**4. Assessment of aorta**

The ascending aorta is exposed to various surgical procedures such as arterial cannulation, cross clamping, root cannula insertion and aortotomy, which is potentially responsible for intraoperative stroke and dissection. While the aorta is assessed for calcification or atheromatous changes in preoperative CT in most cases, TEE or direct echo facilitates a surgeon's ability to exactly locate these pathologies intraoperatively.

TEE assessment is beneficial in minimizing interruptions in the surgical procedure. The aorta is visualized with TEE in midesophageal ascending aorta long- or short-axis view. Although the distal portion of ascending aorta used for cannulation has been deemed to be a blind zone, this can be minimized by two tips. One is the *look-up method* (Fig. 3a,b). Instead of withdrawing the probe to visualize the distal portion, the probe is rather advanced and anteflexion is applied. Improved visualization is obtained through the left atrium and right pulmonary artery as an acoustic window. Another is the *xPlane mode* (Fig. 3c,d). In the

Intraoperative Imaging in Aortic Valve Surgery as a Safety Net 7

Unfavorable events related to aortic valve surgeries mainly take place in the ostium and/or

The ostium of the right coronary artery is found in the right coronary sinus (Fig. 4a,b). Although only a few centimeters of right coronary artery can be visualized due to the large distance from the transducer, the posterior descending artery can be visualized in the

The left coronary ostium is visualized in the left sinus of Valsalva by rotating the TEE probe counterclockwise from the midesophageal aortic valve short- or long-axis view (Fig. 4c,d).

Fig. 4. Visualization of coronary arteries. Left top: diagram showing visualization of coronary arteries. The right coronary artery (RCA) is depicted in midesophageal ascending aorta (AAO) short- and long-axis view (a,b). c,d: The left main truncus (LMT) to the division to left anterior descending (LAD) and left circumflex arteries (LCX) is shown. Left bottom: method of visualizing the distal portion of LCX. e: LAD flow, f: LCX in the atrioventricular groove. AV: aortic valve, CS: coronary sinus, PA: pulmonary artery, RA: right atrium, RV: right ventricle Further rotation visualizes the division of the left main truncus to left anterior descending artery and left circumflex artery. A few centimeters of left anterior descending artery is often visualized. The distal portion of the left circumflex artery is visualized in the left posterior atrioventricular groove in the 90° to 120° scanning plane (Fig. 4e,f) (Ender et al., 2010;

3D TEE provides unique information of the coronary ostium (Fig. 5). This perspective view

is helpful for recognizing the distance of the coronary orifice from the annulus.

the proximal portion of the coronary arteries, which can be visualized with TEE.

posterior interventricular groove in the transgastric mid-short-axis view.

**5.1 Visualization of the coronary arteries** 

Karthik et al., 2007).

midesophageal ascending aorta long-axis view with the probe tip anteflexed, the orthogonal scanning plane is tilted upward. Not only is the distal portion of ascending aorta seen, but the aortic arch is often visualized through the left atrium and left pulmonary artery as an acoustic window. From the upper esophageal arch long- and short-axis views, the ascending aorta can be visualized by tilting the orthogonal scanning plane downward.

Fig. 3. Tips for visualizing the distal portion of ascending aorta (AAO). In the look-up method, the probe is rather advanced from the midesophageal ascending aorta long-axis view (a), and anteflexed. b: The arch is visualized via the left atrium (LA) and pulmonary artery (PA). In xPlane mode, the scanning plane is tilted upward (c). d: The arch is visualized through the LA and left PA

The ascending aorta is assessed for calcification and atheromatous plaque. The former is depicted as a strong echo accompanied by an acoustic shadow. When the aorta is severely calcified, it may be necessary to change the perfusion routes to the axillary artery or femoral artery. In the former, pathologies in the arch branches are checked (Orihashi, 2000). When femoral arterial perfusion is chosen, the atheromatous lesion in the descending aorta should be assessed. If the calcified aorta is clamped, it is checked for a new dissection immediately following declamping to minimize a delay in recognition and treatment.
