Cardiac performance measured by impedance cardiography and radionuclide angiography

Impedance cardiography is used for non-invasive determinations of stroke volume and myocardial oxygen balance predicted from diastolic Pressure Time Index (DPTI) as an estimation of oxygen supply and Systolic Pressure Time Index (SPTI) as an estimation of oxygen demand. The model which is described assesses the cardiac performance and is compared with previously known methods. In recent years the radionuclide technique for measurement of left ventricular ejection fraction (LVEF) has increased. A comparison has been made between impedance cardiography and the radionuclide angiography technique in order to determine the value of impedance cardiography during rapid changes in cardiac performance. Further previous studies have shown a good relationship between the values for impedance stroke volume and the thermodilution technique, and a very high correlation after individual analysis. The method should be suitable for relative measurements of stroke volume; however, the method appears of little value for estimation of absolute values. Our group has shown a fairly good correlation in cardiac performance in a comparative study between impedance cardiography and radionuclide angiography during prenalterol infusion. In conclusion, impedance cardiography is a method which simultaneously gives information about variations in cardiac stroke volume. Additional information is gained from the DPTI/SPTI - ratio, which can assess the myocardial oxygen balance and signify subendocardial underperfusion. The method may be considered as a valuable monitoring tool for repeated determinations of myocardial function.