Efficacy and safety of zero-fluoroscopy ablation for supraventricular tachycardias. Use of optional contact force measurement for zero-fluoroscopy ablation in a clinical routine setting.

BACKGROUND: Conventional catheter ablation of cardiac arrhythmias is associated with radiation risks for patients and laboratory personnel. Widespread use of zero-fluoroscopic catheter ablation in clinical routine is limited by safety concerns. This study investigated the feasibility of zero-fluoroscopy catheter ablation using a three-dimensional mapping system and optional catheter contact force technology for an all-comers collective. PATIENTS AND METHODS: The study comprised 184 patients; 91 patients, including 29 pediatric patients, underwent a zero-fluoroscopic electrophysiology (EP) study using the EnSite NavX system with real-time visualization of all electrodes. These patients were matched to a control group, which was treated using fluoroscopy in the same period. Inclusion criteria were documented supraventricular tachycardia or a history of symptomatic paroxysmal supraventricular tachycardia. Transseptal access, if necessary, was achieved under transesophageal echocardiographic guidance for ablation of left-sided arrhythmias. Radiofrequency (using optional contact force measurement) or a cryotechnique was used for ablation. RESULTS: We observed no major acute complications. There were no significant differences between the two groups in the follow-up period. CONCLUSION: Zero-fluoroscopic catheter ablation is generally feasible in right-sided cardiac arrhythmias. Safety concerns regarding left atrial substrates or children can be overcome with optional real-time contact force measurement.

Characterization of Biostable Atomic Layer Deposited (ALD) Multilayer Passivation Coatings for Active Implants.

The next generation of flexible, electrically active implants, such as brain implants or retina chips require a flexible, biostable as well as biocompatible passivation, ensuring a degradation-free usage for long time periods on the order of several years. Until today, these passivations are prepared mostly by polyimides or parylene, both of which are water vapor permeable to a certain degree. To remedy this deficiency, Atomic Layer Deposited (ALD) thin films are characterized regarding their electrical passivating features under conditions of accelerated aging, such as elevated temperatures in a liquid environment. The initial electrical passivation by various ALD deposited multilayers, combining alternating thin Al2O3 and TiO2 layers is the goal of this research as well as the stability of these layers under induced degradation. Such layers, in combination with a parylene passivation, would ensure a water vapor impermeable and biocompatible coating.

Electrical properties of a light-addressable microelectrode chip with high electrode density for extracellular stimulation and recording of excitable cells.

A light-addressable microelectrode chip with 3600 TiN electrodes was fabricated. Amorphous silicon (a-Si:H) serves as a photo conductor. The electrodes on the chip are addressed by a laser spot and electrical properties of the system are determined. DC measurements show a dark to bright dynamic of 10(6)-10(7). The AC impedance dynamic @ 1 kHz/100 mV and thus the signal-to-noise-ratio is determined to 60. This value is quite sufficient for electrophysiological measurements. For the first time, recordings from cardiac myocytes are reported using the principle of light-addressing. Measurements were done with a standard laser scan microscope (Zeiss LSM 410).

Patch-clamping of primary cardiac cells with micro-openings in polyimide films.

Patch-clamping is a powerful method for investigating the function and regulation of ionic channels. Currently, great efforts are being made to automate this method. As a step towards this goal, the feasibility of patch-clamping primary cells with a microscopic opening in a planar substrate was tested. Using standard microfabrication and ion beam technology, small-diameter openings (2 and 4 microm) were formed in polyimide films (thickness 6.5 microm). Single cells (sheep Purkinje heart cells, Chinese hamster ovary cells) in a suspension were positioned on top of the opening and sucked towards the opening to improve adhesion of the cell to the planar substrate, hence increasing the seal resistance. Voltage/current measurements yielded a median seal resistance of 1.3 Mohms with 4 microm openings (n=24) and 26.0 Mohms with 2 microm openings (n = 75), respectively. With 2 microm openings, successful loose-patch recordings of TTX-sensitive inward currents and action potentials in sheep Purkinje heart cells (n = 18) were made. In rare cases, gigaseals (n = 4) were also measured, and a whole-cell configuration (n = 1) could be established. It was concluded that the simple planar patch approach is suitable for automated loose-patch recordings from cells in suspension but will hardly be suitable for high-throughput whole-cell patch-clamping with high-resistance seals.

Production of wood decay enzymes, loss of mass, and lignin solubilization in wood by diverse tropical freshwater fungi.

In vitro production of cellulase and xylanase was common among diverse freshwater ascomycetes and their hyphomycetous anamorphs. Production of enzymes involved in lignin degradation was rare. Most isolates were capable of causing mass loss in angiosperm wood, although values were low, at approximately 10% during a 24-week period. A few isolates caused higher mass loss of up to 26.5%, and five of these were shown to solubilize significant amounts of lignin. This is the first report of lignin solubilization by freshwater fungi. Torula herbarum (hyphomycete) and Ophioceras dolichostomum (ascomycete) produced indices of lignin solubilization equivalent to those of terrestrial white-rot basidiomycetes. In all cases wood decay was 2.2- to 3-fold higher in exposed rather than submerged conditions.