Surgical Treatment of Chronic Atrial Fibrillation—Unipolar Radiofrequency Ablation versus Cryoablation, and Left Atrial versus Bi-atrial Maze Procedures

AbstractThis study evaluated the efficacy of the left atrial Maze procedure (Lt-maze) and unipolar radiofrequency (RF) ablation as an additional procedure for the surgical treatment of atrial fibrillation (AF) in patient with other cardiac disease.Methods and Results: The Maze procedure was performed in 100 consecutive patients with AF: Lt-maze, 71 patients; bi-atrial Maze (Bi-maze), 29 patients. Cryoablation and RF ablation were used in 82 and 18 patients, respectively. There were no in-hospital or early deaths. Fourteen patients (14%) experienced postoperative complications. Seventy-five patients (75%) were in sinus rhythm (SR) at discharge, 4 patients were in junctional rhythm, and 21 patients had AF. Two patients (2%) required permanent pacemaker implantation. The AF-free rate at discharge was 79%, and the AF-free rate at hospital discharge did not differ significantly between cryoablation and unipolar RF ablation (78% and 82%, respectively). There were no significant differences between these two groups in operative results, in terms of the aortic cross-clamp time, cardiopulmonary bypass time, and AF-free rate, with the AFfree rate not differing significantly in those who received single valve surgery (73% and 75% in the cryoablation and unipolar RF ablation groups, respectively). The equipment cost of the two procedures differed greatly: 14,000 yen/patient for cryoablation and 250,000 yen/patient for RF ablation. The AF-free rate did not differ significantly between Lt-maze (76%) and Bi-maze (86%), including in those who received single valve surgery (72% and 79%, respectively). The significant predictors of AF recurrence in a univariate analysis were left atrial diameter (p = 0.03), duration of AF (p < 0.01), fibrillation amplitude on ECG (p = 0.02), and cardiothoracic ratio (p < 0.01), with the duration of preoperative AF being the only significant predictor of AF in a multivariate analysis.Conclusion: In this series, unipolar RF ablation for the Maze procedure was as effective as cryoablation at eliminating AF, and Lt-maze and Bi-maze were equipotent at restoring SR at discharge

Characteristics of Kiso Ultra-Violet Excess Galaxies

We examined the general characteristics of the Kiso Ultra-violet Excess Galaxies (KUGs). We present for the first time the quantitative expressions for the criteria of the KUGs; the boundary color separating the KUGs from the non-KUGs is (B-V)_{T} = 0.74 and the KUG degrees of UV strength are found to correlate with the mean (B-V)_{T} colors. We investigate the nature of the KUGs, a sample of blue galaxy population, and show that (1) about a half of the KUGs are spiral galaxies with Sb to Scd, (2) the KUGs are biased to late-type galaxies and include early-type galaxies with young star populations, and (3) the KUGs are preferably found among less luminous galaxies with log L(B) < 10. The KUGs also contain the post-starburst galaxies, many of which are found among the blue galaxy population at intermediate redshifts. The analysis of the far-infrared data shows that a typical present-to-past star formation rate for a KUG is 0.4.Comment: Revised version of astro-ph/9706088, accepted manuscript for AJ; uuencoded gzip'ed tar'ed file containing 25 files; a manuscript (aasms4), 7 tables (aj_pt4), 17 PS figures; To be appeared in The Astronomical Journal, Vol. 114, No. 5 (1997 November issue

Regional cerebral tissue blood flow measured by the colored microsphere method during retrograde cerebral perfusion

AbstractBrain tissue blood flow was measured precisely by the colored microsphere method during retrograde cerebral perfusion in 10 normothermic mongrel dogs. The average tissue blood flow rates to the cerebral cortex, cerebral medulla, brain stem, cerebellum, and spinal cord during retrograde cerebral perfusion at 25 mm Hg of external jugular venous pressure were 10.5 ± 10.3, 4.2 ± 4.6, 11.1 ± 9.8, 12.3 ± 8.6, and 9.1 ± 5.8 ml/min per 100 gm, respectively. The brain was perfused wholly by retrograde cerebral perfusion without lateralization. Total cerebral blood flow was calculated as the sum total rates of blood flow to each area. Total cerebral blood flow during retrograde cerebral perfusion at 25 mm Hg was 7.8 ± 4.4 ml/min, which represented 3.5% ± 1.9% of whole body blood flow and one third of the total cerebral blood flow (28.0 ± 4.2 ml/min) during cardiopulmonary bypass at a flow rate of 1000 ml/min. Oxygen consumption and carbon dioxide elimination by the total cerebrum during retrograde cerebral perfusion at 25 mm Hg were 0.54 ± 0.23 ml/min and 34 ± 15 μmol/min, respectively, or 8.6% ± 3.6% and 7.0% ± 3.1% of the corresponding whole body value and represented about one third of that measured during cardiopulmonary bypass (1.21 ± 0.39 ml/min and 96 ± 15 μmol/min). Total cerebral blood flow, total cerebral oxygen consumption, and carbon dioxide elimination increased as the external jugular venous pressure increased from 15 to 25 mm Hg; however, no further increase occurred once the external jugular venous pressure exceeded 25 mm Hg. (J THORAC CARDIOVASC SURG 1995;109:772-9

Photometric Observations of Star Formation Activity in Early Type Spirals

We observationally study the current star formation activities of early type spiral galaxies. We construct a complete sample of 15 early type spirals having far-infrared (FIR) to optical B band luminosity ratios, L(FIR)/L(B), larger than the average of the type, and make their CCD imaging of the R and H-alpha bands. The equivalent widths of H-alpha emission increase with increasing L(FIR)/L(B), indicating that L(FIR)/L(B) can be an indicator of star formation for such early type spirals with star formation activities higher than the average. For all of the observed early type spirals, the extended HII regions exist at the central regions with some asymmetric features. H-alpha emission is more concentrated to the galactic center than the R band light, and the degree of the concentration increases with the star formation activity. We also analyze the relation between the star formation activities and the existence of companion galaxies in the sample galaxies and other bright early type spirals. No correlation is found and this suggests that the interaction is not responsible for all of the star formation activities of early type spirals.Comment: LaTex, 23 pages (2 tables included), plus 9 Postscript figures & 1 table. To be published in AJ (November issue

Life-Detection Technologies for the Next Two Decades

Since its inception six decades ago, astrobiology has diversified immensely to encompass several scientific questions including the origin and evolution of Terran life, the organic chemical composition of extraterrestrial objects, and the concept of habitability, among others. The detection of life beyond Earth forms the main goal of astrobiology, and a significant one for space exploration in general. This goal has galvanized and connected with other critical areas of investigation such as the analysis of meteorites and early Earth geological and biological systems, materials gathered by sample-return space missions, laboratory and computer simulations of extraterrestrial and early Earth environmental chemistry, astronomical remote sensing, and in-situ space exploration missions. Lately, scattered efforts are being undertaken towards the R&D of the novel and as-yet-space-unproven life-detection technologies capable of obtaining unambiguous evidence of extraterrestrial life, even if it is significantly different from Terran life. As the suite of space-proven payloads improves in breadth and sensitivity, this is an apt time to examine the progress and future of life-detection technologies.Comment: 6 pages, the white paper was submitted to and cited by the National Academy of Sciences in support of the Astrobiology Science Strategy for the Search for Life in the Univers

Optical Properties of (162173) 1999 JU3: In Preparation for the JAXA Hayabusa 2 Sample Return Mission

We investigated the magnitude-phase relation of (162173) 1999 JU3, a target asteroid for the JAXA Hayabusa 2 sample return mission. We initially employed the international Astronomical Union's H-G formalism but found that it fits less well using a single set of parameters. To improve the inadequate fit, we employed two photometric functions, the Shevchenko and Hapke functions. With the Shevchenko function, we found that the magnitude-phase relation exhibits linear behavior in a wide phase angle range (alpha = 5-75 deg) and shows weak nonlinear opposition brightening at alpha< 5 deg, providing a more reliable absolute magnitude of Hv = 19.25 +- 0.03. The phase slope (0.039 +- 0.001 mag/deg) and opposition effect amplitude (parameterized by the ratio of intensity at alpha=0.3 deg to that at alpha=5 deg, I(0.3)/I(5)=1.31+-0.05) are consistent with those of typical C-type asteroids. We also attempted to determine the parameters for the Hapke model, which are applicable for constructing the surface reflectance map with the Hayabusa 2 onboard cameras. Although we could not constrain the full set of Hapke parameters, we obtained possible values, w=0.041, g=-0.38, B0=1.43, and h=0.050, assuming a surface roughness parameter theta=20 deg. By combining our photometric study with a thermal model of the asteroid (Mueller et al. in preparation), we obtained a geometric albedo of pv = 0.047 +- 0.003, phase integral q = 0.32 +- 0.03, and Bond albedo AB = 0.014 +- 0.002, which are commensurate with the values for common C-type asteroids.Comment: 27 pages, 4 figure, accepted for publication in the Astrophysical Journa