OBJECTIVEEctopic atrial tachycardia (EAT) is a common type of supraventricular tachycardia in pediatric population, and it can be resistant to antiarrhythmic drugs and lead to tachycardia induced cardiomyopathy (TIC) if not properly managed. This study assessed the clinical course and response to treatment of EAT in children.

METHODA retrospective review included 144 children at the First Hospital of Tsinghua University diagnosed with EAT from January 2009 to April 2014. The clinical detailed history, 12 lead ECG, 24-h Holter recording, echocardiography, response to therapy and follow-up were analyzed.

RESULTThe onset of EAT occurred at any age with a distribution with positive skewness, 57 children ≤1 years, 22 children > 1 - 3 years, 25 children > 3 - 6 years and 40 children ≥ 6 years of age. The percentages of the three tachycardia types were 36. 1% (n = 52) for incessant EAT, 52. 8% (n = 76) for paroxysmal EAT and 11. 1% (n = 16) for sporadic EAT, respectively. There were 115 patients received drug therapy in our hospital and in 72 cases the EAT was completely controlled. Antiarrhythmic therapy had been discontinued in 35 children with complete control. Normal sinus rhythm was observed by telemetry or Holter within 4 to 90 days and the mean duration of medical therapy was 310 days (range 15 to 608 days) in these children. The combination of sotalol and propafenone showed better effectiveness for control of children with EAT (54%, 41/76), compared with single sotalol (36%, 24/66) and the combination of amiodarone and metoprolol (30%, 7/23) (χ2 = 6. 296, P = 0. 043). Tachycardia type was able to predict the response to antiarrhythmic drugs for children with EAT, sporadic tachycardia had best control rate on pharmacological therapy compared with paroxysmal tachycardia and incessant tachycardia (94% (15/16) vs. 67% (42/63) vs. 42% (15/36), χ2 = 17. 925, P = 0. 000) . Acute success of radiofrequency ablation (RFA) in children who showed poor response to antiarrhythmic drugs was achieved in 45 of 49 (92%), ultimate success was achieved in 33 of 49 (67%). The incidence of TIC secondary to EAT was 18. 1% (n =26), and left ventricular ejection-fraction (LVEF) returned to normal in 23 children after successful control of EAT ((61 ± 4) % vs. (43 ± 5) %, t = - 10. 036, P = 0. 000). Side effects including abnormal thyroid function (in 3) and abnormal liver function (in 1) occurred in 4 (17%) of 23 children who received amiodarone and disappeared when amiodarone was discontinued.

CONCLUSIONEAT in children predominantly occurred in young infants and children. Incessant EAT comprised a great percentage. The combination of sotalol and propafenone provided the best results for control of children with EAT. RFA should be considered as a preferred treatment for older children who displayed poor response to medical therapy.

Amiodarone ; Anti-Arrhythmia Agents ; Cardiomyopathies ; Catheter Ablation ; Child ; Child, Preschool ; Echocardiography ; Electrocardiography ; Humans ; Infant ; Retrospective Studies ; Sotalol ; Tachycardia, Ectopic Atrial ; drug therapy ; physiopathology ; Tachycardia, Supraventricular ; drug therapy ; Ventricular Function, Left

To study the antiarrhythmic effect of the newly developed alpha/beta-blocker TJ0711, a variety of animal models of arrhythmia were induced by CaCl2, ouabain and ischemia/reperfusion. Glass microelectrode technique was used to observe action potentials of right ventricular papillary muscle of guinea pig. The onset time of arrhythmia induced by CaCl2 was significantly prolonged by TJ0711 at 0.75, 1.5 and 3 mg x kg(-1) doses. TJ0711 (1.5 and 3 mg x kg(-1)) can significantly shorten the ventricular tachycardia (VT) and ventricular fibrillation (VF) duration, the incidence of VF and mortality were significantly reduced. On ischemia-reperfusion-induced arrhythmic model, TJ0711 (0.25, 0.5, 1 and 2 mg x kg(-1)) can significantly reduce the ventricular premature contraction (PVC), VT, VF incidence, mortality, arrhythmia score with a dose-dependent manner. At the same time, rats serum lactate dehydrogenase (LDH) and creatine kinase (CK) activities decreased significantly by TJ0711 (1 and 2 mg x kg(-1)). Ouabain could cause arrhythmia in guinea pigs, when TJ0711 (0.375, 0.75, 1.5 and 3 mg x kg(-1)) was given, the doses of ouabain inducing a variety of arrhythmia PVC, VT, VF, cardiac arrest (CA) were significantly increased with a dose-dependent manner. In the TJ0711 0.1-30 micromol x L(-1) concentration range, guinea pig right ventricular papillary muscle action potential RP (rest potential), APA (action potential amplitude) and V(max) (maximum velocity of depolarization) were not significantly affected. APD20, APD50 and APD90 had a shortening trend but no statistical difference with the increase of TJ0711 concentration. TJ0711 has antiarrhythmic effect on the sympathetic nerve excitement and myocardial cell high calcium animal arrhythmia model. Myocardial action potential zero phase conduction velocity and resting membrane potential were not inhibited by TJ0711. APD20, APD50 and APD90 were shortened by TJ0711 at high concentration. Its antiarrhythmic action mechanism may be besides the action of blocking beta1 receptor, may also have a strong selective blocking action on alpha1 receptor and reducing intracellular calcium concentration.
Action Potentials ; drug effects ; Adrenergic alpha-Antagonists ; administration & dosage ; pharmacology ; Adrenergic beta-Antagonists ; administration & dosage ; pharmacology ; Animals ; Anti-Arrhythmia Agents ; administration & dosage ; pharmacology ; Arrhythmias, Cardiac ; blood ; chemically induced ; etiology ; pathology ; physiopathology ; Calcium Chloride ; Creatine Kinase ; blood ; Dose-Response Relationship, Drug ; Female ; Guinea Pigs ; Heart Ventricles ; cytology ; Lactate Dehydrogenases ; blood ; Male ; Myocardial Reperfusion Injury ; complications ; Myocytes, Cardiac ; drug effects ; physiology ; Ouabain ; Papillary Muscles ; cytology ; Phenoxypropanolamines ; administration & dosage ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley

BACKGROUND/AIMS: Amiodarone is one of the most widely used antiarrhythmic agents; however, amiodarone-induced pulmonary toxicity (APT) can be irreversible and sometimes fatal. The aim of this study was to evaluate the feasibility of chest computed tomography (CT) as a diagnostic tool for APT and to assess the utility of the CT APT score as an index for predicting the severity of APT. METHODS: Patients underwent amiodarone treatment for various reasons, most often atrial fibrillation, for more than 2 years, and those that received a cumulative dose > 100 g were enrolled. A total of 34 patients who underwent chest CT between December 2011 and June 2012 were enrolled, whether or not they had clinical symptoms. The APT CT score was defined as the number of involved regions in the lung, which was divided into 18 regions (right and left, upper, middle, and lower, and central, middle, and peripheral). The CT findings were evaluated according to the total dose and duration of amiodarone treatment and the results of a pulmonary function test. Clinical symptoms and outcomes were also evaluated according to APT CT scores. RESULTS: Seven patients had positive APT CT scores (interstitial fibrosis in five, organizing pneumonia in one, and mixed interstitial fibrosis and organizing pneumonia in one), and these patients exhibited significantly lower diffusion capacity for carbon monoxide in the lungs compared with patients without an increased APT CT score (70.2% +/- 6.9% vs. 89.7% +/- 19.4%; p = 0.011). Three of the seven patients experienced overt APT that required hospital admission. CONCLUSIONS: Chest CT is a useful diagnostic tool for APT, and the APT CT score might be a useful index for assessing the severity of APT.
Aged ; Amiodarone/*adverse effects ; Anti-Arrhythmia Agents/*adverse effects ; Atrial Fibrillation/diagnosis/*drug therapy ; Cross-Sectional Studies ; Cryptogenic Organizing Pneumonia/chemically induced/physiopathology/*radiography/therapy ; Feasibility Studies ; Female ; Forced Expiratory Volume ; Hospitalization ; Humans ; Lung/drug effects/physiopathology/*radiography ; Male ; Middle Aged ; Predictive Value of Tests ; Prospective Studies ; Pulmonary Diffusing Capacity ; Pulmonary Fibrosis/chemically induced/physiopathology/*radiography/therapy ; Respiratory Function Tests ; Risk Factors ; Time Factors ; *Tomography, X-Ray Computed ; Vital Capacity

Abnormal enhanced transmural dispersion of repolarization (TDR) plays an important role in the maintaining of the severe ventricular arrhythmias such as torsades de pointes (TDP) which can be induced in long-QT (LQT) syndrome. Taking advantage of an in vitro rabbit model of LQT2, we detected the effects of KN-93, a CaM-dependent kinase (CaMK) II inhibitor on repolarization heterogeneity of ventricular myocardium. Using the monophasic action potential recording technique, the action potentials of epicardium and endocardium were recorded in rabbit cardiac wedge infused with hypokalemic, hypomagnesaemic Tyrode's solution. At a basic length (BCL) of 2000 ms, LQT2 model was successfully mimicked with the perfusion of 0.5 μmol/L E-4031, QT intervals and the interval from the peak of T wave to the end of T wave (Tp-e) were prolonged, and Tp-e/QT increased. Besides, TDR was increased and the occurrence rate of arrhythmias like EAD, R-on-T extrasystole, and TDP increased under the above condition. Pretreatment with KN-93 (0.5 μmol/L) could inhibit EAD, R-on-T extrasystole, and TDP induced by E-4031 without affecting QT interval, Tp-e, and Tp-e/QT. This study demonstrated KN-93, a CaMKII inhibitor, can inhibit EADs which are the triggers of TDP, resulting in the suppression of TDP induced by LQT2 without affecting TDR.
Action Potentials ; drug effects ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Arrhythmias, Cardiac ; etiology ; physiopathology ; prevention & control ; Benzylamines ; pharmacology ; Calcium-Calmodulin-Dependent Protein Kinase Type 2 ; antagonists & inhibitors ; metabolism ; Electrocardiography ; Electrophysiologic Techniques, Cardiac ; Endocardium ; drug effects ; physiopathology ; Heart ; drug effects ; physiopathology ; In Vitro Techniques ; Long QT Syndrome ; complications ; Pericardium ; drug effects ; physiopathology ; Piperidines ; pharmacology ; Protein Kinase Inhibitors ; pharmacology ; Pyridines ; pharmacology ; Rabbits ; Sulfonamides ; pharmacology ; Torsades de Pointes ; etiology ; physiopathology ; prevention & control

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

The purpose of the present study was to examine the effects of oxidative stress on ventricular arrhythmias in rabbits with adriamycin-induced cardiomyopathy and the relationship between oxidative stress and ventricular arrhythmia. Forty Japanese white rabbits were randomly divided into four groups (n=10 in each): control group, metoprolol (a selective β1 receptor blocker) group, carvedilol (a nonselective β blocker/α-1 blocker) group and adriamycin group. Models of adriamycin-induced cardiomyopathy were established by intravenously injecting adriamycin hydrochloride (1 mg/kg) to rabbits via the auri-edge vein twice a week for 8 weeks in the adriamycin, metoprolol and carvedilol groups. Rabbits in the control group were given equal volume of saline through the auri-edge vein. Rabbits in the metoprolol and carvedilol groups were then intragastrically administrated metoprolol (5 mg/kg/d) and carvedilol (5 mg/kg/d) respectively for 2 months, while those in the adriamycin and control groups were treated with equal volume of saline in the same manner as in the metroprolol and carvedilol groups. Left ventricular end diastolic diameter (LVEDd) and left ventricular ejection fraction (LVEF) were measured by echocardiography. Plasma levels of N-terminal pro B-type natriuretic peptide (NT-proBNP), malondialdehyde (MAD) and superoxide dismutase (SOD) were detected. The left ventricular wedge preparations were perfused with Tyrode's solution. The transmural electrocardiogram, transmural action potentials from epicardium (Epi) and endocardium (Endo), transmural repolarization dispersion (TDR) were recorded, and the incidences of triggered activity and ventricular arrhythmias were obtained at rapid cycle lengths. The results showed that TDR and the serum MDA and NT-proBNP levels were increased, and LVEF and the serum SOD level decreased in the adriamycin group compared with the control group. The incidences of triggered activity and ventricular arrhythmia were significantly higher in the adriamycin group than those in the control group (P<0.05). In the carvedilol group as compared with the adriamycin group, the serum SOD level and the LVEF were substantially increased; the TDR, and the serum MDA and NT-proBNP levels were significantly decreased; the incidences of triggered activity and ventricular arrhythmia were obviously reduced (P<0.05). There were no significant differences in the levels of MDA and SOD, LVEF, TDR and the incidences of triggered activity and ventricular arrhythmia between the adriamycin group and the metoprolol group. It was concluded that carvedilol may inhibit triggered activity and ventricular arrhythmias in rabbit with adriamycin-induced cardiomyopathy, which is related to the decrease in oxygen free radials.
Animals ; Anti-Arrhythmia Agents ; administration & dosage ; Antibiotics, Antineoplastic ; Carbazoles ; administration & dosage ; Cardiomyopathies ; chemically induced ; physiopathology ; prevention & control ; Doxorubicin ; Heart Rate ; drug effects ; Male ; Metoprolol ; administration & dosage ; Oxidative Stress ; drug effects ; Propanolamines ; administration & dosage ; Rabbits ; Treatment Outcome ; Ventricular Fibrillation ; chemically induced ; physiopathology ; prevention & control

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.
Adult ; Aged ; Aged, 80 and over ; Arrhythmia, Sinus ; diagnosis ; physiopathology ; Arrhythmias, Cardiac ; physiopathology ; Electrocardiography ; methods ; Female ; Humans ; Male ; Middle Aged ; Wavelet Analysis ; Young Adult

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

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

This study is to investigate the effects of phenytoin sodium, lidocaine (sodium channel blockers), propranolol (beta-adrenergic receptor antagonist), amiodarone (drugs prolonging the action potential duration) and verapamil (calcium channel blockers) on arrhythmia of mice induced by Bufonis Venenum (Chansu) and isolated mouse hearts lethal dose of Chansu. Arrhythmia of mice were induced by Chansu and then electrocardiograms (ECGs) were recorded. The changes of P-R interval, QRS complex, Q-T interval, T wave amplitude, heart rate (HR) were observed. Moreover, arrhythmia rate, survival rate and arrhythmia score were counted. Isolated mouse hearts were prefused, and the lethal dose of Chansu was recorded. Compared with control group, after pretreatment with phenytoin sodium, broadening of QRS complex and HR were inhibited, and the incidence of ventricular arrhythmia was reduced dramatically, while survival rate was improved; the isolated mouse hearts lethal dose of Chansu was increased significantly. After pretreatment with lidocaine, the prolongation of P-R interval and broadening of QRS complex were inhibited, and the incidences of ventricular arrhythmia were reduced dramatically, while survival rate was improved; the isolated mouse hearts lethal dose of Chansu was increased significantly. After pretreatment with propranolol, prolongation of P-R interval, broadening of QRS complex, prolongation of Q-T interval and HR were inhibited, and the incidences of both supraventricular and ventricular arrhythmias were reduced dramatically, while survival rate was improved. After pretreatment with amiodarone, HR was inhibited, the incidences of ventricular tachycardia were reduced dramatically. Lastly, after pretreatment with verapamil, the prolongation of P-R interval and Q-T interval were inhibited and the incidences of both supraventricular and ventricular arrhythmias were reduced dramatically; the isolated mouse hearts lethal dose of Chansu was reduced significantly. In in vivo experiments, phenytoin sodium was most effective against the mice arrhythmias induced by Chansu while cautious use of verapamil for Chansu inducing arrhythmia should be noted. It is also concluded that mice ventricular arrhythmias induced by Chansu might be most closely related to sodium channel, supraventricular arrhythmias might be related to beta-adrenergic receptor, and calcium channel plays an important role in conduction block. In in vitro experiments, phenytoin sodium was most effective, followed by lidocaine and propranolol, and amiodarone had no obvious effect and verapamil reduced the lethal dose of Chansu.
Amiodarone ; pharmacology ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Arrhythmias, Cardiac ; chemically induced ; physiopathology ; Bufanolides ; toxicity ; Electrocardiography ; drug effects ; Female ; Heart Rate ; drug effects ; In Vitro Techniques ; Lethal Dose 50 ; Lidocaine ; pharmacology ; Male ; Mice ; Phenytoin ; pharmacology ; Propranolol ; pharmacology ; Verapamil ; pharmacology