Résumé
Cardiac pacing is an effective treatment for cardiac pacing and conduction dysfunction and severe heart failure. However， the conventional right ventricular pacing may increase the incidences of heart failure and atrial fibrillation， and biventricular pacing has a relatively high non-response rate. As a new technique of physiological pacing， a number of studies in recent years have been conducted to show the stability of pacing parameters and good cardiac synchronization of his-purkinje system pacing. This article reviews the current status of research and progress in the effects of his-purkinje conduction system pacing on cardiac function， so as to provide a theoretical basis for promoting the development of this technology.
Résumé
BACKGROUND/OBJECTIVES: The association between tea consumption and risk of coronary heart disease (CHD) remains controversial. This study aimed to determine whether tea consumption has an effect on CHD risk in Chinese adults. SUBJECTS/METHODS: In this hospital-based case-control study, 267 cases of CHD and 235 non-CHD controls were enrolled. Blood samples from all cases were examined. Cardiac function indices (left ventricular ejection fraction, left ventricular end-diastolic dimension, lactate dehydrogenase, and creatine kinase of the muscle or brain type), blood lipid index (high-density lipoprotein cholesterol), and blood coagulation function indices (fibrinogen and activated partial thromboplastin time) were recorded. Tea consumption of study participants was assessed by a specifically designed questionnaire. The baseline characteristics of the study populations were recorded, and CHD-related biomarkers were detected. Differences in baseline characteristics of the study participants were examined using t-tests for continuous variables and chi-squared tests for categorical variables. Unconditional logistic regression was used to measure the association between tea and CHD. RESULTS: There were significant differences in cardiac function indices, blood lipid index, and blood coagulation indices between CHD cases and controls (P 6 days/week was beneficial for CHD prevention (adjusted OR = 0.183, 95% CI: 0.049–0.679, P = 0.0112). When analyzed according to the duration of tea consumption, the risk of CHD was reduced in participants who had been drinking tea for 10–20 years (adjusted OR = 0.360, 95% CI: 0.137–0.946, P = 0.0382). CONCLUSIONS: Tea consumption is associated with a reduced risk of CHD in female but not male populations in Guangzhou.
Résumé
Objective Explore the relationship of ventricular late potential (VLP) and the heart function of children with viral myocarditis,and provide the evidence for their diagnosis and therapy.Methods The clinical data of 152 cases of epileptic children were collected.The patient group was divided into three groups (severe arrhythmia,heart failure,and cardiogenic shock).The patient group was also divided into two groups (cardiac dilatation,and non-cardiac dilatation) according to UCG.Serum levels of cTnI and VLP in children with viral myocarditis were detected.Results The VLP was negative in the mild and control groups,but the positive rate of VLP is 75.0 ％ in the severe group.The positive rate of VLP was 60.0％ in the severe arrhythmia group,77.78％ in the heart failure group,and 100％ in the shock group.There is one kind of negative rank correlation between LAS,RMS40 and LVFS (P ＜ 0.05),and another negative rank correlation between RMS40 and LVEF (P ＜ 0.05).Conclusions The children with viral myocarditis have a favorable prognosis.The sever patient in the minority must be diagnosed in time and treated because of the critical state of viral myocarditis children.The serum level of cTnI and VLP were increased in children with viral myocarditis,and they were sensitive parameters to reflect patients’ condition.
Résumé
BACKGROUND:The hyperpoladzation-activated cyclic nucleotide-gated cation channel (HCN) gene is not increase the risk of induced cardiac arrhythmia,and can accept the modulation function of autonomic nervous system.Therefore,it is the first candidate gene for biological pacemakers.OBJECTIVE:To construct recombinant adenovirus vector containing human HCN4 gene and evaluate its transfection efficency in rat bone marrow mesenchymal stem cells (MSCs).DESIGN,TIME AND SETTING:The in vitro cytology-gene experiment was performed at the Lin Bai-xin Experimental Center,Second Hospital of Sun Yat-sen University from February to September 2008.MATERIALS:Ten SD rats were supplied by the experimental animal center of Sun Yat-sen University.Rlasmid pcDNA3.1-HCN4 containing target gene human HCN4,human embryo kidney 293 cells and Escherichia coll DH5α were preserved by our experimental center;Shuttle plasmid pShuttle-CMV containing green fluorescent protein gene and adenoviral backbone plasmid pAdxsi were bought from SinoGenoMax Co.,Ltd.METHODS:HCN4 cDNA segment was liberated from the cloning vector of pcDNA3.1-HCN4 via Hind Ⅲ+Xba Ⅰ,and subcloned into pShuttle-CMV,which was digested by I-Ceu Ⅰ +I-Sce Ⅰ double enzyme and subcloned into adenoviral plasmid to form recombinant adenovirus plasmid.Recombinant adenovirus plasmid was transfected into 293 cell lines by liposome,and the recombinant adenovirus AdHCN4 was packaged and transfected into rat MSCs.MAIN OUTCOME MEASURES:The identification of recombinant adenovirus plasmid vector,identification of recombinant adenovirus and its titration test;the transfection efficiency of recombinant adenovirus.RESULTS:Cloned sequence about 3.6kbp was obtained by Hind Ⅲ+Xho Ⅰ digestion after HCN4 cDNA segment was cloned into pShuttle-CMV.DNA sequencing results indicated that the clone location was correct.Recombinant adenovirus plasmid was cut into seven fragments while empty vector gained only six fragments after digested by Xho Ⅰ.The recombinant adenovirus was pathogenic to 293 cells after recombinant adenovirus plasmid was packaged in it.HCN4 cDNA (657bp) was amplified by PCR with virus titer of 2.5×10~(11) PFU/mL after transfected 293 cells with supematant.The efficiency of recombinant adenovirus infecting rat MSCs was about 90% when multiplicity of infection was 800.Rat MSCs expressed green fluorescence after transfection.CONCLUSION:The adenovirus vector with human HCN4 cDNA was established successfully,which can effectively transfect rat MSCs.
Résumé
Objective Implantable cardioverter defibrillator(ICD)can effectively treat lifethreatening ventricular arrhythmias.The most common side effect is inappropriate discharge.This study analyzes the incidence and causes of inappropriate discharges of ICD in our hospital.Methods Forty.threepatients implanted with ICD in our hospital from November 2001 to October 2007 were involved in our study.Patients were followed-up regularly.All episodes recorded and stored in the ICD were analyzed.Results Seven of the 43 patients underwent ninety-six inappropriate discharges.Inappropriate discharges in six patients were caused by supraventricular tachyarrhythmias(SVT).In one patient the discharge was caused by noise.Most inappropriate discharges occurred in the first year after implantation.The history of atrial fibrillation before implantation is an independent predictor of inappropriate discharges.Conclusions The incidence of inappropriate discharge is 16.3%in our study and the most common cause is SVT.Most inappropriate discharges occur in the first year after implantation.Patients with atrial fibrillation history have a higher risk of inappropriate discharges.
Résumé
AIM:To research the characteristics of ventricular electrophysiology in right ventricular rapid pacing-induced congestive heart failure (CHF) dogs. METHODS:Dogs (n = 16) were randomly divided into 2 groups:the control (n = 7) and the CHF group (n = 9) induced by rapid right ventricular pacing at 240 pulse·min-1 for 4 to 5 weeks. The electrophysiologic parameters were evaluated by the technique of standard electric stimulation and monophasic action potential (MAP) recording. RESULTS:(1) Ventricular effective refractory period (VERP), ventricular MAP duration (MAPD90), ventricular late repolarization duration (VLRD) and intra- ventricular conduction time (IVCT) were prolonged by 26％ (P ＜ 0. 01), 43％ (P ＜ 0. 01), 318％ (P ＜ 0. 05), and 19％ (P ＜ 0. 01), respectively in CHF group. (2)The ratio of VERP to MAPD90(VERP/MAPD90) was decreased by 13％ (P＜0.05) in CHF group. (3) The dispersion of ventricular recovery time (VRT - D) was increased by 185％ (P ＜0. 01) in CHF group. (4) The ventricular fibrillation threshold (VFT) was decreased by 48％ (P ＜ 0. 01) in CHF group. CONCLUSION:The abnormal electrophysiological changes in the CHF condition may be contributing factors of lethal ventricular arrhythmias and sudden cardiac deaths in CHF.
Résumé
AIM:To study the effects of FK506 binding protein 12.6(FKBP12.6) overexpression on the performance of sarcoplasmic reticulum(SR) in ventricular myocytes of rats with heart failure.METHODS:The adenovirus(Ad)-mediated gene transfer was used to overexpress FKBP12.6 in ventricular myocytes of rats with heart failure.Western blotting and reverse transcriptase-polymerase chain reaction(RT-PCR) analysis were used to reveale specific overexpression of FKBP12.6.X-rhod-1-AM was used as the Ca2+ indicator,and cells were viewed under a confocal microscope.RESULTS:Adenovirus mediated overexpression of FKBP12.6 resulted in a 5-fold increase in relative FKBP12.6 mRNA levels and a 4-fold increase in relative FKBP12.6 protein levels at 48 h after transfection compared with control.The amplitude of the fluorescence [Ca2+]i transient was significantly increased in Ad-FKBP12.6-GFP cardiomyocytes compared with Ad-GFP myocytes(peak F/F0,3.16?0.42 vs 1.43?0.38,P