Administration of adenosine triphosphate or adenosine is an important clinical trial in diagnosis and treatment of arrhythmias. It may not only terminate the paroxysmal supraventricular tachycardia and the specific type of ventricular tachycardia, but also identify the mechanism of majority of arrhythmias. Otherwise, It is also a useful diagnostic test for sick sinus sydrome and a reliable methos to assess radiofrequency catheter ablation.

Objective To describe the new cognition of mapping, ablation and mechanism of typical atrial flutter using non-contact mapping system. Methods In 9 patients with typital AFL, the bi-directional conduction properties of isthmus, atrial activation sequence and reentrant circuit of AFL were mapped using the non-contact mapping system. Linear isthmus radiofrequency ablation was guided by navigation system without fluoroscopy, and isthmus bi-directional block was verified. Results A clockwise moving reentrant activation wavefront in 1 of the 9 patients was observed and a counter-clockwise rotating wavefront in 7 of the 9 patients, respectively. AFL was not inducible in one patient. The mean cycle length of AFL was (215?36) ms. The whole reentrant way and its relation with anatomical structure of right atrium (RA) were displayed by non-contact mapping. In each mapped AFL, the wavefront conducted through the crista terminalis (CT) and propagated slowly, which that indicated the smooth part of RA was involved in the reentrant circuit. In patients with recurrences, the gap in the line of block in the isthmus was identified and ablated, which was navigated by the system. Complete isthmus bi-directional conduction block was achieved at the end of the procedure except in two patients. No recurrences of AFL occurred during the follow-up of 12-36 months. Conclusion The whole activation circuit and its relation with RA anatomical structure of typical AFL can be directly visualized and its reentry mechanism was verified by non-contact mapping system. In recurred cases ,the gap of isthmus block was identified and ablated accurately. CT, which was previously supposed to be a complete posterior conduction barrier, was now proved to be of transverse slow conduction by non-contact mapping.

Objective To evaluate the effectiveness and safety of transcatheter closure of membranous ventricular septal defect (MVSD) using Amplatzer membranous VSD occluder (AMVSO). Methods The patients, who were clinically diagnosed with VSD were recommended for further transthoracic echocardiographic assessment using multiple standard views. If there were left to right shunts across ventricular septum, the margin of defects to the aortic valve was more than 1mm and that to tricuspid valve was more than 3 mm. If there was an aneurysm, it should not interfere with the function of outlet of right ventricule. Finally, if the diameter of VSDs wasless than 14mm, catheter closure of VSDs was suggested in these patients. The patients, having residual shunt after surgical closure of VSD, were included. All procedures were performed under local or general anesthesia. Transthorac echocardiography and X ray were used continuously to monitor the procedure. Transthoracic echocardiography was performed immediately after the release of devices, 24 hours, and 3 months after the procedure, respectively.Results From June 2002 to March 2003, 32 consecutive patients (15 females), underwent transcatheter closure of MVSD. The mean diameters of VSDs measured by echocardiography was 5.1 mm (3～8 mm) and, while that by angiography was 4.4 mm (3～8 mm). The mean size of the occluder was 7.6 mm(4～12 mm). The successful rate of device implantation was 100% (32/32). The residual shunt immediately after the closure was 11.5%, whereas after 24 hours it was only 7.7%, which was not serious. After 3 months′ follow-up, only 3.8% trivial residual shunt existed. No death occurred during and after the procedure. Atrial tachycardia, ventricular tachycardia, and bundle (right and left bundle) branch block, which was considered to relate to catheter manipulation inside the chamber of ventricle, were common and transient. One aortic regurgitation and tricuspid insufficiency became severe after the procedure, but they were not serious. One patient developed III degree A-V block 24 hours after the procedure, and EKG became LBBB 3 days after the temporary pace making. Hemolysis was observed in one patient, and he recovered 7days after the medication therapy. Conclusion Transthoracic echocardiography was very much effective in catheter closure of MVSD. The asymmetric self-expanding nitinol double-disc Amplatzer device designed for the transcatheter closure of MVSD is implanted easily and stably. Due to low ratio of residual shunt and few serious complications, the Amplatzer device is a good choice for the transcatheter closure of MVSD.

Objective To explore and develop a close-chest animal model of acute myocardial infarction (AMI) with left ventricular aneurysm. Methods After anesthesia, 2.0 mm or 2.5 mm angioplasty balloon was positioned in the mid-LAD distal to the first diagnonal branch. The balloon was inflated and occluded the LAD for 150 minutes. ECG and blood pressure were monitored. UCG, cTnI and coronary angiography were also investigated to confirm AMI and the aneurysm. Results Five of seven pigs underwent successful induction of AMI and aneurysm. Two of seven pigs died of ventricular fibrillation. The dynamic changes of ECG and cTnI further confirmed AMI. Regional wall-motion abnormalities were found by two-dimensional echocardiography one hour after AMI and left ventricular aneurysm two weeks later in all pigs. Conclusion A closed-chest pig model of aneurysm after AMI is feasible and has a relatively high induction rate and a low mortality.

Objective To discuss the hemodynamics and treatment of silent patent ductus arteriosus (PDA) Methods The heart catheterizations were performed in seven silent PDA patients Results The mean pulmonary artery pressure of seven patients was (16?2 4) mm?Hg The mean Qp/Qs was 1 08?0 02 The mean size of the left right shunt was (0 32?0 08) L/min The proportion of left right shunt size in pulmonary blood flow was 0 098?0 024 on average The mean PDA at its narrowest segment was (0 9?0 2) mm We performed neither surgery nor interventional treatment in all patients In 9 5 months follow up (clinical findings, electrocardiography, echocardiography), no atrioventricular chambers enlargement, pulmonary hypertension, infective endoarteritis and infective endocarditis happened Conclusion In silent PDA patients, there is less size of left right shunt and smaller effect on hemodynamics Its treatment with surgical and interventional closure is under discussion

Objective Previous investigations have shown that N-aeetylcysteine (NAC) could regulate diverse cell type's apoptosis. The purpose of this study was to evaluate the mechanism of NAC reversed apoptosis ofcardiomyocytes induced by hypoxia-reoxygenation (H/R). Methods Cardiomyocytes were treated with hypoxia 6 h and reoxygenation 72 h in the absence and presence of NAC (100 μmol/ L). The ROS was assayed by using Image-iTTM LIVE green reactive oxygen species detection kit. The viability of cell was assayed with trypan blue. Early stages ofapoptosis were assessed by flow cytometry using Annexin V, and late stages ofapoptosis were assessed using TUNEL system. Bcl2 and bax mRNA levels were determincd by real-time quantitative PCR. Bcl2, bax, p38 and pp38 protein levels were determined by western blot. Results We found that H/R could markedly increase ROS generation and induce the apoptosis of cardiomyocytes (P<0.01). NAC (100 p tool/L) significantly reduced the generation of ROS and apoptosis (P all <0.01). NAC also significantly reduced the protein ratio of pp38 and p38 and increased the RNA and protein ratio of bcl2 and bax (P all <0.01). Conclusion The results showed that NAC significantly reduced apoptosis through inhibiting the phosphorylation of p38 signal pathway, which has potential value for clinical cardiac diseases.

Objective To evaluate left ventricular(LV) systolic synchrony and sequence in patients with premature ventricular complexes(PVCs) from right ventricular outflow tract (RVOT).Methods Thirty patients with frequent isolated PVCs from RVOT and 30 healthy subjects as control were included.Speckle tracking imaging (STI) was performed to assess the time-to-peak segmental systolic strain in longit udinal(TsL), circumferential (TsC) and radial (TsR) direction.The standard deviation (SD) of TsL,TsC and TsR of 18 LV segments were calculated respectively.All values of patients with PVCs were recorded during sinus beats(PVC-S) and PVC beats(PVC-V) respectively.LV systolic sequence in PVC-V was analyzed.Results Significant differences were observed in the SD values between the PVC-V and control subjects in three directions,as well as between the PVC-S and control subjects in circumferential and radial direction.In PVC-V significance difference was seen in TsL and TsR from apical to basal level,as well as in TsL and TsC in different walls.Conclusions LV systolic synchrony was demonstrated in patients with PVCs from RVOT during both sinus beats and PVC beats.Systolic sequence in PVC beats from RVOT exhibit certain rules.

Objective Chronic atrial fibrillation (AF) results in dedifferentiation of atrial cardiomyocytes that plays an important role in the perpetuation of AF.In this study,we aimed to investigate the changes of titin and α-smooth muscle actin (α-SMA) after long time of AF reversal.Methods Twenty-four goats were randomized into four groups:(1) sinus rhythm (SR),(2) 3 months AF (3-mo AF),(3) 3 months SR after 3 months AF (3-mo post AF),(4) 6 months SR after 3-mo AF (6-mo post AF),with 6 in each group.By pacing on the anterior bottom of left atria appendage (LAA),we established a goat model of chronic AF.Atria effective refractory period (AERP) was measured with electrophysiological methods.Ultra-structure was studied with echocardiography,light and electron microscopy.Titin and α-SMA protein expressions were determined by Western blot.Results The animals underwent high rate pacing on LAA for a mean of 42.23±21.70 days before presenting AF.Electrophysiological analysis revealed that AERP completely resumed in 3-mo post AF goats.Echocardiography displayed that the size of left atrium resumed almost in 6-mo post AF goats (P＜ 0.01).Pathological and electron microscopic examination revealed the disorder of myofibrils,augmentation of intercellular space,myolysis,accumulation of glycogen,and numerous bigger mitochondria among atrial cardiomyocytes in 3-mo AF goats.They recovered mostly in 6-mo post AF goats.Western blot showed that the band density of titin significantly reduced in 3-mo AF goats compared to SR ones [1826±319 vs 5012±854,P＜0.01].In 3-and 6-mo post AF goats,titin increased gradually and it reversed completely in 6-mo post AF goats (3841±601 and 4523±833 respectively,P ＜ 0.01).Conversely,the band density of α-SMA was significantly higher in 3-mo AF goats (5324±948) than in SR ones (1619± 271,P＜0.01).In 3-and 6-mo post-AF goats,α-SMA decreased gradually,and it recovered mostly in 6mo post AF goats (4437± 792 and 2205±540 respectively,P＜0.01,).Conclusions These data indicate that the reversal of dedifferentiation of atrial cardiomyocyts is a very slow process,and it is definitely essential for normal cardiac function.

OBJECTIVETo observe the long-term outcome of implantable cardioverter-defibrillator (ICD) implantation in Brugada syndrome patients and to explore how to reduce the frequency of ICD nappropriate schocks.

METHODSThis study included 14 symptomatic patients (mean age (44.3 ± 8.3) years old; all males) with Brugada syndrome implanted with ICD in our hospital between 1998 and 2012, and these patients were followed up routinely every 6 months. The initial ICD parameters were set according o conventional experience. The ventricular tachycardia (VT) zone was programmed to ventricular rate 150-188 bpm/cycle length (CL) 400-320 ms and the ventricular fibrillation (VF) zone was programmed to ventricular rate ≥ 188 bpm/CL ≤ 320 ms. The total events were recorded by ICD. The ICD parameters revision was made by electrophysiological (EP) experts in case of inappropriate shocks.

RESULTSPatients were followed up for mean (43.0 ± 28.3) months. A total of 297 VF/VT events were recorded by ICD. Electrophysiological experts found that 90% (178/198) episodes were true VF ( CL 130-250 ms) among of 198 VF episodes and 147 VF episodes were terminated by one shock and 21 VF events were terminated by two or more shocks, and the rest 10 VF terminated spontaneously. Only 9% (9/99) VT events were true VT (CL 320-360 ms) among of 99 VT episodes. Eight VT episodes were converted by antitachycardia pacing therapy (ATP) and the other one terminated spontaneously. The rest 90 VT episodes (91%) were supraventricular arrhythmias (SVT, CL 340-390 ms). About 90% inappropriate shocks can be reduced by Wavelet discrimination function and optimal programming (VF zone ventricular rate ≥ 222 bpm/CL ≤ 270 ms and/or VT zone ventricular rate 167-222 bpm/CL 270-360 ms ) according to the characteristics of arrhythmia of individual patient.

CONCLUSIONICD can effectively prevent sudden cardiac death and syncope in high-risk patients with Brugada syndrome. The most common complication is inappropriate shock due to SVT. Optimal ICD programming with Wavelet discrimination function can effectively reduce the frequency of inappropriate shock rate.

Adult ; Brugada Syndrome ; Cardiac Conduction System Disease ; Death, Sudden, Cardiac ; Defibrillators, Implantable ; Humans ; Male ; Syncope ; Tachycardia, Ventricular ; Treatment Outcome ; Ventricular Fibrillation

Objective To assess left ventricular(LV)twisting parameters in different layers with velocity vector imaging(VVI)in both healthy subjects and premature ventricular contraction(PVC)bigeminy from right ventricle(RV)patients,and investigate the rules of LV myocardium dynamics in sinus rhythm and PVC from RV.Methods Ten patients with PVC bigeminy from RV and twelve healthy subj ects underwent the examination of two-dimensional ultrasound,in which the standard LV mitral valve(MV)and apical short-axis views were acquired.The twisting angle(TA)and untwisting starting time(UST)were measured.Results In healthy subjects myocardium of LV MV short-axis twisted in clockwise,while the myocardium of LV apical short-axis twisted in counter-clockwise.TA of endocardium was higher than that of epieardium(P＜0.01).In PVC bigeminy from RA patients,their TA during sinus contraction was lower than that of healthy subjects both in MV and apical short axis respectively(P＜0.05),and UST was earlier(P＜0.05).In PVC the TA curve is bidirectional.and in early systolic TA twisted reversely compared with that of healthy subjects and sinus contraction in PVC patients.Conclusions Twisting parameters could be used to assess myocardium dynamics during different ventricular mechanical activation.VVl was a novel tool to analyze myocardium twisting.