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RF Lesion (rf + lesion)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Dynamic Registration of Preablation Imaging With a Catheter Geometry to Guide Ablation in a Swine Model: Validation of Image Integration and Assessment of Catheter Navigation Accuracy

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2010
J. JASON WEST M.D.
Image Integration with a Catheter Mapping System.,Background: Catheter ablation of atrial and ventricular tachyarrhythmia involves anatomically based cardiac ablation strategies. CT and MRI images provide the most detailed cardiac anatomy available. Integration of these images into a mapping system should produce detailed and accurate models suitable to guide ablation. Objective: The purpose of this study was to validate and assess the accuracy of a novel CT and MRI image integration algorithm designed to facilitate catheter navigation and ablation. Methods: Using a lateral thoracotomy, markers were sutured to the epicardial surface of each cardiac chamber in 12 swine. Detailed CT/MRI anatomy was imported into the mapping system. The CT/MRI image was then integrated with a detailed catheter geometry of the relevant chamber using a new image integration algorithm. The epicardial markers, identified from the CT/MRI images, were then displayed on the surface of the integrated image. Guided only by the integrated CT/MRI, a single RF lesion was directed at the corresponding endocardial site for each epicardial marker. At autopsy, the distance from the endocardial RF lesion to the target site was assessed. Results: The mean position error (CT/MRI) for the left atrium was 2.5 ± 2.4 mm/5.1 ± 3.9 mm, for the right atrium 6.2 ± 6.5 mm/4.3 ± 2.2 mm, for the right ventricle 6.2 ± 4.3 mm/6.6 ± 5.3 mm, and for the left ventricle 4.7 ± 3.4 mm/3.1 ± 2.7 mm. There was no cardiac perforation or tamponade. Conclusion: CT and MRI images can be effectively utilized for catheter navigation when integrated into a mapping system. This novel registration module with dynamic registration provides effective guidance for ablation. (J Cardiovasc Electrophysiol, Vol. 21, pp. 81,87, January 2010) [source]

Viral interleukin-6 encoded by rhesus macaque rhadinovirus is associated with lymphoproliferative disorder (LPD)

JOURNAL OF MEDICAL PRIMATOLOGY, Issue 2009
B.U. Orzechowska
Abstract Background, Rhesus macaques (RM) co-infected with simian immunodeficiency virus (SIV) and rhesus macaque rhadinovirus (RRV) develop abnormal cellular proliferations characterized as extra-nodal lymphoma and retroperitoneal fibromatosis (RF). RRV encodes a viral interleukin-6 (vIL-6), much like Kaposi's sarcoma-associated herpesvirus, and involvement of the viral cytokine was examined in proliferative lesions. Methods, Formalin fixed tissue from RM co-infected with SIV and RRV were analyzed for RRV genomes by in situ hybridization and RRV vIL-6 expression by immunofluorescence analysis. Results, In situ hybridization analysis indicated that RRV is present in both types of lesions. Immunofluorescence analysis of different lymphomas and RF revealed positive staining for vIL-6. Similarly to KS, RF lesion is positive for vimentin, CD117 (c-kit), and smooth muscle actin (SMA) and contains T cell, B cell and monocytes/macrophage infiltrates. Conclusions, Our data support the idea that vIL-6 may be critical to the development and progression of lymphoproliferative disorder in RRV/SIV-infected RM. [source]

Effects of Corticosteroid Therapy on the Long-Term Outcome of Radiofrequency Lesions in the Swine Caval Veins

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2008
GUILHERME FENELON M.D.
Background: We explored the angiographic and pathological effects of corticosteroids on the long-term outcome of radiofrequency (RF) ablation lesions in the swine caval veins. Methods: Under fluoroscopy guidance, a single linear RF lesion (4-mm tip, 60°C, 180 seconds) was created in each vena cava (from ±2 cm into the vein to the venoatrial junction) of 20 anesthetized minipigs (35± 2 kg). Three groups were studied: acute (n = 4), killed 1 hour after RF; control (n = 8), sacrificed 83± 1 days after RF; and pigs (n = 8) receiving hydrocortisone (400 mg i.v. after RF) and prednisone (25 mg po for 30 days), killed 83± 1 days post-RF. Angiography was performed before, immediately after ablation, and at follow-up. Then, animals were sacrificed for histological analysis. Results: Mild (<40%) or moderate (41,70%) acute luminal narrowing occurred in 19/20 (95%) inferior veins and in 13/20 (65%) superior veins. Severe (>70%) stenosis and occlusions were not noted. At follow-up, in both chronic groups, mean vessel diameters returned to baseline and progression of luminal narrowing did not occur in any vein. Of note, superior and inferior vena cava angiographic diameter for control and treated pigs did not differ. The same was observed for the cross-sectional luminal area. Acute lesions displayed transmural coagulative necrosis whereas chronic lesions revealed marked fibrosis. Histological findings were similar in controls and treated pigs. Conclusion: In this model, mild and moderate stenosis, occurring immediately after ablation, seems to resolve over time. Corticosteroids do not affect the long-term outcome of such RF lesions in the caval veins. [source]

Radiofrequency Neurotomy for Low Back Pain: Evidence-Based Procedural Guidelines

PAIN MEDICINE, Issue 2 2005
W. Michael Hooten MD
ABSTRACT Objective., This review was undertaken to outline the procedural limitations of the randomized controlled trials (RCTs) of radiofrequency (RF) neurotomy for low back pain. Second, the literature related to patient selection, diagnostic testing, and the technique of performing lumbar spine, RF neurotomy will be critically reviewed and analyzed. Based on these analyses, diagnostic and procedural guidelines will be proposed. Design., A Medline and EMBASE search identified three RCTs and two systematic reviews of RF neurotomy for low back pain. A similar search identified pertinent literature related to the method of patient selection for a diagnostic block, the medial branch and L5 dorsal ramus comparative block, and the anatomical and technical parameters of lumbar spine RF neurotomy. Results., Substantial procedural shortcomings were identified in all three RCTs. In the systematic reviews, these procedural limitations were not accounted for by the quality assessment of study design which resulted in an inaccurate estimate of clinical effectiveness. Analysis using likelihood ratios showed that screening criteria could increase the probability of zygapophysial joint pain before performing diagnostic blocks. Similar analysis showed that comparative medial branch blocks, rather than single blocks, must be used before RF neurotomy. Anatomical studies demonstrated that the shorter distal compared with the circumferential radius of the RF lesion necessitates placement of the electrode parallel to the course of the nerve along the base of the superior articular process. Conclusions., The evidence-based procedural guidelines provide consistent criteria for multisite studies that could enroll a sufficiently large homogenous study cohort. [source]

Randomized Comparison Between Open Irrigation Technology and Intracardiac-Echo-Guided Energy Delivery for Pulmonary Vein Antrum Isolation: Procedural Parameters, Outcomes, and the Effect on Esophageal Injury

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2007
NASSIR F. MARROUCHE M.D.
Introduction: We performed a prospective study to compare efficacy and safety of both open irrigation tip (OIT) technology with intracardiac echo (ICE)-guided energy delivery in patients presenting for PVAI. Methods and Results: Fifty-three patients presenting for PVAI were randomized to ablation using an OIT catheter (Group 1, 26 patients; temperature and power were set at 50° and 50 W, respectively, with a saline pump flow rate of 30 mL/min) or radiofrequency (RF) energy delivery under ICE guidance (Group 2, 27 patients; energy was titrated based on microbubbles formation). The mean procedure time and fluoroscopy exposure were lower in Group 1 (164 ± 42 min and 7,560 ± 2,298 ,Graym2 vs 204 ± 47 min and 12,240 ± 4,356 ,Graym2; P = 0.005 and 0.008, respectively). Moreover, the durations of RF lesions applied per PV antrum was lower in Group 1 compared with Group 2 (5.1 ± 2.2 min vs 9.2 ± 3.2 min, P = 0.03, respectively). Within 24 hours after PVAI in 35.7% (all erythema) of Group 1 and 57.1% (21.4% erythema and 35.7% necrosis) of Group 2, patients' esophageal wall changes were documented. After 14 ± 2 months of follow up, recurrences were documented in 19.2% of Group 1 and 22.2% of Group 2 patients. Conclusion: Although both OIT and ICE-guided energy delivery possess a similar effect in treating AF, OIT seems to be superior in terms of achieving isolation and shortening fluoroscopy exposure. Moreover, a lower incidence of esophageal wall injury was observed utilizing OIT for PVAI. [source]

Effects of Corticosteroid Therapy on the Long-Term Outcome of Radiofrequency Lesions in the Swine Caval Veins

Comparison of the Healing Mechanisms of Myocardial Lesions Induced by Dry Radiofrequency and Microwave Epicardial Ablation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2006
ROSA HENRIQUES DE GOUVEIA
Background: Histological assessment of the evolution of lesions induced on a pig's left atrium by microwave (MW) epicardial applications and comparison with dry radiofrequency (RF) lesions. Methods: MW (40 W, 40 seconds) and dry RF (80°C, 2 minutes) were epicardially applied on nine pigs' left atrium. Samples were procured following application (n = 2), at day 3 (n = 2), day 7 (n = 2), day 14 (n = 2), and at 1 month (n = 1). They were fixed in formalin, embedded in paraffin, sectioned (2 ,), stained with histochemical dyes, immunomarked, and histologically analyzed. Results: Histological features of acute stage MW lesion are interstitial hemorrhage, adipose, and muscular tissues' coagulation necrosis, thrombosis of myocardial interstitium small vessels at damaged and optically undamaged areas, epicardial coronary branches, and endocardial parietal thrombosis. Day 3,lymphohistiocytic infiltration (lysosyme+) highlights lesion limits. Day 7,lymphohistiocytic infiltration increases, multi-nucleated giant cells appear surrounding/fagocyting necrotic tissue. Neovessels and scarce myofibroblasts appear. Lesion edges are now better defined. Day 14,myofibroblastic proliferation (actin++, vimentin+) creates "young" scar tissue, as in "healing by second intention." Lesions are deeper and wider than appeared at acute stage. One month,dense fibrous tissue scar appears. Endothelial cells covering endocardium are morphologically intact. RF lesions are histologically identical to MW's, although no vessel thrombosis was identified at acute optically undamaged areas and cytomorphologic elements emerge at later stages in the healing process. Conclusions: (1) Microwave scars are deeper and wider than the lesions observed at the acute stage. (2) Evolution of microwave lesions is faster and induces broader scars than dry radiofrequency. (3) Scar formation (both energies) is "healing by second intention." (4) Endocardial thrombosis may occur despite morphologically intact endothelium. [source]

Mapping of Atrial Activation Patterns After Inducing Contiguous Radiofrequency Lesions: An Experimental Study

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2001
FRANCISCO J. CHORRO
CHORRO, F.J., et al.: Mapping of Atrial Activation Patterns After Inducing Contiguous Radiofrequency Lesions: An Experimental Study. High resolution mapping techniques are used to analyze the changes in atrial activation patterns produced by contiguous RF induced lesions. In 12 Langendorff-perfused rabbit hearts, left atrial activation maps were obtained before and after RF induction of epicardial lesions following a triple-phase sequential protocol: (phase 1) three separate lesions positioned vertically in the central zone of the left atrial wall; (phase 2) the addition of two lesions located between the central lesion and the upper and lower lesions; and (phase 3) the placement of four additional lesions between those induced in the previous phases. In six additional experiments a pathological analysis of the individual RF lesions was performed. In phase 1 (lesion diameter = 2.8 ± 0.2 mm, gap between lesions = 3 ± 0.8 mm), the activation process bordered the lesions line in two (2.0-ms cycles) and four experiments (1.0-ms cycles). In phase 2, activation bordered the lesions line in eight (2.0-ms cycles, P < 0.01 vs control) and nine experiments (1.0-ms cycles, P < 0.001), and in phase 3 this occurred in all experiments except one (both cycles, P < 0.001 vs control). In the experiments with conduction block, the increment of the interval between activation times proximal and distal to the lesions showed a significant correlation to the length of the lesions (r = 0.68, P < 0.05, 100-ms cycle). In two (17%) experiments, sustained regular tachycardias were induced with reentrant activation patterns around the lesions line. In conclusion, in this acute model, atrial RF lesions with intact tissue gaps of 3 mm between them interrupt conduction occasionally, and conduction block may be frequency dependent. Lesion overlap is required to achieve complete conduction block lines. Tachycardias with reentrant activation patterns around a lesions line may be induced. [source]