This paper aims to find a new method of detecting atrial fibrillation (AF) with fast responding speed and high detecting precision by R-R intervals. Probability density function (PDF) of distance between two points in the reconstructed phase space of R-R intervals of normal sinus rhythm (NSR) and AF is studied. It is found that the distribution of PDF between NSR and AF R-R intervals is significantly different; and based on this finding, a characteristic parameter k is defined. k is used for defection among 400 NSR and 400 AF R-R intervals. The results demonstrate that the new algorithm has fast responding speed and high detecting precision (average sensitivity 97.0%, average specificity 95.2%).
Algorithms ; Atrial Fibrillation ; diagnosis ; physiopathology ; Diagnosis, Differential ; Electrocardiography ; Humans ; Signal Processing, Computer-Assisted ; Sinoatrial Node ; physiopathology

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

Instantaneous chaometry was defined on uniformity theory constructed by the present authors. The sample data, sinus heart rate data and arrhythmia heart rate data from MIT-BIH were analyzed with instantaneous chaometry (ICM); the situation not being distinguished with HRV can be differentiated with ICM. The normal sinus rhythm was found to be of three evident characteristics: (1) instant returning to zero, (2) stability-stable characteristic of ICM on the initial position, (3) interval of mean: 2-7, variance: 1.5-5. The third characteristic shows that the variability of ICM is necessary. The studies on arrhythmia database showed that arrhythmia cases exhibited no returning to zero, nonstability of ICM on the initial position, too small mean or standard deviation, respectively. Evidently, the arithmetic of ICM is simple; ICM can be easily applied in clinical and pathologic analyses.
Arrhythmias, Cardiac ; physiopathology ; Electrocardiography ; methods ; Heart Rate ; physiology ; Humans ; Male ; Middle Aged ; Signal Processing, Computer-Assisted ; Sinoatrial Node ; physiology

To evaluate the possibility and accuracy of Doppler tissue image (DTI) on assessment of normal and abnormal ventricular activation and contraction sequence, 9 open chest canine hearts were analyzed by acceleration mode, M-mode, and spectrum mode DTI. Our results showed that: (1) Acceleration mode DTI could show the origin of activation and conduction sequence on line; (2) M-mode DTI revealed that the activation in mid-interventricular septum was earlier than that in mid-left ventricular posterior wall at sinus activation; (3) Spectrum DTI showed the ventricular endocardium was activated earlier than the ventricular epicardium in all segments at sinus rhythm. The earliest site of activation of the normal ventricular wall was at middle interventricular septum; the latest site was at basal-posterior wall; the contraction sequence was different at the different walls; (4) During abnormal ventricular activation, mid-left ventricular posterior wall was activated earliest in accordance with the pacing sites. Abnormal ventricular activation was slower than sinus activation, and the contraction sequence varied at different sites of ventricular wall. It is concluded that DTI can be used to localize the origin of normal or abnormal myocardial activation and to assess the contraction sequence conveniently, accurately and non-invasively.
Animals ; Dogs ; Echocardiography, Doppler ; instrumentation ; methods ; Heart Ventricles ; diagnostic imaging ; Myocardial Contraction ; physiology ; Sinoatrial Node ; physiology ; Tachycardia ; diagnostic imaging ; physiopathology

To evaluate the possibility and accuracy of Doppler tissue image (DTI) on assessment of normal and abnormal ventricular activation and contraction sequence, 9 open chest canine hearts were analyzed by acceleration mode, M-mode, and spectrum mode DTI. Our results showed that: (1) Acceleration mode DTI could show the origin of activation and conduction sequence on line; (2) M-mode DTI revealed that the activation in mid-interventricular septum was earlier than that in mid-left ventricular posterior wall at sinus activation; (3) Spectrum DTI showed the ventricular endocardium was activated earlier than the ventricular epicardium in all segments at sinus rhythm. The earliest site of activation of the normal ventricular wall was at middle interventricular septum; the latest site was at basal-posterior wall; the contraction sequence was different at the different walls; (4) During abnormal ventricular activation, mid-left ventricular posterior wall was activated earliest in accordance with the pacing sites. Abnormal ventricular activation was slower than sinus activation, and the contraction sequence varied at different sites of ventricular wall. It is concluded that DTI can be used to localize the origin of normal or abnormal myocardial activation and to assess the contraction sequence conveniently, accurately and non-invasively.
Echocardiography, Doppler/instrumentation ; Echocardiography, Doppler/*methods ; Heart Ventricles/*ultrasonography ; Myocardial Contraction/*physiology ; Sinoatrial Node/physiology ; Tachycardia/physiopathology ; Tachycardia/ultrasonography

OBJECTIVETo study the effect of Kangxin Fulu Recipe (KFR) on electrophysiological functions of the sinoatrial node in rabbits with sick sinus syndrome (SSS).

METHODSSixty big ears white rabbits were randomly divided into six groups, i.e., the normal group, the model group, the atropine group, the high dose KFR group, the middle dose KFR group, and the low dose KFR group, ten in each group. SSS model was established by injecting formaldehyde to the sinoatrial node except those in the normal group. Changes in AA interval, the sinoatrial conduction time (SACT), the sinus node recovery time (SNRT), and the corrected sinus node recovery time (CSNRT) were measured before and after modeling, seven days before and after gastrogavage.

RESULTS(1) The AA interval and SACT could be significantly shortened in the high dose KFR group, the middle-dose KFR group, and the atropine group (P<0.05, P<0.01). Better effects were obtained in the former two groups (P<0.05). (2) SNRT and CSNRT could be shortened in the high dose KFR group and the atropine group, with no statistical difference between the two groups (P>0.05).

CONCLUSIONThe electrophysiological mechanism of KFR might possibly be correlated with accelerating the recovery of sinus node autorhythmicity and conduction functions.

Animals ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Heart Rate ; drug effects ; Rabbits ; Sick Sinus Syndrome ; physiopathology ; Sinoatrial Node ; drug effects ; physiopathology

OBJECTIVE: L-type voltage-gated calcium channel subunit alpha1D-/- mice (homozygous mutant, knockout), alpha1D+/- (heterozygous) and alpha1D+/+ (wild-type) have played role in L-type voltage-gated calcium channel alpha1D subunit in auditory function of inner ear as well as sinoatrial node function of the mice. METHOD: Hearing threshold and endocochlear potential (EP) were measured in the alpha1D knockout mice, heterozygous mice and wild-type mice by auditory brainstem response(ABR), EP recordings and Electrocardiograph (ECG) respectively. To assessment of the vestibular function of the mice, the ability of Balancing was performed by a swim test and a horizontal cylinder test. RESULT: The auditory function of alD+/+ mice were normal, the mean value for ABR thresholds in response to click sound stimulus was (34.8 +/- 5.7) dB SPL,EP was (105.3 +/- 3.1) mV. The mean value for ABR thresholds in response to click sound stimulus was elevated in alpha1D+/- mice was (54.4 +/- 12.4) dB SPL, relative to that observed in alpha1D+/+ mice significantly increased (P < 0.05); EP of alpha1D+/- mice was about (75.8 +/- 9.9) mV. alpha1D-/- mice were completely deaf, the ABR wave form was not observed for even 100 dB SPL sound stimuli used and EP was still remain in (48.6 +/- 19.3) mV. alpha1D knockout mice were deaf and demonstrated no vestibular defect. alpha1D+/- and alpha1D-/- mice show significant sinus bradycardia with significant prolongation of the RR interval (146 +/- 1.4 and 244 +/- 2.9, respectively) comparing to the alpha1D+/+ wild-type mice (117 +/- 0.4) in the same littermates. In addition, the homozygous alpha1D-/- show a significant prolongation of the PR interval (53 +/- 0.5) compared to that of the a1D+/+ wild-type mice (38 +/- 0.3). CONCLUSION L-type voltage-gated calcium channel alpha1D subunit plays a critical role in calcium homeostasis in the inner ear. Mice lacking of alpha1D calcium channel gene would lead to influence auditory function and sinoatrial node dysfunction subsequently.
Animals ; Auditory Threshold ; Calcium Channels, L-Type ; genetics ; Deafness ; genetics ; physiopathology ; Electrocardiography ; Evoked Potentials, Auditory, Brain Stem ; Mice ; Mice, Knockout ; Sinoatrial Node ; physiopathology

Heart rate variability (HRV) is the difference between the successive changes in the heartbeat cycle, and it is produced in the autonomic nervous system modulation of the sinus node of the heart. The HRV is a valuable indicator in predicting the sudden cardiac death and arrhythmic events. Traditional analysis of HRV is based on a multielectrocardiogram (ECG), but the ECG signal acquisition is complex, so we have designed an HRV analysis system based on photoplethysmography (PPG). PPG signal is collected by a microcontroller from human's finger, and it is sent to the terminal via USB-Serial module. The terminal software not only collects the data and plot waveforms, but also stores the data for future HRV analysis. The system is small in size, low in power consumption, and easy for operation. It is suitable for daily care no matter whether it is used at home or in a hospital.
Autonomic Nervous System ; physiopathology ; Cardiovascular Diseases ; diagnosis ; Death, Sudden, Cardiac ; Electrocardiography ; Heart Rate ; Humans ; Monitoring, Ambulatory ; instrumentation ; Photoplethysmography ; instrumentation ; Sinoatrial Node ; physiopathology ; Software

The early cardiac biological pacemaker studies were mostly around HCN channel, and how to build a biological pacemaker through the enhanced If current. In recent years, however, people found that the genes of Tbx3 could play an important role in the development of cardiac conduction system, especially in processes of the maturity of the sinoatrial node and maintenance of its function. And the Tbx3 can further optimize the biological pacemaker. Therefore, it could be a new therapeutic focus in biological pacemaker and treatment of cardiac conduction system disease. This paper summarizes some of the latest research progress of the Tbx3 in biological pacemaker in recent years. We hope that this review could provide theoretical basis for the clinical applications of Tbx3.
Arrhythmias, Cardiac ; genetics ; Biological Clocks ; Brugada Syndrome ; Cardiac Conduction System Disease ; Heart ; physiopathology ; Heart Conduction System ; abnormalities ; Humans ; Sinoatrial Node ; T-Box Domain Proteins ; genetics

OBJECTIVE: To investigate the expression of hyperpolarization-activated cyclic nucleotide-gated cation channel 4 (HCN4) and connexin43 (Cx43) in the sinoatrial node of electric shock death. METHODS: As experimental group, 34 cases of electric shock death who had definite current mark evidence were selected from pathology department of Xuzhou Medical College from 2010 to 2013. As the control group, 20 cases of fatal severe craniocerebral injury in traffic accidents were chosen. The expressions of HCN4 and Cx43 in the sinoatrial node were observed by immunohistochemical technology. RESULTS: HCN4 positive cells expressed in the cell membrane and cytoplasm of the sinoatrial node. Cx43 positive cells expressed in the cell membrane and cytoplasm of T cells and myocardial cells. The expression of HCN4 was significantly higher than that of the control group (P < 0.05) and the expression of Cx43 was significantly lower than that of the control group (P < 0.05). CONCLUSION The changes of HCN4 and Cx43 expressions in the sinoatrial node illustrate electric shock death might be related to the abnormalities of cardiac electrophysiology and conduction.
Connexin 43/metabolism* ; Cyclic Nucleotide-Gated Cation Channels ; Heart Rate ; Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/metabolism* ; Immunohistochemistry/methods* ; Myocardium/metabolism* ; Myocytes, Cardiac ; Sinoatrial Node/physiopathology*