Purpose. The results of cryoballoon ablation (CBA) procedure have been mainly derived from studies conducted in experienced atrial fibrillation (AF) ablation centres. Here, we report on CBA efficacy and complications resulting from real practice of this procedure at both high- and low-volume centres. Methods. Among 62 Russian centres performing AF ablation, 15 (24%) used CBA technology for pulmonary vein isolation. The centres were asked to provide a detailed description of all CBA procedures performed and complications, if encountered. Results. Thirteen sites completed interviews on all CBAs in their centres (>95% of CBAs in Russia). Six sites were high-volume AF ablation (>100 AF cases/year) centres, and 7 were low-volume AF ablation. There was no statistical difference in arrhythmia-free rates between high- and low-volume centres (64.6 versus 60.8% at 6 months). Major complications developed in 1.5% of patients and were equally distributed between high- and low-volume centres. Minor procedure-related events were encountered in 8% of patients and were more prevalent in high-volume centres. Total event and vascular access site event rates were higher in women than in men. Conclusions. CBA has an acceptable efficacy profile in real practice. In less experienced AF ablation centres, the major complication rate is equal to that in high-volume centres.

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A single-stage bilateral conduction blockade of the vagus nerves (functional denervation) by constant anodal current was carried out in 13 dogs which are under anesthesia and 3-5 days after operation in chronic experiments. In anesthetized animals, "functional denervation" led to acceleration of the heart rhythm from 102.4+/-3.2 bmp to 123.8+/-4.4 bmp. In chronic dogs "functional denervation" led to transient stoppage of the heart--a preautomatic pause with duration of 2.7+/-0.2 sec. The heartbeats recommenced with the frequency of 89.0+/-3.4 bmp versus an initial rhythm of 118+/-1.5 bpm, i.e., a rhythm deceleration took place. We conclude that in a whole organism the heart rhythm pacemaker is determined by a brain level of the hierarchical system of rhythmogenesis, while the sinoatrial node plays the role of a latent pacemaker.

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Aim      To evaluate the diagnostic significance of clinical and demographic parameters for predicting a 2-year probability of ventricular tachyarrhythmias (VT) in patients with chronic heart failure and reduced left ventricular ejection fraction (CHFrLVEF).Material and methods  This single-center, prospective cohort study included 175 patients with CHFrLVEF who were implanted with a cardioverter defibrillator (CD). The endpoint was a CD-detected episode of VT. Patients were followed up for 2 years with visits at 3, 12, and 24 months after CD implantation.Results The primary endpoint was observed in 43 (24.4 %) patients at an average of 20.9 months (95 % confidence interval (CI), 20–21.9). The 2-year risk of fatal ventricular arrhythmias increased with detection of unstable VT (one-factor analysis, odds ratio (OR), 4.2; 95 % CI, 1.1–16.5; р=0.041; multifactor analysis, OR, 6.3; 95 % CI, 1.5–26.3; р=0.012) and with ischemic CHFrLVEF origin (one-factor analysis, OR, 2.2; 95 % CI, 1.1–4.5; p=0.021; multifactor analysis, OR, 2.5; 95 % CI, 1.2–5.1; р=0.018). In the presence of any type of atrial fibrillation (AF) in patients with non-ischemic CHFrLVEF, the probability of VT increased threefold (one-factor analysis, OR, 2.97; 95 % CI, 1.02–8.8; р=0.047; multifactor analysis, OR, 3.5; 95 % CI, 1.1–10.9; р=0.032).Conclusion      The presence of ischemic heart disease and unstable VT paroxysms can be included in the number of important clinical predictors of VT in patients with CHFrLVEF. In patients with non-ischemic CHF, the presence of AF is associated with a high risk of VT.