Abstract: To investigate the changes of heart rate variability (HRV) and its relationship to cardiac size and function in children with myocarditis. Methods100 children with myocarditis served as the experimental group and 50 normal children as the control group. All received holter ECG and color Doppler echocardiography examination, and the levels of serum creatine phosphokinase MB and troponin I were quantitatively determined. The 24hour HRV parameters included SDNN, SDANN, rMSSD, PNN50, LF, HF and LF/HF. Echocardiography parameters included end-diastolic diameter of left atrial (LAED), enddiastolic diameter of left ventricle (LVED), left ventricular ejection fraction (LVEF) and fractional shorting (LVFS). Linear regression was used to analyze the relationship between HRV and Echocardiography parameters. ResultsIn the experimental group, LF/HF, CKMB, cTnI and LAED were significantly higher(P<0.05) while SDNN, rMSSD, PNN50 and HF were significantly lower (P<0.05) compared with the control group. SDNN was moderately correlated with LAED(r=－0.52, P<0.05) and LVEF(r=0.49, P<0.05). ConclusionsIn children with myocarditis, both the vagal and sympathetic nerve are impaired. Some HRV parameters are correlated with abnormality of cardiac structure and function, while others are independent. Further study is needed to investigate the prognostic value of HRV in children with myocarditis.

Key words: Myocarditis, Heart rate variability, Cardiac size, Cardiac function, Children