Left atrial mechanical function after brief duration atrial fibrillation

ObjectivesThis study examined the effect of brief duration atrial fibrillation on left atrial and left atrial appendage mechanical function in humans with structural heart disease.BackgroundLeft atrial dysfunction and the development of spontaneous echo contrast (SEC) may follow the cardioversion of atrial fibrillation (AF) to sinus rhythm. This phenomenon has been termed “stunning” and is implicated in the development of atrial thrombus and embolic stroke. The effects of brief duration AF on left atrial mechanical function in humans are unknown.MethodsTwenty-four patients (23 men, aged 59.1 ± 12.7 years) with significant structural heart disease (ejection fraction 31.2 ± 9.0%, left atrial diameter 4.9 ± 0.4 cm) undergoing implantation of a ventricular cardiodefibrillator underwent transesophageal echocardiography to evaluate left atrial appendage emptying velocities (LAAeV) and SEC before, during and after a 15-min period of AF induced by rapid right atrial pacing. Atrial fibrillation was then permitted to terminate spontaneously within 5 min or was reverted with an endocardial direct current shock. Velocities and SEC were assessed in sinus rhythm pre-AF, during AF and immediately, 5 and 10 min after reversion to sinus rhythm.ResultsAtrial fibrillation terminated spontaneously in 10 patients after 16.1 ± 1.0 min. Endocardial direct current (DC) cardioversion of 10.4 ± 6.4 J was required in 14 patients after AF lasting 20 min. Mean LAAeV pre-AF (50.0 ± 17.5 cm/s) was not significantly different to LAAeV immediately (52.8 ± 16.7 cm/s), 5 min (54.3 ± 16.4 cm/s) or 10 min (53.7 ± 15.7 cm/s) after reversion to sinus rhythm. Atrial stunning defined as a reduction in LAAeV of >20% was not observed in any patient. Fourteen of 24 patients (58%) developed SEC during AF, which resolved within 30 s of AF termination. There were no significant differences between LAAeV in those patients reverting with DC shock (pre-AF 50.6 ± 16.2 cm/s vs. immediately post-AF 54.7 ± 16.6 cm/s) or in those patients with spontaneous reversion (pre-AF 48.9 ± 20.2 cm/s vs. immediately post-AF 49.8 ± 17.3 cm/s).ConclusionsSignificant left atrial stunning was not observed after brief duration AF in humans with structural heart disease. Transient left atrial SEC develops in a significant proportion of these patients during AF but resolves rapidly on reversion to sinus rhythm. These findings suggest that the risk of thromboembolism may be low after brief duration AF that terminates either spontaneously or with an endocardial DC shock even in patients with significant structural heart disease. These findings have important implications for recipients of implantable devices that are capable of atrial defibrillation in response to AF.     

Left atrial appendage anatomy and function: short term response to sustained atrial fibrillation

OBJECTIVE—To determine whether there is significant atrial or atrial appendage enlargement or functional remodelling as a result of one to two months of sustained atrial fibrillation, a duration similar to that experienced by patients undergoing warfarin anticoagulation before elective cardioversion.
METHODS—To test the hypothesis that left atrial and left atrial appendage enlargement develop as a result of short term atrial fibrillation, serial anatomical and functional indices were measured using transoesophageal echocardiography (TOE) in 20 patients with recent onset atrial fibrillation (14 men, six women; mean (SEM) age 67 (2) years). Serial TOE was performed 2.5 months apart in patients with sustained atrial fibrillation.
RESULTS—There was no significant change in left atrial area (23.7 cm² to 24.1 cm², p = 0.98); length (5.7 cm to 5.7 cm, p = 0.48); width (5.2 cm to 5.2 cm, p = 0.65); volume (83 cm³ to 87 cm³, p = 0.51) or left atrial appendage area (7.9 cm² to 8.1 cm², p = 0.89); length (4.6 cm to 4.5 cm, p = 0.8); or width (2.5 to 2.4 cm, p = 0.87). Peak left atrial appendage velocity ejection (0.2 m/s to 0.2 m/s, p = 0.57), and presence of severe spontaneous echo contrast in the left atrial appendage (n = 15 (75%) to n = 13 (72%)) were also not significantly different. There was no correlation between changes in left atrial or left atrial appendage dimensions.
CONCLUSIONS—In the setting of sustained atrial fibrillation, significant left atrial and left atrial appendage functional and anatomical remodelling do not occur with atrial fibrillation of a duration similar to that used for conservative anticoagulation in preparation for cardioversion.


Keywords: atrial fibrillation; left atrial appendage; remodelling     

阵发性心房颤动射频消融术后左房大小和机械功能变化

目的探讨经导管射频消融术对阵发性心房颤动（房颤）患者左房功能的影响,并比较肺静脉口节段性电隔离（SPVI）和环肺静脉消融（CPVA）两种术式在此方面的异同。方法66例阵发性房颤患者接受射频消融手术治疗。应用经胸心脏超声检查测量患者术前、术后1天、1个月和3个月时的左房前后径、左房面积、舒张晚期跨二尖瓣血流峰速（A峰）和舒张晚期心肌组织运动峰速（A’峰）。结果66例患者中,30例接受SPVI术,36例接受CPVA术。两组患者一般临床情况及术前超声参数相似。术后随访（315±153）d,SPVI组和CPVA组无房性心律失常复发率相似（70％与75％,P=0．650）。两组在手术后左房面积均较术前缩小,SPVI组发生于术后1个月,而CPVA组于术后3个月。SPVI组左房直径也显示出明显缩小（P〈0．05）,而CPVA组术前和术后则差异无统计学意义。左房机械功能方面,CPVA组于术后1天A峰和A’峰明显降低（P〈0．05）,两者均于3个月后较术后1天明显回升,A峰恢复至术前水平,A’峰较术前有明显升高。SPVI组术后1天没有出现A峰和A’峰明显降低;其A峰于术后1个月升高,并保持至3个月;A’峰于术后3个月时升高。结论阵发性房颤经导管SPVI术和CPVA术治疗后3个月,可以出现左房面积缩小和收缩功能改善。CPVA术比SPVI术造成了更多的左房损伤,表现为术后1天左房功能的下降以及术后左房大小、功能参数改善的延迟。     

心房颤动自发复律对老年患者左房功能的影响

目的本文探讨老年患者心房颤动自发复律后心房功能恢复的特点.方法采用SONOS 5500型彩色多普勒血流显像仪,观察20例老年对照组和20例非瓣膜病阵发性心房颤动(PAF)患者在心房颤动自发复律后24 h,72 h及7 d左心房收缩功能.观察以下指标:①左房内径LAD和左室内径LVD;②左室射血分数(LVEF);③二尖瓣E峰峰值速度E(cm/s);④二尖瓣A峰峰值速度A(cm/s);⑤取心尖四腔切面AQ技术观察左房:左房最大容积LAVmax,左房最小容积LAVmin,左房收缩期前容积LAVp,左房主动排空容积LAAEV=LAVp-LAVmin,左房主动排空分数LAAEF(%)=LAAEV/LAVp.结果老年PAF组较老年对照组左房内径[(4.24±0.43)cm vs(3.83±0.22)cm,P＜0.05]及左房容积[(70.43±12.70)ml vs(46.2±4.91)ml,P＜0.05]增大;二尖瓣峰流速A(cm/s)在心房颤动自发复律后24 h,48 h明显降低,7 d有所增高,但仍较对照组低[(45.4±12.37)cm/s;(56.64±16.24)cm/s;(65.01±13.58)cm/s vs(74.55±5.97)cm/s,P＜0.05];老年PAF组自发复律后LAAEF(%)降低,至7 d部分恢复,仍较对照组明显降低[(15.72±5.22)%;(16.42±5.20)%;(18.89±7.70)% vs(34.65±7.83)%,P＜0.05].结论老年心房颤动患者左房内径和左房容积增大,心房颤动自发复律7 d时LAAEF仍降低.由于自发复律后仍存在左房收缩功能障碍,且窦性心律难以维持,因此对于左房容积增大的老年PAF患者,抗凝治疗非常重要.     

Left ventricular function in atrial fibrillation during overdrive pacing

Objective Our purpose was to measure the effect of ventricular pacing in patients with atrial fibrillation (AF) on stroke volume and cardiac output. Background Unceasing variation in cycle length in AF decreases stroke volume and cardiac output. Because ventricular-inhibited pacing after atrioventricular node ablation has been reported to improve left ventricular performance, we tested the hypothesis that overdrive pacing would produce a similar benefit by regularizing cycle length. Methods and Results We studied 18 patients with chronic AF and permanent pacemakers. The aortic time velocity integral (TVI) was measured with continuous-wave Doppler and was used as a surrogate measure of stroke volume (stroke volume = TVI × aortic valve area, and aortic valve area is constant whether in AF or during pacing). For each patient, the linear relation between preceding cycle length and TVI in AF was used to estimate relative stroke volume (TVI compared within each patient) at a preceding cycle length of 666 ms in AF, and a similar comparison between AF and pacing was made at the minimum allowable pacing rate. Relative stroke volume in AF was then compared with relative stroke volume at both the fixed cycle (666 ms) and the minimum allowable rate. During pacing at 666 ms, relative stroke volume increased significantly by 18% (t = 2.8, P = .048), but there was no difference in cardiac output during pacing at the minimum possible rate and the corresponding preceding cycle length in AF. Conclusion Our data suggest that regularization of ventricular rhythm by overdrive pacing in patients with AF only improves stroke volume (and by extension, cardiac output) at pacing rates at the outer limit of and above the normal physiologic range. (Am Heart J 2002;143:827-32.)     

肥厚型心肌病合并心房颤动导管消融术后复发的相关因素分析

目的 探讨国人肥厚型心肌病(HCM)合并心房颤动(房颤)患者导管消融术的疗效及术后心律失常复发的危险因素.方法 纳入2005年6月至2013年6月在北京安贞医院行导管消融术的HCM合并房颤患者共40例(阵发性房颤27例,持续性房颤13例).阵发性房颤的消融策略为双侧环肺静脉隔离(PVI)持续性房颤的消融策略为PVI基础上加行左心房顶部、二尖瓣峡部和三尖瓣峡部线性消融.术后以常规心电图和长程心电图随访患者心律失常复发情况,用回归分析方法甄别与心律失常复发相关的危险因素并检测其预测效力.结果 单次消融术后随访(34±18)个月,窦性心律维持率为30％ (12/40),64.3％ (18/28)的心律失常复发出现在消融术后1年.Cox多因素分析显示左心房内径(LAD)和女性是术后快速房性心律失常复发的独立危险因素(LAD:HR=1.124,95％ CI1.051～1.202,P=0.001;女性:HR=3.304,95％CI1.397 ～7.817,P=0.007).其中LAD的截断值为43.5 mm时的预测敏感度为93.5％,特异度为60.0％;LAD每增加1 mm,心律失常复发的风险比为1.095(95％CI1.031～1.163,P=0.003).结论 HCM合并房颤行导管消融术虽安全可行,但单次手术后长期随访的窦性心律维持率较低,大部分心律失常复发出现在术后1年内,左心房内径增大和女性是术后复发的独立危险因素.     

非瓣膜性房颤患者左心耳超声特征与复律后窦性心律维持的关系

目的探讨非瓣膜性房颤患者左心耳超声特征评估复律后窦性心律维持的价值。方法利用多平面经食管超声心动图观察45例患者的左心耳,根据左心耳血流频谱观察清晰型和模糊型患者复律后1、3、6个月内窦性心律维持情况,并作比较分析。结果与清晰型患者相比,模糊型患者的左心耳充盈血流峰速、排血峰速及左心耳面积变化率显著减小,左心耳内径及面积增大,SEC现象检出率显著增高,复律后1、3、6个月内房颤复发率也明显增高（P＜0．05）。结论了解非瓣膜房颤患者的左心耳改变特征有助干预测复律后窦性心律的维持．提示左心耳超声多普勒检测可以作为复律的参考指标。     

Left atrial pacemaker dominance after catheter ablation of atrial fibrillation

We report a case of left atrial dominant rhythm demonstrated by electroanatomic mapping. The rhythm occurred after radiofrequency catheter ablation in a patient with persistent atrial fibrillation and structural heart disease.     

Left atrial function and ventricular filling in hypertensive patients with paroxysmal atrial fibrillation

Objectives. We evaluated left atrial dimensions and function, as well as left ventricular structure and filling, in hypertensive patients with paroxysmal atrial fibrillation.Background. In hypertensive patients, left atrial dilation and enhanced volume transport may facilitate arrhythmias.Methods. Left ventricular two-dimensional and M-mode echocardiograms and pulsed Doppler echocardiography of transmitral flow were performed in 17 consecutive primary hypertensive patients with paroxysmal atrial fibrillation (group EHf) and in 34 patients with high blood pressure without this arrhythmia (group EH). Seventeen normal subjects (group N) were also investigated. Groups were matched for age and gender.Results. The EH and EHf groups had similar systolic arterial pressures ([mean ± SD] group EH 185 ± 27, group EHf 173 ± 25 mm Hg, p = NS) and left ventricular mass index (group EH 154 ± 55, group EHf 131 ± 57.8 g/m², p = NS), and their M-mode left ventricular systolic wall stress and fractional shortening were comparable to those of normal subjects. M-mode left atrial maximal (group N 37.8 ± 6, group EH 37.9 ± 4.6, group EHf 44.6 ± 6.7 mm, p < 0.05 for group EHf vs. groups N and EH) and minimal diameters and the diameter preceding atrial contraction (group N 31 ± 3.6, group EH 34.5 ± 5, group EHf 40.4 ± 6.9 mm, p < 0.001 for group EHf vs. group N; p < 0.05 for group EHf vs. group EH) were greater in group EHf than in group EH and group N subjects, whereas only the latter diameter was increased in group EH (p < 0.05 vs. group N), so that left atrial fractional shortening was higher than normal only in group EH (group N 10.8 ± 4.4%, group EH 14.6 ± 5.5%, group EHf 9.3 ± 5.3%; group EH vs. group N, p < 0.05; group EHf vs. group EH, p < 0.05). The pulsed Doppler ratio of early to late transmitral flow rates (E and A wave velocity/time integrals × mitral annulus area) was lower than normal in group EH (group N 2.9 ± 2.2, group EH 1.75 ± 0.8, group EHf 2.8 ± 0.8; group EH vs. group N, p < 0.05; group EHf vs. group EH, p < 0.001; group EHf vs. group N, p = NS) and was “normalised” in group EHf, early flow being increased in this group (group N 42 ± 13, group EH 39 ± 29, group EHf 60 ± 17 ml; group EHf vs. group N, p < 0.05; group EHf vs. group EH, p < 0.05).Conclusions. These results suggest that the occurrence of paroxysmal atrial fibrillation in hypertension is associated with enlargement of the left atrium, depression of its contractile function and “normalization” of the pattern of left ventricular filling and is independent of left ventricular hypertrophy and systolic wall stress. The mechanisms linking these variables remain undefined.