1978 Volume 42 Issue 8 Pages 945-954
The present study was designed to evaluate the left ventricular performance in man with the impedance cardiography which was deviced by Kubicek and associates. The Q-Z interval was compared with hemodynamic and angiographic indices of left ventricular performance in 36 patients in whom cardiac catheterization was carried out. Correlation coefficients between the Q-Z interval and other indices, that is Q-dp/dt, V max, Max dp/dt and Ejection Fraction were 0.91, -0.87, -0.71 and -0.54, respectively and all of them were statistically significant. A shortening of the Q-Z interval always corresponded to an increase of myocardial contractility and a prolongation of it corresponded to a decrease of myocardial contractility. In atrial pacing of 10 patients with sinus bradicardia, the Q-Z interval was not influenced by the heart rate. The usefulness of impedance cardiography is based on the good correlation between the interval from the onset of ventricular depolarization to the peak of the first derivative of the impedance cardiogram (Q-Z interval) and the interval from the onset of ventricular depolarization to the peak of the first derivative of left ventricular pressure (Q-dp/dt). From these results, it is postulated that the Q-Z interval is one of the valuable indices for the assessment of left ventricular performance.
