Predictors of successful elimination of sinoatrial tachycardia (SAT) using radiofrequency current (RFC) were investigated in this report. Within 1991-1996 fourteen patients with SAT were subjected to electrophysiological study and radiofrequency catheter ablation (RFCA). Ten patients had sinoatrial reentrant tachycardia (SART), and four patients had chronic non-paroxysmal sinoatrial tachycardia (CNPSAT). The RFC (15-30 W, duration 10-30 sec) were applied during tachycardia in case of CNPSAT, and during sinus rhythm (SR) in case of SART. In 3 patients with SART RFC were delivered during tachycardia due to failing of RFC application, delivered during SR. During successful RFC attempts were noted: 1). In case of SART-transient development (3-6 sec) of SART (if RFC was delivered during SR), and acceleration of tachycardia rate with following termination of tachycardia (if application of RFC was performed during tachycardia); 2). In case of CNPSAT-transient development (4-7 sec) of low right atrial (3 patients) or junctional (1 patient) rhythm with rapid conversion to SR. All 14 patients have been free of tachycardia and have normal sinus node function during follow-up of 8-60 months. We conclude that predictors of successful elimination of SAT are: 1). In case of SART-acceleration of tachycardia rate before termination during RFC application (delivered during tachycardia), and transient development of SART during RFC application (delivered during SR); 2). In case of CNPSAT-transient development of low right atrial or junction rhythm (during application of RFC) with rapid conversion to SR.
For a long time fast reactors were regarded as unpromising for the production of radionuclides. At the same time, in our opinion, they exhibit good possibilities for producing artificial radioactive isotopes on account of the possibility of combining the production of different types of products (electricity + isotopes), the large volumes for installing targets, specifically, the existence of auxiliary breeding zones, and a high neutron-flux density.In Ref. 1, general approaches to obtaining the widely used 6~ and 14C nuclides in the screens of fast reactors were formulated. To increase the efficiency of the production of these isotopes, it was suggested that the spectrum of neutrons at the location of irradiation of the target be changed with the aid of a moderator --zirconium hydride. To this end, either a special irradiating apparatus should be developed or a subzone of a thermal-column type should be developed to replace part of the lateral breeding zone. In the limiting case, the entire lateral breeding zone can be oriented toward producing radionuclides. The computed production indicators turned out to be fairly good: the specific 6~ activity is 100 Ci/g and higher, and several MCi of a given isotope and up to i-2 kCi of t4c can be obtained in one year at the BN-600 reactor (Beloyar nuclear power plant). The computed data were confirmed in an experiment on the production of 6~ in the BN-350 reactor (Aktau, Kazakhstan) [2].The possibilities associated with the existence of a high neutron flux in fast reactors have nonetheless not been investigated adequately and are not used in full measure. For (anti)neutrino sources, which are studied in the present work, stringent requirements are characteristically imposed both on the overall activity of the source and on the specific activity of the main radionuclide. For this reason, we wish to point out that we are viewing the present work not only as a search for ways to solve the actual problem of producing specific sources for neutron physics and astrophysics, but also as the next step in isotope production in fast reactors, in the development of the ideas advanced in Refs. 1 and 2, and as an attempt to understand and evaluate the limiting possibilities of fast reactors for the production of isotopes with high specific activity.In this connection, we call attention to another method, characteristic for fast reactors, for producing radioactive isotopes with high specific activity --the use of threshold reactors with emission of charged particles, such as (n, c0 and (n, p). The drawback that the cross sections of these reactions are small can be compensated by increasing the mass of the irradiated target. Since in these reactions the nuclides of neighboring elements are formed, after irradiation the target nuclide can be separated from the main mass of the target by chemical methods, i.e. it can be obtained carrier-free. This increases substantially the specific activity of the source to values close to the limiting value for a pure monoisotope.(Anti)neutrino Sources...
Providing a better perfusion of the myocardiuln, translnyocardial revascularization with an Nd:YAG laser improves cardiac function and general condition of patients with ischemic heart disease.
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