Immediate heart-rate response to standing: simple test for autonomic neuropathy in diabetes.

Abstract

Summary and conclusionsThe immediate heart-rate response to standing was measured in 22 normal controls and 25 patients with diabetes, 15 of whom had autonomic neuropathy. The response in the controls and patients without autonomic neuropathy was characteristic and consistent, with tachycardia maximal at around the 15th beat and relative bradycardia maximal at around the 30th beat. The diabetics with autonomic neuropathy, however, showed a flat response. In three controls the response was abolished with intravenous atropine but not with propranolol, showing that it is mediated through the vagus.

Prognostic Value of the Change in Heart Rate From the Supine to the Upright Position in Patients With Chronic Heart Failure

“…We must acknowledge that the exact pathophysiological correlate of ∆HR is unknown, and given the methods used in our study, it is likely that we assessed neither the maximum baroreflex‐mediated rise in HR nor the nadir of the relative bradycardia thereafter. Rather, our measurement likely reflects an average HR throughout this period of HR dynamics after getting up or even the more or less stable HR that is established after ~2 minutes at least in healthy subjects 10. Still, we assume that ΔHR as assessed in the present study reflects the integrity or defect, respectively, of the mechanisms responsible for an increased sympathetic outflow to the heart after a person gets up.…”

“…Second, we studied a population with a high proportion of patients on β‐blocker therapy, and the effect of β‐blocker therapy on ΔHR is unknown. An early pathophysiological study has revealed that the above‐described HR response to standing is under vagal control 10. However, adjustment for baseline β‐blocker dosage did not alter the results (data not shown), and there was no interaction between baseline β‐blocker use and the association between ΔHR and outcomes.…”

“…This is not a surprising finding in this population of elderly patients with advanced HF, however. The original study by Ewing et al10 had shown that the magnitude of HR response to standing depends on age and disease status (diabetes, neuropathy). One might argue that this relatively narrow range of ΔHR in HF may limit the applicability of the parameter in practice.…”

“…The ratio of the longest (~30th beat) and shortest (~15th beat) RR intervals (“30/15 ratio”) is used to describe this HR response. However, after the 30th beat, the HR remains elevated compared to the supine baseline in the presence of an intact sympathicovagal balance, and patients with diabetic neuropathy are characterized not only by a low 30/15 ratio but also by a lack of or a severely overall blunted rise in HR from the supine to the standing position 10. Thus, the change in HR following getting up from the supine to the upright position (∆HR) might be a simple test to assess the degree of autonomic dysfunction in patients with chronic HF, which may also predict prognosis, but this has not yet been investigated.…”

Study of cardiac parasympathoautonomic regulation in men of different ages

“…The initial cardio accelerator is an exercise reflex, while the subsequent tachycardia and bradycardia are baroreflex mediated. The 30:15 ratio [RR interval at beat 30/RR interval at beat 15], serves as index of cardiovagal function [14,15]. When the ratio is 1 or less, vagal damage is probably present.…”