Diagnostics of Internal Defects in Composite Overhead Insulators Using an Optic E-Field Sensor.

Composite insulators for high-voltage overhead lines have better performances and are lighter than traditional designs, especially in heavily polluted areas. However, since it is a relatively recent technology, reliable methods to perform live-line diagnostics are still under development, especially with regard to internal defects, which provide few external symptoms. Thermal cameras can be employed, but their use is not always straightforward as the sun radiation can hide the thermal footprint of internal degenerative effects. In this work, an optical E-field sensor has been used to diagnose the internal defects of a set of composite insulators (bandwidth 200 mHz-50 MHz, min. detectable E-field 100 V/m). Moreover, a modelling activity using finite elements has been carried out to identify the possible nature of the defects by comparing experimental E-field profiles with those simulated assuming a specific defect geometry. The results show that the sensor can detect the presence of an internal defect, since its presence distorts the E-field profile when compared to the profile of a sound insulator. Moreover, the measured E-field profiles are compatible with the corresponding simulated ones when a conductive defect is considered. However, it was observed that a defect whose conductivity is not at least two orders of magnitude greater than the conductivity of the surroundings remains undetected.

A Self-Calibrating Localization Solution for Sport Applications with UWB Technology.

This study addressed the problem of localization in an ultrawide-band (UWB) network, where the positions of both the access points and the tags needed to be estimated. We considered a fully wireless UWB localization system, comprising both software and hardware, featuring easy plug-and-play usability for the consumer, primarily targeting sport and leisure applications. Anchor self-localization was addressed by two-way ranging, also embedding a Gauss-Newton algorithm for the estimation and compensation of antenna delays, and a modified isolation forest algorithm working with low-dimensional set of measurements for outlier identification and removal. This approach avoids time-consuming calibration procedures, and it enables accurate tag localization by the multilateration of time difference of arrival measurements. For the assessment of performance and the comparison of different algorithms, we considered an experimental campaign with data gathered by a proprietary UWB localization system.

Effect of Local Topography on Cell Division of Staphylococcus spp.

Surface engineering is a promising strategy to limit or prevent the formation of biofilms. The use of topographic cues to influence early stages of biofilm formationn has been explored, yet many fundamental questions remain unanswered. In this work, we develop a topological model supported by direct experimental evidence, which is able to explain the effect of local topography on the fate of bacterial micro-colonies of Staphylococcus spp. We demonstrate how topological memory at the single-cell level, characteristic of this genus of Gram-positive bacteria, can be exploited to influence the architecture of micro-colonies and the average number of surface anchoring points over nano-patterned surfaces, formed by vertically aligned silicon nanowire arrays that can be reliably produced on a commercial scale, providing an excellent platform to investigate the effect of topography on the early stages of Staphylococcus spp. colonisation. The surfaces are not intrinsically antimicrobial, yet they delivered a topography-based bacteriostatic effect and a significant disruption of the local morphology of micro-colonies at the surface. The insights from this work could open new avenues towards designed technologies for biofilm engineering and prevention, based on surface topography.

Recognized and Emerging Features of Erythropoietic and X-Linked Protoporphyria.

Erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) are inherited disorders resulting from defects in two different enzymes of the heme biosynthetic pathway, i.e., ferrochelatase (FECH) and delta-aminolevulinic acid synthase-2 (ALAS2), respectively. The ubiquitous FECH catalyzes the insertion of iron into the protoporphyrin ring to generate the final product, heme. After hemoglobinization, FECH can utilize other metals like zinc to bind the remainder of the protoporphyrin molecules, leading to the formation of zinc protoporphyrin. Therefore, FECH deficiency in EPP limits the formation of both heme and zinc protoporphyrin molecules. The erythroid-specific ALAS2 catalyses the synthesis of delta-aminolevulinic acid (ALA), from the union of glycine and succinyl-coenzyme A, in the first step of the pathway in the erythron. In XLP, ALAS2 activity increases, resulting in the amplified formation of ALA, and iron becomes the rate-limiting factor for heme synthesis in the erythroid tissue. Both EPP and XLP lead to the systemic accumulation of protoporphyrin IX (PPIX) in blood, erythrocytes, and tissues causing the major symptom of cutaneous photosensitivity and several other less recognized signs that need to be considered. Although significant advances have been made in our understanding of EPP and XLP in recent years, a complete understanding of the factors governing the variability in clinical expression and the severity (progression) of the disease remains elusive. The present review provides an overview of both well-established facts and the latest findings regarding these rare diseases.

One-step preparation of antimicrobial silicone materials based on PDMS and salicylic acid: insights from spatially and temporally resolved techniques.

In this work, we introduce a one-step strategy that is suitable for continuous flow manufacturing of antimicrobial PDMS materials. The process is based on the intrinsic capacity of PDMS to react to certain organic solvents, which enables the incorporation of antimicrobial actives such as salicylic acid (SA), which has been approved for use in humans within pharmaceutical products. By combining different spectroscopic and imaging techniques, we show that the surface properties of PDMS remain unaffected while high doses of the SA are loaded inside the PDMS matrix. The SA can be subsequently released under physiological conditions, delivering a strong antibacterial activity. Furthermore, encapsulation of SA inside the PDMS matrix ensured a diffusion-controlled release that was tracked by spatially resolved Raman spectroscopy, Attenuated Total Reflectance IR (ATR-IR), and UV-Vis spectroscopy. The biological activity of the new material was evaluated directly at the surface and in the planktonic state against model pathogenic bacteria, combining confocal laser scanning microscopy, electron microscopy, and cell viability assays. The results showed complete planktonic inhibition for clinically relevant strains of Staphylococcus aureus and Escherichia coli, and a reduction of up to 4 orders of magnitude for viable sessile cells, demonstrating the efficacy of these surfaces in preventing the initial stages of biofilm formation. Our approach adds a new option to existing strategies for the antimicrobial functionalisation of a wide range of products such as catheters, wound dressings and in-dwelling medical devices based on PDMS.

Reducing antibiotic prescriptions in children is not associated with higher rate of complications.

Acute otitis media (AOM) and sore throat are common reasons for antibiotic prescription in children. Starting from 2007, evidence-based guidelines and other multifaceted improvement activities (ProBA project) were implemented in Emilia-Romagna, a northern Italian region. Antibiotic prescription rate in the region decreased with time (37% relative reduction from 2005 to 2019). Within the ProBA project, this retrospective observational study, including all hospitals of the region, aims to assess if lower rate of antibiotic prescription was associated with an increased rate of acute mastoiditis and acute rheumatic fever (ARF). Hospital admission rates for acute mastoiditis and ARF from 2005 to 2019 were calculated using ICD-9 codes. Hospital intervention rates for myringotomy, incision of mastoid, and mastoidectomy were also assessed. A comparison with antibiotic prescription rate in the pediatric population was performed. Data were gathered using administrative databases and trends were calculated using Poisson regression. During the study period, rate of mastoiditis and similar diagnosis declined from 54.1 to 33.6 per 100.000 (ß coefficient = - 0.047, p value < 0.001) and rate of surgical treatment from 134.6 to 89.6 per 100.000 (ß coefficient = - 0.036, p value < 0.001), whereas rate of ARF remained stable at around 4.4-4.8 per 100.000 (ß coefficient = - 0.009, p value = 0.472).Conclusion: ProBA project implementation-recommending 5 days of amoxicillin for AOM when needed and 6 days of amoxicillin when streptococcal pharyngitis is detected-was associated with a reduced antibiotic use without an increase of complications. What is Known: • Acute otitis media (AOM) and streptococcal pharyngitis are common pediatric infections and frequent cause of antibiotics prescription. • Fear of rare complications like mastoiditis and acute rheumatic fever can hinder health professionals' compliance with evidence-based guideline. What is New: • Guidelines recommending a short course of antibiotics for AOM and streptococcal pharyngitis are associated with reduced antibiotic prescriptions and no increase of complications. • Analysis based on administrative databases is useful for monitoring projects and supporting health professionals in complying with guidelines.

Experimental Characterization of Polymer Surfaces Subject to Corona Discharges in Controlled Atmospheres.

Polymeric dielectrics are employed extensively in the power transmission industry, thanks to their excellent properties; however, under normal operating conditions these materials tend to degrade and fail. In this study, samples of low-density polyethylene, polypropylene, polymethyl methacrylate, and polytetrafluorethylene were subjected to corona discharges under nitrogen and air atmospheres. The discharges introduced structural modifications over the polymer surface. From a chemical perspective, the alterations are analogous among the non-fluorinated polymers (i.e., polyethylene (PE), polypropylene (PP), and polymethyl methacrylate (PMMA)). A simulation of the corona discharge allowed the identification of highly reactive species in the proximity of the surface. The results are consistent with the degradation of insulating polymers in high-voltage applications due to internal partial discharges that ultimately lead to the breakdown of the material.

Formula feeding increases the risk of antibiotic prescriptions in children up to 2 years: results from a cohort study.

Association between the use of infant formula and risks for infants' health is seldom studied in western countries. We set up a historical cohort based on record linkage analysis, combining the data from administrative databases providing individual data. Infants receiving the second dose of pediatric immunization between 2015 and 2017 were included. The main outcome measure was antibiotic prescriptions from enrolment up to 24 months of age, by infant feeding category at enrolment. The extended Cox regression technique was used to account for recurrent events. The infants' cohort included 40,258 5-month-old infants; during the study period, 60,932 antibiotic prescriptions were filled. Compared with infants fully breastfed, children fed with both maternal milk and formula received 106 more antibiotic prescriptions per 1000 children/year, whereas infants receiving formula only had 138 excess prescriptions per 1000 children/year. The association with infant feeding was statistically significant and remained unchanged after adjustment for common confounders (adjusted hazard ratio, HR, for complementary feeding vs full breastfeeding 1.09; 95%CI 1.05 to 1.12; formula only versus full breastfeeding adj. HR 1.12; 95%CI 1.08 to 1.16).Conclusion: In our cohort, we observed a positive association between infant formula use considered a proxy of infections antibiotic prescription rate, considered a proxy of infections. The association followed a gradient.What is Known:• Formula feeding is associated with increased morbidity and mortality even in western countries, but still, it is common.• Information on formula are seldom unbiased; thus, public perception of risks is distorted.What is New:• In a large Italian cohort of infants, formula feeding at 5 months of age results to be associated with an increased rate of antibiotic prescription (considered to be a proxy of infection) up to 24 months of age: the association follows a dose-response relationship.• Record linkage analysis using administrative databases provides useful information at a limited cost.

Novel mutation of PPOX gene in a patient with abdominal pain and syndrome of inappropriate antidiuresis.

PURPOSE: Acute porphyrias are metabolic disorders of heme biosynthesis characterized by acute life-threatening attacks. The diagnosis is often missed since clinical presentation is aspecific mimicking other medical and surgical conditions. Variegate porphyria (VP) is an autosomal dominant inherited disease with incomplete penetrance due to decreased activity of the Protoporphyrinogen Oxydase (PPOX) gene; most VP mutations are family specific. We report the case of a 40 year-old woman who presented many times to the emergency department complaining of unexplained abdominal pain and laboratory investigations showed repeatedly hyponatremia. Syndrome of inappropriate antidiuresis (SIAD) was confirmed and measurement of urine porphobilinogen and delta-aminolevulinic acid disclosed the diagnosis of acute porphyria. The genetic analysis of PPOX gene was performed. METHODS: The entire coding sequence and exon/intron boundaries of PPOX gene were amplified in 5 different Polymerase Chain Reaction (PCR) fragments. In silico prediction of the pathogenicity of the mutation was determined by using different tools, Polyphen2, SNPs&GO, SNPs3D. RESULTS: The genetic analysis of PPOX gene revealed a novel missense variant c.1376 G > A (p.Cys459Tyr) in heterozygous state. The same variant was later found in one of her cousins with skin lesions and other three younger asymptomatic relatives. We provided evidence that this novel mutation is likely to be pathogenetic. CONCLUSIONS: Our case highlights the importance of considering VP in the differential diagnosis of SIAD and underlines the role of genetic screening in the management of such patients. The finding of a novel mutation of PPOX gene in our index case has allowed to recognize an affected family.

A sensor for vector electric field measurements through a nonlinear anisotropic optical crystal.

Electrical applications require the development of electric field sensors that can reproduce vector electric field waveforms with a very large spectral width ranging from 50 Hz to at least 70 MHz. This makes it possible to measure both the normal operation modes of electrical components and abnormal behaviors such as the corona emission and partial discharges. In this work, we aim to develop a fully dielectric sensor capable of measuring two components of the electric field using a wide class of optical crystals including anisotropic ones, whereas most of the efforts in this field have been devoted to isotropic crystals. We report the results of the measurements performed at 50 Hz and with a lightning impulse, to validate the sensor.

Disturbed iron metabolism in erythropoietic protoporphyria and association of GDF15 and gender with disease severity.

Patients with erythropoietic protoporphyria (EPP) have reduced activity of the enzyme ferrochelatase that catalyzes the insertion of iron into protoporphyrin IX (PPIX) to form heme. As the result of ferrochelatase deficiency, PPIX accumulates and causes severe photosensitivity. Among different patients, the concentration of PPIX varies considerably. In addition to photosensitivity, patients frequently exhibit low serum iron and a microcytic hypochromic anemia. The aims of this study were to (1) search for factors related to PPIX concentration in EPP, and (2) characterize anemia in EPP, i.e., whether it is the result of an absolute iron deficiency or the anemia of chronic disease (ACD). Blood samples from 67 EPP patients (51 Italian and 16 Swiss) and 21 healthy volunteers were analyzed. EPP patients had lower ferritin (p = 0.021) and hepcidin (p = 0.031) concentrations and higher zinc-protoporphyrin (p < 0.0001) and soluble-transferrin-receptor (p = 0.0007) concentrations compared with controls. This indicated that anemia in EPP resulted from an absolute iron deficiency. Among EPP patients, PPIX concentrations correlated with both growth differentiation factor (GDF) 15 (p = 0.012) and male gender (p = 0.015). Among a subgroup of patients who were iron replete, hemoglobin levels were normal, which suggested that iron but not ferrochelatase is the limiting factor in heme synthesis of individuals with EPP.

The loss of ATP2C1 impairs the DNA damage response and induces altered skin homeostasis: Consequences for epidermal biology in Hailey-Hailey disease.

Mutation of the Golgi Ca(2+)-ATPase ATP2C1 is associated with deregulated calcium homeostasis and altered skin function. ATP2C1 mutations have been identified as having a causative role in Hailey-Hailey disease, an autosomal-dominant skin disorder. Here, we identified ATP2C1 as a crucial regulator of epidermal homeostasis through the regulation of oxidative stress. Upon ATP2C1 inactivation, oxidative stress and Notch1 activation were increased in cultured human keratinocytes. Using RNA-seq experiments, we found that the DNA damage response (DDR) was consistently down-regulated in keratinocytes derived from the lesions of patients with Hailey-Hailey disease. Although oxidative stress activates the DDR, ATP2C1 inactivation down-regulates DDR gene expression. We showed that the DDR response was a major target of oxidative stress-induced Notch1 activation. Here, we show that this activation is functionally important because early Notch1 activation in keratinocytes induces keratinocyte differentiation and represses the DDR. These results indicate that an ATP2C1/NOTCH1 axis might be critical for keratinocyte function and cutaneous homeostasis, suggesting a plausible model for the pathological features of Hailey-Hailey disease.

Reflectance confocal microscopy for scarring and non-scarring alopecia real-time assessment.

Clinical management of alopecia represents one of the major issues in dermatology. Scalp biopsies are not easily accepted because of the high bleeding and sensitive anatomical area. Trichoscopy is routinely used for diagnosis of alopecia, but in several cases lack to provide sufficient information on the status of the disease. Recently, reflectance confocal microscopy demonstrated its usefulness for the evaluation of several inflammatory skin condition and preliminary reports about alopecia have been proposed in the literature. The aim was to identify the confocal features characterizing scarring and non-scarring alopecia. Reflectance confocal microscopy from 86 patients affected by scarring (28 lichen planopilaris and 9 lupus erythematosus) and non-scarring alopecia (30 androgenic alopecia and 19 alopecia areata), were retrospectively, blinded evaluated. Good concordance between different readers on the confocal criteria has been assessed. Statistical significant features, specific for scarring alopecia and non-scarring alopecia have been identified. In this study, data on reflectance confocal microscopy features useful for the differential diagnosis between scarring and non-scarring alopecia have been identified. Further studies focusing on the use of this non-invasive technique in the therapeutic follow-up and distinction of sub-entities of alopecia are still required.

Porphyria cutanea tarda in an HCV-positive liver transplant patient: a case report.

INTRODUCTION: Porphyria cutanea tarda (PCT) is the most common type of porphyria. The strong association between PCT and hepatitis C virus (HCV) infection is well established. Although antiviral treatment of chronic hepatitis C may improve PCT in some cases, de novo onset of PCT has been observed in patients under- going peginterferon/ribavirin treatment. We present a rare case of a genotype 3 HCV-positive liver transplant recipient who developed PCT during antiviral treatment and discuss its probable etiopathogenesis. CASE PRESENTATION: A genotype 3 HCV-positive liver transplant recipient, a 42-year-old man, was treated with peginterferon alfa-2a (180 µg/week) combined with ribavirin (1,200 mg/day) for recurrence of HCV infection after liver transplantation. He presented with hyperferritinemia but tested negative for genetic hemochromatosis (C282Y and H63D mutations). During antiviral therapy, he developed skin lesions on his hands characterized by vesicles and erosions consistent with PCT. PCT was confirmed by skin biopsy and elevated urinary uroporphyrin levels (1,469 mg/24 h). He was treated with chloroquine (200 mg) twice weekly, resulting in gradual regression of the skin lesions. Antiviral treatment was stopped after 48 weeks, and the patient achieved a sustained virological response. In conclusion, we report an extremely rare case of PCT in a genotype 3 HCV-positive liver transplant patient treated with antiviral therapy. We believe that the combination of HCV genotype 3 infection; hemolysis due to ribavirin treatment; and increased plasma levels of cytokines, such as IL-6 and TNFα, could have altered the patient's iron metabolism and thus caused PCT.

Low clinical recurrence and procedure benefits following treatment of common atrial flutter by electrogram-guided hot spot focal cryoablation.

BACKGROUND: The study sought to evaluate whether electrogram-aided identification of hot spot targets produces additional clinical and/or procedure benefits when using a non-traditional focal cryo ablation method to treat common atrial flutter. METHODS: A preliminary study identified a specific electrogram criterion (e.g., a stimulus to onset of electrogram time of 74 [+/- 5] ms) that produced successful cryo testing plus subsequent cryoablation with demonstrable bi-directional isthmus block created at intervention site. In the present study, 26 consecutive patients with symptomatic common atrial flutter were ablated with a 9FR 8 mm tip cryo catheter using electrogram-aided identification of hot spot targets with a stimulus to onset of electrogram time of > or =70 ms. Outcomes measured were bi-directional isthmus block at intervention, symptom and conduction recurrence at 3 month follow-up, symptom recurrence at 6 month follow-up, and procedure characteristics. RESULTS: Acute success rate at intervention was 100%. The percentage of patients with symptom recurrence by 3 month follow-up was 4.5% and no additional patients had arrhythmia symptoms documented by 12 month follow-up. Repeat electrophysiological study (EPS) at 3 month follow-up identified 44% of patients with conduction recurrence. The mean +/- SD number of cryo tests and ablations were 11 +/- 9 and 2 +/- 1, respectively. Procedure, fluoroscopy and cryoapplication times were 77 +/- 29 min, 11 +/- 7 min, and 28 +/- 11 min, respectively. CONCLUSIONS: A high acute success rate, plus low long-term clinical recurrence rate and procedure benefits may be achieved with electrogram-aided identification of hot spots for focal cryo ablation treatment of common atrial flutter using a 9FR 8 mm tip cryo catheter. The population of patients who were asymptomatic and had demonstrated conduction recurrence on repeat EPS at 3 month follow-up require close scrutiny over the long-term to ascertain whether they eventually experience arrhythmic symptoms. However, should these patients remain symptom-free over the long-term it would suggest that the entire isthmus may not be needed to support symptomatic common atrial flutter.

Comparison between a 7 French 6 mm tip cryothermal catheter and a 9 French 8 mm tip cryothermal catheter for cryoablation treatment of common atrial flutter.

BACKGROUND: Larger tipped cryothermal catheters may deliver efficacy and procedure benefits in the treatment of patients with atrial flutter. OBJECTIVE: To compare 7 French 6 mm and 9 French 8 mm tip cryothermal catheters (Freezor, Xtra or Freezor, MAX, CryoCath Technologies Inc., Kirkland, Canada) in terms of acute and chronic efficacy, and procedure characteristics in the treatment of atrial flutter. METHODS: This non-randomized clinical investigation determined bi-directional isthmus block at intervention, procedure characteristics, and symptom and conduction recurrence rates post procedure in consecutive patients with symptomatic atrial flutter ablated either with the 7 French 6 mm tip cryothermal catheter (n = 43) at -75 degrees C for 4 minutes or the 9 French 8 mm tip cryothermal catheter (n = 51) at -75 degrees C for 8 minutes. RESULTS: Clinical data showed a higher acute success rate for the larger tipped catheter (100% vs. 88%). Symptom recurrence rates were 0% for both catheters at 3, 6, and 9 month follow-up. Conduction recurrence rates were similar for both catheters on repeat electrophysiological study at 3 months post procedure (35% vs. 32%). Procedure benefits were fewer cryotests (20 +/- 17 vs. 26 +/- 21) and ablations (4 +/- 4 vs. 12 +/- 18), and shorter procedure (80 +/- 61 min vs. 87 +/- 48 min), fluoroscopy (14 +/- 9 min vs. 24 +/- 10 min), and cryoapplication times (37 +/- 18 min vs. 44 +/- 23 min) with the larger tipped catheter. There were no adverse events reported. CONCLUSIONS: Clinical results showed differences in catheter performance that favoured the larger tipped catheter. However, increased acute success rate did not translate into reduced conduction recurrence rate post ablation, although clinical recurrence was completely absent long-term.

Long-term efficacy of cryo catheter ablation for the treatment of atrial flutter: results from a repeat electrophysiologic study.

OBJECTIVES: We investigated the long-term efficacy of cryo ablation for treatment of atrial flutter. BACKGROUND: To our knowledge, no study has assessed the long-term efficacy of cryo ablation by assessing both symptom and conduction recurrence. METHODS: A total of 45 consecutive patients with symptomatic atrial flutter were ablated with a 7-F, 6-mm-tip, quadripolar cryo catheter (Freezor Xtra, CryoCath Technologies Inc., Kirkland, Canada). Electrophysiologic studies (EPS) were performed with diagnostic catheters. Cryo ablation was at -75 degrees C for 4 min, beginning at the inferior rim of the coronary sinus os and creating a posterior line to the Eustachian ridge. Safety, bi-directional isthmus block at intervention, and recurrence at three, six, and nine months post procedure were assessed. RESULTS: There were no adverse events reported. All patients were free of discomfort on cryo energy delivery. The acute success rate at intervention was 87%. Follow-up data from 39 acutely successful patients showed 27 (69%) without conduction recurrence on repeat EPS at three months, and none (0%) had symptom recurrence documented by Holter monitoring, electrocardiogram, and/or patient diary records at three, six, and nine months follow-up. CONCLUSIONS: Our experience with a new 7-F, 6-mm-tip, quadripolar cryo catheter yielded a fairly high success rate at intervention, an excellent safety profile, and a good chronic success rate in terms of symptom recurrence. However, further monitoring is necessary to determine whether all asymptomatic patients continue to remain free of symptoms, given the small pool of patients demonstrated to have conduction recurrence.

Cryothermal ablation treatment of atrial flutter--experience with a new 9 French 8 mm tip catheter.

BACKGROUND: Cardiac cryoablation has been used to successfully treat a variety of arrhythmias. OBJECTIVE: This study documents our experience with a new 9 French (FR) 8 mm cryocatheter for ablation treatment of symptomatic atrial flutter. METHODS: A total of 77 consecutive patients with symptomatic atrial flutter were treated. Electrophysiological studies (EPS) were performed with diagnostic catheters and ablation was performed with a 9FR, 8 mm tip, quadripolar cryocatheter (Freezor MAX catheter, CryoCath Technologies Inc., Kirkland, Canada). Cryoablation at -75 degrees C for 8 minutes was performed, beginning at the inferior rim of the coronary sinus (CS) os and creating a posterior line to the Eustachian ridge. Safety, bidirectional isthmus block at intervention, and recurrence at 3 months post procedure were assessed. RESULTS: There were no adverse events reported. All patients remained free of discomfort on cryoenergy delivery. The acute success rate at intervention was 96% for all patients and 100% for those with common atrial flutter. Follow-up data from 47 patients showed 33 (70%) patients without conduction recurrence on repeat EPS at 3 months. Although, 1 (2%) patient had both symptom and conduction recurrence. Data available from 53 acutely successful patients at 6 month clinical follow-up showed that 48 (91%) patients were asymptomatic and 5 (9%) patients had recurrence documented by ECG and/or patient diary records. CONCLUSIONS: Our experience with a new 9FR, 8 mm tip, quadripolar cryocatheter yielded a high success rate at intervention and an excellent safety profile. Although repeat EPS at 3 months post ablation identified conduction recurrence in 30% of patients, at 6 month clinical follow-up only 9% of patients had recurrence. Further monitoring is necessary to assess whether the relatively low recurrence rate observed at 6 month clinical follow-up is maintained over the long term.