The relative importance of diet-related and waterborne effects of copper for a leaf-shredding invertebrate.

Copper (Cu) exposure can increase leaf-associated fungal biomass, an important food component for leaf-shredding macroinvertebrates. To test if this positive nutritional effect supports the physiological fitness of these animals and to assess its importance compared to waterborne toxicity, we performed a 24-day-bioassay in combination with a 2×2 factorial design using the amphipod shredder Gammarus fossarum and a field-relevant Cu concentration of 25 µg/L (n = 65). Waterborne toxicity was negligible, while gammarids fed leaves exposed to Cu during microbial colonization exhibited a near-significant impairment in growth (∼30%) and a significantly reduced lipid content (∼20%). These effects appear to be governed by dietary uptake of Cu, which accumulated in leaves as well as gammarids and likely overrode the positive nutritional effect of the increased fungal biomass. Our results suggest that for adsorptive freshwater contaminants dietary uptake should be evaluated already during the registration process to safeguard the integrity of detritus-based ecosystems.

[Radiofrequency catheter ablation of ventricular tachycardias]. / Radiofrequenz-Katheterablation ventrikulärer Tachykardien.

Management of patients with ventricular tachycardia (VT) is often difficult. Drug therapy is often ineffective. Implantable cardioverter defibrillators (ICDs) can terminate VT episodes but do not prevent them. Radiofrequency (RF) catheter ablation can suppress arrhythmias in selected patients. However, the procedure is often challenging and success rates lower than for ablation of supraventricular tachycardias. The mapping and ablation approach depends on the VT mechanism. Monomorphic VT in patients without structural heart disease is referred to as idiopathic and has a focal origin. These VTs can be abolished by ablation in most of the patients. In VT due to reentry within an area of scar from an old myocardial infarction or cardiomyopathic process, critical parts of the circuit may be difficult to localize, rendering RF ablation challenging. In patients with monomorphic VT, prevention of VT recurrence can be achieved in 55% to 80% of patients. Multiple morphologies of VTs and circuits that are located deep in the endocardium are common problems that reduce efficacy. Furthermore, mapping to identify target regions for ablation can be more difficult if VT is rapid and not tolerated, or not inducible. Recently, multisite mapping of the arrhythmia substrate during sinus rhythm or multisite activation mapping of a few VT beats were shown to be effective for ablation of these "unmappable VTs". Bundle branch reentry tachycardia occur in patients with nonischemic cardiomyopathies, mostly valvular heart disease and can be successfully abolished with RF ablation of the right bundle. However, some of these patients may develop recurrences due to other types of VT. Recent technical developments have increased efficacy and simplified the approach of RF ablation of VT in patients with structural heart disease. However, long-term efficacy is not accurately predictable and implantation of an ICD is mandatory in most of the patients with severely depressed left ventricular function.