Efficacy and tolerability of continuous overdrive atrial pacing in atrial fibrillation.

Overdrive right atrial pacing has been used to prevent atrial fibrillation, but its efficacy in atrial fibrillation prevention and the patient tolerability and quality of life during high rate pacing remain uncertain. The objective of this study was to test the effects of a consistent atrial pacing algorithm that automatically paced the atrium at 30 ms shorter than the sinus P-P interval for atrial fibrillation prevention. Fifteen patients with sick sinus syndrome implanted with a Thera DR (model 7940 or 7960, Medtronic Inc.) were randomly programmed to rate adaptive dual chamber pacing (DDDR) or DDDR + consistent atrial pacing mode, each for an 8-week study period. The efficacy of consistent atrial pacing was assessed by the number of automatic mode switching and the number of premature atrial complexes. Symptoms and quality of life were assessed by the SF-36 quality of life questionnaire and an atrial fibrillation symptom checklist. The percentage of atrial pacing increased from 57 +/- 32% to 86 +/- 28%. Overall, there was no significant difference in the number of automatic mode switching episodes between DDDR and DDDR + consistent atrial pacing (47 +/- 90 vs 42 +/- 87, P > 0.05), but a significant reduction in premature atrial complexes by 74.7% (P < 0.001). There was no undue increase in atrial rate by the DDDR + consistent atrial pacing mode versus DDDR (63 +/- 13 vs 70 +/- 7 bpm). There was no significant difference in quality of life scores and symptom severity on frequency between the two modes of pacing, but a trend towards a lower frequency of symptoms in the DDDR + consistent atrial pacing mode compared with baseline (29.5 +/- 10.2 vs 25.1 +/- 9.7, P = 0.07). An algorithm that provides consistent atrial overdrive pacing can suppress atrial fibrillation triggering premature atrial complexes without the need to increase the overall atrial rate compared with conventional pacing. The algorithm appears to be well-tolerated, but further studies are needed to address the clinical impact of this atrial fibrillation prevention algorithm.     

Transvenous internal cardioversion for atrial fibrillation: a randomized study on defibrillation threshold and tolerability of asymmetrical compared with symmetrical shocks.

The aim of the study was to compare, according to a randomized cross-over design, two different biphasic waveforms (6.5/2.5 ms and 3.0/3.0 ms phases duration, respectively) for low energy internal atrial cardioversion with regard to energy requirements for cardioversion and shock induced discomfort. METHODS: Nineteen patients with chronic persistent atrial fibrillation (AF)(mean duration 16+/-20 months) were submitted to internal atrial cardioversion (shock delivery between catheters in right atrium and coronary sinus, respectively) and were randomly allocated to baseline cardioversion with an asymmetrical biphasic shock (6.5/2.5 ms) or with a symmetrical biphasic shock (3.0/3.0 ms), according to a step up protocol. After baseline cardioversion, a sustained AF was reinduced and the patients crossed to the alternative waveform. The procedure was performed without routine administration of sedatives and shock induced discomfort was monitored by a subjective score (1 to 5). Sedatives or anesthetics were administered at patient's request. RESULTS: The procedure was effective in all the patients and was performed without need for sedatives/anesthetics in 17/19 patients (89%). Leading edge voltage of effective shocks resulted lower for asymmetrical shocks compared to symmetrical shocks (290+/-76 vs. 337+/-104 V, P<0.001) with no statistically significant differences in delivered energy (7.74+/-4.25 vs. 8.65+/-5.94 J). Moreover shock induced discomfort resulted lower for asymmetrical shocks compared to symmetrical (pain score=4.18+/-0.73 vs. 4.59+/-0.62, P<0.02). Shock impedence of effective shocks was 59+/-10 ohms for both waveforms. No significant complications occurred during the procedure and no ventricular arrhythmia was observed after atrial cardioversion. Transient bradycardia requiring support ventricular pacing was observed in one patient. CONCLUSIONS: Delivery of biphasic asymmetrical shocks (6.5/2.5 ms) results in lower leading edge voltage of effective shocks and better patients tolerability compared with conventional biphasic symmetrical shocks (3.0/3.0 ms). These findings are of interest both for transvenous internal cardioversion of chronic persistent AF and for implantable atrial defibrillators.     

Lung function and dyspnea in patients with permanent atrial fibrillation

Background

Reduced forced expiratory volume in one second (FEV₁) has been associated with new-onset atrial fibrillation (AF), and AF patients often complain of dyspnea. We hypothesized that patients with permanent AF had reduced lung function compared to subjects in sinus rhythm.

Methods

The participants were 75 year-olds from the general population. FEV₁, forced vital capacity (FVC), maximal voluntary ventilation (MVV), total lung capacity by single breath (TLC_SB), single-breath diffusing capacity of the lung for carbon monoxide (DLCO_SB) and exercise testing with peak oxygen uptake (VO₂ peak) were assessed. The slope of minute ventilation over carbon dioxide output defined ventilatory efficiency. The Symptom Checklist-frequency and severity questionnaire assessed dyspnea.

Results

AF patients had significantly higher number (%) of subjects below the 5th percentile of predicted FEV₁ (7 (27) versus 3 (4), p = 0.005), FVC (6 (23) versus 2 (3), p = 0.006) and TLC_SB (11 (42) versus 12 (18), p = 0.014) compared to control subjects, also after adjustment for smoking and obesity, or if disregarding subjects with chronic heart failure. The dyspnea frequency and severity scores correlated with VO₂ peak (r = − 0.6, p < 0.01) in AF patients, and in control subjects with % predicted FEV₁, MVV and TLC_SB (r = − 0.3, p < 0.05).

Conclusion

More patients with permanent AF had lung function below normal range than control subjects in sinus rhythm, irrespective of smoking, obesity or chronic heart failure. Dyspnea, however, was related to exercise capacity rather than to lung function in AF patients.     

Cardioversion by internal electric shock of permanent atrial fibrillation

A new technique for cardioversion of chronic atrial fibrillation was used in 17 patients whose arrhythmia had resisted all attempts at electrical and pharmacologycal cardioversion. Atrial fibrillation was badly tolerated by all patients despite digitalis administered alone (8 patients) or combined with amiodarone (9 patients). Twelve patients had left atrial dilatation at echocardiography. The 200, 300 or 400 joule electrical shock was delivered between the proximal pole of a quadripolar catheter (cathode) and a back plate (anode). The catheter was positioned at the His bundle recording site then withdrawn into the right atrium. The internal shock restored sinus rhythm in 15 patients (88 p. 100). Transient atrioventricular block (3-315 sec) was observed in 8 patients. Eleven patients were discharged in sinus rhythm. In 4 patients, the atrial fibrillation recurred on day 8 and after 2, 4 and 9 months. A second shock was attempted in two patients and succeeded in one. After a mean follow-up period of 14.8 +/- 8 months (range 2 to 25 months), 8 of the 11 patients successfully cardioverted (72 p. 100) or of the attempted reductions (47 p. 100) were in sinus rhythm. The remaining 9 patients were treated with antiarrhythmic drugs (n = 5) or by his bundle catheter ablation (n = 4). High energy internal shock therefore seems to be an interesting treatment in patients with permanent atrial fibrillation after failure of external electric shock. It enabled 13 of the 17 patients in this series to avoid His bundle catheter ablation indicated by the quasi-impossibility to control the atrial rate and associated symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of intra-operative radiofrequency ablation in patients with permanent atrial fibrillation undergoing concomitant mitral valve replacement

BACKGROUND: Permanent atrial fibrillation (AF) is present before operation and persists after surgery in 30-40% of patients undergoing mitral valve surgery. Using the maze procedure, 75-82% of patients can be cured of AF, but the procedure is difficult and long lasting. Percutaneous radiofrequency (RF) ablation has emerged as an effective therapy for AF in recent years. AIM: To assess the efficacy of intra-operative RF ablation of AF in patients undergoing mitral valve surgery. METHODS: 100 adults with permanent AF underwent mitral valve replacement. Patients were divided into two groups: the RF group--50 patients qualified for mitral valve replacement and RF ablation; and the control group--50 patients selected for mitral valve replacement without ablation. Odds ratio and 95% confidence interval were examined to assess the influence of several factors on the outcome (free from AF during one-year follow-up based on symptoms and serial Holter ECG recordings). RESULTS: Baseline clinical, demographic and echocardiographic characteristics were similar in both groups. Electrical cardioversion following surgery was required in 76% of patients from the RF group compared with 94% from the control group (p<0.002). In those who underwent cardioversion, sinus rhythm was restored more frequently in RF than control patients (32 vs. 16%, p<0.002). Sinus rhythm at hospital discharge was present in 56% of RF patients compared with 22% of controls (p=0.0001), and after one-year follow-up in 54 vs. 16% (p<0.001), respectively. The use of amiodarone was significantly lower in RF patients compared with controls (32 vs. 70%, p<0.05). NYHA class III (OR 8.5, CI 1.0-394) or IV (OR 36, CI 1.2-1958) and left atrial diameter >6 cm (OR 9.3, CI 0.5-5230) were identified as predictors of AF. CONCLUSIONS: Intra-operative RF ablation performed in the left atrium in patients with chronic AF undergoing mitral valve replacement significantly improves sinus rhythm restoration rate. Advanced heart failure (NYHA class IV) and left atrial diameter >6 cm are negative prognostic factors for sinus rhythm maintenance.     

Limited internal shocks for atrial fibrillation refractory to external cardioversion.

We investigated the feasibility and long-term results of low-energy internal defibrillation using a limited number of shocks in patients with persistent atrial fibrillation resistant to external cardioversion. A relatively high number of shocks of lower energy are usually required in those cases and can be poorly tolerated. METHODS AND RESULTS: Twenty-five patients with persistent atrial fibrillation underwent internal defibrillation, using biphasic R wave synchronous shocks between two catheters in the high right atrium and the coronary sinus. Conversion to sinus rhythm was obtained in all patients, with a median of two shocks. Early recurrence of atrial fibrillation (AF) occurred in eight cases (32%). Seven patients (41%) out of 17 discharged in sinus rhythm remained free of AF after a median follow-up of 8.9 months. Severe mitral insufficiency (P=0.05) and low left ventricle ejection fraction (P=0.002) were correlated with earlier recurrence. Amiodarone significantly favored (P=0.019) maintenance of sinus rhythm. CONCLUSION: Internal defibrillation using a limited number of shocks equal to or less than 30 Joules is effective in terminating refractory atrial fibrillation and could be more acceptable for patients. However, the recurrence rate remains high, particularly in patients with severe mitral insufficiency or poor ventricular function. Amiodarone delays recurrences of atrial fibrillation.     

Efficacy of internal cardioversion for chronic atrial fibrillation in patients with and without left ventricular dysfunction

Internal cardioversion can restore sinus rhythm with energies below 6-10 J, often without anaesthesia/sedation. We investigated its safety and short-/medium-term efficacy in patients with persistent atrial fibrillation (AF) with left ventricular dysfunction (defined as ejection fraction < or = 40%). Among 34 patients with persistent AF who agreed to receive internal cardioversion, 16 had left ventricular dysfunction and 18 did not (the groups were similar as regards age, duration of AF and pretreatment with amiodarone). Internal CV was performed delivering 3.0/3.0-ms biphasic shocks between coil catheters using a step-up protocol. Sinus rhythm was always restored. General anaesthesia (administered only when discomfort was not tolerated) was required only in 2 of the 16 (12.5%) patients with left ventricular dysfunction. The defibrillation threshold was similar in patients with and without left ventricular dysfunction (10.2+/-6.9 vs. 8.4+/-4.9 J; p=0.37). Short-term (within 72 h) AF recurrence rates in the presence and absence of left ventricular dysfunction were 19% (3/16) and 6% (1/18), respectively (p=0.51). After cardioversion, all patients received antiarrhythmic drugs (mostly amiodarone in patients with left ventricular dysfunction and class IC agents in the remainder). With mean follow-up periods of about 220 days, AF recurrence rates among patients with and without left ventricular dysfunction were 50% (8/16) and 28% (5/18), respectively (p=0.328). We conclude that even in patients with left ventricular dysfunction, internal CV is safe and effective, minimizing risks from anaesthesia. Although these patients may have a higher risk of short- or medium-term AF recurrence, 6-month maintenance of sinus rhythm is possible in about 50% of cases.     

Efficacy and safety of dofetilide in patients with atrial fibrillation and atrial flutter

Background  Dofetilide, an I_Kr blocker has been demonstrated to be effective in terminating persistent atrial fibrillation and flutter (AF/AFL), and in maintaining sinus rhythm after direct current cardioversion (CV). It is not known, however, whether pharmacological conversion with dofetilide predicts maintenance of sinus rhythm. In addition, there is limited information comparing the efficacy of dofetilide in persistent versus paroxysmal AF/AFL. Methods and Results  Eighty consecutive patients with AF/AFL (51 persistent, 29 paroxysmal) admitted for initiation of dofetilide were studied. Termination of persistent AF/AFL occurred in 61% of patients while 39% required CV. After 21 ± 19 months of follow-up, 37% of patients with persistent AF/AFL were free of recurrence. Acute conversion with dofetilide did not predict long term efficacy. Dofetilide was more effective in maintaining sinus rhythm in patients with AFL (65%) than in those with AF (25%) (p < 0.05). Dofetilide was more likely to maintain sinus rhythm in patients with persistent than paroxysmal AF/AFL (37 vs. 14%; p < 0.05). Torsades de Pointes developed in two patients despite careful dosing and monitoring of QT changes. Conclusions  Dofetilide is more effective in patients with persistent than in those with paroxysmal AF/AFL. Importantly, short-term response does not necessarily predict long-term efficacy. Significant proarrhythmia can occur even with careful in-hospital monitoring. Dr. Banchs and Dr. Wolbrette contributed equally to this study. Presented in abstract form at the XIII World Congress on Cardiac Pacing and Electrophysiology; December 3, 2007; Rome and published in abstract form (Giornale Italiano di Aritmologia e Cardiostimolazione 2007;10(3):26).     

冲洗式射频消融迷宫手术治疗不同病因永久性心房颤动的疗效比较

目的分析和比较我院冲洗式射频消融迷宫手术治疗不同病因永久性心房颤动（房颤）的疗效。方法：收集我院201 1年1月1日-2012年12月31日外科冲洗式射频消融迷宫手术治疗永久性房颤502例病例资料进行分析。根据病因（手术方式）不同分为两组：瓣膜置换并发冲洗式射频消融迷宫手术（瓣膜病组）406例;非瓣膜置换并发冲洗式射频消融迷宫手术（非瓣膜病组）96例。分别于术中心脏复跳、术后1周、3个月和6个月行超声心动图及心电图检查,观察左房、左室大小及窦性心律维持情况。结果：两组术后各时点心脏转复率均无显著差异,两组左房内径均较术前显著缩小。就全部患者而言,术中心脏转为窦性心律者为358例,转复率为71．3％;术后1周为376例,转复率为74．9％;术后3个月为347例,转复率为69．1％。术后6个月为339例,转复率为67．5％。总体手术死亡3例,2例死于低心排,1例死于恶性心律失常（室颤）,手术死亡率为0．6％。结论：冲洗式射频消融迷宫手术治疗不同病因永久性房颤的疗效没有显著差异,疗效均较好。     

Low energy internal cardioversion of atrial fibrillation resistant to transthoracic shocks.

OBJECTIVE: To investigate the efficacy of internal cardioversion using low energy shocks delivered with a biatrial electrode configuration in chronic atrial fibrillation resistant to transthoracic shocks. METHODS: Low energy internal cardioversion was attempted in 11 patients who had been in atrial fibrillation for 233 (SD 193) days and had failed to cardiovert with transthoracic shocks of 360 J in both apex-base and anterior-posterior positions. Synchronised biphasic shocks of up to 400 V (approximately 6 J) were delivered, usually with intravenous sedation only, between high surface area electrodes in the right atrium and the left atrium (coronary sinus in nine, left pulmonary artery in one, left atrium via patent foramen ovale in one). RESULTS: Sinus rhythm was restored in 8/11 patients. The mean leading edge voltage of successful shocks was 363 (46) V [4.9 (1.2) J]. Higher energy shocks induced transient bradycardia [time to first R wave 1955 (218) ms]. No proarrhythmia or other acute complications were observed. CONCLUSIONS: Low energy internal cardioversion of atrial fibrillation can restore sinus rhythm in patients in whom conventional transthoracic shocks have failed.     

静脉地尔硫治疗快速房颤、房扑的疗效分析

为检验静脉地尔硫艹卓控制房颤、房扑心室率的有效性和安全性，对４７例快速房颤、房扑患者一次静脉注射０．２５ｍｇ／ｋｇ地尔硫艹卓后以５ｍｇ／ｈ～１０ｍｇ／ｈ微泵维持，平均起效时间５．２±２．７ｍｉｎ，总有效率９３．６％，心功能较用药前明显改善（Ｐ＜０．０５），对血压无明显影响，副作用发生率为１０．６％，均不严重。结果提示地尔硫艹卓是一种能迅速、安全、有效控制房颤、房扑患者心室率的药物     

胺碘酮对心力衰竭并心房颤动病人的疗效观察

目的：就胺碘酮对心力衰竭并心房颤动病人的疗效观察进行探讨。方法选择我院2008年11月到2013年1月所收治的心力衰竭并心房颤动患者50例,随机将所有患者分为2组,分别是治疗组、对照组,。对照组采用常规治疗方法,而治疗组在此基础上增加静脉注射胺碘酮溶液及口服胺碘酮。结果治疗组有效率为96％,对照组有效率为82％,二者存在着较为明显的差异,具有统计学意义（P〈0.05）。与治疗前相比,两组患者在治疗后血压值都出现了较为明显的变化,都达到正常水平,存在着统计学意义（P〈0.05）;但两组之间差异不存在着统计学意义（P〉0.05）。两组患者在治疗后都没有出现肾功能、肝功能损害、恶性心律失常、不可耐受性低血压等严重不良反应。结论胺碘酮对心力衰竭并心房颤动病人的疗效较佳,安全有效,无较为严重的不良反应,可以作为首选治疗药物,值得推广应用。     

心脏起搏术后阵发性转为持续性心房颤动的影响因素分析

目的分析心脏起搏术后阵发性心房颤动(简称房颤)进展为持续性房颤的风险及可能影响因素。方法109例慢快综合征和30例快慢综合征患者,分别植入VVI(R)或DDD(R)起搏器。根据房颤进展情况分为持续性房颤组(进展组)和非持续性房颤组(非进展组)。分析心脏永久起搏术后房颤进展情况及影响因素。结果平均随访(5.1±2.2)年,51例进展为持续性房颤。单因素分析显示预测房颤进展的危险因素包括左房内径、未使用抗心律失常药物、VVI起搏、高房颤负荷及慢快综合征。多因素Logistic回归分析显示左房内径(HR=1.103,95%CI1.085~1.124,P0.05)、未使用抗心律失常药物(HR=1.975,95%CI 1.336~2.813,P0.001)、VVI起搏(HR=2.156,95%CI1.458~3.157,P0.001)及慢快综合征(HR=1.875,95%CI1.326~3.025,P0.001)是房颤进展的独立预测因素。Kaplan-Meier分析示慢快综合征进展为持续性房颤快于快慢综合征(P=0.034)。结论慢快综合征、左房内径、未使用抗心律失常药物、VVI起搏是阵发性房颤进展为持续性房颤的独立预测因素。     

Efficacy of an implanted automatic defibrillator which had induced atrial fibrillation

A 54 year old man with refractory life threatening ventricular tachycardia was given an automatic defibrillator. The initial system was a transvenous defibrillator coil electrode and this was later modified by implantation of two patch electrodes at thoracotomy. The modified system successfully controlled ventricular tachycardia. On one occasion reversion of ventricular tachycardia by the defibrillator precipitated atrial fibrillation, a previously unreported side effect.     

Association between transthoracic impedance and electrical cardioversion success with biphasic defibrillators: An analysis of 1055 shocks for atrial fibrillation and flutter

Background

The relevance of transthoracic impedance (TTI) to electrical cardioversion (ECV) success for atrial tachyarrhythmias when using biphasic waveform defibrillators is unknown.

Hypothesis

TTI is predictive of ECV success with contemporary defibrillators.

Methods

De‐identified data stored in biphasic defibrillator memory cards from ECV attempts for atrial fibrillation (AF) or atrial flutter (AFL) over a 2‐year period at our center were evaluated. ECV success, defined as arrhythmia termination and ≥ 1 sinus beat, was adjudicated by 2 blinded cardiac electrophysiologists. The association between TTI and ECV success was assessed via Cochrane‐Armitage trend and Spearman rank correlation tests, as well as simple and multivariable logistic regression. The influence of TTI on the number of shocks and on cumulative energy delivered per patient was also examined.

Results

703 patients (593 with AF, 110 with AFL) receiving 1055 shocks were included. Last shock success was achieved in 88.0% and 98.2% of patients with AF and AFL, respectively. In patients with AF, TTI was positively associated with last shock failure (P_trend =0.019), the need for multiple shocks (P_trend <0.001), and cumulative energy delivered (ρ = 0.348; P < 0.001). After adjusting for first shock energy, 10‐Ω increments in TTI were associated with odds ratios of 1.36 (95% CI: 1.24–1.49) and 1.22 (95% CI: 1.09–1.37) for first and last shock failure, respectively (P < 0.001 for both).

Conclusions

Although contemporary defibrillators are designed to compensate for TTI, this variable continues to be associated with ECV failure in patients with AF. Strategies to lower TTI during ECV for AF may improve procedural success.     

华发令预防高龄非瓣膜病房颤血栓栓塞的效果及安全性

目的观察华发令预防高龄非瓣膜病心房颤动（房颤）患者血栓栓塞的效果及安全性。方法选择2002年1月2006年1月120例在我科住院的年龄≥75岁房颤患者,随机分为4组,A、B、C 3组华发令口服剂量随国际准化比率（INR）调整,A组INR维持在1.52.0;B组INR维持在2.03.0;C组INR维持在1.52.0的同时给予阿司匹林100 mg/d口服;D组给予阿司匹林100200 mg/d口服,随访时间1848（32±8）月,随访内容使用统一表格,记录各项化验及其他辅助检查结果、终点事件发生时间等。结果A组栓塞事件1例（3%）,D组6例（20%）,B、C组无1例;A、D组出血事件各发生1例（3%）,B组5例（17%）,C组7例（23%）;D组死亡7例,C组死亡1例,P<0.05。结论华发令抗凝强度INR为1.52.0时对预防高龄房颤患者血栓栓塞安全、有效,可供临床选择。     

射频消融术在老年阵发性心房颤动患者中的应用效果

目的 探讨射频消融术在老年阵发性心房颤动患者中的应用效果及其对预后的影响.方法 选择2014年9月到2019年9月于秦皇岛市骨科医院院择期行射频消融术的450例阵发性心房颤动患者为研究对象,按照年龄不同将其分为非老年组(年龄<60岁,n=240)和老年组(年龄≥60岁,n=210).2组均采用射频导管消融术进行治疗,并...