Left Atrial Appendage Size Research Articles

Measurement of left atrial appendage size by transesophageal echocardiography.

Transesophageal echocardiography (TEE) is the most common imaging method for evaluating left atrial morphology. Recent advances in 64-slice multidetector computed tomography (64-MDCT) allow accurate measurement of left atrial appendage (LAA) volume. The aim of this study was to evaluate the accuracy of LAA sizing by TEE in comparison with 64-MDCT in patients with atrial fibrillation. Electrocardiogram-gated 64-MDCT and TEE were performed within 2days in 18 consecutive patients (63±9years old, 12 males, 5 paroxysmal atrial fibrillation) with nonvalvular atrial fibrillation. LAA area and LAA volume were measured at end-systole by TEE and 64-MDCT, respectively. The largest LAA area was measured on TEE image. Five patients were in sinus rhythm during examinations. In all patients, LAA was clearly visualized; the largest area of LAA was 9.3±3.9mm(2) and the LAA volume was 21.6±7.5ml. A significant correlation between LAA area and LAA volume was observed (p=0.0003, r=0.75). TEE allows a detailed evaluation of the LAA structure by two-dimensional imaging. LAA size could be evaluated by TEE despite its morphological complexity, i.e., sac-like or multilobed structure.

Larger Left Atrial Appendage Is an Independent Predictor of Stroke in Patients with Atrial Fibrillation

Background: Left atrial appendage (LAA) is an important source of thromboembolism in patients with atrial fibrillation (AF). This study evaluated the features of LAA associated with stroke in patients with AF.Methods: We compared the size of LAA using computed tomography (CT) between 224 AF patients with non-hemorrhagic stroke (Group 1, 71 women, age 67±10 years) and 365 AF patients without stroke (Group 2, 77 women, age 56±11 years).Results: Group 1 included more female patients (31.7% vs. 21.1%, p=0.004), and was older than group 2 (p<0.001). There was no difference in the type of AF between two groups. CHADS2 score (3.2±0.8, vs. 0.6±0.7, p<0.001) and LA dimension (4.76±0.82 vs. 4.12±0.59 cm, p<0.001) were significantly lager in group 1 than group 2. The orifice size (3.85±1.66 vs. 2.57±0.93 cm2, p<0.001) and depth of LAA (3.18±0.67 vs. 2.67±0.57 cm, p<0.001) were significantly larger in group 1 than group 2. In multivariate analysis, age (OR 2.08 per decade increase, 95% CI 1.59–2.71, p<0.001), LA size (OR 1.89, 95% CI 1.29–2.76, p=0.001), the orifice size (OR 1.58, 95% CI 1.26–1.99, p<0.001) and the depth of LAA (OR 1.91, 95% CI 1.24–2.95, p=0.004) were independent predictors of stroke.Conclusion: In patients with non-valvular atrial fibrillation, the larger orifice size and depth of LAA were independent predictors of stroke with advanced age and LA enlargement.

Left atrial appendage contributes to left atrial booster function after the maze procedure: quantitative assessment with multidetector computed tomography☆

Although the left atrial appendage (LAA) is excised to prevent thrombosis in the maze procedure, it remains unclear whether LAA is retained in expectation of LAA booster function. Therefore, we quantitatively assessed LAA size and function after the maze procedure in patients with chronic atrial fibrillation (AF) and mitral valve disease (MVD), and compared with those in patients with sinus rhythm after coronary artery bypass grafting (CABG). We studied 23 patients (maze group: 65.0 + or - 9.2 (SD) years) undergoing the maze procedure for chronic AF and mitral valve surgery and 16 patients having sinus rhythm after CABG (CABG group: 66.5 + or - 9.3 years). The maze procedure was conducted by radiofrequency (RF) ablation and LAA was preserved in all cases. Left atrium (LA) and LAA volume and booster function were quantitatively evaluated by multidetector computed tomography (MDCT) at 11.7 + or - 10.4 months (maze group) and 16.8 + or - 19.9 months (CABG group) after the surgery. In all 23 patients of the maze group, sinus rhythm was well restored. LAA was clearly visualised without thrombi in all 39 patients. The maximal LA volume in the maze group was 128.8 + or - 54.6 ml, being larger than 105.3 + or - 36.1 ml in the CABG group. LA ejection fraction (EF) in the maze group was 16.1 + or - 7.0%, being significantly lower than 26.8 + or - 8.7% in the CABG group. Meanwhile, the maximal LAA volume in the maze group was significantly larger (16.9 + or - 7.3 ml vs 8.4 + or - 4.7 ml), but LAA EF (34.1 + or - 12.8% vs 36.1 + or - 7.4%) was comparable in the two groups. LAA largely contributes to LA booster function, particularly in the maze group, because LA booster function is deteriorated in this group of patients.

Transthoracic Doppler echocardiography for the assessment of left atrial appendage size and blood flow velocity. A multicentre study

The aim of this study was to evaluate the reliability of transthoracic Doppler echocardiography (TTE) in the assessment of left atrial appendage (LAA) size and function. We considered 86 consecutive patients [56 male, 30 female; mean age 64 +/- 13 years, sinus rhythm 36 patients (42%); atrial flutter/fibrillation 50 patients (58%)] referred for transoesophageal echocardiography (TEE) and TTE. Maximum LAA transverse diameters and LAA peak flow velocities were calculated by two-dimensional and pulsed-wave Doppler analysis at TEE and TTE. LAA systolic transverse diameters were detectable in 78 patients (91%) by TTE and showed a significant correlation with TEE (r = 0.77, P < 0.0001). LAA peak flow velocities were measurable by TTE in 72 patients (84%) and were comparable with TEE (50.4 +/- 23 vs 47.3 +/- 23.2 cm/s, r = 0.67, P < 0.0001). A peak blood flow velocity of <25 cm/s at TTE was the best indicator of very low (<20 cm/s) LAA flow velocity as detected by TEE (sensitivity 93%, specificity 87%, area under the curve 0.94, P < 0.0001). Conversely, a peak blood flow velocity of >56 cm/s at TTE indicated a very high (> 40 cm/s) LAA flow velocity as detected by TEE (sensitivity 50%, specificity 96%, area under the curve 0.87; P < 0.0001). Reliable LAA size and blood flow velocities can be obtained by TTE in consecutive, unselected patients. TTE identifies patients with low and high blood flow velocities in the LAA, providing helpful information for the definition of individual embolic risk.

Morphological Changes of the Left Atrial Appendage After Catheter Ablation of Atrial Fibrillation

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). 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. 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.

Analysis of the left atrial appendage by magnetic resonance angiography in patients with atrial fibrillation

Recent interest has focused on the left atrial appendage (LAA) in the setting of atrial fibrillation as a potential source of thromboembolism and stroke, which may be amenable to permanent occlusion by a variety of investigational catheter-delivered devices. Precise anatomic characterization of the LAA is necessary to determine the suitability of a patient for device placement and for device selection and sizing. The purpose of this study was to perform detailed three-dimensional characterization of LAA size and geometry by magnetic resonance angiography. Fifty patients with chronic atrial fibrillation undergoing cardiac magnetic resonance angiography in preparation for catheter ablation of atrial fibrillation were analyzed for LAA volume, neck size, depth, and overall geometry. The average LAA volume was 17.3 +/- 6.7 mL, with a depth of 26.6 +/- 4.9 mm and a "neck" diameter of 20.0 +/- 5.3 mm x 14.1 +/- 4.7 mm. The average number of LAA lobes was 1.4 +/- 0.7 (range 1-4). Substantial interpatient variability was present in the relative dimensions and morphology of the LAA. There was a significant correlation between left atrial size and LAA neck dimensions. There is significant heterogeneity in LAA size and dimensions among patients with atrial fibrillation. Device occlusion of the LAA may require devices that are available in multiple sizes/shapes or that can adapt to this heterogeneity.

Left atrial appendage septae not visualized with transesophageal echocardiography

Left atrial appendage (LAA) filter implantation was attempted in an 89 year old male. The LAA size was estimated by transesophageal echocardiography (TEE). Complete LAA obliteration was not achieved. LAA angiography suggested that the LAA was multilobed, likely separated by a thin septae not seen with TEE. MRI or CT may be more appropriate imaging modalities to define LAA anatomy.

Three-dimensional reconstruction of pulmonary veins in patients with atrial fibrillation and controls: morphological characteristics of different veins.

Multidetector computed tomography can be used to evaluate the anatomy of pulmonary veins (PVs) in patients with AF. The study evaluated two groups. Group 1 included 61 patients assessed following PV ablation with ultrasound of RF energy. Group 2 included 15 patients undergoing ablation for AF and 14 control subjects without a history of AF matched for age and sex. The anatomy of the PVs was analyzed in this group prior to the ablation and compared to controls. Computed tomography was used to measure the ostium of the left superior, left inferior, right superior, right inferior PVs, and the left atrial appendage size. In group 1, PV stenosis was seen in 14 (30%) of 46 patients undergoing ablation with RF energy and in none of the 15 patients receiving ablation with ultrasound energy. In group 2, the ostium size was not different between patients with AF and controls. Similarly, the ostium of the PV that appeared to trigger AF was not larger than the ostium of the remaining veins. A "clustering pattern" of PV branches near the right inferior PV ostium was seen in almost every patient, independent of the presence of the arrhythmia. Computed tomography frequently detects PV stenosis following RF ablation. Ultrasound ablation does not appear to result in PV narrowing. Overall, patients with AF do not have larger sizes of PV ostia. Multiple ramifications from the right inferior PV ostium is a common pattern and may represent a protective anatomic variant.

Location, size and morphological characteristics of left atrial thrombi as assessed by echocardiography in patients with rheumatic mitral valve disease.

This study aimed to assess the use of transthoracic and transoesophageal echocardiography in diagnosing the thrombi located in the left atrium and/or left atrial appendage in patients with rheumatic mitral valve disease, and to investigate the characteristics of thrombi in comparison to intraoperative findings. The study group was comprised of 474 patients who underwent transthoracic and transoesophageal echocardiography prior to mitral valve surgery. Location, thickness and morphological characteristics of thrombi were determined by transoesophageal echocardiography. Intraoperative assessment disclosed left atrial thrombi in 105 patients. Thickness of thrombi < or = 1cm, and thrombi confined to left atrial appendage were associated with false-negative results by transthoracic echocardiography. However, diameter and morphological characteristics of thrombi, left atrial and left atrial appendage size, and the presence of the spontaneous echo contrast were not associated with the diagnosis of thrombi by transthoracic echocardiography. For overall left atrial thrombi, sensitivity and specificity of transthoracic echocardiography were 32%, and 94%, respectively. Sensitivity and specificity of transoesophageal echocardiography for thrombi in the left atrial appendage were 98%, and 98%, for thrombi in the main left atrial cavity were 81%, and 99%, and for thrombi located in both left atrium and appendage cavities were 100%, and 100%, respectively. In patients with rheumatic mitral valve disease, detection of left atrial thrombi by transthoracic echocardiography seems to be determined by thickness and location of thrombi. The multilobed structure of the left atrial appendage and artifacts over posterior wall of the left atrium may still prevent precise diagnosis even with transoesophageal echocardiography.

Left Atrial and Left Atrial Appendage Functional Abnormalities in Patients with Cardioembolic Stroke in Sinus Rhythm and Idiopathic Atrial Fibrillation

Thrombogenesis in the left atrial appendage (LAA) has been related to the special morphology of this cavity and to its size and degree of dysfunction. However, no study has focused on LAA function in conjunction with left atrial (LA) function in both sinus rhythm (SR) and nonrheumatic idiopathic atrial fibrillation (AF) in relation to clinical status (cardioembolic stroke). Forty-three patients in SR (14 patients with stroke, 29 control subjects) and 45 patients in AF (27 patients with stroke, 18 control subjects) were examined by transthoracic and transesophageal echocardiography. Baseline clinical characteristics and standard transthoracic and transesophageal measurements of the LA and LAA (size, fractional area change, flow measurements, spontaneous echo contrast, and thrombus) were recorded and compared in relation to cardiac rhythm. Patients in the stroke-SR group showed a significant decrease of fractional area change in the LA (32% ± 15%) and LAA (34% ± 15%) in relation to control subjects (43% ± 10%, p = 0.035, 49% ± 13%, p = 0.006, respectively). Patients in the stroke-AF group showed significant reduction of appendage flow measurements (outward velocity = 22 ± 13 vs 33 ± 19 cm/sec, p = 0.036), whereas no differences were detected in the center of the LA. In multiple regression analysis, the presence of cardioembolic stroke was positively associated with the presence of spontaneous echo contrast (p = 0.0253) and spontaneous echo contrast negatively associated with appendage inward flow velocity (p < 0.001). Cardioembolic stroke in patients in SR is associated with a global decrease of shortening in both cavities and in patients with AF, with a reduction of LAA flow parameters. Patients with spontaneous echo contrast, thrombus, or both showed further reduction of shortening and flow velocities in both cavities, indicating a more advanced stage of dysfunction. (J Am Soc Echocardiogr 1998;11:711-9.)

Anatomy of the normal left atrial appendage: a quantitative study of age-related changes in 500 autopsy hearts: implications for echocardiographic examination.

Transesophageal echocardiography (TEE) is the diagnostic modality of choice for visualizing the left atrial appendage (LAA). This study defined the morphology of the LAA in normal autopsy specimen hearts and considered the implications of these findings for TEE studies. Five hundred normal autopsy hearts were reviewed (25 male and 25 female subjects from each decade for 10 decades). LAA length, width, orifice size, and number of lobes were recorded. Number of lobes was compared between sexes with the rank sum test and regressed against age. Mean length, width, and orifice size increased with age, up to age 20 years, in both sexes. Rates were significantly different between sexes for LAA size (P=.011) and width (P=.006). After age 20, statistically significant but clinically insignificant age-related changes were observed. Fifty-four percent of LAAs had two lobes (range, 1 to 4), with no age or sex differences. Lobes exist in different planes of the heart. Most pectinate muscles were > or = 1 mm in width. Pectinate muscles < 1 mm (2.6% of cases) were seen in only the first and last decades. Age- and sex-related differences in LAA dimensions exist. These differences and the existence of multilobed appendages are important in the accurate TEE evaluation of LAA. Because lobes exist in different planes, imaging must be done in multiple planes to visualize the entire LAA.

Transesophageal echocardiographic predictors for maintenance of sinus rhythm after electrical cardioversion off atrial fibrillation

The aim of this study was to assess the value of transesophageal echocardiography (TEE) in patients with atrial fibrillation in predicting restoration and maintenance of sinus rhythm after electrical cardioversion. TEE was performed in 62 patients with atrial fibrillation before their first elective cardioversion. Clinical variables evaluated were: age, gender, duration, and etiology of atrial fibrillation. TEE variables included: left atrial (LA) length, width, and size, LA annulus size, as well as presence of LA spontaneous contrast, thrombus and mitral regurgitation, LA appendage size and flow, and left ventricular function. Based on initial outcome of cardioversion, patients were grouped into patients who remained in atrial fibrillation and in whom sinus rhythm was restored. The latter group of patients was followed for 1 year, and grouped into patients who reverted to atrial fibrillation and in whom sinus rhythm was maintained. Successful cardioversion was achieved in 50 of 62 patients (81%). None of the clinical or TEE variables were related to initial outcome. At 1-year follow-up, 29 of 50 patients (58%) who underwent successful cardioversion continued to have sinus rhythm. The following variables were related to maintenance of sinus rhythm: duration of atrial fibrillation (6.7 ± 7.3 vs 2.0 ± 2.4 months; p < 0.005); LA length (6.2 ± 0.7 vs. 5.5 ± 1.0 cm; p < 0.008); width (5.1 ± 0.5 vs. 4.5 ± 0.7 cm; p < 0.002); size (26.4 ± 5.0 vs 19.8 ± 6.5 cm 2; p < 0.0005); annulus size (4.0 ± 0.2 vs 3.7 ± 0.3 cm; p < 0.0005); presence of LA spontaneous contrast (13 [62%] vs 4 [14%]; p < 0.002), and LA appendage flow (19 ± 8 vs 36 ± 15 cm/s; p < 0.0005). In multivariate logistic regression analysis, LA annulus size, but especially LA appendage flow, were significantly associated with maintenance of sinus rhythm. Thus, in TEE-guided electrical cardioversion of atrial fibrillation, variables often used to assess thromboembolic risk may also be used to predict 1-year outcome of cardioversion.

954-2 Transesophageal Echocardiographic and Clinical Predictors for Outcome of Cardioversion of Atrial Fibrillation

To determine the value of transesophageal echo (TEE) and clinical variables in predicting outcome of cardioversion (CVI. we studied 62 patients with nonvalvular atrial fibrillation (AFI. who underwent TEE prior to elective electrical CV We measured left atrial (LA) size, mitral valve annulus (MVA) width, LA appendage (LAA) size and LAA peak flow velocity (pfv), and evaluated presence of LA spontaneous contrast (LASC) and severity (none-mild/moderatesevere) of MV regurgitation (MVR). After CV, sinus rhythm (SR) was restored in 50 patients (81%) and maintained in 29 patients (58%) at 1 year follow-up. Empty CellInitial Outcome1 Year OutcomeEmpty CellAF (n = 12)SR (n = 50)AF (n = 21)Empty CellSR (n = 29)LA size (cm2)23.3 ± 7.422.6 ± 6726.4 ± 5.0*198 ± 6.5MVA width (cm)3.8 ± 0.33.9 ± 034.0 ± 0.2*37 ± 0.3LAA size (cm2)7.8 ± 2.78.8 ± 399.3 ± 3384 ± 3.3LAA-pfv (cm/s)22 ± 929 ± 1519 ± 8*36 ± 15LASC presence51713**4MVR severity7/538/1216/522/7*p &lt; 0.0001**p &lt; 0.005 p &lt; 0.0001 p &lt; 0.005 Outcome was not related to age, gender, etiology of AF, or use of antiarrhythmic drugs. In contrast, duration of AF was of influence on 1 year outcome: AF vs. SR: 6.7 ± 7.3 vs. 2.0 ± 2.4 months; (**). No TEE or clinical variables predict initial success of CV of AF. However, 1 year after initial success, LA size, MVA width, LASC, duration of AF, and particularly LAA-pfv, are highly related to the maintenance of SR.

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.

Left Atrial Appendage Function Determined by Transesophageal Echocardiography in Patients with Rheumatic Mitral Valve Disease

Left atrial thrombi have been considered to be the major source of systemic arterial embolization in patients with rheumatic mitral valve disease. Almost half of the left atrial thrombi are found in the left atrial appendage (LAA). To investigate LAA size and LAA contractile function in patients with rheumatic mitral valve disease, transesophageal echocardiographic and Doppler studies were performed in 61 patients. Among them, 46 patients were in atrial fibrillation (group 1), while the other 15 were in sinus rhythm (group 2). Thirty-six patients with nonrheumatic atrial fibrillation were chosen as control to group 1. Another 22 patients with various cardiovascular diseases and sinus rhythm served as control to group 2. When compared to the patients with nonrheumatic atrial fibrillation (control group), group 1 patients tended to have a larger LAA maximal area (9.7 +/- 5.2 vs. 5.9 +/- 2.8 cm2; p < 0.001). LAA ejection fraction and LAA peak emptying velocity were also lower. A significantly higher incidence of LAA spontaneous echo contrast (SEC) and thrombus formation was also found in these patients. Group 2 patients were also found to have a larger LAA maximal area when compared to the control group (8.8 +/- 3.7 vs. 5.2 +/- 3.0 cm2; p < 0.001). LAA ejection fraction and LAA peak emptying velocity were lower in this group, too. A higher incidence of LAA SEC formation was found in these patients with rheumatic mitral valve disease (4/15 vs. 0/22; p = 0.021). There was no significant difference, however, in LAA thrombus formation between group 2 and its control group (1/15 vs. 1/22; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

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 mm 2) 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 mm 2). 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.