[Impedance cardiography (author's transl)]

Determination of cardiac output by impedance cardiography exhibited perfect agreement with determinations performed by the Fick principle (r = 0.905; p less than 0.001); the measurements were carried out on 11 patients without valvular disease, 15 patients with mitral stenosis, 5 patients with aortic stenosis and 4 patients with combined aortic valvular disease. Impedance cardiography tends to give an underestimate of the cardiac output in patients with mitral insufficiency (N = 7) and in cases with combined mitral valvular disease (N = 9); in patients suffering from aortic insufficiency (N = 6), combined valvular disease (N = 5) and left to right shunts (N = 10) the cardiac output is often overestimated. Impedance cardiography is also suitable for determination of the cardiac output under exercise testing conditions up to submaximum ranges. This was demonstrated on 30 well-trained sportsmen, in a comperison and oxygen consumption testing (r = 0.937; p less than 0.001). Zo impedance does not change in healthy persons during exercise testing. Pharmacological investigations can be performed using impedance cardiography; a reduction in pressure values in pulmonary hypertension was demonstrated under the influence of nitroprusside. The stroke volume of a single cardiac revolution was, more over, measured in 12 patients with implanted pacemakers. P-ST intervals were 70--200 msec. The increase in cardiac output by 33% indifies the opinion that in certain cases, especially in young people, atrial synchronous pacemaker systems should be tried, despite the reported pitfalls and lack of success to date.