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Objective: We investigated the accuracy of the OMRON HEM-7361T automated oscillometric blood pressure (BP) monitor in the differentiation between atrial fibrillation and sinus rhythm., Methods: An approximately equal number of patients with persistent atrial fibrillation and individuals with sinus rhythm were recruited from outpatients and inpatients of Ruijin Hospital, Shanghai, China. BP was measured three times consecutively with a 30-s interval with the OMRON HEM-7361T automatic electronic BP monitor for atrial fibrillation detection. A hand-held single lead electrocardiogram device was used for simultaneous electrocardiogram recordings., Results: The device accurately identified atrial fibrillation in 100 (99.0%) of the 101 patients, with only 1 patient incorrectly classified as non-atrial fibrillation. The device correctly identified 99 (95.2%) of the 104 participants with sinus rhythm as non-atrial fibrillation, with five participants incorrectly classified as atrial fibrillation. The device had a positive predictive value of 95.2%, negative predictive value of 99.0%, and overall accuracy of 97.1%. Among the six misclassified participants, one with atrial fibrillation had a heart rate of 65 beats/min, and four of the five participants with sinus rhythm had cardiac arrhythmias (atrial or ventricular premature beat in one participants, sinus tachycardia in one participant, and both arrhythmias in one participant)., Conclusion: The OMRON HEM-7361T BP monitor is accurate in the differentiation between atrial fibrillation and sinus rhythm. Whether the device is sufficiently accurate in the differentiation between atrial fibrillation and other cardiac arrhythmias remains under investigation., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: The Apple Watch™ (AW) offers heart rate (HR) tracking by photoplethysmography (PPG) and single-lead electrocardiographic (ECG) recordings. The accuracy of AW-HR and diagnostic performance of AW-ECGs among children during both sinus rhythm and arrhythmias have not been explored., Objective: The purposes of this study were to assess the accuracy of AW-HR measurements compared to gold standard modalities in children during sinus rhythm and arrhythmias and to identify non-sinus rhythms using AW-ECGs., Methods: Subjects ≤18 years wore an AW during (1) telemetry admission, (2) electrophysiological study (EPS), or (3) exercise stress test (EST). AW-HRs were compared to gold standard modality values. Recorded AW-ECGs were reviewed by 3 blinded pediatric electrophysiologists., Results: Eighty subjects (median age 13 years; interquartile range 1.0-16.0 years; 50% female) wore AW (telemetry 41% [n = 33]; EPS 34% [n = 27]; EST 25% [n = 20]). A total of 1090 AW-HR measurements were compared to time-synchronized gold standard modality HR values. Intraclass correlation coefficient (ICC) was high 0.99 (0.98-0.99) for AW-HR during sinus rhythm compared to gold standard modalities. ICC was poor comparing AW-HR to gold standard modality HR in tachyarrhythmias (ICC 0.24-0.27) due to systematic undercounting of AW-HR values. A total of 126 AW-ECGs were reviewed. Identification of non-sinus rhythm by AW-ECG showed sensitivity of 89%-96% and specificity of 78%-87%., Conclusions: We found high levels of agreement for AW-HR values with gold standard modalities during sinus rhythm and poor agreement during tachyarrhythmias, likely due to hemodynamic effects of tachyarrhythmias on PPG-based measurements. AW-ECGs had good sensitivity and moderate specificity in identification of non-sinus rhythm in children., Competing Interests: Disclosures Dr Shah serves as a consultant for Medtronic. All other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Objective. The respiratory sinus arrhythmia (RSA) is a well-known marker of vagal activity that can be exploited to measure stress changes. RSA is usually estimated from heart rate variability (HRV). This study aims to compare the RSA obtained with three widely adopted methods showing their strengths and potential pitfalls. Approach. The three methods are tested on 69 healthy preschoolers undergoing a stressful protocol, the strange situation procedure (SSP). We compare the RSA estimated by the Porges method, the univariate autoregressive (AR) spectral analysis of the HRV signal, and the bivariate AR spectral analysis of HRV and respirogram signals. We examine RSA differences detected across the SSP episodes and correlation between the estimates provided by each method. Main results. The Porges and the bivariate AR approaches both detected significant differences (i.e. stress variations) in the RSA measured across the SSP. However, the latter method showed higher sensitivity to stress changes induced by the procedure, with the mean RSA variation between baseline and first separation from the mother (the most stressful condition) being significantly different among methods: Porges, -17.5%; univariate AR, -18.3%; bivariate AR, -23.7%. Moreover, the performances of the Porges algorithm were found strictly dependent on the applied preprocessing. Significance. Our findings confirm the bivariate AR analysis of the HRV and respiratory signals as a robust stress assessment tool that does not require any population-specific preprocessing of the signals and warn about using RSA estimates that neglect breath information in more natural experiments, such as those involving children, in which respiratory frequency changes are extremely likely., (© 2021 Institute of Physics and Engineering in Medicine.)

Objective: Respiratory sinus arrhythmia (RSA) refers to heart rate oscillations synchronous with respiration, and it is one of the major representations of cardiorespiratory coupling. Its strength has been suggested as a biomarker to monitor different conditions, and diseases. Some approaches have been proposed to quantify the RSA, but it is unclear which one performs best in specific scenarios. The main objective of this study is to compare seven state-of-the-art methods for RSA quantification using data generated with a model proposed to simulate, and control the RSA. These methods are also compared, and evaluated on a real-life application, for their ability to capture changes in cardiorespiratory coupling during sleep., Methods: A simulation model is used to create a dataset of heart rate variability, and respiratory signals with controlled RSA, which is used to compare the RSA estimation approaches. To compare the methods objectively in real-life applications, regression models trained on the simulated data are used to map the estimates to the same measurement scale. Results, and conclusion: RSA estimates based on cross entropy, time-frequency coherence, and subspace projections showed the best performance on simulated data. In addition, these estimates captured the expected trends in the changes in cardiorespiratory coupling during sleep similarly., Significance: An objective comparison of methods for RSA quantification is presented to guide future analyses. Also, the proposed simulation model can be used to compare existing, and newly proposed RSA estimates. It is freely accessible online.

Objective: This paper proposes an approach to better estimate the sympathovagal balance (SB) and the respiratory sinus arrhythmia (RSA) after separating respiratory influences from the heart rate (HR)., Methods: The separation is performed using orthogonal subspace projections and the approach is first tested using simulated HR and respiratory signals with different spectral properties. Then, RSA and SB are estimated during autonomic blockade and stress using the proposed approach and the classical heart rate variability (HRV) analysis. Both real- and ECG-derived respiration (EDR) are used and the reliability of the EDR is evaluated., Results: Mean absolute percentage errors lower than [Formula: see text] were obtained after removing previously known respiratory signals from simulated HR. The proposed indices were able to improve the quantification of SB during autonomic withdrawal. In the stress data, differences ( ) among relaxed and stressful phases were found with the proposed approach, using both the real respiration and the EDR, but they disappeared when using the classical HRV., Conclusion: A better assessment of the autonomic nervous system' response to pharmacological blockade and stress can be achieved after removing respiratory influences from HR, and this can be done using either the real respiration or the EDR., Significance: This work can be used to better identify vagal withdrawal and increased sympathetic activation when the classical HRV analysis fails due to the respiratory influences on HR. Furthermore, it can be computed using only the ECG, which is an advantage when developing wearable systems with limited number of sensors.

This paper presents non-contact vital sign monitoring in neonates, based on image processing, where a standard color camera captures the plethysmographic signal and the heart and breathing rates are processed and estimated online. It is important that the measurements are taken in a non-invasive manner, which is imperceptible to the patient. Currently, many methods have been proposed for non-contact measurement. However, to the best of the authors' knowledge, it has not been possible to identify methods with low computational costs and a high tolerance to artifacts. With the aim of improving contactless measurement results, the proposed method based on the computer vision technique is enhanced to overcome the mentioned drawbacks. The camera is attached to an incubator in the Neonatal Intensive Care Unit and a single area in the neonate's diaphragm is monitored. Several factors are considered in the stages of image acquisition, as well as in the plethysmographic signal formation, pre-filtering and filtering. The pre-filter step uses numerical analysis techniques to reduce the signal offset. The proposed method decouples the breath rate from the frequency of sinus arrhythmia. This separation makes it possible to analyze independently any cardiac and respiratory dysrhythmias. Nine newborns were monitored with our proposed method. A Bland-Altman analysis of the data shows a close correlation of the heart rates measured with the two approaches (correlation coefficient of 0.94 for heart rate (HR) and 0.86 for breath rate (BR)) with an uncertainty of 4.2 bpm for HR and 4.9 for BR (k = 1). The comparison of our method and another non-contact method considered as a standard independent component analysis (ICA) showed lower central processing unit (CPU) usage for our method (75% less CPU usage).

Aims: Intermittent change in p-wave discernibility during periods of ectopy and sinus arrhythmia is a cause of inappropriate atrial fibrillation (AF) detection in insertable cardiac monitors (ICM). To address this, we developed and validated an enhanced AF detection algorithm., Methods and Results: Atrial fibrillation detection in Reveal LINQ ICM uses patterns of incoherence in RR intervals and absence of P-wave evidence over a 2-min period. The enhanced algorithm includes P-wave evidence during RR irregularity as evidence of sinus arrhythmia or ectopy to adaptively optimize sensitivity for AF detection. The algorithm was developed and validated using Holter data from the XPECT and LINQ Usability studies which collected surface electrocardiogram (ECG) and continuous ICM ECG over a 24-48 h period. The algorithm detections were compared with Holter annotations, performed by multiple reviewers, to compute episode and duration detection performance. The validation dataset comprised of 3187 h of valid Holter and LINQ recordings from 138 patients, with true AF in 37 patients yielding 108 true AF episodes ≥2-min and 449 h of AF. The enhanced algorithm reduced inappropriately detected episodes by 49% and duration by 66% with <1% loss in true episodes or duration. The algorithm correctly identified 98.9% of total AF duration and 99.8% of total sinus or non-AF rhythm duration. The algorithm detected 97.2% (99.7% per-patient average) of all AF episodes ≥2-min, and 84.9% (95.3% per-patient average) of detected episodes involved AF., Conclusion: An enhancement that adapts sensitivity for AF detection reduced inappropriately detected episodes and duration with minimal reduction in sensitivity.

Infectious diseases, such as dengue fever and Middle East respiratory syndrome, have become prevalent worldwide in recent times. To conduct highly accurate and effective infection screening, we are working on the development of a contactless infection screening system using Doppler radar and thermography. In our previous work, three parameters (face temperature, heartbeat rate, and respiration rate) were used to judge whether a subject was infected. However, facial temperature measurements may be vastly different from temperatures measured at the axilla owing to influence from the immediate environment. In this study, heartbeat rate (HR), respiration rate (RR), and standard deviation of heartbeat interval (SDHI) were used to quantify the infection screening system without using facial temperature as a parameter. We found that respiratory sinus arrhythmia (RSA) diminished in patients who had dengue fever. We gathered data from 47 patients with dengue fever using a 10-GHz Doppler radar system at the National Hospital of Tropical Diseases (NHTD) in Hanoi, Vietnam. To evaluate the accuracy, the data of these patients were compared to that of 23 unaffected subjects. We observed that a linear discriminant analysis (LDA) was effective at detecting the dengue fever conditions, and the detection accuracy was approximately 97.6%.

Background: A significant minority of cardiac transplant patients require permanent pacemaker (PPM) implant, primarily for sinus node dysfunction. The stability of pacing indices has not been determined in this unique patient population, and data regarding ongoing need for pacing are limited., Methods: Pacing indices (sensing, threshold, and impedance) as well as the percentage of time patients required pacing were recorded, from 30 cardiac transplant patients that underwent PPM implant, over 1 year of follow-up. Repeated measure ANOVA (analysis of variance) was used to compare pacing indices and the percentage of time patients required pacing in each cardiac chamber (right atrium (RA) and right ventricle (RV)) and at different time points., Results: There was no difference in sensing among the follow-up time points (p = 0.9). Thresholds at 3 months were significantly higher compared to the day of implant (p = 0.005) and the day after implant (p = 0.03). Impedances at implant were significantly higher compared to day 1 (p < 0.001), 3 months (p < 0.003), and 12 months (p < 0.001) post-implant. The mean percentage of RA pacing was 85 ± 6% the day after implant, 74 ± 6% at 3 months, and 80 ± 6% at 1 year (p = 0.17)., Conclusion: In cardiac transplant patients, pacing impedances decrease and thresholds trend up in short-term follow-up, but subsequent sensing, threshold, and impedance remain stable at 1 year. This is comparable to the pattern observed among noncardiac transplant PPM recipients. The atrial pacing percentage was stable over 1 year, suggesting continued relative sinus node dysfunction.

Background: The underwater environment presents physiological challenges for the cardiovascular, renal and pulmonary systems. Increases in external hydrostatic pressure reduce the capacity of the venous compartment and cause blood to move toward the lung. The aim of this study was to evaluate retrospectively electrocardiographic (ECG) changes in a cohort of professional divers., Methods: Between January 2009 and January 2012, 225 randomly selected professional divers, 204 male (91%) and 21 female (9%) attended our clinic for their biannual diving medical assessment. Their ECG records were evaluated retrospectively., Results: The most common ECG abnormality observed was incomplete right bundle branch block (IRBBB) in 30 divers (13.3%). Eleven divers (4.9%) showed right QRS axis deviation (seven with IRBBB). Six divers had a sinus tachycardia; in four divers there was early repolarization; three divers had ventricular extrasystoles; one diver had ST elevation in lead V3; there was one with sinus arrhythmia and another with T-wave inversion in leads V2, V3 and aVF. These ECG changes were evaluated retrospectively by a cardiologist who made various recommendations for further review including bubble contrast echocardiography for IRBBB., Conclusions: No serious ECG abnormalities were identified, but IRBBB should be further investigated because of its association with persistent (patent) foramen ovale. Rapid cardiological review of ECGs could be achieved using modern communications technology, such as telecardiography, and further clinical investigations directed by specialist recommendation arranged promptly if indicated.

In this study, we were focused on the differences between certain circulating cytokine levels in patients with or without sinus arrhythmia, according to the median IL-6 level. All patients were stable with regards to symptoms and therapy for at least one month prior to the measurements conducted within this study.Exclusion criteria were: patients with sleep apnea, asthma, respiratory insufficiency of any genesis, active infection, allergy, inflammatory diseases, cancer, diabetes of any type and treatment with anti-inflammatory drugs. The study was approved by the Institutional Review Board. All recruited patients gave their verbal and written consent for participation in the study. The study group consisted of 74 patients divided into two groups: with (38) and without sinus arrhythmia but with diagnosed coronary artery disease (36). Sinus arrhythmia was confirmed by 24h Holter monitoring. From all test parameters only cytokines IL-2, IL-8, IL-10, IL-17 and IL-18, showed statistically significant increasing in patients with statistically higher IL-6 levels. It is possible that IL-6 may not be a marker for the selection of patients with sinus arrhythmia or coronary artery disease. The findings indicate that IL-6 represents a reliable indicator for increased expression of IL-2, IL-8, IL-10, IL-17 and IL-18 in patients with sinus arrhythmia or coronary artery disease. Further studies in a large number of patients would be necessary to confirm our observations., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Stroke is the leading cause of disability worldwide. It is known that atrial fibrillation and left atrial enlargement contribute ischemic stroke, and mean platelet volume (MPV) increases in patients with ischemic stroke and atrial fibrillation. We aimed to determine whether higher MPV is associated with ischemic stroke in patients with sinus rhythm. We evaluated 74 patients in sinus rhythm and with ischemic stroke (Group 1) and 90 age-matched and sex-matched healthy individuals as control group (Group 2). After physical and echocardiographic examination, 24-48 h Holter monitoring and complete blood counts were studied. There were no statistically significant differences in age, sex rates, and comorbidities between groups. Left atrial diameter was higher in Group 1 than Group 2 (P = 0.001), but both were in normal range. MPV was significantly higher in Group 1 (P < 0.001) and was an independent determinant [odds ratio (OR): 1.840; P < 0.001; 95% confidence interval (CI) 1.330-2.545] of ischemic stroke with left atrial (OR: 1.138; P = 0.006; 95% CI 1.037-1.248). In conclusion, higher MPV is associated with acute ischemic stroke in patients with sinus rhythm and without heart failure or left atrial enlargement. MPV and left atrial diameter are independent predictors of ischemic stroke in this patient population.

A furuncle on the leg of a 23-year-old woman led to methicillin-resistant staphylococcus aureus sepsis and adult respiratory distress syndrome (ARDS) requiring tracheal intubation in the intensive care unit (ICU). Initially her electrocardiograms (ECGs) showed sinus tachycardia, but otherwise were unchanged from prior ECGs. A week into her ICU stay a different rhythm occurred.

Background: Concealed sinus node dysfunction (SND) may become manifest after restoration of sinus rhythm by ablation in patients with persistent atrial fibrillation (AF). The purpose of this study was to investigate the predictors of SND after catheter ablation of persistent AF., Methods: Two hundred two consecutive patients who underwent ablation for persistent AF were enrolled. Ipsilateral pulmonary vein isolation followed by, if necessary, electrical cardioversion were performed in all patients. SND was defined when temporary and/or permanent pacemakers were needed due to sinus bradycardia after ablation., Results: SND developed in 12 (5.9 %) patients. There was no difference between the patients with and without SND in terms of the age (with SND, 67 ± 9 and without, 66 ± 10 years old, P = 0.599) and sex (male; 58 vs. 79 %, P = 0.186). However, the patients with SND had a lower amplitude of the fibrillatory waves (0.115 ± 0.086 vs. 0.176 ± 0.077 mV, P = 0.009) and larger left atrial volume index (LAVI; 66 ± 31 vs. 34 ± 13, P = 0.007) than those without. A receiver operating characteristic curve identified a fibrillatory wave amplitude of 0.145 mV (AUC = 0.742; sensitivity = 65 %; specificity = 83 %) and LAVI of 47.5 ml/m(2) (AUC = 0.837; sensitivity = 82 %; specificity = 87 %) as the optimal cutoff values for predicting SND. A multivariate analysis revealed that the amplitude of the fibrillatory waves (odds ratio = 0.84 for 0.010 mV increase, 95 % CI = 0.71-0.98, P = 0.031) and LAVI (odds ratio = 1.08 for 1.0 cm(3)/m(2) increase, 95 % CI = 1.04-1.12, P < 0.001) were independent risk factors for SND., Conclusions: A low amplitude of the fibrillatory waves and a large LAVI were predictors of SND after restoration of sinus rhythm by ablation in patients with persistent AF.

Purpose: Hypercapnia increases minute ventilation (V’E) with little effect on heart rate (HR), whereas hypoxia may increase HR without affecting V’E. However, the effects of hypercapnia and hypoxia on both heart rate variability(HRV) and the clustering of heart beats during spontaneous breathing (respiratory sinus arrhythmia – RSA), are not clear., Methods: In this study, 10 human volunteers breathed room air (RA), hypercapnic (5% CO2) or hypoxic (10%O2) gas mixtures, each for 6 min, while resting supine. ECG, mean arterial pressure (MAP), ventilatory flow, inhaled and exhaled fractions of CO2 and O2, were recorded throughout., Results: Both V’E and MAP increased with 5%CO2, with no change in HR. Hypoxia did not change ventilation but increased HR. High frequency components of HRV, and the relative proportion of heart beats occurring during inhalation increased with 5% CO2, but neither changed with 10% O2., Conclusion: Increased RSA concomitant with increased MAP suggests RSA – vagal dissociation with hypercapnia. Elevated heart rate with acute hypoxia with no change in either frequency components of HRV or the distribution of heart beats during ventilation, suggested that clustering of heart beats may not be a mechanism to improve ventilation-perfusion matching during hypoxia.

Background: The ventriculophasic response (VR) refers to shortening of sinus cycle length during heart block when a QRS complex is interposed between 2 P waves. Our purpose was to analyze its relationship to respiratory sinus arrhythmia (SA) and to compare VR in relation to paced versus intrinsic QRS complexes., Methods: Patients with advanced heart block had their pacer devices temporarily programmed to ventricular inhibited mode at 30 ppm. In 35 subjects, we analyzed VR and SA before, during and after 3 cycles of deep breathing. In 16 other patients we compared VR in the presence of paced versus narrower intrinsic QRS complexes., Results: The magnitude of P-P interval shortening surrounding QRS complexes during inspiration correlated with SA (r = 0.36, P = 0.03). The prevalence of VR increased from 37% at baseline to 77% of subjects during deep breathing (P = 0.02). The mean P-P interval shortening was greater surrounding intrinsic QRS complexes than paced QRS complexes (3.6 ± 3.6% vs. 1.4 ± 1.1%, P = 0.02). The prevalence of VR increased from 25% during paced rhythm to 56% when intrinsic complexes were present., Conclusion: VR, like SA, increases with deep breathing and likely reflects intact parasympathetic nervous system function. Its increase in the presence of narrower beats suggests it may reflect ventricular synchrony., (©2013, Wiley Periodicals, Inc.)

The current study evaluated processes underlying two common symptoms (i.e., state regulation problems and deficits in auditory processing) associated with a diagnosis of autism spectrum disorders. Although these symptoms have been treated in the literature as unrelated, when informed by the Polyvagal Theory, these symptoms may be viewed as the predictable consequences of depressed neural regulation of an integrated social engagement system, in which there is down regulation of neural influences to the heart (i.e., via the vagus) and to the middle ear muscles (i.e., via the facial and trigeminal cranial nerves). Respiratory sinus arrhythmia (RSA) and heart period were monitored to evaluate state regulation during a baseline and two auditory processing tasks (i.e., the SCAN tests for Filtered Words and Competing Words), which were used to evaluate auditory processing performance. Children with a diagnosis of autism spectrum disorders (ASD) were contrasted with aged matched typically developing children. The current study identified three features that distinguished the ASD group from a group of typically developing children: 1) baseline RSA, 2) direction of RSA reactivity, and 3) auditory processing performance. In the ASD group, the pattern of change in RSA during the attention demanding SCAN tests moderated the relation between performance on the Competing Words test and IQ. In addition, in a subset of ASD participants, auditory processing performance improved and RSA increased following an intervention designed to improve auditory processing., (Copyright © 2012 Elsevier B.V. All rights reserved.)

We examined indices of children's parasympathetic nervous system activity (PNS), including respiratory sinus arrhythmia during baseline (RSAB) and RSA reactivity (RSAR), to a laboratory challenge, and importantly the interaction between RSAB and RSAR as predictors of multiple parameters of children's sleep. Lower RSAR denotes increased vagal withdrawal (reductions in RSA between baseline and task) and higher RSAR represents decreased vagal withdrawal or augmentation (increases in RSA between baseline and task). A community sample of school-attending children (121 boys and 103 girls) participated [mean age = 10.41 years; standard deviation (SD) = 0.67]. Children's sleep parameters were examined through actigraphy for 7 consecutive nights. Findings demonstrate that RSAB and RSAR interact to predict multiple sleep quality parameters (activity, minutes awake after sleep onset and long wake episodes). The overall pattern of effects illustrates that children who exhibit more disrupted sleep (increased activity, more minutes awake after sleep onset and more frequent long wake episodes) are those with lower RSAB in conjunction with lower RSAR. This combination of low RSAB and low RSAR probably reflects increased autonomic nervous system arousal, which interferes with sleep. Results illustrate the importance of individual differences in physiological regulation indexed by interactions between PNS baseline activity and PNS reactivity for a better understanding of children's sleep quality., (© 2012 European Sleep Research Society.)

Background: Heart failure (HF) complicated by atrial fibrillation/flutter (AF/AFL) is associated with worse outcomes. However, the clinical profile and outcomes of patients following hospitalization for HF with AF/AFL on initial electrocardiogram (ECG) has not been well studied., Methods: EVEREST was a randomized trial of vasopressin-2 receptor blockade, in addition to standard therapy, in 4133 patients hospitalized with HF with ejection fraction ≤40%. A post hoc analysis was performed comparing the clinical characteristics and outcomes [all-cause mortality and cardiovascular mortality/HF hospitalization] of patients with AF/AFL versus sinus rhythm (SR) on baseline ECG, which were centrally analyzed. Times to events were compared using log-rank tests and Cox regression models., Results: Of the 4133 patients, 1195 (29%) were classified with AF/AFL and 2071(50%) with SR. The remaining patients (21%) were excluded because ECGs were unavailable (n = 106), rhythm was paced (n = 727), or junctional/other supraventricular (n = 34). AF/AFL patients were older, with increased weight, faster heart rate, higher blood urea nitrogen, and natriuretic peptide levels compared to SR patients. Anticoagulation was prescribed in 67% of AF/AFL patients on discharge. AF/AFL patients were less likely to receive β-blockers or angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (all P < .05). After risk adjustment, AF/AFL was associated with increased mortality (hazard ratio 1.23; 95% CI, 1.04-1.46) and cardiovascular mortality/HF hospitalization (hazard ratio 1.26; 95% CI, 1.07-1.47)., Conclusion: AF/AFL on initial ECG in patients hospitalized with HF with reduced ejection fraction is associated with lower use of evidence-based therapies and increased mortality and rehospitalization compared to patients in SR., (Copyright © 2012 Mosby, Inc. All rights reserved.)

We examined the association between preschoolers' (N=29; 20 boys; M age = 3.99 years, SD=.69) daytime parasympathetic nervous system (PNS) activity indexed by respiratory sinus arrhythmia (RSA) and their nighttime sleep. Children's baseline RSA was assessed in the laboratory. Sleep was monitored for seven consecutive nights at the child's home via actigraphy and the following sleep parameters were derived: sleep minutes, sleep activity index and sleep efficiency. Regression analyses showed that after controlling for potential confounds, higher RSA was a predictor of lower sleep activity and higher sleep efficiency. Results highlight the importance of physiological regulation for the sleep of healthy preschool children., (Copyright © 2012 Elsevier Inc. All rights reserved.)

To explore the energy proportion of the QRS complexes in the electrocardiogram (ECG), a new method, wavelet analysis, has been presented. Using wavelet transform of ECG, we can calculate the energy proportion of QRS complexes in multiple scales. The electrocardiograms (ECGs) were used as the experimental data, which were collected from a young (21-34 yr) group and an elderly (68-81 yr) group of healthy subjects, as well as from a group of arrhythmia patients (66-81 yr). the data analysis was performed with the energy proportion of the QRS complexes in the ECG using Mexican-Hat as a mother wavelet in multiple scales. Results showed that the energy proportion of the QRS complexes had no changes with ages increasing (P > 0.44), but in the same age group, the arrhythmia patients' energy proportion of the QRS complexes near 17Hz are obviously less than that in the healthy group (P < 0.01), so the energy proportion of the QRS complexes calculated by wavelet analysis can be used as a feature index to judge whether a person is a sinus arrhythmia patient or not.

The current study explored the effects of talking on respiratory sinus arrhythmia (RSA) during a semi-structured emotional interview (Adult Attachment Interview) using 76 female undergraduates. The effectiveness of 2 different methodological approaches (i.e. talking baseline or transfer function) was explored as respiratory control during talking tasks. RSA was collected during resting baseline, talking baseline, and interview conditions. Subjective reports of distress were higher in the interview than in the other 2 conditions. Mean RSA levels were significantly lower in the 2 talking tasks than in the resting baseline. After applying a transfer function for respiratory control, there were no significant differences between the 3 conditions. Moderator analyses yielded lower RSA values in the talking baseline and interview conditions for participants who reported greater distress during the interview. It was concluded that respiratory controls are likely necessary when using RSA in talking paradigms and that both approaches appeared to be adequate., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: We assessed trajectories of children's internalizing symptoms as predicted by interactions among maternal internalizing symptoms, respiratory sinus arrhythmia (RSA) and child sex., Method: An ethnically and socioeconomically diverse sample of children (n = 251) participated during three study waves. Children's mean ages were 8.23 years (SD = 0.72) at T1, 9.31 years (SD = 0.79) at T2 and 10.28 years (SD = 0.99) at T3., Results: Multiple-indicator multilevel latent growth analyses showed maternal internalizing symptoms interacted with child RSA and sex to predict children's internalizing symptoms. Girls with higher RSA whose mothers had lower levels of internalizing symptoms showed the steepest decline in internalizing symptoms across time. Girls with lower RSA whose mothers had higher levels of internalizing symptoms showed the highest levels of internalizing symptoms at T3, whereas boys with higher RSA whose mothers had higher levels of internalizing symptoms showed the highest levels of internalizing symptoms at T3., Conclusions: Findings build on this scant literature and support the importance of individual differences in children's physiological regulation in the prediction of psychopathology otherwise associated with familial risk., (© 2011 The Authors. Journal of Child Psychology and Psychiatry © 2011 Association for Child and Adolescent Mental Health.)

Respiratory sinus arrhythmia (RSA) has been widely used as a measure of the cardiac vagal control in response to stress. However, RSA seems not to be a generalized indicator because of its dependency on respiratory parameter and individual variations of RSA amplitude (A(RSA)). We hypothesized that phase-lag variations between RSA and respiration may serve as a normalized index of the degree of mental stress. Twenty healthy volunteers performed mental arithmetic task (ART) after 5 min of resting control followed by 5 min of recovery. Breathing pattern, beat-to-beat R-R intervals, and blood pressure (BP) were determined using inductance plethysmography, electrocardiography, and a Finapres device, respectively. The analytic signals of breathing and RSA were obtained by Hilbert transform and the degree of phase synchronization (λ) was quantified. With the use of spectral analysis, heart rate variability (HRV) was estimated for the low-frequency (LF) and high-frequency (HF) bands. A steady-state 3-min resting period (REST), the first 3 min (ART1), and the last 3 min (ART2) of the ART period (ranged from 6- to 19 min) and the last 3 min of the recovery period (RCV) were analyzed separately. Heart rate, systolic BP, and breathing frequency (f(R)) increased and λ, A(RSA), and HF power decreased from REST to ART (P < 0.01). The λ was correlated with normalized A(RSA) and the HF power. The decrease in λ could not be explained solely by the increase in f(R). We conclude that mental stress exerts an influence on RSA oscillations, inducing incoherent phase lag with respect to breathing, in addition to a decrease in RSA.

Time-variant partial directed coherence (tvPDC) is used for the first time in a multivariate analysis of heart rate variability (HRV), respiratory movements (RMs) and (systolic) arterial blood pressure. It is shown that respiration-related HRV components which also occur at other frequencies besides the RM frequency (= respiratory sinus arrhythmia, RSA) can be identified. These additional components are known to be an effect of the 'half-the-mean-heart-rate-dilemma' ('cardiac aliasing' CA). These CA components may contaminate the entire frequency range of HRV and can lead to misinterpretation of the RSA analysis. TvPDC analysis of simulated and clinical data (full-term neonates and sedated patients) reveals these contamination effects and, in addition, the respiration-related CA components can be separated from the RSA component and the Traube-Hering-Mayer wave. It can be concluded that tvPDC can be beneficially applied to avoid misinterpretations in HRV analyses as well as to quantify partial correlative interaction properties between RM and RSA.

5-Fluorouracil (5-FU) is a commonly used anti-neoplastic agent. 5-FU has been not uncommonly associated with cardiotoxicity, although the many potentially causative mechanisms are yet to be established. Here, we present the case of a 61-year-old gemstone miner who developed symptomatic sinus bradycardia while receiving a continuous 5-FU infusion combined with radiotherapy for locally advanced rectal cancer. This dysrhythmia is an unusual type of 5-FU toxicity, our case being the second described. We review the actions of 5-FU and the various proposed mechanisms of its cardiotoxic effects., (© 2011 The Authors. Internal Medicine Journal © 2011 Royal Australasian College of Physicians.)

Objective: Rheumatoid arthritis (RA) is a chronic systemic disease. The risk of cardiovascular morbidity and mortality is high in patients with RA. Heart rate turbulence (HRT) expresses ventriculophasic sinus arrhythmia and has been considered to reflect cardiac autonomic activity. It has been shown that HRT is an independent and powerful predictor of mortality. The aim of this study is to determine if HRT changes in patients with RA in comparison with the healthy controls., Methods: The study was performed as a cross-sectional study. Twenty-six patients with RA (mean age 56 ± 10 years, 18 women) and 26 healthy controls (mean age 55 ± 9 years, 18 women) were enrolled in this study. All participants underwent 24 hours Holter electrocardiogram monitoring. HRT measurements, turbulence onset (TO) and turbulence slope (TS), were calculated in patients and healthy controls that have at least one ventricular premature complex (VPC) in their Holter recordings. TO is a measure of the early sinus acceleration and TS is the measure of the rate of sinus deceleration that follows the sinus acceleration after a VPC. Mann-Whitney U test was used for comparison of continuous variables and the Chi-square test for comparison of categorical variables., Results: There were no statistically significant differences in TO and TS between the RA and control groups (TO: -2.2 ± 3.1% vs -2.8 ± 2.5%, p=0.25; TS: 11.5 ± 9.7 ms/RR vs 15.5 ± 10.9 ms/RR, p=0.10)., Conclusion: HRT parameters, which determine the autonomic dysfunction, did not seem to be altered in patients with RA.

Background and Purpose: Diagnosis of paroxysmal atrial fibrillation is difficult but highly relevant in patients presenting with cerebral ischemia yet free from atrial fibrillation on admission. Early initiation and prolongation of continuous Holter monitoring may improve diagnostic yield compared with the standard of care including a 24-hour Holter recording., Methods: In the observational Find-AF trial (ISRCTN 46104198), consecutive patients presenting with symptoms of cerebral ischemia were included. Patients free from atrial fibrillation at presentation received 7-day Holter monitoring., Results: Two hundred eighty-one patients were prospectively included. Forty-four (15.7%) had atrial fibrillation documented by routine electrocardiogram on admission. All remaining patients received Holter monitors at a median of 5.5 hours after presentation. In those 224 patients who received Holter monitors but had no previously known paroxysmal atrial fibrillation, the detection rate with early and prolonged (7 days) Holter monitoring (12.5%) was significantly higher than for any 24-hour (mean of 7 intervals: 4.8%, P = 0.015) or any 48-hour monitoring interval (mean of 6 intervals: 6.4%, P = 0.023). Of those 28 patients with new atrial fibrillation on Holter monitoring, 15 (6.7%) had been discharged without therapeutic anticoagulation after routine clinical care (ie, with data from 24-hour Holter monitoring only). Detection rates were 43.8% or 6.3% for short supraventricular runs of ≥ 10 beats or prolonged episodes (> 5 hours) of atrial fibrillation, respectively. Diagnostic yield appeared to be only slightly and not significantly increased during the first 3 days after the index event., Conclusions: Prolongation of Holter monitoring in patients with symptoms of cerebral ischemic events increases the rate of detection of paroxysmal atrial fibrillation up to Day 7, leading to a relevant change in therapy in a substantial number of patients. Early initiation of monitoring does not appear to be crucial. Hence, prolonged Holter monitoring (≥ 7 days) should be considered for all patients with unexplained cerebral ischemia.

The RR intervals of sinus and ventricular beats were determined by analysis of a 24-h ambulatory electrocardiogram in a Boxer before and after treatment with sotalol. These RR intervals were plotted using tachograms, histograms, and Poincaré plots. The tachogram demonstrated a 'band' wherein a range of RR intervals was infrequent, the histogram did not take the form of a single Gaussian distribution of RR intervals, and the Poincaré plot showed nonhomogeneous beat-to-beat variability. This type of patterning was described as a "zone of avoidance" potentially caused by the clustering of beats within specific ranges. Treatment with sotalol enhanced the "zone of avoidance". Further investigation is needed to understand the mechanism for this observation as well as any clinical implications., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Objective: To investigate in trauma survivors the predictive validity of heightened physiological responsivity to script-driven imagery for the development of posttraumatic stress disorder (PTSD) and to evaluate the interactive effect of survivors' sex. Physiological responses to idiosyncratic trauma reminders may be predictive of later PTSD. The majority of previous studies have been cross sectional and have produced mixed findings. Sex differences may contribute to this heterogeneity., Methods: Heart rate (HR) and respiratory sinus arrhythmia were measured at 2 weeks post trauma in 158 assault survivors during baseline and as they listened to an idiosyncratic trauma script. At 6 months, 15.2% of male and 28.1% of female participants met the diagnostic criteria for PTSD., Results: Generalized linear model and logistic regression analyses showed that HR response to script-driven imagery and sex interacted in predicting PTSD symptom severity at 6 months. Women had greater PTSD symptom severities overall. Female HR responders to script-driven imagery showed the highest PTSD symptom severities and were almost three times more likely to develop PTSD at 6 months compared with men and female nonresponders (odds ratio, 2.72; 95% confidence interval, 1.13-6.57). Respiratory sinus arrhythmia responder type did not predict PTSD (odds ratio, 0.64; 95% confidence interval, 0.30-1.33)., Conclusion: Female trauma survivors who respond to trauma reminders with increased HR may be at particular risk of developing PTSD. Physiological reactivity to trauma cues may be a useful index for screening and prevention of PTSD.