Surface ECG vector characteristics of organized and disorganized atrial activity during atrial fibrillation

Background: The aim of this study was to examine atrial organization from vectorcardiograms (VCGs) derived from the surface ECG of atrial fibrillatory waves. Methods: We retrieved ECGs recorded during ventricular asystole from 22 patients with AF undergoing ablation of the AV junction. The synthesized VCG of each f-wave cycle of each ECG and its plane of best fit, described by azimuth and elevation angles relative to the frontal plane, were computed. Results: Fifteen of the 22 ECGs had at least 30% of the planes in a single 30-degree region of azimuth angles. Of these 15, 12 had the greatest percentage of planes with azimuth angles within 30 degrees of the sagittal plane; two were near the frontal plane; and one near the right anterior oblique plane. Conclusions: Varying degrees of organization were observed from VCGs of fibrillatory waves with the more organized examples having planes predominately near the sagittal plane.     

阵发性心房颤动的动态心电图分析

目的 通过24 h动态心电图观察阵发性心房颤动,分析阵发性心房颤动的发作特点.方法 对32例阵发性心房颤动患者的24 h心房颤动的发生、持续时间和次数进行统计.结果 32例阵发性心房颤动患者心房颤动的发生和持续时间均有2个高峰,发生高峰在0∶00～1∶00和15∶00～16∶00,持续高峰在2∶00～4∶00和16∶00～18∶00时间段,终止高峰在8∶00～10∶00.结论 阵发性心房颤动的发作、持续均有2个高峰期,有着昼夜节律性规律,夜间发作多见于无器质性心脏疾病、年龄偏小、男性患者,持续时间较长的阵发性心房颤动多见于有器质性心脏疾病、老年患者.     

Conduction characteristics in atrial fibrillation

Background

Atrial fibrillation (AF) is one of the most common arrhythmias observed in clinical practice. The frequency of AF is increased in patients with impaired interatrial conduction. We aimed to investigate whether tissue Doppler echocardiography could be used for the evaluation of atrial conduction characteristics instead of an electrophysiological study, and to examine the predictive accuracy of tissue Doppler echocardiography for the inducibility of sustained AF.

Methods

We enrolled 86 consecutive patients who underwent an electrophysiological study. We performed electrocardiographic P wave dispersion, M-mode, two-dimensional, Doppler, and tissue Doppler echocardiography as well as an electrophysiological study (EPS) to evaluate the intra- and interatrial conduction times. We tried to induce AF, and the patients were categorized according to the inducibility of sustained (>?120 s) AF.

Results

We found a good correlation between intra-left atrial conduction time detected by tissue Doppler echocardiography (ILCT-echo) and by EPS (ILCT-eps; r?=?0.744, p?<?0.001), and a weak correlation between interatrial conduction times (IACT-echo and IACT-eps, r?=?0.396, p?<?0.001). In patients with inducible sustained AF, P wave dispersion (46?±?19 ms vs. 27?±?18, p?<?0.001), ILCT-echo (29?±?10 ms vs. 17?±?7 ms, p?<?0.001), and IACT-eps (47?±?11 ms vs. 36?±?13 ms, p?<?0.001) were found to be higher than those of the noninducible/nonsustained AF group. These three parameters were independent predictors of the inducibility of sustained AF.

Conclusion

We demonstrated that ILCT-echo could be used instead of ILCT-eps for the evaluation of left atrial conduction characteristics. We also showed that ILCT-eps could be a valuable parameter for predicting the development of long-lasting AF.     

房颤心电图诊断难点解析

根据典型的心电图表现易诊断房颤,但当房颤合并电解质紊乱、药物中毒或其他心律失常时,将给房颤临床诊断带来困难.鉴别这类心律失常对临床决策非常重要.本文主要针对房颤合并上述情况时的心电图改变进行简要阐述.     

无症状性房颤心电图筛查与诊断的研究进展

房颤是一种常见病,随着心血管危险因素的增加和人口老龄化进程,房颤在世界范围内的发病率正在上升.房颤患者发生缺血性卒中、心力衰竭、死亡和认知能力下降的风险增加;约1/3的房颤因无症状或隐匿而未能被及时发现和治疗.口服抗凝剂治疗可降低房颤患者发生缺血性卒中的风险和死亡率,因此,尽早筛查出无症状性房颤并早期确诊,对正规使用口服抗凝剂和预防缺血性卒中至关重要.目前,房颤的早期识别和治疗指南较少.本文综述了房颤心电检测、筛查和诊断方法方面的最新研究进展.     

P wave signal averaged ECG and chemoreflexsensitivity in paroxysmal atrial fibrillation

Detailed analysis of the QRS-complex and autonomic dysfunction can identify patients at risk to suffer from ventricular arrhythmias. To determine whether patients at risk for paroxysmal atrial fibrillation (PAF) could be identified while in sinus rhythm, a P wave triggered signal averaged ECG and an analysis of the autonomic function by chemoreflexsensitivity (CHRS) were examined. The ratio between the difference of RR intervals in the ECG and the venous partial pressure of oxygen before and after 5-min oxygen inhalation was measured for the determination of CHRS. We examined 224 patients (group A) who suffered from PAF, 250 patients (group B) without arrhythmic history and 30 young volunteers (group C). The filtered P wave duration (FPD) was significantly longer in group A than in group B (140.9+/-21.0 vs. 118.2+/-9.4 ms, p<0.0001) or C (105.2+/-14.1 ms, p<0.0001) while the root mean square voltage of the last 20 ms of the P wave (RMS 20) was significantly lower in group A than in group B (2.68+/-1.12 vs. 4.06+/-1.57 microV, p<0.0001) or C (3.97+/-1.36 microV, p<0.0001). Atrial late potentials (ALP) were defined as a FPD>120 ms and a RMS 20< or =3.5 microV. ALP could identify patients of group A with a specificity of 78% and a sensitivity of 83%. Patients with PAF (2.32+/-1.15 ms/mm Hg) showed a significantly lower CHRS than group B (4.14+/-1.58 ms/mm Hg, p<0.0001) or group C (4.98+/-1.51 ms/mm Hg, p<0.0001). The sensitivity for the presence of atrial fibrillation was 71% for a CHRS below 3.0 ms/mm Hg with a specificity of 70%. A combination of both methods showed a specificity of 85% and a sensitivity of 65% when ALP and pathological CHRS were present. The results of our study suggest that risk of atrial fibrillation could be detected by P wave signal averaged ECG and CHRS. An analysis of CHRS seems to be an appropriate method to demonstrate a neurovegetative imbalance, which might be one possible trigger mechanism.     

Prediction of atrial fibrillation in patients with cardiac dysfunctions: P wave signal-averaged ECG and chemoreflexsensitivity in atrial fibrillation.

AIMS: Atrial fibrillation (AF) is a common arrhythmia in advanced heart failure. The occurrence of AF increases the risk of death and hospitalization for patients with heart failure. The results of different studies indicated that patients with paroxysmal AF have a longer filtered P wave duration (FPD), a lower root mean square voltage of the last 20 ms of the P wave (RMS 20), and a lower chemoreflexsensitivity (CHRS). Our study bases on these observations in order to examine the methods for predicting AF in patients with a left ventricular ejection fraction below 40% without a prior documentation of AF. METHODS AND RESULTS: The ratio between the difference of RR intervals in ECG and venous pO(2) before and after 5-min oxygen inhalation was measured (ms/mmHg) in order to determine the CHRS. A P wave signal-averaged ECG was performed for the measurement of FPD and RMS 20. The measurements were only performed in 94 patients with sinus rhythm. AF occurred during the mean follow-up of 39.9 months in 24 patients (26%). There were no significant differences concerning age, heart diseases, sex, ejection fraction, heart rate, or the use of drugs. The FPD (130.3 +/- 4.2 vs. 118.9 +/- 12.4 ms, P < 0.0001) was significantly longer and the RMS 20 (3.03 +/- 0.95 vs. 3.83 +/- 1.58 microV, P = 0.02) was significantly lower in patients with AF than in sinus rhythm. The CHRS did not differ significantly between both groups (3.57 +/- 1.49 vs. 3.48 +/- 1.62 ms/mmHg, P = 0.81). The chi(2) test showed that the threshold of FPD>or=125 ms and RMS 20 or=125 ms and RMS 20 相似文献   

Oral anticoagulation for ECG tremor artefact simulating atrial fibrillation

That tremor simulates atrial fibrillation and causes oral anticoagulation has not been reported. In a 69-year-old patient with diabetes, arterial hypertension and recurrent strokes, hand tremor developed since 1998. In September 2000 atrial fibrillation was diagnosed upon a routine and 24-hour ambulatory ECG. Because of the additional risk factors for stroke/embolism, phenprocoumon was begun. The diagnosis was changed to paroxysmal AF upon the following ECGs, showing sinus rhythm. Not earlier than 1 year after establishing the diagnosis,"atrial fibrillation" was identified as being due to a tremor artefact. Phenprocoumon was discontinued. Neurological investigations revealed Parkinson's disease as the cause of the tremor. Three weeks after initiation of pramipexol, the tremor artefact was no longer visible on ECG. Misinterpreting an ECG-artefact due to Parkinsons's tremor as atrial fibrillation may be followed by unnecessary diagnostic and therapeutic procedures, including long-term oral anticoagulation. Upon adequate treatment of Parkinson's disease, the tremor artefact immediately disappears from the ECG.     

Signal-averaged P-wave ECG discriminates between persistent and paroxysmal atrial fibrillation.

Atrial fibrillation (Afib) has been associated with abnormal signal-averaged P wave (SAPW) parameters but whether SAPW is associated with the time course of these arrhythmias (persistent vs. paroxysmal, frequent vs. rare episodes) remains unknown. This article assesses the significance of SAPW duration in distinguishing patients with paroxysmal from those with persistent Afib. SAPW electrocardiogram was performed with a "double triggering" software system for acquisition and analysis of data. SAPW total duration (TD), X, Y, and Z leads magnitudes and vector signal magnitudes were measured offline. Optimal cutoff value between control and patient groups was determined by using a receiver operator characteristic curve. Data were analyzed to compare controls with patients groups and between patient groups according to time course of the arrhythmic history. Fifteen age-matched patients without a history of Afib and 55 patients with a history of Afib (33 with paroxysmal and 22 with persistent arrhythmia) were studied off antiarrhythmic drugs. Patients with history of persistent arrhythmia were studied within 2 days after electrical cardioversion to sinus rhythm. SAPW TD was the only parameter consistently associated with Afib. SAPW TD was 98 +/- 6 ms (mean +/- SD) in the control group, 127 +/- 19 ms in the pooled patients group (P =.0001); 122 +/- 20 ms for paroxysmal and 133 +/- 17 ms for the persistent Afib group (P =.04). Analysis of other SAPW parameters were not statistically significant. SAPW duration is a simple method to identify patients with history of Afib. A significantly longer SAPW TD characterizes patients with a history of persistent as opposed to paroxysmal Afib. Prolongation of SAPW TD possibly reflects more advanced electrophysiological changes, creating a more stable substrate that leads to persistence of the arrhythmia.     

Correlation of symptoms to ECG diagnosis following atrial fibrillation ablation

INTRODUCTION: Currently, definition of success following atrial fibrillation (AF) ablation is commonly based on the lack of symptoms. The purpose of this study was to evaluate the correlation between symptoms and the underlying rhythm after AF ablation. METHODS AND RESULTS: Eighty consecutive patients (pts) were treated for paroxysmal episodes of AF by segmental ostial ablation of all pulmonary veins and right atrial isthmus ablation. For 6 months pts transmitted transtelephonic (T-) ECG recordings in combination with comments daily or in the event of symptoms. Eligible comments were classified as: (1) asymptomatic, (2) symptomatic. Analysis was performed at 1-month intervals, defining an acute (first month) and chronic period (second to sixth month) after ablation. Overall 6,835 T-ECGs were analyzed. Of these 5,437 (79.5%) showed sinus rhythm (SR) and 1,398 (20.5%) showed AF. Pts in SR reported symptoms for 593 (10.9%) episodes, whereas 4,844 (89.1%) episodes were asymptomatic. During AF, 646 (46.2%) episodes were associated with symptoms, and 752 (53.8%) episodes remained asymptomatic. Exclusively asymptomatic were 7 (8.8%) pts. In 30 (52.6%) of 57 pts with AF, arrhythmic events were confined to the acute phase. Of the remaining 27 pts 14 (52%) reported an improvement, 12 (44%) the same, and 1 (4%) worsened symptoms after 3 months. A significant change (P < 0.01) toward more asymptomatic episodes from the acute (43.5%) to the chronic (57.5 +/- 4.5%) period was evident. CONCLUSION: Assessment of success after AF ablation cannot be based on the absence of symptoms due to a high prevalence of asymptomatic episodes.     

Diagnosis and characteristics of lone atrial fibrillation

Thirty-two patients with LAF were studied. Nineteen (59 percent) were male subjects. Mean age was 46.8 years. They were followed up for 2 to 16 years. On admission, most patients (94 percent) were symptomatic and had palpitations, nine had nonspecific chest pain, and five had syncope or near syncope. Left atrial size measured by echocardiography was less than 40 mm in all patients. During the follow-up period, only one patient had a complication, ie, cerebral embolism. We conclude that LAF may be regarded as a relatively benign form of AF. According to our study, one of its features is left atrial size not larger than 40 mm in echocardiography.     

Spatial characteristics of atrial fibrillation electrocardiograms

Background

The present study investigates spatial properties of atrial fibrillation (AF) by analyzing vectorcardiogram loops synthesized from 12-lead electrocardiograms (ECGs).

Methods

After atrial signal extraction, spatial properties are characterized through analysis of successive, fixed-length signal segments and expressed in loop orientation, that is, azimuth and elevation, as well as in loop morphology, that is, planarity and planar geometry. It is hypothesized that more organized AF, expressed by a lower AF frequency, is associated with decreased variability in loop morphology. Atrial fibrillation frequency is determined using spectral analysis.

Results

Twenty-six patients with chronic AF were analyzed using 60-second ECG recordings. Loop orientation was similar when determined from either entire 60- or 1-second segments. For 1-second segments, the correlation between AF frequency and the parameters planarity and planar geometry were 0.608 (P < .001) and 0.543 (P < .005), respectively.

Conclusions

Quantification of AF organization based on AF frequency and spatial characteristics from the ECG is possible. The results suggested a relatively weak coupling between loop morphology and AF frequency when determined from the surface ECG.     

Electroanatomic characteristics of atrial premature beats triggering atrial fibrillation in patients with persistent versus paroxysmal atrial fibrillation

APBs in Persistent Versus Paroxysmal AF. BACKGROUND: Although the electrical disconnection between the left atrium (LA) and pulmonary veins (PVs) by radiofrequency catheter ablation has been proven to be effective in controlling atrial fibrillation (AF), the recurrence rate is higher in patients with persistent AF (PeAF) than with paroxysmal AF (PAF). We hypothesized that the origin of the atrial premature beats (APBs) that trigger AF and the pattern of their breakthrough into the LA differ between PAF and PeAF. METHODS: We mapped 75 APBs (53 APBs triggering AF, 22 isolated APBs) from the LA and PVs in 26 patients with AF (age: 49.5 +/- 9.6, males: 23, PAF = 17, PeAF = 9), using a noncontact endocardial mapping (NCM) system. The location of the preferential conduction (PC) sites and their conduction velocity (CV) were compared. RESULTS: In patients with PeAF, the earliest activation (EA) site and exit of the PC were more frequently located on the LA side of the LA-PV junction as compared with PAF (P < 0.001). Eighty-one percent of the PCs were located in the area between the left and right superior PVs. The incidence of PCs was similar between the PeAF and PAF patients (P = NS). PCs were more commonly found with APBs inducing AF (63.3%) than with those not inducing AF (35.2%, P = 0.01). The CV of the PC was slower for PeAF than PAF (P < 0.001). The CV in the LA during sinus rhythm was also slower for PeAF than PAF (P < 0.01). CONCLUSION: PeAF was more frequently triggered by APBs from the LA side of the LA-PV junction than PAF and resulted in slower conduction than did PAF. These findings may help explain the higher potential for recurrence after electrical PV isolation in patients with PeAF.     

Enhanced dispersion of atrial refractoriness as an electrophysiological substrate for vulnerability to atrial fibrillation in patients with paroxysmal atrial fibrillation.

Atrial electrical remodeling plays a part in recurrence of atrial fibrillation (AF). It has been related to an increase in heterogeneity of atrial refractoriness that facilitates the occurrence of multiple reentry wavelets and vulnerability to AF. AIM: To examine the relationship between dispersion of atrial refractoriness (Disp_A) and vulnerability to AF induction (A_Vuln) in patients with clinical paroxysmal AF (PAF). METHODS: Thirty-six patients (22 male; age 55+/-13 years) with > or =1 year of history of PAF (no underlying structural heart disease--n=20, systemic hypertension--n=14, mitral valve prolapse--n=1, surgically corrected pulmonary stenosis--n=1), underwent electrophysiological study (EPS) while off medication. The atrial effective refractory period (AERP) was assessed at five different sites--high (HRA) and low (LRA) lateral right atrium, high interatrial septum (IAS), proximal (pCS) and distal (dCS) coronary sinus--during a cycle length of 600 ms. AERP was taken as the longest S1-S2 interval that failed to initiate a propagation response. Disp_A was calculated as the difference between the longest and shortest AERP. A_Vuln was defined as the ability to induce AF with 1-2 extrastimuli or with incremental atrial pacing (600-300 ms) from the HRA or dCS. The EPS included analysis of focal electrical activity based on the presence of supraventricular ectopic beats (spontaneous or with provocative maneuvers). The patients were divided into group A--AF inducible (n=25) and group B--AF not inducible (n=11). Disp_A was analyzed to determine any association with A_Vuln. Disp_A and A_Vuln were also examined in those patients with documented repetitive focal activity. Logistic regression was used to determine any association of the following variables with A_Vuln: age, systemic hypertension, left ventricular hypertrophy, left atrial size, left ventricular function, duration of PAF, documented atrial flutter/tachycardia and Disp_A. RESULTS: There were no significant differences between the groups with regard to clinical characteristics and echocardiographic data. AF was inducible in 71% of the patients and noninducible in 29%. Group A had greater Disp_A compared to group B (105+/-78 ms vs. 49+/-20 ms; p=0.01). Disp_A was >40 ms in 50% of the patients without A_Vuln and in 91% of those with A_Vuln (p=0.05). Focal activity was demonstrated in 14 cases (39%), 57% of them with A_Vuln. Disp_A was 56+/-23 ms in this group and 92+/-78 ms in the others (p=0.07). Using logistic regression, the only predictor of A_Vuln was Disp_A (p=0.05). CONCLUSION: In patients with paroxysmal AF, Disp_A is a major determinant of A_Vuln. Nevertheless, the degree of nonuniformity of AERP appears to be less important as an electrophysiological substrate for AF due to focal activation.     

老年阵发性房颤患者体表心电图f-f间期变化与房颤持续时间及心房电重构的关系

目的 :研究老年阵发性房颤 （PAF）患者体表心电图 f- f间期变化与房颤持续时间及心房电重构的关系。方法 :选择无心房扩大 ,患有初发或新近发生的 PAF的老年人 ,于随访期前后分别进行 2 4 h Holter监测 ,同意者行心脏电生理检查测右房有效不应期 （ERP） ,随访半年。结果 :入选 32例 ,有 9例于随访期前后行心电生理检查 ,5例失访。采集到以下数据 :2 4 h房颤发作次数 （N）较基线没有显著变化 （2 4± 4 vs 2 4± 4 ,P>0 .0 5 ） ;2 4 h房颤发作累计时间 （TT）显著延长 （2 36± 32 m in vs 2 89± 31min,P<0 .0 1） ;最长一次发作持续时间 （L T）无显著差异 （4 2± 12min vs 4 5± 12 min,P>0 .0 5 ） ;2 4 h平均持续时间 （MT）显著延长 （8.1± 1.2 m in vs 10 .2± 1.6 min,P<0 .0 1） ;平均 f- f间期 （Mf- f）显著缩短 （0 .15± 0 .0 2 s vs0 .11± 0 .0 1s,P<0 .0 5 ）。ERP与对照相比显著缩短 （2 0 8± 11ms vs191± 8ms,P<0 .0 1）。Δ ERP与 Δf- f呈直线正相关 :r=0 .8839,P<0 .0 1,Δ TT与 Δ f- f直线正相关 :r=0 .76 0 4 ,P<0 .0 1,ΔMT与 Δ f- f直线正相关 :r=0 .76 0 ,P<0 .0 1。结论 :老年 PAF患者体表心电图 f- f间期缩短可作为预测老年人 PAF持续时间延长和反映心房发生电重构的有效指标。     

阵发性房颤患者心电图P波形态的分析

目的 探讨体表心电图P波形态与阵发性心房颤动(PAF)的关系.方法 选择52例非瓣膜性阵发性房颤患者及47例无PAF的对照组患者,测定窦性心律时12导联心电图P波离散度(Pd),最大P波时限( Pmax),V1导联P波终末电势(Ptfv1)及aVR导联P波面积和振幅,超声心动图测定左房内径(LAD)、左室舒张末期内径(...     

P wave signal-averaged ECG in normal population and in patients with converted atrial fibrillation

Background: Signal‐averaged electrocardiography of the P wave (P wave SAECG) is a noninvasive method for evaluating the risk of atrial fibrillation (AF). We aimed to study P wave SAECG parameters in a large number of apparently healthy subjects and to compare them with patients with converted AF. Methods: We examined 591 individuals; P wave SAECG were recorded in 330 normal subjects, 31 patients with converted persistent AF and 57 patients with converted paroxysmal AF immediately after conversion, at 12 and 24 hours after conversion, then after 3 and 6 months. P wave SAECG were recorded using a commercially available machine aiming to obtain a noise level <1 μV. Results: In the normal population the duration of the filtered P wave (PWD) was higher in men. P wave duration, RMS₄₀ and RMS₃₀ were significantly correlated with age. By comparing the normal population with patients with persistent AF converted to sinus rhythm we demonstrated significant differences in PWD and P wave integral. Patients with recurrent persistent AF had significantly higher PWD. The study of patients with paroxysmal AF, compared to the control group, showed significant increase of the same parameters: PWD and integral of the P wave. Patients with recurrent paroxysmal AF had higher PWD and lower RMS₄₀, RMS₃₀, RMS₂₀. Conclusions: Filtered P wave duration was higher in men; PWD was weakly but significantly correlated with age. Patients with paroxysmal or persistent AF converted to sinus rhythm had significantly higher P wave duration and P wave integral. Ann Noninvasive Electrocardiol 2011;16(4):351–356