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Objective@#To evaluate the efficacy and safety of nifekalan (NIF) on cardioversion in atrial fibrillation (AF) patients post radiofrequency ablation, and investigate the relevant factors related to the cardioversion efficacy of NIF.@*Methods@#We screened patients with sustained AF rhythm after radiofrequency ablation between November 2016 and July 2018. Participants were treated with intravenous NIF 0.4 mg/kg within 5-10 minutes after ablation. We observed the adverse reaction, and monitored the rhythm, heart rate, QT interval and QTc interval before the medication and at 5, 10, 20, 120 min after the medication. According to the drug outcome of NIF, patients were divided into conversion group and non-conversion group, related factors affecting conversion efficacy were evaluated using logistic regression analysis.@*Results@#(1)A total of 116 patients were enrolled in the study (63 males and 53 females, mean age was (64±18) years). Among them, 72 patients were converted to sinus rhythm, and the overall successful rate was 62.1%. There were 84 patients with persistent AF, of which 50 cases (59.2%) were restored to sinus rhythm. There were 32 patients with paroxysmal AF, 22 cases (68.8%) of them were restored to sinus rhythm. The conversion time was 1.5 to 12 (6.8±3.4)min. (2) In 116 patients, the QT interval and QTc interval were significantly longer after medication than before the drug administration (P<0.01), and peaked at about 10th min, and restored to the level before drug administration at about 120th min. (3) There were 8 cases of bradycardia (6.9%), 3 cases of frequent and short ventricular tachycardia (2.6%). (4) The duration of atrial fibrillation was shorter and left atrial diameter was smaller in the cardioversion group than in the non-cardioversion group (both P<0.05). There were no significant differences in gender, disease history, atrial fibrillation type and structural heart disease between the two groups (P>0.05). (5) Multifactorial logistic regression analysis showed that the duration of atrial fibrillation (OR=0.980, 95%CI 0.966-0.994, P=0.004) and the left atrial diameter (OR=0.888, 95%CI 0.814-0.967, P=0.007) were the factors that influence the cardioversion efficacy of NIF on atrial fibrillation post ablation.@*Conclusions@#The total effective rate of NIF was 62.1% in patients witrh sustained AF post radiofrequency ablation, was 68.8% in patients with paroxysmal AF. Besides, NIF has the advantage of short conversion time and few adverse reactions. Left atrium diameter and AF duration were relevant factors that influence the efficacy of NIF of cardioversion in patients with sustained AF after radiofrequency ablation.
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Objective@#To explore the clinical and molecular genetic features of a Chinese patient with catecholaminergic polymorphic ventricular tachycardia (CPVT).@*Methods@#Clinical data including resting electrocardiography, echocardiography and treadmill exercise testing of a patient with CPVT admitted to our department in March 2013 were analyzed, and the peripheral venous blood samples of the patient and his family members and 400 ethnicity-matched healthy controls were obtained. All exons and exon-intron boundaries of the six CPVT-related genes including RYR2, CASQ2, TRDN, CALM1, KCNJ2 and ANKB were sequenced to detect the variants related to CPVT. The relationship between the genotypes and phenotypes was analyzed to direct the target therapy.@*Results@#Recurrent syncope induced either by exercise or extreme frightened fear was observed in this patient. There was no positive family history of syncope or sudden death. The resting electrocardiography and echocardiography of the patient were normal, while the exercise testing revealed bidirectional and polymorphic ventricular tachycardia. A cardiac ryanodine receptor gene mutation (R2401H) was identified in this patient, while this mutation was absent in his parents and sister and 400 controls. No variant was detected in the remaining five candidate genes. Treatment with high dose of metoprolol succinate (118.75 mg/d) was effective and patient was free of syncopal attack during the 2 years follow-up.@*Conclusion@#This is the first report on RyR2-R2401H mutation in Chinese patient with CPVT, and high dose of metoptolol is the effective therapy option for CPVT related to RyR2 mutation.
ABSTRACT
<p><b>OBJECTIVES</b>We identified the long QT syndrome (LQTS) patients, and detected the potential risk of LQTS in family members by using genetic testing and electrophysiological analysis, which helped provide clinical evaluation and appropriate treatment.</p><p><b>METHODS</b>Detailed clinical characteristics and familiar history were obtained from the whole family members of an idiopathic pediatric LQTS patient. Two hundred healthy subjects with the same ethnic background were recruited as controls. The entire coding sequences of three candidate genes including KCNQ1, KCNH2 and SCN5A were screened for mutations in the proband. The function of the mutation was then explored by whole-cell patch clamp techniques, and the genetic testing and risk assessment of the family members were performed.</p><p><b>RESULTS</b>The proband was clinically preliminary diagnosed as LQTS by 12-lead electrocardiogram. On the third day of metoprolol intake (25 mg, bid), she died suddenly at lunch. One heterozygous missense mutation (SCN5A-V411M) was identified in this proband, but the mutation was absent in 200 healthy subjects. The electrophysiological analysis indicated that SCN5A-V411M significantly increased the peak current density ((230.8 ± 27.6)pA/pF vs. (101.2 ± 10.9)pA/pF, n=10, P<0.01) and the late sodium current ((156.6 ± 13.6)pA/pF vs. (95.9 ± 7.9)pA/pF, n=12, P<0.01) of sodium channel compared to wide type. The enhanced sodium channel activation with a negative shift in the peak I-V relationship was significantly higher by -50 mV than wide type (85.0%± 7.4% vs. 41.5% ± 2.6%, P<0.01), while the steady-state inactivation curves remained unchanged. Additionally, mother and grandmother of the proband were the silent mutation carriers with no symptoms, who needed the appropriate clinical assessment and follow-up. The proband's twin sister and aunt died of sudden infant death syndrome.</p><p><b>CONCLUSIONS</b>We firstly reported a heterozygote missense mutation (SCN5A-V411M) in this Chinese family. V411M induced "gain of function" of sodium channel and formed the basis of type-3 LQTS. Genetic testing could help to increase the diagnostic accuracy, and facilitate clinical assessment and appropriate therapy to prevent sudden cardiac death of individuals with SCN5A-V411M mutation.</p>