J Korean Pediatr Soc.  2002 Sep;45(9):1114-1119.

Abnormal Fractal Correlation of Heart Rate in Children with Neurocardiogenic Syncope

• Kim KY
• Joo EY
• Yum MK
• Oh JW
• Kim CR
• Kim NS
• Lee CB
• Noh CI

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(n16, alpha2) fractal scaling exponents were calculated.
RESULTS
When compared to control, 24-hour average values of alpha1 and all alpha1 values at quarters of each day were significantly higher in patients with syncope. On the contrary, their 24-hour average value of alpha2 and all alpha2 values at quarters of each day were lower in patients with syncope. However, statistical significances were found in 24-hour average value of alpha2 and in alpha2 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.

Keyword

Neurocardiogenic syncope; RR interval variability; Fractal scaling exponent; Detrended fluctuation analysis

MeSH Terms

Child*
Electrocardiography
Fractals*
Heart Rate*
Heart*
Humans
Syncope
Syncope, Vasovagal*