Background-Pulmonary vein (PV) isolation is a promising new treatment for atrial fibrillation (AF). We hypothesized that isolation of large areas around both ipsilateral PVs with verification of conduction block is more effective than the isolation of each individual PV. Methods and Results-A total of 110 patients, 67 with paroxysmal AF and 43 with persistent AF, were randomly assigned to undergo either isolation of each individual PV or isolation of large areas around both ipsilateral PVs. The isolation of each individual PV was an electrophysiologically guided, ostial segmental ablation with a 64-pole basket catheter or a 20-pole circular mapping catheter (group I). Isolation of large areas was performed around the 2 ipsilateral veins with a nonfluoroscopic navigation system and a circular 20-pole mapping catheter for verification of conduction block (group II). In both groups, an irrigated-tip ablation catheter (25 to 35 W) was used to achieve complete isolation. Procedure and ablation times were longer in group II, whereas fluoroscopic time was significantly shorter (PՅ0.001). After a follow-up period of 15Ϯ4 months, 27 patients in group I (49%) and 37 patients in group II (67%) remained free of symptoms of AF and had no AF or atrial flutter during repetitive Holter monitoring without antiarrhythmic drug treatment after a single procedure (PՅ0.05). Conclusions-The rate of success was significantly higher and fluoroscopy times were significantly lower in the group with large isolation areas around both ipsilateral PVs than in those who underwent individual PV isolation. (Circulation.

At 2-year follow-up, the risk of significant pulmonary vein stenosis/occlusion after radiofrequency catheter ablation of refractory atrial fibrillation with conventional mapping and ablation technology was 28%. Distal ablations inside smaller pulmonary veins should be avoided because of the higher risk of stenosis than ablation at the ostium.

Background-Ostial pulmonary vein (PV) isolation by radiofrequency (RF) catheter ablation can cure patients with atrial fibrillation (AF); however, this procedure carries the risk of PV stenosis. The aim of this study was to assess the feasibility of a new mapping and navigation technique using a multipolar basket catheter (BC) for PV isolation in patients with refractory AF and to analyze its safety with regard to PV stenosis at long-term follow-up. Methods and Results-We studied 55 patients (mean age, 53Ϯ11 years; 40 male) with drug-refractory AF (paroxysmal, nϭ37; persistent, nϭ18). A 64-pole BC was placed transseptally into each of the accessible PVs. By use of a nonfluoroscopic navigation system, the ablation catheter was guided to the BC electrodes at the PV ostium, with earliest activation during sinus rhythm. RF was delivered by use of maximum settings of temperature at 50°C and power at 30 W. The end point of the procedure was the complete elimination of all distal and fragmented ostial PV potentials. Of 165 targeted veins, 163 were successfully isolated with a mean RF duration of 720Ϯ301 seconds per vein. At 1-year follow-up, 62% of the patients were in sinus rhythm without antiarrhythmic drugs. Contrast-enhanced magnetic resonance angiography revealed 2 PV stenoses of Ͼ25% out of 165 treated vessels. Conclusions-The use of a multipolar BC allowed effective and safe PV isolation by combining 3D mapping and navigation. At 1-year follow-up, 62% of the patients were in sinus rhythm without antiarrhythmic drugs, and the incidence of relevant diameter reduction of the treated PVs was 1

The in-plane component of the wavefield provides valuable information about media properties from seismology to nondestructive testing. A new compact scanning laser ultrasonic interferometer collects light scattered away from the angle of incidence to provide the absolute ultrasonic displacement for both the out-of-plane and an in-plane components. This new system is tested by measuring the radial and vertical polarization of a Rayleigh wave in an aluminum half-space. The estimated amplitude ratio of the horizontal and vertical displacement agrees well with the theoretical value. The phase difference exhibits a small bias between the two components due to a slightly different frequency response between the two processing channels of the prototype electronic circuitry.

We present a fundamentally new approach to laboratory acoustic and seismic wave experimentation that enables full immersion of a physical wave propagation experiment within a virtual numerical environment. Using a recent theory of immersive boundary conditions that relies on measurements made on an inner closed surface of sensors, the output of numerous closely spaced sources around the physical domain is continuously varied in time and space. This allows waves to seamlessly propagate back and forth between both domains, without being affected by reflections at the boundaries between both domains, which enables us to virtually expand the size of the physical laboratory and operate at much lower frequencies than previously possible (sonic frequencies as low as 1 kHz). While immersive boundary conditions have been rigorously tested numerically, here we present the first proof of concept for their physical implementation with experimental results from a one-dimensional sound wave tube. These experiments demonstrate the performance and capabilities of immersive boundary conditions in canceling boundary reflections and accounting for long-range interactions with a virtual domain outside the physical experiment. Moreover, we introduce a unique high-performance acquisition, computation, and control system that will enable the real-time implementation of immersive boundary conditions in three dimensions. The system is capable of extrapolating wave fields recorded on 800 simultaneous inputs to 800 simultaneous outputs, through arbitrarily complex virtual background media with an extremely low total system latency of 200 μs. The laboratory allows studying a variety of long-standing problems and poorly understood aspects of wave physics and imaging. Moreover, such real-time immersive experimentation opens up exciting possibilities for the future of laboratory acoustic and seismic experiments and for fields such as active acoustic cloaking and holography.