[Systolic time intervals during increasing left ventricular filling pressure following extracorporeal circulation. A...

In 26 patients invasively measured haemodynamic parameters and impedance cardiographically determined systolic time intervals have been compared after open heart surgery with cardio-pulmonary bypass (aortic valve replacement, AVR (n = 7); mitral valve replacement, MVR (n = 7); aorto-coronary bypass, ACB (n = 10)). In both the AVR and ACB group an increase of left atrial pressure resulted in 1) a significant increase of left ventricular stroke work index (LVSWI), 2) a significant decrease of the relation of the pre-ejection period to left ventricular ejection time (PEP/LVET), and 3) a significant increase of cardiac output (thermodilution technique and impedance cardiography), whereas no significant alterations were found in the MVR group. Furthermore cardiac output determination using both the direct thermodilution technique and the indirect impedance method revealed a close correlation (n = 63, range cardiac output 1.5-12.51/min, r = 0.852). These data clearly demonstrate the utility of the non invasive impedance cardiography method compared with invasive methods with respect to measurement of cardiac and haemodynamic parameters, even in critical situations.