Jana Javorkova

Short-term heart rate complexity is reduced in patients with type 1 diabetes mellitus☆

OBJECTIVE The aim of this study was to test whether new heart rate variability (HRV) complexity measures provide diagnostic information regarding early subclinical autonomic dysfunction in diabetes mellitus (DM). METHODS HRV in DM type 1 patients (n=17, 10f, 7m) aged 12.9-31.5 years (duration of DM 12.4+/-1.2 years) was compared to a control group of 17 healthy matched probands. The length of R-R intervals was measured over 1h using a telemetric ECG system. In addition to linear measures, we assessed HRV complexity measures, including multiscale entropy (MSE), compression entropy and various symbolic dynamic measures (Shannon and Renyi entropies, normalized complexity index (NCI), and pattern classification). RESULTS HRV magnitude was significantly reduced in patients with DM. Several HRV complexity parameters (MSE at scales 2-4, Renyi entropy, NCI) were also significantly reduced in diabetics. MSE indices and compression entropy did not correlate with linear measures. CONCLUSIONS The magnitude and complexity of HRV are reduced in young patients with DM, indicating vagal dysfunction. SIGNIFICANCE The quantification of HRV complexity in combination with its magnitude may provide an improved diagnostic tool for cardiovascular autonomic neuropathy in DM.

Reduced short-term complexity of heart rate and blood pressure dynamics in patients with diabetes mellitus type 1: multiscale entropy analysis

Multiscale entropy (MSE) analysis provides information about complexity on various time scales. The aim of this study was to test whether MSE is able to detect autonomic dysregulation in young patients with diabetes mellitus (DM). We analyzed heart rate (HR) oscillations, systolic (SBP) and diastolic blood pressure (DBP) signals in 14 patients with DM type 1 and 14 age- and sex-matched healthy controls. SampEn values (scales 1-10) and linear measures were computed. HR: among the linear measures of heart rate variability significant differences between groups were only found for RMSSD (p = 0.043). MSE was significantly reduced on scales 2 and 3 in DM (p = 0.023 and 0.010, respectively). SBP and DBP: no significant differences were detected with linear measures. In contrast, MSE analysis revealed significantly lower SampEn values in DM on scale 3 (p = 0.039 for SBP; p = 0.015 for DBP). No significant correlations were found between MSE and linear measures. In conclusion, MSE analysis of HR, SBP and DBP oscillations is able to detect subtle abnormalities in cardiovascular control in young patients with DM and is independent of standard linear measures.

Heart rate variability in young patients with diabetes mellitus and healthy subjects explored by Poincaré and sequence plots

Autonomic neuropathy is a common complication of the diabetes mellitus (DM). The significance of its early diagnosis is very high because the mortality of the patients with this complication is elevated. Considering the effort to apply new mathematical methods to cardiac dysregulation diagnosis, the major aim of the study was to ascertain which of the new heart rate variability (HRV) parameters are different in young patients with DM type 1 compared with control group. The next aim was to assess the HRV changes during prolonged (40 min) supine rest. The heart rate was continuously recorded during supine rest in 17 young patients with DM type 1 (10 women, 7 men) aged 22·4 ± 1·0 years (mean ± SEM). The control group consisted of 17 healthy matched probands. The HRV (time/frequency domains, Poincaré and sequence plots, sample entropy) was analysed in two intervals – T1 starting at fifth minute and T2 starting at 30th minute of supine rest. The major results of our study are: the reduced Poincaré plot pattern measures in the young DM group; the lower percentage of points in the third quadrant of sequence plot (this parameter was not correlated with the mean heart rate) and significant changes in HRV during supine rest in DM group (in contrast to control subjects). In conclusion, HRV parameters based on nonlinear dynamics were able to distinguish cardiac dysregulation in young patients with DM from the control group. The percentage of points in the third quadrant of sequence plot provides information that is not dependent on mean heart rate. Poincaré and sequence plots, together with the rate of HRV changes during supine rest, can provide clinically relevant information usable in diagnosis of the cardiac dysregulation.

Parasympathetic versus sympathetic control of the cardiovascular system in young patients with type 1 diabetes mellitus

Autonomic neuropathy and cardiovascular dysregulation are common complications of the diabetes mellitus (DM). The aim of the study was to test the hypothesis that cardiovascular regulation is abnormal in young patients with type 1 DM. Patients with type 1 DM (17, 10 females, 7 males) aged 12·9–31·5 years (mean ± SEM: 22·4 ± 1·0 years) were investigated. The mean duration of DM was 12·4 ± 1·2 years. The control group consisted of 17 healthy probands matched for sex and age. The length of R–R intervals was measured using telemetric system (VariaCardio TF4; Sima Media) where ECG signal (sampling frequency 1000 Hz) from thoracic belt was transferred into PC for further analysis. Systolic blood pressure (SBP) was monitored beat‐to‐beat using volume–clamp method by Finapres 2300 (Ohmeda). Spectral power in HF band of HRV (HRV–HF) was taken as an index of parasympathetic control and spectral power in LF band of systolic BPV (BPV–LF) as an index of sympathetic control. In young patients with type 1 DM significant reduction of spectral power in HF band of the heart rate variability was found, whereas no significant difference between DM group and control group was observed in spectral power in LF band of blood pressure variability. In conclusion, we found impaired parasympathetic control of heart rate in young patients with type 1 DM. No differences in blood vessels sympathetic control were detected using spectral analysis of BPV. We suggest that abnormalities in cardiac parasympathetic regulation precede impairment of blood vessels sympathetic control in young diabetics.

Recurrences in heart rate dynamics are changed in patients with diabetes mellitus.

Detection of subclinical autonomic dysfunction in patients with diabetes mellitus (DM) is of vital importance for risk stratification and subsequent management. Heart rate variability (HRV) analysis is a sensitive tool for assessment of cardiovascular autonomic dysfunction. As the heart is controlled by non‐linear deterministic system, the non‐linear dynamics measures should be preferred. Recurrence plot (RP) is able to analyse recurrences within system dynamics. The aim of the study was to detect heart rate dysregulation in DM by RP and to ascertain which of the recurrence quantification analysis (RQA) measures are changed in patients with DM compared to control group. We analysed HRV recordings from 17 young patients with type 1 DM and 17 healthy matched control subjects. RQA was performed on RPs with a fixed value of recurrence points percentage. From RQA measures based on diagonal lines, we have found higher percentage of determinism in DM group (P = 0·038). Trapping time measure was also higher in DM (P = 0·022). RQA revealed changes in dynamics recurrences with reduced complexity of heart rate control in young diabetic patients. As RQA parameters are independent of overall HRV, parameters of RP should be used together with linear HRV parameters for better description of heart rate dysregulation in patients with diabetics.

Heart rate variability and cardiovascular tests in young patients with diabetes mellitus type 1.

The aim of this study was to obtain information about parameters of heart rate variability (HRV) in three frequency bands (high frequency - HF, low frequency - LF and very low frequency - VLF), the sensitivity of cardiovascular tests, and subjective feelings depending on autonomic nervous system balance in a group of young patients with diabetes mellitus type 1 (IDDM). Sixty-four subjects were examined: 32 patients with diabetes with a mean age of 16.1 +/- 0.7 years and a mean duration of IDDM of 6.3 +/- 0.8 years, and 32 healthy controls matched for age, sex and BMI. Shorter R-R intervals and abnormal values reflecting HRV were found in the diabetic group. In particular, parameters of total power, and HF and LF bands were reduced. The ratio VLF/HF power revealed predominance of sympathetic tone in the diabetic subjects. Although relative power VLF was increased in the supine position, the reactive rise of the VLF band activity in orthostasis was lower in the IDDM group. Using cardiovascular tests (deep breathing, Valsalva, orthostasis), significant differences in reactions were found only in the deep breathing test. Evaluation of sympathetic:parasympathetic:indifferent subjective feelings by questionnaire did not reveal any differences between the diabetic and healthy groups.

Nonlinear PD2i heart rate complexity algorithm detects autonomic neuropathy in patients with type 1 diabetes mellitus

OBJECTIVE The aim of this study was to test whether a new heart rate variability (HRV) complexity measure, the Point Correlation Dimension (PD2i), provides diagnostic information regarding early subclinical autonomic dysfunction in diabetes mellitus (DM). We tested the ability of PD2i to detect diabetic autonomic neuropathy (DAN) in asymptomatic young DM patients without overt neuropathy and compared them to age- and gender-matched controls. METHODS HRV in DM type 1 patients (n=17, 10 female, 7 male) aged 12.9-31.5 years (duration of DM 12.4±1.2 years) was compared to that in a control group of 17 healthy matched probands. The R-R intervals were measured over 1h using a telemetric ECG system. RESULTS PD2i was able to detect ANS dysfunction with p=0.0006, similar to the best discriminating MSE scale, with p=0.0002. CONCLUSIONS The performance of PD2i to detect DAN in asymptomatic DM patients is similar to the best discriminative power of previously published complexity measures. SIGNIFICANCE The PD2i algorithm may prove to be an easy to perform and clinically useful tool for the early detection of autonomic neuropathy in DM type 1 patients, especially given its minimal data requirements.

Heart Rate and its Variability in Juvenile Hypertonics During Respiratory Maneuvers

In 27 children (14 juvenile hypertonics and 13 healthy control children, with the mean age 14.7 +/- 0.4 y. or 15.2 +/- 0.5 y., respectively, P greater than 0.05) the changes of heart rate (HR), its variability (HRV) during deep inspiration and subsequent expiration, Valsalvas maneuver, doubled breathing frequency and the deepening of breathing were studied. The resting supine mean HR was significantly higher (P less than 0.001) in hypertonics than in controls. Deep inspiration was in both groups accompanied with the HR increase. However, the percentage increase in hypertonics was significantly lower than in normals (P less than 0.02). With subsequent expiration, the HR fell in both groups. There was no significant difference between the percentage decreases in both groups (P greater than 0.05). During the Valsalvas maneuver, in the first phase the tachycardic response occurred, which was in hypertonics significantly less pronounced. After the recovery of breathing a bradycardic reaction occurred which was equal in both groups (P greater than 0.05). Both, in juvenile hypertonics and in controls the doubled frequency of breathing increased the mean HR and decreased the HRV. During the deepened breathing there was an increase in mean HR in both groups, and only in the controls there was an increase in HRV. Heart rate variability in hypertonics was lower than in the controls under all the conditions.

Heart rate variability and physical fitness in children and adolescents with diabetes mellitus type 1

The primary aim of the study was to compare heart rate variability (HRV) in children and adolescents with diabetes mellitus type 1 (DM 1) regularly engaged in sports (trained T) and those not engaged in physical activities (non-trained NT). The study evaluated the effect of a short-term stay in a reconditioning summer camp on HRV, and assessed the importance of physical exercise in young diabetics. The patients included twenty diabetics with DM 1 (mean age 15.5 years range 827) with an average duration of DM 1 of 6.0 (0.5 15) years examined by system VariaPulse TF3 on the second and the last day (9 day) of their stay in camp. The mean value of glycosylated hemoglobin (HbA l c ) of the trained subgroup was significantly lower (8.8 ± 0.7 %) in comparison to the NT subgroup (11.6 ± 0.9%). Trained diabetics had significantly longer RR intervals (slower heart rate), higher values of MSSD, spectral total power and powers in three studied frequency bands (very low -VLF, low-LF, high-HF) of the HRV. In active orthostasis, trained subjects had higher reactive changes of spectral powers in the VLF and HF band. Trained subjects had a significantly lower occurence of abnormal values of individual measures of HRV (T = 14 ± 6%, NT = 54 ± 9 %). In the whole group (T+NT) at the end of the stay, as compared with starting values, there were significantly longer RR intervals and higher values of HRV parameters. The increase of the whole spectral power was mainly due to an increased power in HF parasympathetic band. The results indicate the importance of physical activity and sports in the maintenance and improvement of physiological regulation of cardiac activity in diabetic children and adolescents.

Recurrence Quantification Analysis of Heart Rate Dynamics in Young Patients with Diabetes Mellitus

There is an ongoing effort to apply methods based on nonlinear dynamics to improve the description and classification of different states and diseases. Relatively few studies were focused on autonomic neuropathy in young adults with diabetes mellitus (DM) type 1. The aim of this study was to find out which of the heart rate variability parameters derived from recurrence plot (recurrence quantification analysis parameters) are different in young patients with DM compared to control group. We have quantified various recurrence plot measures. From RQA measures based on diagonal lines in recurrence plots, we have found higher percentage of recurrence and of determinism and increased maximal length of diagonal line in DM group. Parameter Trapping Time was higher in DM group compared to control subjects. These results suggests reduced complexity and increased predictability of heart rate dynamics even in young patients with DM. RQA parameters should be used together with other HRV parameters for better description of heart rate dysregulation in various patients groups.