Cardiac RR Research Articles

Assessment of heart rate variability by application of central tendency measure.

The heart rate variability (HRV) is an indicator of the subject homeostasis alterations. For a healthy individual, the HRV shows a nonlinear behavior, thus requiring a nonlinear approach to provide additional information about HRV dynamics. In this work, the nonlinear techniques, central tendency measure (CTM) and second-order difference plot, are applied to HRV analysis using the successive difference of RR intervals in a time series. In total are analyzed 170 tachograms collected by Polar monitor and then classified into three groups according to a cardiologist: healthy young adults, adults in preoperative evaluation for coronary artery bypass grafting for severe coronary disease and premature newborns. This approach identified the tachograms with high and low variability, which demonstrates the ability of CTM to classify and quantitatively characterize cardiac RR intervals.

High salt intake damages the heart through activation of cardiac (pro) renin receptors even at an early stage of hypertension.

ObjectiveIt has not yet been fully elucidated whether cardiac tissue levels of prorenin, renin and (P)RR are activated in hypertension with a high salt intake. We hypothesized that a high salt intake activates the cardiac tissue renin angiotensin system and prorenin-(pro)renin receptor system, and damages the heart at an early stage of hypertension.MethodsWistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) received regular (normal-salt diet, 0.9%) and high-salt (8.9%) chow for 6 weeks from 6 to 12 weeks of age. The systolic blood pressure, plasma renin activity (PRA) and plasma angiotensin II concentration were measured, and the protein expressions of prorenin, (pro)renin receptor, angiotensinogen, angiotensin II AT1 receptor, ERK1/2, TGF-β, p38MAPK and HSP27 in the myocardium were investigated. The cardiac function was assessed by echocardiography, and histological analysis of the myocardium was performed.ResultsThe high-salt diet significantly increased the systolic blood pressure, and significantly reduced the PRA and plasma angiotensin II concentration both in the WKYs and SHRs. Cardiac expressions of prorenin, renin, (P)RR, angiotensinogen, angiotensin II AT1 receptor, phosphorylated (p)-ERK1/2, p-p38MAPK, TGF-β and p-HSP27 were significantly increased by the high salt diet both in the WKYs and SHRs. The high-salt diet significantly increased the interventricular septum thickness and cardiomyocyte size, and accelerated cardiac interstitial and perivascular fibrosis both in the WKYs and SHRs. On the other hand, dilatation of left ventricular end-diastolic dimension and impairment of left ventricular fractional shortening was shown only in salt loaded SHRs.ConclusionThe high-salt diet markedly accelerated cardiac damage through the stimulation of cardiac (P)RR and angiotensin II AT1 receptor by increasing tissue prorenin, renin and angiotensinogen and the activation of ERK1/2, TGF-β, p38MAPK and HSP27 under higher blood pressure.

Use of SSA and MCSSA in the Analysis of Cardiac RR Time Series

A new preprocessing procedure in the analysis of cardiac RR interval time series is described. It uses the singular spectrum analysis (SSA) and the Monte Carlo SSA (MCSSA) test. A novel feature of this preprocessing procedure is the ability to identify the noise component present in the series with a given probability and to separate the time series into a trend, signal, and noise. The MCSSA test involves testing whether the modes obtained from SSA can be generated by a noise process leading to separation of the noise modes from the signal. The procedure described here does not discard or modify any sample in the record but merely separates the time series into a trend, signal, and noise, allowing for further analysis of these components. The procedure is not limited to the length of the record and could be applied to nonstationary data. The basis functions used in SSA are data adaptive in that they are not chosen a priori but instead are dependent on the data set used, increasing flexibility to the analysis. The procedure is illustrated using the RR interval time series of a healthy, congestive heart failure, and atrial fibrillation subject.

GW24-e3524 PARTIAL AORTIC CONSTRICTION IN RATS INCREASES THE EXPRESSION OF (PRO)RENIN RECEPTOR AND PLC-b3 IN THE HEART

ObjectivesRecent studies have shown that (pro)renin receptor (P)RR), a newly identified member of the renin-angiotensin system, was associated with organ damage in the kidney. However, there has been less information...

Mechanisms of causal interaction between short-term RR interval and systolic arterial pressure oscillations during orthostatic challenge

The transition from the supine to the upright position requires a reorganization of the mechanisms of cardiovascular control that, if not properly accomplished, may lead to neurally mediated syncope. We investigated how the patterns of causality between systolic arterial pressure (SAP) and cardiac RR interval were modified by prolonged head-up tilt using a novel nonlinear approach based on corrected conditional entropy (CCE) compared with the standard approach exploiting the cross-correlation function (CCF). Measures of coupling strength and delay of the causal interactions from SAP to RR and from RR to SAP were obtained in 10 patients with recurrent, neurally mediated syncope (RNMS) and 10 healthy control (CO) subjects in the resting supine position (su) and after head-up tilting during early (et; ~2 min) and late (lt; ~15 min or before presyncope) epochs of upright posture. Main results were that 1) the coupling strength from SAP to RR increased significantly from su to et in both groups; by contrast, upon lt, the coupling strength was kept high in CO subjects and dropped to low values in RNMS patients; 2) in RNMS patients, the delay from SAP to RR was higher than in healthy controls and increased moving from et to lt. Although these trends were evident using the CCE approach, statistical significance was not attained using the CCF approach. These results indicate the necessity of dissecting causality between RR and SAP to properly assess directional mechanisms from the closed-loop cardiovascular regulation and suggest a weakened and slowed baroreflex as a major mechanism involved in the cardiovascular impairment associated to neurally mediated syncope.

Influence of psychological nursing on heart rate variability of patients with acute myocardium infarction

Objective To study the effect of psychological nursing on heart rate variability (HRV)in patients with acute myocardium infarction. Methods 80 patients with AMI were randomly divided into group A(routine nursing group)and group B (psychological nursing group) with 40 patients in each group,HRV was evaluated in both groups.The time domain and frequency domain of HRV of 24 h sinus rhythm in two groups of patients were analyzed. Results In group B,24 h average standard deviation of RR interval (SDNN),5 min segments of continuous average standard deviation of RR intervals (SDANN),the difference between adjacent cardiac RR interval of the root mean square (rMSSD),the percentage of adjacent canrdiac RR interval greater than 50 ms (PNN50),low frequency (LF),high frequency (HF) and other HRV parameters were significantly higher than group A. Conclusions Psychological nursing can significantly increase HRV and improve the electric stability of the ischemic myocardium.Psychological nursing can stabilize emotion of patients,decrease sympathetic tone,and may have a role in the prevention of sudden death. Key words: Psychological nursing; Heart rate variability; Sudden cardiac death; Acute myocardium infarction

Gender specificity of the slow wave sleep lost in chronic widespread musculoskeletal pain

Objectives The majority of patients suffering from musculoskeletal chronic widespread pain (CWP) are females, and they tend to report poor sleep. We tested the hypothesis that the poor sleep of female patients reporting CWP is gender specific for changes in (1) electroencephalograph (EEG) features and (2) heart rate variability (HRV). Methods Twenty-four normal sleepers were compared to 24 patients with CWP who complained of poor sleep. Patients were referred from general practice and were matched for age (41–47 years) and gender (25 W, 23 M). Sleep variables and spectral EEG activity analyses were performed during 1 night of sleep recording. Time-domain cardiac RR interval and spectral autoregressive analyses were also performed from the same data set. Results Compared to normal females, female patients with CWP had significantly shorter sleep duration (−68 min), lower sleep efficiency (−9.9%), twice the awakenings and a trend for more periodic limb movements per hour of sleep. Daytime napping was reported by 78% of CWPs. Compared to all controls, females with CWP had significantly less power in the EEG delta band in the first and second non-REM sleep cycle. Although RR interval analysis revealed that CWP patients had a faster heart rate, neither the sympathetic nor sympathovagal analysis reached statistical significance for gender or pain status comparisons. Conclusions Female CWP patients have shorter sleep duration with many awakenings and lower sleep EEG delta activity without gender difference in HRV.

Arousal in obstructive sleep apnoea patients is associated with ECG RR and QT interval shortening and PR interval lengthening

Sudden cardiac death appears to be more prevalent during the normal sleeping hours in obstructive sleep apnoea (OSA) patients compared with the general population as well as to cardiovascular disease patients. The reasons for this remain unclear, but there are three likely main contributors to nocturnal death in OSA patients; cardiac arrhythmias, stroke/ruptured cerebral aneurism and myocardial infarction. Particularly marked cardiovascular system activation with arousal may play a role in initiating sudden adverse cardiovascular events in OSA. The purpose of this study was to investigate cardiac RR, QT and PR interval changes in the electrocardiogram (ECG) associated with spontaneous and respiratory-related arousals in OSA patients. A detailed observational study of ECG records obtained during conventional diagnostic sleep study with no further interventions was carried out in 20 patients (12 males, age 42.8 +/- 2.1 years, body mass index 35.1 +/- 1.9 kg m(-2), and respiratory disturbance index 51.8 +/- 6.4 events/hour). RR and QT intervals showed significant shortening during arousals. RR interval shortening was found to be greater during respiratory arousals when compared to spontaneous arousals. PR interval showed a trend toward a greater prolongation during respiratory arousal. QT interval shortening was weakly correlated with arterial oxygen saturation levels preceding arousal. In conclusion, these data suggest that despite greater cardiac acceleration following respiratory versus spontaneous arousals from sleep, QT shortening and PR prolongation responses are similar independent of arousal type. These data support that arousals produce quite marked and differential cardiac conduction system activation in OSA and that the degree and pattern of activation may be partly influenced by the presence and severity of preceding respiratory events.

A Classification System to Detect Congestive Heart Failure Using Second-Order Difference Plot of RR Intervals

A classification system to detect congestive heart failure (CHF) patients from normal (N) patients is described. The classification procedure uses the k-nearest neighbor algorithm and uses features from the second-order difference plot (SODP) obtained from Holter monitor cardiac RR intervals. The classification system which employs a statistical procedure to obtain the final result gave a success rate of 100% to distinguish CHF patients from normal patients. For this study the Holter monitor data of 36 normal and 36 CHF patients were used. The classification system using standard deviation of RR intervals also performed well, although it did not match the 100% success rate using the features from SODP. However, the success rate for classification using this procedure for SDRR was many fold higher compared to using a threshold. The classification system in this paper will be a valuable asset to the clinician, in the detection congestive heart failure.

Research on the correlation between the mutual information and Lempel-Ziv complexity of nonlinear time series

To explore the correlation between the mutual information and complexity of nonlinear dynamic system, the nonlinear time series of Logistic map， Lorenz model and cardiac RR intervals were used as the experimental data. The multi-segmented time-delayed mutual information， multi-segmented Lempel-Ziv complexity and their correlation coefficients were calculated. The results show that the mutual information of these series are strongly negatively correlated with the complexity. For the 201 series generated by Logistic equation, the absolute value of all correlation coefficients between the mutual information and the complexity of various segments are 0.9126 plus and the maximum reach to 0.9923， and for the 94 series of cardiac RR intervals， they are 0.8555 plus and the maximum reach to 0.9860. The investigations also indicate that the mutual information is more sensitive than the complexity in characterizing a nonlinear dynamic system.

Autoregressive analysis of cardiac RR intervals in preterm and full-term infants.

For the purpose of obtaining information on the maturation process of the autonomic nervous system in pre- and full-term infants, polygraphs were recorded during sleep from a total of 52 appropriate-for-dates infants at a conceptional age of 28-41 weeks. The 104 RR interval time series was calculated by autoregressive (AR) and component analysis. Histograms of damping frequencies obtained were divided into two frequency bands: low frequency fluctuations (LF) of less the 0.1 cycle/beat (c/b) and high frequency fluctuations (HF) of more than 0.15 c/b. Total power and LF power decreased with increases in the conceptional age or postnatal age at a significance level of 0.01, respectively. In addition, the HF amount of bio-informing activity increased (P < 0.001) and the damping time of HF also increased (P < 0.01). From these results, it was speculated that the activity of the sympathetic system decreases with increases in conceptional or postnatal age. It was also speculated that increased regularity and oscillatory duration in HF might be caused by the development of the reciprocal response of respiration to heart rate variation.

Physical factors and cardiac adaptation.

ARTICLESPhysical factors and cardiac adaptationJP Gilmore, HE Cingolani, RR Taylor, and McDonald RH JrJP Gilmore, HE Cingolani, RR Taylor, and McDonald RH JrPublished Online:01 Nov 1966https://doi.org/10.1152/ajplegacy.1966.211.5.1219MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByMonitoring the Variation in Myocardial Function With the Doppler-Derived Myocardial Performance Index During Aortic Cross-ClampingJournal of Cardiothoracic and Vascular Anesthesia, Vol. 26, No. 2Homeometric Autoregulation30 May 2008Mechanisms Underlying the Increase in Force and Ca 2+ Transient That Follow Stretch of Cardiac MuscleCirculation Research, Vol. 85, No. 8Cardiac Output During Exercise: Contributions of the Cardiac, Circulatory, and Respiratory Systems1 January 2011The responses of left ventricular end-systolic pressure-diameter relationship to acute pressure overload induced by aortic constrictionActa Physiologica Scandinavica, Vol. 149, No. 3Alpha-adrenergic regulation of splanchnic volume and cardiac output in the dogActa Physiologica Scandinavica, Vol. 138, No. 3Regulation of Myocardial ContractilityTime-dependent shifts of the left ventricular diastolic filling relationship in conscious dogs.Circulation Research, Vol. 45, No. 5Pressure-volume relations, elastic modulus, and contractile behaviour of the hypertrophied left ventricle of rats with Goldblatt II hypertensionPflügers Archiv European Journal of Physiology, Vol. 369, No. 3Coronary Circulatory Effects of Increased Intrathoracic Pressure in Intact DogsChest, Vol. 72, No. 1The effect of isolation on myocardial propertiesBasic Research in Cardiology, Vol. 71, No. 1Left ventricular function during isometric exercise (handgrip): significance of an atrial gallop (S4)American Heart Journal, Vol. 88, No. 6Regional Coronary Venous Oxygen Saturation and Myocardial Oxygen Tension following Abrupt Changes in Ventricular Pressure in the Isolated Dog HeartCirculation Research, Vol. 34, No. 5The Estimation of Contractile Element Velocity During the Isovolumic Period: Alterations by Cardiac Output and Contractile State27 September 2008 | Archives Internationales de Physiologie et de Biochimie, Vol. 82, No. 5Effect of Increased Afterload on the Inotropic State and Uptake of Free Fatty Acids in the Intact Dog HeartActa Physiologica Scandinavica, Vol. 84, No. 3Diastolic Geometry and Sarcomere Lengths in the Chronically Dilated Canine Left VentricleCirculation Research, Vol. 28, No. 1Steigerungsfähigkeit von Kontraktionsgeschwindigkeit und Schlagvolumen durch inotrope Mechanismen beim intakten Herzen in situArchiv für Kreislaufforschung, Vol. 57, No. 3-4Left Ventricular Pressure-Volume Relations and Performance as Affected by Sudden Increases in Developed PressureCirculation Research, Vol. 22, No. 3A Quantitative Analysis of Left Ventricular Myocardial Function in the Intact, Sedated DogCirculation Research, Vol. 21, No. 1 More from this issue > Volume 211Issue 5November 1966Pages 1219-1226 Copyright & PermissionsCopyright © 1966 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1966.211.5.1219PubMed5924045History Published online 1 November 1966 Published in print 1 November 1966 Metrics