Echocardiography Transesofageal Atrial

Fig. 3. (A) Images showing pectinate muscle morphology on transesphageal echocardiography (TEE). Note their identical echo-reflectivity pattern compared the left atrial appendage (LAA) wall. (B) Views of LAA containing thrombi in patients with atrial fibrillation (AF). Note the presence of spontaneous echocontrast. (C) Views of LAA containing thrombi (arrows) in a patient with AF, visualized in both subcostal view (top panels) and on TEE (bottom panels). Spontaneous echo contrast was also seen in bottom panels. (D) The fold of tissue separating the LAA from the left upper pulmonary vein—the so-called "warfarin ridge" (curved arrows)—owing to false-positive diagnosis of thrombi within the LAA. (Please see companion DVD for corresponding video.)

Table 3

TEE Imaging of Left Atrial Appendage: Thrombi and Anatomical Structures i Artifacts

Index

Thrombi

Artifact

Pectinate muscles

Location

Often at tip of LAA and Acoustic shadowing near always confined to LAA lumen (see Fig. 3B)

Motion with respect to LAA and heart movement

Echoreflectivity pattern compared to LAA walls

Anatomical morphology

Left atrial spontaneous echo contrast

Different

Varied

Often present

"warfarin ridge" or anatomical fold separating LAA and LUPV; reverberations are common, but are x2 object distance from transducer (see Fig. 3C)

Confined to the body of the LAA (see Figs. 2 and 3A)

Relatively independent Fully concordant

Reflectance artifacts Acoustic shadowing Reverberations Consistent with object or structure giving rise to artifact No relationship

Fully concordant

Identical

Follows normal muscle anatomical orientation

No relationship

Coumadin Ridge Echocardiography
Fig. 4. The varied appearance of normal left atrial appearances on transesphageal echocardiography. Normal left atrial appendage morphology can be broadly described as unilobe, bilobed, or multilobed. Note the small pericardial effusion in A.

Fig. 5. Color flow Doppler and pulsed wave Doppler examination of the normal left atrial appendage. The normal appendage actively contracts in most individuals as seen on TEE (A,B) or at surgery. This contributes to the complex quadriphasic pattern seen on pulsed Doppler examination.

Table 4

Transesophageal Echocardiography Findings in Atrial Fibrillation

Transesophageal Echocardiography

Fig. 5. Color flow Doppler and pulsed wave Doppler examination of the normal left atrial appendage. The normal appendage actively contracts in most individuals as seen on TEE (A,B) or at surgery. This contributes to the complex quadriphasic pattern seen on pulsed Doppler examination.

Finding

Spontaneous contrast in left atrium or left atrial appendage

Left atrial appendage thrombus

Attenuated left atrial appendage flow velocities Right atrial appendage thrombus cardiovascular hemodynamics) and an expansion chamber for the left atrium—is incomplete.

Blood flow into and out of the LAA exhibits a complex quadriphasic pattern on spectral Doppler echocardiography (Fig. 5). This pattern reflects left atrial hemodynamics as well as contraction and relaxation patterns of the LAA itself. Normal inflow and outflow LAA velocities in healthy adults are 46 ± 17 cm/s and 46 ± 18 cm/s, respectively. Patterns of flow categorized as type I (sinus rhythm), type II (flutter), type III (fibrillatory),

Significance

Spontaneous echo contrast is thought to increase the risk of thromboembolism.

The most common location of occult thrombus in patients with AF. Thrombus must be distinguished from pectinate muscles that traverse the atrial appendage.

Flow velocities less that 20 cm/s in and out of the LAA is suggestive of stagnant flow.

Not visualized by transthoracic echocardiography, thrombus can be present in right atrial appendage.

type IV (absent) have been described. Normal right artrial appendage ejection velocity is 40 ± 16 cm/s.

EXAMINATION OF THE LAA BY TEE: CONSIDERATIONS

Transesphageal echocardiography, systematically conducted, is an excellent tool for complete visualization of the LAA. It has a high sensitivity for detecting LAA thrombi (Table 4), but this is observer dependent.

TEE probe m

left atrial .appendage

Fig. 6. A systematic examination of the complex left atrial appendage is imperative to "rule out" thrombus. A recommended schema is shown (see Chapter 23).

TEE evaluation of the left atrial appendage involves omni rotation from 0 through 180°, with additional counterclockwise (to the left) rotation of the entire probe between 60 and 90°, and again between 110 and 130° (Fig. 6; see Chapter 23). These serve as a guide, with the final positioning guided by optimal visualization of examined structure during each individual study.

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