Continuous measurement of hemodynamic alterations during pharmacologic cardiovascular stress using automated impedance cardiography.

The contribution of computerized impedance cardiography in monitoring and differentiating cardiovascular responses to pharmacologic stress after the administration of dipyridamole (group 1, n = 24) or dobutamine (group 2, n = 26) was investigated during stress echocardiography. Heart rate, stroke volume index, cardiac index and systemic vascular resistance index were evaluated continuously with an automated, computerized, signal-averaged impedance cardiography system. Dipyridamole had little average effect on heart rate, stroke volume index, and cardiac index. The responses were similar in patients with positive (n = 9) or negative (n = 15) stress echocardiography test results (as characterized by echocardiographic wall-motion abnormalities). Dobutamine induced a similar mean increase in heart rate in patients with negative (n = 13) or positive (n = 13) results on stress echocardiography. The mean increase in stroke volume index induced by dobutamine was greater in patients with negative stress echocardiography test results than in patients with stress-induced wall-motion abnormalities. This distinction was also seen in the cardiac index; the mean change in patients with negative stress echocardiography test results was larger than in patients with positive results. It is concluded that automated computerized impedance cardiography not only allows surveying and monitoring hemodynamic changes during pharmacologic stress echocardiography but also contributes to differentiation of pathologic stress responses.