J Korean Pediatr Soc.  2003 Oct;46(10):996-1002.

Heart Rate Variability and Autonomic Activity in Patients Affected with Rett Syndrome

• Choi DY
• Chang JH
• Chung HJ

Abstract

PURPOSE
In Rett syndrome patients, the incidence of sudden death is greater than that of the general population, and cardiac electrical instability including fatal cardiac arrhythmia is a main suspected cause. In this study, we are going to find out the possible cause of the higher risk of sudden death in Rett patients by the evaluation of heart rate variability, a marker of cardiac autonomic activity and corrected QT intervals.
METHODS
Diagnosis of Rett syndrome was made by molecular genetic study of Rett syndrome (MECP2 gene) or clinical diagnostic criteria of Rett syndrome. Heart rate variability and corrected QT intervals were measured by 24 h-Holter study in 12 Rett patients, and in 30 age-matched healthy children with chief complaints of chest pain or suspected heart murmurs. The were compared with the normal age-matched control.
RESULTS
Patients with total Rett syndrome, classic Rett syndrome, and Rett variants had significantly lower heart rate variability(especially rMSSD)(P<0.05) and longer corrected QT intervals than age-matched healthy children(P<0.05). Sympathovagal balance expressed by the ratio of high to low frequency(LF/HF ratio) also showed statistically significant differences between the three groups considered(P<0.05).
CONCLUSION
A significant reduction of heart rate variability, a marker of autonomic disarray, suggests a possible explanation of cardiac dysfunction in sudden death associated with Rett syndrome.

Keyword

Rett syndrome; Heart rate variability; Cardiac dysautonomia; Sudden death

MeSH Terms

Arrhythmias, Cardiac
Chest Pain
Child
Death, Sudden
Diagnosis
Heart Murmurs
Heart Rate*
Heart*
Humans
Incidence
Molecular Biology
Rett Syndrome*