12 research outputs found
Discrimination of the Healthy and Sick Cardiac Autonomic Nervous System by a New Wavelet Analysis of Heartbeat Intervals
We demonstrate that it is possible to distinguish with a complete certainty
between healthy subjects and patients with various dysfunctions of the cardiac
nervous system by way of multiresolutional wavelet transform of RR intervals.
We repeated the study of Thurner et al on different ensemble of subjects. We
show that reconstructed series using a filter which discards wavelet
coefficients related with higher scales enables one to classify individuals for
which the method otherwise is inconclusive. We suggest a delimiting diagnostic
value of the standard deviation of the filtered, reconstructed RR interval time
series in the range of (for the above mentioned filter), below
which individuals are at risk.Comment: 5 latex pages (including 6 figures). Accepted in Fractal
Characterization of Sleep Stages by Correlations of Heartbeat Increments
We study correlation properties of the magnitude and the sign of the
increments in the time intervals between successive heartbeats during light
sleep, deep sleep, and REM sleep using the detrended fluctuation analysis
method. We find short-range anticorrelations in the sign time series, which are
strong during deep sleep, weaker during light sleep and even weaker during REM
sleep. In contrast, we find long-range positive correlations in the magnitude
time series, which are strong during REM sleep and weaker during light sleep.
We observe uncorrelated behavior for the magnitude during deep sleep. Since the
magnitude series relates to the nonlinear properties of the original time
series, while the signs series relates to the linear properties, our findings
suggest that the nonlinear properties of the heartbeat dynamics are more
pronounced during REM sleep. Thus, the sign and the magnitude series provide
information which is useful in distinguishing between the sleep stages.Comment: 7 pages, 4 figures, revte
A PROBABILITY ANALYSIS OF HEART RATE VARIABILITY FOR HEART TRANSPLANT AND MYOCARDIAL INFARCTION PATIENTS AND FOR HEALTHY SUBJECTS
Scale-specific and scale-independent measures of heart rate variability as risk indicators
We study the correlation properties of heartbeat fluctuations using
scale-specific variance (root-mean-square fluctuation) and scaling
(correlation) exponents as measures of healthy and cardiac impaired
individuals. Our results show that the variance and the scaling
exponent are uncorrelated. We find that the variance measure at
certain scales is well suited to separate healthy subjects from heart
patients. However, for mortality prediction the scaling exponents
outperform the variance measure. Our study is based on a database
containing recordings from 428 individuals after myocardial infarct
(MI) and on a database containing 105 healthy subjects and 11 heart
patients. The results have been obtained by applying two recently
developed methods (DFA -Detrended Fluctuation Analysis and WAV -Multiresolution
Wavelet Analysis) which are shown to be highly
correlated
Discrimination of the Healthy and Sick Cardiac Autonomic Nervous System by a New Wavelet Analysis of Heartbeat Intervals
Sex Differences in Wild-Type Transthyretin Amyloidosis: An Analysis from the Transthyretin Amyloidosis Outcomes Survey (THAOS)
Introduction: Wild-type transthyretin amyloidosis (ATTRwt amyloidosis) is a progressive disease resulting from the accumulation of wild-type transthyretin (TTR) amyloid fibrils, and is diagnosed primarily in males. This analysis examined sex differences in patients with ATTRwt amyloidosis from the Transthyretin Amyloidosis Outcomes Survey (THAOS). Methods: THAOS is an ongoing, global, longitudinal, observational survey of patients with transthyretin amyloidosis, including both inherited and wild-type disease, and asymptomatic carriers of TTR mutations. THAOS data were analyzed to identify potential differences in demographic and clinical characteristics between males and females with ATTRwt amyloidosis (data cutoff: August 1, 2021). Results: Of 1386 patients with ATTRwt amyloidosis, 84 (6%) were female and 1302 (94%) were male. Females had a higher median age at enrollment (80 vs. 78 years; p = 0.002) and symptom onset (75 vs. 73 years; p = 0.045) than males. Mean left ventricular (LV) ejection fraction was higher (53% vs. 48%; p = 0.001) and mean LV diastolic diameter lower (42 vs. 46 mm; p < 0.001) in females versus males, but sex was not identified as a predictor of LV mean wall thickness adjusted for height (beta coefficient − 0.22; p = 0.460) or a predominantly cardiac phenotype (odds ratio 1.60; p = 0.191). Modified polyneuropathy disability scores differed between groups (p < 0.001), with a larger proportion of scores ≥ IIIa among females (23% vs. 7%). Conclusions: Females with ATTRwt amyloidosis in THAOS tended to present at a later age and showed signs of less severe cardiac impairment and more severe walking impairment. Trial Registration: ClinicalTrials.gov: NCT00628745