Twenty-Four-Hour Pattern of Blood Pressure and Spectral Analysis of Heart Rate Variability in Diabetic Patients with Various Degrees of Autonomic Neuropathy. Comparison to Standard Cardiovascular Tests

Abstract

We performed four cardiovascular tests of autonomic function (deep breathing, lying to standing, Valsalva manoeuvre, postural hypotension) and simultaneous 24h recordings of blood pressure (BP) and ECG in 35 normotensive diabetic subjects. Autoregressive power spectrum analysis of RR interval variability was applied to 24h ECG recordings to obtain for day and night periods power of low- (0.03-0.15 Hz, LF) and high-frequency (0.18- 0.40 Hz, HF) components, relative markers of sympathetic and vagal activity respectively, and their ratio (LF/HF), assumed as index of sympathovagal balance. Eighteen patients showed normal cardiovascular tests, 6 patients one abnormal heart rate test, 5 patients two abnormal heart rate tests, and 6 patients also abnormal postural hypotension test. In diabetic patients with increasing degree of autonomic neuropathy, there was a progressive reduction of day-night change in systolic BP (p < 0.01), of LF during the day (p < 0.01), of HF during the night (p < 0.04), of day-night change in HF (p < 0.02), and of day-night change in HF/LF (p < 0.03). Day-night change in systolic BP was related to postural hypotension (p < 0.001) and to deep breathing (p < 0.01). Day LF was related to lying to standing (p < 0.001), to postural hypotension (p < 0.005) and to deep breathing (p < 0.007). Night HF was related to deep breathing (p < 0.0002) and to lying to standing (p < 0.02). Day-night change in HF/LF was slightly related to deep breathing, lying to standing, and to postural hypotension (p < 0.04). In a multiple regression analysis including age, diabetes duration, and cardiovascular tests as independent variables, day-night change in BP and day LF were only related to postural hypotension, whereas night HF was related to deep breathing. In conclusion, in diabetic patients with increasing autonomic damage, there is a progressive impairment of nocturnal fall of BP and of sympathetic activity during the day, blunted nocturnal increase of vagal activity and lower circadian variation in sympathovagal balance. The significant but not very close correlation of day-night pattern of BP and sympathovagal activity to standard cardiovascular reflex tests, supports the independent usefulness of 24h BP monitoring and spectral analysis of heart rate variability in diabetic neuropathy.

A Comparative Study of Heart Rate Variability in Diabetic Subjects and Normal Subjects

“…4.2. Parameters of heart rate variability depicting sympathetic activity: Low frequency power measure of frequency domain result is a major quantitative marker of sympathetic activity 19 was also significantly reduced in our study which is consistent with the study done by Pagani M, et al 20 , H KUDAT et al 17 and Spallone V, et al 22 .Studied power of low frequency parameter of frequency domain results for assessing sympathetic modulation of heart along with other parameters of heart rate variability in 35 normotensive diabetic patients .they found out that L.F. power values are significantly reduced in diabetic patient when compared to normal individuals, this consistent with our study. 4.3.…”

Usefulness of ambulatory blood pressure monitoring in predicting the presence of autonomic neuropathy in type I diabetic patients

“…14,18 A lot of evidence has been gathered that points to a strong link between nondipping phenomenon and autonomic neuropathy, even with a suggestion of a pathogenetic meaning, 13,[15][16][17]29 though some uncertainty still exists about all the pathogenetic mechanisms involved. Nevertheless, recently in 61 type I diabetic subjects, Stella et al 30 did not find any independent relationship between autonomic neuropathy and nondipping and suggested again a primary link between nondipping and diabetic nephropathy regardless of autonomic neuropathy but modified by low-density lipoprotein cholesterol and hypertension.…”

“…[8][9][10][11][12] Although some uncertainty still persists about the whole pathophysiology of the nondipping phenomenon, a series of studies have allowed to show the main pertinence of nondipping to diabetic autonomic neuropathy. [13][14][15][16][17][18] Notwithstanding, the predictive value of nondipping with regard to the presence of autonomic neuropathy has not been established.…”

Characteristics of Autonomic Nervous Function in Zucker-Fatty Rats: Investigation by Power Spectral Analysis of Heart Rate Variability.

“…Previously, we have investigated the characteristics of diurnal variation of autonomic nervous activity using power spectral analysis of heart rate variability (HRV) in some animal species [1,12,16]. Because power spectral analysis of HRV has also been introduced to detect autonomic dysfunction in diabetic patients, this analysis can serve as a clinical test of autonomic function [23,24]. Insulin resistance is considered to be a risk factor in diabetes and other diseases such as hyperlipidemia, hypertension and arteriosclerosis.…”