Measurement of cardiac output by impedance cardiography in patients with myocardial infarction. Comparative evaluation of impedance and dye dilution methods.

The cardiac output was measured simultaneously by the impedance cardiography and dye dilution methods in 10 patients with acute myocardial infarction 2-3 weeks after admission to the Coronary Care Unit. The impedance cardiac output was on the average 9.7% higher than the dye dilution cardiac output. The reproducibility of impedance cardiac output 4.1%, compared with 5.1% for the dye dilution method. The study showed a satisfactory reliability of impedance in predicting the relative changed of cardiac output in response to tilting from the supine to the 30 degrees head-up position, to a 10 degrees head-down position, and to the intravenous administration of propranolol.