Predictors of left atrial appendage clot: a transesophageal echocardiographic study of left atrial appendage function in patients with severe mitral stenosis

BACKGROUND: The purpose of this study was to prospectively evaluate a large group of consecutive, non-anticoagulated patients with severe rheumatic mitral stenosis and to analyze the left atrial appendage function in relation to left atrial appendage clot and spontaneous echo contrast formation. METHODS AND RESULTS: We prospectively studied left atrial appendage function in 200 consecutive patients with severe mitral stenosis who underwent transesophageal echocardiography and correlated it with spontaneous echo contrast and left atrial appendage clot. The mean age was 30.2 +/- 9.4 years. Fifty-five (27.5%) patients were in atrial fibrillation. Left atrial appendage clot was present in 50 (25%) patients and 113 (56.5%) had spontaneous echo contrast. The older age, increased duration of symptoms, atrial fibrillation, spontaneous echo contrast, larger left atrium, depressed left atrial appendage function and type II and III left atrial appendage flow patterns correlated significantly (p<0.05) with the left atrial appendage clot. Left atrial appendage ejection fraction was significantly less in patients with clot (21.8 +/- 12.8% v. 39.1 +/- 13.2%, p<0.0001) and in those with spontaneous echo contrast (30.3 +/- 16.2 % v. 40.3 +/- 11.8%, p<0.001). Left atrial appendage filling (18.0 +/- 11.7 v. 27.6 +/- 11.8 cm/s, p <0.0001) and emptying velocities (15.4 +/- 7.0 v. 21.5 +/- 9.6 cm/s, p<0.001) and filling (1.4 +/- 1.0 v. 2.5 +/- 1.4 cm, p<0.0001) and emptying (1.5 +/- 1.2 v. 2.1 +/- 1.2 cm, p <0.05) velocity time integrals were also significantly lower in patients with clot as compared to those without clot. On multivariate regression analysis, atrial fibrillation (odds ratio 6.68, 95% CI 1.85-24.19, p=0.003) and left atrial appendage ejection fraction (odds ratio 1.06, 95% CI 1.00 - 1.11, p=0.04) were the only two independent predictors of clot formation. Incidence of clot was 62.59% in patients with left atrial appendage ejection fraction < or = 25% as compared to 10.4% in those having left atrial appendage ejection fraction >25%. Similarly patients with spontaneous echo contrasthadlower filling (21.7 +/- 11.5 v. 29.4 +/- 12.7 cm/s, p<0.0001) and emptying (17.0 +/- 8.1 v. 23.9 +/- 10.9 cm/s, p<0.0001) velocities, as well as filling (1.9 +/- 1.3 v. 2.7 +/- 1.3 cm, p<0.01) and emptying (1.7 +/- 1.0 v. 2.3 +/- 1.4 cm, p<0.01) velocity time integrals as compared to patients without spontaneous echo contrast. In a subgroup of the patients with normal sinus rhythm, the left atrial appendage ejection fraction was significantly less in patients with clot compared to those without clot (31.2 +/- 13.2 v. 41.3 +/- 11.5 %, p<0.01). CONCLUSIONS: In the patients with severe mitral stenosis, besides atrial fibrillation, a subgroup of patients in normal sinus rhythm with depressed left atrial appendage function (left atrial appendage ejection fraction < or = 25%) had a higher risk of clot formation in left atrial appendage and these patients should be routinely anticoagulated for prevention of clot formation.     

造影增强经食道超声心动图评估射频消融术前房颤患者左心耳血栓及功能情况研究

目的 探讨造影增强经食道超声心动图(TEE)评估射频消融术前房颤患者的左心耳血栓及功能检出情况及应用价值.方法 选择2020年10月至2020年12月于四川大学华西医院就诊并拟行射频消融术的房颤患者20例,均行常规TEE及造影增强TEE检查.评估两种方法左心耳功能指标(左心耳排空、充盈速度)和左心耳血栓的检出情况.结果...     

Left atrial appendage function in patients with mitral stenosis in sinus rhythm.

AIMS: Left atrial appendage thrombi are believed to be the source of embolism in patients with rheumatic mitral stenosis in atrial fibrillation. There are a few studies which search the effects of left atrial appendage dysfunction in patients with mitral stenosis in sinus rhythm. METHODS AND RESULTS: Left atrial appendage function and flow patterns in 41 patients with rheumatic mitral stenosis in sinus rhythm and 11 healthy subjects were studied by transoesophageal echocardiography. Left atrial appendage flow profiles were recorded within the proximal third of the appendage. The left atrial appendage ejection fraction was expressed as (maximal area of appendage minimal area of appendage)/maximal area of appendage. In addition, two-dimensional imaging was used to determine the presence of spontaneous echocardiographic contrast and thrombus formation. Patients with mitral stenosis in sinus rhythm had significantly decreased left atrial appendage emptying and filling velocities compared to controls (0.40+/-0.15m/s vs 0.82+/-0.19 m/s and 0.42+/-0.21 m/s vs 0.68+/-0.28, respectively, P<0.001 and P<0.05). Compared with the control subjects, patients with mitral stenosis had significantly greater maximal area of the appendage and had reduced left atrial appendage ejection fraction (5.3+/-2.2 cm(2) vs 2.4+/-0.5 cm(2) and 50+/-16% vs 70+/-7%, respectively, P<0.001 and P<0.05). Of the patients with mitral stenosis in sinus rhythm, seven patients had spontaneous echocardiographic contrast and one of these had left atrial appendage thrombus. Compared with patients without spontaneous echocardiographic contrast, patients with spontaneous echocardiographic contrast had decreased left atrial appendage ejection fraction (33+/-21% vs 54+/-13%,P <0.01). One of the patients with mitral stenosis had central retinal artery occlusion, but thrombus was not observed in left atrial appendage. CONCLUSION: The study found that left atrial appendage dysfunction may occur in patients with mitral stenosis in sinus rhythm.     

Relationship of left atrial appendage function to left ventricular function

BACKGROUND: The study was conducted to evaluate the relationship of left atrial appendage function to left ventricular function and to analyze, if left ventricular dysfunction predisposed to left atrial appendage thrombus formation even in the presence of sinus rhythm. METHODS AND RESULTS: The study was conducted in 78 patients with a mean age of 53+/-8.5 years, all of whom were in sinus rhythm. Transesophageal echocardiography was performed to record the left atrial appendage emptying and filling velocity and to look for the presence of spontaneous echo contrast and thrombus. Patients with severe left ventricular dysfunction (Group I--left ventricular ejection fraction < 35%) and patients with moderate left ventricular dysfunction (Group II--left ventricular ejection fraction 35-45%) had lower left atrial appendage emptying velocity (33.6+/-16 and 39.7+/-19.5 cm/s, respectively) and filling velocity (41+/-14.7 and 41+/-17 cm/s, respectively) when compared to patients with preserved systolic function (Group II--left ventricular ejection fraction >45%), who had emptying and filling velocity of 55+/-16 and 56+/-15 cm/s, respectively (p <0.05). Twelve out of 32 (38%) patients with severe left ventricular dysfunction (Group I) and 7 out of 25 (28%) patients with moderate left ventricular dysfunction (Group II) had presence of left atrial appendage thrombus as compared to none of the patients with preserved left ventricular ejection fraction (Group III) (p <0.001). CONCLUSIONS: Patients with left ventricular dysfunction also had left atrial appendage dysfunction as evidenced by lower emptying and filling velocities and had increased incidence of thrombus formation.     

Right Atrial Thrombi and Depressed Right Atrial Appendage Function After Cardioversion of Atrial Fibrillation

BACKGROUND: It has been shown that cardioversion of atrial fibrillation may result in left atrial chamber and appendage dysfunction and cause new thrombi in the left atrium. The aim of this prospective study was to investigate right atrial appendage function and assess the incidence of new right atrial thrombi after electrical cardioversion. METHODS: Transthoracic echocardiography was performed in 25 patients 4 h before and at 24 h and 7 days after electrical cardioversion to determine right and left atrial mechanical function (internal atrial defibrillation, n = 16; external electrical cardioversion, n = 9), as assessed by peak A wave velocities derived from the transtricuspid and transmitral velocity profiles. In addition, transesophageal echocardiography was performed 4 h before and 24 h after cardioversion to evaluate postcardioversion thrombus formation in the right and left atrial chambers and to assess right and left atrial appendage function. The degree of spontaneous echo contrast was noted, and peak emptying velocities of the appendages were measured before and after cardioversion. RESULTS: Peak emptying velocities of both the right atrial appendage (mean +/- SD, 0.23 +/- 0.1 vs 0.32 +/- 0.11 m/sec; P = 0.02) and the left atrial appendage (0.3 +/- 0.15 vs 0.4 +/- 0.15 m/sec; P = 0.01) were significantly lower 24 h after cardioversion compared with 4 h before cardioversion, respectively. The degree of spontaneous echo contrast increased in the left atrium after cardioversion from 1.0 +/- 1.2 to 1.9 +/- 2.1 (P = 0.02), and in the right atrium, it increased from 0.8 +/- 1.1 to 1.2 +/- 1.1 (P = 0.1) after cardioversion. Peak A wave transtricuspid velocity increased from 0.26 +/- 0.05 m/sec at 24 h to 0.38 +/- 0.06 m/sec (P = 0.001) after 7 days; respective values for transmitral peak A wave velocity were 0.39 +/- 0.15 and 0.54 +/- 0.16 m/sec (P = 0.009). No thrombi were found in either the right or left atrium before cardioversion. In two patients, new thrombi in the right atrium were detected 24 h after internal atrial defibrillation. Thrombi were located at the superior rim of the fossa ovalis in both patients with patent foramen ovale. Another patient had developed a thrombus in the left atrial appendage. CONCLUSIONS: Electrical cardioversion may not only cause left atrial chamber and appendage dysfunction and left atrial thrombi but also lead to depressed right atrial appendage function and the generation of new thrombi in the body of the right atrium.     

Left atrial appendage function and thrombus formation in atrial fibrillation-flutter: A transesophageal echocardiographic study

Objectives. The purpose of this study was to investigate left atrial appendage size, function and thrombus prevalence in patients with atrial “fibrillation-flutter.”Background. Thrombus formation and peripheral embolization in atrial fibrillation are related to left atrial appendage dysfunction. Embolization occurs less frequently in atrial flutter. It is not known whether the atrial appendage in fibrillation-flutter, which has an intermediate appearance on the surface electrocardiogram (ECG), has distinct characteristics that could affect thrombus formation.Methods. Sixty-one patients with atrial tachyarrhythmias underwent transesophageal echocardiographic examination of the left atrial appendage. Appendage area, peak emptying velocity and the presence of thrombus and spontaneous echo contrast were determined. The results for 14 patients with fibrillation-flutter (based on ECG fibrillatory wave characteristics) were compared with those for 30 patients with atrial fibrillation and 17 patients with atrial flutter.Results. Both fibrillation-flutter and atrial fibrillation were associated with chaotic appendage flow patterns with similarly low peak emptying velocities (18 ± 8 and 17 ± 10 cm/s, mean ± 1 SD, respectively). Atrial flutter was associated with a regular pattern of appendage contraction and a significantly higher peak emptying velocity (42 ± 18 cm/s, p < 0.0001). Mean appendage area was similar for fibrillation-flutter and fibrillation (6.3 ± 2.2 and 6.7 ± 2.1 cm², respectively) but was significantly smaller for atrial flutter (5.3 ± 1.4 cm², p < 0.05). The prevalence of left atrial appendage thrombus was similar for fibrillation-flutter and atrial fibrillation (40% and 29%, respctivdy), whereas no patient with atrial flutter had a thrombus (p < 0.05). Similarly, the presence of spontaneous echo contrast was higher for fibrillationflutter (50%) and atrial fibrillation (40%) than for atrial flutter (6%, p < 0.05).Conclusions. Left atrial appendage size and function in atrial fibrillation-flutter are indistinguishable from those of typical atrial fibrillation, and the frequency of thrombus and spontaneous echo contrast is similarly high. This is in contrast to atrial flutter, which is characterized by a smaller, more contractile left atrial appendage and a lower frequency of thrombus and spontaneous echo contrast.     

Usefulness of phased-array intracardiac echocardiography for the assessment of left atrial mechanical "stunning" in atrial flutter and comparison with multiplane transesophageal echocardiography(*)

We compared transesophageal and phased-array intracardiac echocardiography (TEE/ICE) for the 2-dimensional and spectral Doppler assessment of left atrial (LA) mechanical function. TEE is commonly used to assess LA body and LA appendage mechanical function in patients who are undergoing radiofrequency ablation of typical atrial flutter. Fifteen patients underwent TEE and ICE imaging before and after ablation of typical atrial flutter. The following parameters were measured: (1) LA appendage emptying velocity and fractional area change, (2) severity of LA spontaneous echo contrast (graded 0 to 4), (3) maximal inflow velocity of the left and right upper pulmonary veins, and (5) maximal mitral valve E- and A-wave inflow velocities in sinus rhythm. Diagnostic quality imaging was achieved in all patients with TEE and ICE. Comparing TEE and ICE, the following absolute values and linear correlation coefficient (R) were obtained: preablation LA appendage emptying velocity: 0.45 +/- 0.21 versus 0.44 +/- 0.21 m/s (r = 0.95, p = <0.001); postablation LA appendage velocity: 0.33 +/- 0.24 versus 0.34 +/- 0.24 m/s (r = 0.97, p <0.001); LA appendage fractional area change: 35.3 +/- 13.7 versus 35.9 +/- 17.1% (r = 0.81, p <0.001); left upper/right upper pulmonary vein inflow velocity: 0.50 +/- 0.17/0.49 +/- 0.18 versus 0.51 +/- 0.17/0.47 +/- 0.20 m/s (r = 0.93/0.90, p <0.001); mitral valve E/A wave: 0.66 +/- 0.14/0.31 +/- 0.14 versus 0.69 +/- 0.17/0.35 +/- 0.23 (r = 0.84/0.97, p <0.002); LA spontaneous echo contrast (pre- and postablation): 1.1 +/- 1.2/1.3 +/- 1.2 versus 1.2 +/- 1.3/1.4 +/- 1.3 (r = 0.92/0.90, p <0.001). No patients were identified with LA appendage thrombus. Thus, TEE and phased-array ICE provided equivalent imaging data with high statistical correlation. ICE may be an imaging alternative to TEE in the evaluation of a "stunned" left atrium.     

Atrial myocardial deformation properties are temporarily reduced after cardioversion for atrial fibrillation and correlate well with left atrial appendage function.

AIM: This study was conducted to evaluate whether left atrial strain and strain rate correlate well with transesophageal parameters of stunning after atrial fibrillation. METHODS AND RESULTS: Twenty-two consecutive patients with chronic atrial fibrillation >/=3 months and <1 year were enrolled in the study. Transthoracic (TTE) and transesophageal (TEE) echocardiography with color Doppler myocardial imaging were performed before, 1 day after and 10 days after successful cardioversion. Left atrial transthoracic strain (S) and strain rate (SR) from lateral, inferior and anterior atrial walls, left atrial appendage tissue velocities, strain and strain rate values were measured with offline analysis. Left atrial appendage emptying (LAAEV) and filling (LAAFV) velocities were obtained from transesophageal echocardiography. Left atrial transthoracic, and left atrial appendage strain and strain rates were significantly lower following 1 day after cardioversion (TTE S/SR, 5.0 +/- 2.8%/2.3 +/- 1.0; TEE (septal) S/SR, 7.6 +/- 3.6%/1.6 +/- 0.7). There was a good correlation between these parameters and LAAEV (LA systolic strain and LAAEV, r = 0.73, P = 0.007). Left atrial and LAA strain and strain rate values improved over time, and correlated well with LAAEV, measured 10 days after cardioversion. CONCLUSIONS: Transthoracic atrial and TEE LAA strain and strain rate, which are quantitative measures of atrial function, are reduced after cardioversion, and recover subsequently. The good correlation between LAA function and TTE strain and strain rate suggests that TTE atrial parameters may help determine duration of anticoagulation.     

Left atrial spontaneous echo contrast in patients with permanent pacemakers.

OBJECTIVE: To determine the relations between left atrial appendage function, spontaneous echo contrast, and thromboembolism in patients with different modes of permanent pacemakers. PATIENTS AND METHODS: 88 patients with pacemaker implantation and 25 healthy controls in sinus rhythm had transoesophageal echocardiographic examination of the left atrial appendage. Left atrial size, appendage area, peak filling and emptying velocities of the atrial appendage, and the presence or absence of spontaneous echo contrast and thromboembolism were determined. The results in 63 patients with ventricular pacing (group 1, subdivided into subgroup 1A: 42 patients with sinus rhythm, and subgroup 1B: 21 patients with atrial fibrillation) were compared with those in 25 patients with synchronous pacing (group 2), and 25 normal control subjects (group 3). RESULTS: Patients with ventricular pacing had two distinct appendage flow patterns: well defined biphasic filling and emptying waves in subgroup 1A, and irregular very low filling and emptying waves in subgroup 1B. The ejection fraction of the left atrial appendage in subgroup 1A was significantly better than that in subgroup 1B (mean (SD) 40.6 (12.0)% v 7.6 (5.0)%, P < 0.0001). The spontaneous echo contrast was observed in 90% of subgroup 1B patients but in only 19% in subgroup 1A (P < 0.05) and was not found in groups 2 and 3 (P < 0.0001). There was a trend for increased prevalence of spontaneous echo contrast in subgroup 1A v group 2 (P = 0.053). Thrombi were detected in two cases, and cardiogenic embolism occurred in one case in subgroup 1B. All patients with spontaneous echo contrast had ventricular pacing. Multivariate analysis showed that atrial fibrillation was associated with occurrence of spontaneous echo contrast in patients with ventricular pacing (P = 0.005). CONCLUSIONS: The left atrial appendage ejection fraction was lower with ventricular pacing than with synchronous pacing. With ventricular pacing there was a trend towards increased prevalence of left atrial spontaneous echo contrast in patients in sinus rhythm, and a significantly increased prevalence in patients with atrial fibrillation.     

Left atrial appendage function in patients with atrial flutter.

OBJECTIVE: To determine whether echocardiographic markers thromboembolic risk differ between patients with pure atrial flutter and patients with atrial flutter and intermittent atrial fibrillation. DESIGN: Patients with atrial flutter were followed up prospectively for 12 months to identify intermittent atrial fibrillation. After the follow up period, transthoracic and multiplane transoesophageal echocardiography were performed to assess left atrial chamber and appendage size, peak emptying velocities, and emptying fraction of the left atrial appendage. The presence of spontaneous echo contrast was also determined. SETTING: Tertiary cardiac care centre. PATIENTS: 20 consecutive patients with atrial flutter; 11 healthy subjects in sinus rhythm served as controls. RESULTS: Intermittent atrial fibrillation was documented in 11 patients by Holter monitoring or surface ECG; atrial fibrillation was not found in the other nine patients. Compared with the patients with pure atrial flutter, patients with atrial flutter and intermittent atrial fibrillation had larger left atrial chamber (mean (SD) 4.5 (0.6) v 3.8 (0.5) cm; 95% confidence interval 0.2 to 1.2; P = 0.01) and appendage areas (6.7 (2.2) v 4.8 (4.9) cm; 95% CI 0.4 to 3.5; P = 0.02), lower left atrial appendage emptying fractions (33 (11)% v 52 (11)%; 95% CI 8 to 29; P = 0.008), and also lower left atrial appendage emptying velocities (0.44 (0.21) v 0.79 (0.27) m/s; 95% CI 0.13 to 0.56; P = 0.005). In addition, a higher incidence of spontaneous echo contrast (11% v 36%) was observed in patients with atrial flutter and intermittent atrial fibrillation. CONCLUSIONS: Left atrial appendage function is depressed and spontaneous echo contrast more frequent in patients with atrial flutter and intermittent atrial fibrillation, as opposed to patients with pure atrial flutter. These data support the concept that patients with atrial flutter and intermittent atrial fibrillation have an increased risk of thromboembolic events and should therefore receive adequate anticoagulant treatment.     

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。     

Time course for resolution of left atrial appendage stunning after catheter ablation of chronic atrial flutter

OBJECTIVES: This study assessed the time course of resolution of left atrial appendage (LAA) stunning after catheter ablation of chronic atrial flutter (AFL). BACKGROUND: Although the presence of LAA stunning after ablation of chronic AFL calls for anticoagulation in the post-cardioversion period, limited information has been obtained, particularly regarding its duration. METHODS: Sixteen patients who underwent ablation of chronic, pure AFL were studied, only five of whom had structural heart disease and one of whom had a reduced left ventricular ejection fraction. The LAA emptying velocities (LAAEV) and left atrial spontaneous echo contrast (SEC) were assessed using transesophageal echocardiography before, within 24 h after, one week after, and two weeks after ablation. RESULTS: Within 24 h after ablation, the LAAEV decreased from 39 +/- 10 cm/s during AFL to 21 +/- 10 cm/s during sinus rhythm (p < 0.01), with eight patients (50%) having documented SEC. After one week, the LAAEV increased (39 +/- 17 cm/s, p < 0.01 vs. within 24 h) and SEC resolved in five of eight patients. After two weeks, the increase in LAAEV persisted (54 +/- 14 cm/s, p < 0.01 vs. 1 week) and SEC was no longer present in any of the patients. The numbers of patients with LAAEV >30 cm/s and absence of SEC were three within 24 h, 11 at one week, and 16 at two weeks after ablation. CONCLUSIONS: Patients with chronic, pure AFL and preserved left ventricular function who will undergo catheter ablation may not require anticoagulation therapy for more than two weeks after the procedure because of the presence of forceful mechanical LAA contractions and the absence of SEC.     

Evaluation of Left Atrial Appendage Functions in Patients with Thrombus and Spontaneous Echo Contrast in Left Atrial Appendage by Using Color Doppler Tissue Imaging

Objective: Thrombus and spontaneous echo contrast (SEC) develops in the left atrial appendage (LAA) when LAA function is disturbed. Decrease of left atrial appendage emptying velocity shows LAA dysfunction. The purpose of this study is to examine the incidence of SEC and/or thrombus in LAA in patients with acute myocardial infarction and to assess the LAA function using color Doppler tissue imaging (CDTI) of the patients with detected SEC and/or thrombus. Method and Results: Eighty‐four patients with acute myocardial infarction were included in the study. Spontaneous echo contrast and/or thrombus were observed in 24 (29%) of the 84 patients who were categorized as group 1 (mean age 59 ± 12 years). Sixty patients (71%) without thrombus and/or SEC in LAA were categorized as group 2 (mean age 58 ± 8 years). Left atrial diameters and left ventricular ejection fraction were measured by using transthoracic echocardiography. Left atrial appendage emptying and LAA filling velocity were measured by transesophageal Doppler echocardiography. Systolic appendage tissue velocities (SaV cm/s) were measured at the basal, mid, and tip of medial wall of LAA by transesophageal CDTI. Group 1 had significantly decreased LAA emptying velocities, mid SaVs, and left ventricular ejection fractions compared to group 2 (37 ± 9 cm/s vs 55 ± 22 cm/s, 3.1 ± 1.6 cm/s vs 3.7 ± 1.2 cm/s, and 47 ± 13% vs 58 ± 10%, respectively, P = 0.002, P = 0.04, P = 0.03). Group 1 had significantly increased left atrial diameters compared to group 2 (40 ± 5 mm vs 36 ± 6 mm P = 0.001). Left atrial appendage‐filling velocities, basal SaVs and tip SaVs in group 1 were lower than those in group 2 but not significantly. Conclusions: Mid‐SaV of LAA medial wall and LAA emptying velocity decrease in patients with thrombus and/or SEC were an indication of functional disorder of LAA. Color Doppler tissue imaging appears to be a clinically applicable and reliable imaging technique that allows quantitative assessment of regional LAA systolic function.     

Mitral valve replacement impairs the flow in the left atrial appendage in mitral regurgitation

OBJECTIVE: We aimed to assess the left atrial appendage (LAA) flow velocities of rheumatic valves in 46 patients, diagnosed with isolated mitral regurgitation (MR) (16 patients), mitral stenosis (MS) (14 patients) and combined MS and MR (MS + MR) (16 patients) before and after operation. METHODS: The patients were subdivided into two groups, according to rhythm: sinus (SR) (20 patients) and atrial fibrillation (AF) (26 patients). All patients underwent transthoracic and transoesophageal echocardiography before and after the operation. RESULTS: Preoperatively LAA flow velocities were the best in the MR group among the three groups. Postoperatively there was no statistically significant difference between the MR group and the other two groups for mean peak emptying and filling velocities in patients with SR and AF. The incidence of spontaneous echo contrast (SEC) and thrombus significantly increased in the MR group after operation. Thrombus was only seen in patients with AF at the postoperative period. CONCLUSIONS: Mitral valve replacement disturbs LAA flow velocities and increases the risk of thrombus formation in patients with MR. This risk was more obvious in cases with AF. Impaired left atrial appendage flow velocities increase the risk of thrombus formation. We recommend close follow-up for the increased possibility of thrombus formation in patients who had MR preoperatively and AF postoperatively.     

Relations between left atrial appendage blood flow velocity,spontaneous echocardiographic contrast and thromboembolic risk in vivo

Objectives. The aim of this study was to determine the relations between spontaneous echo contrast, left atrial appendage blood flow velocity and thromboembolism.Background. Left atrial thrombus and spontaneous echo contrast, a putative marker of thromboembolic risk, are frequently located in the left atrial appendage. Measurement of left atrial appendage outflow Doppler velocity by transesophageal echocardiography is a recent technique for assessment of left atrial appendage function, which may be important in thrombus formation.Methods. Transthoracic and transesophageal echocardiographic studies were performed in 140 patients with atrial fibrillation (chronic in 80 patients, paroxysmal in 50 patients, first episode <2 weeks in 10 patients). The left atrium and appendage were inspected for thrombus and spontaneous echo contrast, which was graded from 0 (none) to 4+ (severe). Outflow velocity profiles were obtained by pulsed wave Doppler at the orifice of the left atrial appendage.Results. Left atrial spontaneous echo contrast was present in 78 patients (56%). In multivariate logistic regression analysis, spontaneous echo contrast was the only significant correlate of left atrial thrombus and was present in 14 (93%) of 15 patients. Spontaneous echo contrast and age were associated positively, and anticoagulant therapy was associated negatively, with previous thromboembolic events. Increasing grades of spontaneous echo contrast were associated with decreasing left atrial appendage blood velocity. The velocity in patients with thrombus was not significantly different from that in patients with 4+ spontaneous echo contrast. In multivariate linear regression analysis, the grade of spontaneous echo contrast was significantly and negatively associated with left atrial appendage velocity (p = −0.0001) and mitral regurgitation (p = −0.0002) and significantly and positively associated with left atrial area (p = 0.0005). The odds ratio for spontaneous echo contrast was 28:1 for low left atrial appendage blood flow velocity (<35 cm/s) and 96:1 for low velocity and the absence of mitral regurgitation.Conclusions. Spontaneous echo contrast is the cardiac factor most strongly associated with left atrial appendage thrombus and embolic events. Spontaneous echo contrast formation is promoted by reduced blood flow velocity and increased left atrial size but is diminished by mitral regurgitation.     

Assessment of left atrial appendage function by biplane transesophageal echocardiography in patients with nonrheumatic atrial fibrillation: Identification of a subgroup of patients at increased embolic risk

Objectives. This study was conducted to identify a subgroup of patients with nonrheumatic atrial fibrillation with an increased risk for cardiogenic embolism by assessing left atrial appendage function.Background. Patients with nonrheumatic atrial fibrillation have an increased risk for thromboembolic complications. The left atrial appendage is the most likely source for thrombus formation. It is likely that the appendage function (contraction, filling dynamics) is related to the pathogenesis of thrombus formation.Methods. Twenty-nine patients with nonrheumatic atrial fibrillation (group I) underwent biplane transesophageal echocardiography. The maximal and minimal areas during a cardiac cycle and the peak emptying and filling velocities of the appendage were measured in both scan planes. For comparison, two additional groups were also analyzed. Group II consisted of 12 patients with chronic atrial fibrillation due to significant mitral stenosis, and group III consisted of 30 patients who were in sinus rhythm.Results. Patients with nonrheumatic atrial fibrillation showed two distinct appendage flow patterns: either well defined peak filling and emptying waves (≥25 cm/s) with visible fibrillatory contractions of the appendage wall (“high flow profile”) or irregular, very low, peak filling and emptying waves (<25 cm/s) associated with almost no visible appendage contractions (“low flow profile”). The left atrial appendage function in the first subgroup resembles that seen in patients with sinus rhythm, whereas the appendage function in the latter subgroup resembles more the “static pouch” seen in patients with rheumatic atrial fibrillation. Events suggestive of cardiogenic embolism occurred in six patients from group I, five of whom were in the low flow profile subgroup (p < 0.05). The spontaneous echo contrast phenomenon was observed in 80% of the low flow profile subgroup but in only 5% in the high flow profile subgroup (p < 0.05). Three thrombi confined to the left atrial appendage were detected by transesophageal echocardiography in group I; all three of the patients were in the low flow profile subgroup.Conclusions. The assessment of left atrial appendage function by transesophageal echocardiography may be helpful to identify subgroups of patients with nonrheumatic atrial fibrilation with an increased risk of thrombus formation.     

Left atrial appendage Doppler flow patterns: implications on thrombus formation.

The characteristics and clinical implications of left atrial appendage (LAA) flow have not been clearly analyzed. Thirty-nine consecutive patients underwent a transesophageal echocardiographic (TEE) color Doppler study to correlate the LAA pulsed Doppler flow pattern with echocardiographic variables and the cardiac rhythm of each patient. Three different LAA flow patterns were identified. Type I flow, characterized by a biphasic pattern (waves of filling and emptying), was found in 17 patients, all in sinus rhythm; it was not associated with LAA spontaneous contrast or thrombus. Mean peak velocities of the filling and emptying waves were, respectively: 28 +/- 12 cm/sec and 31 +/- 9 cm/sec. Type II sawtooth active flow (eight patients) (mean peak velocity: 49 +/- 12 cm/sec) was only detected in atrial fibrillation (AF) and dilated LAA (LAA area: 421 +/- 40 mm2) but without thrombus or significant LAA spontaneous echocardiographic contrast. Type III flow pattern was noted in 14 patients with AF and a very dilated LAA (LAA area: 619 +/- 96 mm2). This flow pattern was characterized by the absence of identifiable flow waves and was associated with the presence of LAA spontaneous contrast; the majority (six of seven) had evidence of thrombus. We concluded that the LAA is a dynamic structure in which TEE study identified three flow patterns with different implications. AF is associated with two LAA flow types (II and III) with a larger LAA size as well as a higher incidence of LAA clots in type III flow.     

Effect of Direct Current Shocks on Left Atrial Mechanical Function in Patients With Structural Heart Disease

Objectives. This study examined the effect of endocardial and transthoracic direct current (DC) shocks on left atrial and left atrial appendage function in humans with structural heart disease.Background. DC cardioversion of atrial fibrillation (AF) to sinus rhythm is associated with transient left atrial and left atrial appendage dysfunction and the development of spontaneous echo contrast (SEC). This phenomenon has been termed atrial “stunning” and may be associated with thrombus formation and embolic stroke. To what extent the shock itself contributes to atrial stunning is unclear.Methods. Thirteen patients in sinus rhythm undergoing implantation of a ventricular implantable cardioverter defibrillator (ICD) were prospectively evaluated. All patients had significant structural heart disease. To evaluate the effects of DC shocks on left atrial and left atrial appendage function, biphasic R wave synchronized endocardial shocks of 1, 10 and 20 J were delivered between the right ventricular electrode and the left pectoral generator of the ICD in sinus rhythm. R wave synchronized transthoracic shocks of 360 J were also delivered between anteriorly and posteriorly positioned chest electrodes. Transesophageal echocardiography was performed to evaluate left atrial appendage velocities, mitral inflow velocities and the presence of SEC before and immediately after each DC shock.Results. There were no significant changes in left atrial or left atrial appendage function after endocardial or transthoracic DC shocks. Left atrial SEC did not develop after endocardial or transthoracic DC shocks.Conclusions. Endocardial and transthoracic DC shocks are not directly responsible for left atrial and left atrial appendage stunning and do not contribute to the stunning that is observed after the cardioversion of AF to sinus rhythm.     

Effect of batroxobin on spontaneous echo contrast and hemorheology in left atrial appendage in atrial fibrillation assessed by transesophageal echocardiograpy.

Controversy exists regarding the effect of defibrination on spontaneous echo contrast and flow dynamics in left atrial appendage (LAA) in atrial fibrillation. We aimed to investigate the effect of batroxobin, which decreases plasma fibrinogen level, on the echo intensity of spontaneous echo contrast in LAA. In 36 patients with atrial fibrillation (duration 7 +/- 4 years), transesophageal echocardiography was performed at baseline and 24 hours after batroxobin administration (0.2 U/kg). At the orifice of the LAA, integrated backscatter of echo contrast and peak velocity of LAA emptying flow were measured. Plasma fibrinogen and whole blood viscosity were also measured. Fibrinogen and viscosity were significantly lower after batroxobin administration (96 +/-38 mg/dl and 4.35 +/- 0.56 cp) than those at baseline (320 +/- 61 mg/dl and 4.71 +/- 0.61 cp, both p <0.001). A significant positive correlation between changes in plasma fibrinogen and whole blood viscosity (r = 0.49, p = 0.002) was shown. The integrated backscatter significantly decreased from 14 +/- 3 to 12 +/- 3 decibels after batroxobin (p <0.001), and the changes in integrated backscatter and plasma fibrinogen was significantly correlated. Therefore, batroxobin administration improved blood rheology and decreased blood cell aggregation, which are effective in preventing left atrial thrombus formation.     

Left atrial thrombus associated with ablation for atrial fibrillation: identification with intracardiac echocardiography

OBJECTIVES: This study reports the incidence of, risk factors for, and management of left atrial (LA) thrombus documented by intracardiac echocardiography (ICE) during LA ablation for atrial fibrillation (AF). BACKGROUND: Thrombus formation is a risk associated with LA ablation procedures. METHODS: Intracardiac echocardiography imaging was performed in 232 patients (184 men, average age 55 +/- 11 years) with AF undergoing pulmonary vein ostial ablation. RESULTS: Anticoagulation (activated clotting time >250 s) was maintained after dual transseptal catheterization. Left atrial thrombus (n = 30) was observed in 24 of 232 patients (10.3%). Thrombi measured 12.9 +/- 11.1 mm (length) and 2.2 +/- 1.3 mm (width) and were attached to a sheath or mapping catheter. Most thrombi (27 of 30, 90%) were eliminated from the LA by withdrawal of the sheath and catheter into the right atrium (RA). Two thrombi became wedged in the interatrial septum and incompletely withdrawn into the RA, and one was recognized only on post-procedure review of ICE images. Patients with LA thrombus had an increased LA diameter (4.8 +/- 0.5 vs. 4.5 +/- 0.6 cm, p < 0.02), spontaneous echo contrast (67% vs. 3%, p < 0.0001) and a history of persistent AF (29% vs. 6%, p < 0.0002). Multivariate discriminant analysis showed that spontaneous echo contrast (f = 97.9, p < 0.0001) was the most important determinant of LA thrombus formation. No patient with LA thrombus suffered a clinical thromboembolic complication. CONCLUSIONS: Left atrial thrombus identified on ICE may occur during LA catheter ablation procedures despite aggressive anticoagulation. Spontaneous echo contrast may predict risk for LA thrombus formation. Left atrial thrombus may be successfully withdrawn into the RA under ICE imaging with no overt complications.