Atrial fibrillation (AF) is the most common rhythm abnormality that is encountered in clinical practice. Echocardiography plays a critical role in the initial evaluation of these patients and in their ongoing management. Transesophageal echocardiography has emerged as an important imaging test in these patients. By virtue of its ability to assess for the presence of atrial thrombus, TEE now plays a pivotal role in the management of patients with atrial fibrillation and atrial flutter by screening for the presence of thrombus prior to cardioversion or ablation. In addition, new options for the prevention of thromboembolic events, such as the left atrial occluder device and the LARIAT procedure, employ TEE during the procedure to guide device placement. In this chapter, Dr. Grimm and his colleagues will explore the use of echocardiography in several of these clinical situations, including the assessment of the patient with atrial fibrillation and risk stratification for thromboembolic events, TEE-guided cardioversion, and intraprocedural TEE during LAA occluder device placement.
SECTION 1: ECHOCARDIOGRAPHY IN ATRIAL DYSRHYTHMIAS: ASSESSMENT OF A PATIENT WITH ATRIAL FIBRILLATION/RISK STRATIFICATION FOR THROMBOEMBOLIC EVENTS
CLINICAL CASE PRESENTATION
A 62-year-old man presented with lower extremity edema, shortness of breath, and atrial fibrillation. He had been seen in the past for coronary artery disease that was manifest by severe ischemic cardiomyopathy following an anterior myocardial infarction (MI) and a history of atrial fibrillation (AF). He had undergone coronary artery bypass surgery, mitral valve repair, pulmonary vein isolation (PVI), and stapling of left atrial appendage (LAA). His preoperative ejection fraction (EF) was 15%. Postoperatively, AF redeveloped, and he underwent radiofrequency ablation therapy (RFA) for AF. This procedure was complicated by high-grade atrioventricular (AV) block, and the following day, he underwent placement of a biventricular-pacing ICD. His EF substantially improved to 35%. He then developed gastrointestinal bleeding, which necessitated discontinuation of anticoagulation. Physical exam was unremarkable except for edema and an irregular rhythm. Prior to a planned cardioversion (CV) and in order to facilitate CV, the patient underwent TEE to assess for LA thrombus. Thrombus was identified, and the cardioversion was postponed (Figures 10-1-1, 10-1-2, 10-1-3, 10-1-4, 10-1-5, 10-1-6). After 3 months of anticoagulant therapy, TEE was repeated and the thrombus resolved (Figure 10-1-7). He subsequently underwent CV and has done well.
Two-dimensional TEE image at 73° in the mid-esophagus, showing the left atrial appendage LAA. This image shows thrombus attached near the apex of the LAA. The thrombus size was measured at 1.3 x 0.7 cm. The LAA is best visualized from midesophageal position. It is a complex anatomic structure and is multilobed in up to 80% of the general population. The presence of left atrial (LA) or LAA thrombus may preclude CV. The presence of LA and LAA -thrombus is associated with a significantly increased risk of stroke. Following 3 weeks of therapeutic anticoagulation prior to, ...