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 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 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 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 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.

Aim To study the effects of telmisartan upon serum calcineurin.Methods 92 male SD rats with the same age were randomly divided into control group (N), sham operation group (S), 2K1C+distilled water group (K) and 2K1C+telmisartan group (T).S rats were performed the open-abdomen surgery without being restricted any renal artery, but the K and the T rats were restricted their left renal artery. Beginning from the third week after the surgery, the K rats started to be treated with the intragastric infusion of distilled water 10 ml·(kg·d)~(-1) , while the T rats with telmisartan 10 mg·(kg·d)~(-1) .And after being treated for 2, 4 and 8 weeks, rats were respectively measured the systolic blood pressure (SBP), the diastolic blood pressure (DBP) of the abdominal aorta. Before and after the operation, ultrasonography with probe of 7.5 MHz was used to obtain the structure and functional indexes, such as IVSd, IVSs, LVPWd, and serum calcineurin were evaluated by ELISA and colorimetric assay kit.Result Compared with the S group and the N group, ① the results of blood pressure (SBP, DBP) were significantly higher in K group (all P <0.01), after use of telmisartan, blood pressure was significantly reduced(P <0.01);② the thickness of interventricular septal and left ventricular posterior wall at the end of diastolic and systolic were significantly higher in K group (all P <0.01), after use of telmisartan, the thickness of those declined(all P <0.01);③ the level and activity of serum calcineurin were significantly higher in K group (all P <0.01), after use of telmisartan, the level and activity of calcineurin significantly fell(P <0.01).Conclusion The serum calcineurin of artery was also raised in the left ventricular remodeling. Telmisartan ameliorates ventricular remodeling effectively, which may be associated with decreasing the expression of artery serum calcineurin.

Objective To evaluate the immediate impact of radiofrequencycatheter ablation on left atrial (LA)volumes and function by velocity vector imaging(ⅤⅥ)and compare the LA function with and without atrial fibrillation after the operation.Methods Ten consecutive patients with paroxysmal AF were studied at baseline and within 3 days after ablation.Ten consecutive patients with persistent AF were studied within 3 days after ablation,in sinus rhythm.Ten patients with normal ventricular function were included in the study.ⅤⅥ was performed to assess LA sizes and strain,strain rate,velocity of the septum,lateral wall and the atrial roof from the apical four-chamber view.Results In patients with paroxysmal AF,global and regioal LA function was not significantly impaired after the ablation procedure.Subgroup analysis demonstrated that there were no significant difference in LA function betwwen patients with paroxysmal AF and control subjects,but the indexed LAVmax was significantly larger in all AF patients compared with control subjects.The global function of LA,including LAEF,LAaEF and LA expansion index significantly decreased in persistent AF patients.By contrast,the LA septal strain,velocity and lateral strain were lower than controls.Conclusions Radiofrequency catheter ablation has no influence on LA function assessed by ⅤⅥ within three days after the operation for patients with paroxysmaI AF.The function of persistent AF patients is absolutely lower than control subjects.

Objective To appraise the clinical value of velocity vector imaging(VVI) by analyzing the peak systolic velocities,strain and strain rate of ventricular segments in patients with DDD pacing. Methods eventeen patients with DDD pacing were enrolled in this study. The peak systolic velocities, strain andstrain rate of ventricular segments were measured with VVI. The difference at baseline and after pacemaker implantation was analyzed. Results Left and right ventricular (LV and RV) longitudinal peak velocities at baseline and after DDD pacing were significantly decreasing from basal, mid to apical segments. But no significant difference was found in longitudinal strain,strain rate and radial motion characteristic of LV. The mean systolic velocities and strain rate at baseline and after pacemaker implantation and strain with pacing of RV posterior septum and free wall were higher than those of posterior septum and lateral segment of LV respectively. The mean strain and strain rate of RV after pacing were higher than that of LV. Compared with the values at baseline, mean strain of LV with pacing was lower significantly. Conclusions VVI can accurately assess ventricular systolic function in patients with DDD pacing, and can become a powerful means in assessing the regional myocardial function.