.9; 95% CI: 1.0-3.5; P = 0.043). The median number of PVC was 3161 (1001-27,407) times/24 h. Outflow tract VAs were recorded in 35 (76.1%) patients. No significant differences were found in origin of VAs (P = 0.187). VAs disappeared without any treatment in 6 patients (13.0%). No VAs-related adverse cardiac event occurred.The study revealed a noticeable prevalence but relatively benign prognosis of new-onset VAs post AF ablation. Increased serum leukocyte counts ≥50% post ablation appeared to be associated with new-onset VAs, implying that inflammatory response caused by ablation might be the mechanism. PMID:27603357

  1. CT-guided Bipolar and Multipolar Radiofrequency Ablation (RF Ablation) of Renal Cell Carcinoma: Specific Technical Aspects and Clinical Results

    SciTech Connect

    Sommer, C. M.; Lemm, G.; Hohenstein, E.; Bellemann, N.; Stampfl, U.; Goezen, A. S.; Rassweiler, J.; Kauczor, H. U.; Radeleff, B. A.; Pereira, P. L.

    2013-06-15

    Purpose. This study was designed to evaluate the clinical efficacy of CT-guided bipolar and multipolar radiofrequency ablation (RF ablation) of renal cell carcinoma (RCC) and to analyze specific technical aspects between both technologies. Methods. We included 22 consecutive patients (3 women; age 74.2 {+-} 8.6 years) after 28 CT-guided bipolar or multipolar RF ablations of 28 RCCs (diameter 2.5 {+-} 0.8 cm). Procedures were performed with a commercially available RF system (Celon AG Olympus, Berlin, Germany). Technical aspects of RF ablation procedures (ablation mode [bipolar or multipolar], number of applicators and ablation cycles, overall ablation time and deployed energy, and technical success rate) were analyzed. Clinical results (local recurrence-free survival and local tumor control rate, renal function [glomerular filtration rate (GFR)]) and complication rates were evaluated. Results. Bipolar RF ablation was performed in 12 procedures and multipolar RF ablation in 16 procedures (2 applicators in 14 procedures and 3 applicators in 2 procedures). One ablation cycle was performed in 15 procedures and two ablation cycles in 13 procedures. Overall ablation time and deployed energy were 35.0 {+-} 13.6 min and 43.7 {+-} 17.9 kJ. Technical success rate was 100 %. Major and minor complication rates were 4 and 14 %. At an imaging follow-up of 15.2 {+-} 8.8 months, local recurrence-free survival was 14.4 {+-} 8.8 months and local tumor control rate was 93 %. GFR did not deteriorate after RF ablation (50.8 {+-} 16.6 ml/min/1.73 m{sup 2} before RF ablation vs. 47.2 {+-} 11.9 ml/min/1.73 m{sup 2} after RF ablation; not significant). Conclusions. CT-guided bipolar and multipolar RF ablation of RCC has a high rate of clinical success and low complication rates. At short-term follow-up, clinical efficacy is high without deterioration of the renal function.

  2. Position of Totally Thoracoscopic Surgical Ablation in the Treatment of Atrial Fibrillation: An Alternative Method of Conduction Testing

    PubMed Central

    Sabashnikov, Anton; Weymann, Alexander; Haldar, Shouvik; Soliman, Rafik F.B.; Fatullayev, Javid; Jones, David; Hussain, Wajid; Choi, Yeong-Hoon; Zeriouh, Mohamed; Dohmen, Pascal M.; Popov, Aron-Frederik; Markides, Vias; Wong, Tom; Bahrami, Toufan

    2015-01-01

    Recent advances in surgical techniques and understanding of the pathophysiology of atrial fibrillation has led to the development of a less invasive thoracoscopic surgical treatment including video-assisted bilateral pulmonary vein isolation using bipolar radiofrequency ablation clamps. More recently, the same operation became possible via a totally thoracoscopic approach. In this paper we describe technical aspects of the thoracoscopic approach to surgical treatment of AF and discuss its features, benefits and limitations. Furthermore, we present a new alternative technique of conduction testing using endoscopic multi-electrode recording catheters. An alternative electrophysiological mapping strategy involves a multi-electrode recording catheter designed primarily for percutaneous endocardial electrophysiologic mapping procedure. According to our initial experience, the recordings obtained from the multi-electrode catheters positioned around the pulmonary veins are more accurate than the recordings obtained from the multifunctional ablation and pacing pen. The totally thoracoscopic surgical ablation approach is a feasible and efficient treatment strategy for atrial fibrillation. The conduction testing can be easily and rapidly performed using a multifunctional pen or multi-electrode recording catheter. PMID:25904211

  3. Cardiac Radiofrequency Ablation: A Clinical Update for Nurses.

    PubMed

    Shoulders, Bridget; Mauriello, Jillian; Shellman, Tamika; Follett, Corrinne

    2016-01-01

    The field of electrophysiology (EP) has rapidly evolved from a focus on diagnostic procedures to an emphasis on interventions. Many cardiac arrhythmias traditionally treated with antiarrhythmic agents, cardioversion, or cardiac surgery are now routinely cured with cardiac ablation. To optimally manage the care of cardiac ablation patients, it is essential that nurses have an understanding of the EP procedures and related nursing implications. There are extensive evidence-based resources available in the medical literature; however, there are limited publications geared toward nurses caring for cardiac ablation patients.This article provides an overview of EP diagnostic and cardiac radio-frequency ablation procedures for select atrial and ventricular tachyarrhythmias. Evidence-based nursing practices related to postprocedure care will be addressed. The objective of this article is to increase nurses' knowledge of common cardiac ablation procedures and the nursing management of the patient postprocedure. PMID:27487751

  4. Radiofrequency catheter ablation of accessory pathways in infants.

    PubMed Central

    Benito, F.; Sánchez, C.

    1997-01-01

    OBJECTIVE: To evaluate the indications, results and complications of radiofrequency catheter ablation in small infants with supraventricular tachycardia due to an accessory atrioventricular pathway. METHODS: Five infants less than 9 months old underwent radiofrequency catheter ablation of accessory pathways. Ablation was done for medically refractory tachyarrhythmia associated with aborted sudden death in two patients, left ventricular dysfunction in one, failure of antiarrhythmic drugs in one, and planned cardiac surgery in one. All five patients underwent a single successful procedure. Three left free wall pathways were ablated by transseptal approach, a right posteroseptal pathway was ablated from the inferior vena cava, and a left posteroseptal pathway was approached from the inferior vena cava into the coronary sinus. A deflectable 5F bipolar electrode catheter with a 3 mm tip was used. RESULTS: A sudden increment in impedance indicative of coagulum formation was observed in two procedures. One patient developed a transient ischaemic complication after ablation of a left lateral accessory pathway by transseptal approach. This patient had mild pericardial effusion after the procedure. Moderate pericardial effusion was also noted in another patient. After a mean follow up of 18.4 months all patients are symptom free without treatment. CONCLUSIONS: Radiofrequency catheter ablation can be performed successfully in infants. Temperature monitoring in 5F ablation catheters would be desirable to prevent the development of coagulum. Echocardiography must be performed after the ablation procedure to investigate pericardial effusion. Images PMID:9326990

  5. Electrophysiological Rotor Ablation in In-Silico Modeling of Atrial Fibrillation: Comparisons with Dominant Frequency, Shannon Entropy, and Phase Singularity

    PubMed Central

    Hwang, Minki; Song, Jun-Seop; Lee, Young-Seon; Li, Changyong; Shim, Eun Bo; Pak, Hui-Nam

    2016-01-01

    Background Although rotors have been considered among the drivers of atrial fibrillation (AF), the rotor definition is inconsistent. We evaluated the nature of rotors in 2D and 3D in- silico models of persistent AF (PeAF) by analyzing phase singularity (PS), dominant frequency (DF), Shannon entropy (ShEn), and complex fractionated atrial electrogram cycle length (CFAE-CL) and their ablation. Methods Mother rotor was spatiotemporally defined as stationary reentries with a meandering tip remaining within half the wavelength and lasting longer than 5 s. We generated 2D- and 3D-maps of the PS, DF, ShEn, and CFAE-CL during AF. The spatial correlations and ablation outcomes targeting each parameter were analyzed. Results 1. In the 2D PeAF model, we observed a mother rotor that matched relatively well with DF (>9 Hz, 71.0%, p<0.001), ShEn (upper 2.5%, 33.2%, p<0.001), and CFAE-CL (lower 2.5%, 23.7%, p<0.001). 2. The 3D-PeAF model also showed mother rotors that had spatial correlations with DF (>5.5 Hz, 39.7%, p<0.001), ShEn (upper 8.5%, 15.1%, p <0.001), and CFAE (lower 8.5%, 8.0%, p = 0.002). 3. In both the 2D and 3D models, virtual ablation targeting the upper 5% of the DF terminated AF within 20 s, but not the ablations based on long-lasting PS, high ShEn area, or lower CFAE-CL area. Conclusion Mother rotors were observed in both 2D and 3D human AF models. Rotor locations were well represented by DF, and their virtual ablation altered wave dynamics and terminated AF. PMID:26909492

  6. Atrial Fibrillation (AF or AFib)

    MedlinePlus

    ... Pressure High Blood Pressure Tools & Resources Stroke More Atrial Fibrillation (AF or AFib) Updated:Feb 10,2016 What ... to the Terms and Conditions and Privacy Policy Atrial Fibrillation • Introduction • What is Atrial Fibrillation? • Why AFib Matters • ...

  7. Assessment of liver ablation using cone beam computed tomography

    PubMed Central

    Abdel-Rehim, Mohamed; Ronot, Maxime; Sibert, Annie; Vilgrain, Valérie

    2015-01-01

    AIM: To investigate the feasibility and accuracy of cone beam computed tomography (CBCT) in assessing the ablation zone after liver tumor ablation. METHODS: Twenty-three patients (17 men and 6 women, range: 45-85 years old, mean age 65 years) with malignant liver tumors underwent ultrasound-guided percutaneous tumor ablation [radiofrequency (n = 14), microwave (n = 9)] followed by intravenous contrast-enhanced CBCT. Baseline multidetector computed tomography (MDCT) and peri-procedural CBCT images were compared. CBCT image quality was assessed as poor, good, or excellent. Image fusion was performed to assess tumor coverage, and quality of fusion was rated as bad, good, or excellent. Ablation zone volumes on peri-procedural CBCT and post-procedural MDCT were compared using the non-parametric paired Wilcoxon t-test. RESULTS: Rate of primary ablation effectiveness was 100%. There were no complications related to ablation. Local tumor recurrence and new liver tumors were found 3 mo after initial treatment in one patient (4%). The ablation zone was identified in 21/23 (91.3%) patients on CBCT. The fusion of baseline MDCT and peri-procedural CBCT images was feasible in all patients and showed satisfactory tumor coverage (at least 5-mm margin). CBCT image quality was poor, good, and excellent in 2 (9%), 8 (35%), and 13 (56%), patients respectively. Registration quality between peri-procedural CBCT and post-procedural MDCT images was good to excellent in 17/23 (74%) patients. The median ablation volume on peri-procedural CBCT and post-procedural MDCT was 30 cm3 (range: 4-95 cm3) and 30 cm3 (range: 4-124 cm3), respectively (P-value > 0.2). There was a good correlation (r = 0.79) between the volumes of the two techniques. CONCLUSION: Contrast-enhanced CBCT after tumor ablation of the liver allows early assessment of the ablation zone. PMID:25593467

  8. Influence of water environment on holmium laser ablation performance for hard tissues.

    PubMed

    Lü, Tao; Xiao, Qing; Li, Zhengjia

    2012-05-01

    This study clarifies the ablation differences in air and in water for hard biological tissues, which are irradiated by fiber-guided long-pulsed holmium lasers. High-speed photography is used to record the dynamic characteristics of ablation plumes and vaporization bubbles induced by pulsed holmium lasers. The ablation morphologies and depth of hard tissues are quantitatively measured by optical coherence microscopy. Explosive vaporization effects in water play a positive role in the contact ablation process and are directly responsible for significant ablation enhancement. Furthermore, water layer depth can also contribute to ablation performance. Under the same laser parameters for fiber-tissue contact ablation in air and water, ablation performances are comparable for a single-laser pulse, but for more laser pulses the ablation performances in water are better than those in air. Comprehensive knowledge of ablation differences under various environments is important, especially in medical procedures that are performed in a liquid environment. PMID:22614434

  9. Laser-ablation processes

    SciTech Connect

    Dingus, R.S.

    1992-01-01

    The various mechanisms by which ablation of materials can be induced with lasers are discussed in this paper. The various ablation processes and potential applications are reviewed from the threshold for ablation up to fluxes of about 10{sup 13} W/cm{sup 2}, with emphasis on three particular processes; namely, front-surface spallation, two-dimensional blowoff, and contained vaporization.

  10. Automatic classification of scar tissue in late gadolinium enhancement cardiac MRI for the assessment of left-atrial wall injury after radiofrequency ablation

    NASA Astrophysics Data System (ADS)

    Perry, Daniel; Morris, Alan; Burgon, Nathan; McGann, Christopher; MacLeod, Robert; Cates, Joshua

    2012-03-01

    Radiofrequency ablation is a promising procedure for treating atrial fibrillation (AF) that relies on accurate lesion delivery in the left atrial (LA) wall for success. Late Gadolinium Enhancement MRI (LGE MRI) at three months post-ablation has proven effective for noninvasive assessment of the location and extent of scar formation, which are important factors for predicting patient outcome and planning of redo ablation procedures. We have developed an algorithm for automatic classification in LGE MRI of scar tissue in the LA wall and have evaluated accuracy and consistency compared to manual scar classifications by expert observers. Our approach clusters voxels based on normalized intensity and was chosen through a systematic comparison of the performance of multivariate clustering on many combinations of image texture. Algorithm performance was determined by overlap with ground truth, using multiple overlap measures, and the accuracy of the estimation of the total amount of scar in the LA. Ground truth was determined using the STAPLE algorithm, which produces a probabilistic estimate of the true scar classification from multiple expert manual segmentations. Evaluation of the ground truth data set was based on both inter- and intra-observer agreement, with variation among expert classifiers indicating the difficulty of scar classification for a given a dataset. Our proposed automatic scar classification algorithm performs well for both scar localization and estimation of scar volume: for ground truth datasets considered easy, variability from the ground truth was low; for those considered difficult, variability from ground truth was on par with the variability across experts.

  11. Neural Ablation and Regeneration in Pain Practice.

    PubMed

    Choi, Eun Ji; Choi, Yun Mi; Jang, Eun Jung; Kim, Ju Yeon; Kim, Tae Kyun; Kim, Kyung Hoon

    2016-01-01

    A nerve block is an effective tool for diagnostic and therapeutic methods. If a diagnostic nerve block is successful for pain relief and the subsequent therapeutic nerve block is effective for only a limited duration, the next step that should be considered is a nerve ablation or modulation. The nerve ablation causes iatrogenic neural degeneration aiming only for sensory or sympathetic denervation without motor deficits. Nerve ablation produces the interruption of axonal continuity, degeneration of nerve fibers distal to the lesion (Wallerian degeneration), and the eventual death of axotomized neurons. The nerve ablation methods currently available for resection/removal of innervation are performed by either chemical or thermal ablation. Meanwhile, the nerve modulation method for interruption of innervation is performed using an electromagnetic field of pulsed radiofrequency. According to Sunderland's classification, it is first and foremost suggested that current neural ablations produce third degree peripheral nerve injury (PNI) to the myelin, axon, and endoneurium without any disruption of the fascicular arrangement, perineurium, and epineurium. The merit of Sunderland's third degree PNI is to produce a reversible injury. However, its shortcoming is the recurrence of pain and the necessity of repeated ablative procedures. The molecular mechanisms related to axonal regeneration after injury include cross-talk between axons and glial cells, neurotrophic factors, extracellular matrix molecules, and their receptors. It is essential to establish a safe, long-standing denervation method without any complications in future practices based on the mechanisms of nerve degeneration as well as following regeneration. PMID:26839664

  12. Neural Ablation and Regeneration in Pain Practice

    PubMed Central

    Choi, Eun Ji; Choi, Yun Mi; Jang, Eun Jung; Kim, Ju Yeon; Kim, Tae Kyun

    2016-01-01

    A nerve block is an effective tool for diagnostic and therapeutic methods. If a diagnostic nerve block is successful for pain relief and the subsequent therapeutic nerve block is effective for only a limited duration, the next step that should be considered is a nerve ablation or modulation. The nerve ablation causes iatrogenic neural degeneration aiming only for sensory or sympathetic denervation without motor deficits. Nerve ablation produces the interruption of axonal continuity, degeneration of nerve fibers distal to the lesion (Wallerian degeneration), and the eventual death of axotomized neurons. The nerve ablation methods currently available for resection/removal of innervation are performed by either chemical or thermal ablation. Meanwhile, the nerve modulation method for interruption of innervation is performed using an electromagnetic field of pulsed radiofrequency. According to Sunderland's classification, it is first and foremost suggested that current neural ablations produce third degree peripheral nerve injury (PNI) to the myelin, axon, and endoneurium without any disruption of the fascicular arrangement, perineurium, and epineurium. The merit of Sunderland's third degree PNI is to produce a reversible injury. However, its shortcoming is the recurrence of pain and the necessity of repeated ablative procedures. The molecular mechanisms related to axonal regeneration after injury include cross-talk between axons and glial cells, neurotrophic factors, extracellular matrix molecules, and their receptors. It is essential to establish a safe, long-standing denervation method without any complications in future practices based on the mechanisms of nerve degeneration as well as following regeneration. PMID:26839664

  13. Image-Guided Spinal Ablation: A Review.

    PubMed

    Tsoumakidou, Georgia; Koch, Guillaume; Caudrelier, Jean; Garnon, Julien; Cazzato, Roberto Luigi; Edalat, Faramarz; Gangi, Afshin

    2016-09-01

    The image-guided thermal ablation procedures can be used to treat a variety of benign and malignant spinal tumours. Small size osteoid osteoma can be treated with laser or radiofrequency. Larger tumours (osteoblastoma, aneurysmal bone cyst and metastasis) can be addressed with radiofrequency or cryoablation. Results on the literature of spinal microwave ablation are scarce, and thus it should be used with caution. A distinct advantage of cryoablation is the ability to monitor the ice-ball by intermittent CT or MRI. The different thermal insulation, temperature and electrophysiological monitoring techniques should be applied. Cautious pre-procedural planning and intermittent intra-procedural monitoring of the ablation zone can help reduce neural complications. Tumour histology, patient clinical-functional status and life-expectancy should define the most efficient and least disabling treatment option. PMID:27329231

  14. Surgical Ablation of Atrial Fibrillation

    PubMed Central

    Ramlawi, Basel; Abu Saleh, Walid K.

    2015-01-01

    The Cox-maze procedure for the restoration of normal sinus rhythm, initially developed by Dr. James Cox, underwent several iterations over the years. The main concept consists of creating a series of transmural lesions in the right and left atria that disrupt re-entrant circuits responsible for propagating the abnormal atrial fibrillation rhythm. The left atrial appendage is excluded as a component of the Maze procedure. For the first three iterations of the Cox- maze procedure, these lesions were performed using a surgical cut-and-sew approach that ensured transmurality. The Cox-Maze IV is the most currently accepted iteration. It achieves the same lesion set of the Cox- maze III but uses alternative energy sources to create the transmural lesions, potentially in a minimally invasive approach on the beating heart. High-frequency ultrasound, microwave, and laser energy have all been used with varying success in the past. Today, bipolar radiofrequency heat or cryotherapy cooling are the most accepted sources for creating linear lesions with consistent safety and transmurality. The robust and reliable nature of these energy delivery methods has yielded a success rate reaching 90% freedom from atrial fibrillation at 12 months. Such approaches offer a significant long-term advantage over catheter-based ablation, especially in patients having longstanding, persistent atrial fibrillation with characteristics such as dilated left atrial dimensions, poor ejection fraction, and failed catheter ablation. Based on these improved results, there currently is significant interest in developing a hybrid ablation strategy that incorporates the superior transmural robust lesions of surgical ablation, the reliable stroke prevention potential of epicardial left atrial appendage exclusion, and sophisticated mapping and confirmatory catheter-based ablation technology. Such a minimally invasive hybrid strategy for ablation may lead to the development of multidisciplinary “Afib teams

  15. Laser ablation of blepharopigmentation

    SciTech Connect

    Tanenbaum, M.; Karas, S.; McCord, C.D. Jr. )

    1988-01-01

    This article discusses laser ablation of blepharopigmentation in four stages: first, experimentally, where pigment vaporization is readily achieved with the argon blue-green laser; second, in the rabbit animal model, where eyelid blepharopigmentation markings are ablated with the laser; third, in human subjects, where the argon blue-green laser is effective in the ablation of implanted eyelid pigment; and fourth, in a case report, where, in a patient with improper pigment placement in the eyelid, the laser is used to safely and effectively ablate the undesired pigment markings. This article describes in detail the new technique of laser ablation of blepharopigmentation. Potential complications associated with the technique are discussed.

  16. Laser ablation in analytical chemistry - A review

    SciTech Connect

    Russo, Richard E.; Mao, Xianglei; Liu, Haichen; Gonzalez, Jhanis; Mao, Samuel S.

    2001-10-10

    Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduced risk of contamination or sample loss, analysis of very small samples not separable for solution analysis, and determination of spatial distributions of elemental composition. This review describes recent research to understand and utilize laser ablation for direct solid sampling, with emphasis on sample introduction to an inductively coupled plasma (ICP). Current research related to contemporary experimental systems, calibration and optimization, and fractionation is discussed, with a summary of applications in several areas.

  17. Atriocaval Rupture After Right Atrial Isthmus Ablation for Atrial Flutter.

    PubMed

    Vloka, Caroline; Nelson, Daniel W; Wetherbee, Jule

    2016-06-01

    A patient with symptomatic typical atrial flutter (AFL) underwent right atrial isthmus ablation with an 8-mm catheter. Eight months later, his typical AFL recurred. Ten months later, he underwent a repeat right atrial isthmus ablation with an irrigated tip catheter and an 8-mm tip catheter. Six weeks after his second procedure, while performing intense sprint intervals on a treadmill, he developed an abrupt onset of chest pain, hypotension, and cardiac tamponade. He underwent emergency surgery to repair an atriocaval rupture and has done well since. Our report suggests that an association of multiple radiofrequency ablations with increased risk for delayed atriocaval rupture occurring 1 to 3 months after ablation. In conclusion, although patients generally were advised to limit exercise for 1 to 2 weeks after AFL ablation procedures in the past, it may be prudent to avoid intense exercise for at least 3 months after procedure. PMID:27112285

  18. Catheter Ablation of Atrial Fibrillation Raises the Plasma Level of NGF-β Which Is Associated with Sympathetic Nerve Activity

    PubMed Central

    Park, Jae Hyung; Wi, Jin; Lee, Da Lyung; Joung, Boyoung; Lee, Moon Hyoung

    2015-01-01

    Purpose The expression of nerve growth factor-β (NGF-β) is related to cardiac nerve sprouting and sympathetic hyper innervation. We investigated the changes of plasma levels of NGF-β and the relationship to follow-up heart rate variability (HRV) after radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). Materials and Methods This study included 147 patients with AF (117 men, 55.8±11.5 years, 106 paroxysmal AF) who underwent RFCA. The plasma levels of NGF-β were quantified using double sandwich enzyme linked immunosorbent assay method before (NGF-βpre) and 1 hour after RFCA (NGF-βpost-1hr). HRV at pre-procedure (HRVpre), 3 months (HRVpost-3mo), and 1 year post-procedure (HRVpost-1yr) were analyzed and compared with plasma levels of NGF-β. Results 1) The plasma levels of NGF-β significantly increased after RFCA (20.05±11.09 pg/mL vs. 29.60±19.43 pg/mL, p<0.001). The patients who did not show increased NGF-βpost-1hr were older (p=0.023) and had greater left atrial volume index (p=0.028) than those with increased NGF-βpost-1hr. 2) In patients with NGF-βpre >18 pg/mL, low frequency components (LF)/high-frequency components (HF) (p=0.003) and the number of atrial premature contractions (APCs, p=0.045) in HRVpost-3mo were significantly higher than those with ≤18 pg/mL. 3) The LF/HF at HRVpost-3mo was linearly associated with the NGF-βpre (B=4.240, 95% CI 1.114-7.336, p=0.008) and the NGF-βpost-1hr (B=7.617, 95% CI 2.106-13.127, p=0.007). 4) Both NGF-βpre (OR=1.159, 95% CI 1.045-1.286, p=0.005) and NGF-βpost-1hr (OR=1.098, 95% CI 1.030-1.170, p=0.004) were independent predictors for the increase of LF/HF at HRVpost-3mo. Conclusion AF catheter ablation increases plasma level of NGF-β, and high plasma levels of NGF-βpre was associated with higher sympathetic nerve activity and higher frequency of APCs in HRVpost-3mo. PMID:26446633

  19. Cost-Effectiveness of Catheter Ablation for Rhythm Control of Atrial Fibrillation

    PubMed Central

    Blackhouse, Gord; Assasi, Nazila; Xie, Feng; Gaebel, Kathryn; Campbell, Kaitryn; Healey, Jeff S.; O'Reilly, Daria

    2013-01-01

    Objective. The objective of this study is to evaluate the cost-effectiveness of catheter ablation for rhythm control compared to antiarrhythmic drug (AAD) therapy in patients with atrial fibrillation (AF) who have previously failed on an AAD. Methods. An economic model was developed to compare (1) catheter ablation and (2) AAD (amiodarone 200 mg/day). At the end of the initial 12 month phase of the model, patients are classified as being in normal sinus rhythm or with AF, based on data from a meta-analysis. In the 5-year Markov phase of the model, patients are at risk of ischemic stroke each 3-month model cycle. Results. The model estimated that, compared to the AAD strategy, ablation had $8,539 higher costs, 0.033 fewer strokes, and 0.144 more QALYS over the 5-year time horizon. The incremental cost per QALY of ablation compared to AAD was estimated to be $59,194. The probability of ablation being cost-effective for willingness to pay thresholds of $50,000 and $100,000 was estimated to be 0.89 and 0.90, respectively. Conclusion. Based on current evidence, pulmonary vein ablation for treatment of AF is cost-effective if decision makers willingness to pay for a QALY is $59,194 or higher. PMID:24089640

  20. Polymorphism rs2200733 at chromosome 4q25 is associated with atrial fibrillation recurrence after radiofrequency catheter ablation in the Chinese Han population

    PubMed Central

    Chen, Feifei; Yang, Yanzong; Zhang, Rongfeng; Zhang, Shulong; Dong, Yingxue; Yin, Xiaomeng; Chang, Dong; Yang, Zhiqiang; Wang, Kejing; Gao, Lianjun; Xia, Yunlong

    2016-01-01

    To test polymorphisms rs2200733 (chromosome 4q25) and rs2106261 (ZFHX3) were associated with AF recurrence after catheter ablation in a Chinese Han cohort. A total of 235 AF patients who underwent catheter ablation were recruited consecutively. Two polymorphisms were amplified by polymerase chain reaction and genotyped using high resolution melting analysis. Primary endpoints for AF recurrence were defined as the time to the first recurrence of atrial tachycardia/flutter/fibrillation (AT/AF). AT/AF recurrence was observed in 76 patients (35%). Allelic analysis demonstrated that rs2200733 was strongly associated with AF recurrence after ablation (P = 0.011) and the minor allele T increased the risk for recurrence (OR = 1.715). Diameters of the right atrium as well as the left and right superior pulmonary veins (PVs) were associated with rs2200733 in different genetic models (P = 0.040, 0.047 and 0.028, respectively). No significant association was detected between rs2106261 and AT/AF recurrence after ablation or atrial/PV diameters in any models. On multivariate Cox regression analysis, only rs2200733 was an independent factor of AF recurrence after ablation (HR = 0.532, P = 0.022). In Chinese Han population, rs2200733 but not rs2106261 is associated with AT/AF recurrence after ablation. The patients with genotype TT have larger size of right atrium and superior PVs than those of CC genotype. The findings suggest that rs2200733 may play a key role in regulating proper development and differentiation of atria/PVs. PMID:27158361

  1. A Minimally Invasive Cox-Maze Procedure: Operative Technique and Results

    PubMed Central

    Lee, Anson M.; Clark, Kal; Bailey, Marci S.; Aziz, Abdulhameed; Schuessler, Richard B.; Damiano, Ralph J.

    2010-01-01

    Summary Objective The Cox-Maze procedure for the surgical treatment of atrial fibrillation traditionally has required a median sternotomy and cardiopulmonary bypass. This study describes a method using ablation technologies to create the full Cox-Maze lesion set through a 5–6 cm right mini-thoracotomy. Methods Twenty-two consecutive patients underwent a Cox-Maze procedure via a right mini-thoracotomy and cardiopulmonary bypass. All patients were followed prospectively with ECG and 24 hour Holter monitoring at 3, 6, and 12 months. The Cox-Maze procedure lesion set was created using bipolar radiofrequency energy and cryothermy. Results There was no operative mortality or major complications. Two patients required a permanent pacemaker. Five patients (23%) had early atrial tachyarrhythmias. At last follow-up (mean 18 ± 12 months), all of the patients (n=22) were free from atrial dysrhythmias. At 3 months (n=19), 84% of patients were off antiarrhythmic drugs. By 6 months (n=18), 94% of patients were free from AF and off antiarrhythmic medications. At 12 months (n=16), 81% of patients were free from AF and off antiarrhythmic drugs and three patients remained on warfarin for a mechanical mitral valve. Conclusions A full Cox-Maze procedure can be performed through a right mini-thoracotomy with outstanding short term results. This less invasive procedure can be offered to patients without compromising efficacy. PMID:21057605

  2. Development of procedures and instrumentation for use of the Nd:YAG laser in the ablation of metastases from colorectal cancer

    NASA Astrophysics Data System (ADS)

    Bartels, Kenneth E.; Mellow, Mark H.; Kostolich, Marilyn; Henry, George A.; Barnes, Bradley R.; Durville, Frederic M.; Schafer, Steven A.; Krasinski, Jerzy S.; Powell, Richard C.

    1992-06-01

    While many colon cancers are curable, curability relates closely to stage. Once disease is spread beyond the confines of the colon and adjacent lymph nodes, cure is clearly the exception rather than the rule. Recently, surgical resection of solitary liver metastases has been effective in treatment of colon cancer, producing long term survival in approximately 20% of treatable patients. Surgery, however, is technically complex and there is a high perioperative morbidity and substantial perioperative mortality. For patients with multiple hepatic metastases in whom surgical extirpation is not possible, the outlook is dismal. Other modalities including chemotherapy have also resulted in limited success. Recently, a number of investigators have evaluated the effect of low power interstitial Nd:YAG laser irradiation for inducing hyperthermia and coagulative necrosis is hepatic tissue. In treating multiple or large hepatic metastases, the use of a lower power (1 - 5 watts), long duration (50 - 2400 seconds), single fiber laser delivery system has limitations. A computer controlled continuous wave Nd:YAG (1064 nm) laser system using a single fiber 'coupled' to a multiple array of fibers (4 to 6) has been developed for the delivery of low power laser irradiation to hepatic tissue. The advantage of laser energy being delivered simultaneously through multiple fibers is that it expands the area of tissue that can be treated over a given time. Through the use of interventional techniques including percutaneous ultrasound and/or CAT scan directed treatment, laser induced interstitial hyperthermia for large or multiple metastatic lesions could be initiated without the morbidity associated with open surgical procedures.

  3. Nonequilibrium Ablation of Phenolic Impregnated Carbon Ablator

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Yih K.; Gokcen, Tahir

    2012-01-01

    In previous work, an equilibrium ablation and thermal response model for Phenolic Impregnated Carbon Ablator was developed. In general, over a wide range of test conditions, model predictions compared well with arcjet data for surface recession, surface temperature, in-depth temperature at multiple thermocouples, and char depth. In this work, additional arcjet tests were conducted at stagnation conditions down to 40 W/sq cm and 1.6 kPa. The new data suggest that nonequilibrium effects become important for ablation predictions at heat flux or pressure below about 80 W/sq cm or 10 kPa, respectively. Modifications to the ablation model to account for nonequilibrium effects are investigated. Predictions of the equilibrium and nonequilibrium models are compared with the arcjet data.

  4. Outcomes after ablation for typical atrial flutter (from the Loire Valley Atrial Fibrillation Project).

    PubMed

    Clementy, Nicolas; Desprets, Laurent; Pierre, Bertrand; Lallemand, Bénédicte; Simeon, Edouard; Brunet-Bernard, Anne; Babuty, Dominique; Fauchier, Laurent

    2014-11-01

    Similar predisposing factors are found in most types of atrial arrhythmias. The incidence of atrial fibrillation (AF) among patients with atrial flutter is high, suggesting similar outcomes in patients with those arrhythmias. We sought to investigate the long-term outcomes and prognostic factors of patients with AF and/or atrial flutter with contemporary management using radiofrequency ablation. In an academic institution, we retrospectively examined the clinical course of 8,962 consecutive patients admitted to our department with a diagnosis of AF and/or atrial flutter. After a median follow-up of 934 ± 1,134 days, 1,155 deaths and 715 stroke and/thromboembolic (TE) events were recorded. Patients with atrial flutter undergoing cavotricuspid isthmus ablation (n = 875, 37% with a history of AF) had a better survival rate than other patients (hazard ratio [HR] 0.35, 95% confidence interval [CI] 0.25 to 0.49, p <0.0001). Using Cox proportional hazards model and propensity score model, after adjustment for main other confounders, ablation for atrial flutter was significantly associated with a lower risk of all-cause mortality (HR 0.55, 95% CI 0.36 to 0.84, p = 0.006) and stroke and/or TE events (HR 0.53, 95% CI 0.30 to 0.92, p = 0.02). After ablation, there was no significant difference in the risk of TE between patients with a history of AF and those with atrial flutter alone (HR 0.83, 95% CI 0.41 to 1.67, p = 0.59). In conclusion, in patients with atrial tachyarrhythmias, those with atrial flutter with contemporary management who undergo cavotricuspid isthmus radiofrequency ablation independently have a lower risk of stroke and/or TE events and death of any cause, whether a history of AF is present or not. PMID:25200340

  5. Radiofrequency Ablation of Thyroid Nodules: Basic Principles and Clinical Application

    PubMed Central

    Shin, Ji Hoon; Baek, Jung Hwan; Ha, Eun Ju; Lee, Jeong Hyun

    2012-01-01

    Radiofrequency (RF) ablation has been gaining popularity as a minimally invasive treatment for benign thyroid nodules regardless of the extent of the solid component. RF ablation of benign nodules demonstrated volume reductions of 33–58% after one month and 51–85% after six months, while solving nodule-related clinical problems. RF ablation has recently shown positive short-term results for locoregional control as well as symptom improvement in patients with recurrent thyroid cancers. This paper reviews the basic physics, indications, patient preparation, devices, procedures, clinical results, and complications of RF ablation. PMID:23133449

  6. Image-Guided Tumor Ablation: Emerging Technologies and Future Directions

    PubMed Central

    McWilliams, Justin P.; Lee, Edward W.; Yamamoto, Shota; Loh, Christopher T.; Kee, Stephen T.

    2010-01-01

    As the trend continues toward the decreased invasiveness of medical procedures, image-guided percutaneous ablation has begun to supplant surgery for the local control of small tumors in the liver, kidney, and lung. New ablation technologies, and refinements of existing technologies, will enable treatment of larger and more complex tumors in these and other organs. At the same time, improvements in intraprocedural imaging promise to improve treatment accuracy and reduce complications. In this review, the latest advancements in clinical and experimental ablation technologies will be summarized, and new applications of image-guided tumor ablation will be discussed. PMID:22550370

  7. Renal Ablation Update

    PubMed Central

    Khiatani, Vishal; Dixon, Robert G.

    2014-01-01

    Thermal ablative technologies have evolved considerably in the recent past and are now an important component of current clinical guidelines for the treatment of small renal masses. Both radiofrequency ablation and cryoablation have intermediate-term oncologic control that rivals surgical options, with favorable complication profiles. Studies comparing cryoablation and radiofrequency ablation show no significant difference in oncologic control or complication profile between the two modalities. Early data from small series with microwave ablation have shown similar promising results. Newer technologies including irreversible electroporation and high-intensity–focused ultrasound have theoretical advantages, but will require further research before becoming a routine part of the ablation armamentarium. The purpose of this review article is to discuss the current ablative technologies available, briefly review their mechanisms of action, discuss technical aspects of each, and provide current data supporting their use. PMID:25049445

  8. Renal ablation update.

    PubMed

    Khiatani, Vishal; Dixon, Robert G

    2014-06-01

    Thermal ablative technologies have evolved considerably in the recent past and are now an important component of current clinical guidelines for the treatment of small renal masses. Both radiofrequency ablation and cryoablation have intermediate-term oncologic control that rivals surgical options, with favorable complication profiles. Studies comparing cryoablation and radiofrequency ablation show no significant difference in oncologic control or complication profile between the two modalities. Early data from small series with microwave ablation have shown similar promising results. Newer technologies including irreversible electroporation and high-intensity-focused ultrasound have theoretical advantages, but will require further research before becoming a routine part of the ablation armamentarium. The purpose of this review article is to discuss the current ablative technologies available, briefly review their mechanisms of action, discuss technical aspects of each, and provide current data supporting their use. PMID:25049445

  9. Radiofrequency Ablation of Cancer

    PubMed Central

    Friedman, Marc; Mikityansky, Igor; Kam, Anthony; Libutti, Steven K.; Walther, McClellan M.; Neeman, Ziv; Locklin, Julia K.; Wood, Bradford J.

    2008-01-01

    Radiofrequency ablation (RFA) has been used for over 18 years for treatment of nerve-related chronic pain and cardiac arrhythmias. In the last 10 years, technical developments have increased ablation volumes in a controllable, versatile, and relatively inexpensive manner. The host of clinical applications for RFA have similarly expanded. Current RFA equipment, techniques, applications, results, complications, and research avenues for local tumor ablation are summarized. PMID:15383844

  10. Radiofrequency Ablation of Cancer

    SciTech Connect

    Friedman, Marc; Mikityansky, Igor; Kam, Anthony; Libutti, Steven K.; Walther, McClellan M.; Neeman, Ziv; Locklin, Julia K.; Wood, Bradford J.

    2004-09-15

    Radiofrequency ablation (RFA) has been used for over 18 years for treatment of nerve-related chronic pain and cardiac arrhythmias. In the last 10 years, technical developments have increased ablation volumes in a controllable, versatile, and relatively inexpensive manner. The host of clinical applications for RFA have similarly expanded. Current RFA equipment, techniques, applications, results, complications, and research avenues for local tumor ablation are summarized.

  11. First steps towards initial registration for electrophysiology procedures

    NASA Astrophysics Data System (ADS)

    Brost, Alexander; Bourier, Felix; Yatziv, Liron; Koch, Martin; Hornegger, Joachim; Strobel, Norbert; Kurzidim, Klaus

    2011-03-01

    Atrial fibrillation is the most common heart arrhythmia and a leading cause of stroke. The treatment option of choice is radio-frequency catheter ablation, which is performed in electrophysiology labs using C-Arm X-ray systems for navigation and guidance. The goal is to electrically isolate the pulmonary vein-left atrial junction thereby rendering myocardial fibers responsible for induction and maintenance of AF inactive. The use of overlay images for fluoroscopic guidance may improve the quality of the ablation procedure, and can reduce procedure time. Overlay images, acquired using CT, MRI, or C-arm CT, can add soft-tissue information, otherwise not visible under X-ray. MRI can be used to image a wide variety of anatomical details without ionizing radiation. In this paper, we present a method to register a 3-D MRI volume to 2-D biplane X-ray images using the coronary sinus. Current approaches require registration of the overlay images to the fluoroscopic images to be performed after the trans-septal puncture, when contast agent can be administered. We present a new approach for registration to align overlay images before the trans-septal puncture. To this end, we manually extract the coronary sinus from pre-operative MRI and register it to a multi-electorde catheter placed in the coronary sinus.

  12. Lung Ablation: Whats New?

    PubMed

    Xiong, Lillian; Dupuy, Damian E

    2016-07-01

    Lung cancer had an estimated incidence of 221,200 in 2015, making up 13% of all cancer diagnoses. Tumor ablation is an important treatment option for nonsurgical lung cancer and pulmonary metastatic patients. Radiofrequency ablation has been used for over a decade with newer modalities, microwave ablation, cryoablation, and irreversible electroporation presenting as additional and possibly improved treatment options for patients. This minimally invasive therapy is best for small primary lesions or favorably located metastatic tumors. These technologies can offer palliation and sometimes cure of thoracic malignancies. This article discusses the current available technologies and techniques available for tumor ablation. PMID:27050331

  13. Ablative Thermal Protection System Fundamentals

    NASA Technical Reports Server (NTRS)

    Beck, Robin A. S.

    2013-01-01

    This is the presentation for a short course on the fundamentals of ablative thermal protection systems. It covers the definition of ablation, description of ablative materials, how they work, how to analyze them and how to model them.

  14. Clinical Experience with Cone Beam CT Navigation for Tumor Ablation

    PubMed Central

    Abi-Jaoudeh, Nadine; Venkatesan, Aradhana M.; Van der Sterren, William; Radaelli, Alessandro; Carelsen, Bart; Wood, Bradford J.

    2015-01-01

    Purpose To describe clinical use and potential benefits of Cone Beam Computed Tomography (CBCT) navigation to perform image guided percutaneous tumor ablations. Materials and Methods All ablations performed between February 2011 and February 2013 using CBCT navigation, were included. Sixteen patients underwent 20 ablations for 29 lesions. CBCT ablation planning capabilities include multimodality image fusion and tumor segmentation for visualization, depiction of the predicted ablation zones for intra-procedural planning and segmentation of the ablated area for immediate post-treatment verification. Number and purpose of CBCT were examined. The initial ablation plan defined as number of probes and duration of energy delivery was recorded for 20/29 lesions. Technical success and local recurrences were recorded. Primary and secondary effectiveness rates were calculated. Results Image fusion was utilized for 16 lesions and intra-procedural ultrasound for 4. Of the 20/29 lesions, where the ablation plans were recorded, there was no deviation from the plan in 14. In the remaining 6/20, iterative planning was needed for complete tumor coverage. An average of 8.7 ± 3.2 CBCT were performed per procedure, including 1.3 ± 0.5 for tumor segmentation and planning, 1.7 ± 0.7 for probe position confirmation, 3.9 ± 2 to ensure complete coverage. Mean follow-up was 18.6 ± 6.5 months. 28/29 ablations were technically successful (96.5%). Of ablations performed with curative intent, technical effectiveness at one-month was 25/26 (96.1%) and 22/26 (84.6%) at last follow-up. Local tumor progression was observed in 11.5% (3/26). Conclusion CBCT navigation may add information to assist and improve ablation guidance and monitoring. PMID:25645409

  15. Automated planning of ablation targets in atrial fibrillation treatment

    NASA Astrophysics Data System (ADS)

    Keustermans, Johannes; De Buck, Stijn; Heidbüchel, Hein; Suetens, Paul

    2011-03-01

    Catheter based radio-frequency ablation is used as an invasive treatment of atrial fibrillation. This procedure is often guided by the use of 3D anatomical models obtained from CT, MRI or rotational angiography. During the intervention the operator accurately guides the catheter to prespecified target ablation lines. The planning stage, however, can be time consuming and operator dependent which is suboptimal both from a cost and health perspective. Therefore, we present a novel statistical model-based algorithm for locating ablation targets from 3D rotational angiography images. Based on a training data set of 20 patients, consisting of 3D rotational angiography images with 30 manually indicated ablation points, a statistical local appearance and shape model is built. The local appearance model is based on local image descriptors to capture the intensity patterns around each ablation point. The local shape model is constructed by embedding the ablation points in an undirected graph and imposing that each ablation point only interacts with its neighbors. Identifying the ablation points on a new 3D rotational angiography image is performed by proposing a set of possible candidate locations for each ablation point, as such, converting the problem into a labeling problem. The algorithm is validated using a leave-one-out-approach on the training data set, by computing the distance between the ablation lines obtained by the algorithm and the manually identified ablation points. The distance error is equal to 3.8+/-2.9 mm. As ablation lesion size is around 5-7 mm, automated planning of ablation targets by the presented approach is sufficiently accurate.

  16. Catheter Ablation of Fascicular Ventricular Tachycardia

    PubMed Central

    Liu, Yaowu; Fang, Zhen; Yang, Bing; Kojodjojo, Pipin; Chen, Hongwu; Ju, Weizhu; Cao, Kejiang; Chen, Minglong

    2015-01-01

    Background— Fascicular ventricular tachycardia (FVT) is a common form of sustained idiopathic left ventricular tachycardia with an Asian preponderance. This study aimed to prospectively investigate long-term clinical outcomes of patients undergoing ablation of FVT and identify predictors of arrhythmia recurrence. Methods and Results— Consecutive patients undergoing FVT ablation at a single tertiary center were enrolled. Activation mapping was performed to identify the earliest presystolic Purkinje potential during FVT that was targeted by radiofrequency ablation. Follow-up with clinic visits, ECG, and Holter monitoring was performed at least every 6 months. A total of 120 consecutive patients (mean age, 29.3±12.7 years; 82% men; all patients with normal ejection fraction) were enrolled. FVT involved left posterior fascicle and left anterior fascicle in 118 and 2 subjects, respectively. VT was noninducible in 3 patients, and ablation was acutely successful in 117 patients. With a median follow-up of 55.7 months, VT of a similar ECG morphology recurred in 17 patients, and repeat procedure confirmed FVT recurrence involving the same fascicle. Shorter VT cycle length was the only significant predictor of FVT recurrence (P=0.03). Six other patients developed new-onset upper septal FVT that was successfully ablated. Conclusions— Ablation of FVT guided by activation mapping is associated with a single procedural success rate without the use of antiarrhythmic drugs of 80.3%. Arrhythmia recurrences after an initially successful ablation were caused by recurrent FVT involving the same fascicle in two thirds of patients or new onset of upper septal FVT in the remainder. PMID:26386017

  17. Microwave Ablation of Hepatic Malignancy

    PubMed Central

    Lubner, Meghan G.; Brace, Christopher L.; Ziemlewicz, Tim J.; Hinshaw, J. Louis; Lee, Fred T.

    2013-01-01

    Microwave ablation is an extremely promising heat-based thermal ablation modality that has particular applicability in treating hepatic malignancies. Microwaves can generate very high temperatures in very short time periods, potentially leading to improved treatment efficiency and larger ablation zones. As the available technology continues to improve, microwave ablation is emerging as a valuable alternative to radiofrequency ablation in the treatment of hepatic malignancies. This article reviews the current state of microwave ablation including technical and clinical considerations. PMID:24436518

  18. Microwave ablation versus laser ablation in occluding lateral veins in goats.

    PubMed

    Wang, Xu-hong; Wang, Xiao-ping; Su, Wen-juan; Yuan, Yuan

    2016-02-01

    Increasing number of endovenous techniques are available for the treatment of saphenous vein reflux and endovenous laser ablation (EVLA) is a frequently used method. A newly developed alternative, based on thermal therapy, is endovenous microwave ablation (EMA). This study evaluated the effect of the two procedures, in terms of coagulation and histological changes, in occluding lateral veins in goats. Twelve animals were randomized into two group, with 6 treated with EMA (EMA group), and the rest 6 with EVLA (EVLA group). Results of coagulation, including coagulation, fibrinolysis and platelet activation, were assessed at three or four different time points: before, immediately after, 24 h (and 48 h) after ablation. The diameter change, a measure of efficacy, was ultrasonographically measured before and 1 month after the ablation. Histological changes were grossly and microscopically evaluated immediately, 1 and 3 month(s) after the ablation. The length of the ablated vein and preoperative average diameter were comparable between the two groups. In both EMA and EVLA groups, several coagulation parameters, fibrinolysis and platelet activation parameters only underwent slight changes. Ultrasound imaging displayed that the diameter reduction of the veins treated by EMA was significantly larger than by EVLA, in consistent with the results of macroscopic examination. Microscopic examination revealed necrosis and thickening of the vein wall, and occlusion of the lumen within 3 months after ablation in both EMA and EVLA groups. It is concluded that EMA is a minimally invasive therapy, which appears to be safe and effective for treatment of lateral veins in goats. PMID:26838749

  19. Burn, freeze, or photo-ablate?: comparative symptom profile in Barrett's dysplasia patients undergoing endoscopic ablation

    NASA Astrophysics Data System (ADS)

    Gill, Kanwar Rupinder S.; Gross, Seth A.; Greenwald, Bruce D.; Hemminger, Lois L.; Wolfsen, Herbert C.

    2009-06-01

    Background: There are few data available comparing endoscopic ablation methods for Barrett's esophagus with high-grade dysplasia (BE-HGD). Objective: To determine differences in symptoms and complications associated with endoscopic ablation. Design: Prospective observational study. Setting: Two tertiary care centers in USA. Patients: Consecutive patients with BE-HGD Interventions: In this pilot study, symptoms profile data were collected for BE-HGD patients among 3 endoscopic ablation methods: porfimer sodium photodynamic therapy, radiofrequency ablation and low-pressure liquid nitrogen spray cryotherapy. Main Outcome Measurements: Symptom profiles and complications from the procedures were assessed 1-8 weeks after treatment. Results: Ten BE-HGD patients were treated with each ablation modality (30 patients total; 25 men, median age: 69 years (range 53-81). All procedures were performed in the clinic setting and none required subsequent hospitalization. The most common symptoms among all therapies were chest pain, dysphagia and odynophagia. More patients (n=8) in the porfimer sodium photodynamic therapy group reported weight loss compared to radio-frequency ablactation (n=2) and cryotherapy (n=0). Four patients in the porfimer sodium photodynamic therapy group developed phototoxicity requiring medical treatment. Strictures, each requiring a single dilation, were found in radiofrequency ablactation (n=1) and porfimer sodium photodynamic therapy (n=2) patients. Limitations: Small sample size, non-randomized study. Conclusions: These three endoscopic therapies are associated with different types and severity of post-ablation symptoms and complications.

  20. Conservative Management of Left Atrial Intramural Hematoma after Catheter Ablation

    PubMed Central

    Oraii, Saeed; Roshanali, Farideh; Ghorbanisharif, Alireza; Mikaeili, Javad; Tahraei, Mahmood

    2016-01-01

    Left atrial intramural hematoma is a very rare complication of radiofrequency ablation procedures. A patient with tachyarrhythmia underwent radiofrequency catheter ablation. Echocardiography performed the following morning showed a large mass in the left atrium, suggestive of intramural hematoma formation. The patient was in a stable condition; therefore, it was decided that follow-up should be conservative and her anticoagulation therapy was continued. The size of the hematoma decreased significantly over the following 50 days. This case highlights a rare complication of a complex catheter ablation procedure in the left atrium that was managed via a noninvasive approach, with which all interventionists should be familiar. PMID:27482270

  1. Present concepts in management of atrial fibrillation: From drug therapy to ablation

    PubMed Central

    Forleo, Giovanni B; Santini, Luca; Romeo, Francesco

    2009-01-01

    Atrial fibrillation (AF) management requires knowledge of its pattern of presentation, underlying conditions, and decisions about restoration and maintenance of sinus rhythm, control of the ventricular rate, and anti-thrombotic therapy. Maintenance of sinus rhythm is a desirable goal in AF patients because the prevention of recurrence may improve cardiac function, relieve symptoms and reduce the likelihood of adverse events. Anti-arrhythmic drug therapy is the first-line treatment for patients with paroxysmal and persistent AF based on current guidelines. However, currently used drugs have limited efficacy and cause cardiac and extracardiac toxicity. Thus, there is a continued need to develop new drugs, device and ablative approaches to rhythm management. Additionally, simpler and safer stroke prevention regimens are needed for AF patients on life-long anticoagulation, including occlusion of the left atrial appendage. The results of the Randomized Evaluation of Long-Term Anticoagulant Therapy study are encouraging in these settings. Knowledge on the pathophysiology of AF is rapidly expanding and identification of focally localized triggers has led to the development of new treatment options for this arrhythmia. Conversely, the clinical decision whether to restore and maintain sinus rhythm or simply control the ventricular rate has remained a matter of intense debate. In the minority of patients in whom AF cannot be adequately managed by pharmacological therapy, the most appropriate type of non-pharmacological therapy must be selected on an individualized basis. Curative treatment of AF with catheter ablation is now a legitimate option for a large number of patients. The evolution of hybrid therapy, in which two or more different strategies are employed in the same patient, may be an effective approach to management of AF. In any case, planning a treatment regimen for AF should include evaluation of the risks inherent in the use of various drugs as well as more

  2. General Model for Multicomponent Ablation Thermochemistry

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Marschall, Jochen; Rasky, Daniel J. (Technical Monitor)

    1994-01-01

    A previous paper (AIAA 94-2042) presented equations and numerical procedures for modeling the thermochemical ablation and pyrolysis of thermal protection materials which contain multiple surface species. This work describes modifications and enhancements to the Multicomponent Ablation Thermochemistry (MAT) theory and code for application to the general case which includes surface area constraints, rate limited surface reactions, and non-thermochemical mass loss (failure). Detailed results and comparisons with data are presented for the Shuttle Orbiter reinforced carbon-carbon oxidation protection system which contains a mixture of sodium silicate (Na2SiO3), silica (SiO2), silicon carbide (SiC), and carbon (C).

  3. Difficulties with Ablation for Arrhythmias in Children

    PubMed Central

    Asirvatham, Samuel J

    2008-01-01

    Radiofrequency ablation procedures in children present unique challenges for the electrophysiologist. At times, obtaining vascular access to reach the heart is a problem. If this first step is accomplished, the small size of the child's heart, arrhythmias relatively unique to the pediatric population, and the presence of congenital heart disease add to the complexity. In this manuscript, a review of commonly encountered problems and suggested solutions based on practice are presented. Precise mapping of the arrhythmogenic substrate, techniques to access excluded portions of the atrium from prior surgery, and the basis for electrophysiology maneuvers important in pediatric ablation are highlighted. PMID:18478062

  4. Value of Implantable Loop Recorders in Monitoring Efficacy of Radiofrequency Catheter Ablation in Atrial Fibrillation

    PubMed Central

    Yang, Ping; Pu, Lijin; Yang, Liuqing; Li, Fang; Luo, Zhiling; Guo, Tao; Hua, Baotong; Li, Shumin

    2016-01-01

    Background The aim of this study was to evaluate the value of the implantable loop recorder (ILR) in diagnosing atrial fibrillation (AF) and assessing the postoperative efficacy of radiofrequency catheter ablation (RFCA). Material/Methods A total of 32 patients who successfully underwent RFCA were selected. These patients discontinued antiarrhythmic medication with no AF recurrence for more than 3 months after RFCA, and underwent ILR placement by a conventional method. The clinical manifestations and information on arrhythmias recorded by the ILR were followed up to assess the efficacy of AF RFCA. Results The mean follow-up period was 24.7±12.5 months. Of 32 patients with ILR information, 27 had successful RFCA and 5 had recurrent AF. The follow-up results obtained by traditional methods showed 29 patients with successful RFCA and 3 with recurrent AF (P<0.05). Among the 18 patients with clinical symptoms, 13 had recorded cardiac arrhythmic events (72.2%) and 5 showed sinus rhythm (27.8%). The ILRs recorded 18 patients with arrhythmic events (56.3%), including 12 cases of atrial arrhythmias, among whom 5 recurred at 9, 12, 16, 17, and 32 months after AF RFCA; there were also 2 patients with ventricular tachycardia (VT) and 4 with bradycardia. Conclusions The value of ILR in assessing the efficacy of AF RFCA was superior to that of traditional methods. ILR can promptly detect asymptomatic AF, and can monitor electrocardiogram features after RFCA, thus providing objective evidence of efficacy. PMID:27518153

  5. Osteoid Osteoma: Experience with Laser- and Radiofrequency-Induced Ablation

    SciTech Connect

    Gebauer, Bernhard Tunn, Per-Ulf; Gaffke, Gunnar; Melcher, Ingo; Felix, Roland; Stroszczynski, Christian

    2006-04-15

    The purpose of this study was to analyze the clinical outcome of osteoid osteoma treated by thermal ablation after drill opening. A total of 17 patients and 20 procedures were included. All patients had typical clinical features (age, pain) and a typical radiograph showing a nidus. In 5 cases, additional histological specimens were acquired. After drill opening of the osteoid osteoma nidus, 12 thermal ablations were induced by laser interstitial thermal therapy (LITT) (9F Power-Laser-Set; Somatex, Germany) and 8 ablations by radiofrequency ablation (RFA) (RITA; StarBurst, USA). Initial clinical success with pain relief has been achieved in all patients after the first ablation. Three patients had an osteoid osteoma recurrence after 3, 9, and 10 months and were successfully re-treated by thermal ablation. No major complication and one minor complication (sensible defect) were recorded. Thermal ablation is a safe and minimally invasive therapy option for osteoid osteoma. Although the groups are too small for a comparative analysis, we determined no difference between laser- and radiofrequency-induced ablation in clinical outcome after ablation.

  6. Delayed Development of Pneumothorax After Pulmonary Radiofrequency Ablation

    SciTech Connect

    Clasen, Stephan; Kettenbach, Joachim; Kosan, Bora; Aebert, Hermann; Schernthaner, Melanie; Kroeber, Stefan-Martin; Boemches, Andrea; Claussen, Claus D.; Pereira, Philippe L.

    2009-05-15

    Acute pneumothorax is a frequent complication after percutaneous pulmonary radiofrequency (RF) ablation. In this study we present three cases showing delayed development of pneumothorax after pulmonary RF ablation in 34 patients. Our purpose is to draw attention to this delayed complication and to propose a possible approach to avoid this major complication. These three cases occurred subsequent to 44 CT-guided pulmonary RF ablation procedures (6.8%) using either internally cooled or multitined expandable RF electrodes. In two patients, the pneumothorax, being initially absent at the end of the intervention, developed without symptoms. One of these patients required chest drain placement 32 h after RF ablation, and in the second patient therapy remained conservative. In the third patient, a slight pneumothorax at the end of the intervention gradually increased and led into tension pneumothorax 5 days after ablation procedure. Underlying bronchopleural fistula along the coagulated former electrode track was diagnosed in two patients. In conclusion, delayed development of pneumothorax after pulmonary RF ablation can occur and is probably due to underlying bronchopleural fistula, potentially leading to tension pneumothorax. Patients and interventionalists should be prepared for delayed onset of this complication, and extensive track ablation following pulmonary RF ablation should be avoided.

  7. Novel catheter enabling simultaneous radiofrequency ablation and optical coherence reflectometry

    PubMed Central

    Herranz, D.; Lloret, Juan; Jiménez-Valero, Santiago; Rubio-Guivernau, J. L.; Margallo-Balbás, Eduardo

    2015-01-01

    A novel radiofrequency ablation catheter has been developed with integrated custom designed optics, enabling real-time monitoring of radiofrequency ablation procedures through polarization-sensitive optical coherence reflectometry. The optics allow for proper tissue illumination through a view-port machined in the catheter tip, thus providing lesion depth control over the RF ablation treatment. The system was verified in an in-vitro model of swine myocardium. Optical performance and thermal stability was confirmed after more than 25 procedures, without any damage to the optical assembly induced by thermal stress or material degradation. The use of this catheter in RF ablation treatments may make possible to assess lesion depth during therapy, thus translating into a reduction of potential complications on the procedure. PMID:26417499

  8. Study about AFS swerve mode

    NASA Astrophysics Data System (ADS)

    Liu, Hong; Jiang, Lanfang; Zhao, Qin; Wang, Li

    2009-11-01

    A swerving mathematical model was established after stating the shortage of the present AFS swerving algorithm. The conception of 'expected lighting distance' was extended to 'expected lighting bound' and approximate treatment of geometry of light beam falling to ground of headlamp was processed. The expected lighting bound was ascertained and the lighting range of turning angle of headlamp was calculated. The calculation formula of turning angle of headlamp was worked out. It was indicated that the turning angle of inside and outside of headlamp calculated by revised algorithm was reasonable by comparing calculation. Finally the control strategy about the turning angle of inside and outside headlamp when turning was worked out. It is of practical significance in promoting the active safety, reducing the traffic accidents caused by insufficient angle and range of irradiation of headlamp.

  9. Eaton AF5000+Genesis Communication Driver

    1995-05-25

    Communication driver allows the Genesis Control Series software to interact with Eaton AF5000+ frequency drives via RS-232 communications. All Eaton AF5000+ parameters that support communications are supported by the Genesis driver. Multidrop addressing to multiple units is available with the Genesis communication driver.

  10. Convergent ablator performance measurements

    SciTech Connect

    Hicks, D. G.; Spears, B. K.; Braun, D. G.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L.; Olson, R. E.

    2010-10-15

    The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other convergent ablator performance parameters have been measured using a single streaked x-ray radiograph. Traditional Abel inversion of such a radiograph is ill-posed since backlighter intensity profiles and x-ray attenuation by the ablated plasma are unknown. To address this we have developed a regularization technique which allows the ablator density profile {rho}(r) and effective backlighter profile I{sub 0}(y) at each time step to be uniquely determined subject to the constraints that {rho}(r) is localized in radius space and I{sub 0}(y) is delocalized in object space. Moments of {rho}(r) then provide the time-resolved areal density, mass, and average radius (and thus velocity) of the remaining ablator material. These results are combined in the spherical rocket model to determine the ablation pressure and mass ablation rate during the implosion. The technique has been validated on simulated radiographs of implosions at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)] and implemented on experiments at the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)].

  11. Tumor Ablation and Nanotechnology

    PubMed Central

    Manthe, Rachel L.; Foy, Susan P.; Krishnamurthy, Nishanth; Sharma, Blanka; Labhasetwar, Vinod

    2010-01-01

    Next to surgical resection, tumor ablation is a commonly used intervention in the treatment of solid tumors. Tumor ablation methods include thermal therapies, photodynamic therapy, and reactive oxygen species (ROS) producing agents. Thermal therapies induce tumor cell death via thermal energy and include radiofrequency, microwave, high intensity focused ultrasound, and cryoablation. Photodynamic therapy and ROS producing agents cause increased oxidative stress in tumor cells leading to apoptosis. While these therapies are safe and viable alternatives when resection of malignancies is not feasible, they do have associated limitations that prevent their widespread use in clinical applications. To improve the efficacy of these treatments, nanoparticles are being studied in combination with nonsurgical ablation regimens. In addition to better thermal effect on tumor ablation, nanoparticles can deliver anticancer therapeutics that show synergistic anti-tumor effect in the presence of heat and can also be imaged to achieve precision in therapy. Understanding the molecular mechanism of nanoparticle-mediated tumor ablation could further help engineer nanoparticles of appropriate composition and properties to synergize the ablation effect. This review aims to explore the various types of nonsurgical tumor ablation methods currently used in cancer treatment and potential improvements by nanotechnology applications. PMID:20866097

  12. Convergent ablator performance measurements

    NASA Astrophysics Data System (ADS)

    Hicks, D. G.; Spears, B. K.; Braun, D. G.; Olson, R. E.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L.

    2010-10-01

    The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other convergent ablator performance parameters have been measured using a single streaked x-ray radiograph. Traditional Abel inversion of such a radiograph is ill-posed since backlighter intensity profiles and x-ray attenuation by the ablated plasma are unknown. To address this we have developed a regularization technique which allows the ablator density profile ρ(r ) and effective backlighter profile I0(y) at each time step to be uniquely determined subject to the constraints that ρ(r ) is localized in radius space and I0(y) is delocalized in object space. Moments of ρ(r ) then provide the time-resolved areal density, mass, and average radius (and thus velocity) of the remaining ablator material. These results are combined in the spherical rocket model to determine the ablation pressure and mass ablation rate during the implosion. The technique has been validated on simulated radiographs of implosions at the National Ignition Facility [Miller et al., Nucl. Fusion 44, 228 (2004)] and implemented on experiments at the OMEGA laser facility [Boehly et al., Opt. Commun. 133, 495 (1997)].

  13. eNOS3 Genetic Polymorphism Is Related to Post-Ablation Early Recurrence of Atrial Fibrillation

    PubMed Central

    Shim, Jaemin; Park, Jae Hyung; Lee, Ji-Young; Uhm, Jae-Sun; Joung, Boyoung; Lee, Moon-Hyoung; Ellinor, Patrick T.

    2015-01-01

    Purpose Previous studies have demonstrated an association between eNOS polymorphisms and atrial fibrillation (AF). We sought to determine whether eNOS polymorphisms are associated with AF recurrence after a radiofrequency catheter ablation (RFCA). Materials and Methods A total of 500 consecutive patients (56±11 years, 77% male) with paroxysmal (68%) or persistent (32%) AF who underwent RFCA and 500 age, gender-matched controls were genotyped for the eNOS3 single nucleotide polymorphism (rs1799983). AF recurrence was monitored according to 2012 ACC/AHA/ESC guidelines. Results The frequencies of the rs1799983 variant alleles (T) in the case and control group were not significantly different (OR 1.05, 95% CI 0.75-1.46, p=0.798). AF patients with rs1799983 variants were more likely to have coronary artery disease or stroke than those without genetic variant at this gene (31.0% vs. 17.3%, p=0.004). During mean 17 months follow-up, early recurrence of AF (ERAF; within 3 months) and clinical recurrence (CR) of AF were 31.8% and 24.8%, respectively. The rs1799983 variant was associated with higher risk of ERAF (OR 1.71, 95% CI 1.06-2.79, p=0.028), but not with CR. ERAF occurred earlier (11±16 days) in variant group than those without variant allele (20±25 days, p=0.016). A multiple logistic regression analysis showed that presence of the rs1799983 variant (OR 1.75, 95% CI 1.07-2.86, p=0.026) and persistent AF were independent predictors for ERAF after AF ablation. Conclusion The rs1799983 variant of the eNOS3 gene was associated with ERAF, but not with CR, after RFCA. eNOS3 gene variants may have a potential role for stratification of post-ablation management. PMID:26256966

  14. Photoacoustic characterization of radiofrequency ablation lesions

    NASA Astrophysics Data System (ADS)

    Bouchard, Richard; Dana, Nicholas; Di Biase, Luigi; Natale, Andrea; Emelianov, Stanislav

    2012-02-01

    Radiofrequency ablation (RFA) procedures are used to destroy abnormal electrical pathways in the heart that can cause cardiac arrhythmias. Current methods relying on fluoroscopy, echocardiography and electrical conduction mapping are unable to accurately assess ablation lesion size. In an effort to better visualize RFA lesions, photoacoustic (PA) and ultrasonic (US) imaging were utilized to obtain co-registered images of ablated porcine cardiac tissue. The left ventricular free wall of fresh (i.e., never frozen) porcine hearts was harvested within 24 hours of the animals' sacrifice. A THERMOCOOLR Ablation System (Biosense Webster, Inc.) operating at 40 W for 30-60 s was used to induce lesions through the endocardial and epicardial walls of the cardiac samples. Following lesion creation, the ablated tissue samples were placed in 25 °C saline to allow for multi-wavelength PA imaging. Samples were imaged with a VevoR 2100 ultrasound system (VisualSonics, Inc.) using a modified 20-MHz array that could provide laser irradiation to the sample from a pulsed tunable laser (Newport Corp.) to allow for co-registered photoacoustic-ultrasound (PAUS) imaging. PA imaging was conducted from 750-1064 nm, with a surface fluence of approximately 15 mJ/cm2 maintained during imaging. In this preliminary study with PA imaging, the ablated region could be well visualized on the surface of the sample, with contrasts of 6-10 dB achieved at 750 nm. Although imaging penetration depth is a concern, PA imaging shows promise in being able to reliably visualize RF ablation lesions.

  15. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation of liver tumours

    PubMed Central

    Bartels, L.W.; Deckers, R.; Ries, M.; Mali, W.P.Th.M.; Moonen, C.T.W.; van den Bosch, M.A.A.J.

    2012-01-01

    Abstract Recent decades have seen a paradigm shift in the treatment of liver tumours from invasive surgical procedures to minimally invasive image-guided ablation techniques. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a novel, completely non-invasive ablation technique that has the potential to change the field of liver tumour ablation. The image guidance, using MR imaging and MR temperature mapping, provides excellent planning images and real-time temperature information during the ablation procedure. However, before clinical implementation of MR-HIFU for liver tumour ablation is feasible, several organ-specific challenges have to be addressed. In this review we discuss the MR-HIFU ablation technique, the liver-specific challenges for MR-HIFU tumour ablation, and the proposed solutions for clinical translation. PMID:23022541

  16. Outcomes registry for better informed treatment of atrial fibrillation II: Rationale and design of the ORBIT-AF II registry

    PubMed Central

    Steinberg, Benjamin A.; Blanco, Rosalia G.; Ollis, Donna; Kim, Sunghee; Holmes, DaJuanicia N.; Kowey, Peter R.; Fonarow, Gregg C.; Ansell, Jack; Gersh, Bernard; Go, Alan S.; Hylek, Elaine; Mahaffey, Kenneth W.; Thomas, Laine; Chang, Paul; Peterson, Eric D.; Piccini, Jonathan P.

    2014-01-01

    Background Recent clinical trials have demonstrated the safety and efficacy of several non–vitamin K oral anticoagulants (NOACs) for the treatment of atrial fibrillation (AF). However, there are limited data on their use and outcomes in routine clinical practice, particularly among patients newly diagnosed as having AF and patients with AF recently transitioned to a NOAC. Methods/Design ORBIT-AF II is a multicenter, national registry of patients with AF that is enrolling up to 15,000 newly diagnosed patients with AF and/or those with AF recently transitioned to a NOAC from 300 US outpatient practices. These patients will be followed for up to 2 years, including clinical status, outcomes (major adverse cardiovascular events, bleeding), and management of anticoagulation surrounding bleeding events. In addition, detailed data regarding the use of these agents in and around cardiac procedures, their complications, and management of such complications will be collected. Conclusions The ORBIT-AF II registry will provide valuable insights into the safety and effectiveness of NOACs used in AF in community practice settings. PMID:25066554

  17. Ablation of kidney tumors.

    PubMed

    Karam, Jose A; Ahrar, Kamran; Matin, Surena F

    2011-04-01

    While surgical excision remains the gold standard for curative treatment of small renal cell carcinomas, ablative therapy has a place as a minimally invasive, kidney function-preserving therapy in carefully selected patients who are poor candidates for surgery. Although laparoscopic cryoablation and percutaneous radiofrequency ablation (RFA) are commonly performed, percutaneous cryoablation and laparoscopic RFA are reportedly being performed with increasing frequency. The renal function and complication profiles following ablative therapy are favorable, while oncologic outcomes lag behind those of surgery, thus reinforcing the need for careful patient selection. PMID:21377587

  18. GPU-based real-time approximation of the ablation zone for radiofrequency ablation.

    PubMed

    Rieder, Christian; Kröger, Tim; Schumann, Christian; Hahn, Horst K

    2011-12-01

    Percutaneous radiofrequency ablation (RFA) is becoming a standard minimally invasive clinical procedure for the treatment of liver tumors. However, planning the applicator placement such that the malignant tissue is completely destroyed, is a demanding task that requires considerable experience. In this work, we present a fast GPU-based real-time approximation of the ablation zone incorporating the cooling effect of liver vessels. Weighted distance fields of varying RF applicator types are derived from complex numerical simulations to allow a fast estimation of the ablation zone. Furthermore, the heat-sink effect of the cooling blood flow close to the applicator's electrode is estimated by means of a preprocessed thermal equilibrium representation of the liver parenchyma and blood vessels. Utilizing the graphics card, the weighted distance field incorporating the cooling blood flow is calculated using a modular shader framework, which facilitates the real-time visualization of the ablation zone in projected slice views and in volume rendering. The proposed methods are integrated in our software assistant prototype for planning RFA therapy. The software allows the physician to interactively place virtual RF applicator models. The real-time visualization of the corresponding approximated ablation zone facilitates interactive evaluation of the tumor coverage in order to optimize the applicator's placement such that all cancer cells are destroyed by the ablation. PMID:22034298

  19. Ablative skin resurfacing.

    PubMed

    Agrawal, Nidhi; Smith, Greg; Heffelfinger, Ryan

    2014-02-01

    Ablative laser resurfacing has evolved as a safe and effective treatment for skin rejuvenation. Although traditional lasers were associated with significant thermal damage and lengthy recovery, advances in laser technology have improved safety profiles and reduced social downtime. CO2 lasers remain the gold standard of treatment, and fractional ablative devices capable of achieving remarkable clinical improvement with fewer side effects and shorter recovery times have made it a more practical option for patients. Although ablative resurfacing has become safer, careful patient selection and choice of suitable laser parameters are essential to minimize complications and optimize outcomes. This article describes the current modalities used in ablative laser skin resurfacing and examines their efficacy, indications, and possible side effects. PMID:24488638

  20. Moldable cork ablation material

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A successful thermal ablative material was manufactured. Moldable cork sheets were tested for density, tensile strength, tensile elongation, thermal conductivity, compression set, and specific heat. A moldable cork sheet, therefore, was established as a realistic product.

  1. Radiofrequency Ablation of Subpleural Lung Malignancy: Reduced Pain Using an Artificially Created Pneumothorax

    SciTech Connect

    Lee, Edward W. Suh, Robert D.; Zeidler, Michelle R.; Tsai, Irene S.; Cameron, Robert B.; Abtin, Fereidoun G.; Goldin, Jonathan G.

    2009-07-15

    One of the main issues with radiofrequency (RF) ablation of the subpleural lung malignancy is pain management during and after RF ablation. In this article, we present a case that utilized a technique to decrease the pain associated with RF ablation of a malignancy located within the subpleural lung. Under CT guidance, we created an artificial pneumothorax prior to the RF ablation, which resulted in minimizing the pain usually experienced during and after the procedure. It also decreased the amount of pain medications usually used in patients undergoing RF ablation of a subpleural lung lesion.

  2. Laser ablation of concrete.

    SciTech Connect

    Savina, M.

    1998-10-05

    Laser ablation is effective both as an analytical tool and as a means of removing surface coatings. The elemental composition of surfaces can be determined by either mass spectrometry or atomic emission spectroscopy of the atomized effluent. Paint can be removed from aircraft without damage to the underlying aluminum substrate, and environmentally damaged buildings and sculptures can be restored by ablating away deposited grime. A recent application of laser ablation is the removal of radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on concrete samples using a high power pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied on various model systems consisting of Type I Portland cement with varying amounts of either fine silica or sand in an effort to understand the effect of substrate composition on ablation rates and mechanisms. A sample of non-contaminated concrete from a nuclear power plant was also studied. In addition, cement and concrete samples were doped with non-radioactive isotopes of elements representative of cooling waterspills, such as cesium and strontium, and analyzed by laser-resorption mass spectrometry to determine the contamination pathways. These samples were also ablated at high power to determine the efficiency with which surface contaminants are removed and captured. The results show that the neat cement matrix melts and vaporizes when little or no sand or aggregate is present. Surface flows of liquid material are readily apparent on the ablated surface and the captured aerosol takes the form of glassy beads up to a few tens of microns in diameter. The presence of sand and aggregate particles causes the material to disaggregate on ablation, with intact particles on the millimeter size scale leaving the surface. Laser resorption mass spectrometric analysis showed that cesium and potassium have similar chemical environments in the

  3. Durable Superhydrophobic Surfaces via Spontaneous Wrinkling of Teflon AF.

    PubMed

    Scarratt, Liam R J; Hoatson, Ben S; Wood, Elliot S; Hawkett, Brian S; Neto, Chiara

    2016-03-16

    We report the fabrication of both single-scale and hierarchical superhydrophobic surfaces, created by exploiting the spontaneous wrinkling of a rigid Teflon AF film on two types of shrinkable plastic substrates. Sub-100 nm to micrometric wrinkles were reproducibly generated by this simple process, with remarkable control over the size and hierarchy. Hierarchical Teflon AF wrinkled surfaces showed extremely high water repellence (contact angle 172°) and very low contact angle hysteresis (2°), resulting in droplets rolling off the surface at tilt angles lower than 5°. The wrinkling process intimately binds the Teflon AF layer with its substrate, making these surfaces mechanically robust, as revealed by macroscale and nanoscale wear tests: hardness values were close to that of commercial optical lenses and aluminum films, resistance to scratch was comparable to commercial hydrophobic coatings, and damage by extensive sonication did not significantly affect water repellence. By this fabrication method the size of the wrinkles can be reproducibly tuned from the nanoscale to the microscale, across the whole surface in one step; the fabrication procedure is extremely rapid, requiring only 2 min of thermal annealing to produce the desired topography, and uses inexpensive materials. The very low roll-off angles achieved in the hierarchical surfaces offer a potentially up-scalable alternative as self-cleaning and drag-reducing coatings. PMID:26910574

  4. Autonomic mechanism for initiation of rapid firing from atria and pulmonary veins: evidence by ablation of ganglionated plexi

    PubMed Central

    Lu, Zhibing; Scherlag, Benjamin J.; Lin, Jiaxiong; Yu, Lilei; Guo, Ji-Hong; Niu, Guodong; Jackman, Warren M.; Lazzara, Ralph; Jiang, Hong; Po, Sunny S.

    2009-01-01

    Aims Previous studies showed that autonomic activation by high-frequency electrical stimulation (HFS) during myocardial refractoriness evokes rapid firing from pulmonary vein (PV) and atria, both in vitro and in vivo. This study sought to investigate the autonomic mechanism underlying the rapid firings at various sites by systematic ablation of multiple ganglionated plexi (GP). Methods and results In 43 mongrel dogs, rapid firing-mediated atrial fibrillation (AF) was induced by local HFS (200 Hz, impulse duration 0.1 ms, train duration 40 ms) to the PVs and atria during myocardial refractoriness. The main GP in the atrial fat pads or the ganglia along the ligament of Marshall (LOM) were then ablated. Ablation of the anterior right GP and inferior right GP significantly increased the AF threshold by HFS at the right atrium and PVs. The AF threshold at left atrium and PVs was significantly increased by ablation of the superior left GP and inferior left GP, and was further increased by ablation of the LOM. Ablation of left- or right-sided GP on the atria had a significant effect on contralateral PVs and atrium. Administration of esmolol (1 mg/kg) or atropine (1 mg) significantly increased AF threshold at all sites. Conclusion HFS applied to local atrial and PV sites initiated rapid firing via activation of the interactive autonomic network in the heart. GP in either left side or right side contributes to the rapid firings and AF originating from ipsolateral and contralateral PVs and atrium. Autonomic denervation suppresses or eliminates those rapid firings. PMID:19520703

  5. Incidence and Cause of Hypertension During Adrenal Radiofrequency Ablation

    SciTech Connect

    Yamakado, Koichiro Takaki, Haruyuki; Yamada, Tomomi; Yamanaka, Takashi; Uraki, Junji; Kashima, Masataka; Nakatsuka, Atsuhiro; Takeda, Kan

    2012-12-15

    Purpose: To evaluate the incidence and cause of hypertension prospectively during adrenal radiofrequency ablation (RFA). Methods: For this study, approved by our institutional review board, written informed consent was obtained from all patients. Patients who received RFA for adrenal tumors (adrenal ablation) and other abdominal tumors (nonadrenal ablation) were included in this prospective study. Blood pressure was monitored during RFA. Serum adrenal hormone levels including epinephrine, norepinephrine, dopamine, and cortisol levels were measured before and during RFA. The respective incidences of procedural hypertension (systolic blood pressure >200 mmHg) of the two patient groups were compared. Factors correlating with procedural systolic blood pressure were evaluated by regression analysis.ResultsNine patients underwent adrenal RFA and another 9 patients liver (n = 5) and renal (n = 4) RFA. Asymptomatic procedural hypertension that returned to the baseline by injecting calcium blocker was found in 7 (38.9%) of 18 patients. The incidence of procedural hypertension was significantly higher in the adrenal ablation group (66.7%, 6/9) than in the nonadrenal ablation group (11.1%, 1/9, P < 0.0498). Procedural systolic blood pressure was significantly correlated with serum epinephrine (R{sup 2} = 0.68, P < 0.0001) and norepinephrine (R{sup 2} = 0.72, P < 0.0001) levels during RFA. The other adrenal hormones did not show correlation with procedural systolic blood pressure. Conclusion: Hypertension occurs frequently during adrenal RFA because of the release of catecholamine.

  6. Ablation characteristics of quantum square pulse mode dental erbium laser

    NASA Astrophysics Data System (ADS)

    Lukač, Nejc; Suhovršnik, Tomaž; Lukač, Matjaž; Jezeršek, Matija

    2016-01-01

    Erbium lasers are by now an accepted tool for performing ablative medical procedures, especially when minimal invasiveness is desired. Ideally, a minimally invasive laser cutting procedure should be fast and precise, and with minimal pain and thermal side effects. All these characteristics are significantly influenced by laser pulse duration, albeit not in the same manner. For example, high cutting efficacy and low heat deposition are characteristics of short pulses, while vibrations and ejected debris screening are less pronounced at longer pulse durations. We report on a study of ablation characteristics on dental enamel and cementum, of a chopped-pulse Er:YAG [quantum square pulse (QSP)] mode, which was designed to reduce debris screening during an ablation process. It is shown that in comparison to other studied standard Er:YAG and Er,Cr:YSGG laser pulse duration modes, the QSP mode exhibits the highest ablation drilling efficacy with lowest heat deposition and reduced vibrations, demonstrating that debris screening has a considerable influence on the ablation process. By measuring single-pulse ablation depths, we also show that tissue desiccation during the consecutive delivery of laser pulses leads to a significant reduction of the intrinsic ablation efficacy that cannot be fully restored under clinical settings by rehydrating the tooth using an external water spray.

  7. RX-26-AY/AF rifle bullet tests

    SciTech Connect

    Sharp, D.D.

    1980-11-01

    A series of rifle bullet tests was performed on two explosives, RX-26-AY and RX-26-AF, using the Pantex version of the Picatinny Arsenal Test (PA-2). With the exception of one test, both explosives displayed a relatively low sensitivity to bullet impact. However, a marked difference was noted in the average burn time duration between the two types of explosives being tested. A minor modification was made on the rifle barrel used at the test site in order to improve the sighting procedure.

  8. Rotational angiography of left ventricle to guide ventricular tachycardia ablation.

    PubMed

    Wolf, Jiri; Starek, Zdenek; Jez, Jiri; Lehar, Frantisek; Lukasova, Marketa; Kulik, Tomas; Novak, Miroslav

    2015-06-01

    Three-dimensional rotational angiography (3 DRA) is a novel imaging method introduced to guide complex catheter ablations of the left atrium. Our aim was to investigate the feasibility of the method in visualization of left ventricular anatomy and to develop a corresponding protocol for guidance of ventricular tachycardia ablation. We performed 3D rotational angiography in 13 patients using a direct left atrial protocol for data acquisition and the 3D reconstruction of the left ventricle was achieved in all patients. Clinical data comparison has proved lower use of radiation and contrast medium during 3 DRA-guided ablations as compared to CT-guided procedures. PMID:25761532

  9. Ablation for atrial fibrillation during mitral valve surgery: 1-year results through continuous subcutaneous monitoring.

    PubMed

    Bogachev-Prokophiev, Alexandr; Zheleznev, Sergey; Romanov, Alexander; Pokushalov, Evgeny; Pivkin, Alexey; Corbucci, Giorgio; Karaskov, Alexander

    2012-07-01

    Continuous monitoring of cardiac rhythm may play an important role in measuring the true symptomatic/asymptomatic atrial fibrillation (AF) burden and improve the management of anti-arrhythmic and anti-thrombotic therapies. Forty-seven patients with mitral valve disease and longstanding persistent AF (LSPAF) underwent a left atrial maze procedure with bipolar radiofrequency and valve surgery. The follow-up data recorded by an implanted loop recorder were analysed after 3, 6 and 12 months. On discharge, 40 (85.1%) patients were in stable sinus rhythm, as documented by in-office electrocardiography (ECG), 4 (8.5%) were in pacemaker rhythm and 3 (6.4%) were in AF. One (2.1%) patient died after 7 months. On 12-month follow-up examination, 30 (65.2%) patients had an AF burden <0.5% and were classified as responders. Three (6.5%) of the 16 non-responders had atrial flutter and 13 (27.7%) had documented AF recurrences with an AF burden >0.5%. Two (4.3%) patients with AF recurrences were completely asymptomatic. Among the symptomatic events stored by the patients, only 27.6% was confirmed as genuine AF recurrences according to the concomitant ECG recorded by the implanted loop recorder. A concomitant bipolar maze procedure during mitral valve surgery is effective in treating AF, as proved by detailed 1-year continuous monitoring. PMID:22514258

  10. STBC AF relay for unmanned aircraft system

    NASA Astrophysics Data System (ADS)

    Adachi, Fumiyuki; Miyazaki, Hiroyuki; Endo, Chikara

    2015-01-01

    If a large scale disaster similar to the Great East Japan Earthquake 2011 happens, some areas may be isolated from the communications network. Recently, unmanned aircraft system (UAS) based wireless relay communication has been attracting much attention since it is able to quickly re-establish the connection between isolated areas and the network. However, the channel between ground station (GS) and unmanned aircraft (UA) is unreliable due to UA's swing motion and as consequence, the relay communication quality degrades. In this paper, we introduce space-time block coded (STBC) amplify-and-forward (AF) relay for UAS based wireless relay communication to improve relay communication quality. A group of UAs forms single frequency network (SFN) to perform STBC-AF cooperative relay. In STBC-AF relay, only conjugate operation, block exchange and amplifying are required at UAs. Therefore, STBC-AF relay improves the relay communication quality while alleviating the complexity problem at UAs. It is shown by computer simulation that STBC-AF relay can achieve better throughput performance than conventional AF relay.

  11. Percutaneous radiofrequency ablation of spinal osteoid osteoma under CT guidance

    PubMed Central

    Morassi, L G; Kokkinis, K; Karargyris, O; Vlachou, I; Kalokairinou, K; Pneumaticos, S G

    2014-01-01

    Objective: Osteoid osteoma (OO) accounts for approximately 10–12% of all benign bone tumours and 3% of all bone tumours. Spinal involvement appears in 10–25% of all cases. The purpose of this study was to evaluate the safety and efficacy of CT-guided radiofrequency (RF) ablation in the treatment of spinal OOs and report our experience. Methods: 13 patients suffering from spinal OO and treated at the authors' institution using CT-guided RF ablation were retrospectively evaluated. The RF probe was introduced through a 11-G Jamshidi® needle, and the lesion was heated at 90 °C for 6 min. Results: All procedures were considered technically successful as the correct positioning of the probe was proven by CT. 11 of the 13 patients reported pain relief after RF ablation. In two cases, RF ablation was repeated 1 month after the first procedure. Pain relief was achieved in both cases after the second procedure. No recurrence was reported throughout the follow-up. No complications like skin burn, soft-tissue haematoma, infection, vessel damage or neurological deficit were reported. Conclusion: This study demonstrates that CT-guided percutaneous RF ablation is a safe and effective method for the treatment of spinal OOs. Advances in knowledge: The data of this study support the efficacy and safety of the recently applied CT-guided percutaneous RF ablation technique for the treatment of spinal OOs. PMID:24712322

  12. Infrared laser bone ablation

    SciTech Connect

    Nuss, R.C.; Fabian, R.L.; Sarkar, R.; Puliafito, C.A.

    1988-01-01

    The bone ablation characteristics of five infrared lasers, including three pulsed lasers (Nd:YAG, lambda = 1064 micron; Hol:YSGG, lambda = 2.10 micron; and Erb:YAG, lambda = 2.94 micron) and two continuous-wave lasers (Nd:YAG, lambda = 1.064 micron; and CO/sub 2/, lambda = 10.6 micron), were studied. All laser ablations were performed in vitro, using moist, freshly dissected calvarium of guinea pig skulls. Quantitative etch rates of the three pulsed lasers were calculated. Light microscopy of histologic sections of ablated bone revealed a zone of tissue damage of 10 to 15 micron adjacent to the lesion edge in the case of the pulsed Nd:YAG and the Erb:YAG lasers, from 20 to 90 micron zone of tissue damage for bone ablated by the Hol:YSGG laser, and 60 to 135 micron zone of tissue damage in the case of the two continuous-wave lasers. Possible mechanisms of bone ablation and tissue damage are discussed.

  13. [Radiofrequency ablation of accessory pathways in pre-excitation syndrome].

    PubMed

    Pfeiffer, D; Tebbenjohanns, J; Jung, W; Manz, M; Lüderitz, B

    1993-04-16

    Various parameters relating to the radio-frequency ablation of accessory pathways were studied in 53 patients (27 males, 26 females: mean age 38.5 [14-64] years) with a history of paroxysmal tachycardia (over 1 month to 50 years), shown to be caused by an accessory pathway (Wolff-Parkinson-White syndrome). In all patients the following values were obtained: (1) number of procedures necessary to achieve permanent blockage of the accessory pathway (1-4); (2) duration of each procedure (45-420 min); (3) duration of fluoroscopy (5-102 min); (4) number of necessary radio-frequency applications (1-48); and (5) cumulative energy per procedure. To ablate left-lateral pathways (n = 10) required fewer procedures, shorter duration per procedure, shorter fluoroscopy time, fewer current applications and less total energy than coagulation of right-sided pathways (n = 10). Those various parameters were greatest for ablation of septal and para-septal pathways (n = 9). Pathways which conducted only retrogradely (n = 15) were more difficult to ablate than those with anterograde conduction (n = 38). There were two complications. In one case a tension pneumothorax occurred after faulty puncture of the subclavian vein; in the other, the left ventricle was perforated causing an acute tamponade which required pericardiocentesis with subsequent suture closure of the perforation. It is concluded that, in principle, all accessory pathways, regardless of their conduction potential and site, can be ablated by a radio-frequency current. PMID:8472633

  14. Impact of computed tomography image and contact force technology on catheter ablation for atrial fibrillation

    PubMed Central

    Marai, Ibrahim; Suleiman, Mahmoud; Blich, Miry; Lessick, Jonathan; Abadi, Sobhi; Boulos, Monther

    2016-01-01

    AIM: To investigate the impact of using computed tomography (CT) and contact force (CF) technology on recurrence of atrial tachyarrhythmia after atrial fibrillation (AF) ablation. METHODS: This non-randomized study included 2 groups of patients. All patients had symptomatic recurrent paroxysmal or persistent AF and were treated with at least 1 anti arrhythmic medication or intolerant to medication. The first group included 33 patients who underwent circumferential pulmonary veins isolation (PVI) for AF during 2012 and 2013 guided by CT image integration (Cartomerge, Biosense Webster, Diamond Bar, CA, United States) of left atrium and pulmonary veins into an electroanatomic mapping (EAM) system (CT group) using standard irrigated radiofrequency catheter (ThermoCool, Carto, Biosense Webster, Diamond Bar, CA, United States) or irrigated catheter with integrated CF sensor (Smart Touch, Carto, Biosense Webster, Diamond Bar, CA, United States). The second group included immediately preceding 32 patients who had circumferential PVI by standard irrigated catheter (ThermoCool) using only EAM (Carto) system (EAM group). Linear lesions were performed according to the discretion of operator. RESULTS: Sex, age, and persistent AF were not different between groups. PVI was achieved in all patients in both groups. Linear ablations including cavo-tricuspid isthmus and or roof line ablation were not different between groups. Free of atrial tachyarrhythmia during follow-up of 24 mo was significantly higher among CT group compared to EAM group (81% vs 55%; respectively; P = 0.027). When 11 patients from CT group who had ablation using Smart Touch catheter were excluded, the difference between CT group and EAM became non significant (73% vs 55%; respectively; P = 0.16). Sub analysis of CT group showed that patients who had ablation using Smart Touch catheter tend to be more free of atrial tachyarrhythmia compared to patients who had ablation using standard irrigated catheter during

  15. Transient Ablation of Teflon Hemispheres

    NASA Technical Reports Server (NTRS)

    Arai, Norio; Karashima, Kei-ichi; Sato, Kiyoshi

    1997-01-01

    For high-speed entry of space vehicles into atmospheric environments, ablation is a practical method for alleviating severe aerodynamic heating. Several studies have been undertaken on steady or quasi-steady ablation. However, ablation is a very complicated phenomenon in which a nonequilibrium chemical process is associated with an aerodynamic process that involves changes in body shape with time. Therefore, it seems realistic to consider that ablation is an unsteady phenomenon. In the design of an ablative heat-shield system, since the ultimate purpose of the heat shield is to keep the internal temperature of the space vehicle at a safe level during entry, the transient heat conduction characteristics of the ablator may be critical in the selection of the material and its thickness. This note presents an experimental study of transient ablation of Teflon, with particular emphasis on the change in body shape, the instantaneous internal temperature distribution, and the effect of thermal expansion on ablation rate.

  16. Local Ablative Strategies for Ductal Pancreatic Cancer (Radiofrequency Ablation, Irreversible Electroporation): A Review

    PubMed Central

    Paiella, Salvatore; Salvia, Roberto; Ramera, Marco; Girelli, Roberto; Frigerio, Isabella; Giardino, Alessandro; Allegrini, Valentina; Bassi, Claudio

    2016-01-01

    Pancreatic ductal adenocarcinoma (PDAC) has still a dismal prognosis. Locally advanced pancreatic cancer (LAPC) accounts for the 40% of the new diagnoses. Current treatment options are based on chemo- and radiotherapy regimens. Local ablative techniques seem to be the future therapeutic option for stage-III patients with PDAC. Radiofrequency Ablation (RFA) and Irreversible Electroporation (IRE) are actually the most emerging local ablative techniques used on LAPC. Initial clinical studies on the use of these techniques have already demonstrated encouraging results in terms of safety and feasibility. Unfortunately, few studies on their efficacy are currently available. Even though some reports on the overall survival are encouraging, randomized studies are still required to corroborate these findings. This study provides an up-to-date overview and a thematic summary of the current available evidence on the application of RFA and IRE on PDAC, together with a comparison of the two procedures. PMID:26981115

  17. Local Ablative Strategies for Ductal Pancreatic Cancer (Radiofrequency Ablation, Irreversible Electroporation): A Review.

    PubMed

    Paiella, Salvatore; Salvia, Roberto; Ramera, Marco; Girelli, Roberto; Frigerio, Isabella; Giardino, Alessandro; Allegrini, Valentina; Bassi, Claudio

    2016-01-01

    Pancreatic ductal adenocarcinoma (PDAC) has still a dismal prognosis. Locally advanced pancreatic cancer (LAPC) accounts for the 40% of the new diagnoses. Current treatment options are based on chemo- and radiotherapy regimens. Local ablative techniques seem to be the future therapeutic option for stage-III patients with PDAC. Radiofrequency Ablation (RFA) and Irreversible Electroporation (IRE) are actually the most emerging local ablative techniques used on LAPC. Initial clinical studies on the use of these techniques have already demonstrated encouraging results in terms of safety and feasibility. Unfortunately, few studies on their efficacy are currently available. Even though some reports on the overall survival are encouraging, randomized studies are still required to corroborate these findings. This study provides an up-to-date overview and a thematic summary of the current available evidence on the application of RFA and IRE on PDAC, together with a comparison of the two procedures. PMID:26981115

  18. Advanced Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew J.

    2011-01-01

    Early NASA missions (Gemini, Apollo, Mars Viking) employed new ablative TPS that were tailored for the entry environment. After 40 years, heritage ablative TPS materials using Viking or Pathfinder era materials are at or near their performance limits and will be inadequate for future exploration missions. Significant advances in TPS materials technology are needed in order to enable any subsequent human exploration missions beyond Low Earth Orbit. This poster summarizes some recent progress at NASA in developing families of advanced rigid/conformable and flexible ablators that could potentially be used for thermal protection in planetary entry missions. In particular the effort focuses technologies required to land heavy (approx.40 metric ton) masses on Mars to facilitate future exploration plans.

  19. Shuttle subscale ablative nozzle tests

    NASA Technical Reports Server (NTRS)

    Powers, L. B.; Bailey, R. L.

    1980-01-01

    Recent subscale nozzle tests have identified new and promising carbon phenolic nozzle ablatives which utilize staple rayon, PAN, and pitch based carbon cloth. A 4-inch throat diameter submerged test nozzle designed for the 48-inch Jet Propulsion Laboratory char motor was used to evaluate five different designs incorporating 20 candidate ablatives. Test results indicate that several pitch and PAN-based carbon phenolic ablatives can provide erosion and char performance equivalent or superior to the present continuous rayon-based SRM ablative.

  20. The Effect of Catheter Ablation on Left Atrial Size and Function for Patients with Atrial Fibrillation: An Updated Meta-Analysis

    PubMed Central

    Xiong, Bin; Li, Dan; Wang, Jianling; Gyawali, Laxman; Jing, Jinjin; Su, Li

    2015-01-01

    Background Catheter ablation (CA) for atrial fibrillation (AF) is now an important therapeutic modality for patients with AF. However, data regarding changes in left atrial (LA) function after CA have indicated conflicting results depending on the AF types, follow-up period, and the analytical imaging tools. The objective of this review was to analyze the effect of CA on the LA size and function for patients with AF. Methods We searched for studies regarding LA size and function pre- and post-ablation in PubMed, Embase, the Cochrane Library, and Web of Knowledge through May 2014. LA function was measured by LA ejective fraction (LAEF), LA active ejective fraction (LAAEF), or both. Total and subgroup analyses were implemented using Cochrane Review Manager Version 5.2. Weighted mean differences with 95% confidence intervals were used to express the results of continuous outcomes using fixed or random effect models. I2 was used to calculate heterogeneity. To assess publication bias, Egger’s test and Begg’s funnel plot were performed using Stata 12.0. Results Twenty-five studies (2040 enrolled patients) were selected for this meta-analysis. The LA diameter (LAD), maximum LA volume, and minimal LA volume were significantly decreased post-ablation, as compared with those at a pre-ablation visit. Compared with the pre-ablation outcomes, we found no significant differences in LAEF/LAAEF at a post-ablation follow-up. Decreases in LA volume and LAEF remained significant post-ablation for paroxysmal AF (PAF); however, the LAEF was insignificant changes in persistent AF (PeAF). Heterogeneity was significant in spite which individual study was excluded. A publication bias was not found. In a meta-regression analysis, we did not find any factor that contributed to the heterogeneity. Conclusion With CA, LA volumes and LAD were decreased significantly in patients with AF; LAEF was not significant changes in patients with PeAF but decreased in those with PAF. PMID:26147984

  1. Comparison of Combination Therapies in the Management of Hepatocellular Carcinoma: Transarterial Chemoembolization with Radiofrequency Ablation versus Microwave Ablation

    PubMed Central

    Ginsburg, Michael; Zivin, Sean P.; Wroblewski, Kristen; Doshi, Taral; Vasnani, Raj J.; Van Ha, Thuong G.

    2015-01-01

    management after the procedure (P = 1.00). Conclusions Based on similar safety and efficacy outcomes, both combination therapies, transcatheter arterial chemoembolization plus RF ablation and transcatheter arterial chemoembolization plus MW ablation, are effective treatments for HCC. PMID:25534635

  2. Noninvasive electrocardiomapping facilitates previously failed ablation of right appendage diverticulum associated life-threatening accessory pathway.

    PubMed

    Hocini, Mélèze; Shah, Ashok J; Cochet, Hubert; Maury, Philippe; Denis, Arnaud; Haïssaguerre, Michel

    2013-05-01

    Combination of structural (CT-scan) and functional (3D electrocardiomapping) imaging methods helped successfully accomplish ablation of a life-threatening manifest accessory pathway in association with a complex right atrial anomaly after previous unsuccessful attempts of endo-epicardial ablation guided by the invasive electroanatomic system in an adolescent female. Such a system has a potential to facilitate the ablation procedure and impact its outcome through accurate localization of the arrhythmogenic substrate. PMID:23252769

  3. Image-guided focused ultrasound ablation of breast cancer: current status, challenges, and future directions

    PubMed Central

    Schmitz, A. C.; Gianfelice, D.; Daniel, B. L.; Mali, W. P. Th. M.

    2008-01-01

    Image-guided focussed ultrasound (FUS) ablation is a non-invasive procedure that has been used for treatment of benign or malignant breast tumours. Image-guidance during ablation is achieved either by using real-time ultrasound (US) or magnetic resonance imaging (MRI). The past decade phase I studies have proven MRI-guided and US-guided FUS ablation of breast cancer to be technically feasible and safe. We provide an overview of studies assessing the efficacy of FUS for breast tumour ablation as measured by percentages of complete tumour necrosis. Successful ablation ranged from 20% to 100%, depending on FUS system type, imaging technique, ablation protocol, and patient selection. Specific issues related to FUS ablation of breast cancer, such as increased treatment time for larger tumours, size of ablation margins, methods used for margin assessment and residual tumour detection after FUS ablation, and impact of FUS ablation on sentinel node procedure are presented. Finally, potential future applications of FUS for breast cancer treatment such as FUS-induced anti-tumour immune response, FUS-mediated gene transfer, and enhanced drug delivery are discussed. Currently, breast-conserving surgery remains the gold standard for breast cancer treatment. PMID:18351348

  4. 78 FR 38617 - Procedures for Establishing That an American Indian Group Exists as an Indian Tribe

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-27

    ... Bureau of Indian Affairs 25 CFR Part 83 RIN 1076-AF18 Procedures for Establishing That an American Indian....'' --Email: consultation@bia.gov . Include ``1076-AF18'' in the subject line of the message. --Mail or Hand... Interior, 1849 C Street NW., MS 4141, Washington, DC 20240. Include ``1076-AF18'' on the cover of...

  5. 60 FR 8812 - Real Estate Settlement Procedures Act (Regulation X); Escrow Accounting Procedures

    Federal Register 2010, 2011, 2012, 2013, 2014

    1995-02-15

    ... 24 CFR Part 3500 Real Estate Settlement Procedures Act (Regulation X); Escrow Accounting Procedures...-Federal Housing Commissioner 24 CFR Part 3500 RIN 2502-AF77 Real Estate Settlement Procedures Act... of the Real Estate Settlement Procedures Act. Subsequent to the publication of that rule,...

  6. Advanced Rigid Ablative TPS

    NASA Technical Reports Server (NTRS)

    Gasch, Matthew J.

    2011-01-01

    NASA Exploration Systems Mission Directorate s (ESMD) Entry, Descent, and Landing (EDL) Technology Development Project (TDP) and the NASA Aeronautics Research Mission Directorate s (ARMD) Hypersonics Project are developing new advanced rigid ablators in an effort to substantially increase reliability, decrease mass, and reduce life cycle cost of rigid aeroshell-based entry systems for multiple missions. Advanced Rigid Ablators combine ablation resistant top layers capable of high heat flux entry and enable high-speed EDL with insulating mass-efficient bottom that, insulate the structure and lower the areal weight. These materials may benefit Commercial Orbital Transportation Services (COTS) vendors and may potentially enable new NASA missions for higher velocity returns (e.g. asteroid, Mars). The materials have been thermally tested to 400-450 W/sq cm at the Laser Hardened Materials Evaluation Lab (LHMEL), Hypersonics Materials Evaluation Test System (HyMETS) and in arcjet facilities. Tested materials exhibit much lower backface temperatures and reduced recession over the baseline materials (PICA). Although the EDL project is ending in FY11, NASA in-house development of advanced ablators will continue with a focus on varying resin systems and fiber/resin interactions.

  7. Advances in local ablation of malignant liver lesions

    PubMed Central

    Eisele, Robert M

    2016-01-01

    Local ablation of liver tumors matured during the recent years and is now proven to be an effective tool in the treatment of malignant liver lesions. Advances focus on the improvement of local tumor control by technical innovations, individual selection of imaging modalities, more accurate needle placement and the free choice of access to the liver. Considering data found in the current literature for conventional local ablative treatment strategies, virtually no single technology is able to demonstrate an unequivocal superiority. Hints at better performance of microwave compared to radiofrequency ablation regarding local tumor control, duration of the procedure and potentially achievable larger size of ablation areas favour the comparably more recent treatment modality; image fusion enables more patients to undergo ultrasound guided local ablation; magnetic resonance guidance may improve primary success rates in selected patients; navigation and robotics accelerate the needle placement and reduces deviation of needle positions; laparoscopic thermoablation results in larger ablation areas and therefore hypothetically better local tumor control under acceptable complication rates, but seems to be limited to patients with no, mild or moderate adhesions following earlier surgical procedures. Apart from that, most techniques appear technically feasible, albeit demanding. Which technology will in the long run become accepted, is subject to future work. PMID:27099433

  8. Advances in local ablation of malignant liver lesions.

    PubMed

    Eisele, Robert M

    2016-04-21

    Local ablation of liver tumors matured during the recent years and is now proven to be an effective tool in the treatment of malignant liver lesions. Advances focus on the improvement of local tumor control by technical innovations, individual selection of imaging modalities, more accurate needle placement and the free choice of access to the liver. Considering data found in the current literature for conventional local ablative treatment strategies, virtually no single technology is able to demonstrate an unequivocal superiority. Hints at better performance of microwave compared to radiofrequency ablation regarding local tumor control, duration of the procedure and potentially achievable larger size of ablation areas favour the comparably more recent treatment modality; image fusion enables more patients to undergo ultrasound guided local ablation; magnetic resonance guidance may improve primary success rates in selected patients; navigation and robotics accelerate the needle placement and reduces deviation of needle positions; laparoscopic thermoablation results in larger ablation areas and therefore hypothetically better local tumor control under acceptable complication rates, but seems to be limited to patients with no, mild or moderate adhesions following earlier surgical procedures. Apart from that, most techniques appear technically feasible, albeit demanding. Which technology will in the long run become accepted, is subject to future work. PMID:27099433

  9. Fibrillation number based on wavelength and critical mass in patients who underwent radiofrequency catheter ablation for atrial fibrillation.

    PubMed

    Hwang, Minki; Park, Junbeum; Lee, Young-Seon; Park, Jae Hyung; Choi, Sung Hwan; Shim, Eun Bo; Pak, Hui-Nam

    2015-02-01

    The heart characteristic length, the inverse of conduction velocity (CV), and the inverse of the refractory period are known to determine vulnerability to cardiac fibrillation (fibrillation number, FibN) in in silico or ex vivo models. The purpose of this study was to validate the accuracy of FibN through in silico atrial modeling and to evaluate its clinical application in patients with atrial fibrillation (AF) who had undergone radiofrequency catheter ablation. We compared the maintenance duration of AF at various FibNAF values using in silico bidomain atrial modeling. Among 60 patients (72% male, 54±13 years old, 82% with paroxysmal AF) who underwent circumferential pulmonary vein isolation (CPVI) for AF rhythm control, we examined the relationship between FibN AF and postprocedural AF inducibility or induction pacing cycle length (iPCL). Clinical FibNAF was calculated using left atrium (LA) dimension (echocardiogram), the inverse of CV, and the inverse of the atrial effective refractory periods measured at proximal and distal coronary sinus. In silico simulation found a positive correlation between AF maintenance duration and FibNAF ( R = 0.90, ). After clinical CPVI, FibNAF ( 0.296±0.038 versus 0.192±0.028, ) was significantly higher in patients with postprocedural AF inducibility ( n = 41) than in those without ( n = 19 ). Among 41 patients with postprocedural AF inducibility, FibNAF ( P = 0.935, ) had excellent correlations with induction pacing cycle length. FibNAF, based on LA mass and wavelength, correlates well with AF maintenance in computational modeling and clinical AF inducibility after CPVI. PMID:25343755

  10. Percutaneous Ablation of Adrenal Tumors

    PubMed Central

    Venkatesan, Aradhana M.; Locklin, Julia; Dupuy, Damian E.; Wood, Bradford J.

    2010-01-01

    Adrenal tumors comprise a broad spectrum of benign and malignant neoplasms, and include functional adrenal adenomas, pheochromocytomas, primary adrenocortical carcinoma and adrenal metastases. Percutaneous ablative approaches that have been described and used in the treatment of adrenal tumors include percutaneous radiofrequency ablation (RFA), cryoablation, microwave ablation and chemical ablation. Local tumor ablation in the adrenal gland presents unique challenges, secondary to the adrenal gland’s unique anatomic and physiologic features. The results of clinical series employing percutaneous ablative techniques in the treatment of adrenal tumors are reviewed in this article. Clinical and technical considerations unique to ablation in the adrenal gland are presented, including approaches commonly used in our practices, and risks and potential complications are discussed. PMID:20540918

  11. New strategies for ventricular tachycardia and ventricular fibrillation ablation.

    PubMed

    Hooks, Darren A; Berte, Benjamin; Yamashita, Seigo; Mahida, Saagar; Sellal, Jean-Marc; Aljefairi, Nora; Frontera, Antonio; Derval, Nicolas; Denis, Arnaud; Hocini, Mélèze; Haïssaguerre, Michel; Jaïs, Pierre; Sacher, Frederic

    2015-03-01

    Patients with ventricular tachycardia (VT) and ventricular fibrillation (VF) and no reversible cause are difficult to treat. While implantable defibrillators prolong survival, many patients remain symptomatic due to device shocks and syncope. To address this, there have been recent advances in the catheter ablation of VT and VF. For example, non-invasive imaging has improved arrhythmia substrate characterisation, 3D catheter navigation tools have facilitated mapping of arrhythmia and substrate and ablation catheters have advanced in their ability to deliver effective lesions. However, the long-term success rates of ablation for VT and VF remain modest, with nearly half of treated patients developing recurrence within 2-3 years, and this drives the ongoing innovation in the field. This review focuses on the challenges particular to ablation of life-threatening ventricular arrhythmia, and the strategies that have been recently developed to improve procedural efficacy. Patient sub-groups that illustrate the use of new strategies are described. PMID:25666031

  12. Laser ablation in analytical chemistry-a review.

    PubMed

    Russo, Richard E; Mao, Xianglei; Liu, Haichen; Gonzalez, Jhanis; Mao, Samuel S

    2002-05-24

    Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduced risk of contamination or sample loss, analysis of very small samples not separable for solution analysis, and determination of spatial distributions of elemental composition. This review describes recent research to understand and utilize laser ablation for direct solid sampling, with emphasis on sample introduction to an inductively coupled plasma (ICP). Current research related to contemporary experimental systems, calibration and optimization, and fractionation is discussed, with a summary of applications in several areas. PMID:18968642

  13. Radiofrequency ablation for neuroendocrine liver metastases: a systematic review.

    PubMed

    Mohan, Helen; Nicholson, Patrick; Winter, Des C; O'Shea, Donal; O'Toole, Dermot; Geoghegan, Justin; Maguire, Donal; Hoti, Emir; Traynor, Oscar; Cantwell, Colin P

    2015-07-01

    To determine the efficacy of radiofrequency (RF) ablation in neuroendocrine tumor (NET) liver metastases. A systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Eight studies were included (N = 301). Twenty-six percent of RF ablation procedures were percutaneous (n = 156), with the remainder conducted at surgery. Forty-eight percent of patients had a concomitant liver resection. Fifty-four percent of patients presented with symptoms, with 92% reporting symptom improvement following RF ablation (alone or in combination with surgery). The median duration of symptom improvement was 14-27 months. However, recurrence was common (63%-87%). RF ablation can provide symptomatic relief in NET liver metastases alone or in combination with surgery. PMID:25840836

  14. Design and position control of AF lens actuator for mobile phone using IPMC-EMIM

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Joo; Kim, Chul-Jin; Park, No-Cheol; Yang, Hyun-Seok; Park, Young-Pil; Park, Kang-Ho; Lee, Hyung-Kun; Choi, Nak-Jin

    2008-03-01

    IPMC-EMIM (Ionic Polyer Metal Composites + 1-ethyl-3- methyl imidazolium trifluromethane sulfonate, EMIM-Tfo) is fabricated by substituting ionic liquid for water in Nafion film, which improves water sensitiveness of IPMC and guarantees uniform performance regardless of the surrounding environment. In this paper, we will briefly introduce the procedure of fabrication of IPMC-EMIM and proceed to introduce the Hook-type actuator using IPMC-EMIM and application to AF Lens actuator. Parameters of Hook-type actuator are estimated from experimental data. In the simulation, The proposed AF Lens Actuator is assumed to be a linear system and based on estimated parameters, PID controller will be designed and controlled motion of AF Lens actuator will be shown through simulation.

  15. Palliative Radiofrequency Ablation for Recurrent Prostate Cancer

    SciTech Connect

    Jindal, Gaurav; Friedman, Marc; Locklin, Julia Wood, Bradford J.

    2006-06-15

    Percutaneous radiofrequency ablation (RFA) is a minimally invasive local therapy for cancer. Its efficacy is now becoming well documented in many different organs, including liver, kidney, and lung. The goal of RFA is typically complete eradication of a tumor in lieu of an invasive surgical procedure. However, RFA can also play an important role in the palliative care of cancer patients. Tumors which are surgically unresectable and incompatible for complete ablation present the opportunity for RFA to be used in a new paradigm. Cancer pain runs the gamut from minor discomfort relieved with mild pain medication to unrelenting suffering for the patient, poorly controlled by conventional means. RFA is a tool which can potentially palliate intractable cancer pain. We present here a case in which RFA provided pain relief in a patient with metastatic prostate cancer with pain uncontrolled by conventional methods.

  16. Nozzle designs with pitch precursor ablatives

    NASA Technical Reports Server (NTRS)

    Blevins, H. R.; Bedard, R. J.

    1976-01-01

    Recent developments in carbon phenolic ablatives for solid rocket motor nozzles have yielded a pitch precursor carbon fiber offering significant raw material availability and cost saving advantages as compared to conventional rayon precursor material. This paper discusses the results of an experimental program conducted to assess the thermal performance and characterize the thermal properties of pitch precursor carbon phenolic ablatives. The end result of this program is the complete thermal characterization of pitch fabric, pitch mat, hybrid pitch/rayon fabric and pitch mat molding compound. With these properties determined an analytic capability now exists for predicting the thermal performance of these materials in rocket nozzle liner applications. Further planned efforts to verify material performance and analytical prediction procedures through actual rocket motor firings are also discussed.

  17. Automated microwave ablation therapy planning with single and multiple entry points

    NASA Astrophysics Data System (ADS)

    Liu, Sheena X.; Dalal, Sandeep; Kruecker, Jochen

    2012-02-01

    Microwave ablation (MWA) has become a recommended treatment modality for interventional cancer treatment. Compared with radiofrequency ablation (RFA), MWA provides more rapid and larger-volume tissue heating. It allows simultaneous ablation from different entry points and allows users to change the ablation size by controlling the power/time parameters. Ablation planning systems have been proposed in the past, mainly addressing the needs for RFA procedures. Thus a planning system addressing MWA-specific parameters and workflows is highly desirable to help physicians achieve better microwave ablation results. In this paper, we design and implement an automated MWA planning system that provides precise probe locations for complete coverage of tumor and margin. We model the thermal ablation lesion as an ellipsoidal object with three known radii varying with the duration of the ablation and the power supplied to the probe. The search for the best ablation coverage can be seen as an iterative optimization problem. The ablation centers are steered toward the location which minimizes both un-ablated tumor tissue and the collateral damage caused to the healthy tissue. We assess the performance of our algorithm using simulated lesions with known "ground truth" optimal coverage. The Mean Localization Error (MLE) between the computed ablation center in 3D and the ground truth ablation center achieves 1.75mm (Standard deviation of the mean (STD): 0.69mm). The Mean Radial Error (MRE) which is estimated by comparing the computed ablation radii with the ground truth radii reaches 0.64mm (STD: 0.43mm). These preliminary results demonstrate the accuracy and robustness of the described planning algorithm.

  18. Recent progress in radiofrequency ablation therapy for hepatocellular carcinoma.

    PubMed

    Ikeda, Kenji; Osaki, Yukio; Nakanishi, Hiroyuki; Nasu, Akihiro; Kawamura, Yusuke; Jyoko, Koji; Sano, Takatomo; Sunagozaka, Hajime; Uchino, Koji; Minami, Yasunori; Saito, Yu; Nagai, Kazumasa; Inokuchi, Ryosuke; Kokubu, Shigehiro; Kudo, Masatoshi

    2014-01-01

    In order to attain better ablation and more effective management of hepatocellular carcinoma (HCC), new approaches and devices in radiofrequency ablation (RFA) therapy were presented and discussed in a workshop at the 50th Annual Meeting of the Liver Cancer Study Group of Japan. A novel bipolar RFA apparatus was introduced in Japan in January 2013. Hundreds of subjects with HCC were treated with multipolar RFA with varied devices and plans. Among these, no-touch ablation was one of the most useful procedures in the treatment of HCC with the apparatus. In RFA therapy, a few assisting devices and techniques were applied for convenience and improvement of the thermal ablation procedure. Contrast-enhanced ultrasonography and three-dimensional fusion imaging technique using volume data of CT or MRI could improve exact targeting and shorten the treatment time for RFA procedures under ultrasonographic guidance. A more complicated method using a workstation was also reported as being helpful in planning the ablated shape and volume in multineedle RFA. The effective use of sedatives and antianalgesics as well as a novel microwave apparatus with a cooled-tip electrode was also discussed. PMID:25427736

  19. Degradation of AF1Q by chaperone-mediated autophagy

    SciTech Connect

    Li, Peng; Ji, Min; Lu, Fei; Zhang, Jingru; Li, Huanjie; Cui, Taixing; Li Wang, Xing; Tang, Dongqi; Ji, Chunyan

    2014-09-10

    AF1Q, a mixed lineage leukemia gene fusion partner, is identified as a poor prognostic biomarker for pediatric acute myeloid leukemia (AML), adult AML with normal cytogenetic and adult myelodysplastic syndrome. AF1Q is highly regulated during hematopoietic progenitor differentiation and development but its regulatory mechanism has not been defined clearly. In the present study, we used pharmacological and genetic approaches to influence chaperone-mediated autophagy (CMA) and explored the degradation mechanism of AF1Q. Pharmacological inhibitors of lysosomal degradation, such as chloroquine, increased AF1Q levels, whereas activators of CMA, including 6-aminonicotinamide and nutrient starvation, decreased AF1Q levels. AF1Q interacts with HSPA8 and LAMP-2A, which are core components of the CMA machinery. Knockdown of HSPA8 or LAMP-2A increased AF1Q protein levels, whereas overexpression showed the opposite effect. Using an amino acid deletion AF1Q mutation plasmid, we identified that AF1Q had a KFERQ-like motif which was recognized by HSPA8 for CMA-dependent proteolysis. In conclusion, we demonstrate for the first time that AF1Q can be degraded in lysosomes by CMA. - Highlights: • Chaperone-mediated autophagy (CMA) is involved in the degradation of AF1Q. • Macroautophagy does not contribute to the AF1Q degradation. • AF1Q has a KFERQ-like motif that is recognized by CMA core components.

  20. AFS Estuaries Section - A Successful Partnership

    EPA Science Inventory

    The Estuaries Section of the American Fisheries Society offers travel awards to students in support of their attendance and presentations at the AFS meeting. Since 2007, the Southern Association of Marine Laboratories has partnered with the Estuaries Section to sponsor two stude...

  1. Surgical Ablation of Atrial Fibrillation during Mitral-Valve Surgery

    PubMed Central

    Gillinov, A. Marc; Gelijns, Annetine C.; Parides, Michael K.; DeRose, Joseph J.; Moskowitz, Alan J.; Voisine, Pierre; Ailawadi, Gorav; Bouchard, Denis; Smith, Peter K.; Mack, Michael J.; Acker, Michael A.; Mullen, John C.; Rose, Eric A.; Chang, Helena L.; Puskas, John D.; Couderc, Jean-Philippe; Gardner, Timothy J.; Varghese, Robin; Horvath, Keith A.; Bolling, Steven F.; Michler, Robert E.; Geller, Nancy L.; Ascheim, Deborah D.; Miller, Marissa A.; Bagiella, Emilia; Moquete, Ellen G.; Williams, Paula; Taddei-Peters, Wendy C.; O’Gara, Patrick T.; Blackstone, Eugene H.; Argenziano, Michael

    2015-01-01

    Background Among patients undergoing mitral-valve surgery, 30 to 50% present with atrial fibrillation, which is associated with reduced survival and increased risk of stroke. Surgical ablation of atrial fibrillation has been widely adopted, but evidence regarding its safety and effectiveness is limited. Methods We randomly assigned 260 patients with persistent or long-standing persistent atrial fibrillation who required mitral-valve surgery to undergo either surgical ablation (ablation group) or no ablation (control group) during the mitral-valve operation. Patients in the ablation group underwent further randomization to pulmonary-vein isolation or a biatrial maze procedure. All patients underwent closure of the left atrial appendage. The primary end point was freedom from atrial fibrillation at both 6 months and 12 months (as assessed by means of 3-day Holter monitoring). Results More patients in the ablation group than in the control group were free from atrial fibrillation at both 6 and 12 months (63.2% vs. 29.4%, P<0.001). There was no significant difference in the rate of freedom from atrial fibrillation between patients who underwent pulmonary-vein isolation and those who underwent the biatrial maze procedure (61.0% and 66.0%, respectively; P = 0.60). One-year mortality was 6.8% in the ablation group and 8.7% in the control group (hazard ratio with ablation, 0.76; 95% confidence interval, 0.32 to 1.84; P = 0.55). Ablation was associated with more implantations of a permanent pacemaker than was no ablation (21.5 vs. 8.1 per 100 patient-years, P = 0.01). There were no significant between-group differences in major cardiac or cerebrovascular adverse events, overall serious adverse events, or hospital readmissions. Conclusions The addition of atrial fibrillation ablation to mitral-valve surgery significantly increased the rate of freedom from atrial fibrillation at 1 year among patients with persistent or long-standing persistent atrial fibrillation, but the

  2. Animal Studies of Epicardial Atrial Ablation

    PubMed Central

    Schuessler, Richard B.; Lee, Anson M.; Melby, Spencer J.; Voeller, Rochus K.; Gaynor, Sydney L.; Sakamoto, Shun-Ichiro; Damiano, Ralph J.

    2009-01-01

    The Cox-Maze procedure is an effective treatment for atrial fibrillation with a long-term freedom from recurrence of >90%. The original procedure was highly invasive and required cardiopulmonary bypass (CPB). Modifications of the procedure have been proposed so that the procedure can be done without CPB. These approaches proposed to use alternative energy sources, to replace cut and sew lesions with lines of ablation, made from the epicardium on the beating heart. This has been challenging because the atrial wall muscle thickness is extremely variable and can be covered with an epicardial layer of fat. Moreover, the circulating intracavitary blood acts as a potential heat sink, making transmural lesions difficult to obtain. In this report, we summarize the use of nine different unidirectional devices to create continuous transmural lines of ablation from the atrial epicardium in a porcine model. We define a unidirectional device as one in which all the energy is applied by a single transducer on a single heart surface. These include four radiofrequency, two microwave, two lasers, and one cryothermic device. The maximum penetration of any device was 8.3 mm. All devices except one, the Atricure IsolatorT pen, failed to penetrate 2.0 mm in some non-transmural sections. Future development of unidirectional energy sources should be directed at increasing the maximum depth and the consistency of penetration. PMID:19959142

  3. Ablation, Thermal Response, and Chemistry Program for Analysis of Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Chen, Yih-Kanq

    2010-01-01

    In previous work, the authors documented the Multicomponent Ablation Thermochemistry (MAT) and Fully Implicit Ablation and Thermal response (FIAT) programs. In this work, key features from MAT and FIAT were combined to create the new Fully Implicit Ablation, Thermal response, and Chemistry (FIATC) program. FIATC is fully compatible with FIAT (version 2.5) but has expanded capabilities to compute the multispecies surface chemistry and ablation rate as part of the surface energy balance. This new methodology eliminates B' tables, provides blown species fractions as a function of time, and enables calculations that would otherwise be impractical (e.g. 4+ dimensional tables) such as pyrolysis and ablation with kinetic rates or unequal diffusion coefficients. Equations and solution procedures are presented, then representative calculations of equilibrium and finite-rate ablation in flight and ground-test environments are discussed.

  4. Health Information in Somali (af Soomaali): MedlinePlus

    MedlinePlus

    ... af Soomaali (Somali) Bilingual PDF Health Information Translations Animal Bites Animal Bites and Scratches Qaniinyada iyo Xagashada Xayawaanka - af ... Soomaali (Somali) Bilingual PDF Health Information Translations Radiation Therapy Preventing Infections When Your White Blood Cell Count ...

  5. Health Information in Somali (af Soomaali): MedlinePlus

    MedlinePlus

    ... Bilingual PDF Health Information Translations Appendectomy for a Child Qabsin-saarid ilmo - af Soomaali (Somali) Bilingual PDF ... Somali) Bilingual PDF Health Information Translations Asthma in Children Nebulizer Treatments Daawenta wal in Xaqiiqsanaan - af Soomaali ( ...

  6. OCDR guided laser ablation device

    DOEpatents

    Dasilva, Luiz B.; Colston, Jr., Bill W.; James, Dale L.

    2002-01-01

    A guided laser ablation device. The device includes a mulitmode laser ablation fiber that is surrounded by one or more single mode optical fibers that are used to image in the vicinity of the laser ablation area to prevent tissue damage. The laser ablation device is combined with an optical coherence domain reflectometry (OCDR) unit and with a control unit which initializes the OCDR unit and a high power laser of the ablation device. Data from the OCDR unit is analyzed by the control unit and used to control the high power laser. The OCDR images up to about 3 mm ahead of the ablation surface to enable a user to see sensitive tissue such as a nerve or artery before damaging it by the laser.

  7. Multiple target laser ablation system

    DOEpatents

    Mashburn, Douglas N.

    1996-01-01

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film.

  8. Multiple target laser ablation system

    DOEpatents

    Mashburn, D.N.

    1996-01-09

    A laser ablation apparatus and method are provided in which multiple targets consisting of material to be ablated are mounted on a movable support. The material transfer rate is determined for each target material, and these rates are stored in a controller. A position detector determines which target material is in a position to be ablated, and then the controller controls the beam trigger timing and energy level to achieve a desired proportion of each constituent material in the resulting film. 3 figs.

  9. Ventricular dysfunction following direct-current shock atrioventricular junction ablation.

    PubMed

    Warren, R J; Vohra, J K; Chan, W; Lichtenstein, M; Mond, H G; Hunt, D

    1991-02-01

    Catheter-induced His bundle ablation for refractory supraventricular arrhythmias is most commonly performed with direct-current shock energy of 200-300 joules. The high energy pulse delivered by direct-current shock produces a lesion in the atrioventricular node by fulguration, with the residual energy being dissipated as a pressure wave. The effect of direct-current shock His bundle ablation on global and regional ventricular function was assessed in 14 consecutive patients by radionuclide ventriculography performed before and after ablation and again three months later. All studies were performed with ventricular pacing at 110 bpm. Global left ventricular ejection fraction was found to be significantly reduced at the three month study (0.43 +/- 0.03 vs 0.50 +/- 0.03, pre ablation, p = 0.02). A significant reduction in wall-motion score was also seen in six of the seven patients who had normal wall motion in pacing rhythm prior to ablation. Deterioration was mainly seen at the left and right ventricular apices. The observed reduction in ventricular function that follows direct-current shock His bundle ablation may result from myocardial damage from electro-coagulation or from barotrauma and supports continued investigation into alternative, less traumatic energy sources for the procedure. PMID:2036072

  10. Thermal Ablation of Lung Tissue: In Vivo Experimental Comparison of Microwave and Radiofrequency

    SciTech Connect

    Crocetti, Laura Bozzi, Elena; Faviana, Pinuccia; Cioni, Dania; Della Pina, Clotilde; Sbrana, Alberto; Fontanini, Gabriella; Lencioni, Riccardo

    2010-08-15

    This study was designed to compare feasibility, safety, and effectiveness of microwave (MW) ablation versus radiofrequency (RF) ablation of lung tissue in a rabbit model. Twenty New Zealand White rabbits were submitted to MW (n = 10, group A) or RF ablation (n = 10, group B). The procedures were performed with a prototype MW ablation device with a 1.6-cm radiating section antenna (Valleylab MW Ablation System) and with a 2-cm exposed-tip RF electrode (Cool-tip RF Ablation System). At immediate computed tomography increase in density, maximum diameters (D1-D3) of ablation zones were measured and ablation volume was calculated. Histopathologic assessment was performed 3 and 7 days after the procedure. Technical success was achieved in nine of 10 rabbits in each group. One death occurred in group B. Complications included pneumothorax (group A, n = 4; group B, n = 4), abscess (group A, n = 1; group B, n = 1), and thoracic wall burn (group A, n = 4). No significant differences were demonstrated in attenuation increase (P = 0.73), dimensions (P = 0.28, 0.86, 0.06, respectively, comparing D1-D3) and volume (P = 0.17). At histopathology, ablation zones were similar, with septal necrosis, edema, hemorrhage, and peripheral lymphocytic infiltrate. Complete thrombosis of more than 90% of vessels up to 2 mm in diameter was depicted at the periphery of the ablation zone in group A specimens. In group B specimens, complete thrombosis was depicted in 20% of vessels. Feasibility and safety of MW and RF ablation are similar in a lung rabbit model. MW ablation produces a greater damage to peripheral small vessels inducing thrombosis.

  11. Femtosecond infrared intrastromal ablation and backscattering-mode adaptive-optics multiphoton microscopy in chicken corneas

    PubMed Central

    Gualda, Emilio J.; Vázquez de Aldana, Javier R.; Martínez-García, M. Carmen; Moreno, Pablo; Hernández-Toro, Juan; Roso, Luis; Artal, Pablo; Bueno, Juan M.

    2011-01-01

    The performance of femtosecond (fs) laser intrastromal ablation was evaluated with backscattering-mode adaptive-optics multiphoton microscopy in ex vivo chicken corneas. The pulse energy of the fs source used for ablation was set to generate two different ablation patterns within the corneal stroma at a certain depth. Intrastromal patterns were imaged with a custom adaptive-optics multiphoton microscope to determine the accuracy of the procedure and verify the outcomes. This study demonstrates the potential of using fs pulses as surgical and monitoring techniques to systematically investigate intratissue ablation. Further refinement of the experimental system by combining both functions into a single fs laser system would be the basis to establish new techniques capable of monitoring corneal surgery without labeling in real-time. Since the backscattering configuration has also been optimized, future in vivo implementations would also be of interest in clinical environments involving corneal ablation procedures. PMID:22076258

  12. Optimization of the generator settings for endobiliary radiofrequency ablation

    PubMed Central

    Barret, Maximilien; Leblanc, Sarah; Vienne, Ariane; Rouquette, Alexandre; Beuvon, Frederic; Chaussade, Stanislas; Prat, Frederic

    2015-01-01

    AIM: To determine the optimal generator settings for endobiliary radiofrequency ablation. METHODS: Endobiliary radiofrequency ablation was performed in live swine on the ampulla of Vater, the common bile duct and in the hepatic parenchyma. Radiofrequency ablation time, “effect”, and power were allowed to vary. The animals were sacrificed two hours after the procedure. Histopathological assessment of the depth of the thermal lesions was performed. RESULTS: Twenty-five radiofrequency bursts were applied in three swine. In the ampulla of Vater (n = 3), necrosis of the duodenal wall was observed starting with an effect set at 8, power output set at 10 W, and a 30 s shot duration, whereas superficial mucosal damage of up to 350 μm in depth was recorded for an effect set at 8, power output set at 6 W and a 30 s shot duration. In the common bile duct (n = 4), a 1070 μm, safe and efficient ablation was obtained for an effect set at 8, a power output of 8 W, and an ablation time of 30 s. Within the hepatic parenchyma (n = 18), the depth of tissue damage varied from 1620 μm (effect = 8, power = 10 W, ablation time = 15 s) to 4480 μm (effect = 8, power = 8 W, ablation time = 90 s). CONCLUSION: The duration of the catheter application appeared to be the most important parameter influencing the depth of the thermal injury during endobiliary radiofrequency ablation. In healthy swine, the currently recommended settings of the generator may induce severe, supratherapeutic tissue damage in the biliary tree, especially in the high-risk area of the ampulla of Vater. PMID:26566429

  13. Analysis of the change in peak corneal temperature during excimer laser ablation in porcine eyes

    NASA Astrophysics Data System (ADS)

    Mosquera, Samuel Arba; Verma, Shwetabh

    2015-07-01

    The objective is to characterize the impact of different ablation parameters on the thermal load during corneal refractive surgery by means of excimer laser ablation on porcine eyes. One hundred eleven ablations were performed in 105 porcine eyes. Each ablation was recorded using infrared thermography and analyzed mainly based on the two tested local frequencies (40 Hz, clinical local frequency; 1000 Hz, no local frequency). The change in peak corneal temperature was analyzed with respect to varying ablation parameters [local frequency, system repetition rate, pulse energy, optical zone (OZ) size, and refractive correction]. Transepithelial ablations were also compared to intrastromal ablations. The average of the baseline temperature across all eyes was 20.5°C±1.1 (17.7°C to 22.2°C). Average of the change in peak corneal temperature for all clinical local frequency ablations was 5.8°C±0.8 (p=3.3E-53 to baseline), whereas the average was 9.0°C±1.5 for all no local frequency ablations (p=1.8E-35 to baseline, 1.6E-16 to clinical local frequency ablations). A logarithmic relationship was observed between the changes in peak corneal temperature with increasing local frequency. For clinical local frequency, change in peak corneal temperature was comparatively flat (r2=0.68 with a range of 1.5°C) with increasing system repetition rate and increased linearly with increasing OZ size (r2=0.95 with a range of 2.4°C). Local frequency controls help maintain safe corneal temperature increase during excimer laser ablations. Transepithelial ablations induce higher thermal load compared to intrastromal ablations, indicating a need for stronger thermal controls in transepithelial refractive procedures.

  14. Calcified lesion modeling for excimer laser ablation

    NASA Astrophysics Data System (ADS)

    Scott, Holly A.; Archuleta, Andrew; Splinter, Robert

    2009-06-01

    Objective: Develop a representative calcium target model to evaluate penetration of calcified plaque lesions during atherectomy procedures using 308 nm Excimer laser ablation. Materials and Methods: An in-vitro model representing human calcified plaque was analyzed using Plaster-of-Paris and cement based composite materials as well as a fibrinogen model. The materials were tested for mechanical consistency. The most likely candidate(s) resulting from initial mechanical and chemical screening was submitted for ablation testing. The penetration rate of specific multi-fiber catheter designs and a single fiber probe was obtained and compared to that in human cadaver calcified plaque. The effects of lasing parameters and catheter tip design on penetration speed in a representative calcified model were verified against the results in human cadaver specimens. Results: In Plaster of Paris, the best penetration was obtained using the single fiber tip configuration operating at 100 Fluence, 120 Hz. Calcified human lesions are twice as hard, twice as elastic as and much more complex than Plaster of Paris. Penetration of human calcified specimens was highly inconsistent and varied significantly from specimen to specimen and within individual specimens. Conclusions: Although Plaster of Paris demonstrated predictable increases in penetration with higher energy density and repetition rate, it can not be considered a totally representative laser ablation model for calcified lesions. This is in part due to the more heterogeneous nature and higher density composition of cadaver intravascular human calcified occlusions. Further testing will require a more representative model of human calcified lesions.

  15. Ablation and Other Local Therapy for Kidney Cancer

    MedlinePlus

    ... how the procedure is being done. Possible side effects include bleeding and damage to the kidneys or other nearby organs. Radiofrequency ablation (RFA) This technique uses high-energy radio waves to heat the tumor. A thin, needle-like probe is ...

  16. Modeling and Validation of Microwave Ablations with Internal Vaporization

    PubMed Central

    Chiang, Jason; Birla, Sohan; Bedoya, Mariajose; Jones, David; Subbiah, Jeyam; Brace, Christopher L.

    2014-01-01

    Numerical simulation is increasingly being utilized for computer-aided design of treatment devices, analysis of ablation growth, and clinical treatment planning. Simulation models to date have incorporated electromagnetic wave propagation and heat conduction, but not other relevant physics such as water vaporization and mass transfer. Such physical changes are particularly noteworthy during the intense heat generation associated with microwave heating. In this work, a numerical model was created that integrates microwave heating with water vapor generation and transport by using porous media assumptions in the tissue domain. The heating physics of the water vapor model was validated through temperature measurements taken at locations 5, 10 and 20 mm away from the heating zone of the microwave antenna in homogenized ex vivo bovine liver setup. Cross-sectional area of water vapor transport was validated through intra-procedural computed tomography (CT) during microwave ablations in homogenized ex vivo bovine liver. Iso-density contours from CT images were compared to vapor concentration contours from the numerical model at intermittent time points using the Jaccard Index. In general, there was an improving correlation in ablation size dimensions as the ablation procedure proceeded, with a Jaccard Index of 0.27, 0.49, 0.61, 0.67 and 0.69 at 1, 2, 3, 4, and 5 minutes. This study demonstrates the feasibility and validity of incorporating water vapor concentration into thermal ablation simulations and validating such models experimentally. PMID:25330481

  17. Role of endocardial septal ablation in the treatment of hypertrophic obstructive cardiomyopathy.

    PubMed

    Aksu, Tolga; Güler, Tümer Erdem; Yalın, Kıvanç; Gölcük, Şükriye Ebru; Özcan, Kazım Serhan

    2016-09-01

    Septal reduction therapy is accepted as a first therapeutic option for symptomatic drug-resistant hypertrophic obstructive cardiomyopathy (HOCM). Although, surgical septal myectomy is the gold standard method, alcohol septal ablation is a well-studied alternative approach in the patients with suitable anatomy. Endocardial septal ablation (ESA) therapy was relatively new defined modality and outcomes of the procedure were not clearly elucidated yet. We aimed to review the clinical aspects of ESA procedure and provide some historical background. PMID:27609434

  18. Microfluidic Pumps Containing Teflon [Trademark] AF Diaphragms

    NASA Technical Reports Server (NTRS)

    Willis, Peter; White, Victor; Grunthaner, Frank; Ikeda, Mike; Mathies, Richard A.

    2009-01-01

    Microfluidic pumps and valves based on pneumatically actuated diaphragms made of Teflon AF polymers are being developed for incorporation into laboratory-on-a-chip devices that must perform well over temperature ranges wider than those of prior diaphragm-based microfluidic pumps and valves. Other potential applications include implanted biomedical microfluidic devices, wherein the biocompatability of Teflon AF polymers would be highly advantageous. These pumps and valves have been demonstrated to function stably after cycling through temperatures from -125 to 120 C. These pumps and valves are intended to be successors to similar prior pumps and valves containing diaphragms made of polydimethylsiloxane (PDMS) [commonly known as silicone rubber]. The PDMS-containing valves ae designed to function stably only within the temperature range from 5 to 80 C. Undesirably, PDMS membranes are somwehat porous and retain water. PDMS is especially unsuitable for use at temperatures below 0 C because the formation of ice crystals increases porosity and introduces microshear.

  19. High temperature ablative foam

    NASA Technical Reports Server (NTRS)

    Liu, Matthew T. (Inventor)

    1992-01-01

    An ablative foam composition is formed of approximately 150 to 250 parts by weight polymeric isocyanate having an isocyanate functionality of 2.6 to 3.2; approximately 15 to 30 parts by weight reactive flame retardant having a hydroxyl number range from 200-260; approximately 10 to 40 parts by weight non-reactive flame retardant; approximately 10 to 40 parts by weight nonhydrolyzable silicone copolymer having a hydroxyl number range from 75-205; and approximately 3 to 16 parts by weight amine initiated polyether resin having an isocyanate functionality greater than or equal to 3.0 and a hydroxyl number range from 400-800.

  20. Advances in Radiofrequency Ablation of the Cerebral Cortex in Primates Using the Venous System: Improvements for Treating Epilepsy with Catheter Ablation Technology

    PubMed Central

    Henz, Benhur D.; Friedman, Paul A.; Bruce, Charles J.; Holmes, David R.; Bower, Mark; Madhavan, Malini; DeSimone, Christopher V.; Wahnschaffe, Douglas; Berhow, Steven; Danielsen, Andrew J.; Ladewig, Dorothy J.; Mikell, Susan B.; Johnson, Susan B.; Suddendorf, Scott H.; Kara, Tomas; Worrell, Gregory A.; Asirvatham, Samuel J.

    2015-01-01

    Background Pharmacology frequently fails for the treatment of epilepsy. Although surgical techniques are effective, these procedures are highly invasive. We describe feasibility and efficacy of minimally invasive mapping and ablation for the treatment of epilepsy. Methods Mapping and radiofrequency ablations were performed via the venous system in eleven baboons and three dogs. Results Mapping in deep cerebral areas was obtained in all animals. High-frequency pacing was able to induce seizure activity of local cerebral tissue in 72% of our attempts. Cerebral activity could be seen during mapping. Ablative lesions were deployed at deep brain sites without steam pops or sudden impedance rise. Histologic analysis showed necrosis at the sites of ablation in all primates. Conclusion Navigation through the cerebral venous system to map seizure activity is feasible. Radiofrequency energy can be delivered transvenously or transcortically to successful ablate cortical tissue in this animal model using this innovative approach. PMID:24836846

  1. LASER ABLATION STUDIES OF CONCRETE

    EPA Science Inventory

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-s...

  2. Efficacy of Short-Term Antiarrhythmic Drugs Use after Catheter Ablation of Atrial Fibrillation—A Systematic Review with Meta-Analyses and Trial Sequential Analyses of Randomized Controlled Trials

    PubMed Central

    Ling, Zhiyu; Xu, Yanping; Fan, Jinqi; Du, Huaan; Xiao, Peilin; Su, Li; Liu, Zengzhang; Lan, Xianbin; Zrenner, Bernhard; Yin, Yuehui

    2016-01-01

    Background The efficacy of short-term antiarrhythmic drugs (AADs) use compared with no-AADs prescription after catheter ablation of atrial fibrillation (AF) in preventing atrial arrhythmia recurrence is uncertain. Methods We searched PubMed, Embase, and the Cochrane Library through December 2015 to identify randomized controlled trials (RCTs) which evaluated the efficacy of short-term AADs use compared with no-AADs prescription after AF ablation in preventing atrial arrhythmia recurrence. The primary outcome was labeled as early atrial arrhythmia recurrence within 3 months after ablation. Secondary outcome was defined as late recurrence after 3 months of ablation. Random-effects model or fixed-effects model was used to estimate relative risks (RRs) with 95% confidence intervals (CIs). Results Six RCTs with 2,667 patients were included into this meta-analysis. Compared with no-AADs administration after AF ablation, short-term AADs use was associated with significant reduction of early atrial arrhythmia recurrence (RR, 0.68; 95% CI, 0.52–0.87; p = 0.003). Trial sequential analysis (TSA) showed that the cumulative Z-curve crossed the trial sequential monitoring boundary for benefit, establishing sufficient and conclusive evidence. However, compared with no-AADs prescription, short-term AADs use after AF ablation didn’t significantly reduce the risk of late atrial arrhythmia recurrence (RR, 0.92; 95% CI, 0.83–1.03; p = 0.15). TSA supported this result; meanwhile the estimated required information size (1,486 patients) was also met. Conclusion Short-term use of AADs after AF ablation can significantly decrease the risk of early atrial arrhythmia recurrence but not lead to corresponding reduction in risk of late atrial arrhythmia recurrence. PMID:27224469

  3. Ablation problems using a finite control volume technique

    SciTech Connect

    Blackwell, B.F.; Thornton, A.L.; Hogan, R.E.

    1993-03-01

    An element based finite control volume procedure is applied to the solution of ablation problems for 2-D axisymmetric geometries. A mesh consisting of four node quadrilateral elements was used. The nodes are allowed to move in response to the surface recession rate. The computational domain is divided into a region with a structured mesh with moving nodes and a region with an unstructured mesh with stationary nodes. The mesh is costrained to move along spines associated with the original mesh. Example problems are presented for the ablation of a realistic nose tip geometry exposed to aerodynamic heating from a uniform free stream environment.

  4. Ablation problems using a finite control volume technique

    SciTech Connect

    Blackwell, B.F.; Thornton, A.L.; Hogan, R.E.

    1993-01-01

    An element based finite control volume procedure is applied to the solution of ablation problems for 2-D axisymmetric geometries. A mesh consisting of four node quadrilateral elements was used. The nodes are allowed to move in response to the surface recession rate. The computational domain is divided into a region with a structured mesh with moving nodes and a region with an unstructured mesh with stationary nodes. The mesh is costrained to move along spines associated with the original mesh. Example problems are presented for the ablation of a realistic nose tip geometry exposed to aerodynamic heating from a uniform free stream environment.

  5. Hepatic tumor ablation with clustered microwave antennae: the US Phase II Trial

    PubMed Central

    Iannitti, David A.; Martin, Robert C.G.; Simon, Caroline J.; Hope, William W.; Newcomb, William L.; McMasters, Kelly M.; Dupuy, Damian

    2007-01-01

    Background: Thermal ablation techniques have become important treatment options for patients with unresectable hepatic malignancies. Microwave ablation (MWA) is a new thermal ablative technique that uses electromagnetic energy to produce coagulation necrosis. We report outcomes from the first clinical trial in the United States using MWA and a 915 MHz generator. Patients and methods: Patients with unresectable primary or metastatic liver cancer were enrolled in a multi-institutional trial from March 2004 through May 2006. Demographic information, diagnosis, treatment, and outcomes were documented. Results: Eighty-seven patients underwent 94 ablation procedures for 224 hepatic tumors. Forty-two ablations (45%) were performed open, 7 (7%) laparoscopically, and 45 (48%) percutaneously. The average tumor size was 3.6 cm (range 0.5–9.0 cm). Single antenna ablation volumes were 10.0 ml (range 7.8–14.0 ml), and clustered antennae ablation volumes were 50.5 ml (range 21.1–146.5 ml). Outcome variables were measured with a mean follow-up of 19 months. Local recurrence at the ablation site occurred in 6 (2.7%) tumors, and regional recurrence occurred in 37 (43%) patients. With a mean follow-up of 19 months, 41 (47%) patients were alive with no evidence of disease. There were no procedure-related deaths. The overall mortality rate was 2.3%. Conclusions: Microwave ablation is a safe and effective technology for hepatic tumor ablation. In our study, clustered antennae resulted in larger ablation volumes. Further studies with histological confirmation are needed to verify clinical results. PMID:18333126

  6. A new system of microwave ablation at 2450 MHz: preliminary experience.

    PubMed

    Ierardi, Anna Maria; Mangano, Alberto; Floridi, Chiara; Dionigi, Gianlorenzo; Biondi, Antonio; Duka, Ejona; Lucchina, Natalie; Lianos, Georgios D; Carrafiello, Gianpaolo

    2015-03-01

    The aim of this study was to assess the feasibility of the application of the new system (Emprint Microwave Ablation System, Covidien Boulder, CO, USA) and to identify its advantages. In particular the attention was focused to the spherical ablation zone obtained and its usefulness in terms of effectiveness. The new system is composed of: a 2450 MHz generator that delivers a maximum power of 100 W, a fiberglass antenna and a pump for internally cooled antenna. Ten liver nodules (8 hepatocellular carcinomas and 2 metastasis) were percutaneously treated (mean diameter 24.9 mm, range 16-35 mm). Technical success, ablation duration time, overall procedure time and safety were registered. To define the shape of the ablation zone, multiplanar reformatting (MPR) was performed. Roundness index transverse was calculated: a value near 1 represents a more spherical ablation zone shape, and a value distant from 1 implies an oval configuration. Technical success was 100%. Mean ablation time was of 3.85 min (range 3-5 min), mean overall procedure time was 30.5 min (range 25-40 min). No major complications were recorded. Roundness index transverse presented a mean value of 0.94, meaning that a spherical shape of ablation zone was achieved. One of the most promising innovations of the new microwave technology is the spherical shape of the ablation volume that could be related with an improving of the effectiveness and safety. PMID:25776064

  7. Catheter ablation of ventricular tachycardia: Lessons learned from past clinical trials and implications for future clinical trials.

    PubMed

    Pokorney, Sean D; Friedman, Daniel J; Calkins, Hugh; Callans, David J; Daoud, Emile G; Della-Bella, Paolo; Jackson, Kevin P; Shivkumar, Kalyanam; Saba, Samir; Sapp, John; Stevenson, William G; Al-Khatib, Sana M

    2016-08-01

    Catheter ablation of ventricular tachycardia (VT) has evolved in recent years, especially in patients with ischemic heart disease. Data from prospective studies show that VT catheter ablation reduces the risk of recurrent VT; however, there is a paucity of data on the effect of VT catheter ablation on mortality and patient-centered outcomes such as quality of life. Performing randomized clinical trials of VT catheter ablation can be fraught with challenges, and, as a result, several prior trials of VT catheter ablation had to be stopped prematurely. The main challenges are inability to blind the patient to therapy to obtain a traditional control group, high crossover rates between the 2 arms of the study, patient refusal to participate in trials in which they have an equal chance of receiving a "pill" vs an invasive procedure, heterogeneity of mapping and ablation techniques as well as catheters and equipment, rapid evolution of technology that may make findings of any long trial less relevant to clinical practice, lack of consensus on what constitutes acute procedural and long-term success, and presentation of patients to electrophysiologists late in the course of their disease. In this article, a panel of experts on VT catheter ablation and/or clinical trials of VT catheter ablation review challenges faced in conducting prior trials of VT catheter ablation and offer potential solutions for those challenges. It is hoped that the proposed solutions will enhance the feasibility of randomized clinical trials of VT catheter ablation. PMID:27050910

  8. Thermal response and ablation characteristics of light weight ceramic ablators

    NASA Technical Reports Server (NTRS)

    Tran, Huy K.; Rasky, Daniel J.; Esfahani, Lili

    1993-01-01

    An account is given of the thermal performance and ablation characteristics of the NASA-Ames Lightweight Ceramic Ablators (LCAs) in supersonic, high-enthalpy convective environments, which use low density ceramic or carbon fiber matrices as substrates for main structural support, with organic resin fillers. LCA densities are in the 0.224-1.282 g/cu cm range. In-depth temperature data have been obtained to determine thermal penetration depths and conductivity. The addition of SiC and PPMA is noted to significantly improve the ablation performance of LCAs with silica substrates. Carbon-based LCAs are the most mass-efficient at high flux levels.

  9. Radio frequency ablation registration, segmentation, and fusion tool.

    PubMed

    McCreedy, Evan S; Cheng, Ruida; Hemler, Paul F; Viswanathan, Anand; Wood, Bradford J; McAuliffe, Matthew J

    2006-07-01

    The radio frequency ablation segmentation tool (RFAST) is a software application developed using the National Institutes of Health's medical image processing analysis and visualization (MIPAV) API for the specific purpose of assisting physicians in the planning of radio frequency ablation (RFA) procedures. The RFAST application sequentially leads the physician through the steps necessary to register, fuse, segment, visualize, and plan the RFA treatment. Three-dimensional volume visualization of the CT dataset with segmented three dimensional (3-D) surface models enables the physician to interactively position the ablation probe to simulate burns and to semimanually simulate sphere packing in an attempt to optimize probe placement. This paper describes software systems contained in RFAST to address the needs of clinicians in planning, evaluating, and simulating RFA treatments of malignant hepatic tissue. PMID:16871716

  10. Analysis of illicit drugs by direct ablation of solid samples.

    PubMed

    Bermúdez, Celina; Cabezas, Carlos; Mata, Santiago; Berdakin, Matias; Tejedor, Jesús M; Alonso, José L

    2015-01-01

    Analysis of illicit drugs arises as an important field of work given the high social impacts presented by drugs in the modern society. Direct laser ablation of solid compounds allows their analysis without sampling or preparation procedures. For that purpose, an experimental set-up that combines laser ablation with time-of- flight mass spectrometry has been constructed very recently to perform studies on the mass spectra of such drugs as 3,4-methylenedioxy-N-methylamphetamine, commonly known as MDMA or ecstasy. Analysis of the observed fragmentation pattern in mass spectra may elucidate the ablation-induced photofragmentation phenomena produced, which differ from those previously observed with conventional ionization methods. PMID:26764307

  11. Recent Trends in Imaging for Atrial Fibrillation Ablation

    PubMed Central

    Kabra, Rajesh; Singh, Jagmeet

    2010-01-01

    Catheter ablation provides an important treatment option for patients with both paroxysmal and persistent atrial fibrillation. It mainly involves pulmonary vein isolation and additional ablations in the left atrium in persistent cases. There have been significant advancements in this procedure to enhance the safety and effectiveness. One of them is the evolution of various imaging modalities to facilitate better visualization of the complex left atrial anatomy and the pulmonary veins in order to deliver the lesions accurately. In this article, we review the electroanatomic mapping systems including the magnetic-based and impedence-based systems. Each of these mapping systems has its own advantages and disadvantages. In addition, we also discuss the role of intracardiac echocardiography and three dimensional rotational angiography in atrial fibrillation ablation. PMID:20473373

  12. Irrigated Tip Catheters for Radiofrequency Ablation in Ventricular Tachycardia

    PubMed Central

    Grothoff, Matthias; Dinov, Borislav; Kosiuk, Jedrzej; Richter, Sergio; Sommer, Philipp; Breithardt, Ole A.; Bollmann, Andreas; Arya, Arash; Hindricks, Gerhard

    2015-01-01

    Radiofrequency (RF) ablation with irrigated tip catheters decreases the likelihood of thrombus and char formation and enables the creation of larger lesions. Due to the potential dramatic consequences, the prevention of thromboembolic events is of particular importance for left-sided procedures. Although acute success rates of ventricular tachycardia (VT) ablation are satisfactory, recurrence rate is high. Apart from the progress of the underlying disease, reconduction and the lack of effective transmural lesions play a major role for VT recurrences. This paper reviews principles of lesion formation with radiofrequency and the effect of tip irrigation as well as recent advances in new technology. Potential areas of further development of catheter technology might be the improvement of mapping by better substrate definition and resolution, the introduction of bipolar and multipolar ablation techniques into clinical routine, and the use of alternative sources of energy. PMID:25705659

  13. Irrigated tip catheters for radiofrequency ablation in ventricular tachycardia.

    PubMed

    Müssigbrodt, Andreas; Grothoff, Matthias; Dinov, Borislav; Kosiuk, Jedrzej; Richter, Sergio; Sommer, Philipp; Breithardt, Ole A; Rolf, Sascha; Bollmann, Andreas; Arya, Arash; Hindricks, Gerhard

    2015-01-01

    Radiofrequency (RF) ablation with irrigated tip catheters decreases the likelihood of thrombus and char formation and enables the creation of larger lesions. Due to the potential dramatic consequences, the prevention of thromboembolic events is of particular importance for left-sided procedures. Although acute success rates of ventricular tachycardia (VT) ablation are satisfactory, recurrence rate is high. Apart from the progress of the underlying disease, reconduction and the lack of effective transmural lesions play a major role for VT recurrences. This paper reviews principles of lesion formation with radiofrequency and the effect of tip irrigation as well as recent advances in new technology. Potential areas of further development of catheter technology might be the improvement of mapping by better substrate definition and resolution, the introduction of bipolar and multipolar ablation techniques into clinical routine, and the use of alternative sources of energy. PMID:25705659

  14. Picosecond laser ablation of porcine sclera

    NASA Astrophysics Data System (ADS)

    Góra, Wojciech S.; Harvey, Eleanor M.; Dhillon, Baljean; Parson, Simon H.; Maier, Robert R. J.; Hand, Duncan P.; Shephard, Jonathan D.

    2013-03-01

    Lasers have been shown to be successful in certain medical procedures and they have been identified as potentially making a major contribution to the development of minimally invasive procedures. However, the uptake is not as widespread and there is scope for many other applications where laser devices may offer a significant advantage in comparison to the traditional surgical tools. The purpose of this research is to assess the potential of using a picosecond laser for minimally invasive laser sclerostomy. Experiments were carried out on porcine scleral samples due to the comparable properties to human tissue. Samples were prepared with a 5mm diameter trephine and were stored in lactated Ringer's solution. After laser machining, the samples were fixed in 3% glutaraldehyde, then dried and investigated under SEM. The laser used in the experiments is an industrial picosecond TRUMPF TruMicro laser operating at a wavelength of 1030nm, pulse length of 6ps, repetition rate of 1 kHz and a focused spot diameter of 30μm. The laser beam was scanned across the samples with the use of a galvanometer scan head and various ablation patterns were investigated. Processing parameters (pulse energy, spot and line separation) which allow for the most efficient laser ablation of scleral tissue without introducing any collateral damage were investigated. The potential to create various shapes, such as linear incisions, square cavities and circular cavities was demonstrated.

  15. Radiofrequency catheter ablation of accessory atrioventricular pathways in children and young adults.

    PubMed Central

    Sreeram, N; Smeets, J L; Pulles-Heintzberger, C F; Wellens, H J

    1993-01-01

    OBJECTIVE--To assess the efficacy of radiofrequency ablation for reentrant tachyarrhythmias in children and young adults. SETTING--A tertiary cardiac referral centre. PATIENTS AND INTERVENTIONS--Over a 16 month period 22 patients aged less than 20 years (median age 16.5 years) underwent 26 radiofrequency ablation procedures for atrioventricular reentry tachycardia through an accessory pathway. The results of radiofrequency ablation were compared with those in a group of 16 patients (median age 14 years) who had had surgical ablation for atrioventricular reentry tachycardia over a preceding six year period. RESULTS--Ablation of an accessory atrioventricular pathway was accomplished for 18 (76%) of 25 pathways in 16 (73%) of 22 patients. There were no procedure-related complications. Surgery was eventually curative in 15/16 patients (94%). However, three patients required a second open heart surgical procedure because tachyarrhythmia recurred. There were no surgical deaths. Failures for radiofrequency ablation were related to accessory pathway location, and were greater for right free wall and posteroseptal pathways (success rate of 50% and 57% respectively). Recurrence after surgery was also associated with pathways in these locations. CONCLUSIONS--Transcatheter radiofrequency current ablation was safe and achieved a cure with less patient morbidity and improved cost efficiency. It is an attractive alternative to long-term drug therapy or surgery in older children and adolescents. A higher success rate may be expected with increased experience. PMID:8038027

  16. Ultrasonic characterization of laser ablation

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Telschow, K. L.

    When a pulsed laser beam strikes the surface of an absorbing material, ultrasonic waves are generated due to thermoelectric expansion and, at higher laser power densities, ablation of the material. These sound generation mechanisms have been the subject of numerous theoretical and experimental studies and are now fairly well understood. In particular, it has been established that at low power densities the thermoelastic mechanism is well described by a surface center of expansion. This mechanism produces a characteristic waveform whose amplitude is proportional to the energy absorbed from the laser pulse and also dependent on the thermal and elastic properties of the material. The ablation ultrasonic source can be described by a point normal force acting on the material surface. For laser power densities near the ablation onset, the time dependence of the source is that of the laser pulse. The resultant waveform recorded on epicenter (source and detector collinear) has a sharp peak determined by the momentum impulse delivered to the material by the ablation process. Particularly in the near ablation onset region, this ultrasonic displacement peak can be used to characterize the ablation process occurring at the material surface. The onset power density for ablation and subsequent ablation dependence on power density are material dependent and thought to be a function of the heat capacity and thermal conductivity of the material. With this in mind, it is possible that these ablation signals could be used to characterize material microstructures, and perhaps material mechanical properties such as hardness, through microstructural changes of the material thermal parameters. This paper explores this question for samples of Type 304 stainless steel with microstructures controlled through work hardening and annealing.

  17. Ablative heat shield design for space shuttle

    NASA Technical Reports Server (NTRS)

    Seiferth, R. W.

    1973-01-01

    Ablator heat shield configuration optimization studies were conducted for the orbiter. Ablator and reusable surface insulation (RSI) trajectories for design studies were shaped to take advantage of the low conductance of ceramic RSI and high temperature capability of ablators. Comparative weights were established for the RSI system and for direct bond and mechanically attached ablator systems. Ablator system costs were determined for fabrication, installation and refurbishment. Cost penalties were assigned for payload weight penalties, if any. The direct bond ablator is lowest in weight and cost. A mechanically attached ablator using a magnesium subpanel is highly competitive for both weight and cost.

  18. Novel Radiofrequency Ablation Strategies for Terminating Atrial Fibrillation in the Left Atrium: A Simulation Study

    PubMed Central

    Bayer, Jason D.; Roney, Caroline H.; Pashaei, Ali; Jaïs, Pierre; Vigmond, Edward J.

    2016-01-01

    Pulmonary vein isolation (PVI) with radiofrequency ablation (RFA) is the cornerstone of atrial fibrillation (AF) therapy, but few strategies exist for when it fails. To guide RFA, phase singularity (PS) mapping locates reentrant electrical waves (rotors) that perpetuate AF. The goal of this study was to test existing and develop new RFA strategies for terminating rotors identified with PS mapping. It is unsafe to test experimental RFA strategies in patients, so they were evaluated in silico using a bilayer computer model of the human atria with persistent AF (pAF) electrical (ionic) and structural (fibrosis) remodeling. pAF was initiated by rapidly pacing the right (RSPV) and left (LSPV) superior pulmonary veins during sinus rhythm, and rotor dynamics quantified by PS analysis. Three RFA strategies were studied: (i) PVI, roof, and mitral lines; (ii) circles, perforated circles, lines, and crosses 0.5–1.5 cm in diameter/length administered near rotor locations/pathways identified by PS mapping; and (iii) 4–8 lines streamlining the sequence of electrical activation during sinus rhythm. As in pAF patients, 2 ± 1 rotors with cycle length 185 ± 4 ms and short PS duration 452 ± 401 ms perpetuated simulated pAF. Spatially, PS density had weak to moderate positive correlations with fibrosis density (RSPV: r = 0.38, p = 0.35, LSPV: r = 0.77, p = 0.02). RFA PVI, mitral, and roof lines failed to terminate pAF, but RFA perforated circles and lines 1.5 cm in diameter/length terminated meandering rotors from RSPV pacing when placed at locations with high PS density. Similarly, RFA circles, perforated circles, and crosses 1.5 cm in diameter/length terminated stationary rotors from LSPV pacing. The most effective strategy for terminating pAF was to streamline the sequence of activation during sinus rhythm with >4 RFA lines. These results demonstrate that co-localizing 1.5 cm RFA lesions with locations of high PS density is a promising strategy for terminating pAF rotors

  19. Novel Radiofrequency Ablation Strategies for Terminating Atrial Fibrillation in the Left Atrium: A Simulation Study.

    PubMed

    Bayer, Jason D; Roney, Caroline H; Pashaei, Ali; Jaïs, Pierre; Vigmond, Edward J

    2016-01-01

    Pulmonary vein isolation (PVI) with radiofrequency ablation (RFA) is the cornerstone of atrial fibrillation (AF) therapy, but few strategies exist for when it fails. To guide RFA, phase singularity (PS) mapping locates reentrant electrical waves (rotors) that perpetuate AF. The goal of this study was to test existing and develop new RFA strategies for terminating rotors identified with PS mapping. It is unsafe to test experimental RFA strategies in patients, so they were evaluated in silico using a bilayer computer model of the human atria with persistent AF (pAF) electrical (ionic) and structural (fibrosis) remodeling. pAF was initiated by rapidly pacing the right (RSPV) and left (LSPV) superior pulmonary veins during sinus rhythm, and rotor dynamics quantified by PS analysis. Three RFA strategies were studied: (i) PVI, roof, and mitral lines; (ii) circles, perforated circles, lines, and crosses 0.5-1.5 cm in diameter/length administered near rotor locations/pathways identified by PS mapping; and (iii) 4-8 lines streamlining the sequence of electrical activation during sinus rhythm. As in pAF patients, 2 ± 1 rotors with cycle length 185 ± 4 ms and short PS duration 452 ± 401 ms perpetuated simulated pAF. Spatially, PS density had weak to moderate positive correlations with fibrosis density (RSPV: r = 0.38, p = 0.35, LSPV: r = 0.77, p = 0.02). RFA PVI, mitral, and roof lines failed to terminate pAF, but RFA perforated circles and lines 1.5 cm in diameter/length terminated meandering rotors from RSPV pacing when placed at locations with high PS density. Similarly, RFA circles, perforated circles, and crosses 1.5 cm in diameter/length terminated stationary rotors from LSPV pacing. The most effective strategy for terminating pAF was to streamline the sequence of activation during sinus rhythm with >4 RFA lines. These results demonstrate that co-localizing 1.5 cm RFA lesions with locations of high PS density is a promising strategy for terminating pAF rotors. For

  20. Modeling and validation of microwave ablations with internal vaporization.

    PubMed

    Chiang, Jason; Birla, Sohan; Bedoya, Mariajose; Jones, David; Subbiah, Jeyam; Brace, Christopher L

    2015-02-01

    Numerical simulation is increasingly being utilized for computer-aided design of treatment devices, analysis of ablation growth, and clinical treatment planning. Simulation models to date have incorporated electromagnetic wave propagation and heat conduction, but not other relevant physics such as water vaporization and mass transfer. Such physical changes are particularly noteworthy during the intense heat generation associated with microwave heating. In this paper, a numerical model was created that integrates microwave heating with water vapor generation and transport by using porous media assumptions in the tissue domain. The heating physics of the water vapor model was validated through temperature measurements taken at locations 5, 10, and 20 mm away from the heating zone of the microwave antenna in homogenized ex vivo bovine liver setup. Cross-sectional area of water vapor transport was validated through intraprocedural computed tomography (CT) during microwave ablations in homogenized ex vivo bovine liver. Iso-density contours from CT images were compared to vapor concentration contours from the numerical model at intermittent time points using the Jaccard index. In general, there was an improving correlation in ablation size dimensions as the ablation procedure proceeded, with a Jaccard index of 0.27, 0.49, 0.61, 0.67, and 0.69 at 1, 2, 3, 4, and 5 min, respectively. This study demonstrates the feasibility and validity of incorporating water vapor concentration into thermal ablation simulations and validating such models experimentally. PMID:25330481

  1. Surgical Ablation of Atrial Fibrillation Using Energy Sources

    PubMed Central

    Brick, Alexandre Visconti; Braile, Domingo Marcolino

    2015-01-01

    Surgical ablation, concomitant with other operations, is an option for treatment in patients with chronic atrial fibrillation. The aim of this study is to present a literature review on surgical ablation of atrial fibrillation in patients undergoing cardiac surgery, considering energy sources and return to sinus rhythm. A comprehensive survey was performed in the literature on surgical ablation of atrial fibrillation considering energy sources, sample size, study type, outcome (early and late), and return to sinus rhythm. Analyzing studies with immediate results (n=5), the percentage of return to sinus rhythm ranged from 73% to 96%, while those with long-term results (n=20) (from 12 months on) ranged from 62% to 97.7%. In both of them, there was subsequent clinical improvement of patients who underwent ablation, regardless of the energy source used. Surgical ablation of atrial fibrillation is essential for the treatment of this arrhythmia. With current technology, it may be minimally invasive, making it mandatory to perform a procedure in an attempt to revert to sinus rhythm in patients requiring heart surgery. PMID:26934404

  2. Pulmonary vein isolation using new technologies to improve ablation lesion formation: Initial results comparing enhanced catheter tip irrigation (Surround Flow®) with contact force measurement (Smarttouch®)

    PubMed Central

    Fichtner, Stephanie; Reents, Tilko; Ammar, Sonia; Semmler, Verena; Kathan, Susanne; Dillier, Roger; Buiatti, Alexandra; Hessling, Gabriele; Deisenhofer, Isabel

    2015-01-01

    Introduction Pulmonary vein reconnection after pulmonary vein isolation (PVI) is a significant problem in the treatment of paroxysmal atrial fibrillation (AF). We report about patients who underwent contact force (CF) guided PVI using CF catheter and compared them to patients with PVI using an ablation catheter with enhanced tip irrigation. Methods A total of 59 patients were included in the analysis. In 30 patients circumferential PVI was performed using the Thermocool Smarttouch® ablation catheter (ST) whereas in 29 patients circumferential PVI using the Thermocool Surround Flow SF® ablation catheter (SF) was performed. Patients were compared in regard to procedure time, fluoroscopy time/dose as well as RF-application duration and completeness of PVI. Adverse events (pericardial effusion, PV stenosis, stroke, death) were evaluated. The presence of sinus rhythm off antiarrhythmic medication was assessed during 6 months follow-up using multiple 7 day Holter-ECGs. Results In both groups, all PVs were isolated without serious adverse events. Procedure time was 2.15 ± 0.5 h (ST) vs. 2.37 ± 1.13 h (SF) (p = 0.19). Duration of RF-applications was 46.6 ± 18 min (ST) and 49.8 ± 19 min (SF) (p = 0.52). Fluoroscopy time was 25.2 ± 13 min (ST) vs. 29 ± 18 min (SF), fluoroscopy dose 2675.6 ± 1658 versus 3038.3 ± 1997 cGym2 (p = 0.36 and 0.46 respectively). Sinus rhythm off antiarrhythmic medication validated with 7 day Holter ECGs was present in both groups in 72% of patients after 6 months of follow up. Conclusion PVI using the new contact force catheter is safe and effective in patients with paroxysmal AF. PMID:26937108

  3. Ion acceleration enhanced by target ablation

    SciTech Connect

    Zhao, S.; Lin, C. Wang, H. Y.; Lu, H. Y.; He, X. T.; Yan, X. Q.; Chen, J. E.; Cowan, T. E.

    2015-07-15

    Laser proton acceleration can be enhanced by using target ablation, due to the energetic electrons generated in the ablation preplasma. When the ablation pulse matches main pulse, the enhancement gets optimized because the electrons' energy density is highest. A scaling law between the ablation pulse and main pulse is confirmed by the simulation, showing that for given CPA pulse and target, proton energy improvement can be achieved several times by adjusting the target ablation.

  4. TPS Ablator Technologies for Interplanetary Spacecraft

    NASA Technical Reports Server (NTRS)

    Curry, Donald M.

    2004-01-01

    This slide presentation reviews the status of Thermal Protection System (TPS) Ablator technologies and the preparation for use in interplanetary spacecraft. NASA does not have adequate TPS ablatives and sufficient selection for planned missions. It includes a comparison of shuttle and interplanetary TPS requirements, the status of mainline TPS charring ablator materials, a summary of JSC SBIR accomplishments in developing advanced charring ablators and the benefits of SBIR Ablator/fabrication technology.

  5. Three-dimension finite-element analyses of multiple electrodes bipolar RF global endometrial ablation

    NASA Astrophysics Data System (ADS)

    Hu, Tao; Panhao, Tang; Xiao, Jiahua

    2015-03-01

    Radio-frequency ablation (RFA) is a minimally invasive surgical procedure to thermally ablate the targeted diseased tissue. There have been many finite-element method (FEM) studies of cardiac and hepatic RFA, but hardly find any FEM study on endometrial ablation for abnormal uterine bleeding. In this paper, a FEM model was generated to analyze the temperature distribution of bipolar RF global endometrial ablation with three pairs of bipolar electrodes placed at the perimeter of the uterine cavity. COMSOL was utilized to calculate the RF electric fields and temperature fields by numerically solving the bioheat equation in the triangle uterine cavity range. The 55°C isothermal surfaces show the shape of the ablation dimensions (depth and width), which reasonably matched the experimental results.

  6. Chemical nonequilibrium Navier-Stokes solutions for hypersonic flow over an ablating graphite nosetip

    NASA Technical Reports Server (NTRS)

    Chen, Y. K.; Henline, W. D.

    1993-01-01

    The general boundary conditions including mass and energy balances of chemically equilibrated or nonequilibrated gas adjacent to ablating surfaces have been derived. A computer procedure based on these conditions was developed and interfaced with the Navier-Stokes solver for predictions of the flow field, surface temperature, and surface ablation rates over re-entry space vehicles with ablating Thermal Protection Systems (TPS). The Navier-Stokes solver with general surface thermochemistry boundary conditions can predict more realistic solutions and provide useful information for the design of TPS. A test case with a proposed hypersonic test vehicle configuration and associated free stream conditions was developed. Solutions with various surface boundary conditions were obtained, and the effect of nonequilibrium gas as well as surface chemistry on surface heating and ablation rate were examined. The solutions of the GASP code with complete ablating surface conditions were compared with those of the ASC code. The direction of future work is also discussed.

  7. Conformal needle-based ultrasound ablation using EM-tracked conebeam CT image guidance

    NASA Astrophysics Data System (ADS)

    Burdette, E. Clif; Banovac, Filip; Diederich, Chris J.; Cheng, Patrick; Wilson, Emmanuel; Cleary, Kevin R.

    2011-03-01

    Numerous studies have demonstrated the efficacy of interstitial ablative approaches for the treatment of renal and hepatic tumors. Despite these promising results, current systems remain highly dependent on operator skill, and cannot treat many tumors because there is little control of the size and shape of the zone of necrosis, and no control over ablator trajectory within tissue once insertion has taken place. Additionally, tissue deformation and target motion make it extremely difficult to accurately place the ablator device into the target. Irregularly shaped target volumes typically require multiple insertions and several sequential thermal ablation procedures. This study demonstrated feasibility of spatially tracked image-guided conformal ultrasound (US) ablation for percutaneous directional ablation of diseased tissue. Tissue was prepared by suturing the liver within a pig belly and 1mm BBs placed to serve as needle targets. The image guided system used integrated electromagnetic tracking and cone-beam CT (CBCT) with conformable needlebased high-intensity US ablation in the interventional suite. Tomographic images from cone beam CT were transferred electronically to the image-guided tracking system (IGSTK). Paired-point registration was used to register the target specimen to CT images and enable navigation. Path planning is done by selecting the target BB on the GUI of the realtime tracking system and determining skin entry location until an optimal path is selected. Power was applied to create the desired ablation extent within 7-10 minutes at a thermal dose (>300eqm43). The system was successfully used to place the US ablator in planned target locations within ex-vivo kidney and liver through percutaneous access. Targeting accuracy was 3-4 mm. Sectioned specimens demonstrated uniform ablation within the planned target zone. Subsequent experiments were conducted for multiple ablator positions based upon treatment planning simulations. Ablation zones in

  8. Optical properties measurement of the laser-ablated tissues for the combined laser ablation with photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Honda, Norihiro; Ishii, Katsunori; Awazu, Kunio

    2012-03-01

    Laser ablation therapy combined with photodynamic therapy (PDT) is studied for treatment of advanced cancers. The clinical outcome of PDT may be improved by the accurate knowledge about the light distribution within tissue. Optical properties [absorption coefficient (μa), scattering coefficient (μs), anisotropy factor (g), refractive index, etc.] of tissues help us realizing a light propagation through the tissue. It is important to understand of the effect of laser coagulation formed by laser ablation to PDT. The aim of this study is to estimate of influence of coagulated region to PDT for effective PDT combined laser ablation therapy. We evaluated the optical property of mouse tumor tissue in native and coagulated state using a double integrating sphere system and an inverse Monte Carlo method in the wavelength range from 350 to 1000 nm. After laser ablation, the μa and reduced scattering coefficient spectra of coagulated tissues were increased in the wavelength range from 350 to 1000 nm. The optical penetration depth of coagulated tissues is 1.2-2.9 times lower than the native state in the wavelength range from 350 to 1000 nm. The intensity of the light energy inside the coagulated tissue falls to about 60% of its original value at the end of coagulated layer. The evaluation of light energy distribution by the determination of the tissues optical properties could be useful for optimization of the treatment procedure in combined laser ablation with PDT.

  9. Direct Pressure Monitoring Accurately Predicts Pulmonary Vein Occlusion During Cryoballoon Ablation

    PubMed Central

    Kosmidou, Ioanna; Wooden, Shannnon; Jones, Brian; Deering, Thomas; Wickliffe, Andrew; Dan, Dan

    2013-01-01

    Cryoballoon ablation (CBA) is an established therapy for atrial fibrillation (AF). Pulmonary vein (PV) occlusion is essential for achieving antral contact and PV isolation and is typically assessed by contrast injection. We present a novel method of direct pressure monitoring for assessment of PV occlusion. Transcatheter pressure is monitored during balloon advancement to the PV antrum. Pressure is recorded via a single pressure transducer connected to the inner lumen of the cryoballoon. Pressure curve characteristics are used to assess occlusion in conjunction with fluoroscopic or intracardiac echocardiography (ICE) guidance. PV occlusion is confirmed when loss of typical left atrial (LA) pressure waveform is observed with recordings of PA pressure characteristics (no A wave and rapid V wave upstroke). Complete pulmonary vein occlusion as assessed with this technique has been confirmed with concurrent contrast utilization during the initial testing of the technique and has been shown to be highly accurate and readily reproducible. We evaluated the efficacy of this novel technique in 35 patients. A total of 128 veins were assessed for occlusion with the cryoballoon utilizing the pressure monitoring technique; occlusive pressure was demonstrated in 113 veins with resultant successful pulmonary vein isolation in 111 veins (98.2%). Occlusion was confirmed with subsequent contrast injection during the initial ten procedures, after which contrast utilization was rapidly reduced or eliminated given the highly accurate identification of occlusive pressure waveform with limited initial training. Verification of PV occlusive pressure during CBA is a novel approach to assessing effective PV occlusion and it accurately predicts electrical isolation. Utilization of this method results in significant decrease in fluoroscopy time and volume of contrast. PMID:23485956

  10. Direct pressure monitoring accurately predicts pulmonary vein occlusion during cryoballoon ablation.

    PubMed

    Kosmidou, Ioanna; Wooden, Shannnon; Jones, Brian; Deering, Thomas; Wickliffe, Andrew; Dan, Dan

    2013-01-01

    Cryoballoon ablation (CBA) is an established therapy for atrial fibrillation (AF). Pulmonary vein (PV) occlusion is essential for achieving antral contact and PV isolation and is typically assessed by contrast injection. We present a novel method of direct pressure monitoring for assessment of PV occlusion. Transcatheter pressure is monitored during balloon advancement to the PV antrum. Pressure is recorded via a single pressure transducer connected to the inner lumen of the cryoballoon. Pressure curve characteristics are used to assess occlusion in conjunction with fluoroscopic or intracardiac echocardiography (ICE) guidance. PV occlusion is confirmed when loss of typical left atrial (LA) pressure waveform is observed with recordings of PA pressure characteristics (no A wave and rapid V wave upstroke). Complete pulmonary vein occlusion as assessed with this technique has been confirmed with concurrent contrast utilization during the initial testing of the technique and has been shown to be highly accurate and readily reproducible. We evaluated the efficacy of this novel technique in 35 patients. A total of 128 veins were assessed for occlusion with the cryoballoon utilizing the pressure monitoring technique; occlusive pressure was demonstrated in 113 veins with resultant successful pulmonary vein isolation in 111 veins (98.2%). Occlusion was confirmed with subsequent contrast injection during the initial ten procedures, after which contrast utilization was rapidly reduced or eliminated given the highly accurate identification of occlusive pressure waveform with limited initial training. Verification of PV occlusive pressure during CBA is a novel approach to assessing effective PV occlusion and it accurately predicts electrical isolation. Utilization of this method results in significant decrease in fluoroscopy time and volume of contrast. PMID:23485956

  11. Laser ablation in analytical chemistry.

    PubMed

    Russo, Richard E; Mao, Xianglei; Gonzalez, Jhanis J; Zorba, Vassilia; Yoo, Jong

    2013-07-01

    In 2002, we wrote an Analytical Chemistry feature article describing the Physics of Laser Ablation in Microchemical Analysis. In line with the theme of the 2002 article, this manuscript discusses current issues in fundamental research, applications based on detecting photons at the ablation site (LIBS and LAMIS) and by collecting particles for excitation in a secondary source (ICP), and directions for the technology. PMID:23614661

  12. Percutaneous microwave ablation vs radiofrequency ablation in the treatment of hepatocellular carcinoma

    PubMed Central

    Poulou, Loukia S; Botsa, Evanthia; Thanou, Ioanna; Ziakas, Panayiotis D; Thanos, Loukas

    2015-01-01

    Hepatocellular cancer ranks fifth among cancers and is related to chronic viral hepatitis, alcohol abuse, steatohepatitis and liver autoimmunity. Surgical resection and orthotopic liver transplantation have curative potential, but fewer than 20% of patients are suitable candidates. Interventional treatments are offered to the vast majority of patients. Radiofrequency (RFA) and microwave ablation (MWA) are among the therapeutic modalities, with similar indications which include the presence of up to three lesions, smaller than 3 cm in size, and the absence of extrahepatic disease. The therapeutic effect of both methods relies on thermal injury, but MWA uses an electromagnetic field as opposed to electrical current used in RFA. Unlike MWA, the effect of RFA is partially limited by the heat-sink effect and increased impedance of the ablated tissue. Compared with RFA, MWA attains a more predictable ablation zone, permits simultaneous treatment of multiple lesions, and achieves larger coagulation volumes in a shorter procedural time. Major complications of both methods are comparable and infrequent (approximately 2%-3%), and they include haemorrhage, infection/abscess, visceral organ injury, liver failure, and pneumothorax. RFA may incur the additional complication of skin burns. Nevertheless, there is no compelling evidence for differences in clinical outcomes, including local recurrence rates and survival. PMID:26052394

  13. Percutaneous microwave ablation vs radiofrequency ablation in the treatment of hepatocellular carcinoma.

    PubMed

    Poulou, Loukia S; Botsa, Evanthia; Thanou, Ioanna; Ziakas, Panayiotis D; Thanos, Loukas

    2015-05-18

    Hepatocellular cancer ranks fifth among cancers and is related to chronic viral hepatitis, alcohol abuse, steatohepatitis and liver autoimmunity. Surgical resection and orthotopic liver transplantation have curative potential, but fewer than 20% of patients are suitable candidates. Interventional treatments are offered to the vast majority of patients. Radiofrequency (RFA) and microwave ablation (MWA) are among the therapeutic modalities, with similar indications which include the presence of up to three lesions, smaller than 3 cm in size, and the absence of extrahepatic disease. The therapeutic effect of both methods relies on thermal injury, but MWA uses an electromagnetic field as opposed to electrical current used in RFA. Unlike MWA, the effect of RFA is partially limited by the heat-sink effect and increased impedance of the ablated tissue. Compared with RFA, MWA attains a more predictable ablation zone, permits simultaneous treatment of multiple lesions, and achieves larger coagulation volumes in a shorter procedural time. Major complications of both methods are comparable and infrequent (approximately 2%-3%), and they include haemorrhage, infection/abscess, visceral organ injury, liver failure, and pneumothorax. RFA may incur the additional complication of skin burns. Nevertheless, there is no compelling evidence for differences in clinical outcomes, including local recurrence rates and survival. PMID:26052394

  14. Dynamics of tissue shrinkage during ablative temperature exposures

    PubMed Central

    Rossmann, Christian; Garrett-Mayer, Elizabeth; Rattay, Frank; Haemmerich, Dieter

    2014-01-01

    There is a lack of studies that examine dynamics of heat-induced shrinkage of organ tissues. Clinical procedures such as radiofrequency ablation, microwave ablation or high-intensity focused ultrasound, use heat to treat diseases such as cancer and cardiac arrhythmia. When heat is applied to tissues, shrinkage occurs due to protein denaturation, dehydration, and contraction of collagen at temperatures greater 50ºC. This is particularly relevant for image-guided procedures such as tumor ablation, where pre- and post-treatment images are compared and any changes in dimensions must be considered to avoid misinterpretations of the treatment outcome. We present data from ex vivo, isothermal shrinkage tests in porcine liver tissue, where axial changes in tissue length were recorded during 15 minutes of heating to temperatures between 60 and 95ºC. A mathematical model was developed to accurately describe the time and temperature-dependent shrinkage behavior. Shrinkage dynamics had same characteristics independent of temperature; the estimated relative shrinkage, adjusted for time since death, after 15 min heating to temperatures of 60, 65, 75, 85 and 95ºC, was 12.3, 13.8, 16.6, 19.2, and 21.7%, respectively. Our results demonstrate shrinkage dynamics of organ tissues, and suggest the importance of considering tissue shrinkage for thermal ablative treatments. PMID:24345880

  15. Detached tip of a transseptal sheath during left atrial ablation.

    PubMed

    El-Damaty, Ahmed; Love, Michael; Parkash, Ratika

    2012-02-15

    Left atrial ablation has become more commonplace with the advent of catheter ablation for atrial fibrillation. A number of transseptal sheaths have been produced to enhance safe and efficient catheter manipulation in the left atrium (LA) for these procedures. Some of the sheaths have been subject to recall due to partial or complete detachment of its radiopaque tip. We report a case of a 46 year-old female diagnosed with idiopathic dilated cardiomyopathy that presented with atypical left atrial flutter. During electrophysiologic study, a Swartz braided SL1 (SL-1) transseptal sheath was used to introduce the ablation catheter to the left atrium. During left atrial mapping, the radiopaque tip of the sheath detached from the rest of the sheath and was seen floating in the LA. After exchanging the SL-1 sheath with a deflectable sheath, the detached segment was retrieved out of the LA and eventually out of the vascular system using an angioplasty balloon advanced over a wire and inflated distal to the lumen of the detached tip. The root cause of this malfunction was found to be lack of a secondary bonding process that these sheaths generally undergo during the manufacturing process. We describe the case of a left atrial ablation procedure where a novel percutaneous method was able to successfully retrieve the detached tip of a transseptal sheath from the vascular system, thereby avoiding a potential catastrophic complication or thoracotomy. This method may be useful in other cases where similar circumstances may present. PMID:22162088

  16. Denervation as a Common Mechanism Underlying Different Pulmonary Vein Isolation Strategies for Paroxysmal Atrial Fibrillation: Evidenced by Heart Rate Variability after Ablation

    PubMed Central

    Wang, Kejing; Chang, Dong; Chu, Zhenliang; Yang, Yanzong; Gao, Lianjun; Zhang, Shulong; Xia, Yunlong; Dong, Yingxue; Yin, Xiaomeng; Cong, Peixin; Jia, Jingjing

    2013-01-01

    Backgrounds. Segmental and circumferential pulmonary vein isolations (SPVI and CPVI) have been demonstrated to be effective therapies for paroxysmal atrial fibrillation (PAF). PVI is well established as the endpoint of different ablation techniques, whereas it may not completely account for the long-term success. Methods. 181 drug-refractory symptomatic PAF patients were referred for segmental or circumferential PVI (SPVI = 67; CPVI = 114). Heart rate variability (HRV) was assessed before and after the final ablation. Results. After following up for 62.23 ± 12.75 months, patients underwent 1.41 ± 0.68 procedures in average, and the success rates in SPVI and CPVI groups were comparable. 119 patients were free from AF recurrence (SPVI-S, n = 43; CPVI-S, n = 76). 56 patients had recurrent episodes (SPVI-R, n = 21; CPVI-R, n = 35). Either ablation technique decreased HRV significantly. Postablation SDNN and rMSSD were significantly lower in SPVI-S and CPVI-S subgroups than in SPVI-R and CPVI-R subgroups (SPVI-S versus SPVI-R: SDNN 91.8 ± 32.6 versus 111.5 ± 36.2 ms, rMSSD 47.4 ± 32.3 versus 55.2 ± 35.2 ms; CPVI-S versus CPVI-R: SDNN 83.0 ± 35.6 versus 101.0 ± 40.7 ms, rMSSD 41.1 ± 22.9 versus 59.2 ± 44.8 ms; all P < 0.05). Attenuation of SDNN and rMSSD remained for 12 months in SPVI-S and CPVI-S subgroups, whereas it recovered earlier in SPVI-R and CPVI-R subgroups. Multivariate logistic regression analysis identified SDNN as the only predictor of long-term success. Conclusions. Beyond PVI, denervation may be a common mechanism underlying different ablation strategies for PAF. PMID:24058286

  17. Multiple-antenna microwave ablation: analysis of non-parallel antenna implants

    NASA Astrophysics Data System (ADS)

    Mukherjee, Souvick; Curto, Sergio; Albin, Nathan; Natarajan, Bala; Prakash, Punit

    2015-03-01

    Microwave ablation is a minimally invasive modality increasingly being used for thermal treatment of cancer in various organs. During ablation procedures, treatment planning is typically restricted to vendor specifications of expected ablation zone volumes based on experiments in unperfused ex vivo tissues, presuming parallel insertion of antennas. However, parallel antenna implants are not always clinically possible due to the restricted control of flexible antennas and presence of intervening organs. This paper aims to quantify the effect of non-parallel antenna implants on the ablation volume. 3D electromagnetic-bioheat transfer models were implemented to analyze ablation zone profiles created by dual antenna arrays. Parallel and non-parallel implants spaced 10-25 mm with antenna tips deviated to create converging or diverging configurations were analyzed. Volumetric Dice Similarity Coefficients (DSC) were calculated to compare ablation zone volumes for parallel and non-parallel configuration. Antenna tip displacements of 3 mm/antenna yielded an average DSC of 0.78. Tip displacements of 5 mm/antenna yielded a DSC of 0.78 and 0.64 for 15 mm and 20 mm antenna spacing, respectively. For ablation with dipole antennas as the frequency of operation decreases from 2.45 GHz to 915 MHz the similarity between the ablation zones for parallel and angled cases increased significantly. In conclusion, ablation volumes with non-parallel antenna implants may differ significantly from the parallel configuration. Patient-specific treatment planning tools may provide more accurate predictions of 3D-ablation volumes based on imaging data of actual implanted antenna configurations. Methods to compare ablation zone volumes incorporating uncertainty in antenna positions and experimental results to validate the numerical modelling are also presented.

  18. Science to practice: what do molecular biologic studies in rodent models add to our understanding of interventional oncologic procedures including percutaneous ablation by using glyceraldehyde-3-phosphate dehydrogenase antagonists?

    PubMed

    Goldberg, S Nahum

    2012-03-01

    In this basic research study, Ganapathy-Kanniappan et al advance our understanding of how to block the glycolytic pathway to inhibit tumor progression by using image guided procedures (1). This was accomplished by demonstrating their ability to perform molecular targeting of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in human hepatocellular carcinoma (HCC) by using percutaneous injection of either inhibitor--3-bromopyruvate (3-BrPA) or short hairpin RNA (shRNA). They take the critical step of providing further rationale for potentially advancing this therapy into clinical trials by demonstrating that GAPDH expression strongly correlates with c-jun, a proto-oncogene involved in liver tumorigenesis in human HCC (2). PMID:22357877

  19. 77 FR 12452 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-01

    .... FOR FURTHER INFORMATION CONTACT: Richard A. Dunham III, Flight Procedure Standards Branch (AFS-420... ``significant rule '' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26,1979) ; and (3... Kalb Taylor Muni, ILS OR LOC RWY 2, Orig-B De Kalb, IL, De Kalb Taylor Muni, NDB RWY 27,...

  20. Survival after Radiofrequency Ablation in 122 Patients with Inoperable Colorectal Lung Metastases

    SciTech Connect

    Gillams, Alice; Khan, Zahid; Osborn, Peter; Lees, William

    2013-06-15

    Purpose. To analyze the factors associated with favorable survival in patients with inoperable colorectal lung metastases treated with percutaneous image-guided radiofrequency ablation. Methods. Between 2002 and 2011, a total of 398 metastases were ablated in 122 patients (87 male, median age 68 years, range 29-90 years) at 256 procedures. Percutaneous CT-guided cool-tip radiofrequency ablation was performed under sedation/general anesthesia. Maximum tumor size, number of tumors ablated, number of procedures, concurrent/prior liver ablation, previous liver or lung resection, systemic chemotherapy, disease-free interval from primary resection to lung metastasis, and survival from first ablation were recorded prospectively. Kaplan-Meier analysis was performed, and factors were compared by log rank test. Results. The initial number of metastases ablated was 2.3 (range 1-8); the total number was 3.3 (range 1-15). The maximum tumor diameter was 1.7 (range 0.5-4) cm, and the number of procedures was 2 (range 1-10). The major complication rate was 3.9 %. Overall median and 3-year survival rate were 41 months and 57 %. Survival was better in patients with smaller tumors-a median of 51 months, with 3-year survival of 64 % for tumors 2 cm or smaller versus 31 months and 44 % for tumors 2.1-4 cm (p = 0.08). The number of metastases ablated and whether the tumors were unilateral or bilateral did not affect survival. The presence of treated liver metastases, systemic chemotherapy, or prior lung resection did not affect survival. Conclusion. Three-year survival of 57 % in patients with inoperable colorectal lung metastases is better than would be expected with chemotherapy alone. Patients with inoperable but small-volume colorectal lung metastases should be referred for ablation.

  1. Experimental Evaluation of the Heat Sink Effect in Hepatic Microwave Ablation

    PubMed Central

    Ringe, Kristina I.; Lutat, Carolin; Rieder, Christian; Schenk, Andrea; Wacker, Frank; Raatschen, Hans-Juergen

    2015-01-01

    Purpose To demonstrate and quantify the heat sink effect in hepatic microwave ablation (MWA) in a standardized ex vivo model, and to analyze the influence of vessel distance and blood flow on lesion volume and shape. Materials and Methods 108 ex vivo MWA procedures were performed in freshly harvested pig livers. Antennas were inserted parallel to non-perfused and perfused (700,1400 ml/min) glass tubes (diameter 5mm) at different distances (10, 15, 20mm). Ablation zones (radius, area) were analyzed and compared (Kruskal-Wallis Test, Dunn’s multiple comparison Test). Temperature changes adjacent to the tubes were measured throughout the ablation cycle. Results Maximum temperature decreased significantly with increasing flow and distance (p<0.05). Compared to non-perfused tubes, ablation zones were significantly deformed by perfused tubes within 15mm distance to the antenna (p<0.05). At a flow rate of 700ml/min ablation zone radius was reduced to 37.2% and 80.1% at 10 and 15mm tube distance, respectively; ablation zone area was reduced to 50.5% and 89.7%, respectively. Conclusion Significant changes of ablation zones were demonstrated in a pig liver model. Considerable heat sink effect was observed within a diameter of 15mm around simulated vessels, dependent on flow rate. This has to be taken into account when ablating liver lesions close to vessels. PMID:26222431

  2. Fundamental Mechanisms of Pulsed Laser Ablation of Biological Tissue

    NASA Astrophysics Data System (ADS)

    Albagli, Douglas

    The ability to cut and remove biological tissue with short pulsed laser light, a process called laser ablation, has the potential to revolutionize many surgical procedures. Ablation procedures using short pulsed lasers are currently being developed or used in many fields of medicine, including cardiology, ophthalmology, dermatology, dentistry, orthopedics, and urology. Despite this, the underlying physics of the ablation process is not well understood. In fact, there is wide disagreement over whether the fundamental mechanism is primarily photothermal, photomechanical, or photochemical. In this thesis, both experimental and theoretical techniques are developed to explore this issue. The photothermal model postulates that ablation proceeds through vaporization of the target material. The photomechanical model asserts that ablation is initiated when the laser-induced tensile stress exceeds the ultimate tensile strength of the target. I have developed a three dimensional model of the thermoelastic response of tissue to short pulsed laser irradiation which allows the time dependent stress distribution to be calculated given the optical, thermal and mechanical properties of the target. A complimentary experimental technique has been developed to verify this model, measure the needed physical properties of the tissue, and record the thermoelastic response of the tissue at the onset of ablation. The results of this work have been widely disseminated to the international research community and have led to significant findings which support the photomechanical model of ablation of tissue. First, the energy deposited in tissue is an order of magnitude less than that required for vaporization. Second, unlike the one-dimensional thermoelastic model of laser-induced stress generation that has appeared in the literature, the full three-dimensional model predicts the development of significant tensile stresses on the surface of the target, precisely where ablation is observed to

  3. AF4 and AF4N protein complexes: recruitment of P-TEFb kinase, their interactome and potential functions

    PubMed Central

    Scholz, Bastian; Kowarz, Eric; Rössler, Tanja; Ahmad, Khalil; Steinhilber, Dieter; Marschalek, Rolf

    2015-01-01

    AF4/AFF1 and AF5/AFF4 are the molecular backbone to assemble “super-elongation complexes” (SECs) that have two main functions: (1) control of transcriptional elongation by recruiting the positive transcription elongation factor b (P-TEFb = CyclinT1/CDK9) that is usually stored in inhibitory 7SK RNPs; (2) binding of different histone methyltransferases, like DOT1L, NSD1 and CARM1. This way, transcribed genes obtain specific histone signatures (e.g. H3K79me2/3, H3K36me2) to generate a transcriptional memory system. Here we addressed several questions: how is P-TEFb recruited into SEC, how is the AF4 interactome composed, and what is the function of the naturally occuring AF4N protein variant which exhibits only the first 360 amino acids of the AF4 full-length protein. Noteworthy, shorter protein variants are a specific feature of all AFF protein family members. Here, we demonstrate that full-length AF4 and AF4N are both catalyzing the transition of P-TEFb from 7SK RNP to their N-terminal domain. We have also mapped the protein-protein interaction network within both complexes. In addition, we have first evidence that the AF4N protein also recruits TFIIH and the tumor suppressor MEN1. This indicate that AF4N may have additional functions in transcriptional initiation and in MEN1-dependend transcriptional processes. PMID:26171280

  4. Should radiofrequency current ablation be performed in asymptomatic patients with the Wolff-Parkinson-White syndrome?

    PubMed

    Steinbeck, G

    1993-03-01

    The exiting new method of ablation of accessory pathways using radiofrequency current applied by catheters will dramatically change our therapeutic decisions in these patients in the near future. This brief survey reviews the existing literature about the risk of the disease as well as of the procedure of catheter ablation. From these data, the risk of sudden death appears to be extremely low in asymptomatic Wolff-Parkinson-White (WPW) individuals. Side effects of catheter ablation may result from the invasive procedure as well as from radiation exposure (the latter to the patient as well as to operating physicians). While the complication rate in experienced centers is extremely low, a multicenter registry of the success and complication rate is urgently needed in view of the many centers starting with catheter ablation. Based on a subjective benefit-to-risk analysis, asymptomatic WPW individuals should be offered catheter ablation only under special circumstances (high risk profession, athletes, family history of sudden death). On the other hand, catheter ablation need not be and should not be considered generally in asymptomatic individuals with WPW pattern. Finally, this author cannot imagine that the energy, time, and money spent for mass screening and eventual catheter ablation of asymptomatic WPW individuals with its attending risks can be outweighed by the potential benefits for these asymptomatic individuals. PMID:7681970

  5. The ablation threshold of Er;Cr:YSGG laser radiation in bone tissue

    NASA Astrophysics Data System (ADS)

    Benetti, Carolina; Zezell, Denise Maria

    2015-06-01

    In laser cut clinical applications, the use of energy densities lower than the ablation threshold causes increase of temperature of the irradiated tissue, which might result in an irreversible thermal damage. Hence, knowing the ablation threshold is crucial for insuring the safety of these procedures. The aim of this study was to determine the ablation threshold of the Er,Cr:YSGG laser in bone tissue. Bone pieces from jaws of New Zealand rabbits were cut as blocks of 5 mm × 8 mm and polished with sandpaper. The Er,Cr:YSGG laser used in this study had wavelength of 2780 nm, 20 Hz of frequency, and the irradiation condition was chosen so as to simulate the irradiation during a surgical procedure. The laser irradiation was performed with 12 different values of laser energy densities, between 3 J/cm2 and 42 J/cm2, during 3 seconds, resulting in the overlap of 60 pulses. This process was repeated in each sample, for all laser energy densities. After irradiation, the samples were analyzed by scanning electron microscope (SEM), and it was measured the crater diameter for each energy density. By fitting a curve that related the ablation threshold with the energy density and the corresponding diameter of ablation crater, it was possible to determine the ablation threshold. The results showed that the ablation threshold of the Er,Cr:YSGG in bone tissue was 1.95+/-0.42 J/cm2.

  6. Atrial rhythm influences catheter tissue contact during radiofrequency catheter ablation of atrial fibrillation: comparison of contact force between sinus rhythm and atrial fibrillation.

    PubMed

    Matsuda, Hisao; Parwani, Abdul Shokor; Attanasio, Philipp; Huemer, Martin; Wutzler, Alexander; Blaschke, Florian; Haverkamp, Wilhelm; Boldt, Leif-Hendrik

    2016-09-01

    Catheter tissue contact force (CF) is an important factor for durable lesion formation during radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). Since CF varies in the beating heart, atrial rhythm during RFCA may influence CF. A high-density map and RFCA points were obtained in 25 patients undergoing RFCA of AF using a CF-sensing catheter (Tacticath, St. Jude Medical). The operators were blinded to the CF information. Contact type was classified into three categories: constant, variable, and intermittent contact. Average CF and contact type were analyzed according to atrial rhythm (SR vs. AF) and anatomical location. A total of 1364 points (891 points during SR and 473 points during AF) were analyzed. Average CFs showed no significant difference between SR (17.2 ± 11.3 g) and AF (17.2 ± 13.3 g; p = 0.99). The distribution of points with an average CF of ≥20 and <10 g also showed no significant difference. However, the distribution of excessive CF (CF ≥40 g) was significantly higher during AF (7.4 %) in comparison with SR (4.2 %; p < 0.05). At the anterior area of the right inferior pulmonary vein (RIPV), the average CF during AF was significantly higher than during SR (p < 0.05). Constant contact was significantly higher during AF (32.2 %) when compared to SR (9.9 %; p < 0.01). Although the average CF was not different between atrial rhythms, constant contact was more often achievable during AF than it was during SR. However, excessive CF also seems to occur more frequently during AF especially at the anterior part of RIPV. PMID:26498938

  7. Practice guidelines for ultrasound-guided percutaneous microwave ablation for hepatic malignancy

    PubMed Central

    Liang, Ping; Yu, Jie; Lu, Ming-De; Dong, Bao-Wei; Yu, Xiao-Ling; Zhou, Xiao-Dong; Hu, Bing; Xie, Ming-Xing; Cheng, Wen; He, Wen; Jia, Jian-Wen; Lu, Guo-Rong

    2013-01-01

    Primary liver cancer and liver metastases are among the most frequent malignancies worldwide, with an increasing number of new cases and deaths every year. Traditional surgery is only suitable for a limited proportion of patients and imaging-guided percutaneous thermal ablation has achieved optimistic results for management of hepatic malignancy. This synopsis outlines the first clinical practice guidelines for ultrasound-guided percutaneous microwave ablation therapy for hepatic malignancy, which was created by a joint task force of the Society of Chinese Interventional Ultrasound. The guidelines aim at standardizing the microwave ablation procedure and therapeutic efficacy assessment, as well as proposing the criteria for the treatment candidates. PMID:24023485

  8. The role of catheter ablation in the management of atrial fibrillation.

    PubMed

    Ang, Richard; Earley, Mark J

    2016-06-01

    Atrial fibrillation is driven by spontaneous electrical activation emerging from the pulmonary veins. Catheter ablation using either radiofrequency or cryothermal energy electrically isolates these veins from the left atrium, both reducing the burden of atrial fibrillation episodes and improving the patient's symptoms. Catheter ablation is superior to antiarryhthmic drugs when patients are carefully selected. Underlying medical problems - including obesity, hypertension and obstructive sleep apnoea - should be optimally treated before considering ablation. Although this treatment has the potential to cure patients of their symptoms, they should be aware of the important associated procedural complications. PMID:27251918

  9. Laser fiber migration into the pelvic cavity: A rare complication of endovenous laser ablation.

    PubMed

    Lun, Yu; Shen, Shikai; Wu, Xiaoyu; Jiang, Han; Xin, Shijie; Zhang, Jian

    2015-10-01

    Endovenous laser ablation is an established alternative to surgery with stripping for the treatment of varicose veins. Ecchymoses and pain are frequently reported side effects of endovenous laser ablation. Device-related complications are rare but serious. We describe here an exceptional complication, necessitating an additional surgical procedure to remove a segment of laser fiber that had migrated into the pelvic cavity. Fortunately, severe damage had not occurred. This case highlights the importance of checking the completeness of the guidewire, catheter, and laser fiber after endovenous laser ablation. PMID:24965101

  10. Radiofrequency Ablation to Prevent Sudden Cardiac Death

    PubMed Central

    Atoui, Moustapha; Gunda, Sampath; Lakkireddy, Dhanunjaya; Mahapatra, Srijoy

    2015-01-01

    Radiofrequency ablation may prevent or treat atrial and ventricular arrhythmias. Since some of these arrhythmias are associated with sudden cardiac death, it has been hypothesized that ablation may prevent sudden death in certain cases. We performed a literature search to better understand under which circumstances ablation may prevent sudden death and found little randomized data demonstrating the long-term effects of ablation. Current literature shows that ablation clearly prevents symptoms of arrhythmia and may reduce the incidence of sudden cardiac death in select patients, although data does not indicate improved mortality. Ongoing clinical trials are needed to better define the role of ablation in preventing sudden cardiac death. PMID:26306130

  11. Radiofrequency ablation without the use of fluoroscopy – in what kind of patients is it feasible?

    PubMed Central

    Gawrysiak, Marcin; Piątkowska, Agnieszka; Lodziński, Piotr; Kiliszek, Marek; Małkowska, Sylwia; Zaczek, Rajmund; Piątkowski, Radosław; Opolski, Grzegorz; Kozłowski, Dariusz

    2013-01-01

    Introduction The aim of the study was to describe the experience in performing ablation without fluoroscopy. Material and methods From 575 ablation procedures with CARTO performed in the period 2003–2008, 108 (42 M; age 40 ±16 years) were done without fluoroscopy. One patient had ablation using the Localisa system. There was one man with thrombocytopenia and two pregnant women. Results Right ventricular (RV) outflow tract arrhythmias and other RV arrhythmias were noted in 38 patients (35%) and 17 patients (15%), respectively. There were 5 (4.6%) left ventricular (LV) outflow tract arrhythmias and 19 (17.5%) other LV tachycardias; right accessory pathways in 17 patients (20%), in the middle cardiac vein in 1, Mahaim fibres in 1, and 3 cases of permanent junctional reciprocating tachycardias. One patient with CRT had AV node ablation (Localisa). In 3 patients there were also other arrhythmias treated: slow AV nodal pathway, typical flutter isthmus and right atrial tachycardia. In 2004, 1/96 CARTO procedures was done without fluoroscopy, in 2006 2/97, in 2007 19 (2 in LV) of 93, in 2008 87 (22 in LV) of 204. The percentage of ablations without fluoroscopy in every hundred CARTO procedures was: 1%, 1%, 8%, 23%, 46%, 28% (mean 18%). There were no procedure-related complications. Conclusions It is feasible to perform ablations within both right and left sides of the heart without fluoroscopy. The number and type of non-fluoroscopic procedures depends on the operator's experience. Pregnant patients, with malignant history or with hematologic diseases should be ablated without fluoroscopy in centres that specialise in these kinds of procedures. PMID:24273563

  12. HIFU Tissue Ablation: Concept and Devices.

    PubMed

    Ter Haar, Gail

    2016-01-01

    High intensity focused ultrasound (HIFU) is rapidly gaining clinical acceptance as a technique capable of providing non-invasive heating and ablation for a wide range of applications. Usually requiring only a single session, treatments are often conducted as day case procedures, with the patient either fully conscious, lightly sedated or under light general anesthesia. HIFU scores over other thermal ablation techniques because of the lack of necessity for the transcutaneous insertion of probes into the target tissue. Sources placed either outside the body (for treatment of tumors or abnormalities of the liver, kidney, breast, uterus, pancreas brain and bone), or in the rectum (for treatment of the prostate), provide rapid heating of a target tissue volume, the highly focused nature of the field leaving tissue in the ultrasound propagation path relatively unaffected. Numerous extra-corporeal, transrectal and interstitial devices have been designed to optimize application-specific treatment delivery for the wide-ranging areas of application that are now being explored with HIFU. Their principle of operation is described here, and an overview of their design principles is given. PMID:26486329

  13. Radiofrequency ablation of intrahepatic cholangiocarcinoma: preliminary experience.

    PubMed

    Carrafiello, Gianpaolo; Laganà, Domenico; Cotta, Elisa; Mangini, Monica; Fontana, Federico; Bandiera, Francesca; Fugazzola, Carlo

    2010-08-01

    The purpose of this study was to evaluate the safety and efficacy of percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) in patients with intrahepatic cholangiocarcinoma (ICCA) in a small, nonrandomized series. From February 2004 to July 2008, six patients (four men and two women; mean age 69.8 years [range 48 to 83]) with ICCA underwent percutaneous US-guided RFA. Preintervetional transarterial embolization was performed in two cases to decrease heat dispersion during RFA in order to increase the area of ablation. The efficacy of RFA was evaluated using contrast-enhanced dynamic computed tomography (CT) 1 month after treatment and then every 3 months thereafter. Nine RFA sessions were performed for six solid hepatic tumors in six patients. The duration of follow-up ranged from 13 to 21 months (mean 17.5). Posttreatment CT showed total necrosis in four of six tumors after one or two RFA sessions. Residual tumor was observed in two patients with larger tumors (5 and 5.8 cm in diameter). All patients tolerated the procedure, and there with no major complications. Only 1 patient developed post-RFA syndrome (pain, fever, malaise, and leukocytosis), which resolved with oral administration of acetaminophen. Percutaneous RFA is a safe and effective treatment for patients with hepatic tumors: It is ideally suited for those who are not eligible for surgery. Long-term follow-up data regarding local and systemic recurrence and survival are still needed. PMID:20411389

  14. Low cost fabrication of ablative heat shields

    NASA Technical Reports Server (NTRS)

    Cecka, A. M.; Schofield, W. C.

    1972-01-01

    A material and process study was performed using subscale panels in an attempt to reduce the cost of fabricating ablative heat shield panels. Although no improvements were made in the material formulation, a significant improvement was obtained in the processing methods compared to those employed in the previous work. The principal feature of the new method is the press filling and curing of the ablation material in a single step with the bonding and curing of the face sheet. This method was chosen to replace the hand troweling and autoclave curing procedure used previously. Double-curvature panels of the same size as the flat panels were fabricated to investigate fabrication problems. It was determined that the same materials and processes used for flat panels can be used to produce the curved panels. A design with severe curvatures consisting of radii of 24 x 48 inches was employed for evaluation. Ten low-density and ten high-density panels were fabricated. With the exception of difficulties related to short run non-optimum tooling, excellent panel filling and density uniformity were obtained.

  15. Radiofrequency Ablation of Intrahepatic Cholangiocarcinoma: Preliminary Experience

    SciTech Connect

    Carrafiello, Gianpaolo Lagana, Domenico; Cotta, Elisa; Mangini, Monica; Fontana, Federico; Bandiera, Francesca; Fugazzola, Carlo

    2010-08-15

    The purpose of this study was to evaluate the safety and efficacy of percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) in patients with intrahepatic cholangiocarcinoma (ICCA) in a small, nonrandomized series. From February 2004 to July 2008, six patients (four men and two women; mean age 69.8 years [range 48 to 83]) with ICCA underwent percutaneous US-guided RFA. Preintervetional transarterial embolization was performed in two cases to decrease heat dispersion during RFA in order to increase the area of ablation. The efficacy of RFA was evaluated using contrast-enhanced dynamic computed tomography (CT) 1 month after treatment and then every 3 months thereafter. Nine RFA sessions were performed for six solid hepatic tumors in six patients. The duration of follow-up ranged from 13 to 21 months (mean 17.5). Posttreatment CT showed total necrosis in four of six tumors after one or two RFA sessions. Residual tumor was observed in two patients with larger tumors (5 and 5.8 cm in diameter). All patients tolerated the procedure, and there with no major complications. Only 1 patient developed post-RFA syndrome (pain, fever, malaise, and leukocytosis), which resolved with oral administration of acetaminophen. Percutaneous RFA is a safe and effective treatment for patients with hepatic tumors: It is ideally suited for those who are not eligible for surgery. Long-term follow-up data regarding local and systemic recurrence and survival are still needed.

  16. [A comparative study between surgical section and radiofrequency ablation of the anomalous pathways in the WPW syndrome].

    PubMed

    Iturralde, P; Colín, L; Kershenovich, S; Saucedo, J; de Micheli, A; Barragán, R; Martínez Rios, M A; González Hermosillo, J A

    1993-01-01

    Radiofrequency catheter ablation is an effective alternative to medical therapy to patient with Wolff Parkinson White syndrome (WPW). The purpose of this study is to compare our results in 70 patients with WPW that underwent either surgery or ablation procedure with radiofrequency energy. Of this number of patients the surgical procedure was successful in 82%; complications were present in 15% and mortality in 8%. Average hospitalization was 6 to 10 days and cost from 2 to 10 thousand of new pesos. On the other hand, of 44 patients that underwent radiofrequency ablation, in 80% the procedure was finally successful with recurrence of 9% and no mortality. The hospitalization period was one day, the cost run from 500 to 2 thousand of new pesos in our institution. These results demonstrate the efficacy of the radiofrequency energy ablation in the treatment of WPW. This procedure is safe and less expensive than surgery. PMID:8466362

  17. 7 CFR Exhibits A-F to Subpart A... - [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 14 2013-01-01 2013-01-01 false A Exhibits A-F to Subpart A of Part 1955 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL BUSINESS-COOPERATIVE... Real and Chattel Property Exhibits A-F to Subpart A of Part 1955...

  18. 7 CFR Exhibits A-F to Subpart A... - [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 14 2012-01-01 2012-01-01 false A Exhibits A-F to Subpart A of Part 1955 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL BUSINESS-COOPERATIVE... Real and Chattel Property Exhibits A-F to Subpart A of Part 1955...

  19. 7 CFR Exhibits A-F to Subpart A... - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 14 2010-01-01 2009-01-01 true A Exhibits A-F to Subpart A of Part 1955 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL BUSINESS-COOPERATIVE... Real and Chattel Property Exhibits A-F to Subpart A of Part 1955...

  20. 7 CFR Exhibits A-F to Subpart A... - [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 14 2011-01-01 2011-01-01 false A Exhibits A-F to Subpart A of Part 1955 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL BUSINESS-COOPERATIVE... Real and Chattel Property Exhibits A-F to Subpart A of Part 1955...

  1. 7 CFR Exhibits A-F to Subpart A... - [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 14 2014-01-01 2014-01-01 false A Exhibits A-F to Subpart A of Part 1955 Agriculture Regulations of the Department of Agriculture (Continued) RURAL HOUSING SERVICE, RURAL BUSINESS-COOPERATIVE... Real and Chattel Property Exhibits A-F to Subpart A of Part 1955...

  2. Part III: AFS - A Secure Distributed File System

    SciTech Connect

    Wachsmann, A.; /SLAC

    2005-06-29

    AFS is a secure distributed global file system providing location independence, scalability and transparent migration capabilities for data. AFS works across a multitude of Unix and non-Unix operating systems and is used at many large sites in production for many years. AFS still provides unique features that are not available with other distributed file systems even though AFS is almost 20 years old. This age might make it less appealing to some but with IBM making AFS available as open-source in 2000, new interest in use and development was sparked. When talking about AFS, people often mention other file systems as potential alternatives. Coda (http://www.coda.cs.cmu.edu/) with its disconnected mode will always be a research project and never have production quality. Intermezzo (http://www.inter-mezzo.org/) is now in the Linux kernel but not available for any other operating systems. NFSv4 (http://www.nfsv4.org/) which picked up many ideas from AFS and Coda is not mature enough yet to be used in serious production mode. This article presents the rich features of AFS and invites readers to play with it.

  3. The effect of elastic modulus on ablation catheter contact area

    NASA Astrophysics Data System (ADS)

    Camp, Jon J.; Linte, Cristian A.; Rettmann, Maryam E.; Sun, Deyu; Packer, Douglas L.; Robb, Richard A.; Holmes, David R.

    2015-03-01

    Cardiac ablation consists of navigating a catheter into the heart and delivering RF energy to electrically isolate tissue regions that generate or propagate arrhythmia. Besides the challenges of accurate and precise targeting of the arrhythmic sites within the beating heart, limited information is currently available to the cardiologist regarding intricate electrodetissue contact, which directly impacts the quality of produced lesions. Recent advances in ablation catheter design provide intra-procedural estimates of tissue-catheter contact force, but the most direct indicator of lesion quality for any particular energy level and duration is the tissue-catheter contact area, and that is a function of not only force, but catheter pose and material elasticity as well. In this experiment, we have employed real-time ultrasound (US) imaging to determine the complete interaction between the ablation electrode and tissue to accurately estimate contact, which will help to better understand the effect of catheter pose and position relative to the tissue. By simultaneously recording tracked position, force reading and US image of the ablation catheter, the differing material properties of polyvinyl alcohol cryogel[1] phantoms are shown to produce varying amounts of tissue depression and contact area (implying varying lesion quality) for equivalent force readings. We have shown that the elastic modulus significantly affects the surface-contact area between the catheter and tissue at any level of contact force. Thus we provide evidence that a prescribed level of catheter force may not always provide sufficient contact area to produce an effective ablation lesion in the prescribed ablation time.

  4. Analysis of a novel expanded tip wire (ETW) antenna for microwave ablation of cardiac arrhythmias.

    PubMed

    Chiu, Heng-Mao; Mohan, Ananda Sanagavarapu; Weily, Andrew R; Guy, Duncan J R; Ross, David L

    2003-07-01

    A novel expanded tip wire (ETW) catheter antenna is proposed for microwave ablation for the treatment of atrial fibrillation (AF). The antenna is designed as an integral part of coaxial cable so that it can be inserted via a 6F catheter. A numerical model based on the rotationally symmetric finite-difference time-domain technique incorporating the generalized perfectly matched layer as the absorbing boundary condition has been utilized to accurately model the interaction between the antenna and the myocardium. Numerical and in-vitro experimental results are presented for specific absorption rate, return loss and heating pattern produced by the antenna. Both numerical modeling and in-vitro experimentation show that the proposed ETW antenna produces a well-defined electric field distribution that provides continuous long and linear lesions for the treatment of AF. PMID:12848357

  5. Percutaneous thermal ablation: how to protect the surrounding organs.

    PubMed

    Tsoumakidou, Georgia; Buy, Xavier; Garnon, Julien; Enescu, Julian; Gangi, Afshin

    2011-09-01

    A variety of thermal ablation techniques have been advocated for percutaneous tumor management. Although the above techniques are considered safe, they can be complicated with unintended thermal injury to the surrounding structures, with disastrous results. In the present article we report a number of different insulation techniques (hydrodissection, gas dissection and balloon interposition, warming/cooling systems) that can be applied. Emphasis is given to the procedure-related details, and we present the advantages and drawbacks of the insulation techniques. We also provide tips on avoiding painful skin burns when treating superficial lesions. Finally, we point out the interest of temperature monitoring and how it can be achieved (use of thermocouples, fiberoptic thermosensors, or direct magnetic resonance imaging temperature mapping). The above thermal insulation and temperature monitoring techniques can be applied alone or in combination. Familiarity with these techniques is essential to avoid major complications and to increase the indications of thermal ablation procedures. PMID:21767784

  6. Laparoscopic Ultrasound-Guided Radiofrequency Ablation of Uterine Fibroids

    SciTech Connect

    Milic, Andrea; Asch, Murray R. Hawrylyshyn, Peter A.; Allen, Lisa M.; Colgan, Terence J.; Kachura, John R.; Hayeems, Eran B.

    2006-08-15

    Four patients with symptomatic uterine fibroids measuring less than 6 cm underwent laparoscopic ultrasound-guided radiofrequency ablation (RFA) using multiprobe-array electrodes. Follow-up of the treated fibroids was performed with gadolinium-enhanced magnetic resonance imaging (MRI) and patients' symptoms were assessed by telephone interviews. The procedure was initially technically successful in 3 of the 4 patients and MRI studies at 1 month demonstrated complete fibroid ablation. Symptom improvement, including a decrease in menstrual bleeding and pain, was achieved in 2 patients at 3 months. At 7 months, 1 of these 2 patients experienced symptom worsening which correlated with recurrent fibroid on MRI. The third, initially technically successfully treated patient did not experience any symptom relief after the procedure and was ultimately diagnosed with adenomyosis. Our preliminary results suggest that RFA is a technically feasible treatment for symptomatic uterine fibroids in appropriately selected patients.

  7. Sequential Hybrid Procedure for Persistent Atrial Fibrillation

    PubMed Central

    Bulava, Alan; Mokracek, Ales; Hanis, Jiri; Kurfirst, Vojtech; Eisenberger, Martin; Pesl, Ladislav

    2015-01-01

    Background Catheter ablation of persistent atrial fibrillation yields an unsatisfactorily high number of failures. The hybrid approach has recently emerged as a technique that overcomes the limitations of both surgical and catheter procedures alone. Methods and Results We investigated the sequential (staged) hybrid method, which consists of a surgical thoracoscopic radiofrequency ablation procedure followed by radiofrequency catheter ablation 6 to 8 weeks later using the CARTO 3 mapping system. Fifty consecutive patients (mean age 62±7 years, 32 males) with long‐standing persistent atrial fibrillation (41±34 months) and a dilated left atrium (>45 mm) were included and prospectively followed in an unblinded registry. During the electrophysiological part of the study, all 4 pulmonary veins were found to be isolated in 36 (72%) patients and a complete box‐lesion was confirmed in 14 (28%) patients. All gaps were successfully re‐ablated. Twelve months after the completed hybrid ablation, 47 patients (94%) were in normal sinus rhythm (4 patients with paroxysmal atrial fibrillation required propafenone and 1 patient underwent a redo catheter procedure). The majority of arrhythmias recurred during the first 3 months. Beyond 12 months, there were no arrhythmia recurrences detected. The surgical part of the procedure was complicated by 7 (13.7%) major complications, while no serious adverse events were recorded during the radiofrequency catheter part of the procedure. Conclusions The staged hybrid epicardial–endocardial treatment of long‐standing persistent atrial fibrillation seems to be extremely effective in maintenance of normal sinus rhythm compared to radiofrequency catheter or surgical ablation alone. Epicardial ablation alone cannot guarantee durable transmural lesions. Clinical Trial Registration URL: www.ablace.cz Unique identifier: cz‐060520121617 PMID:25809548

  8. Periprocedural anticoagulation of patients undergoing pericardiocentesis for cardiac tamponade complicating catheter ablation of atrial fibrillation.

    PubMed

    Lin, Tao; Bai, Rong; Chen, Ying-wei; Yu, Rong-hui; Tang, Ri-bo; Sang, Cai-hua; Li, Song-nan; Ma, Chang-sheng; Dong, Jian-zeng

    2015-01-01

    Anticoagulation of patients with cardiac tamponade (CT) complicating catheter ablation of atrial fibrillation (AF) is an ongoing problem. The aim of this study was to survey the clinical practice of periprocedural anticoagulation in such patients. This study analyzed the periprocedural anticoagulation of 17 patients with CT complicating AF ablation. Emergent pericardiocentesis was performed once CT was confirmed. The mean drained volume was 410.0 ± 194.1 mL. Protamine sulfate was administered to neutralize heparin (1 mg neutralizes 100 units heparin) in 11 patients with persistent pericardial bleeding and vitamin K1 (10 mg) was given to reverse warfarin in 3 patients with supratherapeutic INR (INR > 2.1). Drainage catheters were removed 12 hours after echocardiography confirmed absence of intrapericardial bleeding and anticoagulation therapy was restored 12 hours after removing the catheter. Fifteen patients took oral warfarin and 10 of them were given subcutaneous injection of LMWH (1 mg/kg, twice daily) as a bridge to resumption of systemic anticoagulation with warfarin. Two patients with a small amount of persistent pericardial effusion were given LMWH on days 5 and 13, and warfarin on days 6 and 24. The dosage of warfarin was adjusted to keep the INR within 2-3 in all patients. After 12 months of follow-up, all patients had no neurological events and no occurrence of delayed CT. The results showed that it was effective and safe to resume anticoagulation therapy 12 hours after removal of the drainage catheter. This may help to prevent thromboembolic events following catheter ablation of AF. PMID:25503659

  9. Toward a petabyte-scale AFS service at CERN

    NASA Astrophysics Data System (ADS)

    van der Ster, Daniel; Moscicki, Jakub T.; Wiebalck, Arne

    2014-06-01

    AFS is a mature and reliable storage service at CERN, having worked for more than 20 years as the provider of Unix home directories and project areas. Recently, the AFS service has grown at unprecedented rates (200% in the past year); this growth was unlocked thanks to innovations in both the hardware and software components of our file servers. This work presents how AFS is used at CERN and how the service offering is evolving with the increasing storage needs of its local and remote user communities. In particular, we demonstrate the usage patterns for home directories, workspaces and project spaces, as well as show the daily work which is required to rebalance data and maintaining stability and performance. Finally, we highlight some recent changes and optimisations made to the AFS Service, thereby revealing how AFS can possibly operate at all while being subjected to frequent-almost DDOS-like-attacks from its users.

  10. Thermal response and ablation characteristics of lightweight ceramic ablators

    SciTech Connect

    Tran, H.K.; Rasky, D.J.; Esfahani, L.

    1994-11-01

    This paper presents the thermal performance and ablation characteristics of the newly developed lightweight ceramic ablators (LCAs) in a supersonic, high-enthalpy convective environment. Lightweight ceramic ablators were recently conceived and developed at NASA Ames using low-density ceramic or carbon fibrous matrices as substrates for main structural support and organic resins as fillers. These LCAs were successfully produced with densities ranging from approximately 0.224 to 1.282 g/cu cm. Several infiltrants with different char yields were used to study the effect on surface recession. Tests were conducted in the NASA Ames arc-jet facilities. Material thermal performance was evaluated at cold-wall heat fluxes from 113.5 to 1634 W/sq cm, and stagnation pressures of 0.018 to 0.331 atm. Conventional ablators such as SLA-561, Avcoat 5026-39HC, MA-25S, and balsa wood were tested at the same heat fluxes for direct comparison. Surface temperature was measured using optical pyrometers, and the recession rates were obtained from the high-speed films. In-depth temperature data were obtained to determine the thermal penetration depths and conductivity. Preliminary results indicated that most LCAs performed comparably to or better than conventional ablators. At low flux levels (less than 454 W/sq cm), the addition of silicon carbide and polymethyl methacrylate significantly improved the ablation performance of silica substrates. The carbon-based LCAs were the most mass-efficient at high flux levels (greater than 454 W/sq cm). 16 refs.

  11. Fragmentation and ablation during entry

    SciTech Connect

    Canavan, G.H.

    1997-09-01

    This note discusses objects that both fragment and ablate during entry, using the results of previous reports to describe the velocity, pressure, and fragmentation of entering objects. It shows that the mechanisms used there to describe the breakup of non-ablating objects during deceleration remain valid for most ablating objects. It treats coupled fragmentation and ablation during entry, building on earlier models that separately discuss the entry of objects that are hard, whose high heat of ablation permits little erosion, and those who are strong whose strength prevents fragmentation, which are discussed in ``Radiation from Hard Objects,`` ``Deceleration and Radiation of Strong, Hard, Asteroids During Atmospheric Impact,`` and ``Meteor Signature Interpretation.`` This note provides a more detailed treatment of the further breakup and separation of fragments during descent. It replaces the constraint on mass per unit area used earlier to determine the altitude and magnitude of peak power radiation with a detailed analytic solution of deceleration. Model predictions are shown to be in agreement with the key features of numerical calculations of deceleration. The model equations are solved for the altitudes of maximum radiation, which agree with numerical integrations. The model is inverted analytically to infer object size and speed from measurements of peak power and altitude to provide a complete model for the approximate inversion of meteor data.

  12. Laser ablation studies of concrete

    SciTech Connect

    Savina, M.; Xu, Z.; Wang, Y.; Reed, C.; Pellin, M.

    1999-10-20

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. The authors present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied using cement and high density concrete as targets. Ablation efficiency and material removal rates were determined as functions of irradiance and pulse overlap. Doped samples were also ablated to determine the efficiency with which surface contaminants were removed and captured in the effluent. The results show that the cement phase of the material melts and vaporizes, but the aggregate portion (sand and rock) fragments. The effluent consists of both micron-size aerosol particles and chunks of fragmented aggregate material. Laser-induced optical emission spectroscopy was used to analyze the surface during ablation. Analysis of the effluent showed that contaminants such as cesium and strontium were strongly segregated into different regions of the particle size distribution of the aerosol.

  13. Femtosecond laser ablation of enamel

    NASA Astrophysics Data System (ADS)

    Le, Quang-Tri; Bertrand, Caroline; Vilar, Rui

    2016-06-01

    The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3), at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel's hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.

  14. Diaphragmatic Hernia After Radiofrequency Ablation for Hepatocellular Carcinoma

    SciTech Connect

    Yamagami, Takuji Yoshimatsu, Rika; Matsushima, Shigenori; Tanaka, Osamu; Miura, Hiroshi; Nishimura, Tsunehiko

    2011-02-15

    We describe a 71-year-old woman with a hepatocellular carcinoma who underwent percutaneous radiofrequency ablation (RF) with a single internally cooled electrode under computed tomography (CT) fluoroscopic guidance. Nine months after the procedure, CT images showed herniation of the large intestine into the right pleural cavity. To our knowledge this complication of RF performed with a single internally cooled electrode under CT guidance has not been previously reported.

  15. ECG-Guided Surveillance Technique in Cryoballoon Ablation for Paroxysmal and Persistent Atrial Fibrillation: A Strategy to Prevent From Phrenic Nerve Palsy

    PubMed Central

    Meissner, Axel; Maagh, Petra; Christoph, Arndt; Oernek, Ahmet; Plehn, Gunnar

    2016-01-01

    Aims: Phrenic nerve palsy (PNP) is still a cause for concern in Cryoballoon ablation (CBA) procedures. New surveillance techniques, such as invasive registration of the compound motor action potential (CMAP), have been thought to prevent the occurrence of PNP. The present study investigates the impact of CMAP surveillance via an alternative and non-invasive ECG-conduction technique during CBA. Methods: PVI with CBA was performed in 166 patients suffering from AF. Diaphragmal contraction was monitored by abdominal hands-on observation in Observation Group I; Observation Group II was treated using additional ECG-conduction, as a means of modified CMAP surveillance method. During the ablation of the right superior and inferior pulmonary veins, the upper extremities lead I was newly adjusted between the inferior sternum and the right chest, thereby recording the maximum CMAP. The CMAP in the above-mentioned ECG leads was continuously observed in a semi-quantitative manner. Results: PNP was observed in 10 (6%) patients in total. In Observation Group I, 6 out of 61 (9.8%) demonstrated PNP. In Observation Group II a significant decrease of PNP could be demonstrated (p <0,001) and occurred in 4 out of 105 patients (3.8%). While three patients from Observation Group I left the EP lap with an ongoing PNP, none of the patients in Observation Group II had persistent PNP outside of the EP lab. Conclusion: The present study demonstrates that additional ECG-conduction, used as modified CMAP surveillance, is an easy, effective and helpful additional safety measure to prevent PNP in CBA. PMID:27279788

  16. A Review of Mitral Isthmus Ablation

    PubMed Central

    Wong, Kelvin CK; Betts, Timothy R

    2012-01-01

    Mitral isthmus ablation forms part of the electrophysiologist’s armoury in the catheter ablation treatment of atrial fibrillation. It is well recognised however, that mitral isthmus ablation is technically challenging and incomplete ablation may be pro-arrhythmic, leading some to question its role. This article first reviews the evidence for the use of adjunctive mitral isthmus ablation and its association with the development of macroreentrant perimitral flutter. It then describes the practical techniques of mitral isthmus ablation, with particular emphasis on the assessment of bi-directional mitral isthmus block. The anatomy of the mitral isthmus is also discussed in order to understand the possible obstacles to successful ablation. Finally, novel techniques which may facilitate mitral isthmus ablation are reviewed. PMID:22912536

  17. Femtosecond lasers for machining of transparent, brittle materials: ablative vs. non-ablative femtosecond laser processing

    NASA Astrophysics Data System (ADS)

    Hendricks, F.; Matylitsky, V. V.

    2016-03-01

    This paper focuses on precision machining of transparent materials by means of ablative and non-ablative femtosecond laser processing. Ablation technology will be compared with a newly developed patent pending non-ablative femtosecond process, ClearShapeTM, using the Spectra-Physics Spirit industrial femtosecond laser.

  18. Efficacy of a novel bipolar radiofrequency ablation device on the beating heart for atrial fibrillation ablation: A chronic porcine study

    PubMed Central

    Voeller, Rochus K.; Zierer, Andreas; Lall, Shelly C.; Sakamoto, Shun-ichiro; Schuessler, Richard B.; Damiano, Ralph J.

    2015-01-01

    Background Over the 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 chronic porcine model. Methods Six pigs underwent a Cox-Maze IV procedure on a beating heart off cardiopulmonary bypass using the Atricure Isolator II™ bipolar ablation device. In addition, 6 pigs underwent median sternotomy and pericardiotomy alone to serve as a control group. All animals were survived for 30 days. Each pig underwent induction of atrial fibrillation, and was then sacrificed to remove the heart en bloc for histological assessment. MRI scan were also obtained preoperatively and postoperatively to assess atrial and ventricular function, pulmonary vein anatomy, valve function, and coronary artery patency. Results 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 to 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. Conclusions The Atricure Isolator II™ was able to create reliable chronic 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. PMID:20122702

  19. Microwave ablation of hepatocellular carcinoma

    PubMed Central

    Poggi, Guido; Tosoratti, Nevio; Montagna, Benedetta; Picchi, Chiara

    2015-01-01

    Although surgical resection is still the optimal treatment option for early-stage hepatocellular carcinoma (HCC) in patients with well compensated cirrhosis, thermal ablation techniques provide a valid non-surgical treatment alternative, thanks to their minimal invasiveness, excellent tolerability and safety profile, proven efficacy in local disease control, virtually unlimited repeatability and cost-effectiveness. Different energy sources are currently employed in clinics as physical agents for percutaneous or intra-surgical thermal ablation of HCC nodules. Among them, radiofrequency (RF) currents are the most used, while microwave ablations (MWA) are becoming increasingly popular. Starting from the 90s’, RF ablation (RFA) rapidly became the standard of care in ablation, especially in the treatment of small HCC nodules; however, RFA exhibits substantial performance limitations in the treatment of large lesions and/or tumors located near major heat sinks. MWA, first introduced in the Far Eastern clinical practice in the 80s’, showing promising results but also severe limitations in the controllability of the emitted field and in the high amount of power employed for the ablation of large tumors, resulting in a poor coagulative performance and a relatively high complication rate, nowadays shows better results both in terms of treatment controllability and of overall coagulative performance, thanks to the improvement of technology. In this review we provide an extensive and detailed overview of the key physical and technical aspects of MWA and of the currently available systems, and we want to discuss the most relevant published data on MWA treatments of HCC nodules in regard to clinical results and to the type and rate of complications, both in absolute terms and in comparison with RFA. PMID:26557950

  20. Thermal Ablation of Lung Tumors

    PubMed Central

    Sonntag, P. David; Hinshaw, J. Louis; Lubner, Meghan G.; Brace, Christopher L.; Lee, Fred T.

    2011-01-01

    Lung cancer remains the leading cause of cancer death in the United States, accounting for an estimated 29% of cancer deaths in 2009.1 Pneumonectomy or lobectomy with hilar and mediastinal lymph node sampling is the gold standard treatment and offers the best option for cure of stage 1/2 nonsmall cell lung cancer (NSCLC).2 Unfortunately, only 15% of patients present with stage 1/2 disease, and many of these patients do not meet the pulmonary physiologic guidelines for lobar resection.3 In addition to lung cancer, pulmonary metastases are present in 25% to 30% of patients dying from all types of cancer.4 For some patients with oligometastatic pulmonary disease, metastectomy is associated with an improvement in survival.5 External beam radiation traditionally has been offered as the alternative to surgical resection for NSCLC or pulmonary metastatic disease. Unfortunately, the 5-year survival following radiation for stage 1 and 2 NSCLC remains low at 15% to 20%, with local recurrence being the most common mode of failure.6,7 Thermal ablation offers an intriguing therapeutic option to increase local tumor control and survival in patients with early stage NSCLC or with limited metastatic disease from nonlung primaries who are not surgical candidates because of poor cardiopulmonary reserve, anatomic constraints limiting resection, failure of traditional therapies, or refusal of operative approaches. Thermal ablation has been shown to be effective in treating tumors in bone, kidney, and liver.8–11 Most preclinical and clinical trials have focused on demonstrating the feasibility of three modalities for pulmonary thermal ablation, namely radiofrequency (RF) ablation, microwave (MW) ablation, and cryoablation. This article discusses the unique challenges of performing thermal ablation in lung tissue and reviews the current literature regarding RF, MW, and cryoablation in the lung. PMID:21377589

  1. Microwave ablation of hepatocellular carcinoma.

    PubMed

    Poggi, Guido; Tosoratti, Nevio; Montagna, Benedetta; Picchi, Chiara

    2015-11-01

    Although surgical resection is still the optimal treatment option for early-stage hepatocellular carcinoma (HCC) in patients with well compensated cirrhosis, thermal ablation techniques provide a valid non-surgical treatment alternative, thanks to their minimal invasiveness, excellent tolerability and safety profile, proven efficacy in local disease control, virtually unlimited repeatability and cost-effectiveness. Different energy sources are currently employed in clinics as physical agents for percutaneous or intra-surgical thermal ablation of HCC nodules. Among them, radiofrequency (RF) currents are the most used, while microwave ablations (MWA) are becoming increasingly popular. Starting from the 90s', RF ablation (RFA) rapidly became the standard of care in ablation, especially in the treatment of small HCC nodules; however, RFA exhibits substantial performance limitations in the treatment of large lesions and/or tumors located near major heat sinks. MWA, first introduced in the Far Eastern clinical practice in the 80s', showing promising results but also severe limitations in the controllability of the emitted field and in the high amount of power employed for the ablation of large tumors, resulting in a poor coagulative performance and a relatively high complication rate, nowadays shows better results both in terms of treatment controllability and of overall coagulative performance, thanks to the improvement of technology. In this review we provide an extensive and detailed overview of the key physical and technical aspects of MWA and of the currently available systems, and we want to discuss the most relevant published data on MWA treatments of HCC nodules in regard to clinical results and to the type and rate of complications, both in absolute terms and in comparison with RFA. PMID:26557950

  2. Transhemangioma Ablation of Hepatocellular Carcinoma

    SciTech Connect

    Pua, Uei

    2012-12-15

    Radiofrequency ablation (RFA) is a well-established treatment modality in the treatment of early hepatocellular carcinoma (HCC) [1]. Safe trajectory of the RFA probe is crucial in decreasing collateral tissue damage and unwarranted probe transgression. As a percutaneous technique, however, the trajectory of the needle is sometimes constrained by the available imaging plane. The presence of a hemangioma beside an HCC is uncommon but poses the question of safety related to probe transgression. We hereby describe a case of transhemangioma ablation of a dome HCC.

  3. Laser ablation of human tooth

    NASA Astrophysics Data System (ADS)

    Franklin, Sushmita R.; Chauhan, P.; Mitra, A.; Thareja, R. K.

    2005-05-01

    We report the measurements of ablation threshold of human tooth in air using photo-thermal deflection technique. A third harmonic (355nm) of Nd:YAG (yttrium aluminum garnet) laser was used for irradiation and a low power helium neon laser as a probe beam. The experimental observations of ablation threshold in conjunction with theoretical model based on heat conduction equations for simulating the interaction of a laser radiation with a calcified tissue are used to estimate the absorption coefficient of human tooth.

  4. Tektite ablation - Some confirming calculations.

    NASA Technical Reports Server (NTRS)

    O'Keefe, J. A., III; Silver, A. D.; Cameron, W. S.; Adams , E. W.; Warmbrod, J. D.

    1973-01-01

    The calculation of tektite ablation has been redone, taking into account transient effects, internal radiation, melting and nonequilibrium vaporization of the glass, and the drag effect of the flanges. It is found that the results confirm the earlier calculations of Chapman and his group and of Adams and his co-workers. The general trend of the results is not sensitive to reasonable changes of the physical parameters. The ablation is predominantly by melting rather than by vaporization at all velocities up to 11 km/sec; this is surprising in view of the lack of detectable melt flow in most tektites. Chemical effects have not been considered.

  5. Ablative Therapies for Barrett's Esophagus

    PubMed Central

    Garman, Katherine S.; Shaheen, Nicholas J.

    2011-01-01

    Barrett's esophagus has gained increased clinical attention because of its association with esophageal adenocarcinoma, a cancer with increasing incidence and poor survival rates. The goals of ablating Barrett's esophagus are to decrease esophageal cancer rates and to improve overall survival and quality of life. Different techniques have been developed and tested for their effectiveness eradicating Barrett's epithelium. This review assesses the literature associated with different ablative techniques. The safety and efficacy of different techniques are discussed. This review concludes with recommendations for the clinician, including specific strategies for patient care decisions for patients with Barrett's esophagus with varying degrees of dysplasia. PMID:21373836

  6. Laser ablation based fuel ignition

    DOEpatents

    Early, J.W.; Lester, C.S.

    1998-06-23

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition. 3 figs.

  7. Laser ablation based fuel ignition

    DOEpatents

    Early, James W.; Lester, Charles S.

    1998-01-01

    There is provided a method of fuel/oxidizer ignition comprising: (a) application of laser light to a material surface which is absorptive to the laser radiation; (b) heating of the material surface with the laser light to produce a high temperature ablation plume which emanates from the heated surface as an intensely hot cloud of vaporized surface material; and (c) contacting the fuel/oxidizer mixture with the hot ablation cloud at or near the surface of the material in order to heat the fuel to a temperature sufficient to initiate fuel ignition.

  8. Interventional radiology neck procedures.

    PubMed

    Zabala Landa, R M; Korta Gómez, I; Del Cura Rodríguez, J L

    2016-05-01

    Ultrasonography has become extremely useful in the evaluation of masses in the head and neck. It enables us to determine the anatomic location of the masses as well as the characteristics of the tissues that compose them, thus making it possible to orient the differential diagnosis toward inflammatory, neoplastic, congenital, traumatic, or vascular lesions, although it is necessary to use computed tomography or magnetic resonance imaging to determine the complete extension of certain lesions. The growing range of interventional procedures, mostly guided by ultrasonography, now includes biopsies, drainages, infiltrations, sclerosing treatments, and tumor ablation. PMID:27138033

  9. Regional Pericarditis Status Post Cardiac Ablation: A Case Report

    PubMed Central

    Orme, Joseph; Eddin, Moneer; Loli, Akil

    2014-01-01

    Context: Regional pericarditis is elusive and difficult to diagnosis. Healthcare providers should be familiar with post-cardiac ablation complications as this procedure is now widespread and frequently performed. The management of regional pericarditis differs greatly from that of acute myocardial infarction. Case report: A 52 year-old male underwent atrial fibrillation ablation and developed severe mid-sternal chest pain the following day with electrocardiographic findings suggestive of acute myocardial infarction, and underwent coronary angiography, a left ventriculogram, and 2D transthoracic echocardiogram, all of which were unremarkable without evidence of obstructive coronary disease, wall motion abnormalities, or pericardial effusions. Ultimately, the patient was diagnosed with regional pericarditis. After diagnosis, the patient's presenting symptoms resolved with treatment including nonsteroidal anti-inflammatory agents and colchicine. Conclusion: This is the first reported case study of regional pericarditis status post cardiac ablation. Electrocardiographic findings were classic for an acute myocardial infarction; however, coronary angiography and left ventriculogram demonstrated no acute coronary occlusion or ventricular wall motion abnormalities. Healthcare professionals must remember that the electrocardiographic findings in pericarditis are not always classic and that pericarditis can occur status post cardiac ablation. PMID:25317395

  10. Visual servoing of a laser ablation based cochleostomy

    NASA Astrophysics Data System (ADS)

    Kahrs, Lüder A.; Raczkowsky, Jörg; Werner, Martin; Knapp, Felix B.; Mehrwald, Markus; Hering, Peter; Schipper, Jörg; Klenzner, Thomas; Wörn, Heinz

    2008-03-01

    The aim of this study is a defined, visually based and camera controlled bone removal by a navigated CO II laser on the promontory of the inner ear. A precise and minimally traumatic opening procedure of the cochlea for the implantation of a cochlear implant electrode (so-called cochleostomy) is intended. Harming the membrane linings of the inner ear can result in damage of remaining organ functions (e.g. complete deafness or vertigo). A precise tissue removal by a laser-based bone ablation system is investigated. Inside the borehole the pulsed laser beam is guided automatically over the bone by using a two mirror galvanometric scanner. The ablation process is controlled by visual servoing. For the detection of the boundary layers of the inner ear the ablation area is monitored by a color camera. The acquired pictures are analyzed by image processing. The results of this analysis are used to control the process of laser ablation. This publication describes the complete system including image processing algorithms and the concept for the resulting distribution of single laser pulses. The system has been tested on human cochleae in ex-vivo studies. Further developments could lead to safe intraoperative openings of the cochlea by a robot based surgical laser instrument.

  11. Radiofrequency ablation during continuous saline infusion can extend ablation margins

    PubMed Central

    Ishikawa, Toru; Kubota, Tomoyuki; Horigome, Ryoko; Kimura, Naruhiro; Honda, Hiroki; Iwanaga, Akito; Seki, Keiichi; Honma, Terasu; Yoshida, Toshiaki

    2013-01-01

    AIM: To determine whether fluid injection during radiofrequency ablation (RFA) can increase the coagulation area. METHODS: Bovine liver (1-2 kg) was placed on an aluminum tray with a return electrode affixed to the base, and the liver was punctured by an expandable electrode. During RFA, 5% glucose; 50% glucose; or saline fluid was infused continuously at a rate of 1.0 mL/min through the infusion line connected to the infusion port. The area and volume of the thermocoagulated region of bovine liver were determined after RFA. The Joule heat generated was determined from the temporal change in output during the RFA experiment. RESULTS: No liquid infusion was 17.3 ± 1.6 mL, similar to the volume of a 3-cm diameter sphere (14.1 mL). Mean thermocoagulated volume was significantly larger with continuous infusion of saline (29.3 ± 3.3 mL) than with 5% glucose (21.4 ± 2.2 mL), 50% glucose (16.5 ± 0.9 mL) or no liquid infusion (17.3 ± 1.6 mL). The ablated volume for RFA with saline was approximately 1.7-times greater than for RFA with no liquid infusion, representing a significant difference between these two conditions. Total Joule heat generated during RFA was highest with saline, and lowest with 50% glucose. CONCLUSION: RFA with continuous saline infusion achieves a large ablation zone, and may help inhibit local recurrence by obtaining sufficient ablation margins. RFA during continuous saline infusion can extend ablation margins, and may be prevent local recurrence. PMID:23483097

  12. An Implicit LU/AF FDTD Method

    NASA Technical Reports Server (NTRS)

    Beggs, John H.; Briley, W. Roger

    2001-01-01

    There has been some recent work to develop two and three-dimensional alternating direction implicit (ADI) FDTD schemes. These ADI schemes are based upon the original ADI concept developed by Peaceman and Rachford and Douglas and Gunn, which is a popular solution method in Computational Fluid Dynamics (CFD). These ADI schemes work well and they require solution of a tridiagonal system of equations. A new approach proposed in this paper applies a LU/AF approximate factorization technique from CFD to Maxwell s equations in flux conservative form for one space dimension. The result is a scheme that will retain its unconditional stability in three space dimensions, but does not require the solution of tridiagonal systems. The theory for this new algorithm is outlined in a one-dimensional context for clarity. An extension to two and threedimensional cases is discussed. Results of Fourier analysis are discussed for both stability and dispersion/damping properties of the algorithm. Results are presented for a one-dimensional model problem, and the explicit FDTD algorithm is chosen as a convenient reference for comparison.

  13. Factors Associated with Recurrence of Varicose Veins after Thermal Ablation: Results of The Recurrent Veins after Thermal Ablation Study

    PubMed Central

    Bush, R. G.; Bush, P.; Flanagan, J.; Fritz, R.; Gueldner, T.; Koziarski, J.; McMullen, K.; Zumbro, G.

    2014-01-01

    Background. The goal of this retrospective cohort study (REVATA) was to determine the site, source, and contributory factors of varicose vein recurrence after radiofrequency (RF) and laser ablation. Methods. Seven centers enrolled patients into the study over a 1-year period. All patients underwent previous thermal ablation of the great saphenous vein (GSV), small saphenous vein (SSV), or anterior accessory great saphenous vein (AAGSV). From a specific designed study tool, the etiology of recurrence was identified. Results. 2,380 patients were evaluated during this time frame. A total of 164 patients had varicose vein recurrence at a median of 3 years. GSV ablation was the initial treatment in 159 patients (RF: 33, laser: 126, 52 of these patients had either SSV or AAGSV ablation concurrently). Total or partial GSV recanalization occurred in 47 patients. New AAGSV reflux occurred in 40 patients, and new SSV reflux occurred in 24 patients. Perforator pathology was present in 64% of patients. Conclusion. Recurrence of varicose veins occurred at a median of 3 years after procedure. The four most important factors associated with recurrent veins included perforating veins, recanalized GSV, new AAGSV reflux, and new SSV reflux in decreasing frequency. Patients who underwent RF treatment had a statistically higher rate of recanalization than those treated with laser. PMID:24592172

  14. Percutaneous Tumor Ablation Tools: Microwave, Radiofrequency, or Cryoablation—What Should You Use and Why?

    PubMed Central

    Lubner, Meghan G.; Ziemlewicz, Timothy J.; Lee, Fred T.; Brace, Christopher L.

    2014-01-01

    Image-guided thermal ablation is an evolving and growing treatment option for patients with malignant disease of multiple organ systems. Treatment indications have been expanding to include benign tumors as well. Specifically, the most prevalent indications to date have been in the liver (primary and metastatic disease, as well as benign tumors such as hemangiomas and adenomas), kidney (primarily renal cell carcinoma, but also benign tumors such as angiomyolipomas and oncocytomas), lung (primary and metastatic disease), and soft tissue and/or bone (primarily metastatic disease and osteoid osteomas). Each organ system has different underlying tissue characteristics, which can have profound effects on the resulting thermal changes and ablation zone. Understanding these issues is important for optimizing clinical results. In addition, thermal ablation technology has evolved rapidly during the past several decades, with substantial technical and procedural improvements that can help improve clinical outcomes and safety profiles. Staying up to date on these developments is challenging but critical because the physical properties underlying the different ablation modalities and the appropriate use of adjuncts will have a tremendous effect on treatment results. Ultimately, combining an understanding of the physical properties of the ablation modalities with an understanding of the thermal kinetics in tissue and using the most appropriate ablation modality for each patient are key to optimizing clinical outcomes. Suggested algorithms are described that will help physicians choose among the various ablation modalities for individual patients. ©RSNA, 2014 PMID:25208284

  15. Percutaneous Irreversible Electroporation Lung Ablation: Preliminary Results in a Porcine Model

    SciTech Connect

    Deodhar, Ajita; Monette, Sebastien; Single, Gordon W.; Hamilton, William C.; Thornton, Raymond H.; Sofocleous, Constantinos T.; Maybody, Majid; Solomon, Stephen B.

    2011-12-15

    Objective: Irreversible electroporation (IRE) uses direct electrical pulses to create permanent 'pores' in cell membranes to cause cell death. In contrast to conventional modalities, IRE has a nonthermal mechanism of action. Our objective was to study the histopathological and imaging features of IRE in normal swine lung. Materials and Methods: Eleven female swine were studied for hyperacute (8 h), acute (24 h), subacute (96 h), and chronic (3 week) effects of IRE ablation in lung. Paired unipolar IRE applicators were placed under computed tomography (CT) guidance. Some applicators were deliberately positioned near bronchovascular structures. IRE pulse delivery was synchronized with the cardiac rhythm only when ablation was performed within 2 cm of the heart. Contrast-enhanced CT scan was performed immediately before and after IRE and at 1 and 3 weeks after IRE ablation. Representative tissue was stained with hematoxylin and eosin for histopathology. Results: Twenty-five ablations were created: ten hyperacute, four acute, and three subacute ablations showed alveolar edema and necrosis with necrosis of bronchial, bronchiolar, and vascular epithelium. Bronchovascular architecture was maintained. Chronic ablations showed bronchiolitis obliterans and alveolar interstitial fibrosis. Immediate post-procedure CT images showed linear or patchy density along the applicator tract. At 1 week, there was consolidation that resolved partially or completely by 3 weeks. Pneumothorax requiring chest tube developed in two animals; no significant cardiac arrhythmias were noted. Conclusion: Our preliminary porcine study demonstrates the nonthermal and extracellular matrix sparing mechanism of action of IRE. IRE is a potential alternative to thermal ablative modalities.

  16. Consensus for the Treatment of Varicose Vein with Radiofrequency Ablation

    PubMed Central

    Joh, Jin Hyun; Kim, Woo-Shik; Jung, In Mok; Park, Ki-Hyuk; Lee, Taeseung; Kang, Jin Mo

    2014-01-01

    The objective of this paper is to introduce the schematic protocol of radiofrequency (RF) ablation for the treatment of varicose veins. Indication: anatomic or pathophysiologic indication includes venous diameter within 2–20 mm, reflux time ≥0.5 seconds and distance from the skin ≥5 mm or subfascial location. Access: it is recommended to access at or above the knee joint for great saphenous vein and above the mid-calf for small saphenous vein. Catheter placement: the catheter tip should be placed 2.0 cm inferior to the saphenofemoral or saphenopopliteal junction. Endovenous heat-induced thrombosis ≥class III should be treated with low-molecular weight heparin. Tumescent solution: the composition of solution can be variable (e.g., 2% lidocaine 20 mL+500 mL normal saline+bicarbonate 2.5 mL with/without epinephrine). Infiltration can be done from each direction. Ablation: two cycles’ ablation for the first proximal segment of saphenous vein and the segment with the incompetent perforators is recommended. The other segments should be ablated one time. During RF energy delivery, it is recommended to apply external compression. Concomitant procedure: It is recommended to do simultaneously ambulatory phlebectomy. For sclerotherapy, it is recommended to defer at least 2 weeks. Post-procedural management: post-procedural ambulation is encouraged to reduce the thrombotic complications. Compression stocking should be applied for at least 7 days. Minor daily activity is not limited, but strenuous activities should be avoided for 2 weeks. It is suggested to take showers after 24 hours and tub baths, swimming, or soaking in water after 2 weeks. PMID:26217628

  17. Ablation Technology for the Surgical Treatment of Atrial Fibrillation

    PubMed Central

    Melby, Spencer J.; Schuessler, Richard B.; Damiano, Ralph J.

    2014-01-01

    The Cox maze procedure for the surgical treatment of atrial fibrillation has been simplified from its original cut-and-sew technique. Various energy sources now exist which create linear lines of ablation that can be used to replace the original incisions, greatly facilitating the surgical approach. This review article describes the anatomy of the atria that must be considered in choosing a successful energy source. Furthermore the device characteristics, safety profile, mechanism of tissue injury, and ability to create transmural lesions of the various energy sources that have been used in the Cox maze procedure, along with the strengths and weaknesses of each device is discussed. PMID:23995989

  18. Percutaneous Tumor Ablation with Radiofrequency

    PubMed Central

    Wood, Bradford J.; Ramkaransingh, Jeffrey R.; Fojo, Tito; Walther, McClellan M.; Libutti, Stephen K.

    2008-01-01

    BACKGROUND Radiofrequency thermal ablation (RFA) is a new minimally invasive treatment for localized cancer. Minimally invasive surgical options require less resources, time, recovery, and cost, and often offer reduced morbidity and mortality, compared with more invasive methods. To be useful, image-guided, minimally invasive, local treatments will have to meet those expectations without sacrificing efficacy. METHODS Image-guided, local cancer treatment relies on the assumption that local disease control may improve survival. Recent developments in ablative techniques are being applied to patients with inoperable, small, or solitary liver tumors, recurrent metachronous hereditary renal cell carcinoma, and neoplasms in the bone, lung, breast, and adrenal gland. RESULTS Recent refinements in ablation technology enable large tumor volumes to be treated with image-guided needle placement, either percutaneously, laparoscopically, or with open surgery. Local disease control potentially could result in improved survival, or enhanced operability. CONCLUSIONS Consensus indications in oncology are ill-defined, despite widespread proliferation of the technology. A brief review is presented of the current status of image-guided tumor ablation therapy. More rigorous scientific review, long-term follow-up, and randomized prospective trials are needed to help define the role of RFA in oncology. PMID:11900230

  19. Modern Advances in Ablative TPS

    NASA Technical Reports Server (NTRS)

    Venkatapathy, Ethiraj

    2013-01-01

    Topics covered include: Physics of Hypersonic Flow and TPS Considerations. Destinations, Missions and Requirements. State of the Art Thermal Protection Systems Capabilities. Modern Advances in Ablative TPS. Entry Systems Concepts. Flexible TPS for Hypersonic Inflatable Aerodynamic Decelerators. Conformal TPS for Rigid Aeroshell. 3-D Woven TPS for Extreme Entry Environment. Multi-functional Carbon Fabric for Mechanically Deployable.

  20. Photochemical Ablation of Organic Solids

    NASA Astrophysics Data System (ADS)

    Garrison, Barbara

    2004-03-01

    As discovered by Srinivasan in 1982, irradiation of materials by far UV laser light can lead to photochemical ablation, a process distinct from normal thermal ablation in which the laser primarily heats the material. A versatile mesoscopic model for molecular dynamics simulations of the laser ablation phenomena is presented. The model incorporates both the thermal and photochemical events, that is, both heating of the system and UV induced bond-cleavage followed by abstraction and radical-radical recombination reactions. The results from the simulations are compared to experimental data and the basic physics and chemistry for each irradiation regime are discussed. Initial results from polymer ablation simulations will be presented. L. V. Zhigilei, P. B. S. Kodali and B. J. Garrison, J. Phys. Chem. B, 102, 2845-2853 (1998); L. V. Zhigilei and B. J. Garrison, Journal of Applied Physics, 88, 1281-1298 (2000). Y. G. Yingling, L. V. Zhigilei and B. J. Garrison, J. Photochemistry and Photobiology A: Chemistry, 145, 173-181 (2001); Y. G. Yingling and B. J. Garrison, Chem. Phys. Lett., 364, 237-243 (2002).

  1. Electron Beam Ablation of Metals

    NASA Astrophysics Data System (ADS)

    Kovaleski, S. D.; Gilgenbach, R. M.; Rintamaki, J. I.; Ang, L. K.; Spindler, H. L.; Cohen, W. E.; Lau, Y. Y.; Lash, J. S.

    1996-10-01

    An experiment has recently been devised for material ablation using a channelspark electron beam. The ultimate goal of this experiment is to deposit thin films by electron beam ablation. The channelspark is a pseudospark device developed by Forschungszentrum Karlsruhe (G. Muller, C. Schultheiss, Proc. of Beams, 2, 833(1994)) for production of high current, low energy electron beams. The channelspark has the following operating parameters: a 15-20kV accelerating potential and measured source current of <2000A. Initial experiments have concentrated on characterizing ion-focused electron beam current transport through the necessary background fill gas (typically 5-50 mTorr of Argon). Ablation of Al, Fe, and Ti is being studied with spectroscopy and electron beam current diagnostics. Physical beam target damage is also being investigated and compared to laser ablated targets. Simulations of electron transport and energy deposition are being conducted via the ITS-TIGER code (Sandia Report No. SAND 91-1634) developed at Sandia National Laboratory.

  2. Photophysical ablation of porous silicon

    NASA Astrophysics Data System (ADS)

    Aksenov, Valerii P.; Mikhailova, G. N.

    2004-07-01

    Laser ablation of porous silicon as a function of laser wavelength and width of silicon nanowires was studied in our experiments. The time-resolved evolution of the cloud of the porous silicon particles produced by laser ablation is studied in situ by the analysis of the kinetics of photoluminescence signal. The laser ablation of porous silicon produced by pulses of 532 nm or 337 nm radiation with addition of synchronized power pulses of 1064 nm radiation. The cloud of the nanometer-sized silicon crystallites had the high enhancement of luminescence quantum efficiency in the red region of spectra. The slow PL kinetics component, which is due to the localized carriers, decays on a millisecond time scale. The squeezed electron-hole plasma heating by IR-laser radiation may produce a damage of silicon nanowires. The fragments of nanowires in cloud must be smaller, than the critical length. The energy of excitation of e-h pair in fragment with contribution of longitude quantum modes must be lower than energy of the excited photons. Particles with lesser length don't absorb excited laser radiation and don't damage. For this case we may speak about the quantum mechanism of laser ablation of nanowires.

  3. [The radiofrequency ablation of accessory pathways in 100 consecutive patients with supraventricular tachycardias].

    PubMed

    Colín, L; Kershenovich, S; Iturralde, P; Dan, L; Martínez Ríos, M A; Casanova, M; González Hermosillo, J A

    1993-01-01

    The purpose of this study is to describe the results and the complications of radiofrequency catheter ablation, of accessory pathways in 100 consecutive patients. We had one patient with two pathways. Of the 101 accessory pathways, 56 were overt and 45 concealed. Only 19 patients have had a previous electrophysiology study, in the others, the study and the ablation were performed simultaneously. The location of the accessory pathways were as follows: 61 pathways in the free wall of the left ventricle, 4 in the free wall of the right ventricle, 25 in the left posteroseptal region, 9 in the right posteroseptal region and 2 in the right anteroseptal area. The time required for the diagnostic component of the electrophysiology study, the ablation procedure and the fluoroscopic time was recorded for each patient. Ninety-one of 101 accessory AV connections were successfully ablated (90%). Our success rate for the initial attempt was 87%. We had the opportunity to do a second attempt in only 4 out of 14 patients. The mean time of the procedure, including the electrophysiology test and the ablation was 95.6 %/-55.3 minutes. We have had a recurrence of 9% and 4% of non fatal complications. Radiofrequency catheter ablation can be performed safely and with a high success rate. PMID:8466365

  4. Optoacoustic monitoring of real-time lesion formation during radiofrequency catheter ablation

    NASA Astrophysics Data System (ADS)

    Pang, Genny A.; Bay, Erwin; Deán-Ben, Xosé L.; Razansky, Daniel

    2015-03-01

    Current radiofrequency cardiac ablation procedures lack real-time lesion monitoring guidance, limiting the reliability and efficacy of the treatment. The objective of this work is to demonstrate that optoacoustic imaging can be applied to develop a diagnostic technique applicable to radiofrequency ablation for cardiac arrhythmia treatment with the capabilities of real-time monitoring of ablated lesion size and geometry. We demonstrate an optoacoustic imaging method using a 256-detector optoacoustic imaging probe and pulsed-laser illumination in the infrared wavelength range that is applied during radiofrequency ablation in excised porcine myocardial tissue samples. This technique results in images with high contrast between the lesion volume and unablated tissue, and is also capable of capturing time-resolved image sequences that provide information on the lesion development process. The size and geometry of the imaged lesion were shown to be in excellent agreement with the histological examinations. This study demonstrates the first deep-lesion real-time monitoring for radiofrequency ablation generated lesions, and the technique presented here has the potential for providing critical feedback that can significantly impact the outcome of clinical radiofrequency ablation procedures.

  5. The strainrange partitioning behavior of an advanced gas turbine disk alloy, AF2-1DA

    NASA Technical Reports Server (NTRS)

    Halford, G. R.; Nachtigall, A. J.

    1979-01-01

    The low-cycle, creep-fatigue characteristics of the advanced gas turbine disk alloy, AF2-1DA have been determined at 1400 F and are presented in terms of the method of strainrange partitioning (SRP). The mean stresses which develop in the PC and CP type SRP cycles at the lowest inelastic strainrange were observed to influence the cyclic lives to a greater extent than the creep effects and hence interfered with a conventional interpretation of the results by SRP. A procedure is proposed for dealing with the mean stress effects on life which is compatible with SRP.

  6. Prevention of Obesity and Insulin Resistance by Estrogens Requires ERα Activation Function-2 (ERαAF-2), Whereas ERαAF-1 Is Dispensable

    PubMed Central

    Handgraaf, Sandra; Riant, Elodie; Fabre, Aurélie; Waget, Aurélie; Burcelin, Rémy; Lière, Philippe; Krust, Andrée; Chambon, Pierre; Arnal, Jean-François; Gourdy, Pierre

    2013-01-01

    The beneficial metabolic actions of estrogen-based therapies are mainly mediated by estrogen receptor α (ERα), a nuclear receptor that regulates gene transcription through two activation functions (AFs): AF-1 and AF-2. Using mouse models deleted electively for ERαAF-1 (ERαAF-1°) or ERαAF-2 (ERαAF-2°), we determined their respective roles in the actions of estrogens on body composition and glucose homeostasis in response to either a normal diet or a high-fat diet (HFD). ERαAF-2° males and females developed accelerated weight gain, massive adiposity, severe insulin resistance, and glucose intolerance—quite reminiscent of the phenotype observed in mice deleted for the entire ERα protein (ERα−/−). In striking contrast, ERαAF-1° and wild-type (wt) mice shared a similar metabolic phenotype. Accordingly, 17β-estradiol administration regulated key metabolic genes in insulin-sensitive tissues and conferred a strong protection against HFD-induced metabolic disturbances in wt and ERαAF-1° ovariectomized mice, whereas these actions were totally abrogated in ERαAF-2° and ERα−/− mice. Thus, whereas both AFs have been previously shown to contribute to endometrial and breast cancer cell proliferation, the protective effect of estrogens against obesity and insulin resistance depends on ERαAF-2 but not ERαAF-1, thereby delineating new options for selective modulation of ERα. PMID:23903353

  7. Esophageal papilloma: Flexible endoscopic ablation by radiofrequency

    PubMed Central

    del Genio, Gianmattia; del Genio, Federica; Schettino, Pietro; Limongelli, Paolo; Tolone, Salvatore; Brusciano, Luigi; Avellino, Manuela; Vitiello, Chiara; Docimo, Giovanni; Pezzullo, Angelo; Docimo, Ludovico

    2015-01-01

    Squamous papilloma of the esophagus is a rare benign lesion of the esophagus. Radiofrequency ablation is an established endoscopic technique for the eradication of Barrett esophagus. No cases of endoscopic ablation of esophageal papilloma by radiofrequency ablation (RFA) have been reported. We report a case of esophageal papilloma successfully treated with a single session of radiofrequency ablation. Endoscopic ablation of the lesion was achieved by radiofrequency using a new catheter inserted through the working channel of endoscope. The esophageal ablated tissue was removed by a specifically designed cup. Complete ablation was confirmed at 3 mo by endoscopy with biopsies. This case supports feasibility and safety of as a new potential indication for BarrxTM RFA in patients with esophageal papilloma. PMID:25789102

  8. Laser Ablation as Treatment Strategy for Medically Refractory Dominant Insular Epilepsy – Therapeutic and Functional Considerations

    PubMed Central

    Hawasli, Ammar H.; Bandt, S. Kathleen; Hogan, R. Edward; Werner, Nicole; Leuthardt, Eric C.

    2014-01-01

    Since its introduction to neurosurgery in 2008, laser ablative techniques have been largely confined to the management of unresectable tumors. Application of this technology for the management of focal epilepsy in the adult population has not been fully explored. Given that nearly 1,000,000 Americans live with medically refractory epilepsy and current surgical techniques only address a fraction of epileptic pathologies, additional therapeutic options are needed. We report the successful treatment of dominant insular epilepsy in a 53 year-old male with minimally-invasive laser ablation complicated by mild verbal and memory deficits. We also report neuropsychological test data on this patient before surgery and at 8-months after the ablation procedure. This account represents the first reported successful patient outcome of laser ablation as an effective treatment option for medically refractory post-stroke epilepsy in an adult. PMID:25359500

  9. Global Endometrial Ablation in the Presence of Essure® Microinserts

    PubMed Central

    Aldape, Diana; Chudnoff, Scott G; Levie, Mark D

    2013-01-01

    Abnormal uterine bleeding (AUB) affects 30% of women at some time during their reproductive years and is one of the most common reasons a woman sees a gynecologist. Many women are turning to endometrial ablation to manage their AUB. This article reviews the data relating to the available endometrial ablation techniques performed with hysteroscopic sterilization, and focuses on data from patients who had Essure® (Conceptus, San Carlos, CA) coils placed prior to performance of endometrial ablation. Reviewed specifically are data regarding safety and efficacy of these two procedures when combined. Data submitted to the US Food and Drug Administration for the three devices currently approved are reviewed, as well as all published case series. Articles included were selected based on a PubMed search for endometrial ablation (also using the brand names of the different techniques currently available), hysteroscopic sterilization, and Essure. PMID:24358407

  10. PATH OPTIMIZATION AND CONTROL OF A SHAPE MEMORY ALLOY ACTUATED CATHETER FOR ENDOCARDIAL RADIOFREQUENCY ABLATION

    PubMed Central

    Wiest, Jennifer H.; Buckner, Gregory D.

    2014-01-01

    This paper introduces a real-time path optimization and control strategy for shape memory alloy (SMA) actuated cardiac ablation catheters, potentially enabling the creation of more precise lesions with reduced procedure times and improved patient outcomes. Catheter tip locations and orientations are optimized using parallel genetic algorithms to produce continuous ablation paths with near normal tissue contact through physician-specified points. A nonlinear multivariable control strategy is presented to compensate for SMA hysteresis, bandwidth limitations, and coupling between system inputs. Simulated and experimental results demonstrate efficient generation of ablation paths and optimal reference trajectories. Closed-loop control of the SMA-actuated catheter along optimized ablation paths is validated experimentally. PMID:25684857

  11. Comparison of transcatheter laser and direct-current shock ablation of endocardium near tricuspid anulus

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Zhen; Wang, Shi-Wen; Li, Junheng

    1993-03-01

    Forty to eighty percent of the patients with accessory pathways (APs) manifest themselves by tachyarrhythmias. Many of these patients needed either life-long medical therapy or surgery. In order to avoid the discomfort and expenses in surgical procedures, closed chest percutaneous catheter ablation of APs became a potentially desirable therapeutic approach. Many investigations indicated that ablation of right APs by transcatheter direct current (dc) shock could cause life-threatening arrhythmias, right coronary arterical (RCA) spasm, etc. With the development of transcatheter laser technique, it has been used in drug-incurable arrhythmias. The results show that laser ablation is much safer than surgery and electric shock therapy. The purpose of this study is to explore the effectiveness, advantages, and complications with transcatheter Nd:YAG laser and dc shock in the ablation of right atrioventricular accessory pathways in the atrium near the tricuspid annulus (TA) in 20 dogs.

  12. Fully Implicit Ablation and Thermal Response Program for Spacecraft Heatshield Analysis

    NASA Technical Reports Server (NTRS)

    Chen, Y. K.; Milos, Frank; Rasky, Daniel J. (Technical Monitor)

    1997-01-01

    A fully implicit ablation and thermal response program has been developed for the simulation of one-dimensional transient transport of thermal energy in a multilayer stack of isotropic materials and structure which can ablate from a front surface and decompose in-depth. Equations and numerical procedures for solution are described. Solutions are compared with those of Aerotherm Charring Material Thermal Response and Ablation Program, and with the arcjet data. The code is numerically more stable, and solves much wider range of problems compared with the existing explicit code. Applications of the code for the analysis of aeroshell heatshields of Stardust, Mars 2001, and Mars Microprobe using the advanced Light Weight Ceramic Ablators developed at the NASA Ames Research Center are presented and discussed in detail.

  13. Tuning the Music: Acoustic Force Spectroscopy (AFS) 2.0.

    PubMed

    Kamsma, Douwe; Creyghton, Ramon; Sitters, Gerrit; Wuite, Gijs J L; Peterman, Erwin J G

    2016-08-01

    AFS is a recently introduced high-throughput single-molecule technique that allows studying structural and mechanochemical properties of many biomolecules in parallel. To further improve the method, we developed a modelling tool to optimize the layer thicknesses, and a calibration method to experimentally validate the modelled force profiles. After optimization, we are able to apply 350pN on 4.5μm polystyrene beads, without the use of an amplifier, at the coverslip side of the AFS chip. Furthermore, we present the use of a transparent piezo to generate the acoustic force and we show that AFS can be combined with high-NA oil or water-immersion objectives. With this set of developments AFS will be applicable to a broad range of single-molecule experiments. PMID:27163865

  14. Palliative Treatment of Rectal Carcinoma Recurrence Using Radiofrequency Ablation

    SciTech Connect

    Mylona, Sophia Karagiannis, Georgios Patsoura, Sofia; Galani, Panagiota; Pomoni, Maria; Thanos, Loukas

    2012-08-15

    Purpose: To evaluate the safety and efficacy of CT-guided radiofrequency (RF) ablation for the palliative treatment of recurrent unresectable rectal tumors. Materials and Methods: Twenty-seven patients with locally recurrent rectal cancer were treated with computed tomography (CT)-guided RF ablation. Therapy was performed with the patient under conscious sedation with a seven- or a nine-array expandable RF electrode for 8-10 min at 80-110 Degree-Sign C and a power of 90-110 W. All patients went home under instructions the next day of the procedure. Brief Pain Inventory score was calculated before and after (1 day, 1 week, 1 month, 3 months, and 6 months) treatment. Results: Complete tumor necrosis rate was 77.8% (21 of a total 27 procedures) despite lesion location. BPI score was dramatically decreased after the procedure. The mean preprocedure BPI score was 6.59, which decreased to 3.15, 1.15, and 0.11 at postprocedure day 1, week 1, and month 1, respectively, after the procedure. This decrease was significant (p < 0.01 for the first day and p < 0.001 for the rest of the follow-up intervals (paired Student t test; n - 1 = 26) for all periods during follow-up. Six patients had partial tumor necrosis, and we were attempted to them with a second procedure. Although the necrosis area showed a radiographic increase, no complete necrosis was achieved (secondary success rate 65.6%). No immediate or delayed complications were observed. Conclusion: CT-guided RF ablation is a minimally invasive, safe, and highly effective technique for treatment of malignant rectal recurrence. The method is well tolerated by patients, and pain relief is quickly achieved.

  15. Lung Tumor Radiofrequency Ablation: Where Do We Stand?

    SciTech Connect

    Baere, Thierry de

    2011-04-15

    Today, radiofrequency ablation (RFA) of primary and metastatic lung tumor is increasingly used. Because RFA is most often used with curative intent, preablation workup must be a preoperative workup. General anesthesia provides higher feasibility than conscious sedation. The electrode positioning must be performed under computed tomography for sake of accuracy. The delivery of RFA must be adapted to tumor location, with different impedances used when treating tumors with or without pleural contact. The estimated rate of incomplete local treatment at 18 months was 7% (95% confidence interval, 3-14) per tumor, with incomplete treatment depicted at 4 months (n = 1), 6 months (n = 2), 9 months (n = 2), and 12 months (n = 2). Overall survival and lung disease-free survival at 18 months were, respectively, 71 and 34%. Size is a key point for tumor selection because large size is predictive of incomplete local treatment and poor survival. The ratio of ablation volume relative to tumor volume is predictive of complete ablation. Follow-up computed tomography that relies on the size of the ablation zone demonstrates the presence of incomplete ablation. Positron emission tomography might be an interesting option. Chest tube placement for pneumothorax is reported in 8 to 12%. Alveolar hemorrhage and postprocedure hemoptysis occurred in approximately 10% of procedures and rarely required specific treatment. Death was mostly related to single-lung patients and hilar tumors. No modification of forced expiratory volume in the first second between pre- and post-RFA at 2 months was found. RFA in the lung provides a high local efficacy rate. The use of RFA as a palliative tool in combination with chemotherapy remains to be explored.

  16. Software-assisted post-interventional assessment of radiofrequency ablation

    NASA Astrophysics Data System (ADS)

    Rieder, Christian; Geisler, Benjamin; Bruners, Philipp; Isfort, Peter; Na, Hong-Sik; Mahnken, Andreas H.; Hahn, Horst K.

    2014-03-01

    Radiofrequency ablation (RFA) is becoming a standard procedure for minimally invasive tumor treatment in clinical practice. Due to its common technical procedure, low complication rate, and low cost, RFA has become an alternative to surgical resection in the liver. To evaluate the therapy success of RFA, thorough follow-up imaging is essential. Conventionally, shape, size, and position of tumor and coagulation are visually compared in a side-by-side manner using pre- and post-interventional images. To objectify the verification of the treatment success, a novel software assistant allowing for fast and accurate comparison of tumor and coagulation is proposed. In this work, the clinical value of the proposed assessment software is evaluated. In a retrospective clinical study, 39 cases of hepatic tumor ablation are evaluated using the prototype software and conventional image comparison by four radiologists with different levels of experience. The cases are randomized and evaluated in two sessions to avoid any recall-bias. Self-confidence of correct diagnosis (local recurrence vs. no local recurrence) on a six-point scale is given for each case by the radiologists. Sensitivity, specificity, positive and negative predictive values as well as receiver operating curves are calculated for both methods. It is shown that the software-assisted method allows physicians to correctly identify local tumor recurrence with a higher percentage than the conventional method (sensitivity: 0.6 vs. 0.35), whereas the percentage of correctly identified successful ablations is slightly reduced (specificity: 0.83 vs. 0.89).

  17. Catheter ablation of atrioventricular accessory pathways by radiofrequency current.

    PubMed

    Wang, L; Hu, D; Ding, Y

    1993-12-15

    Tachycardias mediated by atrioventricular accessory pathways, which are refractory to antiarrhythmic drug therapy have been treated both by surgery and by catheter ablation with high energy direct current shock. These procedures have variable success rates and substantial associated morbidity and mortality. Radiofrequency ablation, a newer, low-energy technique is potentially safer and more effective. Of 110 patients with 117 accessory pathways, 101 were located on the left side and 16 on the right. Accessory pathway conduction was abolished permanently in 101 (91.8%) patients. VA conduction dissociation and VA decremental conduction were found in 88 and 13 successful patients, respectively. Four (3.9%) patients with decremental VA conduction suffered arrhythmia recurrence after a mean of 8 months follow-up. Complications developed in two patients including right femoral vein thrombosis and left ventricular insufficiency. There were no deaths from the procedure. We conclude that radiofrequency current ablation is a safe and effective interventional modality for patients with symptomatic tachycardias mediated by atrioventricular accessory pathways. PMID:8112920

  18. Anatomic Guidance For Ablation: Atrial Flutter, Fibrillation, and Outflow Tract Ventricular Tachycardia

    PubMed Central

    Sehar, Nandini; Mears, Jennifer; Bisco, Susan; Patel, Sandeep; Lachman, Nirusha; Asirvatham, Samuel J

    2010-01-01

    After initial documentation of excellent efficacy with radiofrequency ablation, this procedure is being performed increasingly in more complex situations and for more difficult arrhythmia. In these circumstances, an accurate knowledge of the anatomic basis for the ablation procedure will help maintain this efficacy and improve safety. In this review, we discuss the relevant anatomy for electrophysiology interventions for typical right atrial flutter, atrial fibrillation, and outflow tract ventricular tachycardia. In the pediatric population, maintaining safety is a greater challenge, and here again, knowing the neighboring and regional anatomy of the arrhythmogenic substrate for these arrhythmias may go a long way in preventing complications. PMID:20811537

  19. Percutaneous Radiofrequency Ablation of a Small Renal Mass Complicated by Appendiceal Perforation

    SciTech Connect

    Boone, Judith; Bex, Axel; Prevoo, Warner

    2012-06-15

    Percutaneous radiofrequency ablation (RFA) has gained wide acceptance as nephron-sparing therapy for small renal masses in select patients. Generally, it is a safe procedure with minor morbidity and acceptable short-term oncologic outcome. However, as a result of the close proximity of vital structures, such as the bowel, ureter, and large vessels, to the ablative field, complications regarding these structures may occur. This is the first article describing appendiceal perforation as a complication of computed tomography-guided RFA despite hydrodissection. When performing this innovative and promising procedure one should be aware of the possibility of particular minor and even major complications.

  20. Radiofrequency Ablation of Osteoid Osteoma: Initial Experience with a New Monopolar Ablation Device

    SciTech Connect

    Mahnken, Andreas H. Bruners, Philipp; Delbrueck, Heide; Guenther, Rolf W.

    2011-06-15

    The purpose of this article is to report our initial experience with the 'off-label' use of a new monopolar radiofrequency (RF) probe for percutaneous ablation of osteoid osteomas. Seventeen patients (12 male and 5 female, mean age 24.8 [range 9-49]) with osteoid osteoma were treated by computed tomography (CT)-guided RF ablation (RFA). All procedures were performed with the patient under general aesthesia. After localization of the nidus, a 13G hollow drill was introduced into the nidus through a 7F introducer sheath. A monopolar 16.5G RF probe with a 9-mm active tip (Soloist; Boston Scientific, Natick, MA) was inserted through the introducer sheath and connected to the RF generator. Energy application was started at 2 W and subsequently increased every 2 min by 1 W to a maximum of 8 W. The procedure ended if impedance increased by 500 Ohm-Sign . Mean duration of energy deposition was 14.2 {+-} 3.3 min. Fourteen of 17 patients (82%) were free of symptoms at 29.9 {+-} 14.8 (range 4 to 47) months of follow-up. The primary and secondary success rates were 83% and 100%, respectively. In 3 patients, recurrence of pain at 6 (n = 1) and 15 (n = 2) months after the initial procedure was successfully treated by reablation. There were no complications. Monopolar RFA using the Soloist probe is effective and safe for the treatment of osteoid osteoma. It results in comparable success rates as other monopolar or bipolar RF systems in the treatment of osteoid osteoma.

  1. Radiofrequency ablation of osteoid osteoma: initial experience with a new monopolar ablation device.

    PubMed

    Mahnken, Andreas H; Bruners, Philipp; Delbrück, Heide; Günther, Rolf W

    2011-06-01

    The purpose of this article is to report our initial experience with the "off-label" use of a new monopolar radiofrequency (RF) probe for percutaneous ablation of osteoid osteomas. Seventeen patients (12 male and 5 female, mean age 24.8 [range 9-49]) with osteoid osteoma were treated by computed tomography (CT)-guided RF ablation (RFA). All procedures were performed with the patient under general aesthesia. After localization of the nidus, a 13G hollow drill was introduced into the nidus through a 7F introducer sheath. A monopolar 16.5G RF probe with a 9-mm active tip (Soloist; Boston Scientific, Natick, MA) was inserted through the introducer sheath and connected to the RF generator. Energy application was started at 2 W and subsequently increased every 2 min by 1 W to a maximum of 8 W. The procedure ended if impedance increased by 500 Ω. Mean duration of energy deposition was 14.2±3.3 min. Fourteen of 17 patients (82%) were free of symptoms at 29.9±14.8 (range 4 to 47) months of follow-up. The primary and secondary success rates were 83% and 100%, respectively. In 3 patients, recurrence of pain at 6 (n=1) and 15 (n=2) months after the initial procedure was successfully treated by reablation. There were no complications. Monopolar RFA using the Soloist probe is effective and safe for the treatment of osteoid osteoma. It results in comparable success rates as other monopolar or bipolar RF systems in the treatment of osteoid osteoma. PMID:20490491

  2. Mechanochemical endovenous Ablation versus RADiOfrequeNcy Ablation in the treatment of primary great saphenous vein incompetence (MARADONA): study protocol for a randomized controlled trial

    PubMed Central

    2014-01-01

    Background Radiofrequency ablation (RFA) is associated with an excellent outcome in the treatment of great saphenous vein (GSV) incompetence. The use of thermal energy as a treatment source requires the instillation of tumescence anesthesia. Mechanochemical endovenous ablation (MOCA) combines mechanical endothelial damage, using a rotating wire, with the infusion of a liquid sclerosant. Tumescence anesthesia is not required. Preliminary experiences with MOCA showed good results and low post-procedural pain. Methods/Design The MARADONA (Mechanochemical endovenous Ablation versus RADiOfrequeNcy Ablation) trial is a multicenter randomized controlled trial in which 460 patients will be randomly allocated to MOCA or RFA. All patients with primary GSV incompetence who meet the eligibility criteria will be invited to participate in this trial. The primary endpoints are anatomic and clinical success at a one-year follow-up, and post-procedural pain. The secondary endpoints are technical success, complications, operation time, procedural pain, disease-specific quality of life, time taken to return to daily activities and/or work, and cost-efficiency analyses after RFA or MOCA. Both groups will be evaluated on an intention to treat base. Discussion The MARADONA trial is designed to show equal results in anatomic and clinical success after one year, comparing MOCA with RFA. In our hypothesis MOCA has an equal anatomic and clinical success compared with RFA, with less post-procedural pain. Trial registration Clinicaltrials NCT01936168 PMID:24726004

  3. Microwave Ablation Compared with Radiofrequency Ablation for Breast Tissue in an Ex Vivo Bovine Udder Model

    SciTech Connect

    Tanaka, Toshihiro; Westphal, Saskia; Isfort, Peter; Braunschweig, Till; Penzkofer, Tobias Bruners, Philipp; Kichikawa, Kimihiko; Schmitz-Rode, Thomas Mahnken, Andreas H.

    2012-08-15

    Purpose: To compare the effectiveness of microwave (MW) ablation with radiofrequency (RF) ablation for treating breast tissue in a nonperfused ex vivo model of healthy bovine udder tissue. Materials and Methods: MW ablations were performed at power outputs of 25W, 35W, and 45W using a 915-MHz frequency generator and a 2-cm active tip antenna. RF ablations were performed with a bipolar RF system with 2- and 3-cm active tip electrodes. Tissue temperatures were continuously monitored during ablation. Results: The mean short-axis diameters of the coagulation zones were 1.34 {+-} 0.14, 1.45 {+-} 0.13, and 1.74 {+-} 0.11 cm for MW ablation at outputs of 25W, 35W, and 45W. For RF ablation, the corresponding values were 1.16 {+-} 0.09 and 1.26 {+-} 0.14 cm with electrodes having 2- and 3-cm active tips, respectively. The mean coagulation volumes were 2.27 {+-} 0.65, 2.85 {+-} 0.72, and 4.45 {+-} 0.47 cm{sup 3} for MW ablation at outputs of 25W, 35W, and 45W and 1.18 {+-} 0.30 and 2.29 {+-} 0.55 cm{sup 3} got RF ablation with 2- and 3-cm electrodes, respectively. MW ablations at 35W and 45W achieved significantly longer short-axis diameters than RF ablations (P < 0.05). The highest tissue temperature was achieved with MW ablation at 45W (P < 0.05). On histological examination, the extent of the ablation zone in MW ablations was less affected by tissue heterogeneity than that in RF ablations. Conclusion: MW ablation appears to be advantageous with respect to the volume of ablation and the shape of the margin of necrosis compared with RF ablation in an ex vivo bovine udder.

  4. Fast and automatic depth control of iterative bone ablation based on optical coherence tomography data

    NASA Astrophysics Data System (ADS)

    Fuchs, Alexander; Pengel, Steffen; Bergmeier, Jan; Kahrs, Lüder A.; Ortmaier, Tobias

    2015-07-01

    Laser surgery is an established clinical procedure in dental applications, soft tissue ablation, and ophthalmology. The presented experimental set-up for closed-loop control of laser bone ablation addresses a feedback system and enables safe ablation towards anatomical structures that usually would have high risk of damage. This study is based on combined working volumes of optical coherence tomography (OCT) and Er:YAG cutting laser. High level of automation in fast image data processing and tissue treatment enables reproducible results and shortens the time in the operating room. For registration of the two coordinate systems a cross-like incision is ablated with the Er:YAG laser and segmented with OCT in three distances. The resulting Er:YAG coordinate system is reconstructed. A parameter list defines multiple sets of laser parameters including discrete and specific ablation rates as ablation model. The control algorithm uses this model to plan corrective laser paths for each set of laser parameters and dynamically adapts the distance of the laser focus. With this iterative control cycle consisting of image processing, path planning, ablation, and moistening of tissue the target geometry and desired depth are approximated until no further corrective laser paths can be set. The achieved depth stays within the tolerances of the parameter set with the smallest ablation rate. Specimen trials with fresh porcine bone have been conducted to prove the functionality of the developed concept. Flat bottom surfaces and sharp edges of the outline without visual signs of thermal damage verify the feasibility of automated, OCT controlled laser bone ablation with minimal process time.

  5. The Feasibility and Efficacy of a Large-Sized Lasso Catheter Combined With 3 Dimensional Mapping System for Catheter Ablation of Atrial Fibrillation

    PubMed Central

    Jang, Sung-Won; Shin, Woo-Seung; Kim, Ji-Hoon; Choi, Min-Seok; Choi, Yun Seok; Lee, Man-Young; Rho, Tai-Ho

    2011-01-01

    Background and Objectives We aimed to investigate whether a large-sized Lasso catheter could increase the success rate of immediate complete pulmonary vein (PV) antral isolation and improve the outcome of catheter ablation in atrial fibrillation (AF) patients. Subjects and Methods This study included 107 consecutive patients (67 males, mean age: 57.8±9.7 years) who underwent PV mapping and ablation due to symptomatic drug-refractory AF. The first 43 patients underwent isolation of both ipsilateral PVs using the Carto-Merge 3 dimensional mapping system (group 1). The other 64 patients underwent isolation of both ipsilateral PVs using the same technique with a large-sized (a diameter of 30 to 35 mm) Lasso cathe-ter (group 2). When ipsilateral PVs did not show any potential after the initial circumferential ablation, we defined this as 'immediate complete antral isolation (ICAI)'. We compared the AF recurrence rate of both groups. Results There was no significant difference of the clinical characteristics between group 1 and group 2. All the patients were followed-up for 1 year. The ICAI rate of group 1 and group 2 was significantly different (21% vs. 78%, p<0.001), and the AF recurrence rates of group 1 and group 2 were also different (34.9% vs. 18.8%, p=0.042). Using multiple logistic regression analysis, the use of a large-sized Lasso catheter was a significant predictive factor for preventing recurrence (odds ratio: 0.489, 95% confidence interval: 0.136-0.927). Conclusion It is likely that a large-sized Lasso catheter plays an important role in achieving ICAI and in lowering the rate of AF recurrence. PMID:21949528

  6. Bronchopleural Fistula After Radiofrequency Ablation of Lung Tumours

    SciTech Connect

    Cannella, Mathieu; Cornelis, Francois; Descat, Edouard; Ferron, Stephane; Carteret, Thibault; Castagnede, Hugues; Palussiere, Jean

    2011-02-15

    The present article describes two cases of bronchopleural fistula (BPF) occurring after radiofrequency ablation of lung tumors. Both procedures were carried out using expandable multitined electrodes, with no coagulation of the needle track. After both ablations, ground-glass opacities encompassed the nodules and abutted the visceral pleura. The first patient had a delayed pneumothorax, and the second had a recurrent pneumothorax. Both cases of BPF were diagnosed on follow-up computed tomography chest scans (i.e., visibility of a distinct channel between the lung or a peripheral bronchus and the pleura) and were successfully treated with chest tubes alone. Our goal is to highlight the fact that BPF can occur without needle-track coagulation and to suggest that minimally invasive treatment is sufficient to cure BPFs of this specific origin.

  7. Effective Treatment of Chronic Radiation Proctitis Using Radiofrequency Ablation

    PubMed Central

    Zhou, Chao; Adler, Desmond C.; Becker, Laren; Chen, Yu; Tsai, Tsung-Han; Figueiredo, Marisa; Schmitt, Joseph M.; Fujimoto, James G.

    2009-01-01

    Endoscopic argon plasma coagulation and bipolar electrocautery are currently preferred treatments for chronic radiation proctitis, but ulcerations and strictures frequently occur. Radiofrequency ablation (RFA) has been successful for mucosal ablation in the esophagus. Here we report the efficacy of RFA with the BarRx Halo90 system in three patients with bleeding from chronic radiation proctitis. In all cases, the procedure was well tolerated and hemostasis was achieved after 1 or 2 RFA sessions. Re-epithelialization of squamous mucosa was observed over areas of prior hemorrhage. No stricturing or ulceration was seen on follow-up up to 19 months after RFA treatment. Real-time endoscopic optical coherence tomography (EOCT) visualized epithelialization and subsurface tissue microvasculature pre- and post-treatment, demonstrating its potential for follow-up assessment of endoscopic therapies. PMID:20593010

  8. Laser-ablation-assisted microparticle acceleration for drug delivery

    NASA Astrophysics Data System (ADS)

    Menezes, V.; Takayama, K.; Ohki, T.; Gopalan, J.

    2005-10-01

    Localized drug delivery with minimal tissue damage is desired in some of the clinical procedures such as gene therapy, treatment of cancer cells, treatment of thrombosis, etc. We present an effective method for delivering drug-coated microparticles using laser ablation on a thin metal foil containing particles. A thin metal foil, with a deposition of a layer of microparticles is subjected to laser ablation on its backface such that a shock wave propagates through the foil. Due to shock wave loading, the surface of the foil containing microparticles is accelerated to very high speeds, ejecting the deposited particles at hypersonic speeds. The ejected particles have sufficient momentum to penetrate soft body tissues, and the penetration depth observed is sufficient for most of the pharmacological treatments. We have tried delivering 1μm tungsten particles into gelatin models that represent soft tissues, and liver tissues of an experimental rat. Sufficient penetration depths have been observed in these experiments with minimum target damage.

  9. Ablation dynamics in laser sclerotomy ab externo

    NASA Astrophysics Data System (ADS)

    Brinkmann, Ralf; Droege, Gerit; Mohrenstecher, Dirk; Scheu, M.; Birngruber, Reginald

    1996-01-01

    Laser sclerostomy ab externo with flashlamp excited mid-IR laser systems emitting in the 2-3 micrometer spectral range is in phase II clinical trials. Although acutely high success rates were achieved, the restenosis rate after several months is about 40%. Laser pulses of several hundreds of microseconds, known to induce thermo-mechanical explosive evaporation were used for this procedure. We investigated the ablation dynamics in tissue and the cavitation bubble dynamics in water by means of an Er:YAG laser system to estimate the extent of mechanical damage zones in the sclera and in the anterior chamber, which may contribute to the clinical failure. We found substantial mechanical tissue deformation during the ablation process caused by the cavitation effects. Stress waves up to several bar generated by explosive evaporization were measured. The fast mechanical stretching and collapsing of the scleral tissue induced by cavitation resulted in tissue dissection as could be proved by flash photography and histology. The observed high restenosis might be a result of a subsequent enhanced wound healing process. Early fistula occlusions due to iris adherences, observed in about 20% of the clinical cases may be attributed to intraocular trauma induced by vapor bubble expansion through the anterior chamber after scleral perforation. An automatic feedback system minimizing adverse effects by steering and terminating the laser process during scleral fistulization is demonstrated. Moreover, a new approach in laser sclerostomy ab externo is presented using a cw-IR laser diode system emitting at the 1.94 micrometer mid-IR water absorption peak. This system was used in vitro and showed smaller damage zones compared to the pulsed laser radiation.

  10. [Transarterial ablation of hepatocellular carcinoma. Status and developments].

    PubMed

    Radeleff, B A; Stampfl, U; Sommer, C M; Bellemann, N; Hoffmann, K; Ganten, T; Ehehalt, R; Kauczor, H U

    2012-01-01

    Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and represents the main cause of death among European patients with liver cirrhosis. Only 30-40% of patients diagnosed with HCC are candidates for curative treatment options (e.g. surgical resection, liver transplantation or ablation). The remaining majority of patients must undergo local regional and palliative therapies. Transvascular ablation of HCC takes advantage of the fact that the hypervascularized HCC receives most of its blood supply from the hepatic artery. In this context transvascular ablation describes different therapy regimens which can be assigned to four groups: cTACE (conventional transarterial chemoembolization), bland embolization (transarterial embolization TAE), DEB-TACE (TACE with drug-eluting beads, DEB) and SIRT (selective internal radiation therapy, radioembolization). Conventional TACE is the most common type of transvascular ablation and represents a combination of intra-arterial chemotherapy and embolization with occlusion of the arterial blood supply. However, there is no standardized regimen with respect to the chemotherapeutic drug, the embolic agent, the usage of lipiodol and the interval between the TACE procedures. Even the exact course of a cTACE procedure (order of chemotherapy or embolization) is not standardized. It remains unclear whether or not intra-arterial chemotherapy is definitely required as bland embolization using very small, tightly calibrated spherical particles (without intra-arterial administration of a chemotherapeutic drug) shows tumor necrosis comparable to cTACE. For DEB-TACE microparticles loaded with a chemotherapeutic drug combine the advantages of cTACE and bland embolization. Thereby, a continuing chemotherapeutic effect within the tumor might cause a further increase in intratumoral cytotoxicity and at the same time a decrease in systemic toxicity. PMID:22249701

  11. Laser Ablation Propulsion A Study

    NASA Astrophysics Data System (ADS)

    Irfan, Sayed A.; Ugalatad, Akshata C.

    Laser Ablation Propulsion (LAP) will serve as an alternative propulsion system for development of microthrusters. The principle of LAP is that when a laser (pulsed or continuous wave) with sufficient energy (more than the vaporization threshold energy of material) is incident on material, ablation or vaporization takes place which leads to the generation of plasma. The generated plasma has the property to move away from the material hence pressure is generated which leads to the generation of thrust. Nowadays nano satellites are very common in different space and defence applications. It is important to build micro thruster which are useful for orienting and re-positioning small aircraft (like nano satellites) above the atmosphere. modelling of LAP using MATLAB and Mathematica. Schematic is made for the suitable optical configuration of LAP. Practical experiments with shadowgraphy and self emission techniques and the results obtained are analysed taking poly (vinyl-chloride) (PVC) as propellant to study the

  12. Laser Ablation Molecular Isotopic Spectrometry

    NASA Astrophysics Data System (ADS)

    Russo, Richard E.; Bol'shakov, Alexander A.; Mao, Xianglei; McKay, Christopher P.; Perry, Dale L.; Sorkhabi, Osman

    2011-02-01

    A new method of performing optical isotopic analysis of condensed samples in ambient air and at ambient pressure has been developed: Laser Ablation Molecular Isotopic Spectrometry (LAMIS). The technique uses radiative transitions from molecular species either directly vaporized from a sample or formed by associative mechanisms of atoms or ions in a laser ablation plume. This method is an advanced modification of a known atomic emission technique called laser-induced breakdown spectroscopy (LIBS). The new method — LAMIS — can determine not only chemical composition but also isotopic ratios of elements in the sample. Isotopic measurements are enabled by significantly larger isotopic shifts found in molecular spectra relative to atomic spectra. Analysis can be performed from a distance and in real time. No sample preparation or pre-treatment is required. Detection of the isotopes of hydrogen, boron, carbon, and oxygen are discussed to illustrate the technique.

  13. Electron Beam Ablation and Deposition

    NASA Astrophysics Data System (ADS)

    Kovaleski, S. D.; Gilgenbach, R. M.; Ang, L. K.; Lau, Y. Y.

    1997-11-01

    Ablation of fused silica, titanium nitride, and boron nitride with a channel spark electron beam is being studied. The channel spark is a low energy (15-20kV), high current (1600A) electron beam source developed at KFK(G. Muller and C. Schultheiss, Proc. of Beams `94, Vol. II, p833). This is a pseudospark device which operates in the ion focused regime of electron beam transport. For this reason, a low pressure (10-15mTorr of Ar) background gas is used to provide electron beam focusing. Plume composition and excitation has been studied via optical emission spectroscopy. Ablation has also been imaged photographically. Electron density gradients and densities are being studied through laser deflection. Film deposition experiments are also being performed. Electron transport and energy deposition in metals are being simulated in the ITS-TIGER code(Sandia Report No. SAND 91-1634).

  14. Artificial meteor ablation studies: Olivine

    NASA Technical Reports Server (NTRS)

    Blanchard, M. B.; Cunningham, G. G.

    1973-01-01

    Artificial meteor ablation was performed on a Mg-rich olivine sample using an arc-heated plasma of ionized air. Experimental conditions simulated a meteor traveling about 12 km/sec at an altitude of 70 km. The mineral content of the original olivine sample was 98% olivine (including traces of olivine alteration products) and 2% chromite. Forsterite content of the original olivine was Fo-89. After ablation, the forsterite content had increased to Fo-94 in the recrystallized olivine. In addition, lamella-like intergrowths of magnetite were prevalent constituents. Wherever magnetite occurred, there was an increase in Mg and a corresponding decrease in Fe for the recrystallized olivine. The Allende fusion crust consisted of a recrystallized olivine, which was more Mg-rich and Fe-deficient than the original meteorite's olivine, and abundant magnetite grains. Although troilite and pentlandite were the common opaque mineral constituents in this meteorite, magnetite was the principal opaque mineral found in the fusion crust.

  15. Radiofrequency catheter septal ablation for hypertrophic obstructive cardiomyopathy in children

    PubMed Central

    Emmel, M.; Sreeram, N.

    2005-01-01

    Background The definitive therapeutic options for symptomatic obstructive cardiomyopathy in childhood are restricted. At present, extensive surgical myectomy is the only procedure that is of proven benefit. Patients and Methods Three patients, aged 5, 11 and 17 years, respectively, with progressive hypertrophic obstructive cardiomyopathy and increasing symptoms were considered for radiofrequency catheter septal ablation. The peak Doppler gradient recorded on several occasions ranged between 50 to 90mmHg. Via a femoral arterial approach, the His bundle was initially plotted and marked using the LocaLisa navigation system. Subsequently, using a cooled tip catheter a series of lesions were placed in the hypertrophied septum, taking care to stay away from the His bundle. A total of 17, 50 and 45 lesions were applied in the three patients. In one case, the procedure was complicated by two episodes of ventricular fibrillation requiring DC cardioversion but without any neurological sequelae. Results The preablation peak-to-peak gradient between left ventricle and aorta was 50 mmHg, 60 mmHg and 60 mmHg, respectively, and remained unchanged immediately after the procedure. All patients were discharged from hospital 48 hours later. Serial measurement of serum troponin T and CK-MB isoenzyme confirmed significant myocardial necrosis. Follow-up echocardiography both at seven days and at six weeks postablation confirmed a beneficial haemodynamic result, with reduction of left ventricular outflow obstruction and relief of symptoms. Conclusion In young children, in whom alcohol-induced septal ablation is not an option, radiofrequency catheter ablation offers an alternative to surgery, with the benefits of repeatability and a lower risk of procedure-related permanent AV block. ImagesFigure 1Figure 2Figure 3Figure 4 PMID:25696442

  16. Caries selective ablation: the handpiece

    NASA Astrophysics Data System (ADS)

    Hennig, Thomas; Rechmann, Peter; Holtermann, Andreas

    1995-05-01

    Caries selective ablation is fixed to a window of fluences predicted by the ablation thresholds of carious and healthy dentin, respectively. The aim of the study was to develop a dental handpiece which guarantees homogeneous fluence at the irradiated tooth surface. Furthermore the point of treatment should be cooled down without energy losses due to the cooling system. We suggest the direct coupling of the laser radiation into a laminar stream of liquid, which acts in turn as a lengthened beam guide. The impacts of the laser radiation and of the cooling medium fall exactly into the same point. Hot ablation debris is removed out of the crater by the flush of the water jet. Fluences are constant if the handpiece is used in contact mode or at a distance. Normally the surface of a bare fiber working in contact mode is destroyed after a few shots. Coupling the laser radiation into a stream of liquid prevents this destruction. Putting together the benefits of this special handpiece short overall treatment times seem to be possible. High average power can be applied to the tooth without the threat of thermal damage. Furthermore no time consuming cutting of the fiber prolongs the treatment time.

  17. Excimer laser ablation of ferrites

    NASA Astrophysics Data System (ADS)

    Tam, A. C.; Leung, W. P.; Krajnovich, D.

    1991-02-01

    Laser etching of ferrites was previously done by scanning a focused continuous-wave laser beam on a ferrite sample in a chemical environment. We study the phenomenon of photo-ablation of Ni-Zn or Mn-Zn ferrites by pulsed 248-nm KrF excimer laser irradiation. A transfer lens system is used to project a grating pattern of a mask irradiated by the pulsed KrF laser onto the ferrite sample. The threshold fluence for ablation at the ferrite surface is about 0.3 J/cm2. A typical fluence of 1 J/cm2 is used. The etched grooves produced are typically 20-50 μm wide, with depths achieved as deep as 70 μm . Groove straightness is good as long as a sharp image is projected onto the sample surface. The wall angle is steeper than 60 degrees. Scanning electron microscopy of the etched area shows a ``glassy'' skin with extensive microcracks and solidified droplets being ejected that is frozen in action. We found that this skin can be entirely removed by ultrasonic cleaning. A fairly efficient etching rate of about 10 nm/pulse for a patterned area of about 2 mm×2 mm is obtained at a fluence of 1 J/cm2. This study shows that projection excimer laser ablation is useful for micromachining of ferrite ceramics, and indicates that a hydrodynamic sputtering mechanism involving droplet emission is a cause of material removal.

  18. 60 FR 11194 - Real Estate Settlement Procedures Act (Regulation X); Escrow Accounting Procedures

    Federal Register 2010, 2011, 2012, 2013, 2014

    1995-03-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOUSING AND URBAN DEVELOPMENT Office of the Assistant Secretary for Housing-Federal Housing Commissioner 24 CFR Part 3500 RIN 2502-AF77 Real Estate Settlement Procedures Act (Regulation X); Escrow Accounting...

  19. [Long-term results of low-speed irrigated radiofrequency catheter ablation of atrial flutter].

    PubMed

    Ardashev, V N; Ardashev, A V; Novichkov, S A; Konev, A V; Voloshko, S V; Shavarov, A A

    2007-01-01

    The authors studied long-term results of low-speed (10 ml/min) irrigated radiofrequency catheter ablation (RFA) of the lower isthmus (LI) in patients with typical atrial flutter (AF). This treatment was based upon combined use of local and indirect criteria of the block of isthmus conduction. The influence of RFA LI on quality of life (QL), echocardiographic parameters and cardiac rhythm variability (CRV) was studied. Low-speed irrigated RFA LI, based upon combined use of local and indirect criteria for verification of complete bidirectional blockade in this area, is an effective and safe method of treatment of patients with different variants of clinical course of typical AF which makes it possible to significantly improve QL characteristics and central hemodynamic parameters, and normalize CVR parameters as well. Self-organization of chaos, which realizes according to RR interval time rows, in patients with typical AF after RFA LI may be considered an additional criterion of the effectiveness of this operative intervention and a prognostic sign that predicts maintenance of sinus rhythm in this category of patients. PMID:17601035

  20. Image-guided ablation for hepatocellular carcinoma.

    PubMed

    Lencioni, Riccardo; Crocetti, Laura

    2013-01-01

    Image-guided ablation is accepted as the best therapeutic choice for patients with early-stage hepatocellular carcinoma (HCC) when surgical options-including resection and transplantation-are precluded. The term image-guided tumor ablation is defined as the direct application of chemical substances or sources of energy to a focal tumor in an attempt to achieve eradication or substantial tumor destruction. Over the past 25 years, several methods for local tumor destruction have been developed and clinically tested. Radiofrequency ablation (RFA) has shown superior anticancer effect and greater survival benefit with respect to the seminal percutaneous technique, ethanol injection, in meta-analyses of randomized controlled trials, and is currently established as the standard ablative modality. Nevertheless, novel thermal and nonthermal techniques for tumor ablation-including microwave ablation and irreversible electroporation-seem to have potential to improve the efficacy of RFA and are currently undergoing clinical investigation. PMID:22941021

  1. Cholecystokinin-Assisted Hydrodissection of the Gallbladder Fossa during FDG PET/CT-guided Liver Ablation

    SciTech Connect

    Tewari, Sanjit O.; Petre, Elena N.; Osborne, Joseph; Sofocleous, Constantinos T.

    2013-12-15

    A 68-year-old female with colorectal cancer developed a metachronous isolated fluorodeoxyglucose-avid (FDG-avid) segment 5/6 gallbladder fossa hepatic lesion and was referred for percutaneous ablation. Pre-procedure computed tomography (CT) images demonstrated a distended gallbladder abutting the segment 5/6 hepatic metastasis. In order to perform ablation with clear margins and avoid direct puncture and aspiration of the gallbladder, cholecystokinin was administered intravenously to stimulate gallbladder contraction before hydrodissection. Subsequently, the lesion was ablated successfully with sufficient margins, of greater than 1.0 cm, using microwave with ultrasound and FDG PET/CT guidance. The patient tolerated the procedure very well and was discharged home the next day.

  2. Basket catheter-guided three-dimensional activation patterns construction and ablation of common type atrial flutter.

    PubMed

    Zrenner, B; Ndrepepa, G; Schneider, M; Karch, M; Deisenhofer, I; Schreieck, J; Schömig, A; Schmitt, C

    2000-09-01

    Construction of three-dimensional activation maps and evaluation of ablation-created bidirectional block in the tricuspid valve-inferior vena caval (TV-IVC) isthmus in patients with atrial flutter (AF) are difficult with conventional mapping technique. In 36 patients with type I AF (25 men, 11 women; mean age 62 +/- 10.5 years) a multielectrode basket catheter (BC) was deployed in the right atrium (RA). Out of 64 BC electrodes, 56 bipolar electrograms were derived. Three-dimensional activation patterns were constructed with a software program. Stable electrograms of satisfactory quality were obtained in 49 +/- 2 electrode pairs. Capture was possible in 36 +/- 3 of bipoles. In counterclockwise AF (CCW-AF) and clockwise AF (CW-AF) episodes, cycle lengths and TV-IVC isthmus conduction times were 248 +/- 26 ms and 251 +/- 23 ms, (P = 0.74) and 105 +/- 28 ms and 106 +/- 33 ms (P = 0.92), respectively. Conduction velocity in the TV-IVC isthmus was lower than in the anterior or septal limbs of the circuit, in counterclockwise or clockwise episodes. Double potentials were recorded in 94% of patients. Three-dimensional activation patterns were delineated and displayed as isochronal maps. The reentry circuit involved the TV-IVC isthmus, septal, and anterior walls and a part of the RA roof anterior to superior vena cava. Postablation isthmus conduction was evaluated through the sequence criteria, local electrogram-based criteria, and the analysis of three-dimensional activation patterns of the paced rhythms. The complete isthmus block was associated with a significant increase of the low anterior low septal conduction interval (152 +/- 29 vs 104 +/- 32 ms, P = 0.001) and the low septal-low anterior conduction interval (150 +/- 31 vs 107 +/- 33 ms, P = 0.001). Radiofrequency ablation was successful in 32 (90%) of 36 patients. In conclusion, the current mapping system enables construction of three-dimensional activation patterns and facilitates evaluation of the postablation TV

  3. Efficacy comparison between cryoablation and radiofrequency ablation for patients with cavotricuspid valve isthmus dependent atrial flutter: a meta-analysis.

    PubMed

    Chen, Yi-He; Lin, Hui; Xie, Cheng-Long; Zhang, Xiao-Ting; Li, Yi-Gang

    2015-01-01

    We perform this meta-analysis to compare the efficacy and safety of cryoablation versus radiofrequency ablation for patients with cavotricuspid valve isthmus dependent atrial flutter. By searching EMBASE, MEDLINE, PubMed and Cochrane electronic databases from March 1986 to September 2014, 7 randomized clinical trials were included. Acute (risk ratio[RR]: 0.93; P = 0.14) and long-term (RR: 0.94; P = 0.08) success rate were slightly lower in cryoablation group than in radiofrequency ablation group, but the difference was not statistically significant. Additionally, the fluoroscopy time was nonsignificantly reduced (weighted mean difference[WMD]: -2.83; P = 0.29), whereas procedure time was significantly longer (WMD: 25.95; P = 0.01) in cryoablation group compared with radiofrequency ablation group. Furthermore, Pain perception during the catheter ablation was substantially less in cryoablation group than in radiofrequency ablation group (standardized mean difference[SMD]: -2.36; P < 0.00001). Thus, our meta-analysis demonstrated that cryoablation and radiofrequency ablation produce comparable acute and long-term success rate for patients with cavotricuspid valve isthmus dependent atrial flutter. Meanwhile, cryoablation ablation tends to reduce the fluoroscopy time and significantly reduce pain perception in cost of significantly prolonged procedure time. PMID:26039980

  4. Efficacy comparison between cryoablation and radiofrequency ablation for patients with cavotricuspid valve isthmus dependent atrial flutter: a meta-analysis

    NASA Astrophysics Data System (ADS)

    Chen, Yi-He; Lin, Hui; Xie, Cheng-Long; Zhang, Xiao-Ting; Li, Yi-Gang

    2015-06-01

    We perform this meta-analysis to compare the efficacy and safety of cryoablation versus radiofrequency ablation for patients with cavotricuspid valve isthmus dependent atrial flutter. By searching EMBASE, MEDLINE, PubMed and Cochrane electronic databases from March 1986 to September 2014, 7 randomized clinical trials were included. Acute (risk ratio[RR]: 0.93; P = 0.14) and long-term (RR: 0.94; P = 0.08) success rate were slightly lower in cryoablation group than in radiofrequency ablation group, but the difference was not statistically significant. Additionally, the fluoroscopy time was nonsignificantly reduced (weighted mean difference[WMD]: -2.83 P = 0.29), whereas procedure time was significantly longer (WMD: 25.95; P = 0.01) in cryoablation group compared with radiofrequency ablation group. Furthermore, Pain perception during the catheter ablation was substantially less in cryoabaltion group than in radiofrequency ablation group (standardized mean difference[SMD]: -2.36 P < 0.00001). Thus, our meta-analysis demonstrated that cryoablation and radiofrequency ablation produce comparable acute and long-term success rate for patients with cavotricuspid valve isthmus dependent atrial flutter. Meanwhile, cryoablation ablation tends to reduce the fluoroscopy time and significantly reduce pain perception in cost of significantly prolonged procedure time.

  5. Effects of Iron Depletion on CALM-AF10 Leukemias

    PubMed Central

    Heath, Jessica L.; Weiss, Joshua M.

    2014-01-01

    Iron, an essential nutrient for cellular growth and proliferation, enters cells via clathrin-mediated endocytosis (CME). The clathrin assembly lymphoid myeloid (CALM) protein plays an essential role in the cellular import of iron by CME. CALM-AF10 leukemias harbor a single copy of the normal CALM gene, and may therefore be more sensitive to the growth inhibitory effect of iron restriction compared with normal hematopoietic cells. We found that Calm heterozygous (CalmHET) murine fibroblasts exhibit signs of iron deficiency, with increased surface transferrin receptor (sTfR) levels and reduced growth rates. CalmHET hematopoietic cells are more sensitive in vitro to iron chelators than their wild type counterparts. Iron chelation also displayed toxicity towards cultured CalmHET CALM-AF10 leukemia cells and this effect was additive to that of chemotherapy. In mice transplanted with CalmHET CALM-AF10 leukemia, we found that dietary iron restriction reduces tumor burden in the spleen. However, dietary iron restriction, used alone or in conjunction with chemotherapy, did not increase survival of mice with CalmHET CALM-AF10 leukemia. In summary, while Calm heterozygosity results in iron deficiency and increased sensitivity to iron chelation in vitro, our data in mice do not suggest that iron depletion strategies would be beneficial for the therapy of CALM-AF10 leukemia patients. PMID:25193880

  6. Endoscopic radiofrequency ablation for malignant biliary strictures

    PubMed Central

    WANG, FEI; LI, QUANPENG; ZHANG, XIUHUA; JIANG, GUOBING; GE, XIANXIU; YU, HONG; NIE, JUNJIE; JI, GUOZHONG; MIAO, LIN

    2016-01-01

    Endoscopic radiofrequency ablation (RFA) is a novel palliation therapy for malignant biliary stricture; however, its feasibility and safety has not yet been clearly defined. The aim of the present study was to evaluate the feasibility and safety of endoscopic RFA for the treatment of malignant biliary strictures. A total of 12 patients treated by endoscopic RFA between December 2011 and October 2013 were retrospectively analyzed. Adverse events within 30 days post-intervention, stricture diameters prior to and following RFA, stent patency and survival time were investigated. A total of 12 patients underwent 20 RFA procedures as a treatment for malignant biliary strictures. Two patients required repeated elective RFA (4 and 6 times, respectively). All 20 RFA procedures were successfully performed without technical problems. During a 30 day period following each RFA procedure, two patients experienced fever (38.2 and 38.9°C, respectively) and another patient exhibited post-endoscopic retrograde cholangiopancreatography pancreatitis. The 30- and 90-day mortality rates were 0 and 8.3%, respectively. Mean stricture diameter prior to RFA was 5.3 mm (standard deviation (SD), 0.9 mm; range, 5–8 mm), and the mean diameter following RFA was 12.6 mm (SD, 3.1 mm; range, 8–15 mm). There was a significant increase of 7.3 mm in the bile duct diameter following RFA in comparison with prior to RFA (t=8.6; P≤0.001). Of the 11 patients with stents inserted following RFA, the median stent patency was 125.0 days [95% confidence interval (CI), 94.7–155.3 days]. Extrapolated median survival following the first RFA was 232 days (95% CI, 94.3–369.7 days). In conclusion, RFA appears to be an efficient and safe treatment strategy for the palliation of unresectable malignant biliary strictures. PMID:27284336

  7. Laser Ablation of Alumina in Water

    SciTech Connect

    Musaev, O.; Midgley, A; Wrobel, J; Kruger, M

    2010-01-01

    Bulk {alpha}-alumina immersed in distilled water was ablated by pulsed UV laser radiation. The resulting colloidal solution contained micron and submicron size particles. X-ray diffraction and Raman spectra of the ablated and original material are similar. Hence, most of the ablated material is {alpha}-alumina. From transmission electron microscope images, most of the submicron and all of the micron-sized particles have sharp edges and do not have spherical shapes, indicating that the dominant ablation mechanism is due to crack propagation. Some spherical particles of diameter less than 100 nm are observed, indicating that they were formed from the liquid state.

  8. Ablative therapies in renal cell carcinoma.

    PubMed

    Chan, A A; Ahrar, K; Matin, S F

    2011-09-01

    We reviewed the use of ablative therapies in the management of renal cell carcinoma. We performed a PubMed search of the English language literature using the keywords "ablation" and "renal carcinoma." Pertinent articles specific to the technologic advancement of ablative therapy and clinical outcomes were selected for review. Intermediate-term oncologic outcomes of cryoablation and radiofrequency ablation are acceptable but are not quite as good as for surgical excision based nearly all on retrospective studies. No randomized studies have been performed comparing excisional and ablative therapies. Careful selection of patients and tumor characteristics results in improved outcomes. Diagnostic biopsy for tissue confirmation is mandatory and should even be considered post therapy after 6-12 months in patients with a concern about recurrence. Ablative therapies are associated with decreased morbidity, less severe complication rates, and excellent preservation of renal function in comparison with surgical excision. The majority of recurrences occur early, but long-term surveillance is required as delayed recurrences are also possible and the long-term oncologic efficacy is not yet established. Ablation can be delivered percutaneously or laparoscopically, and the superiority of one over the other remains controversial. The percutaneous approach is more cost effective and causes less perinephric desmoplasia. Nearly all data on ablation are retrospective and, with few exceptions, from single institutions. Ablative therapy is an appealing option for the management of small renal tumors shown to be renal cell carcinoma on biopsy in patients who are unsuitable candidates for surgical extirpation. PMID:21993322

  9. Plasma-mediated ablation of biofilm contamination

    NASA Astrophysics Data System (ADS)

    Guo, Zhixiong; Wang, Xiaoliang; Huang, Huan

    2010-12-01

    Ultra-short pulsed laser removal of thin biofilm contamination on different substrates has been conducted via the use of plasma-mediated ablation. The biofilms were formed using sheep whole blood. The ablation was generated using a 1.2 ps ultra-short pulsed laser with wavelength centered at 1552 nm. The blood contamination was transformed into plasma and collected with a vacuum system. The single line ablation features have been measured. The ablation thresholds of blood contamination and bare substrates were determined. It is found that the ablation threshold of the blood contamination is lower than those of the beneath substrates including the glass slide, PDMS, and human dermal tissues. The ablation effects of different laser parameters (pulse overlap rate and pulse energy) were studied and ablation efficiency was measured. Proper ablation parameters were found to efficiently remove contamination with maximum efficiency and without damage to the substrate surface for the current laser system. Complete removal of blood contaminant from the glass substrate surface and freeze-dried dermis tissue surface was demonstrated by the USP laser ablation with repeated area scanning. No obvious thermal damage was found in the decontaminated glass and tissue samples.

  10. [Radiofrequency ablation in tachycardias due to accessory pathways in a pediatric population].

    PubMed

    Iturralde, P; Saucedo, J; Colín, L; Kershenovich, S; Robledo, R; Garrido, A; González-Hermosillo, J A; Buendía, A

    1994-01-01

    Catheter ablation of accessory atrioventricular pathways using radiofrequency current was attempted in 61 children and young adolescents less than 18 years of age who were referred for treatment of symptomatic supraventricular tachycardia. Thirty-three children had the Wolff-Parkinson-White syndrome and 30 tachyarrhythmias related to an accessory pathway conducting only in retrograde fashion. Ablation of left sided accessory pathways was usually attempted utilizing an arterial approach to the annulus of the mitral valve, only in one case we used the transseptal approach, while the venous route to the atrial aspect of the tricuspid valvular annulus was chosen for right sided accessory connections. Ablation of 55 of 63 accessory connections was achieved (87% success) with a range of 1 to 42 applications of radiofrequency current. The sessions were completed within 19 to 180 minutes, and we used within 16 to 45 watts of radiofrequency current. Two patients had complications as a result of their ablation procedure. One patient had complete heart block but did not require pacemaker implantation, and other one had mitral regurgitation. A second session was necessary in three patients, two of three accessory pathways were ablated, giving a success rate of 90%. During a one year period of follow-up, we had 4 recurrences (7.2%). Catheter ablation using radiofrequency current is a highly effective and safe curative approach for treating young patients with supraventricular tachycardia mediated by accessory pathways. PMID:7840718

  11. Catheter ablation for ventricular tachyarrhythmias in patients supported by continuous-flow left ventricular assist devices.

    PubMed

    Garan, Arthur R; Iyer, Vivek; Whang, William; Mody, Kanika P; Yuzefpolskaya, Melana; Colombo, Paolo C; Te-Frey, Rosie; Takayama, Hiroo; Naka, Yoshifumi; Garan, Hasan; Jorde, Ulrich P; Uriel, Nir

    2014-01-01

    Ventricular arrhythmias (VAs) are common after implantation of a left ventricular assist device (LVAD) and in a subset of patients may be refractory to medication. Morbidity from VA in this population includes right ventricular failure (RVF). We sought to evaluate the efficacy of catheter ablation for VA in patients with LVAD. A retrospective analysis of patients supported by continuous-flow LVAD referred for catheter ablation of ventricular tachycardia (VT) between 2008 and the present was performed. Seven patients were referred for VT ablation an average of 236 ± 292 days after LVAD implantation. Three patients (42.9%) developed RVF in the setting of intractable arrhythmias. A transfemoral approach was used for six patients (85.7%) and an epicardial for one patient (14.3%). The clinical VT was inducible and successfully ablated in six patients (85.7%). The location of these arrhythmias was apical in three cases (42.9%). A total of 13 VTs were ablated in seven patients. Although the majority had reduction in VA frequency, recurrent VAs were observed in six patients (85.7%). One patient (14.3%) experienced a bleeding complication after the procedure. For patients with a high VA burden after LVAD implantation, VT ablation is safe and feasible, but VA frequently recurs. PMID:24614361

  12. Conjunction of Endocardial and Coronary Venous System Mapping to Ablate Ventricular Arrhythmias

    PubMed Central

    Wo, Hung-Ta; Yeh, Jih-Kai; Chang, Po-Cheng; Wen, Ming-Shien; Wang, Chun-Chieh; Chou, Chung-Chuan; Yeh, San-Jou

    2016-01-01

    Background Ablation of idiopathic ventricular arrhythmias (VAs) with epicardial or intramural origins is technically challenging. Herein, we have described the successful ablation of left VAs via the coronary venous system (CVS) in conjunction with endocardial map guided by three-dimensional electroanatomical map in six patients. Methods Out of a total consecutive 84 patients with symptomatic idiopathic VAs, radiofrequency ablation via the CVS was performed on six patients (7%). Furthermore, we reviewed patient records and electrophysiologic studies with respect to clinical characteristics. Results Activation map was conducted in 5 patients, and the earliest activation sites were identified within the CVS. The preceding times to the onset of QRS complex were longer than those at the earliest endocardial sites (36.2 ± 5.6 ms vs. 14.2 ± 6.4 ms, p = 0.02, n = 5). Spiky fractionated long-duration potentials were recorded at the successful ablation sites in all 5 patients. The other patient received pacemapping only because of few spontaneous VAs during the procedure, and the best pacemap spot was found within the CVS. Irrigated catheters were required in 4 out of 6 patients because VAs were temporarily suppressed with regular ones. Conclusions Idiopathic VAs can be ablated via the CVS in conjunction with endocardial mapping. Additionally, spiky fractionated long-duration potential can function as a clue to identify the good ablation site.

  13. Laser ablation for small hepatocellular carcinoma: State of the art and future perspectives

    PubMed Central

    Di Costanzo, Giovan Giuseppe; Francica, Giampiero; Pacella, Claudio Maurizio

    2014-01-01

    During the last two decades, various local thermal ablative techniques for the treatment of unresectable hepatocellular carcinoma (HCC) have been developed. According to internationally endorsed guidelines, percutaneous thermal ablation is the mainstay of treatment in patients with small HCC who are not candidates for surgical resection or transplantation. Laser ablation (LA) represents one of currently available loco-ablative techniques. In this article, the general principles, technique, image guidance, and patient selection are reported. Primary effectiveness, long-term outcome, and complications are also discussed. A review of published data suggests that LA is equivalent to the more popular and widespread radiofrequency ablation in both local tumor control and long-term outcome in the percutaneous treatment of early HCC. In addition, the LA technique using multiple thin laser fibres allows improved ablative effectiveness in HCCs greater than 3 cm. Reference centres should be equipped with all the available techniques so as to be able to use the best and the most suitable procedure for each type of lesion for each patient. PMID:25349642

  14. Ultrasound-Guided Percutaneous Radiofrequency Ablation of Liver Tumors: How We Do It Safely and Completely.

    PubMed

    Kim, Jin Woong; Shin, Sang Soo; Heo, Suk Hee; Hong, Jun Hyung; Lim, Hyo Soon; Seon, Hyun Ju; Hur, Young Hoe; Park, Chang Hwan; Jeong, Yong Yeon; Kang, Heoung Keun

    2015-01-01

    Ultrasound-guided percutaneous radiofrequency (RF) ablation has become one of the most promising local cancer therapies for both resectable and nonresectable hepatic tumors. Although RF ablation is a safe and effective technique for the treatment of liver tumors, the outcome of treatment can be closely related to the location and shape of the tumors. There may be difficulties with RF ablation of tumors that are adjacent to large vessels or extrahepatic heat-vulnerable organs and tumors in the caudate lobe, possibly resulting in major complications or treatment failure. Thus, a number of strategies have been developed to overcome these challenges, which include artificial ascites, needle track ablation, fusion imaging guidance, parallel targeting, bypass targeting, etc. Operators need to use the right strategy in the right situation to avoid the possibility of complications and incomplete thermal tissue destruction; with the right strategy, RF ablation can be performed successfully, even for hepatic tumors in high-risk locations. This article offers technical strategies that can be used to effectively perform RF ablation as well as to minimize possible complications related to the procedure with representative cases and schematic illustrations. PMID:26576111

  15. Radio Frequency Ablation for Primary Liver Cancer

    PubMed Central

    2004-01-01

    Executive Summary Objective The Medical Advisory Secretariat undertook a review of the evidence on the safety, clinical effectiveness, and cost-effectiveness of radio frequency ablation (RFA) compared with other treatments for unresectable hepatocellular carcinoma (HCC) in Ontario. Background Liver cancer is the fifth most common type of cancer globally, although it is most prevalent in Asia and Africa. The incidence of liver cancer has been increasing in the Western world, primarily because of an increased prevalence of hepatitis B and C. Data from Cancer Care Ontario from 1998 to 2002 suggest that the age-adjusted incidence of liver cancer in men rose slightly from 4.5 cases to 5.4 cases per 100,000 men. For women, the rates declined slightly, from 1.8 cases to 1.4 cases per 100,000 women during the same period. Most people who present with symptoms of liver cancer have a progressive form of the disease. The rates of survival in untreated patients in the early stage of the disease range from 50% to 82% at 1 year and 26% to 32% at 2 years. Patients with more advanced stages have survival rates ranging from 0% to 36% at 3 years. Surgical resection and transplantation are the procedures that have the best prognoses; however, only 15% to 20% of patients presenting with liver cancer are eligible for surgery. Resection is associated with a 50% survival rate at 5 years. The Technology: Radio Frequency Ablation RFA is a relatively new technique for the treatment of small liver cancers that cannot be treated with surgery. This technique applies alternating high-frequency electrical currents to the cancerous tissue. The intense heat leads to thermal coagulation that can kill the tumour. RFA is done under general or local anesthesia and can be done percutaneously (through the skin with a small needle), laparoscopically (microinvasively, using a small video camera), or intraoperatively. Percutaneous RFA is usually a day procedure. Methods The leading international

  16. Optimization of Direct Current-Enhanced Radiofrequency Ablation: An Ex Vivo Study

    SciTech Connect

    Tanaka, Toshihiro Isfort, Peter; Bruners, Philipp; Penzkofer, Tobias; Kichikawa, Kimihiko; Schmitz-Rode, Thomas; Mahnken, Andreas H.

    2010-10-15

    The purpose of this study was to investigate the optimal setting for radiofrequency (RF) ablation combined with direct electrical current (DC) ablation in ex vivo bovine liver. An electrical circuit combining a commercially available RF ablation system with DC was developed. The negative electrode of a rectifier that provides DC was connected to a 3-cm multitined expandable RF probe. A 100-mH inductor was used to prevent electrical leakage from the RF generator. DC was applied for 15 min and followed by RF ablation in freshly excised bovine livers. Electric current was measured by an ammeter. Coagulation volume, ablation duration, and mean amperage were assessed for various DC voltages (no DC, 2.2, 4.5, and 9.0 V) and different RF ablation protocols (stepwise increase from 40 to 80 W, 40 W fixed, and 80 W fixed). Results were compared using Kruskal-Wallis and Mann-Whitney U test. Applying DC with 4.5 or 9.0 V, in combination with 40 W fixed or a stepwise increase of RF energy, resulted in significantly increased zone of ablation size compared with 2.2 V or no DC (P = 0.009). At 4.5 V DC, the stepwise increase of RF energy resulted in the same necrosis size as a 40 W fixed protocol (26.6 {+-} 3.9 vs. 26.5 {+-} 4.0 ml), but ablation duration was significantly decreased (296 {+-} 85 s vs. 423 {+-} 104 s; P = 0.028). Mean amperage was significantly lower at 4.5 V compared with 9.0 V (P = 0.028). Combining a stepwise increase of RF energy with a DC voltage of 4.5 V is most appropriate to increase coagulation volume and to minimize procedure time.

  17. Geographic Variation in the Use of Catheter Ablation for Atrial Fibrillation Among Medicare Beneficiaries

    PubMed Central

    Greiner, Melissa A.; Walkey, Allan J.; Wallace, Erin R.; Heckbert, Susan R.; Benjamin, Emelia J.; Curtis, Lesley H.

    2015-01-01

    Background Catheter ablation for atrial fibrillation is used increasingly in older patients, yet the risks and benefits are not completely understood. With such uncertainty, local medical opinion may influence catheter ablation use. Methods In a 100% sample of Medicare beneficiaries 65 years or older who underwent catheter ablation for atrial fibrillation between January 1, 2007, and December 31, 2009, we investigated variation in use by hospital referral region (HRR) for 20,176 catheter ablation procedures. Results Across 274 HRRs, median age was 71.2 years (interquartile range, 70.5-71.8), a median of 98% of patients were white, and a median of 39% of patients were women. The median age-standardized prevalence of atrial fibrillation was 77.1 (69.4-84.2) per 1000 beneficiaries; the median rate of catheter ablation was 3.5 (2.4-4.9) per 1000 beneficiaries. We found no significant associations between the rate of catheter ablation and prevalence of atrial fibrillation (P = 0.99), end-of-life Medicare expenditures per capita (P = 0.09), or concentration of cardiologists (P = 0.45), but a slight association with Medicare expenditures per capita (linear regression estimate, 0.016; 95% CI, 0.001-0.031; P = 0.04). Examined HRR characteristics explained only 2% of the variation in HRR-level rates of catheter ablation (model R2 = 0.016). Conclusion The rate of catheter ablation for atrial fibrillation in older patients was low, varied substantially by region, and was not associated with the prevalence of atrial fibrillation, the availability of cardiologists, or end-of-life resource use, and was only slightly associated with overall Medicare expenditures per capita. PMID:26027614

  18. Management of the Temporomandibular Joint after Ablative Surgery

    PubMed Central

    Bredell, Marius; Grätz, Klaus; Obwegeser, Joachim; Gujer, Astrid Kruse

    2014-01-01

    Management of the temporomandibular joint in ablative head and neck surgery is controversial with no standardized approach. The aim of the study was to establish risk-based guidelines for the management of the temporomandibular joint after ablative surgery. Analysis of all patients' records receiving ablative surgery involving the temporomandibular joint in the Department of Cranio-Maxillofacial and Oral Surgery, University Hospital of Zürich, from 2001 to 2012, was performed, identifying 15 patients and 14 reconstructive procedures. A literature search was done identifying all relevant literature on current approaches. Applicable cohorts were constructed, and relevant risks were extrapolated. Evaluated studies are not uniform in their reporting with nonhomogeneous patient groups. A diverse approach is used in the management of these patients with complications such as infection, ankylosis, limited mouth opening, plate penetration in the skull base, and plate loosening. Risk factors for complications appear to be radiation, costochondral graft, disk loss, and plate use alone. Clinical data suggest use of a plate with metal condyle reconstructions and previous radiation therapy as potential risks factors. Employing literature evidence and cumulated clinical data, a risk-based flowchart was developed to assist surgical decision making. Risk factors such as radiation, disk preservation, and soft tissue conditions are important complication-associated factors when planning surgery. Free vascularized fibula grafts appear to have the least complications that must be weighed against donor site morbidity. PMID:25379124

  19. Quality Improvement Guidelines for Radiofrequency Ablation of Liver Tumours

    SciTech Connect

    Crocetti, Laura; Baere, Thierry de; Lencioni, Riccardo

    2010-02-15

    The development of image-guided percutaneous techniques for local tumour ablation has been one of the major advances in the treatment of liver malignancies. Among these methods, radiofrequency ablation (RFA) is currently established as the primary ablative modality at most institutions. RFA is accepted as the best therapeutic choice for patients with early-stage hepatocellular carcinoma (HCC) when liver transplantation or surgical resection are not suitable options [1, 2]. In addition, RFA is considered a viable alternate to surgery (1) for inoperable patients with limited hepatic metastatic disease, especially from colorectal cancer, and (2) for patients deemed ineligible for surgical resection because of extent and location of the disease or concurrent medical conditions [3]. These guidelines were written to be used in quality-improvement programs to assess RFA of HCC and liver metastases. The most important processes of care are (1) patient selection, (2) performing the procedure, and (3) monitoring the patient. The outcome measures or indicators for these processes are indications, success rates, and complication rates.

  20. A system for advanced real-time visualization and monitoring of MR-guided thermal ablations

    NASA Astrophysics Data System (ADS)

    Rothgang, Eva; Gilson, Wesley D.; Hornegger, Joachim; Lorenz, Christine H.

    2010-02-01

    In modern oncology, thermal ablations are increasingly used as a regional treatment option to supplement systemic treatment strategies such as chemotherapy and immunotherapy. The goal of all thermal ablation procedures is to cause cell death of disease tissue while sparing adjacent healthy tissue. Real-time assessment of thermal damage is the key to therapeutic efficiency and safety of such procedures. Magnetic resonance thermometry is capable of monitoring the spatial distribution and temporal evolution of temperature changes during thermal ablations. In this work, we present an advanced monitoring system for MR-guided thermal ablations that includes multiplanar visualization, specialized overlay visualization methods, and additional methods for correcting errors resulting from magnetic field shifts and motion. To ensure the reliability of the displayed thermal data, systematic quality control of thermal maps is carried out on-line. The primary purpose of this work is to provide clinicians with an intuitive tool for accurately visualizing the progress of thermal treatment at the time of the procedure. Importantly, the system is designed to be independent of the heating source. The presented system is expected to be of great value not only to guide thermal procedures but also to further explore the relationship between temperature-time exposure and tissue damage. The software application was implemented within the eXtensible Imaging Platform (XIP) and has been validated with clinical data.

  1. Bacterial infections following non-ablative fractional laser treatment: a case series and discussion.

    PubMed

    Xu, Lisa Y; Kilmer, Suzanne L; Ross, E Victor; Avram, Mathew M

    2015-02-01

    Non-ablative fractional laser procedures have become increasingly popular since their introduction in 2004. The fractional 1,927 nm thulium laser is a non-ablative device that penetrates up to 300 μm in the skin and the 1,550 nm erbium:glass laser penetrates up to 1,400 μm. These procedures are considered minimally invasive with a high safety profile; therefore, infectious complications are exceedingly rare. However, we report five recent cases of bacterial infection with both gram-positive and gram-negative organisms following treatment with the fractional 1550/1927 nm laser approximately 1 day to 1 week post-procedure. One patient had a rapidly progressing pustular eruption with symptoms of sepsis. These patients were seen immediately, cultures were obtained and empiric antibiotic therapy was initiated. They recovered without long-term complications. Rapid-onset bacterial infections following non-ablative laser resurfacing with the 1550/1927 nm laser have not been previously reported in the literature. The infections can progress quickly and lead to serious sequelae, including systemic illness and severe scarring, if not identified and appropriately treated. We present these cases to highlight the importance of close surveillance and when appropriate, rapid intervention, following non-ablative fractional procedures, especially when patients present with atypical symptoms and signs. PMID:25586939

  2. Generalized interactions using virtual tools within the spring framework: probing, piercing, cauterizing and ablating

    NASA Technical Reports Server (NTRS)

    Montgomery, Kevin; Bruyns, Cynthia D.

    2002-01-01

    We present schemes for real-time generalized interactions such as probing, piercing, cauterizing and ablating virtual tissues. These methods have been implemented in a robust, real-time (haptic rate) surgical simulation environment allowing us to model procedures including animal dissection, microsurgery, hysteroscopy, and cleft lip repair.

  3. Reversibility of tachycardia-induced cardiomyopathy after radiofrequency ablation of incessant supraventricular tachycardia in infants.

    PubMed Central

    Sanchez, C.; Benito, F.; Moreno, F.

    1995-01-01

    Tachycardia-induced cardiomyopathy developed in a 3 month old infant with permanent junctional reciprocating tachycardia, which was incessant despite medical treatment. The patient underwent transcatheter radiofrequency ablation. There were no complications and 8 months after the procedure the patient was symptom free without medication. Images PMID:7547032

  4. An animal model for learning Nd:YAG laser ablation of the endometrium.

    PubMed

    Gimpelson, R J; Schomburg, M E; Bagby, M L

    1989-07-01

    Gynecologists must have a good model for practice before performing Nd:YAG laser ablation on humans. The New Zealand white rabbit has been used as a teaching model in courses. Knowing the anatomy and technique enables gynecologists to acquire the skill and dexterity needed to perform this useful procedure. PMID:2769653

  5. Ten-year literature review of global endometrial ablation with the NovaSure® device

    PubMed Central

    Gimpelson, Richard J

    2014-01-01

    This review examines the peer-reviewed literature describing prospective studies that report amenorrhea rates, patient satisfaction, and surgical reintervention rates following the NovaSure® endometrial ablation procedure. A search of the English-language literature published from 2000 to 2011 was conducted using PubMed. Ten prospective studies, six single-arm NovaSure trials, and four randomized controlled trials comparing the NovaSure procedure with other global endometrial ablation modalities met the inclusion criteria and were reviewed. The follow-up periods ranged from 6 to 60 months. Amenorrhea rates for the NovaSure procedure ranged from 30.0% to 75.0%. Patients who reported being satisfied with the NovaSure procedure ranged from 85.0% to 94.0%. In randomized controlled trials with other global endometrial ablation modalities, amenorrhea rates at 12 months with the NovaSure procedure ranged from 43.0% to 56.0%, while other modalities ranged from 8% to 24%. In addition, this manuscript reviews the following: the NovaSure technology; use of the NovaSure procedure in the office setting; intraoperative and postoperative pain; effects on premenstrual syndrome (PMS); dysmenorrhea; special circumstances, including presence of uterine disease, history of cesarean delivery, coagulopathy, or use of anticoagulant medication; post-procedure uterine cavity assessment and cancer risk; contraception and pregnancy; and safety. PMID:24648771

  6. Evaluation of the current radiofrequency ablation systems using axiomatic design theory.

    PubMed

    Zhang, Bing; Moser, Michael A J; Luo, Yigang; Zhang, Edwin M; Zhang, Wenjun

    2014-04-01

    This article evaluates current radiofrequency ablation systems using axiomatic design theory. Due to its minimally invasive procedure, short-time hospital stay, low cost, and tumour metastasis treatment, the radiofrequency ablation technique has been playing an important role in tumour treatment in recent decades. Although the radiofrequency ablation technique has many advantages, some issues still need to be addressed. Among these issues, the two most important are as follows: (1) the size of tumours to be removed (has to be larger than 3 cm in diameter) and (2) cleanness of the removal. Many device solutions have been proposed to address the two issues. However, there is a lack of knowledge regarding the systematic evaluation of these solutions. This article evaluates these systems in terms of their solution principles (or simply called conceptual design in general product design theory) using a design theory called axiomatic design theory. In addition, with the axiomatic design theory, a better conceptual design in terms of its feasibility to cope with incomplete target tissue necrosis from the large size of tumours has been found. The detailed analysis and simulation of the new conceptual design are conducted using finite element approach. The results in this article are proved by the information of animal experiments and clinical practices obtained from the literature. This study thus contributes to the current knowledge to further developments in radiofrequency ablation systems and procedure guidelines for physicians to perform the radiofrequency ablation operation more effectively. PMID:24705341

  7. AF-GEOSpace Version 2.5: Space Environment Software

    NASA Astrophysics Data System (ADS)

    Hilmer, R. V.; Hall, T.; Roth, C.; Ling, A.; Ginet, G. P.; Madden, D.

    2010-12-01

    AF-GEOSpace is a graphics-intensive software program with space environment models and applications developed by the Space Weather Center of Excellence at AFRL. The software addresses a wide range of physical domains, e.g., solar disturbance propagation, geomagnetic field and radiation belt configurations, auroral particle precipitation, and ionospheric scintillation. AF-GEOSpace has become a platform for developing and prototyping space weather visualization products. The new AF-GEOSpace Version 2.5 (release scheduled for 2010) expands on the content of Version 2.1 by including modules addressing the following new topics: (1) energetic proton maps for the South Atlantic Anomaly (from Ginet et al. [2007]), (2) GPS scintillation outage simulation tools, (3) magnetopause location determination (Shue et al. [1998]), (4) a plasmasphere model (Global Core Plasma Model, 2009 version based on Gallagher et al. [2000]), (5) a standard ionospheric model (International Reference Ionosphere 2007), (6) the CAMMICE/MICS model of inner magnetosphere plasma population (based on Roeder et al. [2005]), (7) magnetic field models (e.g., Tsyganenko and Sitnov [2005]), and (8) loading and displaying externally-produced 3D gridded data sets within AF-GEOSpace. Improvements to existing Version 2.1 capabilities include: (1) a 2005 update to the geomagnetic cutoff rigidity model of Smart and Shea [2003], (2) a 2005 update to the ionospheric scintillation Wide-Band Model (WBMOD) of Secan and Bussey [1994], and (3) improved magnetic field flux mapping options for the existing set of AF-GEOSpace radiation belt models. A basic review of these new AF-GEOSpace capabilities will be provided. To obtain a copy of the software, please contact the first author.

  8. AF-GEOSpace Version 2.1 Release

    NASA Astrophysics Data System (ADS)

    Hilmer, R. V.; Ginet, G. P.; Hall, T.; Holeman, E.; Madden, D.; Perry, K. L.; Tautz, M.; Roth, C.

    2006-05-01

    AF-GEOSpace Version 2.1 is a graphics-intensive software program with space environment models and applications developed recently by the Space Weather Center of Excellence at AFRL. A review of new and planned AF-GEOSpace capabilities will be given. The software addresses a wide range of physical domains and addresses such topics as solar disturbance propagation, geomagnetic field and radiation belt configurations, auroral particle precipitation, and ionospheric scintillation. Building on the success of previous releases, AF-GEOSpace has become a platform for the rapid prototyping of automated operational and simulation space weather visualization products and helps with a variety of tasks, including: orbit specification for radiation hazard avoidance; satellite design assessment and post-event anomaly analysis; solar disturbance effects forecasting; determination of link outage regions for active ionospheric conditions; satellite magnetic conjugate studies, scientific model validation and comparison, physics research, and education. Previously, Version 2.0 provided a simplified graphical user interface, improved science and application modules, significantly enhanced graphical performance, common input data archive sets, and 1-D, 2-D, and 3- D visualization tools for all models. Dynamic capabilities permit multiple environments to be generated at user- specified time intervals while animation tools enable the display of satellite orbits and environment data together as a function of time. Building on the Version 2.0 software architecture, AF-GEOSpace Version 2.1 includes a host of new modules providing, for example, plasma sheet charged particle fluxes, neutral atmosphere densities, 3-D cosmic ray cutoff maps, low-altitude trapped proton belt flux specification, DMSP particle data displays, satellite magnetic field footprint mapping determination, and meteor sky maps and shower/storm fluxes with spacecraft impact probabilities. AF-GEOSpace Version 2.1 was

  9. GPIM AF-M315E Propulsion System

    NASA Technical Reports Server (NTRS)

    Spores, Ronald A.; Masse, Robert; Kimbrel, Scott; McLean, Chris

    2014-01-01

    The NASA Space Technology mission Directorate's (STMD) Green Propellant Infusion Mission (GPIM) Technology Demonstration Mission (TDM) will demonstrate an operational AF-M315E green propellant propulsion system. Aerojet-Rocketdyne is responsible for the development of the propulsion system payload. This paper statuses the propulsion system module development, including thruster design and system design; Initial test results for the 1N engineering model thruster are presented. The culmination of this program will be high-performance, green AF-M315E propulsion system technology at TRL 7+, with components demonstrated to TRL 9, ready for direct infusion to a wide range of applications for the space user community.

  10. Modeling Of Laser Ablation And Fragmentation Of Human Calculi

    NASA Astrophysics Data System (ADS)

    Gitomer, Steven J.; Jones, Roger D.; Howsare, Charles

    1989-09-01

    The large-scale radiation-hydrodynamics computer code LASNEX, has been used to model experimental results in the laser ablation and fragmentation of renal and biliary calculi. Recent experiments have demonstrated laser ablation and fragmentation of human calculi in vitro and in vivo. In the interaction, laser light incident upon the calculus is of sufficient intensity to produce a plasma (a hot ionized gas). The physical picture which emerges is as follows. The plasma couples to acoustic and shear waves which then propagate through the dense stone material, causing spall and fracture by reflection from material discontinuities or boundaries. Experiments have thus far yielded data on the interaction against which models can be tested. Data on the following have been published: (1) light emission, (2) absorption and emission spectra, (3) fragmentation efficiency, (4) cavitation bubble dynamics and (5) mass removal. We have performed one dimensional simulations of the laser-matter interaction to elucidate the im-portant physical mechanisms. We find that good quantitative fits between simulation and experiment are obtained for visible light emission, electron temperature, electron density, plasma pressure and cavitation bubble growth. With regard to mass removal, experiment and simulation are consistent with each other and give an excellent estimate of the ablation threshold. The modeling indicates that a very small ablation layer at the surface of the calulus is responsible for significant mass loss by fragmentation within the bulk of the calculus. With such quantitative fits in hand, we believe this type of modeling can now be applied to the study of other procedures involving plasma formation of interest to the medical community.

  11. Ultrasonography guided percutaneous radiofrequency ablation for hepatic cavernous hemangioma

    PubMed Central

    Cui, Yan; Zhou, Li-Yan; Dong, Man-Ku; Wang, Ping; Ji, Min; Li, Xiao-Ou; Chen, Chang-Wei; Liu, Zi-Pei; Xu, Yong-Jie; Zhang, Hong-Wen

    2003-01-01

    AIM: Hepatic cavernous hemangioma (HCH) is the most common benign tumor of the liver and its management is still controversial. Recent success in situ radiofrequency ablation of hepatic malignancies has led us to consider using this technique in patients with HCH. This study was to assess the efficacy, safety, and complications of percutaneous radiofrequency ablation (PRFA) under ultrasonography guidance in patients with HCH. METHODS: Twelve patients (four men and eight women, age ranged 33-56 years, mean age was 41.7 years) with 15 hepatic cavernous hemangiomas (2.5 cm to 9.5 cm) were treated using the RF-2000 generator and 10-needle LeVeen electrode percutaneously guided by B-ultrasound. Lesions larger than 3 cm were treated by multiple overlapping ablations that encompass the entire lesion as well as a rim of normal liver tissue (approximately 0.5 cm). RESULTS: All the patients who received PRFA therapy had no severe pain, bleeding or bile leakage during and after the procedures. Nine to 34 months’ follow-up (mean, 21 months) by ultrasound and/or spiral CT scan demonstrated that the ablated lesions in this group were shrunk remarkably, and the shrunken range was 38%-79% (mean, 67% per 21 months). The contrast enhancement was disappeared within the tumor or at its periphery in all cases on spiral CT scans obtained 3 to 6 months after treatment. CONCLUSION: The results of this study suggest that PRFA therapy is a mini-invasive, simple, safe, and effective method for the treatment of selected patients with HCH. PMID:12970923

  12. Mitral Isthmus Ablation with and Without Temporary Spot Occlusion of the Coronary Sinus

    PubMed Central

    HOCINI, MÉLÈZE; SHAH, ASHOK J.; NAULT, ISABELLE; RIVARD, LENA; LINTON, NICK; NARAYAN, SANJIV; MIYAZAKI, SHINSUKE; JADIDI, AMIR S.; KNECHT, SÉBASTIEN; SCHERR, DANIEL; WILTON, STEPHEN B.; ROTEN, LAURENT; PASCALE, PATRIZIO; PEDERSEN, MICHALA; DERVAL, NICOLAS; SACHER, FRÉDÉRIC; JAÏS, PIERRE; CLÉMENTY, JACQUES; HAÏSSAGUERRE, MICHEL

    2012-01-01

    Objective To evaluate the safety and outcomes of mitral isthmus (MI) linear ablation with temporary spot occlusion of the coronary sinus (CS). Background CS blood flow cools local tissue precluding transmurality and bidirectional block across MI lesion. Methods In a randomized, controlled trial (CS-occlusion = 20, Control = 22), MI ablation was performed during continuous CS pacing to monitor the moment of block. CS was occluded at the ablation site using 1 cm spherical balloon, Swan–Ganz catheter with angiographic confirmation. Ablation was started at posterior mitral annulus and continued up to left inferior pulmonary vein (LIPV) ostium using an irrigated-tip catheter. If block was achieved, balloon was deflated and linear block confirmed. If not, additional ablation was performed epicardially (power ≤25 W). Ablation was abandoned after ~30 minutes, if block was not achieved. Results CS occlusion (mean duration –27 ± 9 minutes) was achieved in all cases. Complete MI block was achieved in 13/20 (65%) and 15/22 (68%) patients in the CS-occlusion and control arms, respectively, P = 0.76. Block was achieved with significantly small number (0.5 ± 0.8 vs 1.9 ± 1.1, P = 0.0008) and duration (1.2 ± 1.7 vs 4.2 ± 3.5 minutes, P = 0.009) of epicardial radiofrequency (RF) applications and significantly lower amount of epicardial energy (1.3 ± 2.4 vs 6.3 ± 5.7 kJ, P = 0.006) in the CS-occlusion versus control arm, respectively. There was no difference in total RF (22 ± 9 vs 23 ± 11 minutes, P = 0.76), procedural (36 ± 16 vs 39 ± 20 minutes, P = 0.57), and fluoroscopic (13 ± 7 vs 15 ± 10 minutes, P = 0.46) durations for MI ablation between the 2 arms. Clinically uneventful CS dissection occurred in 1 patient Conclusions Temporary spot occlusion of CS is safe and significantly reduces the requirement of epicardial ablation to achieve MI block. It does not improve overall procedural success rate and procedural duration. Tissue cooling by CS blood flow is just

  13. Possible Role for Cryoballoon Ablation of Right Atrial Appendage Tachycardia when Conventional Ablation Fails

    PubMed Central

    Kilic, Ayhan

    2015-01-01

    Focal atrial tachycardia arising from the right atrial appendage usually responds well to radiofrequency ablation; however, successful ablation in this anatomic region can be challenging. Surgical excision of the right atrial appendage has sometimes been necessary to eliminate the tachycardia and prevent or reverse the resultant cardiomyopathy. We report the case of a 48-year-old man who had right atrial appendage tachycardia resistant to multiple attempts at ablation with use of conventional radiofrequency energy guided by means of a 3-dimensional mapping system. The condition led to cardiomyopathy in 3 months. The arrhythmia was successfully ablated with use of a 28-mm cryoballoon catheter that had originally been developed for catheter ablation of paroxysmal atrial fibrillation. To our knowledge, this is the first report of cryoballoon ablation without isolation of the right atrial appendage. It might also be an alternative to epicardial ablation or surgery when refractory atrial tachycardia originates from the right atrial appendage. PMID:26175651

  14. Testing and evaluation of light ablation decontamination

    SciTech Connect

    Demmer, R.L.; Ferguson, R.L.

    1994-10-01

    This report details the testing and evaluation of light ablation decontamination. It details WINCO contracted research and application of light ablation efforts by Ames Laboratory. Tests were conducted with SIMCON (simulated contamination) coupons and REALCON (actual radioactive metal coupons) under controlled conditions to compare cleaning effectiveness, speed and application to plant process type equipment.

  15. PULSED LASER ABLATION OF CEMENT AND CONCRETE

    EPA Science Inventory

    Laser ablation was investigated as a means of removing radioactive contaminants from the surface and near-surface regions of concrete from nuclear facilities. We present the results of ablation tests on cement and concrete samples using a pulsed Nd:YAG laser with fiber optic beam...

  16. Percutaneous Local Ablative Therapy for Hepatocellular Carcinoma

    PubMed Central

    Lau, W. Y.; Leung, Thomas W. T.; Yu, Simon C. H.; Ho, Stephen K. W.

    2003-01-01

    Objective To review and compare treatment result for percutaneous local ablative therapy (PLAT) with surgical resection in the treatment of small hepatocellular carcinoma (HCC). Summary Background Data PLAT is indicated for small unresectable HCC localized to the liver. From the use of ethanol to the latest technology of radiofrequency ablation, ablative techniques have been refined and their role in the management of HCC established. This review aims to give an overview of various ablative methods, including their efficacy, indications, and limitations, and also tries to look into the future of clinical trials in PLAT. Methods The authors reviewed recent papers in the English medical literature about the use of local ablative therapy for HCC. Focus was given to the results of treatment in terms of local control, progression-free survival, and overall survival, and to compare treatment results with those of surgery. Results PLAT for small HCC (<5 cm) with thermal ablation (radiofrequency ablation or microwave coagulation) can achieve effective local control of disease and is superior to ethanol injection. Progressive disease in untreated areas is a common reason for failure. Overall progression-free survival is similar to that of surgical resection. Conclusions Thermal ablation gives good local control of small HCC, is superior to ethanol, and may be comparable to surgical resection in long-term outcome. PMID:12560774

  17. Excimer laser ablation of the lens.

    PubMed

    Nanevicz, T M; Prince, M R; Gawande, A A; Puliafito, C A

    1986-12-01

    Ablation of the bovine crystalline lens was studied using radiation from an excimer laser at four ultraviolet wave lengths as follows: 193 nm (argon fluoride), 248 nm (krypton fluoride), 308 nm (xenon chloride), and 351 nm (xenon fluoride). The ablation process was quantitated by measuring mass ablated with an electronic balance, and characterized by examining ablation craters with scanning electron microscopy. The highest ablation rate was observed at 248 nm with lower rates at 193 and 308 nm. No ablation was observed at 351 nm. Scanning electron microscopy revealed the smoothest craters at 193 nm while at 248 nm there was vacuolization in the crater walls and greater disruption of surrounding tissue. The craters made at 308 nm did not have as smooth a contour as the 193-nm lesions. The spectral absorbance of the bovine lens was calculated at the wavelengths used for ablation and correlated with ablation rates and thresholds. High peak-power, pulsed ultraviolet laser radiation may have a role in surgical removal of the lens. PMID:3789982

  18. Renaissance of laser interstitial thermal ablation.

    PubMed

    Missios, Symeon; Bekelis, Kimon; Barnett, Gene H

    2015-03-01

    Laser interstitial thermal therapy (LITT) is a minimally invasive technique for treating intracranial tumors, originally introduced in 1983. Its use in neurosurgical procedures was historically limited by early technical difficulties related to the monitoring and control of the extent of thermal damage. The development of magnetic resonance thermography and its application to LITT have allowed for real-time thermal imaging and feedback control during laser energy delivery, allowing for precise and accurate provision of tissue hyperthermia. Improvements in laser probe design, surgical stereotactic targeting hardware, and computer monitoring software have accelerated acceptance and clinical utilization of LITT as a neurosurgical treatment alternative. Current commercially available LITT systems have been used for the treatment of neurosurgical soft-tissue lesions, including difficult to access brain tumors, malignant gliomas, and radiosurgery-resistant metastases, as well as for the ablation of such lesions as epileptogenic foci and radiation necrosis. In this review, the authors aim to critically analyze the literature to describe the advent of LITT as a neurosurgical, laser excision tool, including its development, use, indications, and efficacy as it relates to neurosurgical applications. PMID:25727222

  19. Pulmonary Thermal Ablation: Comparison of Radiofrequency and Microwave Devices by Using Gross Pathologic and CT Findings in a Swine Model

    PubMed Central

    Brace, Christopher L.; Hinshaw, J. Louis; Laeseke, Paul F.; Sampson, Lisa A.; Lee, Fred T.

    2009-01-01

    Purpose: To compare the performance of equivalently sized radiofrequency and microwave ablation applicators in a normal porcine lung model. Materials and Methods: All experiments were approved by an institutional animal care and use committee. A total of 18 ablations were performed in vivo in normal porcine lungs. By using computed tomographic (CT) fluoroscopic guidance, a 17-gauge cooled triaxial microwave antenna (n = 9) and a 17-gauge cooled radiofrequency (RF) electrode (n = 9) were placed percutaneously. Ablations were performed for 10 minutes by using either 125 W of microwave power or 200 W of RF power delivered with an impedance-based pulsing algorithm. CT images were acquired every minute during ablation to monitor growth. Animals were sacrificed after the procedure. Ablation zones were then excised and sectioned transverse to the applicator in 5-mm increments. Minimum and maximum diameter, cross-sectional area, length, and circularity were measured from gross specimens and CT images. Comparisons of each measurement were performed by using a mixed-effects model; P < .05 was considered to indicate a significant difference. Results: Mean diameter (3.32 cm ± 0.19 [standard deviation] vs 2.70 cm ± 0.23, P < .001) was 25% larger with microwave ablation and mean cross-sectional area (8.25 cm2 ± 0.92 vs 5.45 cm2 ± 1.14, P < .001) was 50% larger with microwave ablation, compared with RF ablation. With microwave ablation, the zones of ablation were also significantly more circular in cross section (mean circularity, 0.90 ± 0.06 vs 0.82 ± 0.09; P < .05). One small pneumothorax was noted during RF ablation but stabilized without intervention. Conclusion: Microwave ablation with a 17-gauge high-power triaxial antenna creates larger and more circular zones of ablation than does a similarly sized RF applicator in a preclinical animal model. Microwave ablation may be a more effective treatment of lung tumors. © RSNA, 2009 PMID:19336667

  20. Molecular and functional identification of three interleukin-17A/F (IL-17A/F) homologues in large yellow croaker (Larimichthys crocea).

    PubMed

    Ding, Yang; Ao, Jingqun; Ai, Chunxiang; Chen, Xinhua

    2016-02-01

    The interleukin-17 (IL-17) cytokine family plays a central role in the coordination of inflammatory responses. In fish species, three genes that have a similar homology to both IL-17A and IL-17F were designated IL-17A/F1, 2, and 3. In this study, we identified three IL-17A/F homologues (LycIL-17A/F1, 2, and 3) from large yellow croaker (Larimichthys crocea). The deduced LycIL-17A/F1 and 3 had four cysteine residues conserved in teleost IL-17A/F1 and 3 homologues and shared a domain similar to the B chain of human IL-17F. The deduced LycIL-17A/F2 possessed the unique arrangement of six cysteine residues as teleost IL-17A/F2 (except Fugu IL-17A/F2) and higher vertebrate IL-17A and F, and shared a domain similar to the D/E chain of human IL-17A. Phylogenetic analysis showed that teleost IL-17A/F1 and 3 fall into a major clade, whereas IL-17A/F2 forms a separated clade and is clustered with IL-17N. Based on structural and phylogenetic analyses, we suggest that teleost IL-17A/Fs may be classified into two subgroups: one consisting of IL-17A/F1 and 3, and the other composed of IL-17A/F2. The three LycIL-17A/Fs were constitutively expressed in all tissues examined although at a different level. Following challenge with Aeromonas hydrophila, expression of these three LycIL-17A/Fs was rapidly increased in head kidney and gills. The in vivo assays showed that recombinant LycIL-17A/F1, 2, and 3 all were able to enhance the expression of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α2), chemokines (CXCL8 and CXCL13), and antimicrobial peptide hepcidin in head kidney. Furthermore, LycIL-17A/Fs appeared to mediate pro-inflammatory responses via NF-κB signalling. These results therefore reveal similar functions between the two subgroup members,LycIL-17A/F1 and 3 and LycIL-17A/F2, in promoting inflammation and host defences. PMID:26429410