Variations of Autonomic Tone Preceding Onset of Paroxysmal Supraventricular Tachycardia

Shin, Yung Woo

Abstract

BACKGROUND: Various observations suggest that variations of autonomic tone participates in arrhythmias, but there is limited information about the influence of the autonomic tone on the development of episodes of paroxysmal atrial tachycardia in the elderly.
METHODS
Ambulatory 24-hour Holter electrocardiogram from 40 patients over 60 years old with paroxysmal atrial tachycardia(PAT) were analyzed. Frequency domain heart rate variability(HRV) parameters were determined every 4 minutes over 16 minutes before the onset of PAT and 8 minutes after. HRV indices included total power(TP) (0~0.5Hz), low frequency power(LF) (0.04~0.15Hz), high frequency power(HF) (0.15~0.4Hz), very low frequency power(VLF) (0~0.04 Hz), the ratio of LF/HF(LF/HF), normalized LF(nu LF) (LF/(TP~VLF) X 100) and normalized HF(nu HF) (HF/(TP~VLF) X 100).
RESULTS
Thirty-one of 40 patients(77.5%) had a sudden rise in LF/HF within 12 minutes before the onset of PATs. Among these 31 patients, 20 had a rise within 4 minutes, 7 in 4~8 minutes and 4 in 8~12 minutes preceding the PATs. There were 28 patients(90.3%) who had a increase in nu LF, 29 patient(93.5%) who had a decrease in nu HF and 18 patients(58. 1%) who had an acceleration of heart rate among these 31 patients. Ten of 40 patients(l0%) had no changes in HRV through the PATs.
CONCLUSION
These findings suggest that a relative rise in sympathetic activity contributed to at least 77.5% in the genesis of the elderly PAT, and thus hope- fully providing a rationale for therapeutic approach involving modification of the sympathetic nervous system in the prevention of PATs.