左心耳电隔离在持续性心房颤动治疗中的研究进展

肺静脉隔离是心房颤动(房颤)导管消融的基石,对于阵发性房颤有良好效果,但在持续性房颤中的效果则不尽人意.肺静脉隔离以外的辅助消融策略有助于提高持续性房颤的手术成功率.左心耳不仅是心腔内血栓的常见起源,还是导致快速性房性心律失常发生或维持的因素,因而左心耳电隔离成为持续性房颤辅助消融策略之一,研究表明其可能有助于提高持续...     

Morphological changes of the left atrial appendage after catheter ablation of atrial fibrillation

Introduction: The left atrial appendage (LAA) has been proven to be the most important site of thrombus formation in patients with atrial fibrillation (AF). However, the information regarding the morphometric alteration of the LAA related to the outcome of AF ablation is still lacking. Thus, we evaluated the long-term changes of the LAA morphology in patients undergoing catheter ablation of AF using magnetic resonance angiography (MRA).
Methods and Results: Group 1 included 15 controls without any AF history. Group 2 included 40 patients with drug-refractory paroxysmal AF. They were divided into two subgroups: group 2a included 30 patients without AF recurrence after pulmonary vein (PV) ablation. Group 2b included 10 patients with late recurrence of AF. The LAA morphology before and after (20 ± 11 months) ablation was evaluated by three-dimensional MRA. The group 2 patients had a larger baseline LAA size (including the LAA orifice, neck, and length) and less eccentric LAA orifice and neck. After the AF ablation, there was a significant reduction in the LAA size in the group 2a patients, and the morphology of the LAA neck became more eccentric during the follow-up period. In group 2b, the LAA size increased and no significant change in the eccentricity of the orifice and neck could be noted.
Conclusions: The morphometric remodeling of the LAA in the AF patients could be reversed after a successful ablation of the AF. Progressive dilation of the LAA was noted in the patients with AF recurrence. These structural changes in the LAA may play a role in reducing the potential risk of cerebrovascular accidents.     

Non-surgical left atrial appendage closure for stroke prevention in atrial fibrillation

Non-Surgical Left Atrial Appendage Closure for Stroke Prevention in Atrial Fibrillation. The most feared complication associated with atrial fibrillation (AF) is stroke, the risk of which increases with advanced age. Because of its complex anatomy and diminished blood flow during AF, the left atrial appendage (LAA) has been a common site of left atrial thrombi and presumed source of thromboembolism. Systemic anticoagulation to treat what may be largely a localized phenomenon is associated with significant complications. Newer anticoagulation agents hold great promise in facilitating dosing and eliminating drug and food interactions, but do not eliminate bleeding risk. These challenges have led to interest in mechanical exclusion of the LAA as a means of preventing thromboembolism in AF. Although surgery permits greater visualization and management of complications, the potential morbidity has limited adoption in often-frail elderly patients. In this paper, we review the current state of percutaneous left atrial exclusion for stroke prevention in AF, and the strengths and limitations of each of these strategies. The nonsurgical approaches to excluding the LAA from the central circulation can be divided into 3 broad categories: transseptally placed devices, percutaneous epicardial approach, and hybrid approaches. The availability of several approaches will allow physician selection of the optimal approach for a given patient based on clinical, physiological, and anatomical considerations. LAA exclusion stands to become an increasingly attractive option for patients with nonvalvular AF because it can be offered to elderly AF patients, and eliminates the long-term cumulative bleeding risks and adherence challenge of anticoagulants.     

Role for the left atrial appendage occlusion device in managing thromboembolic risk in atrial fibrillation

Only 50% of patients who would benefit from warfarin therapy for atrial fibrillation (AF) receive treatment because of clinical concerns regarding chronic anti-coagulation. Percutaneous strategies to treat AF, including pulmonary vein isolation with a curative intent or atrioventricular nodal ablation and implantation of a permanent pacemaker for palliative rate control, have not eliminated the need to manage thromboembolic risk. With the development of a percutaneous left atrial appendage (LAA) occlusion device (the WATCHMAN percutaneous left atrial appendage occluder - Atritech Inc., Plymouth, MN, USA) for thromboembolic protection in non-valvular AF a significant therapeutic option for select patients may be available. We present the first case performed in Australia (24 November 2009) and explore this new methodology.     

Surgical clip closure of the left atrial appendage

Atrial fibrillation (AF) is the most common atrial arrhythmia, but it is not a benign disease. AF is an important risk factor for thromboembolic events, causing significant morbidity and mortality. The left atrial appendage (LAA) plays an important role in thrombus formation, but the ideal management of the LAA remains a topic of debate. The increasing popularity of surgical epicardial ablation and hybrid endoepicardial ablation approaches, especially in patients with a more advanced diseased substrate, has increased interest in epicardial LAA management. Minimally invasive treatment options for the LAA offer a unique opportunity to close the LAA with a clip device. This review highlights morphologic, electrophysiologic, and surgical aspects of the LAA with regard to AF surgery, and aims to illustrate the importance of surgical clip closure of the LAA.     

Influence of age on left atrial appendage function in patients with nonvalvular atrial fibrillation

BACKGROUND: Age is an independent risk factor for thromboembolism in nonvalvular atrial fibrillation (NVAF). An association between low left atrial appendage (LAA) Doppler velocities and thromboembolic risk in NVAF has been reported. Hypothesis: The study was undertaken to identify age-related differences in LAA function that may explain the higher thromboembolic rates in older patients with NVAF. METHODS: Forty-two consecutive patients (age 69+/-2 years [range 42-92], 24 [57%] men) with NVAF underwent transthoracic and transesophageal echocardiography. The following were compared in 22 patients younger and 20 older than 70 years: left ventricular (LV) diameter, mass and ejection fraction, left atrial (LA) diameter and volume, LAA area and volume, LAA peak emptying (PE) and peak filling (PF) velocities, presence and severity of spontaneous echo contrast (SEC) and mitral regurgitation (MR). RESULTS: Left atrial diameter (4.6+/-0.1 vs. 4.5+/-0.2 cm), LA volume (105+/-10 vs. 92+/-8 ml), LAA area (6.8+/-0.6 vs. 5.2+/-0.8 cm2), and LAA volume (5.6+/-0.9 vs. 3.9+/-1.0 ml) were similar (p>0.05) in both groups. Older patients had lower LAA PE (26+/-2 vs. 34+/-3 cm/s, p = 0.02) and PF (32+/-2 vs. 41+/-4 cm/s, p = 0.04) velocities, lower LV mass (175+/-13 vs. 234+/-21 gm, p = 0.02), higher relative wall thickness (0.52+/-0.02 vs. 0.43+/-0.03, p = 0.02), smaller LV diastolic diameter (4.3+/-0.1 vs. 5.2+/-0.2 cm, p < 0.001), and higher LV ejection fraction (62+/-2 vs. 55+/-2%, p = 0.025). Frequency and severity of SEC and MR were similar in both groups. Multivariate analysis identified older age as the only significant predictor of reduced LAA velocities. CONCLUSION: Compared with younger patients, older patients with NVAF have lower LAA velocities despite higher LV ejection fraction, smaller LV size, and similar LA and LAA volumes. These findings may explain the higher thromboembolic rates in older patients with NVAF.     

Transcatheter left atrial appendage occlusion with Amplatzer devices to obviate anticoagulation in patients with atrial fibrillation.

It is assumed that over 90% of clinically apparent embolisms in atrial fibrillation originate from the left atrial appendage. Recently, a percutaneous method (PLAATO technique) to occlude the left atrial appendage to the end of preventing thromboembolic complications of atrial fibrillation has been introduced into clinical practice. This technique is quite intricate and requires general anesthesia. The Amplatzer atrial septal occluder lends itself for a more simple approach to this intervention. The first 16 patients treated at four centers are described. Their age varied from 58 to 83 years. All suffered from atrial fibrillation but eight of them were in sinus rhythm at the time of implantation. All but two procedures were done under local anesthesia of the groin only. There was one technical failure (device embolization) requiring surgery. All other patients left the hospital a day after the procedure without complications. There were no problems or embolic events during an overall follow-up of 5 patient-years and all left atrial appendages were completely occluded without evidence of thrombosis at the atrial side of the device at the latest follow-up echocardiography. With the Amplatzer technique, the left atrial appendage can be percutaneously occluded with a venous puncture under local anesthesia, without echocardiographic guidance, and at a reasonable risk. It remains to be evaluated in larger series or randomized trials how the simpler Amplatzer technique compares with the complex PLAATO technique, and whether left atrial appendage closure is competitive with oral anticoagulation with warfarin or the novel ximelagatran to prevent thromboembolism in atrial fibrillation.     

Percutaneous management of late leak after lariat transcatheter ligation of the left atrial appendage in patients with atrial fibrillation at high risk for stroke

Left atrial appendage (LAA) occlusion or ligation is a novel approach to stroke prevention in atrial fibrillation that may obviate the need for long‐term anticoagulation. The Lariat device has received Food and Drug Administration 510K clearance for the approximation of soft tissue and has been applied to transcatheter LAA ligation using a combined trans‐pericardial and transseptal approach. The occurrence of late leak after transcatheter LAA ligation and its percutaneous management has not been previously reported. Herein, we report three cases of late leak with reconstitution of the LAA after initially successful Lariat closure, and present a simple percutaneous technique for leak closure. © 2013 Wiley Periodicals, Inc.     

Effects of heart rate on flow velocity of the left atrial appendage in patients with nonvalvular atrial fibrillation

Background and hypothesis: Flow velocity of the left atrial appendage (LAA) is thought to be important in thrombus formation in association with blood stasis and the development of spontaneous echo contrast. The effects of heart rate on peak flow velocity of the LAA have not been studied in patients with nonvalvular atrial fibrillaton. Methods: Using transesophageal Doppler echocardiography, peak flow velocity of the LAA was measured at the junction between the left atrium and the LAA during left ventricular (LV) systole and diastole in 21 patients with nonvalvular atrial fibrillation. In six cases, the average peak flow velocity of the LAA for 10 consecutive beats with moderately long R-R intervals (LI beats) was compared with those for 3-5 consecutive beats with extremely short R-R intervals (SI bets). Results: Average peak flow velocity of the LAA during LV diastole was significantly higher than that during LV systole (26.5 ± 15.7 vs. 19.3 ± 10.4 cm/s, p<0.01). In SI beats, average peak flow velocity of the LAA was significantly lower than that in LI beats (17.1 ± 12.1 vs. 21.2 ± 12.9 cm/s, p<0.01). Conclusion: An increased heart rate reduced the peak flow velocity of the LAA in patients with nonvalvular atrial fibrillation, which would promote blood stasis in the LAA.     

经食管超声心动图检测左心耳功能评估非风湿性房颤的栓塞危险性

目的 :探讨经食管超声心动图 （TEE）测定左心耳 （L AA ）功能用于评估非风湿性心房颤动 （房颤 ）患者栓塞危险性的价值。方法 :46例非风湿性房颤患者同时接受常规经胸超声心动图 （TTE）及 TEE检查。根据 TEE测定的L AA血流排空速率将患者分为低流速组 （<2 5 cm/ s,n=18）和高流速组 （≥ 2 5 cm/ s,n=2 8） ,对两组间心房血栓和左房自发性超声对比现象 （L ASEC）检出率及其它预示栓塞危险性的临床 ,TTE指标进行对比分析。结果 :低流速组心房血栓及 L ASEC检出率显著高于高流速组 （P<0 .0 1）。L AA面积扩大与其排空速率降低密切相关 （r=- 0 .5 44 ,P<0 .0 1）。继往栓塞事件、左室功能不全和左房扩大均以低流速组明显 （P<0 .0 5 ） ,而年龄、高血压病史、糖尿病病史在两组间未存在显著差异 （P>0 .0 5 ）。结论 :TEE测定左心耳功能有助于区分非风湿性房颤患者中的栓塞高危人群。     

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     

The feasibility of tissue Doppler acceleration as a new predictor of thrombogenesis in the left atrial appendage associated with nonvalvular atrial fibrillation

BACKGROUND: Tissue acceleration utilizing the tissue Doppler imaging (TDI) technique is a new marker of ventricular contraction. We evaluated whether the left atrial appendage (LAA) wall acceleration was associated with thrombosis in patients with nonvalvular atrial fibrillation (NVAF). METHODS: Seven NVAF patients with thromboembolism (TE), eight without TE, and eight with normal sinus rhythm (NSR) were studied using transesophageal echocardiography. TDI was used to evaluate the LAA wall acceleration. RESULTS: There was a decrease in the peak flow velocity in the TE group compared with the other two groups. There was greater LAA expansion in NVAF with TE groups (with TE [8.9 +/- 2.1 cm(2)] compared with the group without TE [7.3 +/- 2.8 cm(2)]), but the difference was not statistically significant; the difference was statistically significant compared with the NSR group (5.3 +/- 1.2 cm(2); P = 0.0035). The average of the continuous 40-frames area where tissue Doppler acceleration (TDA) was >0.024 cm/sec(2) was significantly lower in the TE group (0.12 +/- 0.05 cm(2)) compared to the group without TE (0.33 +/- 0.17 cm(2); P = 0.0017) and NSR group (0.30 +/- 0.13 cm(2); P = 0.0042), although wall velocity was not significantly different comparing the two NVAF groups. Furthermore, peak flow velocity of LAA was well correlated with LAA wall acceleration (r = 0.864, P < 0.0001). CONCLUSIONS: LAA wall acceleration obtained utilizing the TDI technique may be a new predictor of thrombogenesis in patients with NVAF.