External electrical and pharmacological cardioversion for atrial fibrillation, atrial flutter or atrial tachycardias:a network meta-analysis

BackgroundAtrial fibrillation (AF) is the most frequent sustained arrhythmia. Cardioversion is a rhythm control strategy torestore normal/sinus rhythm, and can be achieved through drugs (pharmacological) or a synchronized electricshock (electrical cardioversion).ObjectivesTo assess the efficacy and safety of pharmacological and electrical cardioversion for AF.Search methodsWe searched CENTRAL, MEDLINE, Embase, Conference Proceedings Citation Index-Science (CPCI-S) andthree trials registers (ClinicalTrials.gov, WHO ICTRP and ISRCTN) on 14 February 2023.Selection criteriaWe included randomised controlled trials (RCTs) at individual patient level. Patient populations were aged ≥18years with AF of any type and duration, atrial flutter or other sustained related atrial arrhythmias, not occurring asa result of reversible causes.Data collection and analysisWe used standard Cochrane methodology to collect data and performed a network meta-analysis using thestandard frequentist graph-theoretical approach using the netmeta package in R. We used GRADE to assess thequality of the evidence which we presented in in our summary of findings with a judgement on certainty. Wecalculated differences using risk ratios (RR) and 95% confidence intervals (CI) as well as ranking treatmentsusing a P-score. We assessed clinical and statistical heterogeneity and split the networks for the primaryoutcome and acute procedural success due to concerns about violating the transitivity assumption.Main resultsWe included 112 RCTs (139 records), from which we pooled data from 15,968 patients. Average age was 47 to72 years and proportion of male patients was 38%-92%.79 trials were considered high risk of bias for at least one domain, 32 had no high risk of bias domains, but hadat least one domain classified as uncertain risk, and one study was considered low risk for all domains.For paroxysmal AF (35 trials), when compared to Placebo, AA/AP BTE incremental cardioversion (RR: 2.42;95%CI 1.65 to 3.56), quinidine (RR: 2.23; 95%CI 1.49 to 3.34), ibutilide (RR: 2.00; 95%CI 1.28 to 3.12),propafenone (RR: 1.98; 95%CI 1.67 to 2.34), amiodarone (RR: 1.69; 95%CI 1.42 to 2.02), sotalol (RR: 1.58;95%CI 1.08 to 2.31) and procainamide (RR: 1.49; 95%CI 1.13 to 1.97) likely result in a large increase inmaintenance of sinus rhythm until hospital discharge or end of study follow-up (certainty of evidence: moderate).The effect size was larger for AA/AP incremental and was progressively smaller for the subsequent interventions.Despite low certainty of evidence Antazoline may result in a large increase (RR: 28.60; 95%CI 1.77 to 461.30) inthis outcome. Similarly, low certainty evidence suggests a large increase on this outcome for flecainide (RR: 2.17;95%CI 1.68 to 2.79), vernakalant (RR: 2.13; 95%CI 1.52 to 2.99), and magnesium (RR: 1.73; 95%CI 0.79 to 3.79)on this outcome.For persistent AF (26 trials), one network was created for electrical cardioversion and showed that whencompared to AP BTE incremental energy with patches, AP BTE maximum energy with patches (RR 1.35, 95%CI1.17 to 1.55) likely results in large increase and Active compression AP BTE incremental energy with patches(RR: 1.14, 95%CI 1.00 to 1.131) likely results in an increase in maintenance of sinus rhythm at hospital dischargeor end of study follow-up (certainty of evidence: high). Use of AP BTE incremental with paddles (RR: 1.03, 95%CI0.98 to 1.09; certainty of evidence: low) may lead to a little increase, and AP MDS Incremental paddles (RR: 0.95,95%CI 0.86 to 1.05; certainty of evidence: low) may lead to a little decrease in efficacy. On the other hand, APMDS incremental energy using patches (RR: 0.78, 95%CI 0.70 to 0.87), AA RBW incremental energy withpatches (RR: 0.76, 95%CI 0.66 to 0.88), AP RBW incremental energy with patches (RR: 0.76, 95%CI 0.68 to0.86), AA MDS incremental energy with patches (RR: 0.76, 95%CI 0.67 to 0.86) and AA MDS incremental energywith paddles (RR: 0.68, 95%CI 0.53 to 0.83) probably result in a decrease on this outcome when compared to APBTE incremental energy with patches (certainty of evidence: moderate). The network for pharmacologicalcardioversion showed that Bepridil (RR: 2.29, 95%CI 1.26 to 4.17) and Quindine (RR: 1.53, (95%CI 1.01 to 2.32)probably result in large increase in maintenance of sinus rhythm at hospital discharge or end of study follow-upwhen compared to amiodarone (certainty of evidence: moderate). Dofetilide (RR: 0.79, 95%CI 0.56 to 1.44),Sotalol (RR: 0.89, 95%CI 0.67 to 1.18), Propafenone (RR: 0.79, 95%CI 0.50 to 1.25) and Pilsicainide (RR: 0.39,95%CI 0.02 to 7.01) may result in a reduction of this outcome when compared to amiodarone, but certainty ofevidence is lowFor atrial flutter (14 trials) a network could be created only for antiarrhythmic drugs. Using Placebo as thecommon comparator, ibutilide (RR: 21.45, 95%CI 4.41 to 104.37), propafenone (RR: 7.15, 95%CI 1.27 to 40.10),dofetilide (RR: 6.43, 95%CI 1.38 to 29.91), and sotalol (RR: 6.39, 95%CI 1.03 to 39.78) probably result in a largeincrease in maintenance of sinus rhythm at hospital discharge or end of study follow-up (certainty of evidence:moderate), and procainamide (RR: 4.29, 95%CI 0.63 to 29.03), flecainide (RR 3.57, 95%CI 0.24 to 52.30) andvernakalant (RR: 1.18, 95%CI 0.05 to 27.37) may result in a large increase of maintenance of sinus rhythm athospital discharge or end of study follow-up at (certainty of evidence: low) All tested electrical cardioversionstrategies for atrial flutter had very high efficacy (97.9% to 100%).Mortality (14 deaths) and Stroke or systemic embolism (3 events) at 30 days was extremely low.Data on quality of life were scarce and of uncertain clinical significance. No information was available regardingheart failure readmissions. Data on duration of hospitalization was scarce, low quality, & could not be pooled.Authors' conclusionsDespite the low quality of evidence, this systematic review provides important information on electrical andpharmacological strategies to help patients and physicians deal with AF and atrial flutter.Assessing the patient comorbidity profile, antiarrhythmic drug onset of action & side effect profile vs. need for aphysician with experience in sedation, or anaesthetics support, for electrical cardioversion are key aspects whenchoosing the cardioversion method

Mechanical degradation of a polyurethane elastomer

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCEBibliography: leaves 121-126.by Joey Lou Mead.Ph.D

Electrical Properties Enhancement of Carbon Nanotube Yarns by Cyclic Loading

Carbon nanotube yarns (CNTYs) possess low density, high conductivity, high strength, and moderate flexibility. These intrinsic properties allow them to be a preferred choice for use as conductive elements in high-performance composites. To fully exploit their potential as conductive reinforcing elements, further improvement in their electrical conductivity is needed. This study demonstrates that tensile cyclic loading under ambient conditions improves the electrical conductivity of two types of CNTYs. The results showed that the electrical resistance of untreated CNTYs was reduced by 80% using cyclic loading, reaching the resistance value of the drawn acid-treated CNTYs. Scanning electron microscopy showed that cyclic loading caused orientation and compaction of the CNT bundles that make up the CNTYs, resulting in significantly improved electrical conductivity of the CNTYs. Furthermore, the elastic modulus was increased by 20% while preserving the tensile strength. This approach has the potential to replace the environmentally unfriendly acid treatment currently used to enhance the conductivity of CNTYs

3D-Printable PP/SEBS Thermoplastic Elastomeric Blends: Preparation and Properties

Currently, material extrusion 3D printing (ME3DP) based on fused deposition modeling (FDM) is considered a highly adaptable and efficient additive manufacturing technique to develop components with complex geometries using computer-aided design. While the 3D printing process for a number of thermoplastic materials using FDM technology has been well demonstrated, there still exists a significant challenge to develop new polymeric materials compatible with ME3DP. The present work reports the development of ME3DP compatible thermoplastic elastomeric (TPE) materials from polypropylene (PP) and styrene-(ethylene-butylene)-styrene (SEBS) block copolymers using a straightforward blending approach, which enables the creation of tailorable materials. Properties of the 3D printed TPEs were compared with traditional injection molded samples. The tensile strength and Young’s modulus of the 3D printed sample were lower than the injection molded samples. However, no significant differences could be found in the melt rheological properties at higher frequency ranges or in the dynamic mechanical behavior. The phase morphologies of the 3D printed and injection molded TPEs were correlated with their respective properties. Reinforcing carbon black was used to increase the mechanical performance of the 3D printed TPE, and the balancing of thermoplastic elastomeric and mechanical properties were achieved at a lower carbon black loading. The preferential location of carbon black in the blend phases was theoretically predicted from wetting parameters. This study was made in order to get an insight to the relationship between morphology and properties of the ME3DP compatible PP/SEBS blends

Properties and dispersion of EPDM/modified-organoclay nanocomposites

Elastomers show improved properties when reinforced with nanoclay at low filler loadings, but dispersion of the clay is difficult in non-polar polymers, such as ethylene propylene diene monomer (EPDM). In this work several compatibilization approaches were studied, including the addition of EPDM modified with maleic anhydride (EPDM-g-MA) and the use of organoclay modified with maleic anhydride-grafted liquid vinyl polybutadiene (LVPB-g-MA). The use of LVPB-g-MA-modified organoclay increased the degree of dispersion as measured by X-ray diffraction, giving increased thermal stability and modulus, and decreased swelling. Flame resistance was poorer for the EPDM/LVPB-g-MA-modified organoclay system compared to the unmodified EPDM/organoclay compound.The resistivity of the nanoclay-filled composites was lower than the reference EPDM compound, but dielectric properties for the LVPB-g-MA modified organoclay were similar to the reference

Stretchable Conductive Tubular Composites Based on Braided Carbon Nanotube Yarns with an Elastomer Matrix

We report an innovative approach to creating stretchable conductive materials composed of a tubular shell made from braided carbon nanotube yarns (CNTYs) embedded in an elastomeric matrix. For stretchable electronics, both mechanical properties and electrical conductivities are of interest. Consequently, both the mechanical behavior and electrical conductivities under large deformations were investigated. A new hyperelastic composite model was developed to predict the large deformation response to applied stress for a braid in a tubular elastomer composite. The composite demonstrated a hyperelastic response due to the architecture of the braid, and the behavior was affected by the braiding angle, braid modulus, and volume fraction of fibers. The elastomer matrix was considered a neo-Hookean material and represented by the Yeoh model. An interaction parameter was proposed to account for the effect of the elastomer/braid cooperative restriction as observed in experimental and calculated results. This novel approach enabled the determination of the constitutive behavior of the composite in large deformations (>150%), taking into account the elastomer and yarn properties and braid configurations. The model exhibited good agreement with the experimental results. As the CNTYs are conductive, a stretchable conductive composite was obtained having a resistivity of 5.01 × 10–4 and 5.67 × 10–5 Ω·cm for the 1-ply and 4-ply composites, respectively. The resistivity remained constant through cyclic loading under large deformations in tension until mechanical failure. The material has potential for use in stretchable electronics applications