This approach starts the TEE study with the probe in a neutral position facing anteriorly, in the mid esophageal position, with a multiplane angle of 0–10°. This produces the mid esophageal four chamber view (ME 4 Ch), which is the TEE equivalent of a standard transthoracic apical four chamber view (Figs. 4.5d and 4.6). Since it is readily recognizable, this view can be used for orientation, thereby serving as the “home base” view for the examination. The ME 4 Ch also serves to identify the base to apex orientation of the heart: levocardia (apex to the left), mesocardia (apex midline), and dextrocardia (apex to the right). Because of the esophageal location for TEE, it can be difficult to ascertain the exact position of the heart in the thorax, but in many cases the base to apex orientation corresponds with the cardiac position [9]. It is important to verify the right/left orientation of the image display and confirm this with rotation of the probe to the right and left; an incorrect setting can complicate the examination, for example by making a patient with levocardia appear to have dextrocardia. Once this view is obtained and the examiner oriented, image settings can be optimized, and the study commences. If the examiner becomes disoriented by movement of the probe to an unfamiliar location, and/or by visualization of unfamiliar structures, the TEE probe can be returned to this “home base” position for reorientation.

The TEE study should begin with an evaluation of visceroatrial situs. This is an important and often overlooked part of the TEE examination for CHD. Visceral and atrial situs are almost always concordant [12], so atrial situs evaluation can be used. Atrial situs is either solitus, inversus, or ambiguous. In situs solitus (normal), the morphologic right atrium (RA) is located to the right of the morphologic left atrium (LA). In situs inversus, there is left-right reversal of the two, and in situs ambiguous (heterotaxy) there is atrial isomerism. By TEE, atrial situs can be determined by several methods. The characteristic features of the atrial appendages serve to distinguish the morphologic RA and LA. The right atrial appendage is typically triangular and broad based, while the left atrial appendage is long and tubular, with a narrow base [8]. In cases of atrial isomerism (heterotaxy, or situs ambiguous), two atrial appendages of the same morphology will usually be seen, presenting as mirror images of each other. Atrial appendage morphology can be readily identified by TEE [25]; the individual appendages can be seen using a combination of mid esophageal views including the mid esophageal bicaval, four and two chamber views (described below). Another important atrial structure, the atrial septum, can also help to establish atrial situs. The atrial septum is comprised of two individual components: the thicker septum secundum (comprised of superior and inferior limbic bands, or limbus), and the thinner septum primum, also known as the valve of the foramen ovale. The septum secundum forms the right atrial surface of the atrial septum, and the septum primum forms the left atrial surface. Therefore in normal atrial situs (solitus), the septum secundum should be located to the right of septum primum; the reverse holds true with atrial situs inversus (the atrial septum is often very deficient in situs ambiguous). When an atrial septum is present, its two components are readily visualized by several mid esophageal TEE views, as will be discussed below.

Atrial situs can also be established by visualization of the suprahepatic portion of inferior vena cava (IVC) and coronary sinus (CS) drainage. These two structures, when present, usually drain into the morphologic RA [26, 27]. Given the postero-inferior position of both structures, the best method to image these is by using a lower esophageal/transgastric window. Therefore from the “home base” (ME 4 Ch) position, the TEE probe is advanced into the stomach and anteflexed, using a multiplane angle of approximately 0° and slight rightward turning of the probe. The hepatic veins (HVs) can be visualized, as well as IVC. The probe is slowly withdrawn, and the HVs will be seen to drain into the IVC in the view that we will refer to as the lower esophageal situs short axis view (LE Situs SAX, Figs. 4.5p and 4.7a). In the same probe location, rotating the multiplane angle to 80–100° and turning the probe rightward (clockwise) visualizes the lengthwise extent of the IVC as it courses through the liver in the lower esophageal IVC long axis view (LE IVC LAX, Figs. 4.5q and 4.7b). This view is useful to distinguish the IVC from prominent HVs, which in some views can mimic the appearance of the IVC. The length of the Eustachian valve can be seen in this view. Rotating back to a multiplane angle of 0°, the probe is withdrawn further (continuing anteflexion to maintain contact with the stomach wall and esophagus), and the IVC can then be seen entering into the right atrium (Fig. 4.8a). Video 4.1 demonstrates this short sweep using nearly orthogonal multiplane angles between 0° and 90°. At this point, or with a small amount of probe withdrawal and retroflexion, the CS can be seen entering into the RA (Fig. 4.8b). Eustachian valve tissue is often seen at the mouth of the IVC, sometimes in continuity with the Thebesian valve of the coronary sinus. The diameter of the coronary sinus opening into the RA is often quite small, except in the presence of a left superior vena cava (LSVC) draining into the CS. The CS is located posteriorly and inferiorly in the heart, and therefore best visualized in its long axis from the lower esophageal window (LE Situs SAX) or the ME 4 Ch view, using a multiplane angle of 0°. Retroflexion of the probe sometimes enables the entire length of the CS to be seen. When the CS is dilated, its margins might not be as well defined, and sometimes a large CS can be confused for a large primum or secundum atrial septal defect. However the CS is more posterior and inferior than either of these defects. A dilated CS is mainly seen when an LSVC is present and drains to the CS; however it can be seen in other conditions as well. A lengthwise view of the dilated CS is best displayed with a multiplane angle of 0–10° (Fig. 4.9).

Once the TEE probe is back in the mid esophageal position, further evaluation of systemic and pulmonary venous return can be undertaken. To visualize a right-sided superior vena cava (the normal position for this vessel in situs solitus, abbreviated as SVC in this chapter), the probe is withdrawn further using slight anteflexion and turning to the right, with a multiplane angle of 0–10° (Fig. 4.10). The entrance of the SVC to the right atrium can be seen in cross section. With further probe withdrawal, more superior portions of the SVC can be seen although this area is not consistently visualized in all patients. Returning to right atrial level, rotation of the multiplane angle to 80–100° yields a sagittal view known as the mid esophageal bicaval view (ME Bicaval, Figs. 4.5k and 4.11, Video 4.2), showing the SVC and IVC entrances to the RA as well as the right atrial appendage. If an LSVC is present, it can also be visualized at this level by rotating the probe leftward (counterclockwise), while maintaining a multiplane angle of 80–100°. This provides a lengthwise, long axis view of the LSVC (Fig. 4.12, Video 4.3). Keeping the probe in the same position and rotating the multiplane angle to 0–10° produces a cross-sectional, short axis view of the LSVC. In both long and short axis views, the LSVC can sometimes be visualized quite superiorly, at the level of the upper esophagus. From this position, by advancing the TEE probe from the upper to mid esophageal position, a superior to inferior sweep of the LSVC can be performed as it descends to its insertion into the dilated CS (Video 4.3). It should be remembered that a LSVC, when present, generally drains through a dilated CS to the RA. However, occasionally it can return directly to the LA, and in these instances the CS will usually not be dilated.

Evaluation of pulmonary venous drainage is one of the strengths of TEE. The close proximity of the LA and pulmonary veins to the esophagus not only provides superior imaging, but also an excellent Doppler color flow signal and favorable angles for spectral Doppler analysis. It is often helpful to utilize color flow mapping to aid assessment of the pulmonary veins. However, lowering of the Nyquist limit (to 30–60 cm/s) is sometimes necessary to visualize an optimal color flow signal.

The individual right and left pulmonary veins can be separately assessed by TEE, although slightly different views and techniques are required for each side [28, 29]. The right pulmonary veins are best evaluated using the ME 4 Ch view, turning the TEE probe to the right to visualize the lateral border of the RA. Advancing the probe and turning to the right enables visualization of right lower pulmonary vein, which takes a more horizontal course on the display (Fig. 4.13a, Video 4.4). With slow withdrawal and slight turning of the probe to the left, the right upper (and sometimes right middle) vein can be readily seen; these veins take a more vertical course on the display as they enter the RA (Fig. 4.13b, Video 4.4). The left pulmonary veins have a slightly different drainage pattern. There are generally two left pulmonary veins (upper and lower), and their sites of return to the LA are usually very close together (or even the same site). The left pulmonary veins can be identified by the ME 4 Ch view, with a multiplane angle of 0–10° and leftward (counterclockwise) turning of the probe. With these settings, slight advancing and withdrawing of the probe is necessary to visualize the individual pulmonary veins. Like the right pulmonary veins, the left lower pulmonary vein has a slightly more horizontal course on the display, and the left upper vein takes a more vertical course (Fig. 4.14a, b, Video 4.4). Both the right and left pulmonary veins can also be visualized from an orthogonal, sagittal (longitudinal) view, effectively a ME Bicaval view with the probe multiplane angle anywhere between 50° and 100°. With this type of evaluation, it is best to visualize first the LA and then rotate the probe rightward or leftward (clockwise/counterclockwise) to visualize the pulmonary veins on either side (Fig. 4.15a, b). These views provide an excellent display of the individual lobar veins as they enter the LA.

It is important to remember that, due to the frequency of anomalous pulmonary venous drainage anomalies seen with CHD, pulmonary venous drainage cannot be relied upon to determine atrial situs. Abnormalities of pulmonary venous drainage are discussed in Chap.​ 6.

The atria and atrial septum are best visualized from the lower and mid esophageal views. A combination of sweeps is generally used. The first sweep begins in the lower esophagus, with a multiplane angle of 0° and a view of the mouth of the IVC entrance to the right atrium. The probe is gradually withdrawn so that the CS and inferior limbic band of atrial septum secundum come into view. Any defects in the posterior atrial septum can be visualized. With further probe withdrawal to the mid esophagus, both atria are well seen, as well as the thin atrial septum primum, and with slightly more rightward rotation, the right atrial appendage (Fig. 4.16a, Video 4.5). As the probe is withdrawn further, superior limbic band of septum secundum becomes visible, as well as the entrance of the SVC into the RA (Fig. 4.16b, Videos 4.5 and 4.6). The right pulmonary veins can be shown returning to the LA (as described above), along with their relationship to the atrial septum. From here, leftward probe rotation and slight probe anteflexion, as well as variation of the multiplane angle between 0° and 60°, will display the left atrial appendage (with its typical finger-like shape) just anterior to the left upper pulmonary vein (Fig. 4.17, Video 4.7).

An orthogonal, sagittal sweep is then performed by setting the multiplane angle to 80–90° and obtaining the ME Bicaval view. The SVC and IVC entrances to the RA, the posterior LA, as well as the right atrial appendage, are well seen (Fig. 4.11, Video 4.5). Rightward turning of the probe visualizes the right pulmonary veins (as noted above); slow leftward turning of the probe back to the ME Bicaval view visualizes the return of these veins back to the LA. The atrial septum is also very well shown with this sweep (Figs. 4.11 and 4.18, Videos 4.2 and 4.5). A patent foramen ovale, when present, is usually seen as a small flap in the atrial septum between its two components of septum secundum and septum primum. Atrial shunting can be confirmed by color flow Doppler (Fig. 4.19, Video 4.8). With further leftward turning of the probe, the remainder of atrial septum (including posterior rim) is visualized, and eventually the entire LA is displayed. A cross section of the CS is then visualized inferiorly. With even more leftward turning, the left atrial appendage and left pulmonary veins come into view (as described above).

If the atrial septum appears intact but atrial shunting is still suspected, a contrast injection can be performed through a peripheral or central vein, using agitated saline [30–32]. Contrast injection can often uncover small, occult right to left atrial level communications. Video 4.9a shows no right to left shunt atrial level shunt, Video 4.9b shows an occult right to left atrial shunt. However, it should be remembered that even with contrast injection, some atrial communications with potential for shunting could still go undetected [33, 34]. In older patients in whom TEE is performed under conscious sedation, provocative maneuvers such as a Valsalva maneuver [30] or coughing [31, 35] have been recommended in conjunction with contrast injection. In patients who are intubated, a simulated Valsalva maneuver can be performed by manually inflating the lungs with positive inspiratory pressure to about 25 mmHg for 10 s [36], maintaining inflation while injecting contrast, and then allowing the lungs to deflate as contrast is seen filling the heart.

Abnormalities of the atria and atrial septum are very well visualized by TEE. For this reason, TEE is widely used to evaluate atrial septal defects (including during transcatheter closure), atrial septal aneurysms, atrial masses and atrial/left atrial appendage thrombi. These applications will be discussed in subsequent chapters of this textbook.

Evaluation of the atrioventricular (AV) junction represents a key aspect of segmental analysis. Because the atrial and ventricular segments are independent of each other, different combinations can occur in the connection between the atria and ventricles [5, 12]. Normally, the RA empties into the morphologic right ventricle (RV) and LA into the morphologic left ventricle (LV), and this is termed AV concordance. However, when the RA empties into LV and LA into RV, there is AV discordance—as seen in congenitally corrected transposition of the great arteries (CCTGA). With two good-sized AV valves and ventricles, the general rule is that the AV valves arise from (and are associated with) their ventricle of entry, not the atrium of exit [37, 38]. Thus the AV valve associated with the morphologic LV is generally the mitral valve, and with the morphologic RV, the tricuspid valve. However, abnormalities of AV connection can occur that cause deviations from this rule, including override or straddling of one AV valve into another chamber, and connection of both AV valves to one ventricle (double inlet ventricle). In addition, other abnormalities can also occur such as absence of an AV valve (tricuspid/mitral atresia), and a common AV valve (AV septal or canal defect) [5, 8, 37]. When evaluating CHD, it is important for the TEE examiner to be mindful of these different possibilities. Nonetheless, the evaluation of the AV connections can be distilled into several important components. The first is, of course, correct morphologic identification of the individual atria (discussed above) and ventricles (discussed below) [8]. Once this is established, details of the AV connections can be determined, including: AV valve identification and number (one vs. two), how the atria and ventricles are connected, any possible override/straddling of the AV valves, and whether AV valve stenosis and/or insufficiency is present. For this type of evaluation, TEE generally provides excellent information.