Sample entropy analysis of heart rhythm following cardiac transplantation

Pediatric heart transplantation has become a mainstream in the treatment of end-stage heart disease in infants and children. Heart rate variability is a measure of autonomic nervous influence on the heart. After heart transplantation, the donor heart loses its nervous control. Nonlinear analysis of heart rate is a method to study the physiologic mechanisms responsible for the control of heart rate fluctuations, in which the autonomic nervous system appears to play a primary role. This work evaluated the heart rate entropy in children who has undergone heart transplantation. Patients who underwent heart transplantation showed significant decrease in entropy as assessed by sample entropy (0.63 ± 0.31 vs. 0.90 ± 0.33, p < 0.05). System complexity as can be assessed by entropy methods decreases in transplanted patients and this may be related to loss of the neural modulation of heart rate.