Home About us Contact
|
Home About us Contact | ||
|
|
||
HRV Measures (hrv + measure)
Selected AbstractsInterleukin-6 Levels are Inversely Correlated with Heart Rate Variability in Patients with Decompensated Heart FailureJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2001DORON ARONSON M.D. Interleukin-6 and Heart Rate Variability.Introduction: Increased local and systemic elaboration of cytokines have an important role in the pathogenesis of congestive heart failure (CHF) through diverse mechanisms. Because cytokines are known to act at the neuronal level in both the peripheral and central nervous system, we sought to determine whether increased cytokine levels are associated with the autonomic dysfunction that characterizes CHF. Methods and Results: We studied 64 patients admitted for decompensated CHF (mean age 59 ± 12 years). Autonomic function was assessed using time, and frequency-domain heart rate variability (HRV) measures, obtained from 24-hour Holter recordings. In addition, norepinephrine, tumor necrosis factor-, (TNF-,), and interleukin-6 (IL-6) were measured in all patients. TNF-, levels did not correlate with any of the HRV measures. IL-6 inversely correlated with the time-domain parameters of standard deviation of RR intervals (SDNN) (r =,0.36, P = 0.004) and standard deviation of all 5,minute mean RR intervals (SDANN) (r =,0.39, P = 0.001), and with the frequency-domain parameters of total power (TP) (r =,0.37, P = 0.003) and ultralow-frequency (ULF) power (r =,0.43, P = 0.001). No correlation was found between IL-6 and indices of parasympathetic modulation. Using multiple linear regression models, adjusting for clinical variables and drug therapies, the strong inverse relationship between IL-6 and SDNN (P = 0.006), SDANN (P = 0.001), TP (P = 0.04), and ULF power (P = 0.0007) persisted. Conclusion: Reduction of long-term HRV indices is associated with increased levels of IL-6 in patients with decompensated heart failure. The ability of long-term HRV parameters to better reflect activation of diverse hormonal systems may explain their greater prognostic power for risk stratification in patients with CHF. [source] Comparison of finger plethysmograph to ECG in the measurement of heart rate variabilityPSYCHOPHYSIOLOGY, Issue 2 2002Nicholas D. Giardino Two experiments compared finger plethysmograph (FP) to electrocardiogram (ECG) in providing accurate heart periods for use in heart rate variability (HRV) calculations. In Experiment 1, simultaneous ECG and FP recordings were taken from 16 healthy subjects at rest. In Experiment 2, 10 additional healthy subjects were recorded at rest and during the Stroop Color-Word Test. In both studies, high correlations were found between FP-derived and ECG-derived band variance for high and low frequency HRV at rest. But, during the Stroop task, correlations were strongly diminished. In addition, under both conditions, HRV measures were significantly higher using the FP signal. Thus, FP may be adequate for determining HRV at rest, but, for experimental use, ECG may still be recommended. Nonetheless, further studies that include test,retest reliability assessment of both data collection techniques are warranted before a more certain determination can be made. [source] Heart Rate Variability Fraction,A New Reportable Measure of 24-Hour R-R Interval VariationANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2005Maciej Sosnowski M.D. Background: The scatterplot of R-R intervals has several unique features. Its numerical evaluation may produce a new useful index of global heart rate variability (HRV) from Holter recordings. Methods: Two-hundred and ten middle-aged healthy subjects were enrolled in this study. The study was repeated the next day in 165 subjects. Each subject had a 24-hour ECG recording taken. Preprocessed data were transferred into a personal computer and the standard HRV time-domain indices: standard deviation of total normal R-R intervals (SDNN), standard deviation of averaged means of normal R-R intervals over 5-minute periods (SDANN), triangular index (TI), and pNN50 were determined. The scatterplot area (0.2,1.8 second) was divided into 256 boxes, each of 0.1-second interval, and the number of paired R-R intervals was counted. The heart rate variability fraction (HRVF) was calculated as the two highest counts divided by the number of total beats differing from the consecutive beat by <50 ms. The HRVF was obtained by subtracting this fraction from 1, and converting the result to a percentage. Results: The normal value of the HRVF was 52.7 ± 8.6%. The 2,98% range calculated from the normal probability plot was 35.1,70.3%. The HRVF varied significantly with gender (female 48.7 ± 8.4% vs male 53.6 ± 8.6%, P = 0.002). The HRVF correlated with RRI (r = 0.525) and showed a similar or better relationship with SDNN (0.851), SDANN (0.653), and TI (0.845) than did the standard HRV measures with each other. Bland-Altman plot showed a good day-by-day reproducibility of the HRVF, with the intraclass correlation coefficient of 0.839 and a low relative standard error difference (1.8%). Conclusion: We introduced a new index of HRV, which is easy for computation, robust, reproducible, easy to understand, and may overcome the limitations that belong to the standard HRV measures. This index, named HRV fraction, by combining magnitude, distribution, and heart-rate influences, might become a clinically useful index of global HRV. [source] Characteristics of Heart Rate Variability Can Predict Impending Septic Shock in Emergency Department Patients with SepsisACADEMIC EMERGENCY MEDICINE, Issue 5 2007Wei-Lung Chen MD ObjectivesTo determine whether heart rate variability (HRV) measures can be used to predict which septic patients in the emergency department (ED) will progress to septic shock. MethodsThe authors prospectively enrolled consecutive patients who met the 2001 International Sepsis Definitions Conference criteria of sepsis and visited the ED of a university teaching hospital over a six-month period. In addition to the septic workup, a continuous 10-minute electrocardiogram recording was performed at the same time. The HRV measures were calculated off-line and correlated with the outcome of the patients. ResultsEighty-one patients aged 30,84 years who met the inclusion criteria were enrolled. The patients were classified as those with no septic shock (n= 60) and those with septic shock (n= 21), according to their outcome within six hours. The baseline root mean square successive difference, high-frequency power, and normalized high-frequency power of the septic shock group were significantly higher than those of the no septic shock group. The low-frequency power, normalized low-frequency power, and low-/high-frequency power ratio of the septic shock group were significantly lower than those of the no septic shock group. Multiple logistic regression analysis identified root mean square successive difference as the best predictor of impending septic shock for septic ED patients. ConclusionsHRV measures may be used to identify septic ED patients with impending septic shock. Among those HRV measures, root mean square successive difference seems to be the best indicator to predict the occurrence of septic shock. [source] | ||||||||||