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Heart rate complexity in response to upright tilt in persons with Down syndrome

Stamatis Agiovlasitis1, Tracy Baynard, Kenneth H Pitetti

  • 1Department of Kinesiology, Mississippi State University, 233 McCarthy Gym, PO Box 6186, Mississippi State, MS 39762, USA. sagiovlasitis@colled.msstate.edu

Research in Developmental Disabilities
|October 12, 2011
PubMed

Insights

People with Down syndrome (DS) exhibit altered heart rate (HR) complexity during upright tilt, potentially linked to cardiovascular risk. Higher body mass index (BMI) partially explains these differences in autonomic response.

Area of Science:

  • Cardiovascular Physiology
  • Autonomic Nervous System Function
  • Human Genetics

Background:

  • Individuals with Down syndrome (DS) display atypical autonomic responses to sympatho-excitation.
  • Heart rate (HR) complexity serves as a metric for cardiac autonomic modulation and is linked to cardiovascular risk.

Purpose of the Study:

  • To investigate differences in HR complexity response to passive upright tilt between individuals with and without DS.
  • To determine if body mass index (BMI) accounts for any observed between-group differences in HR complexity response.

Main Methods:

  • ECG recordings were obtained from 16 individuals with DS and 16 controls during supine rest and upright tilt.
  • Analysis included approximate entropy, correlation dimension, StatAv, and mean R-R interval from 550 R-R intervals per condition.
  • Statistical analyses controlled for BMI to assess its influence on group differences.

Main Results:

  • Participants with DS showed reduced changes in approximate entropy and correlation dimension during tilt compared to controls (p<0.05).
  • These reductions in HR complexity were explained by higher BMI in the DS group.
  • StatAv increased in the DS group during tilt, unlike the control group, even after controlling for BMI (p<0.05).
  • No significant differences in resting HR complexity or R-R interval response were found between groups.

Conclusions:

  • Individuals with DS demonstrate a blunted decrease in HR complexity during upright tilt, partly attributable to higher BMI.
  • Resting cardiac autonomic modulation, as assessed by HR complexity, does not differ between individuals with and without DS.
  • These findings suggest potential implications for understanding cardiovascular risk in the DS population.

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