BACKGROUND: Atrial fibrillation is one of the most common cardiac arrhythmias which has been recieved relatively little attention until recently.Despite the variety of treatment modalities including drugs,surgery,catheter ablation and devices,the overall treatment of atrial fibrillation is not always satisfactory.Phalmacotherapy is still the most commonly used treatment through the unfavorable side effects of antiarrhythmic drugs are problematic.The purpose of this study is to compare the efficacy of class Ic antiarrhythmic drugs,propafenone versus flecainide. METHODS: We treated one hundred eighteen patients with atrial fibrillation by class Ic antiarrhythmic drugs,propafenone or flecainide with/without DC cardioversion to convert to and maintain the sinus rythm. We compared the clinical findings,drug efficacy,side sffects of drugs between two groups. RESULTS: 30 patients were treated by propafenne and 88 patients by flecainide.21 and 60 patients in each group were lone atrial fibrillation,14 and 49 patients were paroxysmal atrial fibrillation.Mean duration of drug administration were 360.9,339.4 days,respectively.The convesion rate to sinus rhythm by drugs was 25.0% in propafenone group and 30.7% in flecainide group(p=NS).The 300 days-manitenance rates of sinus rhythm after conversion by drugs or DC cardioversion were 63,3%,70.4%(p=NS)respectively. The side effects of drugs were dizziness,nausia and vomitting in both group and 1st degree AV block,transient sinus node dysfunction and decreased visual acuity in flecainde group.The drugs were discontinued in 11(37.7%) and 26(29.5%) patients in each group due to recurrence of atrial fibrillation or side effects of drugs. CONCLUSION: This study suggests that propafenone and flecainide are comparably effective in maintaining sinus rhythm in atrial fibrillation patients.Futher prospective and large study is required to confirm this findings.
Anti-Arrhythmia Agents ; Arrhythmias, Cardiac ; Atrial Fibrillation* ; Electric Countershock ; Flecainide* ; Humans ; Propafenone* ; Recurrence ; Sick Sinus Syndrome ; Visual Acuity

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

Sinus tachycardia is an accelerated rhythm in which the rate of impulses arising from the sinoatrial node is elevated. Uncontrolled sinus tachycardia may result in a poor prognosis, particularly in patients with cardiovascular disease, because of a hemodynamic disturbance arising from the tachycardia itself. When sinus tachycardia is specifically triggered by anemia, shock, or fever, it is referred to as physiological sinus tachycardia. Physiological sinus tachycardia should resolve with correction of the underlying cause. Inappropriate sinus tachycardia (IST) is unexplained by physiological demand. Palpitation is the most frequent symptom in IST patients. Even though treatment of IST has insufficient efficacy and a relatively high recurrence rate, several treatment strategies such as use of a β-blocker, ivabradine, and radiofrequency catheter ablation can be used for IST patients.
Anemia ; Arrhythmia, Sinus ; Cardiovascular Diseases ; Catheter Ablation ; Fever ; Hemodynamics ; Humans ; Prognosis ; Recurrence ; Shock ; Sinoatrial Node ; Tachycardia* ; Tachycardia, Sinus

BACKGROUND: Although heart rate variability (HRV) and blood pressure variability (BPV) arise from many different influences, probably the most consistent external modulator is respiration. At rest, the heart rate increases on inspiration and decreases on expiration, a phenomenon called respiratory sinus arrhythmia (RSA). Spectral analysis of heart rate offers good and reproducible estimate of RSA and BPV. Many studies have been conducted on the effects of respiration on HRV and BPV during awake subject breathing spontaneously. However, little is known as to whether respiratory rate modulates HRV and BPV during general anesthesia with mechanical ventilation. Here, we studied effects of respiratory rate on HRV and BPV during general anesthesia. METHODS: We studied 40 patients undergoing general anesthesia with mechanical ventilation. Maintaining anesthesia with isoflurane, we recorded R-R interval and systolic blood pressure at respiratory rate of 15, 10 and 6 breaths/minute. Data was analyzed by the power spectral analyses of HRV and BPV, which were divided into low frequency (LF) and high frequency (HF) band. RESULTS: Respiratory rate did not affect RR interval, systolic blood pressure, and total spectral power HRV and BPV. Compared with its value at 15 breaths/minute, HF-HRV was significantly increased at 6 breaths/minute. HF-and LF-BPV at 6 breaths/minute were significantly increased versus 15 breaths/minute. CONCLUSIONS: Respiratory rate modulates HRV and BPV during general anesthesia with mechanical ventilation. We suggest that respiratory rate should be considered and controlled in studies of cardiovascular variability during general anesthesia.
Anesthesia ; Anesthesia, General* ; Arrhythmia, Sinus ; Blood Pressure ; Heart Rate ; Humans ; Isoflurane ; Respiration ; Respiration, Artificial* ; Respiratory Rate*

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

Sick sinus syndrome (SSS) is an abnormality of sinus nodal impulse formation by intrinsic or extrinsic causes. Patients with SSS often are asymptomatic, or have mild or nonspecific symptoms, including dizziness, palpitations, fatigue, and confusion related to the decreased cardiac output. SSS can rarely cause conditions like syncope, congestive heart failure, thromboembolism, pulmonary edema, cardiac arrest, or sudden death. We report here on a severe bradycardia during general anesthesia for aneurysmal clipping and tachycardia-bradycardia syndrome followed by cardiac arrest postoperatively in the ICU, which was subsequently diagnosed as SSS with 24-hour Holter monitoring.
Anesthesia, General ; Aneurysm ; Bradycardia ; Cardiac Output ; Death, Sudden ; Dizziness ; Edema, Cardiac ; Electrocardiography, Ambulatory ; Fatigue ; Heart Arrest ; Heart Failure ; Humans ; Pulmonary Embolism ; Sick Sinus Syndrome ; Syncope

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

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

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

BACKGROUNDLong-term maintenance of sinus rhythm after successful conversion of chronic atrial fibrillation (CAF), often ameliorates patients' symptoms, reduces the risk of ischemic stroke and improves cardiovascular hemodynamics. This prospective study aims to evaluate the long-term efficacy and safety of very low-dose amiodarone (100 mg daily) for the maintenance of sinus rhythm after successful direct-current (DC) cardioversion in patients with CAF and rheumatic heart disease (RHD) post intervention.

METHODSThis study was a randomized prospective trial. One day after successful DC cardioversion (remained normal sinus rhythm) in patients with CAF and RHD post intervention for more than six months and adequate anticoagulation, all were randomly administered either amiodarone 200 mg daily in group A or amiodarone 100 mg daily in group B.

RESULTSA total of 76 patients (40 men and 36 women) were examined from February 1998 to December 1999. The mean age of the patients was (66 +/- 10) years, and the mean follow-up was (67 +/- 8) months (range 61 to 84 months). Actuarial rates of the maintenance of sinus rhythm were similar in the two groups after 5 years of follow-up. Four patients (11%) in group A but none in group B experienced significant adverse effects that necessitated withdrawal of amiodarone. No death occurred during the study period.

CONCLUSIONA very low dose of amiodarone results in adequate long-term efficacy and is safe for maintaining sinus rhythm in patients with CAF and RHD post intervention after successful DC cardioversion.

Aged ; Amiodarone ; administration & dosage ; adverse effects ; Anti-Arrhythmia Agents ; administration & dosage ; Arrhythmia, Sinus ; drug therapy ; Atrial Fibrillation ; drug therapy ; physiopathology ; Chronic Disease ; Cohort Studies ; Electric Countershock ; methods ; Female ; Humans ; Male ; Middle Aged ; Prospective Studies