The Chinese expert recommendations on the clinical use of dronedarone / 中华内科杂志

Dronedarone, a class Ⅲ antiarrhythmic drug, is a deiodinated benzofuran derivative of amiodarone. It has similar antiarrhythmic effects with amiodarone, but much lesser adverse effects than amiodarone, particularly in those outside the heart. It is suggested to use dronedarone for the rhythm control of atrial fibrillation/flutter, for it has been shown to prevent the recurrence of atrial fibrillation/flutter and reduce rehospitalization in patients with paroxysmal or persistent atrial fibrillation/flutter. Dronedarone is not recommended for the rhythm control in patients with long-term persistent atrial fibrillation or permanent atrial fibrillation, and atrial flutter or atrial fibrillation patients with reduced ejection fraction. Liver function, electrolyte tests and an electrocardiogram should be performed before and after the drug initiation. Potential interactions with other kinds of drugs have to be taken into consideration as well.

Mid and long-term outcomes of catheter ablation of recurrent atrial tachycardias post Mini-Maze surgery / 中国介入心脏病学杂志

Objective To analyze the clinical characteristics and follow-up data of catheter ablation of recurrent atrial tachycardias (ATs) after Mini-Maze surgery,and to explore prognostic factors for recurrence.Methods 59 patients in Guangdong General Hospital with ATs post Mini-Maze and concomitant open-heart surgery from April.2010 to June.2015 were included.According to high density precise mapping,activation mapping,voltage mapping and entrainment mapping,they underwent electrophysiological study and ablation which was guided by three-dimensional mapping system.All patients were followed up regularly.We explored the prognostic factors for recurrence by the Cox regression analysis.Results There were 88 types of ATs being mappedwith mean (1.49 ± 0.75) types of ATs identified per case.Most ATs were macro-reentry ATs(67/88,76.1％)and focal ATs (20/88,22.7％),respectively.56 patients (94.9％) achieved immediate ablation success.In a mean follow-up of (30.8 ± 17.7) months,recurrences were observed in 12 patients after the first time catheter ablation.Recurrent time was 3.5 (1.3,12.0) months and the overall ablation success rate was 74.6％ (44/59).6 patients received second ablation and the achievement of freedom from arrhythmias reached 79.7％ (47/59).Multivariate analysis showed that the LA diameter was the independent predictor for recurrence (HR 1.108,95％ CI 1.002 to 1.226,P =0.045).Conclusion Catheter ablation of ATs post Mini-Maze with concomitant surgery is save and feasible.LA diameter is the independent predictor for recurrence.

MEF2C mediates inhibitory effect of microRNA-214 on cardiomyocyte hypertrophy / 中国病理生理杂志

AIM:To investigate the effect of microRNA-214 ( miR-214) on cardiomyocyte hypertrophy and the expression of the potential target genes .METHODS:A cell model of hypertrophy was established based on angiotensin-Ⅱ( Ang-Ⅱ)-induced neonatal mouse ventricular cardiomyocytes ( NMVCs) .Dual luciferase reporter assay was performed to verify the interaction between miR-214 and the 3’ UTR of MEF2C.The expression of MEF2C and hypertrophy-related genes at mRNA and protein levels was determined by RT-qPCR and Western blot , respectively .RESULTS:The expression of ANP, ACTA1,β-MHC and miR-214 was markedly increased in Ang-Ⅱ-induced hypertrophic cardiomyocytes .Dual lu-ciferase reporter assay revealed that miR-214 interacted with the 3’ UTR of MEF2C, and miR-214 was verified to inhibit MEF2C expression at the transcriptional level .The protein expression of MEF2C was markedly increased in the hypertro-phic cardiomyocytes .Moreover, miR-214 mimic, in parallel to MEF2C siRNA, inhibited the expression of hypertrophy-re-lated genes in Ang-Ⅱ-induced NMVCs.CONCLUSION:MEF2C is a target gene of miR-214, which mediates the effect of miR-214 on attenuating cardiomyocyte hypertrophy .

Effect of circRNA_000203 on fibrotic phenotypes in mouse cardiac fibro-blasts / 中国病理生理杂志

AIM:To determine circular RNA (circRNA) profiles in the diabetic mouse myocardium , and to investigate the effect of circRNA_000203 on fibrotic phenotypes in cardiac fibroblasts .METHODS:Masson trichrome stai-ning was performed on the myocardium of the diabetic db /db mice and the non diabetic db/m control mice .circRNA ex-pression profile in the diabetic myocardium was detected by circRNAs microarray .The expression of circRNA_000203 was determined by real time fluorescence quantitative PCR ( RT-qPCR ) .Recombinant circRNA_000203 adenovirus was pre-pared for enforced the expression of circRNA_000203 in mouse cardiac fibroblasts.The expression of Col1a2, Col3a1andα-SMA was determined in circRNA_000203-modified cardiac fibroblasts , respectively .RESULTS:Masson trichrome stai-ning showed that fibrosis was increased in the diabetic mouse myocardium .The results of circRNA array detection revealed that circRNAs were dysregulated in the diabetic myocardium .circRNA_000203 was up-regulated in the diabetic myocardi-um.Significant over-expression of circRNA_000203 was achieved in the cardiac fibroblasts after infection with the recombi-nant circRNA_000203 adenovirus.The mRNA and protein expression of Col1a2, Col3a1 and α-SMA was significantly in-creased in the cardiac fibroblasts with over-expression of circRNA_000203.CONCLUSION:circRNA_000203 is up-regu-lated in the diabetic mouse myocardium .It has pro-fibrotic effect on the cardiac fibroblasts .

Role of tumor necrosis factor-αin the regulation of T-type calcium channel current in HL-1 cells / 中国病理生理杂志

AIM:Increasing evidence indicates that inflammation contributes to the initiation and perpetuation of atrial fibrillation ( AF) .Al-though tumor necrosis factor ( TNF)-αlevels are increased in patients with AF , the role of TNF-αin the pathogenesis of AF remains unclear.Recent research has revealed that T-type Ca2+currents ( ICa,T ) play an important role in the pathogenesis of AF .METH-ODS:In this study , we used the whole-cell voltage-clamp technique and biochemical assays to explore the role of TNF-αin the regula-tion of ICa,T in atrial myocytes.RESULTS:We found that compared with sinus rhythm (SR) controls, T-type calcium channel (TCC) subunit mRNA levels were decreased , while TNF-αexpression levels were increased , in human atrial tissue from patients with AF .In murine atrial myocyte HL-1 cells, after cultured for 24 h, 12.5, 25 and 50 μg/L TNF-αsignificantly reduced the protein expression levels of the TCC α1G subunit in a concentration-dependent manner .The peak current was reduced by the application of 12.5 or 25μg/L TNF-αin a concentration-dependent manner [from ( -15.08 ±1.11) pA/pF in controls to ( -11.89 ±0.83) pA/pF and (-8.54 ±1.55) pA/pF in 12.5 and 25 μg/L TNF-αgroups, respectively].TNF-αapplication also inhibited voltage-dependent inactivation of ICa,T shifted the inactivation curve to the left .CONCLUSION:These results suggest that TNF-αis involved in the path-ogenesis of AF, probably via decreasing ICa,T function in atrium-derived myocytes through impaired channel function and down -regula-tion of channel protein expression .This pathway thus represents a potential pathogenic mechanism in AF .

Cx43 is involved in electrical remodeling of atrial myocytes through regu-lating L-type calcium current / 中国病理生理杂志

AIM:To investigate whether the association of connexin 43 ( Cx43 ) and L-type calcium channel involved in the pathogenesis of atrial fibrillation ( AF) .METHODS:The biochemical assays and whole-cell patch-clamp technique were used to study the expression of Cx43 in human atrial tissue.The co-localization of Cx43 and L-type calcium channel, and the regulation of L-type calcium current in atrial myocytes were investigated.RESULTS:The expression of Cx43 at mRNA and protein levels was decreased in human atrial tissues of AF patients.In cultured atrium-derived myocytes ( HL-1 cells) , knockdown of Cx43 significantly inhibited the mRNA expression of L-type calcium channelα1c subunit, as well as L-type calcium current.Co-localization of Cx43 with L-type calcium channel α1c subunit in mouse atrial myocytes was observed.CONCLUSION:The decrease in Cx43 is involved in the pathogenesis of AF, probably through reducing the L-type calcium current in atrial myoctyes by co-localization with L-type calcium channel, thus representing the potential pathogenesis in atrial fibrillation.

Inaccuracy of doppler echocardiographic estimates of pulmonary artery pressures in adult atrial septal defect patients with pulmonary arterial hypertension / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>While echocardiography has been a pivotal screening test in pulmonary arterial hypertension (PAH), the presence of structural cardiac defects may affect the ability to reliably predict pulmonary artery pressures (PAPs). This study sought to evaluate the accuracy of Doppler echocardiography (DE) for estimating PAPs in adult atrial septal defect (ASD) patients with PAH.</p><p><b>METHODS</b>A prospective study was carried out to compare the echocardiographic assessment of PAP with the same pressures obtained by right heart catheterization (RHC) in adult ASD patients with PAH who underwent simultaneous DE and RHC. Bland-Altman analyses were performed to evaluate the agreement between DE and RHC measurements of PAPs.</p><p><b>RESULTS</b>Two hundred and fifty-seven patients were included in the study. A significant overestimation of the systolic pulmonary arterial pressure (sPAP) and mean pulmonary artery pressure (mPAP) was reported by echocardiography compared with those by catheterization ((81.8 ± 26.9) mmHg vs. (72.9 ± 26.9) mmHg, P < 0.01; (51.9 ± 16.4) mmHg vs. (41.4 ± 17.2) mmHg, P < 0.01, respectively). Twenty-one percent (55/257) of the patients had PAH when estimated by echocardiography whereas showed normal results in the subsequent catheterization test. Using Bland-Altman analytic methods, the bias for the echocardiographic assessment of the sPAP was 9.1 mmHg with 95% limits of agreement ranging from -24.4 to 42.6 mmHg. For mPAP measurement, the bias was 10.5 mmHg with 95% limits of agreement ranging from -12.4 to 33.4 mmHg. On multiple linear regression analysis, age, gender, body surface area, ASDs' diameter, PVR, diastolic blood pressure, and echocardiographic assessment of right atrial pressure (RAP) explained 68.8% of the total variability in the model (r(2) = 0.688, P < 0.01).</p><p><b>CONCLUSION</b>Inaccuracy was frequently reported in Doppler echocardiographic assessment of the PAP in adult ASD patients with PAH and was often associated with age, gender, body surface area, ASDs' diameter, pulmonary vascular resistance, diastolic blood pressure and echocardiographic estimation of RAP.</p>

Effects of iloprost combined with low dose tadalafil in adult congenital heart disease patients with severe pulmonary arterial hypertension: a single-center, open-label controlled study / 中华心血管病杂志

<p><b>OBJECTIVE</b>To evaluate the therapy efficacy of iloprost combined with low dose tadalafil in adult congenital heart disease (CHD) patients with severe pulmonary arterial hypertension (PAH).</p><p><b>METHODS</b>Adult CHD patients with severe PAH were included and divided into the sequential combination therapy group [iloprost: 10 µg/inhalation, 6 times per day for 6 months, and then add oral tadalafil (5 mg/d) till 12 months, n = 32] and upfront combination therapy group [iloprost: 10 µg/inhalation, 6 times per day combined with oral tadalafil (5 mg) for 12 months, n = 36]. Data on 6 min walking test (6MWT), Borg dyspnea score, oxygen saturation measurement, WHO classification, and cardiac catheterization were obtained at baseline, 6 and 12 months.</p><p><b>RESULTS</b>Seventy-two patients were enrolled in the study and 68 patients completed the study. Pulmonary vascular resistance (PVR) was significantly reduced in the sequential combination therapy group[ (12.96 ± 6.48 ) Wood U vs. (16.94 ± 8.11) Wood U, P < 0.05] and in the upfront combination therapy group [(12.45 ± 7.32) Wood U vs. (16.73 ± 9.28) Wood U, P < 0.05] while pulmonary blood flow [(6.77 ± 3.17) L/min vs. (5.08 ± 2.36) L/min, P < 0.05; (6.95 ± 3.32) L/min vs. (5.03 ± 2.32) L/min, P < 0.05], the 6 MWD were significantly increased [(458 ± 59) m vs. (427 ± 65) m, P < 0.05; (494 ± 59) m vs. (436 ± 62) m, P < 0.01], the Borg dyspnea score (2.04 ± 0.72 vs. 2.52 ± 0.79, P < 0.05; 1.72 ± 0.73 vs. 2.51 ± 0.77, P < 0.01) was significantly improved in both groups at 6 months compared to baseline levels. In the upfront combination therapy group, venous oxygen saturation [(68.4 ± 9.3)% vs. (62.9 ± 9.5)%, P < 0.05] and systemic oxygen saturation during exercise[ (87.2 ± 9.7)% vs. (83.1 ± 15.6)%, P < 0.05]at 6 months were also significantly improved compared to baseline. At month 12, significantly lowered pulmonary artery pressure, PVR, Rp/Rs and increased pulmonary blood flow and cardiac index were evidenced in both groups compared to baseline.</p><p><b>CONCLUSION</b>Iloprost combined with low dose tadalafil regimen can effectively reduce PVR, increase 6MWD, and improve cardiopulmonary function in adults CHD patients with severe PAH. Compared with the sequential therapy regimen, the upfront combination therapy regimen can more rapidly improve the clinical symptoms of patients.</p>

Analysis of atrial fibrillation ablation in patients with rheumatic heart disease after valvula ;surgery / 中国介入心脏病学杂志

Objective To observe efifcacy and safety of catheter ablation for atrial ifbrillation (AF) occurring after surgical valve replacement in patients with rheumatic heart disease (RHD). Methods A total of 23 RHD patients with atrial ifbrillation after surgical valve replacement were enrolled in this study from 2008 to 2013. The clinical characteristics, ablation strategies and successful rate were investigated. Results All the cases included 8 males and 15 females (age, 51.0 ± 9.2 years). Valves replaced were isolated mitral valves (13/23, 56.5%) and multiple valves (10/23, 43.5%). Postoperative AF after cardiac surgery was paroxysmal in 14 patients (60.9%) and nonparoxysmal in 9 cases. Nine patients (39.1%) was in sinus rhythm before cardiac surgery, 4 in paroxysmal AF and 10 in non-paroxysmal AF. The mean interval between the catheter ablation AF and the surgical intervention was (6.9±5.8) years. The postoperative AF duration was (3.1±3.2) years, left and right atrial diameters were (44.1±5.9) mm and (48.1±9.0) mm respectively, left ventricular ejection fraction was 64.0%±8.3%, the mean ablation procedure duration was (156.8±46.6) min, and lfuoroscopy exposure averaged (27.3±11.2) min. Standard pulmonary vein isolation was performed in all cases by using ipsilateral circumferential ablation technique. Additional ablation, including complex fractionated atrial electrograms, mitral and tricuspid isthmus, and left atrial roof, was applied in most of the cases. After a mean follow-up of (29.7±21.2) months (median, 24 months), 60.9%of the patients remained free of AF, 1 died, and 2 lost to follow-up. Conclusions Catheter ablation for AF is effective and safe in patients with RHD after surgical valve replacement. Stepwise ablation strategy may be better for these patients.

Desmoplakin expression silencing affects cardiac voltage-gated sodium channel Nav1.5 in HL-1 cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the association of desmoplakin with the distribution and function of Nav1.5 by RNA silencing technology in HL-1 cells.</p><p><b>METHODS</b>HL-1 cells with desmoplakin expression suppression by RNA silencing were examined for desmoplakin and Nav1.5 protein expressions by Western blotting, and the distribution and co-location of desmoplakin and Nav1.5 protein were detected by immunofluorescence staining. Patch-clamp recording was applied to analyze the changes in whole-cell sodium current after desmoplakin silencing.</p><p><b>RESULTS</b>Compared with the untreated group and negative control group, the cells with desmoplakin silencing showed obviously reduced expressions of desmoplakin and Nav1.5 proteins. Co-localization of desmoplakin and Nav1.5 was detected at cell-cell contact in untreated and control conditions, and desmoplakin expression silencing induced a drastic redistribution of Nav1.5 with decreased peak current density (156.3∓6.2 vs 41.8∓3.1, n=6, P<0.05), a shift in voltage dependence of steady-state inactivation (-42 mV vs -61 mV, n=5, P<0.05), and prolonged time of recovery from inactivation.</p><p><b>CONCLUSION</b>Desmoplakin silencing caused redistribution of Nav1.5 protein and also changes in its electrophysiological properties in HL-1 cells.</p>

The level and source of inflammatory factors in patients with paroxysmal atrial fibrillation / 中国医师进修杂志

Objective To investigate the level and the source of inflammatory factors in patients with paroxysmal atrial fibrillation.Methods Thirty patients with paroxysmal atrial fibrillation were selected as observation group,and 20 cases of patients with paroxysmal supraventricular tachycardia were selected as control group.The blood samples of coronary sinus,right atria,left atria and femoral vein were consecutively collected during the procedure of radiofrequency ablation.The level of tumor necrosis factor (TNF)-α,soluble tumor necrosis factor receptor-1 (sTNFR1),and interleukin(IL)-6 was detected by ELISA separately and compared between two groups.Results The level of TNF-α and IL-6 of coronary sinus,right atria,left atria and femoral vein in observation group was significantly higher than that in control group [TNF-α:(4.45 ± 1.76) ng/L vs.(0.59 ± 0.36) ng/L,(6.67 ± 1.43) ng/L vs.(0.51 ± 0.30) ng/L,(8.35 ± 2.03) ng/L vs.(0.85 ± 0.50) ng/L,(9.97 ± 2.70) ng/L vs.(0.28 ± 0.29) ng/L,P=0.000;IL-6:(2.02 ± 0.87) ng/L vs.(1.04 ± 0.63) ng/L,(1.51 ± 0.68) ng/L vs.(0.74 ± 0.26) ng/L,(2.00 ± 0.51) ng/L vs.(0.88 ± 0.35) ng/L,(1.32 ±0.47) ng/L vs.(0.48 ±0.28) ng/L,P =0.000].The level of high sensitivity C reactive protein (hs-CRP) in observation group was significantly higher than that in control group [(2.41 ± 1.35) mg/L vs.(1.10 ±0.53) mg/L,P =0.002].The level of TNF-αof left atrium in observation group was significantly higher than that of other three sites (P=0.000).The level of IL-6 in the coronary sinus and femoral vein was significantly increased,compared with that in the right atria and left atria (P ＜ 0.05).The level of sTNFR 1 in the femoral vein,right atria and coronary sinus difference was not statistically significant (P ＞ 0.05),but was significantly higher than that in the left atria(P ＜ 0.05).The level of TNF-α,IL-6 and hs-CRP was correlated with the diameter of left atrium (LAD) (P ＜ 0.01 or ＜ 0.05).The level of sTNFR1 in left atria was positively correlated with LAD,and the level of sTNFR1 in right atria was negatively correlated with LAD (P ＜ 0.01).Conclusions The level of TNF-α,IL-6 and hs-CRP is increased in patients with paroxysmal atrial fibrillation.TNF-α and IL-6 may come from the heart and is related with the enlargement of left atrium.

Evaluation of left atrial function serial change after circumferential pulmonary vein ablation for paroxysmal atrial fibrillation by tissue Doppler echocardiography / 中华超声影像学杂志

Objective To evaluate left atrial function serial change after circumferential pulmonary vein ablation(CPVA)for paroxysmal atrial fibrillation using tissue Doppler echocardiography.Methods One hundred and eight patients with paroxysmal atrial fibrillation underwent CPVA guided by CARTO.Tissue Doppler imaging and conventional echocardiography were underwent 48 h before CPVA,48 h,1 month,3 month and 6 month after CPVA.Results One hundred and six patients with paroxysmal atrial fibrillation finished CPVA successfully.Compared tO 48 h pre-CPVA,left atrial diameter and volume decreased 48 h,1 month,3 month,6 month after CPVA,significant change were found at 3 month,6 month after CPVA(P＜0.05).Left ventricular end-diastolic diameter(LVEDD),left ventricular end-systolic diameter(LVESD).left ventricular ejection fraction(LVEF),mitral flow E revealed no significant change(P＞0.05).Mitral flow A decreased significantly 48 h after CPVA(P＜0.05),restored significantly after 3 month.Tissue Doppler parameter S'and E'revealed no significant change(P＞0.05)through the period,A'decreased significantly 48 h after CPVA(P＜0.05),restored significantlv after 1 month.Conclusions Left atrial diameter and volume decreased after CPVA.Left atrial active contraction function decreased shortly after CPVA(LA stunning),and restored progressively.

Electroanatomical mapping and radiofrequency ablation of atrial tachycardia in left atria / 中国介入心脏病学杂志

Objective To characterize the electroanatomical mapping and to assess the value of radiofrequency ablation of atrial tachycardia (AT) in left atria. Methods Nine patients with AT in left atria were studied. Three-dimensional electroanatomical maps were constructed in left atrium using electroanatomical mapping system (Carto). The type of AT (focal or macroreentrant) was identified by the electroanatomical maps, and the ablation targets were at the earliest activation sites or the isthmus of circuit. Results There were ten ATs in 9 cases. The relatively early A waves were recorded in middle, distal or proximal parts of coronary sinus catheter. Nine focal ATs were diagnosed. The activation maps demonstrated that the earliest activation sites were at the ostium of pulmonary veins ( n =5), posterior area of left atrium ( n =2), ostia of left atria appendage ( n =1) or left atria appendage ( n =1) respectively. One macroreeentrant AT was diagnosed, whose circuit propagated through the isthmus, formed by the right superior pulmonary vein and fossa ovalis. Eight focal ATs were all ablated successfully at the earliest activation sites, and one AT from left atria appendage was ablated unsuccessfully. Line of ablation was performed at the isthmus of the macroreentrant AT. During a period of 6-30 months follow-up, one patient with focal AT recurred and underwent another ablation with successful result. No complication occurred. The procedure time and the fluoroscopic time were 90-140 min, 8-16 min respectively in successful cases. Conclusion These results suggest that electroanatomical mapping of AT in left atria may facilitate rapid and accurate identification of the type of AT and guide ablation safely or effectively with less fluoroscopic time and higher success rate, especially in unsuccessful cases with conventional technique.

Mapping and catheter ablation of cardiac tachyarrythmias under the guidance of Carto system / 中国介入心脏病学杂志

Objective To evaluate clinically electroanatomical mapping and ablation of cardiac arrhythmias under the Carto system. Methods Fifty-six patients with various tachycardias indicated for electrophysiological study and radiofrequency ablation were included in this study, among of whom, 49 suffered from supraventricular tachycardia, and 7 ventricular tachycardia (VT). Carto system was utilized during ongoing tachycardia or sinus rhythm, 7F Navi-Star catheter was introduced into the interested cardiac chamber and underwent three-dimensional electroanatomical mapping. The mechanism and origin of cardiac arrhythmia were assessed by activation and propagation map, with which to guide radiofrequency ablation. Results The success ablation rate was 94.6% (53/56). One right accessory pathway (AP), one atrial tachycardia (AT) and one atypical atrial flutter (AF) had failed session. The procedure time was 128?59 minutes, and the fluoroscopic time 14?12 minutes. One patient had complcation of pneumothorax. No conduction block occurred. After follow-up of 1-14 months, one left AT recurred and had another succssful session. Conclusion The study demonstrates that Carto system is a safe and effective tool and may be applied for mapping and ablation of various tachyarrhythmias. It is helpful to guide catheter ablation and shorten fluorocopic time by its ability of associate intracardiac electrograms with their three-dimensional anatomic structure. It also lessen complication and recurrence by tagging the critical cardiac structures and utilize its location memory function. Our experience suggest that carto system has important role in the guidance of mapping and ablation in AT、AF、VT and complex or recurrent AP cases.

Modification of atrioventriculat node by radiofrequency ablation of slow pathway with inferior approach in 23 patients with superaventricular tachycardia / 中国介入心脏病学杂志

18 patients with atrioventricular nodal reentant tachycardia (AVNRT)and 5 patients with atrioventricular reentrant tachycardia (AVRT) with AVN double pathway (AVNDP) received radiofrequency ablation of slow pathway with inferior approach in order to modify AVN. AVNRT was induced in slow-fast form in 16 patients, in fast-slow form in one patients,and in coexistent slow-fast and fast-slow forms in one patients. Selective ablation of slow pathway was achieved in 18 patients. AVRT was induced in 5 patients (one obvient accessory pathway, 4 concealed accessory pathways) ,4 patients with reentrant cirucit of consisting of anterograde conduction by slow pathway of AVN and retrograde conduction by accessory pathway (AP) , one patient coexistent AVRT and AVNRT. Slow pathway in 5 patients and AP in 3 patients were successfully ablated. Junctional rhythm appeared in 21 patients during duation of discharge of radiofrequency current. No severe complicationwere noted. AVNRT in one patient recurred during a follow-up period of 1 to 15 months. The patient experienced second catheter ablation and was successed. It was suggested radlofrequency ablation of slow pathway with Inferior approach may be a method with high rate of success and less complication.

Inward rectifier potassium current and mRNA expression of gene Kir2.1 in human atrial fibrillation / 中国病理生理杂志

AIM: To investigate alteration of inward re ctifier potassium current (I K1) in atrial myocytes and mRNA expression of gene Kir2.1 encoding I K1 in atrial myocardial tissue in patients with chronic atrial fibrillation (AF) compared to that with sinus rhythm (SR).METHODS: Single myocytes were isolated by enzymatic dissociation with the chunk method an d the ionic current was recorded using whole cell patch clamp technique. The sem i-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was used to measure the mRNA expression of Kir2.1 in atrial myocardial tissue, and the g ene GAPDH was used as an internal control.RESULTS: (1) The I K1 density was increased in AF group at hyperpolarizing pot entials, at -120 mV the current densities was (-5.71?0.65) pA/pF in AF group (n=28 cells from 7 patients) and (-4.26?1.22) pA/pF in SR group (n=35 cells from 9 patients) (P0.05).CONCLUSIONS: The increase in I K1 at hyperpolarizing potentials may be related to th e atrial electrophysiological remodeling in chronic human AF. The increased I K1 density in atrial myocytes in AF group without alteration of Kir2.1 mRNA expression in atrial tissue suggests that I K1 may be mediated at post-transcriptional levels.