Prevention of paroxysmal atrial fibrillation in patients with sinus bradycardia: role of right atrial linear ablation and pacing site

INTRODUCTION: Right atrial linear lesions (RALL), either alone or in combination with antiarrhythmic drug therapy, may modify the substrate for maintenance of atrial fibrillation (AF). The aim of this prospective randomized study was to determine whether RALL provides additional benefit to right atrial appendage pacing (RAAP) and/or interatrial septum pacing (IASP) and drug therapy in patients with symptomatic paroxysmal AF and sinus bradycardia requiring permanent atrial pacing. METHODS AND RESULTS: Sixty-four patients (33 men and 31 women, mean age 73 +/- 10 years) completed the 6-month follow-up. Patients were randomized to either RALL (n = 33) or non-right atrial linear lesions (NRALL), and then to either IASP (n = 32) or RAAP (n = 32). Fifteen RALL patients were paced at the IAS and 18 at the RAA. Seventeen NRALL patients were paced at the IAS and 14 at the RAA. No statistical difference was observed with regard to the mean atrial tachyarrhythmia (AT) burden between NRALL (84 +/- 169 min/day) and RALL patients (202 +/- 219 min/day). Mean AT burden was significantly lower in the IASP group (70 +/- 150 min/day) than in RAAP group (219 +/- 317 min/day; P < 0.016). In the RALL group, the mean AT burden was 99 +/- 180 min/day in the IASP patients and 288 +/- 372 min/day in the RAAP patients (P < 0.046). In the NRALL group, no statistical difference in the mean AT burden was observed between IASP patients (46 +/- 117 min/day) and RAAP patients (130 +/- 211 min/day). CONCLUSION: The results of the present study indicate that RALL did not provide any additional therapeutic benefit to combined antiarrhythmic drug therapy and septal or nonseptal atrial pacing in patients with sinus bradycardia and paroxysmal AF.     

Right atrial preventive and antitachycardia pacing for prevention of paroxysmal atrial fibrillation in patients without bradycardia: a randomized study.

AIMS: To investigate the efficacy of preventive and antitachycardia pacing (ATP) in patients with symptomatic paroxysmal atrial fibrillation (AF) without bradyarrhythmias. METHODS AND RESULTS: In this randomized cross-over pilot study, we randomized 38 symptomatic paroxysmal AF patients 'without' bradyarrhythmias to atrial pacing lower rate 70 ppm and prevention and ATP therapies ON or to atrial pacing lower rate 34 ppm and prevention and ATP therapies OFF during 12 weeks with a 4 week washout period in between. The atrial lead was preferably placed in the inter-atrial septum. Antiarrhythmic drugs were continued during the study. Primary endpoint was AF burden. Mean age was 62 +/- 9 years and 27 (71%) patients had lone AF. Septal lead placement was accomplished in 26 (68%) patients. During the treatment ON, there was a trend for AF burden reduction [from median 3.3% (1.0-15.2) to 2.4% (0.2-12.2), P = 0.06, reduction 27%]. If septal lead placement was accomplished, AF burden reduction was statistically significant [44% reduction, from median 2.5% (1.0-8.0) to 1.4% (0.2-8.4), P = 0.03]. Quality of life and symptoms did not change, also not in the septal group. CONCLUSION: A hybrid therapy of preventive and ATP pacing and antiarrhythmic drugs may significantly reduce but not abolish AF burden if septal pacing is realized.     

Combined efficacy of atrial septal lead placement and atrial pacing algorithms for prevention of paroxysmal atrial tachyarrhythmia

INTRODUCTION: The combined role of atrial septal lead location and atrial pacing algorithms in the prevention of atrial tachyarrhythmias (AT/AF), including both atrial fibrillation and flutter, is unknown. We tested the hypothesis that atrial prevention pacing algorithms could decrease AT/AF frequency in patients with atrial septal leads, bradycardia, and paroxysmal AT/AF. METHODS AND RESULTS: A total of 298 patients (age 70 +/- 10 years; 61% male) from 35 centers were implanted with a DDDRP pacing system including three AT/AF prevention pacing algorithms. Lead site was randomized at implant to right atrial septal or nonseptal. Patients were randomized 1 month postimplant to AT/AF prevention ON or OFF for 3 months and then crossed over for 3 months. Patients logged symptomatic AT/AF episodes via a manual activator. Prevention efficacy was evaluated based on intention-to-treat in 277 patients (138 septal) with complete follow-up. No changes in device-recorded AT/AF frequency or burden were observed with algorithms OFF versus ON or between patients randomized to septal versus nonseptal lead location. Analysis of other secondary outcomes revealed that AT/AF prevention pacing resulted in decreased atrial premature contractions in both the septal (1.9 [0.2-8.7] vs 3.3 [0.3-10.6]x 103/day; P < 0.01) and nonseptal groups (0.9 [0.2-3.3] vs 1.3 [0.3-5.5]x 103/day; P < 0.001). Patients with septal leads had fewer symptomatic AT/AF episodes ON versus OFF (1.4 +/- 3.0 vs 2.5 +/- 5.2/month, P = 0.01). CONCLUSION: The combination of three atrial prevention pacing algorithms did not decrease device classified atrial tachyarrhythmia frequency or burden during a 3-month cross-over period in bradycardic patients and septal or nonseptal atrial pacing leads. Prevention pacing was associated with decreased frequency of premature atrial contractions and with decreased symptomatic atrial tachyarrhythmia frequency in patients with atrial septal leads.     

Atrial arrhythmia suppression by atrial overdrive pacing: pacemaker Holter assessment.

The purpose of this study was to assess the efficacy of overdrive, single-site right atrial appendage pacing to reduce the burden of atrial fibrillation (AF) when compared with a standard lower rate limit of 60 bpm. This was verified by using the pacemaker's Holter. Eighteen subjects with a pre-implant history of paroxysmal AF and implanted DDDR mode-switching pacemakers were recruited. The pacemaker lower rate limit was programmed in random order to 60, 75 or 90 bpm for three 2-month periods and the amount of AF quantified. In addition, the exercise tolerance (ET), general well being (GWB), functional capacity (FC) and specific symptom prevalence (SSP) were assessed. The main finding of the study was that when ranked according to the amount of AF, there was no significant difference in the amount of AF according to the pacing rate. Six patients failed to tolerate pacing at 90 bpm. There were no differences in the ET, GWB, FC and SSP scores. It is concluded that those clinicians that manage patients with paroxysmal     

Pacemaker prevention therapies for the control of drug-refractory paroxysmal atrial fibrillation.

AIMS: Atrial septal pacing has been shown to prevent paroxysmal atrial fibrillation (PAF) refractory to drugs in patients without inappropriate bradycardia. This study assesses the effects of atrial septal pacing using new pacing algorithms designed to prevent the initiation or maintenance of PAF. METHODS AND RESULTS: Eleven Medtronic AT500 and 6 Guidant Pulsar Max pacemakers were implanted. The incremental benefit of prevention pacing therapies was compared with DDDR pacing by analysis of pacemaker-stored electrograms, ambulatory electrocardiography, symptoms and quality of life questionnaires. RESULTS: Atrial septal pacing reduced AF burden by >50% in 13/17 patients (76.5%). Activation of a combined pacing algorithm (atrial pacing preference; atrial rate stabilization; and post mode-switch overdrive pacing) in patients with AT500 pacemakers produced a marginal reduction in AF burden (mean %AF 0.61 ON, 0.73 OFF, P=0.53 ns). Conversely in the Pulsar Max group when atrial pacing preference was activated, AF burden was slightly increased (mean %AF 5.84 ON, 3.73 OFF,P =0.13). Symptoms improved with atrial septal pacing but did not change when prevention algorithms were activated. CONCLUSION: Atrial septal pacing resulted in a marked improvement in AF burden and symptoms. Activation of specific prevention pacing algorithms provided more continuous atrial pacing but had limited and heterogeneous effects on AF burden.     

Increased base rate of atrial pacing for prevention of atrial fibrillation after implantation of a dual-chamber pacemaker: insights from the Atrial Overdrive Pacing Study.

AIMS: Different pacing sites and various algorithms have been utilized to prevent atrial fibrillation (AF) in pacemaker recipients. However, the optimal pacing rate settings have not yet been established. In this randomized, prospective, multicentre, single-blinded, cross over study, rate-adaptive pacing at a high base rate (BR) in patients, age 60 years or above, or a history of paroxysmal AF, who underwent dual-chamber (DDD) pacemaker implantation for standard pacing indications, was evaluated for prevention of AF. METHODS AND RESULTS: In the study cohort of 145 patients implanted with DDD pacemakers with a programmable rest rate (RR) feature, the BR/RR settings were sequentially but randomly adjusted as follows: 60 bpm/Off for the baseline quarter (initial 3 months) and then to either 'A-B-C' or 'C-B-A' settings (A = 70/65 bpm, B = 70/Off, C = 80/65 bpm) for the subsequent quarters each of 3 months duration. Data on automatic mode switch episodes, device diagnostics, and a questionnaire evaluating pacemaker awareness and palpitations were collected. Ninety-nine patients, mean age 77 +/- 10 years, who completed the study protocol and followed for 12 months did not show significant differences in the number of mode switch episodes between any settings used. The percentage of atrial pacing was lower during baseline pacing compared to settings A, B, and C (P < 0.0001). Setting C produced a higher percentage of atrial pacing than A and B (P < 0.01). Although a higher percentage of atrial pacing correlated with a lower incidence of mode switch episodes, there was no statistically significant difference in the number of mode switch episodes between settings A, B, and C. There were no significant differences in the questionnaire scores relating to pacemaker awareness or palpitation. CONCLUSION: Overdrive single-site pacing in the right atrium achieved by programming analysed settings in the present study did not reduce AF as assessed by mode switch episodes. Additionally, no change in the symptoms of arrhythmia or awareness of pacing was seen.     

No evidence of automatic atrial overdrive pacing efficacy on reduction of paroxysmal atrial fibrillation.

AIMS: Paroxysmal atrial fibrillation (PAF) is frequently encountered in pacemaker patients, most commonly in sick sinus syndrome. The combination of site-specific pacing in conjunction with an overdrive algorithm combined with antiarrhythmic drugs on the incidence of PAF in patients with a conventional indication for pacing is unknown. METHODS AND RESULTS: Patients with pacemaker indication and PAF received a DDDR-pacemaker, which included an automatic atrial overdrive (AO) algorithm. The atrial lead was implanted in either the right atrial appendage (RAA) (n = 83) or the right low-atrial septum (LAS) (n = 94). The algorithm was switched on or off in a 3 month, single blind crossover design and antiarrhythmic drugs were kept stable. A control group of 96 patients (LAS, n = 14; RAA, n = 84) without PAF served as controls to assess any proarrhythmic effect of overdrive pacing. Atrial fibrillation (AF) burden defined as cumulative time in mode switch was not reduced during automatic AO from either the RAA or from the LAS. The reduction was not effective both for AF of short (<24 h) and long (> or =24 h) duration. There was no atrial proarrhythmia induced by the overdrive algorithm in the control group. CONCLUSIONS: We could not demonstrate a reduction of AF burden defined as cumulative time in AF by the AO algorithm, in patients who are paced for standard indications and PAF, neither from the RAA nor from the LAS.     

Interatrial septum pacing: A new approach to prevent recurrent atrial fibrillation.

Background. There are a variety of approaches to the prevention of atrial fibrillation (AF) with pacing. Aim of this study was to test the safety and feasibility of interatrial septum pacing at the posterior triangle of Koch for AF prevention and to exclude potential arrhythmic effects.Matherial and Methods.Interatrial septum pacing was performed in 34 patients (21 males, 13 females, mean age 69±12 years): 9 without a history and clinical evidence of atrial fibrillation (AF) (6 with sinus bradycardia, 2 with second-degree AV block, and 1 with carotid sinus hypersensitivity) and 25 with sinus bradycardia and paroxysmal atrial fibrillation (PAF) (mean symptomatic episodes/month 6.2±10). In all patients a screw-in bipolar lead was positioned in the interatrial septum superiorly to the coronary sinus.Results.At implant the mean P wave amplitude was 2.5±1.5 mV, the pacing threshold was 1±0.6 V and the impedance was 907±477 Ohm. Mean P wave duration was 118±17 ms in sinus rhythm and 82±15 during interatrial septum pacing (p < 0.001). During a mean follow-up period of 10±7 months, no patients without atrial tachyarrhythmias before implantation experienced AF. During a 9±6 months follow-up we observed only 2 symptomatic arrhythmia recurrences between AF patients (mean symptomatic episodes/month 0.006±0.0022) (p < 0.01 vs before implant period).Conclusions. Our data indicate that interatrial septal pacing is safe and feasible. A significant less incidence of arrhythmic episodes has been observed during follow-up. Further controlled randomized prospective studies are necessary to establish the exact role of this technique respect to conventional or multisite stimulation when patients with paroxysmal AF need to be permanently paced.     

起搏术后心房颤动的影响因素及心房颤动与心钠素的关系

目的观察心脏起搏术后发生心房颤动(简称房颤)的影响因素及房颤与血心钠素(ANP)的关系。方法选择安装心脏起搏器的患者103例进行随访,分析房颤与年龄、起搏方式、心律失常类型、左房内径(LAD)、左室射血分数(LVEF)和血ANP的关系。结果①65岁以下患者房颤发生率低于65岁以上组(P<0.05)。②VVI组房颤发生率高于DDD组(P<0.05)。③慢快综合征组房颤发生率较缓慢型病窦综合征和房室传导阻滞组高(P<0.05)。④VVI房颤组术后LAD增大、LVEF下降(P<0.05),VVI房颤组术后与DDD组比较有差异(P<0.05)。⑤VVI房颤组和VVI窦性心律组ANP浓度较DDD组高(P<0.05);各组不同心功能级别(NYHA)之间ANP浓度随着心功能级别的加重而升高。结论长期心脏起搏术后房颤的发生可能与年龄大、VVI起搏、病窦综合征(慢快型)、LAD增大、LVEF降低及ANP浓度升高相关。     

Conventional and dedicated atrial overdrive pacing for the prevention of paroxysmal atrial fibrillation: the AFTherapy study.

AIMS: This investigation was conducted to determine the effectiveness of several conventional overdrive pacing modalities (single rate and rate responsive pacing at various lower rates) and of four dedicated preventive pacing algorithms in the suppression of paroxysmal atrial fibrillation (AF). METHOD AND RESULTS: In this multi-centre, randomized trial, 372 patients with drug-refractory paroxysmal AF were enrolled. Patients received a dual-chamber pacing device capable of delivering conventional pacing therapy as well as dedicated AF prevention pacing therapies and to record detailed AF-related diagnostics. The primary endpoint was AF burden, whereas secondary endpoints were time to first AF episode and averaged sinus rhythm duration. During a conventional pacing phase, patients were randomized to single rate or rate-responsive pacing with lower rates of either 70 or 85 min(-1) or to a control group with single rate pacing at 40 min(-1). In the subsequent preventive pacing phase, patients underwent pacing at a lower rate of 70 min(-1) with or without concomitant application of four preventive pacing algorithms. A substantial amount of data was excluded from the analysis because of atrial-sensing artefacts, identified in the device-captured diagnostics. In the conventional pacing phase, no significant differences were found between various lower rates and the control group receiving single rate pacing at 40 min(-1) or between single rate and rate-responsive pacing. Patients receiving preventive pacing with all four therapies enabled had a similar AF burden compared with patients treated with conventional pacing at 70 min(-1) (P = 0.47). CONCLUSIONS: The results do not demonstrate a significant effect of conventional atrial overdrive pacing or preventive pacing therapies. However, the observations provided important information for further consideration with respect to the design and conduct of future studies on the effect of atrial pacing therapies for the reduction of AF.     

Novel electrophysiologic parameter of dispersion of atrial repolarization: comparison of different atrial pacing methods

INTRODUCTION: Heterogeneity of ventricular repolarization plays a major role in reentrant tachyarrhythmias in cardiac tissue. However, the role of atrial repolarization added activation time (AT) to refractoriness in atrial vulnerability has not been investigated in detail. METHODS AND RESULTS: The study population consisted of 34 patients: 18 with atrial fibrillation (AF) and 16 without AF (control group). The effective refractory periods (ERPs) in the right atrial appendage, low lateral right atrium, high right septum, and distal coronary sinus, and ATs from P wave onset to each electrogram during sinus rhythm and right atrial appendage, low lateral right atrial, high right septal, distal coronary sinus, and biatrial pacing were measured. Atrial recovery time, defined as the sum of AT and ERP, and its dispersions during sinus rhythm, right atrial appendage, low lateral right atrial, high right septal, distal coronary sinus, and biatrial pacing were calculated. Both ERP dispersion and atrial recovery time dispersion during sinus rhythm were significantly greater in the AF group than in the control group. Atrial recovery time dispersion during distal coronary sinus, high right septal, or biatrial pacing was significantly smaller than that during right atrial appendage or low lateral right atrial pacing in each group. In particular, atrial recovery time dispersion during distal coronary sinus pacing was the smallest of the five pacing methods in the AF group. P wave duration during biatrial or high right septal pacing was significantly shorter than during right atrial appendage, low lateral right atrial, or distal coronary sinus pacing in each group. CONCLUSION: Atrial recovery time dispersion is suitable as an electrophysiologic parameter of atrial vulnerability. Distal coronary sinus pacing may prevent AF by increasing homogeneity of atrial repolarization, whereas biatrial and high right septal pacing contribute not only homogeneity of atrial repolarization but also improvement of atrial depolarization.     

Dual-site atrial pacing for atrial fibrillation in patients without bradycardia.

Atrial pacing has been shown to delay the onset of atrial fibrillation (AF) when compared with ventricular pacing in patients with sick sinus syndrome. The role for pacing in the control of AF in patients without bradycardia is uncertain. We performed a randomized, crossover, single-blinded study in 22 patients (14 women, aged 63 +/- 10 years) with paroxysmal AF refractory to treatment with oral sotalol (202 +/- 68 mg/day) and no bradycardic indication for pacing. All patients received a dual-chamber pacemaker with 2 atrial pacing leads positioned at the high right atrium and coronary sinus ostium, respectively. Patients were randomized in a crossover fashion to be paced for 12 weeks, either with high right atrial (RA) pacing at 30 beats/min ("Off") or dual-site RA pacing with an overdrive algorithm that maintained atrial pacing at a rate slightly above the sinus rate ("On"). Treatment on resulted in a significantly higher percentage of atrial pacing and a reduction in atrial ectopic frequency than the treatment off period. The time to the first clinical AF recurrence was prolonged (15 +/- 17 to 50 +/- 35 days, p = 0.006), and total AF burden was reduced (45 +/- 34% vs 22 +/- 29%, p = 0.04) in the on-treatment phase. However, there was no difference in AF checklist symptom scores or overall quality-of-life measures. Dual-site RA pacing with continued sinus overdrive prolonged the time to AF recurrence and decreased AF burden in patients with paroxysmal AF. The absence of a major impact on symptom control suggests that pacing should be used as an adjunctive therapy with other treatment modalities for AF.     

Effectiveness of rhythm control in persistent or permanent atrial fibrillation with overdrive atrial pacing and antiarrhythmic drugs after linear right atrial catheter ablation

Right atrial (RA) maze procedures using linear catheter ablation have had limited efficacy in paroxysmal atrial fibrillation (AF). We hypothesized that "hybrid" therapy using overdrive atrial pacing and antiarrhythmic drugs can improve efficacy of catheter RA maze and expand its role to persistent or permanent AF. Catheter RA maze procedures were performed in 26 patients with persistent or permanent AF refractory to 4.5 +/- 2.1 antiarrhythmic drugs. Overdrive dual-site RA pacing (21 patients) or high RA pacing (5 patients) was continued (n = 11) or instituted periablation (n = 15). All patients continued receiving previously ineffective antiarrhythmic drugs. Freedom from permanent AF (rhythm control), symptomatic and/or asymptomatic AF recurrences, the safety of hybrid therapy, and overall survival were assessed. There was no procedure-related mortality or stroke. Rhythm control was achieved in 24 patients (92%) within 3 months. During long-term follow-up (6 to 49 months, mean 17 +/- 10), rhythm control was maintained in 20 patients (77%). Nine patients (35%) had no AF recurrences, whereas 11 patients maintained rhythm control with infrequent AF recurrences. Device datalogs at the study cut-off point demonstrated no AF events in 6 patients, nonsustained atrial tachycardia in 2 patients, and brief asymptomatic paroxysmal AF in 12 patients. Actuarial patient survival was 95% at 1 year and 74% at 2 years of follow-up. Thus, hybrid therapy utilizing catheter RA maze procedures with overdrive atrial pacing and antiarrhythmic drugs can be performed safely and can reestablish rhythm control in selected patients with refractory persistent or permanent AF.     

Burden of atrial fibrillation after cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) may diminish atrial fibrillation (AF) burden in patients with chronic heart failure (HF). Each of 27 patients without permanent AF in whom CRT implantation was unsuccessful was paired with 2 active CRT patients-1 responder and 1 nonresponder-based on age, gender, cause of HF, and history of paroxysmal AF. Device-documented high atrial rates and mode-switching episodes were tabulated during a median follow-up of 386 days. CRT responders had significantly improved left ventricular (LV) ejection fraction and New York Heart Association functional class compared with nonresponders and controls. Left atrial dimension change was similar among the groups (+0.03 +/- 0.92 cm controls; -0.18 +/- 0.80 cm responders; -0.11 +/- 1.01 cm nonresponders) despite a significant reduction in mitral regurgitation in responders compared with nonresponders. There was no significant difference in AF burden between controls and patients who underewent CRT when indexed over time. Median AF-free follow-up was significantly longer in patients who underwent CRT without a history of AF (log-rank p = 0.04), but no differences were seen in the overall cohorts. In conclusion, despite inducing LV reverse remodeling and clinical improvement, CRT does not appear to decrease AF burden in responders compared with nonresponders or matched controls in whom CRT implantation failed. CRT may, however, delay onset of new AF.     

Evaluation of right atrial and biatrial temporary pacing for the prevention of atrial fibrillation after coronary artery bypass surgery

OBJECTIVES

The purpose of this study was to determine if atrial pacing is effective in reducing postoperative atrial fibrillation (AF).

BACKGROUND

Atrial fibrillation after coronary artery bypass grafting (CABG) is a common problem for which medical management has been disappointing. Atrial-based pacing has become an attractive nonpharmacologic therapy for the prevention of AF.

METHODS

Sixty-one post-CABG patients (mean age = 65 years) were randomized to one of three groups: no atrial pacing (NAP), right atrial pacing (RAP) or biatrial pacing (BAP). Each patient had one set of atrial wires attached to both the right and left atria, respectively, at the conclusion of surgery. Patients in the RAP and BAP groups were continuously paced at a rate of 100 pulses per minute for 96 h or until the onset of sustained AF (>10 min). All patients were monitored with Holter monitors or full disclosure telemetry to identify the onset of AF. The primary end point of the study was the first onset of sustained AF.

RESULTS

There was no significant difference in the proportion of patients developing AF in the three groups (NAP = 33%; RAP = 29%; BAP = 37%; p > 0.7). However, for the subset of patients on beta-adrenergic blocking agents after CABG, there was a trend toward less AF in the paced groups. There were no serious complications related to pacing, although in three patients the pacemaker appeared to induce AF by pacing during atrial repolarization.

CONCLUSIONS

Continuous right or biatrial pacing in the postoperative setting is safe and well tolerated. We did not find that post-CABG pacing prevented AF in this pilot study; however, the role of combined pacing and beta-blockade merits further study.     

房间隔起搏对阵发性心房颤动患者最大P波时限和P波离散度的影响

观察房间隔起搏对阵发性心房颤动 (AF)患者最大P波时限 (Pmax)及P波离散度 (Pd)的影响 ,探悉房间隔起搏防治AF发作的电生理机制。对 2 1例阵发性AF患者和 2 6例室上性心动过速行射频消融术无阵发性AF患者 ,分别进行右心耳和房间隔起搏 ,比较不同部位起搏对阵发性AF和无阵发性AF患者的Pmax和Pd影响。结果 :阵发性AF患者较无阵发性AF患者Pmax和Pd值明显大 (分别为 1 35± 1 5vs 1 1 9± 1 4ms ,P <0 .0 5 ;36 .5± 9.2vs 1 9.7± 7.1ms ,P <0 .0 1 ) ;房间隔起搏使阵发性AF患者Pd、Pmax显著下降 (分别为 2 3 .4± 8vs 36 .5± 9.2ms ,1 2 0± 1 1vs1 35± 1 5ms,P均 <0 .0 5) ;右心耳起搏使无阵发性AF患者Pmax和Pd明显增加 (分别为 1 32± 1 2vs 1 1 9± 1 4ms,2 5 .5± 8.5vs 1 9.7± 7.1ms ,P均 <0 .0 5)。结论 :右心耳起搏能够使无阵发性AF患者Pmax和Pd值增加。房间隔起搏能够明显降低阵发性AF患者Pmax、Pd ,纠正房内或房间传导延缓 ,改善心房内电活动的各向异性 ,防治AF发作     

抗心动过速起搏器识别、预防和终止快速房性心律失常的有效性分析

目的研究评价抗心动过速DDDRP起搏器对识别、预防和终止快速房性心律失常(atrial tachyarrhythmia,ATA)的有效性.方法研究对象为因病态窦房结综合征合并ATA而置入DDDRP起搏器(Medtronic,AT500/AT501)的患者24例.起搏器的心房预防性起搏(atrial preventive pacing,APP)方案由主治医生决定是否或者何时开启,ATA的监测和抗心动过速起搏(anti-tachycardia pacing,ATP)功能则在置入术后随即激活.回放起搏器存储的心律失常事件和心内电图,核对、分析起搏器识别ATA的准确性和ATP终止ATA的效率,同时比较在APP功能开启前后患者ATA负荷的差异.结果 24例患者在(17.63±8.79)个月的随访期内均无事件生存,无起搏器相关并发症.12例患者起搏器的APP功能始终是关闭状态,6例患者在第一次术后随访时开启,另有6例的APP功能在随访至9.29个月时激活.24台起搏器共记录到97 367阵次的ATA,在有心内电图记录的阵次中,起搏器对ATA识别正确率为(76.77±20.52)%;ATP终止ATA的有效率为(50.27±19.29)%.尽管APP功能开启后的心房起搏比例(87.95±20.93)%较开启前(50.73±34.46)%明显增高(P《0.01),但是患者的ATA负荷(14.73% 与16.52% 或7.52 h/周与6.58 h/周)和最长单阵ATA持续时间(27.27 h 与20.75 h)差异均无统计学意义(P》0.05).结论 DDDRP起搏器能识别和诊断大多数(75%)的房性心律失常,适时发放的ATP治疗可超速抑制、终止约50%的房性心动过速或心房扑动;APP功能提高心房起搏的比例,但从整体上并不能明显减少ATA的发作和降低患者的ATA负荷.     

Placement of atrial pacing leads during atrial fibrillation. Feasibility and subsequent lead performance.

AIMS: To assess the feasibility of placing permanent atrial pacing leads during atrial fibrillation (AF) and whether such leads function satisfactorily. METHODS AND RESULTS: Prospective study of 17 consecutive patients in whom permanent atrial leads were positioned during an episode of paroxysmal AF. Fluoroscopic position ('figure of 8' or side-to-side movement and anterior position in RAO projection), lead impedance (> 300 but < 1000 ohms) and intracardiac electrogram (average peak to peak amplitude > 1 mV) were used to define an acceptable lead position. At 8 weeks post implant we measured: pulse duration pacing threshold at 5 V; lead impedance at 5 V and 0.5 ms; intracardiac electrogram (EGM) signal amplitude. At the end of the study we reviewed patients to establish whether AF had become permanent. In all patients, follow-up demonstrated satisfactory lead function. All leads had impedances between 300 and 1000 ohms. Pacing thresholds were all < 0.1 ms at 5 V. Mean atrial EGM amplitude seen in sinus rhythm was 3.3 mV (range 1.2-8.4); in patients where all follow-up was in AF in was 2.1 mV (range 1.5-2.5). Nine patients (53%) developed permanent AF. CONCLUSION: Placing atrial leads during AF is feasible using the technique described. However, some patients progress to chronic AF, eliminating the benefits of atrial pacing.     

Influence of pacing modalities on the incidence of atrial fibrillation in patients without prior atrial fibrillation. A prospective study

Aim Many studies suggest that patients who receive a physiologicalpacemaker have a reduced incidence of atrial fibrillation comparedto patients receiving a ventricular pacemaker. Methods In order to evaluate the impact of different pacing modalitieson the incidence of atrial fibrillation, we prospectively analysed210 patients. Patients with previous episodes of atrial fibrillationwere excluded from the study. The patient population included110 patients paced for sick sinus syndrome and 100 patientspaced for total atrio-ventricular block or second degree typeatrioventricular block. Results Patients were followed for 5 years; the incidence of atrialfibrillation was 10% at 1 year, 23% at 3 years and 31% at 5years. There was an increase in the incidence of atrial fibrillationin patients receiving a ventricular pacemaker compared to patientsreceiving a physiological pacemaker. Conclusion The pacing modality appeared to influence the incidence of atrialfibrillation in paced patients; patients with ventricular pacinghad a significantly higher incidence of arrhythmias than didpatients with physiological pacing.     

Paroxysmal atrial fibrillation prevention by pacing in patients with pacemaker indication.

AIMS: The prevent-atrial fibrillation (AF) registry analyses the clinical relevance and usefulness of the four preventive pacing algorithms, available in a family of cardiac stimulators, to prevent atrial fibrillation. METHODS AND RESULTS: This study is a prospective, non-randomized, multicentre registry. Patients are eligible for the registry if they have sick sinus syndrome (SSS) with or without pre-existing atrial fibrillation. The preventive pacing algorithms were programmed for each patient on an individual basis using the diagnostic features of the devices. In the period from April 2000 to April 2001 a total of 68 patients (33 male, 35 female) has been included in the registry in 14 hospitals in Spain. Mean age was 72+/-12 years and the pacemaker indication was SSS in 15 patients (22%) and SSS with paroxysmal AF in 53 patients (78%). The median AF burden for the total group (n=32) was significantly reduced from 3.9 to 1.3% (67%, P=0.034, Wilcoxon signed rank test). The decrease in AF burden was accompanied by a non-significant decrease in the median number of episodes per day from 1.47 to 0.64 (a decrease of 56%). The average atrial pacing % was increased from 72 to 78%. CONCLUSIONS: The prevent-AF registry demonstrated the usefulness of four preventive pacing algorithms in daily clinical practice. During the registry a significant reduction in AF burden and all other endpoints was observed. Dedicated diagnostics were key to adapting the optimal pacing therapy during follow-up.