Assessment of left atrial appendage function by biplane transesophageal echocardiography in patients with nonrheumatic atrial fibrillation: identification of a subgroup of patients at increased embolic risk

Impaired atrial contraction in patients with atrial flutter and gradual recovery after cardioversion

The risk of thromboembolism after cardioversion of atrial flutter is controversial. The present study provides evidence for blood stasis in the atria of patients with atrial flutter and for gradual recovery of atrial contraction after cardioversion, which justifies prophylactic treatment at cardioversion, as for atrial fibrillation. We examined atrial thrombi and peak flow velocity in the left atrial appendage as an index of blood stasis in 5 consecutive patients with atrial flutter. Transesophageal echocardiography revealed a thrombus in 1 patient, and peak flow velocity in the left atrial appendage was inversely correlated with left atrial dimension (r = -0.90, p < 0.05). After restoration of sinus rhythm, transmitral flow velocity in late diastole was also examined to evaluate the recovery of atrial contraction. The recovery of transmitral flow velocity the next day and 1 week after cardioversion was correlated with flow velocity in the left atrial appendage before cardioversion (r = 0.89, p < 0.05; r = 0.97, p < 0.01, respectively). These findings suggest that some patients with atrial flutter have impaired atrial contraction and that prolonged impairment after cardioversion is also possible. Atrial enlargement and low flow velocity in the atrial appendage were predictive factors for such patients.

Risk of complications of atrial fibrillation

Atrial fibrillation is associated with three major risk of complications: thromboembolism, hemodynamic compromise, and arrhythmogenesis. In patients with chronic atrial fibrillation the incidence of embolization is about 5% per year. The risk of embolism and in particular of stroke can be reduced by warfarin anticoagulation. Aspirin is generally less effective than warfarin, although it is probably more effective than placebo. The hemodynamic complications which may occur during atrial fibrillation are mainly due to the loss of effective atrial contraction, the irregular ventricular rhythm, and the possible excessively rapid ventricular rate. Sudden death is a recognized manifestation of Wolff-Parkinson-White syndrome and is considered to be precipitated by atrial fibrillation in the majority of patients. Torsades de pointes is perhaps the most widely recognized proarrhythmia associated with treatment of atrial fibrillation, especially with 1A antiarrhythmic drugs and sotalol. The chronic treatment with type 1C drugs in 3.5%-5% of patients may induce atrial flutter with 1:1 conduction with significant hemodynamic compromise.

Is left atrial appendage flow a predictor for outcome of cardioversion of nonvalvular atrial fibrillation? A transthroacic and transesophageal echocardiographic study

Accurate echocardiographic parameters for predicting the success of cardioversion or maintenance of sinus rhythm are poorly defined. This prospective transthoracic and transesophageal echocardiographic study was conducted to test the hypothesis that the left atrial appendage flow pattern could be a predictive parameter of the success of cardioversion and maintenance of sinus rhythm in patients with nonvalvular atrial fibrillation. Eighty-two consecutive patients with nonvalvular atrial fibrillation of <6 months' duration underwent transesophageal examination after transthoracic echocardiography. After exclusion of left atrial thrombus, pharmacologic (n = 18) or electrical (n = 64) cardioversion was successful in 75 of 82 patients. In the group that underwent successful cardioversion, maintenance of sinus rhythm (n = 35) or recurrence of arrhythmia (n = 40) was assessed during a 1-year follow-up. During transesophageal examination, five left atrial appendage thrombi were found, spontaneous echo contrast was present in 26 (32%) patients, and mean peak left atrial appendage emptying velocity was 35 +/- 18 cm/sec. Peak left atrial appendage emptying velocity was found to be statistically related to parameters of left ventricular and left atrial function but not to long-term maintenance of sinus rhythm. No other echocardiographic parameter was identified as a predictor for either the success of cardioversion or the maintenance of sinus rhythm at follow-up. In patients with nonvalvular atrial fibrillation of recent onset, peak left atrial appendage emptying velocity appears to be a complex parameter depending on left atrial and left ventricular function but that does not predict either the success rate of cardioversion or long-term maintenance of sinus rhythm after successful cardioversion.

Left atrial spontaneous echo contrast in patients with permanent pacemakers

OBJECTIVE

To determine the relations between left atrial appendage function, spontaneous echo contrast, and thromboembolism in patients with different modes of permanent pacemakers.

PATIENTS AND METHODS

88 patients with pacemaker implantation and 25 healthy controls in sinus rhythm had transoesophageal echocardiographic examination of the left atrial appendage. Left atrial size, appendage area, peak filling and emptying velocities of the atrial appendage, and the presence or absence of spontaneous echo contrast and thromboembolism were determined. The results in 63 patients with ventricular pacing (group 1, subdivided into subgroup 1A: 42 patients with sinus rhythm, and subgroup 1B: 21 patients with atrial fibrillation) were compared with those in 25 patients with synchronous pacing (group 2), and 25 normal control subjects (group 3).

RESULTS

Patients with ventricular pacing had two distinct appendage flow patterns: well defined biphasic filling and emptying waves in subgroup 1A, and irregular very low filling and emptying waves in subgroup 1B. The ejection fraction of the left atrial appendage in subgroup 1A was significantly better than that in subgroup 1B (mean (SD) 40.6 (12.0)% v 7.6 (5.0)%, P < 0.0001). The spontaneous echo contrast was observed in 90% of subgroup 1B patients but in only 19% in subgroup 1A (P < 0.05) and was not found in groups 2 and 3 (P < 0.0001). There was a trend for increased prevalence of spontaneous echo contrast in subgroup 1A v group 2 (P = 0.053). Thrombi were detected in two cases, and cardiogenic embolism occurred in one case in subgroup 1B. All patients with spontaneous echo contrast had ventricular pacing. Multivariate analysis showed that atrial fibrillation was associated with occurrence of spontaneous echo contrast in patients with ventricular pacing (P = 0.005).

CONCLUSIONS

The left atrial appendage ejection fraction was lower with ventricular pacing than with synchronous pacing. With ventricular pacing there was a trend towards increased prevalence of left atrial spontaneous echo contrast in patients in sinus rhythm, and a significantly increased prevalence in patients with atrial fibrillation.

Transthoracic Versus Transesophageal Two-Dimensional Echo Doppler Determination of Flow Velocity in the Left Atrial Appendage

The assessment of flow velocity (FV) in the left atrial appendage (LAA) by transesophageal echocardiography (TEE) has been reported to be a useful tool as a high risk marker for systemic emboli. The analysis of FV in LAA by transthoracic echocardiography (TTE) has not yet been validated. The purpose of this study was to compare FV measurements in the LAA by TEE and TTE in 30 consecutive patients (age 19-87 years, mean = 55) sent for echocardiographic study with the following diagnosis: stroke (11 patients), mitral stenosis (6 patients), congenital heart disease (4 patients), mitral prosthetic function assessment (2 patients), and other pathologies (7 patients). FV was measured at the outlet and mid-portion of the LAA with TTE, from the apical two-chamber view and with biplane TEE, from the longitudinal two-chamber view. Satisfactory measurements were obtained with TTE from the outlet of the LAA in 96.7% and from the mid-portion of the LAA in 90% of patients. One third of patients were in atrial fibrillation (AF) during the study. The mean FV in the outlet of the LAA was 32.7 +/- 2.5 (SE) cm/sec with TTE and was 33.7 +/- 3.04 (SE) cm/sec with TEE (r = 0.95). The mean FV in the mid-portion of the LAA was 40.9 +/- 3.3 and 42.7 +/- 3.9 with TTE and TEE respectively (P = NS) (r = 0.95). There was no difference in the LAA FV determination by TTE and TEE in the subgroup with AF. TTE was able to detect FV < 30 cm/sec with a sensitivity of 88% and specificity of 81% and a positive predictive value of 84% compared with TEE.

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

The aim of this study was to assess the value of transesophageal echocardiography (TEE) in patients with atrial fibrillation in predicting restoration and maintenance of sinus rhythm after electrical cardioversion. TEE was performed in 62 patients with atrial fibrillation before their first elective cardioversion. Clinical variables evaluated were: age, gender, duration, and etiology of atrial fibrillation. TEE variables included: left atrial (LA) length, width, and size, LA annulus size, as well as presence of LA spontaneous contrast, thrombus and mitral regurgitation, LA appendage size and flow, and left ventricular function. Based on initial outcome of cardioversion, patients were grouped into patients who remained in atrial fibrillation and in whom sinus rhythm was restored. The latter group of patients was followed for 1 year, and grouped into patients who reverted to atrial fibrillation and in whom sinus rhythm was maintained. Successful cardioversion was achieved in 50 of 62 patients (81%). None of the clinical or TEE variables were related to initial outcome. At 1-year follow-up, 29 of 50 patients (58%) who underwent successful cardioversion continued to have sinus rhythm. The following variables were related to maintenance of sinus rhythm: duration of atrial fibrillation (6.7 +/- 7.3 vs 2.0 +/- 2.4 months; p < 0.005); LA length (6.2 +/- 0.7 vs. 5.5 +/- 1.0 cm; p < 0.008); width (5.1 +/- 0.5 vs. 4.5 +/- 0.7 cm; p < 0.002); size (26.4 +/- 5.0 vs 19.8 +/- 6.5 cm2; p < 0.0005); annulus size (4.0 +/- 0.2 vs 3.7 +/- 0.3 cm; p < 0.0005); presence of LA spontaneous contrast (13 [62%] vs 4 [14%]; p < 0.002), and LA appendage flow (19 +/- 8 vs 36 +/- 15 cm/s; p < 0.0005). In multivariate logistic regression analysis, LA annulus size, but especially LA appendage flow, were significantly associated with maintenance of sinus rhythm. Thus, in TEE-guided electrical cardioversion of atrial fibrillation, variables often used to assess thromboembolic risk may also be used to predict 1-year outcome of cardioversion.

Improved Doppler echocardiographic assessment of the left atrial appendage by peripheral vein injection of sonicated albumin microbubbles

We evaluated the usefulness of peripherally injected sonicated albumin microbubbles in transesophageal echo-Doppler cardiographic assessment of the left atrial appendage in 19 patients (age 61 +/- 19 [range 21 to 86] years; 12 [63%] women). Multiplane transesophageal echocardiography was performed before and after intravenous injection of sonicated albumin, and the left atrial appendage image and Doppler flow signal quality were assessed by a grading system of 0 to 3+ (0 = poor, 1 + = adequate, 2+ = good, and 3+ = excellent). Microbubbles appeared in the left atrium in 15 (79%) of 19 patients and completely opacified the left atrial appendage in 7 (37%) of 19 patients. Left atrial appendage maximal and minimal areas by planimetry were similar before and after contrast injection, although image quality improved in 13 (68%) of 19 patients (echocardiographic grade 1.8 +/- 0.6 vs 2.6 +/- 0.5, p< 0.001). Similarly, left atrial appendage peak emptying and peak filling Doppler flow velocities did not change before and after contrast injection, although Doppler flow signal quality improved in 12 (63%) of 19 patients (Doppler grade 1.6 +/- 0.5 vs 2.1 +/- 0.8, p < 0.05). Overall, contrast injection improved left atrial appendage echocardiographic or Doppler quality in 16 (84%) of 19 patients. Thus peripheral vein injection of sonicated albumin microbubbles can improve the assessment of left atrial appendage structure and function by transesophageal echocardiography.

Evaluation of left atrial appendage function by measurement of changes in flow velocity patterns after electrical cardioversion in patients with isolated atrial fibrillation

We investigated temporary changes in left atrial appendage (LAA) flow velocity patterns in patients undergoing electrical cardioversion for chronic isolated atrial fibrillation, and evaluated the role of active LAA contraction in directing blood flow to the left atrial main chamber and left ventricle. The study consisted of 26 patients with chronic isolated atrial fibrillation treated with electrical cardioversion and 20 normal controls in sinus rhythm. Using transthoracic and transesophageal Doppler echocardiography, we recorded transmitral, pulmonary venous, and LAA flow velocity patterns before, 24 hours, and 1 week after cardioversion in all subjects. In the 15 patients who underwent successful cardioversion, the maximal LAA area 24 hours after cardioversion was smaller than the area before cardioversion, whereas LAA ejection fraction during atrial systole and peak atrial systolic emptying velocity of the LAA flow were lower 24 hours after cardioversion than those in the control group. One week after cardioversion, maximal LAA area and LAA peak atrial systolic emptying velocity were restored to levels approximately equivalent to those in the control group, although LAA ejection fraction was lower than in the control group. Maximal LAA area and LAA peak atrial systolic emptying velocity correlated negatively and positively with LAA ejection fraction, respectively, 24 hours and 1 week after cardioversion. These results suggest that LAA and the left atrial main chamber show stunning 24 hours after cardioversion, and the atrial systolic emptying wave of LAA flow is generated by active LAA contraction.

Left atrial chamber and appendage function after internal atrial defibrillation: a prospective and serial transesophageal echocardiographic study

OBJECTIVES

The purpose of this prospective study was to assess left atrial chamber and appendage function after internal atrial defibrillation of atrial fibrillation and to evaluate the time course of recovery.

BACKGROUND

External cardioversion of atrial fibrillation may result in left atrial appendage dysfunction ("stunning") and may promote thrombus formation. In contrast to external cardioversion, internal atrial defibrillation utilizes lower energies; however, it is unknown whether the use of lower energies may avoid stunning of the left atrial appendage.

METHODS

Transesophageal and transthoracic echocardiography were performed in 20 patients 24 h before and 1 and 7 days after internal atrial defibrillation to assess both left atrial chamber and appendage function. Transthoracic echocardiography was again performed 28 days after internal atrial defibrillation to assess left atrial function. The incidence and degree of spontaneous echo contrast accumulation (range 1+ to 4+) was noted, and peak emptying velocities of the left atrial appendage were measured before and after internal atrial defibrillation. To determine left atrial mechanical function, peak A wave velocities were obtained from transmitral flow velocity profiles.

RESULTS

Sinus rhythm was restored in all patients. The mean +/- SD peak A wave velocities increased gradually after cardioversion, from 0.47 +/- 0.16 m/s at 24 h to 0.61 +/- 0.13 m/s after 7 days (p < 0.05) and 0.63 +/- 0.13 m/s after 4 weeks. Peak emptying velocities of the left atrial appendage were 0.37 +/- 0.16 m/s before internal atrial defibrillation, decreased significantly after internal atrial defibrillation to 0.23 +/- 0.1 m/s at 24 h (p < 0.01) and then recovered to 0.49 +/- 0.23 m/s (p < 0.01) after 7 days. The corresponding values for the degree of spontaneous echo contrast were 1.2 +/- 1.2 before internal atrial defibrillation versus 2.0 +/- 1.0 (p < 0.01) and 1.1 +/- 1.3 (p < 0.01) 1 and 7 days after cardioversion, respectively. One patient developed a new thrombus in the left atrial appendage, and another had a thromboembolic event after internal atrial defibrillation.

CONCLUSIONS

Internal atrial defibrillation causes depressed left atrial chamber and appendage function and may result in the subacute accumulation of spontaneous echo contrast and development of new thrombi after cardioversion. These findings have important clinical implications for anticoagulation therapy before and after low energy internal atrial defibrillation in patients with atrial fibrillation.

Prediction of outcome of electrical cardioversion by left atrial appendage flow velocities in atrial fibrillation

We evaluated the usefulness of left atrial appendage (LAA) flow velocity during atrial fibrillation as an objective measure for prediction of the outcome of electrical cardioversion. Left atrial appendage peak velocities were measured by transesophageal echocardiography before cardioversion in 56 patients. Left atrial thrombus was demonstrated in 6 (11%) of these patients. Cardioversion was then performed in the 50 patients who did not have a thrombus and in 1 patient whose left atrial thrombus disappeared after anticoagulant therapy (n = 51). Thirty-eight patients converted to sinus rhythm which remained stable until discharge (initial success group). Of these, long-term (> 6 months) maintenance of sinus rhythm was achieved in 31 patients (82%). Five patients with almost no detectable appendage contractions during atrial fibrillation were classified in the initial failure group. The peak LAA flow velocity was significantly higher in patients with the initial success group compared with the patients in the initial failure group (25.6 +/- 12.0 vs 15.3 +/- 10.7 cm/s, respectively; p < 0.01). Left atrial appendage flow velocity during atrial fibrillation may be useful for identifying candidates for electrical cardioversion.

Left atrial spontaneous echo contrast in asymptomatic patients with a mechanical valve prosthesis

BACKGROUND

Valve thromboembolism may be a fatal complication of mechanical valve prosthesis if detected late. Spontaneous echo contrast (SEC) is a well-documented prothrombotic phenomenon; here we report it in asymptomatic patients with a mechanical valve prosthesis.

METHODS

Ninety-two asymptomatic patients with a mechanical valve prosthesis for underlying rheumatic heart disease underwent transesophageal echocardiography. Appendage area, peak filling and emptying velocities of the left atrial appendage, and the presence or absence of SEC and thrombi were determined. The results of 56 patients without SEC or thrombi (group I) were compared with those of 24 patients with SEC and no thrombi (group II) and 12 patients with thrombi (group III).

RESULTS

Spontaneous echo contrast was present in 39% of the asymptomatic patients with a mechanical valve prosthesis. Although 12 patients had cardiac thrombi, including valve thrombi in 4, no patients presented symptoms. Anticoagulant therapy had no significant association with SEC and atrial thrombi. There was a significantly greater prevalence of atrial fibrillation and mitral prosthesis in groups II and III than in group I. Two patterns of left atrial appendage flow were identified: one was organized biphasic flow with peak filling velocities of 41.2 +/- 17.2 cm/s and emptying velocities of 40.5 +/- 17.5 cm/s. The other showed irregular, very low peak filling velocities (104 +/- 11.5 cm/s) and emptying velocities (12.3 +/- 13.1 cm/s). The former flow pattern was associated with sinus rhythm and the latter form was associated with atrial fibrillation.

CONCLUSIONS

There was a relatively high prevalence of SEC and thrombi in patients with a mechanical valve prosthesis. Patients with a valve prosthesis may not have clinical symptoms. Anticoagulation intensity was not associated with the occurrence of SEC and thrombi. Patients with the mitral valve prosthesis and atrial fibrillation were identified as a high-risk of subgroup for the development of SEC and thrombi.

Left atrial appendage blood flow in a case of persistent atrial standstill

Persistent atrial standstill, characterized by absence of atrial activity on surface and intracavitary electrograms, absence of atrial mechanical activity, and inability to stimulate the atria electrically, is a rare disorder. Left atrial appendage blood flow has been reported to be related to P wave during sinus rhythm or local atrial electrogram during atrial fibrillation. However, distinct and periodical LAA blood flow was demonstrated in a patient with persistent atrial standstill by transesophageal echocardiography.

Role of echocardiography in the evaluation and management of atrial fibrillation

This article reviews the utility of transthoracic echocardiography and transesophageal echocardiography for patients with atrial fibrillation and focuses on evidence that these diagnostic techniques can aid in the achievement of these goals. Following a brief review of common findings from each of these techniques, the relevance of specific results to the management of atrial fibrillation is assessed.

Influence of left atrial pressure on left atrial appendage flow velocity patterns in patients in sinus rhythm

To examine changes in left atrial appendage flow velocity patterns in relation to left atrial pressures during sinus rhythm, transesophageal echocardiography and cardiac catheterization were performed in 31 patients with myocardial diseases in sinus rhythm and 20 control subjects without cardiovascular disease. The 31 patients were divided into two groups according to mean pulmonary capillary wedge pressure: the group with high wedge pressure (19.9 +/- 5.8 mmHg) and the group with low wedge pressure (8.6 +/- 2.9 mmHg). The left atrial appendage peak early emptying velocity was decreased significantly in the groups with both high and low wedge pressure compared with the control group. The left atrial appendage peak late emptying velocity was significantly greater in the group with low wedge pressure compared with the control group, whereas it was decreased significantly in the group, with high wedge pressure compared with the control group. The left atrial appendage peak late emptying velocity had a significant negative correlation with wedge pressure. The maximum left atrial appendage area at end systole in the group with high wedge pressure was significantly greater than that in both the group with low wedge pressure and the control group. There was a significant positive correlation between the maximum left atrial appendage area and the wedge pressure, as well as a significant negative correlation between the left atrial appendage ejection fraction during atrial contraction and the wedge pressure. In the group with high wedge pressure, one patient had evidence of left atrial appendage thrombi and two had spontaneous echo contrast. These results suggest that even in patients in sinus rhythm, a marked elevation in the left atrial pressure is likely to reduce the left atrial appendage peak early and late emptying velocities. These changes may be accompanied by an increased incidence of thrombus formation in the left atrial appendage compared with individuals with normal or only slightly elevated left atrial pressures.

Patterns of Doppler-measured blood flow velocity in the normal and fibrillating human left atrial appendage

Doppler measurement of left atrial appendage (LAA) blood velocity during transesophageal echocardiography has been proposed as a method of assessing LAA contractile function and thromboembolic risk. Clinical and echocardiographic determinants of five LAA Doppler blood velocity patterns were examined in 40 patients with a history of atrial fibrillation (AF), in 10 control subjects, and in 5 patients aged </=60 years having sinus rhythm and left ventricular hypertrophy. In sinus rhythm, two blood velocity patterns were differentiated by the extent of passive emptying of the LAA, which was related to age and left ventricular early diastolic filling properties. In AF, three blood velocity patterns were differentiated by the relative preservation of LAA mechanical function during fibrillatory activity. LAA contractile function is an important but not the sole determinant of blood flow in the normal and fibrillating human LAA.

Evaluation of left atrial appendage anatomy and function in recent-onset atrial fibrillation by transesophageal echocardiography

Data regarding left atrial (LA) and LA appendage anatomy and function among patients with newly recognized atrial fibrillation (AF) who have not received long-term warfarin are currently unknown. To identify echocardiographic indexes which characterize those at increased risk for thrombus formation, we analyzed transesophageal echocardiographic studies in 100 consecutive patients with newly recognized AF (duration 2.6 +/- 0.3 week) who had not received long-term warfarin. Fourteen percent of patients had LA thrombi. LA thrombi were associated with larger LA appendages, more depressed LA appendage outflow velocities, and a higher prevalence of severe spontaneous LA contrast. Patients with spontaneous contrast had larger LA and LA appendage anatomy and lower LA appendage ejection velocity. Among patients presenting with their first episode of AF, greater LA appendage ejection and filling velocities and smaller LA and LA appendage sizes were seen among those with AF of <2 weeks duration compared with those with AF of >2 weeks. Thus, patients with recent onset AF and LA thrombi or spontaneous echo contrast have more dilated LA and LA appendage anatomy, and more depressed LA appendage systolic function. Data from patients with their first episode of AF suggests that AF is associated with rapid LA remodeling.

Transesophageal echocardiography

This article presents an overview of the benefits and efficacy of transesophageal echocardiography (TEE) in the critically ill patient. The echocardiographic evaluation of ventricular function both regional and global, is discussed with special emphasis on ischemic heart disease; assessment of preload, interrogation of valvular heart disease (prosthetic and native) and its complications; endocarditis and its complications; intracardiac and extracardiac masses, including pulmonary embolism; aortic diseases (e.g., aneurysan, dissection, and traumatic tears); evaluation of patent foramen ovale and its association with central and peripheral embolic events; advancements in computer technology; and finally, the effect of TEE on critical care.

Evaluation of left atrial appendage stasis in patients with atrial fibrillation using transesophageal echocardiography with an intravenous albumin-contrast agent

To assess stasis in the left atrial appendage in patients with atrial fibrillation and to identify patients at increased risk for thromboembolism, we performed transesophageal echocardiography with an intravenous albumin contrast agent (Albunex) in 25 patients with atrial fibrillation and in 22 patients in sinus rhythm. We demonstrated that the absence of opacification in the left atrial appendage after Albunex administration implies a high risk of left atrial thrombus and cardiogenic thromboembolism.

Risk of thromboembolism in new onset or transient atrial fibrillation

Atrial fibrillation (AF), potentially serious cardiac arrhythmia, occurs in 2% to 4% of persons greater than 60 years of age. The risk of systemic thromboembolism from chronic AF has long been recognized. Little is known about the thromboembolic risk of new onset AF. However, the results of prior studies support a significant risk of thromboembolism because of recent onset or paroxysmal AF. The mechanism of thrombus formation, embolization, and resolution in AF is ill-defined, particularly that of new onset. The traditional concept holds that atrial thrombus forms only after greater than 2 days of AF and embolizes by dislodgement from increases in shear forces. This prevailing concept further proposes that newly formed atrial thrombus, in the setting of AF, organizes over a span of 14 days. The results of recent transesophageal echocardiographic studies have given insight into the temporal sequence of atrial thrombus formation, embolization, and resolution in AF and have expanded the traditional concept of thromboembolism in AF. Namely, left atrial thrombus may form before the onset of AF in the face of sinus rhythm. Conversion to sinus rhythm may increase the thrombogenic millieu of the left atrium. Importantly, atrial thrombus may form in the acute phase of AF. Lastly, thrombus may require more than 14 days to become immobile or to resolve. On the basis of these emerging insights by transesophageal echocardiography, it appears appropriate to consider anticoagulation in patients presenting with new onset or acute AF.

Atrial anatomy and function postcardioversion: insights from transthoracic and transesophageal echocardiography

Echocardiography provides a valuable tool for the evaluation and assessment of atrial function in patients with atrial fibrilation (AF). Atrial morphology after restoration of sinus rhythm is dynamic, with a decrease in atrial size if sinus rhythm is maintained and atrial growth among those with sustained AF. Restoration of electrocardiographic sinus rhythm is frequently accompanied by relatively depressed atrial mechanical function, with recovery that appears to be related to multiple factors, including the duration of AF before cardioversion and the mode of cardioversion. Such delay appears to confer ongoing risk for thrombus formation and thromboembolism in the days after cardioversion and argues strongly for the need to maintain therapeutic anticoagulation during the pericardioversion and postcardioversion period.

Stratification of thromboembolic risk of atrial fibrillation by transthoracic echocardiography and transesophageal echocardiography: the relative role of left atrial appendage function, mitral valve disease, and spontaneous echocardiographic contrast

The role of transesophageal echocardiography (TEE) in thromboembolic risk stratification in atrial fibrillation (AF) has not been established. Left atrial appendage contractile dysfunction in patients with AF predisposes to thrombus formation. The extent of blood stasis and propensity for thrombus can be assessed during TEE by measurement of the peak Doppler velocity of blood outflow from the appendage. Spontaneous echocardiographic contrast (SEC) is a swirling pattern of blood echogenicity that may be detected by TEE in the left atrium in patients with AF. The presence of SEC reflects left atrial blood stasis and a prothrombotic state. SEC is associated with an increased risk of systemic thromboembolic events. Parameters derived from TEE may provide additional prognostic data to clinical history and transthoracic echocardiography in thromboembolic risk stratification in AF.

Current recommendations for the anticoagulation of patients with atrial fibrillation

Atrial fibrillation (AF) is the most commonly encountered cardiac rhythm disorder and is strongly associated with stroke. The risk of stroke and the benefit of anticoagulant therapy in patients with AF associated with mitral stenosis has been well accepted. Until recently the risk of stroke and the role of anticoagulant therapy in patients with nonrheumatic AF was unclear. Over the past decade studies have shown an approximate fivefold increase in the risk of stroke in patients with nonrheumatic AF. The results of large clinical trials have shown a benefit of treatment with anticoagulants and, to a lesser extent, aspirin for both the primary and secondary prevention of thromboembolic complications. Other than patients with a low risk of thromboembolic complications (primarily young patients without clinical risk factors), current guidelines recommend anticoagulation of most patients with AF. The studies that form the basis for these recommendations and the currently published guidelines are reviewed.

Regional left atrial stasis during atrial fibrillation and flutter: determinants and relation to stroke

OBJECTIVES

This study sought to 1) determine the location of left atrial stasis during atrial arrhythmia; 2) define the degree of stasis associated with significant risk of stroke; and 3) identify clinical or transthoracic echocardiographic data useful for predicting left atrial stasis.

BACKGROUND

Prior studies suggest that stroke during atrial arrhythmia is related to stasis in either the body of the left atrium or the appendage. Recent data indicate that appendage stasis is associated with appendage thrombus formation, but stroke during atrial arrhythmia occurs frequently in the absence of appendage stasis.

METHODS

Blood flow velocity was measured in multiple sites in the body of the left atrium and in the appendage by transesophageal pulsed wave Doppler echocardiography in 89 patients with atrial fibrillation or flutter. Regional velocities were related to the frequency of probable embolic stroke and to clinical and transthoracic echocardiographic variables.

RESULTS

The lowest velocity region was either the posterior left atrium or the appendage. Stroke frequency increased progressively and steeply with velocity < 15 cm/s in either region; this cutoff value had an 87% sensitivity and 40% specificity for stroke. Factors related to stasis were low left atrial ejection fraction, mitral regurgitation < 3+, fibrillation (vs. type I flutter), left ventricular dilation and mitral valve area < 2.0 cm2.

CONCLUSIONS

Posterior left atrial stasis appears to be as important as appendage stasis for the risk of stroke, which increases steeply with lower blood flow velocity in either region. Patients likely to have severe stasis during atrial arrhythmia are those with left ventricular dilation and low atrial ejection fraction accompanying left atrial dilation. Direct measurement of atrial velocity by transesophageal echocardiography appears to be useful for the identification of patients at risk for stroke during atrial arrhythmia.

Influence of aging on left atrial appendage flow velocity patterns in normal subjects

Transesophageal pulsed Doppler echocardiography was performed to examine changes with age in the left atrial appendage flow velocity patterns in 50 normal subjects (15 to 80 years) in sinus rhythm. There was a significant negative correlation between the peak early diastolic forward and backward left atrial appendage flow velocities and age, as well as a significant positive correlation between the peak early diastolic forward left atrial appendage flow velocity and the peak early diastolic transmitral and pulmonary venous flow velocities. Although there was a significant positive correlation between the peak atrial systolic transmitral flow velocity and age, there was a negative correlation between the peak atrial systolic forward and backward left atrial appendage flow velocities and age. There was a positive correlation between both the maximum left atrial diameter and the amplitude of the interatrial septal motion during atrial systole and age. There was a significant negative correlation between the left atrial appendage ejection fraction during atrial systole and age. Left atrial appendage thrombi and spontaneous echo contrast were detected in two subjects with low peak early diastolic and atrial systolic left atrial appendage flow velocities. In conclusion, both peak early diastolic and atrial systolic left atrial appendage flow velocities decreased with age. A decrease in the peak atrial systolic flow velocity appeared to be an important sign of left atrial appendage thrombus formation even in normal elderly subjects in sinus rhythm.

Transesophageal echocardiographic assessment of embolic sources: intracardiac and extracardiac masses and aortic degenerative disease

The increased sensitivity of transesophageal echocardiography (TEE) makes it complementary and, in many cases, superior to transthoracic echocardiography in the detection of various sources of embolism. These sources include intracardiac thrombus, tumors, spontaneous echocardiographic contrast, and others. TEE is also helpful as an adjunctive test for the diagnosis of pulmonary embolisms.

Transesophageal echocardiography in patients with focal cerebral ischemia of unknown cause

BACKGROUND AND PURPOSE

Identification of cardioembolic stroke is often limited by the difficulties involved in the detection of thrombi or the risk factors for thrombus formation. Patients in sinus rhythm with nondiagnostic transthoracic echocardiogram (TTE) and without carotid artery stenosis represent a subset in whom diagnostic recommendations are lacking. The aim of this study was to determine the value of transesophageal echocardiography (TEE) for diagnosis and therapy in this population.

METHODS

Thirty patients with the characteristics described above were studied prospectively with the use of blood analysis, TTE, TEE, and Holter monitoring (in patients with atrial thrombus).

RESULTS

TTE was abnormal in 16 of 30 patients, but no embolic source was identified. TEE disclosed left atrial appendage thrombus in 3 of 30 patients, atrial septal aneurysm in 2 of 30 patients, patent foramen ovale in 7 of 30 patients, and aortic plaques in 19 of 30 patients. The Tee resulted in a change of therapy in 3 of the 30 patients studied.

CONCLUSION

This study demonstrates that TEE is a helpful diagnostic tool in delineating the risk of cardioembolic stroke and demonstrates significant pathology even in a subset of patients deemed to be at low risk. This additional new information led to a substantial change in therapy in 3 of 30 patients.

Early assessment by transesophageal echocardiography of left atrial appendage function after percutaneous mitral commissurotomy

Thirty-seven consecutively admitted patients with severe mitral stenosis underwent percutaneous mitral commissurotomy with a transthoracic and biplane or multiplane transesophageal echocardiographic examination before and between 24 and 48 hours after percutaneous mitral commissurotomy. Thirty patients (81%) were in sinus rhythm and 7 were in atrial fibrillation. Left atrial appendage (LAA) function was evaluated in both the transverse and the longitudinal planes by planimetry and pulsed Doppler echocardiographic interrogation at the LAA outlet. Percutaneous mitral commissurotomy resulted in a twofold increase in mitral valve area, and no severe mitral regurgitation occurred. With use of the planimetry method, there was no significant improvement in LAA ejection fraction, except in the transverse plane for patients in sinus rhythm (p = 0.03). With use of Doppler method, 3 distinct flow patterns were observed before the procedure: a "sinus pattern" in patients in sinus rhythm, and a "fibrillatory pattern" (n = 3) or a "no-flow pattern" (n = 4) in patients in atrial fibrillation. After commissurotomy, there was a marked increase in LAA peak Doppler velocity (+62%) and in LAA velocity time integral (+31%). Of the 4 patients in atrial fibrillation with a no-flow pattern, 2 had recovery of a typical effective fibrillatory flow pattern after the procedure. The increase in peak Doppler velocity after commissurotomy was related to the decrease or regression in left atrial spontaneous echo contrast, and correlated with the increase in mitral valve area, the decrease in tranmitral pressure gradient, and the increase in cardiac index; improvement in valve function after successful percutaneous mitral commissurotomy is associated with early improvement in LAA function.

Influence of left atrial function on Doppler transmitral and pulmonary venous flow patterns in dilated and hypertrophic cardiomyopathy: evaluation of left atrial appendage function by transesophageal echocardiography

Information regarding the relation of left atrial (LA) function to transmitral and pulmonary venous (PV) flow is limited. Using transesophageal echocardiography, we analyzed this relation in 23 patients with dilated cardiomyopathy (DCM) and 25 patients with hypertrophic cardiomyopathy (HCM). Left atrial appendage (LAA) function was assessed as a substitute for overall LA function. Transmitral and PV flow-velocity variables, the LAA emptying flow velocity (LAA-A), and the LAA ejection fraction (LAA-EF) were determined. Each patient group was divided into two subgroups with a normal ( < 15 mm Hg) or elevated ( > or = 15 mm Hg) mean pulmonary wedge pressure (PWP). Transmitral and PV flow patterns as well as LA function were similar in the two subgroups with a normal PWP (11 patients with DCM and 14 patients with HCM). For the subgroups with an elevated PWP, however, the peak velocity ratio of the early filling wave (E) to atrial contraction wave (A) was higher in DCM patients (n = 12) than in HCM patients (n = 11) (2.1 +/- 0.7 vs 1.3 +/- 0.2; p < 0.01). This difference mostly resulted from a lower A velocity in the DCM group than in the HCM group (30 +/- 10 cm/sec vs 43 +/- 7 cm/sec; p < 0.05). In addition, the reverse flow velocity at atrial contraction in the PV was lower in the DCM group than in the HCM group (19 +/- 8 cm/sec vs 37 +/- 8 cm/sec; p < 0.01). These findings were associated with poorer LA systolic function in the DCM group (LAA-A, 35 +/- 13 cm/sec vs 60 +/- 11 cm/sec; LAA-EF, 37% +/- 12% vs 55% +/- 15%, p < 0.05, respectively). Our data suggest that a restrictive transmitral flow pattern develops more easily in DCM than in HCM because LA dysfunction is present in DCM, and that LA contractility plays an important role in determining the atrial contraction wave of transmitral and PV flows with elevated LA pressure.

Effects of percutaneous mitral valvuloplasty on left atrial appendage flow velocity

This study shows an increase in LAA flow after PTMV in both normal sinus rhythm and atrial fibrillation. These results suggest that relief of mitral stenosis may not only confer hemodynamic benefits for the improvement of symptoms but also have a favorable influence on future thromboembolism.

Multiplane transesophageal echocardiographic assessment of left atrial appendage anatomy and function

Anatomic indexes of the LAA are dependent on the plane in which the appendage is viewed. Greater LAA neck width and cross-sectional area are observed at 135 degrees than at 45 degrees or 90 degrees, consistent with the characteristic 3-dimensional ungular shape of this structure. Appendage ejection and inflow velocity measurements are independent of the imaging plane.

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.

Clinical significance of fibrillatory wave amplitude. A clue to left atrial appendage function in nonrheumatic atrial fibrillation

Seventy-eight patients with chronic nonrheumatic atrial fibrillation were studied by transesophageal echocardiography with regard to the left atrial appendage function and its relation to the coarseness of atrial fibrillation on electrocardiogram. These 78 patients (52 men and 26 women; mean age, 66 +/- 10 years; range, 40 to 94 years) were classified into two groups according to the presence of coarse (group 1, n = 46; those with the greatest amplitude of fibrillatory wave in lead V1 > or = 1 mm) or fine (group 2, n = 32; those without the coarse fibrillatory wave in lead V1) atrial fibrillation on a standard 12-lead electrocardiogram within 1 month of echocardiographic studies. There were no significant differences in age, sex, mean duration of atrial fibrillation, left ventricular end-diastolic dimension, left ventricular end-systolic dimension, left ventricular ejection fraction, and left atrial dimension between the two groups. In group 1, however, the left atrial appendage ejection fraction (24.4 +/- 14.2% vs 32.6 +/- 14.8%; p < 0.05) and the peak emptying velocity (21.7 +/- 12.6 cm/s vs 30.4 +/- 14.3 cm/s; p < 0.01) were lower than those in group 2. There were higher incidences of left atrial appendage spontaneous echo contrast (26/46 vs 7/32; p < 0.005) and thrombus (8/46 vs 0/32; p < 0.05) in group 1 patients. The coarse atrial fibrillation revealed a sensitivity of 80.0%, a specificity of 58.1%, a positive predictive value of 60.9%, and a negative predictive value of 78.1% for the presence of left atrial appendage spontaneous echo contrast and/or thrombus formation. In conclusion, in patients with coarse nonrheumatic atrial fibrillation, the left atrial appendage function is usually poor and the incidence of spontaneous echo contrast and thrombus formation appears to be higher in these patients.

Value of transoesophageal echocardiography before DC cardioversion in patients with atrial fibrillation: assessment of embolic risk

Images

Transesophageal echocardiographic detection of atrial thrombi in patients with nonfibrillation atrial tachyarrhythmias and congenital heart disease

OBJECTIVES

We hypothesized an association between atrial thrombi and nonfibrillation atrial tachyarrhythmias in patients with congenital heart disease.

BACKGROUND

We observed a fatal thromboembolus after direct current cardioversion in an adolescent with atrial flutter and repaired tetralogy of Fallot.

METHODS

Using transesophageal echocardiography, we prospectively studied 19 consecutive patients with congenital heart disease with nonfibrillation atrial tachyarrhythmia (atrial flutter in 18, primary atrial tachycardia in 1) undergoing electrophysiologic procedures (median age 19.6 years, range 7.0 to 53.8; 11 male, 8 female). Transthoracic echocardiograms were available for 17 patients.

RESULTS

All transesophageal examinations were performed without incident. No atrial thrombi were detected in 11 patients who subsequently had uncomplicated direct current cardioversion. Eight solitary atrial thrombi were detected (incidence 42%). Six thrombi were located in the right atrium (Fontan repair in four patients, Ebstein's malformation repair in two), and two were noted in the left atrium (congenital hypertrophic cardiomyopathy and atrial septal defect repair in one patient each). Transthoracic echocardiograms were available in seven of eight patients with thrombus detected by transesophageal echocardiography, with only one study conclusive for an atrial thrombus. Cardioversion was deferred in six of eight patients with thrombus, and anticoagulation therapy was initiated. Uncomplicated electrophysiologic procedures were conducted in two patients at the time of detection of right atrial thrombus (atrioventricular node ablation in one patient, direct current cardioversion in the other).

CONCLUSIONS

Prothrombin conditions exist in patients with congenital heart disease with nonfibrillation atrial tachyarrhythmias, as indicated by a significant incidence of transesophageally detected atrial thrombi. The need for prophylactic anticoagulation and the safety of pharmacologic or direct current cardioversion are issues that remain unresolved.