Effect of heartmate left ventricular assist device on cardiac autonomic nervous activity

Background. Clinical performance of a left ventricular assist device is assessed via hemodynamic parameters and end-organ function. This study examined effect of a left ventricular assist device on human neurophysiology. Methods. This study evaluated the time course change of cardiac autonomic activity of 3 patients during support with a left ventricular assist device before cardiac transplantation. Cardiac autonomic activity was determined by power spectral analysis of short-term heart rate variability. The heart rate variability before cardiac transplantation was compared with that on the day before left ventricular assist device implantation. Results. The standard deviation of the mean of the R-R intervals of the electrocardiogram, an index of vagal activity, increased to 27 ± 7 ms from 8 ± 0.6 ms. The modulus of power spectral components increased. Low frequency (sympathetic activity) and high frequency power (vagal activity) increased by a mean of 9 and 22 times of each baseline value (low frequency power, 5.2 ± 3.0 ms2; high frequency power, 2.1 ± 0.7 ms2). The low over high frequency power ratio decreased substantially, indicating an improvement of cardiac sympatho-vagal balance. Conclusions. The study results suggest that left ventricular assist device support before cardiac transplantation may exert a favorable effect on cardiac autonomic control in patients with severe heart failure.