Amiodarone in atrial fibrillation

Twenty-seven patients with atrial fibrillation without any concomitant conduction abnormality have been treated with oral amiodarone in a daily maintenance dose of 200 mg. The drug has been used for three purposes: 1) to block atrioventricular conduction, thereby decreasing the ventricular rate during atrial fibrillation (9 patients), 2) as prophylaxis against paroxysmal atrial fibrillation (8 patients), 3) as prophylaxis against recurrence of atrial fibrillation after DC conversion to sinus rhythm (13 patients). All patients were considered refractory to other antiarrhythmic drugs in these respects. In the second group, 4 of the 8 patients reported complete cessation of attacks and the others a marked reduction of the attack rate. In the third group, 10 of the 13 patients have maintained sinus rhythm for a longer period on treatment with amiodarone than with other drugs, resulting more than a triple prolongation of the time in sinus rhythm. In 3 patients the drug has been discontinued because of side-effects. In conclusion, amiodarone affords protection from episodes of paroxysmal atrial fibrillation, as well as from recurrence of atrial fibrillation after DC conversion to sinus rhythm. If the drug is ineffective in either of these respects, it may still be useful as a means of moderating the ventricular response in atrial fibrillation.     

Comparative study of the effect of pacing mode on the interaction of the right and left ventricles

This study was designed to evaluate ventricular dyssynchrony from the viewpoint of the interaction of right and left ventricular contractions. Forty-three patients, 24 with sick sinus syndrome, 9 with complete atrioventricular block, and 10 with normal sinus rhythm were involved in this study. Microtip transducer catheters were advanced into both the left and right ventricles and ventricular pressure and the associated dp/dt were recorded simultaneously. Hemodynamic differences in various pacing modes were analyzed using pressure and dp/dt recordings obtained from the left and right ventricles. When an asynchrony between the right and left ventricular contractions existed, the right ventricular positive peak dp/dt developed a dual-peak waveform, the second peak corresponding in time to the peak of the left ventricular positive peak dp/dt. This dual-peak dp/dt waveform was seen with ventricular (VVI) and atrioventricular sequential (DVI) pacing, whereas a single-peak waveform was seen with atrial (AAI) pacing or sinus rhythm. In cases where DVI or VVI pacing modes are selected, an asynchronous effect between contractions of the right and left ventricles may occur, with dual-peak dp/dt of the right ventricle. Because the dual-peak dp/dt waveform indicates ventricular dyssynchrony, reducing the distance from peak I to peak II could maintain the synchronization of the right and left ventricles. It is considered particularly vital to give sufficient consideration to this point in chronic heart failure patients with left bundle branch block requiring biventricular pacing.     

Long-term outcome of single-chamber atrial pacing compared with dual-chamber pacing in patients with sinus-node dysfunction and intact atrioventricular node conduction

Purpose

The optimal pacing mode with either single chamber atrial pacemaker (AAI or AAIR) or dual chamber pacemaker (DDD or DDDR) is still not clear in sinus-node dysfunction (SND) and intact atrioventricular (AV) conduction.

Materials and Methods

Patients who were implanted with permanent pacemaker using AAI(R) (n = 73) or DDD(R) (n = 113) were compared.

Results

The baseline characteristics were comparable between the two groups, with a mean follow-up duration of 69 months. The incidence of death did not show statistical difference. However, the incidence of hospitalization for congestive heart failure (CHF) was significantly lower in the AAI(R) group (0%) than the DDD(R) group (8.8%, p = 0.03). Also, atrial fibrillation (AF) was found in 2.8% in the AAI(R) group, which was statistically different from 15.2% of patients in the DDD(R) group (p = 0.01). Four patients (5.5%) with AAI(R) developed AV block, and subsequently switched to DDD(R) pacing. The risk of AF was lower in the patients implanted with AAI(R) than those with DDD(R) [hazard ratio (HR), 0.84; 95% confidence interval, 0.72 to 0.97, p = 0.02].

Conclusion

In patients with SND and intact AV conduction, AAI(R) pacing can achieve a better clinical outcome in terms of occurrence of CHF and AF than DDD(R) pacing. These findings support AAI(R) pacing as the preferred pacing mode in patients with SND and intact AV conduction.     

高频起搏犬房颤模型心房重塑及窦房结和房室结功能的变化

 目的:持续高频起搏犬左心房,观察房颤(AF)发生率、心房重塑以及窦房结、房室结传导功能。方法: 健康比格犬15只随机分为起搏组(P组,n=9)和对照组(N组,n=6)。2组均在左心房心外膜缝合固定一起搏电极,P组以400 min-1的频率起搏,N组不起搏。采用程序起搏技术测定电生理参数。结果: (1) 4周后P组阵发性AF和持续性AF的诱发率与N组比较差异均有统计学意义（分别P<0.05,P<0.01）,P组第2周2只犬自发AF,第4周AF诱发率达100%,且持续性AF的发生率高。 (2) P组4周后心房有效不应期(AERP)在不同基本起搏周期(250 ms、300 ms和350 ms)时均较N组缩短 (P<0.05);房室结文氏点(AVN-Wen) 较N组有意义延长［(294.44±26.03)min-1 vs (328.33±24.01)min-1, P<0.05］;房室结有效不应期(AVERP)在不同起搏周期均明显延长 (P<0.01)。(3) 与N组比较,P组4周后窦房结恢复时间（SNRT）和校正恢复时间（cSNRT）均延长（P<0.01）;P波时限2组比较差异没有统计学意义(P>0.05)。(4) P组2周后心脏超声与N组比较显示左心房前后、上下、左右径都有明显增大(P<0.01),右心房上下增大(P<0.05)。结论: 持续４周心房高频起搏后房颤发生率高,心房肌、窦房结和房室结电生理发生特征性的相应改变,左、右心房不同程度扩大,提示电重塑、结构重塑与房颤的发生关系密切。     

经食管心房调搏诱发阵发性房颤20例分析

目的 探讨经食管心房调搏诱发阵发性房颤的电生理特性及临床意义。方法 采用经食管心房起搏诱发阵发性房颤患者20例（观察组）与无诱发房颤正常人20例（对照组）的电生理资料比较，结果 与对照组比较，观察组最大P波时（Pmax）、心房有效不应期（ERPA）、心房相对不应期区域（ZRRPA）、最大房间传导时间[（S2-A2）max]、早搏刺激的房间延缓（IACD）差异有非常显著意义（P〈0．001）．结论。诱发阵发性房颤的电生理学改变明显，食管心房调搏简便安全，对预测房颤具有一定价值。     

高频刺激左心房引起家兔慢性心房颤动

目的： 探讨以高频率起搏刺激左心房建立家兔慢性心房颤动模型的方法。 方法： 20只家兔随机分为实验组及对照组，对照组为假手术组，植入起搏器但不起搏，实验组10只家兔予开胸植入高频率起搏器(1 000 次/分)刺激左心房30 d，术后定期监测起搏、心房颤动的发生情况、房颤时心室率变化，同时测定起搏前及房颤发生后心房有效不应期（AERP）的变化。 结果： 实验组均完成了实验，术后第7 d，7只（70％）兔发生了房颤，2周时共有8只（80％）发生了房颤并能稳定维持（与对照组比较，P＜0.01），30 d时仍示房颤，其余2只兔至30 d时仍呈起搏心律，对照组则未发生任何心律失常情况。心房颤动时的心室率最初明显增快（P＜0.05），随后有所降低（P＜0.05），但仍高于基础心室率（P＜0.05）。AERP缩短，AERP频率适应不良，与基础状态相比有显著意义。 结论： 长期高频率起搏刺激家兔左心房是建立慢性房颤模型的有效方法。     

The prospectivity of permanent cardiostimulation for prevention of atrial fibrillation

Possibility of prevention of atrial fibrillation in patients with permanent pacemakers was analyzed taking into account induction mechanisms. Patients with bradicardiac and ectopic mechanisms of atrial fibrillation induction seem to be optimal candidates for pacemaker therapy. Right ventricular pacing was an independent predictor of arrhythmic events.     

高血压合并阵发性房颤患者心脏超声临床特点

目的:观察分析高血压合并阵发性房颤患者的心脏超声特点,为临床准确诊断提供依据.方法:选取2019年08月至2020年08月我院收治的51例高血压合并阵发性房颤患者作为研究组,同时选取51例单纯高血压患者作为常规组,所有患者均接受心脏超声诊断确定有无二尖瓣返流;同时观察心脏收缩期右房上下径、左房前后径、室间隔厚度、舒张期...     

Left ventricular function after long-term treatment with ventricular inhibited compared to atrial triggered ventricular pacing

The long-term effect of ventricular inhibited (VVI) and atrial triggered ventricular (VAT) pacing on cardiac performance was determined by cardiac catheterization at rest and during exercise in 9 patients with high-degree AV block. Cardiac output (Q) increased at rest by 22% during VAT vs. VVI (5.5 vs. 4.5 l/min, p less than 0.01). An increased stroke volume constituted the difference (75 vs. 63 ml, p less than 0.05). Mean working capacity increased by 12% in the supine position with VAT vs. VVI (p less than 0.05). During exercise Q increased by 40% with VAT vs. VVI (10.2 vs. 7.3 l/min, p less than 0.01) due to an increase in heart rate. Most pressures were largely unchanged. Stroke work and atrial rate decreased during VAT vs. VVI, which may indicate a lower sympathetic activity with VAT vs. VVI. The study demonstrated that hemodynamics advantages of VAT are still obtainable after several years of VVI pacing.     

Left ventricular volumes with ventricular inhibited and atrial triggered ventricular pacing

Left ventricular (LV) volumes were assessed with equilibrium radionuclide angiocardiography at rest and during exercise in nine patients with high-degree AV block treated with ventricular inhibited (VVI), which was subsequently changed to atrial triggered ventricular pacing (VAT). The ventricular rates were similar at rest but higher on exercise during treatment with VAT (102 ppm) than with VVI (71 bpm). The LV end-diastolic volume tended to be larger with VAT than with VVI pacing, both at rest (185 vs. 145 ml) and during exercise (220 vs. 162 ml). The LV end-systolic volume also tended to be larger at rest (110 vs. 81 ml) and during exercise (149 vs. 83 ml). The LV ejection fractions were similar at rest but on exercise they decreased to significantly lower levels with VAT (0.35), while remaining unchanged with VVI (0.47). One mechanism for this difference could be an enhanced contractile state in VVI pacing compared with VAT pacing.     

Diagnosis of atrial fibrillation in heart failure patients with implantable cardioverter defibrillator or cardiac resynchronisation therapy

IntroductionImplantable cardioverter defibrillators register various types of arrhythmias. Thus they can be exploited to better identify patients with atrial fibrillation episodes and increase the proportion of patients who may benefit from implementation of pharmacological prophylaxis of thromboembolic events, most of which are asymptomatic. The aim of the study was to assess of the frequency, symptoms and predisposing factors for the occurrence of atrial fibrillation episodes in patients with an implanted implantable cardioverter defibrillator (ICD) and cardiac resynchronisation therapy with defibrillator (CRT-D) based on the analysis of intracardiac electrocardiograms (EGM/IEGM) records.Material and methodsThe study included 174 consecutive outpatients with heart failure, sinus rhythm and an implanted cardioverter defibrillator and cardiac resynchronisation therapy with defibrillator. Follow-up visits with analysis of IEGM records occurred every 3 months. During a mean follow-up of 20 months, 901 visits were carried out. One hundred forty-seven patients had at least 1 year of follow-up.ResultsAtrial fibrillation episodes in the study group occurred in 54 (31.0%) patients and 71.4% were asymptomatic. Predisposing factors were: history of paroxysmal atrial fibrillation (37.0% vs. 13.3%, p < 0.001), atrioventricular conduction abnormalities (42.6% vs. 20.0%, p = 0.002), intraventricular conduction abnormalities (59.3% vs. 40.8%, p = 0.02) and more severe mitral regurgitation (7.4% vs. 0.8%, p = 0.04). Chronic renal disease was a risk factor for death in the study group. No stroke occurred during the study.ConclusionsEpisodes of paroxysmal atrial fibrillation in patients with systolic heart failure and implanted cardioverter-defibrillator systems are quite common. The majority of the episodes recorded in the study were asymptomatic.     

单根电极VDD起搏器的临床应用

应用单根电极VDD起搏器治疗窦房结功能正常的完全性或高度房室传导阻带、可以达到房室顺序的起搏目的。裸露的心房电极可感知心房的自身激动(A波),发出脉冲电流、刺激心室起搏。心室率随窦性频率的增加而增加,具有频率跟踪作用,增加了病人运动耐量。且手术操作简单,并发症少。能够安置VVI起搏的单位均可实施此种类型的生理性起搏手术。将成为窦房结功能正常的房室传导阻滞患者的最佳选择。     

Effects of physiologic pacing versus ventricular pacing on the risk of stroke and death due to cardiovascular causes. Canadian Trial of Physiologic Pacing Investigators

BACKGROUND: Evidence suggests that physiologic pacing (dual-chamber or atrial) may be superior to single-chamber (ventricular) pacing because it is associated with lower risks of atrial fibrillation, stroke, and death. These benefits have not been evaluated in a large, randomized, controlled trial. METHODS: At 32 Canadian centers, patients without chronic atrial fibrillation who were scheduled for a first implantation of a pacemaker to treat symptomatic bradycardia were eligible for enrollment. We randomly assigned patients to receive either a ventricular pacemaker or a physiologic pacemaker and followed them for an average of three years. The primary outcome was stroke or death due to cardiovascular causes. Secondary outcomes were death from any cause, atrial fibrillation, and hospitalization for heart failure. RESULTS: A total of 1474 patients were randomly assigned to receive a ventricular pacemaker and 1094 to receive a physiologic pacemaker. The annual rate of stroke or death due to cardiovascular causes was 5.5 percent with ventricular pacing, as compared with 4.9 percent with physiologic pacing (reduction in relative risk, 9.4 percent; 95 percent confidence interval, -10.5 to 25.7 percent [the negative value indicates an increase in risk]; P=0.33). The annual rate of atrial fibrillation was significantly lower among the patients in the physiologic-pacing group (5.3 percent) than among those in the ventricular-pacing group (6.6 percent), for a reduction in relative risk of 18.0 percent (95 percent confidence interval, 0.3 to 32.6 percent; P=0.05). The effect on the rate of atrial fibrillation was not apparent until two years after implantation. The observed annual rates of death from all causes and of hospitalization for heart failure were lower among the patients with a physiologic pacemaker than among those with a ventricular pacemaker, but not significantly so (annual rates of death, 6.6 percent with ventricular pacing and 6.3 percent with physiologic pacing; annual rates of hospitalization for heart failure, 3.5 percent and 3.1 percent, respectively). There were significantly more perioperative complications with physiologic pacing than with ventricular pacing (9.0 percent vs. 3.8 percent, P<0.001). CONCLUSIONS: Physiologic pacing provides little benefit over ventricular pacing for the prevention of stroke or death due to cardiovascular causes.     

The Tokai Pacemaker Register

 The Tokai Working Group on Cardiac Pacemakers was established in 1987 and initiated the Tokai Pacemaker Register in 1993. The register contains data on 1582 patients treated with 1582 generators and 2269 leads. The ECG indications for pacemaker implantation were 49.7% atrioventricular block, 41.1% sinus node dysfunction, and 7.4% atrial fibrillation. Dual-chamber pacing was used in 43.8%, VDD pacing was used in 37.6%, and single-chamber VVI pacing in 18.4% of the patients. Received: November 5, 2001 / Accepted: February 18, 2002 Correspondence to:N. Mizutani     

The relation between mitral annulus motion and left ventricular ejection fraction in atrial fibrillation.

Mitral annulus motion (MAM) has recently been introduced as an index of left ventricular function. Previous studies have shown a good agreement between MAM (mm) x 5 and ejection fraction in middle-aged and elderly patients. These studies only included patients with sinus rhythm, while patients with atrial fibrillation were excluded. In the present study, MAM was reduced in patients with atrial fibrillation while ejection fraction (EF) did not differ from age-matched control patients with sinus rhythm. The 'conversion factor' (EF/MAM) was 7.2 in the group with atrial fibrillation and 5. 1 in controls with sinus rhythm. This difference must be taken into account when MAM is used to estimate left ventricular function in patients with atrial fibrillation. Patients with atrial fibrillation had lower stroke volume and higher heart rate than patients with sinus rhythm. A decreased systolic long-axis shortening was found (P<0.005) compared to patients with sinus rhythm, but no difference in short-axis diameter shortening.     

A case of acute ventricular capture threshold rise associated with flecainide acetate

Antiarrhythmic agents may increase capture threshold, but this is rarely of clinical significance. Flecainide acetate, a class IC agent, is reported to have a significant effect on the myocardial capture threshold. In this presentation, we report the case of a 72-year-old male, with a previously implanted VVI pacemaker due to sick sinus syndrome, who was treated with flecainide acetate for paroxysmal atrial arrhythmia control. During the fifteenth day of treatment, an abrupt rise in the ventricular capture threshold with ventricular pacing failure was noted. The capture threshold decreased two days after discontinuation of flecainide acetate.     

Alternative approaches to treatment of paroxysmal atrial fibrillation

Choice of the optimal antiarrhythmic therapy still remains a challenge. Most frequently, antiarrhythmic agents used to reestablish and maintain sinus rhythm do not provide satisfactory clinical effect. Understanding electrophysiological mechanisms of initiation and maintenance of atrial fibrillation is the best way to develop optimal therapeutic approaches. This aim of this study was to assess the prospects of correcting paroxysmal (persistent) form of atrial fibrillation with termination treatment, ACE inhibitors, and omega-3-polyunsaturated fatty acids. The subjects of the study were 90 patients with documented episodes of atrial fibrillation of less than 48-hour duration. The observation lasted 12 months. The results show that "tablets in the pocket" strategy is the most effective and safe method of treatment of rare episodes of atrial fibrillation in patients with mild structural heart diseases; the terminating effectiveness of propanorm was 79% during hospital treatment and 88% in outpatients in the selected group of patients without a significant number of side effects. Treatment with lisinopril (dapril) was followed by a decrease in the number of paroxysms, duration of arrhythmia episodes, and a tendency to transformation into asymptomatic form. A possible mechanism of this positive effect of dapril on the paroxysmal form of atrial fibrillation is leveling of local electrophysiological effects of angiotensin II in a form of changing time of intra- and interventricular atrial conduction. Adding omega-3-polyunsaturated fatty acids to termination therapy decrease the number atrial fibrillation episodes and the time to their termination.     

经食管心房调搏治疗阵发性室上性心动过速

本文报告了78例阵发性室上性心动过速(PSVT)经食管心房调搏(TEAP)治疗的资料,其中除2例逆传型房室折返性心动过速需要伍用心律平外,均以短阵快速起搏法和超短阵猝发刺激法终止发作,总有效率100％,且操作简单、付作用小,几乎无并发症和禁忌症,对病态窦房结综合征合并PSVT发作者,转复过程一旦出现心脏停搏还可以立即经食管心房起搏,确保生命安全,因此建议在基层医院推广使用。     

动态心电图观察阵发性心房颤动的发生机制

目的:应用动态心电图观察阵发性房颤的发作特征,以探讨阵发性房颤的发生机制。方法:对41例阵发性房颤患者的动态心电图进行分析。男20例,女21例。平均年龄66±13岁。冠心病10例,高血压病8例,糖尿病3例,甲亢性心脏病2例。观察动态心电图中心律失常的特点及与阵发性房颤的关系。结果:41例患者的动态心电图均可见房性早搏。频发者23例,占56.1%(23/41)。伴阵发性心动过速及心房扑动30例,占73.2%(30/41)。伴房性早搏二联律,房性早搏未下传及长R-R间期的35例,占85.3%(35/41)。伴有窦性心动过缓11例,占26.8%(11/41)。结论:阵发性房颤的发生有多种因素,以房性心律失常最常见,其中又以房性早搏居多,早搏的联律间期越短,越容易诱发阵发性房颤。房性早搏二联律,房性早搏未下传及长R-R间期诱发阵发性房颤的原因可能为长短周期机制。部分病例存在窦性心动过缓,与阵发性房颤的关系可能是迷走神经张力增加参与影响的结果。     

心房颤动导管射频消融对心脏起搏器安全性影响的临床研究

目的评价植入起搏器患者经导管射频消融治疗慢性心房颤动(房颤)的安全性。方法18例永久性心脏起搏并房颤患者,其中男性12例,女性6例,年龄55～78岁,平均年龄68.67岁(标准差8.72岁)。分析其接受导管射频消融术中全程记录的心电信息,判断有无感知、起搏功能不良及房室失夺获、噪声反转等现象,并用起搏器程控仪于导管射频消融术前及术后第1天观察房室感知、起搏阈值及电极阻抗等参数的变化。结果18例患者均顺利完成导管射频消融,肺静脉前庭电学隔离率为100%。导管射频消融前后起搏器感知、起搏阈值及阻抗的变化无统计学意义(P>0.05)。导管射频消融过程中,3例(17%)出现噪声反转,3例(17%)出现感知不良,1例(6%)出现起搏功能不良致心室失夺获,均于停止放电后恢复正常。3例(17%)慢性持续性房颤患者在电复律后出现一过性感知不良。结论射频电流和电复律可引起一过性感知、起搏功能的障碍,但一般不引起起搏、感知阈值及电极阻抗的改变。对于已植入心脏起搏器的慢性房颤患者,在需行导管射频消融术时是安全的。