Purpose: Previous studies suggest the possibility of autonomic dysfunction in patients with complicated hand, foot, and mouth disease (HFMD) and herpangina. Heart rate variability (HRV), an index for autonomic nervous system, may be useful to detect disease progression.
Materials and methods: From 2001 to 2002, 66 patients (1-9 years old) were enrolled prospectively in either a control (20 patients) or disease (46 patients with HFMD or herpangina) group. The disease group was subdivided into stage I (fever only), stage II (with complications of encephalomyelitis), and stage III (with complications of encephalomyelitis as well as tachycardia, hyperglycemia, tachypnea, and hypertension or hypotension) groups. Data from electrocardiograms were transformed for HRV.
Results: The HRV parameters generally decreased and the low frequency (LF)/high frequency ratio (HF) increased in the disease groups. Patients in disease group stage II had significantly lower parameters of HRV (triangular index, total power, LF power, and HF power) and higher LF/HF ratio than those in disease group stage I. With this trend, patients with stage III disease had extremely low HRV parameters. The inferred criteria of HRV (standard deviation of normal-to-normal interval <17 milliseconds and HF power <24 milliseconds(2)) to define stage III patients (sensitivity, 100%; specificity, 71.4%) were also useful to predict disease progression.
Conclusions: The HRV markedly decreased, most likely because of autonomic dysfunction, in patients with HFMD and herpangina when complicated with central nervous system involvement and cardiopulmonary failure and may be useful parameters to monitor disease progression.