Assessment of cardiac time intervals by wavelet transform of the impedance cardiogram.

Background: Impedance cardiography (ICG) is an inexpensive, noninvasive technique for estimating hemodynamic parameters. ICG can be used to obtain the ejection fraction of the left atrium and to monitor systolic time intervals. Traditional ICG technique does not enable unambiguous detection of the left ventricle ejection time (LVET) and the time relationships between specific marker points.

Assessment of left ventricular systolic function and diastolic time intervals by the bioimpedance polyrheocardiographic system.

In order to detect left ventricular systolic function and diastolic time intervals using a new improved bioimpedance polyrheocardiographic system (BPCS), 110 healthy subjects and 128 patients with myocardial infarction were examined. Twenty-four simultaneous measurements of cardiac output by thermodilution and BPCS were performed in 11 patients with complicated acute left ventricular failure. Studies demonstrated a high degree of correlation (r = 0.

[A rheographic method of determining the duration of the diastolic phases].

Difference thoracic rheography (recording the curve of a signal by subtracting a differential rheogram of the symmetrical portions of chest halves) was used to develop a procedure to define diastole phases, which established periods of relaxation, rapid and slow left ventricular filling, the duration of a systole of the left and right atria, and the time of rapid left ventricular filling velocity peak. The testing of the procedure in 25 healthy males showed that difference thoracic rheogram may be recorded both at rest and movements of a patient during a graded isometric leg loading, which is particularly important to make a comprehensive assessment of the diastolic function of the heart.

[Rheocardiographic evaluation of left-ventricular contractility in the measured isometric pedal test].

Central hemodynamic parameters were assessed by tetrapolar chest rheography during rationed isometric pedal stress exposure in 54 normal subjects and 24 angina patients. The relationship between left-ventricular contractility and the magnitude of increasing static effort at different steps of stress exposure was examined. In normal subjects, the increase in static effort was shown to affect significantly left-ventricular contractile capacity, left-ventricular performance index and left-ventricular contractile index, and has no effect on the myocardial contractility index.