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ABSTRACT:Objective To observe the effects of late Na current (INa‐L ) and rapidly activating delayed rectifier K current (IKr ) on ventricular heterogeneity and frequency dependency by using high resolution voltage sensitive optical mapping technology .Methods The model of 12 isolated hearts was constructed in rabbits . Voltage sensitive dye Di‐4‐ANEPPS were perfused into the isolated hearts by Langendorff method .LED source with the wave length of 532 nm was used to record APD80 and APD50 of the left and right ventricles .Experimental groups were divided into 3 groups by perfusion drugs dofetillide (30 nmol/L) ,dofetillide+ATX‐Ⅱ(1 nmol/L) ,and dofetillide +ATX‐Ⅱ +mexiletine (10μmol/L) .The subjects were intervened by the above drugs in order ,and they were self‐compared before dosing .After each drug administration ,the hearts were stimulated respectively with the BCL of 2 000 ms ,1 000 ms ,500 ms ,and 300 ms .Then we observed the changes of APD80 and APD50 in the left and right ventricles before and after the interventions .Results ① In the control group ,APD80 and APD50 of the right ventricle were longer than those of the left ventricle in response to different stimulation , and the differences increased with the decrease of stimulating frequency .② When BCL was 1000 ms ,APD80 and APD50 of the left and right ventricles were prolonged respectively after administration of dofetillide , but the differences in APD80 and APD50 were insignificant between the left and right ventricles (P>0 .05) .ΔAPD80 of the two ventricles increased significantly with the decrease of stimulating frequency . ③ After administration of ATX‐Ⅱ , when BCL was 1000 ms ,APD80 and APD50 of the left and right ventricles increased significantly compared with those in the control group and dofetillide intervention group (P0 .05) .The increase of ΔAPD80 of the two ventricles became milder when the stimulating frequency decreased . Conclusion ① IKr blocked by dofetillide did not affect the heterogeneity between the two ventricles , which showed reverse‐frequency dependence . ② In the context of blocking IKr , ATX‐Ⅱ increased the heterogeneity between the left and right ventricles and enhanced the reverse‐frequency dependence .In contrast ,mexiletine ,the blocker of INa‐L ,decreased the heterogeneity between the two ventricles and reverse‐frequency dependence .
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Objective To reveal the role of serum ACE2/Ang (1-7)in the occurrence of atrial fibrillation (AF)and find new targets for the prevention and treatment of AF by analyzing the correlation between the serum concentration of ACE2/Ang (1-7 )in patients with rheumatic valvular heart disease and the occurrence of AF. Methods We collected the basic clinical information and peripheral venous blood of patients with rheumatic heart valve disease (totally 46 patients,including 24 with AF and 22 with SR).ELISA method was used to detect the serum concentration of ACE2,Ang (1-7)and AngⅡ in the serum samples.Then the differences and correlation between the two groups were analyzed.Results In the AF group ① the diameter of the left atrium was significantly greater than that in the SR group [(60.70±3.08 vs.48.15±2.16)mm,P<0.05];② the serum concentration of AngⅡ was significantly higher than that in the SR group [(45.88±2.87 vs.35.78±1.08)pg/mL, P<0.05],AngⅡ and left atrium diameter were positively correlated (Pearson test,P<0.05);③ the serum concentrations of ACE2 [(7.87±0.74 vs.11.65±0.57)U/L,P<0.05]and Ang (1-7)[(146.05±17.61 vs. 321.71±36.50)pg/mL,P<0.05]were significantly lower than those in the SR group,and negatively correlated with left atrium diameter (Pearson test,P<0.05);④ the serum concentration of Ang (1-7)was negatively correlated with AngⅡ concentration (Pearson test,P<0.05).Conclusion For patients with rheumatic valvular heart disease,ACE2/Ang (1-7 )may play a protective role in the occurrence of AF via antagonizing AngⅡ and inhibiting atrial remodeling.
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Objective To assess the therapeutic effect and safety of radiofrequency catheter ablation of atrial fibrillation.Methods We analyzed the clinical data of 47 patients with atrial fibrillation who underwent radiofrequency catheter ablation between March 2013 and January 2008,in the First Affiliated Hospital of Xi'an Jiaotong University.In the average 32 months’follow-up,Holter monitering and echocardiography were reviewed for the left atrial diameter.Results The immediate success rate of catheter ablation for atrial fibrillation was 82.6%.The long-term success rate was 65%,the rate of paroxysmal atrial fibrillation was 69.7%,and the rate of longstanding persistent atrial fibrillation was 42.9%.After ablation,the left atrial diameter were markedly reduced compared with that before treatment [(36.3 ± 4.3 )mm vs .(38.1 ± 5.9 )mm)(P < 0.001 ).The patients with recurrent atrial fibrillation were older than those without recurrence,their left atrial diameter was bigger,and the prevalence rate of hypertension was higher (P <0.05).The average atrial fibrillation load was 14.9% after ablation compared with 46.1% before (P <0.05).Conclusion Radiofrequency catheter ablation is an effective and safe treatment of atrial fibrillation,especially for paroxysmal atrial fibrillation.The left atrial diameter was significantly decreased after radiofrequency catheter ablation compared with that before the ablation.
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Objective To assess the effectiveness and safety of radiofrequency catheter ablation for idiopathic ventricular arrhythmia in patients with idiopathic ventricular arrhythmia after radiofrequency catheter ablation treated in the First Affiliated Hospital of Xi’an Jiaotong University based on the follow-up and retrospective analysis.Methods We retrospectively analyzed the clinical data of 63 patients with idiopathic ventricular arrhythmia who underwent radiofrequency catheter ablation during January 2008 and March 2014 in the First Affiliated Hospital of Xi’an Jiaotong University.In the follow-up,Holter moniterings were reviewed to evaluate ventricular arrhythmia and echocardiography to assess the ejection fractions and left ventricular end-diastolic diameters.Results The immediate success rate of catheter ablation for the treatment of idiopathic ventricular arrhythmia was 89.29% and the long-term success was 82.14%.The ejection fractions and left ventricular end-diastolic diameters were not obviously improved after radiofrequency ablation (P > 0.05 ). The ventricular premature contractions were significantly reduced after radiofrequency ablation (P <0.05).In postoperative care, one case was found with ruptured sinus valsalva tumor and another patient was found with the complication of hematoma in femoral artery puncture.Conclusion Radiofrequency ablation for idiopathic ventricular arrhythmia is safe and effective.