Right atrial spontaneous echo contrast and thrombi in atrial fibrillation: a transesophageal echocardiography study

BACKGROUND

Previous studies have reported the clinical and echocardiographic findings of patients with left atrial spontaneous echo contrast (SEC) and thrombi. We sought to study these characteristics in patients with right atrial SEC and thrombi.

METHODS

We reviewed 580 consecutive patients from the ACUTE (Assessment of Cardioversion Using Transesophageal Echocardiography) Registry and found 79 patients (14%, aged 67 +/-13 years, 67 male) with transesophageal echocardiography (TEE) findings of right atrial SEC or thrombi (group 1). This group was compared with a control group of 75 consecutive patients (group 2) (aged 68 +/- 13 years, P = not significant; 49 male, P <.005) from the registry with no TEE findings of SEC or thrombi in the left or right atrium.

RESULTS

Atrial fibrillation was present in 60 of 79 group 1 patients (76%). Five right atrial (6%) and 11 left atrial (14%) thrombi were identified. Both left ventricular ejection fraction (39% +/- 16% versus 47% +/- 14%; P =.0005) and presence of right ventricular dysfunction (n = 44 versus 18; P =.0001) differed significantly between groups 1 and 2, respectively. Right atrial area (24 +/- 6 cm(2) versus 22 +/- 6 cm(2); P = .02) was larger in patients in group 1. Left atrial SEC was present in 68 of 79 group 1 patients (86%). Patients with right atrial thrombi and right atrial SEC had a longer duration of arrhythmia (524 +/-812 days versus 147 +/-368 days, P <.05) than patients with right atrial SEC only.

CONCLUSIONS

Right atrial SEC has a prevalence of 14% in patients with atrial arrhythmia who undergo TEE-guided cardioversion. Right atrial thrombi are a rare finding and were seen in fewer than 1% (5/580) of patients with atrial arrhythmia. Right atrial thrombi among patients on anticoagulation therapy were not associated with clinically significant pulmonary embolism.

Left ventricular diastolic dysfunction in lone atrial fibrillation determined by Doppler tissue imaging of mitral annular motion

In this study, we sought evidence for an underlying atrial or ventricular myopathy in patients with paroxysmal lone atrial fibrillation using standard echocardiographic parameters in addition to Doppler tissue imaging of mitral annular motion. No impairment in atrial contractile function was found, but there was evidence for impaired diastolic function in these patients.

Efficacy of anticoagulation in resolving left atrial and left atrial appendage thrombi: A transesophageal echocardiographic study

BACKGROUND

Transesophageal echocardiography (TEE) is the gold standard for evaluation of the left atrium and the left atrial appendage (LAA) for the presence of thrombi. Anticoagulation is conventionally used for patients with atrial fibrillation to prevent embolization of atrial thrombi. The mechanism of benefit and effectiveness of thrombi resolution with anticoagulation is not well defined.

METHODS AND RESULTS

We used a TEE database of 9058 consecutive studies performed between January 1996 and November 1998 to identify all patients with thrombi reported in the left atrium and/or LAA. One hundred seventy-four patients with thrombi in the left atrial cavity (LAC) and LAA were identified (1.9% of transesophageal studies performed). The incidence of LAA thrombi was 6.6 times higher than LAC thrombi (151 vs 23, respectively). Almost all LAC thrombi were visualized on transthoracic echocardiography (90.5%). Mitral valve pathology was associated with LAC location of thrombi (P <.0001), whereas atrial fibrillation or flutter was present in most patients with LAA location of thrombi. Anticoagulation of 47 +/- 18 days was associated with thrombus resolution in 80.1% of the patients on follow-up TEE. Further anticoagulation resulted in limited additional benefit.

CONCLUSIONS

LAC thrombi are rare and are usually associated with mitral valve pathology. Transthoracic echocardiography is effective in identifying these thrombi. LAA thrombi occur predominantly in patients with atrial fibrillation or flutter. Short-term anticoagulation achieves a high rate of resolution of LAA and LAC thrombi but does not obviate the need for follow-up TEE.

Reduced survival in women after valve surgery for aortic regurgitation: effect of aortic enlargement and late aortic rupture

OBJECTIVE

We sought to investigate the relationship of female sex, aortic pathology, and left ventricular function to outcome after an operation for aortic regurgitation.

METHODS

One hundred nine women underwent aortic valve replacement (n = 92) or repair (n = 17) for pure aortic regurgitation between 1985 and 1996. Mean follow-up was 5.7 +/- 2.6 years. New York Heart Association functional class III-IV symptoms were present in 70 patients, whereas left ventricular function was normal in 60 patients. Ascending aortic diameter in 97% exceeded the 90th percentile for a size-matched healthy population. A concomitant aortic operation was performed by means of root replacement in 31 patients and by means of interposition graft in 28 patients. Of 50 patients undergoing isolated valve procedures, 19 had aortas of 4.0 cm or larger.

RESULTS

At 5 and 10 years, survival was 78% and 44%, respectively. Fatal aortic rupture occurred in 13 patients, and 2 others underwent emergency operations for impending aortic rupture, for a total of 15 late aortic events. Freedom from aortic events was 87% and 76% at 5 and 10 years, respectively. Risk factors for aortic events were older age (P =.07) and increasing ascending aortic diameter indexed to body surface area (P =.03) in women who had not undergone replacement of the ascending aorta. Rupture location was at the ascending aorta in 71% without ascending replacement and the descending aorta in 62% with ascending grafts.

CONCLUSION

In women, late survival after an operation for aortic regurgitation is importantly decreased by coexisting aortic pathology with subsequent aortic rupture. Aortic replacement at the time of a valve operation should be considered on the basis of indexed aortic size.

Transesophageal echocardiography guided enoxaparin antithrombotic strategy for cardioversion of atrial fibrillation: the ACUTE II pilot study

BACKGROUND

Patients with atrial fibrillation >2 days' duration for whom immediate cardioversion is desired or required are commonly hospitalized for 4 or more days of antithrombotic therapy with intravenous unfractionated heparin and commencement of oral warfarin. For these early cardioversion patients, self-administered low-molecular-weight heparin (enoxaparin sodium) as "bridge" therapy to warfarin may obviate the need for hospitalization and activated partial thromboplastin time monitoring and thus potentially lower costs and enhance utility.

OBJECTIVE

To compare feasibility and safety of a transesophageal echocardiography (TEE)-guided enoxaparin strategy with those of a TEE-guided unfractionated heparin strategy in patients with atrial fibrillation of >2 days' duration undergoing early electrical or chemical cardioversion.

DESIGN AND SETTING

This is a randomized, multicenter clinical trial at 11 hospitals in the United States.

PATIENTS AND INTERVENTION

Two hundred patients with atrial fibrillation >2 days' duration requiring early chemical or electric cardioversion will be enrolled. TEE-guided intravenous unfractionated heparin bridge therapy will be compared with TEE-guided subcutaneous enoxaparin bridge therapy.

OUTCOME MEASURES

Feasibility outcomes are time to hospital discharge, patient quality of life/utility, treatment costs, and sinus rhythm. Safety outcomes are ischemic stroke, transient ischemic attack, systemic embolization, major and minor bleeding, clinical hemodynamic instability, and cardiac and cardioversion-related death for a 5-week period from enrollment.

CLINICAL IMPLICATIONS

The results of this pilot study will have important clinical and economic implications for the antithrombotic management of patients with atrial fibrillation undergoing TEE-guided cardioversion.

Transesophageal echocardiography-guided cardioversion of atrial fibrillation

Transesophageal echocardiography-guided anticoagulation management of patients with atrial fibrillation undergoing cardioversion has evolved over the past decade as a viable alternative to conventional anticoagulation management. Its use grew out of a need for a more predictable, dependable, and convenient approach to this difficult management dilemma, which has become increasingly prevalent in practice as an increasing number of patients present to clinics and hospitals with atrial fibrillation. In addition to its use in risk stratification of patients scheduled to undergo cardioversion, this management strategy allows for early cardioversion, which enables a minimal delay in proceeding from the diagnosis to the institution of therapy (electrical cardioversion). This review explores the evolution of the transesophageal echocardiography-guided strategy, the advantages and disadvantages of its use, and possible modifications to the strategy that would allow for a more convenient, practical, and more widely acceptable approach in the near future.

National use of the transesophageal echocardiographic-guided approach to cardioversion for patients in atrial fibrillation

Transesophageal echocardiographic (TEE)-guided cardioversion of patients in atrial fibrillation (AF) of >2 days' duration is used as an alternative to conventional therapy. The purpose of this study was to investigate practice patterns employed for stroke prophylaxis in patients with AF who underwent cardioversion, and to determine the relative use of conventional and TEE-guided management strategies. We forwarded regionally stratified survey questionnaires to 947 clinical practices within the United States. The 10-question questionnaire queried demographic and clinical practice volumes and practices for managing patients with AF who underwent cardioversion. In addition, we used historical data to determine longitudinal use patterns of the TEE-guided approach for a large institution over 7 years. The 197 completed and returned surveys yielded a return rate of 20.8%. The TEE-guided approach was employed in approximately 12% of total cardioversions, but 75% of practices indicated that they employed transesophageal echocardiography only occasionally. The TEE-guided approach was associated with community size (r = 0.19; p<0.008), type of practice (r = 0.26; p = 0.001), total use of transesophageal echocardiography (r = 0.48; p<0.001), and volume of cardioversions (r = 0.28; p<0.001). Importantly, there was little consensus on the most appropriate clinical indications for TEE-guided cardioversions, and the proportions of TEE-guided cardioversion to total number of electrical cardioversions remained stable over 7 years. Practice volume and physician training may be the most important variables in the adoption of the TEE approach.

Atrial fibrillation early postoperatively following minimally invasive cardiac valvular surgery

We report a cohort of our first 100 minimally invasive cardiac valvular operations matched 1:1 by age and valvular surgery type with patients undergoing a traditional midline sternotomy approach. The prevalence of postoperative atrial fibrillation among patients with minimally invasive procedures versus traditional midline sternotomy was 26.3% versus 38.0%, respectively (p = 0.08). Neither multiple logistic regression nor Kaplan-Meier distribution analysis identified differences in postoperative atrial fibrillation between the 2 surgical techniques.

Noninvasive assessment of left atrial maximum dP/dt by a combination of transmitral and pulmonary venous flow

OBJECTIVES

The study assessed whether hemodynamic parameters of left atrial (LA) systolic function could be estimated noninvasively using Doppler echocardiography.

BACKGROUND

Left atrial systolic function is an important aspect of cardiac function. Doppler echocardiography can measure changes in LA volume, but has not been shown to relate to hemodynamic parameters such as the maximal value of the first derivative of the pressure (LA dP/dt(max)).

METHODS

Eighteen patients in sinus rhythm were studied immediately before and after open heart surgery using simultaneous LA pressure measurements and intraoperative transesophageal echocardiography. Left atrial pressure was measured with a micromanometer catheter, and LA dP/dt(max) during atrial contraction was obtained. Transmitral and pulmonary venous flow were recorded by pulsed Doppler echocardiography. Peak velocity, and mean acceleration and deceleration, and the time-velocity integral of each flow during atrial contraction was measured. The initial eight patients served as the study group to derive a multilinear regression equation to estimate LA dP/dt(max) from Doppler parameters, and the latter 10 patients served as the test group to validate the equation. A previously validated numeric model was used to confirm these results.

RESULTS

In the study group, LA dP/dt(max) showed a linear relation with LA pressure before atrial contraction (r = 0.80, p < 0.005), confirming the presence of the Frank-Starling mechanism in the LA. Among transmitral flow parameters, mean acceleration showed the strongest correlation with LA dP/dt(max) (r = 0.78, p < 0.001). Among pulmonary venous flow parameters, no single parameter was sufficient to estimate LA dP/dt(max) with an r2 > 0.30. By stepwise and multiple linear regression analysis, LA dP/dt(max) was best described as follows: LA dP/dt(max) = 0.1 M-AC +/- 1.8 P-V - 4.1; r = 0.88, p < 0.0001, where M-AC is the mean acceleration of transmitral flow and P-V is the peak velocity of pulmonary venous flow during atrial contraction. This equation was tested in the latter 10 patients of the test group. Predicted and measured LA dP/dt(max) correlated well (r = 0.90, p < 0.0001). Numerical simulation verified that this relationship held across a wide range of atrial elastance, ventricular relaxation and systolic function, with LA dP/dt(max) predicted by the above equation with r = 0.94.

CONCLUSIONS

A combination of transmitral and pulmonary venous flow parameters can provide a hemodynamic assessment of LA systolic function.

Analysis of risk factors for development of atrial fibrillation early after cardiac valvular surgery

Atrial fibrillation (AF) commonly develops after cardiac valvular surgery. The objective of this study was to identify risk factors for postoperative AF following valvular surgery. A cohort of 915 consecutive adult patients undergoing isolated valvular surgery with preoperative sinus rhythm was analyzed. Univariate and independent multivariate risk factors for postoperative AF were determined. A second cohort of 305 patients with the same inclusion criteria was used to validate the multivariate predictors. Patients studied had a mean age of 56.1 +/- 14.7 years, 57.9% were men, 79.6% had a normal left ventricular ejection fraction, and their mean left atrial size was 46.2 +/- 9.3 mm. The incidence of postoperative AF was 36.7%. Independent predictors of postoperative AF included: advanced age (odds ratio [OR] 1.506 per decade, 95% confidence interval, [CI] 1.35 to 1.68, p = 0.0001); mitral stenosis (OR 2.066, CI 1.21 to 3.52, p = 0.0077); left atrial enlargement (OR 1.468, CI 1.07 to 2.01, p = 0.0165); use of systemic hypothermia (OR 0.572, CI 0.422 to 0.776, p = 0.0003); and a history of cardiac surgery (OR 0.676, CI 0.465 to 0.981, p = 0.0393). Among these variables, advanced age, mitral stenosis, and left atrial enlargement were confirmed as independent risk factors in the validation cohort.

The role of intraoperative echocardiography in valve surgery

The widespread use and popularity of intraoperative echocardiography (IOE) has resulted from advances in cardiac surgery, reparative procedures for valvular heart disease and, most specifically, mitral valve repair. IOE has grown exponentially and is becoming an integral part of the planning and evaluation of many types of surgical procedures such that it is now considered standard of care especially for the perioperative management of patients undergoing mitral and aortic valve repair. This article discusses the application of intraoperative echocardiography and focus specifically on valvular heart disease as this represents the most widely accepted indication for the procedure in current clinical practice.

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.

Cardioversion guided by transesophageal echocardiography: the ACUTE Pilot Study. A randomized, controlled trial. Assessment of Cardioversion Using Transesophageal Echocardiography

BACKGROUND

Electrical cardioversion in patients with atrial fibrillation is associated with an increased risk for embolic stroke. Screening for atrial thrombi with transesophageal echocardiography (TEE) before cardioversion should, in many patients, safely permit cardioversion to be done earlier than would be possible with prolonged conventional, anticoagulation therapy.

OBJECTIVE

To compare the feasibility and safety of TEE-guided early cardioversion with those of conventional management of cardioversion in patients with atrial fibrillation.

DESIGN

Randomized, multicenter clinical trial.

SETTING

10 hospitals in the United States, Europe, and Australia.

PATIENTS

126 patients who had atrial fibrillation lasting longer than 2 days and were having electrical cardioversion.

INTERVENTION

Conventional therapy or early, TEE-guided cardioversion with short-term anticoagulation therapy.

OUTCOME MEASURES

Feasibility outcome variables were frequency of cardioversion and times to cardioversion and sinus rhythm. Safety outcomes were ischemic stroke, transient ischemic attack, systemic embolization, bleeding, and detected episodes of clinical hemodynamic instability occurring as long as 4 weeks after cardioversion.

RESULTS

62 patients were randomly assigned to receive TEE-guided cardioversion; TEE was done in 56 (90%) of these patients. Atrial thrombi were detected in 7 patients (13%) and led to the postponement of cardioversion. Cardioversion was successful in 38 of 45 patients (84%) who had early cardioversion. No embolization occurred with this strategy. Of the 64 patients receiving conventional therapy, 37 (58%) had cardioversion, which was successful in 28 patients (76%). One patient had a peripheral embolic event. The time to cardioversion was shorter in the TEE group (0.6 weeks [95% CI, 0.3 to 0.9 weeks] compared with 4.8 weeks [CI, 3.8 to 5.7 weeks]; P < 0.01). The incidence of clinical hemodynamic instability and bleeding complications tended to be greater in the conventional therapy group.

CONCLUSIONS

These results suggest that TEE-guided cardioversion with short-term anticoagulation therapy is feasible and safe. The use of TEE may allow cardioversion to be done earlier, may decrease the risk for embolism associated with cardioversion, and may be associated with less clinical instability than conventional therapy. A large, multicenter study to confirm these findings is currently under way.

Characterization of left atrial appendage Doppler flow in atrial fibrillation and flutter by Fourier analysis

The aim of this study was to characterize left atrial appendage mechanical function in atrial fibrillation and flutter by Fourier analysis to analyze frequency and regularity of flow. Left atrial appendage function is central to a patient's risk for thromboembolism. Although the function of the appendage can be analyzed by Doppler echocardiography in sinus rhythm, its mechanical function in atrial fibrillation and flutter has not been well characterized. This lack of adequate definition is caused by the complexity and temporal variability of the Doppler flow profiles. We assessed left atrial appendage function in 21 cases of atrial fibrillation (n - 11) and flutter (n = 10) and five in sinus rhythm with transesophageal Doppler echocardiography. Doppler profiles were examined by Fourier analysis, and the power spectra compared and analyzed between patients with atrial fibrillation and flutter. Left atrial appendage Doppler flow in atrial fibrillation produced Fourier spectra over a narrow band of frequencies with a peak frequency of 6.2 +/- 1.0 Hz, significantly higher than in atrial flutter (3.9 +/- 0.6 Hz, p < 0.00001). Additionally, a significant difference in subharmonic modulation (spectral power below the peak frequency) was observed between atrial appendage flow in atrial fibrillation and flutter, because 37% +/- 16% of the total spectral power was achieved before the dominant frequency in atrial fibrillation compared with 20% +/- 14% in atrial flutter (p = 0.02). Conversely, patients in sinus rhythm exhibited broad-banded Fourier spectra with most of the power in discrete frequency spikes at harmonics above the fundamental frequency with very little subharmonic modulation (1% +/- 0.05%). Left atrial appendage function in atrial fibrillation and flutter can be well characterized by Fourier analysis of Doppler flow. Atrial fibrillation has higher dominant frequencies and greater subharmonic modulation compared with flutter. Moreover, atrial fibrillation demonstrated quasiperiodic contraction patterns typically found in chaotic systems. Fourier analysis of left atrial appendage contraction patterns may therefore have significant promise in providing insights into mechanisms of atrial fibrillation and thromboembolism.

Transesophageal echocardiography-guided approach to cardioversion of atrial fibrillation

In patients with atrial fibrillation, electrical cardioversion is often performed to relieve symptoms, to improve left ventricular function, and to decrease thromboembolic risks. However, cardioversion of atrial tachyarrhythmias is associated with an increased embolic risk, with an event rate of up to 5.6%. The American College of Chest Physicians recommend 3 weeks of systemic anticoagulation before elective cardioversion and 4 weeks of systemic anticoagulation afterwards. Expulsion of preexisting left atrial (LA) thrombi with resumption of sinus rhythm has traditionally been considered the mechanism for this increased embolic risk associated with cardioversion. The advent of transesophageal echocardiography (TEE) has allowed accurate detection of LA thrombus. Moreover, recent studies using TEE have identified a state of atrial "stunning" immediately after cardioversion, which is considered a thrombogenic milieu in which new thrombus formation and increased or de novo appearance of LA spontaneous echocardiographic contrast have been observed. Furthermore, embolic events have been reported after cardioversion despite exclusion of preexisting LA thrombus by TEE. These studies strongly suggest an alternative mechanism for embolism after cardioversion, ie, atrial stunning with worsened atrial appendage function and enhanced thrombogenesis. Recent studies have shown the safety of a TEE-guided anticoagulation approach in which exclusion of preexisting LA thrombus by TEE enables early cardioversion without the need for the standard 3 weeks of systemic anticoagulation. The importance of maintaining therapeutic anticoagulation has been further emphasized. Although preliminary observational studies of TEE-guided cardioversion are encouraging, there has been no prospective, randomized trial comparing the two strategies of anticoagulation management. The Assessement of Cardioversion Utilizing Transesophageal Echocardiography (ACUTE) pilot study randomized 126 patients from 10 sites and showed the feasibility and safety of the larger scale study. A larger multicenter, prospective randomized trial is now underway and is expected to randomize a total of 3,000 patients. The results of the ACUTE study will definitively establish the safest and the most cost-effective way to manage anticoagulation for elective cardioversion.

Integrated backscatter for quantification of left atrial spontaneous echo contrast

OBJECTIVES

This study was designed to develop a quantitative method of spontaneous echo contrast (SEC) assessment using integrated backscatter and to compare integrated backscatter SEC measurement with independent qualitative grades of SEC and clinical and echocardiographic predictors of thromboembolism.

BACKGROUND

Left atrial SEC refers to dynamic swirling smokelike echoes that are associated with low flow states and embolic events and have been graded qualitatively as mild or severe.

METHODS

We performed transesophageal echocardiography in 43 patients and acquired digital integrated backscatter image sequences of the interatrial septum to internally calibrate the left ventricular cavity and left atrial cavity under different gain settings. Patients were independently assessed as having no, mild or severe SEC. We compared intensity of integrated backscatter in the left atrial cavity relative to that in the left ventricular as well as to the independently assessed qualitative grades of SEC. Fourier analysis characterized the temporal variability of SEC. The integrated backscatter was compared with clinical and echocardiographic predictors of thromboembolism.

RESULTS

The left atrial cavity integrated backscatter intensity of the mild SEC subgroup was 4.7 dB higher than that from the left ventricular cavity, and the left atrial intensity of the severe SEC subgroup was 12.5 dB higher than that from the left ventricular cavity. The left atrial cavity integrated backscatter intensity correlated well with the qualitative grade. Fourier transforms of SEC integrated backscatter sequences revealed a characteristic dominant low frequency/high amplitude spectrum, distinctive from no SEC. There was a close relationship between integrated backscatter values and atrial fibrillation, left atrial size, left atrial appendage flow velocities and thrombus.

CONCLUSIONS

Integrated backscatter provides an objective quantitative measure of SEC that correlates well with qualitative grade and is closely associated with clinical and echocardiographic predictors of thromboembolism. The relationship between integrated backscatter measures and cardioembolic risk will be defined in future multicenter studies.

Recurrent cerebral vascular accidents are an indication for ascending aortic endarterectomy

We present a patient with severe pedunculated ascending atherosclerosis associated with recurrent cerebral vascular accidents. We recommend that endarterectomy be considered for patients with recurrent cerebral vascular accidents associated with severe atherosclerosis of the ascending aorta when no other cause is found to explain the symptoms.

The effect of technical factors on the quality of pulmonary venous flow from the transverse and longitudinal imaging planes with transesophageal echocardiography

Right and left upper pulmonary venous flow is usually assessed with monoplane transesophageal echocardiography (TEE) in the transverse imaging plane. Pulmonary venous flow in the transverse imaging plane may be relatively difficult to record because of the larger angle between the pulmonary vein and the transducer beam. To compare the quality of echocardiographically derived Doppler flows of the right and left upper pulmonary veins between the longitudinal and transverse imaging planes with TEE, we performed pulsed-wave Doppler TEE of both upper pulmonary veins in transverse and longitudinal imaging planes in 36 patients with various diseases. We also recorded a quality index for each flow profile and the angle between the transducer beam and the pulmonary vein. The quality index of the left pulmonary venous flow assessed with the longitudinal and transverse imaging planes was similar in 35 (95%) of 36 patients, whereas the longitudinal imaging plane was superior to the transverse plane in one patient (3%). In contrast, the quality index of the right pulmonary venous flow assessed with the longitudinal and transverse imaging planes was similar in only 19 (53%) of 36 patients, whereas in 17 patients (47%) the longitudinal imaging plane was superior to the transverse imaging plane. The quality index had a significant effect on the Doppler flow recordings; suboptimal-quality flow recordings significantly underestimated the pulmonary venous diastolic flow integrals. The left atrium was larger in those patients with unobtainable flows than in those patients with exclusively obtainable flows (p < 0.001). The angle between the sample volume and the right pulmonary vein was larger in the transverse imaging plane than in the longitudinal plane (p < 0.001). In conclusion, the longitudinal imaging plane is generally superior to the transverse imaging plane for assessing right pulmonary venous flow and is recommended for performing a comprehensive assessment of pulmonary venous flow. The ability to obtain quality images and accurate assessment of flow may be related to the size of the left atrium and angle of the pulmonary vein.

Selection of patients for transesophageal echocardiography after stroke and systemic embolic events. Role of transthoracic echocardiography

BACKGROUND AND PURPOSE

This study examined whether patients suffering from stroke and other systemic embolic events may be selected for transesophageal echocardiography on the basis of clinical and transthoracic echocardiographic findings.

METHODS

We performed transthoracic and transesophageal echocardiography on 824 patients after stroke and other suspected embolic events. Patients were classified into group A if they were in sinus rhythm and had a normal transthoracic echocardiogram. Group B consisted of all other patients. Transesophageal echocardiographic findings of left atrial spontaneous contrast, left atrial thrombus, complex aortic atheroma, and interatrial septal anomalies were correlated with clinical and transthoracic echocardiographic results.

RESULTS

Transesophageal echocardiography detected at least one potential source of embolism in 399 patients (49%): spontaneous contrast in 214 patients (26%), left atrial thrombus in 54 (7%), complex atheroma in 111 (13%), and interatrial septal anomalies in 126 (15%). In group A (n = 236), only 3 (1%) had spontaneous contrast, 11 (4.6%) had complex atheroma, and none had left atrial thrombus. In group B (n = 588), 211 patients (36%, P < .001) had spontaneous contrast, 54 (9.2%, P < .001) had atrial thrombus, and 100 (17%, P < .001) had complex atheroma. Interatrial septal anomalies were detected in similar proportions of patients (18% in group A versus 14% in group B). Left atrial spontaneous echo contrast, thrombus, and complex atheroma were significantly more prevalent in older patients, but interatrial septal anomalies were more prevalent in younger patients irrespective of transthoracic echocardiographic findings. Multivariate analysis identified both an abnormal transthoracic echocardiogram and patient age to be independent predictors of transesophageal echocardiographic findings of left atrial spontaneous echo contrast, left atrial thrombus, or complex atheroma.

CONCLUSIONS

Transesophageal echocardiography has a low yield for left atrial spontaneous contrast, left atrial thrombus, or complex aortic atheroma in patients with normal transthoracic echocardiogram and sinus rhythm and in younger patients. Interatrial septal anomalies are more prevalent in younger patients. Transthoracic echocardiogram should be performed in patients after stroke or systemic embolic events as a noninvasive screening tool. We recommend transesophageal echocardiogram for patients with abnormal transthoracic echocardiogram and in younger patients when the finding of a patent foramen ovale may contribute to patient management.