[Possibilities of Predicting Peak Oxygen Consumption in Patients With Chronic Heart Failure According to the 6­Minute Walk Test].

AIM: To determine the correlation between the results of the 6-minute walk test (6MWT) and peak oxygen consumption (VO2peak) for populations of patients with chronic heart failure with pronounced clinical and demographic differences; to study a possibility of indirect measurement of VO2peak based on the results of 6MWT using the formulas available from the literature. MATERIAL AND METHODS: Two databases were analyzed: 50 patients included in the AEROFIT study (group A), and 31 patients from the Almazov National Medical Research Center (group B). The inclusion criteria were the availability of data from the cardiopulmonary stress test and the 6MWT. The possibility of predicting VO2peak was calculated based on the results of 6MWT using the formulas reported in the literature (L. P. Cahalin et al., 1996; R. M. Ross et al., 2010; R. A. Adedoyin et al., 2010). The predictive accuracy of the models was assessed using the coefficient of determination (R2). The relationship between functional and clinical-demographic indicators was assessed using the Pearson or Spearman correlation analysis. RESULTS: The study groups differed significantly in all parameters, except for the proportion of men and the mean VO2peak. Group B patients were 20 years younger than group A patients, had a lower left ventricular ejection fraction (24.06±7.75 and 41.52±10.48 %, respectively; p<0.001), and covered a 130 m shorter distance in the 6MWT. Despite the absence of a significant difference in VO2peak between groups A and B (13.6 and 13.1 ml / kg / min, respectively; p=0.6581), 61 % of group B patients and 20% of group A belonged to Weber functional class IV. In group A, the 6MWT distance correlated closely with VO2peak (R=0.78; p<0.01) and weakly with age (R=0.4) and body mass index (R=0.3). In group B, the 6MWT distance correlated only with VO2peak (R=0.77; p<0.01). For group A, the R.M. Ross et al. model demonstrated high accuracy in determining the mean VO2peak value with a 0.06% prediction error normalized to measured VO2peak. For group B, none of the models showed satisfactory predictive accuracy. The Ross and Cahalin models showed the best coefficients of determination for groups A and B: Group A, Ross et al. (R2=0.58) and Cahalin et al. (R2=0.59); Group B, Ross et al. (R2=0.59) and Cahalin et al. (R2=0.6). CONCLUSION: In two groups of patients with a statistically insignificant difference in the mean values of VO2peak, the mean values of 6MWT distance were significantly different, although these indicators correlated closely. The VO2peak prediction models showed satisfactory accuracy for estimation of mean VO2, but poor accuracy for estimation of individual values. A better predictive accuracy is determined by similar clinical and demographic characteristics between the training and testing populations, and likely also by models based on larger, more diversified populations.

[Red cell distribution width as a predictor of impaired exercise capacity in patients with heart failure].

Aim    To test a hypothesis that increased values of red cell distribution width (RDW) in patients with chronic heart failure (CHF) can be related with low exercise tolerance.Material and methods    102 patients were evaluated who had CHF with mid-range and reduced left ventricular ejection fraction (LV EF) without anemia (72% men, mean age 66±10.2 years). Cardiopulmonary stress test (CPST), echocardiography, 6­min walk test (6MWT), blood count, and measurements of N-terminal pro-brain natriuretic peptide (NT-pro-BNP) and serum iron were performed.Results    The average LV EF was 39±8.7 %; the peak oxygen consumption (VO2peak) was 13.7±4.8 ml /kg /min; and the median NT-pro-BNP was 595.3 pg /ml (Q1-3 1443-2401). RDW variables, including the RDW coefficient of variation (RDW-CV) and RDW standard deviation (RDW-SD), were not significantly related with serum iron or hemoglobin concentrations. A one-factor linear regression analysis showed a significant correlation of VO2peak with RDW-SD (р=0.039). A multivariate linear regression analysis with adjustments for LV EF, hemoglobin concentration, and age did not reveal any significant correlation of VO2peak with RDW variables. The distance covered in the 6MWT was significantly associated with RDW-CV both in the one-factor analysis and with adjustments for LV EF, hemoglobin and serum iron concentrations, and age.Conclusion    This study showed that high RDW values in CHF patients without anemia predicted low exercise tolerance regardless of the age, LV systolic function, and hemoglobin and serum iron concentrations. A 16% increase in RDW-CV significantly decreased the likelihood of covering a distance longer than 360 m during 6 min.

[Physical training in patients with chronic heart failure: level of involvement, as well as psychosocial, anamnestic and iatrogenic factors that determine the motivation to practice].

Introduction Physical exercise (PE) is a necessary part in the treatment of patients with chronic heart failure (CHF), which is stated in the European Society of Cardiology guidelines and the Russian Heart Failure Society guidelines. However, this type of non-drug treatment is still not sufficiently used in HF patients in Russia.Aim To study the current involvement of HF patients in PT and to describe psychosocial factors that influence the patients' willingness to exercise and potential barriers and motivations for PE.Methods This study was designed as an in-moment survey. Patients with CHF who visited clinics in 7 cities of the Russian Federation in 2018 as a part of European Heart Failure Awareness Days were provided with a self-administered questionnaire containing questions about their social and educational status, attitude to PT as a method of treatment, and factors motivating and demotivating them to participation in training sessions. The survey participants were also asked a question about their source of information about exercise in HF. Physicians filled in the items describing HF clinical manifestations (left ventricular ejection fraction (EF) and HF functional class (FC)). Code numbers were used for further identification of the participants and to protect their confidentiality. Statistical analysis was performed with the StatXcat-8 program. Limits of exact confidence intervals (CIs) were provided both for fractions and parameters of polynomial distribution. CI limits for differences and fractions were calculated using MOVER. Age was analyzed using the PAST program.Results The study included 560 patients with HF; 52 % of them were women (mean age, 64; 95 % CI: 63-65 years). Women were 3 years older than men (95 % CI: 1.3-4.9 years). 501 (89.5 %) patients had FC II-III; 265 (49 %) patients had HF with low EF. 350 (62 %) patients had comorbidities: 41.4 % of patients had diabetes mellitus and 25.4 % of patients had arthritis. Only 91 (17 %) patients reported exercising. Patients younger than 65 exercised significantly more frequently than older ones (odds ratio (OR), 1.7, 95 % CI: 1.0-2.7, р<0.001). Patients with higher education had better chances to be involved in PT or were more anxious to start training (OR, 2.7; 95 % CI: 1.6-4.7, р<0.001). The capability for influencing the disease was the major motivation for PT for both sexes. Probability of this answer was 48 % (95 % CI: 33-61) for men and 46 % (95 % CI: 29-63) for women. 62 % of patients indicated poor health as the major barrier for participation in PT. Only 55 % of patients knew that PT could be a method for HF treatment, and only 50 % were informed about that by their physician.Conclusion The factors that positively influence the willingness to exercise include male sex, higher level of education, younger age, and better perception of the own health condition. 62 % of patients indicated poor health as the major barrier for participation in training. On the whole, the awareness of patients about PT benefits for health in HF was low. To our opinion, this was a serious factor of the extremely low involvement of patients in PT. Only 55 % of patients knew that PT could be a method for HF treatment, and, furthermore, only 50 % of patients received this information from their physicians.

Alterations of the respiratory system in heart failure.

The review discusses mechanisms for the development of the pathology of the respiratory system in patients with CHF, such as various types of periodic respiration, pulmonary hypertension due to the pathology of the left chambers of the heart, and remodeling of the respiratory musculature. The role of chemo- and baroreceptors of the carotid zone, as well as the hyperactivation of the respiratory muscle metaboreflex in the development of the pathology of the respiratory system, and the mediated exacerbation of CHF are discussed.

[Experimental investigation of general toxiology of antioxidant eyedrops davicol].

Authors examined the toxicity of antioxidant eye drops--davikoli. Antioxidants play important role in protecting the body from the formation of very dangerous substances referred to as free radicals. On the basis of honey an eye drops with high antioxidant activity--davicoli has been developed. The ocular effects of eye drops have been measured in a placebo-controlled double-blind study in 44 mice, 44 rats, 40 sea pigs and 20 chinchilla rabbits. Preclinical study revealed that eye drops davikoli are safe and non-toxic. During the investigation anti-inflammation features of eye drops davicoli was discovered.

[Relation between pharmacokinetics of an antibiotic in ocular fluids and the method of administration and dosage form of gentamycin]. / Farmakokinetika antibiotika v zhidkostiakh glaza v zavisimosti ot sposoba vvedeniia i lekarstvennoi formy gentamitsina.

The experiments on rabbits with intraocular infection provided determination of the optimal route and regimen of gentamicin administration in various dosage forms. Gentamicin sulfate made in the USSR was used. It was shown that during instillations of 0.3 per cent eye drops, gentamicin did not penetrate into the intraocular fluid. The ophthalmic drug films (ODF) containing 0.5 mg gentamicin per film provided better penetration of the antibiotic into the eye cavity in the concentrations in the ocular fluid active only against the most gentamicin sensitive microbial strains. Therefore, the use of the ODF containing gentamicin may be recommended for the treatment of intraocular infections caused by gentamicin sensitive organisms. When the antibiotic was administered subconjunctively in a dose of 20 mg, its therapeutic concentrations were mainly detectable in the anterior chamber fluid. Therefore, the use of this administration route was first of all rational in intraocular infections of the anterior part of the eye. The antibiotic should be used in such cases at least twice a day. The therapeutic concentrations of gentamicin active against the majority of the microbial strains were attained in the vitreous body only on intravitreal administration. The high therapeutic levels of gentamicin in the vitreous body after its injection in a dose of 0.4 mg were recorded for at least 4 days. Therefore, for the treatment of endophthalmitis the intravitreal route of gentamicin administration is of the greatest practical importance.