Analyzing heart rate variability in infants using non-linear Poincaré techniques

Congenital heart defects, such as Hypoplastic Left Heart Syndrome, are the most prevalent type of birth defect. Palliative reconstructive procedures may interrupt autonomic cardiac function and increase infant mortality rate. Autonomic cardiac tone is classically assessed using linear, Fourier-based techniques. A non-linear Poincare¿ technique is proposed to more completely characterize heart rate variability in terms of short-term (SD1) and long-term (SD2) variability and randomness (SD1/SD2). 24-hour ECG data was collected for 27 normal infants (Group I) and 26 infants with congenital heart defects (Group II) and analyzed in five-minute segments. At birth, Group II showed reduced SD1 and SD2 and increased SD1/SD2 (p < 0.001). Post-procedure, greater SD1 and SD2 (p < 0.001) was seen in Group II. Poincare¿ analysis captures congenital differences in autonomic cardiac function and improvements over time.