The impact of rapid atrial pacing on ADMA and endothelial NOS

Background

The endothelial nitric oxide synthase (eNOS) inhibitor asymmetric dimethylarginine (ADMA) is a well-established risk factor for oxidative stress, vascular dysfunction, and congestive heart failure. The aim of the present study was to determine the impact of rapid atrial pacing (RAP) on ADMA levels and eNOS expression.

Methods and results

ADMA levels were studied in 60 age- and gender-matched patients. Thirty five patients had persistent atrial fibrillation (AF) ≥ 4 months. In AF-patients, parameters were studied before and 24 h after electrical cardioversion. Moreover, ADMA, eNOS expression, and calcium-handling proteins were studied in pigs subjected to RAP as well as in endothelial cell (EC) cultures. ADMA level was significantly higher in AF compared to sinus rhythm patients (p = 0.024). ADMA was highest in AF-patients, who also showed elevated troponin T (TnT) levels. Moreover, ADMA showed a significant linear correlation to TnT (r = 0.47; p < 0.01). After electrical cardioversion ADMA returned to normal within 24 h. In pigs, RAP for 7 h increased ADMA levels (p = 0.018) and TnI (p < 0.05), and reduced mRNA expression of ventricular and aortic eNOS (− 80%; p < 0.05) compared to sham-control. However, ADMA per se did not affect eNOS mRNA level in EC cultures.

Conclusion

The current study shows that acute and persistent episodes of atrial tachyarrhythmia are associated with elevated ADMA levels accompanied by increased ischemic myocardial markers. Moreover, RAP increases ADMA and down-regulates eNOS expression in an ADMA-independent manner. We conclude that the combination of these two separate and potentially synergistic mechanisms may contribute to long-term vascular injury during atrial tachyarrhythmia.     

最小化心室起搏对阵发性心房颤动的影响

目的观察最小化心室起搏在阵发性心房颤动患者中能否减少心室起搏及房颤发作。方法选择房颤负荷在1%～70%,已植入具有最小化心室起搏功能起搏器的46例患者为研究对象。经过1个月诱导期后,利用EXCEL表格中的随机函数算法随机分为A组(最小化心室起搏功能关闭)和B组(最小化心室起搏功能打开),观察6个月。主要观察指标为心室起搏比率及房颤负荷。结果观察6个月两组之间的房颤负荷,A组为31.9%,B组为7.5%。心室起搏中位数A组显著高于B组,A组为76.0%,B组为2.1%。结论应用最小化心室起搏能显著减少心室起搏比例和房颤发作。     

心理语言、穴位刺激和胃电起搏协同改善功能性消化不良的胃感觉功能

目的研究心理语言、穴位刺激、胃电起搏协同治疗方法(Coordinated Treatment of Psychological language,Acupuncture pointstimulation and Gastric pacing,CTPAG)治疗难治性功能性消化不良的临床疗效及可能机制。方法根据罗马Ⅲ标准选取80例难治性功能性消化不良患者,随机分为两组:口服药物组(n=38)和CTPAG组(n=42),比较两组受试者在症状评分、临床疗效、胃感觉功能中的差异。结果与口服药物组比较,CTPAG组中临床症状评分明显下降,疗效显著率明显升高;胃的初次饱足阈值和最大耐受阈值均明显增加,差异具有统计学意义(P<0.05)。结论心理语言、穴位刺激和胃电起搏协同治疗(CTPAG)可能通过增加胃的可耐受容积,降低内脏敏感性,达到改善早饱、腹胀、进食少等疗效;并且CTPAG组优于常规口服药物组,是难治性FD非药物治疗的一种新选择。     

室间隔起搏损伤电流的临床应用研究

目的 探讨损伤电流(COI)与主动固定导线稳定性关系,为临床判断主动固定导线植入室间隔的可靠性和安全性提供依据.方法 入选按常规方法将主动固定导线植入右心室间隔患者193例,在导线螺旋旋出即刻测试COI,同时进行起搏参数测试.结果 按测得COI值分别为＜5 mV、5 ～10 mV、＞10 mV 3组,COI＜5 mV组平均(3.85±1.01) mV,COI 5～10 mV组平均(7.74±1.63) mV,COI＞10 mV组平均(10.63±0.55)mV.COI＜5 mV组阈值为(0.83±0.16)V,高于COI＞ 10 mV组阈值(0.69±0.15) V(P＜ 0.05),其余组间差异无统计学意义.COI＜5 mV组发生心室导线脱位2例,COI表现为“顶天立地”的发生心室导线穿孔1例.并发症的发生率为1.55％.结论 在室间隔起搏主动固定导线植入术中应测试COI,测得COI应至少在5 mV以上,但COI过大将增加导线穿孔的风险.     

超速起搏预适应的延迟保护作用与环氧化酶2表达的关系

目的观察在超速心室起搏(VOP)预适应延迟保护阶段环氧化酶2(COX-2)的表达水平,从而探讨预适应延迟保护作用机制与COX-2的关系。方法健康的新西兰雄兔24只,随机分为3组,单纯结扎组、起搏组、起搏+放线菌素D组,每组8只,制作超速起搏预适应和缺血/再灌注动物模型,检测肌酸激酶(CK)、CK同工酶(CK-MB)的变化,动态描记再灌注时心电图变化,免疫组化染色检测COX-2抗原。结果缺血后起搏组CK、CK-MB的水平[(1492±474)IU/L和(614±182)IU/L]在再灌注时低于单纯结扎组[(2625±423)IU/L和(1332±178)IU/L]及起搏+放线菌素D组[(2071±390)IU/L和(1095±183)IU/L](P<0.01);单纯结扎组再灌注过程中共有5只(62.5%)发生心律失常,起搏+放线菌素D组也有4只(50%),而起搏组中无心律失常发生,起搏组和单纯结扎组中之间差异具有统计学意义(P<0.05),起搏组中COX-2的阳性表达程度明显高于其他两组。结论超速起搏预适应可以模拟缺血预适应,其延迟保护作用可能与COX-2的表达增加密切相关。     

Atrial Support Pacing in Heart Failure: Results from the Multicenter PEGASUS CRT Trial

Atrial Pacing in Heart Failure. Introduction: Cardiac resynchronization therapy (CRT) efficacy trials to date used atrial‐synchronous biventricular pacing wherein there is no or minimal atrial pacing. However, bradycardia and chronotropic incompetence are common in this patient population. This trial was designed to evaluate the effect of atrial support pacing among heart failure patients receiving a CRT defibrillator. Methods and Results: PEGASUS CRT was a multicenter, 3‐arm, randomized study. At 6 weeks, patients were randomized to DDD mode at a lower rate of 40 bpm (DDD‐40; control arm), or one of the following 2 treatment arms: DDD‐70, or DDDR‐40. The primary endpoint was a clinical composite endpoint that included all‐cause mortality, heart failure events, NYHA functional class, and patient global self‐assessment. Subjects were classified as improved, unchanged, or worsened at 12 months. There were 1,433 patients randomized, of whom 66% were male, mean age was 67 ± 11 years, and mean left ventricular ejection fraction was 23 ± 7%. The average follow‐up time was 10.5 ± 3.5 months and 1,309 patients contributed to the primary endpoint. No significant differences were observed in the composite endpoint between either of the 2 treatment arms compared to the control arm (P>0.05 for both comparisons). Additionally, there were no differences among the groups in mortality or heart failure events. Conclusion: In advanced heart failure patients treated with CRT, atrial support pacing did not improve clinical outcomes compared to atrial tracking. However, atrial pacing did not adversely affect mortality or heart failure events. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1317‐1325, December 2012)     

A Randomized Study of Defibrillator Lead Implantations in the Right Ventricular Mid-Septum versus the Apex: The SEPTAL Study(τ)

Impact of Recalls on ICD Utilization . Introduction: The study was designed to evaluate the feasibility and performance of right ventricular (RV) mid‐septal versus apical implantable defibrillator (ICD) lead placement. Methods and Results: SEPTAL is a randomized, noninferiority trial, which randomly assigned patients to implantation of ICD leads in the RV mid‐septum versus apex, with a primary objective of comparing the implant success rate of implant at each site, based on strict electrical predefined criteria. We also compared the (1) pacing lead characteristics, (2) rates of appropriate and inappropriate ICD therapies, and (3) all‐cause mortality between the 2 sites at 1 year. The trial enrolled 215 patients (mean age = 59.7 ± 12.4 years, mean LVEF = 34.0 ± 14.2%, 84.2% men), of whom 148 (68.8%) presented with ischemic heart disease. The ICD indication was primary prevention in 117 patients (54.4%). The lead was successfully implanted in 96/107 patients (89.7%) assigned to the RV mid‐septum, and in 99/108 (91.7%) assigned to the apex (ns). The 1‐year rate of lead‐related adverse events was similar in both groups. A total of 8 first inappropriate ICD therapies (7.9%) were delivered in the RV mid‐septal group, versus 8 (7.8%) in the apical group (ns), while first appropriate therapies were delivered to 22 (21.4%) and 24 patients (23.8%), respectively (ns). All‐cause mortality was 7.9% in the RV mid‐septal versus 2.9% in the RV apical group (ns). Conclusion: This study confirmed the technical feasibility and noninferior performance of ICD leads implanted in the RV mid‐septum versus the apex. (J Cardiovasc Electrophysiol, Vol. 23, pp. 853‐860, August 2012)