Two-dimensional echocardiographic imaging of left atrial appendage thrombi

Prevalence and predictors of left atrial appendage inactivity in patients of rheumatic mitral stenosis in sinus rhythm: An observational study

BACKGROUND

Systemic thromboembolism is a known complication of rheumatic mitral stenosis (RMS) in sinus rhythm (SR). Left atrial appendage (LAA), the commonest site of thrombus formation is usually hypocontractile (inactive) in such patients. We aimed to study the prevalence of LAA inactivity (LAAI) in severe RMS and assess its independent predictors.

METHODS

The study population consisted of 100 patients of severe RMS in SR. Transthoracic and transesophageal echocardiography were done to assess LAA contractile function. Patients with LAA-peak emptying velocity < 25 cm/seconds were defined as having LAAI.

RESULTS

The mean age of study subjects was 31.66±8.69 years and 56% were females. 73% patients had LAAI (Group A), while remaining 27% had normal LAA function (Group B). Mitral-valve area (MVA) and lateral annulus systolic velocity (Sa-wave) were significantly lower while mitral valve mean gradient (MVMG) and serum fibrinogen were significantly higher (all p-values < 0.001) in group A patients. On multivariate binary logistic regression analysis, MVMG (p < 0.001), Sa-wave (p = 0.02), and serum fibrinogen (p = 0.005) were independent predictors of LAAI. Optimal cut-off values of MVMG, Sa-wave and serum fibrinogen for predicting LAAI were 11.5 mm Hg, 6.8 cm/seconds and 300 mg/dl, respectively. Sixty-Seven (90.55%) patients in group A compared to 13(48.1%) in group B had LA/LAA smoke. LAAI was the only independent predictor of left atrium (LA)/LAA smoke with or without associated thrombus.

CONCLUSION

There is high prevalence of LAAI in patients of severe MS in SR. MVMG, Sa-wave, and serum fibrinogen levels are independent predictors of LAAI. LAAI is an independent predictor of LA/LAA smoke with or without associated thrombus.

Baseline D-Dimer Levels as a Risk Assessment Biomarker for Recurrent Stroke in Patients with Combined Atrial Fibrillation and Atherosclerosis

Background: We investigated the effect of D-dimer levels and efficacy of different antithrombotic therapies according to the baseline D-dimer levels on recurrent stroke in patients with atrial fibrillation (AF)-related stroke and atherosclerosis. Methods: We enrolled 1441 patients with AF-related stroke and atherosclerosis in this nationwide multicenter study. The primary outcome measure was the occurrence of recurrent ischemic stroke over a 3-year period. Results: High D-dimer levels (≥2 μg/mL) were significantly associated with higher risk of recurrent ischemic stroke (adjusted hazard ratio (HR), 1.80; 95% confidence interval (CI), 1.13–2.84; p = 0.012). The risk of recurrent stroke was similar between the anticoagulant and the antiplatelet groups in all subjects (adjusted HR, 0.78; 95% CI, 0.46–1.32; p = 0.369). However, in patients with high D-dimer levels (≥2 μg/mL), risk of recurrent stroke was significantly lower in the anticoagulant group than in the antiplatelet group (adjusted HR, 0.40; 95% CI, 0.18–0.87; p = 0.022). Conclusion: Our findings suggested that baseline D-dimer levels could be used as a risk assessment biomarker of recurrent stroke in patients with AF-related stroke and atherosclerosis. High D-dimer levels would facilitate the identification of patients who are more likely to benefit from anticoagulants to ensure secondary prevention of stroke.

Giant left atrial appendage aneurysm: the third ventricle!

The giant congenital intrapericardial aneurysmal dilatation of the left atrial appendage without mitral valve disease is a very rare condition that is generally diagnosed in older patients. The problem is usually accompanied with supraventricular rhythm disorders and life-threatening systemic thromboembolism. Complete surgical correction is possible, and it should be performed immediately after the diagnosis. We are going to describe a patient with a history of cerebral thromboembolism and palpitation who was diagnosed with congenital intrapericardial aneurysmal dilatation of the left atrial appendage. The condition was identified by means of echocardiography and was surgically treated by resection of the appendage containing the aneurysm.

Usefulness of transthoracic echocardiography for identification of left atrial thrombus before balloon mitral valvuloplasty

The objectives of this study were (1) to identify clinical and transthoracic echocardiographic features of patients with mitral stenosis who have thrombus recognized on transesophageal echocardiography, and (2) to define a clinical and echocardiographic model to predict the presence of left atrial thrombus in these patients.

Imaging of thrombi and assessment of left atrial appendage function: a prospective study comparing transthoracic and transoesophageal echocardiography

OBJECTIVE

To compare the value of current transthoracic echocardiographic systems and transoesophageal echocardiography for assessing left atrial appendage function and imaging thrombi.

DESIGN

Single blind prospective study. Patients were first investigated by transthoracic echocardiography and thereafter by a second investigator using transoesophageal echocardiography. The feasibility of imaging the left atrial appendage, recording its velocities, and identifying thrombi within the appendage were determined by both methods.

PATIENTS

117 consecutive patients with a stroke or transient neurological deficit.

SETTING

Tertiary cardiac and neurological care centre.

RESULTS

Imaging of the complete appendage was feasible in 75% of the patients by transthoracic echocardiography and in 95% by transoesophageal echocardiography. Both methods were concordant for the detection of thrombi in 10 cases. Transoesophageal echocardiography revealed two additional thrombi. In one of these patients, transthoracic echocardiography was not feasible and in the other the thrombus had been missed by transthoracic examination. In patients with adequate transthoracic echogenicity, the specificity and sensitivity of detecting left atrial appendage thrombi were 100% and 91%, respectively. Recording of left atrial appendage velocities by transthoracic echocardiography was feasible in 69% of cases. None of the patients with a velocity > 0.3 m/s had left atrial appendage thrombi. In the one patient in whom transthoracic echocardiographic evaluation missed a left atrial appendage thrombus, the peak emptying velocity of the left atrial appendage was 0.25 m/s.

CONCLUSIONS

A new generation echocardiographic system allows for the transthoracic detection of left atrial appendage thrombi and accurate determination of left atrial appendage function in most patients with a neurological deficit.

Left atrial appendage function in mitral stenosis: is a group in sinus rhythm at risk of thromboembolism?

OBJECTIVE

To study the left atrial appendage (LAA) function and potential for embolization in severe mitral stenosis (MS).

BACKGROUND

Patients with MS and atrial fibrillation or in sinus rhythm develop systemic emboli. LAA function has not been well studied in sinus rhythm.

METHODS

Forty consecutive patients with MS (valve area < or =0.7 cm2/m2) were studied. LAA ejection fraction and peak emptying velocity were measured along with other data.

RESULTS

Patients were subgrouped according to LAA Doppler flow pattern. Group I (n=13) in sinus rhythm had biphasic high velocity > or =25 cm/s. Group II (n=13) in sinus rhythm had biphasic low velocity <25 cm/s. Group III (n=14) in atrial fibrillation had multiphasic irregular flow <25 cm/s or no definite flow. The LAA ejection fraction and peak emptying velocity were strikingly different in all groups. They were lower in group II when compared to group I. Group II had intermediate risk for thromboembolism compared to Group I and III as judged by systemic embolization, spontaneous echo contrast, thrombus in left atrium and LAA.

CONCLUSION

A subset of mitral stenosis in sinus rhythm at increased risk of embolization can be suspected by Doppler transesophageal echocardiographic LAA flow profile.

Comparative evaluation of transthoracic and transesophageal echocardiography in detection of left atrial thrombus before percutaneous transvenous mitral commissurotomy. Do all patients need transesophageal examination?

We postulated that the sensitivity of transthoracic echocardiography in detection of left atrial cavity or appendage thrombi is better in south-east asian patients with rheumatic mitral stenosis. This was considering that these patients are generally younger, have lesser body weight and thinner chest walls resulting in better transthoracic echogenecity than their western counterparts. We prospectively performed transthoracic and transoesophageal echocardiography in 150 consecutive Indian patients (mean age 28.8+/-7.2 years; 78 men) being evaluated for percutaneous transvenous mitral commissurotomy. The overall sensitivity of transthoracic echocardiography was 74% (95% C.I. 59-88%). This was significantly higher than the pooled estimate from five western reports which evaluated similar patients (overall sensitivity 12%; 95% C.I. 0-25%; P<0.0001). The sensitivity rose to 83% when patients with poor echogenecity were excluded. Amongst patients with good echogenecity (81% patients) the diagnosis of left atrial thrombi was correctly made or suspected on transthoracic examination in all patients subsequently shown to have thrombi on transoesophageal echocardiography. Significant savings in cost may be safely achieved by limiting transoesophageal echocardiography to patients in whom left atrial cavity or appendage is not adequately visualized on transthoracic examination due to poor echogenecity, or in whom there are shadows suggestive but not diagnostic of thrombi.

Role of transesophageal echocardiography in the management of thromboembolic stroke

Cardiac causes of stroke account for approximately 20% of strokes occurring in the United States. Transthoracic echocardiography (TTE) remains the cornerstone of non-invasive cardiac imaging, but transesophageal echocardiography (TEE) is superior for identifying potential cardiac sources of emboli, including left atrial thrombi, valvular vegetations, thoracic aortic plaque, patent foramen ovale, and spontaneous left atrial echocardiographic contrast. The diagnostic yield of TEE for potential cardiac causes of thromboembolism exceeds 50%. The impact of TEE on the clinical management of this group, however, remains undefined for most TEE-specific diagnoses. Thus, routine use of TEE in these patients has been questioned. The diagnostic yield is highest if the clinical history/physical examination suggests a cardiac source. However, the clinical scenario often dictates patient management, and TEE data are used to "validate" the clinical impression. Data from large, prospective, randomized (aspirin/warfarin) studies, in which TEE data are obtained from patients with suspected cardiac thromboembolism, are needed. If specific TEE diagnoses can be identified in which defined therapies are beneficial, "source of embolism" will continue to be the most common indication for TEE referral. In this paradigm, TEE (without initial TTE) will probably become a more direct diagnostic pathway. However, if these studies demonstrate that all patients with suspected cardiac source benefit from one (or no) therapy, independent of TEE data, referrals for TEE will decline. Results of ongoing randomized trials to evaluate the efficacy of TEE in patients with cryptogenic stroke or transient ischemic attack are awaited.

Time interval determination from left atrial appendage ejection flow in patients with mitral stenosis

The feasibility of determining the time interval from left atrial appendage (LAA) flow was examined using transesophageal Doppler echocardiography. Time intervals were compared between LAA flow and mitral flow patterns during late diastole in 8 patients with mitral stenosis and in 12 controls. The start of ejection flow from the LAA was later than the initiation of mitral flow, but the termination was same in both flows, indicating the contribution of LAA ejection to the latter half of the left atrial booster pump function. The pre-ejection time and the time interval from P-wave to end-ejection correlated significantly with left atrial dimensions (r = 0.55, and r = 0.70, respectively). The pre-ejection time, duration of the ejection flow from the LAA, and duration of mitral flow in the atrial contraction phase were significantly longer in patients with mitral stenosis (126 +/- 14 msec, 131 +/- 36 msec, and 167 +/- 28 msec, respectively) than in the controls (109 +/- 13 msec, 108 +/- 15 msec, and 141 +/- 17 msec, respectively). These results indicate that electrical conduction time from the right atrium to LAA can be estimated from the LAA ejection flow, and the time is related to the left atrial size. In patients with mitral stenosis, LAA contraction may contribute to left ventricular filling in the latter half of the atrial contraction phase.

Role of transesophageal echocardiography in the detection of left atrial thrombus in patients with chronic nonrheumatic atrial fibrillation

Transesophageal echocardiography was used to assess cardiac abnormalities associated with embolization in patients who had completed the Department of Veterans Affairs Cooperative Study of Stroke Prevention in Nonrheumatic Atrial Fibrillation at the Minneapolis and West Haven Department of Veterans Affairs Medical Centers without an embolic event. Patients were men, 71 +/- 7 years old, with atrial fibrillation of 6.2 +/- 4.3 years' duration who had received warfarin (n = 32) or placebo (n = 23) for 2 years. Thrombi were found in 5 of 55 patients (warfarin 4 and placebo 1; p = 0.39); spontaneous echo contrast was seen in 4 of 5 patients. Other abnormalities identified included spontaneous echo contrast (47%), patent foramen ovale (54%), atrial septal aneurysm (7.3%), and left ventricular thrombus (3.6%). During 34 months of posttreatment follow-up, 5 patients had a stroke (1 fatal), and 10 died. Potential sources of emboli did not predict subsequent outcome. Thus warfarin therapy did not preclude the presence of thrombi. Stroke reduction likely involves the prevention of emboli from sources in addition to the atrial appendage.

Morphology of the left atrial appendage

BACKGROUND

When examining the left atrial appendage by transesophageal echocardiography, differences in size and shape of the left atrial appendage are to be observed. The study was carried out with the aim of investigating the morphology of the left atrial appendage and to find associations with pathologic cardiac findings.

METHODS AND RESULTS

In 220 cases (106 female, 114 male, mean age 72 +/- 13 years) a cast of the left atrial appendage was made after the post mortem examination by using synthetic resin. In 198 cases an ECG was available (sinus rhythm n = 143, atrial fibrillation n = 55). The casts were described in respect to course and ramifications of the principal axis. The casts were measured concerning orifice diameters, outline, and volume. Most frequently (42%) the course of the principal axis was angulated below 100 degrees. More than five ramifications of the principal axis were found in 56% of the casts. The volume ranged from 770-19,270 mm3 (mean 5,220 +/- 3,041). When comparing the clinical and autopsy-data of the patients with the morphology of the casts, associations could be found between the volume of the casts and atrial fibrillation (7,060 mm3 as compared to 4,645 mm3 in sinus rhythm, P < 0.01), left ventricular hypertrophy (5,740 mm3 as compared to 4,639 mm3 without hypertrophy, P < 0.01), myocardial scars (5,923 mm3 as compared to 4,891 mm3 without scars, P < 0.05), closed foramen ovale (5,515 mm3 as compared to 4,037 mm3 with patent foramen ovale, P < 0.01), and left atrial appendage thrombi (8,566 mm3 as compared to 5,027 mm3 without thrombi, P < 0.01).

CONCLUSION

Left atrial appendages are formations greatly varying in volume and shape. This variability should be considered when interpreting images of the left atrial appendage, and in particular when diagnosing thrombi.

Echocardiographic study of left atrial thrombi in mitral stenosis

Sixty-nine patients with predominant mitral stenosis were examined by echocardiographic means to detect the presence of left atrial thrombi. Forty-nine of these patients were in sinus rhythm and twenty in atrial fibrillation. Four percent of patients in the sinus rhythm group and 45% of those in the atrial fibrillation group had left atrial thrombi. The two risk factors identified for left atrial thrombi in mitral stenosis were atrial fibrillation and left atrial enlargement.

Diagnostic accuracy of transesophageal echocardiography for detecting left atrial thrombi in patients with rheumatic heart disease having undergone mitral valve operations

Transesophageal echocardiography (TEE) has emerged as an efficient method for detecting left atrial (LA) thrombi in recent years, but its accuracy has not been fully evaluated. A prospective clinicopathologic study in 213 consecutive patients with chronic rheumatic mitral valve disease over a period of 39 months was undertaken. All patients underwent open heart surgery within 3 days after the TEE study. The presence or absence of LA thrombi was confirmed at surgery by direct inspection of the left atrium and proven by histopathologic examination. Of the 213 patients, 147 had predominant mitral stenosis, and the remaining 66 patients had significant mitral regurgitation. Twenty-eight patients had LA thrombi by TEE criteria. These findings were all confirmed at surgicopathologic studies (specificity 100%). However, in 2 patients, LA thrombi were present but could not be detected by TEE (sensitivity 93.3%). Therefore, the positive predictive value was 100%, the negative predictive value was 98.9% and the diagnostic accuracy was 99.1%. No thrombi were found in patients with significant mitral regurgitation. The frequency of LA thrombi in patients with predominant mitral stenosis was 20% (30 of 147), and most of these patients had chronic atrial fibrillation (28 of 30, 93%). Only 16 patients (16 of 30, 53%) were found to have LA thrombi by transthoracic echocardiography. Furthermore, our data showed poor correlation between the echogenicity of LA thrombi and the degree of thrombus organization. Thus, TEE is excellent for detecting LA thrombi in patients with rheumatic heart disease severe enough to warrant mitral valve operations.

Echocardiography in the evaluation of cardiac sources of emboli: the role of transthoracic echocardiography

Cardioembolism is responsible for a significant number of systemic emboli including approximately 15% of all ischemic strokes. Transthoracic echocardiography has contributed to the understanding of cardioembolism and has been used to detect specific and potential cardiac sources of systemic emboli and risk stratify patients with specific clinical findings for subsequent cardiovascular events. Findings from transthoracic echocardiography indicate that stasis is an important prerequisite for intracardiac thrombosis while reversal of stasis and thrombolysis appear operative in embolism of existing thrombus. Transthoracic echocardiography allows a sensitive and specific noninvasive means to detect left ventricular thrombus, valvular vegetation, and intracardiac tumor, lesions that are directly responsible for cardioembolism. Transthoracic echocardiography can also detect lesions that could potentially contribute to cardioembolism but are not specific causes. Examples of these potential lesions include mitral valve prolapse, patent foramen ovale, and interatrial septal aneurysm. Finally, population-based studies and prospective clinical trials have indicated that the results of transthoracic echocardiography have predictive value for subsequent cardiovascular events and hence provide a means for stratification of patients at risk for cardioembolism. The latter is most notable for the group of patients with nonvalvular atrial fibrillation where left ventricular dysfunction and increased left atrial size are independent predictors for subsequent stroke.

The role of transesophageal echocardiography in the detection of left atrial thrombi

Sensitivity of transthoracic echocardiography in the detection of left atrial thrombi, in particular thrombi confined to the left atrial appendage, is surprisingly low (33%-72%). Concerning the detection of left atrial thrombi, transthoracic echocardiography appears as an inadequate technique in patients with suspected cardiogenic embolism with a success rate of only 0.8% in earlier, and about 3% in recent studies. Imaging from the esophagus substantially increases the detection rate for left atrial thrombi, and is the only clinically relevant semiinvasive technique to diagnose thrombi confined to the left atrial appendage. Transesophageal echocardiography has markedly increased the diagnostic power of cardiovascular ultrasound in patients with suspected cardiogenic embolism and/or atrial fibrillation. Meta-analysis of pooled studies using the transesophageal approach in these patients revealed thrombi within the left atrial cavity in about 7% and within the atrial appendage in about 12% of cases.

Transesophageal echocardiography as a tool in the evaluation of patients with embolic disorders

TEE has become one of the most powerful tools for evaluating patients with unexplained stroke, TIA, and peripheral and pulmonary embolization. This is especially encouraging in view of the previously disappointing results of TTE in these patients. In addition to the dramatic results in terms of clot visualization and the other intracardiac sources of embolization described previously, a new extracardiac source has been identified, namely protruding atheromas in the thoracic aorta. These atheromas have been seen for the first time because of the new diagnostic window that has been opened by the development of TEE. Their recognition and follow-up may lead to information that will change the approach to a significant number of patients with embolic ischemic episodes.

Diagnosis of right atrial mass lesions by transesophageal and transthoracic echocardiography

The echocardiographic findings by transesophageal and transthoracic techniques were compared in 16 patients with right atrial mass lesions diagnosed by transesophageal echocardiography. In only 8 of the 16 patients were the masses imaged by transthoracic echocardiography. Masses in the main body of the right atrium (three of five), as well as those associated with indwelling catheters and pacer wires (three of four) were more likely to be imaged by transthoracic echocardiography than masses in the right atrial appendage (zero of three) or in the superior or inferior vena cava (one of three). Associated masses in other cardiac chambers were detected by transthoracic echocardiography in three of six patients. Other features such as size, mobility, and site of attachment of right atrial masses in general were better defined by transesophageal echocardiography. Thus, patients with suspected right atrial masses should be investigated with transesophageal echocardiography.

Use of echocardiography in detecting cardiac sources of embolus

Up to 20% of all ischemic strokes are felt to be the result of emboli from the heart. High resolution transthoracic (TTE) and transesophageal (TEE) echocardiography have been the principal diagnostic tools for detecting associated cardiac abnormalities and for guiding medical and surgical approaches to these patients. In addition to identifying the precise location and morphological characteristics of intracardiac masses, echocardiography has improved our ability to predict embolic potential of these masses. Specific cardiac lesions that are predisposed to stroke and are readily identifiable by echocardiography include: cardiac thrombi, valvular vegetations, cardiac tumors, aortic atheroma, atrial septal aneurysm, and regional left ventricular wall abnormalities. Careful interrogation of patients with cerebrovascular accidents has identified a potential cardiac source of embolus in approximately 30%. This is largely due to the advent of TEE, which has provided much better assessment of posterior cardiac chambers including left atrium and left atrial appendage. Use of TEE in identifying a cardiac source of embolus is indicated in patients with stroke who are young, have no apparent cerebrovascular disease, or have recurrent embolic events. Echocardiography is an essential diagnostic tool in evaluating patients with a suspected cardiac source of embolus. TTE and TEE provide invaluable information regarding the majority of cardiac sources of embolus.

Left atrial thrombi in non-rheumatic atrial fibrillation: assessment of prevalence by transesophageal echocardiography

To determine the prevalence of left atrial thrombus in hospitalized patients with non-rheumatic atrial fibrillation, 48 patients were consecutively studied with single-plane transesophageal echocardiography. There were 23 males (48%) and 25 females (52%). The mean age was 66 +/- 11 years (range 43-87). Thrombus was detected in 13 patients (27%): 11 were confined to the left atrial appendage, 1 to the atrial body and appendage, and 1 to the left upper pulmonary vein. Prevalence of atrial thrombus was not different among those patients with or without previous stroke [4/16 (25%) vs 9/32 (28%), p = NS] or between patients > 65 years and patients < or = 65 years old (p = NS). Atrial thrombus was detected more frequently in patients with reduced left ventricular global systolic function than in those with normal function [7/14 (50%) vs 6/34 (17%), p < 0.05]. In patients with spontaneous contrast echoes in the left atrium, thrombi were visualized more often than in those without spontaneous echoes [10/24 (41%) vs 3/24 (12%), p < 0.05]. The finding of the atrial spontaneous contrast echoes was more frequent among patients with reduced left ventricular global systolic function [11/14 (78%) vs 13/34 (37%), p < 0.02]. We conclude that in hospitalized patients with non-rheumatic atrial fibrillation the prevalence of left atrial thrombus is high. Reduced left ventricular global systolic function identifies a subset of patients at high risk for formation of thrombus in the left atrium.

Left atrial thrombus and spontaneous echo-contrast in nonanticoagulated mitral stenosis. A transesophageal echocardiographic study

OBJECTIVE

The aim of the study was to investigate if evidence at transthoracic echocardiography (TTE) of left atrial (LA) thrombus and LA spontaneous echo-contrast (LA SEC), which are potential precursors of embolization, can be predicted by clinical and TTE variables in nonanticoagulated mitral valve stenosis (MS).

DESIGN

Clinical (age, NYHA class, rhythm, previous embolization) and TTE variables were related to transesophageal echocardiography (TEE) evidence of LA thrombus and/or LA SEC.

SETTING

Nonanticoagulated MS was the setting.

PATIENTS

Fifty-nine patients had MS, and they were not receiving anticoagulant or antiplatelet therapy (24 in sinus rhythm and 35 in atrial fibrillation). Previous arterial embolization had occurred in 12 patients (20.3 percent).

MEASUREMENTS

The following TTE variables were analyzed: mitral orifice area (pressure half-time method), mitral gradient (Bernouilli's equation), LA end-systolic area, and mitral regurgitation (color Doppler grading). LA thrombus and LA SEC were analyzed by monoplane TEE.

RESULTS

LA thrombus was found by TEE in 12 patients (20.3 percent). Of these 12, 11 (91.6 percent) were in atrial fibrillation. LA SEC was found by TTE in 2 patients (3.5 percent) and by TEE in 40 (67.8 percent) (p < 0.001). Previous embolization had occurred only in patients with LA SEC, of whom 5 had and 7 did not have LA thrombus. Patients with LA SEC, compared with those without LA SEC, were characterized by more frequent advanced NYHA class, atrial fibrillation, smaller mitral valve area, and larger LA size. By multivariate regression analysis, atrial fibrillation and LA end-systolic area were factors related to both LA thrombus and LA SEC, whereas mitral area was related only to LA SEC. However, whereas LA SEC was accurately predicted by the presence of atrial fibrillation (sensitivity: 87.5 percent; specificity: 100 percent) and a LA area > or = 30 cm2 (sensitivity: 72.5 percent; specificity: 89.5 percent), among patients with LA SEC no clinical or TTE variable accurately identified those with actual LA thrombus.

CONCLUSIONS

TEE is not necessary in many patients with MS in order to recognize LA SEC. However, when actual LA thrombus detection is necessary for clinical decision making, TEE should be performed.

Reappraisal by transesophageal echocardiography of the significance of left atrial thrombi in the prediction of systemic arterial embolization in rheumatic mitral valve disease

Systemic arterial embolization imparts a significant risk of serious complications throughout the lives of patients with rheumatic heart disease. Left atrial (LA) thrombi have been thought to be the major source of emboli. A transesophageal echocardiography (TEE) study of 260 consecutive patients with rheumatic mitral valve disease was performed during a period of 24 months, with particular reference to understanding the association between LA thrombi and embolic complications. Of these patients, 155 had predominant mitral stenosis, 24 had significant mitral regurgitation, and the remaining 81 with xenograft mitral valve replacement developed valvular dysfunction (25 resulted in predominant mitral stenosis and 56 in significant mitral regurgitation). LA thrombi were detected in 38 patients (group A) and absent in 222 (group B). Group A patients had a higher frequency of recent (less than or equal to 1 week before TEE study) and remote (greater than 1 week before) embolization than did group B patients (recent: 26.3 vs 5.4% [p less than 0.001]; remote: 18.4 vs 5.0% [p less than 0.01]). The frequency of atrial fibrillation was also greater in group A patients (100 vs 74.3%; p less than 0.001). The exclusion of patients with significant mitral regurgitation and sinus rhythm had no effect on the association between LA thrombi and evidence of previous embolization. It is concluded that TEE is a convenient diagnostic modality that can be used to identify a subset of patients with rheumatic mitral valve disease at high risk for systemic embolization. Consequently, preventive anticoagulation for possible embolic complications should be more vigorously adhered to in patients with rheumatic mitral valve disease and LA thrombi.

Transesophageal echocardiography

Transesophageal echocardiography has provided a new acoustic window to the heart, the great vessels, and the mediastinum. It provides anatomical, functional hemodynamic, and blood flow information. High-quality visualization of left atrial appendage, thoracic aorta, atrial septum, and mitral valvular apparatus can be obtained readily. We discuss historical and technical aspects of transesophageal echocardiography, anatomical views, and major clinical indications for this procedure. These indications include intracardiac masses, thoracic aortic dissection, endocarditis, prosthetic and native cardiac valve function assessment, as well as its value in the detection of intracardiac source of systemic emboli. Furthermore, the role of transesophageal echocardiography in the assessment of coronary artery and congenital heart disease and as an intraoperative diagnostic and monitoring technique is discussed.

Usefulness of transesophageal echocardiography for the detection of left atrial thrombi in patients with rheumatic heart disease

Transesophageal (TEE) and transthoracic (TTE) echocardiograms were performed in 110 patients with rheumatic heart disease to evaluate the usefulness of these methods for the detection of left atrial thrombi. TEE was better than TTE for detecting left atrial thrombi (21 vs 9). The thrombi not detected by TTE were in the left atrial appendage in ten and over the left atrial posterior wall in two. Patients with left atrial thrombi had significantly smaller mitral valve area (P less than 0.01) and greater left atrial dimension (P less than 0.05) than those without. All patients with left atrial thrombi had atrial fibrillation. Thirty-one patients underwent surgical intervention and 13 were found to have left atrial thrombi. TEE detected left atrial thrombi in all 13 patients with a sensitivity of 100%, specificity of 100%, and accuracy of 100%, while TTE detected left atrial thrombi in only nine of these 13 patients with a sensitivity of 69.2%, specificity of 100%, and accuracy of 87.1%. Thus, TEE is superior to TTE for the detection of left atrial thrombi, especially for those thrombi located in the left atrial appendage and along the left atrial posterior wall.

Exclusion of atrial thrombus by transesophageal echocardiography

To determine whether transesophageal echocardiography (TEE) is useful in ruling out the presence of atrial thrombus, we performed TEE in 20 patients immediately before valve replacement or valve repair and within 3 days of an autopsy in one patient. Mitral stenosis was the predominant lesion in three patients, mitral regurgitation was seen in 11 patients, five patients had mitral prosthesis malfunction, one patient had a tricuspid prosthesis malfunction, and one patient had aortic stenosis. Eight patients were in atrial fibrillation. Four patients demonstrated spontaneous contrast in the associated atria. Nine patients were receiving oral anticoagulation. Mean left atrial diameter was 5.3 +/- 1.3 mm. TEE revealed no evidence for atrial thrombus in 18 of the 21 patients; this finding was confirmed by careful inspection of the atria including the appendages. TEE demonstrated a left atrial thrombus in two patients and a right atrial thrombus in another (confirmed at the time of surgery or at autopsy). In all cases transthoracic echocardiography was negative. Our data suggest that TEE is useful in ruling out atrial thrombus, and therefore may be a useful test preceding interventions associated with an increased risk of embolism from the atria such as cardioversion, mitral valvuloplasty, or valve replacement.

Assessment of left atrial appendage function by transesophageal echocardiography. Implications for the development of thrombus

BACKGROUND

The predilection of the left atrial appendage (LAA) for thrombus formation has long been known.

METHODS AND RESULTS

We prospectively studied the two-dimensional echocardiographic and Doppler patterns of LAA function in 82 patients by transesophageal echocardiography. In the 63 patients in sinus rhythm, LAA area was measured during LAA diastole at the onset of the electrocardiographic (ECG) P wave (LAAmax) and after LAA systole at the ECG R wave (LAAmin) and LAA ejection fraction was calculated as (LAAmax-LAAmin)/LAAmax; peak Doppler velocity was recorded from the LAA outlet. The 58 patients in sinus rhythm without LAA thrombus were grouped according to left atrial size on transthoracic echocardiography; 39 patients had a left atrial size of less than 40 mm (group 1) and 19 had a left atrial size of 40 mm or greater (group 2). Five patients in sinus rhythm had LAA thrombus. In the 19 patients with atrial fibrillation or flutter LAAmax was measured independent of the ECG; three of these patients had LAA spontaneous contrast, four had thrombus, and one had both. Patients in sinus rhythm without LAA thrombus demonstrated a characteristic pattern of a contractile LAA apex and a noncontractile base with color flow and pulsed Doppler evidence of LAA emptying that coincided with the P wave. Patients in sinus rhythm with LAA thrombus had a mean +/- SD LAAmax (8.0 +/- 1.5 cm2) larger than that in group 1 (5.0 +/- 1.9 cm2) (p less than 0.01) but not group 2 (6.7 +/- 3.1 cm2), LAAmin (6.5 +/- 1.0 cm2) larger than that in both group 1 (2.3 +/- 1.5 cm2) and group 2 (4.2 +/- 2.7 cm2) (p less than 0.01), and LAA ejection fraction (17 +/- 11%) and LAA velocity (0.24 +/- 0.10 m/sec) less than those in both group 1 (55 +/- 21% and 0.48 +/- 0.24 m/sec, respectively) and group 2 (45 +/- 27% and 0.46 +/- 0.24 m/sec, respectively) (p less than 0.01). Patients with atrial fibrillation or flutter with LAA spontaneous contrast and/or thrombus had LAAmax (10.4 +/- 6.6 cm2) greater than that in patients with atrial fibrillation or flutter without LAA contrast and/or thrombus (6.8 +/- 3.0 cm2) (p less than 0.05). The LAA appeared as a static pouch in seven of eight of the former compared with in two of 11 of the latter. When attempted, Doppler demonstrated a recognizable fibrillatory LAA outflow velocity pattern in none of three in the former versus four of seven in the latter group.

CONCLUSIONS

We conclude that the LAA has a characteristic pattern of emptying in sinus rhythm. LAA thrombus formation in sinus rhythm and atrial fibrillation is associated with both poor LAA contraction and LAA dilation.

Diagnosis of noninfective cardiac mass lesions by two-dimensional echocardiography. Comparison of the transthoracic and transesophageal approaches

This study was conducted in 46 patients with cardiac thrombi, 15 patients with atrial myxomas, and 32 patients with other cardiac or paracardiac tumors. Diagnoses were subsequently proven by surgery, autopsy, computed tomography, magnetic resonance imaging, or angiography in all patients. All patients underwent precordial and transesophageal two-dimensional echocardiography to assess the various mass detection rates. Atrial myxomas and predominantly left-sided cardiac tumors were identified by both echocardiographic techniques with comparable detection rates. Left ventricular apical thrombi were detected more frequently by precordial echocardiography. In contrast, transesophageal echocardiography was superior in visualizing left atrial appendage thrombi, small and flat thrombi in the left atrial cavity, thrombi and tumors in the superior vena cava, and masses attached to the right heart and the descending thoracic aorta. These data indicate that transesophageal echocardiography leads to a clinically relevant improvement of the diagnostic potential in patients in whom cardiac masses are suspected or have to be excluded in order to ensure the safety of clinical procedures.

Comparison of two-dimensional echocardiography and ultrafast cardiac computed tomography for evaluating intracardiac thrombi in cerebral ischemia

Two-dimensional echocardiography has a high specificity for the detection of intracardiac thrombi, but technically difficult studies are often encountered. Ultrafast cardiac computed tomography may be useful in such cases. Using transthoracic two-dimensional echocardiography and ultrafast cardiac computed tomography, we studied 36 patients with cerebral ischemia; one patient had the studies performed on two occasions, making a total of 37 sets of studies. Technical difficulties occurred in 12 echocardiographic (32%) and two ultrafast cardiac computed tomographic (5%) studies. The two techniques agreed in 29 sets of studies (78%). Among the eight discrepant sets of studies, two-dimensional echocardiography was positive for a left ventricular thrombus while ultrafast cardiac computed tomography was negative in three and equivocal in one and echocardiography was equivocal while ultrafast cardiac computed tomography was negative in two and positive in one. In the latter case, a left ventricular thrombus was confirmed at autopsy. In the other discrepant set of studies echocardiography was negative while ultrafast cardiac computed tomography revealed a left atrial and appendage thrombus. Because of its ease of performance and safety, two-dimensional echocardiography is the appropriate initial screening test for left ventricular thrombus. Ultrafast cardiac computed tomography can provide additional information in patients with technically difficult or equivocal two-dimensional echocardiographic studies or patients with cardiac disorders predisposing to atrial thrombi formation.

Cardiac evaluation of the patient with stroke

Coronary artery disease and ischemic cerebrovascular disease are leading causes of morbidity and mortality in the United States. Coronary artery disease often coexists with asymptomatic carotid artery atherosclerosis, transient ischemic attacks, or ischemic stroke. Numerous studies have shown that mortality from all forms of ischemic cerebrovascular disease is primarily due to coronary artery disease. Thus, there is increasing interest in identifying coronary artery disease in patients with cerebrovascular disease, including those without clinical manifestations of heart disease. We review the use of current noninvasive techniques to detect coronary artery disease and present practical approaches to screen for ischemic heart disease. Current diagnostic imaging methods for potential cardioembolic sources of cerebral infarction are also discussed.

111In-labeled platelet scintigraphy and two-dimensional echocardiography for detection of left atrial appendage thrombi. Studies in a new canine model

111In-labeled platelet scintigraphy and two-dimensional echocardiography were performed in 40 dogs to determine the ability of the two techniques to detect left atrial appendage thrombi. Thrombi were induced in 33 dogs that were classified into two groups, "acute" or "chronic," according to the time of labeled-platelet injection after thrombus induction. In the acute group (17 dogs), platelets were injected 24 hours after thrombus induction. In the chronic group (16 dogs), platelets were injected 4-8 days after thrombus induction. "Sham" thoracotomies were performed on seven additional control dogs who did not receive thrombin injections. Analog and blood pool-corrected 111In-labeled platelet scintigraphy images were obtained 4-72 hours later. Closed-chest two-dimensional echocardiography was performed before thoracotomy and repeated at the time of scintigraphy. The location and size of each thrombus were verified at autopsy. Two-dimensional echocardiography detected three of 17 acute (mean volume, 1.2 +/- 1.0 cc) and three of 10 chronic (mean volume, 0.4 +/- 0.3 cc; p less than 0.025) left atrial appendage thrombi. 111In-labeled platelet scintigraphy detected all 17 acute thrombi but only two of 10 chronic thrombi. The measured radioactivity levels of the excised thrombi were 1,949 +/- 1,665 cpm/clot/dose in group 1 and 228 +/- 213 cpm/clot/dose in group 2 (p less than 0.005). In this model, 111In-labeled platelet scintigraphy was able to detect acute left atrial appendage thrombi that could not be identified by two-dimensional echocardiography. Both techniques showed poor sensitivity for detection of chronic thrombi. The decline in sensitivity of 111In-labeled platelet scintigraphy for detection of older thrombi is probably due to diminished labeled-platelet incorporation.

Noninvasive assessment of mitral stenosis before and after percutaneous balloon mitral valvuloplasty

Thirty-seven patients with symptomatic mitral stenosis underwent balloon dilatation of the mitral valve. Significant increases (p less than 0.001) were noted in both catheterization- and Doppler-determined valve area (0.9 +/- 0.3 to 1.8 +/- 0.8 and 0.9 +/- 0.2 to 1.7 +/- 0.5 cm2). However, catheterization and Doppler areas before and after valvuloplasty correlated less well (r = 0.51, p less than 0.002 and r = 0.47, p less than 0.005, respectively) than the catheterization-Doppler area correlation in a previous study of 59 consecutive patients with varying degrees of mitral stenosis (r = 0.84, p less than 0.001). Mitral valve area increases were independent of valve thickness estimated using 2-dimensional echocardiography. Flail mitral leaflet movement was not observed and the degree of mitral regurgitation qualitatively assessed using pulsed Doppler mapping techniques increased by greater than 1 of 4 grades in only 1 patient. The lateral mitral valve orifice diameter increased more than the anteroposterior diameter, suggesting commissural splitting as the mechanism of successful valvuloplasty. Increases (all p less than 0.0001) were noted in mitral valve EF slope (7 +/- 5 to 18 +/- 10 mm/s), excursion (11 +/- 5 to 13 +/- 4 mm), S20S interval (0.07 +/- 0.02 to 0.08 +/- 0.02 s) and cardiac output (4.2 +/- 1.3 to 5.3 +/- 2.0 liters/min). There were significant decreases (all p less than 0.001) in left atrial diameter (5.4 +/- 1.0 to 5.1 +/- 1.0 cm), mean catheterization gradient (15 +/- 5 to 8 +/- 4 mm Hg) and mean Doppler gradient (10 +/- 4 to 6 +/- 3 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Left atrial vascularised thrombus diagnosed by transoesophageal cross sectional echocardiography

This report describes a patient with a Björk-Shiley mitral valve prosthesis in whom transoesophageal cross sectional echocardiography revealed a large vascularised mass within the left atrial appendage with smoke-like opacification of blood flow in the left atrium. Transoesophageal cross sectional echocardiography gave a detailed image of the lesion which was unobtainable with precordial cross sectional echocardiography.

Identification of intracardiac thrombus: comparison of computed tomography and cross-sectional echocardiography

Thirty-eight patients with conditions predisposing to intracardiac thrombus have been studied by computed tomography and cross-sectional echocardiography. Computed tomography identified 22 cases of intracardiac thrombus (13 left ventricular, eight left atrial and one right atrial). Cross-sectional echocardiography identified five of these left ventricular thrombi and the right atrial thrombus, but none of the left atrial thrombi. In addition, measurements of thrombus density on computed tomography identified a significant difference (p less than 0.02) between the density of a new compared with an organized thrombus.

Visualisation of left atrial thrombi by coronary arteriography

Abnormal vascularity in the region of the left atrial appendage was demonstrated by coronary arteriography in 5 patients with mitral stenosis. Subsequently, three of these patients proceeded to operation, and left atrial thrombi were confirmed in all three cases. Neovascularity must be differentiated from congenital fistulae, tumours, and coronary artery disease. Thrombus in the left atrial appendage is difficult to diagnose even with the use of cross-sectional echocardiography and may occasionally be demonstrated by coronary arteriography.

Echocardiographic evaluation of young adults with nonhemorrhagic cerebral infarction

We reviewed echocardiographic findings in patients aged 15 to 45 years with acute nonhemorrhagic cerebral infarction (NHCI). Among 132 patients with NHCI, 96 (72.7%) had M-mode and two-dimensional echocardiography, including contrast echocardiography with intravenous saline injection when clinically indicated. Echocardiograms were abnormal in 33 patients. Of these, 7 had other conditions that could cause NHCI. Echocardiography corroborated the clinical diagnosis of a cardiogenic source for cerebral infarction in 17 others. The other 9 had no other clues for cardiovascular disease. Potential etiologies of NHCI diagnosed by echocardiography in these 9 cases included: paradoxical embolism, 5 patients; right atrial myxoma, 1; rheumatic mitral valve vegetation, 1; myxomatous mitral valve (marantic endocarditis at postmortem), 1; and left atrial enlargement associated with decreased left ventricular function, 1. Routine echocardiography frequently conveys useful information in patients under age 45 with NHCI. In young patients with cerebral embolism of unknown etiology if routine M-mode and two dimensional echocardiographic studies are normal, contrast echocardiographic studies should be performed to rule out intracardiac shunts and the possibility of paradoxical cerebral embolism.

Transesophageal two-dimensional echocardiography for the detection of left atrial appendage thrombus

Thrombi located in the left atrial appendage are frequently not detected with conventional two-dimensional echocardiography. The transesophageal echocardiographic approach readily visualizes left atrial morphology and may be used as an alternative. In 6 of 21 patients with mitral valve stenosis, a left atrial appendage thrombus was diagnosed by transesophageal two-dimensional echocardiography when transthoracic echocardiography had failed. The transesophageal echocardiographic findings were confirmed at surgery for mitral valve replacement in all cases.