[Noninvasive impedance method of determining left ventricular filling pressure]

Impedance chest plethysmograms (IPG) were recorded simultaneously with intraventricular pressure curves before and after ventriculography in 36 patients with chronic coronary heart disease. Phono- and apex cardiograms were recorded simultaneously with the 1st IPG derivative. The analysis of the tracings established criteria for determining the duration of isometric relaxation phase (IRP) from the 1st IPG derivative. The comparison between the IRPIPG and left-ventricular filling pressure (LVFP) values obtained by direct measurement, demonstrated a close correlation (r = 0.896) and suggested a simple formula for non-invasive LVFP determination.