Clinical and Procedural Effects of Transitioning to Contact Force Guided Ablation for Atrial Fibrillation.

Background: A major innovation in atrial fibrillation (AF) ablation has been the introduction of contact force (CF) sensing catheters. Objective: To evaluate procedural and clinical effects of transitioning to CF-guided AF ablation. Methods: Consecutive AF ablation patients were studiedduring the period of time of transitioning from a non-CF to CF sensing catheter. Procedural data recorded was total radiofrequency time, time to isolate the left pulmonary veins (LPVs), and time to isolate the right pulmonary veins (RPVs). Clinically, the 3 and 12-month maintenance of sinus rhythm was noted and compared by: paroxysmal vs. persistent AF; CT scan LA volume more or less than 150 cc; CHA2DS2VASC more or less than 2; and LVEF more or less than 55%. Safety data was recorded as well. Results: Total ablation times were shorter (113 vs.146 min, p=0.011)when using the CF catheters compared to non-CF ablations. This was driven by a decrease in both LPV (46 vs.72 min, p\u3c0.001) and RPV time (54 vs. 75 min, p=0.002).The use of CF catheter did not change the overall percentage of patients in sinus rhythm at 3 and 12-months of follow up. However, sinus rhythm was more frequent at 12 months with CF ablation inpatients with an LA volume of more than 150 cc when compared to non-CF ablation (84.6% and 52.4%, p=0.03). There was no difference in outcomes with stratification by CHA2DS2VASC score or LVEF. No significant difference in complications was noted. Conclusions: For AF ablation, the initial use of CF-sensing technology reduced procedure times with similar overall sinus rhythm maintenance at 3 and 12 months. CF improved 12-month outcomes in patients with an enlarged LA

The Velocity Distribution of the Nearest Interstellar Gas

The bulk flow velocity for the cluster of interstellar cloudlets within about 30 pc of the Sun is determined from optical and ultraviolet absorption line data, after omitting from the sample stars with circumstellar disks or variable emission lines and the active variable HR 1099. Ninety-six velocity components towards the remaining 60 stars yield a streaming velocity through the local standard of rest of -17.0+/-4.6 km/s, with an upstream direction of l=2.3 deg, b=-5.2 deg (using Hipparcos values for the solar apex motion). The velocity dispersion of the interstellar matter (ISM) within 30 pc is consistent with that of nearby diffuse clouds, but present statistics are inadequate to distinguish between a Gaussian or exponential distribution about the bulk flow velocity. The upstream direction of the bulk flow vector suggests an origin associated with the Loop I supernova remnant. Groupings of component velocities by region are seen, indicating regional departures from the bulk flow velocity or possibly separate clouds. The absorption components from the cloudlet feeding ISM into the solar system form one of the regional features. The nominal gradient between the velocities of upstream and downstream gas may be an artifact of the Sun's location near the edge of the local cloud complex. The Sun may emerge from the surrounding gas-patch within several thousand years.Comment: Typographical errors corrected; Five tables, seven figures; Astrophysical Journal, in pres

A systematic correlation between two-dimensional flow topology and the abstract statistics of turbulence

Velocity differences in the direct enstrophy cascade of two-dimensional turbulence are correlated with the underlying flow topology. The statistics of the transverse and longitudinal velocity differences are found to be governed by different structures. The wings of the transverse distribution are dominated by strong vortex centers, whereas, the tails of the longitudinal differences are dominated by saddles. Viewed in the framework of earlier theoretical work this result suggests that the transfer of enstrophy to smaller scales is accomplished in regions of the flow dominated by saddles.Comment: 4 pages, 4 figure

Structure of Plasma Heating in Gyrokinetic Alfvénic Turbulence

We analyze plasma heating in weakly collisional kinetic Alfv\'en wave (KAW) turbulence using high resolution gyrokinetic simulations spanning the range of scales between the ion and the electron gyroradii. Real space structures that have a higher than average heating rate are shown not to be confined to current sheets. This novel result is at odds with previous studies, which use the electromagnetic work in the local electron fluid frame, i.e. $\mathbf{J} \!\cdot\! (\mathbf{E} + \mathbf{v}_e\times\mathbf{B})$, as a proxy for turbulent dissipation to argue that heating follows the intermittent spatial structure of the electric current. Furthermore, we show that electrons are dominated by parallel heating while the ions prefer the perpendicular heating route. We comment on the implications of the results presented here.Comment: 5 pages, 3 figure

Atrioventricular Nodal Reentrant Tachycardia Ablation with a Power-controlled, Contact-force Catheter.

Radiofrequency catheter ablation is a safe and effective treatment option for atrioventricular nodal reentrant tachycardia (AVNRT). A nonirrigated ablation catheter used in a temperature-controlled mode is traditionally used for AVNRT ablation due to the shallow lesion depth required for successful slow-pathway ablation. In this case, a nonirrigated ablation catheter established inadequate lesions to ablate the slow pathway successfully. The adoption of an irrigated contact-force ablation catheter used in a power-controlled mode was necessary to provide higher power and possibly create a deeper lesion to ablate the slow pathway successfully, thus eliminating AVNRT inducibility in this patient

Trends in permanent pacemaker implantation in the United States from 1993 to 2009: increasing complexity of patients and procedures.

OBJECTIVES: This study sought to define contemporary trends in permanent pacemaker use by analyzing a large national database. BACKGROUND: The Medicare National Coverage Determination for permanent pacemaker, which emphasized single-chamber pacing, has not changed significantly since 1985. We sought to define contemporary trends in permanent pacemaker use by analyzing a large national database. METHODS: We queried the Nationwide Inpatient Sample to identify permanent pacemaker implants between 1993 and 2009 using the International Classification of Diseases-Ninth Revision-Clinical Modification procedure codes for dual-chamber (DDD), single-ventricular (VVI), single-atrial (AAI), or biventricular (BiV) devices. Annual permanent pacemaker implantation rates and patient demographics were analyzed. RESULTS: Between 1993 and 2009, 2.9 million patients received permanent pacemakers in the United States. Overall use increased by 55.6%. By 2009, DDD use increased from 62% to 82% (p \u3c 0.001), whereas single-chamber ventricular pacemaker use fell from 36% to 14% (p = 0.01). Use of DDD devices was higher in urban, nonteaching hospitals (79%) compared with urban teaching hospitals (76%) and rural hospitals (72%). Patients with private insurance (83%) more commonly received DDD devices than Medicaid (79%) or Medicare (75%) recipients (p \u3c 0.001). Patient age and Charlson comorbidity index increased over time. Hospital charges ($2011) increased 45.3%, driven by the increased cost of DDD devices. CONCLUSIONS: There is a steady growth in the use of permanent pacemakers in the United States. Although DDD device use is increasing, whereas single-chamber ventricular pacemaker use is decreasing. Patients are becoming older and have more medical comorbidities. These trends have important health care policy implications

16-year trends in the infection burden for pacemakers and implantable cardioverter-defibrillators in the United States 1993 to 2008.

OBJECTIVES: We analyzed the infection burden associated with the implantation of cardiac implantable electrophysiological devices (CIEDs) in the United States for the years 1993 to 2008. BACKGROUND: Recent data suggest that the rate of infection following CIED implantation may be increasing. METHODS: The Nationwide Inpatient Sample (NIS) discharge records were queried between 1993 and 2008 using the 9th Revision of the International Classification of Diseases (ICD-9-CM). CIED infection was defined as either: 1) ICD-9 code for device-related infection (996.61) and any CIED procedure or removal code; or 2) CIED procedure code along with systemic infection. Patient health profile was evaluated by coding for renal failure, heart failure, respiratory failure, and diabetes mellitus. The infection burden and patient health profile were calculated for each year, and linear regression was used to test for changes over time. RESULTS: During the study period (1993 to 2008), the incidence of CIED infection was 1.61%. The annual rate of infections remained constant until 2004, when a marked increase was observed, which coincided with an increase in the incidence of major comorbidities. This was associated with a marked increase in mortality and in-hospital financial charges. CONCLUSIONS: The infection burden associated with CIED implantation is increasing over time and is associated with prolonged hospital stays and high financial costs

Simulating Three-Dimensional Hydrodynamics on a Cellular-Automata Machine

We demonstrate how three-dimensional fluid flow simulations can be carried out on the Cellular Automata Machine 8 (CAM-8), a special-purpose computer for cellular-automata computations. The principal algorithmic innovation is the use of a lattice-gas model with a 16-bit collision operator that is specially adapted to the machine architecture. It is shown how the collision rules can be optimized to obtain a low viscosity of the fluid. Predictions of the viscosity based on a Boltzmann approximation agree well with measurements of the viscosity made on CAM-8. Several test simulations of flows in simple geometries -- channels, pipes, and a cubic array of spheres -- are carried out. Measurements of average flux in these geometries compare well with theoretical predictions.Comment: 19 pages, REVTeX and epsf macros require

Procedural and Clinical Outcomes of Transitioning to High Power Short Duration Guided Ablation for Atrial Fibrillation

Introduction: High-power short-duration (HPSD; 50W for up to 15s) ablation is a novel way to use a contact force-sensing catheter optimized for power-controlled radiofrequency ablation of atrial fibrillation (AF). Our goal was to compare the procedural and clinical outcomes of AF ablation with HPSD to previous ablation methods used, including standard-power standard duration (SPSD; 20-25W, up to 60s) and temperature-controlled non-contact (TCNC; 20-40W, up to 60s). Methods: Procedural and clinical data was from consecutive cases of patients with paroxysmal or persistent AF undergoing pulmonary vein isolation with HPSD, TCNC and SPSD between 7/1/13 to 11/1/19. A total of 171 patients were studied (76 HPSD, 44 TCNC, 51 SPSD). Results: There was no difference in age, sex, or AF type between groups. Radiofrequency ablation time was shorter when comparing HPSD to SPSD (71 vs 101min; p\u3c0.01), HPSD to TCNC (71 vs 146min; p\u3c0.01), and SPSD to TCNC groups (101 vs 146min; p\u3c0.01). There was no difference in sinus rhythm maintenance after 3 or 12-months between groups overall, and when stratified by AF type, left atrial volume, CHA2DS2-VASc score, or left ventricular EF. There was a numerical difference in safety with no adverse events in HPSD (0/76 in HPSD vs 1/51 in SPSD vs 3/44 in TCNC; p=0.06). Discussion: AF ablation utilizing HPSD ablation reduced procedure times with similar sinus rhythm maintenance compared to SPSD and TCNC ablation. This supports the movement to replace SPSD and TCNC with the novel HPSD approach. Further research is warranted with larger populations and longer follow-up