How the new technologies and tools will change the electrophysiology of the future.

Novel technologies and therapies are evolving rapidly in the field of electrophysiology and cardiac ablation, particularly with the aim of improving the management of atrial fibrillation (AF) where pharmacologic treatment fails. High-power short-duration radiofrequency (RF) ablation, in association with the optimized cooling process of the electrode-tissue interface, is one of the most promising approaches for treating durable lesions and pulmonary vein isolation (PVI). Cryo energy, laser, and RF current are examples of novel tools used by competitive balloon catheter platforms and these tools are specifically created to properly promote an effective PVI. Specific mention deserves to be made on the linear array ablation with ultra-low temperature cryoablation that appears promising for durable lesions. It is needless to remind here about the novel evolving energy source in the form of pulsed electrical field (PFA), which results in an irreversible electroporation of myocardial tissue, sparing the surrounding tissue, and thus, apparently with a significant reduction of potential untoward effects. Furthermore, intensive research is in place to specifically investigate the activation pattern of AF so as to devise a patient-('tailored') target ablation, although with inhomogeneous results. Overall, it seems that technologies and therapies are evolving so rapidly than ever with the hope of achieving better long-term clinical results and an improved quality of life for our patients.

A new cryoenergy for ventricular tachycardia ablation: a proof-of-concept study.

INTRODUCTION: Lack of transmural lesion formation during radiofrequency (RF) ablation for ventricular tachycardia (VT) is an important determinant of arrhythmia recurrence. The aim of this proof-of-concept study was to evaluate safety and efficacy of a new and more powerful cryoablation system for ventricular ablation. METHODS AND RESULTS: Five healthy female sheep (59 ± 6 kg) underwent a surgical sternotomy for epicardial and endocardial access [endocardial access via right atrial appendage and left ventricular (LV) apex]. A cryoablation system with liquid nitrogen (IceCure) was used to create 3 min freezes at the right ventricle (RV). Left ventricular cryoablation was performed with either a 6 min or 2 × 4 min freezes. To assess safety, ablation was also performed on the mid left anterior descending artery and the proximal coronary sinus. A total of 45 lesions were created (RV epicardial, n = 12; LV epicardial, n = 18; RV endocardial, n = 7; LV endocardial, n = 8; LAD, n = 4; and CS, n = 4). The mean lesion volume was 5055 ± 92 mm3 (length: 32 ± 4.6 mm, width: 16.0 ± 6.4 mm, and depth: 11.2 ± 4.4 mm). Lesions were transmural in 28/45 (62%) and >10 mm in depth in 35/45 (78%). Of the endocardial lesions, 12/15 were transmural (80%). There was no benefit of the bonus freeze in LV lesions (6 vs. 2 × 4 min: 6790 ± 44 vs. 5595 ± 63 mm3; P = 0.44). All ablated vascular structures appeared macroscopically normal without acute stenosis. One animal died due to incessant Ventricular fibrillation (VF). CONCLUSION: Our results indicate that a more powerful cryoablation system is able to create large, transmural ventricular lesions from both the endocardium and the epicardium. The technology may hold potential for both surgical and catheter-based VT ablation in humans.

Salt accumulation and effects within foliage of Tilia × vulgaris trees from the street greenery of Riga, Latvia.

Green infrastructures within sprawling cities provide essential ecosystem services, increasingly undermined by environmental stress. The main objective in this study was to relate the allocation patterns of NaCl contaminants to injury within foliage of lime trees mechanistically and distinguish between the effects of salt and other environmental stressors. Using field material representative of salt contamination levels in the street greenery of Riga, Latvia, the contribution of salt contaminants to structural and ultrastructural injury was analyzed, combining different microscopy techniques. On severely salt-polluted and dystrophic soils, the foliage of street lime trees showed foliar concentrations of Na/Cl up to 13,600/16,750 mg kg-1 but a still balanced nutrient content. The salt contaminants were allocated to all leaf blade tissues and accumulated in priority within mesophyll vacuoles, changing the vacuolar ionic composition at the expense of especially K and Ca. The size of mesophyll cells and vacuoles was increased as a function of NaCl concentration, suggesting impeded transpiration stream. In parallel, the cytoplasm showed degenerative changes, suggesting indirect stress effects. Hence, the lime trees in Riga showed tolerance to the dystrophic environmental conditions enhanced by salt pollution but their leaf physiology appeared directly impacted by the accumulation of contaminants within foliage.