New squatting test indices are useful for assessing baroreflex sensitivity in diabetes mellitus

M Nakagawa,T Shinohara,F Anan,M Hara,N Okada,N Takahashi,H Yoshimatsu,T Saikawa,K Yufu

doi:10.1111/j.1464-5491.2008.02591.x

M Nakagawa, T Shinohara + Show 7 more

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https://doi.org/10.1111/j.1464-5491.2008.02591.x

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Abstract

AimsThe heart rate (HR) responses after performance of the squatting and standing manoeuvre are thought to be a useful tool to assess autonomic neuropathy in diabetics. Our aim was to develop new simple squatting test indices and to analyse their applicability to the assessment of baroreflex sensitivity (BRS) in patients with diabetes.MethodsTwenty healthy volunteers (mean age 23.2 ± 3.8 years) and 51 patients with diabetes (mean age 55.9 ± 10.6 years) were enrolled in study 1 and study 2, respectively. Each subject stood for 3 min (basal period), then squatted down for 1 min (Sq) and stood up again for 1 min (St). In study 1, the squatting test was performed before and after pharmacological autonomic blockade. In study 2, we measured HR in each period and calculated the difference between basal HR and HRSq (ΔHRSq) and between HRSt and HRSq (ΔHRSt). BRS was also measured using the phenylephrine method in diabetic patients.ResultsIn healthy individuals during autonomic blockade, HR changes were mainly controlled by the vagal tone during squatting and by the sympathetic tone during standing. In diabetic patients, ΔHRSq and ΔHRSt positively correlated (r = 0.86, P < 0.0001) and both ΔHRSq and ΔHRSt significantly correlated with BRS (r = 0.66, P < 0.0001 and r = 0.61, P < 0.0001, respectively).ConclusionsThe new squatting test indices provide useful information for assessing autonomic neuropathy and for identifying diabetic patients at high risk of cardiovascular events.

Highlights

Autonomic neuropathy, a common complication of diabetes mellitus, is associated with increased mortality [1,2]
ΔHRSq and ΔHRSt positively correlated (r = 0.86, P < 0.0001) and both ΔHRSq and ΔHRSt significantly correlated with baroreflex sensitivity (BRS) (r = 0.66, P < 0.0001 and r = 0.61, P < 0.0001, respectively)
We demonstrated a strong correlation between the systolic blood pressure increase and a corresponding lengthening of the RR interval during downward tilting and a significant correlation with the BRS value in diabetic patients undergoing the conventional phenylephrine method [10]

Summary

Introduction

A common complication of diabetes mellitus, is associated with increased mortality [1,2]. Baroreflex sensitivity (BRS) is a marker for the ability to augment vagal activity. BRS is attenuated in diabetic patients with autonomic neuropathy [3,4,5,6] and is associated with cardiovascular mortality [7] or sudden cardiac death [8]. We previously reported a new physiological, non-invasive method to measure baroreflex response during downward tilting [9,10]. We demonstrated a strong correlation between the systolic blood pressure increase and a corresponding lengthening of the RR interval during downward tilting and a significant correlation with the BRS value in diabetic patients undergoing the conventional phenylephrine method [10].

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Discussion

Conclusion