Can peak-to-peak variations in heart periods (VHP) be used as a noninvasive indicator of parasympathetic control of heart rate in normal volunteers?
Peak-to-peak variations in heart periods (VHP) can serve as a reliable, noninvasive indicator of parasympathetic control of heart rate at rest without the need for pharmacologic blockade.
The degree of parasympathetic control of heart rate was assessed by the abolition of respiratory sinus arrhythmia with atropine. Peak-to-peak variations in heart periods (VHP) before atropine injection correlated significantly (r = 0.90, P less than 0.001) with parasympathetic control, indicating that VHP alone may be used as a noninvasive indicator of the parasympathetic control of heart rate. Pharmacologic blockade of beta-adrenergic supply in a separate group of normal volunteers did not alter the relationship between VHP and parasympathetic control, indicating that the condition of the experiment (complete rest in a quiet atmosphere) allows the use of VHP alone without pharmacologic interventions to characterize the vagal control of heart rate in humans.
Fouad et al. (1984) studied this question.
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