Associations between heart rate asymmetry expression and asymmetric detrended fluctuation analysis results.

The relation between recently established asymmetry in Asymmetric Detrended Fluctuation Analysis (ADFA) and Heart Rate Asymmetry is studied. It is found that the ADFA asymmetric exponents are related both to the overall variability and to its asymmetric components at all studied time scales. We find that the asymmetry in scaling exponents, i.e., [Formula: see text] is associated with both variance-based and runs-based types of asymmetry. This observation suggests that the physiological mechanisms of both types are similar, even though their origins and mathematical methods are very different. The graphical abstract demonstrates strong, nonlinear association between the expression of Heart Rate Asymmetry measured using relative descriptors and the Asymmetric Detrended Fluctuation Analysis results. It is clear that there is a strong relation between the two theoretically disparate approaches to signal analysis. The technique to demonstrate the association is loess fit.

Testing heart rate asymmetry in long, nonstationary 24 hour RR-interval time series.

OBJECTIVE: Heart rate asymmetry is a phenomenon in which the contribution of heart rate decelerations to short-term heart rate variability is greater than that of accelerations, and the contribution of accelerations to long-term and total variability is greater than that of decelerations. This has been established for short, stationary recordings, so our aim is to do it for long recordings. APPROACH: In this paper, we analyze heart rate asymmetry in 87 long, 24 h electrocardiogram Holter recordings from healthy people. We show that in the whole recording all types of asymmetry are observable, clear and highly statistically significant. To analyze the local changes of asymmetry in time, we analyzed the recordings by disjoint jumping windows of 300 beats. MAIN RESULTS: This analysis revealed that the local, averaged measures of all types of asymmetry also demonstrate its presence which is highly statistically significant. Additionally, we introduce in this paper a statistical test for asymmetry in a single long recording, as opposed to the current approach in which whole groups are tested. We do this by introducing the proportion of time spent in asymmetry for each recording and using it in the binomial tests. SIGNIFICANCE: We found that for all the recordings most of the time is spent in asymmetry.

Trait anxiety mimics age-related cardiovascular autonomic modulation in young adults.

Anxiety produces maladaptive cardiovascular changes and accelerates biological aging. We evaluated cardiovascular reactivity in young and middle-aged individuals with varying anxiety scores to test the hypothesis that anxiety mimics cardiovascular aging by influencing cardiovascular autonomic modulation. The State-Trait Anxiety Inventory was used to classify healthy young individuals (20-29 years) into high (YHA, n=22;10 men) and low (YLA, n=21;10 men) anxiety, and to identify middle-aged individuals (50-60 years) with low anxiety (MLA, n=22;11 men). Heart rate, blood pressure (BP) and their variability (HRV and BPV, respectively) and baroreflex function were analyzed from beat-to-beat finger BP and electrocardiogram recordings collected during 5-min baseline, 6-min speech task (ST) and 3-min post ST recovery. Analyses of covariance showed significant differences (P<0.05) at baseline for HRV, BPV and barorelfex, and low-frequency power of systolic BP variability (LFSBP) was lower, whereas baroreflex and high frequency (HF) normalized units were higher in the YLA compared with YHA and MLA groups. Compared with YLA, YHA and MLA displayed attenuated vagal withdraw response (HF) to ST. BP and LFSBP responses to ST in YHA and MLA were higher compared with the YLA group. These findings suggest that anxiety could be linked to cardiovascular aging as it attenuates cardiac reactivity and exaggerates vascular responses to stress.

Gray matter volume in relation to cardio-vascular stiffness.

BACKGROUND: Hemodynamic disturbances are associated with aging as well as the chronic process of left ventricular and arterial stiffening. This process can influence gray matter volume and thereby contribute to brain atrophy. We performed a comprehensive assessment of left ventricular and arterial function as well as central hemodynamics. These data were correlated with gray matter volume (GMV) as evaluated by magnetic resonance imaging (MRI). METHODS: GMV and aortic stiffness were estimated using MRI. Left ventricular end-systolic elastance or stiffness (Ees), arterial elastance (Ea) and total arterial compliance (TAC) were determined by echocardiography. Central hemodynamics were assessed using pulse wave analysis. RESULTS: Seventy-five healthy subjects (42 women, 33 men, mean age of 58 years) were recruited. The clinical analyses showed that GMV correlates significantly and inversely with age (r=-0.37, P=0.001), end-systolic LV stiffness (r=-0.39, P=0.0009), augmentation pressure (r=-0.48, P<0.0001), arterial elastance (r=-0.27, P=0.02) and aortic stiffness (r=-0.23, P=0.04), as determined by aortic pulse wave velocity (aPWV). GMV correlated significantly with total arterial compliance (r=0.23, P=0.04). Stepwise forward multiple regression analysis revealed that 35% of variance (P<0.0001) in GMV is attributed to aPWV, Ees and AP. CONCLUSIONS: Left ventricular end-systolic stiffness, augmentation of central arterial pressure and aortic stiffness are associated independently and negatively with GMV. These associations suggested that brain atrophy is influenced by hemodynamic factors.

The structure of heart rate asymmetry: deceleration and acceleration runs.

A family of new heart rate asymmetry measures is introduced, namely deceleration and acceleration runs, as well as entropic measures summarizing their distribution. We introduce the theoretical run distribution for shuffled data and use it as a reference for interpreting the results. The measures defined in the paper are applied to actual 24 h Holter ECG recordings from 87 healthy people, and it is demonstrated that the patterns of accelerations are different from those of decelerations. Acceleration runs are longer and more numerous: all runs of accelerations, with the exception of lengths 3 and 4, are more numerous than those of decelerations. These findings are reflected in the difference between the entropic measures for acceleration and deceleration runs: for 74 subjects the acceleration-related entropic parameter is greater than that of decelerations (p < 0.001). For shuffled data there is no difference in the above parameters, and there are more short runs and fewer long runs than in physiological data. The influence of the measuring equipment resolution is also discussed.

Arterial stiffness in relation to subclinical atherosclerosis.

BACKGROUND: Increased arterial stiffness or arteriosclerosis, represents a physiological part of ageing. Atherosclerosis is a process that does not affect the arterial bed uniformly but has a variable local distribution and is frequently superimposed on stiffened vessels. We therefore addressed the question of whether any correlation exists between the general characteristics of arterial stiffness or wave reflection and subclinical atherosclerosis as assessed by carotid intima-media thickness (IMT) in a sample of healthy subjects. METHODS: A total of 116 healthy subjects (mean age 55 years, 43 female) were evaluated. Arterial stiffness and wave reflection was assessed with the use of digital volume pulse analysis (DVP) and pulse wave analysis (PWA). Subclinical atherosclerosis was assessed by measurement of IMT. RESULTS: Stiffness Index (SI(DVP)), the measure of general arterial stiffness correlated significantly with IMT (r = 0.37, P < 0.01). IMT correlated significantly with age (r = 0.5, P < 0.0001), waist to hip ratio (WHR) (r = 0.39, P < 0.0001) and mean blood pressure (BPmean) (r = 0.4, P < 0.0001). IMT did not correlate with measures of wave reflection. SI(DVP) correlated significantly with age (r = 0.32, P < 0.005), WHR (r = 0.36, P < 0.0001), BPmean (r = 0.36, P < 0.0001) and measurements of wave reflection. However analysis of a model which included variables that significantly influenced SI(DVP) and IMT, such as age, WHR and mean BP showed that arterial stiffness is not independently associated with subclinical atherosclerosis. CONCLUSIONS: The indices of subclinical atherosclerosis, arterial stiffness and wave reflection, indicate different aspects of vascular status in otherwise healthy subjects.

Geometry of the Poincaré plot of RR intervals and its asymmetry in healthy adults.

The geometry of the Poincaré plot of RR intervals is considered and its basic descriptors are defined in terms of the second moment of a distribution of points in a plane. One of the standard descriptors, SD1, is redefined and used to define two new descriptors, SD1(UP) and SD1(DOWN), whose squares partition SD1(2) (the variance corresponding to short-term heart rate variability) into contributions from decelerations and accelerations of heart rate. It is shown that there is a visible and statistically highly significant asymmetry in the Poincaré plot, with the upper part, corresponding to decelerations of heart rate, larger than the lower part, which corresponds to accelerations. The effect is shown in one hundred 30 min long time series of RR intervals derived from the ECG recordings of 100 young (19-32 years old) and healthy adults. After shuffling the data to random order the asymmetry disappears, which shows that this is a genuine physiological phenomenon rather than an artefact of the method.

Difference in estimated GFR with two different formulas in elderly individuals.

The aim of this study was to characterize the differences between the prediction of GFR with Cockcroft-Gault formula (CG=(140-age)/(72 x PCr (mg/ml), for females multiplied by 0.85) and the new formula based on the multicenter trial of the Modification of Diet in Renal Diseases (MDRD=186 x P (Cr) (-1.154) x age(-0.203); 0.742 if patient is female) in elderly subjects. The study involved 100 individuals aged 65-111 years (mean age 88.3+/-14.7; 79 females and 21 males). In all subjects GFR was estimated according to both formulas mentioned above and expressed in ml/min/1.73 m2. Thereafter we calculated the difference between MDRD and CG (MDRD-CG) and analyzed its determinants in every subject. Mean GFR, obtained with MDRD was 76.0+/-24.0, whereas according to CG 67.9+/-18.6 (p < 0.0001). However, the mean MDRD-CG was up to 30.0+/-26.6 which means that MDRD results were much higher in comparison with CG. Using the multiple linear regression analysis we showed that MDRD-CG strongly depend on age (p < 0.0001), BMI (p < 0.0001) and serum creatinine concentration (p<0.0001). However, the gender has not effect on MDRD-CG value. The values of MDRD-CG strongly and positively correlated with age (r=0.7027, p < 0.0001) and negatively both with body mass index (r=-0.7171, p < 0.0001) and serum creatinine (r=-0.5590, p < 0.0001). In summary, our results show that the difference between MDRD and CG strongly depends on age, BMI and Scr. Investigators should be aware of these differences and take it into account in elderly.

Augmentation index, pulse pressure amplification and superoxide anion production in patients with coronary artery disease.

BACKGROUND: Free oxygen radicals appear to be involved in several processes that contribute to atherogenesis and increased arterial stiffness. METHODS: The aim of our study was to evaluate arterial stiffness and the production of superoxide anions by activated polymorphonuclear neutrophils (PMN) obtained from patients with stable coronary artery disease (CAD). Thirty four consecutive patients were studied (21 men, 13 women, mean age 58 years) who underwent coronary angiography. Arterial stiffness was assessed by pulse wave analysis using a validated system (Sphygmocor Mx, AtCor Medical). Superoxide anion production by activated neutrophils was determined by a spectrophotometric method involving the measurement of cytochrome C reduction. The extent of coronary narrowing was estimated by calculation of the Gensini score. RESULTS: Superoxide anion production by stimulated PMN showed a significant positive correlation with the augmentation index (AIx) and a significant negative correlation with pulse pressure amplification (PPA), (r=0.4, p=0.02; r=-0.5 and p=0.0026 respectively). In multivariable analyses, after adjustment for age, gender and Gensini score, superoxide anions and BMI were significant predictors of AIx (R2=57.37%, p=0.001) and PPA (R2=49.04%, p=0.008). Superoxide anion production was significantly higher in the middle (52.0+/-5.8 nmol O2-/2.5x10(6) PMN/30 min) and upper teriles (62.7+/-5.6) of AIx in comparison with the first tertile 31.8+/-4.1 (p< or =0.05, p< or =0.001). Moreover, superoxide anion production in the highest tertile of PPA was significantly lower (35.6+/-4.3 nmol O2-/2.5x10(6) PMN/30 min) than that in the tertile (60.8+/-6.2, p< or =0.05). Neither the augmentation index nor pulse pressure amplification correlate with the severity of coronary atherosclerosis as indicated by the Gensini score. CONCLUSIONS: markers of arterial stiffness, AIx and pulse pressure amplification correlate with superoxide anion production but not with the severity of atherosclerosis in coronary arteries.

[Heart rate variability in patients with chronic renal failure treated by hemodialysis]. / Zmiennosc rytmu zatokowego u chorych z przewlekla niewydolnoscia nerek leczonych zabiegami hemodializ.

Heart rate variability (HRV) is a non-invasive method used for the assessement of autonomic modulation of heart rate. Decreased HRV is an indicator of increased cardiovascular risk. The aim of this study was to evaluate the relationship between the heart rate variability and left ventricular hypertrophy and native parathormone (iPTH) serum concentration in patients with chronic renal failure (crf) treated by hemodialysis. 24-hours ECG recording with time domain HRV evaluation, resting, transthoracic echocardiography (ECHO), were measured in 59 crf patients and in 30 healthy volunteers. Creatinine, urea, total protein, albumin, electrolytes, hemoglobin, hematocrite and iPTH serum concentration as well as body mass index (BMI) were assessed in all patients. All crf patients had decreased lower values of HRV. The correlations between SDNN, pNN50, rMSSD and parameters of LVH and with PTH serum level indicated the disturbances of the autonomic function in chronic renal patients. Left ventricular hypertrophy (LVH) in all crf patients was observed. The correlations between iPTH serum level and parameters of LVH suggest the role of PTH in the development of uremic cardiomyopathy.

Kidney function estimated with different formulas in centenarians.

PURPOSE: There are growing doubts about the accuracy of Cockcroft-Gault formula (CG) used for the estimation of creatinine clearance, especially in elderly. Recently, the authors of the multicenter trial of the Modification of Diet in Renal Diseases (MDRD) have proposed a new equation. Moreover, Baracskay et al. (B), proposed the special formula for the estimation of kidney function (KF) in elderly. The aim of our study was to compare the results of KF calculated with these three formulas in centenarians. MATERIAL AND METHODS: The study involved 50 centenarian subjects aged 100-111 years (41 females and 9 males) who participated in Polish Centenarians Program. In all of them KF was estimated with the CG, B and MDRD formulas. RESULTS: In the whole population examined, the mean KF according to CG was lower in comparison to both others (p < 0.001 vs both B and MDRD). Also, in females CG results were the lowest (p < 0.001 vs both B and MDRD). In contrast, KF calculated according to CG and B did not differ in males. The results of the MDRD formula significantly exceeded the two others also in males (p < 0.001 vs CG and B). No impact of gender on the obtained results could be found when CG and MDRD were used. However, according to B, the mean values for females were higher (p < 0.01). CONCLUSIONS: KF calculated with the CG, B and MDRD formulas significantly differed in the centenarians examined. Thus, further studies, which include a reference standard, are necessary to answer the question which of these mathematical formulas is the most reliable for the calculation of KF in the elderly.

Prospective evaluation of hydroperoxide plasma levels and stable nitric oxide end products in patients subjected to angioplasty for coronary artery disease.

BACKGROUND: Oxidative stress appears to be involved in several processes that contribute to atherogenesis and restenosis following vascular intervention. METHODS: The aim of our study was to evaluate prospectively the plasma concentrations of a hydroperoxide (ROOH) and nitric oxide end product (NO(x)) in patients subjected to coronary angioplasty (PTCA) and routine control angiography 6 months after the initial procedure. We prospectively studied 48 consecutive patients (39 men, nine women, mean age 52 years) with stable angina who underwent successful elective angioplasty. A vascular segment was considered successfully treated when the residual luminal narrowing in the dilated segment immediately after angioplasty was <50%. Angiographic follow-up was obtained in all of the patients. Plasma samples were drawn at baseline (before angioplasty) and serially after angioplasty (1, 3 and 6 months afterwards). Hydroperoxides were determined by the FOX II assay (ferrous oxidation in xylenol orange, Pierce Rockford, IL). Nitrate was converted in the presence of NO3 reductase. The Griess reagent was used for the measurement of NO2. RESULTS: The overall angiographic restenosis rate was 35%. There were no significant differences in clinical variables between the patients with or without restenosis. The baseline levels (0.8+/-0.09 vs. 0.6+/-0.2 micromol/l) as well as the concentrations of authentic lipid hydroperoxide in plasma after 1 month (0.7+/-0.09 vs. 1.0+/-0.2 micromol/l) and 6 months (0.8+/-0.1 vs. 1.0+/-0.2 micromol/l) were similar in both groups. Three months after the angioplasty a significant increase in the ROOH level was noticed in the patients with restenosis (0.9+/-0.1 vs. 1.4+/-0.2, P=0.04). Plasma levels of NO(x) were similar in both groups at baseline (23.6+/-2.1 vs. 22.7+/-2.6 micromol/l) and 1 month after procedure (24.4+/-2.2 vs. 23.4+/-3.3 micromol/l). However, in patients with restenosis significant decreases in stable NO end products were observed 3 and 6 months after PTCA (18.1+/-1.5 vs. 13.3+/-1.7, P=0.04; 14.2+/-1.0 vs. 8.7+/-1.3, P=0.02, respectively). CONCLUSIONS: In patients with angiographic restenosis a significant increase in lipid peroxidation accompanied by a reduction in the stable end products of nitric oxide in plasma is observed several months after PTCA.

[Leukocytosis in the first day of acute ischemic stroke as a prognostic factor of disease progression]. / Leukocytoza w pierwszej dobie udaru niedokrwiennego mózgu jako czynnik prognostyczny przebiegu choroby.

It has been reported that white blood cells (WBC) may contribute to the initiation and further development of stroke. WBC count could have influence on hemorheology, thrombosis and induction of vasoconstriction in cerebral arteries. The aim of this work was to determine whether WBC count assessed in patients with acute stroke in the first day of the disease have a predictive value for the late clinical outcomes. Peripheral WBC count was measured at the admission to the hospital in 100 consecutive patients with acute stroke. Ischemic stroke was confirmed in all patients by head CT. Neurological status was evaluated with the use of modified Rankin's Scale. We assessed the following clinical outcomes: in-hospital mortality, the lack of neurological improvement on the 21st day of disease, and the need for hospital stay longer than 21 days. Odds ratio (OR) with 95% confidence interval (95% CI) adjusted for patient's age, gender, cardiovascular diseases, diabetes mellitus and previous stroke was calculated with the use of logistic regression. OR was evaluated both for the presence of WBC count > 10.000 cells/microliter and for each 1000 leukocytes/microliter increase. WBC count greater than 10.000 cells/microliter was associated with a more than seventy-fold greater risk for death (OR--75.18; 95% CI: 8.89-635.84; p = 0.0001), nearly eight times increased risk for the no-improvement status (OR--7.78; 95% CI: 2.51-24.17; p = 0.0004) and approximately four times increased risk for the prolonged hospital stay (OR--4.20; 95% CI: 1.50-11.72; p = 0.0062). Each 1000 cell/microliter increase in WBC count at the admission was associated with increased risk for in-hospital mortality (OR--2.24; 95% CI: 1.39-3.57; p = 0.0008), no neurological improvement (OR--1.43; 95% CI: 1.15-1.76; p = 0.0009) and the need for prolonged hospitalization (OR--1.26; 95% CI: 1.07-1.49; p = 0.0066). Increased WBC count within the first 12 hours of stroke is an independent and strong risk factor for mortality, no neurological improvement, and the need for prolonged hospitalization in the course of acute ischemic stroke.

Comparison of fentanyl and droperidol mixture (neuroleptanalgesia II) with morphine on clinical outcomes in unstable angina patients.

The objective of the study was to compare the influence of a fentanyl and droperidol mixture (neuroleptanalgesia) with morphine on the in-hospital instability, development of acute myocardial infarction (AMI), and mortality during a 30-day and 12-month follow-up in unstable angina patients. The study was performed in 112 unstable angina patients. In addition to standard therapy for unstable angina (aspirin, heparin, nitroglycerin, and oxygen), 53 patients (63.2 +/- 9.7 years; 32 males) were randomized to receive neuroleptanalgesia (0.025 mg fentanyl and 1.25 mg droperidol in a volume of 1 mL) and 59 patients (58.6 +/- 11.5 years; 41 males) to receive morphine. Neuroleptanalgesia was started i.v. with 2 mL and could be followed by 1 mL every 4 hours. Morphine was started i.v. with 10 mg and could be followed by 5 mg every 4 hours up to angina resolution during 24 hours of hospitalization. Another 1 mL of neuroleptanalgesia or 5 mg of morphine could be administered on demand if angina lasted or reappeared earlier than the next scheduled dose. Odds ratios with 95% confidence intervals (95% CI) adjusted for the age, sex, smoking, previous myocardial infarction, and hypertension were evaluated for all study outcomes. The odds ratios for clinical in-hospital instability (5.93, 95% CI: 2.49-14.15; P = 0.0001), 12-month AMI development (3.57, 95% CI: 1.51-8.45; P = 0.0038), and 12-month mortality (6.00, 95% CI: 1.63-22.09; P = 0.0070) were significantly increased in the neuroleptanalgesia group compared with the patients on morphine. It is concluded that neuroleptanalgesia negatively influences disease course, AMI development, and total mortality in unstable angina patients.

Effects of trimetazidine on clinical symptoms and tolerance of exercise of patients with syndrome X: a preliminary study.

BACKGROUND: Trimetazidine diminishes angina and improves tolerance of exercise of patients with ischemic heart disease, and has no influence on blood pressure and heart rate. OBJECTIVE: To determine the effect of trimetazidine on angina symptoms and exercise tolerance in patients with syndrome X. METHODS: We investigated the effect of trimetazidine on the clinical symptoms and tolerance of exercise of 34 patients (20 women and 14 men, aged 32-60 years) with syndrome X (angina pectoris, positive result of exercise test, and normal coronary angiogram). The exercise test was performed before initiation of oral administration of trimetazidine therapy (20 mg three times a day) and 1 and 6 months thereafter. RESULTS: We obtained negative results of exercise treadmill tests for four patients (11.76%) after 1 month and five patients (14.71%) after 6 months of trimetazidine treatment. There was also a decrease in the incidence of effort angina after 6 months of treatment (26 patients or 76.47% before treatment versus 13 patients or 38.23% after 6 months of treatment). The drug had no significant influence on the heart rate and blood pressure. The duration for which patients could exercise was significantly prolonged by 1 month (652.9 +/- 206.2 versus 563.4 +/- 190.4 s, P = 0.0047) and 6 months (650.3 +/- 207.8 s, P = 0.0094) of treatment with trimetazidine. CONCLUSION: Treatment with trimetazidine decreases signs of angina during exercise and improves tolerance of exercise of patients with syndrome X.