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TEE is often requested before electrical cardioversion or catheter ablation for atrial fibrillation to evaluate the left atrial appendage for the presence of thrombus. Adequate visualization of the atrial appendage requires at least two orthogonal views, using a high-frequency (5 MHz or higher) transducer and with the image zoomed to show the appendage anatomy. This case shows normal views of the left atrial appendage in a patient undergoing coronary artery bypass grafting surgery.
In a patient undergoing cardiopulmonary bypass, baseline echocardiographic images were obtained before cannulation of the inferior vena cava via the right atrium.
This 71-year-old woman presented for aortic valve replacement because of severe aortic insufficiency.
Small valve strands that microscopically are fibroelastic tissue are normal components of the aortic and mitral valve that increase in frequency with age. These small strands, often called Lambl’s excrescence, appear as small, linear mobile echoes that are most often attached to the upstream side of the valve (ventricular side of the aortic and atrial side of the mitral valve). However, they are also seen attached to the nodules of Arantius at the tip of the valve cusps, on the aortic side of the valve, as in this case. The clinical importance of valve strands is unclear, with some studies suggesting an association with stroke but other data suggesting that these are an incidental finding associated with age but without clinical consequences.
Leitman M, Tyomkin V, Peleg E, et al: Clinical significance and prevalence of valvular strands during routine echo examinations, Eur Heart J Cardiovasc Imaging 15(11):1226–1230, 2014.
Jaffe W, Figueredo VM: An example of Lambl’s excrescences by transesophageal echocardiogram: a commonly misinterpreted lesion, Echocardiography 24(10):1086–1089, 2007.
This 42-year-old woman was diagnosed with rheumatic heart disease as a child and at the age of 16 had an open mitral valvotomy via thoracotomy. She had been relatively well, but recently became more symptomatic, and was found to have severe mitral stenosis She was referred for mitral valve replacement with a concurrent maze procedure to treat atrial fibrillation.
Patients with atrial fibrillation are at risk of systemic embolic events due to thrombus formation in the fibrillating left atrium. Most left atrial thrombi occur in the atrial appendage, which is not well visualized on transthoracic imaging. The sensitivity of transthoracic echocardiography for detection of left atrial thrombus is only about 50%. TEE provides high-resolution images of the left atrium and, with an experienced operator, has a sensitivity and specificity of nearly 100% for detection of atrial thrombi.
Imaging of the left atrial appendage should be performed in at least two orthogonal views, typically at 0 and 90 degrees, using a high-frequency transducer and a zoom high-resolution imaging mode. The use of biplane imaging, supplemented by 3D imaging or 2D imaging with minor changes in angulation and rotation from this image plane, are useful approaches to distinguish normal appendage trabeculations, which move with and connect with the atrial wall, from thrombi, which often protrude and have independent motion. Less often, thrombi occur in the body of the atrium, so that careful examination in multiple image planes of the entire atrium, including the atrial septal region, is needed.
Prutkin J, Akoum N: The role of echocardiography in patients with atrial fibrillation and flutter. In Otto CM, editor: The practice of clinical echocardiography, ed 5, Philadelphia, 2016, Elsevier.
Yamamoto M, Seo Y, Kawamatsu N, et al: Complex left atrial appendage morphology and left atrial appendage thrombus formation in patients with atrial fibrillation, Circ Cardiovasc Imaging 7(2):337–343, 2014.
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