Cardiac autonomic nervous activity in patients with transposition of the great arteries after arterial switch operation

BackgroundA chronic imbalance of the autonomic nervous system(ANS) may contribute to long term complications in different congenital heart diseases. The purpose of this study was to determine whether the ASN plays a role in the long-term outcome of patients with Transposition of great arteries(TGA) after arterial switch operation(ASO) as its contribution is as yet not clear.MethodsThe ANS activity was evaluated non-invasively in 26 TGA patients and 52 age-appropriate healthy subjects combining impedance cardiography and electrocardiography. Heart rate, pre-ejection period(sympathetic activity parameter) and respiratory sinus arrhythmia and the root of the mean square of successive normal-to-normal interval differences(parasympathetic activity parameter) were measured during 5 different daily activities(sleep, sitting, active sitting, light and moderate/vigorous physical activity). Whether the ANS activity was related to ventricular function, exercise test performance or clinical outcome in the patient group was also analyzed.ResultsCompared to healthy subjects: heart rate was significantly lower in TGA patients at rest and during quiet and active sitting; sympathetic activity was significantly reduced in patients during physical activity; and the parasympathetic activity was higher in TGA patients while quiet and active sitting. In the patient group a significant positive correlation between 4-chamber longitudinal strain and parasympathetic activity during 3 different daily activities was found.ConclusionsThe sympathetic nervous system response to physical activity is reduced in TGA patients after ASO. Additionally, we observed a positive correlation between better left ventricular function and higher parasympathetic activity that could be in line with the known protective effect of a higher vagal activity.