Three-dimensional echocardiography of left atrial appendage thrombus

A systematic review on the use of ultrasound enhancing agents with transesophageal echocardiography to assess the left atrial appendage prior to cardioversion

BACKGROUND

Assessment of the left atrium and atrial appendage (LAA) for thrombus by transesophageal echocardiography (TEE) may be suboptimal due to difficult imaging windows and ultrasound artifacts. The present study analyzed the benefit of using ultrasound enhancing agents (UEAs) with TEE to improve diagnostic accuracy and image quality.

METHODS

A systematic review of studies published through December 2020 was performed, and included investigations comparing the number of cases deemed indeterminate for visualization of LAA thrombi on TEE pre- versus post-UEAs prior to cardioversion for atrial fibrillation or flutter (AF). Study results were pooled where the number of indeterminate cases by conventional TEE were re-classified as thrombus present, indeterminate, or thrombus excluded following administration of UEAs.

RESULTS

Three studies with a total of 399 patients were identified. Of these, 83 (26%) participants met the inclusion criteria. The mean age of the study population from the three studies was 66 ± 12 years, 29% were female, and prevalence of congestive heart failure or neurologic events was 22% and 5%, respectively. Use of UEAs with TEE re-classified 66% (55/83) of cases initially deemed to be indeterminate for LAA thrombus on conventional TEE. Thrombus was present in 13% (11/83) and excluded in 53% (44/83) of cases; 34% (28/83) of cases remained indeterminate on TEE post-UEAs. There were no complications reported with the administration of UEAs.

CONCLUSION

Adjunctive use of UEAs with TEE can facilitate the diagnosis or exclusion of LAA thrombus, and improve the procedural confidence and cost-efficiency of cardioversion for AF.

Diagnosis of a bilobed left atrial appendage and pectinate muscles mimicking thrombi on real-time 3-dimensional transesophageal echocardiography

OBJECTIVE

Transesophageal echocardiography (TEE)-guided cardioversion is an established strategy for managing atrial arrhythmias and is commonly used as an alternative to the conventional approach of administering several weeks of anticoagulation before cardioversion. However, the safety of this approach depends on the exclusion of left atrial appendage (LAA) thrombi with a high level of diagnostic confidence. The objective of this case series is to explore the use of real-time 3-dimensional (RT3D) TEE in the precardioversion evaluation of patients with complex anatomy in their LAAs.

METHODS

We used RT3D TEE to further assess the LAAs of 3 patients being evaluated for cardioversion who had inconclusive 2-dimensional (2D) TEE studies because of complex anatomic variants of the LAA. We imaged the LAA using the 3D zoom mode and rotated this image to view the LAA en face from the perspective of its ostium. Further cropping was performed as needed.

RESULTS

In all 3 patients, the additional views of the appendage obtained by RT3D TEE were decisive in excluding contraindications to cardioversion. The unique en face view of the LAA acquired with 3D TEE, which was previously unobtainable using 2D TEE, was particularly useful. In 1 patient, a bilobed LAA mimicked a thrombus. In 2 other patients, prominent pectinate muscles masqueraded as thrombi.

CONCLUSIONS

Three-dimensional TEE is valuable for the precardioversion evaluation of patients with complex anatomic variants of the LAA.

Real-time 3-dimensional echocardiography in the operating room

Real-time 3-dimensional transesophageal echocardiography (RT-3D-TEE) represents a novel clinical and intuitively educational perioperative cardiovascular imaging modality. The development of RT-3D-TEE allows for live 3D imaging as it circumvents most of the disadvantages of reconstructive 3D methods. RT-3D-TEE will likely revolutionize perioperative assessment of complex 3D structures, such as the mitral valve (MV), as it provides important mechanistic insights into functional and ischemic mitral regurgitation. The MV is particularly suited to live RT-3D-TEE assessment because of the complex interrelationships among the valve, chordae, papillary muscles, and myocardial walls. The 3D en face view of the MV is in accordance with the surgical view and allows to illustrate the unique saddle shape of the MV annulus and to define and localize mitral leaflet lesions in MV prolapse, endocarditis, or congenital MV abnormalities, all potentially important in guiding surgical repair. RT-3D-TEE will soon be integrated into routine perioperative practice. Its unique ability of real-time acquisition, online rendering and cropping capabilities, accurate identification of the precise pathology and location of cardiac disease, together with its ability to promptly quantify 3D data sets using built-in software, will likely help in transitioning this modality into standard of care.

Preablation assessment for the left atrium: comparison of ECG-gated cardiac CT with echocardiography

RATIONALE AND OBJECTIVES

Evaluate the role of two-dimensional echocardiography and electrocardiographically (ECG)-gated contrast-enhanced multislice computed tomographic (MSCT) cardiac imaging to assess cardiac anatomy, specifically pulmonary venous anatomy and left atrial thrombus, in a selected group of patients before catheter-based atrial fibrillation ablation.

MATERIALS AND METHODS

Left atrial anatomy and associated findings in 34 consecutive patients scheduled for electrophysiologic testing who underwent both echocardiography and ECG-gated 16-slice MSCT cardiac imaging were retrospectively compared. Results from two-dimensional transthoracic echocardiography (TTE), cardiac MSCT, electrophysiologic study (EPS), and transesophageal echocardiography (TEE) (when performed) were taken from the official medical record without prior knowledge of this study when interpretation was rendered for clinical use. Electronic record review included: presence of left atrial thrombus (defined as constant filling defect on at least two echocardiographic views or filling defect on computed tomography) and location, pulmonary venous anatomy, and other cardiac, mediastinal, or pulmonary abnormalities.

RESULTS

Left atrial thrombus was identified by cardiac MSCT alone in five patients (15%). Pulmonary venous variants were identified with cardiac MSCT in two patients (6%). Both MSCT and echocardiography were normal in 17 subjects (79%). Echocardiography was better at identifying associated valvular abnormalities that were seen in 10 patients (29%). Cardiac MSCT angiography alone identified other cardiac and noncardiac abnormalities, including suspicious pulmonary malignancy, mediastinal adenopathy, and coronary stenosis in 15 patients (44%).

CONCLUSIONS

Echocardiography and cardiac MSCT angiography often provide complimentary findings during the preprocedural evaluation for patients with atrial fibrillation requiring ablation. Cardiac MSCT may provide significant additional information about the left atrium, mediastinum, coronary circulation, and visualized lung fields. Based on this study, we would advise that patients considered for radiofrequency ablation for uncontrolled right atrial fibrillation have both echocardiography and ECG-gated contrast-enhanced cardiac MSCT performed as part of the preprocedure evaluation.