OBJECTIVES: Dyspnea and palpitation are common features of pregnancy. While several theories have been put forward to explain the etiology of gestational dyspnea and palpitation, there have been few systemic studies of its incidence, severity and time-course in a group of normal women. METHODS: We interviewed postpartum women, within 3 days after delivery, about dyspnea and palpitation. Separately from this interview, we performed 24-hour ECG monitoring for obstetric patients with palpitation before delivery. RESULTS: The subjects interviewed were 261 women, of whom 37.5 percent and 11.5 percent experienced dyspnea and palpitation, respectively. These symptoms had a tendency to increase to term. The presence of arrhythmias could be documented in only 22% of patients having 24-hour Holter monitoring. CONCLUSION: Dyspnea and palpitation were common among normal pregnant women and had a tendency to increase to term.
Adult ; Arrhythmia/*physiopathology ; Dyspnea/*physiopathology ; Electrocardiography, Ambulatory ; Female ; Human ; Pregnancy ; Pregnancy Complications/*physiopathology ; Time Factors

To investigate the effects of gradually guided breathing on respiratory sinus arrhythmia (RSA), 15 healthy men's simultaneous ECG and respiratory signals during the guided breathing process (14 beats/min-12.5 beats/ min--1 beats/min--9.5 beats/min--8 beats/minute--7 beats/min) were acquired. Based on the frequency domain and time domain methods, the effects of respiratory rate on RSA were studied. A general tendency increase features the three parameters of RSA as respiratory rate decreased. RSA represents the reflection control of respiratory system to cardiovascular system. The results suggested that the function of the reflection control of respiratory system to cardiovascular system increaseed with guided breathing decreasing. The conclusion indicates that the cardiovascular system could be improved by regulating the mode of respiration.
Adult ; Arrhythmia, Sinus ; physiopathology ; Electrocardiography ; Humans ; Male ; Music ; Respiration ; Respiratory Rate ; physiology

Recent evidence indicates that the voltage clock (cyclic activation and deactivation of membrane ion channels) and Ca2+ clocks (rhythmic spontaneous sarcoplasmic reticulum Ca2+ release) jointly regulate sinoatrial node (SAN) automaticity. However, the relative importance of the voltage clock and Ca2+ clock for pacemaking was not revealed in sick sinus syndrome. Previously, we mapped the intracellular calcium (Cai) and membrane potentials of the normal intact SAN simultaneously using optical mapping in Langendorff-perfused canine right atrium. We demonstrated that the sinus rate increased and the leading pacemaker shifted to the superior SAN with robust late diastolic Cai elevation (LDCAE) during beta-adrenergic stimulation. We also showed that the LDCAE was caused by spontaneous diastolic sarcoplasmic reticulum (SR) Ca2+ release and was closely related to heart rate changes. In contrast, in pacing induced canine atrial fibrillation and SAN dysfunction models, Ca2+ clock of SAN was unresponsiveness to beta-adrenergic stimulation and caffeine. Ryanodine receptor 2 (RyR2) in SAN was down-regulated. Using the prolonged low dose isoproterenol together with funny current block, we produced a tachybradycardia model. In this model, chronically elevated sympathetic tone results in abnormal pacemaking hierarchy in the right atrium, including suppression of the superior SAN and enhanced pacemaking from ectopic sites. Finally, if the LDCAE was too small to trigger an action potential, then it induced only delayed afterdepolarization (DAD)-like diastolic depolarization (DD). The failure of DAD-like DD to consistently trigger a sinus beat is a novel mechanism of atrial arrhythmogenesis. We conclude that dysfunction of both the Ca2+ clock and the voltage clock are important in sick sinus syndrome.
Animals ; Arrhythmia, Sinus/physiopathology ; Atrial Fibrillation/physiopathology ; Bradycardia/physiopathology ; Calcium/*physiology ; Calcium Channels/*physiology ; Dogs ; Humans ; Sick Sinus Syndrome/physiopathology ; Sinoatrial Node/physiology/*physiopathology

As is known in literature, the Base-scale Entropy Measure is useful for analyzing short-term heart rate variability signals. In this study, the method is applied to detect cardiac arrhythmias, including sinus and atrial arrhythmia. We detect and analyze normal sinus rhythm (NSR), atrial premature contraction (APC) and sinus bradycardia (SBR) signals. The selected data of NSR are obtained from the MIT-BIH normal sinus database, while others are from the MIT-BIH arrhythmia database. The results show the Base-scale Entropy can also detect sinus and atrial arrhythmia.
Algorithms ; Arrhythmia, Sinus ; diagnosis ; physiopathology ; Atrial Premature Complexes ; diagnosis ; physiopathology ; Electrocardiography ; Entropy ; Humans ; Signal Processing, Computer-Assisted

Arrhythmia, Sinus ; physiopathology ; therapy ; Atrial Fibrillation ; physiopathology ; therapy ; Electric Countershock ; methods ; Humans ; Male ; Middle Aged ; Treatment Outcome

Time irreversibility is a fundamental property of nonequilibrium systems. It is significant to measure the trend of change of time irreversible index under different physiological and pathological state of electrocardiosignal. We analyzed and tested the heart rate variability (HRV) signals of the normal sinus rhythm, atrial contraction, sinus bradycardia in the MIT-BIH standard database using the multiscale time irreversiblity method. It was shown that the time irreversiblity index of the normal heart rhythm, atrial premature beats and bradycardia were in the decreasing trend. The results would be helpful to clinical diagnosis as a secondary means.
Arrhythmia, Sinus ; physiopathology ; Atrial Premature Complexes ; physiopathology ; Bradycardia ; physiopathology ; Electrocardiography ; methods ; Heart Rate ; physiology ; Humans ; Signal Processing, Computer-Assisted ; Time Factors

This study sought to disclose whether Hurst index can be used as a criterion for distinguishing sinus and atrial arrhythmia signals. Normal sinus rhythm beats, atrial premature contraction (APC) beats, and sinus bradycardia (SBR) signals, were taken from the MIT-BIH standard database. Hurst index method was used to distinguish the two kinds of arrhythmia. The results showed that the Hurst exponents of three kinds of signals were larger than 0.5, but they were in different value region. The data indicated that the long-term relevant character was the best for normal signal, better for sinus bradycardia, and the worst for atrial premature beats. So Hurst index is a useful identification criterion for distinguishing sinus and atrial arrhythmia signals.
Algorithms ; Arrhythmia, Sinus ; diagnosis ; physiopathology ; Atrial Premature Complexes ; diagnosis ; physiopathology ; Bradycardia ; diagnosis ; physiopathology ; Diagnosis, Differential ; Electrocardiography ; Humans ; Signal Processing, Computer-Assisted

Respiratory sinus arrhythmia (RSA) is known as fluctuations of heart rate associated with breathing. It has been increasingly used as a noninvasive index of cardiac vagal tone in psychophysiological research recently. Its analysis is often influenced or distorted by respiratory parameters, posture and action, etc. This paper reviews five methods of quantification, including the root mean square of successive differences (RMSSD), peak valley RSA (pvRSA), cosinor fitting, spectral analysis, and joint timing-frequency analysis (JTFA). Paced breathing, analysis of covariance, residua method and msRSA per liter tidal volume are adjustment strategies of measurement and analysis of RSA in this article as well. At last, some prospects of solutions of the problems of RSA research are given.
Algorithms ; Arrhythmia, Sinus ; physiopathology ; Artifacts ; Calibration ; Electrocardiography ; methods ; Humans ; Respiration ; Signal Processing, Computer-Assisted ; Tidal Volume ; physiology ; Vagus Nerve ; physiology

BACKGROUNDIbutilide has been commonly used for pharmacologic cardioversion of atrial fibrillation and flutter in clinical settings. The objective of this study was to investigate the effects of ibutilide on the defibrillation threshold (DFT), restitution properties, dispersion of refractoriness and activation patterns during ventricular fibrillation (VF).

METHODSIbutilide was administrated intravenously in six open-chest beagles. Before and after the drug administration, 20-second episodes of VF were electrically induced and recorded with a 10×10 unipolar electrode plaque sutured on the lateral epicardium of the left ventricle. DFT and VF activation patterns, including type of epicardial activation maps, VF cycle length (VF-CL), conduction velocity, wavelength (WL) and reentry incidence, were measured. Restitution properties and dispersion of refractoriness were estimated from activation recovery intervals (ARI) during pacing.

RESULTSCompared to baseline, ibutilide markedly decreased the DFT by 31% ((491 ± 14) V vs. (337 ± 59) V, P < 0.01). The drug significantly reduced the maximal slope of the restitution curve (1.34 ± 0.08 vs. 0.76 ± 0.06, P < 0.01) and its epicardial dispersion (0.36 ± 0.09 vs. 0.21 ± 0.06, coefficient of variation, P = 0.03). The dispersion of refractoriness was enhanced at the pacing cycle length of 300 ms to 160 ms by ibutilide. The drug significantly increased the VF-CL ((96 ± 19) ms vs. (112 ± 20) ms, P < 0.01) and the WL ((41 ± 9) mm vs. (52 ± 14) mm, P = 0.02) during VF, and reduced the reentry incidence by 25% (0.08 ± 0.02 vs. 0.06 ± 0.02, P < 0.01). In the epicardial activation maps, ibutilide significantly reduced the percentage of more complex activation maps during VF.

CONCLUSIONSIntravenous ibutilide significantly decreased the DFT. It might be due to reduction of activation pattern complexity during VF.

Animals ; Anti-Arrhythmia Agents ; therapeutic use ; Dogs ; Pericardium ; drug effects ; Sulfonamides ; therapeutic use ; Ventricular Fibrillation ; drug therapy ; physiopathology

This study is to quantify time-varying dominant frequencies in electrocardiogram (ECG) during the ventricular fibrillation (VF). Orthogonal ECG (sagittal, x; transverse, y; and longitudinal, z) and the transvenous two-leads defibrillation systems were set in 19 dogs. Time-frequency analysis was used to assess changes in the dominant frequency within ECG recorded in dogs during trials of 10-30 s of VF. In 4 additional dogs, the dominant frequencies were compared during 10 s of VF before and after administration of amiodarone. Results showed that in the 427 trials of 10 s VF and 335 trials of 30 s VF, average variation in the dominant frequency was considerable, between +/- 12%-18%. The frequencies orthogonal ECG during 10 s VF were distributed symmetrically above and below the mean frequency like a normal distribution. In the 79 trials with administration of amiodarone during 10 s VF in all three ECG, the mean frequencies decreased from 6.5 (x), 7.4 (y) and 7.0 Hz (z) to 6.1, 6.4 and 6.3 Hz (P < 0.01), respectively, and the variation in dominant frequencies decreased from 1.18, 1.38 and 1.19 to 0.98, 1.11 and 1.02 Hz (P < 0.05) respectively. The results confirmed that the frequencies of 10-30 s VF in ECG vary considerably and continuously, and amiodarone decreases this variation.
Amiodarone ; pharmacology ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Dogs ; Electric Countershock ; Electrocardiography ; drug effects ; Female ; Male ; Ventricular Fibrillation ; physiopathology