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Biomedical subjects

V I Gridnev

Publications and source records attributed to V I Gridnev.

8 recordsLinked to original sources
PubMed2005

[Assessment of the state of myocardial contractility based on analysis of heart rate variability during exercise tests].

AIM: To elucidate stability of 0.1 Hz component of heart rate variability (HRV) spectrum in patients with different state of myocardial contractile function during bicycle exercise tests under controlled breathing with 10 sec period. MATERIAL: Male patients with class II-III effort angina and either abnormal myocardial contractile function (n=45, age 51.0+/-2.5 years, left ventricular ejection fraction <50%), or without disturbances of myocardial contractility (n=35, age 52+/-6 years, ejection fraction > 60%). METHODS: All patients underwent Doppler echocardiography and submaximal exercise tests with initial loads 25 W. Registration of series of RR-intervals was done during controlled breathing with 10 sec periods (0.1 Hz) for 5 min at rest and exercise (25 W work load). Depth and balance of phases of controlled breathing were similar to those of spontaneous breathing. Analysis of the heart rate variability was made on the basis of auto-regression algorithm. RESULTS: Stability of 0.1 Hz component of the heart rate variability spectrum to low-level exercise correlated with the severity of depression of myocardial contractility.

Echocardiography, Doppler, Pulsed↗
PubMed2004

[Prognostication of coronary atherosclerosis for selection of tactics of management of patients with ischemic heart disease].

AIM: To create an artificial neural network for prognostication of coronary atherosclerosis and thus selection of patients requiring invasive interventions. METHODS AND RESULTS: Efficacy of prognostication made by a physician and by a model was compared basing on probabilistic estimates with consideration of individual level of risk. Nineteen clinical and instrumental parameters were entered into multifactorial analysis. These parameters included data from anamnesis, results of instrumental examination, a priori likelihood of ischemic heart disease, and magnitude of individual risk of cardiovascular events. The following factors were selected as significant at neural network prognostication of coronary atherosclerosis: result of exercise test, typical angina, history of myocardial infarction, ECG-signs of left ventricular hypertrophy and a priori likelihood of ischemic heart disease. Basing on these data two stage scheme of prognostication of coronary atherosclerosis was suggested. CONCLUSION: Thus artificial neural network suitable for screening and selection of patients for invasive interventions in ambulatory practice was created. Prognosis made with the use of artificial neural network was 1.5-3 times more accurate than that made by a physician.

Chi-Square Distribution↗
PubMed2003

Synchronization between main rhythmic processes in the human cardiovascular system.

For the cases of spontaneous respiration and paced respiration with a fixed frequency and linearly increasing frequency, we investigate synchronization between three main rhythmic processes governing the cardiovascular dynamics in humans, namely, the main heart rhythm, respiration, and the process whose fundamental frequency is close to 0.1 Hz. The analysis of the experimental records reveals synchronous regimes of different orders n:m between all the three main rhythms. The influence of the regime of breathing and the magnitude of heart rate variability on the degree of synchronization is considered.

Adult↗
PubMedDate not supplied

[The investigation of the synchronization between rhythms in the human cardiovascular system from time series of R-R-intervals].

We demonstrated that, from the sequence of R-R intervals, it is possible to calculate the instantaneous phases and instantaneous frequencies of the main rhythmic processes governing the cardiovascular dynamics in humans, namely, the main heart rhythm, respiration, and the process of slow regulation of blood pressure with basic frequency close to 0.1 Hz. For the cases of spontaneous respiration and paced respiration with a fixed frequency, the synchronization between the rhythms of the cardiovascular system was investigated based on the analysis of only the time series of R-R intervals. It is shown that the main heart rhythm and the rhythm of low-frequency regulation of blood pressure can be synchronized with respiration.

Cardiovascular Physiological Phenomena↗