Normal and abnormal circadian profiles of heart autonomic balance, evaluated by time-related common indicator of heart rate variability.

Objective: Heart rate variability (HRV) is an universally accepted method for assessing the heart autonomic balance (HAB). At the same time HRV is a highly specific method, but with a low sensitivity to the cardiovascular diseases (CVD). We found that HRV indices may be applied to obtain differentiated characteristics of the HAB for individual CVD.

Transthoracic impedance study with large self-adhesive electrodes in two conventional positions for defibrillation.

External defibrillation requires the application of high voltage electrical impulses via large external electrodes, placed on selected locations on the thorax surface. The position of the electrodes is one of the major determinants of the transthoracic impedance (TTI) which influences the intracardiac current flow during electric shock and defibrillation success. The variety of factors which influence TTI measurements raised our interest to investigate the range of TTI values and the temporal TTI variance during long-term application of defibrillation self-adhesive electrodes in two conventional positions on the patient's chest--position 1 (sub-clavicular/sub-axillar position) and position 2 (antero-posterior position).

Dataset of manually measured QT intervals in the electrocardiogram.

Background: The QT interval and the QT dispersion are currently a subject of considerable interest. Cardiac repolarization delay is known to favor the development of arrhythmias. The QT dispersion, defined as the difference between the longest and the shortest QT intervals or as the standard deviation of the QT duration in the 12-lead ECG is assumed to be reliable predictor of cardiovascular mortality.

Diagnostic value of the RR-variability indicators for mild hypertension.

Experimental and clinical studies have shown that an imbalance of the cardiovascular system autonomous regulation can lead to complications. In this study we have aimed to investigate whether the vegetative control of patients with mild hypertension is disturbed and to evaluate the power of the RR-variability indicators to detect the disturbances. RR variability has been studied in two groups of individuals: normotensive and mildly hypertensive.