September 1, 1980Cardiovascular Research
Mechanisms of tachycardia on standing: studies in normal individuals and in chronic Chagas' heart patients
Key result
A 70-degree head-up tilt elicited markedly decreased initial heart rate responses in chronic Chagas' heart disease patients compared to normal individuals.
Why the study?
What are the autonomic mechanisms of reflex tachycardia induced by standing in normal individuals and patients with chronic Chagas' heart disease?
Population
Conscious normal individuals and patients with chronic Chagas' heart disease (without cardiac failure)
Comparison
70 degree head-up tilt from supine position… vs Normal individuals vs Chagas' patients; baseline…
Design
Other
Follow-up
5 minutes
Authors
Discussion
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Implication
Blunted initial orthostatic tachycardia may signal parasympathetic impairment in Chagas' disease; leaves open its role in risk stratification.
Study Design
Type
Observational
Structured PICO
What are the autonomic mechanisms of reflex tachycardia induced by standing in normal individuals and patients with chronic Chagas' heart disease?
P
Population
Conscious normal individuals and patients with chronic Chagas' heart disease without cardiac failure.
E
Exposure
70 degree head-up tilt from supine position, with and without parasympathetic blockade (atropine) and beta-adrenergic blockade
C
Comparator
Normal individuals vs Chagas' patients; baseline vs pharmacological blockade
O
Outcome
Heart rate response (reflex tachycardia) at initial 10 s, 1 min, and 5 min following tiltsurrogate
The reflex tachycardia upon standing is biphasic, initially driven by parasympathetic withdrawal and subsequently maintained by sympathetic stimulation.
Cite This Study
Gallo et al. (1980) conducted an observational in Chronic Chagas' heart disease. 70 degree head-up tilt vs. Supine position was evaluated on Heart rate response. A 70-degree head-up tilt elicited markedly decreased initial heart rate responses in chronic Chagas' heart disease patients compared to normal individuals.