All issues > Volume 45(9); 2002

Original Article

J Korean Pediatr Soc. 2002;45(9):1114-1119. Published online September 15, 2002.

Abnormal Fractal Correlation of Heart Rate in Children with Neurocardiogenic Syncope

Keoung-Young KY Kim¹, Eun-Young EY Joo¹, Myung-Kul MK Yum¹, Je-Wen JW Oh¹, Chang-Ryul CR Kim¹, Nam-Su NS Kim¹, Cheol-Beom CB Lee², Chung-Ill CI Noh³

¹Department of Pediatrics, College of Medicine, Hanyang University, Kuri, Korea
²Department of Thoracic & Cardiovascular Surgery, College of Medicine, Hanyang University, Kuri, Korea
³Department of Pediatrics, College of Medicine, Seoul University, Seoul, Korea

Correspondence Myung-Kul MK Yum ,Email: mkyumm@hanyang.ac.kr

Abstract

Purpose
: The purposes of this study were to determine short- and long-term fractal correlation behavior of heart rates during daily activity in patients with neurocardiogenic syncope.
Methods
: Twenty five patients with histories of neurocardiogenic syncope episodes were included. Their analogue 24h ambulatory Holter electrocardiograms were analyzed. The tape was digitized and the digitized electrocardiograms were partioned into sections of one hour. Then their RR intervals were measured and 20,000 points of RRI were used. To quantify the fractal correlation behavior, we employed the detrended fluctuation analysis, and short-term(n≤16, α1) and long-term(n>16, α2) fractal scaling exponents were calculated.
Results
: When compared to control, 24-hour average values of α1 and all α1 values at quarters of each day were significantly higher in patients with syncope. On the contrary, their 24-hour average value of α2 and all α2 values at quarters of each day were lower in patients with syncope. However, statistical significances were found in 24-hour average value of α2 and in α2 value at MN-6AM.
Conclusion
: In the syncope patients with neurocardiogenic syncope, short-term fractal scaling exponents of RR interval was significantly high throughout the day. Therefore, their RR intervals were smoother in the short term scale and had a tendency to continue in the same direction of increase or decrease, which may contribute to persistent decrease in heart rate during a syncopal attack.

Keywords :Neurocardiogenic syncope, RR interval variability, Fractal scaling exponent, Detrended fluctuation analysis