Blunted heart rate response to upright tilt in people with Down syndrome.
OBJECTIVE
To determine whether heart rate and blood pressure responses to upright tilt would be lower in subjects with Down syndrome (DS) than in control subjects with no disabilities.


METHODS
Comparative study.


METHODS
University research laboratory.


METHODS
Nineteen people with DS (mean age, 25.1+/-7.3 y) and 17 control subjects without disabilities (mean age, 28.4+/-5.6 y).


METHODS
Not applicable.


METHODS
Heart rate and blood pressure recordings were obtained at rest and during a 2-minute period of passive head up tilt to 80 degrees .


RESULTS
Heart rate and blood pressure increased significantly during the first 30 seconds of upright tilt in both groups ( P <.05) and then stabilized for the remainder of the test. The initial heart rate response to head up tilt (first 30s) was significantly higher in controls compared with subjects with DS ( P <.05), whereas the blood pressure response did not differ between groups ( P >.05). Controlling for heart rate reserve showed a blunted heart rate response through the tilt period in subjects with DS.


CONCLUSIONS
These data show a blunted heart rate response to upright tilt in people with DS, despite similar changes in blood pressure, consistent with reduced sympathoexcitation and possibly altered baroreceptor function in these people with DS.
Fernhall
Bo
B
Exercise Science Department, Syracuse University, NY, USA. fernhall@uiuc.edu
Figueroa
Arturo
A
Collier
Scott
S
Baynard
Tracy
T
Giannopoulou
Ifigenia
I
Goulopoulou
Styliani
S
D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D004314:Down Syndrome / Q000503:physiopathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D018667:Tilt-Table Test