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Effects of ventricular rate and regularity on the velocity and magnitude of left atrial appendage flow in atrial fibrillation.

OBJECTIVE: To prospectively determine whether ventricular rate and regularity are significant determinants of the velocity and magnitude of left atrial appendage (LAA) flow. DESIGN AND PATIENTS: 12 patients with atrial fibrillation (AF), high degree atrioventricular block, and indwelling permanent pacemakers were studied. SETTING: Cardiology department of a tertiary referral centre. INTERVENTIONS: Pacing was triggered by an external programmable transcutaneous device. Patients were paced at 60, 120, and 150 beats/min in both regular and irregular rhythm. LAA flow velocity and magnitude were assessed with transoesophageal Doppler echocardiography. MAIN OUTCOME MEASURES: Peak and mean LAA inflow and outflow velocity, and time-velocity interval (TVI) of LAA flow. RESULTS: Increasing ventricular rate was associated with significantly lower peak inflow (p < 0.01), peak outflow (p < 0.05), mean inflow (p < 0.01), and mean outflow (p < 0.05) velocities and with a lower TVI of LAA filling and emptying velocities (p < 0.01). This effect was noted at rates of 60 beats/min compared with both 120 and 150 beats/min. At a pacing rate of 120 beats/min there was a significantly higher total TVI when pacing at a regular than at an irregular rhythm (40.16 (14.6) cm v 30.74 (10.9) cm, p < 0.05). CONCLUSIONS: In this study, LAA filling velocities in patients in AF were significantly influenced by paced ventricular rate and to a much lesser extent ventricular rhythm. These results suggest that rapid ventricular rates may predispose to stasis in the LAA in AF.

Adult↗

Left atrial appendage thrombus in atrial flutter with no associated heart disease.

The risk of cardioembolic events and the role of anti-coagulation therapy in the management of patients with lone atrial flutter is not well defined in the medical literature. We report the case of an otherwise healthy 42-year-old man with chronic established atrial flutter, unassociated with any other heart disease or systemic illness, with transesophageal echocardiographic findings of a mobile left atrial appendage thrombus. The literature to date, potential mechanisms, and recommendations are discussed. The role of transesophageal electrocardiography and anticoagulation in atrial flutter may need to be considered more seriously, especially if atrial flutter has been present for a prolonged period of time.

Adult↗

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.

Atrial Function, Left↗

Resolution of Thrombi in Left Atrial Appendage Aneurysm.

Atrial appendage aneurysm is a rare cardiac disease and may be complicated by embolic events and rhythm disturbances. We describe a case of a congenital left atrial aneurysm presenting with a cerebrovascular accident in a 57-year-old female. The diagnosis was made by transesophageal echocardiography, which revealed the presence of intraaneurysmal thrombi. The patient initially received anticoagulant therapy and the thrombi were resolved. Subsequently, she was successfully operated on and the aneurysm was removed. This is the first report of thrombi resolution in a left atrial appendage aneurysm.

Journal Article↗

Left atrial appendage smoke-like echo in dilated cardiomyopathy: its clinical significance and relation to left atrial appendage function.

To elucidate the clinical significance and pathogenesis of left atrial appendage smoke-like echo in dilated cardiomyopathy (DCM), clinical history and transesophageal echocardiographic assessment of left atrial appendage (LAA) anatomy and function were studied in 18 DCM patients with smoke-like echo (SE), 34 patients with DCM but no smoke-like echo and in 14 age-matched normal subjects. Patients with SE had a larger left atrial appendage area, a lower peak LAA systolic flow velocity (PLAAV), a greater incidence of atrial fibrillation, with both left atrial appendage thrombi and a history of arterial embolic episodes, than did patients without SE. Patients in sinus rhythm with SE had a minimal LAA area (5.0 +/- 3.0 cm2) larger than that in the no SE group (3.0 +/- 1.6 cm2) (p < 0.05), and LAA ejection fraction (18 +/- 10%) and PLAAV (24 +/- 9 cm/sec) less than that in the no SE group (40 +/- 11% and 39 +/- 16 cm/sec, respectively) (P < 0.05). Patients with atrial fibrillation (AF) and SE had PLAAV (15 +/- 6 cm/sec) less than that in AF patients without SE (30 +/- 12 cm/sec) (p < 0.05). It is concluded that smoke-like echo in LAA is an indicator of DCM patients with an increased thromboembolic risk usually associated with dilated and poorly contractile LAA.

Adult↗

Thrombus formation in the left atrial appendage in the course of atrial fibrillation.

BACKGROUND: Thromboembolism in patients with nonvalvular atrial fibrillation is secondary to emboli arising from atrial cavities, particularly left atrial appendage. Stroke Prevention Atrial Fibrillation (SPAF) III study showed washing flow, left appendage ejection fraction, natural echocontrast, and left appendage volume and morphology, as risk parameters of thromboembolism. METHODS: The authors examined 69 patients by transesophageal echocardiography, subdividing them into 3 groups: 26 patients in sinus rhythm in Group A (Gr.A), 22 patients in atrial fibrillation without thrombi in the left atrial appendage in Group B (Gr.B), 21 patients with tromboembolism and with thrombus in the left atrial appendage (Gr.C). RESULTS: Atrial volume in sinus rhythm (SR) patients (41.9 +/- 23.4 cm3) was lower than the one in Gr.B (86.2 +/- 47.9 cm3, p < 0.001) and Gr.C (78.6 +/- 28.5 cm3, p < 0.01), whereas no difference was found between Gr.B and Gr.C (86.2 vs. 78.6 cm3; p > 0.05). No difference was found between Gr.A and Gr.B left atrial appendage fraction (31.8% versus 29.1%, p > 0.05), whereas it was found related to Gr.C (31.8% versus 15.4% p < 0.01). Flow velocity within left atrial appendage was significantly higher in Gr.A in relation to the other two groups (p < 0.001); flow velocity in Gr.B was lower than in Gr.A but higher than in Gr.C and in all cases such differences were statistically significant (p < 0.001). Gr.A flow duration was approximately twice as much compared to the one in Gr.B (616.8 +/- 94.1 msec vs. 483.3 +/- 172.6 msec, p < 0.01), whereas it was approximately four times higher compared to the one in Gr.C (616.8 +/- 94.1 msec vs. 165.7 +/- 53.7 msec; p < 0.001). Such duration, if related to the corresponding cardiac cycle, indicates the percentage of time during which blood flows through a cycle within the left atrial appendage; this value is about 85% of cardiac cycle in Gr.A, while it is 65% in Gr.B (p < 0.01) and about 21% in Gr.C (p < 0.001). CONCLUSIONS: Such results add a new parameter to the ones suggested in the SPAF III study for the evaluation of TE risk, that is flow duration measurement within the left atrial appendage, and its ratio to the cardiac cycle. The availability to measure this parameter, by recording the transesophageal pulse wave sample volume positioned in the atrial appendage, makes the evaluation of TE risk more reliable.

Atrial Appendage↗

Left atrial appendage "stunning" after electrical cardioversion of atrial flutter: an attenuated response compared with atrial fibrillation as the mechanism for lower susceptibility to thromboembolic events.

OBJECTIVES: This study sought to determine whether left atrial appendage stunning occurs in patients with atrial flutter and to compare left atrial appendage function in the pericardioversion period with that in patients with atrial fibrillation. BACKGROUND: Left atrial appendage stunning has recently been proposed as a key mechanistic phenomenon in the etiology of postcardioversion thromboembolic events in atrial fibrillation. Atrial flutter is thought to be associated with a negligible risk of thromboembolic events; therefore, anticoagulation is commonly withheld before and after cardioversion in these patients. METHODS: Sixty-three patients with atrial flutter (n = 19) or atrial fibrillation (n = 44) underwent transesophageal echocardiography immediately before and after electrical cardioversion. In addition to assessing the presence of thrombus and spontaneous echo contrast, we measured left atrial appendage emptying velocity and calculated shear rates by pulsed wave Doppler and two-dimensional echocardiography. RESULTS: Patients with atrial flutter exhibited greater left atrial appendage flow velocities before cardioversion than those with atrial fibrillation (42 +/- 19 vs. 28 +/- 15 cm/s [mean +/- SD], p < 0.001). Left atrial appendage shear rates were also higher in patients with atrial flutter (103 +/- 82 vs. 59 +/- 37 s-1, p < 0.001). After cardioversion, left atrial appendage flow velocities decreased compared with precardioversion values in patients with atrial fibrillation (28 +/- 15 before to 15 +/- 14 cm/s after cardioversion, p < 0.001) and atrial flutter (42 +/- 19 to 27 +/- 18 cm/s, respectively, p < 0.001). Shear rates decreased from 59 +/- 37 before cardioversion to 30 +/- 31 s-1 after cardioversion in atrial fibrillation (p < 0.001), and from 103 +/- 82 s to 65 +/- 52 s-1, respectively (p < 0.001), in atrial flutter. This decrease in flow velocity from before to after cardioversion occurred in 36 (82%) of 44 patients with atrial fibrillation and 14 (74%) of 19 with atrial flutter. The impaired left atrial appendage function after cardioversion was less pronounced in the group with atrial flutter (27 +/- 18 cm/s for atrial flutter vs. 15 +/- 14 cm/s for atrial fibrillation, p < 0.001). New or increased spontaneous echo contrast occurred in 22 (50%) of 44 patients with atrial fibrillation versus 4 (21%) of 19 with atrial flutter (p < 0.05). CONCLUSIONS: Left atrial appendage stunning also occurs in patients with atrial flutter, although to a lesser degree than in those with atrial fibrillation. These data suggest that patients with atrial flutter are at risk for thromboembolic events after cardioversion, although this risk is most likely lower than that in patients with atrial fibrillation because of better preserved left atrial appendage function.

Aged↗

Right atrial appendage thrombosis in atrial fibrillation: its frequency and its clinical predictors.

This study assesses the incidence of right atrial (RA) chamber and appendage thrombosis in patients with atrial fibrillation (AF) in relation to RA appendage morphology and function. Transthoracic and multiplane transesophageal echocardiography were performed in 102 patients with AF to assess the incidence of RA and left atrial (LA) thrombi and spontaneous echo contrast. Both right and left ventricular sizes, atrial chamber and appendage sizes and function were measured. Twenty-two patients in sinus rhythm served as the control group (SR). Complete visualization of the RA appendage was feasible in 90 patients with AF. Patients with AF had lower tricuspid annular excursion (p = 0.008) and larger RA chamber area (p = 0.0001) than patients in SR. In addition, RA appendage areas were larger (p <0.05) and RA ejection fraction and peak emptying velocities (both p <0.0001) were lower in patients with AF patients than in those in SR. Equivalent differences were found for the LA appendage. Six thrombi were found in the RA appendage and 11 thrombi in the LA appendage in AF patients. Spontaneous echo contrast was found in 57% and 66% in the right atrium and in the left atrium, respectively. AF patients with RA appendage thrombi had a larger RA area (p = 0.0001), and lower RA appendage ejection fraction and emptying velocities (both p = 0.0001) than patients without thrombi. Spontaneous echo contrast was detected in all patients with thrombi. Spontaneous echo contrast was the only independent predictor of RA (p = 0.03) and LA appendage thrombosis (p = 0.036). In conclusion, multiplane transesophageal echocardiography allows the assessment of RA appendage morphology and function. RA spontaneous echo contrast is the only independent predictor of RA appendage thrombosis.

Adult↗

[Function of the left atrial appendage after electrical cardioversion of atrial fibrillation to sinus rhythm].

INTRODUCTION: It is widely believed that atrial fibrillation appears in a secondly manner to atrial enlargement. Morfological alteration might be the source of disturbance of electrical activation and mechanical function to fibres that facilitate arrhythmia preservation as well as life threatening complications. THE OBJECTIVE: It is crucial to establish whether reversion of atrial fibrillation to sinus rhythm causes size diminishment and function improvement of the left atrial appendage, which creates hope to avoid dangerous complications, particularly systemic embolisation. DATA AND METHODOLOGY: 30 patients were qualified including 18 males and 12 females aged between 52 and 86 (average age was 63.81 +/- 9.22). All the patients suffered from nonrheumatic atrial fibrillation. The echocardiographic examination was conducted before reversion of atrial fibrillation, right after reaching sinus rhythm and after 6 months observation at sustained sinus rhythm. During the transesophageal echocardiographic examination the following parameters were investigated: LAApodł, LAApoprz, LAAobw, LAApole, LAAF, LAAB, LAAF intg, LAAB intg, spontaneous echocardiographic contrast, thrombus. RESULTS: Left atrial appendage size right after reversion of atrial fibrillation did not considerably differ from the values registered at the time of arrhythmia. It significantly diminished in the case of sustained stabilisation of sinus rhythm. The diminishment of the left atrial appendage size was connected with its function improvement expressed by increased maximum filling and emptying velocities as well as their integrals. SEC appearance frequency considerably increased right after reaching sinus rhythm. SEC appeared very rarely in the examination after 6 months. No single case of THR in LAA was noted. At the same time several cases of THR were disclosed both before and directly after restoration of sinus rhythm. CONCLUSIONS: Sinus rhythm restoration and its sustaining for a longer period of time results in size diminishing and function improvement of left atrial appendage. The stability of sinus rhythm is closely tied with thromboembolism risk factors.

Aged↗

Assessment of left atrial appendage function after cardioversion of atrial fibrillation: relation to left atrial mechanical function.

Although several flow patterns in the left atrial appendage have been described, mechanical determinants of its function have not been elucidated in human beings. We attempted to investigate changes in left atrial appendage function after cardioversion of atrial fibrillation and examine the potential relation between appendage function and left atrial mechanical function. Twenty patients without mitral valvular disease underwent transesophageal and transthoracic echocardiography at 24 hours and 1 week after cardioversion of atrial fibrillation. Left atrial appendage function was assessed by the pulsed Doppler measurements of left atrial appendage emptying and filling velocities corresponding to early and late ventricular diastole, respectively. Left atrial mechanical function was evaluated by the transmitral A-wave velocity, percent atrial contribution of the total left ventricular filling (percent atrial filling), and the pulmonary venous A-wave velocity. Left ventricular function was also estimated with conventional M-mode echocardiography. The late appendage emptying and filling velocities markedly increased during 1 week after cardioversion (p < 0.0001, respectively). This finding was associated with an increase in left atrial mechanical function. Changes in the late emptying and filling velocities significantly correlated with changes in the transmitral A-wave velocity (r = 0.59, p < 0.01), percent atrial filling (r = 0.61, p < 0.005), and the pulmonary venous A-wave velocity (r = 0.56, p < 0.05). In contrast, little change was observed in the early emptying and filling velocities. There was no relation between the indexes of left ventricular function and those of appendage function. In conclusion, unless there was an alteration of the loading conditions, left atrial appendage function improved over several days after cardioversion, and its function was related to left atrial mechanical function.

Adult↗

Inverted left atrial appendage mimicking a left atrial mass during mitral valve repair.

This case report describes the appearance of a new homogenous mass seen in the left atrium on intraoperative transesophageal echocardiography after mitral valve repair. This "mass" was the inverted left atrial appendage. Echocardiographers need to recognize normal variants, such as an inverted left atrial appendage, to avoid misdiagnosis.

Aged↗

Relationship between left atrial appendage function and left atrial thrombus in patients with nonvalvular chronic atrial fibrillation and atrial flutter.

The relationship between the left atrial appendage (LAA) function, as assessed by transesophageal echocardiography, and the incidence of left atrial thrombus was evaluated in 62 patients with nonvalvular chronic atrial fibrillation (AF; n=50) and atrial flutter (AFL; n=12). It was hypothesized that in both AF and AFL not only the LAA flow velocity (LAAFV), but also the frequency of the LAA movement (the LAA flow time, LAAFT) is a major contributing factor to thrombus formation. LAAFT was defined as the average duration of LAA flow with emptying and filling waves. The patients with AF were divided into 2 groups: lone AF (n=14) and non-lone AF (n=36). LAA thrombus was found in 6 patients with none-lone AF. LAAFV was lower and LAAFT was shorter in patients with thrombus as compared with patients without thrombus (12.0+/-2.2 cm/s vs 24.1+/-10.6 cm/s, 68.7+/-1.5 ms vs 72.9+/-3.3 ms, p<0.01, respectively). Patients with AFL had higher LAAFV and longer LAAFT than those with chronic AF. The present data suggest that, in addition to LAAFV, LAAFT characterized LAA function and might serve as a predictor of thrombus formation in chronic AF. With respect to LAA function, patients with lone AF or AFL are at low risk for thrombus formation.

Aged↗

Evaluation of a novel device for left atrial appendage exclusion: the second-generation atrial exclusion device.

BACKGROUND: The left atrial appendage is a frequent source of thromboemboli in patients with atrial fibrillation. Exclusion of the left atrial appendage may reduce the risk of stroke in patients with atrial fibrillation. The atrial exclusion device, previously developed to perform left atrial appendage exclusion on a beating heart, was modified to accommodate different anatomic patterns of the human left atrial appendage and to ensure uniform pressure and occlusion. The purpose of this study was to evaluate this second-generation atrial exclusion device during a midterm period in a canine model. METHODS: Ten mongrel dogs (mean weight 28.9 +/- 4.6 kg) were used in this study. The atrial exclusion device, constructed from two parallel and rigid titanium tubes and two nitinol springs with a knit-braided polyester fabric, was implanted at the base of the left atrial appendage through a left thoracotomy on a beating heart using a specially designed delivery tool. Dogs were evaluated at 30 days (n = 4) and 90 days (n = 6) by epicardial echocardiography, left atrial and coronary angiography, gross pathology, and histologic inspection. RESULTS: Device implantation was performed without complications in all dogs. Complete left atrial appendage exclusion without device migration or hemodynamic instability was confirmed, and there was no damage to the left circumflex artery or pulmonary artery. Macroscopic and microscopic assessments revealed favorable biocompatibility during midterm follow-up. CONCLUSION: The atrial exclusion device enabled rapid, reliable, and safe exclusion of the left atrial appendage. Clinical application may provide a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation.

Animals↗

Comparison of the acute effects of pacing the atrial septum, right atrial appendage, coronary sinus os, and the latter two sites simultaneously on the duration of atrial activation.

OBJECTIVE: To compare the acute effects of right atrial appendage, atrial septal, coronary sinus os, and dual site pacing on the duration of atrial activation. METHODS: 20 patients with a variety of cardiac conditions underwent an intracardiac electrophysiological study. Electrograms were recorded from the right atrial appendage and at multiple sites within the coronary sinus. The duration of atrial activation was measured during pacing at the right atrial appendage, atrial septum, and coronary sinus os, and also during dual site stimulation. RESULTS: The duration of atrial activation with atrial appendage pacing was notably longer (p < 0.001) than with dual site, septal, or coronary sinus os pacing, but there were no significant differences in atrial activation times between these latter three pacing modes. When stimulating the atria at a cycle length of 500 ms, the mean (SD) duration of atrial activation was 145 (37) ms for right atrial appendage pacing, 93 (26) ms for dual site pacing, 96 (28) ms for septal pacing, and 98 (28) ms for coronary sinus os pacing. CONCLUSIONS: Assuming that the duration of atrial activation is an important determinant of predisposition to paroxysmal atrial fibrillation, atrial septal pacing or coronary sinus os pacing would appear to offer the same advantage as dual site pacing without the additional complexities associated with the latter pacing mode.

Adult↗

Left Atrial Appendage Occlusion Study (LAAOS): results of a randomized controlled pilot study of left atrial appendage occlusion during coronary bypass surgery in patients at risk for stroke.

AIM: This pilot study assessed the safety and efficacy of left atrial appendage (LAA) occlusion, performed at the time of coronary artery bypass grafting (CABG). METHODS AND RESULTS: At the time of CABG, 77 patients with risk factors for stroke were randomized to LAA occlusion or control. The LAA was occluded using sutures or a stapling device. Completeness of occlusion was assessed with transesophageal echocardiography. There were no significant differences in cardiopulmonary bypass duration, perioperative heart failure, atrial fibrillation, or bleeding between the 2 groups. During surgery, there were 9 appendage tears, all of which were repaired easily with sutures. Among patients having a postoperative transesophageal echocardiography, complete occlusion of the LAA was achieved in 45% (5/11) of cases using sutures and in 72% (24/33) using a stapler, P = .14. The rate of LAA occlusion by individual surgeons increased from 43% (9/21) to 87% (20/23) after performing 4 cases (P = .0001). After a mean follow-up of 13 +/- 7 months, 2.6% of patients had thromboembolic events. CONCLUSIONS: LAA occlusion at the time of CABG is safe. The rate of complete occlusion improves, to acceptable levels, with increased experience and the use of a stapling device. A large trial is needed to determine if LAA occlusion prevents stroke.

Aged↗