Radiation grafted poly(vinylidene fluoride)-graftpolystyrene sulfonic acid membranes for fuel cells: Structure-property relationships

Structure-property relationships for poly(vinylidene fluoride)-graft-polystyrene sulfonic acid (PVDF-g-PSSA) fuel cell membranes prepared by a single step method involving radiation-induced grafting of sodium styrene sulfonate (SSS) onto electron beam (EB) irradiated poly(vinylidene fluoride) (PVDF) films were established. The physico-chemical properties of the membranes such as ion exchange capacity, water swelling and proton conductivity were correlated with the degree of grafting (G, %) and the structural changes taking place in the membrane matrix during the preparation procedure. The variation in the crystallinity and the thermal stability of membranes was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The membranes were found to undergo substantial structural changes in forms of ionic sites increase, hydrophilicity enhancement, hydrophobicity reduction and crystallinity decrease with the variation in G (%) and the preparation method. The structural and thermal properties of the obtained membranes were also compared with their counterparts prepared by a conventional two-steps method i.e. radiation induced grafting of styrene onto EB irradiated PVDF films followed by sulfonation. The PVDF-g-PSSA membranes obtained by a single-step method were found to have superior properties compared to those obtained by the conventional two-steps method

Wireless LV endocardial stimulation for cardiac resynchronisation: 12 month experience of clinical efficacy and clinical events

Cardiolog

The durability of pulmonary vein isolation using the visually guided laser balloon catheter: Multicenter results of pulmonary vein remapping studies

Background: The visually guided laser ablation (VGLA) catheter is a compliant, variable-diameter balloon that delivers laser energy around the pulmonary vein (PV) ostium under real-time endoscopic visualization. While acute PV isolation has been shown to be feasible, limited data exist regarding the durability of isolation. Objective: We sought to determine the durability of PV isolation following ablation using the balloon-based VGLA catheter. Methods: The VGLA catheter was evaluated in patients with paroxysmal atrial fibrillation (3 sites, 10 operators). Following transseptal puncture, the VGLA catheter was advanced through a 12-F deflectable sheath and inflated at the target PV ostium. Under endoscopic guidance, the 30\uc2\ub0 aiming arc was maneuvered around the PV and laser energy was delivered to ablate tissue in a contiguous/overlapping manner. At \ue2\u88\ubc3 months, all patients returned for a PV remapping procedure. Results: In 56 patients, 202 of 206 PVs (98%) were acutely isolated. At 105 \uc2\ub1 44 (mean \uc2\ub1 SD) days, 52 patients returned for PV remapping at which time 162 of 189 PVs (86%) remained isolated and 32 of 52 patients (62%) had all PVs still isolated. On comparing the operators performing <10 vs <10 procedures, the durable PV isolation rate and the percentage of patients with all PVs isolated were found to be 73% vs 89% (P =.011) and 57% vs 66% (P =.746), respectively. After 2 procedures and 12.0 \uc2\ub1 1.9 months of follow-up, the drug-free rate of freedom from atrial fibrillation was 71.2%. Conclusions: In this multicenter, multioperator experience, VGLA resulted in a very high rate of durable PV isolation with a clinical efficacy similar to that of radiofrequency ablation

Pulmonary Vein Isolation With a Novel Multielectrode Radiofrequency Balloon Catheter That Allows Directionally Tailored Energy Delivery: Short-Term Outcomes From a Multicenter First-in-Human Study (RADIANCE)

Background: Balloon catheters facilitate pulmonary vein (PV) isolation, but current technology is limited by either a single ablative element, potentially leading to over-ablation of thin and under-ablation of thick tissue, or prolonged procedure times. Visualized by electroanatomical mapping, a novel compliant radiofrequency balloon catheter with 10 irrigated, flexible electrodes can simultaneously and independently deliver energy. Herein, we evaluated the feasibility, safety, and short-term efficacy of this radiofrequency balloon in a multicenter, single-arm, first-in-human study. Methods: Paroxysmal atrial fibrillation patients underwent PV isolation with the radiofrequency balloon delivered over-the-wire with a deflectable 13.5F sheath. Radiofrequency energy is delivered simultaneously from all electrodes-up to 30 s posteriorly and 60 s anteriorly. Esophageal temperature was monitored in all patients; the esophagus was also mechanically deviated in 10 patients. Results: At 4 sites, 39 patients were treated by 9 operators. The radiofrequency balloon isolated all targeted PVs (152/152), 79.6% with a single application. Electrical reconnection occurred in only 7/150 PVs (4.7%) on adenosine/isoproterenol challenge. Mean procedure, balloon dwell, and fluoroscopy times were 101.6, 40.5, and 17.4 min, respectively. Esophagogastroduodenoscopy revealed asymptomatic esophageal erythema in 5 patients. Phrenic nerve palsy occurred in a patient in whom phrenic pacing was inadvertently omitted. At 3 months, imaging revealed no PV stenosis, and early atrial arrhythmia recurrence occurred in only 10/39 (25.6%) patients. Conclusions: The compliant radiofrequency balloon can directionally tailor energy delivery for efficient, effective, and reasonably safe acute PV isolation