Spontaneous echo contrast in the descending aorta detected by transesophageal echocardiography

Relationship between spontaneous echo contrast in the thoracic aorta and plasma von Willebrand factor

PURPOSE

To clarify the relationships between spontaneous echo contrast (SEC) detected by transesophageal echocardiography (TEE) and coagulopathy, ultrasonographic findings that may correlate to biochemical coagulation markers were examined.

METHODS

TEE was performed on 49 consecutive patients (mean age 64 ± 14 years; 28 men, 21 women). Blood samples were taken at the same time as TEE was carried out. Aortic SEC (Ao-SEC) and left atrial SEC (LA-SEC) were classified into three grades: absent, mild and marked. Levels of von Willebrand factor (vWF), thrombin antithrombin III complex (TAT), prothrombin fragments 1+2 (F1+2) and fibrinopeptide A (FPA) were measured.

RESULTS

Mean plasma vWF levels by Ao-SEC grade were 144 ± 39% for absent, 177 ± 55% for mild and 210 ± 73% for marked, with significantly higher levels in the Ao-SEC marked group than in the Ao-SEC absent group (P < 0.05). Mean plasma vWF levels by LA-SEC were 185 ± 73% for absent, 180 ± 49% for mild and 201 ± 62% for marked, with no significant differences apparent between groups. Moreover, no relationships were identified between Ao-SEC grade and plasma levels of coagulation indicators TAT, F1+2 and FPA.

CONCLUSION

Plasma vWF levels correlated to grade of aortic SEC. Characteristics of the coagulation system differ between Ao-SEC and LA-SEC. Ao-SEC offers a clinical indicator of platelet thrombus formation.

The Impact of Spontaneous Echocardiographic Contrast in Patients With Left Atrial Enlargement Undergoing Cardiac Valvular Surgery

OBJECTIVE

The aim of this study was to evaluate the impact of either left atrial or aortic spontaneous echocardiographic contrast (SEC), as identified on intraoperative transesophageal echocardiography, on short-term morbidity and mortality in patients with left atrial enlargement undergoing cardiac valvular surgery.

DESIGN

Retrospective and observational.

SETTING

Single-center, university teaching hospital.

PARTICIPANTS

The authors identified 197 patients (105 males and 92 females; mean age, 68 +/- 14 years) with left atrial enlargement who underwent surgical intervention for valvular heart disease from January 1, 2004 to January 1, 2005.

MAIN RESULTS

Of the total population, 40 patients (20.3%) showed left atrial SEC, and 10 patients (5.1%) showed aortic SEC. On multivariate analysis, increasing left atrial size and the absence of mitral regurgitation were independent predictors for the presence of left atrial SEC. On multivariate analysis, the presence of atrial fibrillation and a dilated descending aorta were predictive of aortic SEC. Although the identification of left atrial SEC was an echocardiographic marker of an increased risk for thromboembolic events postoperatively, this finding did not hold true for the presence of aortic SEC.

CONCLUSIONS

Intraoperative identification of left atrial dilatation or aortic dilatation is predictive of SEC in the left atrium or descending aorta, respectively. The identification of left atrial SEC is an echocardiographic marker of an increased risk for thromboembolic events in this high-risk population.

Improved Detection of Spontaneous Echo Contrast in the Aorta with Tissue Doppler Imaging

AIMS

Spontaneous echo contrast (SEC) within the cardiac chambers has been associated with increased risk of thromboembolism. We investigated the presence and severity of SEC in the aorta with tissue Doppler imaging (TDI) and compared these to the aortic flow velocity and to the clinical profile of the patients.

METHODS AND RESULTS

Seventy patients (35 males, 35 females, mean age 64, 22-86 years) underwent TEE for standard indications. Spontaneous echo contrast was studied with conventional and TDI imaging. Aortic flow velocity was measured in the center and lateral part of the descending aorta. SEC of any grade was detected in 24 patients with conventional imaging and in 53 using TDI (P < 0.0001). The presence of swirling was associated with aortic atherosclerosis, older age, history of hypertension and coronary artery disease, atrial fibrillation, and previous embolic events. There was correlation between intraaortic swirling, larger descending aortic diameter (23.6 vs 17 mm, P < 0.00001) and lower peak aortic flow velocity (55 vs 68 cm/s, P = 0.038).

CONCLUSION

Spontaneous echo contrast in the aorta is common in high-risk patients and is associated with increased clinical profile, larger aortic diameter, and lower peak aortic flow velocity. Tissue Doppler imaging is more sensitive in the detection of SEC than conventional imaging.

Spontaneous echo contrast in the descending aorta in patients without aortic dissection: associated clinical and echocardiographic characteristics

The objective of the study was to evaluate the frequency, clinical and echocardiographic correlates of spontaneous echo contrast in the descending aorta in the absence of dissection. Prevalence of spontaneous echo contrast in the descending aorta in the absence of dissection, and its clinical and echocardiographic correlates were investigated in 1199 consecutive patients who underwent transesophageal echocardiography. Spontaneous echo contrast in the descending aorta was detected in 54 (4.5%) patients. Patients with spontaneous echo contrast in the descending aorta had an older age (60.6+/-8 vs. 40.6+/-14.2 years, P=0.0001), an increased prevalence of male gender (66.7 vs. 43.9%, P=0.001), an increased diameter of ascending aorta (4.2+/-1.0 vs. 3.3+/-1.1 cm, P=0.0001), an increased diameter of descending aorta (3.1+/-0.9 vs. 2.1+/-0.4 cm, P=0.0001), a higher prevalence of aortic wall calcification (9.3 vs. 0.5%, P=0.00001), complex plaque in the descending aorta (13 vs. 0.7%, P=0.0001), left ventricular dysfunction (7.4 vs. 2.1%, P<0.05), a lower incidence of severe aortic regurgitation (0 vs. 3.5%, P<0.05), a lower peak flow velocity in the descending aorta (28+/-9 vs. 51+/-21 cm/s, P<0.00001), and a lower maximal shear rate in the descending aorta (51+/-29 vs. 105+/-47 s(-1), P<0.00001) compared with patients without spontaneous echo contrast in the descending aorta. However, prevalence of atrial fibrillation, mitral valve disease, intracardiac spontaneous echo contrast and/or thrombus and embolic event were not different between patients with and without spontaneous echo contrast in the descending aorta (P>0.05). Shear rate, diameter of the descending aorta, aortic wall calcification, complex plaque in the descending aorta, absence of severe aortic regurgitation and male gender were independent variables of spontaneous echo contrast in the descending aorta. Spontaneous echo contrast in the descending aorta is a local and flow-dependent phenomenon related to aortic dilation, atherosclerosis, and decreased shear rates in the descending aorta. However, in this study, spontaneous echo contrast in the descending aorta was not found to be associated with embolic events.

Prognosis of spontaneous echocardiographic contrast in the thoracic aorta

The aim of this study was to assess the predictive value of spontaneous echocardiographic contrast (SEC) detected in the thoracic aorta by transesophageal echocardiography (TEE) on intermediate-term cardiovascular morbidity and mortality. We studied 299 consecutive patients (aged 61 +/- 13 years) without aortic aneurysm or dissection, who underwent TEE in 1995 to 1996. Cardiovascular deaths and nonfatal events were recorded over a period of < or = 60 months. Left ventricular function was classified as preserved versus depressed according to ejection fraction values (>40% vs < or = 40%) on 2-dimensional echocardiography. SEC was identified in 35 patients (11.7%). During follow-up, 66 patients died (36 deaths were due to cardiovascular causes; 10 and 26 cardiovascular deaths occurred in patients with and without SEC, respectively [p <0.001]). Survival time was significantly reduced in patients with versus without SEC (28 +/- 18 vs 39 +/- 19 months, p = 0.0012). Multivariate analysis revealed that the presence of SEC doubled the odds for cardiovascular death and for the combined end point of cardiovascular death and events. There was a significant difference in survival distributions between patients with and without SEC between both genders (p <0.001). In patients with normal or mildly reduced left ventricular function, SEC was predictive of an adverse outcome, whereas this was not the case in patients with more severely depressed cardiac function. It is concluded that the presence of SEC in the thoracic aorta is associated with a high risk of cardiovascular events and/or death over intermediate-term follow-up.

Spontaneous echo contrast in the descending aorta in patients without aortic dissection: associated clinical and echocardiographic characteristics

OBJECTIVE

To evaluate the frequency, clinical and echocardiographic correlates of spontaneous echo contrast in the descending aorta in the absence of dissection.

METHODS

Prevalence of spontaneous echo contrast in the descending aorta in the absence of dissection, and its clinical and echocardiographic correlates were investigated in 1,199 consecutive patients who underwent transesophageal echocardiography.

RESULTS

Spontaneous echo contrast in the descending aorta was detected in 54 (4.5%) patients. Patients with spontaneous echo contrast in the descending aorta had an older age (60.6+/-8 vs. 40.6+/-14.2 years, p=0.0001), an increased prevalence of male gender (66.7 vs. 43.9%, p=0.001), an increased diameter of ascending aorta (4.2+/-1.0 vs. 3.3+/-1.1 cm, p=0.0001), an increased diameter of descending aorta (3.1+/-0.9 vs. 2.1+/-0.4 cm, p=0.0001), a higher prevalence of aortic wall calcification (9.3 vs. 0.5%, p=0.00001), complex plaque in the descending aorta (13 vs. 0.7%, p=0.0001), left ventricular dysfunction (7.4 vs. 2.1%, p<0.05), a lower incidence of severe aortic regurgitation (0 vs. 3.5%, p<0.05), a lower peak flow velocity in the descending aorta (28+/-9 vs. 51+/-21 cm/s, p<0.00001), and a lower maximal shear rate in the descending aorta (51+/-29 vs. 105+/-47 s(-1), p<0.00001) compared with patients without spontaneous echo contrast in the descending aorta. However, prevalence of atrial fibrillation, mitral valve disease, intracardiac spontaneous echo contrast and/or thrombus and embolic event were not different between patients with and without spontaneous echo contrast in the descending aorta (p>0.05). Shear rate, diameter of the descending aorta, aortic wall calcification, complex plaque in the descending aorta, absence of severe aortic regurgitation and male gender were independent variables of spontaneous echo contrast in the descending aorta.

CONCLUSIONS

Spontaneous echo contrast in the descending aorta is a local and flow dependent phenomenon relates to aortic dilation, atherosclerosis, and decreased shear rates in the descending aorta. However, in this study, spontaneous echo contrast in the descending aorta was not found to be associated with embolic events.

Aortic spontaneous echocardiographic contrast and hemostatic markers in patients with nonrheumatic atrial fibrillation

OBJECTIVES

To determine the relationship between spontaneous echocardiographic contrast (SEC) in the descending thoracic aorta and plasma levels of hemostatic markers in patients with nonrheumatic atrial fibrillation (AF).

DESIGN AND SETTINGS

A cross-sectional study at a university hospital.

PATIENTS AND MEASUREMENTS

In 91 consecutive patients (mean +/- SE age, 70 +/- 1 years; 68 men) with nonrheumatic AF who underwent transesophageal echocardiography, plasma levels of markers for platelet activity (platelet factor 4 [PF4] and beta-thromboglobulin [beta-TG]), thrombotic status (thrombin-antithrombin III complex [TAT]), and fibrinolytic status (D-dimer and plasmin-alpha(2)-plasmin inhibitor complex [PIC]) were determined.

RESULTS

Forty-three patients who had aortic SEC (AoSEC) were older (72 years vs 68 years; p < 0.05) and had a higher prevalence of chronic AF (88% vs 52%; p < 0.05) than 48 patients without AoSEC. TAT, PIC, and D-dimer levels were significantly higher in patients with AoSEC than in those without AoSEC, whereas PF4 and beta-TG levels were not different between the two groups. Although the prevalence of cerebral embolism did not differ between the two groups (23% vs 29%), the prevalence of peripheral embolism was higher in patients with AoSEC than in those without AoSEC (10% vs 0%; p < 0.05). Multivariate analysis revealed mitral regurgitation (odds ratio, 7.53; p < 0.02), SEC in the left atrium (odds ratio, 2.14; p < 0.02), and aortic atherosclerosis (odds ratio, 1.87; p < 0.04) emerged as independent predictors of AoSEC.

CONCLUSIONS

Patients with nonrheumatic AF who have AoSEC appear to have enhanced coagulation activity but not platelet activity. Intensive anticoagulation treatment might be required for these patients.

Spontaneous echo contrast in descending aorta correlates with low blood-flow velocity in carotid arteries and hemostatic abnormalities

Spontaneous echo contrast in the descending aorta (DA-SEC) was examined as a possible risk factor for cerebral thromboembolism. In 19 patients (10 males, 9 females) in the chronic stage of cerebral infarction, abnormal findings by transesophageal echocardiography, flow dynamics of the common carotid artery (CCA), and hemostatic factors including blood coagulation and fibrinolysis were investigated. In nine patients, DA-SEC was detected, and SEC in left atrium (LA-SEC) was detected in nine patients. The DA-SEC positive group showed decreased blood-flow velocity (BFV) in bilateral CCA, high levels of thrombin-antithrombin III complex (TAT) and prothrombin fragment 1.2 (F1+2), a decrease in platelet count and a slight increase in D-dimer, which means an activated state of thrombin generation and resulting fibrinolysis, compared to the DA-SEC negative group. On the other hand, the LA-SEC positive group showed normal BFV in CCA and only a slight increase in D-dimer. We conclude that the condition producing DA-SEC is a stronger risk factor for cerebral infarction than that producing LA-SEC.

Embolic risk based on aortic atherosclerotic morphologic features and aortic spontaneous echocardiographic contrast

BACKGROUND

Different aortic atherosclerotic plaque morphologic features may have varying embolic potentials. Spontaneous echocardiographic contrast (SEC) in the aorta, as in the left atrium, has been associated with an increased risk of embolic events and often occurs with complex aortic atherosclerosis. Thus an evaluation of their isolated and combined association with embolic events was undertaken.

METHODS

We retrospectively studied all patients who underwent biplane or multiplane transesophageal echocardiography meeting the following inclusion and exclusion criteria: age >/=55 years and no other cardiac pathologic condition known to be associated with embolic events other than aortic atherosclerosis or aortic SEC. The 105 patients meeting the criteria were divided into those with aortic atherosclerosis and/or aortic SEC (the study group) and those without these aortic pathologic conditions (the comparison group). Complex aortic atherosclerosis was defined as mobile, ulcerated, or protuberant (> 4 mm). SEC was defined as a pulsatile, swirling echo pattern within the aortic lumen. Embolic events included strokes, transient ischemic attacks, or peripheral emboli.

RESULTS

The 61 study patients and 44 comparison patients did not significantly differ with respect to the reason for referral, age, or sex. Embolic events occurred in 35 patients. Those with ulcerated or mobile plaques had a greater prevalence of embolic events (odds ratio 4.50; 95% confidence interval, 1.30-15.5; P <.05). The highest embolic event rate was seen in patients with any complex atherosclerosis and concomitant SEC (odds ratio 9.00; 95% confidence interval, 2.06-39.3; P <.01). Patients with SEC alone or protuberant plaques alone did not have a higher event rate (odds ratio 1.71 and 0.60; 95% confidence interval, 0.57-5.17 and 0.15-2. 47, respectively).

CONCLUSIONS

Embolic events were associated with the presence of ulcerated or mobile aortic plaques. In addition, the combination of aortic SEC and any complex atherosclerosis had the highest embolic association.

Role of transesophageal echocardiography in the evaluation of patients with clinical pacemaker syndrome

OBJECTIVES

The goal of this study was to investigate the possible role of transesophageal echocardiography in the evaluation of patients with clinical pacemaker syndrome.

BACKGROUND

Several reports on transthoracic echocardiographic features of ventricular pacing were described; however, no previous study of transesophageal echocardiography has been undertaken in patients at the severe end of pacemaker syndrome who need reprogramming of dual-chamber pacing for symptom relief.

METHODS

Twelve patients with ventricular-inhibited pacemakers (VVI) with clinical symptomatic pacemaker syndrome (group I) and 10 patients with VVI without pacemaker syndrome (group II) were prospectively studied. The two groups were pacemaker dependent and had persistent ventriculoatrial conduction. Transesophageal echocardiographic parameters were assessed in group II and within 6 hours before reprogramming to the DDD mode in group I. Follow-up transesophageal echocardiographic study was performed 28+/-5 days after reprogramming in group I.

RESULTS

All patients in group I had subjective improvements of symptoms after DDD reprogramming. The atrial reverse flow velocities of pulmonary veins in group I before reprogramming were significantly higher in group II (39.3+/-11.4 versus 15.7+/-13.5 cm/sec, p < 0.0001). Spontaneous echo contrast in the descending aorta was detected in all patients from group I before reprogramming. The prevalence of significant mitral regurgitation (> or = moderate) was significantly higher in group I before reprogramming than in group II (67% versus 8%, p = 0.01). Significant mitral regurgitation and spontaneous echo contrast in the descending aorta in group I disappeared after reprogramming to the DDD mode.

CONCLUSIONS

Transesophageal echocardiography provides physiologic, pacemaker-related hemodynamic changes in paced patients. Significantly higher atrial reverse flow velocities of pulmonary veins, increased frequency of spontaneous echo contrast in the descending aorta, and significant mitral regurgitation are peculiar echocardiographic findings in patients with VVI with clinical pacemaker syndrome.

Hemodynamic Predictors of Atherosclerosis in the Thoracic Aorta

We sought to identify atherosclerotic plaques and measured flow parameters in the descending aorta (DA) of 83 consecutive patients (40 years and older) studied with transesophageal echocardiography. Patients with atherosclerotic plaques in the DA were older (68 +/- 10 vs 58 +/- 12 years [P = 0.0001]), had a higher proportion of spontaneous echo contrast in the DA (15/46 [33%] vs 3 of 37 [8%] P = 0.02), had larger aortic diameters (2.52 +/- 0.35 vs 2.37 +/- 0.36 cm [P = 0.06]), had a lower maximal velocity in the DA (54.2 +/- 21.5 vs 73.8 +/- 33.0 cm/sec [P = 0.02]), and had a lower calculated maximal shear rate (SR) (88.0 +/- 37.6 vs 129.0 +/- 67.0 sec(-1) [P = 0.002]). There was no significant difference between groups with respect to sex, hypertension, diabetes, total cholesterol, and smoking. In multivariate analysis only age (P = 0.002) and maximal SR (P = 0.03) were identified as independent predictors of atherosclerosis in the DA. We conclude that low SR is associated with aortic atherosclerosis.

Prognostic significance of spontaneous echo contrast in the thoracic aorta: relation with accelerated clinical progression of coronary artery disease

OBJECTIVES

The purposes of this study were to identify the incidence of aortic smoke in an unselected cohort of patients and to determine the utility of this measurement as a clinical marker for future coronary events and long-term cardiac prognosis.

BACKGROUND

Although spontaneous echo contrast detected within the cardiac chambers has been associated with an increased risk of thromboembolism, less is known about "smoke" within the thoracic aorta and its relation to progression of coronary artery disease.

METHODS

We prospectively assessed 118 unselected, consecutive male patients (mean age 67 years, range 29 to 86) who underwent transesophageal echocardiography (TEE). The presence of aortic smoke was identified by swirling echodense shadows distinct from high gain artifact. A positive result required confirmation by two of three independent observers.

RESULTS

Aortic smoke without dissection was found in 25 of the patients (21%). Indications for TEE, coronary risk factors, the incidence of reduced left ventricular ejection fraction and mitral insufficiency and known coronary artery disease severity collectively did not differ significantly at baseline between the groups with and without smoke. Follow-up averaged 20.4 months (range 18 to 24) and was 100% complete for mortality and 98% complete for morbidity. The presence of aortic smoke was an independent predictor of myocardial infarction (16.0% vs. 2.2%, p < 0.005) and cardiac death (20.0% vs. 1.1%, p < 0.0001). These statistics remained significant after covarying for age, ejection fraction < 50%, hypertension, diabetes, aortic dimension, the presence of an atheromatous plaque and smoke in the left atrium.

CONCLUSIONS

Spontaneous echo contrast detected within the thoracic aorta by transesophageal echocardiography is a common and important clinical marker that is strongly associated with an increased risk for future myocardial infarction and cardiac mortality. Future studies will attempt to define the pathophysiology of this relation and assess whether aggressive revascularization strategies and antithrombotic therapy may aid in the reduction of this risk.

Spontaneous echocardiographic contrast in the true lumen of a dissected aortic aneurysm

Spontaneous echocardiographic contrast may be seen in the false and true lumens of dissecting aortic aneurysms. Using transesophageal echocardiography, we identified the false lumen as the source of spontaneous echocardiographic contrast in the true lumen of a patient with an aortic dissection.

Differences in the erythrocyte aggregation level between veins and arteries of normolipidemic and hyperlipidemic individuals

The objectives of this study were to detect differences in the Doppler power backscattered by blood in vivo, and to identify factors affecting the backscattered power. The main hypothesis was that variations in the erythrocyte aggregation level between veins and arteries of normolipidemic and hyperlipidemic individuals can be detected with power Doppler ultrasound. Doppler measurements were performed at 5 MHz, with an Acuson 128 XP/10 system, over the carotid artery and jugular vein, external iliac artery and vein, common femoral artery and vein and popliteal artery and vein. Doppler signals were recorded at the center of each vessel to optimize the detection of erythrocyte aggregation, and processed off-line to obtain the backscattered power. The power of each recording was compensated for Doppler gain differences, tissue attenuation with depth and transmitted power variations occurring with pulse-repetition interval modifications. Results showed statistically stronger backscattered power in veins compared to arteries for the iliac, femoral and popliteal sites. In comparison with healthy subjects, stronger powers were observed in hyperlipidemic patients for the femoral and popliteal sites. Power differences were also found between peripheral measurements. On the other hand, no difference was observed between the power measured in the carotid artery and jugular vein for both groups of individuals. Multiple linear regression analyses were performed to identify factors affecting the backscattered power. Results showed a correlation (r) of 71.2% between the Doppler power in the femoral vein and the linear combination of two parameters: an erythrocyte aggregation index S10 measured with a laser scattering method, and the diameter of the vessel measured on B-mode images. Statistically significant linear correlation levels were also found between S10 and the Doppler power in various vessels. In conclusion, this study showed that power Doppler differences exist in vivo in large vessels between veins and arteries of normolipidemic and hyperlipidemic individuals. The Doppler power variations were also shown to be related to erythrocyte aggregation.

Hemodynamic correlates of spontaneous echo contrast in the descending aorta

To identify the hemodynamic association of spontaneous echo contrast (SEC) in the descending aorta (DA), we measured aortic flow parameters in 102 consecutive patients studied with transesophageal echocardiography. SEC in the DA was identified in 19 of 102 patients (19%). Patients with SEC in the DA were older (67 +/- 9 vs 57 +/- 17 years; p = 0.001), had a higher proportion of chronic atrial arrhythmia (13 of 19 vs 11 of 83; p = 0.000001), and had a higher frequency of decreased left ventricular performance (10 of 19 vs 19 of 83; p = 0.01). Patients with SEC in the DA had larger aortic diameters (2.9 +/- 0.5 vs 2.3 +/- 0.4 cm; p = 0.0001), lower maximal velocity in the DA (42.6 +/- 12.8 vs 75.6 +/- 34.4 cm/s; p = 0.0001), and lower maximal shear rate (61.6 +/- 20.3 vs 139.9 +/- 78.8 s-1; p = 0.0001). There was no difference in volumetric flow in the DA between groups. In multivariate analysis, only arrhythmia (p = 0.008) and maximal shear rate (p = 0.002) were identified as significant independent predictors of SEC in the DA. We conclude that SEC in the DA is related to chronic atrial arrhythmia and shear rate but not to volumetric flow.

Spontaneous echocardiographic contrast in the thoracic aorta: factors associated with its occurrence and its association with embolic events

Spontaneous echocardiographic contrast is associated with embolic events when it occurs in the left atrium. Because little is known about spontaneous echocardiographic contrast in the aorta, we investigated this association retrospectively in 343 patients without aortic dissection or aneurysm who had undergone transesophageal echocardiography. Two independent readers concurred on the presence of spontaneous echocardiographic contrast in the aorta in 93% of the study patients, with the remainder agreed on by consensus. Spontaneous echocardiographic contrast was found in 65 patients (19%) and was associated with older age (p < 0.0001), male sex (p < 0.0001), slightly larger aortas (p < 0.0001), and complex aortic atherosclerosis (p = 0.0001). Thirty-four (28.6%) of 119 patients with clinical embolic events had spontaneous echocardiographic contrast in the aorta in contrast to 31 (13.8%) of 224 patients referred for other reasons (p = 0.0001). This finding remained significant when spontaneous echocardiographic contrast in the aorta was the only abnormality allowed (n = 207, p = 0.0065) or when other echocardiographic variables known to be related to embolic events were included in a multivariate analysis. Thus, spontaneous echocardiographic contrast in the aorta can often be detected by transesophageal echocardiography and is associated with a higher prevalence of embolic events.